110
Dielectric Barrier Discharge (DBD) & Dielectric Barrier Discharge (DBD) & Progress in Large Progress in Large-Scale Ozone Generation Scale Ozone Generation d l l i l l i Progress in Large Progress in Large Scale Ozone Generation Scale Ozone Generation 3 rd rd Complex Plasma Summer Institute Complex Plasma Summer Institute Jose L Lopez PhD Jose L Lopez PhD Jose L. Lopez, PhD Jose L. Lopez, PhD Seton Hall University Seton Hall University Department of Physics Department of Physics South Orange, New Jersey (USA) South Orange, New Jersey (USA)

Dielectric Barrier Discharge (DBD) & Progress in Large ...bonitz/si12/talks/august_8/lopez_si12.pdf · Dielectric Barrier Discharge (DBD) & Progress in Large-Scale Ozone Generation

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Dielectric Barrier Discharge (DBD) amp Dielectric Barrier Discharge (DBD) amp Progress in LargeProgress in Large--Scale Ozone GenerationScale Ozone Generation

dd l l il l i

Progress in LargeProgress in Large Scale Ozone GenerationScale Ozone Generation

33rdrd Complex Plasma Summer InstituteComplex Plasma Summer Institute

Jose L Lopez PhDJose L Lopez PhDJose L Lopez PhDJose L Lopez PhD

Seton Hall UniversitySeton Hall UniversitySeto a U e s tySeto a U e s tyDepartment of PhysicsDepartment of Physics

South Orange New Jersey (USA)South Orange New Jersey (USA)

New Jersey New Jersey ndashndash Home of Seton HallHome of Seton Hall

New Jersey ndash The birth place of Plasma Science

Irving Langmuir (1881 ndash 1957) Nobel Laureate 1932Nobel Laureate 1932Birth of Plasma Science

BirthplaceBirthplace HobokenHoboken NewNew JerseyJersey

Irving Langmuir was one of the first scientists to work on plasmas and the first to refer to this 4th state of

tt l b th imatter as plasmas because their similarity to blood plasma

Irving Langmuir

Plasma Lighting Technology

Thomas EdisonIncandescent Light Bulb

Fluorescent Lamps Compact fluorescent blub

Daniel McFarlan Moore

BirthplaceBirthplace ofof thethe FluorescentFluorescent LightLight BulbBulb EdisonEdison (Menlo(Menlo Park)Park) WestWest OrangeOrange NJNJ

Plasma Enhanced Technology

A small section of amemory chip

Straight holes like these canbe etched with plasmasmemory chip be etched with plasmas

BirthplaceBirthplace ofof solidsolid--statestate microelectronicsmicroelectronicsBellBell LaboratoriesLaboratories MurrayMurray HillHill NJNJ

Microchip fabrication with plasmas

The US Department of Energyrsquos Princeton Plasma Physics Laboratory (PPPL) is acollaborative national center for plasma and fusion science Its primary mission is tocollaborative national center for plasma and fusion science Its primary mission is todevelop the scientific understanding and the key innovations which will lead to anattractive fusion energy source Associated missions include conducting world-classresearch along the broad frontier of plasma science and technology and providing thehighest quality of scientific education

National Spherical Torus Experiment (NSTX)

Atmospheric Cold PlasmasErich Kunhardt amp Kurt Becker

An Atmospheric Pressure Plasma Generated with a

(Courtesy of K Becker)

Capillary-Plasma-Electrode Discharge

Two Types of plasmas

bull High‐temperature plasmas (Hot Plasmas)g p p ( )Tiasymp Te ge107 Keg fusion plasmas

T asymp T asymp T le 2 x 104 KTi asymp Te asymp Tg le 2 x 104 Keg arc plasma at normal pressure

bull Low‐temperature plasmas (Cold Plasmas)Ti asymp Tg asymp 300 KT ltlt T le 105 KTi ltlt Te le 105 Keg low‐pressure glow discharge

high‐pressure cold plasma

Hot vs Cold PlasmasHot vs Cold Plasmas

LowLow--Temperature (ldquoColdrdquo) PlasmasTemperature (ldquoColdrdquo) Plasmas[Non[Non--equilibrium Nonequilibrium Non--Thermal]Thermal][Non[Non equilibrium Nonequilibrium Non Thermal]Thermal]

How do we make plasmasHow do we make plasmas

Supply Energyeg Heat transfer radiation electric powerhellip

For many plasma applicationsFor many plasma applications an Electric Field is applied to a gaseous environment

Plasma or Gaseous DischargePlasma or Gaseous Discharge

LowLow--Pressure Glow Discharge PlasmasPressure Glow Discharge Plasmas

Plasmas are easier to be generated at low pressures

Low pressure plasmas (1 T f T )

at low pressures

are well understood

are used extensively nowadays

(1 mTorr ~ a few Torr)

are used extensively nowadays (eg in semiconductor industry for computer chips manufacturing)

However to generate low pressure plasmas

vacuum chambers + + = expensive vacuum pumps

pressure monitoring and pressure control devices

+ + =Generate Plasmas at Atmospheric PressureGenerate Plasmas at Atmospheric Pressure

What happens at air pressureWhat happens at air pressure

bull No vacuum is involvedDiffi l d ibull Difficult to generate and sustain

bull Run into some challenges such as glow toarc transition ndash Non controllable

Arc Discharge thermal plasma-Itrsquos hot and detrimental-Gas temperature can reach as high as 2x104 KGas temperature can reach as high as 2x10 K- Low voltage drop at cathode- High cathode current density

High Pressure Microplasmas

Stabilization of high-pressure plasmas ldquopd scalingrdquo ldquoprdquo uarr soplasmas pd scaling p uarr so ldquodrdquo darr to keep breakdown voltage low and minimize instabilities after breakdown -

MicroplasmasDimension a few millimeterDimension a few millimeter down to and below 100 m

Paschen Breakdown CurveH H i 60 100Human Hair 60 ndash 100 m

How do we solve this problemHow do we solve this problem

Transient (pulsed) plasmas In atmospheric plasmas for efficient gas heating atleast 100-1000 collisions are necessary Thus if the plasma duration is shorterleast 100 1000 collisions are necessary Thus if the plasma duration is shorterthan 10-6 ndash 10-5 s gas heating is limited Of course for practical purposes suchplasma has to be operated in a repetitive mode eg in trains of microsecondpulses with millisecond intervals

Micro-confinement Gas heating occurs in the plasma volume and the energy iscarried away by thermal diffusionconvection to the outside If the plasma has asmall volume and a relatively large surface gas heating is limited

Dielectric Barrier Discharges These plasmas are typically created betweenmetal plates which are covered by a thin layer of dielectric or highly resistivematerial The dielectric layer plays an important role in suppressing the currentthe cathodeanode layer is charged by incoming positive ionselectrons whichreduces the electric field and hinders charge transport towards the electrodeDBD also has a large surface-to-volume ratio which promotes diffusion lossesand maintains a low gas temperatureand maintains a low gas temperature

Advantages of Microplasmas Advantages of Microplasmas

bull Low-cost of implementationpbull System flexibilitybull Atmospheric pressure operationbull High densities and high reaction ratesbull High densities and high reaction ratesbull Fast and efficient processesbull Easy to generate and sustain for a variety of gas mixtures

Gl lik d diffbull Glow-like and diffusebull Non-equilibrium (Te gt Tg) to thermalbull Unique chemistryq y

hellip a new realm of plasma sciencehellip a new realm of plasma science

What can we do with microplasmasWhat can we do with microplasmas

Material Synthesis Plasma display Surface Treatment Lighting

OzoneOzone generation for water cleaning

Bio-applicationMaterial processing Dental application

and Many morehellip

Some High Pressure microplasma reactors Some High Pressure microplasma reactors

Dielectric Barrier Discharge (DBD)Dielectric Barrier Discharge (DBD)

Hi h V l

HighVoltage

High VoltageElectrode

ACGenerator

DielectricBarrier

Generator

G

Microplasmas

GroundElectrode

Faradayrsquos Dielectric CapacitorsFaradayrsquos Dielectric Capacitors

Faradays Dielectric Capacitor (circa 1837)

Michael Faraday (1781 ndash 1867) Capacitance INCREASED

Historical Ozone Tube of W Siemens (1857)Historical Ozone Tube of W Siemens (1857)

Werner v SiemensP d frsquo A l d Ch i d Ph ik 102 66 (1857)Poggendorfrsquos Annalen der Chemie und Physik 102 66 (1857)

ldquoOzone Production in an Atmospheric-PressureDielectric Barrier Dischargerdquo

Dielectric Barrier Discharge

Dielectric Barrier DischargeDielectric - Barrier Discharge ConfigurationsHigh

VoltageAC

Generator

High VoltageElectrode

DielectricBarrier

DielectricBarrier

High VoltageElectrode

Discharge

DischargeGeneratorGround

Electrode

Electrode

GroundElectrode

Discharge

H E Wagner R Brandenburg et al lsquoThe barrier discharge basic properties and applications toHE Wagner R Brandenburg et al The barrier discharge basic properties and applications tosurface treatmentrsquo Vacuum 71 p417-436 (2003)

Typical operational conditions of barrier discharges Typical operational conditions of barrier discharges

Electric field strength E of first breakdown asymp150 Td (p = 1bar T=300 K)

Voltage Vpp 3ndash20 kV

Repetition frequency f 50 Hzndash30 kHz

Pressure p 1ndash3 bar

Gap distance g 02ndash5mm

Dielectric material thickness d 05ndash2mm

Relative dielectric permittivity r 5ndash10 (glass)

B Eliasson and U Kogelschatz IEEE Transactions Plasma Science Vol 19 Issue 6 1063-1077 (1991)B Eliasson and U Kogelschatz IEEE Transactions Plasma Science Vol 19 Issue 6 1063-1077 (1991)

Single and double DBD

Single dielectric Double dielectric

Role of the Dielectric (Insulator)

Th di l t i i th k f thThe dielectric is the key for the properfunctioning of the discharge

Serves two functions

1 Limits the amount of charge transportedby a single microplasma

2 Distributes the microplasmas over theentire electrode surface area

Equivalent Circuit of a Microdischarge

Microdischarge Activity and U-Q Lissajous Figure

B Eliasson and U Kogelschatz IEEE Transactions Plasma Science Vol 19 Issue 6 1063-1077 (1991)

Fundamental Operation of the Dielectric Barrier DischargeFundamental Operation of the Dielectric Barrier Discharge

bull Many of relevant plasma processes that areof importance to achieving our goal occuron time scales that allow us to study themon time scales that allow us to study them

bull Optical emission spectroscopic studies willallow us to determine the temporal andspatial development of important plasmaspatial development of important plasmaspecies such as radicals (OH NO variousoxygen radicals) with high time resolution(less than 10 ns) and a spatial resolution onthe scale of mm in the plasma volumepfollowing pulsed plasma excitation

Time scale of the relevant processes of the DBD

HE Wagner R Brandenburg et al lsquoThe barrier discharge basic properties and applications tosurface treatmentrsquo Vacuum 71 417-436 (2003)

Fundamental Operation of the DBDFundamental Operation of the DBD

Electron DensityTemporal Development (ns)

y

Outer Contour Linen = 1010 cm-3ne = 1010 cm 3

Inner Contour Linene = 1014 cm-3

Streamer Propagation in 1 bar AirAA Kulikovsky IEEE Trans Plasma Sci 25 439-446 (1997)

Numerical Results of Microdischarge Formationin Dielectric Barrier Discharges

Starting Phase of a Microdischarge (1 bar 20 CO2 80 H2)

E0=34 kVcm1010 cm-3

1010 cm-3 ne=1012 cm-3

1mm10 cm

ne=108 cm-3

An electron avalanche propagates towards the anode

Reverse propagationtowards the cathodepropagates towards the anode towards the cathode

Numerical Results of Microdischarge Formationin Dielectric Barrier Discharges

Cathode Layer Formation

E0=34 kVcm1010 cm-39 3 0

1mm

1010 cm-3

10 cmne=109 cm-31014

10131014

1013

10 cm1012

Just before the peak of the total current

Peak currentof the total current

Numerical Results of Microdischarge Formationin Dielectric Barrier Discharges

Local Field Collapse in Area Defined by Surface Discharge

ne=109cm-3 ne=1014 cm-3

Gap

Principals of DBD MicroplasmasPrincipals of DBD MicroplasmasPrincipals of DBD MicroplasmasPrincipals of DBD Microplasmas

C C-- - --- - - CG

CD

-- - - CG

CD

Principals of DBD MicroplasmasPrincipals of DBD MicroplasmasPrincipals of DBD MicroplasmasPrincipals of DBD Microplasmas

Dielectric Barrier Discharge (DBD)Dielectric Barrier Discharge (DBD)Electric Field

B kdBreakdown

Electrons amp Ions Discharge Physics

Excited SpeciesPlasma Chemistry

Chemical Reactions

OzoneGeneration

SurfaceTreatment

PollutionControl

ExcimerFormation CO2 Lasers Hydrogenation

of CO2

Excimer Lamps Plasma Displays

How A Plasma Display Works

How A Plasma Display Work

Plasma Display TelevisionsPlasma Display Televisions

Ozone Generator

3 O 2 O

Dielectric Barrier Discharge

3 O2 2 O3

OO22 OO33++OO22Ondash ndashO3O2

O2O2

Ondash ndash

endash O2Ondash ndash O2endash

O3

O3O2O2 O2

HeatHeatHeatHeat

Properties of Ozone (O3)

T i t i f f Tri-atomic form of oxygen

Most powerful commercial oxidizing agent

Unstable - must be generated and used onsite

Limited solubility in water but more so than oxygenLimited solubility in water but more so than oxygen

Leaves a dissolved residual which ultimately converts back to oxygenconverts back to oxygen

Discharge Tubes in Ozone GeneratorsDischarge Tubes in Ozone Generators

Traditional

Ozone Generator

with Glass Tubes

Generation of OzoneGeneration of Ozone

Generation of OzoneAdvantages of Enamel Dielectrics

Proven Patented Designbull Simplicity

Si l Di l i Cbull Single Dielectric Componentndash Reduced number of Dielectrics

bull Safety ndash Lower operating voltage

(lt 4000 V)bull Reliabilty

ndash Fused Dielectrics ensure continuous production

bull Lowest Power Consumption Operational Savingsndash Operational Savings

Modern Ozone GeneratorModern Ozone Generator

Ozonia Advanced Technology Ozone GeneratorOzone Generator

Generation of OzoneGeneration of Ozone

Generation of Ozone

Power Supply UnitPower Supply Unit

IGBT Inverter CircuitMain Circuit Breaker

HV 480 Volts60 Hz3 Phase Supply

C I

450KVAPow er to

GeneratorFILTER

CONVERTER INVERTERTRANSFORMER

C I450KVA Power Stage

CONTACTOR

bull Latest in Power Semiconductor Technology Modular Design

bull Utilizes IGBTrsquos (Insulated Gate Bi‐Polar Transistors) Converter and Inverter Components

Ozone Water Treatment

B bbl Diff iB bbl Diff iBubble DiffusionBubble Diffusion

Easy to use

Low energy usage Low energy usage

Mass transfer efficiencies to gt 90

Ozone Process Flow DiagramOzone Process Flow DiagramVent to

Atmosphere

O OOxygen

Off-Gas Blower

Ozone Destruct Unit

10 12

O3O2

LOX

10-12 O3

Ozone Generators

Ozone Contact ChamberLOX T k Generators Chamber

VaporizersLOX Tank

Municipal Ozone Installations

Ozonia Installations Ozone Plant Size [lbday] Start-Up DateKey Ozonia Installations (Partial List)

Los Angeles CA 10000 1986Fairfax VA ndash Corbalis 9000 2003MWD CA ndash Mills 9 000 2003

Ozonia Installations Ozone Plant Size [lbday] Start Up Date

MWD CA Mills 9000 2003Fairfax Co VA ndash Griffith 9000 2004MWD CA ndash Jensen 18750 2005Indianapolis IN ndash Belmont AWT 12000 2007I di li IN 12 000 2007Indianapolis IN ndash Southport AWT 12000 2007MWD CA ndash Diemer 13400 2008MWD CA ndash Weymouth 13400 2009

Ozonia North America - Potable Water SummaryTotal Number of Installations 90Total Installed Production gt 265000 lbsdayTotal Installed Production 265000 lbsday

Revision -B

Ozone Water TreatmentOzone Water Treatment

MWD Mills WTP - California

3 3 000 lbsda of o one3 3 000 lbsda of o one3 x 3000 lbsday of ozone3 x 3000 lbsday of ozone

Ozone Water TreatmentOzone Water TreatmentOzone Ozone -- How it worksHow it works

OxidantOxidant DisinfectantDisinfectant

bullbull Breaks double carbon Breaks double carbon bondsbonds

bullbull Kills by cell lysing or Kills by cell lysing or causing the cell wall tocausing the cell wall tobondsbonds

bullbull Creates OHCreates OHbullbull radicals radicals which break higher carbon which break higher carbon

causing the cell wall to causing the cell wall to rupture rupture

bullbull AttacksAttacks allall bacteriabacteriabondsbondsbullbull Increased temp and pH Increased temp and pH

accelerates Oaccelerates O33

Attacks Attacks allall bacteria bacteria virus cysts and spores virus cysts and spores in varying degreesin varying degreesaccelerates Oaccelerates O33

decomposition to OHdecomposition to OHbullbull

Micro-organism DNA

Capsule AdenineAdenine

Cell wall ThymineThymine

CytosineCytosine

GuanineGuanine

NuclearmaterialCellmembrane

material

Typical Bacterium DNA

Microbial Growth at Various Ozone ConcentrationsConcentrations

Growth likely

Growth possibleGrowth possible

NO GROWTH

0004 0008 0012 0016 0020

Ozone concentration (mgl)Ozone concentration (mgl)

Typical Water Treatment UsageTypical Water Treatment Usage

Application O3 mgl Contact timeUltra Pure Water 005 - 025 sec ndash min

Water bottling 04 ndash 10 5 ndash 10 min

Swimming pools ampspas

01 ndash 075 4 minutes

Potable taste amp odor 15 ndash 50 5 ndash 10 mindisinfection

Microfloculation 10 ndash 30 5 ndash 10 min

Lignin amp tammin 3 0 10 0 10 30 minLignin amp tamminremoval

30 ndash 100 10 ndash 30 min

Municipal wastewater 50 ndash 150+ 15 ndash 30 min

Ozone Water TreatmentOzone Water TreatmentOzone Ozone ndashndash Municipal ApplicationsMunicipal Applications

bullbull Taste and OdorTaste and Odor

bullbull Color RemovalColor Removal

bullbull Disinfection Without Trihalomethanes (THMs)Disinfection Without Trihalomethanes (THMs)

bullbull Improved Filtration Efficiency and FlocculationImproved Filtration Efficiency and Flocculation

bullbull Cryptosporidium DeactivationCryptosporidium Deactivation

bullbull Giardia amp Virus InactivationGiardia amp Virus Inactivation

bullbull Oxidation Oxidation -- Organics Fe amp MnOrganics Fe amp Mn

bullbull Wastewater disinfectionWastewater disinfection

bullbull BOD COD and TOC reductionBOD COD and TOC reduction

Applications of Ozone

Wastewater Treatmentbull Disinfection of Secondary and Tertiary Effluentsbull Color Reductionbull Color Reductionbull TOC Oxidation (Industrial)bull Oxidation of Odor Causing Compoundsbull Oxidation of Endocrine Disruptors (EDCrsquos) and p ( )

Pharmaceutically Active Compounds (PACrsquos)

Applications of Ozone

What are Endocrine Disruptors (EDCrsquos) and What are Endocrine Disruptors (EDCrsquos) and Ph ti ll A ti C d (PACrsquo )Ph ti ll A ti C d (PACrsquo )Pharmaceutically Active Compounds (PACrsquos)Pharmaceutically Active Compounds (PACrsquos)

bullbull EDCrsquosEDCrsquos andand PACrsquosPACrsquos areare NaturallyNaturally andand SyntheticSyntheticdd th tth t ff tff t thth b lb l llcompoundscompounds thatthat maymay affectaffect thethe balancebalance oror normalnormal

functionsfunctions inin animalsanimals andand humanshumans

What can EDCrsquos and PACrsquos doWhat can EDCrsquos and PACrsquos do

bullbull Even in very small concentrations these compounds Even in very small concentrations these compounds y py pcan can disruptdisrupt normal bodily functionsnormal bodily functions

bullbull ManMan--made chemicals can trick the bodies endocrine made chemicals can trick the bodies endocrine system system

Applications of Ozone

Examples of Endocrine Disruptors1000rsquos of compounds that may be Investigated as EDCs ndash Some examples are

bullbull Synthetic HormonesSynthetic Hormonesbullbull Naturally Occurring Estrogens Naturally Occurring Estrogens

Health and Beauty AidsHealth and Beauty Aidsbullbull Health and Beauty AidsHealth and Beauty Aidsbullbull SolventsSolventsbullbull PesticidesPesticidesbullbull SurfactantsSurfactantsbullbull PlasticsPlastics

F i idF i idbullbull FungicidesFungicides

Ozone Water TreatmentOzone Water Treatment

Ozone Ozone -- Industrial ApplicationsIndustrial Applications-- Ultrapure Water for Pharmaceutical ApplicationsUltrapure Water for Pharmaceutical Applications

-- Wastewater disinfection color removalWastewater disinfection color removal

-- Soil and Groundwater Remediation Soil and Groundwater Remediation

-- Cooling Tower Water TreatmentCooling Tower Water Treatment

-- Food ProcessingFood Processing

-- Aquaculture AquariumsAquaculture AquariumsAquaculture AquariumsAquaculture Aquariums

-- Beverage ApplicationsBeverage Applications

P l amp P Bl hiP l amp P Bl hi-- Pulp amp Paper BleachingPulp amp Paper Bleaching

High Purity OzonationHigh Purity Ozonation

Microchip manufacturingMicrochip manufacturing

What are the current issues in large-scale gozone generationg

Experimental Setup

Front view of the two units after the redesign and reworking ofthe gas water and instruments connectionsthe gas water and instruments connections

Experimental Setup

Top view of the twoexperimental unitsexperimental unitsSpectroscope (notshown) is to the left ofthe DBD The units weredifferent with respect todifferent with respect totheir electrodes onehad only the electrodecoated with thedielectric (ldquosingle-dielectric ( single-coatedrdquo) the other onehad the electrode andthe anode coated withthe dielectric (ldquodouble-the dielectric ( double-coatedrdquo)

Basics Generation of OzoneBasics Generation of Ozone

SpectroscopyPlasma

Plasma Absorption SpectroscopyPlasma Absorption Spectroscopy

Infrared Absorption SpectroscopyInfrared Absorption Spectroscopy

IR spectra in pure oxygen (black curve) and at approximately 10wt N2 admixture (red line) N2O5 peaks appear at124 1 d 1 2 11245 cm-1 and at 1725 cm-1

Infrared Absorption SpectroscopyInfrared Absorption Spectroscopy

IR spectra of several methane variations The green curve envelopes all of the methane peaks at 1325 cm-1recorded at smaller methane admixtures Simultaneously the N2O5 peaks disappear as the methane peaks appear

N2O5 FormationN2O5 Formation2 52 5p=2 bara cwt=20degC q=35kWm2 f=1450Hz

45N2O5 AT95

30

35

40

N

2 B

lend

ing

N2O AT95N2O5 IGSN2O IGSN2O5 LGN2O LG

1 5

20

25

nt [p

pmV]

3

wt

05

10

15

NO

x co

nten

005 7 9 11 13 15 17

ozone conc [wt]

Amount of formed N2O5 and N2O as a function of ozone concentration at 3 wt of nitrogen admixture and fori l dvarious electrode arrangements

Plasma Emission SpectroscopyPlasma Emission Spectroscopyp pyp py

Relative Emissions of the Ozonizer plasmaRelative Emissions of the Ozonizer plasma

Region 300- 850 nm from individual (calibrated) regions (smoothed by PeakFit) Single-coated ozone generator Inlet side

3 5E+06

30E+06

35E+06

7 9

20E+06

25E+06

nten

sity

au

2

311 12

10E+06

15E+06

In 4

5

6 8 10

14

15

16

17

00E+00

50E+05

280 300 320 340 360 380 400 420 440 460 480 500 520 540 560 580 600 620 640 660 680 700 720 740 760 780 800 820 840 860

Wavelength nm

1 13

Wavelength nm

Absolute Emission of the DBD PlasmaAbsolute Emission of the DBD Plasma

Intensities in (O2+3 wtN2) plasma

1 20E+04

100E+04

120E+04

600E+03

800E+03

nten

sity

(au

)

200E+03

400E+03

In

O(777)

000E+00200 250 300 350 400 450 500 550 600 650 700 750 800 850

Wavelength nm

Intensities in 3 wtN2+O2 plasmaIntensities in 3 wtN2+O2 plasma

Plasma Chemistry in OzonizersPlasma Chemistry in Ozonizers

Dry Air O2 N2

e - e -

O N2 N O2

O3 NO

O2 N O2

O3

N

3

NO2

O2 O3

NO

N

NO2 O3

N2O

NO3 N

N2O4

NO2

NO2

N2O5

NO3

Primary electron-driven chemical reactions leading to the formation of N2O5 and N2O in a dry air plasma

Plasma emission diagnostics role of N2Plasma emission diagnostics role of N2

Dry Air O2 N2

e - e -

O N2 N O2

O3 NO

O2 N O2

O3

O

N

ON

NO2

O2O3

N

NO N

NO2 O3

N2O

NO3 N

N2O4

NO2

NO2

N2O5

NO3

ONbullWith N2 present ndash less oxygen atoms are formed However the difference in intensity is

very small

Modeling of plasma chemistry incl the NxOy chemistry up to N2O5 for different Oxygen Nitrogen mixtures varying power deposition scenarios

and initial ozone background concentrations (up to 15) previously done

The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation

The role of N2 must be related to its by-products reacting on the surface of the electrodeThe role of N2 must be related to its by-products reacting on the surface of the electrode

The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established

Ab 8 t f O

The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established

Ab 8 t f OAbove 8 wt of O3

1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)

Above 8 wt of O3

1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)case without pampp)

2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of the

case without pampp)

2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of thethem A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface

them A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface

The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation

Three possibilities have to be considered for the oxygen-fedozone generator

Three possibilities have to be considered for the oxygen-fedozone generatorozone generator

bull Excited N2 molecules lead to an increased O2 dissociation in

ozone generator

bull Excited N2 molecules lead to an increased O2 dissociation in2 2such case an increased efficiency is correlated to the N2admixture

2 2such case an increased efficiency is correlated to the N2admixture

bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial

bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial

bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2

bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2g p g 3 pp y 2g p g 3 pp y 2

Effect of methane on ozone efficiency and specific powerEffect of methane on ozone efficiency and specific power

Effect of Methane on Ozone Content in Outlet Gas and on Specific Power Pure O2

13 12

10

11

12

t 8

10

8

9

10

ne c

onte

nt w

t

6

8

ecifi

c po

wer

kW

hlb

5

6

7

Ozo

n

2

4 Spe

400E+00 20E+03 40E+03 60E+03 80E+03 10E+04 12E+04

Methane in feedgas ppm

0

Ozone content in the outlet gas Specif ic pow er of the ozone generatorg p p g

Effects of N2 and CH4Effects of N2 and CH4

Pi t f h t lli N O t tPicture of an amorphous-crystalline N2O5 structurecaptured at the Orlando Skylake water plant in 2006

Plasma Chemistry with CH4 Impurities

OxygenO2 N2

e - e -

CHO N2

NO2

O NO

O2 N O2 O3

NOH

CH4e-

O3 NO

NO2

O2O3NO N

NO2 O

NO2

NO2

N2ONO3

N

O3

NO2

NO

HNO3

N2O4

N2O5

NO2

NO3

N2O5

Effect of methane on the electrode surfaces

a) b)

Inlet Outlet Outlet

) d)

I l t I l t

c) d)

Electrode of the ozone generator afterseveral hours in CH8O2 and up to 2 wt of methane (a b c)

Inlet Inlet

three hours in CH8O2+traces of N2 and up to 1 wt of methane (d) Visible change of discharge character at about 13 length of electrode (a d)

Kinetics of CHx Conversion without N2

conversion by collisions

O2 + CHx 12wt O3 + CO2 +H2O

deposition vaporizationby sputtering

ibl b l 1000 CHreversible process below 1000ppm CH4

Effect of water on electrode surface with N2

Inlet

OutletOutlet

Electrode of the ozone generator after several hours in H OO N

Inlet

Electrode of the ozone generator after several hours in H2OO2N2

Effect of water on electrode surface

Long term effect (800 hrs) of H2OO2N2

Kinetics of CHx Conversion with N2

conversion by collisionsHNO3 formation

O2 + N2 +CHx 12wtO2 + CO2 +H2O + HNO3

deposition vaporizationby sputtering

H2O + HNO3

by sputtering

irreversible process above a N2 threshold () ltlt 1000ppm N2

sticky deposit

p 2 ( ) pp 2 any CH4 concentration (60ppm)

Plasma Chemistry with CH4 ImpuritiesPlasma Chemistry with CH4 Impurities4

bull Formation of NO and NO2 depends on O3 N2 and gas temperature Conclusion N2 admixture is the key factor

SummarySummaryyyThe mechanisms of formed NOx by-products follows the sameThe mechanisms of formed NOx by-products follows the sameprinciples as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentration

principles as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentrationozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)

ozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)g p ( g p )

The conversion of methane to OH and H2O is found to depend on

g p ( g p )

The conversion of methane to OH and H2O is found to depend ondissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)

dissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)discharge gap)discharge gap)

How do you optimize an ozone generatorg

Scientific ApproachScientific ApproachTheoretical Experimental

pppp

c [wt]

f [Hz]

c [wt]

f [Hz]

[kW]UUUβ1

1Cf4αPn

1iiminpeakimin

iiD

q [kWm2]q [kWm2]

150

180

][V]voltagepeakUpeak

[]cylinder perslicesofamountnsliceii

whereth

09 00

30

60

90

120

effic

ienc

y [

][0tdj t bl[F]sliceisdielectricofecapacitancC

[Hz]frequencyf[V]sliceivoltageminimumiUmin

thiD

th

10

28

46

64

82

39

107

176

244 power density

[kWm2]

ozone conc [wt][]CCβ

][0parameteradjustableα

iDiGi

Impact of Power Inductionp

350

400

wer

200

250

300

App

lied

Pow

Arr C 2Arr D +0

Arr E +45Arr F +7

Arr G +3

5 0

100

150

Frac

tion

of

1 2 3 4

ReferenceArr B unstable

Arr C -2

00

50

4Position (1inlet 4outlet)

Experimental Test Rigp g

Experimental Test Rigp g

Outer grounded electrode (left picture) and the dielectric covered inner electrodes (right) d e ect c cove ed e e ect odes ( g t)

Reference (Traditional) Arrangement

Inlet OutletGas flow direction

Optimized Arrangement

Inlet OutletGas flow direction

Intelligent Gap System (IGS)g p y ( )

Molecular Oxygen (O2) Ozone (O3)

O2 O3

yg ( 2) ( 3)

Particle Size SynthesisParticle Size SynthesisByBy--Products Cluster FormationProducts Cluster Formationyy

high diffusion and deposition to surfaces

low diffusion rate good transport

high sedimentation on the structurehigh sedimentation on the structure

Degreacutemont Technologies ndash OzoniaIntelligent Gap SystemIntelligent Gap System

G Vezzuacute JL Lopez A Freilich and K Becker Optimizationof Large-Scale Ozone Generators IEEE Transactions onPlasma Science Vol 37 No 6 p 890-896 (2009)

ConclusionsConclusionsConclusionsConclusionsFundamentals of ozone synthesis in a DBD plasmay p

ndash Highly filamented DBD discharges are best-suitedfor the production of ozone concentrations in therange of 6 to 14 wtrange of 6 to 14 wt

ndash The preferred characteristic of the microdischargesare Townsend-like at reduced electric fields Enaround 190 Townsend

ndash Detrimental side-effects induced by by-productscan be avoided by a proper design of the electrodecan be avoided by a proper design of the electrodearrangement The phenomenon is related to thediffusion rates of formed by-product clusters

ConclusionsConclusionsConclusionsConclusionsBenefits from DBD microplasma tailoring

ndash Reduced power consumption of up to 10 improvement

ndash Increased ozone concentrations of up to 14 now achievable

ndash Improved neutralization and conditioning of detrimental by-products

ndash Reduced system capital and operational cost

New technologies to improve ozone p

generatorg

HV Pulsed Power SwitchingHV Pulsed Power Switching

Microchannel Generation of Ozone

Channel ArrayChannel Array

Microchannel

330 microm 230 microm

Some Cap-DBD Devices Operating in Air

Increase of 60 of

Spacing 225 μmof 60 of plasma

No space

Cap‐DBD ozone generation

bull Ozone concentration is evaluated via Eco S d l UV 100 O A l (0 01Sensors model UV-100 Ozone Analyzer (001 ndash 900 ppm wiht an accuracy of plusmn2)

bull Three reactors 6 tubings 6rdquo with spacings of 0 μm 225 μm and 500 μm running at 3 kV μ μ μ g

SpacingOzone Concentration

3 kV rms 4 kV rms3 kV rms 4 kV rms

0 μm 660 ppm

225 μm 550 ppm

For a device of such small scale these ozone levels are promising

500 μm 380 ppm

J Mahoney W Zhu VS Johnson KH Becker and JL Lopez Electrical and optical emissionmeasurements of a capillary dielectric barrier discharge European Physics Journal D Vol 60 441-447(2010)

QuestionsQuestions

Thank YouFor more informationProf Jose L Lopez PhD

Thank YouFor more informationDepartment of Physics

Telephone (973) 761-9057Email joselopez1shuedu

Website wwwshueduacademicsartsciphysicsWebsite wwwshueduacademicsartsciphysics

Page 2: Dielectric Barrier Discharge (DBD) & Progress in Large ...bonitz/si12/talks/august_8/lopez_si12.pdf · Dielectric Barrier Discharge (DBD) & Progress in Large-Scale Ozone Generation

New Jersey New Jersey ndashndash Home of Seton HallHome of Seton Hall

New Jersey ndash The birth place of Plasma Science

Irving Langmuir (1881 ndash 1957) Nobel Laureate 1932Nobel Laureate 1932Birth of Plasma Science

BirthplaceBirthplace HobokenHoboken NewNew JerseyJersey

Irving Langmuir was one of the first scientists to work on plasmas and the first to refer to this 4th state of

tt l b th imatter as plasmas because their similarity to blood plasma

Irving Langmuir

Plasma Lighting Technology

Thomas EdisonIncandescent Light Bulb

Fluorescent Lamps Compact fluorescent blub

Daniel McFarlan Moore

BirthplaceBirthplace ofof thethe FluorescentFluorescent LightLight BulbBulb EdisonEdison (Menlo(Menlo Park)Park) WestWest OrangeOrange NJNJ

Plasma Enhanced Technology

A small section of amemory chip

Straight holes like these canbe etched with plasmasmemory chip be etched with plasmas

BirthplaceBirthplace ofof solidsolid--statestate microelectronicsmicroelectronicsBellBell LaboratoriesLaboratories MurrayMurray HillHill NJNJ

Microchip fabrication with plasmas

The US Department of Energyrsquos Princeton Plasma Physics Laboratory (PPPL) is acollaborative national center for plasma and fusion science Its primary mission is tocollaborative national center for plasma and fusion science Its primary mission is todevelop the scientific understanding and the key innovations which will lead to anattractive fusion energy source Associated missions include conducting world-classresearch along the broad frontier of plasma science and technology and providing thehighest quality of scientific education

National Spherical Torus Experiment (NSTX)

Atmospheric Cold PlasmasErich Kunhardt amp Kurt Becker

An Atmospheric Pressure Plasma Generated with a

(Courtesy of K Becker)

Capillary-Plasma-Electrode Discharge

Two Types of plasmas

bull High‐temperature plasmas (Hot Plasmas)g p p ( )Tiasymp Te ge107 Keg fusion plasmas

T asymp T asymp T le 2 x 104 KTi asymp Te asymp Tg le 2 x 104 Keg arc plasma at normal pressure

bull Low‐temperature plasmas (Cold Plasmas)Ti asymp Tg asymp 300 KT ltlt T le 105 KTi ltlt Te le 105 Keg low‐pressure glow discharge

high‐pressure cold plasma

Hot vs Cold PlasmasHot vs Cold Plasmas

LowLow--Temperature (ldquoColdrdquo) PlasmasTemperature (ldquoColdrdquo) Plasmas[Non[Non--equilibrium Nonequilibrium Non--Thermal]Thermal][Non[Non equilibrium Nonequilibrium Non Thermal]Thermal]

How do we make plasmasHow do we make plasmas

Supply Energyeg Heat transfer radiation electric powerhellip

For many plasma applicationsFor many plasma applications an Electric Field is applied to a gaseous environment

Plasma or Gaseous DischargePlasma or Gaseous Discharge

LowLow--Pressure Glow Discharge PlasmasPressure Glow Discharge Plasmas

Plasmas are easier to be generated at low pressures

Low pressure plasmas (1 T f T )

at low pressures

are well understood

are used extensively nowadays

(1 mTorr ~ a few Torr)

are used extensively nowadays (eg in semiconductor industry for computer chips manufacturing)

However to generate low pressure plasmas

vacuum chambers + + = expensive vacuum pumps

pressure monitoring and pressure control devices

+ + =Generate Plasmas at Atmospheric PressureGenerate Plasmas at Atmospheric Pressure

What happens at air pressureWhat happens at air pressure

bull No vacuum is involvedDiffi l d ibull Difficult to generate and sustain

bull Run into some challenges such as glow toarc transition ndash Non controllable

Arc Discharge thermal plasma-Itrsquos hot and detrimental-Gas temperature can reach as high as 2x104 KGas temperature can reach as high as 2x10 K- Low voltage drop at cathode- High cathode current density

High Pressure Microplasmas

Stabilization of high-pressure plasmas ldquopd scalingrdquo ldquoprdquo uarr soplasmas pd scaling p uarr so ldquodrdquo darr to keep breakdown voltage low and minimize instabilities after breakdown -

MicroplasmasDimension a few millimeterDimension a few millimeter down to and below 100 m

Paschen Breakdown CurveH H i 60 100Human Hair 60 ndash 100 m

How do we solve this problemHow do we solve this problem

Transient (pulsed) plasmas In atmospheric plasmas for efficient gas heating atleast 100-1000 collisions are necessary Thus if the plasma duration is shorterleast 100 1000 collisions are necessary Thus if the plasma duration is shorterthan 10-6 ndash 10-5 s gas heating is limited Of course for practical purposes suchplasma has to be operated in a repetitive mode eg in trains of microsecondpulses with millisecond intervals

Micro-confinement Gas heating occurs in the plasma volume and the energy iscarried away by thermal diffusionconvection to the outside If the plasma has asmall volume and a relatively large surface gas heating is limited

Dielectric Barrier Discharges These plasmas are typically created betweenmetal plates which are covered by a thin layer of dielectric or highly resistivematerial The dielectric layer plays an important role in suppressing the currentthe cathodeanode layer is charged by incoming positive ionselectrons whichreduces the electric field and hinders charge transport towards the electrodeDBD also has a large surface-to-volume ratio which promotes diffusion lossesand maintains a low gas temperatureand maintains a low gas temperature

Advantages of Microplasmas Advantages of Microplasmas

bull Low-cost of implementationpbull System flexibilitybull Atmospheric pressure operationbull High densities and high reaction ratesbull High densities and high reaction ratesbull Fast and efficient processesbull Easy to generate and sustain for a variety of gas mixtures

Gl lik d diffbull Glow-like and diffusebull Non-equilibrium (Te gt Tg) to thermalbull Unique chemistryq y

hellip a new realm of plasma sciencehellip a new realm of plasma science

What can we do with microplasmasWhat can we do with microplasmas

Material Synthesis Plasma display Surface Treatment Lighting

OzoneOzone generation for water cleaning

Bio-applicationMaterial processing Dental application

and Many morehellip

Some High Pressure microplasma reactors Some High Pressure microplasma reactors

Dielectric Barrier Discharge (DBD)Dielectric Barrier Discharge (DBD)

Hi h V l

HighVoltage

High VoltageElectrode

ACGenerator

DielectricBarrier

Generator

G

Microplasmas

GroundElectrode

Faradayrsquos Dielectric CapacitorsFaradayrsquos Dielectric Capacitors

Faradays Dielectric Capacitor (circa 1837)

Michael Faraday (1781 ndash 1867) Capacitance INCREASED

Historical Ozone Tube of W Siemens (1857)Historical Ozone Tube of W Siemens (1857)

Werner v SiemensP d frsquo A l d Ch i d Ph ik 102 66 (1857)Poggendorfrsquos Annalen der Chemie und Physik 102 66 (1857)

ldquoOzone Production in an Atmospheric-PressureDielectric Barrier Dischargerdquo

Dielectric Barrier Discharge

Dielectric Barrier DischargeDielectric - Barrier Discharge ConfigurationsHigh

VoltageAC

Generator

High VoltageElectrode

DielectricBarrier

DielectricBarrier

High VoltageElectrode

Discharge

DischargeGeneratorGround

Electrode

Electrode

GroundElectrode

Discharge

H E Wagner R Brandenburg et al lsquoThe barrier discharge basic properties and applications toHE Wagner R Brandenburg et al The barrier discharge basic properties and applications tosurface treatmentrsquo Vacuum 71 p417-436 (2003)

Typical operational conditions of barrier discharges Typical operational conditions of barrier discharges

Electric field strength E of first breakdown asymp150 Td (p = 1bar T=300 K)

Voltage Vpp 3ndash20 kV

Repetition frequency f 50 Hzndash30 kHz

Pressure p 1ndash3 bar

Gap distance g 02ndash5mm

Dielectric material thickness d 05ndash2mm

Relative dielectric permittivity r 5ndash10 (glass)

B Eliasson and U Kogelschatz IEEE Transactions Plasma Science Vol 19 Issue 6 1063-1077 (1991)B Eliasson and U Kogelschatz IEEE Transactions Plasma Science Vol 19 Issue 6 1063-1077 (1991)

Single and double DBD

Single dielectric Double dielectric

Role of the Dielectric (Insulator)

Th di l t i i th k f thThe dielectric is the key for the properfunctioning of the discharge

Serves two functions

1 Limits the amount of charge transportedby a single microplasma

2 Distributes the microplasmas over theentire electrode surface area

Equivalent Circuit of a Microdischarge

Microdischarge Activity and U-Q Lissajous Figure

B Eliasson and U Kogelschatz IEEE Transactions Plasma Science Vol 19 Issue 6 1063-1077 (1991)

Fundamental Operation of the Dielectric Barrier DischargeFundamental Operation of the Dielectric Barrier Discharge

bull Many of relevant plasma processes that areof importance to achieving our goal occuron time scales that allow us to study themon time scales that allow us to study them

bull Optical emission spectroscopic studies willallow us to determine the temporal andspatial development of important plasmaspatial development of important plasmaspecies such as radicals (OH NO variousoxygen radicals) with high time resolution(less than 10 ns) and a spatial resolution onthe scale of mm in the plasma volumepfollowing pulsed plasma excitation

Time scale of the relevant processes of the DBD

HE Wagner R Brandenburg et al lsquoThe barrier discharge basic properties and applications tosurface treatmentrsquo Vacuum 71 417-436 (2003)

Fundamental Operation of the DBDFundamental Operation of the DBD

Electron DensityTemporal Development (ns)

y

Outer Contour Linen = 1010 cm-3ne = 1010 cm 3

Inner Contour Linene = 1014 cm-3

Streamer Propagation in 1 bar AirAA Kulikovsky IEEE Trans Plasma Sci 25 439-446 (1997)

Numerical Results of Microdischarge Formationin Dielectric Barrier Discharges

Starting Phase of a Microdischarge (1 bar 20 CO2 80 H2)

E0=34 kVcm1010 cm-3

1010 cm-3 ne=1012 cm-3

1mm10 cm

ne=108 cm-3

An electron avalanche propagates towards the anode

Reverse propagationtowards the cathodepropagates towards the anode towards the cathode

Numerical Results of Microdischarge Formationin Dielectric Barrier Discharges

Cathode Layer Formation

E0=34 kVcm1010 cm-39 3 0

1mm

1010 cm-3

10 cmne=109 cm-31014

10131014

1013

10 cm1012

Just before the peak of the total current

Peak currentof the total current

Numerical Results of Microdischarge Formationin Dielectric Barrier Discharges

Local Field Collapse in Area Defined by Surface Discharge

ne=109cm-3 ne=1014 cm-3

Gap

Principals of DBD MicroplasmasPrincipals of DBD MicroplasmasPrincipals of DBD MicroplasmasPrincipals of DBD Microplasmas

C C-- - --- - - CG

CD

-- - - CG

CD

Principals of DBD MicroplasmasPrincipals of DBD MicroplasmasPrincipals of DBD MicroplasmasPrincipals of DBD Microplasmas

Dielectric Barrier Discharge (DBD)Dielectric Barrier Discharge (DBD)Electric Field

B kdBreakdown

Electrons amp Ions Discharge Physics

Excited SpeciesPlasma Chemistry

Chemical Reactions

OzoneGeneration

SurfaceTreatment

PollutionControl

ExcimerFormation CO2 Lasers Hydrogenation

of CO2

Excimer Lamps Plasma Displays

How A Plasma Display Works

How A Plasma Display Work

Plasma Display TelevisionsPlasma Display Televisions

Ozone Generator

3 O 2 O

Dielectric Barrier Discharge

3 O2 2 O3

OO22 OO33++OO22Ondash ndashO3O2

O2O2

Ondash ndash

endash O2Ondash ndash O2endash

O3

O3O2O2 O2

HeatHeatHeatHeat

Properties of Ozone (O3)

T i t i f f Tri-atomic form of oxygen

Most powerful commercial oxidizing agent

Unstable - must be generated and used onsite

Limited solubility in water but more so than oxygenLimited solubility in water but more so than oxygen

Leaves a dissolved residual which ultimately converts back to oxygenconverts back to oxygen

Discharge Tubes in Ozone GeneratorsDischarge Tubes in Ozone Generators

Traditional

Ozone Generator

with Glass Tubes

Generation of OzoneGeneration of Ozone

Generation of OzoneAdvantages of Enamel Dielectrics

Proven Patented Designbull Simplicity

Si l Di l i Cbull Single Dielectric Componentndash Reduced number of Dielectrics

bull Safety ndash Lower operating voltage

(lt 4000 V)bull Reliabilty

ndash Fused Dielectrics ensure continuous production

bull Lowest Power Consumption Operational Savingsndash Operational Savings

Modern Ozone GeneratorModern Ozone Generator

Ozonia Advanced Technology Ozone GeneratorOzone Generator

Generation of OzoneGeneration of Ozone

Generation of Ozone

Power Supply UnitPower Supply Unit

IGBT Inverter CircuitMain Circuit Breaker

HV 480 Volts60 Hz3 Phase Supply

C I

450KVAPow er to

GeneratorFILTER

CONVERTER INVERTERTRANSFORMER

C I450KVA Power Stage

CONTACTOR

bull Latest in Power Semiconductor Technology Modular Design

bull Utilizes IGBTrsquos (Insulated Gate Bi‐Polar Transistors) Converter and Inverter Components

Ozone Water Treatment

B bbl Diff iB bbl Diff iBubble DiffusionBubble Diffusion

Easy to use

Low energy usage Low energy usage

Mass transfer efficiencies to gt 90

Ozone Process Flow DiagramOzone Process Flow DiagramVent to

Atmosphere

O OOxygen

Off-Gas Blower

Ozone Destruct Unit

10 12

O3O2

LOX

10-12 O3

Ozone Generators

Ozone Contact ChamberLOX T k Generators Chamber

VaporizersLOX Tank

Municipal Ozone Installations

Ozonia Installations Ozone Plant Size [lbday] Start-Up DateKey Ozonia Installations (Partial List)

Los Angeles CA 10000 1986Fairfax VA ndash Corbalis 9000 2003MWD CA ndash Mills 9 000 2003

Ozonia Installations Ozone Plant Size [lbday] Start Up Date

MWD CA Mills 9000 2003Fairfax Co VA ndash Griffith 9000 2004MWD CA ndash Jensen 18750 2005Indianapolis IN ndash Belmont AWT 12000 2007I di li IN 12 000 2007Indianapolis IN ndash Southport AWT 12000 2007MWD CA ndash Diemer 13400 2008MWD CA ndash Weymouth 13400 2009

Ozonia North America - Potable Water SummaryTotal Number of Installations 90Total Installed Production gt 265000 lbsdayTotal Installed Production 265000 lbsday

Revision -B

Ozone Water TreatmentOzone Water Treatment

MWD Mills WTP - California

3 3 000 lbsda of o one3 3 000 lbsda of o one3 x 3000 lbsday of ozone3 x 3000 lbsday of ozone

Ozone Water TreatmentOzone Water TreatmentOzone Ozone -- How it worksHow it works

OxidantOxidant DisinfectantDisinfectant

bullbull Breaks double carbon Breaks double carbon bondsbonds

bullbull Kills by cell lysing or Kills by cell lysing or causing the cell wall tocausing the cell wall tobondsbonds

bullbull Creates OHCreates OHbullbull radicals radicals which break higher carbon which break higher carbon

causing the cell wall to causing the cell wall to rupture rupture

bullbull AttacksAttacks allall bacteriabacteriabondsbondsbullbull Increased temp and pH Increased temp and pH

accelerates Oaccelerates O33

Attacks Attacks allall bacteria bacteria virus cysts and spores virus cysts and spores in varying degreesin varying degreesaccelerates Oaccelerates O33

decomposition to OHdecomposition to OHbullbull

Micro-organism DNA

Capsule AdenineAdenine

Cell wall ThymineThymine

CytosineCytosine

GuanineGuanine

NuclearmaterialCellmembrane

material

Typical Bacterium DNA

Microbial Growth at Various Ozone ConcentrationsConcentrations

Growth likely

Growth possibleGrowth possible

NO GROWTH

0004 0008 0012 0016 0020

Ozone concentration (mgl)Ozone concentration (mgl)

Typical Water Treatment UsageTypical Water Treatment Usage

Application O3 mgl Contact timeUltra Pure Water 005 - 025 sec ndash min

Water bottling 04 ndash 10 5 ndash 10 min

Swimming pools ampspas

01 ndash 075 4 minutes

Potable taste amp odor 15 ndash 50 5 ndash 10 mindisinfection

Microfloculation 10 ndash 30 5 ndash 10 min

Lignin amp tammin 3 0 10 0 10 30 minLignin amp tamminremoval

30 ndash 100 10 ndash 30 min

Municipal wastewater 50 ndash 150+ 15 ndash 30 min

Ozone Water TreatmentOzone Water TreatmentOzone Ozone ndashndash Municipal ApplicationsMunicipal Applications

bullbull Taste and OdorTaste and Odor

bullbull Color RemovalColor Removal

bullbull Disinfection Without Trihalomethanes (THMs)Disinfection Without Trihalomethanes (THMs)

bullbull Improved Filtration Efficiency and FlocculationImproved Filtration Efficiency and Flocculation

bullbull Cryptosporidium DeactivationCryptosporidium Deactivation

bullbull Giardia amp Virus InactivationGiardia amp Virus Inactivation

bullbull Oxidation Oxidation -- Organics Fe amp MnOrganics Fe amp Mn

bullbull Wastewater disinfectionWastewater disinfection

bullbull BOD COD and TOC reductionBOD COD and TOC reduction

Applications of Ozone

Wastewater Treatmentbull Disinfection of Secondary and Tertiary Effluentsbull Color Reductionbull Color Reductionbull TOC Oxidation (Industrial)bull Oxidation of Odor Causing Compoundsbull Oxidation of Endocrine Disruptors (EDCrsquos) and p ( )

Pharmaceutically Active Compounds (PACrsquos)

Applications of Ozone

What are Endocrine Disruptors (EDCrsquos) and What are Endocrine Disruptors (EDCrsquos) and Ph ti ll A ti C d (PACrsquo )Ph ti ll A ti C d (PACrsquo )Pharmaceutically Active Compounds (PACrsquos)Pharmaceutically Active Compounds (PACrsquos)

bullbull EDCrsquosEDCrsquos andand PACrsquosPACrsquos areare NaturallyNaturally andand SyntheticSyntheticdd th tth t ff tff t thth b lb l llcompoundscompounds thatthat maymay affectaffect thethe balancebalance oror normalnormal

functionsfunctions inin animalsanimals andand humanshumans

What can EDCrsquos and PACrsquos doWhat can EDCrsquos and PACrsquos do

bullbull Even in very small concentrations these compounds Even in very small concentrations these compounds y py pcan can disruptdisrupt normal bodily functionsnormal bodily functions

bullbull ManMan--made chemicals can trick the bodies endocrine made chemicals can trick the bodies endocrine system system

Applications of Ozone

Examples of Endocrine Disruptors1000rsquos of compounds that may be Investigated as EDCs ndash Some examples are

bullbull Synthetic HormonesSynthetic Hormonesbullbull Naturally Occurring Estrogens Naturally Occurring Estrogens

Health and Beauty AidsHealth and Beauty Aidsbullbull Health and Beauty AidsHealth and Beauty Aidsbullbull SolventsSolventsbullbull PesticidesPesticidesbullbull SurfactantsSurfactantsbullbull PlasticsPlastics

F i idF i idbullbull FungicidesFungicides

Ozone Water TreatmentOzone Water Treatment

Ozone Ozone -- Industrial ApplicationsIndustrial Applications-- Ultrapure Water for Pharmaceutical ApplicationsUltrapure Water for Pharmaceutical Applications

-- Wastewater disinfection color removalWastewater disinfection color removal

-- Soil and Groundwater Remediation Soil and Groundwater Remediation

-- Cooling Tower Water TreatmentCooling Tower Water Treatment

-- Food ProcessingFood Processing

-- Aquaculture AquariumsAquaculture AquariumsAquaculture AquariumsAquaculture Aquariums

-- Beverage ApplicationsBeverage Applications

P l amp P Bl hiP l amp P Bl hi-- Pulp amp Paper BleachingPulp amp Paper Bleaching

High Purity OzonationHigh Purity Ozonation

Microchip manufacturingMicrochip manufacturing

What are the current issues in large-scale gozone generationg

Experimental Setup

Front view of the two units after the redesign and reworking ofthe gas water and instruments connectionsthe gas water and instruments connections

Experimental Setup

Top view of the twoexperimental unitsexperimental unitsSpectroscope (notshown) is to the left ofthe DBD The units weredifferent with respect todifferent with respect totheir electrodes onehad only the electrodecoated with thedielectric (ldquosingle-dielectric ( single-coatedrdquo) the other onehad the electrode andthe anode coated withthe dielectric (ldquodouble-the dielectric ( double-coatedrdquo)

Basics Generation of OzoneBasics Generation of Ozone

SpectroscopyPlasma

Plasma Absorption SpectroscopyPlasma Absorption Spectroscopy

Infrared Absorption SpectroscopyInfrared Absorption Spectroscopy

IR spectra in pure oxygen (black curve) and at approximately 10wt N2 admixture (red line) N2O5 peaks appear at124 1 d 1 2 11245 cm-1 and at 1725 cm-1

Infrared Absorption SpectroscopyInfrared Absorption Spectroscopy

IR spectra of several methane variations The green curve envelopes all of the methane peaks at 1325 cm-1recorded at smaller methane admixtures Simultaneously the N2O5 peaks disappear as the methane peaks appear

N2O5 FormationN2O5 Formation2 52 5p=2 bara cwt=20degC q=35kWm2 f=1450Hz

45N2O5 AT95

30

35

40

N

2 B

lend

ing

N2O AT95N2O5 IGSN2O IGSN2O5 LGN2O LG

1 5

20

25

nt [p

pmV]

3

wt

05

10

15

NO

x co

nten

005 7 9 11 13 15 17

ozone conc [wt]

Amount of formed N2O5 and N2O as a function of ozone concentration at 3 wt of nitrogen admixture and fori l dvarious electrode arrangements

Plasma Emission SpectroscopyPlasma Emission Spectroscopyp pyp py

Relative Emissions of the Ozonizer plasmaRelative Emissions of the Ozonizer plasma

Region 300- 850 nm from individual (calibrated) regions (smoothed by PeakFit) Single-coated ozone generator Inlet side

3 5E+06

30E+06

35E+06

7 9

20E+06

25E+06

nten

sity

au

2

311 12

10E+06

15E+06

In 4

5

6 8 10

14

15

16

17

00E+00

50E+05

280 300 320 340 360 380 400 420 440 460 480 500 520 540 560 580 600 620 640 660 680 700 720 740 760 780 800 820 840 860

Wavelength nm

1 13

Wavelength nm

Absolute Emission of the DBD PlasmaAbsolute Emission of the DBD Plasma

Intensities in (O2+3 wtN2) plasma

1 20E+04

100E+04

120E+04

600E+03

800E+03

nten

sity

(au

)

200E+03

400E+03

In

O(777)

000E+00200 250 300 350 400 450 500 550 600 650 700 750 800 850

Wavelength nm

Intensities in 3 wtN2+O2 plasmaIntensities in 3 wtN2+O2 plasma

Plasma Chemistry in OzonizersPlasma Chemistry in Ozonizers

Dry Air O2 N2

e - e -

O N2 N O2

O3 NO

O2 N O2

O3

N

3

NO2

O2 O3

NO

N

NO2 O3

N2O

NO3 N

N2O4

NO2

NO2

N2O5

NO3

Primary electron-driven chemical reactions leading to the formation of N2O5 and N2O in a dry air plasma

Plasma emission diagnostics role of N2Plasma emission diagnostics role of N2

Dry Air O2 N2

e - e -

O N2 N O2

O3 NO

O2 N O2

O3

O

N

ON

NO2

O2O3

N

NO N

NO2 O3

N2O

NO3 N

N2O4

NO2

NO2

N2O5

NO3

ONbullWith N2 present ndash less oxygen atoms are formed However the difference in intensity is

very small

Modeling of plasma chemistry incl the NxOy chemistry up to N2O5 for different Oxygen Nitrogen mixtures varying power deposition scenarios

and initial ozone background concentrations (up to 15) previously done

The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation

The role of N2 must be related to its by-products reacting on the surface of the electrodeThe role of N2 must be related to its by-products reacting on the surface of the electrode

The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established

Ab 8 t f O

The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established

Ab 8 t f OAbove 8 wt of O3

1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)

Above 8 wt of O3

1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)case without pampp)

2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of the

case without pampp)

2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of thethem A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface

them A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface

The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation

Three possibilities have to be considered for the oxygen-fedozone generator

Three possibilities have to be considered for the oxygen-fedozone generatorozone generator

bull Excited N2 molecules lead to an increased O2 dissociation in

ozone generator

bull Excited N2 molecules lead to an increased O2 dissociation in2 2such case an increased efficiency is correlated to the N2admixture

2 2such case an increased efficiency is correlated to the N2admixture

bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial

bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial

bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2

bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2g p g 3 pp y 2g p g 3 pp y 2

Effect of methane on ozone efficiency and specific powerEffect of methane on ozone efficiency and specific power

Effect of Methane on Ozone Content in Outlet Gas and on Specific Power Pure O2

13 12

10

11

12

t 8

10

8

9

10

ne c

onte

nt w

t

6

8

ecifi

c po

wer

kW

hlb

5

6

7

Ozo

n

2

4 Spe

400E+00 20E+03 40E+03 60E+03 80E+03 10E+04 12E+04

Methane in feedgas ppm

0

Ozone content in the outlet gas Specif ic pow er of the ozone generatorg p p g

Effects of N2 and CH4Effects of N2 and CH4

Pi t f h t lli N O t tPicture of an amorphous-crystalline N2O5 structurecaptured at the Orlando Skylake water plant in 2006

Plasma Chemistry with CH4 Impurities

OxygenO2 N2

e - e -

CHO N2

NO2

O NO

O2 N O2 O3

NOH

CH4e-

O3 NO

NO2

O2O3NO N

NO2 O

NO2

NO2

N2ONO3

N

O3

NO2

NO

HNO3

N2O4

N2O5

NO2

NO3

N2O5

Effect of methane on the electrode surfaces

a) b)

Inlet Outlet Outlet

) d)

I l t I l t

c) d)

Electrode of the ozone generator afterseveral hours in CH8O2 and up to 2 wt of methane (a b c)

Inlet Inlet

three hours in CH8O2+traces of N2 and up to 1 wt of methane (d) Visible change of discharge character at about 13 length of electrode (a d)

Kinetics of CHx Conversion without N2

conversion by collisions

O2 + CHx 12wt O3 + CO2 +H2O

deposition vaporizationby sputtering

ibl b l 1000 CHreversible process below 1000ppm CH4

Effect of water on electrode surface with N2

Inlet

OutletOutlet

Electrode of the ozone generator after several hours in H OO N

Inlet

Electrode of the ozone generator after several hours in H2OO2N2

Effect of water on electrode surface

Long term effect (800 hrs) of H2OO2N2

Kinetics of CHx Conversion with N2

conversion by collisionsHNO3 formation

O2 + N2 +CHx 12wtO2 + CO2 +H2O + HNO3

deposition vaporizationby sputtering

H2O + HNO3

by sputtering

irreversible process above a N2 threshold () ltlt 1000ppm N2

sticky deposit

p 2 ( ) pp 2 any CH4 concentration (60ppm)

Plasma Chemistry with CH4 ImpuritiesPlasma Chemistry with CH4 Impurities4

bull Formation of NO and NO2 depends on O3 N2 and gas temperature Conclusion N2 admixture is the key factor

SummarySummaryyyThe mechanisms of formed NOx by-products follows the sameThe mechanisms of formed NOx by-products follows the sameprinciples as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentration

principles as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentrationozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)

ozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)g p ( g p )

The conversion of methane to OH and H2O is found to depend on

g p ( g p )

The conversion of methane to OH and H2O is found to depend ondissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)

dissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)discharge gap)discharge gap)

How do you optimize an ozone generatorg

Scientific ApproachScientific ApproachTheoretical Experimental

pppp

c [wt]

f [Hz]

c [wt]

f [Hz]

[kW]UUUβ1

1Cf4αPn

1iiminpeakimin

iiD

q [kWm2]q [kWm2]

150

180

][V]voltagepeakUpeak

[]cylinder perslicesofamountnsliceii

whereth

09 00

30

60

90

120

effic

ienc

y [

][0tdj t bl[F]sliceisdielectricofecapacitancC

[Hz]frequencyf[V]sliceivoltageminimumiUmin

thiD

th

10

28

46

64

82

39

107

176

244 power density

[kWm2]

ozone conc [wt][]CCβ

][0parameteradjustableα

iDiGi

Impact of Power Inductionp

350

400

wer

200

250

300

App

lied

Pow

Arr C 2Arr D +0

Arr E +45Arr F +7

Arr G +3

5 0

100

150

Frac

tion

of

1 2 3 4

ReferenceArr B unstable

Arr C -2

00

50

4Position (1inlet 4outlet)

Experimental Test Rigp g

Experimental Test Rigp g

Outer grounded electrode (left picture) and the dielectric covered inner electrodes (right) d e ect c cove ed e e ect odes ( g t)

Reference (Traditional) Arrangement

Inlet OutletGas flow direction

Optimized Arrangement

Inlet OutletGas flow direction

Intelligent Gap System (IGS)g p y ( )

Molecular Oxygen (O2) Ozone (O3)

O2 O3

yg ( 2) ( 3)

Particle Size SynthesisParticle Size SynthesisByBy--Products Cluster FormationProducts Cluster Formationyy

high diffusion and deposition to surfaces

low diffusion rate good transport

high sedimentation on the structurehigh sedimentation on the structure

Degreacutemont Technologies ndash OzoniaIntelligent Gap SystemIntelligent Gap System

G Vezzuacute JL Lopez A Freilich and K Becker Optimizationof Large-Scale Ozone Generators IEEE Transactions onPlasma Science Vol 37 No 6 p 890-896 (2009)

ConclusionsConclusionsConclusionsConclusionsFundamentals of ozone synthesis in a DBD plasmay p

ndash Highly filamented DBD discharges are best-suitedfor the production of ozone concentrations in therange of 6 to 14 wtrange of 6 to 14 wt

ndash The preferred characteristic of the microdischargesare Townsend-like at reduced electric fields Enaround 190 Townsend

ndash Detrimental side-effects induced by by-productscan be avoided by a proper design of the electrodecan be avoided by a proper design of the electrodearrangement The phenomenon is related to thediffusion rates of formed by-product clusters

ConclusionsConclusionsConclusionsConclusionsBenefits from DBD microplasma tailoring

ndash Reduced power consumption of up to 10 improvement

ndash Increased ozone concentrations of up to 14 now achievable

ndash Improved neutralization and conditioning of detrimental by-products

ndash Reduced system capital and operational cost

New technologies to improve ozone p

generatorg

HV Pulsed Power SwitchingHV Pulsed Power Switching

Microchannel Generation of Ozone

Channel ArrayChannel Array

Microchannel

330 microm 230 microm

Some Cap-DBD Devices Operating in Air

Increase of 60 of

Spacing 225 μmof 60 of plasma

No space

Cap‐DBD ozone generation

bull Ozone concentration is evaluated via Eco S d l UV 100 O A l (0 01Sensors model UV-100 Ozone Analyzer (001 ndash 900 ppm wiht an accuracy of plusmn2)

bull Three reactors 6 tubings 6rdquo with spacings of 0 μm 225 μm and 500 μm running at 3 kV μ μ μ g

SpacingOzone Concentration

3 kV rms 4 kV rms3 kV rms 4 kV rms

0 μm 660 ppm

225 μm 550 ppm

For a device of such small scale these ozone levels are promising

500 μm 380 ppm

J Mahoney W Zhu VS Johnson KH Becker and JL Lopez Electrical and optical emissionmeasurements of a capillary dielectric barrier discharge European Physics Journal D Vol 60 441-447(2010)

QuestionsQuestions

Thank YouFor more informationProf Jose L Lopez PhD

Thank YouFor more informationDepartment of Physics

Telephone (973) 761-9057Email joselopez1shuedu

Website wwwshueduacademicsartsciphysicsWebsite wwwshueduacademicsartsciphysics

Page 3: Dielectric Barrier Discharge (DBD) & Progress in Large ...bonitz/si12/talks/august_8/lopez_si12.pdf · Dielectric Barrier Discharge (DBD) & Progress in Large-Scale Ozone Generation

New Jersey ndash The birth place of Plasma Science

Irving Langmuir (1881 ndash 1957) Nobel Laureate 1932Nobel Laureate 1932Birth of Plasma Science

BirthplaceBirthplace HobokenHoboken NewNew JerseyJersey

Irving Langmuir was one of the first scientists to work on plasmas and the first to refer to this 4th state of

tt l b th imatter as plasmas because their similarity to blood plasma

Irving Langmuir

Plasma Lighting Technology

Thomas EdisonIncandescent Light Bulb

Fluorescent Lamps Compact fluorescent blub

Daniel McFarlan Moore

BirthplaceBirthplace ofof thethe FluorescentFluorescent LightLight BulbBulb EdisonEdison (Menlo(Menlo Park)Park) WestWest OrangeOrange NJNJ

Plasma Enhanced Technology

A small section of amemory chip

Straight holes like these canbe etched with plasmasmemory chip be etched with plasmas

BirthplaceBirthplace ofof solidsolid--statestate microelectronicsmicroelectronicsBellBell LaboratoriesLaboratories MurrayMurray HillHill NJNJ

Microchip fabrication with plasmas

The US Department of Energyrsquos Princeton Plasma Physics Laboratory (PPPL) is acollaborative national center for plasma and fusion science Its primary mission is tocollaborative national center for plasma and fusion science Its primary mission is todevelop the scientific understanding and the key innovations which will lead to anattractive fusion energy source Associated missions include conducting world-classresearch along the broad frontier of plasma science and technology and providing thehighest quality of scientific education

National Spherical Torus Experiment (NSTX)

Atmospheric Cold PlasmasErich Kunhardt amp Kurt Becker

An Atmospheric Pressure Plasma Generated with a

(Courtesy of K Becker)

Capillary-Plasma-Electrode Discharge

Two Types of plasmas

bull High‐temperature plasmas (Hot Plasmas)g p p ( )Tiasymp Te ge107 Keg fusion plasmas

T asymp T asymp T le 2 x 104 KTi asymp Te asymp Tg le 2 x 104 Keg arc plasma at normal pressure

bull Low‐temperature plasmas (Cold Plasmas)Ti asymp Tg asymp 300 KT ltlt T le 105 KTi ltlt Te le 105 Keg low‐pressure glow discharge

high‐pressure cold plasma

Hot vs Cold PlasmasHot vs Cold Plasmas

LowLow--Temperature (ldquoColdrdquo) PlasmasTemperature (ldquoColdrdquo) Plasmas[Non[Non--equilibrium Nonequilibrium Non--Thermal]Thermal][Non[Non equilibrium Nonequilibrium Non Thermal]Thermal]

How do we make plasmasHow do we make plasmas

Supply Energyeg Heat transfer radiation electric powerhellip

For many plasma applicationsFor many plasma applications an Electric Field is applied to a gaseous environment

Plasma or Gaseous DischargePlasma or Gaseous Discharge

LowLow--Pressure Glow Discharge PlasmasPressure Glow Discharge Plasmas

Plasmas are easier to be generated at low pressures

Low pressure plasmas (1 T f T )

at low pressures

are well understood

are used extensively nowadays

(1 mTorr ~ a few Torr)

are used extensively nowadays (eg in semiconductor industry for computer chips manufacturing)

However to generate low pressure plasmas

vacuum chambers + + = expensive vacuum pumps

pressure monitoring and pressure control devices

+ + =Generate Plasmas at Atmospheric PressureGenerate Plasmas at Atmospheric Pressure

What happens at air pressureWhat happens at air pressure

bull No vacuum is involvedDiffi l d ibull Difficult to generate and sustain

bull Run into some challenges such as glow toarc transition ndash Non controllable

Arc Discharge thermal plasma-Itrsquos hot and detrimental-Gas temperature can reach as high as 2x104 KGas temperature can reach as high as 2x10 K- Low voltage drop at cathode- High cathode current density

High Pressure Microplasmas

Stabilization of high-pressure plasmas ldquopd scalingrdquo ldquoprdquo uarr soplasmas pd scaling p uarr so ldquodrdquo darr to keep breakdown voltage low and minimize instabilities after breakdown -

MicroplasmasDimension a few millimeterDimension a few millimeter down to and below 100 m

Paschen Breakdown CurveH H i 60 100Human Hair 60 ndash 100 m

How do we solve this problemHow do we solve this problem

Transient (pulsed) plasmas In atmospheric plasmas for efficient gas heating atleast 100-1000 collisions are necessary Thus if the plasma duration is shorterleast 100 1000 collisions are necessary Thus if the plasma duration is shorterthan 10-6 ndash 10-5 s gas heating is limited Of course for practical purposes suchplasma has to be operated in a repetitive mode eg in trains of microsecondpulses with millisecond intervals

Micro-confinement Gas heating occurs in the plasma volume and the energy iscarried away by thermal diffusionconvection to the outside If the plasma has asmall volume and a relatively large surface gas heating is limited

Dielectric Barrier Discharges These plasmas are typically created betweenmetal plates which are covered by a thin layer of dielectric or highly resistivematerial The dielectric layer plays an important role in suppressing the currentthe cathodeanode layer is charged by incoming positive ionselectrons whichreduces the electric field and hinders charge transport towards the electrodeDBD also has a large surface-to-volume ratio which promotes diffusion lossesand maintains a low gas temperatureand maintains a low gas temperature

Advantages of Microplasmas Advantages of Microplasmas

bull Low-cost of implementationpbull System flexibilitybull Atmospheric pressure operationbull High densities and high reaction ratesbull High densities and high reaction ratesbull Fast and efficient processesbull Easy to generate and sustain for a variety of gas mixtures

Gl lik d diffbull Glow-like and diffusebull Non-equilibrium (Te gt Tg) to thermalbull Unique chemistryq y

hellip a new realm of plasma sciencehellip a new realm of plasma science

What can we do with microplasmasWhat can we do with microplasmas

Material Synthesis Plasma display Surface Treatment Lighting

OzoneOzone generation for water cleaning

Bio-applicationMaterial processing Dental application

and Many morehellip

Some High Pressure microplasma reactors Some High Pressure microplasma reactors

Dielectric Barrier Discharge (DBD)Dielectric Barrier Discharge (DBD)

Hi h V l

HighVoltage

High VoltageElectrode

ACGenerator

DielectricBarrier

Generator

G

Microplasmas

GroundElectrode

Faradayrsquos Dielectric CapacitorsFaradayrsquos Dielectric Capacitors

Faradays Dielectric Capacitor (circa 1837)

Michael Faraday (1781 ndash 1867) Capacitance INCREASED

Historical Ozone Tube of W Siemens (1857)Historical Ozone Tube of W Siemens (1857)

Werner v SiemensP d frsquo A l d Ch i d Ph ik 102 66 (1857)Poggendorfrsquos Annalen der Chemie und Physik 102 66 (1857)

ldquoOzone Production in an Atmospheric-PressureDielectric Barrier Dischargerdquo

Dielectric Barrier Discharge

Dielectric Barrier DischargeDielectric - Barrier Discharge ConfigurationsHigh

VoltageAC

Generator

High VoltageElectrode

DielectricBarrier

DielectricBarrier

High VoltageElectrode

Discharge

DischargeGeneratorGround

Electrode

Electrode

GroundElectrode

Discharge

H E Wagner R Brandenburg et al lsquoThe barrier discharge basic properties and applications toHE Wagner R Brandenburg et al The barrier discharge basic properties and applications tosurface treatmentrsquo Vacuum 71 p417-436 (2003)

Typical operational conditions of barrier discharges Typical operational conditions of barrier discharges

Electric field strength E of first breakdown asymp150 Td (p = 1bar T=300 K)

Voltage Vpp 3ndash20 kV

Repetition frequency f 50 Hzndash30 kHz

Pressure p 1ndash3 bar

Gap distance g 02ndash5mm

Dielectric material thickness d 05ndash2mm

Relative dielectric permittivity r 5ndash10 (glass)

B Eliasson and U Kogelschatz IEEE Transactions Plasma Science Vol 19 Issue 6 1063-1077 (1991)B Eliasson and U Kogelschatz IEEE Transactions Plasma Science Vol 19 Issue 6 1063-1077 (1991)

Single and double DBD

Single dielectric Double dielectric

Role of the Dielectric (Insulator)

Th di l t i i th k f thThe dielectric is the key for the properfunctioning of the discharge

Serves two functions

1 Limits the amount of charge transportedby a single microplasma

2 Distributes the microplasmas over theentire electrode surface area

Equivalent Circuit of a Microdischarge

Microdischarge Activity and U-Q Lissajous Figure

B Eliasson and U Kogelschatz IEEE Transactions Plasma Science Vol 19 Issue 6 1063-1077 (1991)

Fundamental Operation of the Dielectric Barrier DischargeFundamental Operation of the Dielectric Barrier Discharge

bull Many of relevant plasma processes that areof importance to achieving our goal occuron time scales that allow us to study themon time scales that allow us to study them

bull Optical emission spectroscopic studies willallow us to determine the temporal andspatial development of important plasmaspatial development of important plasmaspecies such as radicals (OH NO variousoxygen radicals) with high time resolution(less than 10 ns) and a spatial resolution onthe scale of mm in the plasma volumepfollowing pulsed plasma excitation

Time scale of the relevant processes of the DBD

HE Wagner R Brandenburg et al lsquoThe barrier discharge basic properties and applications tosurface treatmentrsquo Vacuum 71 417-436 (2003)

Fundamental Operation of the DBDFundamental Operation of the DBD

Electron DensityTemporal Development (ns)

y

Outer Contour Linen = 1010 cm-3ne = 1010 cm 3

Inner Contour Linene = 1014 cm-3

Streamer Propagation in 1 bar AirAA Kulikovsky IEEE Trans Plasma Sci 25 439-446 (1997)

Numerical Results of Microdischarge Formationin Dielectric Barrier Discharges

Starting Phase of a Microdischarge (1 bar 20 CO2 80 H2)

E0=34 kVcm1010 cm-3

1010 cm-3 ne=1012 cm-3

1mm10 cm

ne=108 cm-3

An electron avalanche propagates towards the anode

Reverse propagationtowards the cathodepropagates towards the anode towards the cathode

Numerical Results of Microdischarge Formationin Dielectric Barrier Discharges

Cathode Layer Formation

E0=34 kVcm1010 cm-39 3 0

1mm

1010 cm-3

10 cmne=109 cm-31014

10131014

1013

10 cm1012

Just before the peak of the total current

Peak currentof the total current

Numerical Results of Microdischarge Formationin Dielectric Barrier Discharges

Local Field Collapse in Area Defined by Surface Discharge

ne=109cm-3 ne=1014 cm-3

Gap

Principals of DBD MicroplasmasPrincipals of DBD MicroplasmasPrincipals of DBD MicroplasmasPrincipals of DBD Microplasmas

C C-- - --- - - CG

CD

-- - - CG

CD

Principals of DBD MicroplasmasPrincipals of DBD MicroplasmasPrincipals of DBD MicroplasmasPrincipals of DBD Microplasmas

Dielectric Barrier Discharge (DBD)Dielectric Barrier Discharge (DBD)Electric Field

B kdBreakdown

Electrons amp Ions Discharge Physics

Excited SpeciesPlasma Chemistry

Chemical Reactions

OzoneGeneration

SurfaceTreatment

PollutionControl

ExcimerFormation CO2 Lasers Hydrogenation

of CO2

Excimer Lamps Plasma Displays

How A Plasma Display Works

How A Plasma Display Work

Plasma Display TelevisionsPlasma Display Televisions

Ozone Generator

3 O 2 O

Dielectric Barrier Discharge

3 O2 2 O3

OO22 OO33++OO22Ondash ndashO3O2

O2O2

Ondash ndash

endash O2Ondash ndash O2endash

O3

O3O2O2 O2

HeatHeatHeatHeat

Properties of Ozone (O3)

T i t i f f Tri-atomic form of oxygen

Most powerful commercial oxidizing agent

Unstable - must be generated and used onsite

Limited solubility in water but more so than oxygenLimited solubility in water but more so than oxygen

Leaves a dissolved residual which ultimately converts back to oxygenconverts back to oxygen

Discharge Tubes in Ozone GeneratorsDischarge Tubes in Ozone Generators

Traditional

Ozone Generator

with Glass Tubes

Generation of OzoneGeneration of Ozone

Generation of OzoneAdvantages of Enamel Dielectrics

Proven Patented Designbull Simplicity

Si l Di l i Cbull Single Dielectric Componentndash Reduced number of Dielectrics

bull Safety ndash Lower operating voltage

(lt 4000 V)bull Reliabilty

ndash Fused Dielectrics ensure continuous production

bull Lowest Power Consumption Operational Savingsndash Operational Savings

Modern Ozone GeneratorModern Ozone Generator

Ozonia Advanced Technology Ozone GeneratorOzone Generator

Generation of OzoneGeneration of Ozone

Generation of Ozone

Power Supply UnitPower Supply Unit

IGBT Inverter CircuitMain Circuit Breaker

HV 480 Volts60 Hz3 Phase Supply

C I

450KVAPow er to

GeneratorFILTER

CONVERTER INVERTERTRANSFORMER

C I450KVA Power Stage

CONTACTOR

bull Latest in Power Semiconductor Technology Modular Design

bull Utilizes IGBTrsquos (Insulated Gate Bi‐Polar Transistors) Converter and Inverter Components

Ozone Water Treatment

B bbl Diff iB bbl Diff iBubble DiffusionBubble Diffusion

Easy to use

Low energy usage Low energy usage

Mass transfer efficiencies to gt 90

Ozone Process Flow DiagramOzone Process Flow DiagramVent to

Atmosphere

O OOxygen

Off-Gas Blower

Ozone Destruct Unit

10 12

O3O2

LOX

10-12 O3

Ozone Generators

Ozone Contact ChamberLOX T k Generators Chamber

VaporizersLOX Tank

Municipal Ozone Installations

Ozonia Installations Ozone Plant Size [lbday] Start-Up DateKey Ozonia Installations (Partial List)

Los Angeles CA 10000 1986Fairfax VA ndash Corbalis 9000 2003MWD CA ndash Mills 9 000 2003

Ozonia Installations Ozone Plant Size [lbday] Start Up Date

MWD CA Mills 9000 2003Fairfax Co VA ndash Griffith 9000 2004MWD CA ndash Jensen 18750 2005Indianapolis IN ndash Belmont AWT 12000 2007I di li IN 12 000 2007Indianapolis IN ndash Southport AWT 12000 2007MWD CA ndash Diemer 13400 2008MWD CA ndash Weymouth 13400 2009

Ozonia North America - Potable Water SummaryTotal Number of Installations 90Total Installed Production gt 265000 lbsdayTotal Installed Production 265000 lbsday

Revision -B

Ozone Water TreatmentOzone Water Treatment

MWD Mills WTP - California

3 3 000 lbsda of o one3 3 000 lbsda of o one3 x 3000 lbsday of ozone3 x 3000 lbsday of ozone

Ozone Water TreatmentOzone Water TreatmentOzone Ozone -- How it worksHow it works

OxidantOxidant DisinfectantDisinfectant

bullbull Breaks double carbon Breaks double carbon bondsbonds

bullbull Kills by cell lysing or Kills by cell lysing or causing the cell wall tocausing the cell wall tobondsbonds

bullbull Creates OHCreates OHbullbull radicals radicals which break higher carbon which break higher carbon

causing the cell wall to causing the cell wall to rupture rupture

bullbull AttacksAttacks allall bacteriabacteriabondsbondsbullbull Increased temp and pH Increased temp and pH

accelerates Oaccelerates O33

Attacks Attacks allall bacteria bacteria virus cysts and spores virus cysts and spores in varying degreesin varying degreesaccelerates Oaccelerates O33

decomposition to OHdecomposition to OHbullbull

Micro-organism DNA

Capsule AdenineAdenine

Cell wall ThymineThymine

CytosineCytosine

GuanineGuanine

NuclearmaterialCellmembrane

material

Typical Bacterium DNA

Microbial Growth at Various Ozone ConcentrationsConcentrations

Growth likely

Growth possibleGrowth possible

NO GROWTH

0004 0008 0012 0016 0020

Ozone concentration (mgl)Ozone concentration (mgl)

Typical Water Treatment UsageTypical Water Treatment Usage

Application O3 mgl Contact timeUltra Pure Water 005 - 025 sec ndash min

Water bottling 04 ndash 10 5 ndash 10 min

Swimming pools ampspas

01 ndash 075 4 minutes

Potable taste amp odor 15 ndash 50 5 ndash 10 mindisinfection

Microfloculation 10 ndash 30 5 ndash 10 min

Lignin amp tammin 3 0 10 0 10 30 minLignin amp tamminremoval

30 ndash 100 10 ndash 30 min

Municipal wastewater 50 ndash 150+ 15 ndash 30 min

Ozone Water TreatmentOzone Water TreatmentOzone Ozone ndashndash Municipal ApplicationsMunicipal Applications

bullbull Taste and OdorTaste and Odor

bullbull Color RemovalColor Removal

bullbull Disinfection Without Trihalomethanes (THMs)Disinfection Without Trihalomethanes (THMs)

bullbull Improved Filtration Efficiency and FlocculationImproved Filtration Efficiency and Flocculation

bullbull Cryptosporidium DeactivationCryptosporidium Deactivation

bullbull Giardia amp Virus InactivationGiardia amp Virus Inactivation

bullbull Oxidation Oxidation -- Organics Fe amp MnOrganics Fe amp Mn

bullbull Wastewater disinfectionWastewater disinfection

bullbull BOD COD and TOC reductionBOD COD and TOC reduction

Applications of Ozone

Wastewater Treatmentbull Disinfection of Secondary and Tertiary Effluentsbull Color Reductionbull Color Reductionbull TOC Oxidation (Industrial)bull Oxidation of Odor Causing Compoundsbull Oxidation of Endocrine Disruptors (EDCrsquos) and p ( )

Pharmaceutically Active Compounds (PACrsquos)

Applications of Ozone

What are Endocrine Disruptors (EDCrsquos) and What are Endocrine Disruptors (EDCrsquos) and Ph ti ll A ti C d (PACrsquo )Ph ti ll A ti C d (PACrsquo )Pharmaceutically Active Compounds (PACrsquos)Pharmaceutically Active Compounds (PACrsquos)

bullbull EDCrsquosEDCrsquos andand PACrsquosPACrsquos areare NaturallyNaturally andand SyntheticSyntheticdd th tth t ff tff t thth b lb l llcompoundscompounds thatthat maymay affectaffect thethe balancebalance oror normalnormal

functionsfunctions inin animalsanimals andand humanshumans

What can EDCrsquos and PACrsquos doWhat can EDCrsquos and PACrsquos do

bullbull Even in very small concentrations these compounds Even in very small concentrations these compounds y py pcan can disruptdisrupt normal bodily functionsnormal bodily functions

bullbull ManMan--made chemicals can trick the bodies endocrine made chemicals can trick the bodies endocrine system system

Applications of Ozone

Examples of Endocrine Disruptors1000rsquos of compounds that may be Investigated as EDCs ndash Some examples are

bullbull Synthetic HormonesSynthetic Hormonesbullbull Naturally Occurring Estrogens Naturally Occurring Estrogens

Health and Beauty AidsHealth and Beauty Aidsbullbull Health and Beauty AidsHealth and Beauty Aidsbullbull SolventsSolventsbullbull PesticidesPesticidesbullbull SurfactantsSurfactantsbullbull PlasticsPlastics

F i idF i idbullbull FungicidesFungicides

Ozone Water TreatmentOzone Water Treatment

Ozone Ozone -- Industrial ApplicationsIndustrial Applications-- Ultrapure Water for Pharmaceutical ApplicationsUltrapure Water for Pharmaceutical Applications

-- Wastewater disinfection color removalWastewater disinfection color removal

-- Soil and Groundwater Remediation Soil and Groundwater Remediation

-- Cooling Tower Water TreatmentCooling Tower Water Treatment

-- Food ProcessingFood Processing

-- Aquaculture AquariumsAquaculture AquariumsAquaculture AquariumsAquaculture Aquariums

-- Beverage ApplicationsBeverage Applications

P l amp P Bl hiP l amp P Bl hi-- Pulp amp Paper BleachingPulp amp Paper Bleaching

High Purity OzonationHigh Purity Ozonation

Microchip manufacturingMicrochip manufacturing

What are the current issues in large-scale gozone generationg

Experimental Setup

Front view of the two units after the redesign and reworking ofthe gas water and instruments connectionsthe gas water and instruments connections

Experimental Setup

Top view of the twoexperimental unitsexperimental unitsSpectroscope (notshown) is to the left ofthe DBD The units weredifferent with respect todifferent with respect totheir electrodes onehad only the electrodecoated with thedielectric (ldquosingle-dielectric ( single-coatedrdquo) the other onehad the electrode andthe anode coated withthe dielectric (ldquodouble-the dielectric ( double-coatedrdquo)

Basics Generation of OzoneBasics Generation of Ozone

SpectroscopyPlasma

Plasma Absorption SpectroscopyPlasma Absorption Spectroscopy

Infrared Absorption SpectroscopyInfrared Absorption Spectroscopy

IR spectra in pure oxygen (black curve) and at approximately 10wt N2 admixture (red line) N2O5 peaks appear at124 1 d 1 2 11245 cm-1 and at 1725 cm-1

Infrared Absorption SpectroscopyInfrared Absorption Spectroscopy

IR spectra of several methane variations The green curve envelopes all of the methane peaks at 1325 cm-1recorded at smaller methane admixtures Simultaneously the N2O5 peaks disappear as the methane peaks appear

N2O5 FormationN2O5 Formation2 52 5p=2 bara cwt=20degC q=35kWm2 f=1450Hz

45N2O5 AT95

30

35

40

N

2 B

lend

ing

N2O AT95N2O5 IGSN2O IGSN2O5 LGN2O LG

1 5

20

25

nt [p

pmV]

3

wt

05

10

15

NO

x co

nten

005 7 9 11 13 15 17

ozone conc [wt]

Amount of formed N2O5 and N2O as a function of ozone concentration at 3 wt of nitrogen admixture and fori l dvarious electrode arrangements

Plasma Emission SpectroscopyPlasma Emission Spectroscopyp pyp py

Relative Emissions of the Ozonizer plasmaRelative Emissions of the Ozonizer plasma

Region 300- 850 nm from individual (calibrated) regions (smoothed by PeakFit) Single-coated ozone generator Inlet side

3 5E+06

30E+06

35E+06

7 9

20E+06

25E+06

nten

sity

au

2

311 12

10E+06

15E+06

In 4

5

6 8 10

14

15

16

17

00E+00

50E+05

280 300 320 340 360 380 400 420 440 460 480 500 520 540 560 580 600 620 640 660 680 700 720 740 760 780 800 820 840 860

Wavelength nm

1 13

Wavelength nm

Absolute Emission of the DBD PlasmaAbsolute Emission of the DBD Plasma

Intensities in (O2+3 wtN2) plasma

1 20E+04

100E+04

120E+04

600E+03

800E+03

nten

sity

(au

)

200E+03

400E+03

In

O(777)

000E+00200 250 300 350 400 450 500 550 600 650 700 750 800 850

Wavelength nm

Intensities in 3 wtN2+O2 plasmaIntensities in 3 wtN2+O2 plasma

Plasma Chemistry in OzonizersPlasma Chemistry in Ozonizers

Dry Air O2 N2

e - e -

O N2 N O2

O3 NO

O2 N O2

O3

N

3

NO2

O2 O3

NO

N

NO2 O3

N2O

NO3 N

N2O4

NO2

NO2

N2O5

NO3

Primary electron-driven chemical reactions leading to the formation of N2O5 and N2O in a dry air plasma

Plasma emission diagnostics role of N2Plasma emission diagnostics role of N2

Dry Air O2 N2

e - e -

O N2 N O2

O3 NO

O2 N O2

O3

O

N

ON

NO2

O2O3

N

NO N

NO2 O3

N2O

NO3 N

N2O4

NO2

NO2

N2O5

NO3

ONbullWith N2 present ndash less oxygen atoms are formed However the difference in intensity is

very small

Modeling of plasma chemistry incl the NxOy chemistry up to N2O5 for different Oxygen Nitrogen mixtures varying power deposition scenarios

and initial ozone background concentrations (up to 15) previously done

The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation

The role of N2 must be related to its by-products reacting on the surface of the electrodeThe role of N2 must be related to its by-products reacting on the surface of the electrode

The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established

Ab 8 t f O

The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established

Ab 8 t f OAbove 8 wt of O3

1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)

Above 8 wt of O3

1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)case without pampp)

2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of the

case without pampp)

2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of thethem A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface

them A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface

The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation

Three possibilities have to be considered for the oxygen-fedozone generator

Three possibilities have to be considered for the oxygen-fedozone generatorozone generator

bull Excited N2 molecules lead to an increased O2 dissociation in

ozone generator

bull Excited N2 molecules lead to an increased O2 dissociation in2 2such case an increased efficiency is correlated to the N2admixture

2 2such case an increased efficiency is correlated to the N2admixture

bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial

bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial

bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2

bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2g p g 3 pp y 2g p g 3 pp y 2

Effect of methane on ozone efficiency and specific powerEffect of methane on ozone efficiency and specific power

Effect of Methane on Ozone Content in Outlet Gas and on Specific Power Pure O2

13 12

10

11

12

t 8

10

8

9

10

ne c

onte

nt w

t

6

8

ecifi

c po

wer

kW

hlb

5

6

7

Ozo

n

2

4 Spe

400E+00 20E+03 40E+03 60E+03 80E+03 10E+04 12E+04

Methane in feedgas ppm

0

Ozone content in the outlet gas Specif ic pow er of the ozone generatorg p p g

Effects of N2 and CH4Effects of N2 and CH4

Pi t f h t lli N O t tPicture of an amorphous-crystalline N2O5 structurecaptured at the Orlando Skylake water plant in 2006

Plasma Chemistry with CH4 Impurities

OxygenO2 N2

e - e -

CHO N2

NO2

O NO

O2 N O2 O3

NOH

CH4e-

O3 NO

NO2

O2O3NO N

NO2 O

NO2

NO2

N2ONO3

N

O3

NO2

NO

HNO3

N2O4

N2O5

NO2

NO3

N2O5

Effect of methane on the electrode surfaces

a) b)

Inlet Outlet Outlet

) d)

I l t I l t

c) d)

Electrode of the ozone generator afterseveral hours in CH8O2 and up to 2 wt of methane (a b c)

Inlet Inlet

three hours in CH8O2+traces of N2 and up to 1 wt of methane (d) Visible change of discharge character at about 13 length of electrode (a d)

Kinetics of CHx Conversion without N2

conversion by collisions

O2 + CHx 12wt O3 + CO2 +H2O

deposition vaporizationby sputtering

ibl b l 1000 CHreversible process below 1000ppm CH4

Effect of water on electrode surface with N2

Inlet

OutletOutlet

Electrode of the ozone generator after several hours in H OO N

Inlet

Electrode of the ozone generator after several hours in H2OO2N2

Effect of water on electrode surface

Long term effect (800 hrs) of H2OO2N2

Kinetics of CHx Conversion with N2

conversion by collisionsHNO3 formation

O2 + N2 +CHx 12wtO2 + CO2 +H2O + HNO3

deposition vaporizationby sputtering

H2O + HNO3

by sputtering

irreversible process above a N2 threshold () ltlt 1000ppm N2

sticky deposit

p 2 ( ) pp 2 any CH4 concentration (60ppm)

Plasma Chemistry with CH4 ImpuritiesPlasma Chemistry with CH4 Impurities4

bull Formation of NO and NO2 depends on O3 N2 and gas temperature Conclusion N2 admixture is the key factor

SummarySummaryyyThe mechanisms of formed NOx by-products follows the sameThe mechanisms of formed NOx by-products follows the sameprinciples as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentration

principles as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentrationozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)

ozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)g p ( g p )

The conversion of methane to OH and H2O is found to depend on

g p ( g p )

The conversion of methane to OH and H2O is found to depend ondissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)

dissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)discharge gap)discharge gap)

How do you optimize an ozone generatorg

Scientific ApproachScientific ApproachTheoretical Experimental

pppp

c [wt]

f [Hz]

c [wt]

f [Hz]

[kW]UUUβ1

1Cf4αPn

1iiminpeakimin

iiD

q [kWm2]q [kWm2]

150

180

][V]voltagepeakUpeak

[]cylinder perslicesofamountnsliceii

whereth

09 00

30

60

90

120

effic

ienc

y [

][0tdj t bl[F]sliceisdielectricofecapacitancC

[Hz]frequencyf[V]sliceivoltageminimumiUmin

thiD

th

10

28

46

64

82

39

107

176

244 power density

[kWm2]

ozone conc [wt][]CCβ

][0parameteradjustableα

iDiGi

Impact of Power Inductionp

350

400

wer

200

250

300

App

lied

Pow

Arr C 2Arr D +0

Arr E +45Arr F +7

Arr G +3

5 0

100

150

Frac

tion

of

1 2 3 4

ReferenceArr B unstable

Arr C -2

00

50

4Position (1inlet 4outlet)

Experimental Test Rigp g

Experimental Test Rigp g

Outer grounded electrode (left picture) and the dielectric covered inner electrodes (right) d e ect c cove ed e e ect odes ( g t)

Reference (Traditional) Arrangement

Inlet OutletGas flow direction

Optimized Arrangement

Inlet OutletGas flow direction

Intelligent Gap System (IGS)g p y ( )

Molecular Oxygen (O2) Ozone (O3)

O2 O3

yg ( 2) ( 3)

Particle Size SynthesisParticle Size SynthesisByBy--Products Cluster FormationProducts Cluster Formationyy

high diffusion and deposition to surfaces

low diffusion rate good transport

high sedimentation on the structurehigh sedimentation on the structure

Degreacutemont Technologies ndash OzoniaIntelligent Gap SystemIntelligent Gap System

G Vezzuacute JL Lopez A Freilich and K Becker Optimizationof Large-Scale Ozone Generators IEEE Transactions onPlasma Science Vol 37 No 6 p 890-896 (2009)

ConclusionsConclusionsConclusionsConclusionsFundamentals of ozone synthesis in a DBD plasmay p

ndash Highly filamented DBD discharges are best-suitedfor the production of ozone concentrations in therange of 6 to 14 wtrange of 6 to 14 wt

ndash The preferred characteristic of the microdischargesare Townsend-like at reduced electric fields Enaround 190 Townsend

ndash Detrimental side-effects induced by by-productscan be avoided by a proper design of the electrodecan be avoided by a proper design of the electrodearrangement The phenomenon is related to thediffusion rates of formed by-product clusters

ConclusionsConclusionsConclusionsConclusionsBenefits from DBD microplasma tailoring

ndash Reduced power consumption of up to 10 improvement

ndash Increased ozone concentrations of up to 14 now achievable

ndash Improved neutralization and conditioning of detrimental by-products

ndash Reduced system capital and operational cost

New technologies to improve ozone p

generatorg

HV Pulsed Power SwitchingHV Pulsed Power Switching

Microchannel Generation of Ozone

Channel ArrayChannel Array

Microchannel

330 microm 230 microm

Some Cap-DBD Devices Operating in Air

Increase of 60 of

Spacing 225 μmof 60 of plasma

No space

Cap‐DBD ozone generation

bull Ozone concentration is evaluated via Eco S d l UV 100 O A l (0 01Sensors model UV-100 Ozone Analyzer (001 ndash 900 ppm wiht an accuracy of plusmn2)

bull Three reactors 6 tubings 6rdquo with spacings of 0 μm 225 μm and 500 μm running at 3 kV μ μ μ g

SpacingOzone Concentration

3 kV rms 4 kV rms3 kV rms 4 kV rms

0 μm 660 ppm

225 μm 550 ppm

For a device of such small scale these ozone levels are promising

500 μm 380 ppm

J Mahoney W Zhu VS Johnson KH Becker and JL Lopez Electrical and optical emissionmeasurements of a capillary dielectric barrier discharge European Physics Journal D Vol 60 441-447(2010)

QuestionsQuestions

Thank YouFor more informationProf Jose L Lopez PhD

Thank YouFor more informationDepartment of Physics

Telephone (973) 761-9057Email joselopez1shuedu

Website wwwshueduacademicsartsciphysicsWebsite wwwshueduacademicsartsciphysics

Page 4: Dielectric Barrier Discharge (DBD) & Progress in Large ...bonitz/si12/talks/august_8/lopez_si12.pdf · Dielectric Barrier Discharge (DBD) & Progress in Large-Scale Ozone Generation

Plasma Lighting Technology

Thomas EdisonIncandescent Light Bulb

Fluorescent Lamps Compact fluorescent blub

Daniel McFarlan Moore

BirthplaceBirthplace ofof thethe FluorescentFluorescent LightLight BulbBulb EdisonEdison (Menlo(Menlo Park)Park) WestWest OrangeOrange NJNJ

Plasma Enhanced Technology

A small section of amemory chip

Straight holes like these canbe etched with plasmasmemory chip be etched with plasmas

BirthplaceBirthplace ofof solidsolid--statestate microelectronicsmicroelectronicsBellBell LaboratoriesLaboratories MurrayMurray HillHill NJNJ

Microchip fabrication with plasmas

The US Department of Energyrsquos Princeton Plasma Physics Laboratory (PPPL) is acollaborative national center for plasma and fusion science Its primary mission is tocollaborative national center for plasma and fusion science Its primary mission is todevelop the scientific understanding and the key innovations which will lead to anattractive fusion energy source Associated missions include conducting world-classresearch along the broad frontier of plasma science and technology and providing thehighest quality of scientific education

National Spherical Torus Experiment (NSTX)

Atmospheric Cold PlasmasErich Kunhardt amp Kurt Becker

An Atmospheric Pressure Plasma Generated with a

(Courtesy of K Becker)

Capillary-Plasma-Electrode Discharge

Two Types of plasmas

bull High‐temperature plasmas (Hot Plasmas)g p p ( )Tiasymp Te ge107 Keg fusion plasmas

T asymp T asymp T le 2 x 104 KTi asymp Te asymp Tg le 2 x 104 Keg arc plasma at normal pressure

bull Low‐temperature plasmas (Cold Plasmas)Ti asymp Tg asymp 300 KT ltlt T le 105 KTi ltlt Te le 105 Keg low‐pressure glow discharge

high‐pressure cold plasma

Hot vs Cold PlasmasHot vs Cold Plasmas

LowLow--Temperature (ldquoColdrdquo) PlasmasTemperature (ldquoColdrdquo) Plasmas[Non[Non--equilibrium Nonequilibrium Non--Thermal]Thermal][Non[Non equilibrium Nonequilibrium Non Thermal]Thermal]

How do we make plasmasHow do we make plasmas

Supply Energyeg Heat transfer radiation electric powerhellip

For many plasma applicationsFor many plasma applications an Electric Field is applied to a gaseous environment

Plasma or Gaseous DischargePlasma or Gaseous Discharge

LowLow--Pressure Glow Discharge PlasmasPressure Glow Discharge Plasmas

Plasmas are easier to be generated at low pressures

Low pressure plasmas (1 T f T )

at low pressures

are well understood

are used extensively nowadays

(1 mTorr ~ a few Torr)

are used extensively nowadays (eg in semiconductor industry for computer chips manufacturing)

However to generate low pressure plasmas

vacuum chambers + + = expensive vacuum pumps

pressure monitoring and pressure control devices

+ + =Generate Plasmas at Atmospheric PressureGenerate Plasmas at Atmospheric Pressure

What happens at air pressureWhat happens at air pressure

bull No vacuum is involvedDiffi l d ibull Difficult to generate and sustain

bull Run into some challenges such as glow toarc transition ndash Non controllable

Arc Discharge thermal plasma-Itrsquos hot and detrimental-Gas temperature can reach as high as 2x104 KGas temperature can reach as high as 2x10 K- Low voltage drop at cathode- High cathode current density

High Pressure Microplasmas

Stabilization of high-pressure plasmas ldquopd scalingrdquo ldquoprdquo uarr soplasmas pd scaling p uarr so ldquodrdquo darr to keep breakdown voltage low and minimize instabilities after breakdown -

MicroplasmasDimension a few millimeterDimension a few millimeter down to and below 100 m

Paschen Breakdown CurveH H i 60 100Human Hair 60 ndash 100 m

How do we solve this problemHow do we solve this problem

Transient (pulsed) plasmas In atmospheric plasmas for efficient gas heating atleast 100-1000 collisions are necessary Thus if the plasma duration is shorterleast 100 1000 collisions are necessary Thus if the plasma duration is shorterthan 10-6 ndash 10-5 s gas heating is limited Of course for practical purposes suchplasma has to be operated in a repetitive mode eg in trains of microsecondpulses with millisecond intervals

Micro-confinement Gas heating occurs in the plasma volume and the energy iscarried away by thermal diffusionconvection to the outside If the plasma has asmall volume and a relatively large surface gas heating is limited

Dielectric Barrier Discharges These plasmas are typically created betweenmetal plates which are covered by a thin layer of dielectric or highly resistivematerial The dielectric layer plays an important role in suppressing the currentthe cathodeanode layer is charged by incoming positive ionselectrons whichreduces the electric field and hinders charge transport towards the electrodeDBD also has a large surface-to-volume ratio which promotes diffusion lossesand maintains a low gas temperatureand maintains a low gas temperature

Advantages of Microplasmas Advantages of Microplasmas

bull Low-cost of implementationpbull System flexibilitybull Atmospheric pressure operationbull High densities and high reaction ratesbull High densities and high reaction ratesbull Fast and efficient processesbull Easy to generate and sustain for a variety of gas mixtures

Gl lik d diffbull Glow-like and diffusebull Non-equilibrium (Te gt Tg) to thermalbull Unique chemistryq y

hellip a new realm of plasma sciencehellip a new realm of plasma science

What can we do with microplasmasWhat can we do with microplasmas

Material Synthesis Plasma display Surface Treatment Lighting

OzoneOzone generation for water cleaning

Bio-applicationMaterial processing Dental application

and Many morehellip

Some High Pressure microplasma reactors Some High Pressure microplasma reactors

Dielectric Barrier Discharge (DBD)Dielectric Barrier Discharge (DBD)

Hi h V l

HighVoltage

High VoltageElectrode

ACGenerator

DielectricBarrier

Generator

G

Microplasmas

GroundElectrode

Faradayrsquos Dielectric CapacitorsFaradayrsquos Dielectric Capacitors

Faradays Dielectric Capacitor (circa 1837)

Michael Faraday (1781 ndash 1867) Capacitance INCREASED

Historical Ozone Tube of W Siemens (1857)Historical Ozone Tube of W Siemens (1857)

Werner v SiemensP d frsquo A l d Ch i d Ph ik 102 66 (1857)Poggendorfrsquos Annalen der Chemie und Physik 102 66 (1857)

ldquoOzone Production in an Atmospheric-PressureDielectric Barrier Dischargerdquo

Dielectric Barrier Discharge

Dielectric Barrier DischargeDielectric - Barrier Discharge ConfigurationsHigh

VoltageAC

Generator

High VoltageElectrode

DielectricBarrier

DielectricBarrier

High VoltageElectrode

Discharge

DischargeGeneratorGround

Electrode

Electrode

GroundElectrode

Discharge

H E Wagner R Brandenburg et al lsquoThe barrier discharge basic properties and applications toHE Wagner R Brandenburg et al The barrier discharge basic properties and applications tosurface treatmentrsquo Vacuum 71 p417-436 (2003)

Typical operational conditions of barrier discharges Typical operational conditions of barrier discharges

Electric field strength E of first breakdown asymp150 Td (p = 1bar T=300 K)

Voltage Vpp 3ndash20 kV

Repetition frequency f 50 Hzndash30 kHz

Pressure p 1ndash3 bar

Gap distance g 02ndash5mm

Dielectric material thickness d 05ndash2mm

Relative dielectric permittivity r 5ndash10 (glass)

B Eliasson and U Kogelschatz IEEE Transactions Plasma Science Vol 19 Issue 6 1063-1077 (1991)B Eliasson and U Kogelschatz IEEE Transactions Plasma Science Vol 19 Issue 6 1063-1077 (1991)

Single and double DBD

Single dielectric Double dielectric

Role of the Dielectric (Insulator)

Th di l t i i th k f thThe dielectric is the key for the properfunctioning of the discharge

Serves two functions

1 Limits the amount of charge transportedby a single microplasma

2 Distributes the microplasmas over theentire electrode surface area

Equivalent Circuit of a Microdischarge

Microdischarge Activity and U-Q Lissajous Figure

B Eliasson and U Kogelschatz IEEE Transactions Plasma Science Vol 19 Issue 6 1063-1077 (1991)

Fundamental Operation of the Dielectric Barrier DischargeFundamental Operation of the Dielectric Barrier Discharge

bull Many of relevant plasma processes that areof importance to achieving our goal occuron time scales that allow us to study themon time scales that allow us to study them

bull Optical emission spectroscopic studies willallow us to determine the temporal andspatial development of important plasmaspatial development of important plasmaspecies such as radicals (OH NO variousoxygen radicals) with high time resolution(less than 10 ns) and a spatial resolution onthe scale of mm in the plasma volumepfollowing pulsed plasma excitation

Time scale of the relevant processes of the DBD

HE Wagner R Brandenburg et al lsquoThe barrier discharge basic properties and applications tosurface treatmentrsquo Vacuum 71 417-436 (2003)

Fundamental Operation of the DBDFundamental Operation of the DBD

Electron DensityTemporal Development (ns)

y

Outer Contour Linen = 1010 cm-3ne = 1010 cm 3

Inner Contour Linene = 1014 cm-3

Streamer Propagation in 1 bar AirAA Kulikovsky IEEE Trans Plasma Sci 25 439-446 (1997)

Numerical Results of Microdischarge Formationin Dielectric Barrier Discharges

Starting Phase of a Microdischarge (1 bar 20 CO2 80 H2)

E0=34 kVcm1010 cm-3

1010 cm-3 ne=1012 cm-3

1mm10 cm

ne=108 cm-3

An electron avalanche propagates towards the anode

Reverse propagationtowards the cathodepropagates towards the anode towards the cathode

Numerical Results of Microdischarge Formationin Dielectric Barrier Discharges

Cathode Layer Formation

E0=34 kVcm1010 cm-39 3 0

1mm

1010 cm-3

10 cmne=109 cm-31014

10131014

1013

10 cm1012

Just before the peak of the total current

Peak currentof the total current

Numerical Results of Microdischarge Formationin Dielectric Barrier Discharges

Local Field Collapse in Area Defined by Surface Discharge

ne=109cm-3 ne=1014 cm-3

Gap

Principals of DBD MicroplasmasPrincipals of DBD MicroplasmasPrincipals of DBD MicroplasmasPrincipals of DBD Microplasmas

C C-- - --- - - CG

CD

-- - - CG

CD

Principals of DBD MicroplasmasPrincipals of DBD MicroplasmasPrincipals of DBD MicroplasmasPrincipals of DBD Microplasmas

Dielectric Barrier Discharge (DBD)Dielectric Barrier Discharge (DBD)Electric Field

B kdBreakdown

Electrons amp Ions Discharge Physics

Excited SpeciesPlasma Chemistry

Chemical Reactions

OzoneGeneration

SurfaceTreatment

PollutionControl

ExcimerFormation CO2 Lasers Hydrogenation

of CO2

Excimer Lamps Plasma Displays

How A Plasma Display Works

How A Plasma Display Work

Plasma Display TelevisionsPlasma Display Televisions

Ozone Generator

3 O 2 O

Dielectric Barrier Discharge

3 O2 2 O3

OO22 OO33++OO22Ondash ndashO3O2

O2O2

Ondash ndash

endash O2Ondash ndash O2endash

O3

O3O2O2 O2

HeatHeatHeatHeat

Properties of Ozone (O3)

T i t i f f Tri-atomic form of oxygen

Most powerful commercial oxidizing agent

Unstable - must be generated and used onsite

Limited solubility in water but more so than oxygenLimited solubility in water but more so than oxygen

Leaves a dissolved residual which ultimately converts back to oxygenconverts back to oxygen

Discharge Tubes in Ozone GeneratorsDischarge Tubes in Ozone Generators

Traditional

Ozone Generator

with Glass Tubes

Generation of OzoneGeneration of Ozone

Generation of OzoneAdvantages of Enamel Dielectrics

Proven Patented Designbull Simplicity

Si l Di l i Cbull Single Dielectric Componentndash Reduced number of Dielectrics

bull Safety ndash Lower operating voltage

(lt 4000 V)bull Reliabilty

ndash Fused Dielectrics ensure continuous production

bull Lowest Power Consumption Operational Savingsndash Operational Savings

Modern Ozone GeneratorModern Ozone Generator

Ozonia Advanced Technology Ozone GeneratorOzone Generator

Generation of OzoneGeneration of Ozone

Generation of Ozone

Power Supply UnitPower Supply Unit

IGBT Inverter CircuitMain Circuit Breaker

HV 480 Volts60 Hz3 Phase Supply

C I

450KVAPow er to

GeneratorFILTER

CONVERTER INVERTERTRANSFORMER

C I450KVA Power Stage

CONTACTOR

bull Latest in Power Semiconductor Technology Modular Design

bull Utilizes IGBTrsquos (Insulated Gate Bi‐Polar Transistors) Converter and Inverter Components

Ozone Water Treatment

B bbl Diff iB bbl Diff iBubble DiffusionBubble Diffusion

Easy to use

Low energy usage Low energy usage

Mass transfer efficiencies to gt 90

Ozone Process Flow DiagramOzone Process Flow DiagramVent to

Atmosphere

O OOxygen

Off-Gas Blower

Ozone Destruct Unit

10 12

O3O2

LOX

10-12 O3

Ozone Generators

Ozone Contact ChamberLOX T k Generators Chamber

VaporizersLOX Tank

Municipal Ozone Installations

Ozonia Installations Ozone Plant Size [lbday] Start-Up DateKey Ozonia Installations (Partial List)

Los Angeles CA 10000 1986Fairfax VA ndash Corbalis 9000 2003MWD CA ndash Mills 9 000 2003

Ozonia Installations Ozone Plant Size [lbday] Start Up Date

MWD CA Mills 9000 2003Fairfax Co VA ndash Griffith 9000 2004MWD CA ndash Jensen 18750 2005Indianapolis IN ndash Belmont AWT 12000 2007I di li IN 12 000 2007Indianapolis IN ndash Southport AWT 12000 2007MWD CA ndash Diemer 13400 2008MWD CA ndash Weymouth 13400 2009

Ozonia North America - Potable Water SummaryTotal Number of Installations 90Total Installed Production gt 265000 lbsdayTotal Installed Production 265000 lbsday

Revision -B

Ozone Water TreatmentOzone Water Treatment

MWD Mills WTP - California

3 3 000 lbsda of o one3 3 000 lbsda of o one3 x 3000 lbsday of ozone3 x 3000 lbsday of ozone

Ozone Water TreatmentOzone Water TreatmentOzone Ozone -- How it worksHow it works

OxidantOxidant DisinfectantDisinfectant

bullbull Breaks double carbon Breaks double carbon bondsbonds

bullbull Kills by cell lysing or Kills by cell lysing or causing the cell wall tocausing the cell wall tobondsbonds

bullbull Creates OHCreates OHbullbull radicals radicals which break higher carbon which break higher carbon

causing the cell wall to causing the cell wall to rupture rupture

bullbull AttacksAttacks allall bacteriabacteriabondsbondsbullbull Increased temp and pH Increased temp and pH

accelerates Oaccelerates O33

Attacks Attacks allall bacteria bacteria virus cysts and spores virus cysts and spores in varying degreesin varying degreesaccelerates Oaccelerates O33

decomposition to OHdecomposition to OHbullbull

Micro-organism DNA

Capsule AdenineAdenine

Cell wall ThymineThymine

CytosineCytosine

GuanineGuanine

NuclearmaterialCellmembrane

material

Typical Bacterium DNA

Microbial Growth at Various Ozone ConcentrationsConcentrations

Growth likely

Growth possibleGrowth possible

NO GROWTH

0004 0008 0012 0016 0020

Ozone concentration (mgl)Ozone concentration (mgl)

Typical Water Treatment UsageTypical Water Treatment Usage

Application O3 mgl Contact timeUltra Pure Water 005 - 025 sec ndash min

Water bottling 04 ndash 10 5 ndash 10 min

Swimming pools ampspas

01 ndash 075 4 minutes

Potable taste amp odor 15 ndash 50 5 ndash 10 mindisinfection

Microfloculation 10 ndash 30 5 ndash 10 min

Lignin amp tammin 3 0 10 0 10 30 minLignin amp tamminremoval

30 ndash 100 10 ndash 30 min

Municipal wastewater 50 ndash 150+ 15 ndash 30 min

Ozone Water TreatmentOzone Water TreatmentOzone Ozone ndashndash Municipal ApplicationsMunicipal Applications

bullbull Taste and OdorTaste and Odor

bullbull Color RemovalColor Removal

bullbull Disinfection Without Trihalomethanes (THMs)Disinfection Without Trihalomethanes (THMs)

bullbull Improved Filtration Efficiency and FlocculationImproved Filtration Efficiency and Flocculation

bullbull Cryptosporidium DeactivationCryptosporidium Deactivation

bullbull Giardia amp Virus InactivationGiardia amp Virus Inactivation

bullbull Oxidation Oxidation -- Organics Fe amp MnOrganics Fe amp Mn

bullbull Wastewater disinfectionWastewater disinfection

bullbull BOD COD and TOC reductionBOD COD and TOC reduction

Applications of Ozone

Wastewater Treatmentbull Disinfection of Secondary and Tertiary Effluentsbull Color Reductionbull Color Reductionbull TOC Oxidation (Industrial)bull Oxidation of Odor Causing Compoundsbull Oxidation of Endocrine Disruptors (EDCrsquos) and p ( )

Pharmaceutically Active Compounds (PACrsquos)

Applications of Ozone

What are Endocrine Disruptors (EDCrsquos) and What are Endocrine Disruptors (EDCrsquos) and Ph ti ll A ti C d (PACrsquo )Ph ti ll A ti C d (PACrsquo )Pharmaceutically Active Compounds (PACrsquos)Pharmaceutically Active Compounds (PACrsquos)

bullbull EDCrsquosEDCrsquos andand PACrsquosPACrsquos areare NaturallyNaturally andand SyntheticSyntheticdd th tth t ff tff t thth b lb l llcompoundscompounds thatthat maymay affectaffect thethe balancebalance oror normalnormal

functionsfunctions inin animalsanimals andand humanshumans

What can EDCrsquos and PACrsquos doWhat can EDCrsquos and PACrsquos do

bullbull Even in very small concentrations these compounds Even in very small concentrations these compounds y py pcan can disruptdisrupt normal bodily functionsnormal bodily functions

bullbull ManMan--made chemicals can trick the bodies endocrine made chemicals can trick the bodies endocrine system system

Applications of Ozone

Examples of Endocrine Disruptors1000rsquos of compounds that may be Investigated as EDCs ndash Some examples are

bullbull Synthetic HormonesSynthetic Hormonesbullbull Naturally Occurring Estrogens Naturally Occurring Estrogens

Health and Beauty AidsHealth and Beauty Aidsbullbull Health and Beauty AidsHealth and Beauty Aidsbullbull SolventsSolventsbullbull PesticidesPesticidesbullbull SurfactantsSurfactantsbullbull PlasticsPlastics

F i idF i idbullbull FungicidesFungicides

Ozone Water TreatmentOzone Water Treatment

Ozone Ozone -- Industrial ApplicationsIndustrial Applications-- Ultrapure Water for Pharmaceutical ApplicationsUltrapure Water for Pharmaceutical Applications

-- Wastewater disinfection color removalWastewater disinfection color removal

-- Soil and Groundwater Remediation Soil and Groundwater Remediation

-- Cooling Tower Water TreatmentCooling Tower Water Treatment

-- Food ProcessingFood Processing

-- Aquaculture AquariumsAquaculture AquariumsAquaculture AquariumsAquaculture Aquariums

-- Beverage ApplicationsBeverage Applications

P l amp P Bl hiP l amp P Bl hi-- Pulp amp Paper BleachingPulp amp Paper Bleaching

High Purity OzonationHigh Purity Ozonation

Microchip manufacturingMicrochip manufacturing

What are the current issues in large-scale gozone generationg

Experimental Setup

Front view of the two units after the redesign and reworking ofthe gas water and instruments connectionsthe gas water and instruments connections

Experimental Setup

Top view of the twoexperimental unitsexperimental unitsSpectroscope (notshown) is to the left ofthe DBD The units weredifferent with respect todifferent with respect totheir electrodes onehad only the electrodecoated with thedielectric (ldquosingle-dielectric ( single-coatedrdquo) the other onehad the electrode andthe anode coated withthe dielectric (ldquodouble-the dielectric ( double-coatedrdquo)

Basics Generation of OzoneBasics Generation of Ozone

SpectroscopyPlasma

Plasma Absorption SpectroscopyPlasma Absorption Spectroscopy

Infrared Absorption SpectroscopyInfrared Absorption Spectroscopy

IR spectra in pure oxygen (black curve) and at approximately 10wt N2 admixture (red line) N2O5 peaks appear at124 1 d 1 2 11245 cm-1 and at 1725 cm-1

Infrared Absorption SpectroscopyInfrared Absorption Spectroscopy

IR spectra of several methane variations The green curve envelopes all of the methane peaks at 1325 cm-1recorded at smaller methane admixtures Simultaneously the N2O5 peaks disappear as the methane peaks appear

N2O5 FormationN2O5 Formation2 52 5p=2 bara cwt=20degC q=35kWm2 f=1450Hz

45N2O5 AT95

30

35

40

N

2 B

lend

ing

N2O AT95N2O5 IGSN2O IGSN2O5 LGN2O LG

1 5

20

25

nt [p

pmV]

3

wt

05

10

15

NO

x co

nten

005 7 9 11 13 15 17

ozone conc [wt]

Amount of formed N2O5 and N2O as a function of ozone concentration at 3 wt of nitrogen admixture and fori l dvarious electrode arrangements

Plasma Emission SpectroscopyPlasma Emission Spectroscopyp pyp py

Relative Emissions of the Ozonizer plasmaRelative Emissions of the Ozonizer plasma

Region 300- 850 nm from individual (calibrated) regions (smoothed by PeakFit) Single-coated ozone generator Inlet side

3 5E+06

30E+06

35E+06

7 9

20E+06

25E+06

nten

sity

au

2

311 12

10E+06

15E+06

In 4

5

6 8 10

14

15

16

17

00E+00

50E+05

280 300 320 340 360 380 400 420 440 460 480 500 520 540 560 580 600 620 640 660 680 700 720 740 760 780 800 820 840 860

Wavelength nm

1 13

Wavelength nm

Absolute Emission of the DBD PlasmaAbsolute Emission of the DBD Plasma

Intensities in (O2+3 wtN2) plasma

1 20E+04

100E+04

120E+04

600E+03

800E+03

nten

sity

(au

)

200E+03

400E+03

In

O(777)

000E+00200 250 300 350 400 450 500 550 600 650 700 750 800 850

Wavelength nm

Intensities in 3 wtN2+O2 plasmaIntensities in 3 wtN2+O2 plasma

Plasma Chemistry in OzonizersPlasma Chemistry in Ozonizers

Dry Air O2 N2

e - e -

O N2 N O2

O3 NO

O2 N O2

O3

N

3

NO2

O2 O3

NO

N

NO2 O3

N2O

NO3 N

N2O4

NO2

NO2

N2O5

NO3

Primary electron-driven chemical reactions leading to the formation of N2O5 and N2O in a dry air plasma

Plasma emission diagnostics role of N2Plasma emission diagnostics role of N2

Dry Air O2 N2

e - e -

O N2 N O2

O3 NO

O2 N O2

O3

O

N

ON

NO2

O2O3

N

NO N

NO2 O3

N2O

NO3 N

N2O4

NO2

NO2

N2O5

NO3

ONbullWith N2 present ndash less oxygen atoms are formed However the difference in intensity is

very small

Modeling of plasma chemistry incl the NxOy chemistry up to N2O5 for different Oxygen Nitrogen mixtures varying power deposition scenarios

and initial ozone background concentrations (up to 15) previously done

The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation

The role of N2 must be related to its by-products reacting on the surface of the electrodeThe role of N2 must be related to its by-products reacting on the surface of the electrode

The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established

Ab 8 t f O

The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established

Ab 8 t f OAbove 8 wt of O3

1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)

Above 8 wt of O3

1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)case without pampp)

2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of the

case without pampp)

2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of thethem A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface

them A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface

The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation

Three possibilities have to be considered for the oxygen-fedozone generator

Three possibilities have to be considered for the oxygen-fedozone generatorozone generator

bull Excited N2 molecules lead to an increased O2 dissociation in

ozone generator

bull Excited N2 molecules lead to an increased O2 dissociation in2 2such case an increased efficiency is correlated to the N2admixture

2 2such case an increased efficiency is correlated to the N2admixture

bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial

bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial

bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2

bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2g p g 3 pp y 2g p g 3 pp y 2

Effect of methane on ozone efficiency and specific powerEffect of methane on ozone efficiency and specific power

Effect of Methane on Ozone Content in Outlet Gas and on Specific Power Pure O2

13 12

10

11

12

t 8

10

8

9

10

ne c

onte

nt w

t

6

8

ecifi

c po

wer

kW

hlb

5

6

7

Ozo

n

2

4 Spe

400E+00 20E+03 40E+03 60E+03 80E+03 10E+04 12E+04

Methane in feedgas ppm

0

Ozone content in the outlet gas Specif ic pow er of the ozone generatorg p p g

Effects of N2 and CH4Effects of N2 and CH4

Pi t f h t lli N O t tPicture of an amorphous-crystalline N2O5 structurecaptured at the Orlando Skylake water plant in 2006

Plasma Chemistry with CH4 Impurities

OxygenO2 N2

e - e -

CHO N2

NO2

O NO

O2 N O2 O3

NOH

CH4e-

O3 NO

NO2

O2O3NO N

NO2 O

NO2

NO2

N2ONO3

N

O3

NO2

NO

HNO3

N2O4

N2O5

NO2

NO3

N2O5

Effect of methane on the electrode surfaces

a) b)

Inlet Outlet Outlet

) d)

I l t I l t

c) d)

Electrode of the ozone generator afterseveral hours in CH8O2 and up to 2 wt of methane (a b c)

Inlet Inlet

three hours in CH8O2+traces of N2 and up to 1 wt of methane (d) Visible change of discharge character at about 13 length of electrode (a d)

Kinetics of CHx Conversion without N2

conversion by collisions

O2 + CHx 12wt O3 + CO2 +H2O

deposition vaporizationby sputtering

ibl b l 1000 CHreversible process below 1000ppm CH4

Effect of water on electrode surface with N2

Inlet

OutletOutlet

Electrode of the ozone generator after several hours in H OO N

Inlet

Electrode of the ozone generator after several hours in H2OO2N2

Effect of water on electrode surface

Long term effect (800 hrs) of H2OO2N2

Kinetics of CHx Conversion with N2

conversion by collisionsHNO3 formation

O2 + N2 +CHx 12wtO2 + CO2 +H2O + HNO3

deposition vaporizationby sputtering

H2O + HNO3

by sputtering

irreversible process above a N2 threshold () ltlt 1000ppm N2

sticky deposit

p 2 ( ) pp 2 any CH4 concentration (60ppm)

Plasma Chemistry with CH4 ImpuritiesPlasma Chemistry with CH4 Impurities4

bull Formation of NO and NO2 depends on O3 N2 and gas temperature Conclusion N2 admixture is the key factor

SummarySummaryyyThe mechanisms of formed NOx by-products follows the sameThe mechanisms of formed NOx by-products follows the sameprinciples as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentration

principles as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentrationozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)

ozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)g p ( g p )

The conversion of methane to OH and H2O is found to depend on

g p ( g p )

The conversion of methane to OH and H2O is found to depend ondissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)

dissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)discharge gap)discharge gap)

How do you optimize an ozone generatorg

Scientific ApproachScientific ApproachTheoretical Experimental

pppp

c [wt]

f [Hz]

c [wt]

f [Hz]

[kW]UUUβ1

1Cf4αPn

1iiminpeakimin

iiD

q [kWm2]q [kWm2]

150

180

][V]voltagepeakUpeak

[]cylinder perslicesofamountnsliceii

whereth

09 00

30

60

90

120

effic

ienc

y [

][0tdj t bl[F]sliceisdielectricofecapacitancC

[Hz]frequencyf[V]sliceivoltageminimumiUmin

thiD

th

10

28

46

64

82

39

107

176

244 power density

[kWm2]

ozone conc [wt][]CCβ

][0parameteradjustableα

iDiGi

Impact of Power Inductionp

350

400

wer

200

250

300

App

lied

Pow

Arr C 2Arr D +0

Arr E +45Arr F +7

Arr G +3

5 0

100

150

Frac

tion

of

1 2 3 4

ReferenceArr B unstable

Arr C -2

00

50

4Position (1inlet 4outlet)

Experimental Test Rigp g

Experimental Test Rigp g

Outer grounded electrode (left picture) and the dielectric covered inner electrodes (right) d e ect c cove ed e e ect odes ( g t)

Reference (Traditional) Arrangement

Inlet OutletGas flow direction

Optimized Arrangement

Inlet OutletGas flow direction

Intelligent Gap System (IGS)g p y ( )

Molecular Oxygen (O2) Ozone (O3)

O2 O3

yg ( 2) ( 3)

Particle Size SynthesisParticle Size SynthesisByBy--Products Cluster FormationProducts Cluster Formationyy

high diffusion and deposition to surfaces

low diffusion rate good transport

high sedimentation on the structurehigh sedimentation on the structure

Degreacutemont Technologies ndash OzoniaIntelligent Gap SystemIntelligent Gap System

G Vezzuacute JL Lopez A Freilich and K Becker Optimizationof Large-Scale Ozone Generators IEEE Transactions onPlasma Science Vol 37 No 6 p 890-896 (2009)

ConclusionsConclusionsConclusionsConclusionsFundamentals of ozone synthesis in a DBD plasmay p

ndash Highly filamented DBD discharges are best-suitedfor the production of ozone concentrations in therange of 6 to 14 wtrange of 6 to 14 wt

ndash The preferred characteristic of the microdischargesare Townsend-like at reduced electric fields Enaround 190 Townsend

ndash Detrimental side-effects induced by by-productscan be avoided by a proper design of the electrodecan be avoided by a proper design of the electrodearrangement The phenomenon is related to thediffusion rates of formed by-product clusters

ConclusionsConclusionsConclusionsConclusionsBenefits from DBD microplasma tailoring

ndash Reduced power consumption of up to 10 improvement

ndash Increased ozone concentrations of up to 14 now achievable

ndash Improved neutralization and conditioning of detrimental by-products

ndash Reduced system capital and operational cost

New technologies to improve ozone p

generatorg

HV Pulsed Power SwitchingHV Pulsed Power Switching

Microchannel Generation of Ozone

Channel ArrayChannel Array

Microchannel

330 microm 230 microm

Some Cap-DBD Devices Operating in Air

Increase of 60 of

Spacing 225 μmof 60 of plasma

No space

Cap‐DBD ozone generation

bull Ozone concentration is evaluated via Eco S d l UV 100 O A l (0 01Sensors model UV-100 Ozone Analyzer (001 ndash 900 ppm wiht an accuracy of plusmn2)

bull Three reactors 6 tubings 6rdquo with spacings of 0 μm 225 μm and 500 μm running at 3 kV μ μ μ g

SpacingOzone Concentration

3 kV rms 4 kV rms3 kV rms 4 kV rms

0 μm 660 ppm

225 μm 550 ppm

For a device of such small scale these ozone levels are promising

500 μm 380 ppm

J Mahoney W Zhu VS Johnson KH Becker and JL Lopez Electrical and optical emissionmeasurements of a capillary dielectric barrier discharge European Physics Journal D Vol 60 441-447(2010)

QuestionsQuestions

Thank YouFor more informationProf Jose L Lopez PhD

Thank YouFor more informationDepartment of Physics

Telephone (973) 761-9057Email joselopez1shuedu

Website wwwshueduacademicsartsciphysicsWebsite wwwshueduacademicsartsciphysics

Page 5: Dielectric Barrier Discharge (DBD) & Progress in Large ...bonitz/si12/talks/august_8/lopez_si12.pdf · Dielectric Barrier Discharge (DBD) & Progress in Large-Scale Ozone Generation

Plasma Enhanced Technology

A small section of amemory chip

Straight holes like these canbe etched with plasmasmemory chip be etched with plasmas

BirthplaceBirthplace ofof solidsolid--statestate microelectronicsmicroelectronicsBellBell LaboratoriesLaboratories MurrayMurray HillHill NJNJ

Microchip fabrication with plasmas

The US Department of Energyrsquos Princeton Plasma Physics Laboratory (PPPL) is acollaborative national center for plasma and fusion science Its primary mission is tocollaborative national center for plasma and fusion science Its primary mission is todevelop the scientific understanding and the key innovations which will lead to anattractive fusion energy source Associated missions include conducting world-classresearch along the broad frontier of plasma science and technology and providing thehighest quality of scientific education

National Spherical Torus Experiment (NSTX)

Atmospheric Cold PlasmasErich Kunhardt amp Kurt Becker

An Atmospheric Pressure Plasma Generated with a

(Courtesy of K Becker)

Capillary-Plasma-Electrode Discharge

Two Types of plasmas

bull High‐temperature plasmas (Hot Plasmas)g p p ( )Tiasymp Te ge107 Keg fusion plasmas

T asymp T asymp T le 2 x 104 KTi asymp Te asymp Tg le 2 x 104 Keg arc plasma at normal pressure

bull Low‐temperature plasmas (Cold Plasmas)Ti asymp Tg asymp 300 KT ltlt T le 105 KTi ltlt Te le 105 Keg low‐pressure glow discharge

high‐pressure cold plasma

Hot vs Cold PlasmasHot vs Cold Plasmas

LowLow--Temperature (ldquoColdrdquo) PlasmasTemperature (ldquoColdrdquo) Plasmas[Non[Non--equilibrium Nonequilibrium Non--Thermal]Thermal][Non[Non equilibrium Nonequilibrium Non Thermal]Thermal]

How do we make plasmasHow do we make plasmas

Supply Energyeg Heat transfer radiation electric powerhellip

For many plasma applicationsFor many plasma applications an Electric Field is applied to a gaseous environment

Plasma or Gaseous DischargePlasma or Gaseous Discharge

LowLow--Pressure Glow Discharge PlasmasPressure Glow Discharge Plasmas

Plasmas are easier to be generated at low pressures

Low pressure plasmas (1 T f T )

at low pressures

are well understood

are used extensively nowadays

(1 mTorr ~ a few Torr)

are used extensively nowadays (eg in semiconductor industry for computer chips manufacturing)

However to generate low pressure plasmas

vacuum chambers + + = expensive vacuum pumps

pressure monitoring and pressure control devices

+ + =Generate Plasmas at Atmospheric PressureGenerate Plasmas at Atmospheric Pressure

What happens at air pressureWhat happens at air pressure

bull No vacuum is involvedDiffi l d ibull Difficult to generate and sustain

bull Run into some challenges such as glow toarc transition ndash Non controllable

Arc Discharge thermal plasma-Itrsquos hot and detrimental-Gas temperature can reach as high as 2x104 KGas temperature can reach as high as 2x10 K- Low voltage drop at cathode- High cathode current density

High Pressure Microplasmas

Stabilization of high-pressure plasmas ldquopd scalingrdquo ldquoprdquo uarr soplasmas pd scaling p uarr so ldquodrdquo darr to keep breakdown voltage low and minimize instabilities after breakdown -

MicroplasmasDimension a few millimeterDimension a few millimeter down to and below 100 m

Paschen Breakdown CurveH H i 60 100Human Hair 60 ndash 100 m

How do we solve this problemHow do we solve this problem

Transient (pulsed) plasmas In atmospheric plasmas for efficient gas heating atleast 100-1000 collisions are necessary Thus if the plasma duration is shorterleast 100 1000 collisions are necessary Thus if the plasma duration is shorterthan 10-6 ndash 10-5 s gas heating is limited Of course for practical purposes suchplasma has to be operated in a repetitive mode eg in trains of microsecondpulses with millisecond intervals

Micro-confinement Gas heating occurs in the plasma volume and the energy iscarried away by thermal diffusionconvection to the outside If the plasma has asmall volume and a relatively large surface gas heating is limited

Dielectric Barrier Discharges These plasmas are typically created betweenmetal plates which are covered by a thin layer of dielectric or highly resistivematerial The dielectric layer plays an important role in suppressing the currentthe cathodeanode layer is charged by incoming positive ionselectrons whichreduces the electric field and hinders charge transport towards the electrodeDBD also has a large surface-to-volume ratio which promotes diffusion lossesand maintains a low gas temperatureand maintains a low gas temperature

Advantages of Microplasmas Advantages of Microplasmas

bull Low-cost of implementationpbull System flexibilitybull Atmospheric pressure operationbull High densities and high reaction ratesbull High densities and high reaction ratesbull Fast and efficient processesbull Easy to generate and sustain for a variety of gas mixtures

Gl lik d diffbull Glow-like and diffusebull Non-equilibrium (Te gt Tg) to thermalbull Unique chemistryq y

hellip a new realm of plasma sciencehellip a new realm of plasma science

What can we do with microplasmasWhat can we do with microplasmas

Material Synthesis Plasma display Surface Treatment Lighting

OzoneOzone generation for water cleaning

Bio-applicationMaterial processing Dental application

and Many morehellip

Some High Pressure microplasma reactors Some High Pressure microplasma reactors

Dielectric Barrier Discharge (DBD)Dielectric Barrier Discharge (DBD)

Hi h V l

HighVoltage

High VoltageElectrode

ACGenerator

DielectricBarrier

Generator

G

Microplasmas

GroundElectrode

Faradayrsquos Dielectric CapacitorsFaradayrsquos Dielectric Capacitors

Faradays Dielectric Capacitor (circa 1837)

Michael Faraday (1781 ndash 1867) Capacitance INCREASED

Historical Ozone Tube of W Siemens (1857)Historical Ozone Tube of W Siemens (1857)

Werner v SiemensP d frsquo A l d Ch i d Ph ik 102 66 (1857)Poggendorfrsquos Annalen der Chemie und Physik 102 66 (1857)

ldquoOzone Production in an Atmospheric-PressureDielectric Barrier Dischargerdquo

Dielectric Barrier Discharge

Dielectric Barrier DischargeDielectric - Barrier Discharge ConfigurationsHigh

VoltageAC

Generator

High VoltageElectrode

DielectricBarrier

DielectricBarrier

High VoltageElectrode

Discharge

DischargeGeneratorGround

Electrode

Electrode

GroundElectrode

Discharge

H E Wagner R Brandenburg et al lsquoThe barrier discharge basic properties and applications toHE Wagner R Brandenburg et al The barrier discharge basic properties and applications tosurface treatmentrsquo Vacuum 71 p417-436 (2003)

Typical operational conditions of barrier discharges Typical operational conditions of barrier discharges

Electric field strength E of first breakdown asymp150 Td (p = 1bar T=300 K)

Voltage Vpp 3ndash20 kV

Repetition frequency f 50 Hzndash30 kHz

Pressure p 1ndash3 bar

Gap distance g 02ndash5mm

Dielectric material thickness d 05ndash2mm

Relative dielectric permittivity r 5ndash10 (glass)

B Eliasson and U Kogelschatz IEEE Transactions Plasma Science Vol 19 Issue 6 1063-1077 (1991)B Eliasson and U Kogelschatz IEEE Transactions Plasma Science Vol 19 Issue 6 1063-1077 (1991)

Single and double DBD

Single dielectric Double dielectric

Role of the Dielectric (Insulator)

Th di l t i i th k f thThe dielectric is the key for the properfunctioning of the discharge

Serves two functions

1 Limits the amount of charge transportedby a single microplasma

2 Distributes the microplasmas over theentire electrode surface area

Equivalent Circuit of a Microdischarge

Microdischarge Activity and U-Q Lissajous Figure

B Eliasson and U Kogelschatz IEEE Transactions Plasma Science Vol 19 Issue 6 1063-1077 (1991)

Fundamental Operation of the Dielectric Barrier DischargeFundamental Operation of the Dielectric Barrier Discharge

bull Many of relevant plasma processes that areof importance to achieving our goal occuron time scales that allow us to study themon time scales that allow us to study them

bull Optical emission spectroscopic studies willallow us to determine the temporal andspatial development of important plasmaspatial development of important plasmaspecies such as radicals (OH NO variousoxygen radicals) with high time resolution(less than 10 ns) and a spatial resolution onthe scale of mm in the plasma volumepfollowing pulsed plasma excitation

Time scale of the relevant processes of the DBD

HE Wagner R Brandenburg et al lsquoThe barrier discharge basic properties and applications tosurface treatmentrsquo Vacuum 71 417-436 (2003)

Fundamental Operation of the DBDFundamental Operation of the DBD

Electron DensityTemporal Development (ns)

y

Outer Contour Linen = 1010 cm-3ne = 1010 cm 3

Inner Contour Linene = 1014 cm-3

Streamer Propagation in 1 bar AirAA Kulikovsky IEEE Trans Plasma Sci 25 439-446 (1997)

Numerical Results of Microdischarge Formationin Dielectric Barrier Discharges

Starting Phase of a Microdischarge (1 bar 20 CO2 80 H2)

E0=34 kVcm1010 cm-3

1010 cm-3 ne=1012 cm-3

1mm10 cm

ne=108 cm-3

An electron avalanche propagates towards the anode

Reverse propagationtowards the cathodepropagates towards the anode towards the cathode

Numerical Results of Microdischarge Formationin Dielectric Barrier Discharges

Cathode Layer Formation

E0=34 kVcm1010 cm-39 3 0

1mm

1010 cm-3

10 cmne=109 cm-31014

10131014

1013

10 cm1012

Just before the peak of the total current

Peak currentof the total current

Numerical Results of Microdischarge Formationin Dielectric Barrier Discharges

Local Field Collapse in Area Defined by Surface Discharge

ne=109cm-3 ne=1014 cm-3

Gap

Principals of DBD MicroplasmasPrincipals of DBD MicroplasmasPrincipals of DBD MicroplasmasPrincipals of DBD Microplasmas

C C-- - --- - - CG

CD

-- - - CG

CD

Principals of DBD MicroplasmasPrincipals of DBD MicroplasmasPrincipals of DBD MicroplasmasPrincipals of DBD Microplasmas

Dielectric Barrier Discharge (DBD)Dielectric Barrier Discharge (DBD)Electric Field

B kdBreakdown

Electrons amp Ions Discharge Physics

Excited SpeciesPlasma Chemistry

Chemical Reactions

OzoneGeneration

SurfaceTreatment

PollutionControl

ExcimerFormation CO2 Lasers Hydrogenation

of CO2

Excimer Lamps Plasma Displays

How A Plasma Display Works

How A Plasma Display Work

Plasma Display TelevisionsPlasma Display Televisions

Ozone Generator

3 O 2 O

Dielectric Barrier Discharge

3 O2 2 O3

OO22 OO33++OO22Ondash ndashO3O2

O2O2

Ondash ndash

endash O2Ondash ndash O2endash

O3

O3O2O2 O2

HeatHeatHeatHeat

Properties of Ozone (O3)

T i t i f f Tri-atomic form of oxygen

Most powerful commercial oxidizing agent

Unstable - must be generated and used onsite

Limited solubility in water but more so than oxygenLimited solubility in water but more so than oxygen

Leaves a dissolved residual which ultimately converts back to oxygenconverts back to oxygen

Discharge Tubes in Ozone GeneratorsDischarge Tubes in Ozone Generators

Traditional

Ozone Generator

with Glass Tubes

Generation of OzoneGeneration of Ozone

Generation of OzoneAdvantages of Enamel Dielectrics

Proven Patented Designbull Simplicity

Si l Di l i Cbull Single Dielectric Componentndash Reduced number of Dielectrics

bull Safety ndash Lower operating voltage

(lt 4000 V)bull Reliabilty

ndash Fused Dielectrics ensure continuous production

bull Lowest Power Consumption Operational Savingsndash Operational Savings

Modern Ozone GeneratorModern Ozone Generator

Ozonia Advanced Technology Ozone GeneratorOzone Generator

Generation of OzoneGeneration of Ozone

Generation of Ozone

Power Supply UnitPower Supply Unit

IGBT Inverter CircuitMain Circuit Breaker

HV 480 Volts60 Hz3 Phase Supply

C I

450KVAPow er to

GeneratorFILTER

CONVERTER INVERTERTRANSFORMER

C I450KVA Power Stage

CONTACTOR

bull Latest in Power Semiconductor Technology Modular Design

bull Utilizes IGBTrsquos (Insulated Gate Bi‐Polar Transistors) Converter and Inverter Components

Ozone Water Treatment

B bbl Diff iB bbl Diff iBubble DiffusionBubble Diffusion

Easy to use

Low energy usage Low energy usage

Mass transfer efficiencies to gt 90

Ozone Process Flow DiagramOzone Process Flow DiagramVent to

Atmosphere

O OOxygen

Off-Gas Blower

Ozone Destruct Unit

10 12

O3O2

LOX

10-12 O3

Ozone Generators

Ozone Contact ChamberLOX T k Generators Chamber

VaporizersLOX Tank

Municipal Ozone Installations

Ozonia Installations Ozone Plant Size [lbday] Start-Up DateKey Ozonia Installations (Partial List)

Los Angeles CA 10000 1986Fairfax VA ndash Corbalis 9000 2003MWD CA ndash Mills 9 000 2003

Ozonia Installations Ozone Plant Size [lbday] Start Up Date

MWD CA Mills 9000 2003Fairfax Co VA ndash Griffith 9000 2004MWD CA ndash Jensen 18750 2005Indianapolis IN ndash Belmont AWT 12000 2007I di li IN 12 000 2007Indianapolis IN ndash Southport AWT 12000 2007MWD CA ndash Diemer 13400 2008MWD CA ndash Weymouth 13400 2009

Ozonia North America - Potable Water SummaryTotal Number of Installations 90Total Installed Production gt 265000 lbsdayTotal Installed Production 265000 lbsday

Revision -B

Ozone Water TreatmentOzone Water Treatment

MWD Mills WTP - California

3 3 000 lbsda of o one3 3 000 lbsda of o one3 x 3000 lbsday of ozone3 x 3000 lbsday of ozone

Ozone Water TreatmentOzone Water TreatmentOzone Ozone -- How it worksHow it works

OxidantOxidant DisinfectantDisinfectant

bullbull Breaks double carbon Breaks double carbon bondsbonds

bullbull Kills by cell lysing or Kills by cell lysing or causing the cell wall tocausing the cell wall tobondsbonds

bullbull Creates OHCreates OHbullbull radicals radicals which break higher carbon which break higher carbon

causing the cell wall to causing the cell wall to rupture rupture

bullbull AttacksAttacks allall bacteriabacteriabondsbondsbullbull Increased temp and pH Increased temp and pH

accelerates Oaccelerates O33

Attacks Attacks allall bacteria bacteria virus cysts and spores virus cysts and spores in varying degreesin varying degreesaccelerates Oaccelerates O33

decomposition to OHdecomposition to OHbullbull

Micro-organism DNA

Capsule AdenineAdenine

Cell wall ThymineThymine

CytosineCytosine

GuanineGuanine

NuclearmaterialCellmembrane

material

Typical Bacterium DNA

Microbial Growth at Various Ozone ConcentrationsConcentrations

Growth likely

Growth possibleGrowth possible

NO GROWTH

0004 0008 0012 0016 0020

Ozone concentration (mgl)Ozone concentration (mgl)

Typical Water Treatment UsageTypical Water Treatment Usage

Application O3 mgl Contact timeUltra Pure Water 005 - 025 sec ndash min

Water bottling 04 ndash 10 5 ndash 10 min

Swimming pools ampspas

01 ndash 075 4 minutes

Potable taste amp odor 15 ndash 50 5 ndash 10 mindisinfection

Microfloculation 10 ndash 30 5 ndash 10 min

Lignin amp tammin 3 0 10 0 10 30 minLignin amp tamminremoval

30 ndash 100 10 ndash 30 min

Municipal wastewater 50 ndash 150+ 15 ndash 30 min

Ozone Water TreatmentOzone Water TreatmentOzone Ozone ndashndash Municipal ApplicationsMunicipal Applications

bullbull Taste and OdorTaste and Odor

bullbull Color RemovalColor Removal

bullbull Disinfection Without Trihalomethanes (THMs)Disinfection Without Trihalomethanes (THMs)

bullbull Improved Filtration Efficiency and FlocculationImproved Filtration Efficiency and Flocculation

bullbull Cryptosporidium DeactivationCryptosporidium Deactivation

bullbull Giardia amp Virus InactivationGiardia amp Virus Inactivation

bullbull Oxidation Oxidation -- Organics Fe amp MnOrganics Fe amp Mn

bullbull Wastewater disinfectionWastewater disinfection

bullbull BOD COD and TOC reductionBOD COD and TOC reduction

Applications of Ozone

Wastewater Treatmentbull Disinfection of Secondary and Tertiary Effluentsbull Color Reductionbull Color Reductionbull TOC Oxidation (Industrial)bull Oxidation of Odor Causing Compoundsbull Oxidation of Endocrine Disruptors (EDCrsquos) and p ( )

Pharmaceutically Active Compounds (PACrsquos)

Applications of Ozone

What are Endocrine Disruptors (EDCrsquos) and What are Endocrine Disruptors (EDCrsquos) and Ph ti ll A ti C d (PACrsquo )Ph ti ll A ti C d (PACrsquo )Pharmaceutically Active Compounds (PACrsquos)Pharmaceutically Active Compounds (PACrsquos)

bullbull EDCrsquosEDCrsquos andand PACrsquosPACrsquos areare NaturallyNaturally andand SyntheticSyntheticdd th tth t ff tff t thth b lb l llcompoundscompounds thatthat maymay affectaffect thethe balancebalance oror normalnormal

functionsfunctions inin animalsanimals andand humanshumans

What can EDCrsquos and PACrsquos doWhat can EDCrsquos and PACrsquos do

bullbull Even in very small concentrations these compounds Even in very small concentrations these compounds y py pcan can disruptdisrupt normal bodily functionsnormal bodily functions

bullbull ManMan--made chemicals can trick the bodies endocrine made chemicals can trick the bodies endocrine system system

Applications of Ozone

Examples of Endocrine Disruptors1000rsquos of compounds that may be Investigated as EDCs ndash Some examples are

bullbull Synthetic HormonesSynthetic Hormonesbullbull Naturally Occurring Estrogens Naturally Occurring Estrogens

Health and Beauty AidsHealth and Beauty Aidsbullbull Health and Beauty AidsHealth and Beauty Aidsbullbull SolventsSolventsbullbull PesticidesPesticidesbullbull SurfactantsSurfactantsbullbull PlasticsPlastics

F i idF i idbullbull FungicidesFungicides

Ozone Water TreatmentOzone Water Treatment

Ozone Ozone -- Industrial ApplicationsIndustrial Applications-- Ultrapure Water for Pharmaceutical ApplicationsUltrapure Water for Pharmaceutical Applications

-- Wastewater disinfection color removalWastewater disinfection color removal

-- Soil and Groundwater Remediation Soil and Groundwater Remediation

-- Cooling Tower Water TreatmentCooling Tower Water Treatment

-- Food ProcessingFood Processing

-- Aquaculture AquariumsAquaculture AquariumsAquaculture AquariumsAquaculture Aquariums

-- Beverage ApplicationsBeverage Applications

P l amp P Bl hiP l amp P Bl hi-- Pulp amp Paper BleachingPulp amp Paper Bleaching

High Purity OzonationHigh Purity Ozonation

Microchip manufacturingMicrochip manufacturing

What are the current issues in large-scale gozone generationg

Experimental Setup

Front view of the two units after the redesign and reworking ofthe gas water and instruments connectionsthe gas water and instruments connections

Experimental Setup

Top view of the twoexperimental unitsexperimental unitsSpectroscope (notshown) is to the left ofthe DBD The units weredifferent with respect todifferent with respect totheir electrodes onehad only the electrodecoated with thedielectric (ldquosingle-dielectric ( single-coatedrdquo) the other onehad the electrode andthe anode coated withthe dielectric (ldquodouble-the dielectric ( double-coatedrdquo)

Basics Generation of OzoneBasics Generation of Ozone

SpectroscopyPlasma

Plasma Absorption SpectroscopyPlasma Absorption Spectroscopy

Infrared Absorption SpectroscopyInfrared Absorption Spectroscopy

IR spectra in pure oxygen (black curve) and at approximately 10wt N2 admixture (red line) N2O5 peaks appear at124 1 d 1 2 11245 cm-1 and at 1725 cm-1

Infrared Absorption SpectroscopyInfrared Absorption Spectroscopy

IR spectra of several methane variations The green curve envelopes all of the methane peaks at 1325 cm-1recorded at smaller methane admixtures Simultaneously the N2O5 peaks disappear as the methane peaks appear

N2O5 FormationN2O5 Formation2 52 5p=2 bara cwt=20degC q=35kWm2 f=1450Hz

45N2O5 AT95

30

35

40

N

2 B

lend

ing

N2O AT95N2O5 IGSN2O IGSN2O5 LGN2O LG

1 5

20

25

nt [p

pmV]

3

wt

05

10

15

NO

x co

nten

005 7 9 11 13 15 17

ozone conc [wt]

Amount of formed N2O5 and N2O as a function of ozone concentration at 3 wt of nitrogen admixture and fori l dvarious electrode arrangements

Plasma Emission SpectroscopyPlasma Emission Spectroscopyp pyp py

Relative Emissions of the Ozonizer plasmaRelative Emissions of the Ozonizer plasma

Region 300- 850 nm from individual (calibrated) regions (smoothed by PeakFit) Single-coated ozone generator Inlet side

3 5E+06

30E+06

35E+06

7 9

20E+06

25E+06

nten

sity

au

2

311 12

10E+06

15E+06

In 4

5

6 8 10

14

15

16

17

00E+00

50E+05

280 300 320 340 360 380 400 420 440 460 480 500 520 540 560 580 600 620 640 660 680 700 720 740 760 780 800 820 840 860

Wavelength nm

1 13

Wavelength nm

Absolute Emission of the DBD PlasmaAbsolute Emission of the DBD Plasma

Intensities in (O2+3 wtN2) plasma

1 20E+04

100E+04

120E+04

600E+03

800E+03

nten

sity

(au

)

200E+03

400E+03

In

O(777)

000E+00200 250 300 350 400 450 500 550 600 650 700 750 800 850

Wavelength nm

Intensities in 3 wtN2+O2 plasmaIntensities in 3 wtN2+O2 plasma

Plasma Chemistry in OzonizersPlasma Chemistry in Ozonizers

Dry Air O2 N2

e - e -

O N2 N O2

O3 NO

O2 N O2

O3

N

3

NO2

O2 O3

NO

N

NO2 O3

N2O

NO3 N

N2O4

NO2

NO2

N2O5

NO3

Primary electron-driven chemical reactions leading to the formation of N2O5 and N2O in a dry air plasma

Plasma emission diagnostics role of N2Plasma emission diagnostics role of N2

Dry Air O2 N2

e - e -

O N2 N O2

O3 NO

O2 N O2

O3

O

N

ON

NO2

O2O3

N

NO N

NO2 O3

N2O

NO3 N

N2O4

NO2

NO2

N2O5

NO3

ONbullWith N2 present ndash less oxygen atoms are formed However the difference in intensity is

very small

Modeling of plasma chemistry incl the NxOy chemistry up to N2O5 for different Oxygen Nitrogen mixtures varying power deposition scenarios

and initial ozone background concentrations (up to 15) previously done

The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation

The role of N2 must be related to its by-products reacting on the surface of the electrodeThe role of N2 must be related to its by-products reacting on the surface of the electrode

The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established

Ab 8 t f O

The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established

Ab 8 t f OAbove 8 wt of O3

1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)

Above 8 wt of O3

1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)case without pampp)

2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of the

case without pampp)

2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of thethem A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface

them A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface

The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation

Three possibilities have to be considered for the oxygen-fedozone generator

Three possibilities have to be considered for the oxygen-fedozone generatorozone generator

bull Excited N2 molecules lead to an increased O2 dissociation in

ozone generator

bull Excited N2 molecules lead to an increased O2 dissociation in2 2such case an increased efficiency is correlated to the N2admixture

2 2such case an increased efficiency is correlated to the N2admixture

bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial

bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial

bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2

bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2g p g 3 pp y 2g p g 3 pp y 2

Effect of methane on ozone efficiency and specific powerEffect of methane on ozone efficiency and specific power

Effect of Methane on Ozone Content in Outlet Gas and on Specific Power Pure O2

13 12

10

11

12

t 8

10

8

9

10

ne c

onte

nt w

t

6

8

ecifi

c po

wer

kW

hlb

5

6

7

Ozo

n

2

4 Spe

400E+00 20E+03 40E+03 60E+03 80E+03 10E+04 12E+04

Methane in feedgas ppm

0

Ozone content in the outlet gas Specif ic pow er of the ozone generatorg p p g

Effects of N2 and CH4Effects of N2 and CH4

Pi t f h t lli N O t tPicture of an amorphous-crystalline N2O5 structurecaptured at the Orlando Skylake water plant in 2006

Plasma Chemistry with CH4 Impurities

OxygenO2 N2

e - e -

CHO N2

NO2

O NO

O2 N O2 O3

NOH

CH4e-

O3 NO

NO2

O2O3NO N

NO2 O

NO2

NO2

N2ONO3

N

O3

NO2

NO

HNO3

N2O4

N2O5

NO2

NO3

N2O5

Effect of methane on the electrode surfaces

a) b)

Inlet Outlet Outlet

) d)

I l t I l t

c) d)

Electrode of the ozone generator afterseveral hours in CH8O2 and up to 2 wt of methane (a b c)

Inlet Inlet

three hours in CH8O2+traces of N2 and up to 1 wt of methane (d) Visible change of discharge character at about 13 length of electrode (a d)

Kinetics of CHx Conversion without N2

conversion by collisions

O2 + CHx 12wt O3 + CO2 +H2O

deposition vaporizationby sputtering

ibl b l 1000 CHreversible process below 1000ppm CH4

Effect of water on electrode surface with N2

Inlet

OutletOutlet

Electrode of the ozone generator after several hours in H OO N

Inlet

Electrode of the ozone generator after several hours in H2OO2N2

Effect of water on electrode surface

Long term effect (800 hrs) of H2OO2N2

Kinetics of CHx Conversion with N2

conversion by collisionsHNO3 formation

O2 + N2 +CHx 12wtO2 + CO2 +H2O + HNO3

deposition vaporizationby sputtering

H2O + HNO3

by sputtering

irreversible process above a N2 threshold () ltlt 1000ppm N2

sticky deposit

p 2 ( ) pp 2 any CH4 concentration (60ppm)

Plasma Chemistry with CH4 ImpuritiesPlasma Chemistry with CH4 Impurities4

bull Formation of NO and NO2 depends on O3 N2 and gas temperature Conclusion N2 admixture is the key factor

SummarySummaryyyThe mechanisms of formed NOx by-products follows the sameThe mechanisms of formed NOx by-products follows the sameprinciples as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentration

principles as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentrationozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)

ozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)g p ( g p )

The conversion of methane to OH and H2O is found to depend on

g p ( g p )

The conversion of methane to OH and H2O is found to depend ondissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)

dissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)discharge gap)discharge gap)

How do you optimize an ozone generatorg

Scientific ApproachScientific ApproachTheoretical Experimental

pppp

c [wt]

f [Hz]

c [wt]

f [Hz]

[kW]UUUβ1

1Cf4αPn

1iiminpeakimin

iiD

q [kWm2]q [kWm2]

150

180

][V]voltagepeakUpeak

[]cylinder perslicesofamountnsliceii

whereth

09 00

30

60

90

120

effic

ienc

y [

][0tdj t bl[F]sliceisdielectricofecapacitancC

[Hz]frequencyf[V]sliceivoltageminimumiUmin

thiD

th

10

28

46

64

82

39

107

176

244 power density

[kWm2]

ozone conc [wt][]CCβ

][0parameteradjustableα

iDiGi

Impact of Power Inductionp

350

400

wer

200

250

300

App

lied

Pow

Arr C 2Arr D +0

Arr E +45Arr F +7

Arr G +3

5 0

100

150

Frac

tion

of

1 2 3 4

ReferenceArr B unstable

Arr C -2

00

50

4Position (1inlet 4outlet)

Experimental Test Rigp g

Experimental Test Rigp g

Outer grounded electrode (left picture) and the dielectric covered inner electrodes (right) d e ect c cove ed e e ect odes ( g t)

Reference (Traditional) Arrangement

Inlet OutletGas flow direction

Optimized Arrangement

Inlet OutletGas flow direction

Intelligent Gap System (IGS)g p y ( )

Molecular Oxygen (O2) Ozone (O3)

O2 O3

yg ( 2) ( 3)

Particle Size SynthesisParticle Size SynthesisByBy--Products Cluster FormationProducts Cluster Formationyy

high diffusion and deposition to surfaces

low diffusion rate good transport

high sedimentation on the structurehigh sedimentation on the structure

Degreacutemont Technologies ndash OzoniaIntelligent Gap SystemIntelligent Gap System

G Vezzuacute JL Lopez A Freilich and K Becker Optimizationof Large-Scale Ozone Generators IEEE Transactions onPlasma Science Vol 37 No 6 p 890-896 (2009)

ConclusionsConclusionsConclusionsConclusionsFundamentals of ozone synthesis in a DBD plasmay p

ndash Highly filamented DBD discharges are best-suitedfor the production of ozone concentrations in therange of 6 to 14 wtrange of 6 to 14 wt

ndash The preferred characteristic of the microdischargesare Townsend-like at reduced electric fields Enaround 190 Townsend

ndash Detrimental side-effects induced by by-productscan be avoided by a proper design of the electrodecan be avoided by a proper design of the electrodearrangement The phenomenon is related to thediffusion rates of formed by-product clusters

ConclusionsConclusionsConclusionsConclusionsBenefits from DBD microplasma tailoring

ndash Reduced power consumption of up to 10 improvement

ndash Increased ozone concentrations of up to 14 now achievable

ndash Improved neutralization and conditioning of detrimental by-products

ndash Reduced system capital and operational cost

New technologies to improve ozone p

generatorg

HV Pulsed Power SwitchingHV Pulsed Power Switching

Microchannel Generation of Ozone

Channel ArrayChannel Array

Microchannel

330 microm 230 microm

Some Cap-DBD Devices Operating in Air

Increase of 60 of

Spacing 225 μmof 60 of plasma

No space

Cap‐DBD ozone generation

bull Ozone concentration is evaluated via Eco S d l UV 100 O A l (0 01Sensors model UV-100 Ozone Analyzer (001 ndash 900 ppm wiht an accuracy of plusmn2)

bull Three reactors 6 tubings 6rdquo with spacings of 0 μm 225 μm and 500 μm running at 3 kV μ μ μ g

SpacingOzone Concentration

3 kV rms 4 kV rms3 kV rms 4 kV rms

0 μm 660 ppm

225 μm 550 ppm

For a device of such small scale these ozone levels are promising

500 μm 380 ppm

J Mahoney W Zhu VS Johnson KH Becker and JL Lopez Electrical and optical emissionmeasurements of a capillary dielectric barrier discharge European Physics Journal D Vol 60 441-447(2010)

QuestionsQuestions

Thank YouFor more informationProf Jose L Lopez PhD

Thank YouFor more informationDepartment of Physics

Telephone (973) 761-9057Email joselopez1shuedu

Website wwwshueduacademicsartsciphysicsWebsite wwwshueduacademicsartsciphysics

Page 6: Dielectric Barrier Discharge (DBD) & Progress in Large ...bonitz/si12/talks/august_8/lopez_si12.pdf · Dielectric Barrier Discharge (DBD) & Progress in Large-Scale Ozone Generation

The US Department of Energyrsquos Princeton Plasma Physics Laboratory (PPPL) is acollaborative national center for plasma and fusion science Its primary mission is tocollaborative national center for plasma and fusion science Its primary mission is todevelop the scientific understanding and the key innovations which will lead to anattractive fusion energy source Associated missions include conducting world-classresearch along the broad frontier of plasma science and technology and providing thehighest quality of scientific education

National Spherical Torus Experiment (NSTX)

Atmospheric Cold PlasmasErich Kunhardt amp Kurt Becker

An Atmospheric Pressure Plasma Generated with a

(Courtesy of K Becker)

Capillary-Plasma-Electrode Discharge

Two Types of plasmas

bull High‐temperature plasmas (Hot Plasmas)g p p ( )Tiasymp Te ge107 Keg fusion plasmas

T asymp T asymp T le 2 x 104 KTi asymp Te asymp Tg le 2 x 104 Keg arc plasma at normal pressure

bull Low‐temperature plasmas (Cold Plasmas)Ti asymp Tg asymp 300 KT ltlt T le 105 KTi ltlt Te le 105 Keg low‐pressure glow discharge

high‐pressure cold plasma

Hot vs Cold PlasmasHot vs Cold Plasmas

LowLow--Temperature (ldquoColdrdquo) PlasmasTemperature (ldquoColdrdquo) Plasmas[Non[Non--equilibrium Nonequilibrium Non--Thermal]Thermal][Non[Non equilibrium Nonequilibrium Non Thermal]Thermal]

How do we make plasmasHow do we make plasmas

Supply Energyeg Heat transfer radiation electric powerhellip

For many plasma applicationsFor many plasma applications an Electric Field is applied to a gaseous environment

Plasma or Gaseous DischargePlasma or Gaseous Discharge

LowLow--Pressure Glow Discharge PlasmasPressure Glow Discharge Plasmas

Plasmas are easier to be generated at low pressures

Low pressure plasmas (1 T f T )

at low pressures

are well understood

are used extensively nowadays

(1 mTorr ~ a few Torr)

are used extensively nowadays (eg in semiconductor industry for computer chips manufacturing)

However to generate low pressure plasmas

vacuum chambers + + = expensive vacuum pumps

pressure monitoring and pressure control devices

+ + =Generate Plasmas at Atmospheric PressureGenerate Plasmas at Atmospheric Pressure

What happens at air pressureWhat happens at air pressure

bull No vacuum is involvedDiffi l d ibull Difficult to generate and sustain

bull Run into some challenges such as glow toarc transition ndash Non controllable

Arc Discharge thermal plasma-Itrsquos hot and detrimental-Gas temperature can reach as high as 2x104 KGas temperature can reach as high as 2x10 K- Low voltage drop at cathode- High cathode current density

High Pressure Microplasmas

Stabilization of high-pressure plasmas ldquopd scalingrdquo ldquoprdquo uarr soplasmas pd scaling p uarr so ldquodrdquo darr to keep breakdown voltage low and minimize instabilities after breakdown -

MicroplasmasDimension a few millimeterDimension a few millimeter down to and below 100 m

Paschen Breakdown CurveH H i 60 100Human Hair 60 ndash 100 m

How do we solve this problemHow do we solve this problem

Transient (pulsed) plasmas In atmospheric plasmas for efficient gas heating atleast 100-1000 collisions are necessary Thus if the plasma duration is shorterleast 100 1000 collisions are necessary Thus if the plasma duration is shorterthan 10-6 ndash 10-5 s gas heating is limited Of course for practical purposes suchplasma has to be operated in a repetitive mode eg in trains of microsecondpulses with millisecond intervals

Micro-confinement Gas heating occurs in the plasma volume and the energy iscarried away by thermal diffusionconvection to the outside If the plasma has asmall volume and a relatively large surface gas heating is limited

Dielectric Barrier Discharges These plasmas are typically created betweenmetal plates which are covered by a thin layer of dielectric or highly resistivematerial The dielectric layer plays an important role in suppressing the currentthe cathodeanode layer is charged by incoming positive ionselectrons whichreduces the electric field and hinders charge transport towards the electrodeDBD also has a large surface-to-volume ratio which promotes diffusion lossesand maintains a low gas temperatureand maintains a low gas temperature

Advantages of Microplasmas Advantages of Microplasmas

bull Low-cost of implementationpbull System flexibilitybull Atmospheric pressure operationbull High densities and high reaction ratesbull High densities and high reaction ratesbull Fast and efficient processesbull Easy to generate and sustain for a variety of gas mixtures

Gl lik d diffbull Glow-like and diffusebull Non-equilibrium (Te gt Tg) to thermalbull Unique chemistryq y

hellip a new realm of plasma sciencehellip a new realm of plasma science

What can we do with microplasmasWhat can we do with microplasmas

Material Synthesis Plasma display Surface Treatment Lighting

OzoneOzone generation for water cleaning

Bio-applicationMaterial processing Dental application

and Many morehellip

Some High Pressure microplasma reactors Some High Pressure microplasma reactors

Dielectric Barrier Discharge (DBD)Dielectric Barrier Discharge (DBD)

Hi h V l

HighVoltage

High VoltageElectrode

ACGenerator

DielectricBarrier

Generator

G

Microplasmas

GroundElectrode

Faradayrsquos Dielectric CapacitorsFaradayrsquos Dielectric Capacitors

Faradays Dielectric Capacitor (circa 1837)

Michael Faraday (1781 ndash 1867) Capacitance INCREASED

Historical Ozone Tube of W Siemens (1857)Historical Ozone Tube of W Siemens (1857)

Werner v SiemensP d frsquo A l d Ch i d Ph ik 102 66 (1857)Poggendorfrsquos Annalen der Chemie und Physik 102 66 (1857)

ldquoOzone Production in an Atmospheric-PressureDielectric Barrier Dischargerdquo

Dielectric Barrier Discharge

Dielectric Barrier DischargeDielectric - Barrier Discharge ConfigurationsHigh

VoltageAC

Generator

High VoltageElectrode

DielectricBarrier

DielectricBarrier

High VoltageElectrode

Discharge

DischargeGeneratorGround

Electrode

Electrode

GroundElectrode

Discharge

H E Wagner R Brandenburg et al lsquoThe barrier discharge basic properties and applications toHE Wagner R Brandenburg et al The barrier discharge basic properties and applications tosurface treatmentrsquo Vacuum 71 p417-436 (2003)

Typical operational conditions of barrier discharges Typical operational conditions of barrier discharges

Electric field strength E of first breakdown asymp150 Td (p = 1bar T=300 K)

Voltage Vpp 3ndash20 kV

Repetition frequency f 50 Hzndash30 kHz

Pressure p 1ndash3 bar

Gap distance g 02ndash5mm

Dielectric material thickness d 05ndash2mm

Relative dielectric permittivity r 5ndash10 (glass)

B Eliasson and U Kogelschatz IEEE Transactions Plasma Science Vol 19 Issue 6 1063-1077 (1991)B Eliasson and U Kogelschatz IEEE Transactions Plasma Science Vol 19 Issue 6 1063-1077 (1991)

Single and double DBD

Single dielectric Double dielectric

Role of the Dielectric (Insulator)

Th di l t i i th k f thThe dielectric is the key for the properfunctioning of the discharge

Serves two functions

1 Limits the amount of charge transportedby a single microplasma

2 Distributes the microplasmas over theentire electrode surface area

Equivalent Circuit of a Microdischarge

Microdischarge Activity and U-Q Lissajous Figure

B Eliasson and U Kogelschatz IEEE Transactions Plasma Science Vol 19 Issue 6 1063-1077 (1991)

Fundamental Operation of the Dielectric Barrier DischargeFundamental Operation of the Dielectric Barrier Discharge

bull Many of relevant plasma processes that areof importance to achieving our goal occuron time scales that allow us to study themon time scales that allow us to study them

bull Optical emission spectroscopic studies willallow us to determine the temporal andspatial development of important plasmaspatial development of important plasmaspecies such as radicals (OH NO variousoxygen radicals) with high time resolution(less than 10 ns) and a spatial resolution onthe scale of mm in the plasma volumepfollowing pulsed plasma excitation

Time scale of the relevant processes of the DBD

HE Wagner R Brandenburg et al lsquoThe barrier discharge basic properties and applications tosurface treatmentrsquo Vacuum 71 417-436 (2003)

Fundamental Operation of the DBDFundamental Operation of the DBD

Electron DensityTemporal Development (ns)

y

Outer Contour Linen = 1010 cm-3ne = 1010 cm 3

Inner Contour Linene = 1014 cm-3

Streamer Propagation in 1 bar AirAA Kulikovsky IEEE Trans Plasma Sci 25 439-446 (1997)

Numerical Results of Microdischarge Formationin Dielectric Barrier Discharges

Starting Phase of a Microdischarge (1 bar 20 CO2 80 H2)

E0=34 kVcm1010 cm-3

1010 cm-3 ne=1012 cm-3

1mm10 cm

ne=108 cm-3

An electron avalanche propagates towards the anode

Reverse propagationtowards the cathodepropagates towards the anode towards the cathode

Numerical Results of Microdischarge Formationin Dielectric Barrier Discharges

Cathode Layer Formation

E0=34 kVcm1010 cm-39 3 0

1mm

1010 cm-3

10 cmne=109 cm-31014

10131014

1013

10 cm1012

Just before the peak of the total current

Peak currentof the total current

Numerical Results of Microdischarge Formationin Dielectric Barrier Discharges

Local Field Collapse in Area Defined by Surface Discharge

ne=109cm-3 ne=1014 cm-3

Gap

Principals of DBD MicroplasmasPrincipals of DBD MicroplasmasPrincipals of DBD MicroplasmasPrincipals of DBD Microplasmas

C C-- - --- - - CG

CD

-- - - CG

CD

Principals of DBD MicroplasmasPrincipals of DBD MicroplasmasPrincipals of DBD MicroplasmasPrincipals of DBD Microplasmas

Dielectric Barrier Discharge (DBD)Dielectric Barrier Discharge (DBD)Electric Field

B kdBreakdown

Electrons amp Ions Discharge Physics

Excited SpeciesPlasma Chemistry

Chemical Reactions

OzoneGeneration

SurfaceTreatment

PollutionControl

ExcimerFormation CO2 Lasers Hydrogenation

of CO2

Excimer Lamps Plasma Displays

How A Plasma Display Works

How A Plasma Display Work

Plasma Display TelevisionsPlasma Display Televisions

Ozone Generator

3 O 2 O

Dielectric Barrier Discharge

3 O2 2 O3

OO22 OO33++OO22Ondash ndashO3O2

O2O2

Ondash ndash

endash O2Ondash ndash O2endash

O3

O3O2O2 O2

HeatHeatHeatHeat

Properties of Ozone (O3)

T i t i f f Tri-atomic form of oxygen

Most powerful commercial oxidizing agent

Unstable - must be generated and used onsite

Limited solubility in water but more so than oxygenLimited solubility in water but more so than oxygen

Leaves a dissolved residual which ultimately converts back to oxygenconverts back to oxygen

Discharge Tubes in Ozone GeneratorsDischarge Tubes in Ozone Generators

Traditional

Ozone Generator

with Glass Tubes

Generation of OzoneGeneration of Ozone

Generation of OzoneAdvantages of Enamel Dielectrics

Proven Patented Designbull Simplicity

Si l Di l i Cbull Single Dielectric Componentndash Reduced number of Dielectrics

bull Safety ndash Lower operating voltage

(lt 4000 V)bull Reliabilty

ndash Fused Dielectrics ensure continuous production

bull Lowest Power Consumption Operational Savingsndash Operational Savings

Modern Ozone GeneratorModern Ozone Generator

Ozonia Advanced Technology Ozone GeneratorOzone Generator

Generation of OzoneGeneration of Ozone

Generation of Ozone

Power Supply UnitPower Supply Unit

IGBT Inverter CircuitMain Circuit Breaker

HV 480 Volts60 Hz3 Phase Supply

C I

450KVAPow er to

GeneratorFILTER

CONVERTER INVERTERTRANSFORMER

C I450KVA Power Stage

CONTACTOR

bull Latest in Power Semiconductor Technology Modular Design

bull Utilizes IGBTrsquos (Insulated Gate Bi‐Polar Transistors) Converter and Inverter Components

Ozone Water Treatment

B bbl Diff iB bbl Diff iBubble DiffusionBubble Diffusion

Easy to use

Low energy usage Low energy usage

Mass transfer efficiencies to gt 90

Ozone Process Flow DiagramOzone Process Flow DiagramVent to

Atmosphere

O OOxygen

Off-Gas Blower

Ozone Destruct Unit

10 12

O3O2

LOX

10-12 O3

Ozone Generators

Ozone Contact ChamberLOX T k Generators Chamber

VaporizersLOX Tank

Municipal Ozone Installations

Ozonia Installations Ozone Plant Size [lbday] Start-Up DateKey Ozonia Installations (Partial List)

Los Angeles CA 10000 1986Fairfax VA ndash Corbalis 9000 2003MWD CA ndash Mills 9 000 2003

Ozonia Installations Ozone Plant Size [lbday] Start Up Date

MWD CA Mills 9000 2003Fairfax Co VA ndash Griffith 9000 2004MWD CA ndash Jensen 18750 2005Indianapolis IN ndash Belmont AWT 12000 2007I di li IN 12 000 2007Indianapolis IN ndash Southport AWT 12000 2007MWD CA ndash Diemer 13400 2008MWD CA ndash Weymouth 13400 2009

Ozonia North America - Potable Water SummaryTotal Number of Installations 90Total Installed Production gt 265000 lbsdayTotal Installed Production 265000 lbsday

Revision -B

Ozone Water TreatmentOzone Water Treatment

MWD Mills WTP - California

3 3 000 lbsda of o one3 3 000 lbsda of o one3 x 3000 lbsday of ozone3 x 3000 lbsday of ozone

Ozone Water TreatmentOzone Water TreatmentOzone Ozone -- How it worksHow it works

OxidantOxidant DisinfectantDisinfectant

bullbull Breaks double carbon Breaks double carbon bondsbonds

bullbull Kills by cell lysing or Kills by cell lysing or causing the cell wall tocausing the cell wall tobondsbonds

bullbull Creates OHCreates OHbullbull radicals radicals which break higher carbon which break higher carbon

causing the cell wall to causing the cell wall to rupture rupture

bullbull AttacksAttacks allall bacteriabacteriabondsbondsbullbull Increased temp and pH Increased temp and pH

accelerates Oaccelerates O33

Attacks Attacks allall bacteria bacteria virus cysts and spores virus cysts and spores in varying degreesin varying degreesaccelerates Oaccelerates O33

decomposition to OHdecomposition to OHbullbull

Micro-organism DNA

Capsule AdenineAdenine

Cell wall ThymineThymine

CytosineCytosine

GuanineGuanine

NuclearmaterialCellmembrane

material

Typical Bacterium DNA

Microbial Growth at Various Ozone ConcentrationsConcentrations

Growth likely

Growth possibleGrowth possible

NO GROWTH

0004 0008 0012 0016 0020

Ozone concentration (mgl)Ozone concentration (mgl)

Typical Water Treatment UsageTypical Water Treatment Usage

Application O3 mgl Contact timeUltra Pure Water 005 - 025 sec ndash min

Water bottling 04 ndash 10 5 ndash 10 min

Swimming pools ampspas

01 ndash 075 4 minutes

Potable taste amp odor 15 ndash 50 5 ndash 10 mindisinfection

Microfloculation 10 ndash 30 5 ndash 10 min

Lignin amp tammin 3 0 10 0 10 30 minLignin amp tamminremoval

30 ndash 100 10 ndash 30 min

Municipal wastewater 50 ndash 150+ 15 ndash 30 min

Ozone Water TreatmentOzone Water TreatmentOzone Ozone ndashndash Municipal ApplicationsMunicipal Applications

bullbull Taste and OdorTaste and Odor

bullbull Color RemovalColor Removal

bullbull Disinfection Without Trihalomethanes (THMs)Disinfection Without Trihalomethanes (THMs)

bullbull Improved Filtration Efficiency and FlocculationImproved Filtration Efficiency and Flocculation

bullbull Cryptosporidium DeactivationCryptosporidium Deactivation

bullbull Giardia amp Virus InactivationGiardia amp Virus Inactivation

bullbull Oxidation Oxidation -- Organics Fe amp MnOrganics Fe amp Mn

bullbull Wastewater disinfectionWastewater disinfection

bullbull BOD COD and TOC reductionBOD COD and TOC reduction

Applications of Ozone

Wastewater Treatmentbull Disinfection of Secondary and Tertiary Effluentsbull Color Reductionbull Color Reductionbull TOC Oxidation (Industrial)bull Oxidation of Odor Causing Compoundsbull Oxidation of Endocrine Disruptors (EDCrsquos) and p ( )

Pharmaceutically Active Compounds (PACrsquos)

Applications of Ozone

What are Endocrine Disruptors (EDCrsquos) and What are Endocrine Disruptors (EDCrsquos) and Ph ti ll A ti C d (PACrsquo )Ph ti ll A ti C d (PACrsquo )Pharmaceutically Active Compounds (PACrsquos)Pharmaceutically Active Compounds (PACrsquos)

bullbull EDCrsquosEDCrsquos andand PACrsquosPACrsquos areare NaturallyNaturally andand SyntheticSyntheticdd th tth t ff tff t thth b lb l llcompoundscompounds thatthat maymay affectaffect thethe balancebalance oror normalnormal

functionsfunctions inin animalsanimals andand humanshumans

What can EDCrsquos and PACrsquos doWhat can EDCrsquos and PACrsquos do

bullbull Even in very small concentrations these compounds Even in very small concentrations these compounds y py pcan can disruptdisrupt normal bodily functionsnormal bodily functions

bullbull ManMan--made chemicals can trick the bodies endocrine made chemicals can trick the bodies endocrine system system

Applications of Ozone

Examples of Endocrine Disruptors1000rsquos of compounds that may be Investigated as EDCs ndash Some examples are

bullbull Synthetic HormonesSynthetic Hormonesbullbull Naturally Occurring Estrogens Naturally Occurring Estrogens

Health and Beauty AidsHealth and Beauty Aidsbullbull Health and Beauty AidsHealth and Beauty Aidsbullbull SolventsSolventsbullbull PesticidesPesticidesbullbull SurfactantsSurfactantsbullbull PlasticsPlastics

F i idF i idbullbull FungicidesFungicides

Ozone Water TreatmentOzone Water Treatment

Ozone Ozone -- Industrial ApplicationsIndustrial Applications-- Ultrapure Water for Pharmaceutical ApplicationsUltrapure Water for Pharmaceutical Applications

-- Wastewater disinfection color removalWastewater disinfection color removal

-- Soil and Groundwater Remediation Soil and Groundwater Remediation

-- Cooling Tower Water TreatmentCooling Tower Water Treatment

-- Food ProcessingFood Processing

-- Aquaculture AquariumsAquaculture AquariumsAquaculture AquariumsAquaculture Aquariums

-- Beverage ApplicationsBeverage Applications

P l amp P Bl hiP l amp P Bl hi-- Pulp amp Paper BleachingPulp amp Paper Bleaching

High Purity OzonationHigh Purity Ozonation

Microchip manufacturingMicrochip manufacturing

What are the current issues in large-scale gozone generationg

Experimental Setup

Front view of the two units after the redesign and reworking ofthe gas water and instruments connectionsthe gas water and instruments connections

Experimental Setup

Top view of the twoexperimental unitsexperimental unitsSpectroscope (notshown) is to the left ofthe DBD The units weredifferent with respect todifferent with respect totheir electrodes onehad only the electrodecoated with thedielectric (ldquosingle-dielectric ( single-coatedrdquo) the other onehad the electrode andthe anode coated withthe dielectric (ldquodouble-the dielectric ( double-coatedrdquo)

Basics Generation of OzoneBasics Generation of Ozone

SpectroscopyPlasma

Plasma Absorption SpectroscopyPlasma Absorption Spectroscopy

Infrared Absorption SpectroscopyInfrared Absorption Spectroscopy

IR spectra in pure oxygen (black curve) and at approximately 10wt N2 admixture (red line) N2O5 peaks appear at124 1 d 1 2 11245 cm-1 and at 1725 cm-1

Infrared Absorption SpectroscopyInfrared Absorption Spectroscopy

IR spectra of several methane variations The green curve envelopes all of the methane peaks at 1325 cm-1recorded at smaller methane admixtures Simultaneously the N2O5 peaks disappear as the methane peaks appear

N2O5 FormationN2O5 Formation2 52 5p=2 bara cwt=20degC q=35kWm2 f=1450Hz

45N2O5 AT95

30

35

40

N

2 B

lend

ing

N2O AT95N2O5 IGSN2O IGSN2O5 LGN2O LG

1 5

20

25

nt [p

pmV]

3

wt

05

10

15

NO

x co

nten

005 7 9 11 13 15 17

ozone conc [wt]

Amount of formed N2O5 and N2O as a function of ozone concentration at 3 wt of nitrogen admixture and fori l dvarious electrode arrangements

Plasma Emission SpectroscopyPlasma Emission Spectroscopyp pyp py

Relative Emissions of the Ozonizer plasmaRelative Emissions of the Ozonizer plasma

Region 300- 850 nm from individual (calibrated) regions (smoothed by PeakFit) Single-coated ozone generator Inlet side

3 5E+06

30E+06

35E+06

7 9

20E+06

25E+06

nten

sity

au

2

311 12

10E+06

15E+06

In 4

5

6 8 10

14

15

16

17

00E+00

50E+05

280 300 320 340 360 380 400 420 440 460 480 500 520 540 560 580 600 620 640 660 680 700 720 740 760 780 800 820 840 860

Wavelength nm

1 13

Wavelength nm

Absolute Emission of the DBD PlasmaAbsolute Emission of the DBD Plasma

Intensities in (O2+3 wtN2) plasma

1 20E+04

100E+04

120E+04

600E+03

800E+03

nten

sity

(au

)

200E+03

400E+03

In

O(777)

000E+00200 250 300 350 400 450 500 550 600 650 700 750 800 850

Wavelength nm

Intensities in 3 wtN2+O2 plasmaIntensities in 3 wtN2+O2 plasma

Plasma Chemistry in OzonizersPlasma Chemistry in Ozonizers

Dry Air O2 N2

e - e -

O N2 N O2

O3 NO

O2 N O2

O3

N

3

NO2

O2 O3

NO

N

NO2 O3

N2O

NO3 N

N2O4

NO2

NO2

N2O5

NO3

Primary electron-driven chemical reactions leading to the formation of N2O5 and N2O in a dry air plasma

Plasma emission diagnostics role of N2Plasma emission diagnostics role of N2

Dry Air O2 N2

e - e -

O N2 N O2

O3 NO

O2 N O2

O3

O

N

ON

NO2

O2O3

N

NO N

NO2 O3

N2O

NO3 N

N2O4

NO2

NO2

N2O5

NO3

ONbullWith N2 present ndash less oxygen atoms are formed However the difference in intensity is

very small

Modeling of plasma chemistry incl the NxOy chemistry up to N2O5 for different Oxygen Nitrogen mixtures varying power deposition scenarios

and initial ozone background concentrations (up to 15) previously done

The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation

The role of N2 must be related to its by-products reacting on the surface of the electrodeThe role of N2 must be related to its by-products reacting on the surface of the electrode

The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established

Ab 8 t f O

The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established

Ab 8 t f OAbove 8 wt of O3

1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)

Above 8 wt of O3

1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)case without pampp)

2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of the

case without pampp)

2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of thethem A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface

them A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface

The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation

Three possibilities have to be considered for the oxygen-fedozone generator

Three possibilities have to be considered for the oxygen-fedozone generatorozone generator

bull Excited N2 molecules lead to an increased O2 dissociation in

ozone generator

bull Excited N2 molecules lead to an increased O2 dissociation in2 2such case an increased efficiency is correlated to the N2admixture

2 2such case an increased efficiency is correlated to the N2admixture

bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial

bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial

bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2

bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2g p g 3 pp y 2g p g 3 pp y 2

Effect of methane on ozone efficiency and specific powerEffect of methane on ozone efficiency and specific power

Effect of Methane on Ozone Content in Outlet Gas and on Specific Power Pure O2

13 12

10

11

12

t 8

10

8

9

10

ne c

onte

nt w

t

6

8

ecifi

c po

wer

kW

hlb

5

6

7

Ozo

n

2

4 Spe

400E+00 20E+03 40E+03 60E+03 80E+03 10E+04 12E+04

Methane in feedgas ppm

0

Ozone content in the outlet gas Specif ic pow er of the ozone generatorg p p g

Effects of N2 and CH4Effects of N2 and CH4

Pi t f h t lli N O t tPicture of an amorphous-crystalline N2O5 structurecaptured at the Orlando Skylake water plant in 2006

Plasma Chemistry with CH4 Impurities

OxygenO2 N2

e - e -

CHO N2

NO2

O NO

O2 N O2 O3

NOH

CH4e-

O3 NO

NO2

O2O3NO N

NO2 O

NO2

NO2

N2ONO3

N

O3

NO2

NO

HNO3

N2O4

N2O5

NO2

NO3

N2O5

Effect of methane on the electrode surfaces

a) b)

Inlet Outlet Outlet

) d)

I l t I l t

c) d)

Electrode of the ozone generator afterseveral hours in CH8O2 and up to 2 wt of methane (a b c)

Inlet Inlet

three hours in CH8O2+traces of N2 and up to 1 wt of methane (d) Visible change of discharge character at about 13 length of electrode (a d)

Kinetics of CHx Conversion without N2

conversion by collisions

O2 + CHx 12wt O3 + CO2 +H2O

deposition vaporizationby sputtering

ibl b l 1000 CHreversible process below 1000ppm CH4

Effect of water on electrode surface with N2

Inlet

OutletOutlet

Electrode of the ozone generator after several hours in H OO N

Inlet

Electrode of the ozone generator after several hours in H2OO2N2

Effect of water on electrode surface

Long term effect (800 hrs) of H2OO2N2

Kinetics of CHx Conversion with N2

conversion by collisionsHNO3 formation

O2 + N2 +CHx 12wtO2 + CO2 +H2O + HNO3

deposition vaporizationby sputtering

H2O + HNO3

by sputtering

irreversible process above a N2 threshold () ltlt 1000ppm N2

sticky deposit

p 2 ( ) pp 2 any CH4 concentration (60ppm)

Plasma Chemistry with CH4 ImpuritiesPlasma Chemistry with CH4 Impurities4

bull Formation of NO and NO2 depends on O3 N2 and gas temperature Conclusion N2 admixture is the key factor

SummarySummaryyyThe mechanisms of formed NOx by-products follows the sameThe mechanisms of formed NOx by-products follows the sameprinciples as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentration

principles as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentrationozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)

ozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)g p ( g p )

The conversion of methane to OH and H2O is found to depend on

g p ( g p )

The conversion of methane to OH and H2O is found to depend ondissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)

dissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)discharge gap)discharge gap)

How do you optimize an ozone generatorg

Scientific ApproachScientific ApproachTheoretical Experimental

pppp

c [wt]

f [Hz]

c [wt]

f [Hz]

[kW]UUUβ1

1Cf4αPn

1iiminpeakimin

iiD

q [kWm2]q [kWm2]

150

180

][V]voltagepeakUpeak

[]cylinder perslicesofamountnsliceii

whereth

09 00

30

60

90

120

effic

ienc

y [

][0tdj t bl[F]sliceisdielectricofecapacitancC

[Hz]frequencyf[V]sliceivoltageminimumiUmin

thiD

th

10

28

46

64

82

39

107

176

244 power density

[kWm2]

ozone conc [wt][]CCβ

][0parameteradjustableα

iDiGi

Impact of Power Inductionp

350

400

wer

200

250

300

App

lied

Pow

Arr C 2Arr D +0

Arr E +45Arr F +7

Arr G +3

5 0

100

150

Frac

tion

of

1 2 3 4

ReferenceArr B unstable

Arr C -2

00

50

4Position (1inlet 4outlet)

Experimental Test Rigp g

Experimental Test Rigp g

Outer grounded electrode (left picture) and the dielectric covered inner electrodes (right) d e ect c cove ed e e ect odes ( g t)

Reference (Traditional) Arrangement

Inlet OutletGas flow direction

Optimized Arrangement

Inlet OutletGas flow direction

Intelligent Gap System (IGS)g p y ( )

Molecular Oxygen (O2) Ozone (O3)

O2 O3

yg ( 2) ( 3)

Particle Size SynthesisParticle Size SynthesisByBy--Products Cluster FormationProducts Cluster Formationyy

high diffusion and deposition to surfaces

low diffusion rate good transport

high sedimentation on the structurehigh sedimentation on the structure

Degreacutemont Technologies ndash OzoniaIntelligent Gap SystemIntelligent Gap System

G Vezzuacute JL Lopez A Freilich and K Becker Optimizationof Large-Scale Ozone Generators IEEE Transactions onPlasma Science Vol 37 No 6 p 890-896 (2009)

ConclusionsConclusionsConclusionsConclusionsFundamentals of ozone synthesis in a DBD plasmay p

ndash Highly filamented DBD discharges are best-suitedfor the production of ozone concentrations in therange of 6 to 14 wtrange of 6 to 14 wt

ndash The preferred characteristic of the microdischargesare Townsend-like at reduced electric fields Enaround 190 Townsend

ndash Detrimental side-effects induced by by-productscan be avoided by a proper design of the electrodecan be avoided by a proper design of the electrodearrangement The phenomenon is related to thediffusion rates of formed by-product clusters

ConclusionsConclusionsConclusionsConclusionsBenefits from DBD microplasma tailoring

ndash Reduced power consumption of up to 10 improvement

ndash Increased ozone concentrations of up to 14 now achievable

ndash Improved neutralization and conditioning of detrimental by-products

ndash Reduced system capital and operational cost

New technologies to improve ozone p

generatorg

HV Pulsed Power SwitchingHV Pulsed Power Switching

Microchannel Generation of Ozone

Channel ArrayChannel Array

Microchannel

330 microm 230 microm

Some Cap-DBD Devices Operating in Air

Increase of 60 of

Spacing 225 μmof 60 of plasma

No space

Cap‐DBD ozone generation

bull Ozone concentration is evaluated via Eco S d l UV 100 O A l (0 01Sensors model UV-100 Ozone Analyzer (001 ndash 900 ppm wiht an accuracy of plusmn2)

bull Three reactors 6 tubings 6rdquo with spacings of 0 μm 225 μm and 500 μm running at 3 kV μ μ μ g

SpacingOzone Concentration

3 kV rms 4 kV rms3 kV rms 4 kV rms

0 μm 660 ppm

225 μm 550 ppm

For a device of such small scale these ozone levels are promising

500 μm 380 ppm

J Mahoney W Zhu VS Johnson KH Becker and JL Lopez Electrical and optical emissionmeasurements of a capillary dielectric barrier discharge European Physics Journal D Vol 60 441-447(2010)

QuestionsQuestions

Thank YouFor more informationProf Jose L Lopez PhD

Thank YouFor more informationDepartment of Physics

Telephone (973) 761-9057Email joselopez1shuedu

Website wwwshueduacademicsartsciphysicsWebsite wwwshueduacademicsartsciphysics

Page 7: Dielectric Barrier Discharge (DBD) & Progress in Large ...bonitz/si12/talks/august_8/lopez_si12.pdf · Dielectric Barrier Discharge (DBD) & Progress in Large-Scale Ozone Generation

Atmospheric Cold PlasmasErich Kunhardt amp Kurt Becker

An Atmospheric Pressure Plasma Generated with a

(Courtesy of K Becker)

Capillary-Plasma-Electrode Discharge

Two Types of plasmas

bull High‐temperature plasmas (Hot Plasmas)g p p ( )Tiasymp Te ge107 Keg fusion plasmas

T asymp T asymp T le 2 x 104 KTi asymp Te asymp Tg le 2 x 104 Keg arc plasma at normal pressure

bull Low‐temperature plasmas (Cold Plasmas)Ti asymp Tg asymp 300 KT ltlt T le 105 KTi ltlt Te le 105 Keg low‐pressure glow discharge

high‐pressure cold plasma

Hot vs Cold PlasmasHot vs Cold Plasmas

LowLow--Temperature (ldquoColdrdquo) PlasmasTemperature (ldquoColdrdquo) Plasmas[Non[Non--equilibrium Nonequilibrium Non--Thermal]Thermal][Non[Non equilibrium Nonequilibrium Non Thermal]Thermal]

How do we make plasmasHow do we make plasmas

Supply Energyeg Heat transfer radiation electric powerhellip

For many plasma applicationsFor many plasma applications an Electric Field is applied to a gaseous environment

Plasma or Gaseous DischargePlasma or Gaseous Discharge

LowLow--Pressure Glow Discharge PlasmasPressure Glow Discharge Plasmas

Plasmas are easier to be generated at low pressures

Low pressure plasmas (1 T f T )

at low pressures

are well understood

are used extensively nowadays

(1 mTorr ~ a few Torr)

are used extensively nowadays (eg in semiconductor industry for computer chips manufacturing)

However to generate low pressure plasmas

vacuum chambers + + = expensive vacuum pumps

pressure monitoring and pressure control devices

+ + =Generate Plasmas at Atmospheric PressureGenerate Plasmas at Atmospheric Pressure

What happens at air pressureWhat happens at air pressure

bull No vacuum is involvedDiffi l d ibull Difficult to generate and sustain

bull Run into some challenges such as glow toarc transition ndash Non controllable

Arc Discharge thermal plasma-Itrsquos hot and detrimental-Gas temperature can reach as high as 2x104 KGas temperature can reach as high as 2x10 K- Low voltage drop at cathode- High cathode current density

High Pressure Microplasmas

Stabilization of high-pressure plasmas ldquopd scalingrdquo ldquoprdquo uarr soplasmas pd scaling p uarr so ldquodrdquo darr to keep breakdown voltage low and minimize instabilities after breakdown -

MicroplasmasDimension a few millimeterDimension a few millimeter down to and below 100 m

Paschen Breakdown CurveH H i 60 100Human Hair 60 ndash 100 m

How do we solve this problemHow do we solve this problem

Transient (pulsed) plasmas In atmospheric plasmas for efficient gas heating atleast 100-1000 collisions are necessary Thus if the plasma duration is shorterleast 100 1000 collisions are necessary Thus if the plasma duration is shorterthan 10-6 ndash 10-5 s gas heating is limited Of course for practical purposes suchplasma has to be operated in a repetitive mode eg in trains of microsecondpulses with millisecond intervals

Micro-confinement Gas heating occurs in the plasma volume and the energy iscarried away by thermal diffusionconvection to the outside If the plasma has asmall volume and a relatively large surface gas heating is limited

Dielectric Barrier Discharges These plasmas are typically created betweenmetal plates which are covered by a thin layer of dielectric or highly resistivematerial The dielectric layer plays an important role in suppressing the currentthe cathodeanode layer is charged by incoming positive ionselectrons whichreduces the electric field and hinders charge transport towards the electrodeDBD also has a large surface-to-volume ratio which promotes diffusion lossesand maintains a low gas temperatureand maintains a low gas temperature

Advantages of Microplasmas Advantages of Microplasmas

bull Low-cost of implementationpbull System flexibilitybull Atmospheric pressure operationbull High densities and high reaction ratesbull High densities and high reaction ratesbull Fast and efficient processesbull Easy to generate and sustain for a variety of gas mixtures

Gl lik d diffbull Glow-like and diffusebull Non-equilibrium (Te gt Tg) to thermalbull Unique chemistryq y

hellip a new realm of plasma sciencehellip a new realm of plasma science

What can we do with microplasmasWhat can we do with microplasmas

Material Synthesis Plasma display Surface Treatment Lighting

OzoneOzone generation for water cleaning

Bio-applicationMaterial processing Dental application

and Many morehellip

Some High Pressure microplasma reactors Some High Pressure microplasma reactors

Dielectric Barrier Discharge (DBD)Dielectric Barrier Discharge (DBD)

Hi h V l

HighVoltage

High VoltageElectrode

ACGenerator

DielectricBarrier

Generator

G

Microplasmas

GroundElectrode

Faradayrsquos Dielectric CapacitorsFaradayrsquos Dielectric Capacitors

Faradays Dielectric Capacitor (circa 1837)

Michael Faraday (1781 ndash 1867) Capacitance INCREASED

Historical Ozone Tube of W Siemens (1857)Historical Ozone Tube of W Siemens (1857)

Werner v SiemensP d frsquo A l d Ch i d Ph ik 102 66 (1857)Poggendorfrsquos Annalen der Chemie und Physik 102 66 (1857)

ldquoOzone Production in an Atmospheric-PressureDielectric Barrier Dischargerdquo

Dielectric Barrier Discharge

Dielectric Barrier DischargeDielectric - Barrier Discharge ConfigurationsHigh

VoltageAC

Generator

High VoltageElectrode

DielectricBarrier

DielectricBarrier

High VoltageElectrode

Discharge

DischargeGeneratorGround

Electrode

Electrode

GroundElectrode

Discharge

H E Wagner R Brandenburg et al lsquoThe barrier discharge basic properties and applications toHE Wagner R Brandenburg et al The barrier discharge basic properties and applications tosurface treatmentrsquo Vacuum 71 p417-436 (2003)

Typical operational conditions of barrier discharges Typical operational conditions of barrier discharges

Electric field strength E of first breakdown asymp150 Td (p = 1bar T=300 K)

Voltage Vpp 3ndash20 kV

Repetition frequency f 50 Hzndash30 kHz

Pressure p 1ndash3 bar

Gap distance g 02ndash5mm

Dielectric material thickness d 05ndash2mm

Relative dielectric permittivity r 5ndash10 (glass)

B Eliasson and U Kogelschatz IEEE Transactions Plasma Science Vol 19 Issue 6 1063-1077 (1991)B Eliasson and U Kogelschatz IEEE Transactions Plasma Science Vol 19 Issue 6 1063-1077 (1991)

Single and double DBD

Single dielectric Double dielectric

Role of the Dielectric (Insulator)

Th di l t i i th k f thThe dielectric is the key for the properfunctioning of the discharge

Serves two functions

1 Limits the amount of charge transportedby a single microplasma

2 Distributes the microplasmas over theentire electrode surface area

Equivalent Circuit of a Microdischarge

Microdischarge Activity and U-Q Lissajous Figure

B Eliasson and U Kogelschatz IEEE Transactions Plasma Science Vol 19 Issue 6 1063-1077 (1991)

Fundamental Operation of the Dielectric Barrier DischargeFundamental Operation of the Dielectric Barrier Discharge

bull Many of relevant plasma processes that areof importance to achieving our goal occuron time scales that allow us to study themon time scales that allow us to study them

bull Optical emission spectroscopic studies willallow us to determine the temporal andspatial development of important plasmaspatial development of important plasmaspecies such as radicals (OH NO variousoxygen radicals) with high time resolution(less than 10 ns) and a spatial resolution onthe scale of mm in the plasma volumepfollowing pulsed plasma excitation

Time scale of the relevant processes of the DBD

HE Wagner R Brandenburg et al lsquoThe barrier discharge basic properties and applications tosurface treatmentrsquo Vacuum 71 417-436 (2003)

Fundamental Operation of the DBDFundamental Operation of the DBD

Electron DensityTemporal Development (ns)

y

Outer Contour Linen = 1010 cm-3ne = 1010 cm 3

Inner Contour Linene = 1014 cm-3

Streamer Propagation in 1 bar AirAA Kulikovsky IEEE Trans Plasma Sci 25 439-446 (1997)

Numerical Results of Microdischarge Formationin Dielectric Barrier Discharges

Starting Phase of a Microdischarge (1 bar 20 CO2 80 H2)

E0=34 kVcm1010 cm-3

1010 cm-3 ne=1012 cm-3

1mm10 cm

ne=108 cm-3

An electron avalanche propagates towards the anode

Reverse propagationtowards the cathodepropagates towards the anode towards the cathode

Numerical Results of Microdischarge Formationin Dielectric Barrier Discharges

Cathode Layer Formation

E0=34 kVcm1010 cm-39 3 0

1mm

1010 cm-3

10 cmne=109 cm-31014

10131014

1013

10 cm1012

Just before the peak of the total current

Peak currentof the total current

Numerical Results of Microdischarge Formationin Dielectric Barrier Discharges

Local Field Collapse in Area Defined by Surface Discharge

ne=109cm-3 ne=1014 cm-3

Gap

Principals of DBD MicroplasmasPrincipals of DBD MicroplasmasPrincipals of DBD MicroplasmasPrincipals of DBD Microplasmas

C C-- - --- - - CG

CD

-- - - CG

CD

Principals of DBD MicroplasmasPrincipals of DBD MicroplasmasPrincipals of DBD MicroplasmasPrincipals of DBD Microplasmas

Dielectric Barrier Discharge (DBD)Dielectric Barrier Discharge (DBD)Electric Field

B kdBreakdown

Electrons amp Ions Discharge Physics

Excited SpeciesPlasma Chemistry

Chemical Reactions

OzoneGeneration

SurfaceTreatment

PollutionControl

ExcimerFormation CO2 Lasers Hydrogenation

of CO2

Excimer Lamps Plasma Displays

How A Plasma Display Works

How A Plasma Display Work

Plasma Display TelevisionsPlasma Display Televisions

Ozone Generator

3 O 2 O

Dielectric Barrier Discharge

3 O2 2 O3

OO22 OO33++OO22Ondash ndashO3O2

O2O2

Ondash ndash

endash O2Ondash ndash O2endash

O3

O3O2O2 O2

HeatHeatHeatHeat

Properties of Ozone (O3)

T i t i f f Tri-atomic form of oxygen

Most powerful commercial oxidizing agent

Unstable - must be generated and used onsite

Limited solubility in water but more so than oxygenLimited solubility in water but more so than oxygen

Leaves a dissolved residual which ultimately converts back to oxygenconverts back to oxygen

Discharge Tubes in Ozone GeneratorsDischarge Tubes in Ozone Generators

Traditional

Ozone Generator

with Glass Tubes

Generation of OzoneGeneration of Ozone

Generation of OzoneAdvantages of Enamel Dielectrics

Proven Patented Designbull Simplicity

Si l Di l i Cbull Single Dielectric Componentndash Reduced number of Dielectrics

bull Safety ndash Lower operating voltage

(lt 4000 V)bull Reliabilty

ndash Fused Dielectrics ensure continuous production

bull Lowest Power Consumption Operational Savingsndash Operational Savings

Modern Ozone GeneratorModern Ozone Generator

Ozonia Advanced Technology Ozone GeneratorOzone Generator

Generation of OzoneGeneration of Ozone

Generation of Ozone

Power Supply UnitPower Supply Unit

IGBT Inverter CircuitMain Circuit Breaker

HV 480 Volts60 Hz3 Phase Supply

C I

450KVAPow er to

GeneratorFILTER

CONVERTER INVERTERTRANSFORMER

C I450KVA Power Stage

CONTACTOR

bull Latest in Power Semiconductor Technology Modular Design

bull Utilizes IGBTrsquos (Insulated Gate Bi‐Polar Transistors) Converter and Inverter Components

Ozone Water Treatment

B bbl Diff iB bbl Diff iBubble DiffusionBubble Diffusion

Easy to use

Low energy usage Low energy usage

Mass transfer efficiencies to gt 90

Ozone Process Flow DiagramOzone Process Flow DiagramVent to

Atmosphere

O OOxygen

Off-Gas Blower

Ozone Destruct Unit

10 12

O3O2

LOX

10-12 O3

Ozone Generators

Ozone Contact ChamberLOX T k Generators Chamber

VaporizersLOX Tank

Municipal Ozone Installations

Ozonia Installations Ozone Plant Size [lbday] Start-Up DateKey Ozonia Installations (Partial List)

Los Angeles CA 10000 1986Fairfax VA ndash Corbalis 9000 2003MWD CA ndash Mills 9 000 2003

Ozonia Installations Ozone Plant Size [lbday] Start Up Date

MWD CA Mills 9000 2003Fairfax Co VA ndash Griffith 9000 2004MWD CA ndash Jensen 18750 2005Indianapolis IN ndash Belmont AWT 12000 2007I di li IN 12 000 2007Indianapolis IN ndash Southport AWT 12000 2007MWD CA ndash Diemer 13400 2008MWD CA ndash Weymouth 13400 2009

Ozonia North America - Potable Water SummaryTotal Number of Installations 90Total Installed Production gt 265000 lbsdayTotal Installed Production 265000 lbsday

Revision -B

Ozone Water TreatmentOzone Water Treatment

MWD Mills WTP - California

3 3 000 lbsda of o one3 3 000 lbsda of o one3 x 3000 lbsday of ozone3 x 3000 lbsday of ozone

Ozone Water TreatmentOzone Water TreatmentOzone Ozone -- How it worksHow it works

OxidantOxidant DisinfectantDisinfectant

bullbull Breaks double carbon Breaks double carbon bondsbonds

bullbull Kills by cell lysing or Kills by cell lysing or causing the cell wall tocausing the cell wall tobondsbonds

bullbull Creates OHCreates OHbullbull radicals radicals which break higher carbon which break higher carbon

causing the cell wall to causing the cell wall to rupture rupture

bullbull AttacksAttacks allall bacteriabacteriabondsbondsbullbull Increased temp and pH Increased temp and pH

accelerates Oaccelerates O33

Attacks Attacks allall bacteria bacteria virus cysts and spores virus cysts and spores in varying degreesin varying degreesaccelerates Oaccelerates O33

decomposition to OHdecomposition to OHbullbull

Micro-organism DNA

Capsule AdenineAdenine

Cell wall ThymineThymine

CytosineCytosine

GuanineGuanine

NuclearmaterialCellmembrane

material

Typical Bacterium DNA

Microbial Growth at Various Ozone ConcentrationsConcentrations

Growth likely

Growth possibleGrowth possible

NO GROWTH

0004 0008 0012 0016 0020

Ozone concentration (mgl)Ozone concentration (mgl)

Typical Water Treatment UsageTypical Water Treatment Usage

Application O3 mgl Contact timeUltra Pure Water 005 - 025 sec ndash min

Water bottling 04 ndash 10 5 ndash 10 min

Swimming pools ampspas

01 ndash 075 4 minutes

Potable taste amp odor 15 ndash 50 5 ndash 10 mindisinfection

Microfloculation 10 ndash 30 5 ndash 10 min

Lignin amp tammin 3 0 10 0 10 30 minLignin amp tamminremoval

30 ndash 100 10 ndash 30 min

Municipal wastewater 50 ndash 150+ 15 ndash 30 min

Ozone Water TreatmentOzone Water TreatmentOzone Ozone ndashndash Municipal ApplicationsMunicipal Applications

bullbull Taste and OdorTaste and Odor

bullbull Color RemovalColor Removal

bullbull Disinfection Without Trihalomethanes (THMs)Disinfection Without Trihalomethanes (THMs)

bullbull Improved Filtration Efficiency and FlocculationImproved Filtration Efficiency and Flocculation

bullbull Cryptosporidium DeactivationCryptosporidium Deactivation

bullbull Giardia amp Virus InactivationGiardia amp Virus Inactivation

bullbull Oxidation Oxidation -- Organics Fe amp MnOrganics Fe amp Mn

bullbull Wastewater disinfectionWastewater disinfection

bullbull BOD COD and TOC reductionBOD COD and TOC reduction

Applications of Ozone

Wastewater Treatmentbull Disinfection of Secondary and Tertiary Effluentsbull Color Reductionbull Color Reductionbull TOC Oxidation (Industrial)bull Oxidation of Odor Causing Compoundsbull Oxidation of Endocrine Disruptors (EDCrsquos) and p ( )

Pharmaceutically Active Compounds (PACrsquos)

Applications of Ozone

What are Endocrine Disruptors (EDCrsquos) and What are Endocrine Disruptors (EDCrsquos) and Ph ti ll A ti C d (PACrsquo )Ph ti ll A ti C d (PACrsquo )Pharmaceutically Active Compounds (PACrsquos)Pharmaceutically Active Compounds (PACrsquos)

bullbull EDCrsquosEDCrsquos andand PACrsquosPACrsquos areare NaturallyNaturally andand SyntheticSyntheticdd th tth t ff tff t thth b lb l llcompoundscompounds thatthat maymay affectaffect thethe balancebalance oror normalnormal

functionsfunctions inin animalsanimals andand humanshumans

What can EDCrsquos and PACrsquos doWhat can EDCrsquos and PACrsquos do

bullbull Even in very small concentrations these compounds Even in very small concentrations these compounds y py pcan can disruptdisrupt normal bodily functionsnormal bodily functions

bullbull ManMan--made chemicals can trick the bodies endocrine made chemicals can trick the bodies endocrine system system

Applications of Ozone

Examples of Endocrine Disruptors1000rsquos of compounds that may be Investigated as EDCs ndash Some examples are

bullbull Synthetic HormonesSynthetic Hormonesbullbull Naturally Occurring Estrogens Naturally Occurring Estrogens

Health and Beauty AidsHealth and Beauty Aidsbullbull Health and Beauty AidsHealth and Beauty Aidsbullbull SolventsSolventsbullbull PesticidesPesticidesbullbull SurfactantsSurfactantsbullbull PlasticsPlastics

F i idF i idbullbull FungicidesFungicides

Ozone Water TreatmentOzone Water Treatment

Ozone Ozone -- Industrial ApplicationsIndustrial Applications-- Ultrapure Water for Pharmaceutical ApplicationsUltrapure Water for Pharmaceutical Applications

-- Wastewater disinfection color removalWastewater disinfection color removal

-- Soil and Groundwater Remediation Soil and Groundwater Remediation

-- Cooling Tower Water TreatmentCooling Tower Water Treatment

-- Food ProcessingFood Processing

-- Aquaculture AquariumsAquaculture AquariumsAquaculture AquariumsAquaculture Aquariums

-- Beverage ApplicationsBeverage Applications

P l amp P Bl hiP l amp P Bl hi-- Pulp amp Paper BleachingPulp amp Paper Bleaching

High Purity OzonationHigh Purity Ozonation

Microchip manufacturingMicrochip manufacturing

What are the current issues in large-scale gozone generationg

Experimental Setup

Front view of the two units after the redesign and reworking ofthe gas water and instruments connectionsthe gas water and instruments connections

Experimental Setup

Top view of the twoexperimental unitsexperimental unitsSpectroscope (notshown) is to the left ofthe DBD The units weredifferent with respect todifferent with respect totheir electrodes onehad only the electrodecoated with thedielectric (ldquosingle-dielectric ( single-coatedrdquo) the other onehad the electrode andthe anode coated withthe dielectric (ldquodouble-the dielectric ( double-coatedrdquo)

Basics Generation of OzoneBasics Generation of Ozone

SpectroscopyPlasma

Plasma Absorption SpectroscopyPlasma Absorption Spectroscopy

Infrared Absorption SpectroscopyInfrared Absorption Spectroscopy

IR spectra in pure oxygen (black curve) and at approximately 10wt N2 admixture (red line) N2O5 peaks appear at124 1 d 1 2 11245 cm-1 and at 1725 cm-1

Infrared Absorption SpectroscopyInfrared Absorption Spectroscopy

IR spectra of several methane variations The green curve envelopes all of the methane peaks at 1325 cm-1recorded at smaller methane admixtures Simultaneously the N2O5 peaks disappear as the methane peaks appear

N2O5 FormationN2O5 Formation2 52 5p=2 bara cwt=20degC q=35kWm2 f=1450Hz

45N2O5 AT95

30

35

40

N

2 B

lend

ing

N2O AT95N2O5 IGSN2O IGSN2O5 LGN2O LG

1 5

20

25

nt [p

pmV]

3

wt

05

10

15

NO

x co

nten

005 7 9 11 13 15 17

ozone conc [wt]

Amount of formed N2O5 and N2O as a function of ozone concentration at 3 wt of nitrogen admixture and fori l dvarious electrode arrangements

Plasma Emission SpectroscopyPlasma Emission Spectroscopyp pyp py

Relative Emissions of the Ozonizer plasmaRelative Emissions of the Ozonizer plasma

Region 300- 850 nm from individual (calibrated) regions (smoothed by PeakFit) Single-coated ozone generator Inlet side

3 5E+06

30E+06

35E+06

7 9

20E+06

25E+06

nten

sity

au

2

311 12

10E+06

15E+06

In 4

5

6 8 10

14

15

16

17

00E+00

50E+05

280 300 320 340 360 380 400 420 440 460 480 500 520 540 560 580 600 620 640 660 680 700 720 740 760 780 800 820 840 860

Wavelength nm

1 13

Wavelength nm

Absolute Emission of the DBD PlasmaAbsolute Emission of the DBD Plasma

Intensities in (O2+3 wtN2) plasma

1 20E+04

100E+04

120E+04

600E+03

800E+03

nten

sity

(au

)

200E+03

400E+03

In

O(777)

000E+00200 250 300 350 400 450 500 550 600 650 700 750 800 850

Wavelength nm

Intensities in 3 wtN2+O2 plasmaIntensities in 3 wtN2+O2 plasma

Plasma Chemistry in OzonizersPlasma Chemistry in Ozonizers

Dry Air O2 N2

e - e -

O N2 N O2

O3 NO

O2 N O2

O3

N

3

NO2

O2 O3

NO

N

NO2 O3

N2O

NO3 N

N2O4

NO2

NO2

N2O5

NO3

Primary electron-driven chemical reactions leading to the formation of N2O5 and N2O in a dry air plasma

Plasma emission diagnostics role of N2Plasma emission diagnostics role of N2

Dry Air O2 N2

e - e -

O N2 N O2

O3 NO

O2 N O2

O3

O

N

ON

NO2

O2O3

N

NO N

NO2 O3

N2O

NO3 N

N2O4

NO2

NO2

N2O5

NO3

ONbullWith N2 present ndash less oxygen atoms are formed However the difference in intensity is

very small

Modeling of plasma chemistry incl the NxOy chemistry up to N2O5 for different Oxygen Nitrogen mixtures varying power deposition scenarios

and initial ozone background concentrations (up to 15) previously done

The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation

The role of N2 must be related to its by-products reacting on the surface of the electrodeThe role of N2 must be related to its by-products reacting on the surface of the electrode

The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established

Ab 8 t f O

The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established

Ab 8 t f OAbove 8 wt of O3

1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)

Above 8 wt of O3

1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)case without pampp)

2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of the

case without pampp)

2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of thethem A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface

them A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface

The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation

Three possibilities have to be considered for the oxygen-fedozone generator

Three possibilities have to be considered for the oxygen-fedozone generatorozone generator

bull Excited N2 molecules lead to an increased O2 dissociation in

ozone generator

bull Excited N2 molecules lead to an increased O2 dissociation in2 2such case an increased efficiency is correlated to the N2admixture

2 2such case an increased efficiency is correlated to the N2admixture

bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial

bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial

bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2

bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2g p g 3 pp y 2g p g 3 pp y 2

Effect of methane on ozone efficiency and specific powerEffect of methane on ozone efficiency and specific power

Effect of Methane on Ozone Content in Outlet Gas and on Specific Power Pure O2

13 12

10

11

12

t 8

10

8

9

10

ne c

onte

nt w

t

6

8

ecifi

c po

wer

kW

hlb

5

6

7

Ozo

n

2

4 Spe

400E+00 20E+03 40E+03 60E+03 80E+03 10E+04 12E+04

Methane in feedgas ppm

0

Ozone content in the outlet gas Specif ic pow er of the ozone generatorg p p g

Effects of N2 and CH4Effects of N2 and CH4

Pi t f h t lli N O t tPicture of an amorphous-crystalline N2O5 structurecaptured at the Orlando Skylake water plant in 2006

Plasma Chemistry with CH4 Impurities

OxygenO2 N2

e - e -

CHO N2

NO2

O NO

O2 N O2 O3

NOH

CH4e-

O3 NO

NO2

O2O3NO N

NO2 O

NO2

NO2

N2ONO3

N

O3

NO2

NO

HNO3

N2O4

N2O5

NO2

NO3

N2O5

Effect of methane on the electrode surfaces

a) b)

Inlet Outlet Outlet

) d)

I l t I l t

c) d)

Electrode of the ozone generator afterseveral hours in CH8O2 and up to 2 wt of methane (a b c)

Inlet Inlet

three hours in CH8O2+traces of N2 and up to 1 wt of methane (d) Visible change of discharge character at about 13 length of electrode (a d)

Kinetics of CHx Conversion without N2

conversion by collisions

O2 + CHx 12wt O3 + CO2 +H2O

deposition vaporizationby sputtering

ibl b l 1000 CHreversible process below 1000ppm CH4

Effect of water on electrode surface with N2

Inlet

OutletOutlet

Electrode of the ozone generator after several hours in H OO N

Inlet

Electrode of the ozone generator after several hours in H2OO2N2

Effect of water on electrode surface

Long term effect (800 hrs) of H2OO2N2

Kinetics of CHx Conversion with N2

conversion by collisionsHNO3 formation

O2 + N2 +CHx 12wtO2 + CO2 +H2O + HNO3

deposition vaporizationby sputtering

H2O + HNO3

by sputtering

irreversible process above a N2 threshold () ltlt 1000ppm N2

sticky deposit

p 2 ( ) pp 2 any CH4 concentration (60ppm)

Plasma Chemistry with CH4 ImpuritiesPlasma Chemistry with CH4 Impurities4

bull Formation of NO and NO2 depends on O3 N2 and gas temperature Conclusion N2 admixture is the key factor

SummarySummaryyyThe mechanisms of formed NOx by-products follows the sameThe mechanisms of formed NOx by-products follows the sameprinciples as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentration

principles as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentrationozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)

ozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)g p ( g p )

The conversion of methane to OH and H2O is found to depend on

g p ( g p )

The conversion of methane to OH and H2O is found to depend ondissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)

dissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)discharge gap)discharge gap)

How do you optimize an ozone generatorg

Scientific ApproachScientific ApproachTheoretical Experimental

pppp

c [wt]

f [Hz]

c [wt]

f [Hz]

[kW]UUUβ1

1Cf4αPn

1iiminpeakimin

iiD

q [kWm2]q [kWm2]

150

180

][V]voltagepeakUpeak

[]cylinder perslicesofamountnsliceii

whereth

09 00

30

60

90

120

effic

ienc

y [

][0tdj t bl[F]sliceisdielectricofecapacitancC

[Hz]frequencyf[V]sliceivoltageminimumiUmin

thiD

th

10

28

46

64

82

39

107

176

244 power density

[kWm2]

ozone conc [wt][]CCβ

][0parameteradjustableα

iDiGi

Impact of Power Inductionp

350

400

wer

200

250

300

App

lied

Pow

Arr C 2Arr D +0

Arr E +45Arr F +7

Arr G +3

5 0

100

150

Frac

tion

of

1 2 3 4

ReferenceArr B unstable

Arr C -2

00

50

4Position (1inlet 4outlet)

Experimental Test Rigp g

Experimental Test Rigp g

Outer grounded electrode (left picture) and the dielectric covered inner electrodes (right) d e ect c cove ed e e ect odes ( g t)

Reference (Traditional) Arrangement

Inlet OutletGas flow direction

Optimized Arrangement

Inlet OutletGas flow direction

Intelligent Gap System (IGS)g p y ( )

Molecular Oxygen (O2) Ozone (O3)

O2 O3

yg ( 2) ( 3)

Particle Size SynthesisParticle Size SynthesisByBy--Products Cluster FormationProducts Cluster Formationyy

high diffusion and deposition to surfaces

low diffusion rate good transport

high sedimentation on the structurehigh sedimentation on the structure

Degreacutemont Technologies ndash OzoniaIntelligent Gap SystemIntelligent Gap System

G Vezzuacute JL Lopez A Freilich and K Becker Optimizationof Large-Scale Ozone Generators IEEE Transactions onPlasma Science Vol 37 No 6 p 890-896 (2009)

ConclusionsConclusionsConclusionsConclusionsFundamentals of ozone synthesis in a DBD plasmay p

ndash Highly filamented DBD discharges are best-suitedfor the production of ozone concentrations in therange of 6 to 14 wtrange of 6 to 14 wt

ndash The preferred characteristic of the microdischargesare Townsend-like at reduced electric fields Enaround 190 Townsend

ndash Detrimental side-effects induced by by-productscan be avoided by a proper design of the electrodecan be avoided by a proper design of the electrodearrangement The phenomenon is related to thediffusion rates of formed by-product clusters

ConclusionsConclusionsConclusionsConclusionsBenefits from DBD microplasma tailoring

ndash Reduced power consumption of up to 10 improvement

ndash Increased ozone concentrations of up to 14 now achievable

ndash Improved neutralization and conditioning of detrimental by-products

ndash Reduced system capital and operational cost

New technologies to improve ozone p

generatorg

HV Pulsed Power SwitchingHV Pulsed Power Switching

Microchannel Generation of Ozone

Channel ArrayChannel Array

Microchannel

330 microm 230 microm

Some Cap-DBD Devices Operating in Air

Increase of 60 of

Spacing 225 μmof 60 of plasma

No space

Cap‐DBD ozone generation

bull Ozone concentration is evaluated via Eco S d l UV 100 O A l (0 01Sensors model UV-100 Ozone Analyzer (001 ndash 900 ppm wiht an accuracy of plusmn2)

bull Three reactors 6 tubings 6rdquo with spacings of 0 μm 225 μm and 500 μm running at 3 kV μ μ μ g

SpacingOzone Concentration

3 kV rms 4 kV rms3 kV rms 4 kV rms

0 μm 660 ppm

225 μm 550 ppm

For a device of such small scale these ozone levels are promising

500 μm 380 ppm

J Mahoney W Zhu VS Johnson KH Becker and JL Lopez Electrical and optical emissionmeasurements of a capillary dielectric barrier discharge European Physics Journal D Vol 60 441-447(2010)

QuestionsQuestions

Thank YouFor more informationProf Jose L Lopez PhD

Thank YouFor more informationDepartment of Physics

Telephone (973) 761-9057Email joselopez1shuedu

Website wwwshueduacademicsartsciphysicsWebsite wwwshueduacademicsartsciphysics

Page 8: Dielectric Barrier Discharge (DBD) & Progress in Large ...bonitz/si12/talks/august_8/lopez_si12.pdf · Dielectric Barrier Discharge (DBD) & Progress in Large-Scale Ozone Generation

Two Types of plasmas

bull High‐temperature plasmas (Hot Plasmas)g p p ( )Tiasymp Te ge107 Keg fusion plasmas

T asymp T asymp T le 2 x 104 KTi asymp Te asymp Tg le 2 x 104 Keg arc plasma at normal pressure

bull Low‐temperature plasmas (Cold Plasmas)Ti asymp Tg asymp 300 KT ltlt T le 105 KTi ltlt Te le 105 Keg low‐pressure glow discharge

high‐pressure cold plasma

Hot vs Cold PlasmasHot vs Cold Plasmas

LowLow--Temperature (ldquoColdrdquo) PlasmasTemperature (ldquoColdrdquo) Plasmas[Non[Non--equilibrium Nonequilibrium Non--Thermal]Thermal][Non[Non equilibrium Nonequilibrium Non Thermal]Thermal]

How do we make plasmasHow do we make plasmas

Supply Energyeg Heat transfer radiation electric powerhellip

For many plasma applicationsFor many plasma applications an Electric Field is applied to a gaseous environment

Plasma or Gaseous DischargePlasma or Gaseous Discharge

LowLow--Pressure Glow Discharge PlasmasPressure Glow Discharge Plasmas

Plasmas are easier to be generated at low pressures

Low pressure plasmas (1 T f T )

at low pressures

are well understood

are used extensively nowadays

(1 mTorr ~ a few Torr)

are used extensively nowadays (eg in semiconductor industry for computer chips manufacturing)

However to generate low pressure plasmas

vacuum chambers + + = expensive vacuum pumps

pressure monitoring and pressure control devices

+ + =Generate Plasmas at Atmospheric PressureGenerate Plasmas at Atmospheric Pressure

What happens at air pressureWhat happens at air pressure

bull No vacuum is involvedDiffi l d ibull Difficult to generate and sustain

bull Run into some challenges such as glow toarc transition ndash Non controllable

Arc Discharge thermal plasma-Itrsquos hot and detrimental-Gas temperature can reach as high as 2x104 KGas temperature can reach as high as 2x10 K- Low voltage drop at cathode- High cathode current density

High Pressure Microplasmas

Stabilization of high-pressure plasmas ldquopd scalingrdquo ldquoprdquo uarr soplasmas pd scaling p uarr so ldquodrdquo darr to keep breakdown voltage low and minimize instabilities after breakdown -

MicroplasmasDimension a few millimeterDimension a few millimeter down to and below 100 m

Paschen Breakdown CurveH H i 60 100Human Hair 60 ndash 100 m

How do we solve this problemHow do we solve this problem

Transient (pulsed) plasmas In atmospheric plasmas for efficient gas heating atleast 100-1000 collisions are necessary Thus if the plasma duration is shorterleast 100 1000 collisions are necessary Thus if the plasma duration is shorterthan 10-6 ndash 10-5 s gas heating is limited Of course for practical purposes suchplasma has to be operated in a repetitive mode eg in trains of microsecondpulses with millisecond intervals

Micro-confinement Gas heating occurs in the plasma volume and the energy iscarried away by thermal diffusionconvection to the outside If the plasma has asmall volume and a relatively large surface gas heating is limited

Dielectric Barrier Discharges These plasmas are typically created betweenmetal plates which are covered by a thin layer of dielectric or highly resistivematerial The dielectric layer plays an important role in suppressing the currentthe cathodeanode layer is charged by incoming positive ionselectrons whichreduces the electric field and hinders charge transport towards the electrodeDBD also has a large surface-to-volume ratio which promotes diffusion lossesand maintains a low gas temperatureand maintains a low gas temperature

Advantages of Microplasmas Advantages of Microplasmas

bull Low-cost of implementationpbull System flexibilitybull Atmospheric pressure operationbull High densities and high reaction ratesbull High densities and high reaction ratesbull Fast and efficient processesbull Easy to generate and sustain for a variety of gas mixtures

Gl lik d diffbull Glow-like and diffusebull Non-equilibrium (Te gt Tg) to thermalbull Unique chemistryq y

hellip a new realm of plasma sciencehellip a new realm of plasma science

What can we do with microplasmasWhat can we do with microplasmas

Material Synthesis Plasma display Surface Treatment Lighting

OzoneOzone generation for water cleaning

Bio-applicationMaterial processing Dental application

and Many morehellip

Some High Pressure microplasma reactors Some High Pressure microplasma reactors

Dielectric Barrier Discharge (DBD)Dielectric Barrier Discharge (DBD)

Hi h V l

HighVoltage

High VoltageElectrode

ACGenerator

DielectricBarrier

Generator

G

Microplasmas

GroundElectrode

Faradayrsquos Dielectric CapacitorsFaradayrsquos Dielectric Capacitors

Faradays Dielectric Capacitor (circa 1837)

Michael Faraday (1781 ndash 1867) Capacitance INCREASED

Historical Ozone Tube of W Siemens (1857)Historical Ozone Tube of W Siemens (1857)

Werner v SiemensP d frsquo A l d Ch i d Ph ik 102 66 (1857)Poggendorfrsquos Annalen der Chemie und Physik 102 66 (1857)

ldquoOzone Production in an Atmospheric-PressureDielectric Barrier Dischargerdquo

Dielectric Barrier Discharge

Dielectric Barrier DischargeDielectric - Barrier Discharge ConfigurationsHigh

VoltageAC

Generator

High VoltageElectrode

DielectricBarrier

DielectricBarrier

High VoltageElectrode

Discharge

DischargeGeneratorGround

Electrode

Electrode

GroundElectrode

Discharge

H E Wagner R Brandenburg et al lsquoThe barrier discharge basic properties and applications toHE Wagner R Brandenburg et al The barrier discharge basic properties and applications tosurface treatmentrsquo Vacuum 71 p417-436 (2003)

Typical operational conditions of barrier discharges Typical operational conditions of barrier discharges

Electric field strength E of first breakdown asymp150 Td (p = 1bar T=300 K)

Voltage Vpp 3ndash20 kV

Repetition frequency f 50 Hzndash30 kHz

Pressure p 1ndash3 bar

Gap distance g 02ndash5mm

Dielectric material thickness d 05ndash2mm

Relative dielectric permittivity r 5ndash10 (glass)

B Eliasson and U Kogelschatz IEEE Transactions Plasma Science Vol 19 Issue 6 1063-1077 (1991)B Eliasson and U Kogelschatz IEEE Transactions Plasma Science Vol 19 Issue 6 1063-1077 (1991)

Single and double DBD

Single dielectric Double dielectric

Role of the Dielectric (Insulator)

Th di l t i i th k f thThe dielectric is the key for the properfunctioning of the discharge

Serves two functions

1 Limits the amount of charge transportedby a single microplasma

2 Distributes the microplasmas over theentire electrode surface area

Equivalent Circuit of a Microdischarge

Microdischarge Activity and U-Q Lissajous Figure

B Eliasson and U Kogelschatz IEEE Transactions Plasma Science Vol 19 Issue 6 1063-1077 (1991)

Fundamental Operation of the Dielectric Barrier DischargeFundamental Operation of the Dielectric Barrier Discharge

bull Many of relevant plasma processes that areof importance to achieving our goal occuron time scales that allow us to study themon time scales that allow us to study them

bull Optical emission spectroscopic studies willallow us to determine the temporal andspatial development of important plasmaspatial development of important plasmaspecies such as radicals (OH NO variousoxygen radicals) with high time resolution(less than 10 ns) and a spatial resolution onthe scale of mm in the plasma volumepfollowing pulsed plasma excitation

Time scale of the relevant processes of the DBD

HE Wagner R Brandenburg et al lsquoThe barrier discharge basic properties and applications tosurface treatmentrsquo Vacuum 71 417-436 (2003)

Fundamental Operation of the DBDFundamental Operation of the DBD

Electron DensityTemporal Development (ns)

y

Outer Contour Linen = 1010 cm-3ne = 1010 cm 3

Inner Contour Linene = 1014 cm-3

Streamer Propagation in 1 bar AirAA Kulikovsky IEEE Trans Plasma Sci 25 439-446 (1997)

Numerical Results of Microdischarge Formationin Dielectric Barrier Discharges

Starting Phase of a Microdischarge (1 bar 20 CO2 80 H2)

E0=34 kVcm1010 cm-3

1010 cm-3 ne=1012 cm-3

1mm10 cm

ne=108 cm-3

An electron avalanche propagates towards the anode

Reverse propagationtowards the cathodepropagates towards the anode towards the cathode

Numerical Results of Microdischarge Formationin Dielectric Barrier Discharges

Cathode Layer Formation

E0=34 kVcm1010 cm-39 3 0

1mm

1010 cm-3

10 cmne=109 cm-31014

10131014

1013

10 cm1012

Just before the peak of the total current

Peak currentof the total current

Numerical Results of Microdischarge Formationin Dielectric Barrier Discharges

Local Field Collapse in Area Defined by Surface Discharge

ne=109cm-3 ne=1014 cm-3

Gap

Principals of DBD MicroplasmasPrincipals of DBD MicroplasmasPrincipals of DBD MicroplasmasPrincipals of DBD Microplasmas

C C-- - --- - - CG

CD

-- - - CG

CD

Principals of DBD MicroplasmasPrincipals of DBD MicroplasmasPrincipals of DBD MicroplasmasPrincipals of DBD Microplasmas

Dielectric Barrier Discharge (DBD)Dielectric Barrier Discharge (DBD)Electric Field

B kdBreakdown

Electrons amp Ions Discharge Physics

Excited SpeciesPlasma Chemistry

Chemical Reactions

OzoneGeneration

SurfaceTreatment

PollutionControl

ExcimerFormation CO2 Lasers Hydrogenation

of CO2

Excimer Lamps Plasma Displays

How A Plasma Display Works

How A Plasma Display Work

Plasma Display TelevisionsPlasma Display Televisions

Ozone Generator

3 O 2 O

Dielectric Barrier Discharge

3 O2 2 O3

OO22 OO33++OO22Ondash ndashO3O2

O2O2

Ondash ndash

endash O2Ondash ndash O2endash

O3

O3O2O2 O2

HeatHeatHeatHeat

Properties of Ozone (O3)

T i t i f f Tri-atomic form of oxygen

Most powerful commercial oxidizing agent

Unstable - must be generated and used onsite

Limited solubility in water but more so than oxygenLimited solubility in water but more so than oxygen

Leaves a dissolved residual which ultimately converts back to oxygenconverts back to oxygen

Discharge Tubes in Ozone GeneratorsDischarge Tubes in Ozone Generators

Traditional

Ozone Generator

with Glass Tubes

Generation of OzoneGeneration of Ozone

Generation of OzoneAdvantages of Enamel Dielectrics

Proven Patented Designbull Simplicity

Si l Di l i Cbull Single Dielectric Componentndash Reduced number of Dielectrics

bull Safety ndash Lower operating voltage

(lt 4000 V)bull Reliabilty

ndash Fused Dielectrics ensure continuous production

bull Lowest Power Consumption Operational Savingsndash Operational Savings

Modern Ozone GeneratorModern Ozone Generator

Ozonia Advanced Technology Ozone GeneratorOzone Generator

Generation of OzoneGeneration of Ozone

Generation of Ozone

Power Supply UnitPower Supply Unit

IGBT Inverter CircuitMain Circuit Breaker

HV 480 Volts60 Hz3 Phase Supply

C I

450KVAPow er to

GeneratorFILTER

CONVERTER INVERTERTRANSFORMER

C I450KVA Power Stage

CONTACTOR

bull Latest in Power Semiconductor Technology Modular Design

bull Utilizes IGBTrsquos (Insulated Gate Bi‐Polar Transistors) Converter and Inverter Components

Ozone Water Treatment

B bbl Diff iB bbl Diff iBubble DiffusionBubble Diffusion

Easy to use

Low energy usage Low energy usage

Mass transfer efficiencies to gt 90

Ozone Process Flow DiagramOzone Process Flow DiagramVent to

Atmosphere

O OOxygen

Off-Gas Blower

Ozone Destruct Unit

10 12

O3O2

LOX

10-12 O3

Ozone Generators

Ozone Contact ChamberLOX T k Generators Chamber

VaporizersLOX Tank

Municipal Ozone Installations

Ozonia Installations Ozone Plant Size [lbday] Start-Up DateKey Ozonia Installations (Partial List)

Los Angeles CA 10000 1986Fairfax VA ndash Corbalis 9000 2003MWD CA ndash Mills 9 000 2003

Ozonia Installations Ozone Plant Size [lbday] Start Up Date

MWD CA Mills 9000 2003Fairfax Co VA ndash Griffith 9000 2004MWD CA ndash Jensen 18750 2005Indianapolis IN ndash Belmont AWT 12000 2007I di li IN 12 000 2007Indianapolis IN ndash Southport AWT 12000 2007MWD CA ndash Diemer 13400 2008MWD CA ndash Weymouth 13400 2009

Ozonia North America - Potable Water SummaryTotal Number of Installations 90Total Installed Production gt 265000 lbsdayTotal Installed Production 265000 lbsday

Revision -B

Ozone Water TreatmentOzone Water Treatment

MWD Mills WTP - California

3 3 000 lbsda of o one3 3 000 lbsda of o one3 x 3000 lbsday of ozone3 x 3000 lbsday of ozone

Ozone Water TreatmentOzone Water TreatmentOzone Ozone -- How it worksHow it works

OxidantOxidant DisinfectantDisinfectant

bullbull Breaks double carbon Breaks double carbon bondsbonds

bullbull Kills by cell lysing or Kills by cell lysing or causing the cell wall tocausing the cell wall tobondsbonds

bullbull Creates OHCreates OHbullbull radicals radicals which break higher carbon which break higher carbon

causing the cell wall to causing the cell wall to rupture rupture

bullbull AttacksAttacks allall bacteriabacteriabondsbondsbullbull Increased temp and pH Increased temp and pH

accelerates Oaccelerates O33

Attacks Attacks allall bacteria bacteria virus cysts and spores virus cysts and spores in varying degreesin varying degreesaccelerates Oaccelerates O33

decomposition to OHdecomposition to OHbullbull

Micro-organism DNA

Capsule AdenineAdenine

Cell wall ThymineThymine

CytosineCytosine

GuanineGuanine

NuclearmaterialCellmembrane

material

Typical Bacterium DNA

Microbial Growth at Various Ozone ConcentrationsConcentrations

Growth likely

Growth possibleGrowth possible

NO GROWTH

0004 0008 0012 0016 0020

Ozone concentration (mgl)Ozone concentration (mgl)

Typical Water Treatment UsageTypical Water Treatment Usage

Application O3 mgl Contact timeUltra Pure Water 005 - 025 sec ndash min

Water bottling 04 ndash 10 5 ndash 10 min

Swimming pools ampspas

01 ndash 075 4 minutes

Potable taste amp odor 15 ndash 50 5 ndash 10 mindisinfection

Microfloculation 10 ndash 30 5 ndash 10 min

Lignin amp tammin 3 0 10 0 10 30 minLignin amp tamminremoval

30 ndash 100 10 ndash 30 min

Municipal wastewater 50 ndash 150+ 15 ndash 30 min

Ozone Water TreatmentOzone Water TreatmentOzone Ozone ndashndash Municipal ApplicationsMunicipal Applications

bullbull Taste and OdorTaste and Odor

bullbull Color RemovalColor Removal

bullbull Disinfection Without Trihalomethanes (THMs)Disinfection Without Trihalomethanes (THMs)

bullbull Improved Filtration Efficiency and FlocculationImproved Filtration Efficiency and Flocculation

bullbull Cryptosporidium DeactivationCryptosporidium Deactivation

bullbull Giardia amp Virus InactivationGiardia amp Virus Inactivation

bullbull Oxidation Oxidation -- Organics Fe amp MnOrganics Fe amp Mn

bullbull Wastewater disinfectionWastewater disinfection

bullbull BOD COD and TOC reductionBOD COD and TOC reduction

Applications of Ozone

Wastewater Treatmentbull Disinfection of Secondary and Tertiary Effluentsbull Color Reductionbull Color Reductionbull TOC Oxidation (Industrial)bull Oxidation of Odor Causing Compoundsbull Oxidation of Endocrine Disruptors (EDCrsquos) and p ( )

Pharmaceutically Active Compounds (PACrsquos)

Applications of Ozone

What are Endocrine Disruptors (EDCrsquos) and What are Endocrine Disruptors (EDCrsquos) and Ph ti ll A ti C d (PACrsquo )Ph ti ll A ti C d (PACrsquo )Pharmaceutically Active Compounds (PACrsquos)Pharmaceutically Active Compounds (PACrsquos)

bullbull EDCrsquosEDCrsquos andand PACrsquosPACrsquos areare NaturallyNaturally andand SyntheticSyntheticdd th tth t ff tff t thth b lb l llcompoundscompounds thatthat maymay affectaffect thethe balancebalance oror normalnormal

functionsfunctions inin animalsanimals andand humanshumans

What can EDCrsquos and PACrsquos doWhat can EDCrsquos and PACrsquos do

bullbull Even in very small concentrations these compounds Even in very small concentrations these compounds y py pcan can disruptdisrupt normal bodily functionsnormal bodily functions

bullbull ManMan--made chemicals can trick the bodies endocrine made chemicals can trick the bodies endocrine system system

Applications of Ozone

Examples of Endocrine Disruptors1000rsquos of compounds that may be Investigated as EDCs ndash Some examples are

bullbull Synthetic HormonesSynthetic Hormonesbullbull Naturally Occurring Estrogens Naturally Occurring Estrogens

Health and Beauty AidsHealth and Beauty Aidsbullbull Health and Beauty AidsHealth and Beauty Aidsbullbull SolventsSolventsbullbull PesticidesPesticidesbullbull SurfactantsSurfactantsbullbull PlasticsPlastics

F i idF i idbullbull FungicidesFungicides

Ozone Water TreatmentOzone Water Treatment

Ozone Ozone -- Industrial ApplicationsIndustrial Applications-- Ultrapure Water for Pharmaceutical ApplicationsUltrapure Water for Pharmaceutical Applications

-- Wastewater disinfection color removalWastewater disinfection color removal

-- Soil and Groundwater Remediation Soil and Groundwater Remediation

-- Cooling Tower Water TreatmentCooling Tower Water Treatment

-- Food ProcessingFood Processing

-- Aquaculture AquariumsAquaculture AquariumsAquaculture AquariumsAquaculture Aquariums

-- Beverage ApplicationsBeverage Applications

P l amp P Bl hiP l amp P Bl hi-- Pulp amp Paper BleachingPulp amp Paper Bleaching

High Purity OzonationHigh Purity Ozonation

Microchip manufacturingMicrochip manufacturing

What are the current issues in large-scale gozone generationg

Experimental Setup

Front view of the two units after the redesign and reworking ofthe gas water and instruments connectionsthe gas water and instruments connections

Experimental Setup

Top view of the twoexperimental unitsexperimental unitsSpectroscope (notshown) is to the left ofthe DBD The units weredifferent with respect todifferent with respect totheir electrodes onehad only the electrodecoated with thedielectric (ldquosingle-dielectric ( single-coatedrdquo) the other onehad the electrode andthe anode coated withthe dielectric (ldquodouble-the dielectric ( double-coatedrdquo)

Basics Generation of OzoneBasics Generation of Ozone

SpectroscopyPlasma

Plasma Absorption SpectroscopyPlasma Absorption Spectroscopy

Infrared Absorption SpectroscopyInfrared Absorption Spectroscopy

IR spectra in pure oxygen (black curve) and at approximately 10wt N2 admixture (red line) N2O5 peaks appear at124 1 d 1 2 11245 cm-1 and at 1725 cm-1

Infrared Absorption SpectroscopyInfrared Absorption Spectroscopy

IR spectra of several methane variations The green curve envelopes all of the methane peaks at 1325 cm-1recorded at smaller methane admixtures Simultaneously the N2O5 peaks disappear as the methane peaks appear

N2O5 FormationN2O5 Formation2 52 5p=2 bara cwt=20degC q=35kWm2 f=1450Hz

45N2O5 AT95

30

35

40

N

2 B

lend

ing

N2O AT95N2O5 IGSN2O IGSN2O5 LGN2O LG

1 5

20

25

nt [p

pmV]

3

wt

05

10

15

NO

x co

nten

005 7 9 11 13 15 17

ozone conc [wt]

Amount of formed N2O5 and N2O as a function of ozone concentration at 3 wt of nitrogen admixture and fori l dvarious electrode arrangements

Plasma Emission SpectroscopyPlasma Emission Spectroscopyp pyp py

Relative Emissions of the Ozonizer plasmaRelative Emissions of the Ozonizer plasma

Region 300- 850 nm from individual (calibrated) regions (smoothed by PeakFit) Single-coated ozone generator Inlet side

3 5E+06

30E+06

35E+06

7 9

20E+06

25E+06

nten

sity

au

2

311 12

10E+06

15E+06

In 4

5

6 8 10

14

15

16

17

00E+00

50E+05

280 300 320 340 360 380 400 420 440 460 480 500 520 540 560 580 600 620 640 660 680 700 720 740 760 780 800 820 840 860

Wavelength nm

1 13

Wavelength nm

Absolute Emission of the DBD PlasmaAbsolute Emission of the DBD Plasma

Intensities in (O2+3 wtN2) plasma

1 20E+04

100E+04

120E+04

600E+03

800E+03

nten

sity

(au

)

200E+03

400E+03

In

O(777)

000E+00200 250 300 350 400 450 500 550 600 650 700 750 800 850

Wavelength nm

Intensities in 3 wtN2+O2 plasmaIntensities in 3 wtN2+O2 plasma

Plasma Chemistry in OzonizersPlasma Chemistry in Ozonizers

Dry Air O2 N2

e - e -

O N2 N O2

O3 NO

O2 N O2

O3

N

3

NO2

O2 O3

NO

N

NO2 O3

N2O

NO3 N

N2O4

NO2

NO2

N2O5

NO3

Primary electron-driven chemical reactions leading to the formation of N2O5 and N2O in a dry air plasma

Plasma emission diagnostics role of N2Plasma emission diagnostics role of N2

Dry Air O2 N2

e - e -

O N2 N O2

O3 NO

O2 N O2

O3

O

N

ON

NO2

O2O3

N

NO N

NO2 O3

N2O

NO3 N

N2O4

NO2

NO2

N2O5

NO3

ONbullWith N2 present ndash less oxygen atoms are formed However the difference in intensity is

very small

Modeling of plasma chemistry incl the NxOy chemistry up to N2O5 for different Oxygen Nitrogen mixtures varying power deposition scenarios

and initial ozone background concentrations (up to 15) previously done

The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation

The role of N2 must be related to its by-products reacting on the surface of the electrodeThe role of N2 must be related to its by-products reacting on the surface of the electrode

The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established

Ab 8 t f O

The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established

Ab 8 t f OAbove 8 wt of O3

1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)

Above 8 wt of O3

1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)case without pampp)

2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of the

case without pampp)

2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of thethem A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface

them A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface

The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation

Three possibilities have to be considered for the oxygen-fedozone generator

Three possibilities have to be considered for the oxygen-fedozone generatorozone generator

bull Excited N2 molecules lead to an increased O2 dissociation in

ozone generator

bull Excited N2 molecules lead to an increased O2 dissociation in2 2such case an increased efficiency is correlated to the N2admixture

2 2such case an increased efficiency is correlated to the N2admixture

bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial

bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial

bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2

bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2g p g 3 pp y 2g p g 3 pp y 2

Effect of methane on ozone efficiency and specific powerEffect of methane on ozone efficiency and specific power

Effect of Methane on Ozone Content in Outlet Gas and on Specific Power Pure O2

13 12

10

11

12

t 8

10

8

9

10

ne c

onte

nt w

t

6

8

ecifi

c po

wer

kW

hlb

5

6

7

Ozo

n

2

4 Spe

400E+00 20E+03 40E+03 60E+03 80E+03 10E+04 12E+04

Methane in feedgas ppm

0

Ozone content in the outlet gas Specif ic pow er of the ozone generatorg p p g

Effects of N2 and CH4Effects of N2 and CH4

Pi t f h t lli N O t tPicture of an amorphous-crystalline N2O5 structurecaptured at the Orlando Skylake water plant in 2006

Plasma Chemistry with CH4 Impurities

OxygenO2 N2

e - e -

CHO N2

NO2

O NO

O2 N O2 O3

NOH

CH4e-

O3 NO

NO2

O2O3NO N

NO2 O

NO2

NO2

N2ONO3

N

O3

NO2

NO

HNO3

N2O4

N2O5

NO2

NO3

N2O5

Effect of methane on the electrode surfaces

a) b)

Inlet Outlet Outlet

) d)

I l t I l t

c) d)

Electrode of the ozone generator afterseveral hours in CH8O2 and up to 2 wt of methane (a b c)

Inlet Inlet

three hours in CH8O2+traces of N2 and up to 1 wt of methane (d) Visible change of discharge character at about 13 length of electrode (a d)

Kinetics of CHx Conversion without N2

conversion by collisions

O2 + CHx 12wt O3 + CO2 +H2O

deposition vaporizationby sputtering

ibl b l 1000 CHreversible process below 1000ppm CH4

Effect of water on electrode surface with N2

Inlet

OutletOutlet

Electrode of the ozone generator after several hours in H OO N

Inlet

Electrode of the ozone generator after several hours in H2OO2N2

Effect of water on electrode surface

Long term effect (800 hrs) of H2OO2N2

Kinetics of CHx Conversion with N2

conversion by collisionsHNO3 formation

O2 + N2 +CHx 12wtO2 + CO2 +H2O + HNO3

deposition vaporizationby sputtering

H2O + HNO3

by sputtering

irreversible process above a N2 threshold () ltlt 1000ppm N2

sticky deposit

p 2 ( ) pp 2 any CH4 concentration (60ppm)

Plasma Chemistry with CH4 ImpuritiesPlasma Chemistry with CH4 Impurities4

bull Formation of NO and NO2 depends on O3 N2 and gas temperature Conclusion N2 admixture is the key factor

SummarySummaryyyThe mechanisms of formed NOx by-products follows the sameThe mechanisms of formed NOx by-products follows the sameprinciples as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentration

principles as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentrationozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)

ozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)g p ( g p )

The conversion of methane to OH and H2O is found to depend on

g p ( g p )

The conversion of methane to OH and H2O is found to depend ondissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)

dissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)discharge gap)discharge gap)

How do you optimize an ozone generatorg

Scientific ApproachScientific ApproachTheoretical Experimental

pppp

c [wt]

f [Hz]

c [wt]

f [Hz]

[kW]UUUβ1

1Cf4αPn

1iiminpeakimin

iiD

q [kWm2]q [kWm2]

150

180

][V]voltagepeakUpeak

[]cylinder perslicesofamountnsliceii

whereth

09 00

30

60

90

120

effic

ienc

y [

][0tdj t bl[F]sliceisdielectricofecapacitancC

[Hz]frequencyf[V]sliceivoltageminimumiUmin

thiD

th

10

28

46

64

82

39

107

176

244 power density

[kWm2]

ozone conc [wt][]CCβ

][0parameteradjustableα

iDiGi

Impact of Power Inductionp

350

400

wer

200

250

300

App

lied

Pow

Arr C 2Arr D +0

Arr E +45Arr F +7

Arr G +3

5 0

100

150

Frac

tion

of

1 2 3 4

ReferenceArr B unstable

Arr C -2

00

50

4Position (1inlet 4outlet)

Experimental Test Rigp g

Experimental Test Rigp g

Outer grounded electrode (left picture) and the dielectric covered inner electrodes (right) d e ect c cove ed e e ect odes ( g t)

Reference (Traditional) Arrangement

Inlet OutletGas flow direction

Optimized Arrangement

Inlet OutletGas flow direction

Intelligent Gap System (IGS)g p y ( )

Molecular Oxygen (O2) Ozone (O3)

O2 O3

yg ( 2) ( 3)

Particle Size SynthesisParticle Size SynthesisByBy--Products Cluster FormationProducts Cluster Formationyy

high diffusion and deposition to surfaces

low diffusion rate good transport

high sedimentation on the structurehigh sedimentation on the structure

Degreacutemont Technologies ndash OzoniaIntelligent Gap SystemIntelligent Gap System

G Vezzuacute JL Lopez A Freilich and K Becker Optimizationof Large-Scale Ozone Generators IEEE Transactions onPlasma Science Vol 37 No 6 p 890-896 (2009)

ConclusionsConclusionsConclusionsConclusionsFundamentals of ozone synthesis in a DBD plasmay p

ndash Highly filamented DBD discharges are best-suitedfor the production of ozone concentrations in therange of 6 to 14 wtrange of 6 to 14 wt

ndash The preferred characteristic of the microdischargesare Townsend-like at reduced electric fields Enaround 190 Townsend

ndash Detrimental side-effects induced by by-productscan be avoided by a proper design of the electrodecan be avoided by a proper design of the electrodearrangement The phenomenon is related to thediffusion rates of formed by-product clusters

ConclusionsConclusionsConclusionsConclusionsBenefits from DBD microplasma tailoring

ndash Reduced power consumption of up to 10 improvement

ndash Increased ozone concentrations of up to 14 now achievable

ndash Improved neutralization and conditioning of detrimental by-products

ndash Reduced system capital and operational cost

New technologies to improve ozone p

generatorg

HV Pulsed Power SwitchingHV Pulsed Power Switching

Microchannel Generation of Ozone

Channel ArrayChannel Array

Microchannel

330 microm 230 microm

Some Cap-DBD Devices Operating in Air

Increase of 60 of

Spacing 225 μmof 60 of plasma

No space

Cap‐DBD ozone generation

bull Ozone concentration is evaluated via Eco S d l UV 100 O A l (0 01Sensors model UV-100 Ozone Analyzer (001 ndash 900 ppm wiht an accuracy of plusmn2)

bull Three reactors 6 tubings 6rdquo with spacings of 0 μm 225 μm and 500 μm running at 3 kV μ μ μ g

SpacingOzone Concentration

3 kV rms 4 kV rms3 kV rms 4 kV rms

0 μm 660 ppm

225 μm 550 ppm

For a device of such small scale these ozone levels are promising

500 μm 380 ppm

J Mahoney W Zhu VS Johnson KH Becker and JL Lopez Electrical and optical emissionmeasurements of a capillary dielectric barrier discharge European Physics Journal D Vol 60 441-447(2010)

QuestionsQuestions

Thank YouFor more informationProf Jose L Lopez PhD

Thank YouFor more informationDepartment of Physics

Telephone (973) 761-9057Email joselopez1shuedu

Website wwwshueduacademicsartsciphysicsWebsite wwwshueduacademicsartsciphysics

Page 9: Dielectric Barrier Discharge (DBD) & Progress in Large ...bonitz/si12/talks/august_8/lopez_si12.pdf · Dielectric Barrier Discharge (DBD) & Progress in Large-Scale Ozone Generation

Hot vs Cold PlasmasHot vs Cold Plasmas

LowLow--Temperature (ldquoColdrdquo) PlasmasTemperature (ldquoColdrdquo) Plasmas[Non[Non--equilibrium Nonequilibrium Non--Thermal]Thermal][Non[Non equilibrium Nonequilibrium Non Thermal]Thermal]

How do we make plasmasHow do we make plasmas

Supply Energyeg Heat transfer radiation electric powerhellip

For many plasma applicationsFor many plasma applications an Electric Field is applied to a gaseous environment

Plasma or Gaseous DischargePlasma or Gaseous Discharge

LowLow--Pressure Glow Discharge PlasmasPressure Glow Discharge Plasmas

Plasmas are easier to be generated at low pressures

Low pressure plasmas (1 T f T )

at low pressures

are well understood

are used extensively nowadays

(1 mTorr ~ a few Torr)

are used extensively nowadays (eg in semiconductor industry for computer chips manufacturing)

However to generate low pressure plasmas

vacuum chambers + + = expensive vacuum pumps

pressure monitoring and pressure control devices

+ + =Generate Plasmas at Atmospheric PressureGenerate Plasmas at Atmospheric Pressure

What happens at air pressureWhat happens at air pressure

bull No vacuum is involvedDiffi l d ibull Difficult to generate and sustain

bull Run into some challenges such as glow toarc transition ndash Non controllable

Arc Discharge thermal plasma-Itrsquos hot and detrimental-Gas temperature can reach as high as 2x104 KGas temperature can reach as high as 2x10 K- Low voltage drop at cathode- High cathode current density

High Pressure Microplasmas

Stabilization of high-pressure plasmas ldquopd scalingrdquo ldquoprdquo uarr soplasmas pd scaling p uarr so ldquodrdquo darr to keep breakdown voltage low and minimize instabilities after breakdown -

MicroplasmasDimension a few millimeterDimension a few millimeter down to and below 100 m

Paschen Breakdown CurveH H i 60 100Human Hair 60 ndash 100 m

How do we solve this problemHow do we solve this problem

Transient (pulsed) plasmas In atmospheric plasmas for efficient gas heating atleast 100-1000 collisions are necessary Thus if the plasma duration is shorterleast 100 1000 collisions are necessary Thus if the plasma duration is shorterthan 10-6 ndash 10-5 s gas heating is limited Of course for practical purposes suchplasma has to be operated in a repetitive mode eg in trains of microsecondpulses with millisecond intervals

Micro-confinement Gas heating occurs in the plasma volume and the energy iscarried away by thermal diffusionconvection to the outside If the plasma has asmall volume and a relatively large surface gas heating is limited

Dielectric Barrier Discharges These plasmas are typically created betweenmetal plates which are covered by a thin layer of dielectric or highly resistivematerial The dielectric layer plays an important role in suppressing the currentthe cathodeanode layer is charged by incoming positive ionselectrons whichreduces the electric field and hinders charge transport towards the electrodeDBD also has a large surface-to-volume ratio which promotes diffusion lossesand maintains a low gas temperatureand maintains a low gas temperature

Advantages of Microplasmas Advantages of Microplasmas

bull Low-cost of implementationpbull System flexibilitybull Atmospheric pressure operationbull High densities and high reaction ratesbull High densities and high reaction ratesbull Fast and efficient processesbull Easy to generate and sustain for a variety of gas mixtures

Gl lik d diffbull Glow-like and diffusebull Non-equilibrium (Te gt Tg) to thermalbull Unique chemistryq y

hellip a new realm of plasma sciencehellip a new realm of plasma science

What can we do with microplasmasWhat can we do with microplasmas

Material Synthesis Plasma display Surface Treatment Lighting

OzoneOzone generation for water cleaning

Bio-applicationMaterial processing Dental application

and Many morehellip

Some High Pressure microplasma reactors Some High Pressure microplasma reactors

Dielectric Barrier Discharge (DBD)Dielectric Barrier Discharge (DBD)

Hi h V l

HighVoltage

High VoltageElectrode

ACGenerator

DielectricBarrier

Generator

G

Microplasmas

GroundElectrode

Faradayrsquos Dielectric CapacitorsFaradayrsquos Dielectric Capacitors

Faradays Dielectric Capacitor (circa 1837)

Michael Faraday (1781 ndash 1867) Capacitance INCREASED

Historical Ozone Tube of W Siemens (1857)Historical Ozone Tube of W Siemens (1857)

Werner v SiemensP d frsquo A l d Ch i d Ph ik 102 66 (1857)Poggendorfrsquos Annalen der Chemie und Physik 102 66 (1857)

ldquoOzone Production in an Atmospheric-PressureDielectric Barrier Dischargerdquo

Dielectric Barrier Discharge

Dielectric Barrier DischargeDielectric - Barrier Discharge ConfigurationsHigh

VoltageAC

Generator

High VoltageElectrode

DielectricBarrier

DielectricBarrier

High VoltageElectrode

Discharge

DischargeGeneratorGround

Electrode

Electrode

GroundElectrode

Discharge

H E Wagner R Brandenburg et al lsquoThe barrier discharge basic properties and applications toHE Wagner R Brandenburg et al The barrier discharge basic properties and applications tosurface treatmentrsquo Vacuum 71 p417-436 (2003)

Typical operational conditions of barrier discharges Typical operational conditions of barrier discharges

Electric field strength E of first breakdown asymp150 Td (p = 1bar T=300 K)

Voltage Vpp 3ndash20 kV

Repetition frequency f 50 Hzndash30 kHz

Pressure p 1ndash3 bar

Gap distance g 02ndash5mm

Dielectric material thickness d 05ndash2mm

Relative dielectric permittivity r 5ndash10 (glass)

B Eliasson and U Kogelschatz IEEE Transactions Plasma Science Vol 19 Issue 6 1063-1077 (1991)B Eliasson and U Kogelschatz IEEE Transactions Plasma Science Vol 19 Issue 6 1063-1077 (1991)

Single and double DBD

Single dielectric Double dielectric

Role of the Dielectric (Insulator)

Th di l t i i th k f thThe dielectric is the key for the properfunctioning of the discharge

Serves two functions

1 Limits the amount of charge transportedby a single microplasma

2 Distributes the microplasmas over theentire electrode surface area

Equivalent Circuit of a Microdischarge

Microdischarge Activity and U-Q Lissajous Figure

B Eliasson and U Kogelschatz IEEE Transactions Plasma Science Vol 19 Issue 6 1063-1077 (1991)

Fundamental Operation of the Dielectric Barrier DischargeFundamental Operation of the Dielectric Barrier Discharge

bull Many of relevant plasma processes that areof importance to achieving our goal occuron time scales that allow us to study themon time scales that allow us to study them

bull Optical emission spectroscopic studies willallow us to determine the temporal andspatial development of important plasmaspatial development of important plasmaspecies such as radicals (OH NO variousoxygen radicals) with high time resolution(less than 10 ns) and a spatial resolution onthe scale of mm in the plasma volumepfollowing pulsed plasma excitation

Time scale of the relevant processes of the DBD

HE Wagner R Brandenburg et al lsquoThe barrier discharge basic properties and applications tosurface treatmentrsquo Vacuum 71 417-436 (2003)

Fundamental Operation of the DBDFundamental Operation of the DBD

Electron DensityTemporal Development (ns)

y

Outer Contour Linen = 1010 cm-3ne = 1010 cm 3

Inner Contour Linene = 1014 cm-3

Streamer Propagation in 1 bar AirAA Kulikovsky IEEE Trans Plasma Sci 25 439-446 (1997)

Numerical Results of Microdischarge Formationin Dielectric Barrier Discharges

Starting Phase of a Microdischarge (1 bar 20 CO2 80 H2)

E0=34 kVcm1010 cm-3

1010 cm-3 ne=1012 cm-3

1mm10 cm

ne=108 cm-3

An electron avalanche propagates towards the anode

Reverse propagationtowards the cathodepropagates towards the anode towards the cathode

Numerical Results of Microdischarge Formationin Dielectric Barrier Discharges

Cathode Layer Formation

E0=34 kVcm1010 cm-39 3 0

1mm

1010 cm-3

10 cmne=109 cm-31014

10131014

1013

10 cm1012

Just before the peak of the total current

Peak currentof the total current

Numerical Results of Microdischarge Formationin Dielectric Barrier Discharges

Local Field Collapse in Area Defined by Surface Discharge

ne=109cm-3 ne=1014 cm-3

Gap

Principals of DBD MicroplasmasPrincipals of DBD MicroplasmasPrincipals of DBD MicroplasmasPrincipals of DBD Microplasmas

C C-- - --- - - CG

CD

-- - - CG

CD

Principals of DBD MicroplasmasPrincipals of DBD MicroplasmasPrincipals of DBD MicroplasmasPrincipals of DBD Microplasmas

Dielectric Barrier Discharge (DBD)Dielectric Barrier Discharge (DBD)Electric Field

B kdBreakdown

Electrons amp Ions Discharge Physics

Excited SpeciesPlasma Chemistry

Chemical Reactions

OzoneGeneration

SurfaceTreatment

PollutionControl

ExcimerFormation CO2 Lasers Hydrogenation

of CO2

Excimer Lamps Plasma Displays

How A Plasma Display Works

How A Plasma Display Work

Plasma Display TelevisionsPlasma Display Televisions

Ozone Generator

3 O 2 O

Dielectric Barrier Discharge

3 O2 2 O3

OO22 OO33++OO22Ondash ndashO3O2

O2O2

Ondash ndash

endash O2Ondash ndash O2endash

O3

O3O2O2 O2

HeatHeatHeatHeat

Properties of Ozone (O3)

T i t i f f Tri-atomic form of oxygen

Most powerful commercial oxidizing agent

Unstable - must be generated and used onsite

Limited solubility in water but more so than oxygenLimited solubility in water but more so than oxygen

Leaves a dissolved residual which ultimately converts back to oxygenconverts back to oxygen

Discharge Tubes in Ozone GeneratorsDischarge Tubes in Ozone Generators

Traditional

Ozone Generator

with Glass Tubes

Generation of OzoneGeneration of Ozone

Generation of OzoneAdvantages of Enamel Dielectrics

Proven Patented Designbull Simplicity

Si l Di l i Cbull Single Dielectric Componentndash Reduced number of Dielectrics

bull Safety ndash Lower operating voltage

(lt 4000 V)bull Reliabilty

ndash Fused Dielectrics ensure continuous production

bull Lowest Power Consumption Operational Savingsndash Operational Savings

Modern Ozone GeneratorModern Ozone Generator

Ozonia Advanced Technology Ozone GeneratorOzone Generator

Generation of OzoneGeneration of Ozone

Generation of Ozone

Power Supply UnitPower Supply Unit

IGBT Inverter CircuitMain Circuit Breaker

HV 480 Volts60 Hz3 Phase Supply

C I

450KVAPow er to

GeneratorFILTER

CONVERTER INVERTERTRANSFORMER

C I450KVA Power Stage

CONTACTOR

bull Latest in Power Semiconductor Technology Modular Design

bull Utilizes IGBTrsquos (Insulated Gate Bi‐Polar Transistors) Converter and Inverter Components

Ozone Water Treatment

B bbl Diff iB bbl Diff iBubble DiffusionBubble Diffusion

Easy to use

Low energy usage Low energy usage

Mass transfer efficiencies to gt 90

Ozone Process Flow DiagramOzone Process Flow DiagramVent to

Atmosphere

O OOxygen

Off-Gas Blower

Ozone Destruct Unit

10 12

O3O2

LOX

10-12 O3

Ozone Generators

Ozone Contact ChamberLOX T k Generators Chamber

VaporizersLOX Tank

Municipal Ozone Installations

Ozonia Installations Ozone Plant Size [lbday] Start-Up DateKey Ozonia Installations (Partial List)

Los Angeles CA 10000 1986Fairfax VA ndash Corbalis 9000 2003MWD CA ndash Mills 9 000 2003

Ozonia Installations Ozone Plant Size [lbday] Start Up Date

MWD CA Mills 9000 2003Fairfax Co VA ndash Griffith 9000 2004MWD CA ndash Jensen 18750 2005Indianapolis IN ndash Belmont AWT 12000 2007I di li IN 12 000 2007Indianapolis IN ndash Southport AWT 12000 2007MWD CA ndash Diemer 13400 2008MWD CA ndash Weymouth 13400 2009

Ozonia North America - Potable Water SummaryTotal Number of Installations 90Total Installed Production gt 265000 lbsdayTotal Installed Production 265000 lbsday

Revision -B

Ozone Water TreatmentOzone Water Treatment

MWD Mills WTP - California

3 3 000 lbsda of o one3 3 000 lbsda of o one3 x 3000 lbsday of ozone3 x 3000 lbsday of ozone

Ozone Water TreatmentOzone Water TreatmentOzone Ozone -- How it worksHow it works

OxidantOxidant DisinfectantDisinfectant

bullbull Breaks double carbon Breaks double carbon bondsbonds

bullbull Kills by cell lysing or Kills by cell lysing or causing the cell wall tocausing the cell wall tobondsbonds

bullbull Creates OHCreates OHbullbull radicals radicals which break higher carbon which break higher carbon

causing the cell wall to causing the cell wall to rupture rupture

bullbull AttacksAttacks allall bacteriabacteriabondsbondsbullbull Increased temp and pH Increased temp and pH

accelerates Oaccelerates O33

Attacks Attacks allall bacteria bacteria virus cysts and spores virus cysts and spores in varying degreesin varying degreesaccelerates Oaccelerates O33

decomposition to OHdecomposition to OHbullbull

Micro-organism DNA

Capsule AdenineAdenine

Cell wall ThymineThymine

CytosineCytosine

GuanineGuanine

NuclearmaterialCellmembrane

material

Typical Bacterium DNA

Microbial Growth at Various Ozone ConcentrationsConcentrations

Growth likely

Growth possibleGrowth possible

NO GROWTH

0004 0008 0012 0016 0020

Ozone concentration (mgl)Ozone concentration (mgl)

Typical Water Treatment UsageTypical Water Treatment Usage

Application O3 mgl Contact timeUltra Pure Water 005 - 025 sec ndash min

Water bottling 04 ndash 10 5 ndash 10 min

Swimming pools ampspas

01 ndash 075 4 minutes

Potable taste amp odor 15 ndash 50 5 ndash 10 mindisinfection

Microfloculation 10 ndash 30 5 ndash 10 min

Lignin amp tammin 3 0 10 0 10 30 minLignin amp tamminremoval

30 ndash 100 10 ndash 30 min

Municipal wastewater 50 ndash 150+ 15 ndash 30 min

Ozone Water TreatmentOzone Water TreatmentOzone Ozone ndashndash Municipal ApplicationsMunicipal Applications

bullbull Taste and OdorTaste and Odor

bullbull Color RemovalColor Removal

bullbull Disinfection Without Trihalomethanes (THMs)Disinfection Without Trihalomethanes (THMs)

bullbull Improved Filtration Efficiency and FlocculationImproved Filtration Efficiency and Flocculation

bullbull Cryptosporidium DeactivationCryptosporidium Deactivation

bullbull Giardia amp Virus InactivationGiardia amp Virus Inactivation

bullbull Oxidation Oxidation -- Organics Fe amp MnOrganics Fe amp Mn

bullbull Wastewater disinfectionWastewater disinfection

bullbull BOD COD and TOC reductionBOD COD and TOC reduction

Applications of Ozone

Wastewater Treatmentbull Disinfection of Secondary and Tertiary Effluentsbull Color Reductionbull Color Reductionbull TOC Oxidation (Industrial)bull Oxidation of Odor Causing Compoundsbull Oxidation of Endocrine Disruptors (EDCrsquos) and p ( )

Pharmaceutically Active Compounds (PACrsquos)

Applications of Ozone

What are Endocrine Disruptors (EDCrsquos) and What are Endocrine Disruptors (EDCrsquos) and Ph ti ll A ti C d (PACrsquo )Ph ti ll A ti C d (PACrsquo )Pharmaceutically Active Compounds (PACrsquos)Pharmaceutically Active Compounds (PACrsquos)

bullbull EDCrsquosEDCrsquos andand PACrsquosPACrsquos areare NaturallyNaturally andand SyntheticSyntheticdd th tth t ff tff t thth b lb l llcompoundscompounds thatthat maymay affectaffect thethe balancebalance oror normalnormal

functionsfunctions inin animalsanimals andand humanshumans

What can EDCrsquos and PACrsquos doWhat can EDCrsquos and PACrsquos do

bullbull Even in very small concentrations these compounds Even in very small concentrations these compounds y py pcan can disruptdisrupt normal bodily functionsnormal bodily functions

bullbull ManMan--made chemicals can trick the bodies endocrine made chemicals can trick the bodies endocrine system system

Applications of Ozone

Examples of Endocrine Disruptors1000rsquos of compounds that may be Investigated as EDCs ndash Some examples are

bullbull Synthetic HormonesSynthetic Hormonesbullbull Naturally Occurring Estrogens Naturally Occurring Estrogens

Health and Beauty AidsHealth and Beauty Aidsbullbull Health and Beauty AidsHealth and Beauty Aidsbullbull SolventsSolventsbullbull PesticidesPesticidesbullbull SurfactantsSurfactantsbullbull PlasticsPlastics

F i idF i idbullbull FungicidesFungicides

Ozone Water TreatmentOzone Water Treatment

Ozone Ozone -- Industrial ApplicationsIndustrial Applications-- Ultrapure Water for Pharmaceutical ApplicationsUltrapure Water for Pharmaceutical Applications

-- Wastewater disinfection color removalWastewater disinfection color removal

-- Soil and Groundwater Remediation Soil and Groundwater Remediation

-- Cooling Tower Water TreatmentCooling Tower Water Treatment

-- Food ProcessingFood Processing

-- Aquaculture AquariumsAquaculture AquariumsAquaculture AquariumsAquaculture Aquariums

-- Beverage ApplicationsBeverage Applications

P l amp P Bl hiP l amp P Bl hi-- Pulp amp Paper BleachingPulp amp Paper Bleaching

High Purity OzonationHigh Purity Ozonation

Microchip manufacturingMicrochip manufacturing

What are the current issues in large-scale gozone generationg

Experimental Setup

Front view of the two units after the redesign and reworking ofthe gas water and instruments connectionsthe gas water and instruments connections

Experimental Setup

Top view of the twoexperimental unitsexperimental unitsSpectroscope (notshown) is to the left ofthe DBD The units weredifferent with respect todifferent with respect totheir electrodes onehad only the electrodecoated with thedielectric (ldquosingle-dielectric ( single-coatedrdquo) the other onehad the electrode andthe anode coated withthe dielectric (ldquodouble-the dielectric ( double-coatedrdquo)

Basics Generation of OzoneBasics Generation of Ozone

SpectroscopyPlasma

Plasma Absorption SpectroscopyPlasma Absorption Spectroscopy

Infrared Absorption SpectroscopyInfrared Absorption Spectroscopy

IR spectra in pure oxygen (black curve) and at approximately 10wt N2 admixture (red line) N2O5 peaks appear at124 1 d 1 2 11245 cm-1 and at 1725 cm-1

Infrared Absorption SpectroscopyInfrared Absorption Spectroscopy

IR spectra of several methane variations The green curve envelopes all of the methane peaks at 1325 cm-1recorded at smaller methane admixtures Simultaneously the N2O5 peaks disappear as the methane peaks appear

N2O5 FormationN2O5 Formation2 52 5p=2 bara cwt=20degC q=35kWm2 f=1450Hz

45N2O5 AT95

30

35

40

N

2 B

lend

ing

N2O AT95N2O5 IGSN2O IGSN2O5 LGN2O LG

1 5

20

25

nt [p

pmV]

3

wt

05

10

15

NO

x co

nten

005 7 9 11 13 15 17

ozone conc [wt]

Amount of formed N2O5 and N2O as a function of ozone concentration at 3 wt of nitrogen admixture and fori l dvarious electrode arrangements

Plasma Emission SpectroscopyPlasma Emission Spectroscopyp pyp py

Relative Emissions of the Ozonizer plasmaRelative Emissions of the Ozonizer plasma

Region 300- 850 nm from individual (calibrated) regions (smoothed by PeakFit) Single-coated ozone generator Inlet side

3 5E+06

30E+06

35E+06

7 9

20E+06

25E+06

nten

sity

au

2

311 12

10E+06

15E+06

In 4

5

6 8 10

14

15

16

17

00E+00

50E+05

280 300 320 340 360 380 400 420 440 460 480 500 520 540 560 580 600 620 640 660 680 700 720 740 760 780 800 820 840 860

Wavelength nm

1 13

Wavelength nm

Absolute Emission of the DBD PlasmaAbsolute Emission of the DBD Plasma

Intensities in (O2+3 wtN2) plasma

1 20E+04

100E+04

120E+04

600E+03

800E+03

nten

sity

(au

)

200E+03

400E+03

In

O(777)

000E+00200 250 300 350 400 450 500 550 600 650 700 750 800 850

Wavelength nm

Intensities in 3 wtN2+O2 plasmaIntensities in 3 wtN2+O2 plasma

Plasma Chemistry in OzonizersPlasma Chemistry in Ozonizers

Dry Air O2 N2

e - e -

O N2 N O2

O3 NO

O2 N O2

O3

N

3

NO2

O2 O3

NO

N

NO2 O3

N2O

NO3 N

N2O4

NO2

NO2

N2O5

NO3

Primary electron-driven chemical reactions leading to the formation of N2O5 and N2O in a dry air plasma

Plasma emission diagnostics role of N2Plasma emission diagnostics role of N2

Dry Air O2 N2

e - e -

O N2 N O2

O3 NO

O2 N O2

O3

O

N

ON

NO2

O2O3

N

NO N

NO2 O3

N2O

NO3 N

N2O4

NO2

NO2

N2O5

NO3

ONbullWith N2 present ndash less oxygen atoms are formed However the difference in intensity is

very small

Modeling of plasma chemistry incl the NxOy chemistry up to N2O5 for different Oxygen Nitrogen mixtures varying power deposition scenarios

and initial ozone background concentrations (up to 15) previously done

The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation

The role of N2 must be related to its by-products reacting on the surface of the electrodeThe role of N2 must be related to its by-products reacting on the surface of the electrode

The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established

Ab 8 t f O

The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established

Ab 8 t f OAbove 8 wt of O3

1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)

Above 8 wt of O3

1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)case without pampp)

2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of the

case without pampp)

2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of thethem A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface

them A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface

The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation

Three possibilities have to be considered for the oxygen-fedozone generator

Three possibilities have to be considered for the oxygen-fedozone generatorozone generator

bull Excited N2 molecules lead to an increased O2 dissociation in

ozone generator

bull Excited N2 molecules lead to an increased O2 dissociation in2 2such case an increased efficiency is correlated to the N2admixture

2 2such case an increased efficiency is correlated to the N2admixture

bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial

bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial

bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2

bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2g p g 3 pp y 2g p g 3 pp y 2

Effect of methane on ozone efficiency and specific powerEffect of methane on ozone efficiency and specific power

Effect of Methane on Ozone Content in Outlet Gas and on Specific Power Pure O2

13 12

10

11

12

t 8

10

8

9

10

ne c

onte

nt w

t

6

8

ecifi

c po

wer

kW

hlb

5

6

7

Ozo

n

2

4 Spe

400E+00 20E+03 40E+03 60E+03 80E+03 10E+04 12E+04

Methane in feedgas ppm

0

Ozone content in the outlet gas Specif ic pow er of the ozone generatorg p p g

Effects of N2 and CH4Effects of N2 and CH4

Pi t f h t lli N O t tPicture of an amorphous-crystalline N2O5 structurecaptured at the Orlando Skylake water plant in 2006

Plasma Chemistry with CH4 Impurities

OxygenO2 N2

e - e -

CHO N2

NO2

O NO

O2 N O2 O3

NOH

CH4e-

O3 NO

NO2

O2O3NO N

NO2 O

NO2

NO2

N2ONO3

N

O3

NO2

NO

HNO3

N2O4

N2O5

NO2

NO3

N2O5

Effect of methane on the electrode surfaces

a) b)

Inlet Outlet Outlet

) d)

I l t I l t

c) d)

Electrode of the ozone generator afterseveral hours in CH8O2 and up to 2 wt of methane (a b c)

Inlet Inlet

three hours in CH8O2+traces of N2 and up to 1 wt of methane (d) Visible change of discharge character at about 13 length of electrode (a d)

Kinetics of CHx Conversion without N2

conversion by collisions

O2 + CHx 12wt O3 + CO2 +H2O

deposition vaporizationby sputtering

ibl b l 1000 CHreversible process below 1000ppm CH4

Effect of water on electrode surface with N2

Inlet

OutletOutlet

Electrode of the ozone generator after several hours in H OO N

Inlet

Electrode of the ozone generator after several hours in H2OO2N2

Effect of water on electrode surface

Long term effect (800 hrs) of H2OO2N2

Kinetics of CHx Conversion with N2

conversion by collisionsHNO3 formation

O2 + N2 +CHx 12wtO2 + CO2 +H2O + HNO3

deposition vaporizationby sputtering

H2O + HNO3

by sputtering

irreversible process above a N2 threshold () ltlt 1000ppm N2

sticky deposit

p 2 ( ) pp 2 any CH4 concentration (60ppm)

Plasma Chemistry with CH4 ImpuritiesPlasma Chemistry with CH4 Impurities4

bull Formation of NO and NO2 depends on O3 N2 and gas temperature Conclusion N2 admixture is the key factor

SummarySummaryyyThe mechanisms of formed NOx by-products follows the sameThe mechanisms of formed NOx by-products follows the sameprinciples as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentration

principles as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentrationozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)

ozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)g p ( g p )

The conversion of methane to OH and H2O is found to depend on

g p ( g p )

The conversion of methane to OH and H2O is found to depend ondissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)

dissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)discharge gap)discharge gap)

How do you optimize an ozone generatorg

Scientific ApproachScientific ApproachTheoretical Experimental

pppp

c [wt]

f [Hz]

c [wt]

f [Hz]

[kW]UUUβ1

1Cf4αPn

1iiminpeakimin

iiD

q [kWm2]q [kWm2]

150

180

][V]voltagepeakUpeak

[]cylinder perslicesofamountnsliceii

whereth

09 00

30

60

90

120

effic

ienc

y [

][0tdj t bl[F]sliceisdielectricofecapacitancC

[Hz]frequencyf[V]sliceivoltageminimumiUmin

thiD

th

10

28

46

64

82

39

107

176

244 power density

[kWm2]

ozone conc [wt][]CCβ

][0parameteradjustableα

iDiGi

Impact of Power Inductionp

350

400

wer

200

250

300

App

lied

Pow

Arr C 2Arr D +0

Arr E +45Arr F +7

Arr G +3

5 0

100

150

Frac

tion

of

1 2 3 4

ReferenceArr B unstable

Arr C -2

00

50

4Position (1inlet 4outlet)

Experimental Test Rigp g

Experimental Test Rigp g

Outer grounded electrode (left picture) and the dielectric covered inner electrodes (right) d e ect c cove ed e e ect odes ( g t)

Reference (Traditional) Arrangement

Inlet OutletGas flow direction

Optimized Arrangement

Inlet OutletGas flow direction

Intelligent Gap System (IGS)g p y ( )

Molecular Oxygen (O2) Ozone (O3)

O2 O3

yg ( 2) ( 3)

Particle Size SynthesisParticle Size SynthesisByBy--Products Cluster FormationProducts Cluster Formationyy

high diffusion and deposition to surfaces

low diffusion rate good transport

high sedimentation on the structurehigh sedimentation on the structure

Degreacutemont Technologies ndash OzoniaIntelligent Gap SystemIntelligent Gap System

G Vezzuacute JL Lopez A Freilich and K Becker Optimizationof Large-Scale Ozone Generators IEEE Transactions onPlasma Science Vol 37 No 6 p 890-896 (2009)

ConclusionsConclusionsConclusionsConclusionsFundamentals of ozone synthesis in a DBD plasmay p

ndash Highly filamented DBD discharges are best-suitedfor the production of ozone concentrations in therange of 6 to 14 wtrange of 6 to 14 wt

ndash The preferred characteristic of the microdischargesare Townsend-like at reduced electric fields Enaround 190 Townsend

ndash Detrimental side-effects induced by by-productscan be avoided by a proper design of the electrodecan be avoided by a proper design of the electrodearrangement The phenomenon is related to thediffusion rates of formed by-product clusters

ConclusionsConclusionsConclusionsConclusionsBenefits from DBD microplasma tailoring

ndash Reduced power consumption of up to 10 improvement

ndash Increased ozone concentrations of up to 14 now achievable

ndash Improved neutralization and conditioning of detrimental by-products

ndash Reduced system capital and operational cost

New technologies to improve ozone p

generatorg

HV Pulsed Power SwitchingHV Pulsed Power Switching

Microchannel Generation of Ozone

Channel ArrayChannel Array

Microchannel

330 microm 230 microm

Some Cap-DBD Devices Operating in Air

Increase of 60 of

Spacing 225 μmof 60 of plasma

No space

Cap‐DBD ozone generation

bull Ozone concentration is evaluated via Eco S d l UV 100 O A l (0 01Sensors model UV-100 Ozone Analyzer (001 ndash 900 ppm wiht an accuracy of plusmn2)

bull Three reactors 6 tubings 6rdquo with spacings of 0 μm 225 μm and 500 μm running at 3 kV μ μ μ g

SpacingOzone Concentration

3 kV rms 4 kV rms3 kV rms 4 kV rms

0 μm 660 ppm

225 μm 550 ppm

For a device of such small scale these ozone levels are promising

500 μm 380 ppm

J Mahoney W Zhu VS Johnson KH Becker and JL Lopez Electrical and optical emissionmeasurements of a capillary dielectric barrier discharge European Physics Journal D Vol 60 441-447(2010)

QuestionsQuestions

Thank YouFor more informationProf Jose L Lopez PhD

Thank YouFor more informationDepartment of Physics

Telephone (973) 761-9057Email joselopez1shuedu

Website wwwshueduacademicsartsciphysicsWebsite wwwshueduacademicsartsciphysics

Page 10: Dielectric Barrier Discharge (DBD) & Progress in Large ...bonitz/si12/talks/august_8/lopez_si12.pdf · Dielectric Barrier Discharge (DBD) & Progress in Large-Scale Ozone Generation

LowLow--Temperature (ldquoColdrdquo) PlasmasTemperature (ldquoColdrdquo) Plasmas[Non[Non--equilibrium Nonequilibrium Non--Thermal]Thermal][Non[Non equilibrium Nonequilibrium Non Thermal]Thermal]

How do we make plasmasHow do we make plasmas

Supply Energyeg Heat transfer radiation electric powerhellip

For many plasma applicationsFor many plasma applications an Electric Field is applied to a gaseous environment

Plasma or Gaseous DischargePlasma or Gaseous Discharge

LowLow--Pressure Glow Discharge PlasmasPressure Glow Discharge Plasmas

Plasmas are easier to be generated at low pressures

Low pressure plasmas (1 T f T )

at low pressures

are well understood

are used extensively nowadays

(1 mTorr ~ a few Torr)

are used extensively nowadays (eg in semiconductor industry for computer chips manufacturing)

However to generate low pressure plasmas

vacuum chambers + + = expensive vacuum pumps

pressure monitoring and pressure control devices

+ + =Generate Plasmas at Atmospheric PressureGenerate Plasmas at Atmospheric Pressure

What happens at air pressureWhat happens at air pressure

bull No vacuum is involvedDiffi l d ibull Difficult to generate and sustain

bull Run into some challenges such as glow toarc transition ndash Non controllable

Arc Discharge thermal plasma-Itrsquos hot and detrimental-Gas temperature can reach as high as 2x104 KGas temperature can reach as high as 2x10 K- Low voltage drop at cathode- High cathode current density

High Pressure Microplasmas

Stabilization of high-pressure plasmas ldquopd scalingrdquo ldquoprdquo uarr soplasmas pd scaling p uarr so ldquodrdquo darr to keep breakdown voltage low and minimize instabilities after breakdown -

MicroplasmasDimension a few millimeterDimension a few millimeter down to and below 100 m

Paschen Breakdown CurveH H i 60 100Human Hair 60 ndash 100 m

How do we solve this problemHow do we solve this problem

Transient (pulsed) plasmas In atmospheric plasmas for efficient gas heating atleast 100-1000 collisions are necessary Thus if the plasma duration is shorterleast 100 1000 collisions are necessary Thus if the plasma duration is shorterthan 10-6 ndash 10-5 s gas heating is limited Of course for practical purposes suchplasma has to be operated in a repetitive mode eg in trains of microsecondpulses with millisecond intervals

Micro-confinement Gas heating occurs in the plasma volume and the energy iscarried away by thermal diffusionconvection to the outside If the plasma has asmall volume and a relatively large surface gas heating is limited

Dielectric Barrier Discharges These plasmas are typically created betweenmetal plates which are covered by a thin layer of dielectric or highly resistivematerial The dielectric layer plays an important role in suppressing the currentthe cathodeanode layer is charged by incoming positive ionselectrons whichreduces the electric field and hinders charge transport towards the electrodeDBD also has a large surface-to-volume ratio which promotes diffusion lossesand maintains a low gas temperatureand maintains a low gas temperature

Advantages of Microplasmas Advantages of Microplasmas

bull Low-cost of implementationpbull System flexibilitybull Atmospheric pressure operationbull High densities and high reaction ratesbull High densities and high reaction ratesbull Fast and efficient processesbull Easy to generate and sustain for a variety of gas mixtures

Gl lik d diffbull Glow-like and diffusebull Non-equilibrium (Te gt Tg) to thermalbull Unique chemistryq y

hellip a new realm of plasma sciencehellip a new realm of plasma science

What can we do with microplasmasWhat can we do with microplasmas

Material Synthesis Plasma display Surface Treatment Lighting

OzoneOzone generation for water cleaning

Bio-applicationMaterial processing Dental application

and Many morehellip

Some High Pressure microplasma reactors Some High Pressure microplasma reactors

Dielectric Barrier Discharge (DBD)Dielectric Barrier Discharge (DBD)

Hi h V l

HighVoltage

High VoltageElectrode

ACGenerator

DielectricBarrier

Generator

G

Microplasmas

GroundElectrode

Faradayrsquos Dielectric CapacitorsFaradayrsquos Dielectric Capacitors

Faradays Dielectric Capacitor (circa 1837)

Michael Faraday (1781 ndash 1867) Capacitance INCREASED

Historical Ozone Tube of W Siemens (1857)Historical Ozone Tube of W Siemens (1857)

Werner v SiemensP d frsquo A l d Ch i d Ph ik 102 66 (1857)Poggendorfrsquos Annalen der Chemie und Physik 102 66 (1857)

ldquoOzone Production in an Atmospheric-PressureDielectric Barrier Dischargerdquo

Dielectric Barrier Discharge

Dielectric Barrier DischargeDielectric - Barrier Discharge ConfigurationsHigh

VoltageAC

Generator

High VoltageElectrode

DielectricBarrier

DielectricBarrier

High VoltageElectrode

Discharge

DischargeGeneratorGround

Electrode

Electrode

GroundElectrode

Discharge

H E Wagner R Brandenburg et al lsquoThe barrier discharge basic properties and applications toHE Wagner R Brandenburg et al The barrier discharge basic properties and applications tosurface treatmentrsquo Vacuum 71 p417-436 (2003)

Typical operational conditions of barrier discharges Typical operational conditions of barrier discharges

Electric field strength E of first breakdown asymp150 Td (p = 1bar T=300 K)

Voltage Vpp 3ndash20 kV

Repetition frequency f 50 Hzndash30 kHz

Pressure p 1ndash3 bar

Gap distance g 02ndash5mm

Dielectric material thickness d 05ndash2mm

Relative dielectric permittivity r 5ndash10 (glass)

B Eliasson and U Kogelschatz IEEE Transactions Plasma Science Vol 19 Issue 6 1063-1077 (1991)B Eliasson and U Kogelschatz IEEE Transactions Plasma Science Vol 19 Issue 6 1063-1077 (1991)

Single and double DBD

Single dielectric Double dielectric

Role of the Dielectric (Insulator)

Th di l t i i th k f thThe dielectric is the key for the properfunctioning of the discharge

Serves two functions

1 Limits the amount of charge transportedby a single microplasma

2 Distributes the microplasmas over theentire electrode surface area

Equivalent Circuit of a Microdischarge

Microdischarge Activity and U-Q Lissajous Figure

B Eliasson and U Kogelschatz IEEE Transactions Plasma Science Vol 19 Issue 6 1063-1077 (1991)

Fundamental Operation of the Dielectric Barrier DischargeFundamental Operation of the Dielectric Barrier Discharge

bull Many of relevant plasma processes that areof importance to achieving our goal occuron time scales that allow us to study themon time scales that allow us to study them

bull Optical emission spectroscopic studies willallow us to determine the temporal andspatial development of important plasmaspatial development of important plasmaspecies such as radicals (OH NO variousoxygen radicals) with high time resolution(less than 10 ns) and a spatial resolution onthe scale of mm in the plasma volumepfollowing pulsed plasma excitation

Time scale of the relevant processes of the DBD

HE Wagner R Brandenburg et al lsquoThe barrier discharge basic properties and applications tosurface treatmentrsquo Vacuum 71 417-436 (2003)

Fundamental Operation of the DBDFundamental Operation of the DBD

Electron DensityTemporal Development (ns)

y

Outer Contour Linen = 1010 cm-3ne = 1010 cm 3

Inner Contour Linene = 1014 cm-3

Streamer Propagation in 1 bar AirAA Kulikovsky IEEE Trans Plasma Sci 25 439-446 (1997)

Numerical Results of Microdischarge Formationin Dielectric Barrier Discharges

Starting Phase of a Microdischarge (1 bar 20 CO2 80 H2)

E0=34 kVcm1010 cm-3

1010 cm-3 ne=1012 cm-3

1mm10 cm

ne=108 cm-3

An electron avalanche propagates towards the anode

Reverse propagationtowards the cathodepropagates towards the anode towards the cathode

Numerical Results of Microdischarge Formationin Dielectric Barrier Discharges

Cathode Layer Formation

E0=34 kVcm1010 cm-39 3 0

1mm

1010 cm-3

10 cmne=109 cm-31014

10131014

1013

10 cm1012

Just before the peak of the total current

Peak currentof the total current

Numerical Results of Microdischarge Formationin Dielectric Barrier Discharges

Local Field Collapse in Area Defined by Surface Discharge

ne=109cm-3 ne=1014 cm-3

Gap

Principals of DBD MicroplasmasPrincipals of DBD MicroplasmasPrincipals of DBD MicroplasmasPrincipals of DBD Microplasmas

C C-- - --- - - CG

CD

-- - - CG

CD

Principals of DBD MicroplasmasPrincipals of DBD MicroplasmasPrincipals of DBD MicroplasmasPrincipals of DBD Microplasmas

Dielectric Barrier Discharge (DBD)Dielectric Barrier Discharge (DBD)Electric Field

B kdBreakdown

Electrons amp Ions Discharge Physics

Excited SpeciesPlasma Chemistry

Chemical Reactions

OzoneGeneration

SurfaceTreatment

PollutionControl

ExcimerFormation CO2 Lasers Hydrogenation

of CO2

Excimer Lamps Plasma Displays

How A Plasma Display Works

How A Plasma Display Work

Plasma Display TelevisionsPlasma Display Televisions

Ozone Generator

3 O 2 O

Dielectric Barrier Discharge

3 O2 2 O3

OO22 OO33++OO22Ondash ndashO3O2

O2O2

Ondash ndash

endash O2Ondash ndash O2endash

O3

O3O2O2 O2

HeatHeatHeatHeat

Properties of Ozone (O3)

T i t i f f Tri-atomic form of oxygen

Most powerful commercial oxidizing agent

Unstable - must be generated and used onsite

Limited solubility in water but more so than oxygenLimited solubility in water but more so than oxygen

Leaves a dissolved residual which ultimately converts back to oxygenconverts back to oxygen

Discharge Tubes in Ozone GeneratorsDischarge Tubes in Ozone Generators

Traditional

Ozone Generator

with Glass Tubes

Generation of OzoneGeneration of Ozone

Generation of OzoneAdvantages of Enamel Dielectrics

Proven Patented Designbull Simplicity

Si l Di l i Cbull Single Dielectric Componentndash Reduced number of Dielectrics

bull Safety ndash Lower operating voltage

(lt 4000 V)bull Reliabilty

ndash Fused Dielectrics ensure continuous production

bull Lowest Power Consumption Operational Savingsndash Operational Savings

Modern Ozone GeneratorModern Ozone Generator

Ozonia Advanced Technology Ozone GeneratorOzone Generator

Generation of OzoneGeneration of Ozone

Generation of Ozone

Power Supply UnitPower Supply Unit

IGBT Inverter CircuitMain Circuit Breaker

HV 480 Volts60 Hz3 Phase Supply

C I

450KVAPow er to

GeneratorFILTER

CONVERTER INVERTERTRANSFORMER

C I450KVA Power Stage

CONTACTOR

bull Latest in Power Semiconductor Technology Modular Design

bull Utilizes IGBTrsquos (Insulated Gate Bi‐Polar Transistors) Converter and Inverter Components

Ozone Water Treatment

B bbl Diff iB bbl Diff iBubble DiffusionBubble Diffusion

Easy to use

Low energy usage Low energy usage

Mass transfer efficiencies to gt 90

Ozone Process Flow DiagramOzone Process Flow DiagramVent to

Atmosphere

O OOxygen

Off-Gas Blower

Ozone Destruct Unit

10 12

O3O2

LOX

10-12 O3

Ozone Generators

Ozone Contact ChamberLOX T k Generators Chamber

VaporizersLOX Tank

Municipal Ozone Installations

Ozonia Installations Ozone Plant Size [lbday] Start-Up DateKey Ozonia Installations (Partial List)

Los Angeles CA 10000 1986Fairfax VA ndash Corbalis 9000 2003MWD CA ndash Mills 9 000 2003

Ozonia Installations Ozone Plant Size [lbday] Start Up Date

MWD CA Mills 9000 2003Fairfax Co VA ndash Griffith 9000 2004MWD CA ndash Jensen 18750 2005Indianapolis IN ndash Belmont AWT 12000 2007I di li IN 12 000 2007Indianapolis IN ndash Southport AWT 12000 2007MWD CA ndash Diemer 13400 2008MWD CA ndash Weymouth 13400 2009

Ozonia North America - Potable Water SummaryTotal Number of Installations 90Total Installed Production gt 265000 lbsdayTotal Installed Production 265000 lbsday

Revision -B

Ozone Water TreatmentOzone Water Treatment

MWD Mills WTP - California

3 3 000 lbsda of o one3 3 000 lbsda of o one3 x 3000 lbsday of ozone3 x 3000 lbsday of ozone

Ozone Water TreatmentOzone Water TreatmentOzone Ozone -- How it worksHow it works

OxidantOxidant DisinfectantDisinfectant

bullbull Breaks double carbon Breaks double carbon bondsbonds

bullbull Kills by cell lysing or Kills by cell lysing or causing the cell wall tocausing the cell wall tobondsbonds

bullbull Creates OHCreates OHbullbull radicals radicals which break higher carbon which break higher carbon

causing the cell wall to causing the cell wall to rupture rupture

bullbull AttacksAttacks allall bacteriabacteriabondsbondsbullbull Increased temp and pH Increased temp and pH

accelerates Oaccelerates O33

Attacks Attacks allall bacteria bacteria virus cysts and spores virus cysts and spores in varying degreesin varying degreesaccelerates Oaccelerates O33

decomposition to OHdecomposition to OHbullbull

Micro-organism DNA

Capsule AdenineAdenine

Cell wall ThymineThymine

CytosineCytosine

GuanineGuanine

NuclearmaterialCellmembrane

material

Typical Bacterium DNA

Microbial Growth at Various Ozone ConcentrationsConcentrations

Growth likely

Growth possibleGrowth possible

NO GROWTH

0004 0008 0012 0016 0020

Ozone concentration (mgl)Ozone concentration (mgl)

Typical Water Treatment UsageTypical Water Treatment Usage

Application O3 mgl Contact timeUltra Pure Water 005 - 025 sec ndash min

Water bottling 04 ndash 10 5 ndash 10 min

Swimming pools ampspas

01 ndash 075 4 minutes

Potable taste amp odor 15 ndash 50 5 ndash 10 mindisinfection

Microfloculation 10 ndash 30 5 ndash 10 min

Lignin amp tammin 3 0 10 0 10 30 minLignin amp tamminremoval

30 ndash 100 10 ndash 30 min

Municipal wastewater 50 ndash 150+ 15 ndash 30 min

Ozone Water TreatmentOzone Water TreatmentOzone Ozone ndashndash Municipal ApplicationsMunicipal Applications

bullbull Taste and OdorTaste and Odor

bullbull Color RemovalColor Removal

bullbull Disinfection Without Trihalomethanes (THMs)Disinfection Without Trihalomethanes (THMs)

bullbull Improved Filtration Efficiency and FlocculationImproved Filtration Efficiency and Flocculation

bullbull Cryptosporidium DeactivationCryptosporidium Deactivation

bullbull Giardia amp Virus InactivationGiardia amp Virus Inactivation

bullbull Oxidation Oxidation -- Organics Fe amp MnOrganics Fe amp Mn

bullbull Wastewater disinfectionWastewater disinfection

bullbull BOD COD and TOC reductionBOD COD and TOC reduction

Applications of Ozone

Wastewater Treatmentbull Disinfection of Secondary and Tertiary Effluentsbull Color Reductionbull Color Reductionbull TOC Oxidation (Industrial)bull Oxidation of Odor Causing Compoundsbull Oxidation of Endocrine Disruptors (EDCrsquos) and p ( )

Pharmaceutically Active Compounds (PACrsquos)

Applications of Ozone

What are Endocrine Disruptors (EDCrsquos) and What are Endocrine Disruptors (EDCrsquos) and Ph ti ll A ti C d (PACrsquo )Ph ti ll A ti C d (PACrsquo )Pharmaceutically Active Compounds (PACrsquos)Pharmaceutically Active Compounds (PACrsquos)

bullbull EDCrsquosEDCrsquos andand PACrsquosPACrsquos areare NaturallyNaturally andand SyntheticSyntheticdd th tth t ff tff t thth b lb l llcompoundscompounds thatthat maymay affectaffect thethe balancebalance oror normalnormal

functionsfunctions inin animalsanimals andand humanshumans

What can EDCrsquos and PACrsquos doWhat can EDCrsquos and PACrsquos do

bullbull Even in very small concentrations these compounds Even in very small concentrations these compounds y py pcan can disruptdisrupt normal bodily functionsnormal bodily functions

bullbull ManMan--made chemicals can trick the bodies endocrine made chemicals can trick the bodies endocrine system system

Applications of Ozone

Examples of Endocrine Disruptors1000rsquos of compounds that may be Investigated as EDCs ndash Some examples are

bullbull Synthetic HormonesSynthetic Hormonesbullbull Naturally Occurring Estrogens Naturally Occurring Estrogens

Health and Beauty AidsHealth and Beauty Aidsbullbull Health and Beauty AidsHealth and Beauty Aidsbullbull SolventsSolventsbullbull PesticidesPesticidesbullbull SurfactantsSurfactantsbullbull PlasticsPlastics

F i idF i idbullbull FungicidesFungicides

Ozone Water TreatmentOzone Water Treatment

Ozone Ozone -- Industrial ApplicationsIndustrial Applications-- Ultrapure Water for Pharmaceutical ApplicationsUltrapure Water for Pharmaceutical Applications

-- Wastewater disinfection color removalWastewater disinfection color removal

-- Soil and Groundwater Remediation Soil and Groundwater Remediation

-- Cooling Tower Water TreatmentCooling Tower Water Treatment

-- Food ProcessingFood Processing

-- Aquaculture AquariumsAquaculture AquariumsAquaculture AquariumsAquaculture Aquariums

-- Beverage ApplicationsBeverage Applications

P l amp P Bl hiP l amp P Bl hi-- Pulp amp Paper BleachingPulp amp Paper Bleaching

High Purity OzonationHigh Purity Ozonation

Microchip manufacturingMicrochip manufacturing

What are the current issues in large-scale gozone generationg

Experimental Setup

Front view of the two units after the redesign and reworking ofthe gas water and instruments connectionsthe gas water and instruments connections

Experimental Setup

Top view of the twoexperimental unitsexperimental unitsSpectroscope (notshown) is to the left ofthe DBD The units weredifferent with respect todifferent with respect totheir electrodes onehad only the electrodecoated with thedielectric (ldquosingle-dielectric ( single-coatedrdquo) the other onehad the electrode andthe anode coated withthe dielectric (ldquodouble-the dielectric ( double-coatedrdquo)

Basics Generation of OzoneBasics Generation of Ozone

SpectroscopyPlasma

Plasma Absorption SpectroscopyPlasma Absorption Spectroscopy

Infrared Absorption SpectroscopyInfrared Absorption Spectroscopy

IR spectra in pure oxygen (black curve) and at approximately 10wt N2 admixture (red line) N2O5 peaks appear at124 1 d 1 2 11245 cm-1 and at 1725 cm-1

Infrared Absorption SpectroscopyInfrared Absorption Spectroscopy

IR spectra of several methane variations The green curve envelopes all of the methane peaks at 1325 cm-1recorded at smaller methane admixtures Simultaneously the N2O5 peaks disappear as the methane peaks appear

N2O5 FormationN2O5 Formation2 52 5p=2 bara cwt=20degC q=35kWm2 f=1450Hz

45N2O5 AT95

30

35

40

N

2 B

lend

ing

N2O AT95N2O5 IGSN2O IGSN2O5 LGN2O LG

1 5

20

25

nt [p

pmV]

3

wt

05

10

15

NO

x co

nten

005 7 9 11 13 15 17

ozone conc [wt]

Amount of formed N2O5 and N2O as a function of ozone concentration at 3 wt of nitrogen admixture and fori l dvarious electrode arrangements

Plasma Emission SpectroscopyPlasma Emission Spectroscopyp pyp py

Relative Emissions of the Ozonizer plasmaRelative Emissions of the Ozonizer plasma

Region 300- 850 nm from individual (calibrated) regions (smoothed by PeakFit) Single-coated ozone generator Inlet side

3 5E+06

30E+06

35E+06

7 9

20E+06

25E+06

nten

sity

au

2

311 12

10E+06

15E+06

In 4

5

6 8 10

14

15

16

17

00E+00

50E+05

280 300 320 340 360 380 400 420 440 460 480 500 520 540 560 580 600 620 640 660 680 700 720 740 760 780 800 820 840 860

Wavelength nm

1 13

Wavelength nm

Absolute Emission of the DBD PlasmaAbsolute Emission of the DBD Plasma

Intensities in (O2+3 wtN2) plasma

1 20E+04

100E+04

120E+04

600E+03

800E+03

nten

sity

(au

)

200E+03

400E+03

In

O(777)

000E+00200 250 300 350 400 450 500 550 600 650 700 750 800 850

Wavelength nm

Intensities in 3 wtN2+O2 plasmaIntensities in 3 wtN2+O2 plasma

Plasma Chemistry in OzonizersPlasma Chemistry in Ozonizers

Dry Air O2 N2

e - e -

O N2 N O2

O3 NO

O2 N O2

O3

N

3

NO2

O2 O3

NO

N

NO2 O3

N2O

NO3 N

N2O4

NO2

NO2

N2O5

NO3

Primary electron-driven chemical reactions leading to the formation of N2O5 and N2O in a dry air plasma

Plasma emission diagnostics role of N2Plasma emission diagnostics role of N2

Dry Air O2 N2

e - e -

O N2 N O2

O3 NO

O2 N O2

O3

O

N

ON

NO2

O2O3

N

NO N

NO2 O3

N2O

NO3 N

N2O4

NO2

NO2

N2O5

NO3

ONbullWith N2 present ndash less oxygen atoms are formed However the difference in intensity is

very small

Modeling of plasma chemistry incl the NxOy chemistry up to N2O5 for different Oxygen Nitrogen mixtures varying power deposition scenarios

and initial ozone background concentrations (up to 15) previously done

The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation

The role of N2 must be related to its by-products reacting on the surface of the electrodeThe role of N2 must be related to its by-products reacting on the surface of the electrode

The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established

Ab 8 t f O

The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established

Ab 8 t f OAbove 8 wt of O3

1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)

Above 8 wt of O3

1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)case without pampp)

2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of the

case without pampp)

2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of thethem A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface

them A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface

The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation

Three possibilities have to be considered for the oxygen-fedozone generator

Three possibilities have to be considered for the oxygen-fedozone generatorozone generator

bull Excited N2 molecules lead to an increased O2 dissociation in

ozone generator

bull Excited N2 molecules lead to an increased O2 dissociation in2 2such case an increased efficiency is correlated to the N2admixture

2 2such case an increased efficiency is correlated to the N2admixture

bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial

bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial

bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2

bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2g p g 3 pp y 2g p g 3 pp y 2

Effect of methane on ozone efficiency and specific powerEffect of methane on ozone efficiency and specific power

Effect of Methane on Ozone Content in Outlet Gas and on Specific Power Pure O2

13 12

10

11

12

t 8

10

8

9

10

ne c

onte

nt w

t

6

8

ecifi

c po

wer

kW

hlb

5

6

7

Ozo

n

2

4 Spe

400E+00 20E+03 40E+03 60E+03 80E+03 10E+04 12E+04

Methane in feedgas ppm

0

Ozone content in the outlet gas Specif ic pow er of the ozone generatorg p p g

Effects of N2 and CH4Effects of N2 and CH4

Pi t f h t lli N O t tPicture of an amorphous-crystalline N2O5 structurecaptured at the Orlando Skylake water plant in 2006

Plasma Chemistry with CH4 Impurities

OxygenO2 N2

e - e -

CHO N2

NO2

O NO

O2 N O2 O3

NOH

CH4e-

O3 NO

NO2

O2O3NO N

NO2 O

NO2

NO2

N2ONO3

N

O3

NO2

NO

HNO3

N2O4

N2O5

NO2

NO3

N2O5

Effect of methane on the electrode surfaces

a) b)

Inlet Outlet Outlet

) d)

I l t I l t

c) d)

Electrode of the ozone generator afterseveral hours in CH8O2 and up to 2 wt of methane (a b c)

Inlet Inlet

three hours in CH8O2+traces of N2 and up to 1 wt of methane (d) Visible change of discharge character at about 13 length of electrode (a d)

Kinetics of CHx Conversion without N2

conversion by collisions

O2 + CHx 12wt O3 + CO2 +H2O

deposition vaporizationby sputtering

ibl b l 1000 CHreversible process below 1000ppm CH4

Effect of water on electrode surface with N2

Inlet

OutletOutlet

Electrode of the ozone generator after several hours in H OO N

Inlet

Electrode of the ozone generator after several hours in H2OO2N2

Effect of water on electrode surface

Long term effect (800 hrs) of H2OO2N2

Kinetics of CHx Conversion with N2

conversion by collisionsHNO3 formation

O2 + N2 +CHx 12wtO2 + CO2 +H2O + HNO3

deposition vaporizationby sputtering

H2O + HNO3

by sputtering

irreversible process above a N2 threshold () ltlt 1000ppm N2

sticky deposit

p 2 ( ) pp 2 any CH4 concentration (60ppm)

Plasma Chemistry with CH4 ImpuritiesPlasma Chemistry with CH4 Impurities4

bull Formation of NO and NO2 depends on O3 N2 and gas temperature Conclusion N2 admixture is the key factor

SummarySummaryyyThe mechanisms of formed NOx by-products follows the sameThe mechanisms of formed NOx by-products follows the sameprinciples as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentration

principles as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentrationozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)

ozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)g p ( g p )

The conversion of methane to OH and H2O is found to depend on

g p ( g p )

The conversion of methane to OH and H2O is found to depend ondissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)

dissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)discharge gap)discharge gap)

How do you optimize an ozone generatorg

Scientific ApproachScientific ApproachTheoretical Experimental

pppp

c [wt]

f [Hz]

c [wt]

f [Hz]

[kW]UUUβ1

1Cf4αPn

1iiminpeakimin

iiD

q [kWm2]q [kWm2]

150

180

][V]voltagepeakUpeak

[]cylinder perslicesofamountnsliceii

whereth

09 00

30

60

90

120

effic

ienc

y [

][0tdj t bl[F]sliceisdielectricofecapacitancC

[Hz]frequencyf[V]sliceivoltageminimumiUmin

thiD

th

10

28

46

64

82

39

107

176

244 power density

[kWm2]

ozone conc [wt][]CCβ

][0parameteradjustableα

iDiGi

Impact of Power Inductionp

350

400

wer

200

250

300

App

lied

Pow

Arr C 2Arr D +0

Arr E +45Arr F +7

Arr G +3

5 0

100

150

Frac

tion

of

1 2 3 4

ReferenceArr B unstable

Arr C -2

00

50

4Position (1inlet 4outlet)

Experimental Test Rigp g

Experimental Test Rigp g

Outer grounded electrode (left picture) and the dielectric covered inner electrodes (right) d e ect c cove ed e e ect odes ( g t)

Reference (Traditional) Arrangement

Inlet OutletGas flow direction

Optimized Arrangement

Inlet OutletGas flow direction

Intelligent Gap System (IGS)g p y ( )

Molecular Oxygen (O2) Ozone (O3)

O2 O3

yg ( 2) ( 3)

Particle Size SynthesisParticle Size SynthesisByBy--Products Cluster FormationProducts Cluster Formationyy

high diffusion and deposition to surfaces

low diffusion rate good transport

high sedimentation on the structurehigh sedimentation on the structure

Degreacutemont Technologies ndash OzoniaIntelligent Gap SystemIntelligent Gap System

G Vezzuacute JL Lopez A Freilich and K Becker Optimizationof Large-Scale Ozone Generators IEEE Transactions onPlasma Science Vol 37 No 6 p 890-896 (2009)

ConclusionsConclusionsConclusionsConclusionsFundamentals of ozone synthesis in a DBD plasmay p

ndash Highly filamented DBD discharges are best-suitedfor the production of ozone concentrations in therange of 6 to 14 wtrange of 6 to 14 wt

ndash The preferred characteristic of the microdischargesare Townsend-like at reduced electric fields Enaround 190 Townsend

ndash Detrimental side-effects induced by by-productscan be avoided by a proper design of the electrodecan be avoided by a proper design of the electrodearrangement The phenomenon is related to thediffusion rates of formed by-product clusters

ConclusionsConclusionsConclusionsConclusionsBenefits from DBD microplasma tailoring

ndash Reduced power consumption of up to 10 improvement

ndash Increased ozone concentrations of up to 14 now achievable

ndash Improved neutralization and conditioning of detrimental by-products

ndash Reduced system capital and operational cost

New technologies to improve ozone p

generatorg

HV Pulsed Power SwitchingHV Pulsed Power Switching

Microchannel Generation of Ozone

Channel ArrayChannel Array

Microchannel

330 microm 230 microm

Some Cap-DBD Devices Operating in Air

Increase of 60 of

Spacing 225 μmof 60 of plasma

No space

Cap‐DBD ozone generation

bull Ozone concentration is evaluated via Eco S d l UV 100 O A l (0 01Sensors model UV-100 Ozone Analyzer (001 ndash 900 ppm wiht an accuracy of plusmn2)

bull Three reactors 6 tubings 6rdquo with spacings of 0 μm 225 μm and 500 μm running at 3 kV μ μ μ g

SpacingOzone Concentration

3 kV rms 4 kV rms3 kV rms 4 kV rms

0 μm 660 ppm

225 μm 550 ppm

For a device of such small scale these ozone levels are promising

500 μm 380 ppm

J Mahoney W Zhu VS Johnson KH Becker and JL Lopez Electrical and optical emissionmeasurements of a capillary dielectric barrier discharge European Physics Journal D Vol 60 441-447(2010)

QuestionsQuestions

Thank YouFor more informationProf Jose L Lopez PhD

Thank YouFor more informationDepartment of Physics

Telephone (973) 761-9057Email joselopez1shuedu

Website wwwshueduacademicsartsciphysicsWebsite wwwshueduacademicsartsciphysics

Page 11: Dielectric Barrier Discharge (DBD) & Progress in Large ...bonitz/si12/talks/august_8/lopez_si12.pdf · Dielectric Barrier Discharge (DBD) & Progress in Large-Scale Ozone Generation

How do we make plasmasHow do we make plasmas

Supply Energyeg Heat transfer radiation electric powerhellip

For many plasma applicationsFor many plasma applications an Electric Field is applied to a gaseous environment

Plasma or Gaseous DischargePlasma or Gaseous Discharge

LowLow--Pressure Glow Discharge PlasmasPressure Glow Discharge Plasmas

Plasmas are easier to be generated at low pressures

Low pressure plasmas (1 T f T )

at low pressures

are well understood

are used extensively nowadays

(1 mTorr ~ a few Torr)

are used extensively nowadays (eg in semiconductor industry for computer chips manufacturing)

However to generate low pressure plasmas

vacuum chambers + + = expensive vacuum pumps

pressure monitoring and pressure control devices

+ + =Generate Plasmas at Atmospheric PressureGenerate Plasmas at Atmospheric Pressure

What happens at air pressureWhat happens at air pressure

bull No vacuum is involvedDiffi l d ibull Difficult to generate and sustain

bull Run into some challenges such as glow toarc transition ndash Non controllable

Arc Discharge thermal plasma-Itrsquos hot and detrimental-Gas temperature can reach as high as 2x104 KGas temperature can reach as high as 2x10 K- Low voltage drop at cathode- High cathode current density

High Pressure Microplasmas

Stabilization of high-pressure plasmas ldquopd scalingrdquo ldquoprdquo uarr soplasmas pd scaling p uarr so ldquodrdquo darr to keep breakdown voltage low and minimize instabilities after breakdown -

MicroplasmasDimension a few millimeterDimension a few millimeter down to and below 100 m

Paschen Breakdown CurveH H i 60 100Human Hair 60 ndash 100 m

How do we solve this problemHow do we solve this problem

Transient (pulsed) plasmas In atmospheric plasmas for efficient gas heating atleast 100-1000 collisions are necessary Thus if the plasma duration is shorterleast 100 1000 collisions are necessary Thus if the plasma duration is shorterthan 10-6 ndash 10-5 s gas heating is limited Of course for practical purposes suchplasma has to be operated in a repetitive mode eg in trains of microsecondpulses with millisecond intervals

Micro-confinement Gas heating occurs in the plasma volume and the energy iscarried away by thermal diffusionconvection to the outside If the plasma has asmall volume and a relatively large surface gas heating is limited

Dielectric Barrier Discharges These plasmas are typically created betweenmetal plates which are covered by a thin layer of dielectric or highly resistivematerial The dielectric layer plays an important role in suppressing the currentthe cathodeanode layer is charged by incoming positive ionselectrons whichreduces the electric field and hinders charge transport towards the electrodeDBD also has a large surface-to-volume ratio which promotes diffusion lossesand maintains a low gas temperatureand maintains a low gas temperature

Advantages of Microplasmas Advantages of Microplasmas

bull Low-cost of implementationpbull System flexibilitybull Atmospheric pressure operationbull High densities and high reaction ratesbull High densities and high reaction ratesbull Fast and efficient processesbull Easy to generate and sustain for a variety of gas mixtures

Gl lik d diffbull Glow-like and diffusebull Non-equilibrium (Te gt Tg) to thermalbull Unique chemistryq y

hellip a new realm of plasma sciencehellip a new realm of plasma science

What can we do with microplasmasWhat can we do with microplasmas

Material Synthesis Plasma display Surface Treatment Lighting

OzoneOzone generation for water cleaning

Bio-applicationMaterial processing Dental application

and Many morehellip

Some High Pressure microplasma reactors Some High Pressure microplasma reactors

Dielectric Barrier Discharge (DBD)Dielectric Barrier Discharge (DBD)

Hi h V l

HighVoltage

High VoltageElectrode

ACGenerator

DielectricBarrier

Generator

G

Microplasmas

GroundElectrode

Faradayrsquos Dielectric CapacitorsFaradayrsquos Dielectric Capacitors

Faradays Dielectric Capacitor (circa 1837)

Michael Faraday (1781 ndash 1867) Capacitance INCREASED

Historical Ozone Tube of W Siemens (1857)Historical Ozone Tube of W Siemens (1857)

Werner v SiemensP d frsquo A l d Ch i d Ph ik 102 66 (1857)Poggendorfrsquos Annalen der Chemie und Physik 102 66 (1857)

ldquoOzone Production in an Atmospheric-PressureDielectric Barrier Dischargerdquo

Dielectric Barrier Discharge

Dielectric Barrier DischargeDielectric - Barrier Discharge ConfigurationsHigh

VoltageAC

Generator

High VoltageElectrode

DielectricBarrier

DielectricBarrier

High VoltageElectrode

Discharge

DischargeGeneratorGround

Electrode

Electrode

GroundElectrode

Discharge

H E Wagner R Brandenburg et al lsquoThe barrier discharge basic properties and applications toHE Wagner R Brandenburg et al The barrier discharge basic properties and applications tosurface treatmentrsquo Vacuum 71 p417-436 (2003)

Typical operational conditions of barrier discharges Typical operational conditions of barrier discharges

Electric field strength E of first breakdown asymp150 Td (p = 1bar T=300 K)

Voltage Vpp 3ndash20 kV

Repetition frequency f 50 Hzndash30 kHz

Pressure p 1ndash3 bar

Gap distance g 02ndash5mm

Dielectric material thickness d 05ndash2mm

Relative dielectric permittivity r 5ndash10 (glass)

B Eliasson and U Kogelschatz IEEE Transactions Plasma Science Vol 19 Issue 6 1063-1077 (1991)B Eliasson and U Kogelschatz IEEE Transactions Plasma Science Vol 19 Issue 6 1063-1077 (1991)

Single and double DBD

Single dielectric Double dielectric

Role of the Dielectric (Insulator)

Th di l t i i th k f thThe dielectric is the key for the properfunctioning of the discharge

Serves two functions

1 Limits the amount of charge transportedby a single microplasma

2 Distributes the microplasmas over theentire electrode surface area

Equivalent Circuit of a Microdischarge

Microdischarge Activity and U-Q Lissajous Figure

B Eliasson and U Kogelschatz IEEE Transactions Plasma Science Vol 19 Issue 6 1063-1077 (1991)

Fundamental Operation of the Dielectric Barrier DischargeFundamental Operation of the Dielectric Barrier Discharge

bull Many of relevant plasma processes that areof importance to achieving our goal occuron time scales that allow us to study themon time scales that allow us to study them

bull Optical emission spectroscopic studies willallow us to determine the temporal andspatial development of important plasmaspatial development of important plasmaspecies such as radicals (OH NO variousoxygen radicals) with high time resolution(less than 10 ns) and a spatial resolution onthe scale of mm in the plasma volumepfollowing pulsed plasma excitation

Time scale of the relevant processes of the DBD

HE Wagner R Brandenburg et al lsquoThe barrier discharge basic properties and applications tosurface treatmentrsquo Vacuum 71 417-436 (2003)

Fundamental Operation of the DBDFundamental Operation of the DBD

Electron DensityTemporal Development (ns)

y

Outer Contour Linen = 1010 cm-3ne = 1010 cm 3

Inner Contour Linene = 1014 cm-3

Streamer Propagation in 1 bar AirAA Kulikovsky IEEE Trans Plasma Sci 25 439-446 (1997)

Numerical Results of Microdischarge Formationin Dielectric Barrier Discharges

Starting Phase of a Microdischarge (1 bar 20 CO2 80 H2)

E0=34 kVcm1010 cm-3

1010 cm-3 ne=1012 cm-3

1mm10 cm

ne=108 cm-3

An electron avalanche propagates towards the anode

Reverse propagationtowards the cathodepropagates towards the anode towards the cathode

Numerical Results of Microdischarge Formationin Dielectric Barrier Discharges

Cathode Layer Formation

E0=34 kVcm1010 cm-39 3 0

1mm

1010 cm-3

10 cmne=109 cm-31014

10131014

1013

10 cm1012

Just before the peak of the total current

Peak currentof the total current

Numerical Results of Microdischarge Formationin Dielectric Barrier Discharges

Local Field Collapse in Area Defined by Surface Discharge

ne=109cm-3 ne=1014 cm-3

Gap

Principals of DBD MicroplasmasPrincipals of DBD MicroplasmasPrincipals of DBD MicroplasmasPrincipals of DBD Microplasmas

C C-- - --- - - CG

CD

-- - - CG

CD

Principals of DBD MicroplasmasPrincipals of DBD MicroplasmasPrincipals of DBD MicroplasmasPrincipals of DBD Microplasmas

Dielectric Barrier Discharge (DBD)Dielectric Barrier Discharge (DBD)Electric Field

B kdBreakdown

Electrons amp Ions Discharge Physics

Excited SpeciesPlasma Chemistry

Chemical Reactions

OzoneGeneration

SurfaceTreatment

PollutionControl

ExcimerFormation CO2 Lasers Hydrogenation

of CO2

Excimer Lamps Plasma Displays

How A Plasma Display Works

How A Plasma Display Work

Plasma Display TelevisionsPlasma Display Televisions

Ozone Generator

3 O 2 O

Dielectric Barrier Discharge

3 O2 2 O3

OO22 OO33++OO22Ondash ndashO3O2

O2O2

Ondash ndash

endash O2Ondash ndash O2endash

O3

O3O2O2 O2

HeatHeatHeatHeat

Properties of Ozone (O3)

T i t i f f Tri-atomic form of oxygen

Most powerful commercial oxidizing agent

Unstable - must be generated and used onsite

Limited solubility in water but more so than oxygenLimited solubility in water but more so than oxygen

Leaves a dissolved residual which ultimately converts back to oxygenconverts back to oxygen

Discharge Tubes in Ozone GeneratorsDischarge Tubes in Ozone Generators

Traditional

Ozone Generator

with Glass Tubes

Generation of OzoneGeneration of Ozone

Generation of OzoneAdvantages of Enamel Dielectrics

Proven Patented Designbull Simplicity

Si l Di l i Cbull Single Dielectric Componentndash Reduced number of Dielectrics

bull Safety ndash Lower operating voltage

(lt 4000 V)bull Reliabilty

ndash Fused Dielectrics ensure continuous production

bull Lowest Power Consumption Operational Savingsndash Operational Savings

Modern Ozone GeneratorModern Ozone Generator

Ozonia Advanced Technology Ozone GeneratorOzone Generator

Generation of OzoneGeneration of Ozone

Generation of Ozone

Power Supply UnitPower Supply Unit

IGBT Inverter CircuitMain Circuit Breaker

HV 480 Volts60 Hz3 Phase Supply

C I

450KVAPow er to

GeneratorFILTER

CONVERTER INVERTERTRANSFORMER

C I450KVA Power Stage

CONTACTOR

bull Latest in Power Semiconductor Technology Modular Design

bull Utilizes IGBTrsquos (Insulated Gate Bi‐Polar Transistors) Converter and Inverter Components

Ozone Water Treatment

B bbl Diff iB bbl Diff iBubble DiffusionBubble Diffusion

Easy to use

Low energy usage Low energy usage

Mass transfer efficiencies to gt 90

Ozone Process Flow DiagramOzone Process Flow DiagramVent to

Atmosphere

O OOxygen

Off-Gas Blower

Ozone Destruct Unit

10 12

O3O2

LOX

10-12 O3

Ozone Generators

Ozone Contact ChamberLOX T k Generators Chamber

VaporizersLOX Tank

Municipal Ozone Installations

Ozonia Installations Ozone Plant Size [lbday] Start-Up DateKey Ozonia Installations (Partial List)

Los Angeles CA 10000 1986Fairfax VA ndash Corbalis 9000 2003MWD CA ndash Mills 9 000 2003

Ozonia Installations Ozone Plant Size [lbday] Start Up Date

MWD CA Mills 9000 2003Fairfax Co VA ndash Griffith 9000 2004MWD CA ndash Jensen 18750 2005Indianapolis IN ndash Belmont AWT 12000 2007I di li IN 12 000 2007Indianapolis IN ndash Southport AWT 12000 2007MWD CA ndash Diemer 13400 2008MWD CA ndash Weymouth 13400 2009

Ozonia North America - Potable Water SummaryTotal Number of Installations 90Total Installed Production gt 265000 lbsdayTotal Installed Production 265000 lbsday

Revision -B

Ozone Water TreatmentOzone Water Treatment

MWD Mills WTP - California

3 3 000 lbsda of o one3 3 000 lbsda of o one3 x 3000 lbsday of ozone3 x 3000 lbsday of ozone

Ozone Water TreatmentOzone Water TreatmentOzone Ozone -- How it worksHow it works

OxidantOxidant DisinfectantDisinfectant

bullbull Breaks double carbon Breaks double carbon bondsbonds

bullbull Kills by cell lysing or Kills by cell lysing or causing the cell wall tocausing the cell wall tobondsbonds

bullbull Creates OHCreates OHbullbull radicals radicals which break higher carbon which break higher carbon

causing the cell wall to causing the cell wall to rupture rupture

bullbull AttacksAttacks allall bacteriabacteriabondsbondsbullbull Increased temp and pH Increased temp and pH

accelerates Oaccelerates O33

Attacks Attacks allall bacteria bacteria virus cysts and spores virus cysts and spores in varying degreesin varying degreesaccelerates Oaccelerates O33

decomposition to OHdecomposition to OHbullbull

Micro-organism DNA

Capsule AdenineAdenine

Cell wall ThymineThymine

CytosineCytosine

GuanineGuanine

NuclearmaterialCellmembrane

material

Typical Bacterium DNA

Microbial Growth at Various Ozone ConcentrationsConcentrations

Growth likely

Growth possibleGrowth possible

NO GROWTH

0004 0008 0012 0016 0020

Ozone concentration (mgl)Ozone concentration (mgl)

Typical Water Treatment UsageTypical Water Treatment Usage

Application O3 mgl Contact timeUltra Pure Water 005 - 025 sec ndash min

Water bottling 04 ndash 10 5 ndash 10 min

Swimming pools ampspas

01 ndash 075 4 minutes

Potable taste amp odor 15 ndash 50 5 ndash 10 mindisinfection

Microfloculation 10 ndash 30 5 ndash 10 min

Lignin amp tammin 3 0 10 0 10 30 minLignin amp tamminremoval

30 ndash 100 10 ndash 30 min

Municipal wastewater 50 ndash 150+ 15 ndash 30 min

Ozone Water TreatmentOzone Water TreatmentOzone Ozone ndashndash Municipal ApplicationsMunicipal Applications

bullbull Taste and OdorTaste and Odor

bullbull Color RemovalColor Removal

bullbull Disinfection Without Trihalomethanes (THMs)Disinfection Without Trihalomethanes (THMs)

bullbull Improved Filtration Efficiency and FlocculationImproved Filtration Efficiency and Flocculation

bullbull Cryptosporidium DeactivationCryptosporidium Deactivation

bullbull Giardia amp Virus InactivationGiardia amp Virus Inactivation

bullbull Oxidation Oxidation -- Organics Fe amp MnOrganics Fe amp Mn

bullbull Wastewater disinfectionWastewater disinfection

bullbull BOD COD and TOC reductionBOD COD and TOC reduction

Applications of Ozone

Wastewater Treatmentbull Disinfection of Secondary and Tertiary Effluentsbull Color Reductionbull Color Reductionbull TOC Oxidation (Industrial)bull Oxidation of Odor Causing Compoundsbull Oxidation of Endocrine Disruptors (EDCrsquos) and p ( )

Pharmaceutically Active Compounds (PACrsquos)

Applications of Ozone

What are Endocrine Disruptors (EDCrsquos) and What are Endocrine Disruptors (EDCrsquos) and Ph ti ll A ti C d (PACrsquo )Ph ti ll A ti C d (PACrsquo )Pharmaceutically Active Compounds (PACrsquos)Pharmaceutically Active Compounds (PACrsquos)

bullbull EDCrsquosEDCrsquos andand PACrsquosPACrsquos areare NaturallyNaturally andand SyntheticSyntheticdd th tth t ff tff t thth b lb l llcompoundscompounds thatthat maymay affectaffect thethe balancebalance oror normalnormal

functionsfunctions inin animalsanimals andand humanshumans

What can EDCrsquos and PACrsquos doWhat can EDCrsquos and PACrsquos do

bullbull Even in very small concentrations these compounds Even in very small concentrations these compounds y py pcan can disruptdisrupt normal bodily functionsnormal bodily functions

bullbull ManMan--made chemicals can trick the bodies endocrine made chemicals can trick the bodies endocrine system system

Applications of Ozone

Examples of Endocrine Disruptors1000rsquos of compounds that may be Investigated as EDCs ndash Some examples are

bullbull Synthetic HormonesSynthetic Hormonesbullbull Naturally Occurring Estrogens Naturally Occurring Estrogens

Health and Beauty AidsHealth and Beauty Aidsbullbull Health and Beauty AidsHealth and Beauty Aidsbullbull SolventsSolventsbullbull PesticidesPesticidesbullbull SurfactantsSurfactantsbullbull PlasticsPlastics

F i idF i idbullbull FungicidesFungicides

Ozone Water TreatmentOzone Water Treatment

Ozone Ozone -- Industrial ApplicationsIndustrial Applications-- Ultrapure Water for Pharmaceutical ApplicationsUltrapure Water for Pharmaceutical Applications

-- Wastewater disinfection color removalWastewater disinfection color removal

-- Soil and Groundwater Remediation Soil and Groundwater Remediation

-- Cooling Tower Water TreatmentCooling Tower Water Treatment

-- Food ProcessingFood Processing

-- Aquaculture AquariumsAquaculture AquariumsAquaculture AquariumsAquaculture Aquariums

-- Beverage ApplicationsBeverage Applications

P l amp P Bl hiP l amp P Bl hi-- Pulp amp Paper BleachingPulp amp Paper Bleaching

High Purity OzonationHigh Purity Ozonation

Microchip manufacturingMicrochip manufacturing

What are the current issues in large-scale gozone generationg

Experimental Setup

Front view of the two units after the redesign and reworking ofthe gas water and instruments connectionsthe gas water and instruments connections

Experimental Setup

Top view of the twoexperimental unitsexperimental unitsSpectroscope (notshown) is to the left ofthe DBD The units weredifferent with respect todifferent with respect totheir electrodes onehad only the electrodecoated with thedielectric (ldquosingle-dielectric ( single-coatedrdquo) the other onehad the electrode andthe anode coated withthe dielectric (ldquodouble-the dielectric ( double-coatedrdquo)

Basics Generation of OzoneBasics Generation of Ozone

SpectroscopyPlasma

Plasma Absorption SpectroscopyPlasma Absorption Spectroscopy

Infrared Absorption SpectroscopyInfrared Absorption Spectroscopy

IR spectra in pure oxygen (black curve) and at approximately 10wt N2 admixture (red line) N2O5 peaks appear at124 1 d 1 2 11245 cm-1 and at 1725 cm-1

Infrared Absorption SpectroscopyInfrared Absorption Spectroscopy

IR spectra of several methane variations The green curve envelopes all of the methane peaks at 1325 cm-1recorded at smaller methane admixtures Simultaneously the N2O5 peaks disappear as the methane peaks appear

N2O5 FormationN2O5 Formation2 52 5p=2 bara cwt=20degC q=35kWm2 f=1450Hz

45N2O5 AT95

30

35

40

N

2 B

lend

ing

N2O AT95N2O5 IGSN2O IGSN2O5 LGN2O LG

1 5

20

25

nt [p

pmV]

3

wt

05

10

15

NO

x co

nten

005 7 9 11 13 15 17

ozone conc [wt]

Amount of formed N2O5 and N2O as a function of ozone concentration at 3 wt of nitrogen admixture and fori l dvarious electrode arrangements

Plasma Emission SpectroscopyPlasma Emission Spectroscopyp pyp py

Relative Emissions of the Ozonizer plasmaRelative Emissions of the Ozonizer plasma

Region 300- 850 nm from individual (calibrated) regions (smoothed by PeakFit) Single-coated ozone generator Inlet side

3 5E+06

30E+06

35E+06

7 9

20E+06

25E+06

nten

sity

au

2

311 12

10E+06

15E+06

In 4

5

6 8 10

14

15

16

17

00E+00

50E+05

280 300 320 340 360 380 400 420 440 460 480 500 520 540 560 580 600 620 640 660 680 700 720 740 760 780 800 820 840 860

Wavelength nm

1 13

Wavelength nm

Absolute Emission of the DBD PlasmaAbsolute Emission of the DBD Plasma

Intensities in (O2+3 wtN2) plasma

1 20E+04

100E+04

120E+04

600E+03

800E+03

nten

sity

(au

)

200E+03

400E+03

In

O(777)

000E+00200 250 300 350 400 450 500 550 600 650 700 750 800 850

Wavelength nm

Intensities in 3 wtN2+O2 plasmaIntensities in 3 wtN2+O2 plasma

Plasma Chemistry in OzonizersPlasma Chemistry in Ozonizers

Dry Air O2 N2

e - e -

O N2 N O2

O3 NO

O2 N O2

O3

N

3

NO2

O2 O3

NO

N

NO2 O3

N2O

NO3 N

N2O4

NO2

NO2

N2O5

NO3

Primary electron-driven chemical reactions leading to the formation of N2O5 and N2O in a dry air plasma

Plasma emission diagnostics role of N2Plasma emission diagnostics role of N2

Dry Air O2 N2

e - e -

O N2 N O2

O3 NO

O2 N O2

O3

O

N

ON

NO2

O2O3

N

NO N

NO2 O3

N2O

NO3 N

N2O4

NO2

NO2

N2O5

NO3

ONbullWith N2 present ndash less oxygen atoms are formed However the difference in intensity is

very small

Modeling of plasma chemistry incl the NxOy chemistry up to N2O5 for different Oxygen Nitrogen mixtures varying power deposition scenarios

and initial ozone background concentrations (up to 15) previously done

The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation

The role of N2 must be related to its by-products reacting on the surface of the electrodeThe role of N2 must be related to its by-products reacting on the surface of the electrode

The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established

Ab 8 t f O

The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established

Ab 8 t f OAbove 8 wt of O3

1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)

Above 8 wt of O3

1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)case without pampp)

2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of the

case without pampp)

2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of thethem A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface

them A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface

The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation

Three possibilities have to be considered for the oxygen-fedozone generator

Three possibilities have to be considered for the oxygen-fedozone generatorozone generator

bull Excited N2 molecules lead to an increased O2 dissociation in

ozone generator

bull Excited N2 molecules lead to an increased O2 dissociation in2 2such case an increased efficiency is correlated to the N2admixture

2 2such case an increased efficiency is correlated to the N2admixture

bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial

bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial

bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2

bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2g p g 3 pp y 2g p g 3 pp y 2

Effect of methane on ozone efficiency and specific powerEffect of methane on ozone efficiency and specific power

Effect of Methane on Ozone Content in Outlet Gas and on Specific Power Pure O2

13 12

10

11

12

t 8

10

8

9

10

ne c

onte

nt w

t

6

8

ecifi

c po

wer

kW

hlb

5

6

7

Ozo

n

2

4 Spe

400E+00 20E+03 40E+03 60E+03 80E+03 10E+04 12E+04

Methane in feedgas ppm

0

Ozone content in the outlet gas Specif ic pow er of the ozone generatorg p p g

Effects of N2 and CH4Effects of N2 and CH4

Pi t f h t lli N O t tPicture of an amorphous-crystalline N2O5 structurecaptured at the Orlando Skylake water plant in 2006

Plasma Chemistry with CH4 Impurities

OxygenO2 N2

e - e -

CHO N2

NO2

O NO

O2 N O2 O3

NOH

CH4e-

O3 NO

NO2

O2O3NO N

NO2 O

NO2

NO2

N2ONO3

N

O3

NO2

NO

HNO3

N2O4

N2O5

NO2

NO3

N2O5

Effect of methane on the electrode surfaces

a) b)

Inlet Outlet Outlet

) d)

I l t I l t

c) d)

Electrode of the ozone generator afterseveral hours in CH8O2 and up to 2 wt of methane (a b c)

Inlet Inlet

three hours in CH8O2+traces of N2 and up to 1 wt of methane (d) Visible change of discharge character at about 13 length of electrode (a d)

Kinetics of CHx Conversion without N2

conversion by collisions

O2 + CHx 12wt O3 + CO2 +H2O

deposition vaporizationby sputtering

ibl b l 1000 CHreversible process below 1000ppm CH4

Effect of water on electrode surface with N2

Inlet

OutletOutlet

Electrode of the ozone generator after several hours in H OO N

Inlet

Electrode of the ozone generator after several hours in H2OO2N2

Effect of water on electrode surface

Long term effect (800 hrs) of H2OO2N2

Kinetics of CHx Conversion with N2

conversion by collisionsHNO3 formation

O2 + N2 +CHx 12wtO2 + CO2 +H2O + HNO3

deposition vaporizationby sputtering

H2O + HNO3

by sputtering

irreversible process above a N2 threshold () ltlt 1000ppm N2

sticky deposit

p 2 ( ) pp 2 any CH4 concentration (60ppm)

Plasma Chemistry with CH4 ImpuritiesPlasma Chemistry with CH4 Impurities4

bull Formation of NO and NO2 depends on O3 N2 and gas temperature Conclusion N2 admixture is the key factor

SummarySummaryyyThe mechanisms of formed NOx by-products follows the sameThe mechanisms of formed NOx by-products follows the sameprinciples as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentration

principles as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentrationozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)

ozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)g p ( g p )

The conversion of methane to OH and H2O is found to depend on

g p ( g p )

The conversion of methane to OH and H2O is found to depend ondissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)

dissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)discharge gap)discharge gap)

How do you optimize an ozone generatorg

Scientific ApproachScientific ApproachTheoretical Experimental

pppp

c [wt]

f [Hz]

c [wt]

f [Hz]

[kW]UUUβ1

1Cf4αPn

1iiminpeakimin

iiD

q [kWm2]q [kWm2]

150

180

][V]voltagepeakUpeak

[]cylinder perslicesofamountnsliceii

whereth

09 00

30

60

90

120

effic

ienc

y [

][0tdj t bl[F]sliceisdielectricofecapacitancC

[Hz]frequencyf[V]sliceivoltageminimumiUmin

thiD

th

10

28

46

64

82

39

107

176

244 power density

[kWm2]

ozone conc [wt][]CCβ

][0parameteradjustableα

iDiGi

Impact of Power Inductionp

350

400

wer

200

250

300

App

lied

Pow

Arr C 2Arr D +0

Arr E +45Arr F +7

Arr G +3

5 0

100

150

Frac

tion

of

1 2 3 4

ReferenceArr B unstable

Arr C -2

00

50

4Position (1inlet 4outlet)

Experimental Test Rigp g

Experimental Test Rigp g

Outer grounded electrode (left picture) and the dielectric covered inner electrodes (right) d e ect c cove ed e e ect odes ( g t)

Reference (Traditional) Arrangement

Inlet OutletGas flow direction

Optimized Arrangement

Inlet OutletGas flow direction

Intelligent Gap System (IGS)g p y ( )

Molecular Oxygen (O2) Ozone (O3)

O2 O3

yg ( 2) ( 3)

Particle Size SynthesisParticle Size SynthesisByBy--Products Cluster FormationProducts Cluster Formationyy

high diffusion and deposition to surfaces

low diffusion rate good transport

high sedimentation on the structurehigh sedimentation on the structure

Degreacutemont Technologies ndash OzoniaIntelligent Gap SystemIntelligent Gap System

G Vezzuacute JL Lopez A Freilich and K Becker Optimizationof Large-Scale Ozone Generators IEEE Transactions onPlasma Science Vol 37 No 6 p 890-896 (2009)

ConclusionsConclusionsConclusionsConclusionsFundamentals of ozone synthesis in a DBD plasmay p

ndash Highly filamented DBD discharges are best-suitedfor the production of ozone concentrations in therange of 6 to 14 wtrange of 6 to 14 wt

ndash The preferred characteristic of the microdischargesare Townsend-like at reduced electric fields Enaround 190 Townsend

ndash Detrimental side-effects induced by by-productscan be avoided by a proper design of the electrodecan be avoided by a proper design of the electrodearrangement The phenomenon is related to thediffusion rates of formed by-product clusters

ConclusionsConclusionsConclusionsConclusionsBenefits from DBD microplasma tailoring

ndash Reduced power consumption of up to 10 improvement

ndash Increased ozone concentrations of up to 14 now achievable

ndash Improved neutralization and conditioning of detrimental by-products

ndash Reduced system capital and operational cost

New technologies to improve ozone p

generatorg

HV Pulsed Power SwitchingHV Pulsed Power Switching

Microchannel Generation of Ozone

Channel ArrayChannel Array

Microchannel

330 microm 230 microm

Some Cap-DBD Devices Operating in Air

Increase of 60 of

Spacing 225 μmof 60 of plasma

No space

Cap‐DBD ozone generation

bull Ozone concentration is evaluated via Eco S d l UV 100 O A l (0 01Sensors model UV-100 Ozone Analyzer (001 ndash 900 ppm wiht an accuracy of plusmn2)

bull Three reactors 6 tubings 6rdquo with spacings of 0 μm 225 μm and 500 μm running at 3 kV μ μ μ g

SpacingOzone Concentration

3 kV rms 4 kV rms3 kV rms 4 kV rms

0 μm 660 ppm

225 μm 550 ppm

For a device of such small scale these ozone levels are promising

500 μm 380 ppm

J Mahoney W Zhu VS Johnson KH Becker and JL Lopez Electrical and optical emissionmeasurements of a capillary dielectric barrier discharge European Physics Journal D Vol 60 441-447(2010)

QuestionsQuestions

Thank YouFor more informationProf Jose L Lopez PhD

Thank YouFor more informationDepartment of Physics

Telephone (973) 761-9057Email joselopez1shuedu

Website wwwshueduacademicsartsciphysicsWebsite wwwshueduacademicsartsciphysics

Page 12: Dielectric Barrier Discharge (DBD) & Progress in Large ...bonitz/si12/talks/august_8/lopez_si12.pdf · Dielectric Barrier Discharge (DBD) & Progress in Large-Scale Ozone Generation

LowLow--Pressure Glow Discharge PlasmasPressure Glow Discharge Plasmas

Plasmas are easier to be generated at low pressures

Low pressure plasmas (1 T f T )

at low pressures

are well understood

are used extensively nowadays

(1 mTorr ~ a few Torr)

are used extensively nowadays (eg in semiconductor industry for computer chips manufacturing)

However to generate low pressure plasmas

vacuum chambers + + = expensive vacuum pumps

pressure monitoring and pressure control devices

+ + =Generate Plasmas at Atmospheric PressureGenerate Plasmas at Atmospheric Pressure

What happens at air pressureWhat happens at air pressure

bull No vacuum is involvedDiffi l d ibull Difficult to generate and sustain

bull Run into some challenges such as glow toarc transition ndash Non controllable

Arc Discharge thermal plasma-Itrsquos hot and detrimental-Gas temperature can reach as high as 2x104 KGas temperature can reach as high as 2x10 K- Low voltage drop at cathode- High cathode current density

High Pressure Microplasmas

Stabilization of high-pressure plasmas ldquopd scalingrdquo ldquoprdquo uarr soplasmas pd scaling p uarr so ldquodrdquo darr to keep breakdown voltage low and minimize instabilities after breakdown -

MicroplasmasDimension a few millimeterDimension a few millimeter down to and below 100 m

Paschen Breakdown CurveH H i 60 100Human Hair 60 ndash 100 m

How do we solve this problemHow do we solve this problem

Transient (pulsed) plasmas In atmospheric plasmas for efficient gas heating atleast 100-1000 collisions are necessary Thus if the plasma duration is shorterleast 100 1000 collisions are necessary Thus if the plasma duration is shorterthan 10-6 ndash 10-5 s gas heating is limited Of course for practical purposes suchplasma has to be operated in a repetitive mode eg in trains of microsecondpulses with millisecond intervals

Micro-confinement Gas heating occurs in the plasma volume and the energy iscarried away by thermal diffusionconvection to the outside If the plasma has asmall volume and a relatively large surface gas heating is limited

Dielectric Barrier Discharges These plasmas are typically created betweenmetal plates which are covered by a thin layer of dielectric or highly resistivematerial The dielectric layer plays an important role in suppressing the currentthe cathodeanode layer is charged by incoming positive ionselectrons whichreduces the electric field and hinders charge transport towards the electrodeDBD also has a large surface-to-volume ratio which promotes diffusion lossesand maintains a low gas temperatureand maintains a low gas temperature

Advantages of Microplasmas Advantages of Microplasmas

bull Low-cost of implementationpbull System flexibilitybull Atmospheric pressure operationbull High densities and high reaction ratesbull High densities and high reaction ratesbull Fast and efficient processesbull Easy to generate and sustain for a variety of gas mixtures

Gl lik d diffbull Glow-like and diffusebull Non-equilibrium (Te gt Tg) to thermalbull Unique chemistryq y

hellip a new realm of plasma sciencehellip a new realm of plasma science

What can we do with microplasmasWhat can we do with microplasmas

Material Synthesis Plasma display Surface Treatment Lighting

OzoneOzone generation for water cleaning

Bio-applicationMaterial processing Dental application

and Many morehellip

Some High Pressure microplasma reactors Some High Pressure microplasma reactors

Dielectric Barrier Discharge (DBD)Dielectric Barrier Discharge (DBD)

Hi h V l

HighVoltage

High VoltageElectrode

ACGenerator

DielectricBarrier

Generator

G

Microplasmas

GroundElectrode

Faradayrsquos Dielectric CapacitorsFaradayrsquos Dielectric Capacitors

Faradays Dielectric Capacitor (circa 1837)

Michael Faraday (1781 ndash 1867) Capacitance INCREASED

Historical Ozone Tube of W Siemens (1857)Historical Ozone Tube of W Siemens (1857)

Werner v SiemensP d frsquo A l d Ch i d Ph ik 102 66 (1857)Poggendorfrsquos Annalen der Chemie und Physik 102 66 (1857)

ldquoOzone Production in an Atmospheric-PressureDielectric Barrier Dischargerdquo

Dielectric Barrier Discharge

Dielectric Barrier DischargeDielectric - Barrier Discharge ConfigurationsHigh

VoltageAC

Generator

High VoltageElectrode

DielectricBarrier

DielectricBarrier

High VoltageElectrode

Discharge

DischargeGeneratorGround

Electrode

Electrode

GroundElectrode

Discharge

H E Wagner R Brandenburg et al lsquoThe barrier discharge basic properties and applications toHE Wagner R Brandenburg et al The barrier discharge basic properties and applications tosurface treatmentrsquo Vacuum 71 p417-436 (2003)

Typical operational conditions of barrier discharges Typical operational conditions of barrier discharges

Electric field strength E of first breakdown asymp150 Td (p = 1bar T=300 K)

Voltage Vpp 3ndash20 kV

Repetition frequency f 50 Hzndash30 kHz

Pressure p 1ndash3 bar

Gap distance g 02ndash5mm

Dielectric material thickness d 05ndash2mm

Relative dielectric permittivity r 5ndash10 (glass)

B Eliasson and U Kogelschatz IEEE Transactions Plasma Science Vol 19 Issue 6 1063-1077 (1991)B Eliasson and U Kogelschatz IEEE Transactions Plasma Science Vol 19 Issue 6 1063-1077 (1991)

Single and double DBD

Single dielectric Double dielectric

Role of the Dielectric (Insulator)

Th di l t i i th k f thThe dielectric is the key for the properfunctioning of the discharge

Serves two functions

1 Limits the amount of charge transportedby a single microplasma

2 Distributes the microplasmas over theentire electrode surface area

Equivalent Circuit of a Microdischarge

Microdischarge Activity and U-Q Lissajous Figure

B Eliasson and U Kogelschatz IEEE Transactions Plasma Science Vol 19 Issue 6 1063-1077 (1991)

Fundamental Operation of the Dielectric Barrier DischargeFundamental Operation of the Dielectric Barrier Discharge

bull Many of relevant plasma processes that areof importance to achieving our goal occuron time scales that allow us to study themon time scales that allow us to study them

bull Optical emission spectroscopic studies willallow us to determine the temporal andspatial development of important plasmaspatial development of important plasmaspecies such as radicals (OH NO variousoxygen radicals) with high time resolution(less than 10 ns) and a spatial resolution onthe scale of mm in the plasma volumepfollowing pulsed plasma excitation

Time scale of the relevant processes of the DBD

HE Wagner R Brandenburg et al lsquoThe barrier discharge basic properties and applications tosurface treatmentrsquo Vacuum 71 417-436 (2003)

Fundamental Operation of the DBDFundamental Operation of the DBD

Electron DensityTemporal Development (ns)

y

Outer Contour Linen = 1010 cm-3ne = 1010 cm 3

Inner Contour Linene = 1014 cm-3

Streamer Propagation in 1 bar AirAA Kulikovsky IEEE Trans Plasma Sci 25 439-446 (1997)

Numerical Results of Microdischarge Formationin Dielectric Barrier Discharges

Starting Phase of a Microdischarge (1 bar 20 CO2 80 H2)

E0=34 kVcm1010 cm-3

1010 cm-3 ne=1012 cm-3

1mm10 cm

ne=108 cm-3

An electron avalanche propagates towards the anode

Reverse propagationtowards the cathodepropagates towards the anode towards the cathode

Numerical Results of Microdischarge Formationin Dielectric Barrier Discharges

Cathode Layer Formation

E0=34 kVcm1010 cm-39 3 0

1mm

1010 cm-3

10 cmne=109 cm-31014

10131014

1013

10 cm1012

Just before the peak of the total current

Peak currentof the total current

Numerical Results of Microdischarge Formationin Dielectric Barrier Discharges

Local Field Collapse in Area Defined by Surface Discharge

ne=109cm-3 ne=1014 cm-3

Gap

Principals of DBD MicroplasmasPrincipals of DBD MicroplasmasPrincipals of DBD MicroplasmasPrincipals of DBD Microplasmas

C C-- - --- - - CG

CD

-- - - CG

CD

Principals of DBD MicroplasmasPrincipals of DBD MicroplasmasPrincipals of DBD MicroplasmasPrincipals of DBD Microplasmas

Dielectric Barrier Discharge (DBD)Dielectric Barrier Discharge (DBD)Electric Field

B kdBreakdown

Electrons amp Ions Discharge Physics

Excited SpeciesPlasma Chemistry

Chemical Reactions

OzoneGeneration

SurfaceTreatment

PollutionControl

ExcimerFormation CO2 Lasers Hydrogenation

of CO2

Excimer Lamps Plasma Displays

How A Plasma Display Works

How A Plasma Display Work

Plasma Display TelevisionsPlasma Display Televisions

Ozone Generator

3 O 2 O

Dielectric Barrier Discharge

3 O2 2 O3

OO22 OO33++OO22Ondash ndashO3O2

O2O2

Ondash ndash

endash O2Ondash ndash O2endash

O3

O3O2O2 O2

HeatHeatHeatHeat

Properties of Ozone (O3)

T i t i f f Tri-atomic form of oxygen

Most powerful commercial oxidizing agent

Unstable - must be generated and used onsite

Limited solubility in water but more so than oxygenLimited solubility in water but more so than oxygen

Leaves a dissolved residual which ultimately converts back to oxygenconverts back to oxygen

Discharge Tubes in Ozone GeneratorsDischarge Tubes in Ozone Generators

Traditional

Ozone Generator

with Glass Tubes

Generation of OzoneGeneration of Ozone

Generation of OzoneAdvantages of Enamel Dielectrics

Proven Patented Designbull Simplicity

Si l Di l i Cbull Single Dielectric Componentndash Reduced number of Dielectrics

bull Safety ndash Lower operating voltage

(lt 4000 V)bull Reliabilty

ndash Fused Dielectrics ensure continuous production

bull Lowest Power Consumption Operational Savingsndash Operational Savings

Modern Ozone GeneratorModern Ozone Generator

Ozonia Advanced Technology Ozone GeneratorOzone Generator

Generation of OzoneGeneration of Ozone

Generation of Ozone

Power Supply UnitPower Supply Unit

IGBT Inverter CircuitMain Circuit Breaker

HV 480 Volts60 Hz3 Phase Supply

C I

450KVAPow er to

GeneratorFILTER

CONVERTER INVERTERTRANSFORMER

C I450KVA Power Stage

CONTACTOR

bull Latest in Power Semiconductor Technology Modular Design

bull Utilizes IGBTrsquos (Insulated Gate Bi‐Polar Transistors) Converter and Inverter Components

Ozone Water Treatment

B bbl Diff iB bbl Diff iBubble DiffusionBubble Diffusion

Easy to use

Low energy usage Low energy usage

Mass transfer efficiencies to gt 90

Ozone Process Flow DiagramOzone Process Flow DiagramVent to

Atmosphere

O OOxygen

Off-Gas Blower

Ozone Destruct Unit

10 12

O3O2

LOX

10-12 O3

Ozone Generators

Ozone Contact ChamberLOX T k Generators Chamber

VaporizersLOX Tank

Municipal Ozone Installations

Ozonia Installations Ozone Plant Size [lbday] Start-Up DateKey Ozonia Installations (Partial List)

Los Angeles CA 10000 1986Fairfax VA ndash Corbalis 9000 2003MWD CA ndash Mills 9 000 2003

Ozonia Installations Ozone Plant Size [lbday] Start Up Date

MWD CA Mills 9000 2003Fairfax Co VA ndash Griffith 9000 2004MWD CA ndash Jensen 18750 2005Indianapolis IN ndash Belmont AWT 12000 2007I di li IN 12 000 2007Indianapolis IN ndash Southport AWT 12000 2007MWD CA ndash Diemer 13400 2008MWD CA ndash Weymouth 13400 2009

Ozonia North America - Potable Water SummaryTotal Number of Installations 90Total Installed Production gt 265000 lbsdayTotal Installed Production 265000 lbsday

Revision -B

Ozone Water TreatmentOzone Water Treatment

MWD Mills WTP - California

3 3 000 lbsda of o one3 3 000 lbsda of o one3 x 3000 lbsday of ozone3 x 3000 lbsday of ozone

Ozone Water TreatmentOzone Water TreatmentOzone Ozone -- How it worksHow it works

OxidantOxidant DisinfectantDisinfectant

bullbull Breaks double carbon Breaks double carbon bondsbonds

bullbull Kills by cell lysing or Kills by cell lysing or causing the cell wall tocausing the cell wall tobondsbonds

bullbull Creates OHCreates OHbullbull radicals radicals which break higher carbon which break higher carbon

causing the cell wall to causing the cell wall to rupture rupture

bullbull AttacksAttacks allall bacteriabacteriabondsbondsbullbull Increased temp and pH Increased temp and pH

accelerates Oaccelerates O33

Attacks Attacks allall bacteria bacteria virus cysts and spores virus cysts and spores in varying degreesin varying degreesaccelerates Oaccelerates O33

decomposition to OHdecomposition to OHbullbull

Micro-organism DNA

Capsule AdenineAdenine

Cell wall ThymineThymine

CytosineCytosine

GuanineGuanine

NuclearmaterialCellmembrane

material

Typical Bacterium DNA

Microbial Growth at Various Ozone ConcentrationsConcentrations

Growth likely

Growth possibleGrowth possible

NO GROWTH

0004 0008 0012 0016 0020

Ozone concentration (mgl)Ozone concentration (mgl)

Typical Water Treatment UsageTypical Water Treatment Usage

Application O3 mgl Contact timeUltra Pure Water 005 - 025 sec ndash min

Water bottling 04 ndash 10 5 ndash 10 min

Swimming pools ampspas

01 ndash 075 4 minutes

Potable taste amp odor 15 ndash 50 5 ndash 10 mindisinfection

Microfloculation 10 ndash 30 5 ndash 10 min

Lignin amp tammin 3 0 10 0 10 30 minLignin amp tamminremoval

30 ndash 100 10 ndash 30 min

Municipal wastewater 50 ndash 150+ 15 ndash 30 min

Ozone Water TreatmentOzone Water TreatmentOzone Ozone ndashndash Municipal ApplicationsMunicipal Applications

bullbull Taste and OdorTaste and Odor

bullbull Color RemovalColor Removal

bullbull Disinfection Without Trihalomethanes (THMs)Disinfection Without Trihalomethanes (THMs)

bullbull Improved Filtration Efficiency and FlocculationImproved Filtration Efficiency and Flocculation

bullbull Cryptosporidium DeactivationCryptosporidium Deactivation

bullbull Giardia amp Virus InactivationGiardia amp Virus Inactivation

bullbull Oxidation Oxidation -- Organics Fe amp MnOrganics Fe amp Mn

bullbull Wastewater disinfectionWastewater disinfection

bullbull BOD COD and TOC reductionBOD COD and TOC reduction

Applications of Ozone

Wastewater Treatmentbull Disinfection of Secondary and Tertiary Effluentsbull Color Reductionbull Color Reductionbull TOC Oxidation (Industrial)bull Oxidation of Odor Causing Compoundsbull Oxidation of Endocrine Disruptors (EDCrsquos) and p ( )

Pharmaceutically Active Compounds (PACrsquos)

Applications of Ozone

What are Endocrine Disruptors (EDCrsquos) and What are Endocrine Disruptors (EDCrsquos) and Ph ti ll A ti C d (PACrsquo )Ph ti ll A ti C d (PACrsquo )Pharmaceutically Active Compounds (PACrsquos)Pharmaceutically Active Compounds (PACrsquos)

bullbull EDCrsquosEDCrsquos andand PACrsquosPACrsquos areare NaturallyNaturally andand SyntheticSyntheticdd th tth t ff tff t thth b lb l llcompoundscompounds thatthat maymay affectaffect thethe balancebalance oror normalnormal

functionsfunctions inin animalsanimals andand humanshumans

What can EDCrsquos and PACrsquos doWhat can EDCrsquos and PACrsquos do

bullbull Even in very small concentrations these compounds Even in very small concentrations these compounds y py pcan can disruptdisrupt normal bodily functionsnormal bodily functions

bullbull ManMan--made chemicals can trick the bodies endocrine made chemicals can trick the bodies endocrine system system

Applications of Ozone

Examples of Endocrine Disruptors1000rsquos of compounds that may be Investigated as EDCs ndash Some examples are

bullbull Synthetic HormonesSynthetic Hormonesbullbull Naturally Occurring Estrogens Naturally Occurring Estrogens

Health and Beauty AidsHealth and Beauty Aidsbullbull Health and Beauty AidsHealth and Beauty Aidsbullbull SolventsSolventsbullbull PesticidesPesticidesbullbull SurfactantsSurfactantsbullbull PlasticsPlastics

F i idF i idbullbull FungicidesFungicides

Ozone Water TreatmentOzone Water Treatment

Ozone Ozone -- Industrial ApplicationsIndustrial Applications-- Ultrapure Water for Pharmaceutical ApplicationsUltrapure Water for Pharmaceutical Applications

-- Wastewater disinfection color removalWastewater disinfection color removal

-- Soil and Groundwater Remediation Soil and Groundwater Remediation

-- Cooling Tower Water TreatmentCooling Tower Water Treatment

-- Food ProcessingFood Processing

-- Aquaculture AquariumsAquaculture AquariumsAquaculture AquariumsAquaculture Aquariums

-- Beverage ApplicationsBeverage Applications

P l amp P Bl hiP l amp P Bl hi-- Pulp amp Paper BleachingPulp amp Paper Bleaching

High Purity OzonationHigh Purity Ozonation

Microchip manufacturingMicrochip manufacturing

What are the current issues in large-scale gozone generationg

Experimental Setup

Front view of the two units after the redesign and reworking ofthe gas water and instruments connectionsthe gas water and instruments connections

Experimental Setup

Top view of the twoexperimental unitsexperimental unitsSpectroscope (notshown) is to the left ofthe DBD The units weredifferent with respect todifferent with respect totheir electrodes onehad only the electrodecoated with thedielectric (ldquosingle-dielectric ( single-coatedrdquo) the other onehad the electrode andthe anode coated withthe dielectric (ldquodouble-the dielectric ( double-coatedrdquo)

Basics Generation of OzoneBasics Generation of Ozone

SpectroscopyPlasma

Plasma Absorption SpectroscopyPlasma Absorption Spectroscopy

Infrared Absorption SpectroscopyInfrared Absorption Spectroscopy

IR spectra in pure oxygen (black curve) and at approximately 10wt N2 admixture (red line) N2O5 peaks appear at124 1 d 1 2 11245 cm-1 and at 1725 cm-1

Infrared Absorption SpectroscopyInfrared Absorption Spectroscopy

IR spectra of several methane variations The green curve envelopes all of the methane peaks at 1325 cm-1recorded at smaller methane admixtures Simultaneously the N2O5 peaks disappear as the methane peaks appear

N2O5 FormationN2O5 Formation2 52 5p=2 bara cwt=20degC q=35kWm2 f=1450Hz

45N2O5 AT95

30

35

40

N

2 B

lend

ing

N2O AT95N2O5 IGSN2O IGSN2O5 LGN2O LG

1 5

20

25

nt [p

pmV]

3

wt

05

10

15

NO

x co

nten

005 7 9 11 13 15 17

ozone conc [wt]

Amount of formed N2O5 and N2O as a function of ozone concentration at 3 wt of nitrogen admixture and fori l dvarious electrode arrangements

Plasma Emission SpectroscopyPlasma Emission Spectroscopyp pyp py

Relative Emissions of the Ozonizer plasmaRelative Emissions of the Ozonizer plasma

Region 300- 850 nm from individual (calibrated) regions (smoothed by PeakFit) Single-coated ozone generator Inlet side

3 5E+06

30E+06

35E+06

7 9

20E+06

25E+06

nten

sity

au

2

311 12

10E+06

15E+06

In 4

5

6 8 10

14

15

16

17

00E+00

50E+05

280 300 320 340 360 380 400 420 440 460 480 500 520 540 560 580 600 620 640 660 680 700 720 740 760 780 800 820 840 860

Wavelength nm

1 13

Wavelength nm

Absolute Emission of the DBD PlasmaAbsolute Emission of the DBD Plasma

Intensities in (O2+3 wtN2) plasma

1 20E+04

100E+04

120E+04

600E+03

800E+03

nten

sity

(au

)

200E+03

400E+03

In

O(777)

000E+00200 250 300 350 400 450 500 550 600 650 700 750 800 850

Wavelength nm

Intensities in 3 wtN2+O2 plasmaIntensities in 3 wtN2+O2 plasma

Plasma Chemistry in OzonizersPlasma Chemistry in Ozonizers

Dry Air O2 N2

e - e -

O N2 N O2

O3 NO

O2 N O2

O3

N

3

NO2

O2 O3

NO

N

NO2 O3

N2O

NO3 N

N2O4

NO2

NO2

N2O5

NO3

Primary electron-driven chemical reactions leading to the formation of N2O5 and N2O in a dry air plasma

Plasma emission diagnostics role of N2Plasma emission diagnostics role of N2

Dry Air O2 N2

e - e -

O N2 N O2

O3 NO

O2 N O2

O3

O

N

ON

NO2

O2O3

N

NO N

NO2 O3

N2O

NO3 N

N2O4

NO2

NO2

N2O5

NO3

ONbullWith N2 present ndash less oxygen atoms are formed However the difference in intensity is

very small

Modeling of plasma chemistry incl the NxOy chemistry up to N2O5 for different Oxygen Nitrogen mixtures varying power deposition scenarios

and initial ozone background concentrations (up to 15) previously done

The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation

The role of N2 must be related to its by-products reacting on the surface of the electrodeThe role of N2 must be related to its by-products reacting on the surface of the electrode

The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established

Ab 8 t f O

The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established

Ab 8 t f OAbove 8 wt of O3

1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)

Above 8 wt of O3

1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)case without pampp)

2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of the

case without pampp)

2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of thethem A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface

them A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface

The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation

Three possibilities have to be considered for the oxygen-fedozone generator

Three possibilities have to be considered for the oxygen-fedozone generatorozone generator

bull Excited N2 molecules lead to an increased O2 dissociation in

ozone generator

bull Excited N2 molecules lead to an increased O2 dissociation in2 2such case an increased efficiency is correlated to the N2admixture

2 2such case an increased efficiency is correlated to the N2admixture

bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial

bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial

bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2

bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2g p g 3 pp y 2g p g 3 pp y 2

Effect of methane on ozone efficiency and specific powerEffect of methane on ozone efficiency and specific power

Effect of Methane on Ozone Content in Outlet Gas and on Specific Power Pure O2

13 12

10

11

12

t 8

10

8

9

10

ne c

onte

nt w

t

6

8

ecifi

c po

wer

kW

hlb

5

6

7

Ozo

n

2

4 Spe

400E+00 20E+03 40E+03 60E+03 80E+03 10E+04 12E+04

Methane in feedgas ppm

0

Ozone content in the outlet gas Specif ic pow er of the ozone generatorg p p g

Effects of N2 and CH4Effects of N2 and CH4

Pi t f h t lli N O t tPicture of an amorphous-crystalline N2O5 structurecaptured at the Orlando Skylake water plant in 2006

Plasma Chemistry with CH4 Impurities

OxygenO2 N2

e - e -

CHO N2

NO2

O NO

O2 N O2 O3

NOH

CH4e-

O3 NO

NO2

O2O3NO N

NO2 O

NO2

NO2

N2ONO3

N

O3

NO2

NO

HNO3

N2O4

N2O5

NO2

NO3

N2O5

Effect of methane on the electrode surfaces

a) b)

Inlet Outlet Outlet

) d)

I l t I l t

c) d)

Electrode of the ozone generator afterseveral hours in CH8O2 and up to 2 wt of methane (a b c)

Inlet Inlet

three hours in CH8O2+traces of N2 and up to 1 wt of methane (d) Visible change of discharge character at about 13 length of electrode (a d)

Kinetics of CHx Conversion without N2

conversion by collisions

O2 + CHx 12wt O3 + CO2 +H2O

deposition vaporizationby sputtering

ibl b l 1000 CHreversible process below 1000ppm CH4

Effect of water on electrode surface with N2

Inlet

OutletOutlet

Electrode of the ozone generator after several hours in H OO N

Inlet

Electrode of the ozone generator after several hours in H2OO2N2

Effect of water on electrode surface

Long term effect (800 hrs) of H2OO2N2

Kinetics of CHx Conversion with N2

conversion by collisionsHNO3 formation

O2 + N2 +CHx 12wtO2 + CO2 +H2O + HNO3

deposition vaporizationby sputtering

H2O + HNO3

by sputtering

irreversible process above a N2 threshold () ltlt 1000ppm N2

sticky deposit

p 2 ( ) pp 2 any CH4 concentration (60ppm)

Plasma Chemistry with CH4 ImpuritiesPlasma Chemistry with CH4 Impurities4

bull Formation of NO and NO2 depends on O3 N2 and gas temperature Conclusion N2 admixture is the key factor

SummarySummaryyyThe mechanisms of formed NOx by-products follows the sameThe mechanisms of formed NOx by-products follows the sameprinciples as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentration

principles as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentrationozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)

ozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)g p ( g p )

The conversion of methane to OH and H2O is found to depend on

g p ( g p )

The conversion of methane to OH and H2O is found to depend ondissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)

dissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)discharge gap)discharge gap)

How do you optimize an ozone generatorg

Scientific ApproachScientific ApproachTheoretical Experimental

pppp

c [wt]

f [Hz]

c [wt]

f [Hz]

[kW]UUUβ1

1Cf4αPn

1iiminpeakimin

iiD

q [kWm2]q [kWm2]

150

180

][V]voltagepeakUpeak

[]cylinder perslicesofamountnsliceii

whereth

09 00

30

60

90

120

effic

ienc

y [

][0tdj t bl[F]sliceisdielectricofecapacitancC

[Hz]frequencyf[V]sliceivoltageminimumiUmin

thiD

th

10

28

46

64

82

39

107

176

244 power density

[kWm2]

ozone conc [wt][]CCβ

][0parameteradjustableα

iDiGi

Impact of Power Inductionp

350

400

wer

200

250

300

App

lied

Pow

Arr C 2Arr D +0

Arr E +45Arr F +7

Arr G +3

5 0

100

150

Frac

tion

of

1 2 3 4

ReferenceArr B unstable

Arr C -2

00

50

4Position (1inlet 4outlet)

Experimental Test Rigp g

Experimental Test Rigp g

Outer grounded electrode (left picture) and the dielectric covered inner electrodes (right) d e ect c cove ed e e ect odes ( g t)

Reference (Traditional) Arrangement

Inlet OutletGas flow direction

Optimized Arrangement

Inlet OutletGas flow direction

Intelligent Gap System (IGS)g p y ( )

Molecular Oxygen (O2) Ozone (O3)

O2 O3

yg ( 2) ( 3)

Particle Size SynthesisParticle Size SynthesisByBy--Products Cluster FormationProducts Cluster Formationyy

high diffusion and deposition to surfaces

low diffusion rate good transport

high sedimentation on the structurehigh sedimentation on the structure

Degreacutemont Technologies ndash OzoniaIntelligent Gap SystemIntelligent Gap System

G Vezzuacute JL Lopez A Freilich and K Becker Optimizationof Large-Scale Ozone Generators IEEE Transactions onPlasma Science Vol 37 No 6 p 890-896 (2009)

ConclusionsConclusionsConclusionsConclusionsFundamentals of ozone synthesis in a DBD plasmay p

ndash Highly filamented DBD discharges are best-suitedfor the production of ozone concentrations in therange of 6 to 14 wtrange of 6 to 14 wt

ndash The preferred characteristic of the microdischargesare Townsend-like at reduced electric fields Enaround 190 Townsend

ndash Detrimental side-effects induced by by-productscan be avoided by a proper design of the electrodecan be avoided by a proper design of the electrodearrangement The phenomenon is related to thediffusion rates of formed by-product clusters

ConclusionsConclusionsConclusionsConclusionsBenefits from DBD microplasma tailoring

ndash Reduced power consumption of up to 10 improvement

ndash Increased ozone concentrations of up to 14 now achievable

ndash Improved neutralization and conditioning of detrimental by-products

ndash Reduced system capital and operational cost

New technologies to improve ozone p

generatorg

HV Pulsed Power SwitchingHV Pulsed Power Switching

Microchannel Generation of Ozone

Channel ArrayChannel Array

Microchannel

330 microm 230 microm

Some Cap-DBD Devices Operating in Air

Increase of 60 of

Spacing 225 μmof 60 of plasma

No space

Cap‐DBD ozone generation

bull Ozone concentration is evaluated via Eco S d l UV 100 O A l (0 01Sensors model UV-100 Ozone Analyzer (001 ndash 900 ppm wiht an accuracy of plusmn2)

bull Three reactors 6 tubings 6rdquo with spacings of 0 μm 225 μm and 500 μm running at 3 kV μ μ μ g

SpacingOzone Concentration

3 kV rms 4 kV rms3 kV rms 4 kV rms

0 μm 660 ppm

225 μm 550 ppm

For a device of such small scale these ozone levels are promising

500 μm 380 ppm

J Mahoney W Zhu VS Johnson KH Becker and JL Lopez Electrical and optical emissionmeasurements of a capillary dielectric barrier discharge European Physics Journal D Vol 60 441-447(2010)

QuestionsQuestions

Thank YouFor more informationProf Jose L Lopez PhD

Thank YouFor more informationDepartment of Physics

Telephone (973) 761-9057Email joselopez1shuedu

Website wwwshueduacademicsartsciphysicsWebsite wwwshueduacademicsartsciphysics

Page 13: Dielectric Barrier Discharge (DBD) & Progress in Large ...bonitz/si12/talks/august_8/lopez_si12.pdf · Dielectric Barrier Discharge (DBD) & Progress in Large-Scale Ozone Generation

Plasmas are easier to be generated at low pressures

Low pressure plasmas (1 T f T )

at low pressures

are well understood

are used extensively nowadays

(1 mTorr ~ a few Torr)

are used extensively nowadays (eg in semiconductor industry for computer chips manufacturing)

However to generate low pressure plasmas

vacuum chambers + + = expensive vacuum pumps

pressure monitoring and pressure control devices

+ + =Generate Plasmas at Atmospheric PressureGenerate Plasmas at Atmospheric Pressure

What happens at air pressureWhat happens at air pressure

bull No vacuum is involvedDiffi l d ibull Difficult to generate and sustain

bull Run into some challenges such as glow toarc transition ndash Non controllable

Arc Discharge thermal plasma-Itrsquos hot and detrimental-Gas temperature can reach as high as 2x104 KGas temperature can reach as high as 2x10 K- Low voltage drop at cathode- High cathode current density

High Pressure Microplasmas

Stabilization of high-pressure plasmas ldquopd scalingrdquo ldquoprdquo uarr soplasmas pd scaling p uarr so ldquodrdquo darr to keep breakdown voltage low and minimize instabilities after breakdown -

MicroplasmasDimension a few millimeterDimension a few millimeter down to and below 100 m

Paschen Breakdown CurveH H i 60 100Human Hair 60 ndash 100 m

How do we solve this problemHow do we solve this problem

Transient (pulsed) plasmas In atmospheric plasmas for efficient gas heating atleast 100-1000 collisions are necessary Thus if the plasma duration is shorterleast 100 1000 collisions are necessary Thus if the plasma duration is shorterthan 10-6 ndash 10-5 s gas heating is limited Of course for practical purposes suchplasma has to be operated in a repetitive mode eg in trains of microsecondpulses with millisecond intervals

Micro-confinement Gas heating occurs in the plasma volume and the energy iscarried away by thermal diffusionconvection to the outside If the plasma has asmall volume and a relatively large surface gas heating is limited

Dielectric Barrier Discharges These plasmas are typically created betweenmetal plates which are covered by a thin layer of dielectric or highly resistivematerial The dielectric layer plays an important role in suppressing the currentthe cathodeanode layer is charged by incoming positive ionselectrons whichreduces the electric field and hinders charge transport towards the electrodeDBD also has a large surface-to-volume ratio which promotes diffusion lossesand maintains a low gas temperatureand maintains a low gas temperature

Advantages of Microplasmas Advantages of Microplasmas

bull Low-cost of implementationpbull System flexibilitybull Atmospheric pressure operationbull High densities and high reaction ratesbull High densities and high reaction ratesbull Fast and efficient processesbull Easy to generate and sustain for a variety of gas mixtures

Gl lik d diffbull Glow-like and diffusebull Non-equilibrium (Te gt Tg) to thermalbull Unique chemistryq y

hellip a new realm of plasma sciencehellip a new realm of plasma science

What can we do with microplasmasWhat can we do with microplasmas

Material Synthesis Plasma display Surface Treatment Lighting

OzoneOzone generation for water cleaning

Bio-applicationMaterial processing Dental application

and Many morehellip

Some High Pressure microplasma reactors Some High Pressure microplasma reactors

Dielectric Barrier Discharge (DBD)Dielectric Barrier Discharge (DBD)

Hi h V l

HighVoltage

High VoltageElectrode

ACGenerator

DielectricBarrier

Generator

G

Microplasmas

GroundElectrode

Faradayrsquos Dielectric CapacitorsFaradayrsquos Dielectric Capacitors

Faradays Dielectric Capacitor (circa 1837)

Michael Faraday (1781 ndash 1867) Capacitance INCREASED

Historical Ozone Tube of W Siemens (1857)Historical Ozone Tube of W Siemens (1857)

Werner v SiemensP d frsquo A l d Ch i d Ph ik 102 66 (1857)Poggendorfrsquos Annalen der Chemie und Physik 102 66 (1857)

ldquoOzone Production in an Atmospheric-PressureDielectric Barrier Dischargerdquo

Dielectric Barrier Discharge

Dielectric Barrier DischargeDielectric - Barrier Discharge ConfigurationsHigh

VoltageAC

Generator

High VoltageElectrode

DielectricBarrier

DielectricBarrier

High VoltageElectrode

Discharge

DischargeGeneratorGround

Electrode

Electrode

GroundElectrode

Discharge

H E Wagner R Brandenburg et al lsquoThe barrier discharge basic properties and applications toHE Wagner R Brandenburg et al The barrier discharge basic properties and applications tosurface treatmentrsquo Vacuum 71 p417-436 (2003)

Typical operational conditions of barrier discharges Typical operational conditions of barrier discharges

Electric field strength E of first breakdown asymp150 Td (p = 1bar T=300 K)

Voltage Vpp 3ndash20 kV

Repetition frequency f 50 Hzndash30 kHz

Pressure p 1ndash3 bar

Gap distance g 02ndash5mm

Dielectric material thickness d 05ndash2mm

Relative dielectric permittivity r 5ndash10 (glass)

B Eliasson and U Kogelschatz IEEE Transactions Plasma Science Vol 19 Issue 6 1063-1077 (1991)B Eliasson and U Kogelschatz IEEE Transactions Plasma Science Vol 19 Issue 6 1063-1077 (1991)

Single and double DBD

Single dielectric Double dielectric

Role of the Dielectric (Insulator)

Th di l t i i th k f thThe dielectric is the key for the properfunctioning of the discharge

Serves two functions

1 Limits the amount of charge transportedby a single microplasma

2 Distributes the microplasmas over theentire electrode surface area

Equivalent Circuit of a Microdischarge

Microdischarge Activity and U-Q Lissajous Figure

B Eliasson and U Kogelschatz IEEE Transactions Plasma Science Vol 19 Issue 6 1063-1077 (1991)

Fundamental Operation of the Dielectric Barrier DischargeFundamental Operation of the Dielectric Barrier Discharge

bull Many of relevant plasma processes that areof importance to achieving our goal occuron time scales that allow us to study themon time scales that allow us to study them

bull Optical emission spectroscopic studies willallow us to determine the temporal andspatial development of important plasmaspatial development of important plasmaspecies such as radicals (OH NO variousoxygen radicals) with high time resolution(less than 10 ns) and a spatial resolution onthe scale of mm in the plasma volumepfollowing pulsed plasma excitation

Time scale of the relevant processes of the DBD

HE Wagner R Brandenburg et al lsquoThe barrier discharge basic properties and applications tosurface treatmentrsquo Vacuum 71 417-436 (2003)

Fundamental Operation of the DBDFundamental Operation of the DBD

Electron DensityTemporal Development (ns)

y

Outer Contour Linen = 1010 cm-3ne = 1010 cm 3

Inner Contour Linene = 1014 cm-3

Streamer Propagation in 1 bar AirAA Kulikovsky IEEE Trans Plasma Sci 25 439-446 (1997)

Numerical Results of Microdischarge Formationin Dielectric Barrier Discharges

Starting Phase of a Microdischarge (1 bar 20 CO2 80 H2)

E0=34 kVcm1010 cm-3

1010 cm-3 ne=1012 cm-3

1mm10 cm

ne=108 cm-3

An electron avalanche propagates towards the anode

Reverse propagationtowards the cathodepropagates towards the anode towards the cathode

Numerical Results of Microdischarge Formationin Dielectric Barrier Discharges

Cathode Layer Formation

E0=34 kVcm1010 cm-39 3 0

1mm

1010 cm-3

10 cmne=109 cm-31014

10131014

1013

10 cm1012

Just before the peak of the total current

Peak currentof the total current

Numerical Results of Microdischarge Formationin Dielectric Barrier Discharges

Local Field Collapse in Area Defined by Surface Discharge

ne=109cm-3 ne=1014 cm-3

Gap

Principals of DBD MicroplasmasPrincipals of DBD MicroplasmasPrincipals of DBD MicroplasmasPrincipals of DBD Microplasmas

C C-- - --- - - CG

CD

-- - - CG

CD

Principals of DBD MicroplasmasPrincipals of DBD MicroplasmasPrincipals of DBD MicroplasmasPrincipals of DBD Microplasmas

Dielectric Barrier Discharge (DBD)Dielectric Barrier Discharge (DBD)Electric Field

B kdBreakdown

Electrons amp Ions Discharge Physics

Excited SpeciesPlasma Chemistry

Chemical Reactions

OzoneGeneration

SurfaceTreatment

PollutionControl

ExcimerFormation CO2 Lasers Hydrogenation

of CO2

Excimer Lamps Plasma Displays

How A Plasma Display Works

How A Plasma Display Work

Plasma Display TelevisionsPlasma Display Televisions

Ozone Generator

3 O 2 O

Dielectric Barrier Discharge

3 O2 2 O3

OO22 OO33++OO22Ondash ndashO3O2

O2O2

Ondash ndash

endash O2Ondash ndash O2endash

O3

O3O2O2 O2

HeatHeatHeatHeat

Properties of Ozone (O3)

T i t i f f Tri-atomic form of oxygen

Most powerful commercial oxidizing agent

Unstable - must be generated and used onsite

Limited solubility in water but more so than oxygenLimited solubility in water but more so than oxygen

Leaves a dissolved residual which ultimately converts back to oxygenconverts back to oxygen

Discharge Tubes in Ozone GeneratorsDischarge Tubes in Ozone Generators

Traditional

Ozone Generator

with Glass Tubes

Generation of OzoneGeneration of Ozone

Generation of OzoneAdvantages of Enamel Dielectrics

Proven Patented Designbull Simplicity

Si l Di l i Cbull Single Dielectric Componentndash Reduced number of Dielectrics

bull Safety ndash Lower operating voltage

(lt 4000 V)bull Reliabilty

ndash Fused Dielectrics ensure continuous production

bull Lowest Power Consumption Operational Savingsndash Operational Savings

Modern Ozone GeneratorModern Ozone Generator

Ozonia Advanced Technology Ozone GeneratorOzone Generator

Generation of OzoneGeneration of Ozone

Generation of Ozone

Power Supply UnitPower Supply Unit

IGBT Inverter CircuitMain Circuit Breaker

HV 480 Volts60 Hz3 Phase Supply

C I

450KVAPow er to

GeneratorFILTER

CONVERTER INVERTERTRANSFORMER

C I450KVA Power Stage

CONTACTOR

bull Latest in Power Semiconductor Technology Modular Design

bull Utilizes IGBTrsquos (Insulated Gate Bi‐Polar Transistors) Converter and Inverter Components

Ozone Water Treatment

B bbl Diff iB bbl Diff iBubble DiffusionBubble Diffusion

Easy to use

Low energy usage Low energy usage

Mass transfer efficiencies to gt 90

Ozone Process Flow DiagramOzone Process Flow DiagramVent to

Atmosphere

O OOxygen

Off-Gas Blower

Ozone Destruct Unit

10 12

O3O2

LOX

10-12 O3

Ozone Generators

Ozone Contact ChamberLOX T k Generators Chamber

VaporizersLOX Tank

Municipal Ozone Installations

Ozonia Installations Ozone Plant Size [lbday] Start-Up DateKey Ozonia Installations (Partial List)

Los Angeles CA 10000 1986Fairfax VA ndash Corbalis 9000 2003MWD CA ndash Mills 9 000 2003

Ozonia Installations Ozone Plant Size [lbday] Start Up Date

MWD CA Mills 9000 2003Fairfax Co VA ndash Griffith 9000 2004MWD CA ndash Jensen 18750 2005Indianapolis IN ndash Belmont AWT 12000 2007I di li IN 12 000 2007Indianapolis IN ndash Southport AWT 12000 2007MWD CA ndash Diemer 13400 2008MWD CA ndash Weymouth 13400 2009

Ozonia North America - Potable Water SummaryTotal Number of Installations 90Total Installed Production gt 265000 lbsdayTotal Installed Production 265000 lbsday

Revision -B

Ozone Water TreatmentOzone Water Treatment

MWD Mills WTP - California

3 3 000 lbsda of o one3 3 000 lbsda of o one3 x 3000 lbsday of ozone3 x 3000 lbsday of ozone

Ozone Water TreatmentOzone Water TreatmentOzone Ozone -- How it worksHow it works

OxidantOxidant DisinfectantDisinfectant

bullbull Breaks double carbon Breaks double carbon bondsbonds

bullbull Kills by cell lysing or Kills by cell lysing or causing the cell wall tocausing the cell wall tobondsbonds

bullbull Creates OHCreates OHbullbull radicals radicals which break higher carbon which break higher carbon

causing the cell wall to causing the cell wall to rupture rupture

bullbull AttacksAttacks allall bacteriabacteriabondsbondsbullbull Increased temp and pH Increased temp and pH

accelerates Oaccelerates O33

Attacks Attacks allall bacteria bacteria virus cysts and spores virus cysts and spores in varying degreesin varying degreesaccelerates Oaccelerates O33

decomposition to OHdecomposition to OHbullbull

Micro-organism DNA

Capsule AdenineAdenine

Cell wall ThymineThymine

CytosineCytosine

GuanineGuanine

NuclearmaterialCellmembrane

material

Typical Bacterium DNA

Microbial Growth at Various Ozone ConcentrationsConcentrations

Growth likely

Growth possibleGrowth possible

NO GROWTH

0004 0008 0012 0016 0020

Ozone concentration (mgl)Ozone concentration (mgl)

Typical Water Treatment UsageTypical Water Treatment Usage

Application O3 mgl Contact timeUltra Pure Water 005 - 025 sec ndash min

Water bottling 04 ndash 10 5 ndash 10 min

Swimming pools ampspas

01 ndash 075 4 minutes

Potable taste amp odor 15 ndash 50 5 ndash 10 mindisinfection

Microfloculation 10 ndash 30 5 ndash 10 min

Lignin amp tammin 3 0 10 0 10 30 minLignin amp tamminremoval

30 ndash 100 10 ndash 30 min

Municipal wastewater 50 ndash 150+ 15 ndash 30 min

Ozone Water TreatmentOzone Water TreatmentOzone Ozone ndashndash Municipal ApplicationsMunicipal Applications

bullbull Taste and OdorTaste and Odor

bullbull Color RemovalColor Removal

bullbull Disinfection Without Trihalomethanes (THMs)Disinfection Without Trihalomethanes (THMs)

bullbull Improved Filtration Efficiency and FlocculationImproved Filtration Efficiency and Flocculation

bullbull Cryptosporidium DeactivationCryptosporidium Deactivation

bullbull Giardia amp Virus InactivationGiardia amp Virus Inactivation

bullbull Oxidation Oxidation -- Organics Fe amp MnOrganics Fe amp Mn

bullbull Wastewater disinfectionWastewater disinfection

bullbull BOD COD and TOC reductionBOD COD and TOC reduction

Applications of Ozone

Wastewater Treatmentbull Disinfection of Secondary and Tertiary Effluentsbull Color Reductionbull Color Reductionbull TOC Oxidation (Industrial)bull Oxidation of Odor Causing Compoundsbull Oxidation of Endocrine Disruptors (EDCrsquos) and p ( )

Pharmaceutically Active Compounds (PACrsquos)

Applications of Ozone

What are Endocrine Disruptors (EDCrsquos) and What are Endocrine Disruptors (EDCrsquos) and Ph ti ll A ti C d (PACrsquo )Ph ti ll A ti C d (PACrsquo )Pharmaceutically Active Compounds (PACrsquos)Pharmaceutically Active Compounds (PACrsquos)

bullbull EDCrsquosEDCrsquos andand PACrsquosPACrsquos areare NaturallyNaturally andand SyntheticSyntheticdd th tth t ff tff t thth b lb l llcompoundscompounds thatthat maymay affectaffect thethe balancebalance oror normalnormal

functionsfunctions inin animalsanimals andand humanshumans

What can EDCrsquos and PACrsquos doWhat can EDCrsquos and PACrsquos do

bullbull Even in very small concentrations these compounds Even in very small concentrations these compounds y py pcan can disruptdisrupt normal bodily functionsnormal bodily functions

bullbull ManMan--made chemicals can trick the bodies endocrine made chemicals can trick the bodies endocrine system system

Applications of Ozone

Examples of Endocrine Disruptors1000rsquos of compounds that may be Investigated as EDCs ndash Some examples are

bullbull Synthetic HormonesSynthetic Hormonesbullbull Naturally Occurring Estrogens Naturally Occurring Estrogens

Health and Beauty AidsHealth and Beauty Aidsbullbull Health and Beauty AidsHealth and Beauty Aidsbullbull SolventsSolventsbullbull PesticidesPesticidesbullbull SurfactantsSurfactantsbullbull PlasticsPlastics

F i idF i idbullbull FungicidesFungicides

Ozone Water TreatmentOzone Water Treatment

Ozone Ozone -- Industrial ApplicationsIndustrial Applications-- Ultrapure Water for Pharmaceutical ApplicationsUltrapure Water for Pharmaceutical Applications

-- Wastewater disinfection color removalWastewater disinfection color removal

-- Soil and Groundwater Remediation Soil and Groundwater Remediation

-- Cooling Tower Water TreatmentCooling Tower Water Treatment

-- Food ProcessingFood Processing

-- Aquaculture AquariumsAquaculture AquariumsAquaculture AquariumsAquaculture Aquariums

-- Beverage ApplicationsBeverage Applications

P l amp P Bl hiP l amp P Bl hi-- Pulp amp Paper BleachingPulp amp Paper Bleaching

High Purity OzonationHigh Purity Ozonation

Microchip manufacturingMicrochip manufacturing

What are the current issues in large-scale gozone generationg

Experimental Setup

Front view of the two units after the redesign and reworking ofthe gas water and instruments connectionsthe gas water and instruments connections

Experimental Setup

Top view of the twoexperimental unitsexperimental unitsSpectroscope (notshown) is to the left ofthe DBD The units weredifferent with respect todifferent with respect totheir electrodes onehad only the electrodecoated with thedielectric (ldquosingle-dielectric ( single-coatedrdquo) the other onehad the electrode andthe anode coated withthe dielectric (ldquodouble-the dielectric ( double-coatedrdquo)

Basics Generation of OzoneBasics Generation of Ozone

SpectroscopyPlasma

Plasma Absorption SpectroscopyPlasma Absorption Spectroscopy

Infrared Absorption SpectroscopyInfrared Absorption Spectroscopy

IR spectra in pure oxygen (black curve) and at approximately 10wt N2 admixture (red line) N2O5 peaks appear at124 1 d 1 2 11245 cm-1 and at 1725 cm-1

Infrared Absorption SpectroscopyInfrared Absorption Spectroscopy

IR spectra of several methane variations The green curve envelopes all of the methane peaks at 1325 cm-1recorded at smaller methane admixtures Simultaneously the N2O5 peaks disappear as the methane peaks appear

N2O5 FormationN2O5 Formation2 52 5p=2 bara cwt=20degC q=35kWm2 f=1450Hz

45N2O5 AT95

30

35

40

N

2 B

lend

ing

N2O AT95N2O5 IGSN2O IGSN2O5 LGN2O LG

1 5

20

25

nt [p

pmV]

3

wt

05

10

15

NO

x co

nten

005 7 9 11 13 15 17

ozone conc [wt]

Amount of formed N2O5 and N2O as a function of ozone concentration at 3 wt of nitrogen admixture and fori l dvarious electrode arrangements

Plasma Emission SpectroscopyPlasma Emission Spectroscopyp pyp py

Relative Emissions of the Ozonizer plasmaRelative Emissions of the Ozonizer plasma

Region 300- 850 nm from individual (calibrated) regions (smoothed by PeakFit) Single-coated ozone generator Inlet side

3 5E+06

30E+06

35E+06

7 9

20E+06

25E+06

nten

sity

au

2

311 12

10E+06

15E+06

In 4

5

6 8 10

14

15

16

17

00E+00

50E+05

280 300 320 340 360 380 400 420 440 460 480 500 520 540 560 580 600 620 640 660 680 700 720 740 760 780 800 820 840 860

Wavelength nm

1 13

Wavelength nm

Absolute Emission of the DBD PlasmaAbsolute Emission of the DBD Plasma

Intensities in (O2+3 wtN2) plasma

1 20E+04

100E+04

120E+04

600E+03

800E+03

nten

sity

(au

)

200E+03

400E+03

In

O(777)

000E+00200 250 300 350 400 450 500 550 600 650 700 750 800 850

Wavelength nm

Intensities in 3 wtN2+O2 plasmaIntensities in 3 wtN2+O2 plasma

Plasma Chemistry in OzonizersPlasma Chemistry in Ozonizers

Dry Air O2 N2

e - e -

O N2 N O2

O3 NO

O2 N O2

O3

N

3

NO2

O2 O3

NO

N

NO2 O3

N2O

NO3 N

N2O4

NO2

NO2

N2O5

NO3

Primary electron-driven chemical reactions leading to the formation of N2O5 and N2O in a dry air plasma

Plasma emission diagnostics role of N2Plasma emission diagnostics role of N2

Dry Air O2 N2

e - e -

O N2 N O2

O3 NO

O2 N O2

O3

O

N

ON

NO2

O2O3

N

NO N

NO2 O3

N2O

NO3 N

N2O4

NO2

NO2

N2O5

NO3

ONbullWith N2 present ndash less oxygen atoms are formed However the difference in intensity is

very small

Modeling of plasma chemistry incl the NxOy chemistry up to N2O5 for different Oxygen Nitrogen mixtures varying power deposition scenarios

and initial ozone background concentrations (up to 15) previously done

The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation

The role of N2 must be related to its by-products reacting on the surface of the electrodeThe role of N2 must be related to its by-products reacting on the surface of the electrode

The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established

Ab 8 t f O

The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established

Ab 8 t f OAbove 8 wt of O3

1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)

Above 8 wt of O3

1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)case without pampp)

2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of the

case without pampp)

2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of thethem A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface

them A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface

The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation

Three possibilities have to be considered for the oxygen-fedozone generator

Three possibilities have to be considered for the oxygen-fedozone generatorozone generator

bull Excited N2 molecules lead to an increased O2 dissociation in

ozone generator

bull Excited N2 molecules lead to an increased O2 dissociation in2 2such case an increased efficiency is correlated to the N2admixture

2 2such case an increased efficiency is correlated to the N2admixture

bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial

bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial

bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2

bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2g p g 3 pp y 2g p g 3 pp y 2

Effect of methane on ozone efficiency and specific powerEffect of methane on ozone efficiency and specific power

Effect of Methane on Ozone Content in Outlet Gas and on Specific Power Pure O2

13 12

10

11

12

t 8

10

8

9

10

ne c

onte

nt w

t

6

8

ecifi

c po

wer

kW

hlb

5

6

7

Ozo

n

2

4 Spe

400E+00 20E+03 40E+03 60E+03 80E+03 10E+04 12E+04

Methane in feedgas ppm

0

Ozone content in the outlet gas Specif ic pow er of the ozone generatorg p p g

Effects of N2 and CH4Effects of N2 and CH4

Pi t f h t lli N O t tPicture of an amorphous-crystalline N2O5 structurecaptured at the Orlando Skylake water plant in 2006

Plasma Chemistry with CH4 Impurities

OxygenO2 N2

e - e -

CHO N2

NO2

O NO

O2 N O2 O3

NOH

CH4e-

O3 NO

NO2

O2O3NO N

NO2 O

NO2

NO2

N2ONO3

N

O3

NO2

NO

HNO3

N2O4

N2O5

NO2

NO3

N2O5

Effect of methane on the electrode surfaces

a) b)

Inlet Outlet Outlet

) d)

I l t I l t

c) d)

Electrode of the ozone generator afterseveral hours in CH8O2 and up to 2 wt of methane (a b c)

Inlet Inlet

three hours in CH8O2+traces of N2 and up to 1 wt of methane (d) Visible change of discharge character at about 13 length of electrode (a d)

Kinetics of CHx Conversion without N2

conversion by collisions

O2 + CHx 12wt O3 + CO2 +H2O

deposition vaporizationby sputtering

ibl b l 1000 CHreversible process below 1000ppm CH4

Effect of water on electrode surface with N2

Inlet

OutletOutlet

Electrode of the ozone generator after several hours in H OO N

Inlet

Electrode of the ozone generator after several hours in H2OO2N2

Effect of water on electrode surface

Long term effect (800 hrs) of H2OO2N2

Kinetics of CHx Conversion with N2

conversion by collisionsHNO3 formation

O2 + N2 +CHx 12wtO2 + CO2 +H2O + HNO3

deposition vaporizationby sputtering

H2O + HNO3

by sputtering

irreversible process above a N2 threshold () ltlt 1000ppm N2

sticky deposit

p 2 ( ) pp 2 any CH4 concentration (60ppm)

Plasma Chemistry with CH4 ImpuritiesPlasma Chemistry with CH4 Impurities4

bull Formation of NO and NO2 depends on O3 N2 and gas temperature Conclusion N2 admixture is the key factor

SummarySummaryyyThe mechanisms of formed NOx by-products follows the sameThe mechanisms of formed NOx by-products follows the sameprinciples as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentration

principles as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentrationozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)

ozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)g p ( g p )

The conversion of methane to OH and H2O is found to depend on

g p ( g p )

The conversion of methane to OH and H2O is found to depend ondissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)

dissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)discharge gap)discharge gap)

How do you optimize an ozone generatorg

Scientific ApproachScientific ApproachTheoretical Experimental

pppp

c [wt]

f [Hz]

c [wt]

f [Hz]

[kW]UUUβ1

1Cf4αPn

1iiminpeakimin

iiD

q [kWm2]q [kWm2]

150

180

][V]voltagepeakUpeak

[]cylinder perslicesofamountnsliceii

whereth

09 00

30

60

90

120

effic

ienc

y [

][0tdj t bl[F]sliceisdielectricofecapacitancC

[Hz]frequencyf[V]sliceivoltageminimumiUmin

thiD

th

10

28

46

64

82

39

107

176

244 power density

[kWm2]

ozone conc [wt][]CCβ

][0parameteradjustableα

iDiGi

Impact of Power Inductionp

350

400

wer

200

250

300

App

lied

Pow

Arr C 2Arr D +0

Arr E +45Arr F +7

Arr G +3

5 0

100

150

Frac

tion

of

1 2 3 4

ReferenceArr B unstable

Arr C -2

00

50

4Position (1inlet 4outlet)

Experimental Test Rigp g

Experimental Test Rigp g

Outer grounded electrode (left picture) and the dielectric covered inner electrodes (right) d e ect c cove ed e e ect odes ( g t)

Reference (Traditional) Arrangement

Inlet OutletGas flow direction

Optimized Arrangement

Inlet OutletGas flow direction

Intelligent Gap System (IGS)g p y ( )

Molecular Oxygen (O2) Ozone (O3)

O2 O3

yg ( 2) ( 3)

Particle Size SynthesisParticle Size SynthesisByBy--Products Cluster FormationProducts Cluster Formationyy

high diffusion and deposition to surfaces

low diffusion rate good transport

high sedimentation on the structurehigh sedimentation on the structure

Degreacutemont Technologies ndash OzoniaIntelligent Gap SystemIntelligent Gap System

G Vezzuacute JL Lopez A Freilich and K Becker Optimizationof Large-Scale Ozone Generators IEEE Transactions onPlasma Science Vol 37 No 6 p 890-896 (2009)

ConclusionsConclusionsConclusionsConclusionsFundamentals of ozone synthesis in a DBD plasmay p

ndash Highly filamented DBD discharges are best-suitedfor the production of ozone concentrations in therange of 6 to 14 wtrange of 6 to 14 wt

ndash The preferred characteristic of the microdischargesare Townsend-like at reduced electric fields Enaround 190 Townsend

ndash Detrimental side-effects induced by by-productscan be avoided by a proper design of the electrodecan be avoided by a proper design of the electrodearrangement The phenomenon is related to thediffusion rates of formed by-product clusters

ConclusionsConclusionsConclusionsConclusionsBenefits from DBD microplasma tailoring

ndash Reduced power consumption of up to 10 improvement

ndash Increased ozone concentrations of up to 14 now achievable

ndash Improved neutralization and conditioning of detrimental by-products

ndash Reduced system capital and operational cost

New technologies to improve ozone p

generatorg

HV Pulsed Power SwitchingHV Pulsed Power Switching

Microchannel Generation of Ozone

Channel ArrayChannel Array

Microchannel

330 microm 230 microm

Some Cap-DBD Devices Operating in Air

Increase of 60 of

Spacing 225 μmof 60 of plasma

No space

Cap‐DBD ozone generation

bull Ozone concentration is evaluated via Eco S d l UV 100 O A l (0 01Sensors model UV-100 Ozone Analyzer (001 ndash 900 ppm wiht an accuracy of plusmn2)

bull Three reactors 6 tubings 6rdquo with spacings of 0 μm 225 μm and 500 μm running at 3 kV μ μ μ g

SpacingOzone Concentration

3 kV rms 4 kV rms3 kV rms 4 kV rms

0 μm 660 ppm

225 μm 550 ppm

For a device of such small scale these ozone levels are promising

500 μm 380 ppm

J Mahoney W Zhu VS Johnson KH Becker and JL Lopez Electrical and optical emissionmeasurements of a capillary dielectric barrier discharge European Physics Journal D Vol 60 441-447(2010)

QuestionsQuestions

Thank YouFor more informationProf Jose L Lopez PhD

Thank YouFor more informationDepartment of Physics

Telephone (973) 761-9057Email joselopez1shuedu

Website wwwshueduacademicsartsciphysicsWebsite wwwshueduacademicsartsciphysics

Page 14: Dielectric Barrier Discharge (DBD) & Progress in Large ...bonitz/si12/talks/august_8/lopez_si12.pdf · Dielectric Barrier Discharge (DBD) & Progress in Large-Scale Ozone Generation

What happens at air pressureWhat happens at air pressure

bull No vacuum is involvedDiffi l d ibull Difficult to generate and sustain

bull Run into some challenges such as glow toarc transition ndash Non controllable

Arc Discharge thermal plasma-Itrsquos hot and detrimental-Gas temperature can reach as high as 2x104 KGas temperature can reach as high as 2x10 K- Low voltage drop at cathode- High cathode current density

High Pressure Microplasmas

Stabilization of high-pressure plasmas ldquopd scalingrdquo ldquoprdquo uarr soplasmas pd scaling p uarr so ldquodrdquo darr to keep breakdown voltage low and minimize instabilities after breakdown -

MicroplasmasDimension a few millimeterDimension a few millimeter down to and below 100 m

Paschen Breakdown CurveH H i 60 100Human Hair 60 ndash 100 m

How do we solve this problemHow do we solve this problem

Transient (pulsed) plasmas In atmospheric plasmas for efficient gas heating atleast 100-1000 collisions are necessary Thus if the plasma duration is shorterleast 100 1000 collisions are necessary Thus if the plasma duration is shorterthan 10-6 ndash 10-5 s gas heating is limited Of course for practical purposes suchplasma has to be operated in a repetitive mode eg in trains of microsecondpulses with millisecond intervals

Micro-confinement Gas heating occurs in the plasma volume and the energy iscarried away by thermal diffusionconvection to the outside If the plasma has asmall volume and a relatively large surface gas heating is limited

Dielectric Barrier Discharges These plasmas are typically created betweenmetal plates which are covered by a thin layer of dielectric or highly resistivematerial The dielectric layer plays an important role in suppressing the currentthe cathodeanode layer is charged by incoming positive ionselectrons whichreduces the electric field and hinders charge transport towards the electrodeDBD also has a large surface-to-volume ratio which promotes diffusion lossesand maintains a low gas temperatureand maintains a low gas temperature

Advantages of Microplasmas Advantages of Microplasmas

bull Low-cost of implementationpbull System flexibilitybull Atmospheric pressure operationbull High densities and high reaction ratesbull High densities and high reaction ratesbull Fast and efficient processesbull Easy to generate and sustain for a variety of gas mixtures

Gl lik d diffbull Glow-like and diffusebull Non-equilibrium (Te gt Tg) to thermalbull Unique chemistryq y

hellip a new realm of plasma sciencehellip a new realm of plasma science

What can we do with microplasmasWhat can we do with microplasmas

Material Synthesis Plasma display Surface Treatment Lighting

OzoneOzone generation for water cleaning

Bio-applicationMaterial processing Dental application

and Many morehellip

Some High Pressure microplasma reactors Some High Pressure microplasma reactors

Dielectric Barrier Discharge (DBD)Dielectric Barrier Discharge (DBD)

Hi h V l

HighVoltage

High VoltageElectrode

ACGenerator

DielectricBarrier

Generator

G

Microplasmas

GroundElectrode

Faradayrsquos Dielectric CapacitorsFaradayrsquos Dielectric Capacitors

Faradays Dielectric Capacitor (circa 1837)

Michael Faraday (1781 ndash 1867) Capacitance INCREASED

Historical Ozone Tube of W Siemens (1857)Historical Ozone Tube of W Siemens (1857)

Werner v SiemensP d frsquo A l d Ch i d Ph ik 102 66 (1857)Poggendorfrsquos Annalen der Chemie und Physik 102 66 (1857)

ldquoOzone Production in an Atmospheric-PressureDielectric Barrier Dischargerdquo

Dielectric Barrier Discharge

Dielectric Barrier DischargeDielectric - Barrier Discharge ConfigurationsHigh

VoltageAC

Generator

High VoltageElectrode

DielectricBarrier

DielectricBarrier

High VoltageElectrode

Discharge

DischargeGeneratorGround

Electrode

Electrode

GroundElectrode

Discharge

H E Wagner R Brandenburg et al lsquoThe barrier discharge basic properties and applications toHE Wagner R Brandenburg et al The barrier discharge basic properties and applications tosurface treatmentrsquo Vacuum 71 p417-436 (2003)

Typical operational conditions of barrier discharges Typical operational conditions of barrier discharges

Electric field strength E of first breakdown asymp150 Td (p = 1bar T=300 K)

Voltage Vpp 3ndash20 kV

Repetition frequency f 50 Hzndash30 kHz

Pressure p 1ndash3 bar

Gap distance g 02ndash5mm

Dielectric material thickness d 05ndash2mm

Relative dielectric permittivity r 5ndash10 (glass)

B Eliasson and U Kogelschatz IEEE Transactions Plasma Science Vol 19 Issue 6 1063-1077 (1991)B Eliasson and U Kogelschatz IEEE Transactions Plasma Science Vol 19 Issue 6 1063-1077 (1991)

Single and double DBD

Single dielectric Double dielectric

Role of the Dielectric (Insulator)

Th di l t i i th k f thThe dielectric is the key for the properfunctioning of the discharge

Serves two functions

1 Limits the amount of charge transportedby a single microplasma

2 Distributes the microplasmas over theentire electrode surface area

Equivalent Circuit of a Microdischarge

Microdischarge Activity and U-Q Lissajous Figure

B Eliasson and U Kogelschatz IEEE Transactions Plasma Science Vol 19 Issue 6 1063-1077 (1991)

Fundamental Operation of the Dielectric Barrier DischargeFundamental Operation of the Dielectric Barrier Discharge

bull Many of relevant plasma processes that areof importance to achieving our goal occuron time scales that allow us to study themon time scales that allow us to study them

bull Optical emission spectroscopic studies willallow us to determine the temporal andspatial development of important plasmaspatial development of important plasmaspecies such as radicals (OH NO variousoxygen radicals) with high time resolution(less than 10 ns) and a spatial resolution onthe scale of mm in the plasma volumepfollowing pulsed plasma excitation

Time scale of the relevant processes of the DBD

HE Wagner R Brandenburg et al lsquoThe barrier discharge basic properties and applications tosurface treatmentrsquo Vacuum 71 417-436 (2003)

Fundamental Operation of the DBDFundamental Operation of the DBD

Electron DensityTemporal Development (ns)

y

Outer Contour Linen = 1010 cm-3ne = 1010 cm 3

Inner Contour Linene = 1014 cm-3

Streamer Propagation in 1 bar AirAA Kulikovsky IEEE Trans Plasma Sci 25 439-446 (1997)

Numerical Results of Microdischarge Formationin Dielectric Barrier Discharges

Starting Phase of a Microdischarge (1 bar 20 CO2 80 H2)

E0=34 kVcm1010 cm-3

1010 cm-3 ne=1012 cm-3

1mm10 cm

ne=108 cm-3

An electron avalanche propagates towards the anode

Reverse propagationtowards the cathodepropagates towards the anode towards the cathode

Numerical Results of Microdischarge Formationin Dielectric Barrier Discharges

Cathode Layer Formation

E0=34 kVcm1010 cm-39 3 0

1mm

1010 cm-3

10 cmne=109 cm-31014

10131014

1013

10 cm1012

Just before the peak of the total current

Peak currentof the total current

Numerical Results of Microdischarge Formationin Dielectric Barrier Discharges

Local Field Collapse in Area Defined by Surface Discharge

ne=109cm-3 ne=1014 cm-3

Gap

Principals of DBD MicroplasmasPrincipals of DBD MicroplasmasPrincipals of DBD MicroplasmasPrincipals of DBD Microplasmas

C C-- - --- - - CG

CD

-- - - CG

CD

Principals of DBD MicroplasmasPrincipals of DBD MicroplasmasPrincipals of DBD MicroplasmasPrincipals of DBD Microplasmas

Dielectric Barrier Discharge (DBD)Dielectric Barrier Discharge (DBD)Electric Field

B kdBreakdown

Electrons amp Ions Discharge Physics

Excited SpeciesPlasma Chemistry

Chemical Reactions

OzoneGeneration

SurfaceTreatment

PollutionControl

ExcimerFormation CO2 Lasers Hydrogenation

of CO2

Excimer Lamps Plasma Displays

How A Plasma Display Works

How A Plasma Display Work

Plasma Display TelevisionsPlasma Display Televisions

Ozone Generator

3 O 2 O

Dielectric Barrier Discharge

3 O2 2 O3

OO22 OO33++OO22Ondash ndashO3O2

O2O2

Ondash ndash

endash O2Ondash ndash O2endash

O3

O3O2O2 O2

HeatHeatHeatHeat

Properties of Ozone (O3)

T i t i f f Tri-atomic form of oxygen

Most powerful commercial oxidizing agent

Unstable - must be generated and used onsite

Limited solubility in water but more so than oxygenLimited solubility in water but more so than oxygen

Leaves a dissolved residual which ultimately converts back to oxygenconverts back to oxygen

Discharge Tubes in Ozone GeneratorsDischarge Tubes in Ozone Generators

Traditional

Ozone Generator

with Glass Tubes

Generation of OzoneGeneration of Ozone

Generation of OzoneAdvantages of Enamel Dielectrics

Proven Patented Designbull Simplicity

Si l Di l i Cbull Single Dielectric Componentndash Reduced number of Dielectrics

bull Safety ndash Lower operating voltage

(lt 4000 V)bull Reliabilty

ndash Fused Dielectrics ensure continuous production

bull Lowest Power Consumption Operational Savingsndash Operational Savings

Modern Ozone GeneratorModern Ozone Generator

Ozonia Advanced Technology Ozone GeneratorOzone Generator

Generation of OzoneGeneration of Ozone

Generation of Ozone

Power Supply UnitPower Supply Unit

IGBT Inverter CircuitMain Circuit Breaker

HV 480 Volts60 Hz3 Phase Supply

C I

450KVAPow er to

GeneratorFILTER

CONVERTER INVERTERTRANSFORMER

C I450KVA Power Stage

CONTACTOR

bull Latest in Power Semiconductor Technology Modular Design

bull Utilizes IGBTrsquos (Insulated Gate Bi‐Polar Transistors) Converter and Inverter Components

Ozone Water Treatment

B bbl Diff iB bbl Diff iBubble DiffusionBubble Diffusion

Easy to use

Low energy usage Low energy usage

Mass transfer efficiencies to gt 90

Ozone Process Flow DiagramOzone Process Flow DiagramVent to

Atmosphere

O OOxygen

Off-Gas Blower

Ozone Destruct Unit

10 12

O3O2

LOX

10-12 O3

Ozone Generators

Ozone Contact ChamberLOX T k Generators Chamber

VaporizersLOX Tank

Municipal Ozone Installations

Ozonia Installations Ozone Plant Size [lbday] Start-Up DateKey Ozonia Installations (Partial List)

Los Angeles CA 10000 1986Fairfax VA ndash Corbalis 9000 2003MWD CA ndash Mills 9 000 2003

Ozonia Installations Ozone Plant Size [lbday] Start Up Date

MWD CA Mills 9000 2003Fairfax Co VA ndash Griffith 9000 2004MWD CA ndash Jensen 18750 2005Indianapolis IN ndash Belmont AWT 12000 2007I di li IN 12 000 2007Indianapolis IN ndash Southport AWT 12000 2007MWD CA ndash Diemer 13400 2008MWD CA ndash Weymouth 13400 2009

Ozonia North America - Potable Water SummaryTotal Number of Installations 90Total Installed Production gt 265000 lbsdayTotal Installed Production 265000 lbsday

Revision -B

Ozone Water TreatmentOzone Water Treatment

MWD Mills WTP - California

3 3 000 lbsda of o one3 3 000 lbsda of o one3 x 3000 lbsday of ozone3 x 3000 lbsday of ozone

Ozone Water TreatmentOzone Water TreatmentOzone Ozone -- How it worksHow it works

OxidantOxidant DisinfectantDisinfectant

bullbull Breaks double carbon Breaks double carbon bondsbonds

bullbull Kills by cell lysing or Kills by cell lysing or causing the cell wall tocausing the cell wall tobondsbonds

bullbull Creates OHCreates OHbullbull radicals radicals which break higher carbon which break higher carbon

causing the cell wall to causing the cell wall to rupture rupture

bullbull AttacksAttacks allall bacteriabacteriabondsbondsbullbull Increased temp and pH Increased temp and pH

accelerates Oaccelerates O33

Attacks Attacks allall bacteria bacteria virus cysts and spores virus cysts and spores in varying degreesin varying degreesaccelerates Oaccelerates O33

decomposition to OHdecomposition to OHbullbull

Micro-organism DNA

Capsule AdenineAdenine

Cell wall ThymineThymine

CytosineCytosine

GuanineGuanine

NuclearmaterialCellmembrane

material

Typical Bacterium DNA

Microbial Growth at Various Ozone ConcentrationsConcentrations

Growth likely

Growth possibleGrowth possible

NO GROWTH

0004 0008 0012 0016 0020

Ozone concentration (mgl)Ozone concentration (mgl)

Typical Water Treatment UsageTypical Water Treatment Usage

Application O3 mgl Contact timeUltra Pure Water 005 - 025 sec ndash min

Water bottling 04 ndash 10 5 ndash 10 min

Swimming pools ampspas

01 ndash 075 4 minutes

Potable taste amp odor 15 ndash 50 5 ndash 10 mindisinfection

Microfloculation 10 ndash 30 5 ndash 10 min

Lignin amp tammin 3 0 10 0 10 30 minLignin amp tamminremoval

30 ndash 100 10 ndash 30 min

Municipal wastewater 50 ndash 150+ 15 ndash 30 min

Ozone Water TreatmentOzone Water TreatmentOzone Ozone ndashndash Municipal ApplicationsMunicipal Applications

bullbull Taste and OdorTaste and Odor

bullbull Color RemovalColor Removal

bullbull Disinfection Without Trihalomethanes (THMs)Disinfection Without Trihalomethanes (THMs)

bullbull Improved Filtration Efficiency and FlocculationImproved Filtration Efficiency and Flocculation

bullbull Cryptosporidium DeactivationCryptosporidium Deactivation

bullbull Giardia amp Virus InactivationGiardia amp Virus Inactivation

bullbull Oxidation Oxidation -- Organics Fe amp MnOrganics Fe amp Mn

bullbull Wastewater disinfectionWastewater disinfection

bullbull BOD COD and TOC reductionBOD COD and TOC reduction

Applications of Ozone

Wastewater Treatmentbull Disinfection of Secondary and Tertiary Effluentsbull Color Reductionbull Color Reductionbull TOC Oxidation (Industrial)bull Oxidation of Odor Causing Compoundsbull Oxidation of Endocrine Disruptors (EDCrsquos) and p ( )

Pharmaceutically Active Compounds (PACrsquos)

Applications of Ozone

What are Endocrine Disruptors (EDCrsquos) and What are Endocrine Disruptors (EDCrsquos) and Ph ti ll A ti C d (PACrsquo )Ph ti ll A ti C d (PACrsquo )Pharmaceutically Active Compounds (PACrsquos)Pharmaceutically Active Compounds (PACrsquos)

bullbull EDCrsquosEDCrsquos andand PACrsquosPACrsquos areare NaturallyNaturally andand SyntheticSyntheticdd th tth t ff tff t thth b lb l llcompoundscompounds thatthat maymay affectaffect thethe balancebalance oror normalnormal

functionsfunctions inin animalsanimals andand humanshumans

What can EDCrsquos and PACrsquos doWhat can EDCrsquos and PACrsquos do

bullbull Even in very small concentrations these compounds Even in very small concentrations these compounds y py pcan can disruptdisrupt normal bodily functionsnormal bodily functions

bullbull ManMan--made chemicals can trick the bodies endocrine made chemicals can trick the bodies endocrine system system

Applications of Ozone

Examples of Endocrine Disruptors1000rsquos of compounds that may be Investigated as EDCs ndash Some examples are

bullbull Synthetic HormonesSynthetic Hormonesbullbull Naturally Occurring Estrogens Naturally Occurring Estrogens

Health and Beauty AidsHealth and Beauty Aidsbullbull Health and Beauty AidsHealth and Beauty Aidsbullbull SolventsSolventsbullbull PesticidesPesticidesbullbull SurfactantsSurfactantsbullbull PlasticsPlastics

F i idF i idbullbull FungicidesFungicides

Ozone Water TreatmentOzone Water Treatment

Ozone Ozone -- Industrial ApplicationsIndustrial Applications-- Ultrapure Water for Pharmaceutical ApplicationsUltrapure Water for Pharmaceutical Applications

-- Wastewater disinfection color removalWastewater disinfection color removal

-- Soil and Groundwater Remediation Soil and Groundwater Remediation

-- Cooling Tower Water TreatmentCooling Tower Water Treatment

-- Food ProcessingFood Processing

-- Aquaculture AquariumsAquaculture AquariumsAquaculture AquariumsAquaculture Aquariums

-- Beverage ApplicationsBeverage Applications

P l amp P Bl hiP l amp P Bl hi-- Pulp amp Paper BleachingPulp amp Paper Bleaching

High Purity OzonationHigh Purity Ozonation

Microchip manufacturingMicrochip manufacturing

What are the current issues in large-scale gozone generationg

Experimental Setup

Front view of the two units after the redesign and reworking ofthe gas water and instruments connectionsthe gas water and instruments connections

Experimental Setup

Top view of the twoexperimental unitsexperimental unitsSpectroscope (notshown) is to the left ofthe DBD The units weredifferent with respect todifferent with respect totheir electrodes onehad only the electrodecoated with thedielectric (ldquosingle-dielectric ( single-coatedrdquo) the other onehad the electrode andthe anode coated withthe dielectric (ldquodouble-the dielectric ( double-coatedrdquo)

Basics Generation of OzoneBasics Generation of Ozone

SpectroscopyPlasma

Plasma Absorption SpectroscopyPlasma Absorption Spectroscopy

Infrared Absorption SpectroscopyInfrared Absorption Spectroscopy

IR spectra in pure oxygen (black curve) and at approximately 10wt N2 admixture (red line) N2O5 peaks appear at124 1 d 1 2 11245 cm-1 and at 1725 cm-1

Infrared Absorption SpectroscopyInfrared Absorption Spectroscopy

IR spectra of several methane variations The green curve envelopes all of the methane peaks at 1325 cm-1recorded at smaller methane admixtures Simultaneously the N2O5 peaks disappear as the methane peaks appear

N2O5 FormationN2O5 Formation2 52 5p=2 bara cwt=20degC q=35kWm2 f=1450Hz

45N2O5 AT95

30

35

40

N

2 B

lend

ing

N2O AT95N2O5 IGSN2O IGSN2O5 LGN2O LG

1 5

20

25

nt [p

pmV]

3

wt

05

10

15

NO

x co

nten

005 7 9 11 13 15 17

ozone conc [wt]

Amount of formed N2O5 and N2O as a function of ozone concentration at 3 wt of nitrogen admixture and fori l dvarious electrode arrangements

Plasma Emission SpectroscopyPlasma Emission Spectroscopyp pyp py

Relative Emissions of the Ozonizer plasmaRelative Emissions of the Ozonizer plasma

Region 300- 850 nm from individual (calibrated) regions (smoothed by PeakFit) Single-coated ozone generator Inlet side

3 5E+06

30E+06

35E+06

7 9

20E+06

25E+06

nten

sity

au

2

311 12

10E+06

15E+06

In 4

5

6 8 10

14

15

16

17

00E+00

50E+05

280 300 320 340 360 380 400 420 440 460 480 500 520 540 560 580 600 620 640 660 680 700 720 740 760 780 800 820 840 860

Wavelength nm

1 13

Wavelength nm

Absolute Emission of the DBD PlasmaAbsolute Emission of the DBD Plasma

Intensities in (O2+3 wtN2) plasma

1 20E+04

100E+04

120E+04

600E+03

800E+03

nten

sity

(au

)

200E+03

400E+03

In

O(777)

000E+00200 250 300 350 400 450 500 550 600 650 700 750 800 850

Wavelength nm

Intensities in 3 wtN2+O2 plasmaIntensities in 3 wtN2+O2 plasma

Plasma Chemistry in OzonizersPlasma Chemistry in Ozonizers

Dry Air O2 N2

e - e -

O N2 N O2

O3 NO

O2 N O2

O3

N

3

NO2

O2 O3

NO

N

NO2 O3

N2O

NO3 N

N2O4

NO2

NO2

N2O5

NO3

Primary electron-driven chemical reactions leading to the formation of N2O5 and N2O in a dry air plasma

Plasma emission diagnostics role of N2Plasma emission diagnostics role of N2

Dry Air O2 N2

e - e -

O N2 N O2

O3 NO

O2 N O2

O3

O

N

ON

NO2

O2O3

N

NO N

NO2 O3

N2O

NO3 N

N2O4

NO2

NO2

N2O5

NO3

ONbullWith N2 present ndash less oxygen atoms are formed However the difference in intensity is

very small

Modeling of plasma chemistry incl the NxOy chemistry up to N2O5 for different Oxygen Nitrogen mixtures varying power deposition scenarios

and initial ozone background concentrations (up to 15) previously done

The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation

The role of N2 must be related to its by-products reacting on the surface of the electrodeThe role of N2 must be related to its by-products reacting on the surface of the electrode

The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established

Ab 8 t f O

The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established

Ab 8 t f OAbove 8 wt of O3

1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)

Above 8 wt of O3

1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)case without pampp)

2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of the

case without pampp)

2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of thethem A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface

them A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface

The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation

Three possibilities have to be considered for the oxygen-fedozone generator

Three possibilities have to be considered for the oxygen-fedozone generatorozone generator

bull Excited N2 molecules lead to an increased O2 dissociation in

ozone generator

bull Excited N2 molecules lead to an increased O2 dissociation in2 2such case an increased efficiency is correlated to the N2admixture

2 2such case an increased efficiency is correlated to the N2admixture

bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial

bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial

bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2

bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2g p g 3 pp y 2g p g 3 pp y 2

Effect of methane on ozone efficiency and specific powerEffect of methane on ozone efficiency and specific power

Effect of Methane on Ozone Content in Outlet Gas and on Specific Power Pure O2

13 12

10

11

12

t 8

10

8

9

10

ne c

onte

nt w

t

6

8

ecifi

c po

wer

kW

hlb

5

6

7

Ozo

n

2

4 Spe

400E+00 20E+03 40E+03 60E+03 80E+03 10E+04 12E+04

Methane in feedgas ppm

0

Ozone content in the outlet gas Specif ic pow er of the ozone generatorg p p g

Effects of N2 and CH4Effects of N2 and CH4

Pi t f h t lli N O t tPicture of an amorphous-crystalline N2O5 structurecaptured at the Orlando Skylake water plant in 2006

Plasma Chemistry with CH4 Impurities

OxygenO2 N2

e - e -

CHO N2

NO2

O NO

O2 N O2 O3

NOH

CH4e-

O3 NO

NO2

O2O3NO N

NO2 O

NO2

NO2

N2ONO3

N

O3

NO2

NO

HNO3

N2O4

N2O5

NO2

NO3

N2O5

Effect of methane on the electrode surfaces

a) b)

Inlet Outlet Outlet

) d)

I l t I l t

c) d)

Electrode of the ozone generator afterseveral hours in CH8O2 and up to 2 wt of methane (a b c)

Inlet Inlet

three hours in CH8O2+traces of N2 and up to 1 wt of methane (d) Visible change of discharge character at about 13 length of electrode (a d)

Kinetics of CHx Conversion without N2

conversion by collisions

O2 + CHx 12wt O3 + CO2 +H2O

deposition vaporizationby sputtering

ibl b l 1000 CHreversible process below 1000ppm CH4

Effect of water on electrode surface with N2

Inlet

OutletOutlet

Electrode of the ozone generator after several hours in H OO N

Inlet

Electrode of the ozone generator after several hours in H2OO2N2

Effect of water on electrode surface

Long term effect (800 hrs) of H2OO2N2

Kinetics of CHx Conversion with N2

conversion by collisionsHNO3 formation

O2 + N2 +CHx 12wtO2 + CO2 +H2O + HNO3

deposition vaporizationby sputtering

H2O + HNO3

by sputtering

irreversible process above a N2 threshold () ltlt 1000ppm N2

sticky deposit

p 2 ( ) pp 2 any CH4 concentration (60ppm)

Plasma Chemistry with CH4 ImpuritiesPlasma Chemistry with CH4 Impurities4

bull Formation of NO and NO2 depends on O3 N2 and gas temperature Conclusion N2 admixture is the key factor

SummarySummaryyyThe mechanisms of formed NOx by-products follows the sameThe mechanisms of formed NOx by-products follows the sameprinciples as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentration

principles as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentrationozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)

ozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)g p ( g p )

The conversion of methane to OH and H2O is found to depend on

g p ( g p )

The conversion of methane to OH and H2O is found to depend ondissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)

dissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)discharge gap)discharge gap)

How do you optimize an ozone generatorg

Scientific ApproachScientific ApproachTheoretical Experimental

pppp

c [wt]

f [Hz]

c [wt]

f [Hz]

[kW]UUUβ1

1Cf4αPn

1iiminpeakimin

iiD

q [kWm2]q [kWm2]

150

180

][V]voltagepeakUpeak

[]cylinder perslicesofamountnsliceii

whereth

09 00

30

60

90

120

effic

ienc

y [

][0tdj t bl[F]sliceisdielectricofecapacitancC

[Hz]frequencyf[V]sliceivoltageminimumiUmin

thiD

th

10

28

46

64

82

39

107

176

244 power density

[kWm2]

ozone conc [wt][]CCβ

][0parameteradjustableα

iDiGi

Impact of Power Inductionp

350

400

wer

200

250

300

App

lied

Pow

Arr C 2Arr D +0

Arr E +45Arr F +7

Arr G +3

5 0

100

150

Frac

tion

of

1 2 3 4

ReferenceArr B unstable

Arr C -2

00

50

4Position (1inlet 4outlet)

Experimental Test Rigp g

Experimental Test Rigp g

Outer grounded electrode (left picture) and the dielectric covered inner electrodes (right) d e ect c cove ed e e ect odes ( g t)

Reference (Traditional) Arrangement

Inlet OutletGas flow direction

Optimized Arrangement

Inlet OutletGas flow direction

Intelligent Gap System (IGS)g p y ( )

Molecular Oxygen (O2) Ozone (O3)

O2 O3

yg ( 2) ( 3)

Particle Size SynthesisParticle Size SynthesisByBy--Products Cluster FormationProducts Cluster Formationyy

high diffusion and deposition to surfaces

low diffusion rate good transport

high sedimentation on the structurehigh sedimentation on the structure

Degreacutemont Technologies ndash OzoniaIntelligent Gap SystemIntelligent Gap System

G Vezzuacute JL Lopez A Freilich and K Becker Optimizationof Large-Scale Ozone Generators IEEE Transactions onPlasma Science Vol 37 No 6 p 890-896 (2009)

ConclusionsConclusionsConclusionsConclusionsFundamentals of ozone synthesis in a DBD plasmay p

ndash Highly filamented DBD discharges are best-suitedfor the production of ozone concentrations in therange of 6 to 14 wtrange of 6 to 14 wt

ndash The preferred characteristic of the microdischargesare Townsend-like at reduced electric fields Enaround 190 Townsend

ndash Detrimental side-effects induced by by-productscan be avoided by a proper design of the electrodecan be avoided by a proper design of the electrodearrangement The phenomenon is related to thediffusion rates of formed by-product clusters

ConclusionsConclusionsConclusionsConclusionsBenefits from DBD microplasma tailoring

ndash Reduced power consumption of up to 10 improvement

ndash Increased ozone concentrations of up to 14 now achievable

ndash Improved neutralization and conditioning of detrimental by-products

ndash Reduced system capital and operational cost

New technologies to improve ozone p

generatorg

HV Pulsed Power SwitchingHV Pulsed Power Switching

Microchannel Generation of Ozone

Channel ArrayChannel Array

Microchannel

330 microm 230 microm

Some Cap-DBD Devices Operating in Air

Increase of 60 of

Spacing 225 μmof 60 of plasma

No space

Cap‐DBD ozone generation

bull Ozone concentration is evaluated via Eco S d l UV 100 O A l (0 01Sensors model UV-100 Ozone Analyzer (001 ndash 900 ppm wiht an accuracy of plusmn2)

bull Three reactors 6 tubings 6rdquo with spacings of 0 μm 225 μm and 500 μm running at 3 kV μ μ μ g

SpacingOzone Concentration

3 kV rms 4 kV rms3 kV rms 4 kV rms

0 μm 660 ppm

225 μm 550 ppm

For a device of such small scale these ozone levels are promising

500 μm 380 ppm

J Mahoney W Zhu VS Johnson KH Becker and JL Lopez Electrical and optical emissionmeasurements of a capillary dielectric barrier discharge European Physics Journal D Vol 60 441-447(2010)

QuestionsQuestions

Thank YouFor more informationProf Jose L Lopez PhD

Thank YouFor more informationDepartment of Physics

Telephone (973) 761-9057Email joselopez1shuedu

Website wwwshueduacademicsartsciphysicsWebsite wwwshueduacademicsartsciphysics

Page 15: Dielectric Barrier Discharge (DBD) & Progress in Large ...bonitz/si12/talks/august_8/lopez_si12.pdf · Dielectric Barrier Discharge (DBD) & Progress in Large-Scale Ozone Generation

High Pressure Microplasmas

Stabilization of high-pressure plasmas ldquopd scalingrdquo ldquoprdquo uarr soplasmas pd scaling p uarr so ldquodrdquo darr to keep breakdown voltage low and minimize instabilities after breakdown -

MicroplasmasDimension a few millimeterDimension a few millimeter down to and below 100 m

Paschen Breakdown CurveH H i 60 100Human Hair 60 ndash 100 m

How do we solve this problemHow do we solve this problem

Transient (pulsed) plasmas In atmospheric plasmas for efficient gas heating atleast 100-1000 collisions are necessary Thus if the plasma duration is shorterleast 100 1000 collisions are necessary Thus if the plasma duration is shorterthan 10-6 ndash 10-5 s gas heating is limited Of course for practical purposes suchplasma has to be operated in a repetitive mode eg in trains of microsecondpulses with millisecond intervals

Micro-confinement Gas heating occurs in the plasma volume and the energy iscarried away by thermal diffusionconvection to the outside If the plasma has asmall volume and a relatively large surface gas heating is limited

Dielectric Barrier Discharges These plasmas are typically created betweenmetal plates which are covered by a thin layer of dielectric or highly resistivematerial The dielectric layer plays an important role in suppressing the currentthe cathodeanode layer is charged by incoming positive ionselectrons whichreduces the electric field and hinders charge transport towards the electrodeDBD also has a large surface-to-volume ratio which promotes diffusion lossesand maintains a low gas temperatureand maintains a low gas temperature

Advantages of Microplasmas Advantages of Microplasmas

bull Low-cost of implementationpbull System flexibilitybull Atmospheric pressure operationbull High densities and high reaction ratesbull High densities and high reaction ratesbull Fast and efficient processesbull Easy to generate and sustain for a variety of gas mixtures

Gl lik d diffbull Glow-like and diffusebull Non-equilibrium (Te gt Tg) to thermalbull Unique chemistryq y

hellip a new realm of plasma sciencehellip a new realm of plasma science

What can we do with microplasmasWhat can we do with microplasmas

Material Synthesis Plasma display Surface Treatment Lighting

OzoneOzone generation for water cleaning

Bio-applicationMaterial processing Dental application

and Many morehellip

Some High Pressure microplasma reactors Some High Pressure microplasma reactors

Dielectric Barrier Discharge (DBD)Dielectric Barrier Discharge (DBD)

Hi h V l

HighVoltage

High VoltageElectrode

ACGenerator

DielectricBarrier

Generator

G

Microplasmas

GroundElectrode

Faradayrsquos Dielectric CapacitorsFaradayrsquos Dielectric Capacitors

Faradays Dielectric Capacitor (circa 1837)

Michael Faraday (1781 ndash 1867) Capacitance INCREASED

Historical Ozone Tube of W Siemens (1857)Historical Ozone Tube of W Siemens (1857)

Werner v SiemensP d frsquo A l d Ch i d Ph ik 102 66 (1857)Poggendorfrsquos Annalen der Chemie und Physik 102 66 (1857)

ldquoOzone Production in an Atmospheric-PressureDielectric Barrier Dischargerdquo

Dielectric Barrier Discharge

Dielectric Barrier DischargeDielectric - Barrier Discharge ConfigurationsHigh

VoltageAC

Generator

High VoltageElectrode

DielectricBarrier

DielectricBarrier

High VoltageElectrode

Discharge

DischargeGeneratorGround

Electrode

Electrode

GroundElectrode

Discharge

H E Wagner R Brandenburg et al lsquoThe barrier discharge basic properties and applications toHE Wagner R Brandenburg et al The barrier discharge basic properties and applications tosurface treatmentrsquo Vacuum 71 p417-436 (2003)

Typical operational conditions of barrier discharges Typical operational conditions of barrier discharges

Electric field strength E of first breakdown asymp150 Td (p = 1bar T=300 K)

Voltage Vpp 3ndash20 kV

Repetition frequency f 50 Hzndash30 kHz

Pressure p 1ndash3 bar

Gap distance g 02ndash5mm

Dielectric material thickness d 05ndash2mm

Relative dielectric permittivity r 5ndash10 (glass)

B Eliasson and U Kogelschatz IEEE Transactions Plasma Science Vol 19 Issue 6 1063-1077 (1991)B Eliasson and U Kogelschatz IEEE Transactions Plasma Science Vol 19 Issue 6 1063-1077 (1991)

Single and double DBD

Single dielectric Double dielectric

Role of the Dielectric (Insulator)

Th di l t i i th k f thThe dielectric is the key for the properfunctioning of the discharge

Serves two functions

1 Limits the amount of charge transportedby a single microplasma

2 Distributes the microplasmas over theentire electrode surface area

Equivalent Circuit of a Microdischarge

Microdischarge Activity and U-Q Lissajous Figure

B Eliasson and U Kogelschatz IEEE Transactions Plasma Science Vol 19 Issue 6 1063-1077 (1991)

Fundamental Operation of the Dielectric Barrier DischargeFundamental Operation of the Dielectric Barrier Discharge

bull Many of relevant plasma processes that areof importance to achieving our goal occuron time scales that allow us to study themon time scales that allow us to study them

bull Optical emission spectroscopic studies willallow us to determine the temporal andspatial development of important plasmaspatial development of important plasmaspecies such as radicals (OH NO variousoxygen radicals) with high time resolution(less than 10 ns) and a spatial resolution onthe scale of mm in the plasma volumepfollowing pulsed plasma excitation

Time scale of the relevant processes of the DBD

HE Wagner R Brandenburg et al lsquoThe barrier discharge basic properties and applications tosurface treatmentrsquo Vacuum 71 417-436 (2003)

Fundamental Operation of the DBDFundamental Operation of the DBD

Electron DensityTemporal Development (ns)

y

Outer Contour Linen = 1010 cm-3ne = 1010 cm 3

Inner Contour Linene = 1014 cm-3

Streamer Propagation in 1 bar AirAA Kulikovsky IEEE Trans Plasma Sci 25 439-446 (1997)

Numerical Results of Microdischarge Formationin Dielectric Barrier Discharges

Starting Phase of a Microdischarge (1 bar 20 CO2 80 H2)

E0=34 kVcm1010 cm-3

1010 cm-3 ne=1012 cm-3

1mm10 cm

ne=108 cm-3

An electron avalanche propagates towards the anode

Reverse propagationtowards the cathodepropagates towards the anode towards the cathode

Numerical Results of Microdischarge Formationin Dielectric Barrier Discharges

Cathode Layer Formation

E0=34 kVcm1010 cm-39 3 0

1mm

1010 cm-3

10 cmne=109 cm-31014

10131014

1013

10 cm1012

Just before the peak of the total current

Peak currentof the total current

Numerical Results of Microdischarge Formationin Dielectric Barrier Discharges

Local Field Collapse in Area Defined by Surface Discharge

ne=109cm-3 ne=1014 cm-3

Gap

Principals of DBD MicroplasmasPrincipals of DBD MicroplasmasPrincipals of DBD MicroplasmasPrincipals of DBD Microplasmas

C C-- - --- - - CG

CD

-- - - CG

CD

Principals of DBD MicroplasmasPrincipals of DBD MicroplasmasPrincipals of DBD MicroplasmasPrincipals of DBD Microplasmas

Dielectric Barrier Discharge (DBD)Dielectric Barrier Discharge (DBD)Electric Field

B kdBreakdown

Electrons amp Ions Discharge Physics

Excited SpeciesPlasma Chemistry

Chemical Reactions

OzoneGeneration

SurfaceTreatment

PollutionControl

ExcimerFormation CO2 Lasers Hydrogenation

of CO2

Excimer Lamps Plasma Displays

How A Plasma Display Works

How A Plasma Display Work

Plasma Display TelevisionsPlasma Display Televisions

Ozone Generator

3 O 2 O

Dielectric Barrier Discharge

3 O2 2 O3

OO22 OO33++OO22Ondash ndashO3O2

O2O2

Ondash ndash

endash O2Ondash ndash O2endash

O3

O3O2O2 O2

HeatHeatHeatHeat

Properties of Ozone (O3)

T i t i f f Tri-atomic form of oxygen

Most powerful commercial oxidizing agent

Unstable - must be generated and used onsite

Limited solubility in water but more so than oxygenLimited solubility in water but more so than oxygen

Leaves a dissolved residual which ultimately converts back to oxygenconverts back to oxygen

Discharge Tubes in Ozone GeneratorsDischarge Tubes in Ozone Generators

Traditional

Ozone Generator

with Glass Tubes

Generation of OzoneGeneration of Ozone

Generation of OzoneAdvantages of Enamel Dielectrics

Proven Patented Designbull Simplicity

Si l Di l i Cbull Single Dielectric Componentndash Reduced number of Dielectrics

bull Safety ndash Lower operating voltage

(lt 4000 V)bull Reliabilty

ndash Fused Dielectrics ensure continuous production

bull Lowest Power Consumption Operational Savingsndash Operational Savings

Modern Ozone GeneratorModern Ozone Generator

Ozonia Advanced Technology Ozone GeneratorOzone Generator

Generation of OzoneGeneration of Ozone

Generation of Ozone

Power Supply UnitPower Supply Unit

IGBT Inverter CircuitMain Circuit Breaker

HV 480 Volts60 Hz3 Phase Supply

C I

450KVAPow er to

GeneratorFILTER

CONVERTER INVERTERTRANSFORMER

C I450KVA Power Stage

CONTACTOR

bull Latest in Power Semiconductor Technology Modular Design

bull Utilizes IGBTrsquos (Insulated Gate Bi‐Polar Transistors) Converter and Inverter Components

Ozone Water Treatment

B bbl Diff iB bbl Diff iBubble DiffusionBubble Diffusion

Easy to use

Low energy usage Low energy usage

Mass transfer efficiencies to gt 90

Ozone Process Flow DiagramOzone Process Flow DiagramVent to

Atmosphere

O OOxygen

Off-Gas Blower

Ozone Destruct Unit

10 12

O3O2

LOX

10-12 O3

Ozone Generators

Ozone Contact ChamberLOX T k Generators Chamber

VaporizersLOX Tank

Municipal Ozone Installations

Ozonia Installations Ozone Plant Size [lbday] Start-Up DateKey Ozonia Installations (Partial List)

Los Angeles CA 10000 1986Fairfax VA ndash Corbalis 9000 2003MWD CA ndash Mills 9 000 2003

Ozonia Installations Ozone Plant Size [lbday] Start Up Date

MWD CA Mills 9000 2003Fairfax Co VA ndash Griffith 9000 2004MWD CA ndash Jensen 18750 2005Indianapolis IN ndash Belmont AWT 12000 2007I di li IN 12 000 2007Indianapolis IN ndash Southport AWT 12000 2007MWD CA ndash Diemer 13400 2008MWD CA ndash Weymouth 13400 2009

Ozonia North America - Potable Water SummaryTotal Number of Installations 90Total Installed Production gt 265000 lbsdayTotal Installed Production 265000 lbsday

Revision -B

Ozone Water TreatmentOzone Water Treatment

MWD Mills WTP - California

3 3 000 lbsda of o one3 3 000 lbsda of o one3 x 3000 lbsday of ozone3 x 3000 lbsday of ozone

Ozone Water TreatmentOzone Water TreatmentOzone Ozone -- How it worksHow it works

OxidantOxidant DisinfectantDisinfectant

bullbull Breaks double carbon Breaks double carbon bondsbonds

bullbull Kills by cell lysing or Kills by cell lysing or causing the cell wall tocausing the cell wall tobondsbonds

bullbull Creates OHCreates OHbullbull radicals radicals which break higher carbon which break higher carbon

causing the cell wall to causing the cell wall to rupture rupture

bullbull AttacksAttacks allall bacteriabacteriabondsbondsbullbull Increased temp and pH Increased temp and pH

accelerates Oaccelerates O33

Attacks Attacks allall bacteria bacteria virus cysts and spores virus cysts and spores in varying degreesin varying degreesaccelerates Oaccelerates O33

decomposition to OHdecomposition to OHbullbull

Micro-organism DNA

Capsule AdenineAdenine

Cell wall ThymineThymine

CytosineCytosine

GuanineGuanine

NuclearmaterialCellmembrane

material

Typical Bacterium DNA

Microbial Growth at Various Ozone ConcentrationsConcentrations

Growth likely

Growth possibleGrowth possible

NO GROWTH

0004 0008 0012 0016 0020

Ozone concentration (mgl)Ozone concentration (mgl)

Typical Water Treatment UsageTypical Water Treatment Usage

Application O3 mgl Contact timeUltra Pure Water 005 - 025 sec ndash min

Water bottling 04 ndash 10 5 ndash 10 min

Swimming pools ampspas

01 ndash 075 4 minutes

Potable taste amp odor 15 ndash 50 5 ndash 10 mindisinfection

Microfloculation 10 ndash 30 5 ndash 10 min

Lignin amp tammin 3 0 10 0 10 30 minLignin amp tamminremoval

30 ndash 100 10 ndash 30 min

Municipal wastewater 50 ndash 150+ 15 ndash 30 min

Ozone Water TreatmentOzone Water TreatmentOzone Ozone ndashndash Municipal ApplicationsMunicipal Applications

bullbull Taste and OdorTaste and Odor

bullbull Color RemovalColor Removal

bullbull Disinfection Without Trihalomethanes (THMs)Disinfection Without Trihalomethanes (THMs)

bullbull Improved Filtration Efficiency and FlocculationImproved Filtration Efficiency and Flocculation

bullbull Cryptosporidium DeactivationCryptosporidium Deactivation

bullbull Giardia amp Virus InactivationGiardia amp Virus Inactivation

bullbull Oxidation Oxidation -- Organics Fe amp MnOrganics Fe amp Mn

bullbull Wastewater disinfectionWastewater disinfection

bullbull BOD COD and TOC reductionBOD COD and TOC reduction

Applications of Ozone

Wastewater Treatmentbull Disinfection of Secondary and Tertiary Effluentsbull Color Reductionbull Color Reductionbull TOC Oxidation (Industrial)bull Oxidation of Odor Causing Compoundsbull Oxidation of Endocrine Disruptors (EDCrsquos) and p ( )

Pharmaceutically Active Compounds (PACrsquos)

Applications of Ozone

What are Endocrine Disruptors (EDCrsquos) and What are Endocrine Disruptors (EDCrsquos) and Ph ti ll A ti C d (PACrsquo )Ph ti ll A ti C d (PACrsquo )Pharmaceutically Active Compounds (PACrsquos)Pharmaceutically Active Compounds (PACrsquos)

bullbull EDCrsquosEDCrsquos andand PACrsquosPACrsquos areare NaturallyNaturally andand SyntheticSyntheticdd th tth t ff tff t thth b lb l llcompoundscompounds thatthat maymay affectaffect thethe balancebalance oror normalnormal

functionsfunctions inin animalsanimals andand humanshumans

What can EDCrsquos and PACrsquos doWhat can EDCrsquos and PACrsquos do

bullbull Even in very small concentrations these compounds Even in very small concentrations these compounds y py pcan can disruptdisrupt normal bodily functionsnormal bodily functions

bullbull ManMan--made chemicals can trick the bodies endocrine made chemicals can trick the bodies endocrine system system

Applications of Ozone

Examples of Endocrine Disruptors1000rsquos of compounds that may be Investigated as EDCs ndash Some examples are

bullbull Synthetic HormonesSynthetic Hormonesbullbull Naturally Occurring Estrogens Naturally Occurring Estrogens

Health and Beauty AidsHealth and Beauty Aidsbullbull Health and Beauty AidsHealth and Beauty Aidsbullbull SolventsSolventsbullbull PesticidesPesticidesbullbull SurfactantsSurfactantsbullbull PlasticsPlastics

F i idF i idbullbull FungicidesFungicides

Ozone Water TreatmentOzone Water Treatment

Ozone Ozone -- Industrial ApplicationsIndustrial Applications-- Ultrapure Water for Pharmaceutical ApplicationsUltrapure Water for Pharmaceutical Applications

-- Wastewater disinfection color removalWastewater disinfection color removal

-- Soil and Groundwater Remediation Soil and Groundwater Remediation

-- Cooling Tower Water TreatmentCooling Tower Water Treatment

-- Food ProcessingFood Processing

-- Aquaculture AquariumsAquaculture AquariumsAquaculture AquariumsAquaculture Aquariums

-- Beverage ApplicationsBeverage Applications

P l amp P Bl hiP l amp P Bl hi-- Pulp amp Paper BleachingPulp amp Paper Bleaching

High Purity OzonationHigh Purity Ozonation

Microchip manufacturingMicrochip manufacturing

What are the current issues in large-scale gozone generationg

Experimental Setup

Front view of the two units after the redesign and reworking ofthe gas water and instruments connectionsthe gas water and instruments connections

Experimental Setup

Top view of the twoexperimental unitsexperimental unitsSpectroscope (notshown) is to the left ofthe DBD The units weredifferent with respect todifferent with respect totheir electrodes onehad only the electrodecoated with thedielectric (ldquosingle-dielectric ( single-coatedrdquo) the other onehad the electrode andthe anode coated withthe dielectric (ldquodouble-the dielectric ( double-coatedrdquo)

Basics Generation of OzoneBasics Generation of Ozone

SpectroscopyPlasma

Plasma Absorption SpectroscopyPlasma Absorption Spectroscopy

Infrared Absorption SpectroscopyInfrared Absorption Spectroscopy

IR spectra in pure oxygen (black curve) and at approximately 10wt N2 admixture (red line) N2O5 peaks appear at124 1 d 1 2 11245 cm-1 and at 1725 cm-1

Infrared Absorption SpectroscopyInfrared Absorption Spectroscopy

IR spectra of several methane variations The green curve envelopes all of the methane peaks at 1325 cm-1recorded at smaller methane admixtures Simultaneously the N2O5 peaks disappear as the methane peaks appear

N2O5 FormationN2O5 Formation2 52 5p=2 bara cwt=20degC q=35kWm2 f=1450Hz

45N2O5 AT95

30

35

40

N

2 B

lend

ing

N2O AT95N2O5 IGSN2O IGSN2O5 LGN2O LG

1 5

20

25

nt [p

pmV]

3

wt

05

10

15

NO

x co

nten

005 7 9 11 13 15 17

ozone conc [wt]

Amount of formed N2O5 and N2O as a function of ozone concentration at 3 wt of nitrogen admixture and fori l dvarious electrode arrangements

Plasma Emission SpectroscopyPlasma Emission Spectroscopyp pyp py

Relative Emissions of the Ozonizer plasmaRelative Emissions of the Ozonizer plasma

Region 300- 850 nm from individual (calibrated) regions (smoothed by PeakFit) Single-coated ozone generator Inlet side

3 5E+06

30E+06

35E+06

7 9

20E+06

25E+06

nten

sity

au

2

311 12

10E+06

15E+06

In 4

5

6 8 10

14

15

16

17

00E+00

50E+05

280 300 320 340 360 380 400 420 440 460 480 500 520 540 560 580 600 620 640 660 680 700 720 740 760 780 800 820 840 860

Wavelength nm

1 13

Wavelength nm

Absolute Emission of the DBD PlasmaAbsolute Emission of the DBD Plasma

Intensities in (O2+3 wtN2) plasma

1 20E+04

100E+04

120E+04

600E+03

800E+03

nten

sity

(au

)

200E+03

400E+03

In

O(777)

000E+00200 250 300 350 400 450 500 550 600 650 700 750 800 850

Wavelength nm

Intensities in 3 wtN2+O2 plasmaIntensities in 3 wtN2+O2 plasma

Plasma Chemistry in OzonizersPlasma Chemistry in Ozonizers

Dry Air O2 N2

e - e -

O N2 N O2

O3 NO

O2 N O2

O3

N

3

NO2

O2 O3

NO

N

NO2 O3

N2O

NO3 N

N2O4

NO2

NO2

N2O5

NO3

Primary electron-driven chemical reactions leading to the formation of N2O5 and N2O in a dry air plasma

Plasma emission diagnostics role of N2Plasma emission diagnostics role of N2

Dry Air O2 N2

e - e -

O N2 N O2

O3 NO

O2 N O2

O3

O

N

ON

NO2

O2O3

N

NO N

NO2 O3

N2O

NO3 N

N2O4

NO2

NO2

N2O5

NO3

ONbullWith N2 present ndash less oxygen atoms are formed However the difference in intensity is

very small

Modeling of plasma chemistry incl the NxOy chemistry up to N2O5 for different Oxygen Nitrogen mixtures varying power deposition scenarios

and initial ozone background concentrations (up to 15) previously done

The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation

The role of N2 must be related to its by-products reacting on the surface of the electrodeThe role of N2 must be related to its by-products reacting on the surface of the electrode

The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established

Ab 8 t f O

The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established

Ab 8 t f OAbove 8 wt of O3

1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)

Above 8 wt of O3

1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)case without pampp)

2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of the

case without pampp)

2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of thethem A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface

them A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface

The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation

Three possibilities have to be considered for the oxygen-fedozone generator

Three possibilities have to be considered for the oxygen-fedozone generatorozone generator

bull Excited N2 molecules lead to an increased O2 dissociation in

ozone generator

bull Excited N2 molecules lead to an increased O2 dissociation in2 2such case an increased efficiency is correlated to the N2admixture

2 2such case an increased efficiency is correlated to the N2admixture

bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial

bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial

bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2

bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2g p g 3 pp y 2g p g 3 pp y 2

Effect of methane on ozone efficiency and specific powerEffect of methane on ozone efficiency and specific power

Effect of Methane on Ozone Content in Outlet Gas and on Specific Power Pure O2

13 12

10

11

12

t 8

10

8

9

10

ne c

onte

nt w

t

6

8

ecifi

c po

wer

kW

hlb

5

6

7

Ozo

n

2

4 Spe

400E+00 20E+03 40E+03 60E+03 80E+03 10E+04 12E+04

Methane in feedgas ppm

0

Ozone content in the outlet gas Specif ic pow er of the ozone generatorg p p g

Effects of N2 and CH4Effects of N2 and CH4

Pi t f h t lli N O t tPicture of an amorphous-crystalline N2O5 structurecaptured at the Orlando Skylake water plant in 2006

Plasma Chemistry with CH4 Impurities

OxygenO2 N2

e - e -

CHO N2

NO2

O NO

O2 N O2 O3

NOH

CH4e-

O3 NO

NO2

O2O3NO N

NO2 O

NO2

NO2

N2ONO3

N

O3

NO2

NO

HNO3

N2O4

N2O5

NO2

NO3

N2O5

Effect of methane on the electrode surfaces

a) b)

Inlet Outlet Outlet

) d)

I l t I l t

c) d)

Electrode of the ozone generator afterseveral hours in CH8O2 and up to 2 wt of methane (a b c)

Inlet Inlet

three hours in CH8O2+traces of N2 and up to 1 wt of methane (d) Visible change of discharge character at about 13 length of electrode (a d)

Kinetics of CHx Conversion without N2

conversion by collisions

O2 + CHx 12wt O3 + CO2 +H2O

deposition vaporizationby sputtering

ibl b l 1000 CHreversible process below 1000ppm CH4

Effect of water on electrode surface with N2

Inlet

OutletOutlet

Electrode of the ozone generator after several hours in H OO N

Inlet

Electrode of the ozone generator after several hours in H2OO2N2

Effect of water on electrode surface

Long term effect (800 hrs) of H2OO2N2

Kinetics of CHx Conversion with N2

conversion by collisionsHNO3 formation

O2 + N2 +CHx 12wtO2 + CO2 +H2O + HNO3

deposition vaporizationby sputtering

H2O + HNO3

by sputtering

irreversible process above a N2 threshold () ltlt 1000ppm N2

sticky deposit

p 2 ( ) pp 2 any CH4 concentration (60ppm)

Plasma Chemistry with CH4 ImpuritiesPlasma Chemistry with CH4 Impurities4

bull Formation of NO and NO2 depends on O3 N2 and gas temperature Conclusion N2 admixture is the key factor

SummarySummaryyyThe mechanisms of formed NOx by-products follows the sameThe mechanisms of formed NOx by-products follows the sameprinciples as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentration

principles as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentrationozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)

ozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)g p ( g p )

The conversion of methane to OH and H2O is found to depend on

g p ( g p )

The conversion of methane to OH and H2O is found to depend ondissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)

dissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)discharge gap)discharge gap)

How do you optimize an ozone generatorg

Scientific ApproachScientific ApproachTheoretical Experimental

pppp

c [wt]

f [Hz]

c [wt]

f [Hz]

[kW]UUUβ1

1Cf4αPn

1iiminpeakimin

iiD

q [kWm2]q [kWm2]

150

180

][V]voltagepeakUpeak

[]cylinder perslicesofamountnsliceii

whereth

09 00

30

60

90

120

effic

ienc

y [

][0tdj t bl[F]sliceisdielectricofecapacitancC

[Hz]frequencyf[V]sliceivoltageminimumiUmin

thiD

th

10

28

46

64

82

39

107

176

244 power density

[kWm2]

ozone conc [wt][]CCβ

][0parameteradjustableα

iDiGi

Impact of Power Inductionp

350

400

wer

200

250

300

App

lied

Pow

Arr C 2Arr D +0

Arr E +45Arr F +7

Arr G +3

5 0

100

150

Frac

tion

of

1 2 3 4

ReferenceArr B unstable

Arr C -2

00

50

4Position (1inlet 4outlet)

Experimental Test Rigp g

Experimental Test Rigp g

Outer grounded electrode (left picture) and the dielectric covered inner electrodes (right) d e ect c cove ed e e ect odes ( g t)

Reference (Traditional) Arrangement

Inlet OutletGas flow direction

Optimized Arrangement

Inlet OutletGas flow direction

Intelligent Gap System (IGS)g p y ( )

Molecular Oxygen (O2) Ozone (O3)

O2 O3

yg ( 2) ( 3)

Particle Size SynthesisParticle Size SynthesisByBy--Products Cluster FormationProducts Cluster Formationyy

high diffusion and deposition to surfaces

low diffusion rate good transport

high sedimentation on the structurehigh sedimentation on the structure

Degreacutemont Technologies ndash OzoniaIntelligent Gap SystemIntelligent Gap System

G Vezzuacute JL Lopez A Freilich and K Becker Optimizationof Large-Scale Ozone Generators IEEE Transactions onPlasma Science Vol 37 No 6 p 890-896 (2009)

ConclusionsConclusionsConclusionsConclusionsFundamentals of ozone synthesis in a DBD plasmay p

ndash Highly filamented DBD discharges are best-suitedfor the production of ozone concentrations in therange of 6 to 14 wtrange of 6 to 14 wt

ndash The preferred characteristic of the microdischargesare Townsend-like at reduced electric fields Enaround 190 Townsend

ndash Detrimental side-effects induced by by-productscan be avoided by a proper design of the electrodecan be avoided by a proper design of the electrodearrangement The phenomenon is related to thediffusion rates of formed by-product clusters

ConclusionsConclusionsConclusionsConclusionsBenefits from DBD microplasma tailoring

ndash Reduced power consumption of up to 10 improvement

ndash Increased ozone concentrations of up to 14 now achievable

ndash Improved neutralization and conditioning of detrimental by-products

ndash Reduced system capital and operational cost

New technologies to improve ozone p

generatorg

HV Pulsed Power SwitchingHV Pulsed Power Switching

Microchannel Generation of Ozone

Channel ArrayChannel Array

Microchannel

330 microm 230 microm

Some Cap-DBD Devices Operating in Air

Increase of 60 of

Spacing 225 μmof 60 of plasma

No space

Cap‐DBD ozone generation

bull Ozone concentration is evaluated via Eco S d l UV 100 O A l (0 01Sensors model UV-100 Ozone Analyzer (001 ndash 900 ppm wiht an accuracy of plusmn2)

bull Three reactors 6 tubings 6rdquo with spacings of 0 μm 225 μm and 500 μm running at 3 kV μ μ μ g

SpacingOzone Concentration

3 kV rms 4 kV rms3 kV rms 4 kV rms

0 μm 660 ppm

225 μm 550 ppm

For a device of such small scale these ozone levels are promising

500 μm 380 ppm

J Mahoney W Zhu VS Johnson KH Becker and JL Lopez Electrical and optical emissionmeasurements of a capillary dielectric barrier discharge European Physics Journal D Vol 60 441-447(2010)

QuestionsQuestions

Thank YouFor more informationProf Jose L Lopez PhD

Thank YouFor more informationDepartment of Physics

Telephone (973) 761-9057Email joselopez1shuedu

Website wwwshueduacademicsartsciphysicsWebsite wwwshueduacademicsartsciphysics

Page 16: Dielectric Barrier Discharge (DBD) & Progress in Large ...bonitz/si12/talks/august_8/lopez_si12.pdf · Dielectric Barrier Discharge (DBD) & Progress in Large-Scale Ozone Generation

How do we solve this problemHow do we solve this problem

Transient (pulsed) plasmas In atmospheric plasmas for efficient gas heating atleast 100-1000 collisions are necessary Thus if the plasma duration is shorterleast 100 1000 collisions are necessary Thus if the plasma duration is shorterthan 10-6 ndash 10-5 s gas heating is limited Of course for practical purposes suchplasma has to be operated in a repetitive mode eg in trains of microsecondpulses with millisecond intervals

Micro-confinement Gas heating occurs in the plasma volume and the energy iscarried away by thermal diffusionconvection to the outside If the plasma has asmall volume and a relatively large surface gas heating is limited

Dielectric Barrier Discharges These plasmas are typically created betweenmetal plates which are covered by a thin layer of dielectric or highly resistivematerial The dielectric layer plays an important role in suppressing the currentthe cathodeanode layer is charged by incoming positive ionselectrons whichreduces the electric field and hinders charge transport towards the electrodeDBD also has a large surface-to-volume ratio which promotes diffusion lossesand maintains a low gas temperatureand maintains a low gas temperature

Advantages of Microplasmas Advantages of Microplasmas

bull Low-cost of implementationpbull System flexibilitybull Atmospheric pressure operationbull High densities and high reaction ratesbull High densities and high reaction ratesbull Fast and efficient processesbull Easy to generate and sustain for a variety of gas mixtures

Gl lik d diffbull Glow-like and diffusebull Non-equilibrium (Te gt Tg) to thermalbull Unique chemistryq y

hellip a new realm of plasma sciencehellip a new realm of plasma science

What can we do with microplasmasWhat can we do with microplasmas

Material Synthesis Plasma display Surface Treatment Lighting

OzoneOzone generation for water cleaning

Bio-applicationMaterial processing Dental application

and Many morehellip

Some High Pressure microplasma reactors Some High Pressure microplasma reactors

Dielectric Barrier Discharge (DBD)Dielectric Barrier Discharge (DBD)

Hi h V l

HighVoltage

High VoltageElectrode

ACGenerator

DielectricBarrier

Generator

G

Microplasmas

GroundElectrode

Faradayrsquos Dielectric CapacitorsFaradayrsquos Dielectric Capacitors

Faradays Dielectric Capacitor (circa 1837)

Michael Faraday (1781 ndash 1867) Capacitance INCREASED

Historical Ozone Tube of W Siemens (1857)Historical Ozone Tube of W Siemens (1857)

Werner v SiemensP d frsquo A l d Ch i d Ph ik 102 66 (1857)Poggendorfrsquos Annalen der Chemie und Physik 102 66 (1857)

ldquoOzone Production in an Atmospheric-PressureDielectric Barrier Dischargerdquo

Dielectric Barrier Discharge

Dielectric Barrier DischargeDielectric - Barrier Discharge ConfigurationsHigh

VoltageAC

Generator

High VoltageElectrode

DielectricBarrier

DielectricBarrier

High VoltageElectrode

Discharge

DischargeGeneratorGround

Electrode

Electrode

GroundElectrode

Discharge

H E Wagner R Brandenburg et al lsquoThe barrier discharge basic properties and applications toHE Wagner R Brandenburg et al The barrier discharge basic properties and applications tosurface treatmentrsquo Vacuum 71 p417-436 (2003)

Typical operational conditions of barrier discharges Typical operational conditions of barrier discharges

Electric field strength E of first breakdown asymp150 Td (p = 1bar T=300 K)

Voltage Vpp 3ndash20 kV

Repetition frequency f 50 Hzndash30 kHz

Pressure p 1ndash3 bar

Gap distance g 02ndash5mm

Dielectric material thickness d 05ndash2mm

Relative dielectric permittivity r 5ndash10 (glass)

B Eliasson and U Kogelschatz IEEE Transactions Plasma Science Vol 19 Issue 6 1063-1077 (1991)B Eliasson and U Kogelschatz IEEE Transactions Plasma Science Vol 19 Issue 6 1063-1077 (1991)

Single and double DBD

Single dielectric Double dielectric

Role of the Dielectric (Insulator)

Th di l t i i th k f thThe dielectric is the key for the properfunctioning of the discharge

Serves two functions

1 Limits the amount of charge transportedby a single microplasma

2 Distributes the microplasmas over theentire electrode surface area

Equivalent Circuit of a Microdischarge

Microdischarge Activity and U-Q Lissajous Figure

B Eliasson and U Kogelschatz IEEE Transactions Plasma Science Vol 19 Issue 6 1063-1077 (1991)

Fundamental Operation of the Dielectric Barrier DischargeFundamental Operation of the Dielectric Barrier Discharge

bull Many of relevant plasma processes that areof importance to achieving our goal occuron time scales that allow us to study themon time scales that allow us to study them

bull Optical emission spectroscopic studies willallow us to determine the temporal andspatial development of important plasmaspatial development of important plasmaspecies such as radicals (OH NO variousoxygen radicals) with high time resolution(less than 10 ns) and a spatial resolution onthe scale of mm in the plasma volumepfollowing pulsed plasma excitation

Time scale of the relevant processes of the DBD

HE Wagner R Brandenburg et al lsquoThe barrier discharge basic properties and applications tosurface treatmentrsquo Vacuum 71 417-436 (2003)

Fundamental Operation of the DBDFundamental Operation of the DBD

Electron DensityTemporal Development (ns)

y

Outer Contour Linen = 1010 cm-3ne = 1010 cm 3

Inner Contour Linene = 1014 cm-3

Streamer Propagation in 1 bar AirAA Kulikovsky IEEE Trans Plasma Sci 25 439-446 (1997)

Numerical Results of Microdischarge Formationin Dielectric Barrier Discharges

Starting Phase of a Microdischarge (1 bar 20 CO2 80 H2)

E0=34 kVcm1010 cm-3

1010 cm-3 ne=1012 cm-3

1mm10 cm

ne=108 cm-3

An electron avalanche propagates towards the anode

Reverse propagationtowards the cathodepropagates towards the anode towards the cathode

Numerical Results of Microdischarge Formationin Dielectric Barrier Discharges

Cathode Layer Formation

E0=34 kVcm1010 cm-39 3 0

1mm

1010 cm-3

10 cmne=109 cm-31014

10131014

1013

10 cm1012

Just before the peak of the total current

Peak currentof the total current

Numerical Results of Microdischarge Formationin Dielectric Barrier Discharges

Local Field Collapse in Area Defined by Surface Discharge

ne=109cm-3 ne=1014 cm-3

Gap

Principals of DBD MicroplasmasPrincipals of DBD MicroplasmasPrincipals of DBD MicroplasmasPrincipals of DBD Microplasmas

C C-- - --- - - CG

CD

-- - - CG

CD

Principals of DBD MicroplasmasPrincipals of DBD MicroplasmasPrincipals of DBD MicroplasmasPrincipals of DBD Microplasmas

Dielectric Barrier Discharge (DBD)Dielectric Barrier Discharge (DBD)Electric Field

B kdBreakdown

Electrons amp Ions Discharge Physics

Excited SpeciesPlasma Chemistry

Chemical Reactions

OzoneGeneration

SurfaceTreatment

PollutionControl

ExcimerFormation CO2 Lasers Hydrogenation

of CO2

Excimer Lamps Plasma Displays

How A Plasma Display Works

How A Plasma Display Work

Plasma Display TelevisionsPlasma Display Televisions

Ozone Generator

3 O 2 O

Dielectric Barrier Discharge

3 O2 2 O3

OO22 OO33++OO22Ondash ndashO3O2

O2O2

Ondash ndash

endash O2Ondash ndash O2endash

O3

O3O2O2 O2

HeatHeatHeatHeat

Properties of Ozone (O3)

T i t i f f Tri-atomic form of oxygen

Most powerful commercial oxidizing agent

Unstable - must be generated and used onsite

Limited solubility in water but more so than oxygenLimited solubility in water but more so than oxygen

Leaves a dissolved residual which ultimately converts back to oxygenconverts back to oxygen

Discharge Tubes in Ozone GeneratorsDischarge Tubes in Ozone Generators

Traditional

Ozone Generator

with Glass Tubes

Generation of OzoneGeneration of Ozone

Generation of OzoneAdvantages of Enamel Dielectrics

Proven Patented Designbull Simplicity

Si l Di l i Cbull Single Dielectric Componentndash Reduced number of Dielectrics

bull Safety ndash Lower operating voltage

(lt 4000 V)bull Reliabilty

ndash Fused Dielectrics ensure continuous production

bull Lowest Power Consumption Operational Savingsndash Operational Savings

Modern Ozone GeneratorModern Ozone Generator

Ozonia Advanced Technology Ozone GeneratorOzone Generator

Generation of OzoneGeneration of Ozone

Generation of Ozone

Power Supply UnitPower Supply Unit

IGBT Inverter CircuitMain Circuit Breaker

HV 480 Volts60 Hz3 Phase Supply

C I

450KVAPow er to

GeneratorFILTER

CONVERTER INVERTERTRANSFORMER

C I450KVA Power Stage

CONTACTOR

bull Latest in Power Semiconductor Technology Modular Design

bull Utilizes IGBTrsquos (Insulated Gate Bi‐Polar Transistors) Converter and Inverter Components

Ozone Water Treatment

B bbl Diff iB bbl Diff iBubble DiffusionBubble Diffusion

Easy to use

Low energy usage Low energy usage

Mass transfer efficiencies to gt 90

Ozone Process Flow DiagramOzone Process Flow DiagramVent to

Atmosphere

O OOxygen

Off-Gas Blower

Ozone Destruct Unit

10 12

O3O2

LOX

10-12 O3

Ozone Generators

Ozone Contact ChamberLOX T k Generators Chamber

VaporizersLOX Tank

Municipal Ozone Installations

Ozonia Installations Ozone Plant Size [lbday] Start-Up DateKey Ozonia Installations (Partial List)

Los Angeles CA 10000 1986Fairfax VA ndash Corbalis 9000 2003MWD CA ndash Mills 9 000 2003

Ozonia Installations Ozone Plant Size [lbday] Start Up Date

MWD CA Mills 9000 2003Fairfax Co VA ndash Griffith 9000 2004MWD CA ndash Jensen 18750 2005Indianapolis IN ndash Belmont AWT 12000 2007I di li IN 12 000 2007Indianapolis IN ndash Southport AWT 12000 2007MWD CA ndash Diemer 13400 2008MWD CA ndash Weymouth 13400 2009

Ozonia North America - Potable Water SummaryTotal Number of Installations 90Total Installed Production gt 265000 lbsdayTotal Installed Production 265000 lbsday

Revision -B

Ozone Water TreatmentOzone Water Treatment

MWD Mills WTP - California

3 3 000 lbsda of o one3 3 000 lbsda of o one3 x 3000 lbsday of ozone3 x 3000 lbsday of ozone

Ozone Water TreatmentOzone Water TreatmentOzone Ozone -- How it worksHow it works

OxidantOxidant DisinfectantDisinfectant

bullbull Breaks double carbon Breaks double carbon bondsbonds

bullbull Kills by cell lysing or Kills by cell lysing or causing the cell wall tocausing the cell wall tobondsbonds

bullbull Creates OHCreates OHbullbull radicals radicals which break higher carbon which break higher carbon

causing the cell wall to causing the cell wall to rupture rupture

bullbull AttacksAttacks allall bacteriabacteriabondsbondsbullbull Increased temp and pH Increased temp and pH

accelerates Oaccelerates O33

Attacks Attacks allall bacteria bacteria virus cysts and spores virus cysts and spores in varying degreesin varying degreesaccelerates Oaccelerates O33

decomposition to OHdecomposition to OHbullbull

Micro-organism DNA

Capsule AdenineAdenine

Cell wall ThymineThymine

CytosineCytosine

GuanineGuanine

NuclearmaterialCellmembrane

material

Typical Bacterium DNA

Microbial Growth at Various Ozone ConcentrationsConcentrations

Growth likely

Growth possibleGrowth possible

NO GROWTH

0004 0008 0012 0016 0020

Ozone concentration (mgl)Ozone concentration (mgl)

Typical Water Treatment UsageTypical Water Treatment Usage

Application O3 mgl Contact timeUltra Pure Water 005 - 025 sec ndash min

Water bottling 04 ndash 10 5 ndash 10 min

Swimming pools ampspas

01 ndash 075 4 minutes

Potable taste amp odor 15 ndash 50 5 ndash 10 mindisinfection

Microfloculation 10 ndash 30 5 ndash 10 min

Lignin amp tammin 3 0 10 0 10 30 minLignin amp tamminremoval

30 ndash 100 10 ndash 30 min

Municipal wastewater 50 ndash 150+ 15 ndash 30 min

Ozone Water TreatmentOzone Water TreatmentOzone Ozone ndashndash Municipal ApplicationsMunicipal Applications

bullbull Taste and OdorTaste and Odor

bullbull Color RemovalColor Removal

bullbull Disinfection Without Trihalomethanes (THMs)Disinfection Without Trihalomethanes (THMs)

bullbull Improved Filtration Efficiency and FlocculationImproved Filtration Efficiency and Flocculation

bullbull Cryptosporidium DeactivationCryptosporidium Deactivation

bullbull Giardia amp Virus InactivationGiardia amp Virus Inactivation

bullbull Oxidation Oxidation -- Organics Fe amp MnOrganics Fe amp Mn

bullbull Wastewater disinfectionWastewater disinfection

bullbull BOD COD and TOC reductionBOD COD and TOC reduction

Applications of Ozone

Wastewater Treatmentbull Disinfection of Secondary and Tertiary Effluentsbull Color Reductionbull Color Reductionbull TOC Oxidation (Industrial)bull Oxidation of Odor Causing Compoundsbull Oxidation of Endocrine Disruptors (EDCrsquos) and p ( )

Pharmaceutically Active Compounds (PACrsquos)

Applications of Ozone

What are Endocrine Disruptors (EDCrsquos) and What are Endocrine Disruptors (EDCrsquos) and Ph ti ll A ti C d (PACrsquo )Ph ti ll A ti C d (PACrsquo )Pharmaceutically Active Compounds (PACrsquos)Pharmaceutically Active Compounds (PACrsquos)

bullbull EDCrsquosEDCrsquos andand PACrsquosPACrsquos areare NaturallyNaturally andand SyntheticSyntheticdd th tth t ff tff t thth b lb l llcompoundscompounds thatthat maymay affectaffect thethe balancebalance oror normalnormal

functionsfunctions inin animalsanimals andand humanshumans

What can EDCrsquos and PACrsquos doWhat can EDCrsquos and PACrsquos do

bullbull Even in very small concentrations these compounds Even in very small concentrations these compounds y py pcan can disruptdisrupt normal bodily functionsnormal bodily functions

bullbull ManMan--made chemicals can trick the bodies endocrine made chemicals can trick the bodies endocrine system system

Applications of Ozone

Examples of Endocrine Disruptors1000rsquos of compounds that may be Investigated as EDCs ndash Some examples are

bullbull Synthetic HormonesSynthetic Hormonesbullbull Naturally Occurring Estrogens Naturally Occurring Estrogens

Health and Beauty AidsHealth and Beauty Aidsbullbull Health and Beauty AidsHealth and Beauty Aidsbullbull SolventsSolventsbullbull PesticidesPesticidesbullbull SurfactantsSurfactantsbullbull PlasticsPlastics

F i idF i idbullbull FungicidesFungicides

Ozone Water TreatmentOzone Water Treatment

Ozone Ozone -- Industrial ApplicationsIndustrial Applications-- Ultrapure Water for Pharmaceutical ApplicationsUltrapure Water for Pharmaceutical Applications

-- Wastewater disinfection color removalWastewater disinfection color removal

-- Soil and Groundwater Remediation Soil and Groundwater Remediation

-- Cooling Tower Water TreatmentCooling Tower Water Treatment

-- Food ProcessingFood Processing

-- Aquaculture AquariumsAquaculture AquariumsAquaculture AquariumsAquaculture Aquariums

-- Beverage ApplicationsBeverage Applications

P l amp P Bl hiP l amp P Bl hi-- Pulp amp Paper BleachingPulp amp Paper Bleaching

High Purity OzonationHigh Purity Ozonation

Microchip manufacturingMicrochip manufacturing

What are the current issues in large-scale gozone generationg

Experimental Setup

Front view of the two units after the redesign and reworking ofthe gas water and instruments connectionsthe gas water and instruments connections

Experimental Setup

Top view of the twoexperimental unitsexperimental unitsSpectroscope (notshown) is to the left ofthe DBD The units weredifferent with respect todifferent with respect totheir electrodes onehad only the electrodecoated with thedielectric (ldquosingle-dielectric ( single-coatedrdquo) the other onehad the electrode andthe anode coated withthe dielectric (ldquodouble-the dielectric ( double-coatedrdquo)

Basics Generation of OzoneBasics Generation of Ozone

SpectroscopyPlasma

Plasma Absorption SpectroscopyPlasma Absorption Spectroscopy

Infrared Absorption SpectroscopyInfrared Absorption Spectroscopy

IR spectra in pure oxygen (black curve) and at approximately 10wt N2 admixture (red line) N2O5 peaks appear at124 1 d 1 2 11245 cm-1 and at 1725 cm-1

Infrared Absorption SpectroscopyInfrared Absorption Spectroscopy

IR spectra of several methane variations The green curve envelopes all of the methane peaks at 1325 cm-1recorded at smaller methane admixtures Simultaneously the N2O5 peaks disappear as the methane peaks appear

N2O5 FormationN2O5 Formation2 52 5p=2 bara cwt=20degC q=35kWm2 f=1450Hz

45N2O5 AT95

30

35

40

N

2 B

lend

ing

N2O AT95N2O5 IGSN2O IGSN2O5 LGN2O LG

1 5

20

25

nt [p

pmV]

3

wt

05

10

15

NO

x co

nten

005 7 9 11 13 15 17

ozone conc [wt]

Amount of formed N2O5 and N2O as a function of ozone concentration at 3 wt of nitrogen admixture and fori l dvarious electrode arrangements

Plasma Emission SpectroscopyPlasma Emission Spectroscopyp pyp py

Relative Emissions of the Ozonizer plasmaRelative Emissions of the Ozonizer plasma

Region 300- 850 nm from individual (calibrated) regions (smoothed by PeakFit) Single-coated ozone generator Inlet side

3 5E+06

30E+06

35E+06

7 9

20E+06

25E+06

nten

sity

au

2

311 12

10E+06

15E+06

In 4

5

6 8 10

14

15

16

17

00E+00

50E+05

280 300 320 340 360 380 400 420 440 460 480 500 520 540 560 580 600 620 640 660 680 700 720 740 760 780 800 820 840 860

Wavelength nm

1 13

Wavelength nm

Absolute Emission of the DBD PlasmaAbsolute Emission of the DBD Plasma

Intensities in (O2+3 wtN2) plasma

1 20E+04

100E+04

120E+04

600E+03

800E+03

nten

sity

(au

)

200E+03

400E+03

In

O(777)

000E+00200 250 300 350 400 450 500 550 600 650 700 750 800 850

Wavelength nm

Intensities in 3 wtN2+O2 plasmaIntensities in 3 wtN2+O2 plasma

Plasma Chemistry in OzonizersPlasma Chemistry in Ozonizers

Dry Air O2 N2

e - e -

O N2 N O2

O3 NO

O2 N O2

O3

N

3

NO2

O2 O3

NO

N

NO2 O3

N2O

NO3 N

N2O4

NO2

NO2

N2O5

NO3

Primary electron-driven chemical reactions leading to the formation of N2O5 and N2O in a dry air plasma

Plasma emission diagnostics role of N2Plasma emission diagnostics role of N2

Dry Air O2 N2

e - e -

O N2 N O2

O3 NO

O2 N O2

O3

O

N

ON

NO2

O2O3

N

NO N

NO2 O3

N2O

NO3 N

N2O4

NO2

NO2

N2O5

NO3

ONbullWith N2 present ndash less oxygen atoms are formed However the difference in intensity is

very small

Modeling of plasma chemistry incl the NxOy chemistry up to N2O5 for different Oxygen Nitrogen mixtures varying power deposition scenarios

and initial ozone background concentrations (up to 15) previously done

The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation

The role of N2 must be related to its by-products reacting on the surface of the electrodeThe role of N2 must be related to its by-products reacting on the surface of the electrode

The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established

Ab 8 t f O

The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established

Ab 8 t f OAbove 8 wt of O3

1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)

Above 8 wt of O3

1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)case without pampp)

2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of the

case without pampp)

2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of thethem A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface

them A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface

The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation

Three possibilities have to be considered for the oxygen-fedozone generator

Three possibilities have to be considered for the oxygen-fedozone generatorozone generator

bull Excited N2 molecules lead to an increased O2 dissociation in

ozone generator

bull Excited N2 molecules lead to an increased O2 dissociation in2 2such case an increased efficiency is correlated to the N2admixture

2 2such case an increased efficiency is correlated to the N2admixture

bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial

bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial

bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2

bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2g p g 3 pp y 2g p g 3 pp y 2

Effect of methane on ozone efficiency and specific powerEffect of methane on ozone efficiency and specific power

Effect of Methane on Ozone Content in Outlet Gas and on Specific Power Pure O2

13 12

10

11

12

t 8

10

8

9

10

ne c

onte

nt w

t

6

8

ecifi

c po

wer

kW

hlb

5

6

7

Ozo

n

2

4 Spe

400E+00 20E+03 40E+03 60E+03 80E+03 10E+04 12E+04

Methane in feedgas ppm

0

Ozone content in the outlet gas Specif ic pow er of the ozone generatorg p p g

Effects of N2 and CH4Effects of N2 and CH4

Pi t f h t lli N O t tPicture of an amorphous-crystalline N2O5 structurecaptured at the Orlando Skylake water plant in 2006

Plasma Chemistry with CH4 Impurities

OxygenO2 N2

e - e -

CHO N2

NO2

O NO

O2 N O2 O3

NOH

CH4e-

O3 NO

NO2

O2O3NO N

NO2 O

NO2

NO2

N2ONO3

N

O3

NO2

NO

HNO3

N2O4

N2O5

NO2

NO3

N2O5

Effect of methane on the electrode surfaces

a) b)

Inlet Outlet Outlet

) d)

I l t I l t

c) d)

Electrode of the ozone generator afterseveral hours in CH8O2 and up to 2 wt of methane (a b c)

Inlet Inlet

three hours in CH8O2+traces of N2 and up to 1 wt of methane (d) Visible change of discharge character at about 13 length of electrode (a d)

Kinetics of CHx Conversion without N2

conversion by collisions

O2 + CHx 12wt O3 + CO2 +H2O

deposition vaporizationby sputtering

ibl b l 1000 CHreversible process below 1000ppm CH4

Effect of water on electrode surface with N2

Inlet

OutletOutlet

Electrode of the ozone generator after several hours in H OO N

Inlet

Electrode of the ozone generator after several hours in H2OO2N2

Effect of water on electrode surface

Long term effect (800 hrs) of H2OO2N2

Kinetics of CHx Conversion with N2

conversion by collisionsHNO3 formation

O2 + N2 +CHx 12wtO2 + CO2 +H2O + HNO3

deposition vaporizationby sputtering

H2O + HNO3

by sputtering

irreversible process above a N2 threshold () ltlt 1000ppm N2

sticky deposit

p 2 ( ) pp 2 any CH4 concentration (60ppm)

Plasma Chemistry with CH4 ImpuritiesPlasma Chemistry with CH4 Impurities4

bull Formation of NO and NO2 depends on O3 N2 and gas temperature Conclusion N2 admixture is the key factor

SummarySummaryyyThe mechanisms of formed NOx by-products follows the sameThe mechanisms of formed NOx by-products follows the sameprinciples as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentration

principles as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentrationozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)

ozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)g p ( g p )

The conversion of methane to OH and H2O is found to depend on

g p ( g p )

The conversion of methane to OH and H2O is found to depend ondissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)

dissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)discharge gap)discharge gap)

How do you optimize an ozone generatorg

Scientific ApproachScientific ApproachTheoretical Experimental

pppp

c [wt]

f [Hz]

c [wt]

f [Hz]

[kW]UUUβ1

1Cf4αPn

1iiminpeakimin

iiD

q [kWm2]q [kWm2]

150

180

][V]voltagepeakUpeak

[]cylinder perslicesofamountnsliceii

whereth

09 00

30

60

90

120

effic

ienc

y [

][0tdj t bl[F]sliceisdielectricofecapacitancC

[Hz]frequencyf[V]sliceivoltageminimumiUmin

thiD

th

10

28

46

64

82

39

107

176

244 power density

[kWm2]

ozone conc [wt][]CCβ

][0parameteradjustableα

iDiGi

Impact of Power Inductionp

350

400

wer

200

250

300

App

lied

Pow

Arr C 2Arr D +0

Arr E +45Arr F +7

Arr G +3

5 0

100

150

Frac

tion

of

1 2 3 4

ReferenceArr B unstable

Arr C -2

00

50

4Position (1inlet 4outlet)

Experimental Test Rigp g

Experimental Test Rigp g

Outer grounded electrode (left picture) and the dielectric covered inner electrodes (right) d e ect c cove ed e e ect odes ( g t)

Reference (Traditional) Arrangement

Inlet OutletGas flow direction

Optimized Arrangement

Inlet OutletGas flow direction

Intelligent Gap System (IGS)g p y ( )

Molecular Oxygen (O2) Ozone (O3)

O2 O3

yg ( 2) ( 3)

Particle Size SynthesisParticle Size SynthesisByBy--Products Cluster FormationProducts Cluster Formationyy

high diffusion and deposition to surfaces

low diffusion rate good transport

high sedimentation on the structurehigh sedimentation on the structure

Degreacutemont Technologies ndash OzoniaIntelligent Gap SystemIntelligent Gap System

G Vezzuacute JL Lopez A Freilich and K Becker Optimizationof Large-Scale Ozone Generators IEEE Transactions onPlasma Science Vol 37 No 6 p 890-896 (2009)

ConclusionsConclusionsConclusionsConclusionsFundamentals of ozone synthesis in a DBD plasmay p

ndash Highly filamented DBD discharges are best-suitedfor the production of ozone concentrations in therange of 6 to 14 wtrange of 6 to 14 wt

ndash The preferred characteristic of the microdischargesare Townsend-like at reduced electric fields Enaround 190 Townsend

ndash Detrimental side-effects induced by by-productscan be avoided by a proper design of the electrodecan be avoided by a proper design of the electrodearrangement The phenomenon is related to thediffusion rates of formed by-product clusters

ConclusionsConclusionsConclusionsConclusionsBenefits from DBD microplasma tailoring

ndash Reduced power consumption of up to 10 improvement

ndash Increased ozone concentrations of up to 14 now achievable

ndash Improved neutralization and conditioning of detrimental by-products

ndash Reduced system capital and operational cost

New technologies to improve ozone p

generatorg

HV Pulsed Power SwitchingHV Pulsed Power Switching

Microchannel Generation of Ozone

Channel ArrayChannel Array

Microchannel

330 microm 230 microm

Some Cap-DBD Devices Operating in Air

Increase of 60 of

Spacing 225 μmof 60 of plasma

No space

Cap‐DBD ozone generation

bull Ozone concentration is evaluated via Eco S d l UV 100 O A l (0 01Sensors model UV-100 Ozone Analyzer (001 ndash 900 ppm wiht an accuracy of plusmn2)

bull Three reactors 6 tubings 6rdquo with spacings of 0 μm 225 μm and 500 μm running at 3 kV μ μ μ g

SpacingOzone Concentration

3 kV rms 4 kV rms3 kV rms 4 kV rms

0 μm 660 ppm

225 μm 550 ppm

For a device of such small scale these ozone levels are promising

500 μm 380 ppm

J Mahoney W Zhu VS Johnson KH Becker and JL Lopez Electrical and optical emissionmeasurements of a capillary dielectric barrier discharge European Physics Journal D Vol 60 441-447(2010)

QuestionsQuestions

Thank YouFor more informationProf Jose L Lopez PhD

Thank YouFor more informationDepartment of Physics

Telephone (973) 761-9057Email joselopez1shuedu

Website wwwshueduacademicsartsciphysicsWebsite wwwshueduacademicsartsciphysics

Page 17: Dielectric Barrier Discharge (DBD) & Progress in Large ...bonitz/si12/talks/august_8/lopez_si12.pdf · Dielectric Barrier Discharge (DBD) & Progress in Large-Scale Ozone Generation

Advantages of Microplasmas Advantages of Microplasmas

bull Low-cost of implementationpbull System flexibilitybull Atmospheric pressure operationbull High densities and high reaction ratesbull High densities and high reaction ratesbull Fast and efficient processesbull Easy to generate and sustain for a variety of gas mixtures

Gl lik d diffbull Glow-like and diffusebull Non-equilibrium (Te gt Tg) to thermalbull Unique chemistryq y

hellip a new realm of plasma sciencehellip a new realm of plasma science

What can we do with microplasmasWhat can we do with microplasmas

Material Synthesis Plasma display Surface Treatment Lighting

OzoneOzone generation for water cleaning

Bio-applicationMaterial processing Dental application

and Many morehellip

Some High Pressure microplasma reactors Some High Pressure microplasma reactors

Dielectric Barrier Discharge (DBD)Dielectric Barrier Discharge (DBD)

Hi h V l

HighVoltage

High VoltageElectrode

ACGenerator

DielectricBarrier

Generator

G

Microplasmas

GroundElectrode

Faradayrsquos Dielectric CapacitorsFaradayrsquos Dielectric Capacitors

Faradays Dielectric Capacitor (circa 1837)

Michael Faraday (1781 ndash 1867) Capacitance INCREASED

Historical Ozone Tube of W Siemens (1857)Historical Ozone Tube of W Siemens (1857)

Werner v SiemensP d frsquo A l d Ch i d Ph ik 102 66 (1857)Poggendorfrsquos Annalen der Chemie und Physik 102 66 (1857)

ldquoOzone Production in an Atmospheric-PressureDielectric Barrier Dischargerdquo

Dielectric Barrier Discharge

Dielectric Barrier DischargeDielectric - Barrier Discharge ConfigurationsHigh

VoltageAC

Generator

High VoltageElectrode

DielectricBarrier

DielectricBarrier

High VoltageElectrode

Discharge

DischargeGeneratorGround

Electrode

Electrode

GroundElectrode

Discharge

H E Wagner R Brandenburg et al lsquoThe barrier discharge basic properties and applications toHE Wagner R Brandenburg et al The barrier discharge basic properties and applications tosurface treatmentrsquo Vacuum 71 p417-436 (2003)

Typical operational conditions of barrier discharges Typical operational conditions of barrier discharges

Electric field strength E of first breakdown asymp150 Td (p = 1bar T=300 K)

Voltage Vpp 3ndash20 kV

Repetition frequency f 50 Hzndash30 kHz

Pressure p 1ndash3 bar

Gap distance g 02ndash5mm

Dielectric material thickness d 05ndash2mm

Relative dielectric permittivity r 5ndash10 (glass)

B Eliasson and U Kogelschatz IEEE Transactions Plasma Science Vol 19 Issue 6 1063-1077 (1991)B Eliasson and U Kogelschatz IEEE Transactions Plasma Science Vol 19 Issue 6 1063-1077 (1991)

Single and double DBD

Single dielectric Double dielectric

Role of the Dielectric (Insulator)

Th di l t i i th k f thThe dielectric is the key for the properfunctioning of the discharge

Serves two functions

1 Limits the amount of charge transportedby a single microplasma

2 Distributes the microplasmas over theentire electrode surface area

Equivalent Circuit of a Microdischarge

Microdischarge Activity and U-Q Lissajous Figure

B Eliasson and U Kogelschatz IEEE Transactions Plasma Science Vol 19 Issue 6 1063-1077 (1991)

Fundamental Operation of the Dielectric Barrier DischargeFundamental Operation of the Dielectric Barrier Discharge

bull Many of relevant plasma processes that areof importance to achieving our goal occuron time scales that allow us to study themon time scales that allow us to study them

bull Optical emission spectroscopic studies willallow us to determine the temporal andspatial development of important plasmaspatial development of important plasmaspecies such as radicals (OH NO variousoxygen radicals) with high time resolution(less than 10 ns) and a spatial resolution onthe scale of mm in the plasma volumepfollowing pulsed plasma excitation

Time scale of the relevant processes of the DBD

HE Wagner R Brandenburg et al lsquoThe barrier discharge basic properties and applications tosurface treatmentrsquo Vacuum 71 417-436 (2003)

Fundamental Operation of the DBDFundamental Operation of the DBD

Electron DensityTemporal Development (ns)

y

Outer Contour Linen = 1010 cm-3ne = 1010 cm 3

Inner Contour Linene = 1014 cm-3

Streamer Propagation in 1 bar AirAA Kulikovsky IEEE Trans Plasma Sci 25 439-446 (1997)

Numerical Results of Microdischarge Formationin Dielectric Barrier Discharges

Starting Phase of a Microdischarge (1 bar 20 CO2 80 H2)

E0=34 kVcm1010 cm-3

1010 cm-3 ne=1012 cm-3

1mm10 cm

ne=108 cm-3

An electron avalanche propagates towards the anode

Reverse propagationtowards the cathodepropagates towards the anode towards the cathode

Numerical Results of Microdischarge Formationin Dielectric Barrier Discharges

Cathode Layer Formation

E0=34 kVcm1010 cm-39 3 0

1mm

1010 cm-3

10 cmne=109 cm-31014

10131014

1013

10 cm1012

Just before the peak of the total current

Peak currentof the total current

Numerical Results of Microdischarge Formationin Dielectric Barrier Discharges

Local Field Collapse in Area Defined by Surface Discharge

ne=109cm-3 ne=1014 cm-3

Gap

Principals of DBD MicroplasmasPrincipals of DBD MicroplasmasPrincipals of DBD MicroplasmasPrincipals of DBD Microplasmas

C C-- - --- - - CG

CD

-- - - CG

CD

Principals of DBD MicroplasmasPrincipals of DBD MicroplasmasPrincipals of DBD MicroplasmasPrincipals of DBD Microplasmas

Dielectric Barrier Discharge (DBD)Dielectric Barrier Discharge (DBD)Electric Field

B kdBreakdown

Electrons amp Ions Discharge Physics

Excited SpeciesPlasma Chemistry

Chemical Reactions

OzoneGeneration

SurfaceTreatment

PollutionControl

ExcimerFormation CO2 Lasers Hydrogenation

of CO2

Excimer Lamps Plasma Displays

How A Plasma Display Works

How A Plasma Display Work

Plasma Display TelevisionsPlasma Display Televisions

Ozone Generator

3 O 2 O

Dielectric Barrier Discharge

3 O2 2 O3

OO22 OO33++OO22Ondash ndashO3O2

O2O2

Ondash ndash

endash O2Ondash ndash O2endash

O3

O3O2O2 O2

HeatHeatHeatHeat

Properties of Ozone (O3)

T i t i f f Tri-atomic form of oxygen

Most powerful commercial oxidizing agent

Unstable - must be generated and used onsite

Limited solubility in water but more so than oxygenLimited solubility in water but more so than oxygen

Leaves a dissolved residual which ultimately converts back to oxygenconverts back to oxygen

Discharge Tubes in Ozone GeneratorsDischarge Tubes in Ozone Generators

Traditional

Ozone Generator

with Glass Tubes

Generation of OzoneGeneration of Ozone

Generation of OzoneAdvantages of Enamel Dielectrics

Proven Patented Designbull Simplicity

Si l Di l i Cbull Single Dielectric Componentndash Reduced number of Dielectrics

bull Safety ndash Lower operating voltage

(lt 4000 V)bull Reliabilty

ndash Fused Dielectrics ensure continuous production

bull Lowest Power Consumption Operational Savingsndash Operational Savings

Modern Ozone GeneratorModern Ozone Generator

Ozonia Advanced Technology Ozone GeneratorOzone Generator

Generation of OzoneGeneration of Ozone

Generation of Ozone

Power Supply UnitPower Supply Unit

IGBT Inverter CircuitMain Circuit Breaker

HV 480 Volts60 Hz3 Phase Supply

C I

450KVAPow er to

GeneratorFILTER

CONVERTER INVERTERTRANSFORMER

C I450KVA Power Stage

CONTACTOR

bull Latest in Power Semiconductor Technology Modular Design

bull Utilizes IGBTrsquos (Insulated Gate Bi‐Polar Transistors) Converter and Inverter Components

Ozone Water Treatment

B bbl Diff iB bbl Diff iBubble DiffusionBubble Diffusion

Easy to use

Low energy usage Low energy usage

Mass transfer efficiencies to gt 90

Ozone Process Flow DiagramOzone Process Flow DiagramVent to

Atmosphere

O OOxygen

Off-Gas Blower

Ozone Destruct Unit

10 12

O3O2

LOX

10-12 O3

Ozone Generators

Ozone Contact ChamberLOX T k Generators Chamber

VaporizersLOX Tank

Municipal Ozone Installations

Ozonia Installations Ozone Plant Size [lbday] Start-Up DateKey Ozonia Installations (Partial List)

Los Angeles CA 10000 1986Fairfax VA ndash Corbalis 9000 2003MWD CA ndash Mills 9 000 2003

Ozonia Installations Ozone Plant Size [lbday] Start Up Date

MWD CA Mills 9000 2003Fairfax Co VA ndash Griffith 9000 2004MWD CA ndash Jensen 18750 2005Indianapolis IN ndash Belmont AWT 12000 2007I di li IN 12 000 2007Indianapolis IN ndash Southport AWT 12000 2007MWD CA ndash Diemer 13400 2008MWD CA ndash Weymouth 13400 2009

Ozonia North America - Potable Water SummaryTotal Number of Installations 90Total Installed Production gt 265000 lbsdayTotal Installed Production 265000 lbsday

Revision -B

Ozone Water TreatmentOzone Water Treatment

MWD Mills WTP - California

3 3 000 lbsda of o one3 3 000 lbsda of o one3 x 3000 lbsday of ozone3 x 3000 lbsday of ozone

Ozone Water TreatmentOzone Water TreatmentOzone Ozone -- How it worksHow it works

OxidantOxidant DisinfectantDisinfectant

bullbull Breaks double carbon Breaks double carbon bondsbonds

bullbull Kills by cell lysing or Kills by cell lysing or causing the cell wall tocausing the cell wall tobondsbonds

bullbull Creates OHCreates OHbullbull radicals radicals which break higher carbon which break higher carbon

causing the cell wall to causing the cell wall to rupture rupture

bullbull AttacksAttacks allall bacteriabacteriabondsbondsbullbull Increased temp and pH Increased temp and pH

accelerates Oaccelerates O33

Attacks Attacks allall bacteria bacteria virus cysts and spores virus cysts and spores in varying degreesin varying degreesaccelerates Oaccelerates O33

decomposition to OHdecomposition to OHbullbull

Micro-organism DNA

Capsule AdenineAdenine

Cell wall ThymineThymine

CytosineCytosine

GuanineGuanine

NuclearmaterialCellmembrane

material

Typical Bacterium DNA

Microbial Growth at Various Ozone ConcentrationsConcentrations

Growth likely

Growth possibleGrowth possible

NO GROWTH

0004 0008 0012 0016 0020

Ozone concentration (mgl)Ozone concentration (mgl)

Typical Water Treatment UsageTypical Water Treatment Usage

Application O3 mgl Contact timeUltra Pure Water 005 - 025 sec ndash min

Water bottling 04 ndash 10 5 ndash 10 min

Swimming pools ampspas

01 ndash 075 4 minutes

Potable taste amp odor 15 ndash 50 5 ndash 10 mindisinfection

Microfloculation 10 ndash 30 5 ndash 10 min

Lignin amp tammin 3 0 10 0 10 30 minLignin amp tamminremoval

30 ndash 100 10 ndash 30 min

Municipal wastewater 50 ndash 150+ 15 ndash 30 min

Ozone Water TreatmentOzone Water TreatmentOzone Ozone ndashndash Municipal ApplicationsMunicipal Applications

bullbull Taste and OdorTaste and Odor

bullbull Color RemovalColor Removal

bullbull Disinfection Without Trihalomethanes (THMs)Disinfection Without Trihalomethanes (THMs)

bullbull Improved Filtration Efficiency and FlocculationImproved Filtration Efficiency and Flocculation

bullbull Cryptosporidium DeactivationCryptosporidium Deactivation

bullbull Giardia amp Virus InactivationGiardia amp Virus Inactivation

bullbull Oxidation Oxidation -- Organics Fe amp MnOrganics Fe amp Mn

bullbull Wastewater disinfectionWastewater disinfection

bullbull BOD COD and TOC reductionBOD COD and TOC reduction

Applications of Ozone

Wastewater Treatmentbull Disinfection of Secondary and Tertiary Effluentsbull Color Reductionbull Color Reductionbull TOC Oxidation (Industrial)bull Oxidation of Odor Causing Compoundsbull Oxidation of Endocrine Disruptors (EDCrsquos) and p ( )

Pharmaceutically Active Compounds (PACrsquos)

Applications of Ozone

What are Endocrine Disruptors (EDCrsquos) and What are Endocrine Disruptors (EDCrsquos) and Ph ti ll A ti C d (PACrsquo )Ph ti ll A ti C d (PACrsquo )Pharmaceutically Active Compounds (PACrsquos)Pharmaceutically Active Compounds (PACrsquos)

bullbull EDCrsquosEDCrsquos andand PACrsquosPACrsquos areare NaturallyNaturally andand SyntheticSyntheticdd th tth t ff tff t thth b lb l llcompoundscompounds thatthat maymay affectaffect thethe balancebalance oror normalnormal

functionsfunctions inin animalsanimals andand humanshumans

What can EDCrsquos and PACrsquos doWhat can EDCrsquos and PACrsquos do

bullbull Even in very small concentrations these compounds Even in very small concentrations these compounds y py pcan can disruptdisrupt normal bodily functionsnormal bodily functions

bullbull ManMan--made chemicals can trick the bodies endocrine made chemicals can trick the bodies endocrine system system

Applications of Ozone

Examples of Endocrine Disruptors1000rsquos of compounds that may be Investigated as EDCs ndash Some examples are

bullbull Synthetic HormonesSynthetic Hormonesbullbull Naturally Occurring Estrogens Naturally Occurring Estrogens

Health and Beauty AidsHealth and Beauty Aidsbullbull Health and Beauty AidsHealth and Beauty Aidsbullbull SolventsSolventsbullbull PesticidesPesticidesbullbull SurfactantsSurfactantsbullbull PlasticsPlastics

F i idF i idbullbull FungicidesFungicides

Ozone Water TreatmentOzone Water Treatment

Ozone Ozone -- Industrial ApplicationsIndustrial Applications-- Ultrapure Water for Pharmaceutical ApplicationsUltrapure Water for Pharmaceutical Applications

-- Wastewater disinfection color removalWastewater disinfection color removal

-- Soil and Groundwater Remediation Soil and Groundwater Remediation

-- Cooling Tower Water TreatmentCooling Tower Water Treatment

-- Food ProcessingFood Processing

-- Aquaculture AquariumsAquaculture AquariumsAquaculture AquariumsAquaculture Aquariums

-- Beverage ApplicationsBeverage Applications

P l amp P Bl hiP l amp P Bl hi-- Pulp amp Paper BleachingPulp amp Paper Bleaching

High Purity OzonationHigh Purity Ozonation

Microchip manufacturingMicrochip manufacturing

What are the current issues in large-scale gozone generationg

Experimental Setup

Front view of the two units after the redesign and reworking ofthe gas water and instruments connectionsthe gas water and instruments connections

Experimental Setup

Top view of the twoexperimental unitsexperimental unitsSpectroscope (notshown) is to the left ofthe DBD The units weredifferent with respect todifferent with respect totheir electrodes onehad only the electrodecoated with thedielectric (ldquosingle-dielectric ( single-coatedrdquo) the other onehad the electrode andthe anode coated withthe dielectric (ldquodouble-the dielectric ( double-coatedrdquo)

Basics Generation of OzoneBasics Generation of Ozone

SpectroscopyPlasma

Plasma Absorption SpectroscopyPlasma Absorption Spectroscopy

Infrared Absorption SpectroscopyInfrared Absorption Spectroscopy

IR spectra in pure oxygen (black curve) and at approximately 10wt N2 admixture (red line) N2O5 peaks appear at124 1 d 1 2 11245 cm-1 and at 1725 cm-1

Infrared Absorption SpectroscopyInfrared Absorption Spectroscopy

IR spectra of several methane variations The green curve envelopes all of the methane peaks at 1325 cm-1recorded at smaller methane admixtures Simultaneously the N2O5 peaks disappear as the methane peaks appear

N2O5 FormationN2O5 Formation2 52 5p=2 bara cwt=20degC q=35kWm2 f=1450Hz

45N2O5 AT95

30

35

40

N

2 B

lend

ing

N2O AT95N2O5 IGSN2O IGSN2O5 LGN2O LG

1 5

20

25

nt [p

pmV]

3

wt

05

10

15

NO

x co

nten

005 7 9 11 13 15 17

ozone conc [wt]

Amount of formed N2O5 and N2O as a function of ozone concentration at 3 wt of nitrogen admixture and fori l dvarious electrode arrangements

Plasma Emission SpectroscopyPlasma Emission Spectroscopyp pyp py

Relative Emissions of the Ozonizer plasmaRelative Emissions of the Ozonizer plasma

Region 300- 850 nm from individual (calibrated) regions (smoothed by PeakFit) Single-coated ozone generator Inlet side

3 5E+06

30E+06

35E+06

7 9

20E+06

25E+06

nten

sity

au

2

311 12

10E+06

15E+06

In 4

5

6 8 10

14

15

16

17

00E+00

50E+05

280 300 320 340 360 380 400 420 440 460 480 500 520 540 560 580 600 620 640 660 680 700 720 740 760 780 800 820 840 860

Wavelength nm

1 13

Wavelength nm

Absolute Emission of the DBD PlasmaAbsolute Emission of the DBD Plasma

Intensities in (O2+3 wtN2) plasma

1 20E+04

100E+04

120E+04

600E+03

800E+03

nten

sity

(au

)

200E+03

400E+03

In

O(777)

000E+00200 250 300 350 400 450 500 550 600 650 700 750 800 850

Wavelength nm

Intensities in 3 wtN2+O2 plasmaIntensities in 3 wtN2+O2 plasma

Plasma Chemistry in OzonizersPlasma Chemistry in Ozonizers

Dry Air O2 N2

e - e -

O N2 N O2

O3 NO

O2 N O2

O3

N

3

NO2

O2 O3

NO

N

NO2 O3

N2O

NO3 N

N2O4

NO2

NO2

N2O5

NO3

Primary electron-driven chemical reactions leading to the formation of N2O5 and N2O in a dry air plasma

Plasma emission diagnostics role of N2Plasma emission diagnostics role of N2

Dry Air O2 N2

e - e -

O N2 N O2

O3 NO

O2 N O2

O3

O

N

ON

NO2

O2O3

N

NO N

NO2 O3

N2O

NO3 N

N2O4

NO2

NO2

N2O5

NO3

ONbullWith N2 present ndash less oxygen atoms are formed However the difference in intensity is

very small

Modeling of plasma chemistry incl the NxOy chemistry up to N2O5 for different Oxygen Nitrogen mixtures varying power deposition scenarios

and initial ozone background concentrations (up to 15) previously done

The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation

The role of N2 must be related to its by-products reacting on the surface of the electrodeThe role of N2 must be related to its by-products reacting on the surface of the electrode

The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established

Ab 8 t f O

The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established

Ab 8 t f OAbove 8 wt of O3

1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)

Above 8 wt of O3

1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)case without pampp)

2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of the

case without pampp)

2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of thethem A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface

them A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface

The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation

Three possibilities have to be considered for the oxygen-fedozone generator

Three possibilities have to be considered for the oxygen-fedozone generatorozone generator

bull Excited N2 molecules lead to an increased O2 dissociation in

ozone generator

bull Excited N2 molecules lead to an increased O2 dissociation in2 2such case an increased efficiency is correlated to the N2admixture

2 2such case an increased efficiency is correlated to the N2admixture

bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial

bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial

bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2

bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2g p g 3 pp y 2g p g 3 pp y 2

Effect of methane on ozone efficiency and specific powerEffect of methane on ozone efficiency and specific power

Effect of Methane on Ozone Content in Outlet Gas and on Specific Power Pure O2

13 12

10

11

12

t 8

10

8

9

10

ne c

onte

nt w

t

6

8

ecifi

c po

wer

kW

hlb

5

6

7

Ozo

n

2

4 Spe

400E+00 20E+03 40E+03 60E+03 80E+03 10E+04 12E+04

Methane in feedgas ppm

0

Ozone content in the outlet gas Specif ic pow er of the ozone generatorg p p g

Effects of N2 and CH4Effects of N2 and CH4

Pi t f h t lli N O t tPicture of an amorphous-crystalline N2O5 structurecaptured at the Orlando Skylake water plant in 2006

Plasma Chemistry with CH4 Impurities

OxygenO2 N2

e - e -

CHO N2

NO2

O NO

O2 N O2 O3

NOH

CH4e-

O3 NO

NO2

O2O3NO N

NO2 O

NO2

NO2

N2ONO3

N

O3

NO2

NO

HNO3

N2O4

N2O5

NO2

NO3

N2O5

Effect of methane on the electrode surfaces

a) b)

Inlet Outlet Outlet

) d)

I l t I l t

c) d)

Electrode of the ozone generator afterseveral hours in CH8O2 and up to 2 wt of methane (a b c)

Inlet Inlet

three hours in CH8O2+traces of N2 and up to 1 wt of methane (d) Visible change of discharge character at about 13 length of electrode (a d)

Kinetics of CHx Conversion without N2

conversion by collisions

O2 + CHx 12wt O3 + CO2 +H2O

deposition vaporizationby sputtering

ibl b l 1000 CHreversible process below 1000ppm CH4

Effect of water on electrode surface with N2

Inlet

OutletOutlet

Electrode of the ozone generator after several hours in H OO N

Inlet

Electrode of the ozone generator after several hours in H2OO2N2

Effect of water on electrode surface

Long term effect (800 hrs) of H2OO2N2

Kinetics of CHx Conversion with N2

conversion by collisionsHNO3 formation

O2 + N2 +CHx 12wtO2 + CO2 +H2O + HNO3

deposition vaporizationby sputtering

H2O + HNO3

by sputtering

irreversible process above a N2 threshold () ltlt 1000ppm N2

sticky deposit

p 2 ( ) pp 2 any CH4 concentration (60ppm)

Plasma Chemistry with CH4 ImpuritiesPlasma Chemistry with CH4 Impurities4

bull Formation of NO and NO2 depends on O3 N2 and gas temperature Conclusion N2 admixture is the key factor

SummarySummaryyyThe mechanisms of formed NOx by-products follows the sameThe mechanisms of formed NOx by-products follows the sameprinciples as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentration

principles as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentrationozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)

ozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)g p ( g p )

The conversion of methane to OH and H2O is found to depend on

g p ( g p )

The conversion of methane to OH and H2O is found to depend ondissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)

dissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)discharge gap)discharge gap)

How do you optimize an ozone generatorg

Scientific ApproachScientific ApproachTheoretical Experimental

pppp

c [wt]

f [Hz]

c [wt]

f [Hz]

[kW]UUUβ1

1Cf4αPn

1iiminpeakimin

iiD

q [kWm2]q [kWm2]

150

180

][V]voltagepeakUpeak

[]cylinder perslicesofamountnsliceii

whereth

09 00

30

60

90

120

effic

ienc

y [

][0tdj t bl[F]sliceisdielectricofecapacitancC

[Hz]frequencyf[V]sliceivoltageminimumiUmin

thiD

th

10

28

46

64

82

39

107

176

244 power density

[kWm2]

ozone conc [wt][]CCβ

][0parameteradjustableα

iDiGi

Impact of Power Inductionp

350

400

wer

200

250

300

App

lied

Pow

Arr C 2Arr D +0

Arr E +45Arr F +7

Arr G +3

5 0

100

150

Frac

tion

of

1 2 3 4

ReferenceArr B unstable

Arr C -2

00

50

4Position (1inlet 4outlet)

Experimental Test Rigp g

Experimental Test Rigp g

Outer grounded electrode (left picture) and the dielectric covered inner electrodes (right) d e ect c cove ed e e ect odes ( g t)

Reference (Traditional) Arrangement

Inlet OutletGas flow direction

Optimized Arrangement

Inlet OutletGas flow direction

Intelligent Gap System (IGS)g p y ( )

Molecular Oxygen (O2) Ozone (O3)

O2 O3

yg ( 2) ( 3)

Particle Size SynthesisParticle Size SynthesisByBy--Products Cluster FormationProducts Cluster Formationyy

high diffusion and deposition to surfaces

low diffusion rate good transport

high sedimentation on the structurehigh sedimentation on the structure

Degreacutemont Technologies ndash OzoniaIntelligent Gap SystemIntelligent Gap System

G Vezzuacute JL Lopez A Freilich and K Becker Optimizationof Large-Scale Ozone Generators IEEE Transactions onPlasma Science Vol 37 No 6 p 890-896 (2009)

ConclusionsConclusionsConclusionsConclusionsFundamentals of ozone synthesis in a DBD plasmay p

ndash Highly filamented DBD discharges are best-suitedfor the production of ozone concentrations in therange of 6 to 14 wtrange of 6 to 14 wt

ndash The preferred characteristic of the microdischargesare Townsend-like at reduced electric fields Enaround 190 Townsend

ndash Detrimental side-effects induced by by-productscan be avoided by a proper design of the electrodecan be avoided by a proper design of the electrodearrangement The phenomenon is related to thediffusion rates of formed by-product clusters

ConclusionsConclusionsConclusionsConclusionsBenefits from DBD microplasma tailoring

ndash Reduced power consumption of up to 10 improvement

ndash Increased ozone concentrations of up to 14 now achievable

ndash Improved neutralization and conditioning of detrimental by-products

ndash Reduced system capital and operational cost

New technologies to improve ozone p

generatorg

HV Pulsed Power SwitchingHV Pulsed Power Switching

Microchannel Generation of Ozone

Channel ArrayChannel Array

Microchannel

330 microm 230 microm

Some Cap-DBD Devices Operating in Air

Increase of 60 of

Spacing 225 μmof 60 of plasma

No space

Cap‐DBD ozone generation

bull Ozone concentration is evaluated via Eco S d l UV 100 O A l (0 01Sensors model UV-100 Ozone Analyzer (001 ndash 900 ppm wiht an accuracy of plusmn2)

bull Three reactors 6 tubings 6rdquo with spacings of 0 μm 225 μm and 500 μm running at 3 kV μ μ μ g

SpacingOzone Concentration

3 kV rms 4 kV rms3 kV rms 4 kV rms

0 μm 660 ppm

225 μm 550 ppm

For a device of such small scale these ozone levels are promising

500 μm 380 ppm

J Mahoney W Zhu VS Johnson KH Becker and JL Lopez Electrical and optical emissionmeasurements of a capillary dielectric barrier discharge European Physics Journal D Vol 60 441-447(2010)

QuestionsQuestions

Thank YouFor more informationProf Jose L Lopez PhD

Thank YouFor more informationDepartment of Physics

Telephone (973) 761-9057Email joselopez1shuedu

Website wwwshueduacademicsartsciphysicsWebsite wwwshueduacademicsartsciphysics

Page 18: Dielectric Barrier Discharge (DBD) & Progress in Large ...bonitz/si12/talks/august_8/lopez_si12.pdf · Dielectric Barrier Discharge (DBD) & Progress in Large-Scale Ozone Generation

What can we do with microplasmasWhat can we do with microplasmas

Material Synthesis Plasma display Surface Treatment Lighting

OzoneOzone generation for water cleaning

Bio-applicationMaterial processing Dental application

and Many morehellip

Some High Pressure microplasma reactors Some High Pressure microplasma reactors

Dielectric Barrier Discharge (DBD)Dielectric Barrier Discharge (DBD)

Hi h V l

HighVoltage

High VoltageElectrode

ACGenerator

DielectricBarrier

Generator

G

Microplasmas

GroundElectrode

Faradayrsquos Dielectric CapacitorsFaradayrsquos Dielectric Capacitors

Faradays Dielectric Capacitor (circa 1837)

Michael Faraday (1781 ndash 1867) Capacitance INCREASED

Historical Ozone Tube of W Siemens (1857)Historical Ozone Tube of W Siemens (1857)

Werner v SiemensP d frsquo A l d Ch i d Ph ik 102 66 (1857)Poggendorfrsquos Annalen der Chemie und Physik 102 66 (1857)

ldquoOzone Production in an Atmospheric-PressureDielectric Barrier Dischargerdquo

Dielectric Barrier Discharge

Dielectric Barrier DischargeDielectric - Barrier Discharge ConfigurationsHigh

VoltageAC

Generator

High VoltageElectrode

DielectricBarrier

DielectricBarrier

High VoltageElectrode

Discharge

DischargeGeneratorGround

Electrode

Electrode

GroundElectrode

Discharge

H E Wagner R Brandenburg et al lsquoThe barrier discharge basic properties and applications toHE Wagner R Brandenburg et al The barrier discharge basic properties and applications tosurface treatmentrsquo Vacuum 71 p417-436 (2003)

Typical operational conditions of barrier discharges Typical operational conditions of barrier discharges

Electric field strength E of first breakdown asymp150 Td (p = 1bar T=300 K)

Voltage Vpp 3ndash20 kV

Repetition frequency f 50 Hzndash30 kHz

Pressure p 1ndash3 bar

Gap distance g 02ndash5mm

Dielectric material thickness d 05ndash2mm

Relative dielectric permittivity r 5ndash10 (glass)

B Eliasson and U Kogelschatz IEEE Transactions Plasma Science Vol 19 Issue 6 1063-1077 (1991)B Eliasson and U Kogelschatz IEEE Transactions Plasma Science Vol 19 Issue 6 1063-1077 (1991)

Single and double DBD

Single dielectric Double dielectric

Role of the Dielectric (Insulator)

Th di l t i i th k f thThe dielectric is the key for the properfunctioning of the discharge

Serves two functions

1 Limits the amount of charge transportedby a single microplasma

2 Distributes the microplasmas over theentire electrode surface area

Equivalent Circuit of a Microdischarge

Microdischarge Activity and U-Q Lissajous Figure

B Eliasson and U Kogelschatz IEEE Transactions Plasma Science Vol 19 Issue 6 1063-1077 (1991)

Fundamental Operation of the Dielectric Barrier DischargeFundamental Operation of the Dielectric Barrier Discharge

bull Many of relevant plasma processes that areof importance to achieving our goal occuron time scales that allow us to study themon time scales that allow us to study them

bull Optical emission spectroscopic studies willallow us to determine the temporal andspatial development of important plasmaspatial development of important plasmaspecies such as radicals (OH NO variousoxygen radicals) with high time resolution(less than 10 ns) and a spatial resolution onthe scale of mm in the plasma volumepfollowing pulsed plasma excitation

Time scale of the relevant processes of the DBD

HE Wagner R Brandenburg et al lsquoThe barrier discharge basic properties and applications tosurface treatmentrsquo Vacuum 71 417-436 (2003)

Fundamental Operation of the DBDFundamental Operation of the DBD

Electron DensityTemporal Development (ns)

y

Outer Contour Linen = 1010 cm-3ne = 1010 cm 3

Inner Contour Linene = 1014 cm-3

Streamer Propagation in 1 bar AirAA Kulikovsky IEEE Trans Plasma Sci 25 439-446 (1997)

Numerical Results of Microdischarge Formationin Dielectric Barrier Discharges

Starting Phase of a Microdischarge (1 bar 20 CO2 80 H2)

E0=34 kVcm1010 cm-3

1010 cm-3 ne=1012 cm-3

1mm10 cm

ne=108 cm-3

An electron avalanche propagates towards the anode

Reverse propagationtowards the cathodepropagates towards the anode towards the cathode

Numerical Results of Microdischarge Formationin Dielectric Barrier Discharges

Cathode Layer Formation

E0=34 kVcm1010 cm-39 3 0

1mm

1010 cm-3

10 cmne=109 cm-31014

10131014

1013

10 cm1012

Just before the peak of the total current

Peak currentof the total current

Numerical Results of Microdischarge Formationin Dielectric Barrier Discharges

Local Field Collapse in Area Defined by Surface Discharge

ne=109cm-3 ne=1014 cm-3

Gap

Principals of DBD MicroplasmasPrincipals of DBD MicroplasmasPrincipals of DBD MicroplasmasPrincipals of DBD Microplasmas

C C-- - --- - - CG

CD

-- - - CG

CD

Principals of DBD MicroplasmasPrincipals of DBD MicroplasmasPrincipals of DBD MicroplasmasPrincipals of DBD Microplasmas

Dielectric Barrier Discharge (DBD)Dielectric Barrier Discharge (DBD)Electric Field

B kdBreakdown

Electrons amp Ions Discharge Physics

Excited SpeciesPlasma Chemistry

Chemical Reactions

OzoneGeneration

SurfaceTreatment

PollutionControl

ExcimerFormation CO2 Lasers Hydrogenation

of CO2

Excimer Lamps Plasma Displays

How A Plasma Display Works

How A Plasma Display Work

Plasma Display TelevisionsPlasma Display Televisions

Ozone Generator

3 O 2 O

Dielectric Barrier Discharge

3 O2 2 O3

OO22 OO33++OO22Ondash ndashO3O2

O2O2

Ondash ndash

endash O2Ondash ndash O2endash

O3

O3O2O2 O2

HeatHeatHeatHeat

Properties of Ozone (O3)

T i t i f f Tri-atomic form of oxygen

Most powerful commercial oxidizing agent

Unstable - must be generated and used onsite

Limited solubility in water but more so than oxygenLimited solubility in water but more so than oxygen

Leaves a dissolved residual which ultimately converts back to oxygenconverts back to oxygen

Discharge Tubes in Ozone GeneratorsDischarge Tubes in Ozone Generators

Traditional

Ozone Generator

with Glass Tubes

Generation of OzoneGeneration of Ozone

Generation of OzoneAdvantages of Enamel Dielectrics

Proven Patented Designbull Simplicity

Si l Di l i Cbull Single Dielectric Componentndash Reduced number of Dielectrics

bull Safety ndash Lower operating voltage

(lt 4000 V)bull Reliabilty

ndash Fused Dielectrics ensure continuous production

bull Lowest Power Consumption Operational Savingsndash Operational Savings

Modern Ozone GeneratorModern Ozone Generator

Ozonia Advanced Technology Ozone GeneratorOzone Generator

Generation of OzoneGeneration of Ozone

Generation of Ozone

Power Supply UnitPower Supply Unit

IGBT Inverter CircuitMain Circuit Breaker

HV 480 Volts60 Hz3 Phase Supply

C I

450KVAPow er to

GeneratorFILTER

CONVERTER INVERTERTRANSFORMER

C I450KVA Power Stage

CONTACTOR

bull Latest in Power Semiconductor Technology Modular Design

bull Utilizes IGBTrsquos (Insulated Gate Bi‐Polar Transistors) Converter and Inverter Components

Ozone Water Treatment

B bbl Diff iB bbl Diff iBubble DiffusionBubble Diffusion

Easy to use

Low energy usage Low energy usage

Mass transfer efficiencies to gt 90

Ozone Process Flow DiagramOzone Process Flow DiagramVent to

Atmosphere

O OOxygen

Off-Gas Blower

Ozone Destruct Unit

10 12

O3O2

LOX

10-12 O3

Ozone Generators

Ozone Contact ChamberLOX T k Generators Chamber

VaporizersLOX Tank

Municipal Ozone Installations

Ozonia Installations Ozone Plant Size [lbday] Start-Up DateKey Ozonia Installations (Partial List)

Los Angeles CA 10000 1986Fairfax VA ndash Corbalis 9000 2003MWD CA ndash Mills 9 000 2003

Ozonia Installations Ozone Plant Size [lbday] Start Up Date

MWD CA Mills 9000 2003Fairfax Co VA ndash Griffith 9000 2004MWD CA ndash Jensen 18750 2005Indianapolis IN ndash Belmont AWT 12000 2007I di li IN 12 000 2007Indianapolis IN ndash Southport AWT 12000 2007MWD CA ndash Diemer 13400 2008MWD CA ndash Weymouth 13400 2009

Ozonia North America - Potable Water SummaryTotal Number of Installations 90Total Installed Production gt 265000 lbsdayTotal Installed Production 265000 lbsday

Revision -B

Ozone Water TreatmentOzone Water Treatment

MWD Mills WTP - California

3 3 000 lbsda of o one3 3 000 lbsda of o one3 x 3000 lbsday of ozone3 x 3000 lbsday of ozone

Ozone Water TreatmentOzone Water TreatmentOzone Ozone -- How it worksHow it works

OxidantOxidant DisinfectantDisinfectant

bullbull Breaks double carbon Breaks double carbon bondsbonds

bullbull Kills by cell lysing or Kills by cell lysing or causing the cell wall tocausing the cell wall tobondsbonds

bullbull Creates OHCreates OHbullbull radicals radicals which break higher carbon which break higher carbon

causing the cell wall to causing the cell wall to rupture rupture

bullbull AttacksAttacks allall bacteriabacteriabondsbondsbullbull Increased temp and pH Increased temp and pH

accelerates Oaccelerates O33

Attacks Attacks allall bacteria bacteria virus cysts and spores virus cysts and spores in varying degreesin varying degreesaccelerates Oaccelerates O33

decomposition to OHdecomposition to OHbullbull

Micro-organism DNA

Capsule AdenineAdenine

Cell wall ThymineThymine

CytosineCytosine

GuanineGuanine

NuclearmaterialCellmembrane

material

Typical Bacterium DNA

Microbial Growth at Various Ozone ConcentrationsConcentrations

Growth likely

Growth possibleGrowth possible

NO GROWTH

0004 0008 0012 0016 0020

Ozone concentration (mgl)Ozone concentration (mgl)

Typical Water Treatment UsageTypical Water Treatment Usage

Application O3 mgl Contact timeUltra Pure Water 005 - 025 sec ndash min

Water bottling 04 ndash 10 5 ndash 10 min

Swimming pools ampspas

01 ndash 075 4 minutes

Potable taste amp odor 15 ndash 50 5 ndash 10 mindisinfection

Microfloculation 10 ndash 30 5 ndash 10 min

Lignin amp tammin 3 0 10 0 10 30 minLignin amp tamminremoval

30 ndash 100 10 ndash 30 min

Municipal wastewater 50 ndash 150+ 15 ndash 30 min

Ozone Water TreatmentOzone Water TreatmentOzone Ozone ndashndash Municipal ApplicationsMunicipal Applications

bullbull Taste and OdorTaste and Odor

bullbull Color RemovalColor Removal

bullbull Disinfection Without Trihalomethanes (THMs)Disinfection Without Trihalomethanes (THMs)

bullbull Improved Filtration Efficiency and FlocculationImproved Filtration Efficiency and Flocculation

bullbull Cryptosporidium DeactivationCryptosporidium Deactivation

bullbull Giardia amp Virus InactivationGiardia amp Virus Inactivation

bullbull Oxidation Oxidation -- Organics Fe amp MnOrganics Fe amp Mn

bullbull Wastewater disinfectionWastewater disinfection

bullbull BOD COD and TOC reductionBOD COD and TOC reduction

Applications of Ozone

Wastewater Treatmentbull Disinfection of Secondary and Tertiary Effluentsbull Color Reductionbull Color Reductionbull TOC Oxidation (Industrial)bull Oxidation of Odor Causing Compoundsbull Oxidation of Endocrine Disruptors (EDCrsquos) and p ( )

Pharmaceutically Active Compounds (PACrsquos)

Applications of Ozone

What are Endocrine Disruptors (EDCrsquos) and What are Endocrine Disruptors (EDCrsquos) and Ph ti ll A ti C d (PACrsquo )Ph ti ll A ti C d (PACrsquo )Pharmaceutically Active Compounds (PACrsquos)Pharmaceutically Active Compounds (PACrsquos)

bullbull EDCrsquosEDCrsquos andand PACrsquosPACrsquos areare NaturallyNaturally andand SyntheticSyntheticdd th tth t ff tff t thth b lb l llcompoundscompounds thatthat maymay affectaffect thethe balancebalance oror normalnormal

functionsfunctions inin animalsanimals andand humanshumans

What can EDCrsquos and PACrsquos doWhat can EDCrsquos and PACrsquos do

bullbull Even in very small concentrations these compounds Even in very small concentrations these compounds y py pcan can disruptdisrupt normal bodily functionsnormal bodily functions

bullbull ManMan--made chemicals can trick the bodies endocrine made chemicals can trick the bodies endocrine system system

Applications of Ozone

Examples of Endocrine Disruptors1000rsquos of compounds that may be Investigated as EDCs ndash Some examples are

bullbull Synthetic HormonesSynthetic Hormonesbullbull Naturally Occurring Estrogens Naturally Occurring Estrogens

Health and Beauty AidsHealth and Beauty Aidsbullbull Health and Beauty AidsHealth and Beauty Aidsbullbull SolventsSolventsbullbull PesticidesPesticidesbullbull SurfactantsSurfactantsbullbull PlasticsPlastics

F i idF i idbullbull FungicidesFungicides

Ozone Water TreatmentOzone Water Treatment

Ozone Ozone -- Industrial ApplicationsIndustrial Applications-- Ultrapure Water for Pharmaceutical ApplicationsUltrapure Water for Pharmaceutical Applications

-- Wastewater disinfection color removalWastewater disinfection color removal

-- Soil and Groundwater Remediation Soil and Groundwater Remediation

-- Cooling Tower Water TreatmentCooling Tower Water Treatment

-- Food ProcessingFood Processing

-- Aquaculture AquariumsAquaculture AquariumsAquaculture AquariumsAquaculture Aquariums

-- Beverage ApplicationsBeverage Applications

P l amp P Bl hiP l amp P Bl hi-- Pulp amp Paper BleachingPulp amp Paper Bleaching

High Purity OzonationHigh Purity Ozonation

Microchip manufacturingMicrochip manufacturing

What are the current issues in large-scale gozone generationg

Experimental Setup

Front view of the two units after the redesign and reworking ofthe gas water and instruments connectionsthe gas water and instruments connections

Experimental Setup

Top view of the twoexperimental unitsexperimental unitsSpectroscope (notshown) is to the left ofthe DBD The units weredifferent with respect todifferent with respect totheir electrodes onehad only the electrodecoated with thedielectric (ldquosingle-dielectric ( single-coatedrdquo) the other onehad the electrode andthe anode coated withthe dielectric (ldquodouble-the dielectric ( double-coatedrdquo)

Basics Generation of OzoneBasics Generation of Ozone

SpectroscopyPlasma

Plasma Absorption SpectroscopyPlasma Absorption Spectroscopy

Infrared Absorption SpectroscopyInfrared Absorption Spectroscopy

IR spectra in pure oxygen (black curve) and at approximately 10wt N2 admixture (red line) N2O5 peaks appear at124 1 d 1 2 11245 cm-1 and at 1725 cm-1

Infrared Absorption SpectroscopyInfrared Absorption Spectroscopy

IR spectra of several methane variations The green curve envelopes all of the methane peaks at 1325 cm-1recorded at smaller methane admixtures Simultaneously the N2O5 peaks disappear as the methane peaks appear

N2O5 FormationN2O5 Formation2 52 5p=2 bara cwt=20degC q=35kWm2 f=1450Hz

45N2O5 AT95

30

35

40

N

2 B

lend

ing

N2O AT95N2O5 IGSN2O IGSN2O5 LGN2O LG

1 5

20

25

nt [p

pmV]

3

wt

05

10

15

NO

x co

nten

005 7 9 11 13 15 17

ozone conc [wt]

Amount of formed N2O5 and N2O as a function of ozone concentration at 3 wt of nitrogen admixture and fori l dvarious electrode arrangements

Plasma Emission SpectroscopyPlasma Emission Spectroscopyp pyp py

Relative Emissions of the Ozonizer plasmaRelative Emissions of the Ozonizer plasma

Region 300- 850 nm from individual (calibrated) regions (smoothed by PeakFit) Single-coated ozone generator Inlet side

3 5E+06

30E+06

35E+06

7 9

20E+06

25E+06

nten

sity

au

2

311 12

10E+06

15E+06

In 4

5

6 8 10

14

15

16

17

00E+00

50E+05

280 300 320 340 360 380 400 420 440 460 480 500 520 540 560 580 600 620 640 660 680 700 720 740 760 780 800 820 840 860

Wavelength nm

1 13

Wavelength nm

Absolute Emission of the DBD PlasmaAbsolute Emission of the DBD Plasma

Intensities in (O2+3 wtN2) plasma

1 20E+04

100E+04

120E+04

600E+03

800E+03

nten

sity

(au

)

200E+03

400E+03

In

O(777)

000E+00200 250 300 350 400 450 500 550 600 650 700 750 800 850

Wavelength nm

Intensities in 3 wtN2+O2 plasmaIntensities in 3 wtN2+O2 plasma

Plasma Chemistry in OzonizersPlasma Chemistry in Ozonizers

Dry Air O2 N2

e - e -

O N2 N O2

O3 NO

O2 N O2

O3

N

3

NO2

O2 O3

NO

N

NO2 O3

N2O

NO3 N

N2O4

NO2

NO2

N2O5

NO3

Primary electron-driven chemical reactions leading to the formation of N2O5 and N2O in a dry air plasma

Plasma emission diagnostics role of N2Plasma emission diagnostics role of N2

Dry Air O2 N2

e - e -

O N2 N O2

O3 NO

O2 N O2

O3

O

N

ON

NO2

O2O3

N

NO N

NO2 O3

N2O

NO3 N

N2O4

NO2

NO2

N2O5

NO3

ONbullWith N2 present ndash less oxygen atoms are formed However the difference in intensity is

very small

Modeling of plasma chemistry incl the NxOy chemistry up to N2O5 for different Oxygen Nitrogen mixtures varying power deposition scenarios

and initial ozone background concentrations (up to 15) previously done

The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation

The role of N2 must be related to its by-products reacting on the surface of the electrodeThe role of N2 must be related to its by-products reacting on the surface of the electrode

The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established

Ab 8 t f O

The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established

Ab 8 t f OAbove 8 wt of O3

1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)

Above 8 wt of O3

1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)case without pampp)

2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of the

case without pampp)

2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of thethem A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface

them A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface

The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation

Three possibilities have to be considered for the oxygen-fedozone generator

Three possibilities have to be considered for the oxygen-fedozone generatorozone generator

bull Excited N2 molecules lead to an increased O2 dissociation in

ozone generator

bull Excited N2 molecules lead to an increased O2 dissociation in2 2such case an increased efficiency is correlated to the N2admixture

2 2such case an increased efficiency is correlated to the N2admixture

bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial

bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial

bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2

bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2g p g 3 pp y 2g p g 3 pp y 2

Effect of methane on ozone efficiency and specific powerEffect of methane on ozone efficiency and specific power

Effect of Methane on Ozone Content in Outlet Gas and on Specific Power Pure O2

13 12

10

11

12

t 8

10

8

9

10

ne c

onte

nt w

t

6

8

ecifi

c po

wer

kW

hlb

5

6

7

Ozo

n

2

4 Spe

400E+00 20E+03 40E+03 60E+03 80E+03 10E+04 12E+04

Methane in feedgas ppm

0

Ozone content in the outlet gas Specif ic pow er of the ozone generatorg p p g

Effects of N2 and CH4Effects of N2 and CH4

Pi t f h t lli N O t tPicture of an amorphous-crystalline N2O5 structurecaptured at the Orlando Skylake water plant in 2006

Plasma Chemistry with CH4 Impurities

OxygenO2 N2

e - e -

CHO N2

NO2

O NO

O2 N O2 O3

NOH

CH4e-

O3 NO

NO2

O2O3NO N

NO2 O

NO2

NO2

N2ONO3

N

O3

NO2

NO

HNO3

N2O4

N2O5

NO2

NO3

N2O5

Effect of methane on the electrode surfaces

a) b)

Inlet Outlet Outlet

) d)

I l t I l t

c) d)

Electrode of the ozone generator afterseveral hours in CH8O2 and up to 2 wt of methane (a b c)

Inlet Inlet

three hours in CH8O2+traces of N2 and up to 1 wt of methane (d) Visible change of discharge character at about 13 length of electrode (a d)

Kinetics of CHx Conversion without N2

conversion by collisions

O2 + CHx 12wt O3 + CO2 +H2O

deposition vaporizationby sputtering

ibl b l 1000 CHreversible process below 1000ppm CH4

Effect of water on electrode surface with N2

Inlet

OutletOutlet

Electrode of the ozone generator after several hours in H OO N

Inlet

Electrode of the ozone generator after several hours in H2OO2N2

Effect of water on electrode surface

Long term effect (800 hrs) of H2OO2N2

Kinetics of CHx Conversion with N2

conversion by collisionsHNO3 formation

O2 + N2 +CHx 12wtO2 + CO2 +H2O + HNO3

deposition vaporizationby sputtering

H2O + HNO3

by sputtering

irreversible process above a N2 threshold () ltlt 1000ppm N2

sticky deposit

p 2 ( ) pp 2 any CH4 concentration (60ppm)

Plasma Chemistry with CH4 ImpuritiesPlasma Chemistry with CH4 Impurities4

bull Formation of NO and NO2 depends on O3 N2 and gas temperature Conclusion N2 admixture is the key factor

SummarySummaryyyThe mechanisms of formed NOx by-products follows the sameThe mechanisms of formed NOx by-products follows the sameprinciples as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentration

principles as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentrationozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)

ozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)g p ( g p )

The conversion of methane to OH and H2O is found to depend on

g p ( g p )

The conversion of methane to OH and H2O is found to depend ondissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)

dissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)discharge gap)discharge gap)

How do you optimize an ozone generatorg

Scientific ApproachScientific ApproachTheoretical Experimental

pppp

c [wt]

f [Hz]

c [wt]

f [Hz]

[kW]UUUβ1

1Cf4αPn

1iiminpeakimin

iiD

q [kWm2]q [kWm2]

150

180

][V]voltagepeakUpeak

[]cylinder perslicesofamountnsliceii

whereth

09 00

30

60

90

120

effic

ienc

y [

][0tdj t bl[F]sliceisdielectricofecapacitancC

[Hz]frequencyf[V]sliceivoltageminimumiUmin

thiD

th

10

28

46

64

82

39

107

176

244 power density

[kWm2]

ozone conc [wt][]CCβ

][0parameteradjustableα

iDiGi

Impact of Power Inductionp

350

400

wer

200

250

300

App

lied

Pow

Arr C 2Arr D +0

Arr E +45Arr F +7

Arr G +3

5 0

100

150

Frac

tion

of

1 2 3 4

ReferenceArr B unstable

Arr C -2

00

50

4Position (1inlet 4outlet)

Experimental Test Rigp g

Experimental Test Rigp g

Outer grounded electrode (left picture) and the dielectric covered inner electrodes (right) d e ect c cove ed e e ect odes ( g t)

Reference (Traditional) Arrangement

Inlet OutletGas flow direction

Optimized Arrangement

Inlet OutletGas flow direction

Intelligent Gap System (IGS)g p y ( )

Molecular Oxygen (O2) Ozone (O3)

O2 O3

yg ( 2) ( 3)

Particle Size SynthesisParticle Size SynthesisByBy--Products Cluster FormationProducts Cluster Formationyy

high diffusion and deposition to surfaces

low diffusion rate good transport

high sedimentation on the structurehigh sedimentation on the structure

Degreacutemont Technologies ndash OzoniaIntelligent Gap SystemIntelligent Gap System

G Vezzuacute JL Lopez A Freilich and K Becker Optimizationof Large-Scale Ozone Generators IEEE Transactions onPlasma Science Vol 37 No 6 p 890-896 (2009)

ConclusionsConclusionsConclusionsConclusionsFundamentals of ozone synthesis in a DBD plasmay p

ndash Highly filamented DBD discharges are best-suitedfor the production of ozone concentrations in therange of 6 to 14 wtrange of 6 to 14 wt

ndash The preferred characteristic of the microdischargesare Townsend-like at reduced electric fields Enaround 190 Townsend

ndash Detrimental side-effects induced by by-productscan be avoided by a proper design of the electrodecan be avoided by a proper design of the electrodearrangement The phenomenon is related to thediffusion rates of formed by-product clusters

ConclusionsConclusionsConclusionsConclusionsBenefits from DBD microplasma tailoring

ndash Reduced power consumption of up to 10 improvement

ndash Increased ozone concentrations of up to 14 now achievable

ndash Improved neutralization and conditioning of detrimental by-products

ndash Reduced system capital and operational cost

New technologies to improve ozone p

generatorg

HV Pulsed Power SwitchingHV Pulsed Power Switching

Microchannel Generation of Ozone

Channel ArrayChannel Array

Microchannel

330 microm 230 microm

Some Cap-DBD Devices Operating in Air

Increase of 60 of

Spacing 225 μmof 60 of plasma

No space

Cap‐DBD ozone generation

bull Ozone concentration is evaluated via Eco S d l UV 100 O A l (0 01Sensors model UV-100 Ozone Analyzer (001 ndash 900 ppm wiht an accuracy of plusmn2)

bull Three reactors 6 tubings 6rdquo with spacings of 0 μm 225 μm and 500 μm running at 3 kV μ μ μ g

SpacingOzone Concentration

3 kV rms 4 kV rms3 kV rms 4 kV rms

0 μm 660 ppm

225 μm 550 ppm

For a device of such small scale these ozone levels are promising

500 μm 380 ppm

J Mahoney W Zhu VS Johnson KH Becker and JL Lopez Electrical and optical emissionmeasurements of a capillary dielectric barrier discharge European Physics Journal D Vol 60 441-447(2010)

QuestionsQuestions

Thank YouFor more informationProf Jose L Lopez PhD

Thank YouFor more informationDepartment of Physics

Telephone (973) 761-9057Email joselopez1shuedu

Website wwwshueduacademicsartsciphysicsWebsite wwwshueduacademicsartsciphysics

Page 19: Dielectric Barrier Discharge (DBD) & Progress in Large ...bonitz/si12/talks/august_8/lopez_si12.pdf · Dielectric Barrier Discharge (DBD) & Progress in Large-Scale Ozone Generation

Some High Pressure microplasma reactors Some High Pressure microplasma reactors

Dielectric Barrier Discharge (DBD)Dielectric Barrier Discharge (DBD)

Hi h V l

HighVoltage

High VoltageElectrode

ACGenerator

DielectricBarrier

Generator

G

Microplasmas

GroundElectrode

Faradayrsquos Dielectric CapacitorsFaradayrsquos Dielectric Capacitors

Faradays Dielectric Capacitor (circa 1837)

Michael Faraday (1781 ndash 1867) Capacitance INCREASED

Historical Ozone Tube of W Siemens (1857)Historical Ozone Tube of W Siemens (1857)

Werner v SiemensP d frsquo A l d Ch i d Ph ik 102 66 (1857)Poggendorfrsquos Annalen der Chemie und Physik 102 66 (1857)

ldquoOzone Production in an Atmospheric-PressureDielectric Barrier Dischargerdquo

Dielectric Barrier Discharge

Dielectric Barrier DischargeDielectric - Barrier Discharge ConfigurationsHigh

VoltageAC

Generator

High VoltageElectrode

DielectricBarrier

DielectricBarrier

High VoltageElectrode

Discharge

DischargeGeneratorGround

Electrode

Electrode

GroundElectrode

Discharge

H E Wagner R Brandenburg et al lsquoThe barrier discharge basic properties and applications toHE Wagner R Brandenburg et al The barrier discharge basic properties and applications tosurface treatmentrsquo Vacuum 71 p417-436 (2003)

Typical operational conditions of barrier discharges Typical operational conditions of barrier discharges

Electric field strength E of first breakdown asymp150 Td (p = 1bar T=300 K)

Voltage Vpp 3ndash20 kV

Repetition frequency f 50 Hzndash30 kHz

Pressure p 1ndash3 bar

Gap distance g 02ndash5mm

Dielectric material thickness d 05ndash2mm

Relative dielectric permittivity r 5ndash10 (glass)

B Eliasson and U Kogelschatz IEEE Transactions Plasma Science Vol 19 Issue 6 1063-1077 (1991)B Eliasson and U Kogelschatz IEEE Transactions Plasma Science Vol 19 Issue 6 1063-1077 (1991)

Single and double DBD

Single dielectric Double dielectric

Role of the Dielectric (Insulator)

Th di l t i i th k f thThe dielectric is the key for the properfunctioning of the discharge

Serves two functions

1 Limits the amount of charge transportedby a single microplasma

2 Distributes the microplasmas over theentire electrode surface area

Equivalent Circuit of a Microdischarge

Microdischarge Activity and U-Q Lissajous Figure

B Eliasson and U Kogelschatz IEEE Transactions Plasma Science Vol 19 Issue 6 1063-1077 (1991)

Fundamental Operation of the Dielectric Barrier DischargeFundamental Operation of the Dielectric Barrier Discharge

bull Many of relevant plasma processes that areof importance to achieving our goal occuron time scales that allow us to study themon time scales that allow us to study them

bull Optical emission spectroscopic studies willallow us to determine the temporal andspatial development of important plasmaspatial development of important plasmaspecies such as radicals (OH NO variousoxygen radicals) with high time resolution(less than 10 ns) and a spatial resolution onthe scale of mm in the plasma volumepfollowing pulsed plasma excitation

Time scale of the relevant processes of the DBD

HE Wagner R Brandenburg et al lsquoThe barrier discharge basic properties and applications tosurface treatmentrsquo Vacuum 71 417-436 (2003)

Fundamental Operation of the DBDFundamental Operation of the DBD

Electron DensityTemporal Development (ns)

y

Outer Contour Linen = 1010 cm-3ne = 1010 cm 3

Inner Contour Linene = 1014 cm-3

Streamer Propagation in 1 bar AirAA Kulikovsky IEEE Trans Plasma Sci 25 439-446 (1997)

Numerical Results of Microdischarge Formationin Dielectric Barrier Discharges

Starting Phase of a Microdischarge (1 bar 20 CO2 80 H2)

E0=34 kVcm1010 cm-3

1010 cm-3 ne=1012 cm-3

1mm10 cm

ne=108 cm-3

An electron avalanche propagates towards the anode

Reverse propagationtowards the cathodepropagates towards the anode towards the cathode

Numerical Results of Microdischarge Formationin Dielectric Barrier Discharges

Cathode Layer Formation

E0=34 kVcm1010 cm-39 3 0

1mm

1010 cm-3

10 cmne=109 cm-31014

10131014

1013

10 cm1012

Just before the peak of the total current

Peak currentof the total current

Numerical Results of Microdischarge Formationin Dielectric Barrier Discharges

Local Field Collapse in Area Defined by Surface Discharge

ne=109cm-3 ne=1014 cm-3

Gap

Principals of DBD MicroplasmasPrincipals of DBD MicroplasmasPrincipals of DBD MicroplasmasPrincipals of DBD Microplasmas

C C-- - --- - - CG

CD

-- - - CG

CD

Principals of DBD MicroplasmasPrincipals of DBD MicroplasmasPrincipals of DBD MicroplasmasPrincipals of DBD Microplasmas

Dielectric Barrier Discharge (DBD)Dielectric Barrier Discharge (DBD)Electric Field

B kdBreakdown

Electrons amp Ions Discharge Physics

Excited SpeciesPlasma Chemistry

Chemical Reactions

OzoneGeneration

SurfaceTreatment

PollutionControl

ExcimerFormation CO2 Lasers Hydrogenation

of CO2

Excimer Lamps Plasma Displays

How A Plasma Display Works

How A Plasma Display Work

Plasma Display TelevisionsPlasma Display Televisions

Ozone Generator

3 O 2 O

Dielectric Barrier Discharge

3 O2 2 O3

OO22 OO33++OO22Ondash ndashO3O2

O2O2

Ondash ndash

endash O2Ondash ndash O2endash

O3

O3O2O2 O2

HeatHeatHeatHeat

Properties of Ozone (O3)

T i t i f f Tri-atomic form of oxygen

Most powerful commercial oxidizing agent

Unstable - must be generated and used onsite

Limited solubility in water but more so than oxygenLimited solubility in water but more so than oxygen

Leaves a dissolved residual which ultimately converts back to oxygenconverts back to oxygen

Discharge Tubes in Ozone GeneratorsDischarge Tubes in Ozone Generators

Traditional

Ozone Generator

with Glass Tubes

Generation of OzoneGeneration of Ozone

Generation of OzoneAdvantages of Enamel Dielectrics

Proven Patented Designbull Simplicity

Si l Di l i Cbull Single Dielectric Componentndash Reduced number of Dielectrics

bull Safety ndash Lower operating voltage

(lt 4000 V)bull Reliabilty

ndash Fused Dielectrics ensure continuous production

bull Lowest Power Consumption Operational Savingsndash Operational Savings

Modern Ozone GeneratorModern Ozone Generator

Ozonia Advanced Technology Ozone GeneratorOzone Generator

Generation of OzoneGeneration of Ozone

Generation of Ozone

Power Supply UnitPower Supply Unit

IGBT Inverter CircuitMain Circuit Breaker

HV 480 Volts60 Hz3 Phase Supply

C I

450KVAPow er to

GeneratorFILTER

CONVERTER INVERTERTRANSFORMER

C I450KVA Power Stage

CONTACTOR

bull Latest in Power Semiconductor Technology Modular Design

bull Utilizes IGBTrsquos (Insulated Gate Bi‐Polar Transistors) Converter and Inverter Components

Ozone Water Treatment

B bbl Diff iB bbl Diff iBubble DiffusionBubble Diffusion

Easy to use

Low energy usage Low energy usage

Mass transfer efficiencies to gt 90

Ozone Process Flow DiagramOzone Process Flow DiagramVent to

Atmosphere

O OOxygen

Off-Gas Blower

Ozone Destruct Unit

10 12

O3O2

LOX

10-12 O3

Ozone Generators

Ozone Contact ChamberLOX T k Generators Chamber

VaporizersLOX Tank

Municipal Ozone Installations

Ozonia Installations Ozone Plant Size [lbday] Start-Up DateKey Ozonia Installations (Partial List)

Los Angeles CA 10000 1986Fairfax VA ndash Corbalis 9000 2003MWD CA ndash Mills 9 000 2003

Ozonia Installations Ozone Plant Size [lbday] Start Up Date

MWD CA Mills 9000 2003Fairfax Co VA ndash Griffith 9000 2004MWD CA ndash Jensen 18750 2005Indianapolis IN ndash Belmont AWT 12000 2007I di li IN 12 000 2007Indianapolis IN ndash Southport AWT 12000 2007MWD CA ndash Diemer 13400 2008MWD CA ndash Weymouth 13400 2009

Ozonia North America - Potable Water SummaryTotal Number of Installations 90Total Installed Production gt 265000 lbsdayTotal Installed Production 265000 lbsday

Revision -B

Ozone Water TreatmentOzone Water Treatment

MWD Mills WTP - California

3 3 000 lbsda of o one3 3 000 lbsda of o one3 x 3000 lbsday of ozone3 x 3000 lbsday of ozone

Ozone Water TreatmentOzone Water TreatmentOzone Ozone -- How it worksHow it works

OxidantOxidant DisinfectantDisinfectant

bullbull Breaks double carbon Breaks double carbon bondsbonds

bullbull Kills by cell lysing or Kills by cell lysing or causing the cell wall tocausing the cell wall tobondsbonds

bullbull Creates OHCreates OHbullbull radicals radicals which break higher carbon which break higher carbon

causing the cell wall to causing the cell wall to rupture rupture

bullbull AttacksAttacks allall bacteriabacteriabondsbondsbullbull Increased temp and pH Increased temp and pH

accelerates Oaccelerates O33

Attacks Attacks allall bacteria bacteria virus cysts and spores virus cysts and spores in varying degreesin varying degreesaccelerates Oaccelerates O33

decomposition to OHdecomposition to OHbullbull

Micro-organism DNA

Capsule AdenineAdenine

Cell wall ThymineThymine

CytosineCytosine

GuanineGuanine

NuclearmaterialCellmembrane

material

Typical Bacterium DNA

Microbial Growth at Various Ozone ConcentrationsConcentrations

Growth likely

Growth possibleGrowth possible

NO GROWTH

0004 0008 0012 0016 0020

Ozone concentration (mgl)Ozone concentration (mgl)

Typical Water Treatment UsageTypical Water Treatment Usage

Application O3 mgl Contact timeUltra Pure Water 005 - 025 sec ndash min

Water bottling 04 ndash 10 5 ndash 10 min

Swimming pools ampspas

01 ndash 075 4 minutes

Potable taste amp odor 15 ndash 50 5 ndash 10 mindisinfection

Microfloculation 10 ndash 30 5 ndash 10 min

Lignin amp tammin 3 0 10 0 10 30 minLignin amp tamminremoval

30 ndash 100 10 ndash 30 min

Municipal wastewater 50 ndash 150+ 15 ndash 30 min

Ozone Water TreatmentOzone Water TreatmentOzone Ozone ndashndash Municipal ApplicationsMunicipal Applications

bullbull Taste and OdorTaste and Odor

bullbull Color RemovalColor Removal

bullbull Disinfection Without Trihalomethanes (THMs)Disinfection Without Trihalomethanes (THMs)

bullbull Improved Filtration Efficiency and FlocculationImproved Filtration Efficiency and Flocculation

bullbull Cryptosporidium DeactivationCryptosporidium Deactivation

bullbull Giardia amp Virus InactivationGiardia amp Virus Inactivation

bullbull Oxidation Oxidation -- Organics Fe amp MnOrganics Fe amp Mn

bullbull Wastewater disinfectionWastewater disinfection

bullbull BOD COD and TOC reductionBOD COD and TOC reduction

Applications of Ozone

Wastewater Treatmentbull Disinfection of Secondary and Tertiary Effluentsbull Color Reductionbull Color Reductionbull TOC Oxidation (Industrial)bull Oxidation of Odor Causing Compoundsbull Oxidation of Endocrine Disruptors (EDCrsquos) and p ( )

Pharmaceutically Active Compounds (PACrsquos)

Applications of Ozone

What are Endocrine Disruptors (EDCrsquos) and What are Endocrine Disruptors (EDCrsquos) and Ph ti ll A ti C d (PACrsquo )Ph ti ll A ti C d (PACrsquo )Pharmaceutically Active Compounds (PACrsquos)Pharmaceutically Active Compounds (PACrsquos)

bullbull EDCrsquosEDCrsquos andand PACrsquosPACrsquos areare NaturallyNaturally andand SyntheticSyntheticdd th tth t ff tff t thth b lb l llcompoundscompounds thatthat maymay affectaffect thethe balancebalance oror normalnormal

functionsfunctions inin animalsanimals andand humanshumans

What can EDCrsquos and PACrsquos doWhat can EDCrsquos and PACrsquos do

bullbull Even in very small concentrations these compounds Even in very small concentrations these compounds y py pcan can disruptdisrupt normal bodily functionsnormal bodily functions

bullbull ManMan--made chemicals can trick the bodies endocrine made chemicals can trick the bodies endocrine system system

Applications of Ozone

Examples of Endocrine Disruptors1000rsquos of compounds that may be Investigated as EDCs ndash Some examples are

bullbull Synthetic HormonesSynthetic Hormonesbullbull Naturally Occurring Estrogens Naturally Occurring Estrogens

Health and Beauty AidsHealth and Beauty Aidsbullbull Health and Beauty AidsHealth and Beauty Aidsbullbull SolventsSolventsbullbull PesticidesPesticidesbullbull SurfactantsSurfactantsbullbull PlasticsPlastics

F i idF i idbullbull FungicidesFungicides

Ozone Water TreatmentOzone Water Treatment

Ozone Ozone -- Industrial ApplicationsIndustrial Applications-- Ultrapure Water for Pharmaceutical ApplicationsUltrapure Water for Pharmaceutical Applications

-- Wastewater disinfection color removalWastewater disinfection color removal

-- Soil and Groundwater Remediation Soil and Groundwater Remediation

-- Cooling Tower Water TreatmentCooling Tower Water Treatment

-- Food ProcessingFood Processing

-- Aquaculture AquariumsAquaculture AquariumsAquaculture AquariumsAquaculture Aquariums

-- Beverage ApplicationsBeverage Applications

P l amp P Bl hiP l amp P Bl hi-- Pulp amp Paper BleachingPulp amp Paper Bleaching

High Purity OzonationHigh Purity Ozonation

Microchip manufacturingMicrochip manufacturing

What are the current issues in large-scale gozone generationg

Experimental Setup

Front view of the two units after the redesign and reworking ofthe gas water and instruments connectionsthe gas water and instruments connections

Experimental Setup

Top view of the twoexperimental unitsexperimental unitsSpectroscope (notshown) is to the left ofthe DBD The units weredifferent with respect todifferent with respect totheir electrodes onehad only the electrodecoated with thedielectric (ldquosingle-dielectric ( single-coatedrdquo) the other onehad the electrode andthe anode coated withthe dielectric (ldquodouble-the dielectric ( double-coatedrdquo)

Basics Generation of OzoneBasics Generation of Ozone

SpectroscopyPlasma

Plasma Absorption SpectroscopyPlasma Absorption Spectroscopy

Infrared Absorption SpectroscopyInfrared Absorption Spectroscopy

IR spectra in pure oxygen (black curve) and at approximately 10wt N2 admixture (red line) N2O5 peaks appear at124 1 d 1 2 11245 cm-1 and at 1725 cm-1

Infrared Absorption SpectroscopyInfrared Absorption Spectroscopy

IR spectra of several methane variations The green curve envelopes all of the methane peaks at 1325 cm-1recorded at smaller methane admixtures Simultaneously the N2O5 peaks disappear as the methane peaks appear

N2O5 FormationN2O5 Formation2 52 5p=2 bara cwt=20degC q=35kWm2 f=1450Hz

45N2O5 AT95

30

35

40

N

2 B

lend

ing

N2O AT95N2O5 IGSN2O IGSN2O5 LGN2O LG

1 5

20

25

nt [p

pmV]

3

wt

05

10

15

NO

x co

nten

005 7 9 11 13 15 17

ozone conc [wt]

Amount of formed N2O5 and N2O as a function of ozone concentration at 3 wt of nitrogen admixture and fori l dvarious electrode arrangements

Plasma Emission SpectroscopyPlasma Emission Spectroscopyp pyp py

Relative Emissions of the Ozonizer plasmaRelative Emissions of the Ozonizer plasma

Region 300- 850 nm from individual (calibrated) regions (smoothed by PeakFit) Single-coated ozone generator Inlet side

3 5E+06

30E+06

35E+06

7 9

20E+06

25E+06

nten

sity

au

2

311 12

10E+06

15E+06

In 4

5

6 8 10

14

15

16

17

00E+00

50E+05

280 300 320 340 360 380 400 420 440 460 480 500 520 540 560 580 600 620 640 660 680 700 720 740 760 780 800 820 840 860

Wavelength nm

1 13

Wavelength nm

Absolute Emission of the DBD PlasmaAbsolute Emission of the DBD Plasma

Intensities in (O2+3 wtN2) plasma

1 20E+04

100E+04

120E+04

600E+03

800E+03

nten

sity

(au

)

200E+03

400E+03

In

O(777)

000E+00200 250 300 350 400 450 500 550 600 650 700 750 800 850

Wavelength nm

Intensities in 3 wtN2+O2 plasmaIntensities in 3 wtN2+O2 plasma

Plasma Chemistry in OzonizersPlasma Chemistry in Ozonizers

Dry Air O2 N2

e - e -

O N2 N O2

O3 NO

O2 N O2

O3

N

3

NO2

O2 O3

NO

N

NO2 O3

N2O

NO3 N

N2O4

NO2

NO2

N2O5

NO3

Primary electron-driven chemical reactions leading to the formation of N2O5 and N2O in a dry air plasma

Plasma emission diagnostics role of N2Plasma emission diagnostics role of N2

Dry Air O2 N2

e - e -

O N2 N O2

O3 NO

O2 N O2

O3

O

N

ON

NO2

O2O3

N

NO N

NO2 O3

N2O

NO3 N

N2O4

NO2

NO2

N2O5

NO3

ONbullWith N2 present ndash less oxygen atoms are formed However the difference in intensity is

very small

Modeling of plasma chemistry incl the NxOy chemistry up to N2O5 for different Oxygen Nitrogen mixtures varying power deposition scenarios

and initial ozone background concentrations (up to 15) previously done

The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation

The role of N2 must be related to its by-products reacting on the surface of the electrodeThe role of N2 must be related to its by-products reacting on the surface of the electrode

The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established

Ab 8 t f O

The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established

Ab 8 t f OAbove 8 wt of O3

1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)

Above 8 wt of O3

1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)case without pampp)

2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of the

case without pampp)

2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of thethem A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface

them A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface

The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation

Three possibilities have to be considered for the oxygen-fedozone generator

Three possibilities have to be considered for the oxygen-fedozone generatorozone generator

bull Excited N2 molecules lead to an increased O2 dissociation in

ozone generator

bull Excited N2 molecules lead to an increased O2 dissociation in2 2such case an increased efficiency is correlated to the N2admixture

2 2such case an increased efficiency is correlated to the N2admixture

bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial

bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial

bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2

bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2g p g 3 pp y 2g p g 3 pp y 2

Effect of methane on ozone efficiency and specific powerEffect of methane on ozone efficiency and specific power

Effect of Methane on Ozone Content in Outlet Gas and on Specific Power Pure O2

13 12

10

11

12

t 8

10

8

9

10

ne c

onte

nt w

t

6

8

ecifi

c po

wer

kW

hlb

5

6

7

Ozo

n

2

4 Spe

400E+00 20E+03 40E+03 60E+03 80E+03 10E+04 12E+04

Methane in feedgas ppm

0

Ozone content in the outlet gas Specif ic pow er of the ozone generatorg p p g

Effects of N2 and CH4Effects of N2 and CH4

Pi t f h t lli N O t tPicture of an amorphous-crystalline N2O5 structurecaptured at the Orlando Skylake water plant in 2006

Plasma Chemistry with CH4 Impurities

OxygenO2 N2

e - e -

CHO N2

NO2

O NO

O2 N O2 O3

NOH

CH4e-

O3 NO

NO2

O2O3NO N

NO2 O

NO2

NO2

N2ONO3

N

O3

NO2

NO

HNO3

N2O4

N2O5

NO2

NO3

N2O5

Effect of methane on the electrode surfaces

a) b)

Inlet Outlet Outlet

) d)

I l t I l t

c) d)

Electrode of the ozone generator afterseveral hours in CH8O2 and up to 2 wt of methane (a b c)

Inlet Inlet

three hours in CH8O2+traces of N2 and up to 1 wt of methane (d) Visible change of discharge character at about 13 length of electrode (a d)

Kinetics of CHx Conversion without N2

conversion by collisions

O2 + CHx 12wt O3 + CO2 +H2O

deposition vaporizationby sputtering

ibl b l 1000 CHreversible process below 1000ppm CH4

Effect of water on electrode surface with N2

Inlet

OutletOutlet

Electrode of the ozone generator after several hours in H OO N

Inlet

Electrode of the ozone generator after several hours in H2OO2N2

Effect of water on electrode surface

Long term effect (800 hrs) of H2OO2N2

Kinetics of CHx Conversion with N2

conversion by collisionsHNO3 formation

O2 + N2 +CHx 12wtO2 + CO2 +H2O + HNO3

deposition vaporizationby sputtering

H2O + HNO3

by sputtering

irreversible process above a N2 threshold () ltlt 1000ppm N2

sticky deposit

p 2 ( ) pp 2 any CH4 concentration (60ppm)

Plasma Chemistry with CH4 ImpuritiesPlasma Chemistry with CH4 Impurities4

bull Formation of NO and NO2 depends on O3 N2 and gas temperature Conclusion N2 admixture is the key factor

SummarySummaryyyThe mechanisms of formed NOx by-products follows the sameThe mechanisms of formed NOx by-products follows the sameprinciples as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentration

principles as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentrationozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)

ozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)g p ( g p )

The conversion of methane to OH and H2O is found to depend on

g p ( g p )

The conversion of methane to OH and H2O is found to depend ondissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)

dissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)discharge gap)discharge gap)

How do you optimize an ozone generatorg

Scientific ApproachScientific ApproachTheoretical Experimental

pppp

c [wt]

f [Hz]

c [wt]

f [Hz]

[kW]UUUβ1

1Cf4αPn

1iiminpeakimin

iiD

q [kWm2]q [kWm2]

150

180

][V]voltagepeakUpeak

[]cylinder perslicesofamountnsliceii

whereth

09 00

30

60

90

120

effic

ienc

y [

][0tdj t bl[F]sliceisdielectricofecapacitancC

[Hz]frequencyf[V]sliceivoltageminimumiUmin

thiD

th

10

28

46

64

82

39

107

176

244 power density

[kWm2]

ozone conc [wt][]CCβ

][0parameteradjustableα

iDiGi

Impact of Power Inductionp

350

400

wer

200

250

300

App

lied

Pow

Arr C 2Arr D +0

Arr E +45Arr F +7

Arr G +3

5 0

100

150

Frac

tion

of

1 2 3 4

ReferenceArr B unstable

Arr C -2

00

50

4Position (1inlet 4outlet)

Experimental Test Rigp g

Experimental Test Rigp g

Outer grounded electrode (left picture) and the dielectric covered inner electrodes (right) d e ect c cove ed e e ect odes ( g t)

Reference (Traditional) Arrangement

Inlet OutletGas flow direction

Optimized Arrangement

Inlet OutletGas flow direction

Intelligent Gap System (IGS)g p y ( )

Molecular Oxygen (O2) Ozone (O3)

O2 O3

yg ( 2) ( 3)

Particle Size SynthesisParticle Size SynthesisByBy--Products Cluster FormationProducts Cluster Formationyy

high diffusion and deposition to surfaces

low diffusion rate good transport

high sedimentation on the structurehigh sedimentation on the structure

Degreacutemont Technologies ndash OzoniaIntelligent Gap SystemIntelligent Gap System

G Vezzuacute JL Lopez A Freilich and K Becker Optimizationof Large-Scale Ozone Generators IEEE Transactions onPlasma Science Vol 37 No 6 p 890-896 (2009)

ConclusionsConclusionsConclusionsConclusionsFundamentals of ozone synthesis in a DBD plasmay p

ndash Highly filamented DBD discharges are best-suitedfor the production of ozone concentrations in therange of 6 to 14 wtrange of 6 to 14 wt

ndash The preferred characteristic of the microdischargesare Townsend-like at reduced electric fields Enaround 190 Townsend

ndash Detrimental side-effects induced by by-productscan be avoided by a proper design of the electrodecan be avoided by a proper design of the electrodearrangement The phenomenon is related to thediffusion rates of formed by-product clusters

ConclusionsConclusionsConclusionsConclusionsBenefits from DBD microplasma tailoring

ndash Reduced power consumption of up to 10 improvement

ndash Increased ozone concentrations of up to 14 now achievable

ndash Improved neutralization and conditioning of detrimental by-products

ndash Reduced system capital and operational cost

New technologies to improve ozone p

generatorg

HV Pulsed Power SwitchingHV Pulsed Power Switching

Microchannel Generation of Ozone

Channel ArrayChannel Array

Microchannel

330 microm 230 microm

Some Cap-DBD Devices Operating in Air

Increase of 60 of

Spacing 225 μmof 60 of plasma

No space

Cap‐DBD ozone generation

bull Ozone concentration is evaluated via Eco S d l UV 100 O A l (0 01Sensors model UV-100 Ozone Analyzer (001 ndash 900 ppm wiht an accuracy of plusmn2)

bull Three reactors 6 tubings 6rdquo with spacings of 0 μm 225 μm and 500 μm running at 3 kV μ μ μ g

SpacingOzone Concentration

3 kV rms 4 kV rms3 kV rms 4 kV rms

0 μm 660 ppm

225 μm 550 ppm

For a device of such small scale these ozone levels are promising

500 μm 380 ppm

J Mahoney W Zhu VS Johnson KH Becker and JL Lopez Electrical and optical emissionmeasurements of a capillary dielectric barrier discharge European Physics Journal D Vol 60 441-447(2010)

QuestionsQuestions

Thank YouFor more informationProf Jose L Lopez PhD

Thank YouFor more informationDepartment of Physics

Telephone (973) 761-9057Email joselopez1shuedu

Website wwwshueduacademicsartsciphysicsWebsite wwwshueduacademicsartsciphysics

Page 20: Dielectric Barrier Discharge (DBD) & Progress in Large ...bonitz/si12/talks/august_8/lopez_si12.pdf · Dielectric Barrier Discharge (DBD) & Progress in Large-Scale Ozone Generation

Dielectric Barrier Discharge (DBD)Dielectric Barrier Discharge (DBD)

Hi h V l

HighVoltage

High VoltageElectrode

ACGenerator

DielectricBarrier

Generator

G

Microplasmas

GroundElectrode

Faradayrsquos Dielectric CapacitorsFaradayrsquos Dielectric Capacitors

Faradays Dielectric Capacitor (circa 1837)

Michael Faraday (1781 ndash 1867) Capacitance INCREASED

Historical Ozone Tube of W Siemens (1857)Historical Ozone Tube of W Siemens (1857)

Werner v SiemensP d frsquo A l d Ch i d Ph ik 102 66 (1857)Poggendorfrsquos Annalen der Chemie und Physik 102 66 (1857)

ldquoOzone Production in an Atmospheric-PressureDielectric Barrier Dischargerdquo

Dielectric Barrier Discharge

Dielectric Barrier DischargeDielectric - Barrier Discharge ConfigurationsHigh

VoltageAC

Generator

High VoltageElectrode

DielectricBarrier

DielectricBarrier

High VoltageElectrode

Discharge

DischargeGeneratorGround

Electrode

Electrode

GroundElectrode

Discharge

H E Wagner R Brandenburg et al lsquoThe barrier discharge basic properties and applications toHE Wagner R Brandenburg et al The barrier discharge basic properties and applications tosurface treatmentrsquo Vacuum 71 p417-436 (2003)

Typical operational conditions of barrier discharges Typical operational conditions of barrier discharges

Electric field strength E of first breakdown asymp150 Td (p = 1bar T=300 K)

Voltage Vpp 3ndash20 kV

Repetition frequency f 50 Hzndash30 kHz

Pressure p 1ndash3 bar

Gap distance g 02ndash5mm

Dielectric material thickness d 05ndash2mm

Relative dielectric permittivity r 5ndash10 (glass)

B Eliasson and U Kogelschatz IEEE Transactions Plasma Science Vol 19 Issue 6 1063-1077 (1991)B Eliasson and U Kogelschatz IEEE Transactions Plasma Science Vol 19 Issue 6 1063-1077 (1991)

Single and double DBD

Single dielectric Double dielectric

Role of the Dielectric (Insulator)

Th di l t i i th k f thThe dielectric is the key for the properfunctioning of the discharge

Serves two functions

1 Limits the amount of charge transportedby a single microplasma

2 Distributes the microplasmas over theentire electrode surface area

Equivalent Circuit of a Microdischarge

Microdischarge Activity and U-Q Lissajous Figure

B Eliasson and U Kogelschatz IEEE Transactions Plasma Science Vol 19 Issue 6 1063-1077 (1991)

Fundamental Operation of the Dielectric Barrier DischargeFundamental Operation of the Dielectric Barrier Discharge

bull Many of relevant plasma processes that areof importance to achieving our goal occuron time scales that allow us to study themon time scales that allow us to study them

bull Optical emission spectroscopic studies willallow us to determine the temporal andspatial development of important plasmaspatial development of important plasmaspecies such as radicals (OH NO variousoxygen radicals) with high time resolution(less than 10 ns) and a spatial resolution onthe scale of mm in the plasma volumepfollowing pulsed plasma excitation

Time scale of the relevant processes of the DBD

HE Wagner R Brandenburg et al lsquoThe barrier discharge basic properties and applications tosurface treatmentrsquo Vacuum 71 417-436 (2003)

Fundamental Operation of the DBDFundamental Operation of the DBD

Electron DensityTemporal Development (ns)

y

Outer Contour Linen = 1010 cm-3ne = 1010 cm 3

Inner Contour Linene = 1014 cm-3

Streamer Propagation in 1 bar AirAA Kulikovsky IEEE Trans Plasma Sci 25 439-446 (1997)

Numerical Results of Microdischarge Formationin Dielectric Barrier Discharges

Starting Phase of a Microdischarge (1 bar 20 CO2 80 H2)

E0=34 kVcm1010 cm-3

1010 cm-3 ne=1012 cm-3

1mm10 cm

ne=108 cm-3

An electron avalanche propagates towards the anode

Reverse propagationtowards the cathodepropagates towards the anode towards the cathode

Numerical Results of Microdischarge Formationin Dielectric Barrier Discharges

Cathode Layer Formation

E0=34 kVcm1010 cm-39 3 0

1mm

1010 cm-3

10 cmne=109 cm-31014

10131014

1013

10 cm1012

Just before the peak of the total current

Peak currentof the total current

Numerical Results of Microdischarge Formationin Dielectric Barrier Discharges

Local Field Collapse in Area Defined by Surface Discharge

ne=109cm-3 ne=1014 cm-3

Gap

Principals of DBD MicroplasmasPrincipals of DBD MicroplasmasPrincipals of DBD MicroplasmasPrincipals of DBD Microplasmas

C C-- - --- - - CG

CD

-- - - CG

CD

Principals of DBD MicroplasmasPrincipals of DBD MicroplasmasPrincipals of DBD MicroplasmasPrincipals of DBD Microplasmas

Dielectric Barrier Discharge (DBD)Dielectric Barrier Discharge (DBD)Electric Field

B kdBreakdown

Electrons amp Ions Discharge Physics

Excited SpeciesPlasma Chemistry

Chemical Reactions

OzoneGeneration

SurfaceTreatment

PollutionControl

ExcimerFormation CO2 Lasers Hydrogenation

of CO2

Excimer Lamps Plasma Displays

How A Plasma Display Works

How A Plasma Display Work

Plasma Display TelevisionsPlasma Display Televisions

Ozone Generator

3 O 2 O

Dielectric Barrier Discharge

3 O2 2 O3

OO22 OO33++OO22Ondash ndashO3O2

O2O2

Ondash ndash

endash O2Ondash ndash O2endash

O3

O3O2O2 O2

HeatHeatHeatHeat

Properties of Ozone (O3)

T i t i f f Tri-atomic form of oxygen

Most powerful commercial oxidizing agent

Unstable - must be generated and used onsite

Limited solubility in water but more so than oxygenLimited solubility in water but more so than oxygen

Leaves a dissolved residual which ultimately converts back to oxygenconverts back to oxygen

Discharge Tubes in Ozone GeneratorsDischarge Tubes in Ozone Generators

Traditional

Ozone Generator

with Glass Tubes

Generation of OzoneGeneration of Ozone

Generation of OzoneAdvantages of Enamel Dielectrics

Proven Patented Designbull Simplicity

Si l Di l i Cbull Single Dielectric Componentndash Reduced number of Dielectrics

bull Safety ndash Lower operating voltage

(lt 4000 V)bull Reliabilty

ndash Fused Dielectrics ensure continuous production

bull Lowest Power Consumption Operational Savingsndash Operational Savings

Modern Ozone GeneratorModern Ozone Generator

Ozonia Advanced Technology Ozone GeneratorOzone Generator

Generation of OzoneGeneration of Ozone

Generation of Ozone

Power Supply UnitPower Supply Unit

IGBT Inverter CircuitMain Circuit Breaker

HV 480 Volts60 Hz3 Phase Supply

C I

450KVAPow er to

GeneratorFILTER

CONVERTER INVERTERTRANSFORMER

C I450KVA Power Stage

CONTACTOR

bull Latest in Power Semiconductor Technology Modular Design

bull Utilizes IGBTrsquos (Insulated Gate Bi‐Polar Transistors) Converter and Inverter Components

Ozone Water Treatment

B bbl Diff iB bbl Diff iBubble DiffusionBubble Diffusion

Easy to use

Low energy usage Low energy usage

Mass transfer efficiencies to gt 90

Ozone Process Flow DiagramOzone Process Flow DiagramVent to

Atmosphere

O OOxygen

Off-Gas Blower

Ozone Destruct Unit

10 12

O3O2

LOX

10-12 O3

Ozone Generators

Ozone Contact ChamberLOX T k Generators Chamber

VaporizersLOX Tank

Municipal Ozone Installations

Ozonia Installations Ozone Plant Size [lbday] Start-Up DateKey Ozonia Installations (Partial List)

Los Angeles CA 10000 1986Fairfax VA ndash Corbalis 9000 2003MWD CA ndash Mills 9 000 2003

Ozonia Installations Ozone Plant Size [lbday] Start Up Date

MWD CA Mills 9000 2003Fairfax Co VA ndash Griffith 9000 2004MWD CA ndash Jensen 18750 2005Indianapolis IN ndash Belmont AWT 12000 2007I di li IN 12 000 2007Indianapolis IN ndash Southport AWT 12000 2007MWD CA ndash Diemer 13400 2008MWD CA ndash Weymouth 13400 2009

Ozonia North America - Potable Water SummaryTotal Number of Installations 90Total Installed Production gt 265000 lbsdayTotal Installed Production 265000 lbsday

Revision -B

Ozone Water TreatmentOzone Water Treatment

MWD Mills WTP - California

3 3 000 lbsda of o one3 3 000 lbsda of o one3 x 3000 lbsday of ozone3 x 3000 lbsday of ozone

Ozone Water TreatmentOzone Water TreatmentOzone Ozone -- How it worksHow it works

OxidantOxidant DisinfectantDisinfectant

bullbull Breaks double carbon Breaks double carbon bondsbonds

bullbull Kills by cell lysing or Kills by cell lysing or causing the cell wall tocausing the cell wall tobondsbonds

bullbull Creates OHCreates OHbullbull radicals radicals which break higher carbon which break higher carbon

causing the cell wall to causing the cell wall to rupture rupture

bullbull AttacksAttacks allall bacteriabacteriabondsbondsbullbull Increased temp and pH Increased temp and pH

accelerates Oaccelerates O33

Attacks Attacks allall bacteria bacteria virus cysts and spores virus cysts and spores in varying degreesin varying degreesaccelerates Oaccelerates O33

decomposition to OHdecomposition to OHbullbull

Micro-organism DNA

Capsule AdenineAdenine

Cell wall ThymineThymine

CytosineCytosine

GuanineGuanine

NuclearmaterialCellmembrane

material

Typical Bacterium DNA

Microbial Growth at Various Ozone ConcentrationsConcentrations

Growth likely

Growth possibleGrowth possible

NO GROWTH

0004 0008 0012 0016 0020

Ozone concentration (mgl)Ozone concentration (mgl)

Typical Water Treatment UsageTypical Water Treatment Usage

Application O3 mgl Contact timeUltra Pure Water 005 - 025 sec ndash min

Water bottling 04 ndash 10 5 ndash 10 min

Swimming pools ampspas

01 ndash 075 4 minutes

Potable taste amp odor 15 ndash 50 5 ndash 10 mindisinfection

Microfloculation 10 ndash 30 5 ndash 10 min

Lignin amp tammin 3 0 10 0 10 30 minLignin amp tamminremoval

30 ndash 100 10 ndash 30 min

Municipal wastewater 50 ndash 150+ 15 ndash 30 min

Ozone Water TreatmentOzone Water TreatmentOzone Ozone ndashndash Municipal ApplicationsMunicipal Applications

bullbull Taste and OdorTaste and Odor

bullbull Color RemovalColor Removal

bullbull Disinfection Without Trihalomethanes (THMs)Disinfection Without Trihalomethanes (THMs)

bullbull Improved Filtration Efficiency and FlocculationImproved Filtration Efficiency and Flocculation

bullbull Cryptosporidium DeactivationCryptosporidium Deactivation

bullbull Giardia amp Virus InactivationGiardia amp Virus Inactivation

bullbull Oxidation Oxidation -- Organics Fe amp MnOrganics Fe amp Mn

bullbull Wastewater disinfectionWastewater disinfection

bullbull BOD COD and TOC reductionBOD COD and TOC reduction

Applications of Ozone

Wastewater Treatmentbull Disinfection of Secondary and Tertiary Effluentsbull Color Reductionbull Color Reductionbull TOC Oxidation (Industrial)bull Oxidation of Odor Causing Compoundsbull Oxidation of Endocrine Disruptors (EDCrsquos) and p ( )

Pharmaceutically Active Compounds (PACrsquos)

Applications of Ozone

What are Endocrine Disruptors (EDCrsquos) and What are Endocrine Disruptors (EDCrsquos) and Ph ti ll A ti C d (PACrsquo )Ph ti ll A ti C d (PACrsquo )Pharmaceutically Active Compounds (PACrsquos)Pharmaceutically Active Compounds (PACrsquos)

bullbull EDCrsquosEDCrsquos andand PACrsquosPACrsquos areare NaturallyNaturally andand SyntheticSyntheticdd th tth t ff tff t thth b lb l llcompoundscompounds thatthat maymay affectaffect thethe balancebalance oror normalnormal

functionsfunctions inin animalsanimals andand humanshumans

What can EDCrsquos and PACrsquos doWhat can EDCrsquos and PACrsquos do

bullbull Even in very small concentrations these compounds Even in very small concentrations these compounds y py pcan can disruptdisrupt normal bodily functionsnormal bodily functions

bullbull ManMan--made chemicals can trick the bodies endocrine made chemicals can trick the bodies endocrine system system

Applications of Ozone

Examples of Endocrine Disruptors1000rsquos of compounds that may be Investigated as EDCs ndash Some examples are

bullbull Synthetic HormonesSynthetic Hormonesbullbull Naturally Occurring Estrogens Naturally Occurring Estrogens

Health and Beauty AidsHealth and Beauty Aidsbullbull Health and Beauty AidsHealth and Beauty Aidsbullbull SolventsSolventsbullbull PesticidesPesticidesbullbull SurfactantsSurfactantsbullbull PlasticsPlastics

F i idF i idbullbull FungicidesFungicides

Ozone Water TreatmentOzone Water Treatment

Ozone Ozone -- Industrial ApplicationsIndustrial Applications-- Ultrapure Water for Pharmaceutical ApplicationsUltrapure Water for Pharmaceutical Applications

-- Wastewater disinfection color removalWastewater disinfection color removal

-- Soil and Groundwater Remediation Soil and Groundwater Remediation

-- Cooling Tower Water TreatmentCooling Tower Water Treatment

-- Food ProcessingFood Processing

-- Aquaculture AquariumsAquaculture AquariumsAquaculture AquariumsAquaculture Aquariums

-- Beverage ApplicationsBeverage Applications

P l amp P Bl hiP l amp P Bl hi-- Pulp amp Paper BleachingPulp amp Paper Bleaching

High Purity OzonationHigh Purity Ozonation

Microchip manufacturingMicrochip manufacturing

What are the current issues in large-scale gozone generationg

Experimental Setup

Front view of the two units after the redesign and reworking ofthe gas water and instruments connectionsthe gas water and instruments connections

Experimental Setup

Top view of the twoexperimental unitsexperimental unitsSpectroscope (notshown) is to the left ofthe DBD The units weredifferent with respect todifferent with respect totheir electrodes onehad only the electrodecoated with thedielectric (ldquosingle-dielectric ( single-coatedrdquo) the other onehad the electrode andthe anode coated withthe dielectric (ldquodouble-the dielectric ( double-coatedrdquo)

Basics Generation of OzoneBasics Generation of Ozone

SpectroscopyPlasma

Plasma Absorption SpectroscopyPlasma Absorption Spectroscopy

Infrared Absorption SpectroscopyInfrared Absorption Spectroscopy

IR spectra in pure oxygen (black curve) and at approximately 10wt N2 admixture (red line) N2O5 peaks appear at124 1 d 1 2 11245 cm-1 and at 1725 cm-1

Infrared Absorption SpectroscopyInfrared Absorption Spectroscopy

IR spectra of several methane variations The green curve envelopes all of the methane peaks at 1325 cm-1recorded at smaller methane admixtures Simultaneously the N2O5 peaks disappear as the methane peaks appear

N2O5 FormationN2O5 Formation2 52 5p=2 bara cwt=20degC q=35kWm2 f=1450Hz

45N2O5 AT95

30

35

40

N

2 B

lend

ing

N2O AT95N2O5 IGSN2O IGSN2O5 LGN2O LG

1 5

20

25

nt [p

pmV]

3

wt

05

10

15

NO

x co

nten

005 7 9 11 13 15 17

ozone conc [wt]

Amount of formed N2O5 and N2O as a function of ozone concentration at 3 wt of nitrogen admixture and fori l dvarious electrode arrangements

Plasma Emission SpectroscopyPlasma Emission Spectroscopyp pyp py

Relative Emissions of the Ozonizer plasmaRelative Emissions of the Ozonizer plasma

Region 300- 850 nm from individual (calibrated) regions (smoothed by PeakFit) Single-coated ozone generator Inlet side

3 5E+06

30E+06

35E+06

7 9

20E+06

25E+06

nten

sity

au

2

311 12

10E+06

15E+06

In 4

5

6 8 10

14

15

16

17

00E+00

50E+05

280 300 320 340 360 380 400 420 440 460 480 500 520 540 560 580 600 620 640 660 680 700 720 740 760 780 800 820 840 860

Wavelength nm

1 13

Wavelength nm

Absolute Emission of the DBD PlasmaAbsolute Emission of the DBD Plasma

Intensities in (O2+3 wtN2) plasma

1 20E+04

100E+04

120E+04

600E+03

800E+03

nten

sity

(au

)

200E+03

400E+03

In

O(777)

000E+00200 250 300 350 400 450 500 550 600 650 700 750 800 850

Wavelength nm

Intensities in 3 wtN2+O2 plasmaIntensities in 3 wtN2+O2 plasma

Plasma Chemistry in OzonizersPlasma Chemistry in Ozonizers

Dry Air O2 N2

e - e -

O N2 N O2

O3 NO

O2 N O2

O3

N

3

NO2

O2 O3

NO

N

NO2 O3

N2O

NO3 N

N2O4

NO2

NO2

N2O5

NO3

Primary electron-driven chemical reactions leading to the formation of N2O5 and N2O in a dry air plasma

Plasma emission diagnostics role of N2Plasma emission diagnostics role of N2

Dry Air O2 N2

e - e -

O N2 N O2

O3 NO

O2 N O2

O3

O

N

ON

NO2

O2O3

N

NO N

NO2 O3

N2O

NO3 N

N2O4

NO2

NO2

N2O5

NO3

ONbullWith N2 present ndash less oxygen atoms are formed However the difference in intensity is

very small

Modeling of plasma chemistry incl the NxOy chemistry up to N2O5 for different Oxygen Nitrogen mixtures varying power deposition scenarios

and initial ozone background concentrations (up to 15) previously done

The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation

The role of N2 must be related to its by-products reacting on the surface of the electrodeThe role of N2 must be related to its by-products reacting on the surface of the electrode

The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established

Ab 8 t f O

The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established

Ab 8 t f OAbove 8 wt of O3

1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)

Above 8 wt of O3

1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)case without pampp)

2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of the

case without pampp)

2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of thethem A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface

them A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface

The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation

Three possibilities have to be considered for the oxygen-fedozone generator

Three possibilities have to be considered for the oxygen-fedozone generatorozone generator

bull Excited N2 molecules lead to an increased O2 dissociation in

ozone generator

bull Excited N2 molecules lead to an increased O2 dissociation in2 2such case an increased efficiency is correlated to the N2admixture

2 2such case an increased efficiency is correlated to the N2admixture

bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial

bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial

bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2

bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2g p g 3 pp y 2g p g 3 pp y 2

Effect of methane on ozone efficiency and specific powerEffect of methane on ozone efficiency and specific power

Effect of Methane on Ozone Content in Outlet Gas and on Specific Power Pure O2

13 12

10

11

12

t 8

10

8

9

10

ne c

onte

nt w

t

6

8

ecifi

c po

wer

kW

hlb

5

6

7

Ozo

n

2

4 Spe

400E+00 20E+03 40E+03 60E+03 80E+03 10E+04 12E+04

Methane in feedgas ppm

0

Ozone content in the outlet gas Specif ic pow er of the ozone generatorg p p g

Effects of N2 and CH4Effects of N2 and CH4

Pi t f h t lli N O t tPicture of an amorphous-crystalline N2O5 structurecaptured at the Orlando Skylake water plant in 2006

Plasma Chemistry with CH4 Impurities

OxygenO2 N2

e - e -

CHO N2

NO2

O NO

O2 N O2 O3

NOH

CH4e-

O3 NO

NO2

O2O3NO N

NO2 O

NO2

NO2

N2ONO3

N

O3

NO2

NO

HNO3

N2O4

N2O5

NO2

NO3

N2O5

Effect of methane on the electrode surfaces

a) b)

Inlet Outlet Outlet

) d)

I l t I l t

c) d)

Electrode of the ozone generator afterseveral hours in CH8O2 and up to 2 wt of methane (a b c)

Inlet Inlet

three hours in CH8O2+traces of N2 and up to 1 wt of methane (d) Visible change of discharge character at about 13 length of electrode (a d)

Kinetics of CHx Conversion without N2

conversion by collisions

O2 + CHx 12wt O3 + CO2 +H2O

deposition vaporizationby sputtering

ibl b l 1000 CHreversible process below 1000ppm CH4

Effect of water on electrode surface with N2

Inlet

OutletOutlet

Electrode of the ozone generator after several hours in H OO N

Inlet

Electrode of the ozone generator after several hours in H2OO2N2

Effect of water on electrode surface

Long term effect (800 hrs) of H2OO2N2

Kinetics of CHx Conversion with N2

conversion by collisionsHNO3 formation

O2 + N2 +CHx 12wtO2 + CO2 +H2O + HNO3

deposition vaporizationby sputtering

H2O + HNO3

by sputtering

irreversible process above a N2 threshold () ltlt 1000ppm N2

sticky deposit

p 2 ( ) pp 2 any CH4 concentration (60ppm)

Plasma Chemistry with CH4 ImpuritiesPlasma Chemistry with CH4 Impurities4

bull Formation of NO and NO2 depends on O3 N2 and gas temperature Conclusion N2 admixture is the key factor

SummarySummaryyyThe mechanisms of formed NOx by-products follows the sameThe mechanisms of formed NOx by-products follows the sameprinciples as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentration

principles as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentrationozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)

ozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)g p ( g p )

The conversion of methane to OH and H2O is found to depend on

g p ( g p )

The conversion of methane to OH and H2O is found to depend ondissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)

dissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)discharge gap)discharge gap)

How do you optimize an ozone generatorg

Scientific ApproachScientific ApproachTheoretical Experimental

pppp

c [wt]

f [Hz]

c [wt]

f [Hz]

[kW]UUUβ1

1Cf4αPn

1iiminpeakimin

iiD

q [kWm2]q [kWm2]

150

180

][V]voltagepeakUpeak

[]cylinder perslicesofamountnsliceii

whereth

09 00

30

60

90

120

effic

ienc

y [

][0tdj t bl[F]sliceisdielectricofecapacitancC

[Hz]frequencyf[V]sliceivoltageminimumiUmin

thiD

th

10

28

46

64

82

39

107

176

244 power density

[kWm2]

ozone conc [wt][]CCβ

][0parameteradjustableα

iDiGi

Impact of Power Inductionp

350

400

wer

200

250

300

App

lied

Pow

Arr C 2Arr D +0

Arr E +45Arr F +7

Arr G +3

5 0

100

150

Frac

tion

of

1 2 3 4

ReferenceArr B unstable

Arr C -2

00

50

4Position (1inlet 4outlet)

Experimental Test Rigp g

Experimental Test Rigp g

Outer grounded electrode (left picture) and the dielectric covered inner electrodes (right) d e ect c cove ed e e ect odes ( g t)

Reference (Traditional) Arrangement

Inlet OutletGas flow direction

Optimized Arrangement

Inlet OutletGas flow direction

Intelligent Gap System (IGS)g p y ( )

Molecular Oxygen (O2) Ozone (O3)

O2 O3

yg ( 2) ( 3)

Particle Size SynthesisParticle Size SynthesisByBy--Products Cluster FormationProducts Cluster Formationyy

high diffusion and deposition to surfaces

low diffusion rate good transport

high sedimentation on the structurehigh sedimentation on the structure

Degreacutemont Technologies ndash OzoniaIntelligent Gap SystemIntelligent Gap System

G Vezzuacute JL Lopez A Freilich and K Becker Optimizationof Large-Scale Ozone Generators IEEE Transactions onPlasma Science Vol 37 No 6 p 890-896 (2009)

ConclusionsConclusionsConclusionsConclusionsFundamentals of ozone synthesis in a DBD plasmay p

ndash Highly filamented DBD discharges are best-suitedfor the production of ozone concentrations in therange of 6 to 14 wtrange of 6 to 14 wt

ndash The preferred characteristic of the microdischargesare Townsend-like at reduced electric fields Enaround 190 Townsend

ndash Detrimental side-effects induced by by-productscan be avoided by a proper design of the electrodecan be avoided by a proper design of the electrodearrangement The phenomenon is related to thediffusion rates of formed by-product clusters

ConclusionsConclusionsConclusionsConclusionsBenefits from DBD microplasma tailoring

ndash Reduced power consumption of up to 10 improvement

ndash Increased ozone concentrations of up to 14 now achievable

ndash Improved neutralization and conditioning of detrimental by-products

ndash Reduced system capital and operational cost

New technologies to improve ozone p

generatorg

HV Pulsed Power SwitchingHV Pulsed Power Switching

Microchannel Generation of Ozone

Channel ArrayChannel Array

Microchannel

330 microm 230 microm

Some Cap-DBD Devices Operating in Air

Increase of 60 of

Spacing 225 μmof 60 of plasma

No space

Cap‐DBD ozone generation

bull Ozone concentration is evaluated via Eco S d l UV 100 O A l (0 01Sensors model UV-100 Ozone Analyzer (001 ndash 900 ppm wiht an accuracy of plusmn2)

bull Three reactors 6 tubings 6rdquo with spacings of 0 μm 225 μm and 500 μm running at 3 kV μ μ μ g

SpacingOzone Concentration

3 kV rms 4 kV rms3 kV rms 4 kV rms

0 μm 660 ppm

225 μm 550 ppm

For a device of such small scale these ozone levels are promising

500 μm 380 ppm

J Mahoney W Zhu VS Johnson KH Becker and JL Lopez Electrical and optical emissionmeasurements of a capillary dielectric barrier discharge European Physics Journal D Vol 60 441-447(2010)

QuestionsQuestions

Thank YouFor more informationProf Jose L Lopez PhD

Thank YouFor more informationDepartment of Physics

Telephone (973) 761-9057Email joselopez1shuedu

Website wwwshueduacademicsartsciphysicsWebsite wwwshueduacademicsartsciphysics

Page 21: Dielectric Barrier Discharge (DBD) & Progress in Large ...bonitz/si12/talks/august_8/lopez_si12.pdf · Dielectric Barrier Discharge (DBD) & Progress in Large-Scale Ozone Generation

Faradayrsquos Dielectric CapacitorsFaradayrsquos Dielectric Capacitors

Faradays Dielectric Capacitor (circa 1837)

Michael Faraday (1781 ndash 1867) Capacitance INCREASED

Historical Ozone Tube of W Siemens (1857)Historical Ozone Tube of W Siemens (1857)

Werner v SiemensP d frsquo A l d Ch i d Ph ik 102 66 (1857)Poggendorfrsquos Annalen der Chemie und Physik 102 66 (1857)

ldquoOzone Production in an Atmospheric-PressureDielectric Barrier Dischargerdquo

Dielectric Barrier Discharge

Dielectric Barrier DischargeDielectric - Barrier Discharge ConfigurationsHigh

VoltageAC

Generator

High VoltageElectrode

DielectricBarrier

DielectricBarrier

High VoltageElectrode

Discharge

DischargeGeneratorGround

Electrode

Electrode

GroundElectrode

Discharge

H E Wagner R Brandenburg et al lsquoThe barrier discharge basic properties and applications toHE Wagner R Brandenburg et al The barrier discharge basic properties and applications tosurface treatmentrsquo Vacuum 71 p417-436 (2003)

Typical operational conditions of barrier discharges Typical operational conditions of barrier discharges

Electric field strength E of first breakdown asymp150 Td (p = 1bar T=300 K)

Voltage Vpp 3ndash20 kV

Repetition frequency f 50 Hzndash30 kHz

Pressure p 1ndash3 bar

Gap distance g 02ndash5mm

Dielectric material thickness d 05ndash2mm

Relative dielectric permittivity r 5ndash10 (glass)

B Eliasson and U Kogelschatz IEEE Transactions Plasma Science Vol 19 Issue 6 1063-1077 (1991)B Eliasson and U Kogelschatz IEEE Transactions Plasma Science Vol 19 Issue 6 1063-1077 (1991)

Single and double DBD

Single dielectric Double dielectric

Role of the Dielectric (Insulator)

Th di l t i i th k f thThe dielectric is the key for the properfunctioning of the discharge

Serves two functions

1 Limits the amount of charge transportedby a single microplasma

2 Distributes the microplasmas over theentire electrode surface area

Equivalent Circuit of a Microdischarge

Microdischarge Activity and U-Q Lissajous Figure

B Eliasson and U Kogelschatz IEEE Transactions Plasma Science Vol 19 Issue 6 1063-1077 (1991)

Fundamental Operation of the Dielectric Barrier DischargeFundamental Operation of the Dielectric Barrier Discharge

bull Many of relevant plasma processes that areof importance to achieving our goal occuron time scales that allow us to study themon time scales that allow us to study them

bull Optical emission spectroscopic studies willallow us to determine the temporal andspatial development of important plasmaspatial development of important plasmaspecies such as radicals (OH NO variousoxygen radicals) with high time resolution(less than 10 ns) and a spatial resolution onthe scale of mm in the plasma volumepfollowing pulsed plasma excitation

Time scale of the relevant processes of the DBD

HE Wagner R Brandenburg et al lsquoThe barrier discharge basic properties and applications tosurface treatmentrsquo Vacuum 71 417-436 (2003)

Fundamental Operation of the DBDFundamental Operation of the DBD

Electron DensityTemporal Development (ns)

y

Outer Contour Linen = 1010 cm-3ne = 1010 cm 3

Inner Contour Linene = 1014 cm-3

Streamer Propagation in 1 bar AirAA Kulikovsky IEEE Trans Plasma Sci 25 439-446 (1997)

Numerical Results of Microdischarge Formationin Dielectric Barrier Discharges

Starting Phase of a Microdischarge (1 bar 20 CO2 80 H2)

E0=34 kVcm1010 cm-3

1010 cm-3 ne=1012 cm-3

1mm10 cm

ne=108 cm-3

An electron avalanche propagates towards the anode

Reverse propagationtowards the cathodepropagates towards the anode towards the cathode

Numerical Results of Microdischarge Formationin Dielectric Barrier Discharges

Cathode Layer Formation

E0=34 kVcm1010 cm-39 3 0

1mm

1010 cm-3

10 cmne=109 cm-31014

10131014

1013

10 cm1012

Just before the peak of the total current

Peak currentof the total current

Numerical Results of Microdischarge Formationin Dielectric Barrier Discharges

Local Field Collapse in Area Defined by Surface Discharge

ne=109cm-3 ne=1014 cm-3

Gap

Principals of DBD MicroplasmasPrincipals of DBD MicroplasmasPrincipals of DBD MicroplasmasPrincipals of DBD Microplasmas

C C-- - --- - - CG

CD

-- - - CG

CD

Principals of DBD MicroplasmasPrincipals of DBD MicroplasmasPrincipals of DBD MicroplasmasPrincipals of DBD Microplasmas

Dielectric Barrier Discharge (DBD)Dielectric Barrier Discharge (DBD)Electric Field

B kdBreakdown

Electrons amp Ions Discharge Physics

Excited SpeciesPlasma Chemistry

Chemical Reactions

OzoneGeneration

SurfaceTreatment

PollutionControl

ExcimerFormation CO2 Lasers Hydrogenation

of CO2

Excimer Lamps Plasma Displays

How A Plasma Display Works

How A Plasma Display Work

Plasma Display TelevisionsPlasma Display Televisions

Ozone Generator

3 O 2 O

Dielectric Barrier Discharge

3 O2 2 O3

OO22 OO33++OO22Ondash ndashO3O2

O2O2

Ondash ndash

endash O2Ondash ndash O2endash

O3

O3O2O2 O2

HeatHeatHeatHeat

Properties of Ozone (O3)

T i t i f f Tri-atomic form of oxygen

Most powerful commercial oxidizing agent

Unstable - must be generated and used onsite

Limited solubility in water but more so than oxygenLimited solubility in water but more so than oxygen

Leaves a dissolved residual which ultimately converts back to oxygenconverts back to oxygen

Discharge Tubes in Ozone GeneratorsDischarge Tubes in Ozone Generators

Traditional

Ozone Generator

with Glass Tubes

Generation of OzoneGeneration of Ozone

Generation of OzoneAdvantages of Enamel Dielectrics

Proven Patented Designbull Simplicity

Si l Di l i Cbull Single Dielectric Componentndash Reduced number of Dielectrics

bull Safety ndash Lower operating voltage

(lt 4000 V)bull Reliabilty

ndash Fused Dielectrics ensure continuous production

bull Lowest Power Consumption Operational Savingsndash Operational Savings

Modern Ozone GeneratorModern Ozone Generator

Ozonia Advanced Technology Ozone GeneratorOzone Generator

Generation of OzoneGeneration of Ozone

Generation of Ozone

Power Supply UnitPower Supply Unit

IGBT Inverter CircuitMain Circuit Breaker

HV 480 Volts60 Hz3 Phase Supply

C I

450KVAPow er to

GeneratorFILTER

CONVERTER INVERTERTRANSFORMER

C I450KVA Power Stage

CONTACTOR

bull Latest in Power Semiconductor Technology Modular Design

bull Utilizes IGBTrsquos (Insulated Gate Bi‐Polar Transistors) Converter and Inverter Components

Ozone Water Treatment

B bbl Diff iB bbl Diff iBubble DiffusionBubble Diffusion

Easy to use

Low energy usage Low energy usage

Mass transfer efficiencies to gt 90

Ozone Process Flow DiagramOzone Process Flow DiagramVent to

Atmosphere

O OOxygen

Off-Gas Blower

Ozone Destruct Unit

10 12

O3O2

LOX

10-12 O3

Ozone Generators

Ozone Contact ChamberLOX T k Generators Chamber

VaporizersLOX Tank

Municipal Ozone Installations

Ozonia Installations Ozone Plant Size [lbday] Start-Up DateKey Ozonia Installations (Partial List)

Los Angeles CA 10000 1986Fairfax VA ndash Corbalis 9000 2003MWD CA ndash Mills 9 000 2003

Ozonia Installations Ozone Plant Size [lbday] Start Up Date

MWD CA Mills 9000 2003Fairfax Co VA ndash Griffith 9000 2004MWD CA ndash Jensen 18750 2005Indianapolis IN ndash Belmont AWT 12000 2007I di li IN 12 000 2007Indianapolis IN ndash Southport AWT 12000 2007MWD CA ndash Diemer 13400 2008MWD CA ndash Weymouth 13400 2009

Ozonia North America - Potable Water SummaryTotal Number of Installations 90Total Installed Production gt 265000 lbsdayTotal Installed Production 265000 lbsday

Revision -B

Ozone Water TreatmentOzone Water Treatment

MWD Mills WTP - California

3 3 000 lbsda of o one3 3 000 lbsda of o one3 x 3000 lbsday of ozone3 x 3000 lbsday of ozone

Ozone Water TreatmentOzone Water TreatmentOzone Ozone -- How it worksHow it works

OxidantOxidant DisinfectantDisinfectant

bullbull Breaks double carbon Breaks double carbon bondsbonds

bullbull Kills by cell lysing or Kills by cell lysing or causing the cell wall tocausing the cell wall tobondsbonds

bullbull Creates OHCreates OHbullbull radicals radicals which break higher carbon which break higher carbon

causing the cell wall to causing the cell wall to rupture rupture

bullbull AttacksAttacks allall bacteriabacteriabondsbondsbullbull Increased temp and pH Increased temp and pH

accelerates Oaccelerates O33

Attacks Attacks allall bacteria bacteria virus cysts and spores virus cysts and spores in varying degreesin varying degreesaccelerates Oaccelerates O33

decomposition to OHdecomposition to OHbullbull

Micro-organism DNA

Capsule AdenineAdenine

Cell wall ThymineThymine

CytosineCytosine

GuanineGuanine

NuclearmaterialCellmembrane

material

Typical Bacterium DNA

Microbial Growth at Various Ozone ConcentrationsConcentrations

Growth likely

Growth possibleGrowth possible

NO GROWTH

0004 0008 0012 0016 0020

Ozone concentration (mgl)Ozone concentration (mgl)

Typical Water Treatment UsageTypical Water Treatment Usage

Application O3 mgl Contact timeUltra Pure Water 005 - 025 sec ndash min

Water bottling 04 ndash 10 5 ndash 10 min

Swimming pools ampspas

01 ndash 075 4 minutes

Potable taste amp odor 15 ndash 50 5 ndash 10 mindisinfection

Microfloculation 10 ndash 30 5 ndash 10 min

Lignin amp tammin 3 0 10 0 10 30 minLignin amp tamminremoval

30 ndash 100 10 ndash 30 min

Municipal wastewater 50 ndash 150+ 15 ndash 30 min

Ozone Water TreatmentOzone Water TreatmentOzone Ozone ndashndash Municipal ApplicationsMunicipal Applications

bullbull Taste and OdorTaste and Odor

bullbull Color RemovalColor Removal

bullbull Disinfection Without Trihalomethanes (THMs)Disinfection Without Trihalomethanes (THMs)

bullbull Improved Filtration Efficiency and FlocculationImproved Filtration Efficiency and Flocculation

bullbull Cryptosporidium DeactivationCryptosporidium Deactivation

bullbull Giardia amp Virus InactivationGiardia amp Virus Inactivation

bullbull Oxidation Oxidation -- Organics Fe amp MnOrganics Fe amp Mn

bullbull Wastewater disinfectionWastewater disinfection

bullbull BOD COD and TOC reductionBOD COD and TOC reduction

Applications of Ozone

Wastewater Treatmentbull Disinfection of Secondary and Tertiary Effluentsbull Color Reductionbull Color Reductionbull TOC Oxidation (Industrial)bull Oxidation of Odor Causing Compoundsbull Oxidation of Endocrine Disruptors (EDCrsquos) and p ( )

Pharmaceutically Active Compounds (PACrsquos)

Applications of Ozone

What are Endocrine Disruptors (EDCrsquos) and What are Endocrine Disruptors (EDCrsquos) and Ph ti ll A ti C d (PACrsquo )Ph ti ll A ti C d (PACrsquo )Pharmaceutically Active Compounds (PACrsquos)Pharmaceutically Active Compounds (PACrsquos)

bullbull EDCrsquosEDCrsquos andand PACrsquosPACrsquos areare NaturallyNaturally andand SyntheticSyntheticdd th tth t ff tff t thth b lb l llcompoundscompounds thatthat maymay affectaffect thethe balancebalance oror normalnormal

functionsfunctions inin animalsanimals andand humanshumans

What can EDCrsquos and PACrsquos doWhat can EDCrsquos and PACrsquos do

bullbull Even in very small concentrations these compounds Even in very small concentrations these compounds y py pcan can disruptdisrupt normal bodily functionsnormal bodily functions

bullbull ManMan--made chemicals can trick the bodies endocrine made chemicals can trick the bodies endocrine system system

Applications of Ozone

Examples of Endocrine Disruptors1000rsquos of compounds that may be Investigated as EDCs ndash Some examples are

bullbull Synthetic HormonesSynthetic Hormonesbullbull Naturally Occurring Estrogens Naturally Occurring Estrogens

Health and Beauty AidsHealth and Beauty Aidsbullbull Health and Beauty AidsHealth and Beauty Aidsbullbull SolventsSolventsbullbull PesticidesPesticidesbullbull SurfactantsSurfactantsbullbull PlasticsPlastics

F i idF i idbullbull FungicidesFungicides

Ozone Water TreatmentOzone Water Treatment

Ozone Ozone -- Industrial ApplicationsIndustrial Applications-- Ultrapure Water for Pharmaceutical ApplicationsUltrapure Water for Pharmaceutical Applications

-- Wastewater disinfection color removalWastewater disinfection color removal

-- Soil and Groundwater Remediation Soil and Groundwater Remediation

-- Cooling Tower Water TreatmentCooling Tower Water Treatment

-- Food ProcessingFood Processing

-- Aquaculture AquariumsAquaculture AquariumsAquaculture AquariumsAquaculture Aquariums

-- Beverage ApplicationsBeverage Applications

P l amp P Bl hiP l amp P Bl hi-- Pulp amp Paper BleachingPulp amp Paper Bleaching

High Purity OzonationHigh Purity Ozonation

Microchip manufacturingMicrochip manufacturing

What are the current issues in large-scale gozone generationg

Experimental Setup

Front view of the two units after the redesign and reworking ofthe gas water and instruments connectionsthe gas water and instruments connections

Experimental Setup

Top view of the twoexperimental unitsexperimental unitsSpectroscope (notshown) is to the left ofthe DBD The units weredifferent with respect todifferent with respect totheir electrodes onehad only the electrodecoated with thedielectric (ldquosingle-dielectric ( single-coatedrdquo) the other onehad the electrode andthe anode coated withthe dielectric (ldquodouble-the dielectric ( double-coatedrdquo)

Basics Generation of OzoneBasics Generation of Ozone

SpectroscopyPlasma

Plasma Absorption SpectroscopyPlasma Absorption Spectroscopy

Infrared Absorption SpectroscopyInfrared Absorption Spectroscopy

IR spectra in pure oxygen (black curve) and at approximately 10wt N2 admixture (red line) N2O5 peaks appear at124 1 d 1 2 11245 cm-1 and at 1725 cm-1

Infrared Absorption SpectroscopyInfrared Absorption Spectroscopy

IR spectra of several methane variations The green curve envelopes all of the methane peaks at 1325 cm-1recorded at smaller methane admixtures Simultaneously the N2O5 peaks disappear as the methane peaks appear

N2O5 FormationN2O5 Formation2 52 5p=2 bara cwt=20degC q=35kWm2 f=1450Hz

45N2O5 AT95

30

35

40

N

2 B

lend

ing

N2O AT95N2O5 IGSN2O IGSN2O5 LGN2O LG

1 5

20

25

nt [p

pmV]

3

wt

05

10

15

NO

x co

nten

005 7 9 11 13 15 17

ozone conc [wt]

Amount of formed N2O5 and N2O as a function of ozone concentration at 3 wt of nitrogen admixture and fori l dvarious electrode arrangements

Plasma Emission SpectroscopyPlasma Emission Spectroscopyp pyp py

Relative Emissions of the Ozonizer plasmaRelative Emissions of the Ozonizer plasma

Region 300- 850 nm from individual (calibrated) regions (smoothed by PeakFit) Single-coated ozone generator Inlet side

3 5E+06

30E+06

35E+06

7 9

20E+06

25E+06

nten

sity

au

2

311 12

10E+06

15E+06

In 4

5

6 8 10

14

15

16

17

00E+00

50E+05

280 300 320 340 360 380 400 420 440 460 480 500 520 540 560 580 600 620 640 660 680 700 720 740 760 780 800 820 840 860

Wavelength nm

1 13

Wavelength nm

Absolute Emission of the DBD PlasmaAbsolute Emission of the DBD Plasma

Intensities in (O2+3 wtN2) plasma

1 20E+04

100E+04

120E+04

600E+03

800E+03

nten

sity

(au

)

200E+03

400E+03

In

O(777)

000E+00200 250 300 350 400 450 500 550 600 650 700 750 800 850

Wavelength nm

Intensities in 3 wtN2+O2 plasmaIntensities in 3 wtN2+O2 plasma

Plasma Chemistry in OzonizersPlasma Chemistry in Ozonizers

Dry Air O2 N2

e - e -

O N2 N O2

O3 NO

O2 N O2

O3

N

3

NO2

O2 O3

NO

N

NO2 O3

N2O

NO3 N

N2O4

NO2

NO2

N2O5

NO3

Primary electron-driven chemical reactions leading to the formation of N2O5 and N2O in a dry air plasma

Plasma emission diagnostics role of N2Plasma emission diagnostics role of N2

Dry Air O2 N2

e - e -

O N2 N O2

O3 NO

O2 N O2

O3

O

N

ON

NO2

O2O3

N

NO N

NO2 O3

N2O

NO3 N

N2O4

NO2

NO2

N2O5

NO3

ONbullWith N2 present ndash less oxygen atoms are formed However the difference in intensity is

very small

Modeling of plasma chemistry incl the NxOy chemistry up to N2O5 for different Oxygen Nitrogen mixtures varying power deposition scenarios

and initial ozone background concentrations (up to 15) previously done

The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation

The role of N2 must be related to its by-products reacting on the surface of the electrodeThe role of N2 must be related to its by-products reacting on the surface of the electrode

The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established

Ab 8 t f O

The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established

Ab 8 t f OAbove 8 wt of O3

1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)

Above 8 wt of O3

1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)case without pampp)

2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of the

case without pampp)

2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of thethem A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface

them A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface

The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation

Three possibilities have to be considered for the oxygen-fedozone generator

Three possibilities have to be considered for the oxygen-fedozone generatorozone generator

bull Excited N2 molecules lead to an increased O2 dissociation in

ozone generator

bull Excited N2 molecules lead to an increased O2 dissociation in2 2such case an increased efficiency is correlated to the N2admixture

2 2such case an increased efficiency is correlated to the N2admixture

bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial

bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial

bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2

bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2g p g 3 pp y 2g p g 3 pp y 2

Effect of methane on ozone efficiency and specific powerEffect of methane on ozone efficiency and specific power

Effect of Methane on Ozone Content in Outlet Gas and on Specific Power Pure O2

13 12

10

11

12

t 8

10

8

9

10

ne c

onte

nt w

t

6

8

ecifi

c po

wer

kW

hlb

5

6

7

Ozo

n

2

4 Spe

400E+00 20E+03 40E+03 60E+03 80E+03 10E+04 12E+04

Methane in feedgas ppm

0

Ozone content in the outlet gas Specif ic pow er of the ozone generatorg p p g

Effects of N2 and CH4Effects of N2 and CH4

Pi t f h t lli N O t tPicture of an amorphous-crystalline N2O5 structurecaptured at the Orlando Skylake water plant in 2006

Plasma Chemistry with CH4 Impurities

OxygenO2 N2

e - e -

CHO N2

NO2

O NO

O2 N O2 O3

NOH

CH4e-

O3 NO

NO2

O2O3NO N

NO2 O

NO2

NO2

N2ONO3

N

O3

NO2

NO

HNO3

N2O4

N2O5

NO2

NO3

N2O5

Effect of methane on the electrode surfaces

a) b)

Inlet Outlet Outlet

) d)

I l t I l t

c) d)

Electrode of the ozone generator afterseveral hours in CH8O2 and up to 2 wt of methane (a b c)

Inlet Inlet

three hours in CH8O2+traces of N2 and up to 1 wt of methane (d) Visible change of discharge character at about 13 length of electrode (a d)

Kinetics of CHx Conversion without N2

conversion by collisions

O2 + CHx 12wt O3 + CO2 +H2O

deposition vaporizationby sputtering

ibl b l 1000 CHreversible process below 1000ppm CH4

Effect of water on electrode surface with N2

Inlet

OutletOutlet

Electrode of the ozone generator after several hours in H OO N

Inlet

Electrode of the ozone generator after several hours in H2OO2N2

Effect of water on electrode surface

Long term effect (800 hrs) of H2OO2N2

Kinetics of CHx Conversion with N2

conversion by collisionsHNO3 formation

O2 + N2 +CHx 12wtO2 + CO2 +H2O + HNO3

deposition vaporizationby sputtering

H2O + HNO3

by sputtering

irreversible process above a N2 threshold () ltlt 1000ppm N2

sticky deposit

p 2 ( ) pp 2 any CH4 concentration (60ppm)

Plasma Chemistry with CH4 ImpuritiesPlasma Chemistry with CH4 Impurities4

bull Formation of NO and NO2 depends on O3 N2 and gas temperature Conclusion N2 admixture is the key factor

SummarySummaryyyThe mechanisms of formed NOx by-products follows the sameThe mechanisms of formed NOx by-products follows the sameprinciples as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentration

principles as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentrationozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)

ozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)g p ( g p )

The conversion of methane to OH and H2O is found to depend on

g p ( g p )

The conversion of methane to OH and H2O is found to depend ondissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)

dissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)discharge gap)discharge gap)

How do you optimize an ozone generatorg

Scientific ApproachScientific ApproachTheoretical Experimental

pppp

c [wt]

f [Hz]

c [wt]

f [Hz]

[kW]UUUβ1

1Cf4αPn

1iiminpeakimin

iiD

q [kWm2]q [kWm2]

150

180

][V]voltagepeakUpeak

[]cylinder perslicesofamountnsliceii

whereth

09 00

30

60

90

120

effic

ienc

y [

][0tdj t bl[F]sliceisdielectricofecapacitancC

[Hz]frequencyf[V]sliceivoltageminimumiUmin

thiD

th

10

28

46

64

82

39

107

176

244 power density

[kWm2]

ozone conc [wt][]CCβ

][0parameteradjustableα

iDiGi

Impact of Power Inductionp

350

400

wer

200

250

300

App

lied

Pow

Arr C 2Arr D +0

Arr E +45Arr F +7

Arr G +3

5 0

100

150

Frac

tion

of

1 2 3 4

ReferenceArr B unstable

Arr C -2

00

50

4Position (1inlet 4outlet)

Experimental Test Rigp g

Experimental Test Rigp g

Outer grounded electrode (left picture) and the dielectric covered inner electrodes (right) d e ect c cove ed e e ect odes ( g t)

Reference (Traditional) Arrangement

Inlet OutletGas flow direction

Optimized Arrangement

Inlet OutletGas flow direction

Intelligent Gap System (IGS)g p y ( )

Molecular Oxygen (O2) Ozone (O3)

O2 O3

yg ( 2) ( 3)

Particle Size SynthesisParticle Size SynthesisByBy--Products Cluster FormationProducts Cluster Formationyy

high diffusion and deposition to surfaces

low diffusion rate good transport

high sedimentation on the structurehigh sedimentation on the structure

Degreacutemont Technologies ndash OzoniaIntelligent Gap SystemIntelligent Gap System

G Vezzuacute JL Lopez A Freilich and K Becker Optimizationof Large-Scale Ozone Generators IEEE Transactions onPlasma Science Vol 37 No 6 p 890-896 (2009)

ConclusionsConclusionsConclusionsConclusionsFundamentals of ozone synthesis in a DBD plasmay p

ndash Highly filamented DBD discharges are best-suitedfor the production of ozone concentrations in therange of 6 to 14 wtrange of 6 to 14 wt

ndash The preferred characteristic of the microdischargesare Townsend-like at reduced electric fields Enaround 190 Townsend

ndash Detrimental side-effects induced by by-productscan be avoided by a proper design of the electrodecan be avoided by a proper design of the electrodearrangement The phenomenon is related to thediffusion rates of formed by-product clusters

ConclusionsConclusionsConclusionsConclusionsBenefits from DBD microplasma tailoring

ndash Reduced power consumption of up to 10 improvement

ndash Increased ozone concentrations of up to 14 now achievable

ndash Improved neutralization and conditioning of detrimental by-products

ndash Reduced system capital and operational cost

New technologies to improve ozone p

generatorg

HV Pulsed Power SwitchingHV Pulsed Power Switching

Microchannel Generation of Ozone

Channel ArrayChannel Array

Microchannel

330 microm 230 microm

Some Cap-DBD Devices Operating in Air

Increase of 60 of

Spacing 225 μmof 60 of plasma

No space

Cap‐DBD ozone generation

bull Ozone concentration is evaluated via Eco S d l UV 100 O A l (0 01Sensors model UV-100 Ozone Analyzer (001 ndash 900 ppm wiht an accuracy of plusmn2)

bull Three reactors 6 tubings 6rdquo with spacings of 0 μm 225 μm and 500 μm running at 3 kV μ μ μ g

SpacingOzone Concentration

3 kV rms 4 kV rms3 kV rms 4 kV rms

0 μm 660 ppm

225 μm 550 ppm

For a device of such small scale these ozone levels are promising

500 μm 380 ppm

J Mahoney W Zhu VS Johnson KH Becker and JL Lopez Electrical and optical emissionmeasurements of a capillary dielectric barrier discharge European Physics Journal D Vol 60 441-447(2010)

QuestionsQuestions

Thank YouFor more informationProf Jose L Lopez PhD

Thank YouFor more informationDepartment of Physics

Telephone (973) 761-9057Email joselopez1shuedu

Website wwwshueduacademicsartsciphysicsWebsite wwwshueduacademicsartsciphysics

Page 22: Dielectric Barrier Discharge (DBD) & Progress in Large ...bonitz/si12/talks/august_8/lopez_si12.pdf · Dielectric Barrier Discharge (DBD) & Progress in Large-Scale Ozone Generation

Historical Ozone Tube of W Siemens (1857)Historical Ozone Tube of W Siemens (1857)

Werner v SiemensP d frsquo A l d Ch i d Ph ik 102 66 (1857)Poggendorfrsquos Annalen der Chemie und Physik 102 66 (1857)

ldquoOzone Production in an Atmospheric-PressureDielectric Barrier Dischargerdquo

Dielectric Barrier Discharge

Dielectric Barrier DischargeDielectric - Barrier Discharge ConfigurationsHigh

VoltageAC

Generator

High VoltageElectrode

DielectricBarrier

DielectricBarrier

High VoltageElectrode

Discharge

DischargeGeneratorGround

Electrode

Electrode

GroundElectrode

Discharge

H E Wagner R Brandenburg et al lsquoThe barrier discharge basic properties and applications toHE Wagner R Brandenburg et al The barrier discharge basic properties and applications tosurface treatmentrsquo Vacuum 71 p417-436 (2003)

Typical operational conditions of barrier discharges Typical operational conditions of barrier discharges

Electric field strength E of first breakdown asymp150 Td (p = 1bar T=300 K)

Voltage Vpp 3ndash20 kV

Repetition frequency f 50 Hzndash30 kHz

Pressure p 1ndash3 bar

Gap distance g 02ndash5mm

Dielectric material thickness d 05ndash2mm

Relative dielectric permittivity r 5ndash10 (glass)

B Eliasson and U Kogelschatz IEEE Transactions Plasma Science Vol 19 Issue 6 1063-1077 (1991)B Eliasson and U Kogelschatz IEEE Transactions Plasma Science Vol 19 Issue 6 1063-1077 (1991)

Single and double DBD

Single dielectric Double dielectric

Role of the Dielectric (Insulator)

Th di l t i i th k f thThe dielectric is the key for the properfunctioning of the discharge

Serves two functions

1 Limits the amount of charge transportedby a single microplasma

2 Distributes the microplasmas over theentire electrode surface area

Equivalent Circuit of a Microdischarge

Microdischarge Activity and U-Q Lissajous Figure

B Eliasson and U Kogelschatz IEEE Transactions Plasma Science Vol 19 Issue 6 1063-1077 (1991)

Fundamental Operation of the Dielectric Barrier DischargeFundamental Operation of the Dielectric Barrier Discharge

bull Many of relevant plasma processes that areof importance to achieving our goal occuron time scales that allow us to study themon time scales that allow us to study them

bull Optical emission spectroscopic studies willallow us to determine the temporal andspatial development of important plasmaspatial development of important plasmaspecies such as radicals (OH NO variousoxygen radicals) with high time resolution(less than 10 ns) and a spatial resolution onthe scale of mm in the plasma volumepfollowing pulsed plasma excitation

Time scale of the relevant processes of the DBD

HE Wagner R Brandenburg et al lsquoThe barrier discharge basic properties and applications tosurface treatmentrsquo Vacuum 71 417-436 (2003)

Fundamental Operation of the DBDFundamental Operation of the DBD

Electron DensityTemporal Development (ns)

y

Outer Contour Linen = 1010 cm-3ne = 1010 cm 3

Inner Contour Linene = 1014 cm-3

Streamer Propagation in 1 bar AirAA Kulikovsky IEEE Trans Plasma Sci 25 439-446 (1997)

Numerical Results of Microdischarge Formationin Dielectric Barrier Discharges

Starting Phase of a Microdischarge (1 bar 20 CO2 80 H2)

E0=34 kVcm1010 cm-3

1010 cm-3 ne=1012 cm-3

1mm10 cm

ne=108 cm-3

An electron avalanche propagates towards the anode

Reverse propagationtowards the cathodepropagates towards the anode towards the cathode

Numerical Results of Microdischarge Formationin Dielectric Barrier Discharges

Cathode Layer Formation

E0=34 kVcm1010 cm-39 3 0

1mm

1010 cm-3

10 cmne=109 cm-31014

10131014

1013

10 cm1012

Just before the peak of the total current

Peak currentof the total current

Numerical Results of Microdischarge Formationin Dielectric Barrier Discharges

Local Field Collapse in Area Defined by Surface Discharge

ne=109cm-3 ne=1014 cm-3

Gap

Principals of DBD MicroplasmasPrincipals of DBD MicroplasmasPrincipals of DBD MicroplasmasPrincipals of DBD Microplasmas

C C-- - --- - - CG

CD

-- - - CG

CD

Principals of DBD MicroplasmasPrincipals of DBD MicroplasmasPrincipals of DBD MicroplasmasPrincipals of DBD Microplasmas

Dielectric Barrier Discharge (DBD)Dielectric Barrier Discharge (DBD)Electric Field

B kdBreakdown

Electrons amp Ions Discharge Physics

Excited SpeciesPlasma Chemistry

Chemical Reactions

OzoneGeneration

SurfaceTreatment

PollutionControl

ExcimerFormation CO2 Lasers Hydrogenation

of CO2

Excimer Lamps Plasma Displays

How A Plasma Display Works

How A Plasma Display Work

Plasma Display TelevisionsPlasma Display Televisions

Ozone Generator

3 O 2 O

Dielectric Barrier Discharge

3 O2 2 O3

OO22 OO33++OO22Ondash ndashO3O2

O2O2

Ondash ndash

endash O2Ondash ndash O2endash

O3

O3O2O2 O2

HeatHeatHeatHeat

Properties of Ozone (O3)

T i t i f f Tri-atomic form of oxygen

Most powerful commercial oxidizing agent

Unstable - must be generated and used onsite

Limited solubility in water but more so than oxygenLimited solubility in water but more so than oxygen

Leaves a dissolved residual which ultimately converts back to oxygenconverts back to oxygen

Discharge Tubes in Ozone GeneratorsDischarge Tubes in Ozone Generators

Traditional

Ozone Generator

with Glass Tubes

Generation of OzoneGeneration of Ozone

Generation of OzoneAdvantages of Enamel Dielectrics

Proven Patented Designbull Simplicity

Si l Di l i Cbull Single Dielectric Componentndash Reduced number of Dielectrics

bull Safety ndash Lower operating voltage

(lt 4000 V)bull Reliabilty

ndash Fused Dielectrics ensure continuous production

bull Lowest Power Consumption Operational Savingsndash Operational Savings

Modern Ozone GeneratorModern Ozone Generator

Ozonia Advanced Technology Ozone GeneratorOzone Generator

Generation of OzoneGeneration of Ozone

Generation of Ozone

Power Supply UnitPower Supply Unit

IGBT Inverter CircuitMain Circuit Breaker

HV 480 Volts60 Hz3 Phase Supply

C I

450KVAPow er to

GeneratorFILTER

CONVERTER INVERTERTRANSFORMER

C I450KVA Power Stage

CONTACTOR

bull Latest in Power Semiconductor Technology Modular Design

bull Utilizes IGBTrsquos (Insulated Gate Bi‐Polar Transistors) Converter and Inverter Components

Ozone Water Treatment

B bbl Diff iB bbl Diff iBubble DiffusionBubble Diffusion

Easy to use

Low energy usage Low energy usage

Mass transfer efficiencies to gt 90

Ozone Process Flow DiagramOzone Process Flow DiagramVent to

Atmosphere

O OOxygen

Off-Gas Blower

Ozone Destruct Unit

10 12

O3O2

LOX

10-12 O3

Ozone Generators

Ozone Contact ChamberLOX T k Generators Chamber

VaporizersLOX Tank

Municipal Ozone Installations

Ozonia Installations Ozone Plant Size [lbday] Start-Up DateKey Ozonia Installations (Partial List)

Los Angeles CA 10000 1986Fairfax VA ndash Corbalis 9000 2003MWD CA ndash Mills 9 000 2003

Ozonia Installations Ozone Plant Size [lbday] Start Up Date

MWD CA Mills 9000 2003Fairfax Co VA ndash Griffith 9000 2004MWD CA ndash Jensen 18750 2005Indianapolis IN ndash Belmont AWT 12000 2007I di li IN 12 000 2007Indianapolis IN ndash Southport AWT 12000 2007MWD CA ndash Diemer 13400 2008MWD CA ndash Weymouth 13400 2009

Ozonia North America - Potable Water SummaryTotal Number of Installations 90Total Installed Production gt 265000 lbsdayTotal Installed Production 265000 lbsday

Revision -B

Ozone Water TreatmentOzone Water Treatment

MWD Mills WTP - California

3 3 000 lbsda of o one3 3 000 lbsda of o one3 x 3000 lbsday of ozone3 x 3000 lbsday of ozone

Ozone Water TreatmentOzone Water TreatmentOzone Ozone -- How it worksHow it works

OxidantOxidant DisinfectantDisinfectant

bullbull Breaks double carbon Breaks double carbon bondsbonds

bullbull Kills by cell lysing or Kills by cell lysing or causing the cell wall tocausing the cell wall tobondsbonds

bullbull Creates OHCreates OHbullbull radicals radicals which break higher carbon which break higher carbon

causing the cell wall to causing the cell wall to rupture rupture

bullbull AttacksAttacks allall bacteriabacteriabondsbondsbullbull Increased temp and pH Increased temp and pH

accelerates Oaccelerates O33

Attacks Attacks allall bacteria bacteria virus cysts and spores virus cysts and spores in varying degreesin varying degreesaccelerates Oaccelerates O33

decomposition to OHdecomposition to OHbullbull

Micro-organism DNA

Capsule AdenineAdenine

Cell wall ThymineThymine

CytosineCytosine

GuanineGuanine

NuclearmaterialCellmembrane

material

Typical Bacterium DNA

Microbial Growth at Various Ozone ConcentrationsConcentrations

Growth likely

Growth possibleGrowth possible

NO GROWTH

0004 0008 0012 0016 0020

Ozone concentration (mgl)Ozone concentration (mgl)

Typical Water Treatment UsageTypical Water Treatment Usage

Application O3 mgl Contact timeUltra Pure Water 005 - 025 sec ndash min

Water bottling 04 ndash 10 5 ndash 10 min

Swimming pools ampspas

01 ndash 075 4 minutes

Potable taste amp odor 15 ndash 50 5 ndash 10 mindisinfection

Microfloculation 10 ndash 30 5 ndash 10 min

Lignin amp tammin 3 0 10 0 10 30 minLignin amp tamminremoval

30 ndash 100 10 ndash 30 min

Municipal wastewater 50 ndash 150+ 15 ndash 30 min

Ozone Water TreatmentOzone Water TreatmentOzone Ozone ndashndash Municipal ApplicationsMunicipal Applications

bullbull Taste and OdorTaste and Odor

bullbull Color RemovalColor Removal

bullbull Disinfection Without Trihalomethanes (THMs)Disinfection Without Trihalomethanes (THMs)

bullbull Improved Filtration Efficiency and FlocculationImproved Filtration Efficiency and Flocculation

bullbull Cryptosporidium DeactivationCryptosporidium Deactivation

bullbull Giardia amp Virus InactivationGiardia amp Virus Inactivation

bullbull Oxidation Oxidation -- Organics Fe amp MnOrganics Fe amp Mn

bullbull Wastewater disinfectionWastewater disinfection

bullbull BOD COD and TOC reductionBOD COD and TOC reduction

Applications of Ozone

Wastewater Treatmentbull Disinfection of Secondary and Tertiary Effluentsbull Color Reductionbull Color Reductionbull TOC Oxidation (Industrial)bull Oxidation of Odor Causing Compoundsbull Oxidation of Endocrine Disruptors (EDCrsquos) and p ( )

Pharmaceutically Active Compounds (PACrsquos)

Applications of Ozone

What are Endocrine Disruptors (EDCrsquos) and What are Endocrine Disruptors (EDCrsquos) and Ph ti ll A ti C d (PACrsquo )Ph ti ll A ti C d (PACrsquo )Pharmaceutically Active Compounds (PACrsquos)Pharmaceutically Active Compounds (PACrsquos)

bullbull EDCrsquosEDCrsquos andand PACrsquosPACrsquos areare NaturallyNaturally andand SyntheticSyntheticdd th tth t ff tff t thth b lb l llcompoundscompounds thatthat maymay affectaffect thethe balancebalance oror normalnormal

functionsfunctions inin animalsanimals andand humanshumans

What can EDCrsquos and PACrsquos doWhat can EDCrsquos and PACrsquos do

bullbull Even in very small concentrations these compounds Even in very small concentrations these compounds y py pcan can disruptdisrupt normal bodily functionsnormal bodily functions

bullbull ManMan--made chemicals can trick the bodies endocrine made chemicals can trick the bodies endocrine system system

Applications of Ozone

Examples of Endocrine Disruptors1000rsquos of compounds that may be Investigated as EDCs ndash Some examples are

bullbull Synthetic HormonesSynthetic Hormonesbullbull Naturally Occurring Estrogens Naturally Occurring Estrogens

Health and Beauty AidsHealth and Beauty Aidsbullbull Health and Beauty AidsHealth and Beauty Aidsbullbull SolventsSolventsbullbull PesticidesPesticidesbullbull SurfactantsSurfactantsbullbull PlasticsPlastics

F i idF i idbullbull FungicidesFungicides

Ozone Water TreatmentOzone Water Treatment

Ozone Ozone -- Industrial ApplicationsIndustrial Applications-- Ultrapure Water for Pharmaceutical ApplicationsUltrapure Water for Pharmaceutical Applications

-- Wastewater disinfection color removalWastewater disinfection color removal

-- Soil and Groundwater Remediation Soil and Groundwater Remediation

-- Cooling Tower Water TreatmentCooling Tower Water Treatment

-- Food ProcessingFood Processing

-- Aquaculture AquariumsAquaculture AquariumsAquaculture AquariumsAquaculture Aquariums

-- Beverage ApplicationsBeverage Applications

P l amp P Bl hiP l amp P Bl hi-- Pulp amp Paper BleachingPulp amp Paper Bleaching

High Purity OzonationHigh Purity Ozonation

Microchip manufacturingMicrochip manufacturing

What are the current issues in large-scale gozone generationg

Experimental Setup

Front view of the two units after the redesign and reworking ofthe gas water and instruments connectionsthe gas water and instruments connections

Experimental Setup

Top view of the twoexperimental unitsexperimental unitsSpectroscope (notshown) is to the left ofthe DBD The units weredifferent with respect todifferent with respect totheir electrodes onehad only the electrodecoated with thedielectric (ldquosingle-dielectric ( single-coatedrdquo) the other onehad the electrode andthe anode coated withthe dielectric (ldquodouble-the dielectric ( double-coatedrdquo)

Basics Generation of OzoneBasics Generation of Ozone

SpectroscopyPlasma

Plasma Absorption SpectroscopyPlasma Absorption Spectroscopy

Infrared Absorption SpectroscopyInfrared Absorption Spectroscopy

IR spectra in pure oxygen (black curve) and at approximately 10wt N2 admixture (red line) N2O5 peaks appear at124 1 d 1 2 11245 cm-1 and at 1725 cm-1

Infrared Absorption SpectroscopyInfrared Absorption Spectroscopy

IR spectra of several methane variations The green curve envelopes all of the methane peaks at 1325 cm-1recorded at smaller methane admixtures Simultaneously the N2O5 peaks disappear as the methane peaks appear

N2O5 FormationN2O5 Formation2 52 5p=2 bara cwt=20degC q=35kWm2 f=1450Hz

45N2O5 AT95

30

35

40

N

2 B

lend

ing

N2O AT95N2O5 IGSN2O IGSN2O5 LGN2O LG

1 5

20

25

nt [p

pmV]

3

wt

05

10

15

NO

x co

nten

005 7 9 11 13 15 17

ozone conc [wt]

Amount of formed N2O5 and N2O as a function of ozone concentration at 3 wt of nitrogen admixture and fori l dvarious electrode arrangements

Plasma Emission SpectroscopyPlasma Emission Spectroscopyp pyp py

Relative Emissions of the Ozonizer plasmaRelative Emissions of the Ozonizer plasma

Region 300- 850 nm from individual (calibrated) regions (smoothed by PeakFit) Single-coated ozone generator Inlet side

3 5E+06

30E+06

35E+06

7 9

20E+06

25E+06

nten

sity

au

2

311 12

10E+06

15E+06

In 4

5

6 8 10

14

15

16

17

00E+00

50E+05

280 300 320 340 360 380 400 420 440 460 480 500 520 540 560 580 600 620 640 660 680 700 720 740 760 780 800 820 840 860

Wavelength nm

1 13

Wavelength nm

Absolute Emission of the DBD PlasmaAbsolute Emission of the DBD Plasma

Intensities in (O2+3 wtN2) plasma

1 20E+04

100E+04

120E+04

600E+03

800E+03

nten

sity

(au

)

200E+03

400E+03

In

O(777)

000E+00200 250 300 350 400 450 500 550 600 650 700 750 800 850

Wavelength nm

Intensities in 3 wtN2+O2 plasmaIntensities in 3 wtN2+O2 plasma

Plasma Chemistry in OzonizersPlasma Chemistry in Ozonizers

Dry Air O2 N2

e - e -

O N2 N O2

O3 NO

O2 N O2

O3

N

3

NO2

O2 O3

NO

N

NO2 O3

N2O

NO3 N

N2O4

NO2

NO2

N2O5

NO3

Primary electron-driven chemical reactions leading to the formation of N2O5 and N2O in a dry air plasma

Plasma emission diagnostics role of N2Plasma emission diagnostics role of N2

Dry Air O2 N2

e - e -

O N2 N O2

O3 NO

O2 N O2

O3

O

N

ON

NO2

O2O3

N

NO N

NO2 O3

N2O

NO3 N

N2O4

NO2

NO2

N2O5

NO3

ONbullWith N2 present ndash less oxygen atoms are formed However the difference in intensity is

very small

Modeling of plasma chemistry incl the NxOy chemistry up to N2O5 for different Oxygen Nitrogen mixtures varying power deposition scenarios

and initial ozone background concentrations (up to 15) previously done

The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation

The role of N2 must be related to its by-products reacting on the surface of the electrodeThe role of N2 must be related to its by-products reacting on the surface of the electrode

The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established

Ab 8 t f O

The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established

Ab 8 t f OAbove 8 wt of O3

1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)

Above 8 wt of O3

1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)case without pampp)

2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of the

case without pampp)

2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of thethem A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface

them A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface

The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation

Three possibilities have to be considered for the oxygen-fedozone generator

Three possibilities have to be considered for the oxygen-fedozone generatorozone generator

bull Excited N2 molecules lead to an increased O2 dissociation in

ozone generator

bull Excited N2 molecules lead to an increased O2 dissociation in2 2such case an increased efficiency is correlated to the N2admixture

2 2such case an increased efficiency is correlated to the N2admixture

bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial

bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial

bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2

bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2g p g 3 pp y 2g p g 3 pp y 2

Effect of methane on ozone efficiency and specific powerEffect of methane on ozone efficiency and specific power

Effect of Methane on Ozone Content in Outlet Gas and on Specific Power Pure O2

13 12

10

11

12

t 8

10

8

9

10

ne c

onte

nt w

t

6

8

ecifi

c po

wer

kW

hlb

5

6

7

Ozo

n

2

4 Spe

400E+00 20E+03 40E+03 60E+03 80E+03 10E+04 12E+04

Methane in feedgas ppm

0

Ozone content in the outlet gas Specif ic pow er of the ozone generatorg p p g

Effects of N2 and CH4Effects of N2 and CH4

Pi t f h t lli N O t tPicture of an amorphous-crystalline N2O5 structurecaptured at the Orlando Skylake water plant in 2006

Plasma Chemistry with CH4 Impurities

OxygenO2 N2

e - e -

CHO N2

NO2

O NO

O2 N O2 O3

NOH

CH4e-

O3 NO

NO2

O2O3NO N

NO2 O

NO2

NO2

N2ONO3

N

O3

NO2

NO

HNO3

N2O4

N2O5

NO2

NO3

N2O5

Effect of methane on the electrode surfaces

a) b)

Inlet Outlet Outlet

) d)

I l t I l t

c) d)

Electrode of the ozone generator afterseveral hours in CH8O2 and up to 2 wt of methane (a b c)

Inlet Inlet

three hours in CH8O2+traces of N2 and up to 1 wt of methane (d) Visible change of discharge character at about 13 length of electrode (a d)

Kinetics of CHx Conversion without N2

conversion by collisions

O2 + CHx 12wt O3 + CO2 +H2O

deposition vaporizationby sputtering

ibl b l 1000 CHreversible process below 1000ppm CH4

Effect of water on electrode surface with N2

Inlet

OutletOutlet

Electrode of the ozone generator after several hours in H OO N

Inlet

Electrode of the ozone generator after several hours in H2OO2N2

Effect of water on electrode surface

Long term effect (800 hrs) of H2OO2N2

Kinetics of CHx Conversion with N2

conversion by collisionsHNO3 formation

O2 + N2 +CHx 12wtO2 + CO2 +H2O + HNO3

deposition vaporizationby sputtering

H2O + HNO3

by sputtering

irreversible process above a N2 threshold () ltlt 1000ppm N2

sticky deposit

p 2 ( ) pp 2 any CH4 concentration (60ppm)

Plasma Chemistry with CH4 ImpuritiesPlasma Chemistry with CH4 Impurities4

bull Formation of NO and NO2 depends on O3 N2 and gas temperature Conclusion N2 admixture is the key factor

SummarySummaryyyThe mechanisms of formed NOx by-products follows the sameThe mechanisms of formed NOx by-products follows the sameprinciples as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentration

principles as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentrationozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)

ozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)g p ( g p )

The conversion of methane to OH and H2O is found to depend on

g p ( g p )

The conversion of methane to OH and H2O is found to depend ondissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)

dissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)discharge gap)discharge gap)

How do you optimize an ozone generatorg

Scientific ApproachScientific ApproachTheoretical Experimental

pppp

c [wt]

f [Hz]

c [wt]

f [Hz]

[kW]UUUβ1

1Cf4αPn

1iiminpeakimin

iiD

q [kWm2]q [kWm2]

150

180

][V]voltagepeakUpeak

[]cylinder perslicesofamountnsliceii

whereth

09 00

30

60

90

120

effic

ienc

y [

][0tdj t bl[F]sliceisdielectricofecapacitancC

[Hz]frequencyf[V]sliceivoltageminimumiUmin

thiD

th

10

28

46

64

82

39

107

176

244 power density

[kWm2]

ozone conc [wt][]CCβ

][0parameteradjustableα

iDiGi

Impact of Power Inductionp

350

400

wer

200

250

300

App

lied

Pow

Arr C 2Arr D +0

Arr E +45Arr F +7

Arr G +3

5 0

100

150

Frac

tion

of

1 2 3 4

ReferenceArr B unstable

Arr C -2

00

50

4Position (1inlet 4outlet)

Experimental Test Rigp g

Experimental Test Rigp g

Outer grounded electrode (left picture) and the dielectric covered inner electrodes (right) d e ect c cove ed e e ect odes ( g t)

Reference (Traditional) Arrangement

Inlet OutletGas flow direction

Optimized Arrangement

Inlet OutletGas flow direction

Intelligent Gap System (IGS)g p y ( )

Molecular Oxygen (O2) Ozone (O3)

O2 O3

yg ( 2) ( 3)

Particle Size SynthesisParticle Size SynthesisByBy--Products Cluster FormationProducts Cluster Formationyy

high diffusion and deposition to surfaces

low diffusion rate good transport

high sedimentation on the structurehigh sedimentation on the structure

Degreacutemont Technologies ndash OzoniaIntelligent Gap SystemIntelligent Gap System

G Vezzuacute JL Lopez A Freilich and K Becker Optimizationof Large-Scale Ozone Generators IEEE Transactions onPlasma Science Vol 37 No 6 p 890-896 (2009)

ConclusionsConclusionsConclusionsConclusionsFundamentals of ozone synthesis in a DBD plasmay p

ndash Highly filamented DBD discharges are best-suitedfor the production of ozone concentrations in therange of 6 to 14 wtrange of 6 to 14 wt

ndash The preferred characteristic of the microdischargesare Townsend-like at reduced electric fields Enaround 190 Townsend

ndash Detrimental side-effects induced by by-productscan be avoided by a proper design of the electrodecan be avoided by a proper design of the electrodearrangement The phenomenon is related to thediffusion rates of formed by-product clusters

ConclusionsConclusionsConclusionsConclusionsBenefits from DBD microplasma tailoring

ndash Reduced power consumption of up to 10 improvement

ndash Increased ozone concentrations of up to 14 now achievable

ndash Improved neutralization and conditioning of detrimental by-products

ndash Reduced system capital and operational cost

New technologies to improve ozone p

generatorg

HV Pulsed Power SwitchingHV Pulsed Power Switching

Microchannel Generation of Ozone

Channel ArrayChannel Array

Microchannel

330 microm 230 microm

Some Cap-DBD Devices Operating in Air

Increase of 60 of

Spacing 225 μmof 60 of plasma

No space

Cap‐DBD ozone generation

bull Ozone concentration is evaluated via Eco S d l UV 100 O A l (0 01Sensors model UV-100 Ozone Analyzer (001 ndash 900 ppm wiht an accuracy of plusmn2)

bull Three reactors 6 tubings 6rdquo with spacings of 0 μm 225 μm and 500 μm running at 3 kV μ μ μ g

SpacingOzone Concentration

3 kV rms 4 kV rms3 kV rms 4 kV rms

0 μm 660 ppm

225 μm 550 ppm

For a device of such small scale these ozone levels are promising

500 μm 380 ppm

J Mahoney W Zhu VS Johnson KH Becker and JL Lopez Electrical and optical emissionmeasurements of a capillary dielectric barrier discharge European Physics Journal D Vol 60 441-447(2010)

QuestionsQuestions

Thank YouFor more informationProf Jose L Lopez PhD

Thank YouFor more informationDepartment of Physics

Telephone (973) 761-9057Email joselopez1shuedu

Website wwwshueduacademicsartsciphysicsWebsite wwwshueduacademicsartsciphysics

Page 23: Dielectric Barrier Discharge (DBD) & Progress in Large ...bonitz/si12/talks/august_8/lopez_si12.pdf · Dielectric Barrier Discharge (DBD) & Progress in Large-Scale Ozone Generation

Dielectric Barrier Discharge

Dielectric Barrier DischargeDielectric - Barrier Discharge ConfigurationsHigh

VoltageAC

Generator

High VoltageElectrode

DielectricBarrier

DielectricBarrier

High VoltageElectrode

Discharge

DischargeGeneratorGround

Electrode

Electrode

GroundElectrode

Discharge

H E Wagner R Brandenburg et al lsquoThe barrier discharge basic properties and applications toHE Wagner R Brandenburg et al The barrier discharge basic properties and applications tosurface treatmentrsquo Vacuum 71 p417-436 (2003)

Typical operational conditions of barrier discharges Typical operational conditions of barrier discharges

Electric field strength E of first breakdown asymp150 Td (p = 1bar T=300 K)

Voltage Vpp 3ndash20 kV

Repetition frequency f 50 Hzndash30 kHz

Pressure p 1ndash3 bar

Gap distance g 02ndash5mm

Dielectric material thickness d 05ndash2mm

Relative dielectric permittivity r 5ndash10 (glass)

B Eliasson and U Kogelschatz IEEE Transactions Plasma Science Vol 19 Issue 6 1063-1077 (1991)B Eliasson and U Kogelschatz IEEE Transactions Plasma Science Vol 19 Issue 6 1063-1077 (1991)

Single and double DBD

Single dielectric Double dielectric

Role of the Dielectric (Insulator)

Th di l t i i th k f thThe dielectric is the key for the properfunctioning of the discharge

Serves two functions

1 Limits the amount of charge transportedby a single microplasma

2 Distributes the microplasmas over theentire electrode surface area

Equivalent Circuit of a Microdischarge

Microdischarge Activity and U-Q Lissajous Figure

B Eliasson and U Kogelschatz IEEE Transactions Plasma Science Vol 19 Issue 6 1063-1077 (1991)

Fundamental Operation of the Dielectric Barrier DischargeFundamental Operation of the Dielectric Barrier Discharge

bull Many of relevant plasma processes that areof importance to achieving our goal occuron time scales that allow us to study themon time scales that allow us to study them

bull Optical emission spectroscopic studies willallow us to determine the temporal andspatial development of important plasmaspatial development of important plasmaspecies such as radicals (OH NO variousoxygen radicals) with high time resolution(less than 10 ns) and a spatial resolution onthe scale of mm in the plasma volumepfollowing pulsed plasma excitation

Time scale of the relevant processes of the DBD

HE Wagner R Brandenburg et al lsquoThe barrier discharge basic properties and applications tosurface treatmentrsquo Vacuum 71 417-436 (2003)

Fundamental Operation of the DBDFundamental Operation of the DBD

Electron DensityTemporal Development (ns)

y

Outer Contour Linen = 1010 cm-3ne = 1010 cm 3

Inner Contour Linene = 1014 cm-3

Streamer Propagation in 1 bar AirAA Kulikovsky IEEE Trans Plasma Sci 25 439-446 (1997)

Numerical Results of Microdischarge Formationin Dielectric Barrier Discharges

Starting Phase of a Microdischarge (1 bar 20 CO2 80 H2)

E0=34 kVcm1010 cm-3

1010 cm-3 ne=1012 cm-3

1mm10 cm

ne=108 cm-3

An electron avalanche propagates towards the anode

Reverse propagationtowards the cathodepropagates towards the anode towards the cathode

Numerical Results of Microdischarge Formationin Dielectric Barrier Discharges

Cathode Layer Formation

E0=34 kVcm1010 cm-39 3 0

1mm

1010 cm-3

10 cmne=109 cm-31014

10131014

1013

10 cm1012

Just before the peak of the total current

Peak currentof the total current

Numerical Results of Microdischarge Formationin Dielectric Barrier Discharges

Local Field Collapse in Area Defined by Surface Discharge

ne=109cm-3 ne=1014 cm-3

Gap

Principals of DBD MicroplasmasPrincipals of DBD MicroplasmasPrincipals of DBD MicroplasmasPrincipals of DBD Microplasmas

C C-- - --- - - CG

CD

-- - - CG

CD

Principals of DBD MicroplasmasPrincipals of DBD MicroplasmasPrincipals of DBD MicroplasmasPrincipals of DBD Microplasmas

Dielectric Barrier Discharge (DBD)Dielectric Barrier Discharge (DBD)Electric Field

B kdBreakdown

Electrons amp Ions Discharge Physics

Excited SpeciesPlasma Chemistry

Chemical Reactions

OzoneGeneration

SurfaceTreatment

PollutionControl

ExcimerFormation CO2 Lasers Hydrogenation

of CO2

Excimer Lamps Plasma Displays

How A Plasma Display Works

How A Plasma Display Work

Plasma Display TelevisionsPlasma Display Televisions

Ozone Generator

3 O 2 O

Dielectric Barrier Discharge

3 O2 2 O3

OO22 OO33++OO22Ondash ndashO3O2

O2O2

Ondash ndash

endash O2Ondash ndash O2endash

O3

O3O2O2 O2

HeatHeatHeatHeat

Properties of Ozone (O3)

T i t i f f Tri-atomic form of oxygen

Most powerful commercial oxidizing agent

Unstable - must be generated and used onsite

Limited solubility in water but more so than oxygenLimited solubility in water but more so than oxygen

Leaves a dissolved residual which ultimately converts back to oxygenconverts back to oxygen

Discharge Tubes in Ozone GeneratorsDischarge Tubes in Ozone Generators

Traditional

Ozone Generator

with Glass Tubes

Generation of OzoneGeneration of Ozone

Generation of OzoneAdvantages of Enamel Dielectrics

Proven Patented Designbull Simplicity

Si l Di l i Cbull Single Dielectric Componentndash Reduced number of Dielectrics

bull Safety ndash Lower operating voltage

(lt 4000 V)bull Reliabilty

ndash Fused Dielectrics ensure continuous production

bull Lowest Power Consumption Operational Savingsndash Operational Savings

Modern Ozone GeneratorModern Ozone Generator

Ozonia Advanced Technology Ozone GeneratorOzone Generator

Generation of OzoneGeneration of Ozone

Generation of Ozone

Power Supply UnitPower Supply Unit

IGBT Inverter CircuitMain Circuit Breaker

HV 480 Volts60 Hz3 Phase Supply

C I

450KVAPow er to

GeneratorFILTER

CONVERTER INVERTERTRANSFORMER

C I450KVA Power Stage

CONTACTOR

bull Latest in Power Semiconductor Technology Modular Design

bull Utilizes IGBTrsquos (Insulated Gate Bi‐Polar Transistors) Converter and Inverter Components

Ozone Water Treatment

B bbl Diff iB bbl Diff iBubble DiffusionBubble Diffusion

Easy to use

Low energy usage Low energy usage

Mass transfer efficiencies to gt 90

Ozone Process Flow DiagramOzone Process Flow DiagramVent to

Atmosphere

O OOxygen

Off-Gas Blower

Ozone Destruct Unit

10 12

O3O2

LOX

10-12 O3

Ozone Generators

Ozone Contact ChamberLOX T k Generators Chamber

VaporizersLOX Tank

Municipal Ozone Installations

Ozonia Installations Ozone Plant Size [lbday] Start-Up DateKey Ozonia Installations (Partial List)

Los Angeles CA 10000 1986Fairfax VA ndash Corbalis 9000 2003MWD CA ndash Mills 9 000 2003

Ozonia Installations Ozone Plant Size [lbday] Start Up Date

MWD CA Mills 9000 2003Fairfax Co VA ndash Griffith 9000 2004MWD CA ndash Jensen 18750 2005Indianapolis IN ndash Belmont AWT 12000 2007I di li IN 12 000 2007Indianapolis IN ndash Southport AWT 12000 2007MWD CA ndash Diemer 13400 2008MWD CA ndash Weymouth 13400 2009

Ozonia North America - Potable Water SummaryTotal Number of Installations 90Total Installed Production gt 265000 lbsdayTotal Installed Production 265000 lbsday

Revision -B

Ozone Water TreatmentOzone Water Treatment

MWD Mills WTP - California

3 3 000 lbsda of o one3 3 000 lbsda of o one3 x 3000 lbsday of ozone3 x 3000 lbsday of ozone

Ozone Water TreatmentOzone Water TreatmentOzone Ozone -- How it worksHow it works

OxidantOxidant DisinfectantDisinfectant

bullbull Breaks double carbon Breaks double carbon bondsbonds

bullbull Kills by cell lysing or Kills by cell lysing or causing the cell wall tocausing the cell wall tobondsbonds

bullbull Creates OHCreates OHbullbull radicals radicals which break higher carbon which break higher carbon

causing the cell wall to causing the cell wall to rupture rupture

bullbull AttacksAttacks allall bacteriabacteriabondsbondsbullbull Increased temp and pH Increased temp and pH

accelerates Oaccelerates O33

Attacks Attacks allall bacteria bacteria virus cysts and spores virus cysts and spores in varying degreesin varying degreesaccelerates Oaccelerates O33

decomposition to OHdecomposition to OHbullbull

Micro-organism DNA

Capsule AdenineAdenine

Cell wall ThymineThymine

CytosineCytosine

GuanineGuanine

NuclearmaterialCellmembrane

material

Typical Bacterium DNA

Microbial Growth at Various Ozone ConcentrationsConcentrations

Growth likely

Growth possibleGrowth possible

NO GROWTH

0004 0008 0012 0016 0020

Ozone concentration (mgl)Ozone concentration (mgl)

Typical Water Treatment UsageTypical Water Treatment Usage

Application O3 mgl Contact timeUltra Pure Water 005 - 025 sec ndash min

Water bottling 04 ndash 10 5 ndash 10 min

Swimming pools ampspas

01 ndash 075 4 minutes

Potable taste amp odor 15 ndash 50 5 ndash 10 mindisinfection

Microfloculation 10 ndash 30 5 ndash 10 min

Lignin amp tammin 3 0 10 0 10 30 minLignin amp tamminremoval

30 ndash 100 10 ndash 30 min

Municipal wastewater 50 ndash 150+ 15 ndash 30 min

Ozone Water TreatmentOzone Water TreatmentOzone Ozone ndashndash Municipal ApplicationsMunicipal Applications

bullbull Taste and OdorTaste and Odor

bullbull Color RemovalColor Removal

bullbull Disinfection Without Trihalomethanes (THMs)Disinfection Without Trihalomethanes (THMs)

bullbull Improved Filtration Efficiency and FlocculationImproved Filtration Efficiency and Flocculation

bullbull Cryptosporidium DeactivationCryptosporidium Deactivation

bullbull Giardia amp Virus InactivationGiardia amp Virus Inactivation

bullbull Oxidation Oxidation -- Organics Fe amp MnOrganics Fe amp Mn

bullbull Wastewater disinfectionWastewater disinfection

bullbull BOD COD and TOC reductionBOD COD and TOC reduction

Applications of Ozone

Wastewater Treatmentbull Disinfection of Secondary and Tertiary Effluentsbull Color Reductionbull Color Reductionbull TOC Oxidation (Industrial)bull Oxidation of Odor Causing Compoundsbull Oxidation of Endocrine Disruptors (EDCrsquos) and p ( )

Pharmaceutically Active Compounds (PACrsquos)

Applications of Ozone

What are Endocrine Disruptors (EDCrsquos) and What are Endocrine Disruptors (EDCrsquos) and Ph ti ll A ti C d (PACrsquo )Ph ti ll A ti C d (PACrsquo )Pharmaceutically Active Compounds (PACrsquos)Pharmaceutically Active Compounds (PACrsquos)

bullbull EDCrsquosEDCrsquos andand PACrsquosPACrsquos areare NaturallyNaturally andand SyntheticSyntheticdd th tth t ff tff t thth b lb l llcompoundscompounds thatthat maymay affectaffect thethe balancebalance oror normalnormal

functionsfunctions inin animalsanimals andand humanshumans

What can EDCrsquos and PACrsquos doWhat can EDCrsquos and PACrsquos do

bullbull Even in very small concentrations these compounds Even in very small concentrations these compounds y py pcan can disruptdisrupt normal bodily functionsnormal bodily functions

bullbull ManMan--made chemicals can trick the bodies endocrine made chemicals can trick the bodies endocrine system system

Applications of Ozone

Examples of Endocrine Disruptors1000rsquos of compounds that may be Investigated as EDCs ndash Some examples are

bullbull Synthetic HormonesSynthetic Hormonesbullbull Naturally Occurring Estrogens Naturally Occurring Estrogens

Health and Beauty AidsHealth and Beauty Aidsbullbull Health and Beauty AidsHealth and Beauty Aidsbullbull SolventsSolventsbullbull PesticidesPesticidesbullbull SurfactantsSurfactantsbullbull PlasticsPlastics

F i idF i idbullbull FungicidesFungicides

Ozone Water TreatmentOzone Water Treatment

Ozone Ozone -- Industrial ApplicationsIndustrial Applications-- Ultrapure Water for Pharmaceutical ApplicationsUltrapure Water for Pharmaceutical Applications

-- Wastewater disinfection color removalWastewater disinfection color removal

-- Soil and Groundwater Remediation Soil and Groundwater Remediation

-- Cooling Tower Water TreatmentCooling Tower Water Treatment

-- Food ProcessingFood Processing

-- Aquaculture AquariumsAquaculture AquariumsAquaculture AquariumsAquaculture Aquariums

-- Beverage ApplicationsBeverage Applications

P l amp P Bl hiP l amp P Bl hi-- Pulp amp Paper BleachingPulp amp Paper Bleaching

High Purity OzonationHigh Purity Ozonation

Microchip manufacturingMicrochip manufacturing

What are the current issues in large-scale gozone generationg

Experimental Setup

Front view of the two units after the redesign and reworking ofthe gas water and instruments connectionsthe gas water and instruments connections

Experimental Setup

Top view of the twoexperimental unitsexperimental unitsSpectroscope (notshown) is to the left ofthe DBD The units weredifferent with respect todifferent with respect totheir electrodes onehad only the electrodecoated with thedielectric (ldquosingle-dielectric ( single-coatedrdquo) the other onehad the electrode andthe anode coated withthe dielectric (ldquodouble-the dielectric ( double-coatedrdquo)

Basics Generation of OzoneBasics Generation of Ozone

SpectroscopyPlasma

Plasma Absorption SpectroscopyPlasma Absorption Spectroscopy

Infrared Absorption SpectroscopyInfrared Absorption Spectroscopy

IR spectra in pure oxygen (black curve) and at approximately 10wt N2 admixture (red line) N2O5 peaks appear at124 1 d 1 2 11245 cm-1 and at 1725 cm-1

Infrared Absorption SpectroscopyInfrared Absorption Spectroscopy

IR spectra of several methane variations The green curve envelopes all of the methane peaks at 1325 cm-1recorded at smaller methane admixtures Simultaneously the N2O5 peaks disappear as the methane peaks appear

N2O5 FormationN2O5 Formation2 52 5p=2 bara cwt=20degC q=35kWm2 f=1450Hz

45N2O5 AT95

30

35

40

N

2 B

lend

ing

N2O AT95N2O5 IGSN2O IGSN2O5 LGN2O LG

1 5

20

25

nt [p

pmV]

3

wt

05

10

15

NO

x co

nten

005 7 9 11 13 15 17

ozone conc [wt]

Amount of formed N2O5 and N2O as a function of ozone concentration at 3 wt of nitrogen admixture and fori l dvarious electrode arrangements

Plasma Emission SpectroscopyPlasma Emission Spectroscopyp pyp py

Relative Emissions of the Ozonizer plasmaRelative Emissions of the Ozonizer plasma

Region 300- 850 nm from individual (calibrated) regions (smoothed by PeakFit) Single-coated ozone generator Inlet side

3 5E+06

30E+06

35E+06

7 9

20E+06

25E+06

nten

sity

au

2

311 12

10E+06

15E+06

In 4

5

6 8 10

14

15

16

17

00E+00

50E+05

280 300 320 340 360 380 400 420 440 460 480 500 520 540 560 580 600 620 640 660 680 700 720 740 760 780 800 820 840 860

Wavelength nm

1 13

Wavelength nm

Absolute Emission of the DBD PlasmaAbsolute Emission of the DBD Plasma

Intensities in (O2+3 wtN2) plasma

1 20E+04

100E+04

120E+04

600E+03

800E+03

nten

sity

(au

)

200E+03

400E+03

In

O(777)

000E+00200 250 300 350 400 450 500 550 600 650 700 750 800 850

Wavelength nm

Intensities in 3 wtN2+O2 plasmaIntensities in 3 wtN2+O2 plasma

Plasma Chemistry in OzonizersPlasma Chemistry in Ozonizers

Dry Air O2 N2

e - e -

O N2 N O2

O3 NO

O2 N O2

O3

N

3

NO2

O2 O3

NO

N

NO2 O3

N2O

NO3 N

N2O4

NO2

NO2

N2O5

NO3

Primary electron-driven chemical reactions leading to the formation of N2O5 and N2O in a dry air plasma

Plasma emission diagnostics role of N2Plasma emission diagnostics role of N2

Dry Air O2 N2

e - e -

O N2 N O2

O3 NO

O2 N O2

O3

O

N

ON

NO2

O2O3

N

NO N

NO2 O3

N2O

NO3 N

N2O4

NO2

NO2

N2O5

NO3

ONbullWith N2 present ndash less oxygen atoms are formed However the difference in intensity is

very small

Modeling of plasma chemistry incl the NxOy chemistry up to N2O5 for different Oxygen Nitrogen mixtures varying power deposition scenarios

and initial ozone background concentrations (up to 15) previously done

The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation

The role of N2 must be related to its by-products reacting on the surface of the electrodeThe role of N2 must be related to its by-products reacting on the surface of the electrode

The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established

Ab 8 t f O

The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established

Ab 8 t f OAbove 8 wt of O3

1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)

Above 8 wt of O3

1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)case without pampp)

2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of the

case without pampp)

2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of thethem A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface

them A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface

The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation

Three possibilities have to be considered for the oxygen-fedozone generator

Three possibilities have to be considered for the oxygen-fedozone generatorozone generator

bull Excited N2 molecules lead to an increased O2 dissociation in

ozone generator

bull Excited N2 molecules lead to an increased O2 dissociation in2 2such case an increased efficiency is correlated to the N2admixture

2 2such case an increased efficiency is correlated to the N2admixture

bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial

bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial

bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2

bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2g p g 3 pp y 2g p g 3 pp y 2

Effect of methane on ozone efficiency and specific powerEffect of methane on ozone efficiency and specific power

Effect of Methane on Ozone Content in Outlet Gas and on Specific Power Pure O2

13 12

10

11

12

t 8

10

8

9

10

ne c

onte

nt w

t

6

8

ecifi

c po

wer

kW

hlb

5

6

7

Ozo

n

2

4 Spe

400E+00 20E+03 40E+03 60E+03 80E+03 10E+04 12E+04

Methane in feedgas ppm

0

Ozone content in the outlet gas Specif ic pow er of the ozone generatorg p p g

Effects of N2 and CH4Effects of N2 and CH4

Pi t f h t lli N O t tPicture of an amorphous-crystalline N2O5 structurecaptured at the Orlando Skylake water plant in 2006

Plasma Chemistry with CH4 Impurities

OxygenO2 N2

e - e -

CHO N2

NO2

O NO

O2 N O2 O3

NOH

CH4e-

O3 NO

NO2

O2O3NO N

NO2 O

NO2

NO2

N2ONO3

N

O3

NO2

NO

HNO3

N2O4

N2O5

NO2

NO3

N2O5

Effect of methane on the electrode surfaces

a) b)

Inlet Outlet Outlet

) d)

I l t I l t

c) d)

Electrode of the ozone generator afterseveral hours in CH8O2 and up to 2 wt of methane (a b c)

Inlet Inlet

three hours in CH8O2+traces of N2 and up to 1 wt of methane (d) Visible change of discharge character at about 13 length of electrode (a d)

Kinetics of CHx Conversion without N2

conversion by collisions

O2 + CHx 12wt O3 + CO2 +H2O

deposition vaporizationby sputtering

ibl b l 1000 CHreversible process below 1000ppm CH4

Effect of water on electrode surface with N2

Inlet

OutletOutlet

Electrode of the ozone generator after several hours in H OO N

Inlet

Electrode of the ozone generator after several hours in H2OO2N2

Effect of water on electrode surface

Long term effect (800 hrs) of H2OO2N2

Kinetics of CHx Conversion with N2

conversion by collisionsHNO3 formation

O2 + N2 +CHx 12wtO2 + CO2 +H2O + HNO3

deposition vaporizationby sputtering

H2O + HNO3

by sputtering

irreversible process above a N2 threshold () ltlt 1000ppm N2

sticky deposit

p 2 ( ) pp 2 any CH4 concentration (60ppm)

Plasma Chemistry with CH4 ImpuritiesPlasma Chemistry with CH4 Impurities4

bull Formation of NO and NO2 depends on O3 N2 and gas temperature Conclusion N2 admixture is the key factor

SummarySummaryyyThe mechanisms of formed NOx by-products follows the sameThe mechanisms of formed NOx by-products follows the sameprinciples as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentration

principles as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentrationozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)

ozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)g p ( g p )

The conversion of methane to OH and H2O is found to depend on

g p ( g p )

The conversion of methane to OH and H2O is found to depend ondissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)

dissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)discharge gap)discharge gap)

How do you optimize an ozone generatorg

Scientific ApproachScientific ApproachTheoretical Experimental

pppp

c [wt]

f [Hz]

c [wt]

f [Hz]

[kW]UUUβ1

1Cf4αPn

1iiminpeakimin

iiD

q [kWm2]q [kWm2]

150

180

][V]voltagepeakUpeak

[]cylinder perslicesofamountnsliceii

whereth

09 00

30

60

90

120

effic

ienc

y [

][0tdj t bl[F]sliceisdielectricofecapacitancC

[Hz]frequencyf[V]sliceivoltageminimumiUmin

thiD

th

10

28

46

64

82

39

107

176

244 power density

[kWm2]

ozone conc [wt][]CCβ

][0parameteradjustableα

iDiGi

Impact of Power Inductionp

350

400

wer

200

250

300

App

lied

Pow

Arr C 2Arr D +0

Arr E +45Arr F +7

Arr G +3

5 0

100

150

Frac

tion

of

1 2 3 4

ReferenceArr B unstable

Arr C -2

00

50

4Position (1inlet 4outlet)

Experimental Test Rigp g

Experimental Test Rigp g

Outer grounded electrode (left picture) and the dielectric covered inner electrodes (right) d e ect c cove ed e e ect odes ( g t)

Reference (Traditional) Arrangement

Inlet OutletGas flow direction

Optimized Arrangement

Inlet OutletGas flow direction

Intelligent Gap System (IGS)g p y ( )

Molecular Oxygen (O2) Ozone (O3)

O2 O3

yg ( 2) ( 3)

Particle Size SynthesisParticle Size SynthesisByBy--Products Cluster FormationProducts Cluster Formationyy

high diffusion and deposition to surfaces

low diffusion rate good transport

high sedimentation on the structurehigh sedimentation on the structure

Degreacutemont Technologies ndash OzoniaIntelligent Gap SystemIntelligent Gap System

G Vezzuacute JL Lopez A Freilich and K Becker Optimizationof Large-Scale Ozone Generators IEEE Transactions onPlasma Science Vol 37 No 6 p 890-896 (2009)

ConclusionsConclusionsConclusionsConclusionsFundamentals of ozone synthesis in a DBD plasmay p

ndash Highly filamented DBD discharges are best-suitedfor the production of ozone concentrations in therange of 6 to 14 wtrange of 6 to 14 wt

ndash The preferred characteristic of the microdischargesare Townsend-like at reduced electric fields Enaround 190 Townsend

ndash Detrimental side-effects induced by by-productscan be avoided by a proper design of the electrodecan be avoided by a proper design of the electrodearrangement The phenomenon is related to thediffusion rates of formed by-product clusters

ConclusionsConclusionsConclusionsConclusionsBenefits from DBD microplasma tailoring

ndash Reduced power consumption of up to 10 improvement

ndash Increased ozone concentrations of up to 14 now achievable

ndash Improved neutralization and conditioning of detrimental by-products

ndash Reduced system capital and operational cost

New technologies to improve ozone p

generatorg

HV Pulsed Power SwitchingHV Pulsed Power Switching

Microchannel Generation of Ozone

Channel ArrayChannel Array

Microchannel

330 microm 230 microm

Some Cap-DBD Devices Operating in Air

Increase of 60 of

Spacing 225 μmof 60 of plasma

No space

Cap‐DBD ozone generation

bull Ozone concentration is evaluated via Eco S d l UV 100 O A l (0 01Sensors model UV-100 Ozone Analyzer (001 ndash 900 ppm wiht an accuracy of plusmn2)

bull Three reactors 6 tubings 6rdquo with spacings of 0 μm 225 μm and 500 μm running at 3 kV μ μ μ g

SpacingOzone Concentration

3 kV rms 4 kV rms3 kV rms 4 kV rms

0 μm 660 ppm

225 μm 550 ppm

For a device of such small scale these ozone levels are promising

500 μm 380 ppm

J Mahoney W Zhu VS Johnson KH Becker and JL Lopez Electrical and optical emissionmeasurements of a capillary dielectric barrier discharge European Physics Journal D Vol 60 441-447(2010)

QuestionsQuestions

Thank YouFor more informationProf Jose L Lopez PhD

Thank YouFor more informationDepartment of Physics

Telephone (973) 761-9057Email joselopez1shuedu

Website wwwshueduacademicsartsciphysicsWebsite wwwshueduacademicsartsciphysics

Page 24: Dielectric Barrier Discharge (DBD) & Progress in Large ...bonitz/si12/talks/august_8/lopez_si12.pdf · Dielectric Barrier Discharge (DBD) & Progress in Large-Scale Ozone Generation

Typical operational conditions of barrier discharges Typical operational conditions of barrier discharges

Electric field strength E of first breakdown asymp150 Td (p = 1bar T=300 K)

Voltage Vpp 3ndash20 kV

Repetition frequency f 50 Hzndash30 kHz

Pressure p 1ndash3 bar

Gap distance g 02ndash5mm

Dielectric material thickness d 05ndash2mm

Relative dielectric permittivity r 5ndash10 (glass)

B Eliasson and U Kogelschatz IEEE Transactions Plasma Science Vol 19 Issue 6 1063-1077 (1991)B Eliasson and U Kogelschatz IEEE Transactions Plasma Science Vol 19 Issue 6 1063-1077 (1991)

Single and double DBD

Single dielectric Double dielectric

Role of the Dielectric (Insulator)

Th di l t i i th k f thThe dielectric is the key for the properfunctioning of the discharge

Serves two functions

1 Limits the amount of charge transportedby a single microplasma

2 Distributes the microplasmas over theentire electrode surface area

Equivalent Circuit of a Microdischarge

Microdischarge Activity and U-Q Lissajous Figure

B Eliasson and U Kogelschatz IEEE Transactions Plasma Science Vol 19 Issue 6 1063-1077 (1991)

Fundamental Operation of the Dielectric Barrier DischargeFundamental Operation of the Dielectric Barrier Discharge

bull Many of relevant plasma processes that areof importance to achieving our goal occuron time scales that allow us to study themon time scales that allow us to study them

bull Optical emission spectroscopic studies willallow us to determine the temporal andspatial development of important plasmaspatial development of important plasmaspecies such as radicals (OH NO variousoxygen radicals) with high time resolution(less than 10 ns) and a spatial resolution onthe scale of mm in the plasma volumepfollowing pulsed plasma excitation

Time scale of the relevant processes of the DBD

HE Wagner R Brandenburg et al lsquoThe barrier discharge basic properties and applications tosurface treatmentrsquo Vacuum 71 417-436 (2003)

Fundamental Operation of the DBDFundamental Operation of the DBD

Electron DensityTemporal Development (ns)

y

Outer Contour Linen = 1010 cm-3ne = 1010 cm 3

Inner Contour Linene = 1014 cm-3

Streamer Propagation in 1 bar AirAA Kulikovsky IEEE Trans Plasma Sci 25 439-446 (1997)

Numerical Results of Microdischarge Formationin Dielectric Barrier Discharges

Starting Phase of a Microdischarge (1 bar 20 CO2 80 H2)

E0=34 kVcm1010 cm-3

1010 cm-3 ne=1012 cm-3

1mm10 cm

ne=108 cm-3

An electron avalanche propagates towards the anode

Reverse propagationtowards the cathodepropagates towards the anode towards the cathode

Numerical Results of Microdischarge Formationin Dielectric Barrier Discharges

Cathode Layer Formation

E0=34 kVcm1010 cm-39 3 0

1mm

1010 cm-3

10 cmne=109 cm-31014

10131014

1013

10 cm1012

Just before the peak of the total current

Peak currentof the total current

Numerical Results of Microdischarge Formationin Dielectric Barrier Discharges

Local Field Collapse in Area Defined by Surface Discharge

ne=109cm-3 ne=1014 cm-3

Gap

Principals of DBD MicroplasmasPrincipals of DBD MicroplasmasPrincipals of DBD MicroplasmasPrincipals of DBD Microplasmas

C C-- - --- - - CG

CD

-- - - CG

CD

Principals of DBD MicroplasmasPrincipals of DBD MicroplasmasPrincipals of DBD MicroplasmasPrincipals of DBD Microplasmas

Dielectric Barrier Discharge (DBD)Dielectric Barrier Discharge (DBD)Electric Field

B kdBreakdown

Electrons amp Ions Discharge Physics

Excited SpeciesPlasma Chemistry

Chemical Reactions

OzoneGeneration

SurfaceTreatment

PollutionControl

ExcimerFormation CO2 Lasers Hydrogenation

of CO2

Excimer Lamps Plasma Displays

How A Plasma Display Works

How A Plasma Display Work

Plasma Display TelevisionsPlasma Display Televisions

Ozone Generator

3 O 2 O

Dielectric Barrier Discharge

3 O2 2 O3

OO22 OO33++OO22Ondash ndashO3O2

O2O2

Ondash ndash

endash O2Ondash ndash O2endash

O3

O3O2O2 O2

HeatHeatHeatHeat

Properties of Ozone (O3)

T i t i f f Tri-atomic form of oxygen

Most powerful commercial oxidizing agent

Unstable - must be generated and used onsite

Limited solubility in water but more so than oxygenLimited solubility in water but more so than oxygen

Leaves a dissolved residual which ultimately converts back to oxygenconverts back to oxygen

Discharge Tubes in Ozone GeneratorsDischarge Tubes in Ozone Generators

Traditional

Ozone Generator

with Glass Tubes

Generation of OzoneGeneration of Ozone

Generation of OzoneAdvantages of Enamel Dielectrics

Proven Patented Designbull Simplicity

Si l Di l i Cbull Single Dielectric Componentndash Reduced number of Dielectrics

bull Safety ndash Lower operating voltage

(lt 4000 V)bull Reliabilty

ndash Fused Dielectrics ensure continuous production

bull Lowest Power Consumption Operational Savingsndash Operational Savings

Modern Ozone GeneratorModern Ozone Generator

Ozonia Advanced Technology Ozone GeneratorOzone Generator

Generation of OzoneGeneration of Ozone

Generation of Ozone

Power Supply UnitPower Supply Unit

IGBT Inverter CircuitMain Circuit Breaker

HV 480 Volts60 Hz3 Phase Supply

C I

450KVAPow er to

GeneratorFILTER

CONVERTER INVERTERTRANSFORMER

C I450KVA Power Stage

CONTACTOR

bull Latest in Power Semiconductor Technology Modular Design

bull Utilizes IGBTrsquos (Insulated Gate Bi‐Polar Transistors) Converter and Inverter Components

Ozone Water Treatment

B bbl Diff iB bbl Diff iBubble DiffusionBubble Diffusion

Easy to use

Low energy usage Low energy usage

Mass transfer efficiencies to gt 90

Ozone Process Flow DiagramOzone Process Flow DiagramVent to

Atmosphere

O OOxygen

Off-Gas Blower

Ozone Destruct Unit

10 12

O3O2

LOX

10-12 O3

Ozone Generators

Ozone Contact ChamberLOX T k Generators Chamber

VaporizersLOX Tank

Municipal Ozone Installations

Ozonia Installations Ozone Plant Size [lbday] Start-Up DateKey Ozonia Installations (Partial List)

Los Angeles CA 10000 1986Fairfax VA ndash Corbalis 9000 2003MWD CA ndash Mills 9 000 2003

Ozonia Installations Ozone Plant Size [lbday] Start Up Date

MWD CA Mills 9000 2003Fairfax Co VA ndash Griffith 9000 2004MWD CA ndash Jensen 18750 2005Indianapolis IN ndash Belmont AWT 12000 2007I di li IN 12 000 2007Indianapolis IN ndash Southport AWT 12000 2007MWD CA ndash Diemer 13400 2008MWD CA ndash Weymouth 13400 2009

Ozonia North America - Potable Water SummaryTotal Number of Installations 90Total Installed Production gt 265000 lbsdayTotal Installed Production 265000 lbsday

Revision -B

Ozone Water TreatmentOzone Water Treatment

MWD Mills WTP - California

3 3 000 lbsda of o one3 3 000 lbsda of o one3 x 3000 lbsday of ozone3 x 3000 lbsday of ozone

Ozone Water TreatmentOzone Water TreatmentOzone Ozone -- How it worksHow it works

OxidantOxidant DisinfectantDisinfectant

bullbull Breaks double carbon Breaks double carbon bondsbonds

bullbull Kills by cell lysing or Kills by cell lysing or causing the cell wall tocausing the cell wall tobondsbonds

bullbull Creates OHCreates OHbullbull radicals radicals which break higher carbon which break higher carbon

causing the cell wall to causing the cell wall to rupture rupture

bullbull AttacksAttacks allall bacteriabacteriabondsbondsbullbull Increased temp and pH Increased temp and pH

accelerates Oaccelerates O33

Attacks Attacks allall bacteria bacteria virus cysts and spores virus cysts and spores in varying degreesin varying degreesaccelerates Oaccelerates O33

decomposition to OHdecomposition to OHbullbull

Micro-organism DNA

Capsule AdenineAdenine

Cell wall ThymineThymine

CytosineCytosine

GuanineGuanine

NuclearmaterialCellmembrane

material

Typical Bacterium DNA

Microbial Growth at Various Ozone ConcentrationsConcentrations

Growth likely

Growth possibleGrowth possible

NO GROWTH

0004 0008 0012 0016 0020

Ozone concentration (mgl)Ozone concentration (mgl)

Typical Water Treatment UsageTypical Water Treatment Usage

Application O3 mgl Contact timeUltra Pure Water 005 - 025 sec ndash min

Water bottling 04 ndash 10 5 ndash 10 min

Swimming pools ampspas

01 ndash 075 4 minutes

Potable taste amp odor 15 ndash 50 5 ndash 10 mindisinfection

Microfloculation 10 ndash 30 5 ndash 10 min

Lignin amp tammin 3 0 10 0 10 30 minLignin amp tamminremoval

30 ndash 100 10 ndash 30 min

Municipal wastewater 50 ndash 150+ 15 ndash 30 min

Ozone Water TreatmentOzone Water TreatmentOzone Ozone ndashndash Municipal ApplicationsMunicipal Applications

bullbull Taste and OdorTaste and Odor

bullbull Color RemovalColor Removal

bullbull Disinfection Without Trihalomethanes (THMs)Disinfection Without Trihalomethanes (THMs)

bullbull Improved Filtration Efficiency and FlocculationImproved Filtration Efficiency and Flocculation

bullbull Cryptosporidium DeactivationCryptosporidium Deactivation

bullbull Giardia amp Virus InactivationGiardia amp Virus Inactivation

bullbull Oxidation Oxidation -- Organics Fe amp MnOrganics Fe amp Mn

bullbull Wastewater disinfectionWastewater disinfection

bullbull BOD COD and TOC reductionBOD COD and TOC reduction

Applications of Ozone

Wastewater Treatmentbull Disinfection of Secondary and Tertiary Effluentsbull Color Reductionbull Color Reductionbull TOC Oxidation (Industrial)bull Oxidation of Odor Causing Compoundsbull Oxidation of Endocrine Disruptors (EDCrsquos) and p ( )

Pharmaceutically Active Compounds (PACrsquos)

Applications of Ozone

What are Endocrine Disruptors (EDCrsquos) and What are Endocrine Disruptors (EDCrsquos) and Ph ti ll A ti C d (PACrsquo )Ph ti ll A ti C d (PACrsquo )Pharmaceutically Active Compounds (PACrsquos)Pharmaceutically Active Compounds (PACrsquos)

bullbull EDCrsquosEDCrsquos andand PACrsquosPACrsquos areare NaturallyNaturally andand SyntheticSyntheticdd th tth t ff tff t thth b lb l llcompoundscompounds thatthat maymay affectaffect thethe balancebalance oror normalnormal

functionsfunctions inin animalsanimals andand humanshumans

What can EDCrsquos and PACrsquos doWhat can EDCrsquos and PACrsquos do

bullbull Even in very small concentrations these compounds Even in very small concentrations these compounds y py pcan can disruptdisrupt normal bodily functionsnormal bodily functions

bullbull ManMan--made chemicals can trick the bodies endocrine made chemicals can trick the bodies endocrine system system

Applications of Ozone

Examples of Endocrine Disruptors1000rsquos of compounds that may be Investigated as EDCs ndash Some examples are

bullbull Synthetic HormonesSynthetic Hormonesbullbull Naturally Occurring Estrogens Naturally Occurring Estrogens

Health and Beauty AidsHealth and Beauty Aidsbullbull Health and Beauty AidsHealth and Beauty Aidsbullbull SolventsSolventsbullbull PesticidesPesticidesbullbull SurfactantsSurfactantsbullbull PlasticsPlastics

F i idF i idbullbull FungicidesFungicides

Ozone Water TreatmentOzone Water Treatment

Ozone Ozone -- Industrial ApplicationsIndustrial Applications-- Ultrapure Water for Pharmaceutical ApplicationsUltrapure Water for Pharmaceutical Applications

-- Wastewater disinfection color removalWastewater disinfection color removal

-- Soil and Groundwater Remediation Soil and Groundwater Remediation

-- Cooling Tower Water TreatmentCooling Tower Water Treatment

-- Food ProcessingFood Processing

-- Aquaculture AquariumsAquaculture AquariumsAquaculture AquariumsAquaculture Aquariums

-- Beverage ApplicationsBeverage Applications

P l amp P Bl hiP l amp P Bl hi-- Pulp amp Paper BleachingPulp amp Paper Bleaching

High Purity OzonationHigh Purity Ozonation

Microchip manufacturingMicrochip manufacturing

What are the current issues in large-scale gozone generationg

Experimental Setup

Front view of the two units after the redesign and reworking ofthe gas water and instruments connectionsthe gas water and instruments connections

Experimental Setup

Top view of the twoexperimental unitsexperimental unitsSpectroscope (notshown) is to the left ofthe DBD The units weredifferent with respect todifferent with respect totheir electrodes onehad only the electrodecoated with thedielectric (ldquosingle-dielectric ( single-coatedrdquo) the other onehad the electrode andthe anode coated withthe dielectric (ldquodouble-the dielectric ( double-coatedrdquo)

Basics Generation of OzoneBasics Generation of Ozone

SpectroscopyPlasma

Plasma Absorption SpectroscopyPlasma Absorption Spectroscopy

Infrared Absorption SpectroscopyInfrared Absorption Spectroscopy

IR spectra in pure oxygen (black curve) and at approximately 10wt N2 admixture (red line) N2O5 peaks appear at124 1 d 1 2 11245 cm-1 and at 1725 cm-1

Infrared Absorption SpectroscopyInfrared Absorption Spectroscopy

IR spectra of several methane variations The green curve envelopes all of the methane peaks at 1325 cm-1recorded at smaller methane admixtures Simultaneously the N2O5 peaks disappear as the methane peaks appear

N2O5 FormationN2O5 Formation2 52 5p=2 bara cwt=20degC q=35kWm2 f=1450Hz

45N2O5 AT95

30

35

40

N

2 B

lend

ing

N2O AT95N2O5 IGSN2O IGSN2O5 LGN2O LG

1 5

20

25

nt [p

pmV]

3

wt

05

10

15

NO

x co

nten

005 7 9 11 13 15 17

ozone conc [wt]

Amount of formed N2O5 and N2O as a function of ozone concentration at 3 wt of nitrogen admixture and fori l dvarious electrode arrangements

Plasma Emission SpectroscopyPlasma Emission Spectroscopyp pyp py

Relative Emissions of the Ozonizer plasmaRelative Emissions of the Ozonizer plasma

Region 300- 850 nm from individual (calibrated) regions (smoothed by PeakFit) Single-coated ozone generator Inlet side

3 5E+06

30E+06

35E+06

7 9

20E+06

25E+06

nten

sity

au

2

311 12

10E+06

15E+06

In 4

5

6 8 10

14

15

16

17

00E+00

50E+05

280 300 320 340 360 380 400 420 440 460 480 500 520 540 560 580 600 620 640 660 680 700 720 740 760 780 800 820 840 860

Wavelength nm

1 13

Wavelength nm

Absolute Emission of the DBD PlasmaAbsolute Emission of the DBD Plasma

Intensities in (O2+3 wtN2) plasma

1 20E+04

100E+04

120E+04

600E+03

800E+03

nten

sity

(au

)

200E+03

400E+03

In

O(777)

000E+00200 250 300 350 400 450 500 550 600 650 700 750 800 850

Wavelength nm

Intensities in 3 wtN2+O2 plasmaIntensities in 3 wtN2+O2 plasma

Plasma Chemistry in OzonizersPlasma Chemistry in Ozonizers

Dry Air O2 N2

e - e -

O N2 N O2

O3 NO

O2 N O2

O3

N

3

NO2

O2 O3

NO

N

NO2 O3

N2O

NO3 N

N2O4

NO2

NO2

N2O5

NO3

Primary electron-driven chemical reactions leading to the formation of N2O5 and N2O in a dry air plasma

Plasma emission diagnostics role of N2Plasma emission diagnostics role of N2

Dry Air O2 N2

e - e -

O N2 N O2

O3 NO

O2 N O2

O3

O

N

ON

NO2

O2O3

N

NO N

NO2 O3

N2O

NO3 N

N2O4

NO2

NO2

N2O5

NO3

ONbullWith N2 present ndash less oxygen atoms are formed However the difference in intensity is

very small

Modeling of plasma chemistry incl the NxOy chemistry up to N2O5 for different Oxygen Nitrogen mixtures varying power deposition scenarios

and initial ozone background concentrations (up to 15) previously done

The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation

The role of N2 must be related to its by-products reacting on the surface of the electrodeThe role of N2 must be related to its by-products reacting on the surface of the electrode

The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established

Ab 8 t f O

The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established

Ab 8 t f OAbove 8 wt of O3

1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)

Above 8 wt of O3

1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)case without pampp)

2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of the

case without pampp)

2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of thethem A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface

them A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface

The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation

Three possibilities have to be considered for the oxygen-fedozone generator

Three possibilities have to be considered for the oxygen-fedozone generatorozone generator

bull Excited N2 molecules lead to an increased O2 dissociation in

ozone generator

bull Excited N2 molecules lead to an increased O2 dissociation in2 2such case an increased efficiency is correlated to the N2admixture

2 2such case an increased efficiency is correlated to the N2admixture

bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial

bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial

bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2

bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2g p g 3 pp y 2g p g 3 pp y 2

Effect of methane on ozone efficiency and specific powerEffect of methane on ozone efficiency and specific power

Effect of Methane on Ozone Content in Outlet Gas and on Specific Power Pure O2

13 12

10

11

12

t 8

10

8

9

10

ne c

onte

nt w

t

6

8

ecifi

c po

wer

kW

hlb

5

6

7

Ozo

n

2

4 Spe

400E+00 20E+03 40E+03 60E+03 80E+03 10E+04 12E+04

Methane in feedgas ppm

0

Ozone content in the outlet gas Specif ic pow er of the ozone generatorg p p g

Effects of N2 and CH4Effects of N2 and CH4

Pi t f h t lli N O t tPicture of an amorphous-crystalline N2O5 structurecaptured at the Orlando Skylake water plant in 2006

Plasma Chemistry with CH4 Impurities

OxygenO2 N2

e - e -

CHO N2

NO2

O NO

O2 N O2 O3

NOH

CH4e-

O3 NO

NO2

O2O3NO N

NO2 O

NO2

NO2

N2ONO3

N

O3

NO2

NO

HNO3

N2O4

N2O5

NO2

NO3

N2O5

Effect of methane on the electrode surfaces

a) b)

Inlet Outlet Outlet

) d)

I l t I l t

c) d)

Electrode of the ozone generator afterseveral hours in CH8O2 and up to 2 wt of methane (a b c)

Inlet Inlet

three hours in CH8O2+traces of N2 and up to 1 wt of methane (d) Visible change of discharge character at about 13 length of electrode (a d)

Kinetics of CHx Conversion without N2

conversion by collisions

O2 + CHx 12wt O3 + CO2 +H2O

deposition vaporizationby sputtering

ibl b l 1000 CHreversible process below 1000ppm CH4

Effect of water on electrode surface with N2

Inlet

OutletOutlet

Electrode of the ozone generator after several hours in H OO N

Inlet

Electrode of the ozone generator after several hours in H2OO2N2

Effect of water on electrode surface

Long term effect (800 hrs) of H2OO2N2

Kinetics of CHx Conversion with N2

conversion by collisionsHNO3 formation

O2 + N2 +CHx 12wtO2 + CO2 +H2O + HNO3

deposition vaporizationby sputtering

H2O + HNO3

by sputtering

irreversible process above a N2 threshold () ltlt 1000ppm N2

sticky deposit

p 2 ( ) pp 2 any CH4 concentration (60ppm)

Plasma Chemistry with CH4 ImpuritiesPlasma Chemistry with CH4 Impurities4

bull Formation of NO and NO2 depends on O3 N2 and gas temperature Conclusion N2 admixture is the key factor

SummarySummaryyyThe mechanisms of formed NOx by-products follows the sameThe mechanisms of formed NOx by-products follows the sameprinciples as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentration

principles as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentrationozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)

ozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)g p ( g p )

The conversion of methane to OH and H2O is found to depend on

g p ( g p )

The conversion of methane to OH and H2O is found to depend ondissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)

dissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)discharge gap)discharge gap)

How do you optimize an ozone generatorg

Scientific ApproachScientific ApproachTheoretical Experimental

pppp

c [wt]

f [Hz]

c [wt]

f [Hz]

[kW]UUUβ1

1Cf4αPn

1iiminpeakimin

iiD

q [kWm2]q [kWm2]

150

180

][V]voltagepeakUpeak

[]cylinder perslicesofamountnsliceii

whereth

09 00

30

60

90

120

effic

ienc

y [

][0tdj t bl[F]sliceisdielectricofecapacitancC

[Hz]frequencyf[V]sliceivoltageminimumiUmin

thiD

th

10

28

46

64

82

39

107

176

244 power density

[kWm2]

ozone conc [wt][]CCβ

][0parameteradjustableα

iDiGi

Impact of Power Inductionp

350

400

wer

200

250

300

App

lied

Pow

Arr C 2Arr D +0

Arr E +45Arr F +7

Arr G +3

5 0

100

150

Frac

tion

of

1 2 3 4

ReferenceArr B unstable

Arr C -2

00

50

4Position (1inlet 4outlet)

Experimental Test Rigp g

Experimental Test Rigp g

Outer grounded electrode (left picture) and the dielectric covered inner electrodes (right) d e ect c cove ed e e ect odes ( g t)

Reference (Traditional) Arrangement

Inlet OutletGas flow direction

Optimized Arrangement

Inlet OutletGas flow direction

Intelligent Gap System (IGS)g p y ( )

Molecular Oxygen (O2) Ozone (O3)

O2 O3

yg ( 2) ( 3)

Particle Size SynthesisParticle Size SynthesisByBy--Products Cluster FormationProducts Cluster Formationyy

high diffusion and deposition to surfaces

low diffusion rate good transport

high sedimentation on the structurehigh sedimentation on the structure

Degreacutemont Technologies ndash OzoniaIntelligent Gap SystemIntelligent Gap System

G Vezzuacute JL Lopez A Freilich and K Becker Optimizationof Large-Scale Ozone Generators IEEE Transactions onPlasma Science Vol 37 No 6 p 890-896 (2009)

ConclusionsConclusionsConclusionsConclusionsFundamentals of ozone synthesis in a DBD plasmay p

ndash Highly filamented DBD discharges are best-suitedfor the production of ozone concentrations in therange of 6 to 14 wtrange of 6 to 14 wt

ndash The preferred characteristic of the microdischargesare Townsend-like at reduced electric fields Enaround 190 Townsend

ndash Detrimental side-effects induced by by-productscan be avoided by a proper design of the electrodecan be avoided by a proper design of the electrodearrangement The phenomenon is related to thediffusion rates of formed by-product clusters

ConclusionsConclusionsConclusionsConclusionsBenefits from DBD microplasma tailoring

ndash Reduced power consumption of up to 10 improvement

ndash Increased ozone concentrations of up to 14 now achievable

ndash Improved neutralization and conditioning of detrimental by-products

ndash Reduced system capital and operational cost

New technologies to improve ozone p

generatorg

HV Pulsed Power SwitchingHV Pulsed Power Switching

Microchannel Generation of Ozone

Channel ArrayChannel Array

Microchannel

330 microm 230 microm

Some Cap-DBD Devices Operating in Air

Increase of 60 of

Spacing 225 μmof 60 of plasma

No space

Cap‐DBD ozone generation

bull Ozone concentration is evaluated via Eco S d l UV 100 O A l (0 01Sensors model UV-100 Ozone Analyzer (001 ndash 900 ppm wiht an accuracy of plusmn2)

bull Three reactors 6 tubings 6rdquo with spacings of 0 μm 225 μm and 500 μm running at 3 kV μ μ μ g

SpacingOzone Concentration

3 kV rms 4 kV rms3 kV rms 4 kV rms

0 μm 660 ppm

225 μm 550 ppm

For a device of such small scale these ozone levels are promising

500 μm 380 ppm

J Mahoney W Zhu VS Johnson KH Becker and JL Lopez Electrical and optical emissionmeasurements of a capillary dielectric barrier discharge European Physics Journal D Vol 60 441-447(2010)

QuestionsQuestions

Thank YouFor more informationProf Jose L Lopez PhD

Thank YouFor more informationDepartment of Physics

Telephone (973) 761-9057Email joselopez1shuedu

Website wwwshueduacademicsartsciphysicsWebsite wwwshueduacademicsartsciphysics

Page 25: Dielectric Barrier Discharge (DBD) & Progress in Large ...bonitz/si12/talks/august_8/lopez_si12.pdf · Dielectric Barrier Discharge (DBD) & Progress in Large-Scale Ozone Generation

Single and double DBD

Single dielectric Double dielectric

Role of the Dielectric (Insulator)

Th di l t i i th k f thThe dielectric is the key for the properfunctioning of the discharge

Serves two functions

1 Limits the amount of charge transportedby a single microplasma

2 Distributes the microplasmas over theentire electrode surface area

Equivalent Circuit of a Microdischarge

Microdischarge Activity and U-Q Lissajous Figure

B Eliasson and U Kogelschatz IEEE Transactions Plasma Science Vol 19 Issue 6 1063-1077 (1991)

Fundamental Operation of the Dielectric Barrier DischargeFundamental Operation of the Dielectric Barrier Discharge

bull Many of relevant plasma processes that areof importance to achieving our goal occuron time scales that allow us to study themon time scales that allow us to study them

bull Optical emission spectroscopic studies willallow us to determine the temporal andspatial development of important plasmaspatial development of important plasmaspecies such as radicals (OH NO variousoxygen radicals) with high time resolution(less than 10 ns) and a spatial resolution onthe scale of mm in the plasma volumepfollowing pulsed plasma excitation

Time scale of the relevant processes of the DBD

HE Wagner R Brandenburg et al lsquoThe barrier discharge basic properties and applications tosurface treatmentrsquo Vacuum 71 417-436 (2003)

Fundamental Operation of the DBDFundamental Operation of the DBD

Electron DensityTemporal Development (ns)

y

Outer Contour Linen = 1010 cm-3ne = 1010 cm 3

Inner Contour Linene = 1014 cm-3

Streamer Propagation in 1 bar AirAA Kulikovsky IEEE Trans Plasma Sci 25 439-446 (1997)

Numerical Results of Microdischarge Formationin Dielectric Barrier Discharges

Starting Phase of a Microdischarge (1 bar 20 CO2 80 H2)

E0=34 kVcm1010 cm-3

1010 cm-3 ne=1012 cm-3

1mm10 cm

ne=108 cm-3

An electron avalanche propagates towards the anode

Reverse propagationtowards the cathodepropagates towards the anode towards the cathode

Numerical Results of Microdischarge Formationin Dielectric Barrier Discharges

Cathode Layer Formation

E0=34 kVcm1010 cm-39 3 0

1mm

1010 cm-3

10 cmne=109 cm-31014

10131014

1013

10 cm1012

Just before the peak of the total current

Peak currentof the total current

Numerical Results of Microdischarge Formationin Dielectric Barrier Discharges

Local Field Collapse in Area Defined by Surface Discharge

ne=109cm-3 ne=1014 cm-3

Gap

Principals of DBD MicroplasmasPrincipals of DBD MicroplasmasPrincipals of DBD MicroplasmasPrincipals of DBD Microplasmas

C C-- - --- - - CG

CD

-- - - CG

CD

Principals of DBD MicroplasmasPrincipals of DBD MicroplasmasPrincipals of DBD MicroplasmasPrincipals of DBD Microplasmas

Dielectric Barrier Discharge (DBD)Dielectric Barrier Discharge (DBD)Electric Field

B kdBreakdown

Electrons amp Ions Discharge Physics

Excited SpeciesPlasma Chemistry

Chemical Reactions

OzoneGeneration

SurfaceTreatment

PollutionControl

ExcimerFormation CO2 Lasers Hydrogenation

of CO2

Excimer Lamps Plasma Displays

How A Plasma Display Works

How A Plasma Display Work

Plasma Display TelevisionsPlasma Display Televisions

Ozone Generator

3 O 2 O

Dielectric Barrier Discharge

3 O2 2 O3

OO22 OO33++OO22Ondash ndashO3O2

O2O2

Ondash ndash

endash O2Ondash ndash O2endash

O3

O3O2O2 O2

HeatHeatHeatHeat

Properties of Ozone (O3)

T i t i f f Tri-atomic form of oxygen

Most powerful commercial oxidizing agent

Unstable - must be generated and used onsite

Limited solubility in water but more so than oxygenLimited solubility in water but more so than oxygen

Leaves a dissolved residual which ultimately converts back to oxygenconverts back to oxygen

Discharge Tubes in Ozone GeneratorsDischarge Tubes in Ozone Generators

Traditional

Ozone Generator

with Glass Tubes

Generation of OzoneGeneration of Ozone

Generation of OzoneAdvantages of Enamel Dielectrics

Proven Patented Designbull Simplicity

Si l Di l i Cbull Single Dielectric Componentndash Reduced number of Dielectrics

bull Safety ndash Lower operating voltage

(lt 4000 V)bull Reliabilty

ndash Fused Dielectrics ensure continuous production

bull Lowest Power Consumption Operational Savingsndash Operational Savings

Modern Ozone GeneratorModern Ozone Generator

Ozonia Advanced Technology Ozone GeneratorOzone Generator

Generation of OzoneGeneration of Ozone

Generation of Ozone

Power Supply UnitPower Supply Unit

IGBT Inverter CircuitMain Circuit Breaker

HV 480 Volts60 Hz3 Phase Supply

C I

450KVAPow er to

GeneratorFILTER

CONVERTER INVERTERTRANSFORMER

C I450KVA Power Stage

CONTACTOR

bull Latest in Power Semiconductor Technology Modular Design

bull Utilizes IGBTrsquos (Insulated Gate Bi‐Polar Transistors) Converter and Inverter Components

Ozone Water Treatment

B bbl Diff iB bbl Diff iBubble DiffusionBubble Diffusion

Easy to use

Low energy usage Low energy usage

Mass transfer efficiencies to gt 90

Ozone Process Flow DiagramOzone Process Flow DiagramVent to

Atmosphere

O OOxygen

Off-Gas Blower

Ozone Destruct Unit

10 12

O3O2

LOX

10-12 O3

Ozone Generators

Ozone Contact ChamberLOX T k Generators Chamber

VaporizersLOX Tank

Municipal Ozone Installations

Ozonia Installations Ozone Plant Size [lbday] Start-Up DateKey Ozonia Installations (Partial List)

Los Angeles CA 10000 1986Fairfax VA ndash Corbalis 9000 2003MWD CA ndash Mills 9 000 2003

Ozonia Installations Ozone Plant Size [lbday] Start Up Date

MWD CA Mills 9000 2003Fairfax Co VA ndash Griffith 9000 2004MWD CA ndash Jensen 18750 2005Indianapolis IN ndash Belmont AWT 12000 2007I di li IN 12 000 2007Indianapolis IN ndash Southport AWT 12000 2007MWD CA ndash Diemer 13400 2008MWD CA ndash Weymouth 13400 2009

Ozonia North America - Potable Water SummaryTotal Number of Installations 90Total Installed Production gt 265000 lbsdayTotal Installed Production 265000 lbsday

Revision -B

Ozone Water TreatmentOzone Water Treatment

MWD Mills WTP - California

3 3 000 lbsda of o one3 3 000 lbsda of o one3 x 3000 lbsday of ozone3 x 3000 lbsday of ozone

Ozone Water TreatmentOzone Water TreatmentOzone Ozone -- How it worksHow it works

OxidantOxidant DisinfectantDisinfectant

bullbull Breaks double carbon Breaks double carbon bondsbonds

bullbull Kills by cell lysing or Kills by cell lysing or causing the cell wall tocausing the cell wall tobondsbonds

bullbull Creates OHCreates OHbullbull radicals radicals which break higher carbon which break higher carbon

causing the cell wall to causing the cell wall to rupture rupture

bullbull AttacksAttacks allall bacteriabacteriabondsbondsbullbull Increased temp and pH Increased temp and pH

accelerates Oaccelerates O33

Attacks Attacks allall bacteria bacteria virus cysts and spores virus cysts and spores in varying degreesin varying degreesaccelerates Oaccelerates O33

decomposition to OHdecomposition to OHbullbull

Micro-organism DNA

Capsule AdenineAdenine

Cell wall ThymineThymine

CytosineCytosine

GuanineGuanine

NuclearmaterialCellmembrane

material

Typical Bacterium DNA

Microbial Growth at Various Ozone ConcentrationsConcentrations

Growth likely

Growth possibleGrowth possible

NO GROWTH

0004 0008 0012 0016 0020

Ozone concentration (mgl)Ozone concentration (mgl)

Typical Water Treatment UsageTypical Water Treatment Usage

Application O3 mgl Contact timeUltra Pure Water 005 - 025 sec ndash min

Water bottling 04 ndash 10 5 ndash 10 min

Swimming pools ampspas

01 ndash 075 4 minutes

Potable taste amp odor 15 ndash 50 5 ndash 10 mindisinfection

Microfloculation 10 ndash 30 5 ndash 10 min

Lignin amp tammin 3 0 10 0 10 30 minLignin amp tamminremoval

30 ndash 100 10 ndash 30 min

Municipal wastewater 50 ndash 150+ 15 ndash 30 min

Ozone Water TreatmentOzone Water TreatmentOzone Ozone ndashndash Municipal ApplicationsMunicipal Applications

bullbull Taste and OdorTaste and Odor

bullbull Color RemovalColor Removal

bullbull Disinfection Without Trihalomethanes (THMs)Disinfection Without Trihalomethanes (THMs)

bullbull Improved Filtration Efficiency and FlocculationImproved Filtration Efficiency and Flocculation

bullbull Cryptosporidium DeactivationCryptosporidium Deactivation

bullbull Giardia amp Virus InactivationGiardia amp Virus Inactivation

bullbull Oxidation Oxidation -- Organics Fe amp MnOrganics Fe amp Mn

bullbull Wastewater disinfectionWastewater disinfection

bullbull BOD COD and TOC reductionBOD COD and TOC reduction

Applications of Ozone

Wastewater Treatmentbull Disinfection of Secondary and Tertiary Effluentsbull Color Reductionbull Color Reductionbull TOC Oxidation (Industrial)bull Oxidation of Odor Causing Compoundsbull Oxidation of Endocrine Disruptors (EDCrsquos) and p ( )

Pharmaceutically Active Compounds (PACrsquos)

Applications of Ozone

What are Endocrine Disruptors (EDCrsquos) and What are Endocrine Disruptors (EDCrsquos) and Ph ti ll A ti C d (PACrsquo )Ph ti ll A ti C d (PACrsquo )Pharmaceutically Active Compounds (PACrsquos)Pharmaceutically Active Compounds (PACrsquos)

bullbull EDCrsquosEDCrsquos andand PACrsquosPACrsquos areare NaturallyNaturally andand SyntheticSyntheticdd th tth t ff tff t thth b lb l llcompoundscompounds thatthat maymay affectaffect thethe balancebalance oror normalnormal

functionsfunctions inin animalsanimals andand humanshumans

What can EDCrsquos and PACrsquos doWhat can EDCrsquos and PACrsquos do

bullbull Even in very small concentrations these compounds Even in very small concentrations these compounds y py pcan can disruptdisrupt normal bodily functionsnormal bodily functions

bullbull ManMan--made chemicals can trick the bodies endocrine made chemicals can trick the bodies endocrine system system

Applications of Ozone

Examples of Endocrine Disruptors1000rsquos of compounds that may be Investigated as EDCs ndash Some examples are

bullbull Synthetic HormonesSynthetic Hormonesbullbull Naturally Occurring Estrogens Naturally Occurring Estrogens

Health and Beauty AidsHealth and Beauty Aidsbullbull Health and Beauty AidsHealth and Beauty Aidsbullbull SolventsSolventsbullbull PesticidesPesticidesbullbull SurfactantsSurfactantsbullbull PlasticsPlastics

F i idF i idbullbull FungicidesFungicides

Ozone Water TreatmentOzone Water Treatment

Ozone Ozone -- Industrial ApplicationsIndustrial Applications-- Ultrapure Water for Pharmaceutical ApplicationsUltrapure Water for Pharmaceutical Applications

-- Wastewater disinfection color removalWastewater disinfection color removal

-- Soil and Groundwater Remediation Soil and Groundwater Remediation

-- Cooling Tower Water TreatmentCooling Tower Water Treatment

-- Food ProcessingFood Processing

-- Aquaculture AquariumsAquaculture AquariumsAquaculture AquariumsAquaculture Aquariums

-- Beverage ApplicationsBeverage Applications

P l amp P Bl hiP l amp P Bl hi-- Pulp amp Paper BleachingPulp amp Paper Bleaching

High Purity OzonationHigh Purity Ozonation

Microchip manufacturingMicrochip manufacturing

What are the current issues in large-scale gozone generationg

Experimental Setup

Front view of the two units after the redesign and reworking ofthe gas water and instruments connectionsthe gas water and instruments connections

Experimental Setup

Top view of the twoexperimental unitsexperimental unitsSpectroscope (notshown) is to the left ofthe DBD The units weredifferent with respect todifferent with respect totheir electrodes onehad only the electrodecoated with thedielectric (ldquosingle-dielectric ( single-coatedrdquo) the other onehad the electrode andthe anode coated withthe dielectric (ldquodouble-the dielectric ( double-coatedrdquo)

Basics Generation of OzoneBasics Generation of Ozone

SpectroscopyPlasma

Plasma Absorption SpectroscopyPlasma Absorption Spectroscopy

Infrared Absorption SpectroscopyInfrared Absorption Spectroscopy

IR spectra in pure oxygen (black curve) and at approximately 10wt N2 admixture (red line) N2O5 peaks appear at124 1 d 1 2 11245 cm-1 and at 1725 cm-1

Infrared Absorption SpectroscopyInfrared Absorption Spectroscopy

IR spectra of several methane variations The green curve envelopes all of the methane peaks at 1325 cm-1recorded at smaller methane admixtures Simultaneously the N2O5 peaks disappear as the methane peaks appear

N2O5 FormationN2O5 Formation2 52 5p=2 bara cwt=20degC q=35kWm2 f=1450Hz

45N2O5 AT95

30

35

40

N

2 B

lend

ing

N2O AT95N2O5 IGSN2O IGSN2O5 LGN2O LG

1 5

20

25

nt [p

pmV]

3

wt

05

10

15

NO

x co

nten

005 7 9 11 13 15 17

ozone conc [wt]

Amount of formed N2O5 and N2O as a function of ozone concentration at 3 wt of nitrogen admixture and fori l dvarious electrode arrangements

Plasma Emission SpectroscopyPlasma Emission Spectroscopyp pyp py

Relative Emissions of the Ozonizer plasmaRelative Emissions of the Ozonizer plasma

Region 300- 850 nm from individual (calibrated) regions (smoothed by PeakFit) Single-coated ozone generator Inlet side

3 5E+06

30E+06

35E+06

7 9

20E+06

25E+06

nten

sity

au

2

311 12

10E+06

15E+06

In 4

5

6 8 10

14

15

16

17

00E+00

50E+05

280 300 320 340 360 380 400 420 440 460 480 500 520 540 560 580 600 620 640 660 680 700 720 740 760 780 800 820 840 860

Wavelength nm

1 13

Wavelength nm

Absolute Emission of the DBD PlasmaAbsolute Emission of the DBD Plasma

Intensities in (O2+3 wtN2) plasma

1 20E+04

100E+04

120E+04

600E+03

800E+03

nten

sity

(au

)

200E+03

400E+03

In

O(777)

000E+00200 250 300 350 400 450 500 550 600 650 700 750 800 850

Wavelength nm

Intensities in 3 wtN2+O2 plasmaIntensities in 3 wtN2+O2 plasma

Plasma Chemistry in OzonizersPlasma Chemistry in Ozonizers

Dry Air O2 N2

e - e -

O N2 N O2

O3 NO

O2 N O2

O3

N

3

NO2

O2 O3

NO

N

NO2 O3

N2O

NO3 N

N2O4

NO2

NO2

N2O5

NO3

Primary electron-driven chemical reactions leading to the formation of N2O5 and N2O in a dry air plasma

Plasma emission diagnostics role of N2Plasma emission diagnostics role of N2

Dry Air O2 N2

e - e -

O N2 N O2

O3 NO

O2 N O2

O3

O

N

ON

NO2

O2O3

N

NO N

NO2 O3

N2O

NO3 N

N2O4

NO2

NO2

N2O5

NO3

ONbullWith N2 present ndash less oxygen atoms are formed However the difference in intensity is

very small

Modeling of plasma chemistry incl the NxOy chemistry up to N2O5 for different Oxygen Nitrogen mixtures varying power deposition scenarios

and initial ozone background concentrations (up to 15) previously done

The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation

The role of N2 must be related to its by-products reacting on the surface of the electrodeThe role of N2 must be related to its by-products reacting on the surface of the electrode

The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established

Ab 8 t f O

The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established

Ab 8 t f OAbove 8 wt of O3

1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)

Above 8 wt of O3

1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)case without pampp)

2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of the

case without pampp)

2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of thethem A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface

them A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface

The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation

Three possibilities have to be considered for the oxygen-fedozone generator

Three possibilities have to be considered for the oxygen-fedozone generatorozone generator

bull Excited N2 molecules lead to an increased O2 dissociation in

ozone generator

bull Excited N2 molecules lead to an increased O2 dissociation in2 2such case an increased efficiency is correlated to the N2admixture

2 2such case an increased efficiency is correlated to the N2admixture

bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial

bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial

bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2

bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2g p g 3 pp y 2g p g 3 pp y 2

Effect of methane on ozone efficiency and specific powerEffect of methane on ozone efficiency and specific power

Effect of Methane on Ozone Content in Outlet Gas and on Specific Power Pure O2

13 12

10

11

12

t 8

10

8

9

10

ne c

onte

nt w

t

6

8

ecifi

c po

wer

kW

hlb

5

6

7

Ozo

n

2

4 Spe

400E+00 20E+03 40E+03 60E+03 80E+03 10E+04 12E+04

Methane in feedgas ppm

0

Ozone content in the outlet gas Specif ic pow er of the ozone generatorg p p g

Effects of N2 and CH4Effects of N2 and CH4

Pi t f h t lli N O t tPicture of an amorphous-crystalline N2O5 structurecaptured at the Orlando Skylake water plant in 2006

Plasma Chemistry with CH4 Impurities

OxygenO2 N2

e - e -

CHO N2

NO2

O NO

O2 N O2 O3

NOH

CH4e-

O3 NO

NO2

O2O3NO N

NO2 O

NO2

NO2

N2ONO3

N

O3

NO2

NO

HNO3

N2O4

N2O5

NO2

NO3

N2O5

Effect of methane on the electrode surfaces

a) b)

Inlet Outlet Outlet

) d)

I l t I l t

c) d)

Electrode of the ozone generator afterseveral hours in CH8O2 and up to 2 wt of methane (a b c)

Inlet Inlet

three hours in CH8O2+traces of N2 and up to 1 wt of methane (d) Visible change of discharge character at about 13 length of electrode (a d)

Kinetics of CHx Conversion without N2

conversion by collisions

O2 + CHx 12wt O3 + CO2 +H2O

deposition vaporizationby sputtering

ibl b l 1000 CHreversible process below 1000ppm CH4

Effect of water on electrode surface with N2

Inlet

OutletOutlet

Electrode of the ozone generator after several hours in H OO N

Inlet

Electrode of the ozone generator after several hours in H2OO2N2

Effect of water on electrode surface

Long term effect (800 hrs) of H2OO2N2

Kinetics of CHx Conversion with N2

conversion by collisionsHNO3 formation

O2 + N2 +CHx 12wtO2 + CO2 +H2O + HNO3

deposition vaporizationby sputtering

H2O + HNO3

by sputtering

irreversible process above a N2 threshold () ltlt 1000ppm N2

sticky deposit

p 2 ( ) pp 2 any CH4 concentration (60ppm)

Plasma Chemistry with CH4 ImpuritiesPlasma Chemistry with CH4 Impurities4

bull Formation of NO and NO2 depends on O3 N2 and gas temperature Conclusion N2 admixture is the key factor

SummarySummaryyyThe mechanisms of formed NOx by-products follows the sameThe mechanisms of formed NOx by-products follows the sameprinciples as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentration

principles as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentrationozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)

ozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)g p ( g p )

The conversion of methane to OH and H2O is found to depend on

g p ( g p )

The conversion of methane to OH and H2O is found to depend ondissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)

dissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)discharge gap)discharge gap)

How do you optimize an ozone generatorg

Scientific ApproachScientific ApproachTheoretical Experimental

pppp

c [wt]

f [Hz]

c [wt]

f [Hz]

[kW]UUUβ1

1Cf4αPn

1iiminpeakimin

iiD

q [kWm2]q [kWm2]

150

180

][V]voltagepeakUpeak

[]cylinder perslicesofamountnsliceii

whereth

09 00

30

60

90

120

effic

ienc

y [

][0tdj t bl[F]sliceisdielectricofecapacitancC

[Hz]frequencyf[V]sliceivoltageminimumiUmin

thiD

th

10

28

46

64

82

39

107

176

244 power density

[kWm2]

ozone conc [wt][]CCβ

][0parameteradjustableα

iDiGi

Impact of Power Inductionp

350

400

wer

200

250

300

App

lied

Pow

Arr C 2Arr D +0

Arr E +45Arr F +7

Arr G +3

5 0

100

150

Frac

tion

of

1 2 3 4

ReferenceArr B unstable

Arr C -2

00

50

4Position (1inlet 4outlet)

Experimental Test Rigp g

Experimental Test Rigp g

Outer grounded electrode (left picture) and the dielectric covered inner electrodes (right) d e ect c cove ed e e ect odes ( g t)

Reference (Traditional) Arrangement

Inlet OutletGas flow direction

Optimized Arrangement

Inlet OutletGas flow direction

Intelligent Gap System (IGS)g p y ( )

Molecular Oxygen (O2) Ozone (O3)

O2 O3

yg ( 2) ( 3)

Particle Size SynthesisParticle Size SynthesisByBy--Products Cluster FormationProducts Cluster Formationyy

high diffusion and deposition to surfaces

low diffusion rate good transport

high sedimentation on the structurehigh sedimentation on the structure

Degreacutemont Technologies ndash OzoniaIntelligent Gap SystemIntelligent Gap System

G Vezzuacute JL Lopez A Freilich and K Becker Optimizationof Large-Scale Ozone Generators IEEE Transactions onPlasma Science Vol 37 No 6 p 890-896 (2009)

ConclusionsConclusionsConclusionsConclusionsFundamentals of ozone synthesis in a DBD plasmay p

ndash Highly filamented DBD discharges are best-suitedfor the production of ozone concentrations in therange of 6 to 14 wtrange of 6 to 14 wt

ndash The preferred characteristic of the microdischargesare Townsend-like at reduced electric fields Enaround 190 Townsend

ndash Detrimental side-effects induced by by-productscan be avoided by a proper design of the electrodecan be avoided by a proper design of the electrodearrangement The phenomenon is related to thediffusion rates of formed by-product clusters

ConclusionsConclusionsConclusionsConclusionsBenefits from DBD microplasma tailoring

ndash Reduced power consumption of up to 10 improvement

ndash Increased ozone concentrations of up to 14 now achievable

ndash Improved neutralization and conditioning of detrimental by-products

ndash Reduced system capital and operational cost

New technologies to improve ozone p

generatorg

HV Pulsed Power SwitchingHV Pulsed Power Switching

Microchannel Generation of Ozone

Channel ArrayChannel Array

Microchannel

330 microm 230 microm

Some Cap-DBD Devices Operating in Air

Increase of 60 of

Spacing 225 μmof 60 of plasma

No space

Cap‐DBD ozone generation

bull Ozone concentration is evaluated via Eco S d l UV 100 O A l (0 01Sensors model UV-100 Ozone Analyzer (001 ndash 900 ppm wiht an accuracy of plusmn2)

bull Three reactors 6 tubings 6rdquo with spacings of 0 μm 225 μm and 500 μm running at 3 kV μ μ μ g

SpacingOzone Concentration

3 kV rms 4 kV rms3 kV rms 4 kV rms

0 μm 660 ppm

225 μm 550 ppm

For a device of such small scale these ozone levels are promising

500 μm 380 ppm

J Mahoney W Zhu VS Johnson KH Becker and JL Lopez Electrical and optical emissionmeasurements of a capillary dielectric barrier discharge European Physics Journal D Vol 60 441-447(2010)

QuestionsQuestions

Thank YouFor more informationProf Jose L Lopez PhD

Thank YouFor more informationDepartment of Physics

Telephone (973) 761-9057Email joselopez1shuedu

Website wwwshueduacademicsartsciphysicsWebsite wwwshueduacademicsartsciphysics

Page 26: Dielectric Barrier Discharge (DBD) & Progress in Large ...bonitz/si12/talks/august_8/lopez_si12.pdf · Dielectric Barrier Discharge (DBD) & Progress in Large-Scale Ozone Generation

Role of the Dielectric (Insulator)

Th di l t i i th k f thThe dielectric is the key for the properfunctioning of the discharge

Serves two functions

1 Limits the amount of charge transportedby a single microplasma

2 Distributes the microplasmas over theentire electrode surface area

Equivalent Circuit of a Microdischarge

Microdischarge Activity and U-Q Lissajous Figure

B Eliasson and U Kogelschatz IEEE Transactions Plasma Science Vol 19 Issue 6 1063-1077 (1991)

Fundamental Operation of the Dielectric Barrier DischargeFundamental Operation of the Dielectric Barrier Discharge

bull Many of relevant plasma processes that areof importance to achieving our goal occuron time scales that allow us to study themon time scales that allow us to study them

bull Optical emission spectroscopic studies willallow us to determine the temporal andspatial development of important plasmaspatial development of important plasmaspecies such as radicals (OH NO variousoxygen radicals) with high time resolution(less than 10 ns) and a spatial resolution onthe scale of mm in the plasma volumepfollowing pulsed plasma excitation

Time scale of the relevant processes of the DBD

HE Wagner R Brandenburg et al lsquoThe barrier discharge basic properties and applications tosurface treatmentrsquo Vacuum 71 417-436 (2003)

Fundamental Operation of the DBDFundamental Operation of the DBD

Electron DensityTemporal Development (ns)

y

Outer Contour Linen = 1010 cm-3ne = 1010 cm 3

Inner Contour Linene = 1014 cm-3

Streamer Propagation in 1 bar AirAA Kulikovsky IEEE Trans Plasma Sci 25 439-446 (1997)

Numerical Results of Microdischarge Formationin Dielectric Barrier Discharges

Starting Phase of a Microdischarge (1 bar 20 CO2 80 H2)

E0=34 kVcm1010 cm-3

1010 cm-3 ne=1012 cm-3

1mm10 cm

ne=108 cm-3

An electron avalanche propagates towards the anode

Reverse propagationtowards the cathodepropagates towards the anode towards the cathode

Numerical Results of Microdischarge Formationin Dielectric Barrier Discharges

Cathode Layer Formation

E0=34 kVcm1010 cm-39 3 0

1mm

1010 cm-3

10 cmne=109 cm-31014

10131014

1013

10 cm1012

Just before the peak of the total current

Peak currentof the total current

Numerical Results of Microdischarge Formationin Dielectric Barrier Discharges

Local Field Collapse in Area Defined by Surface Discharge

ne=109cm-3 ne=1014 cm-3

Gap

Principals of DBD MicroplasmasPrincipals of DBD MicroplasmasPrincipals of DBD MicroplasmasPrincipals of DBD Microplasmas

C C-- - --- - - CG

CD

-- - - CG

CD

Principals of DBD MicroplasmasPrincipals of DBD MicroplasmasPrincipals of DBD MicroplasmasPrincipals of DBD Microplasmas

Dielectric Barrier Discharge (DBD)Dielectric Barrier Discharge (DBD)Electric Field

B kdBreakdown

Electrons amp Ions Discharge Physics

Excited SpeciesPlasma Chemistry

Chemical Reactions

OzoneGeneration

SurfaceTreatment

PollutionControl

ExcimerFormation CO2 Lasers Hydrogenation

of CO2

Excimer Lamps Plasma Displays

How A Plasma Display Works

How A Plasma Display Work

Plasma Display TelevisionsPlasma Display Televisions

Ozone Generator

3 O 2 O

Dielectric Barrier Discharge

3 O2 2 O3

OO22 OO33++OO22Ondash ndashO3O2

O2O2

Ondash ndash

endash O2Ondash ndash O2endash

O3

O3O2O2 O2

HeatHeatHeatHeat

Properties of Ozone (O3)

T i t i f f Tri-atomic form of oxygen

Most powerful commercial oxidizing agent

Unstable - must be generated and used onsite

Limited solubility in water but more so than oxygenLimited solubility in water but more so than oxygen

Leaves a dissolved residual which ultimately converts back to oxygenconverts back to oxygen

Discharge Tubes in Ozone GeneratorsDischarge Tubes in Ozone Generators

Traditional

Ozone Generator

with Glass Tubes

Generation of OzoneGeneration of Ozone

Generation of OzoneAdvantages of Enamel Dielectrics

Proven Patented Designbull Simplicity

Si l Di l i Cbull Single Dielectric Componentndash Reduced number of Dielectrics

bull Safety ndash Lower operating voltage

(lt 4000 V)bull Reliabilty

ndash Fused Dielectrics ensure continuous production

bull Lowest Power Consumption Operational Savingsndash Operational Savings

Modern Ozone GeneratorModern Ozone Generator

Ozonia Advanced Technology Ozone GeneratorOzone Generator

Generation of OzoneGeneration of Ozone

Generation of Ozone

Power Supply UnitPower Supply Unit

IGBT Inverter CircuitMain Circuit Breaker

HV 480 Volts60 Hz3 Phase Supply

C I

450KVAPow er to

GeneratorFILTER

CONVERTER INVERTERTRANSFORMER

C I450KVA Power Stage

CONTACTOR

bull Latest in Power Semiconductor Technology Modular Design

bull Utilizes IGBTrsquos (Insulated Gate Bi‐Polar Transistors) Converter and Inverter Components

Ozone Water Treatment

B bbl Diff iB bbl Diff iBubble DiffusionBubble Diffusion

Easy to use

Low energy usage Low energy usage

Mass transfer efficiencies to gt 90

Ozone Process Flow DiagramOzone Process Flow DiagramVent to

Atmosphere

O OOxygen

Off-Gas Blower

Ozone Destruct Unit

10 12

O3O2

LOX

10-12 O3

Ozone Generators

Ozone Contact ChamberLOX T k Generators Chamber

VaporizersLOX Tank

Municipal Ozone Installations

Ozonia Installations Ozone Plant Size [lbday] Start-Up DateKey Ozonia Installations (Partial List)

Los Angeles CA 10000 1986Fairfax VA ndash Corbalis 9000 2003MWD CA ndash Mills 9 000 2003

Ozonia Installations Ozone Plant Size [lbday] Start Up Date

MWD CA Mills 9000 2003Fairfax Co VA ndash Griffith 9000 2004MWD CA ndash Jensen 18750 2005Indianapolis IN ndash Belmont AWT 12000 2007I di li IN 12 000 2007Indianapolis IN ndash Southport AWT 12000 2007MWD CA ndash Diemer 13400 2008MWD CA ndash Weymouth 13400 2009

Ozonia North America - Potable Water SummaryTotal Number of Installations 90Total Installed Production gt 265000 lbsdayTotal Installed Production 265000 lbsday

Revision -B

Ozone Water TreatmentOzone Water Treatment

MWD Mills WTP - California

3 3 000 lbsda of o one3 3 000 lbsda of o one3 x 3000 lbsday of ozone3 x 3000 lbsday of ozone

Ozone Water TreatmentOzone Water TreatmentOzone Ozone -- How it worksHow it works

OxidantOxidant DisinfectantDisinfectant

bullbull Breaks double carbon Breaks double carbon bondsbonds

bullbull Kills by cell lysing or Kills by cell lysing or causing the cell wall tocausing the cell wall tobondsbonds

bullbull Creates OHCreates OHbullbull radicals radicals which break higher carbon which break higher carbon

causing the cell wall to causing the cell wall to rupture rupture

bullbull AttacksAttacks allall bacteriabacteriabondsbondsbullbull Increased temp and pH Increased temp and pH

accelerates Oaccelerates O33

Attacks Attacks allall bacteria bacteria virus cysts and spores virus cysts and spores in varying degreesin varying degreesaccelerates Oaccelerates O33

decomposition to OHdecomposition to OHbullbull

Micro-organism DNA

Capsule AdenineAdenine

Cell wall ThymineThymine

CytosineCytosine

GuanineGuanine

NuclearmaterialCellmembrane

material

Typical Bacterium DNA

Microbial Growth at Various Ozone ConcentrationsConcentrations

Growth likely

Growth possibleGrowth possible

NO GROWTH

0004 0008 0012 0016 0020

Ozone concentration (mgl)Ozone concentration (mgl)

Typical Water Treatment UsageTypical Water Treatment Usage

Application O3 mgl Contact timeUltra Pure Water 005 - 025 sec ndash min

Water bottling 04 ndash 10 5 ndash 10 min

Swimming pools ampspas

01 ndash 075 4 minutes

Potable taste amp odor 15 ndash 50 5 ndash 10 mindisinfection

Microfloculation 10 ndash 30 5 ndash 10 min

Lignin amp tammin 3 0 10 0 10 30 minLignin amp tamminremoval

30 ndash 100 10 ndash 30 min

Municipal wastewater 50 ndash 150+ 15 ndash 30 min

Ozone Water TreatmentOzone Water TreatmentOzone Ozone ndashndash Municipal ApplicationsMunicipal Applications

bullbull Taste and OdorTaste and Odor

bullbull Color RemovalColor Removal

bullbull Disinfection Without Trihalomethanes (THMs)Disinfection Without Trihalomethanes (THMs)

bullbull Improved Filtration Efficiency and FlocculationImproved Filtration Efficiency and Flocculation

bullbull Cryptosporidium DeactivationCryptosporidium Deactivation

bullbull Giardia amp Virus InactivationGiardia amp Virus Inactivation

bullbull Oxidation Oxidation -- Organics Fe amp MnOrganics Fe amp Mn

bullbull Wastewater disinfectionWastewater disinfection

bullbull BOD COD and TOC reductionBOD COD and TOC reduction

Applications of Ozone

Wastewater Treatmentbull Disinfection of Secondary and Tertiary Effluentsbull Color Reductionbull Color Reductionbull TOC Oxidation (Industrial)bull Oxidation of Odor Causing Compoundsbull Oxidation of Endocrine Disruptors (EDCrsquos) and p ( )

Pharmaceutically Active Compounds (PACrsquos)

Applications of Ozone

What are Endocrine Disruptors (EDCrsquos) and What are Endocrine Disruptors (EDCrsquos) and Ph ti ll A ti C d (PACrsquo )Ph ti ll A ti C d (PACrsquo )Pharmaceutically Active Compounds (PACrsquos)Pharmaceutically Active Compounds (PACrsquos)

bullbull EDCrsquosEDCrsquos andand PACrsquosPACrsquos areare NaturallyNaturally andand SyntheticSyntheticdd th tth t ff tff t thth b lb l llcompoundscompounds thatthat maymay affectaffect thethe balancebalance oror normalnormal

functionsfunctions inin animalsanimals andand humanshumans

What can EDCrsquos and PACrsquos doWhat can EDCrsquos and PACrsquos do

bullbull Even in very small concentrations these compounds Even in very small concentrations these compounds y py pcan can disruptdisrupt normal bodily functionsnormal bodily functions

bullbull ManMan--made chemicals can trick the bodies endocrine made chemicals can trick the bodies endocrine system system

Applications of Ozone

Examples of Endocrine Disruptors1000rsquos of compounds that may be Investigated as EDCs ndash Some examples are

bullbull Synthetic HormonesSynthetic Hormonesbullbull Naturally Occurring Estrogens Naturally Occurring Estrogens

Health and Beauty AidsHealth and Beauty Aidsbullbull Health and Beauty AidsHealth and Beauty Aidsbullbull SolventsSolventsbullbull PesticidesPesticidesbullbull SurfactantsSurfactantsbullbull PlasticsPlastics

F i idF i idbullbull FungicidesFungicides

Ozone Water TreatmentOzone Water Treatment

Ozone Ozone -- Industrial ApplicationsIndustrial Applications-- Ultrapure Water for Pharmaceutical ApplicationsUltrapure Water for Pharmaceutical Applications

-- Wastewater disinfection color removalWastewater disinfection color removal

-- Soil and Groundwater Remediation Soil and Groundwater Remediation

-- Cooling Tower Water TreatmentCooling Tower Water Treatment

-- Food ProcessingFood Processing

-- Aquaculture AquariumsAquaculture AquariumsAquaculture AquariumsAquaculture Aquariums

-- Beverage ApplicationsBeverage Applications

P l amp P Bl hiP l amp P Bl hi-- Pulp amp Paper BleachingPulp amp Paper Bleaching

High Purity OzonationHigh Purity Ozonation

Microchip manufacturingMicrochip manufacturing

What are the current issues in large-scale gozone generationg

Experimental Setup

Front view of the two units after the redesign and reworking ofthe gas water and instruments connectionsthe gas water and instruments connections

Experimental Setup

Top view of the twoexperimental unitsexperimental unitsSpectroscope (notshown) is to the left ofthe DBD The units weredifferent with respect todifferent with respect totheir electrodes onehad only the electrodecoated with thedielectric (ldquosingle-dielectric ( single-coatedrdquo) the other onehad the electrode andthe anode coated withthe dielectric (ldquodouble-the dielectric ( double-coatedrdquo)

Basics Generation of OzoneBasics Generation of Ozone

SpectroscopyPlasma

Plasma Absorption SpectroscopyPlasma Absorption Spectroscopy

Infrared Absorption SpectroscopyInfrared Absorption Spectroscopy

IR spectra in pure oxygen (black curve) and at approximately 10wt N2 admixture (red line) N2O5 peaks appear at124 1 d 1 2 11245 cm-1 and at 1725 cm-1

Infrared Absorption SpectroscopyInfrared Absorption Spectroscopy

IR spectra of several methane variations The green curve envelopes all of the methane peaks at 1325 cm-1recorded at smaller methane admixtures Simultaneously the N2O5 peaks disappear as the methane peaks appear

N2O5 FormationN2O5 Formation2 52 5p=2 bara cwt=20degC q=35kWm2 f=1450Hz

45N2O5 AT95

30

35

40

N

2 B

lend

ing

N2O AT95N2O5 IGSN2O IGSN2O5 LGN2O LG

1 5

20

25

nt [p

pmV]

3

wt

05

10

15

NO

x co

nten

005 7 9 11 13 15 17

ozone conc [wt]

Amount of formed N2O5 and N2O as a function of ozone concentration at 3 wt of nitrogen admixture and fori l dvarious electrode arrangements

Plasma Emission SpectroscopyPlasma Emission Spectroscopyp pyp py

Relative Emissions of the Ozonizer plasmaRelative Emissions of the Ozonizer plasma

Region 300- 850 nm from individual (calibrated) regions (smoothed by PeakFit) Single-coated ozone generator Inlet side

3 5E+06

30E+06

35E+06

7 9

20E+06

25E+06

nten

sity

au

2

311 12

10E+06

15E+06

In 4

5

6 8 10

14

15

16

17

00E+00

50E+05

280 300 320 340 360 380 400 420 440 460 480 500 520 540 560 580 600 620 640 660 680 700 720 740 760 780 800 820 840 860

Wavelength nm

1 13

Wavelength nm

Absolute Emission of the DBD PlasmaAbsolute Emission of the DBD Plasma

Intensities in (O2+3 wtN2) plasma

1 20E+04

100E+04

120E+04

600E+03

800E+03

nten

sity

(au

)

200E+03

400E+03

In

O(777)

000E+00200 250 300 350 400 450 500 550 600 650 700 750 800 850

Wavelength nm

Intensities in 3 wtN2+O2 plasmaIntensities in 3 wtN2+O2 plasma

Plasma Chemistry in OzonizersPlasma Chemistry in Ozonizers

Dry Air O2 N2

e - e -

O N2 N O2

O3 NO

O2 N O2

O3

N

3

NO2

O2 O3

NO

N

NO2 O3

N2O

NO3 N

N2O4

NO2

NO2

N2O5

NO3

Primary electron-driven chemical reactions leading to the formation of N2O5 and N2O in a dry air plasma

Plasma emission diagnostics role of N2Plasma emission diagnostics role of N2

Dry Air O2 N2

e - e -

O N2 N O2

O3 NO

O2 N O2

O3

O

N

ON

NO2

O2O3

N

NO N

NO2 O3

N2O

NO3 N

N2O4

NO2

NO2

N2O5

NO3

ONbullWith N2 present ndash less oxygen atoms are formed However the difference in intensity is

very small

Modeling of plasma chemistry incl the NxOy chemistry up to N2O5 for different Oxygen Nitrogen mixtures varying power deposition scenarios

and initial ozone background concentrations (up to 15) previously done

The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation

The role of N2 must be related to its by-products reacting on the surface of the electrodeThe role of N2 must be related to its by-products reacting on the surface of the electrode

The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established

Ab 8 t f O

The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established

Ab 8 t f OAbove 8 wt of O3

1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)

Above 8 wt of O3

1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)case without pampp)

2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of the

case without pampp)

2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of thethem A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface

them A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface

The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation

Three possibilities have to be considered for the oxygen-fedozone generator

Three possibilities have to be considered for the oxygen-fedozone generatorozone generator

bull Excited N2 molecules lead to an increased O2 dissociation in

ozone generator

bull Excited N2 molecules lead to an increased O2 dissociation in2 2such case an increased efficiency is correlated to the N2admixture

2 2such case an increased efficiency is correlated to the N2admixture

bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial

bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial

bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2

bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2g p g 3 pp y 2g p g 3 pp y 2

Effect of methane on ozone efficiency and specific powerEffect of methane on ozone efficiency and specific power

Effect of Methane on Ozone Content in Outlet Gas and on Specific Power Pure O2

13 12

10

11

12

t 8

10

8

9

10

ne c

onte

nt w

t

6

8

ecifi

c po

wer

kW

hlb

5

6

7

Ozo

n

2

4 Spe

400E+00 20E+03 40E+03 60E+03 80E+03 10E+04 12E+04

Methane in feedgas ppm

0

Ozone content in the outlet gas Specif ic pow er of the ozone generatorg p p g

Effects of N2 and CH4Effects of N2 and CH4

Pi t f h t lli N O t tPicture of an amorphous-crystalline N2O5 structurecaptured at the Orlando Skylake water plant in 2006

Plasma Chemistry with CH4 Impurities

OxygenO2 N2

e - e -

CHO N2

NO2

O NO

O2 N O2 O3

NOH

CH4e-

O3 NO

NO2

O2O3NO N

NO2 O

NO2

NO2

N2ONO3

N

O3

NO2

NO

HNO3

N2O4

N2O5

NO2

NO3

N2O5

Effect of methane on the electrode surfaces

a) b)

Inlet Outlet Outlet

) d)

I l t I l t

c) d)

Electrode of the ozone generator afterseveral hours in CH8O2 and up to 2 wt of methane (a b c)

Inlet Inlet

three hours in CH8O2+traces of N2 and up to 1 wt of methane (d) Visible change of discharge character at about 13 length of electrode (a d)

Kinetics of CHx Conversion without N2

conversion by collisions

O2 + CHx 12wt O3 + CO2 +H2O

deposition vaporizationby sputtering

ibl b l 1000 CHreversible process below 1000ppm CH4

Effect of water on electrode surface with N2

Inlet

OutletOutlet

Electrode of the ozone generator after several hours in H OO N

Inlet

Electrode of the ozone generator after several hours in H2OO2N2

Effect of water on electrode surface

Long term effect (800 hrs) of H2OO2N2

Kinetics of CHx Conversion with N2

conversion by collisionsHNO3 formation

O2 + N2 +CHx 12wtO2 + CO2 +H2O + HNO3

deposition vaporizationby sputtering

H2O + HNO3

by sputtering

irreversible process above a N2 threshold () ltlt 1000ppm N2

sticky deposit

p 2 ( ) pp 2 any CH4 concentration (60ppm)

Plasma Chemistry with CH4 ImpuritiesPlasma Chemistry with CH4 Impurities4

bull Formation of NO and NO2 depends on O3 N2 and gas temperature Conclusion N2 admixture is the key factor

SummarySummaryyyThe mechanisms of formed NOx by-products follows the sameThe mechanisms of formed NOx by-products follows the sameprinciples as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentration

principles as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentrationozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)

ozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)g p ( g p )

The conversion of methane to OH and H2O is found to depend on

g p ( g p )

The conversion of methane to OH and H2O is found to depend ondissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)

dissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)discharge gap)discharge gap)

How do you optimize an ozone generatorg

Scientific ApproachScientific ApproachTheoretical Experimental

pppp

c [wt]

f [Hz]

c [wt]

f [Hz]

[kW]UUUβ1

1Cf4αPn

1iiminpeakimin

iiD

q [kWm2]q [kWm2]

150

180

][V]voltagepeakUpeak

[]cylinder perslicesofamountnsliceii

whereth

09 00

30

60

90

120

effic

ienc

y [

][0tdj t bl[F]sliceisdielectricofecapacitancC

[Hz]frequencyf[V]sliceivoltageminimumiUmin

thiD

th

10

28

46

64

82

39

107

176

244 power density

[kWm2]

ozone conc [wt][]CCβ

][0parameteradjustableα

iDiGi

Impact of Power Inductionp

350

400

wer

200

250

300

App

lied

Pow

Arr C 2Arr D +0

Arr E +45Arr F +7

Arr G +3

5 0

100

150

Frac

tion

of

1 2 3 4

ReferenceArr B unstable

Arr C -2

00

50

4Position (1inlet 4outlet)

Experimental Test Rigp g

Experimental Test Rigp g

Outer grounded electrode (left picture) and the dielectric covered inner electrodes (right) d e ect c cove ed e e ect odes ( g t)

Reference (Traditional) Arrangement

Inlet OutletGas flow direction

Optimized Arrangement

Inlet OutletGas flow direction

Intelligent Gap System (IGS)g p y ( )

Molecular Oxygen (O2) Ozone (O3)

O2 O3

yg ( 2) ( 3)

Particle Size SynthesisParticle Size SynthesisByBy--Products Cluster FormationProducts Cluster Formationyy

high diffusion and deposition to surfaces

low diffusion rate good transport

high sedimentation on the structurehigh sedimentation on the structure

Degreacutemont Technologies ndash OzoniaIntelligent Gap SystemIntelligent Gap System

G Vezzuacute JL Lopez A Freilich and K Becker Optimizationof Large-Scale Ozone Generators IEEE Transactions onPlasma Science Vol 37 No 6 p 890-896 (2009)

ConclusionsConclusionsConclusionsConclusionsFundamentals of ozone synthesis in a DBD plasmay p

ndash Highly filamented DBD discharges are best-suitedfor the production of ozone concentrations in therange of 6 to 14 wtrange of 6 to 14 wt

ndash The preferred characteristic of the microdischargesare Townsend-like at reduced electric fields Enaround 190 Townsend

ndash Detrimental side-effects induced by by-productscan be avoided by a proper design of the electrodecan be avoided by a proper design of the electrodearrangement The phenomenon is related to thediffusion rates of formed by-product clusters

ConclusionsConclusionsConclusionsConclusionsBenefits from DBD microplasma tailoring

ndash Reduced power consumption of up to 10 improvement

ndash Increased ozone concentrations of up to 14 now achievable

ndash Improved neutralization and conditioning of detrimental by-products

ndash Reduced system capital and operational cost

New technologies to improve ozone p

generatorg

HV Pulsed Power SwitchingHV Pulsed Power Switching

Microchannel Generation of Ozone

Channel ArrayChannel Array

Microchannel

330 microm 230 microm

Some Cap-DBD Devices Operating in Air

Increase of 60 of

Spacing 225 μmof 60 of plasma

No space

Cap‐DBD ozone generation

bull Ozone concentration is evaluated via Eco S d l UV 100 O A l (0 01Sensors model UV-100 Ozone Analyzer (001 ndash 900 ppm wiht an accuracy of plusmn2)

bull Three reactors 6 tubings 6rdquo with spacings of 0 μm 225 μm and 500 μm running at 3 kV μ μ μ g

SpacingOzone Concentration

3 kV rms 4 kV rms3 kV rms 4 kV rms

0 μm 660 ppm

225 μm 550 ppm

For a device of such small scale these ozone levels are promising

500 μm 380 ppm

J Mahoney W Zhu VS Johnson KH Becker and JL Lopez Electrical and optical emissionmeasurements of a capillary dielectric barrier discharge European Physics Journal D Vol 60 441-447(2010)

QuestionsQuestions

Thank YouFor more informationProf Jose L Lopez PhD

Thank YouFor more informationDepartment of Physics

Telephone (973) 761-9057Email joselopez1shuedu

Website wwwshueduacademicsartsciphysicsWebsite wwwshueduacademicsartsciphysics

Page 27: Dielectric Barrier Discharge (DBD) & Progress in Large ...bonitz/si12/talks/august_8/lopez_si12.pdf · Dielectric Barrier Discharge (DBD) & Progress in Large-Scale Ozone Generation

Equivalent Circuit of a Microdischarge

Microdischarge Activity and U-Q Lissajous Figure

B Eliasson and U Kogelschatz IEEE Transactions Plasma Science Vol 19 Issue 6 1063-1077 (1991)

Fundamental Operation of the Dielectric Barrier DischargeFundamental Operation of the Dielectric Barrier Discharge

bull Many of relevant plasma processes that areof importance to achieving our goal occuron time scales that allow us to study themon time scales that allow us to study them

bull Optical emission spectroscopic studies willallow us to determine the temporal andspatial development of important plasmaspatial development of important plasmaspecies such as radicals (OH NO variousoxygen radicals) with high time resolution(less than 10 ns) and a spatial resolution onthe scale of mm in the plasma volumepfollowing pulsed plasma excitation

Time scale of the relevant processes of the DBD

HE Wagner R Brandenburg et al lsquoThe barrier discharge basic properties and applications tosurface treatmentrsquo Vacuum 71 417-436 (2003)

Fundamental Operation of the DBDFundamental Operation of the DBD

Electron DensityTemporal Development (ns)

y

Outer Contour Linen = 1010 cm-3ne = 1010 cm 3

Inner Contour Linene = 1014 cm-3

Streamer Propagation in 1 bar AirAA Kulikovsky IEEE Trans Plasma Sci 25 439-446 (1997)

Numerical Results of Microdischarge Formationin Dielectric Barrier Discharges

Starting Phase of a Microdischarge (1 bar 20 CO2 80 H2)

E0=34 kVcm1010 cm-3

1010 cm-3 ne=1012 cm-3

1mm10 cm

ne=108 cm-3

An electron avalanche propagates towards the anode

Reverse propagationtowards the cathodepropagates towards the anode towards the cathode

Numerical Results of Microdischarge Formationin Dielectric Barrier Discharges

Cathode Layer Formation

E0=34 kVcm1010 cm-39 3 0

1mm

1010 cm-3

10 cmne=109 cm-31014

10131014

1013

10 cm1012

Just before the peak of the total current

Peak currentof the total current

Numerical Results of Microdischarge Formationin Dielectric Barrier Discharges

Local Field Collapse in Area Defined by Surface Discharge

ne=109cm-3 ne=1014 cm-3

Gap

Principals of DBD MicroplasmasPrincipals of DBD MicroplasmasPrincipals of DBD MicroplasmasPrincipals of DBD Microplasmas

C C-- - --- - - CG

CD

-- - - CG

CD

Principals of DBD MicroplasmasPrincipals of DBD MicroplasmasPrincipals of DBD MicroplasmasPrincipals of DBD Microplasmas

Dielectric Barrier Discharge (DBD)Dielectric Barrier Discharge (DBD)Electric Field

B kdBreakdown

Electrons amp Ions Discharge Physics

Excited SpeciesPlasma Chemistry

Chemical Reactions

OzoneGeneration

SurfaceTreatment

PollutionControl

ExcimerFormation CO2 Lasers Hydrogenation

of CO2

Excimer Lamps Plasma Displays

How A Plasma Display Works

How A Plasma Display Work

Plasma Display TelevisionsPlasma Display Televisions

Ozone Generator

3 O 2 O

Dielectric Barrier Discharge

3 O2 2 O3

OO22 OO33++OO22Ondash ndashO3O2

O2O2

Ondash ndash

endash O2Ondash ndash O2endash

O3

O3O2O2 O2

HeatHeatHeatHeat

Properties of Ozone (O3)

T i t i f f Tri-atomic form of oxygen

Most powerful commercial oxidizing agent

Unstable - must be generated and used onsite

Limited solubility in water but more so than oxygenLimited solubility in water but more so than oxygen

Leaves a dissolved residual which ultimately converts back to oxygenconverts back to oxygen

Discharge Tubes in Ozone GeneratorsDischarge Tubes in Ozone Generators

Traditional

Ozone Generator

with Glass Tubes

Generation of OzoneGeneration of Ozone

Generation of OzoneAdvantages of Enamel Dielectrics

Proven Patented Designbull Simplicity

Si l Di l i Cbull Single Dielectric Componentndash Reduced number of Dielectrics

bull Safety ndash Lower operating voltage

(lt 4000 V)bull Reliabilty

ndash Fused Dielectrics ensure continuous production

bull Lowest Power Consumption Operational Savingsndash Operational Savings

Modern Ozone GeneratorModern Ozone Generator

Ozonia Advanced Technology Ozone GeneratorOzone Generator

Generation of OzoneGeneration of Ozone

Generation of Ozone

Power Supply UnitPower Supply Unit

IGBT Inverter CircuitMain Circuit Breaker

HV 480 Volts60 Hz3 Phase Supply

C I

450KVAPow er to

GeneratorFILTER

CONVERTER INVERTERTRANSFORMER

C I450KVA Power Stage

CONTACTOR

bull Latest in Power Semiconductor Technology Modular Design

bull Utilizes IGBTrsquos (Insulated Gate Bi‐Polar Transistors) Converter and Inverter Components

Ozone Water Treatment

B bbl Diff iB bbl Diff iBubble DiffusionBubble Diffusion

Easy to use

Low energy usage Low energy usage

Mass transfer efficiencies to gt 90

Ozone Process Flow DiagramOzone Process Flow DiagramVent to

Atmosphere

O OOxygen

Off-Gas Blower

Ozone Destruct Unit

10 12

O3O2

LOX

10-12 O3

Ozone Generators

Ozone Contact ChamberLOX T k Generators Chamber

VaporizersLOX Tank

Municipal Ozone Installations

Ozonia Installations Ozone Plant Size [lbday] Start-Up DateKey Ozonia Installations (Partial List)

Los Angeles CA 10000 1986Fairfax VA ndash Corbalis 9000 2003MWD CA ndash Mills 9 000 2003

Ozonia Installations Ozone Plant Size [lbday] Start Up Date

MWD CA Mills 9000 2003Fairfax Co VA ndash Griffith 9000 2004MWD CA ndash Jensen 18750 2005Indianapolis IN ndash Belmont AWT 12000 2007I di li IN 12 000 2007Indianapolis IN ndash Southport AWT 12000 2007MWD CA ndash Diemer 13400 2008MWD CA ndash Weymouth 13400 2009

Ozonia North America - Potable Water SummaryTotal Number of Installations 90Total Installed Production gt 265000 lbsdayTotal Installed Production 265000 lbsday

Revision -B

Ozone Water TreatmentOzone Water Treatment

MWD Mills WTP - California

3 3 000 lbsda of o one3 3 000 lbsda of o one3 x 3000 lbsday of ozone3 x 3000 lbsday of ozone

Ozone Water TreatmentOzone Water TreatmentOzone Ozone -- How it worksHow it works

OxidantOxidant DisinfectantDisinfectant

bullbull Breaks double carbon Breaks double carbon bondsbonds

bullbull Kills by cell lysing or Kills by cell lysing or causing the cell wall tocausing the cell wall tobondsbonds

bullbull Creates OHCreates OHbullbull radicals radicals which break higher carbon which break higher carbon

causing the cell wall to causing the cell wall to rupture rupture

bullbull AttacksAttacks allall bacteriabacteriabondsbondsbullbull Increased temp and pH Increased temp and pH

accelerates Oaccelerates O33

Attacks Attacks allall bacteria bacteria virus cysts and spores virus cysts and spores in varying degreesin varying degreesaccelerates Oaccelerates O33

decomposition to OHdecomposition to OHbullbull

Micro-organism DNA

Capsule AdenineAdenine

Cell wall ThymineThymine

CytosineCytosine

GuanineGuanine

NuclearmaterialCellmembrane

material

Typical Bacterium DNA

Microbial Growth at Various Ozone ConcentrationsConcentrations

Growth likely

Growth possibleGrowth possible

NO GROWTH

0004 0008 0012 0016 0020

Ozone concentration (mgl)Ozone concentration (mgl)

Typical Water Treatment UsageTypical Water Treatment Usage

Application O3 mgl Contact timeUltra Pure Water 005 - 025 sec ndash min

Water bottling 04 ndash 10 5 ndash 10 min

Swimming pools ampspas

01 ndash 075 4 minutes

Potable taste amp odor 15 ndash 50 5 ndash 10 mindisinfection

Microfloculation 10 ndash 30 5 ndash 10 min

Lignin amp tammin 3 0 10 0 10 30 minLignin amp tamminremoval

30 ndash 100 10 ndash 30 min

Municipal wastewater 50 ndash 150+ 15 ndash 30 min

Ozone Water TreatmentOzone Water TreatmentOzone Ozone ndashndash Municipal ApplicationsMunicipal Applications

bullbull Taste and OdorTaste and Odor

bullbull Color RemovalColor Removal

bullbull Disinfection Without Trihalomethanes (THMs)Disinfection Without Trihalomethanes (THMs)

bullbull Improved Filtration Efficiency and FlocculationImproved Filtration Efficiency and Flocculation

bullbull Cryptosporidium DeactivationCryptosporidium Deactivation

bullbull Giardia amp Virus InactivationGiardia amp Virus Inactivation

bullbull Oxidation Oxidation -- Organics Fe amp MnOrganics Fe amp Mn

bullbull Wastewater disinfectionWastewater disinfection

bullbull BOD COD and TOC reductionBOD COD and TOC reduction

Applications of Ozone

Wastewater Treatmentbull Disinfection of Secondary and Tertiary Effluentsbull Color Reductionbull Color Reductionbull TOC Oxidation (Industrial)bull Oxidation of Odor Causing Compoundsbull Oxidation of Endocrine Disruptors (EDCrsquos) and p ( )

Pharmaceutically Active Compounds (PACrsquos)

Applications of Ozone

What are Endocrine Disruptors (EDCrsquos) and What are Endocrine Disruptors (EDCrsquos) and Ph ti ll A ti C d (PACrsquo )Ph ti ll A ti C d (PACrsquo )Pharmaceutically Active Compounds (PACrsquos)Pharmaceutically Active Compounds (PACrsquos)

bullbull EDCrsquosEDCrsquos andand PACrsquosPACrsquos areare NaturallyNaturally andand SyntheticSyntheticdd th tth t ff tff t thth b lb l llcompoundscompounds thatthat maymay affectaffect thethe balancebalance oror normalnormal

functionsfunctions inin animalsanimals andand humanshumans

What can EDCrsquos and PACrsquos doWhat can EDCrsquos and PACrsquos do

bullbull Even in very small concentrations these compounds Even in very small concentrations these compounds y py pcan can disruptdisrupt normal bodily functionsnormal bodily functions

bullbull ManMan--made chemicals can trick the bodies endocrine made chemicals can trick the bodies endocrine system system

Applications of Ozone

Examples of Endocrine Disruptors1000rsquos of compounds that may be Investigated as EDCs ndash Some examples are

bullbull Synthetic HormonesSynthetic Hormonesbullbull Naturally Occurring Estrogens Naturally Occurring Estrogens

Health and Beauty AidsHealth and Beauty Aidsbullbull Health and Beauty AidsHealth and Beauty Aidsbullbull SolventsSolventsbullbull PesticidesPesticidesbullbull SurfactantsSurfactantsbullbull PlasticsPlastics

F i idF i idbullbull FungicidesFungicides

Ozone Water TreatmentOzone Water Treatment

Ozone Ozone -- Industrial ApplicationsIndustrial Applications-- Ultrapure Water for Pharmaceutical ApplicationsUltrapure Water for Pharmaceutical Applications

-- Wastewater disinfection color removalWastewater disinfection color removal

-- Soil and Groundwater Remediation Soil and Groundwater Remediation

-- Cooling Tower Water TreatmentCooling Tower Water Treatment

-- Food ProcessingFood Processing

-- Aquaculture AquariumsAquaculture AquariumsAquaculture AquariumsAquaculture Aquariums

-- Beverage ApplicationsBeverage Applications

P l amp P Bl hiP l amp P Bl hi-- Pulp amp Paper BleachingPulp amp Paper Bleaching

High Purity OzonationHigh Purity Ozonation

Microchip manufacturingMicrochip manufacturing

What are the current issues in large-scale gozone generationg

Experimental Setup

Front view of the two units after the redesign and reworking ofthe gas water and instruments connectionsthe gas water and instruments connections

Experimental Setup

Top view of the twoexperimental unitsexperimental unitsSpectroscope (notshown) is to the left ofthe DBD The units weredifferent with respect todifferent with respect totheir electrodes onehad only the electrodecoated with thedielectric (ldquosingle-dielectric ( single-coatedrdquo) the other onehad the electrode andthe anode coated withthe dielectric (ldquodouble-the dielectric ( double-coatedrdquo)

Basics Generation of OzoneBasics Generation of Ozone

SpectroscopyPlasma

Plasma Absorption SpectroscopyPlasma Absorption Spectroscopy

Infrared Absorption SpectroscopyInfrared Absorption Spectroscopy

IR spectra in pure oxygen (black curve) and at approximately 10wt N2 admixture (red line) N2O5 peaks appear at124 1 d 1 2 11245 cm-1 and at 1725 cm-1

Infrared Absorption SpectroscopyInfrared Absorption Spectroscopy

IR spectra of several methane variations The green curve envelopes all of the methane peaks at 1325 cm-1recorded at smaller methane admixtures Simultaneously the N2O5 peaks disappear as the methane peaks appear

N2O5 FormationN2O5 Formation2 52 5p=2 bara cwt=20degC q=35kWm2 f=1450Hz

45N2O5 AT95

30

35

40

N

2 B

lend

ing

N2O AT95N2O5 IGSN2O IGSN2O5 LGN2O LG

1 5

20

25

nt [p

pmV]

3

wt

05

10

15

NO

x co

nten

005 7 9 11 13 15 17

ozone conc [wt]

Amount of formed N2O5 and N2O as a function of ozone concentration at 3 wt of nitrogen admixture and fori l dvarious electrode arrangements

Plasma Emission SpectroscopyPlasma Emission Spectroscopyp pyp py

Relative Emissions of the Ozonizer plasmaRelative Emissions of the Ozonizer plasma

Region 300- 850 nm from individual (calibrated) regions (smoothed by PeakFit) Single-coated ozone generator Inlet side

3 5E+06

30E+06

35E+06

7 9

20E+06

25E+06

nten

sity

au

2

311 12

10E+06

15E+06

In 4

5

6 8 10

14

15

16

17

00E+00

50E+05

280 300 320 340 360 380 400 420 440 460 480 500 520 540 560 580 600 620 640 660 680 700 720 740 760 780 800 820 840 860

Wavelength nm

1 13

Wavelength nm

Absolute Emission of the DBD PlasmaAbsolute Emission of the DBD Plasma

Intensities in (O2+3 wtN2) plasma

1 20E+04

100E+04

120E+04

600E+03

800E+03

nten

sity

(au

)

200E+03

400E+03

In

O(777)

000E+00200 250 300 350 400 450 500 550 600 650 700 750 800 850

Wavelength nm

Intensities in 3 wtN2+O2 plasmaIntensities in 3 wtN2+O2 plasma

Plasma Chemistry in OzonizersPlasma Chemistry in Ozonizers

Dry Air O2 N2

e - e -

O N2 N O2

O3 NO

O2 N O2

O3

N

3

NO2

O2 O3

NO

N

NO2 O3

N2O

NO3 N

N2O4

NO2

NO2

N2O5

NO3

Primary electron-driven chemical reactions leading to the formation of N2O5 and N2O in a dry air plasma

Plasma emission diagnostics role of N2Plasma emission diagnostics role of N2

Dry Air O2 N2

e - e -

O N2 N O2

O3 NO

O2 N O2

O3

O

N

ON

NO2

O2O3

N

NO N

NO2 O3

N2O

NO3 N

N2O4

NO2

NO2

N2O5

NO3

ONbullWith N2 present ndash less oxygen atoms are formed However the difference in intensity is

very small

Modeling of plasma chemistry incl the NxOy chemistry up to N2O5 for different Oxygen Nitrogen mixtures varying power deposition scenarios

and initial ozone background concentrations (up to 15) previously done

The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation

The role of N2 must be related to its by-products reacting on the surface of the electrodeThe role of N2 must be related to its by-products reacting on the surface of the electrode

The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established

Ab 8 t f O

The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established

Ab 8 t f OAbove 8 wt of O3

1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)

Above 8 wt of O3

1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)case without pampp)

2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of the

case without pampp)

2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of thethem A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface

them A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface

The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation

Three possibilities have to be considered for the oxygen-fedozone generator

Three possibilities have to be considered for the oxygen-fedozone generatorozone generator

bull Excited N2 molecules lead to an increased O2 dissociation in

ozone generator

bull Excited N2 molecules lead to an increased O2 dissociation in2 2such case an increased efficiency is correlated to the N2admixture

2 2such case an increased efficiency is correlated to the N2admixture

bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial

bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial

bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2

bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2g p g 3 pp y 2g p g 3 pp y 2

Effect of methane on ozone efficiency and specific powerEffect of methane on ozone efficiency and specific power

Effect of Methane on Ozone Content in Outlet Gas and on Specific Power Pure O2

13 12

10

11

12

t 8

10

8

9

10

ne c

onte

nt w

t

6

8

ecifi

c po

wer

kW

hlb

5

6

7

Ozo

n

2

4 Spe

400E+00 20E+03 40E+03 60E+03 80E+03 10E+04 12E+04

Methane in feedgas ppm

0

Ozone content in the outlet gas Specif ic pow er of the ozone generatorg p p g

Effects of N2 and CH4Effects of N2 and CH4

Pi t f h t lli N O t tPicture of an amorphous-crystalline N2O5 structurecaptured at the Orlando Skylake water plant in 2006

Plasma Chemistry with CH4 Impurities

OxygenO2 N2

e - e -

CHO N2

NO2

O NO

O2 N O2 O3

NOH

CH4e-

O3 NO

NO2

O2O3NO N

NO2 O

NO2

NO2

N2ONO3

N

O3

NO2

NO

HNO3

N2O4

N2O5

NO2

NO3

N2O5

Effect of methane on the electrode surfaces

a) b)

Inlet Outlet Outlet

) d)

I l t I l t

c) d)

Electrode of the ozone generator afterseveral hours in CH8O2 and up to 2 wt of methane (a b c)

Inlet Inlet

three hours in CH8O2+traces of N2 and up to 1 wt of methane (d) Visible change of discharge character at about 13 length of electrode (a d)

Kinetics of CHx Conversion without N2

conversion by collisions

O2 + CHx 12wt O3 + CO2 +H2O

deposition vaporizationby sputtering

ibl b l 1000 CHreversible process below 1000ppm CH4

Effect of water on electrode surface with N2

Inlet

OutletOutlet

Electrode of the ozone generator after several hours in H OO N

Inlet

Electrode of the ozone generator after several hours in H2OO2N2

Effect of water on electrode surface

Long term effect (800 hrs) of H2OO2N2

Kinetics of CHx Conversion with N2

conversion by collisionsHNO3 formation

O2 + N2 +CHx 12wtO2 + CO2 +H2O + HNO3

deposition vaporizationby sputtering

H2O + HNO3

by sputtering

irreversible process above a N2 threshold () ltlt 1000ppm N2

sticky deposit

p 2 ( ) pp 2 any CH4 concentration (60ppm)

Plasma Chemistry with CH4 ImpuritiesPlasma Chemistry with CH4 Impurities4

bull Formation of NO and NO2 depends on O3 N2 and gas temperature Conclusion N2 admixture is the key factor

SummarySummaryyyThe mechanisms of formed NOx by-products follows the sameThe mechanisms of formed NOx by-products follows the sameprinciples as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentration

principles as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentrationozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)

ozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)g p ( g p )

The conversion of methane to OH and H2O is found to depend on

g p ( g p )

The conversion of methane to OH and H2O is found to depend ondissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)

dissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)discharge gap)discharge gap)

How do you optimize an ozone generatorg

Scientific ApproachScientific ApproachTheoretical Experimental

pppp

c [wt]

f [Hz]

c [wt]

f [Hz]

[kW]UUUβ1

1Cf4αPn

1iiminpeakimin

iiD

q [kWm2]q [kWm2]

150

180

][V]voltagepeakUpeak

[]cylinder perslicesofamountnsliceii

whereth

09 00

30

60

90

120

effic

ienc

y [

][0tdj t bl[F]sliceisdielectricofecapacitancC

[Hz]frequencyf[V]sliceivoltageminimumiUmin

thiD

th

10

28

46

64

82

39

107

176

244 power density

[kWm2]

ozone conc [wt][]CCβ

][0parameteradjustableα

iDiGi

Impact of Power Inductionp

350

400

wer

200

250

300

App

lied

Pow

Arr C 2Arr D +0

Arr E +45Arr F +7

Arr G +3

5 0

100

150

Frac

tion

of

1 2 3 4

ReferenceArr B unstable

Arr C -2

00

50

4Position (1inlet 4outlet)

Experimental Test Rigp g

Experimental Test Rigp g

Outer grounded electrode (left picture) and the dielectric covered inner electrodes (right) d e ect c cove ed e e ect odes ( g t)

Reference (Traditional) Arrangement

Inlet OutletGas flow direction

Optimized Arrangement

Inlet OutletGas flow direction

Intelligent Gap System (IGS)g p y ( )

Molecular Oxygen (O2) Ozone (O3)

O2 O3

yg ( 2) ( 3)

Particle Size SynthesisParticle Size SynthesisByBy--Products Cluster FormationProducts Cluster Formationyy

high diffusion and deposition to surfaces

low diffusion rate good transport

high sedimentation on the structurehigh sedimentation on the structure

Degreacutemont Technologies ndash OzoniaIntelligent Gap SystemIntelligent Gap System

G Vezzuacute JL Lopez A Freilich and K Becker Optimizationof Large-Scale Ozone Generators IEEE Transactions onPlasma Science Vol 37 No 6 p 890-896 (2009)

ConclusionsConclusionsConclusionsConclusionsFundamentals of ozone synthesis in a DBD plasmay p

ndash Highly filamented DBD discharges are best-suitedfor the production of ozone concentrations in therange of 6 to 14 wtrange of 6 to 14 wt

ndash The preferred characteristic of the microdischargesare Townsend-like at reduced electric fields Enaround 190 Townsend

ndash Detrimental side-effects induced by by-productscan be avoided by a proper design of the electrodecan be avoided by a proper design of the electrodearrangement The phenomenon is related to thediffusion rates of formed by-product clusters

ConclusionsConclusionsConclusionsConclusionsBenefits from DBD microplasma tailoring

ndash Reduced power consumption of up to 10 improvement

ndash Increased ozone concentrations of up to 14 now achievable

ndash Improved neutralization and conditioning of detrimental by-products

ndash Reduced system capital and operational cost

New technologies to improve ozone p

generatorg

HV Pulsed Power SwitchingHV Pulsed Power Switching

Microchannel Generation of Ozone

Channel ArrayChannel Array

Microchannel

330 microm 230 microm

Some Cap-DBD Devices Operating in Air

Increase of 60 of

Spacing 225 μmof 60 of plasma

No space

Cap‐DBD ozone generation

bull Ozone concentration is evaluated via Eco S d l UV 100 O A l (0 01Sensors model UV-100 Ozone Analyzer (001 ndash 900 ppm wiht an accuracy of plusmn2)

bull Three reactors 6 tubings 6rdquo with spacings of 0 μm 225 μm and 500 μm running at 3 kV μ μ μ g

SpacingOzone Concentration

3 kV rms 4 kV rms3 kV rms 4 kV rms

0 μm 660 ppm

225 μm 550 ppm

For a device of such small scale these ozone levels are promising

500 μm 380 ppm

J Mahoney W Zhu VS Johnson KH Becker and JL Lopez Electrical and optical emissionmeasurements of a capillary dielectric barrier discharge European Physics Journal D Vol 60 441-447(2010)

QuestionsQuestions

Thank YouFor more informationProf Jose L Lopez PhD

Thank YouFor more informationDepartment of Physics

Telephone (973) 761-9057Email joselopez1shuedu

Website wwwshueduacademicsartsciphysicsWebsite wwwshueduacademicsartsciphysics

Page 28: Dielectric Barrier Discharge (DBD) & Progress in Large ...bonitz/si12/talks/august_8/lopez_si12.pdf · Dielectric Barrier Discharge (DBD) & Progress in Large-Scale Ozone Generation

Microdischarge Activity and U-Q Lissajous Figure

B Eliasson and U Kogelschatz IEEE Transactions Plasma Science Vol 19 Issue 6 1063-1077 (1991)

Fundamental Operation of the Dielectric Barrier DischargeFundamental Operation of the Dielectric Barrier Discharge

bull Many of relevant plasma processes that areof importance to achieving our goal occuron time scales that allow us to study themon time scales that allow us to study them

bull Optical emission spectroscopic studies willallow us to determine the temporal andspatial development of important plasmaspatial development of important plasmaspecies such as radicals (OH NO variousoxygen radicals) with high time resolution(less than 10 ns) and a spatial resolution onthe scale of mm in the plasma volumepfollowing pulsed plasma excitation

Time scale of the relevant processes of the DBD

HE Wagner R Brandenburg et al lsquoThe barrier discharge basic properties and applications tosurface treatmentrsquo Vacuum 71 417-436 (2003)

Fundamental Operation of the DBDFundamental Operation of the DBD

Electron DensityTemporal Development (ns)

y

Outer Contour Linen = 1010 cm-3ne = 1010 cm 3

Inner Contour Linene = 1014 cm-3

Streamer Propagation in 1 bar AirAA Kulikovsky IEEE Trans Plasma Sci 25 439-446 (1997)

Numerical Results of Microdischarge Formationin Dielectric Barrier Discharges

Starting Phase of a Microdischarge (1 bar 20 CO2 80 H2)

E0=34 kVcm1010 cm-3

1010 cm-3 ne=1012 cm-3

1mm10 cm

ne=108 cm-3

An electron avalanche propagates towards the anode

Reverse propagationtowards the cathodepropagates towards the anode towards the cathode

Numerical Results of Microdischarge Formationin Dielectric Barrier Discharges

Cathode Layer Formation

E0=34 kVcm1010 cm-39 3 0

1mm

1010 cm-3

10 cmne=109 cm-31014

10131014

1013

10 cm1012

Just before the peak of the total current

Peak currentof the total current

Numerical Results of Microdischarge Formationin Dielectric Barrier Discharges

Local Field Collapse in Area Defined by Surface Discharge

ne=109cm-3 ne=1014 cm-3

Gap

Principals of DBD MicroplasmasPrincipals of DBD MicroplasmasPrincipals of DBD MicroplasmasPrincipals of DBD Microplasmas

C C-- - --- - - CG

CD

-- - - CG

CD

Principals of DBD MicroplasmasPrincipals of DBD MicroplasmasPrincipals of DBD MicroplasmasPrincipals of DBD Microplasmas

Dielectric Barrier Discharge (DBD)Dielectric Barrier Discharge (DBD)Electric Field

B kdBreakdown

Electrons amp Ions Discharge Physics

Excited SpeciesPlasma Chemistry

Chemical Reactions

OzoneGeneration

SurfaceTreatment

PollutionControl

ExcimerFormation CO2 Lasers Hydrogenation

of CO2

Excimer Lamps Plasma Displays

How A Plasma Display Works

How A Plasma Display Work

Plasma Display TelevisionsPlasma Display Televisions

Ozone Generator

3 O 2 O

Dielectric Barrier Discharge

3 O2 2 O3

OO22 OO33++OO22Ondash ndashO3O2

O2O2

Ondash ndash

endash O2Ondash ndash O2endash

O3

O3O2O2 O2

HeatHeatHeatHeat

Properties of Ozone (O3)

T i t i f f Tri-atomic form of oxygen

Most powerful commercial oxidizing agent

Unstable - must be generated and used onsite

Limited solubility in water but more so than oxygenLimited solubility in water but more so than oxygen

Leaves a dissolved residual which ultimately converts back to oxygenconverts back to oxygen

Discharge Tubes in Ozone GeneratorsDischarge Tubes in Ozone Generators

Traditional

Ozone Generator

with Glass Tubes

Generation of OzoneGeneration of Ozone

Generation of OzoneAdvantages of Enamel Dielectrics

Proven Patented Designbull Simplicity

Si l Di l i Cbull Single Dielectric Componentndash Reduced number of Dielectrics

bull Safety ndash Lower operating voltage

(lt 4000 V)bull Reliabilty

ndash Fused Dielectrics ensure continuous production

bull Lowest Power Consumption Operational Savingsndash Operational Savings

Modern Ozone GeneratorModern Ozone Generator

Ozonia Advanced Technology Ozone GeneratorOzone Generator

Generation of OzoneGeneration of Ozone

Generation of Ozone

Power Supply UnitPower Supply Unit

IGBT Inverter CircuitMain Circuit Breaker

HV 480 Volts60 Hz3 Phase Supply

C I

450KVAPow er to

GeneratorFILTER

CONVERTER INVERTERTRANSFORMER

C I450KVA Power Stage

CONTACTOR

bull Latest in Power Semiconductor Technology Modular Design

bull Utilizes IGBTrsquos (Insulated Gate Bi‐Polar Transistors) Converter and Inverter Components

Ozone Water Treatment

B bbl Diff iB bbl Diff iBubble DiffusionBubble Diffusion

Easy to use

Low energy usage Low energy usage

Mass transfer efficiencies to gt 90

Ozone Process Flow DiagramOzone Process Flow DiagramVent to

Atmosphere

O OOxygen

Off-Gas Blower

Ozone Destruct Unit

10 12

O3O2

LOX

10-12 O3

Ozone Generators

Ozone Contact ChamberLOX T k Generators Chamber

VaporizersLOX Tank

Municipal Ozone Installations

Ozonia Installations Ozone Plant Size [lbday] Start-Up DateKey Ozonia Installations (Partial List)

Los Angeles CA 10000 1986Fairfax VA ndash Corbalis 9000 2003MWD CA ndash Mills 9 000 2003

Ozonia Installations Ozone Plant Size [lbday] Start Up Date

MWD CA Mills 9000 2003Fairfax Co VA ndash Griffith 9000 2004MWD CA ndash Jensen 18750 2005Indianapolis IN ndash Belmont AWT 12000 2007I di li IN 12 000 2007Indianapolis IN ndash Southport AWT 12000 2007MWD CA ndash Diemer 13400 2008MWD CA ndash Weymouth 13400 2009

Ozonia North America - Potable Water SummaryTotal Number of Installations 90Total Installed Production gt 265000 lbsdayTotal Installed Production 265000 lbsday

Revision -B

Ozone Water TreatmentOzone Water Treatment

MWD Mills WTP - California

3 3 000 lbsda of o one3 3 000 lbsda of o one3 x 3000 lbsday of ozone3 x 3000 lbsday of ozone

Ozone Water TreatmentOzone Water TreatmentOzone Ozone -- How it worksHow it works

OxidantOxidant DisinfectantDisinfectant

bullbull Breaks double carbon Breaks double carbon bondsbonds

bullbull Kills by cell lysing or Kills by cell lysing or causing the cell wall tocausing the cell wall tobondsbonds

bullbull Creates OHCreates OHbullbull radicals radicals which break higher carbon which break higher carbon

causing the cell wall to causing the cell wall to rupture rupture

bullbull AttacksAttacks allall bacteriabacteriabondsbondsbullbull Increased temp and pH Increased temp and pH

accelerates Oaccelerates O33

Attacks Attacks allall bacteria bacteria virus cysts and spores virus cysts and spores in varying degreesin varying degreesaccelerates Oaccelerates O33

decomposition to OHdecomposition to OHbullbull

Micro-organism DNA

Capsule AdenineAdenine

Cell wall ThymineThymine

CytosineCytosine

GuanineGuanine

NuclearmaterialCellmembrane

material

Typical Bacterium DNA

Microbial Growth at Various Ozone ConcentrationsConcentrations

Growth likely

Growth possibleGrowth possible

NO GROWTH

0004 0008 0012 0016 0020

Ozone concentration (mgl)Ozone concentration (mgl)

Typical Water Treatment UsageTypical Water Treatment Usage

Application O3 mgl Contact timeUltra Pure Water 005 - 025 sec ndash min

Water bottling 04 ndash 10 5 ndash 10 min

Swimming pools ampspas

01 ndash 075 4 minutes

Potable taste amp odor 15 ndash 50 5 ndash 10 mindisinfection

Microfloculation 10 ndash 30 5 ndash 10 min

Lignin amp tammin 3 0 10 0 10 30 minLignin amp tamminremoval

30 ndash 100 10 ndash 30 min

Municipal wastewater 50 ndash 150+ 15 ndash 30 min

Ozone Water TreatmentOzone Water TreatmentOzone Ozone ndashndash Municipal ApplicationsMunicipal Applications

bullbull Taste and OdorTaste and Odor

bullbull Color RemovalColor Removal

bullbull Disinfection Without Trihalomethanes (THMs)Disinfection Without Trihalomethanes (THMs)

bullbull Improved Filtration Efficiency and FlocculationImproved Filtration Efficiency and Flocculation

bullbull Cryptosporidium DeactivationCryptosporidium Deactivation

bullbull Giardia amp Virus InactivationGiardia amp Virus Inactivation

bullbull Oxidation Oxidation -- Organics Fe amp MnOrganics Fe amp Mn

bullbull Wastewater disinfectionWastewater disinfection

bullbull BOD COD and TOC reductionBOD COD and TOC reduction

Applications of Ozone

Wastewater Treatmentbull Disinfection of Secondary and Tertiary Effluentsbull Color Reductionbull Color Reductionbull TOC Oxidation (Industrial)bull Oxidation of Odor Causing Compoundsbull Oxidation of Endocrine Disruptors (EDCrsquos) and p ( )

Pharmaceutically Active Compounds (PACrsquos)

Applications of Ozone

What are Endocrine Disruptors (EDCrsquos) and What are Endocrine Disruptors (EDCrsquos) and Ph ti ll A ti C d (PACrsquo )Ph ti ll A ti C d (PACrsquo )Pharmaceutically Active Compounds (PACrsquos)Pharmaceutically Active Compounds (PACrsquos)

bullbull EDCrsquosEDCrsquos andand PACrsquosPACrsquos areare NaturallyNaturally andand SyntheticSyntheticdd th tth t ff tff t thth b lb l llcompoundscompounds thatthat maymay affectaffect thethe balancebalance oror normalnormal

functionsfunctions inin animalsanimals andand humanshumans

What can EDCrsquos and PACrsquos doWhat can EDCrsquos and PACrsquos do

bullbull Even in very small concentrations these compounds Even in very small concentrations these compounds y py pcan can disruptdisrupt normal bodily functionsnormal bodily functions

bullbull ManMan--made chemicals can trick the bodies endocrine made chemicals can trick the bodies endocrine system system

Applications of Ozone

Examples of Endocrine Disruptors1000rsquos of compounds that may be Investigated as EDCs ndash Some examples are

bullbull Synthetic HormonesSynthetic Hormonesbullbull Naturally Occurring Estrogens Naturally Occurring Estrogens

Health and Beauty AidsHealth and Beauty Aidsbullbull Health and Beauty AidsHealth and Beauty Aidsbullbull SolventsSolventsbullbull PesticidesPesticidesbullbull SurfactantsSurfactantsbullbull PlasticsPlastics

F i idF i idbullbull FungicidesFungicides

Ozone Water TreatmentOzone Water Treatment

Ozone Ozone -- Industrial ApplicationsIndustrial Applications-- Ultrapure Water for Pharmaceutical ApplicationsUltrapure Water for Pharmaceutical Applications

-- Wastewater disinfection color removalWastewater disinfection color removal

-- Soil and Groundwater Remediation Soil and Groundwater Remediation

-- Cooling Tower Water TreatmentCooling Tower Water Treatment

-- Food ProcessingFood Processing

-- Aquaculture AquariumsAquaculture AquariumsAquaculture AquariumsAquaculture Aquariums

-- Beverage ApplicationsBeverage Applications

P l amp P Bl hiP l amp P Bl hi-- Pulp amp Paper BleachingPulp amp Paper Bleaching

High Purity OzonationHigh Purity Ozonation

Microchip manufacturingMicrochip manufacturing

What are the current issues in large-scale gozone generationg

Experimental Setup

Front view of the two units after the redesign and reworking ofthe gas water and instruments connectionsthe gas water and instruments connections

Experimental Setup

Top view of the twoexperimental unitsexperimental unitsSpectroscope (notshown) is to the left ofthe DBD The units weredifferent with respect todifferent with respect totheir electrodes onehad only the electrodecoated with thedielectric (ldquosingle-dielectric ( single-coatedrdquo) the other onehad the electrode andthe anode coated withthe dielectric (ldquodouble-the dielectric ( double-coatedrdquo)

Basics Generation of OzoneBasics Generation of Ozone

SpectroscopyPlasma

Plasma Absorption SpectroscopyPlasma Absorption Spectroscopy

Infrared Absorption SpectroscopyInfrared Absorption Spectroscopy

IR spectra in pure oxygen (black curve) and at approximately 10wt N2 admixture (red line) N2O5 peaks appear at124 1 d 1 2 11245 cm-1 and at 1725 cm-1

Infrared Absorption SpectroscopyInfrared Absorption Spectroscopy

IR spectra of several methane variations The green curve envelopes all of the methane peaks at 1325 cm-1recorded at smaller methane admixtures Simultaneously the N2O5 peaks disappear as the methane peaks appear

N2O5 FormationN2O5 Formation2 52 5p=2 bara cwt=20degC q=35kWm2 f=1450Hz

45N2O5 AT95

30

35

40

N

2 B

lend

ing

N2O AT95N2O5 IGSN2O IGSN2O5 LGN2O LG

1 5

20

25

nt [p

pmV]

3

wt

05

10

15

NO

x co

nten

005 7 9 11 13 15 17

ozone conc [wt]

Amount of formed N2O5 and N2O as a function of ozone concentration at 3 wt of nitrogen admixture and fori l dvarious electrode arrangements

Plasma Emission SpectroscopyPlasma Emission Spectroscopyp pyp py

Relative Emissions of the Ozonizer plasmaRelative Emissions of the Ozonizer plasma

Region 300- 850 nm from individual (calibrated) regions (smoothed by PeakFit) Single-coated ozone generator Inlet side

3 5E+06

30E+06

35E+06

7 9

20E+06

25E+06

nten

sity

au

2

311 12

10E+06

15E+06

In 4

5

6 8 10

14

15

16

17

00E+00

50E+05

280 300 320 340 360 380 400 420 440 460 480 500 520 540 560 580 600 620 640 660 680 700 720 740 760 780 800 820 840 860

Wavelength nm

1 13

Wavelength nm

Absolute Emission of the DBD PlasmaAbsolute Emission of the DBD Plasma

Intensities in (O2+3 wtN2) plasma

1 20E+04

100E+04

120E+04

600E+03

800E+03

nten

sity

(au

)

200E+03

400E+03

In

O(777)

000E+00200 250 300 350 400 450 500 550 600 650 700 750 800 850

Wavelength nm

Intensities in 3 wtN2+O2 plasmaIntensities in 3 wtN2+O2 plasma

Plasma Chemistry in OzonizersPlasma Chemistry in Ozonizers

Dry Air O2 N2

e - e -

O N2 N O2

O3 NO

O2 N O2

O3

N

3

NO2

O2 O3

NO

N

NO2 O3

N2O

NO3 N

N2O4

NO2

NO2

N2O5

NO3

Primary electron-driven chemical reactions leading to the formation of N2O5 and N2O in a dry air plasma

Plasma emission diagnostics role of N2Plasma emission diagnostics role of N2

Dry Air O2 N2

e - e -

O N2 N O2

O3 NO

O2 N O2

O3

O

N

ON

NO2

O2O3

N

NO N

NO2 O3

N2O

NO3 N

N2O4

NO2

NO2

N2O5

NO3

ONbullWith N2 present ndash less oxygen atoms are formed However the difference in intensity is

very small

Modeling of plasma chemistry incl the NxOy chemistry up to N2O5 for different Oxygen Nitrogen mixtures varying power deposition scenarios

and initial ozone background concentrations (up to 15) previously done

The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation

The role of N2 must be related to its by-products reacting on the surface of the electrodeThe role of N2 must be related to its by-products reacting on the surface of the electrode

The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established

Ab 8 t f O

The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established

Ab 8 t f OAbove 8 wt of O3

1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)

Above 8 wt of O3

1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)case without pampp)

2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of the

case without pampp)

2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of thethem A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface

them A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface

The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation

Three possibilities have to be considered for the oxygen-fedozone generator

Three possibilities have to be considered for the oxygen-fedozone generatorozone generator

bull Excited N2 molecules lead to an increased O2 dissociation in

ozone generator

bull Excited N2 molecules lead to an increased O2 dissociation in2 2such case an increased efficiency is correlated to the N2admixture

2 2such case an increased efficiency is correlated to the N2admixture

bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial

bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial

bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2

bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2g p g 3 pp y 2g p g 3 pp y 2

Effect of methane on ozone efficiency and specific powerEffect of methane on ozone efficiency and specific power

Effect of Methane on Ozone Content in Outlet Gas and on Specific Power Pure O2

13 12

10

11

12

t 8

10

8

9

10

ne c

onte

nt w

t

6

8

ecifi

c po

wer

kW

hlb

5

6

7

Ozo

n

2

4 Spe

400E+00 20E+03 40E+03 60E+03 80E+03 10E+04 12E+04

Methane in feedgas ppm

0

Ozone content in the outlet gas Specif ic pow er of the ozone generatorg p p g

Effects of N2 and CH4Effects of N2 and CH4

Pi t f h t lli N O t tPicture of an amorphous-crystalline N2O5 structurecaptured at the Orlando Skylake water plant in 2006

Plasma Chemistry with CH4 Impurities

OxygenO2 N2

e - e -

CHO N2

NO2

O NO

O2 N O2 O3

NOH

CH4e-

O3 NO

NO2

O2O3NO N

NO2 O

NO2

NO2

N2ONO3

N

O3

NO2

NO

HNO3

N2O4

N2O5

NO2

NO3

N2O5

Effect of methane on the electrode surfaces

a) b)

Inlet Outlet Outlet

) d)

I l t I l t

c) d)

Electrode of the ozone generator afterseveral hours in CH8O2 and up to 2 wt of methane (a b c)

Inlet Inlet

three hours in CH8O2+traces of N2 and up to 1 wt of methane (d) Visible change of discharge character at about 13 length of electrode (a d)

Kinetics of CHx Conversion without N2

conversion by collisions

O2 + CHx 12wt O3 + CO2 +H2O

deposition vaporizationby sputtering

ibl b l 1000 CHreversible process below 1000ppm CH4

Effect of water on electrode surface with N2

Inlet

OutletOutlet

Electrode of the ozone generator after several hours in H OO N

Inlet

Electrode of the ozone generator after several hours in H2OO2N2

Effect of water on electrode surface

Long term effect (800 hrs) of H2OO2N2

Kinetics of CHx Conversion with N2

conversion by collisionsHNO3 formation

O2 + N2 +CHx 12wtO2 + CO2 +H2O + HNO3

deposition vaporizationby sputtering

H2O + HNO3

by sputtering

irreversible process above a N2 threshold () ltlt 1000ppm N2

sticky deposit

p 2 ( ) pp 2 any CH4 concentration (60ppm)

Plasma Chemistry with CH4 ImpuritiesPlasma Chemistry with CH4 Impurities4

bull Formation of NO and NO2 depends on O3 N2 and gas temperature Conclusion N2 admixture is the key factor

SummarySummaryyyThe mechanisms of formed NOx by-products follows the sameThe mechanisms of formed NOx by-products follows the sameprinciples as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentration

principles as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentrationozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)

ozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)g p ( g p )

The conversion of methane to OH and H2O is found to depend on

g p ( g p )

The conversion of methane to OH and H2O is found to depend ondissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)

dissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)discharge gap)discharge gap)

How do you optimize an ozone generatorg

Scientific ApproachScientific ApproachTheoretical Experimental

pppp

c [wt]

f [Hz]

c [wt]

f [Hz]

[kW]UUUβ1

1Cf4αPn

1iiminpeakimin

iiD

q [kWm2]q [kWm2]

150

180

][V]voltagepeakUpeak

[]cylinder perslicesofamountnsliceii

whereth

09 00

30

60

90

120

effic

ienc

y [

][0tdj t bl[F]sliceisdielectricofecapacitancC

[Hz]frequencyf[V]sliceivoltageminimumiUmin

thiD

th

10

28

46

64

82

39

107

176

244 power density

[kWm2]

ozone conc [wt][]CCβ

][0parameteradjustableα

iDiGi

Impact of Power Inductionp

350

400

wer

200

250

300

App

lied

Pow

Arr C 2Arr D +0

Arr E +45Arr F +7

Arr G +3

5 0

100

150

Frac

tion

of

1 2 3 4

ReferenceArr B unstable

Arr C -2

00

50

4Position (1inlet 4outlet)

Experimental Test Rigp g

Experimental Test Rigp g

Outer grounded electrode (left picture) and the dielectric covered inner electrodes (right) d e ect c cove ed e e ect odes ( g t)

Reference (Traditional) Arrangement

Inlet OutletGas flow direction

Optimized Arrangement

Inlet OutletGas flow direction

Intelligent Gap System (IGS)g p y ( )

Molecular Oxygen (O2) Ozone (O3)

O2 O3

yg ( 2) ( 3)

Particle Size SynthesisParticle Size SynthesisByBy--Products Cluster FormationProducts Cluster Formationyy

high diffusion and deposition to surfaces

low diffusion rate good transport

high sedimentation on the structurehigh sedimentation on the structure

Degreacutemont Technologies ndash OzoniaIntelligent Gap SystemIntelligent Gap System

G Vezzuacute JL Lopez A Freilich and K Becker Optimizationof Large-Scale Ozone Generators IEEE Transactions onPlasma Science Vol 37 No 6 p 890-896 (2009)

ConclusionsConclusionsConclusionsConclusionsFundamentals of ozone synthesis in a DBD plasmay p

ndash Highly filamented DBD discharges are best-suitedfor the production of ozone concentrations in therange of 6 to 14 wtrange of 6 to 14 wt

ndash The preferred characteristic of the microdischargesare Townsend-like at reduced electric fields Enaround 190 Townsend

ndash Detrimental side-effects induced by by-productscan be avoided by a proper design of the electrodecan be avoided by a proper design of the electrodearrangement The phenomenon is related to thediffusion rates of formed by-product clusters

ConclusionsConclusionsConclusionsConclusionsBenefits from DBD microplasma tailoring

ndash Reduced power consumption of up to 10 improvement

ndash Increased ozone concentrations of up to 14 now achievable

ndash Improved neutralization and conditioning of detrimental by-products

ndash Reduced system capital and operational cost

New technologies to improve ozone p

generatorg

HV Pulsed Power SwitchingHV Pulsed Power Switching

Microchannel Generation of Ozone

Channel ArrayChannel Array

Microchannel

330 microm 230 microm

Some Cap-DBD Devices Operating in Air

Increase of 60 of

Spacing 225 μmof 60 of plasma

No space

Cap‐DBD ozone generation

bull Ozone concentration is evaluated via Eco S d l UV 100 O A l (0 01Sensors model UV-100 Ozone Analyzer (001 ndash 900 ppm wiht an accuracy of plusmn2)

bull Three reactors 6 tubings 6rdquo with spacings of 0 μm 225 μm and 500 μm running at 3 kV μ μ μ g

SpacingOzone Concentration

3 kV rms 4 kV rms3 kV rms 4 kV rms

0 μm 660 ppm

225 μm 550 ppm

For a device of such small scale these ozone levels are promising

500 μm 380 ppm

J Mahoney W Zhu VS Johnson KH Becker and JL Lopez Electrical and optical emissionmeasurements of a capillary dielectric barrier discharge European Physics Journal D Vol 60 441-447(2010)

QuestionsQuestions

Thank YouFor more informationProf Jose L Lopez PhD

Thank YouFor more informationDepartment of Physics

Telephone (973) 761-9057Email joselopez1shuedu

Website wwwshueduacademicsartsciphysicsWebsite wwwshueduacademicsartsciphysics

Page 29: Dielectric Barrier Discharge (DBD) & Progress in Large ...bonitz/si12/talks/august_8/lopez_si12.pdf · Dielectric Barrier Discharge (DBD) & Progress in Large-Scale Ozone Generation

Fundamental Operation of the Dielectric Barrier DischargeFundamental Operation of the Dielectric Barrier Discharge

bull Many of relevant plasma processes that areof importance to achieving our goal occuron time scales that allow us to study themon time scales that allow us to study them

bull Optical emission spectroscopic studies willallow us to determine the temporal andspatial development of important plasmaspatial development of important plasmaspecies such as radicals (OH NO variousoxygen radicals) with high time resolution(less than 10 ns) and a spatial resolution onthe scale of mm in the plasma volumepfollowing pulsed plasma excitation

Time scale of the relevant processes of the DBD

HE Wagner R Brandenburg et al lsquoThe barrier discharge basic properties and applications tosurface treatmentrsquo Vacuum 71 417-436 (2003)

Fundamental Operation of the DBDFundamental Operation of the DBD

Electron DensityTemporal Development (ns)

y

Outer Contour Linen = 1010 cm-3ne = 1010 cm 3

Inner Contour Linene = 1014 cm-3

Streamer Propagation in 1 bar AirAA Kulikovsky IEEE Trans Plasma Sci 25 439-446 (1997)

Numerical Results of Microdischarge Formationin Dielectric Barrier Discharges

Starting Phase of a Microdischarge (1 bar 20 CO2 80 H2)

E0=34 kVcm1010 cm-3

1010 cm-3 ne=1012 cm-3

1mm10 cm

ne=108 cm-3

An electron avalanche propagates towards the anode

Reverse propagationtowards the cathodepropagates towards the anode towards the cathode

Numerical Results of Microdischarge Formationin Dielectric Barrier Discharges

Cathode Layer Formation

E0=34 kVcm1010 cm-39 3 0

1mm

1010 cm-3

10 cmne=109 cm-31014

10131014

1013

10 cm1012

Just before the peak of the total current

Peak currentof the total current

Numerical Results of Microdischarge Formationin Dielectric Barrier Discharges

Local Field Collapse in Area Defined by Surface Discharge

ne=109cm-3 ne=1014 cm-3

Gap

Principals of DBD MicroplasmasPrincipals of DBD MicroplasmasPrincipals of DBD MicroplasmasPrincipals of DBD Microplasmas

C C-- - --- - - CG

CD

-- - - CG

CD

Principals of DBD MicroplasmasPrincipals of DBD MicroplasmasPrincipals of DBD MicroplasmasPrincipals of DBD Microplasmas

Dielectric Barrier Discharge (DBD)Dielectric Barrier Discharge (DBD)Electric Field

B kdBreakdown

Electrons amp Ions Discharge Physics

Excited SpeciesPlasma Chemistry

Chemical Reactions

OzoneGeneration

SurfaceTreatment

PollutionControl

ExcimerFormation CO2 Lasers Hydrogenation

of CO2

Excimer Lamps Plasma Displays

How A Plasma Display Works

How A Plasma Display Work

Plasma Display TelevisionsPlasma Display Televisions

Ozone Generator

3 O 2 O

Dielectric Barrier Discharge

3 O2 2 O3

OO22 OO33++OO22Ondash ndashO3O2

O2O2

Ondash ndash

endash O2Ondash ndash O2endash

O3

O3O2O2 O2

HeatHeatHeatHeat

Properties of Ozone (O3)

T i t i f f Tri-atomic form of oxygen

Most powerful commercial oxidizing agent

Unstable - must be generated and used onsite

Limited solubility in water but more so than oxygenLimited solubility in water but more so than oxygen

Leaves a dissolved residual which ultimately converts back to oxygenconverts back to oxygen

Discharge Tubes in Ozone GeneratorsDischarge Tubes in Ozone Generators

Traditional

Ozone Generator

with Glass Tubes

Generation of OzoneGeneration of Ozone

Generation of OzoneAdvantages of Enamel Dielectrics

Proven Patented Designbull Simplicity

Si l Di l i Cbull Single Dielectric Componentndash Reduced number of Dielectrics

bull Safety ndash Lower operating voltage

(lt 4000 V)bull Reliabilty

ndash Fused Dielectrics ensure continuous production

bull Lowest Power Consumption Operational Savingsndash Operational Savings

Modern Ozone GeneratorModern Ozone Generator

Ozonia Advanced Technology Ozone GeneratorOzone Generator

Generation of OzoneGeneration of Ozone

Generation of Ozone

Power Supply UnitPower Supply Unit

IGBT Inverter CircuitMain Circuit Breaker

HV 480 Volts60 Hz3 Phase Supply

C I

450KVAPow er to

GeneratorFILTER

CONVERTER INVERTERTRANSFORMER

C I450KVA Power Stage

CONTACTOR

bull Latest in Power Semiconductor Technology Modular Design

bull Utilizes IGBTrsquos (Insulated Gate Bi‐Polar Transistors) Converter and Inverter Components

Ozone Water Treatment

B bbl Diff iB bbl Diff iBubble DiffusionBubble Diffusion

Easy to use

Low energy usage Low energy usage

Mass transfer efficiencies to gt 90

Ozone Process Flow DiagramOzone Process Flow DiagramVent to

Atmosphere

O OOxygen

Off-Gas Blower

Ozone Destruct Unit

10 12

O3O2

LOX

10-12 O3

Ozone Generators

Ozone Contact ChamberLOX T k Generators Chamber

VaporizersLOX Tank

Municipal Ozone Installations

Ozonia Installations Ozone Plant Size [lbday] Start-Up DateKey Ozonia Installations (Partial List)

Los Angeles CA 10000 1986Fairfax VA ndash Corbalis 9000 2003MWD CA ndash Mills 9 000 2003

Ozonia Installations Ozone Plant Size [lbday] Start Up Date

MWD CA Mills 9000 2003Fairfax Co VA ndash Griffith 9000 2004MWD CA ndash Jensen 18750 2005Indianapolis IN ndash Belmont AWT 12000 2007I di li IN 12 000 2007Indianapolis IN ndash Southport AWT 12000 2007MWD CA ndash Diemer 13400 2008MWD CA ndash Weymouth 13400 2009

Ozonia North America - Potable Water SummaryTotal Number of Installations 90Total Installed Production gt 265000 lbsdayTotal Installed Production 265000 lbsday

Revision -B

Ozone Water TreatmentOzone Water Treatment

MWD Mills WTP - California

3 3 000 lbsda of o one3 3 000 lbsda of o one3 x 3000 lbsday of ozone3 x 3000 lbsday of ozone

Ozone Water TreatmentOzone Water TreatmentOzone Ozone -- How it worksHow it works

OxidantOxidant DisinfectantDisinfectant

bullbull Breaks double carbon Breaks double carbon bondsbonds

bullbull Kills by cell lysing or Kills by cell lysing or causing the cell wall tocausing the cell wall tobondsbonds

bullbull Creates OHCreates OHbullbull radicals radicals which break higher carbon which break higher carbon

causing the cell wall to causing the cell wall to rupture rupture

bullbull AttacksAttacks allall bacteriabacteriabondsbondsbullbull Increased temp and pH Increased temp and pH

accelerates Oaccelerates O33

Attacks Attacks allall bacteria bacteria virus cysts and spores virus cysts and spores in varying degreesin varying degreesaccelerates Oaccelerates O33

decomposition to OHdecomposition to OHbullbull

Micro-organism DNA

Capsule AdenineAdenine

Cell wall ThymineThymine

CytosineCytosine

GuanineGuanine

NuclearmaterialCellmembrane

material

Typical Bacterium DNA

Microbial Growth at Various Ozone ConcentrationsConcentrations

Growth likely

Growth possibleGrowth possible

NO GROWTH

0004 0008 0012 0016 0020

Ozone concentration (mgl)Ozone concentration (mgl)

Typical Water Treatment UsageTypical Water Treatment Usage

Application O3 mgl Contact timeUltra Pure Water 005 - 025 sec ndash min

Water bottling 04 ndash 10 5 ndash 10 min

Swimming pools ampspas

01 ndash 075 4 minutes

Potable taste amp odor 15 ndash 50 5 ndash 10 mindisinfection

Microfloculation 10 ndash 30 5 ndash 10 min

Lignin amp tammin 3 0 10 0 10 30 minLignin amp tamminremoval

30 ndash 100 10 ndash 30 min

Municipal wastewater 50 ndash 150+ 15 ndash 30 min

Ozone Water TreatmentOzone Water TreatmentOzone Ozone ndashndash Municipal ApplicationsMunicipal Applications

bullbull Taste and OdorTaste and Odor

bullbull Color RemovalColor Removal

bullbull Disinfection Without Trihalomethanes (THMs)Disinfection Without Trihalomethanes (THMs)

bullbull Improved Filtration Efficiency and FlocculationImproved Filtration Efficiency and Flocculation

bullbull Cryptosporidium DeactivationCryptosporidium Deactivation

bullbull Giardia amp Virus InactivationGiardia amp Virus Inactivation

bullbull Oxidation Oxidation -- Organics Fe amp MnOrganics Fe amp Mn

bullbull Wastewater disinfectionWastewater disinfection

bullbull BOD COD and TOC reductionBOD COD and TOC reduction

Applications of Ozone

Wastewater Treatmentbull Disinfection of Secondary and Tertiary Effluentsbull Color Reductionbull Color Reductionbull TOC Oxidation (Industrial)bull Oxidation of Odor Causing Compoundsbull Oxidation of Endocrine Disruptors (EDCrsquos) and p ( )

Pharmaceutically Active Compounds (PACrsquos)

Applications of Ozone

What are Endocrine Disruptors (EDCrsquos) and What are Endocrine Disruptors (EDCrsquos) and Ph ti ll A ti C d (PACrsquo )Ph ti ll A ti C d (PACrsquo )Pharmaceutically Active Compounds (PACrsquos)Pharmaceutically Active Compounds (PACrsquos)

bullbull EDCrsquosEDCrsquos andand PACrsquosPACrsquos areare NaturallyNaturally andand SyntheticSyntheticdd th tth t ff tff t thth b lb l llcompoundscompounds thatthat maymay affectaffect thethe balancebalance oror normalnormal

functionsfunctions inin animalsanimals andand humanshumans

What can EDCrsquos and PACrsquos doWhat can EDCrsquos and PACrsquos do

bullbull Even in very small concentrations these compounds Even in very small concentrations these compounds y py pcan can disruptdisrupt normal bodily functionsnormal bodily functions

bullbull ManMan--made chemicals can trick the bodies endocrine made chemicals can trick the bodies endocrine system system

Applications of Ozone

Examples of Endocrine Disruptors1000rsquos of compounds that may be Investigated as EDCs ndash Some examples are

bullbull Synthetic HormonesSynthetic Hormonesbullbull Naturally Occurring Estrogens Naturally Occurring Estrogens

Health and Beauty AidsHealth and Beauty Aidsbullbull Health and Beauty AidsHealth and Beauty Aidsbullbull SolventsSolventsbullbull PesticidesPesticidesbullbull SurfactantsSurfactantsbullbull PlasticsPlastics

F i idF i idbullbull FungicidesFungicides

Ozone Water TreatmentOzone Water Treatment

Ozone Ozone -- Industrial ApplicationsIndustrial Applications-- Ultrapure Water for Pharmaceutical ApplicationsUltrapure Water for Pharmaceutical Applications

-- Wastewater disinfection color removalWastewater disinfection color removal

-- Soil and Groundwater Remediation Soil and Groundwater Remediation

-- Cooling Tower Water TreatmentCooling Tower Water Treatment

-- Food ProcessingFood Processing

-- Aquaculture AquariumsAquaculture AquariumsAquaculture AquariumsAquaculture Aquariums

-- Beverage ApplicationsBeverage Applications

P l amp P Bl hiP l amp P Bl hi-- Pulp amp Paper BleachingPulp amp Paper Bleaching

High Purity OzonationHigh Purity Ozonation

Microchip manufacturingMicrochip manufacturing

What are the current issues in large-scale gozone generationg

Experimental Setup

Front view of the two units after the redesign and reworking ofthe gas water and instruments connectionsthe gas water and instruments connections

Experimental Setup

Top view of the twoexperimental unitsexperimental unitsSpectroscope (notshown) is to the left ofthe DBD The units weredifferent with respect todifferent with respect totheir electrodes onehad only the electrodecoated with thedielectric (ldquosingle-dielectric ( single-coatedrdquo) the other onehad the electrode andthe anode coated withthe dielectric (ldquodouble-the dielectric ( double-coatedrdquo)

Basics Generation of OzoneBasics Generation of Ozone

SpectroscopyPlasma

Plasma Absorption SpectroscopyPlasma Absorption Spectroscopy

Infrared Absorption SpectroscopyInfrared Absorption Spectroscopy

IR spectra in pure oxygen (black curve) and at approximately 10wt N2 admixture (red line) N2O5 peaks appear at124 1 d 1 2 11245 cm-1 and at 1725 cm-1

Infrared Absorption SpectroscopyInfrared Absorption Spectroscopy

IR spectra of several methane variations The green curve envelopes all of the methane peaks at 1325 cm-1recorded at smaller methane admixtures Simultaneously the N2O5 peaks disappear as the methane peaks appear

N2O5 FormationN2O5 Formation2 52 5p=2 bara cwt=20degC q=35kWm2 f=1450Hz

45N2O5 AT95

30

35

40

N

2 B

lend

ing

N2O AT95N2O5 IGSN2O IGSN2O5 LGN2O LG

1 5

20

25

nt [p

pmV]

3

wt

05

10

15

NO

x co

nten

005 7 9 11 13 15 17

ozone conc [wt]

Amount of formed N2O5 and N2O as a function of ozone concentration at 3 wt of nitrogen admixture and fori l dvarious electrode arrangements

Plasma Emission SpectroscopyPlasma Emission Spectroscopyp pyp py

Relative Emissions of the Ozonizer plasmaRelative Emissions of the Ozonizer plasma

Region 300- 850 nm from individual (calibrated) regions (smoothed by PeakFit) Single-coated ozone generator Inlet side

3 5E+06

30E+06

35E+06

7 9

20E+06

25E+06

nten

sity

au

2

311 12

10E+06

15E+06

In 4

5

6 8 10

14

15

16

17

00E+00

50E+05

280 300 320 340 360 380 400 420 440 460 480 500 520 540 560 580 600 620 640 660 680 700 720 740 760 780 800 820 840 860

Wavelength nm

1 13

Wavelength nm

Absolute Emission of the DBD PlasmaAbsolute Emission of the DBD Plasma

Intensities in (O2+3 wtN2) plasma

1 20E+04

100E+04

120E+04

600E+03

800E+03

nten

sity

(au

)

200E+03

400E+03

In

O(777)

000E+00200 250 300 350 400 450 500 550 600 650 700 750 800 850

Wavelength nm

Intensities in 3 wtN2+O2 plasmaIntensities in 3 wtN2+O2 plasma

Plasma Chemistry in OzonizersPlasma Chemistry in Ozonizers

Dry Air O2 N2

e - e -

O N2 N O2

O3 NO

O2 N O2

O3

N

3

NO2

O2 O3

NO

N

NO2 O3

N2O

NO3 N

N2O4

NO2

NO2

N2O5

NO3

Primary electron-driven chemical reactions leading to the formation of N2O5 and N2O in a dry air plasma

Plasma emission diagnostics role of N2Plasma emission diagnostics role of N2

Dry Air O2 N2

e - e -

O N2 N O2

O3 NO

O2 N O2

O3

O

N

ON

NO2

O2O3

N

NO N

NO2 O3

N2O

NO3 N

N2O4

NO2

NO2

N2O5

NO3

ONbullWith N2 present ndash less oxygen atoms are formed However the difference in intensity is

very small

Modeling of plasma chemistry incl the NxOy chemistry up to N2O5 for different Oxygen Nitrogen mixtures varying power deposition scenarios

and initial ozone background concentrations (up to 15) previously done

The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation

The role of N2 must be related to its by-products reacting on the surface of the electrodeThe role of N2 must be related to its by-products reacting on the surface of the electrode

The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established

Ab 8 t f O

The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established

Ab 8 t f OAbove 8 wt of O3

1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)

Above 8 wt of O3

1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)case without pampp)

2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of the

case without pampp)

2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of thethem A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface

them A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface

The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation

Three possibilities have to be considered for the oxygen-fedozone generator

Three possibilities have to be considered for the oxygen-fedozone generatorozone generator

bull Excited N2 molecules lead to an increased O2 dissociation in

ozone generator

bull Excited N2 molecules lead to an increased O2 dissociation in2 2such case an increased efficiency is correlated to the N2admixture

2 2such case an increased efficiency is correlated to the N2admixture

bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial

bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial

bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2

bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2g p g 3 pp y 2g p g 3 pp y 2

Effect of methane on ozone efficiency and specific powerEffect of methane on ozone efficiency and specific power

Effect of Methane on Ozone Content in Outlet Gas and on Specific Power Pure O2

13 12

10

11

12

t 8

10

8

9

10

ne c

onte

nt w

t

6

8

ecifi

c po

wer

kW

hlb

5

6

7

Ozo

n

2

4 Spe

400E+00 20E+03 40E+03 60E+03 80E+03 10E+04 12E+04

Methane in feedgas ppm

0

Ozone content in the outlet gas Specif ic pow er of the ozone generatorg p p g

Effects of N2 and CH4Effects of N2 and CH4

Pi t f h t lli N O t tPicture of an amorphous-crystalline N2O5 structurecaptured at the Orlando Skylake water plant in 2006

Plasma Chemistry with CH4 Impurities

OxygenO2 N2

e - e -

CHO N2

NO2

O NO

O2 N O2 O3

NOH

CH4e-

O3 NO

NO2

O2O3NO N

NO2 O

NO2

NO2

N2ONO3

N

O3

NO2

NO

HNO3

N2O4

N2O5

NO2

NO3

N2O5

Effect of methane on the electrode surfaces

a) b)

Inlet Outlet Outlet

) d)

I l t I l t

c) d)

Electrode of the ozone generator afterseveral hours in CH8O2 and up to 2 wt of methane (a b c)

Inlet Inlet

three hours in CH8O2+traces of N2 and up to 1 wt of methane (d) Visible change of discharge character at about 13 length of electrode (a d)

Kinetics of CHx Conversion without N2

conversion by collisions

O2 + CHx 12wt O3 + CO2 +H2O

deposition vaporizationby sputtering

ibl b l 1000 CHreversible process below 1000ppm CH4

Effect of water on electrode surface with N2

Inlet

OutletOutlet

Electrode of the ozone generator after several hours in H OO N

Inlet

Electrode of the ozone generator after several hours in H2OO2N2

Effect of water on electrode surface

Long term effect (800 hrs) of H2OO2N2

Kinetics of CHx Conversion with N2

conversion by collisionsHNO3 formation

O2 + N2 +CHx 12wtO2 + CO2 +H2O + HNO3

deposition vaporizationby sputtering

H2O + HNO3

by sputtering

irreversible process above a N2 threshold () ltlt 1000ppm N2

sticky deposit

p 2 ( ) pp 2 any CH4 concentration (60ppm)

Plasma Chemistry with CH4 ImpuritiesPlasma Chemistry with CH4 Impurities4

bull Formation of NO and NO2 depends on O3 N2 and gas temperature Conclusion N2 admixture is the key factor

SummarySummaryyyThe mechanisms of formed NOx by-products follows the sameThe mechanisms of formed NOx by-products follows the sameprinciples as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentration

principles as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentrationozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)

ozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)g p ( g p )

The conversion of methane to OH and H2O is found to depend on

g p ( g p )

The conversion of methane to OH and H2O is found to depend ondissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)

dissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)discharge gap)discharge gap)

How do you optimize an ozone generatorg

Scientific ApproachScientific ApproachTheoretical Experimental

pppp

c [wt]

f [Hz]

c [wt]

f [Hz]

[kW]UUUβ1

1Cf4αPn

1iiminpeakimin

iiD

q [kWm2]q [kWm2]

150

180

][V]voltagepeakUpeak

[]cylinder perslicesofamountnsliceii

whereth

09 00

30

60

90

120

effic

ienc

y [

][0tdj t bl[F]sliceisdielectricofecapacitancC

[Hz]frequencyf[V]sliceivoltageminimumiUmin

thiD

th

10

28

46

64

82

39

107

176

244 power density

[kWm2]

ozone conc [wt][]CCβ

][0parameteradjustableα

iDiGi

Impact of Power Inductionp

350

400

wer

200

250

300

App

lied

Pow

Arr C 2Arr D +0

Arr E +45Arr F +7

Arr G +3

5 0

100

150

Frac

tion

of

1 2 3 4

ReferenceArr B unstable

Arr C -2

00

50

4Position (1inlet 4outlet)

Experimental Test Rigp g

Experimental Test Rigp g

Outer grounded electrode (left picture) and the dielectric covered inner electrodes (right) d e ect c cove ed e e ect odes ( g t)

Reference (Traditional) Arrangement

Inlet OutletGas flow direction

Optimized Arrangement

Inlet OutletGas flow direction

Intelligent Gap System (IGS)g p y ( )

Molecular Oxygen (O2) Ozone (O3)

O2 O3

yg ( 2) ( 3)

Particle Size SynthesisParticle Size SynthesisByBy--Products Cluster FormationProducts Cluster Formationyy

high diffusion and deposition to surfaces

low diffusion rate good transport

high sedimentation on the structurehigh sedimentation on the structure

Degreacutemont Technologies ndash OzoniaIntelligent Gap SystemIntelligent Gap System

G Vezzuacute JL Lopez A Freilich and K Becker Optimizationof Large-Scale Ozone Generators IEEE Transactions onPlasma Science Vol 37 No 6 p 890-896 (2009)

ConclusionsConclusionsConclusionsConclusionsFundamentals of ozone synthesis in a DBD plasmay p

ndash Highly filamented DBD discharges are best-suitedfor the production of ozone concentrations in therange of 6 to 14 wtrange of 6 to 14 wt

ndash The preferred characteristic of the microdischargesare Townsend-like at reduced electric fields Enaround 190 Townsend

ndash Detrimental side-effects induced by by-productscan be avoided by a proper design of the electrodecan be avoided by a proper design of the electrodearrangement The phenomenon is related to thediffusion rates of formed by-product clusters

ConclusionsConclusionsConclusionsConclusionsBenefits from DBD microplasma tailoring

ndash Reduced power consumption of up to 10 improvement

ndash Increased ozone concentrations of up to 14 now achievable

ndash Improved neutralization and conditioning of detrimental by-products

ndash Reduced system capital and operational cost

New technologies to improve ozone p

generatorg

HV Pulsed Power SwitchingHV Pulsed Power Switching

Microchannel Generation of Ozone

Channel ArrayChannel Array

Microchannel

330 microm 230 microm

Some Cap-DBD Devices Operating in Air

Increase of 60 of

Spacing 225 μmof 60 of plasma

No space

Cap‐DBD ozone generation

bull Ozone concentration is evaluated via Eco S d l UV 100 O A l (0 01Sensors model UV-100 Ozone Analyzer (001 ndash 900 ppm wiht an accuracy of plusmn2)

bull Three reactors 6 tubings 6rdquo with spacings of 0 μm 225 μm and 500 μm running at 3 kV μ μ μ g

SpacingOzone Concentration

3 kV rms 4 kV rms3 kV rms 4 kV rms

0 μm 660 ppm

225 μm 550 ppm

For a device of such small scale these ozone levels are promising

500 μm 380 ppm

J Mahoney W Zhu VS Johnson KH Becker and JL Lopez Electrical and optical emissionmeasurements of a capillary dielectric barrier discharge European Physics Journal D Vol 60 441-447(2010)

QuestionsQuestions

Thank YouFor more informationProf Jose L Lopez PhD

Thank YouFor more informationDepartment of Physics

Telephone (973) 761-9057Email joselopez1shuedu

Website wwwshueduacademicsartsciphysicsWebsite wwwshueduacademicsartsciphysics

Page 30: Dielectric Barrier Discharge (DBD) & Progress in Large ...bonitz/si12/talks/august_8/lopez_si12.pdf · Dielectric Barrier Discharge (DBD) & Progress in Large-Scale Ozone Generation

Fundamental Operation of the DBDFundamental Operation of the DBD

Electron DensityTemporal Development (ns)

y

Outer Contour Linen = 1010 cm-3ne = 1010 cm 3

Inner Contour Linene = 1014 cm-3

Streamer Propagation in 1 bar AirAA Kulikovsky IEEE Trans Plasma Sci 25 439-446 (1997)

Numerical Results of Microdischarge Formationin Dielectric Barrier Discharges

Starting Phase of a Microdischarge (1 bar 20 CO2 80 H2)

E0=34 kVcm1010 cm-3

1010 cm-3 ne=1012 cm-3

1mm10 cm

ne=108 cm-3

An electron avalanche propagates towards the anode

Reverse propagationtowards the cathodepropagates towards the anode towards the cathode

Numerical Results of Microdischarge Formationin Dielectric Barrier Discharges

Cathode Layer Formation

E0=34 kVcm1010 cm-39 3 0

1mm

1010 cm-3

10 cmne=109 cm-31014

10131014

1013

10 cm1012

Just before the peak of the total current

Peak currentof the total current

Numerical Results of Microdischarge Formationin Dielectric Barrier Discharges

Local Field Collapse in Area Defined by Surface Discharge

ne=109cm-3 ne=1014 cm-3

Gap

Principals of DBD MicroplasmasPrincipals of DBD MicroplasmasPrincipals of DBD MicroplasmasPrincipals of DBD Microplasmas

C C-- - --- - - CG

CD

-- - - CG

CD

Principals of DBD MicroplasmasPrincipals of DBD MicroplasmasPrincipals of DBD MicroplasmasPrincipals of DBD Microplasmas

Dielectric Barrier Discharge (DBD)Dielectric Barrier Discharge (DBD)Electric Field

B kdBreakdown

Electrons amp Ions Discharge Physics

Excited SpeciesPlasma Chemistry

Chemical Reactions

OzoneGeneration

SurfaceTreatment

PollutionControl

ExcimerFormation CO2 Lasers Hydrogenation

of CO2

Excimer Lamps Plasma Displays

How A Plasma Display Works

How A Plasma Display Work

Plasma Display TelevisionsPlasma Display Televisions

Ozone Generator

3 O 2 O

Dielectric Barrier Discharge

3 O2 2 O3

OO22 OO33++OO22Ondash ndashO3O2

O2O2

Ondash ndash

endash O2Ondash ndash O2endash

O3

O3O2O2 O2

HeatHeatHeatHeat

Properties of Ozone (O3)

T i t i f f Tri-atomic form of oxygen

Most powerful commercial oxidizing agent

Unstable - must be generated and used onsite

Limited solubility in water but more so than oxygenLimited solubility in water but more so than oxygen

Leaves a dissolved residual which ultimately converts back to oxygenconverts back to oxygen

Discharge Tubes in Ozone GeneratorsDischarge Tubes in Ozone Generators

Traditional

Ozone Generator

with Glass Tubes

Generation of OzoneGeneration of Ozone

Generation of OzoneAdvantages of Enamel Dielectrics

Proven Patented Designbull Simplicity

Si l Di l i Cbull Single Dielectric Componentndash Reduced number of Dielectrics

bull Safety ndash Lower operating voltage

(lt 4000 V)bull Reliabilty

ndash Fused Dielectrics ensure continuous production

bull Lowest Power Consumption Operational Savingsndash Operational Savings

Modern Ozone GeneratorModern Ozone Generator

Ozonia Advanced Technology Ozone GeneratorOzone Generator

Generation of OzoneGeneration of Ozone

Generation of Ozone

Power Supply UnitPower Supply Unit

IGBT Inverter CircuitMain Circuit Breaker

HV 480 Volts60 Hz3 Phase Supply

C I

450KVAPow er to

GeneratorFILTER

CONVERTER INVERTERTRANSFORMER

C I450KVA Power Stage

CONTACTOR

bull Latest in Power Semiconductor Technology Modular Design

bull Utilizes IGBTrsquos (Insulated Gate Bi‐Polar Transistors) Converter and Inverter Components

Ozone Water Treatment

B bbl Diff iB bbl Diff iBubble DiffusionBubble Diffusion

Easy to use

Low energy usage Low energy usage

Mass transfer efficiencies to gt 90

Ozone Process Flow DiagramOzone Process Flow DiagramVent to

Atmosphere

O OOxygen

Off-Gas Blower

Ozone Destruct Unit

10 12

O3O2

LOX

10-12 O3

Ozone Generators

Ozone Contact ChamberLOX T k Generators Chamber

VaporizersLOX Tank

Municipal Ozone Installations

Ozonia Installations Ozone Plant Size [lbday] Start-Up DateKey Ozonia Installations (Partial List)

Los Angeles CA 10000 1986Fairfax VA ndash Corbalis 9000 2003MWD CA ndash Mills 9 000 2003

Ozonia Installations Ozone Plant Size [lbday] Start Up Date

MWD CA Mills 9000 2003Fairfax Co VA ndash Griffith 9000 2004MWD CA ndash Jensen 18750 2005Indianapolis IN ndash Belmont AWT 12000 2007I di li IN 12 000 2007Indianapolis IN ndash Southport AWT 12000 2007MWD CA ndash Diemer 13400 2008MWD CA ndash Weymouth 13400 2009

Ozonia North America - Potable Water SummaryTotal Number of Installations 90Total Installed Production gt 265000 lbsdayTotal Installed Production 265000 lbsday

Revision -B

Ozone Water TreatmentOzone Water Treatment

MWD Mills WTP - California

3 3 000 lbsda of o one3 3 000 lbsda of o one3 x 3000 lbsday of ozone3 x 3000 lbsday of ozone

Ozone Water TreatmentOzone Water TreatmentOzone Ozone -- How it worksHow it works

OxidantOxidant DisinfectantDisinfectant

bullbull Breaks double carbon Breaks double carbon bondsbonds

bullbull Kills by cell lysing or Kills by cell lysing or causing the cell wall tocausing the cell wall tobondsbonds

bullbull Creates OHCreates OHbullbull radicals radicals which break higher carbon which break higher carbon

causing the cell wall to causing the cell wall to rupture rupture

bullbull AttacksAttacks allall bacteriabacteriabondsbondsbullbull Increased temp and pH Increased temp and pH

accelerates Oaccelerates O33

Attacks Attacks allall bacteria bacteria virus cysts and spores virus cysts and spores in varying degreesin varying degreesaccelerates Oaccelerates O33

decomposition to OHdecomposition to OHbullbull

Micro-organism DNA

Capsule AdenineAdenine

Cell wall ThymineThymine

CytosineCytosine

GuanineGuanine

NuclearmaterialCellmembrane

material

Typical Bacterium DNA

Microbial Growth at Various Ozone ConcentrationsConcentrations

Growth likely

Growth possibleGrowth possible

NO GROWTH

0004 0008 0012 0016 0020

Ozone concentration (mgl)Ozone concentration (mgl)

Typical Water Treatment UsageTypical Water Treatment Usage

Application O3 mgl Contact timeUltra Pure Water 005 - 025 sec ndash min

Water bottling 04 ndash 10 5 ndash 10 min

Swimming pools ampspas

01 ndash 075 4 minutes

Potable taste amp odor 15 ndash 50 5 ndash 10 mindisinfection

Microfloculation 10 ndash 30 5 ndash 10 min

Lignin amp tammin 3 0 10 0 10 30 minLignin amp tamminremoval

30 ndash 100 10 ndash 30 min

Municipal wastewater 50 ndash 150+ 15 ndash 30 min

Ozone Water TreatmentOzone Water TreatmentOzone Ozone ndashndash Municipal ApplicationsMunicipal Applications

bullbull Taste and OdorTaste and Odor

bullbull Color RemovalColor Removal

bullbull Disinfection Without Trihalomethanes (THMs)Disinfection Without Trihalomethanes (THMs)

bullbull Improved Filtration Efficiency and FlocculationImproved Filtration Efficiency and Flocculation

bullbull Cryptosporidium DeactivationCryptosporidium Deactivation

bullbull Giardia amp Virus InactivationGiardia amp Virus Inactivation

bullbull Oxidation Oxidation -- Organics Fe amp MnOrganics Fe amp Mn

bullbull Wastewater disinfectionWastewater disinfection

bullbull BOD COD and TOC reductionBOD COD and TOC reduction

Applications of Ozone

Wastewater Treatmentbull Disinfection of Secondary and Tertiary Effluentsbull Color Reductionbull Color Reductionbull TOC Oxidation (Industrial)bull Oxidation of Odor Causing Compoundsbull Oxidation of Endocrine Disruptors (EDCrsquos) and p ( )

Pharmaceutically Active Compounds (PACrsquos)

Applications of Ozone

What are Endocrine Disruptors (EDCrsquos) and What are Endocrine Disruptors (EDCrsquos) and Ph ti ll A ti C d (PACrsquo )Ph ti ll A ti C d (PACrsquo )Pharmaceutically Active Compounds (PACrsquos)Pharmaceutically Active Compounds (PACrsquos)

bullbull EDCrsquosEDCrsquos andand PACrsquosPACrsquos areare NaturallyNaturally andand SyntheticSyntheticdd th tth t ff tff t thth b lb l llcompoundscompounds thatthat maymay affectaffect thethe balancebalance oror normalnormal

functionsfunctions inin animalsanimals andand humanshumans

What can EDCrsquos and PACrsquos doWhat can EDCrsquos and PACrsquos do

bullbull Even in very small concentrations these compounds Even in very small concentrations these compounds y py pcan can disruptdisrupt normal bodily functionsnormal bodily functions

bullbull ManMan--made chemicals can trick the bodies endocrine made chemicals can trick the bodies endocrine system system

Applications of Ozone

Examples of Endocrine Disruptors1000rsquos of compounds that may be Investigated as EDCs ndash Some examples are

bullbull Synthetic HormonesSynthetic Hormonesbullbull Naturally Occurring Estrogens Naturally Occurring Estrogens

Health and Beauty AidsHealth and Beauty Aidsbullbull Health and Beauty AidsHealth and Beauty Aidsbullbull SolventsSolventsbullbull PesticidesPesticidesbullbull SurfactantsSurfactantsbullbull PlasticsPlastics

F i idF i idbullbull FungicidesFungicides

Ozone Water TreatmentOzone Water Treatment

Ozone Ozone -- Industrial ApplicationsIndustrial Applications-- Ultrapure Water for Pharmaceutical ApplicationsUltrapure Water for Pharmaceutical Applications

-- Wastewater disinfection color removalWastewater disinfection color removal

-- Soil and Groundwater Remediation Soil and Groundwater Remediation

-- Cooling Tower Water TreatmentCooling Tower Water Treatment

-- Food ProcessingFood Processing

-- Aquaculture AquariumsAquaculture AquariumsAquaculture AquariumsAquaculture Aquariums

-- Beverage ApplicationsBeverage Applications

P l amp P Bl hiP l amp P Bl hi-- Pulp amp Paper BleachingPulp amp Paper Bleaching

High Purity OzonationHigh Purity Ozonation

Microchip manufacturingMicrochip manufacturing

What are the current issues in large-scale gozone generationg

Experimental Setup

Front view of the two units after the redesign and reworking ofthe gas water and instruments connectionsthe gas water and instruments connections

Experimental Setup

Top view of the twoexperimental unitsexperimental unitsSpectroscope (notshown) is to the left ofthe DBD The units weredifferent with respect todifferent with respect totheir electrodes onehad only the electrodecoated with thedielectric (ldquosingle-dielectric ( single-coatedrdquo) the other onehad the electrode andthe anode coated withthe dielectric (ldquodouble-the dielectric ( double-coatedrdquo)

Basics Generation of OzoneBasics Generation of Ozone

SpectroscopyPlasma

Plasma Absorption SpectroscopyPlasma Absorption Spectroscopy

Infrared Absorption SpectroscopyInfrared Absorption Spectroscopy

IR spectra in pure oxygen (black curve) and at approximately 10wt N2 admixture (red line) N2O5 peaks appear at124 1 d 1 2 11245 cm-1 and at 1725 cm-1

Infrared Absorption SpectroscopyInfrared Absorption Spectroscopy

IR spectra of several methane variations The green curve envelopes all of the methane peaks at 1325 cm-1recorded at smaller methane admixtures Simultaneously the N2O5 peaks disappear as the methane peaks appear

N2O5 FormationN2O5 Formation2 52 5p=2 bara cwt=20degC q=35kWm2 f=1450Hz

45N2O5 AT95

30

35

40

N

2 B

lend

ing

N2O AT95N2O5 IGSN2O IGSN2O5 LGN2O LG

1 5

20

25

nt [p

pmV]

3

wt

05

10

15

NO

x co

nten

005 7 9 11 13 15 17

ozone conc [wt]

Amount of formed N2O5 and N2O as a function of ozone concentration at 3 wt of nitrogen admixture and fori l dvarious electrode arrangements

Plasma Emission SpectroscopyPlasma Emission Spectroscopyp pyp py

Relative Emissions of the Ozonizer plasmaRelative Emissions of the Ozonizer plasma

Region 300- 850 nm from individual (calibrated) regions (smoothed by PeakFit) Single-coated ozone generator Inlet side

3 5E+06

30E+06

35E+06

7 9

20E+06

25E+06

nten

sity

au

2

311 12

10E+06

15E+06

In 4

5

6 8 10

14

15

16

17

00E+00

50E+05

280 300 320 340 360 380 400 420 440 460 480 500 520 540 560 580 600 620 640 660 680 700 720 740 760 780 800 820 840 860

Wavelength nm

1 13

Wavelength nm

Absolute Emission of the DBD PlasmaAbsolute Emission of the DBD Plasma

Intensities in (O2+3 wtN2) plasma

1 20E+04

100E+04

120E+04

600E+03

800E+03

nten

sity

(au

)

200E+03

400E+03

In

O(777)

000E+00200 250 300 350 400 450 500 550 600 650 700 750 800 850

Wavelength nm

Intensities in 3 wtN2+O2 plasmaIntensities in 3 wtN2+O2 plasma

Plasma Chemistry in OzonizersPlasma Chemistry in Ozonizers

Dry Air O2 N2

e - e -

O N2 N O2

O3 NO

O2 N O2

O3

N

3

NO2

O2 O3

NO

N

NO2 O3

N2O

NO3 N

N2O4

NO2

NO2

N2O5

NO3

Primary electron-driven chemical reactions leading to the formation of N2O5 and N2O in a dry air plasma

Plasma emission diagnostics role of N2Plasma emission diagnostics role of N2

Dry Air O2 N2

e - e -

O N2 N O2

O3 NO

O2 N O2

O3

O

N

ON

NO2

O2O3

N

NO N

NO2 O3

N2O

NO3 N

N2O4

NO2

NO2

N2O5

NO3

ONbullWith N2 present ndash less oxygen atoms are formed However the difference in intensity is

very small

Modeling of plasma chemistry incl the NxOy chemistry up to N2O5 for different Oxygen Nitrogen mixtures varying power deposition scenarios

and initial ozone background concentrations (up to 15) previously done

The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation

The role of N2 must be related to its by-products reacting on the surface of the electrodeThe role of N2 must be related to its by-products reacting on the surface of the electrode

The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established

Ab 8 t f O

The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established

Ab 8 t f OAbove 8 wt of O3

1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)

Above 8 wt of O3

1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)case without pampp)

2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of the

case without pampp)

2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of thethem A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface

them A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface

The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation

Three possibilities have to be considered for the oxygen-fedozone generator

Three possibilities have to be considered for the oxygen-fedozone generatorozone generator

bull Excited N2 molecules lead to an increased O2 dissociation in

ozone generator

bull Excited N2 molecules lead to an increased O2 dissociation in2 2such case an increased efficiency is correlated to the N2admixture

2 2such case an increased efficiency is correlated to the N2admixture

bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial

bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial

bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2

bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2g p g 3 pp y 2g p g 3 pp y 2

Effect of methane on ozone efficiency and specific powerEffect of methane on ozone efficiency and specific power

Effect of Methane on Ozone Content in Outlet Gas and on Specific Power Pure O2

13 12

10

11

12

t 8

10

8

9

10

ne c

onte

nt w

t

6

8

ecifi

c po

wer

kW

hlb

5

6

7

Ozo

n

2

4 Spe

400E+00 20E+03 40E+03 60E+03 80E+03 10E+04 12E+04

Methane in feedgas ppm

0

Ozone content in the outlet gas Specif ic pow er of the ozone generatorg p p g

Effects of N2 and CH4Effects of N2 and CH4

Pi t f h t lli N O t tPicture of an amorphous-crystalline N2O5 structurecaptured at the Orlando Skylake water plant in 2006

Plasma Chemistry with CH4 Impurities

OxygenO2 N2

e - e -

CHO N2

NO2

O NO

O2 N O2 O3

NOH

CH4e-

O3 NO

NO2

O2O3NO N

NO2 O

NO2

NO2

N2ONO3

N

O3

NO2

NO

HNO3

N2O4

N2O5

NO2

NO3

N2O5

Effect of methane on the electrode surfaces

a) b)

Inlet Outlet Outlet

) d)

I l t I l t

c) d)

Electrode of the ozone generator afterseveral hours in CH8O2 and up to 2 wt of methane (a b c)

Inlet Inlet

three hours in CH8O2+traces of N2 and up to 1 wt of methane (d) Visible change of discharge character at about 13 length of electrode (a d)

Kinetics of CHx Conversion without N2

conversion by collisions

O2 + CHx 12wt O3 + CO2 +H2O

deposition vaporizationby sputtering

ibl b l 1000 CHreversible process below 1000ppm CH4

Effect of water on electrode surface with N2

Inlet

OutletOutlet

Electrode of the ozone generator after several hours in H OO N

Inlet

Electrode of the ozone generator after several hours in H2OO2N2

Effect of water on electrode surface

Long term effect (800 hrs) of H2OO2N2

Kinetics of CHx Conversion with N2

conversion by collisionsHNO3 formation

O2 + N2 +CHx 12wtO2 + CO2 +H2O + HNO3

deposition vaporizationby sputtering

H2O + HNO3

by sputtering

irreversible process above a N2 threshold () ltlt 1000ppm N2

sticky deposit

p 2 ( ) pp 2 any CH4 concentration (60ppm)

Plasma Chemistry with CH4 ImpuritiesPlasma Chemistry with CH4 Impurities4

bull Formation of NO and NO2 depends on O3 N2 and gas temperature Conclusion N2 admixture is the key factor

SummarySummaryyyThe mechanisms of formed NOx by-products follows the sameThe mechanisms of formed NOx by-products follows the sameprinciples as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentration

principles as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentrationozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)

ozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)g p ( g p )

The conversion of methane to OH and H2O is found to depend on

g p ( g p )

The conversion of methane to OH and H2O is found to depend ondissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)

dissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)discharge gap)discharge gap)

How do you optimize an ozone generatorg

Scientific ApproachScientific ApproachTheoretical Experimental

pppp

c [wt]

f [Hz]

c [wt]

f [Hz]

[kW]UUUβ1

1Cf4αPn

1iiminpeakimin

iiD

q [kWm2]q [kWm2]

150

180

][V]voltagepeakUpeak

[]cylinder perslicesofamountnsliceii

whereth

09 00

30

60

90

120

effic

ienc

y [

][0tdj t bl[F]sliceisdielectricofecapacitancC

[Hz]frequencyf[V]sliceivoltageminimumiUmin

thiD

th

10

28

46

64

82

39

107

176

244 power density

[kWm2]

ozone conc [wt][]CCβ

][0parameteradjustableα

iDiGi

Impact of Power Inductionp

350

400

wer

200

250

300

App

lied

Pow

Arr C 2Arr D +0

Arr E +45Arr F +7

Arr G +3

5 0

100

150

Frac

tion

of

1 2 3 4

ReferenceArr B unstable

Arr C -2

00

50

4Position (1inlet 4outlet)

Experimental Test Rigp g

Experimental Test Rigp g

Outer grounded electrode (left picture) and the dielectric covered inner electrodes (right) d e ect c cove ed e e ect odes ( g t)

Reference (Traditional) Arrangement

Inlet OutletGas flow direction

Optimized Arrangement

Inlet OutletGas flow direction

Intelligent Gap System (IGS)g p y ( )

Molecular Oxygen (O2) Ozone (O3)

O2 O3

yg ( 2) ( 3)

Particle Size SynthesisParticle Size SynthesisByBy--Products Cluster FormationProducts Cluster Formationyy

high diffusion and deposition to surfaces

low diffusion rate good transport

high sedimentation on the structurehigh sedimentation on the structure

Degreacutemont Technologies ndash OzoniaIntelligent Gap SystemIntelligent Gap System

G Vezzuacute JL Lopez A Freilich and K Becker Optimizationof Large-Scale Ozone Generators IEEE Transactions onPlasma Science Vol 37 No 6 p 890-896 (2009)

ConclusionsConclusionsConclusionsConclusionsFundamentals of ozone synthesis in a DBD plasmay p

ndash Highly filamented DBD discharges are best-suitedfor the production of ozone concentrations in therange of 6 to 14 wtrange of 6 to 14 wt

ndash The preferred characteristic of the microdischargesare Townsend-like at reduced electric fields Enaround 190 Townsend

ndash Detrimental side-effects induced by by-productscan be avoided by a proper design of the electrodecan be avoided by a proper design of the electrodearrangement The phenomenon is related to thediffusion rates of formed by-product clusters

ConclusionsConclusionsConclusionsConclusionsBenefits from DBD microplasma tailoring

ndash Reduced power consumption of up to 10 improvement

ndash Increased ozone concentrations of up to 14 now achievable

ndash Improved neutralization and conditioning of detrimental by-products

ndash Reduced system capital and operational cost

New technologies to improve ozone p

generatorg

HV Pulsed Power SwitchingHV Pulsed Power Switching

Microchannel Generation of Ozone

Channel ArrayChannel Array

Microchannel

330 microm 230 microm

Some Cap-DBD Devices Operating in Air

Increase of 60 of

Spacing 225 μmof 60 of plasma

No space

Cap‐DBD ozone generation

bull Ozone concentration is evaluated via Eco S d l UV 100 O A l (0 01Sensors model UV-100 Ozone Analyzer (001 ndash 900 ppm wiht an accuracy of plusmn2)

bull Three reactors 6 tubings 6rdquo with spacings of 0 μm 225 μm and 500 μm running at 3 kV μ μ μ g

SpacingOzone Concentration

3 kV rms 4 kV rms3 kV rms 4 kV rms

0 μm 660 ppm

225 μm 550 ppm

For a device of such small scale these ozone levels are promising

500 μm 380 ppm

J Mahoney W Zhu VS Johnson KH Becker and JL Lopez Electrical and optical emissionmeasurements of a capillary dielectric barrier discharge European Physics Journal D Vol 60 441-447(2010)

QuestionsQuestions

Thank YouFor more informationProf Jose L Lopez PhD

Thank YouFor more informationDepartment of Physics

Telephone (973) 761-9057Email joselopez1shuedu

Website wwwshueduacademicsartsciphysicsWebsite wwwshueduacademicsartsciphysics

Page 31: Dielectric Barrier Discharge (DBD) & Progress in Large ...bonitz/si12/talks/august_8/lopez_si12.pdf · Dielectric Barrier Discharge (DBD) & Progress in Large-Scale Ozone Generation

Numerical Results of Microdischarge Formationin Dielectric Barrier Discharges

Starting Phase of a Microdischarge (1 bar 20 CO2 80 H2)

E0=34 kVcm1010 cm-3

1010 cm-3 ne=1012 cm-3

1mm10 cm

ne=108 cm-3

An electron avalanche propagates towards the anode

Reverse propagationtowards the cathodepropagates towards the anode towards the cathode

Numerical Results of Microdischarge Formationin Dielectric Barrier Discharges

Cathode Layer Formation

E0=34 kVcm1010 cm-39 3 0

1mm

1010 cm-3

10 cmne=109 cm-31014

10131014

1013

10 cm1012

Just before the peak of the total current

Peak currentof the total current

Numerical Results of Microdischarge Formationin Dielectric Barrier Discharges

Local Field Collapse in Area Defined by Surface Discharge

ne=109cm-3 ne=1014 cm-3

Gap

Principals of DBD MicroplasmasPrincipals of DBD MicroplasmasPrincipals of DBD MicroplasmasPrincipals of DBD Microplasmas

C C-- - --- - - CG

CD

-- - - CG

CD

Principals of DBD MicroplasmasPrincipals of DBD MicroplasmasPrincipals of DBD MicroplasmasPrincipals of DBD Microplasmas

Dielectric Barrier Discharge (DBD)Dielectric Barrier Discharge (DBD)Electric Field

B kdBreakdown

Electrons amp Ions Discharge Physics

Excited SpeciesPlasma Chemistry

Chemical Reactions

OzoneGeneration

SurfaceTreatment

PollutionControl

ExcimerFormation CO2 Lasers Hydrogenation

of CO2

Excimer Lamps Plasma Displays

How A Plasma Display Works

How A Plasma Display Work

Plasma Display TelevisionsPlasma Display Televisions

Ozone Generator

3 O 2 O

Dielectric Barrier Discharge

3 O2 2 O3

OO22 OO33++OO22Ondash ndashO3O2

O2O2

Ondash ndash

endash O2Ondash ndash O2endash

O3

O3O2O2 O2

HeatHeatHeatHeat

Properties of Ozone (O3)

T i t i f f Tri-atomic form of oxygen

Most powerful commercial oxidizing agent

Unstable - must be generated and used onsite

Limited solubility in water but more so than oxygenLimited solubility in water but more so than oxygen

Leaves a dissolved residual which ultimately converts back to oxygenconverts back to oxygen

Discharge Tubes in Ozone GeneratorsDischarge Tubes in Ozone Generators

Traditional

Ozone Generator

with Glass Tubes

Generation of OzoneGeneration of Ozone

Generation of OzoneAdvantages of Enamel Dielectrics

Proven Patented Designbull Simplicity

Si l Di l i Cbull Single Dielectric Componentndash Reduced number of Dielectrics

bull Safety ndash Lower operating voltage

(lt 4000 V)bull Reliabilty

ndash Fused Dielectrics ensure continuous production

bull Lowest Power Consumption Operational Savingsndash Operational Savings

Modern Ozone GeneratorModern Ozone Generator

Ozonia Advanced Technology Ozone GeneratorOzone Generator

Generation of OzoneGeneration of Ozone

Generation of Ozone

Power Supply UnitPower Supply Unit

IGBT Inverter CircuitMain Circuit Breaker

HV 480 Volts60 Hz3 Phase Supply

C I

450KVAPow er to

GeneratorFILTER

CONVERTER INVERTERTRANSFORMER

C I450KVA Power Stage

CONTACTOR

bull Latest in Power Semiconductor Technology Modular Design

bull Utilizes IGBTrsquos (Insulated Gate Bi‐Polar Transistors) Converter and Inverter Components

Ozone Water Treatment

B bbl Diff iB bbl Diff iBubble DiffusionBubble Diffusion

Easy to use

Low energy usage Low energy usage

Mass transfer efficiencies to gt 90

Ozone Process Flow DiagramOzone Process Flow DiagramVent to

Atmosphere

O OOxygen

Off-Gas Blower

Ozone Destruct Unit

10 12

O3O2

LOX

10-12 O3

Ozone Generators

Ozone Contact ChamberLOX T k Generators Chamber

VaporizersLOX Tank

Municipal Ozone Installations

Ozonia Installations Ozone Plant Size [lbday] Start-Up DateKey Ozonia Installations (Partial List)

Los Angeles CA 10000 1986Fairfax VA ndash Corbalis 9000 2003MWD CA ndash Mills 9 000 2003

Ozonia Installations Ozone Plant Size [lbday] Start Up Date

MWD CA Mills 9000 2003Fairfax Co VA ndash Griffith 9000 2004MWD CA ndash Jensen 18750 2005Indianapolis IN ndash Belmont AWT 12000 2007I di li IN 12 000 2007Indianapolis IN ndash Southport AWT 12000 2007MWD CA ndash Diemer 13400 2008MWD CA ndash Weymouth 13400 2009

Ozonia North America - Potable Water SummaryTotal Number of Installations 90Total Installed Production gt 265000 lbsdayTotal Installed Production 265000 lbsday

Revision -B

Ozone Water TreatmentOzone Water Treatment

MWD Mills WTP - California

3 3 000 lbsda of o one3 3 000 lbsda of o one3 x 3000 lbsday of ozone3 x 3000 lbsday of ozone

Ozone Water TreatmentOzone Water TreatmentOzone Ozone -- How it worksHow it works

OxidantOxidant DisinfectantDisinfectant

bullbull Breaks double carbon Breaks double carbon bondsbonds

bullbull Kills by cell lysing or Kills by cell lysing or causing the cell wall tocausing the cell wall tobondsbonds

bullbull Creates OHCreates OHbullbull radicals radicals which break higher carbon which break higher carbon

causing the cell wall to causing the cell wall to rupture rupture

bullbull AttacksAttacks allall bacteriabacteriabondsbondsbullbull Increased temp and pH Increased temp and pH

accelerates Oaccelerates O33

Attacks Attacks allall bacteria bacteria virus cysts and spores virus cysts and spores in varying degreesin varying degreesaccelerates Oaccelerates O33

decomposition to OHdecomposition to OHbullbull

Micro-organism DNA

Capsule AdenineAdenine

Cell wall ThymineThymine

CytosineCytosine

GuanineGuanine

NuclearmaterialCellmembrane

material

Typical Bacterium DNA

Microbial Growth at Various Ozone ConcentrationsConcentrations

Growth likely

Growth possibleGrowth possible

NO GROWTH

0004 0008 0012 0016 0020

Ozone concentration (mgl)Ozone concentration (mgl)

Typical Water Treatment UsageTypical Water Treatment Usage

Application O3 mgl Contact timeUltra Pure Water 005 - 025 sec ndash min

Water bottling 04 ndash 10 5 ndash 10 min

Swimming pools ampspas

01 ndash 075 4 minutes

Potable taste amp odor 15 ndash 50 5 ndash 10 mindisinfection

Microfloculation 10 ndash 30 5 ndash 10 min

Lignin amp tammin 3 0 10 0 10 30 minLignin amp tamminremoval

30 ndash 100 10 ndash 30 min

Municipal wastewater 50 ndash 150+ 15 ndash 30 min

Ozone Water TreatmentOzone Water TreatmentOzone Ozone ndashndash Municipal ApplicationsMunicipal Applications

bullbull Taste and OdorTaste and Odor

bullbull Color RemovalColor Removal

bullbull Disinfection Without Trihalomethanes (THMs)Disinfection Without Trihalomethanes (THMs)

bullbull Improved Filtration Efficiency and FlocculationImproved Filtration Efficiency and Flocculation

bullbull Cryptosporidium DeactivationCryptosporidium Deactivation

bullbull Giardia amp Virus InactivationGiardia amp Virus Inactivation

bullbull Oxidation Oxidation -- Organics Fe amp MnOrganics Fe amp Mn

bullbull Wastewater disinfectionWastewater disinfection

bullbull BOD COD and TOC reductionBOD COD and TOC reduction

Applications of Ozone

Wastewater Treatmentbull Disinfection of Secondary and Tertiary Effluentsbull Color Reductionbull Color Reductionbull TOC Oxidation (Industrial)bull Oxidation of Odor Causing Compoundsbull Oxidation of Endocrine Disruptors (EDCrsquos) and p ( )

Pharmaceutically Active Compounds (PACrsquos)

Applications of Ozone

What are Endocrine Disruptors (EDCrsquos) and What are Endocrine Disruptors (EDCrsquos) and Ph ti ll A ti C d (PACrsquo )Ph ti ll A ti C d (PACrsquo )Pharmaceutically Active Compounds (PACrsquos)Pharmaceutically Active Compounds (PACrsquos)

bullbull EDCrsquosEDCrsquos andand PACrsquosPACrsquos areare NaturallyNaturally andand SyntheticSyntheticdd th tth t ff tff t thth b lb l llcompoundscompounds thatthat maymay affectaffect thethe balancebalance oror normalnormal

functionsfunctions inin animalsanimals andand humanshumans

What can EDCrsquos and PACrsquos doWhat can EDCrsquos and PACrsquos do

bullbull Even in very small concentrations these compounds Even in very small concentrations these compounds y py pcan can disruptdisrupt normal bodily functionsnormal bodily functions

bullbull ManMan--made chemicals can trick the bodies endocrine made chemicals can trick the bodies endocrine system system

Applications of Ozone

Examples of Endocrine Disruptors1000rsquos of compounds that may be Investigated as EDCs ndash Some examples are

bullbull Synthetic HormonesSynthetic Hormonesbullbull Naturally Occurring Estrogens Naturally Occurring Estrogens

Health and Beauty AidsHealth and Beauty Aidsbullbull Health and Beauty AidsHealth and Beauty Aidsbullbull SolventsSolventsbullbull PesticidesPesticidesbullbull SurfactantsSurfactantsbullbull PlasticsPlastics

F i idF i idbullbull FungicidesFungicides

Ozone Water TreatmentOzone Water Treatment

Ozone Ozone -- Industrial ApplicationsIndustrial Applications-- Ultrapure Water for Pharmaceutical ApplicationsUltrapure Water for Pharmaceutical Applications

-- Wastewater disinfection color removalWastewater disinfection color removal

-- Soil and Groundwater Remediation Soil and Groundwater Remediation

-- Cooling Tower Water TreatmentCooling Tower Water Treatment

-- Food ProcessingFood Processing

-- Aquaculture AquariumsAquaculture AquariumsAquaculture AquariumsAquaculture Aquariums

-- Beverage ApplicationsBeverage Applications

P l amp P Bl hiP l amp P Bl hi-- Pulp amp Paper BleachingPulp amp Paper Bleaching

High Purity OzonationHigh Purity Ozonation

Microchip manufacturingMicrochip manufacturing

What are the current issues in large-scale gozone generationg

Experimental Setup

Front view of the two units after the redesign and reworking ofthe gas water and instruments connectionsthe gas water and instruments connections

Experimental Setup

Top view of the twoexperimental unitsexperimental unitsSpectroscope (notshown) is to the left ofthe DBD The units weredifferent with respect todifferent with respect totheir electrodes onehad only the electrodecoated with thedielectric (ldquosingle-dielectric ( single-coatedrdquo) the other onehad the electrode andthe anode coated withthe dielectric (ldquodouble-the dielectric ( double-coatedrdquo)

Basics Generation of OzoneBasics Generation of Ozone

SpectroscopyPlasma

Plasma Absorption SpectroscopyPlasma Absorption Spectroscopy

Infrared Absorption SpectroscopyInfrared Absorption Spectroscopy

IR spectra in pure oxygen (black curve) and at approximately 10wt N2 admixture (red line) N2O5 peaks appear at124 1 d 1 2 11245 cm-1 and at 1725 cm-1

Infrared Absorption SpectroscopyInfrared Absorption Spectroscopy

IR spectra of several methane variations The green curve envelopes all of the methane peaks at 1325 cm-1recorded at smaller methane admixtures Simultaneously the N2O5 peaks disappear as the methane peaks appear

N2O5 FormationN2O5 Formation2 52 5p=2 bara cwt=20degC q=35kWm2 f=1450Hz

45N2O5 AT95

30

35

40

N

2 B

lend

ing

N2O AT95N2O5 IGSN2O IGSN2O5 LGN2O LG

1 5

20

25

nt [p

pmV]

3

wt

05

10

15

NO

x co

nten

005 7 9 11 13 15 17

ozone conc [wt]

Amount of formed N2O5 and N2O as a function of ozone concentration at 3 wt of nitrogen admixture and fori l dvarious electrode arrangements

Plasma Emission SpectroscopyPlasma Emission Spectroscopyp pyp py

Relative Emissions of the Ozonizer plasmaRelative Emissions of the Ozonizer plasma

Region 300- 850 nm from individual (calibrated) regions (smoothed by PeakFit) Single-coated ozone generator Inlet side

3 5E+06

30E+06

35E+06

7 9

20E+06

25E+06

nten

sity

au

2

311 12

10E+06

15E+06

In 4

5

6 8 10

14

15

16

17

00E+00

50E+05

280 300 320 340 360 380 400 420 440 460 480 500 520 540 560 580 600 620 640 660 680 700 720 740 760 780 800 820 840 860

Wavelength nm

1 13

Wavelength nm

Absolute Emission of the DBD PlasmaAbsolute Emission of the DBD Plasma

Intensities in (O2+3 wtN2) plasma

1 20E+04

100E+04

120E+04

600E+03

800E+03

nten

sity

(au

)

200E+03

400E+03

In

O(777)

000E+00200 250 300 350 400 450 500 550 600 650 700 750 800 850

Wavelength nm

Intensities in 3 wtN2+O2 plasmaIntensities in 3 wtN2+O2 plasma

Plasma Chemistry in OzonizersPlasma Chemistry in Ozonizers

Dry Air O2 N2

e - e -

O N2 N O2

O3 NO

O2 N O2

O3

N

3

NO2

O2 O3

NO

N

NO2 O3

N2O

NO3 N

N2O4

NO2

NO2

N2O5

NO3

Primary electron-driven chemical reactions leading to the formation of N2O5 and N2O in a dry air plasma

Plasma emission diagnostics role of N2Plasma emission diagnostics role of N2

Dry Air O2 N2

e - e -

O N2 N O2

O3 NO

O2 N O2

O3

O

N

ON

NO2

O2O3

N

NO N

NO2 O3

N2O

NO3 N

N2O4

NO2

NO2

N2O5

NO3

ONbullWith N2 present ndash less oxygen atoms are formed However the difference in intensity is

very small

Modeling of plasma chemistry incl the NxOy chemistry up to N2O5 for different Oxygen Nitrogen mixtures varying power deposition scenarios

and initial ozone background concentrations (up to 15) previously done

The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation

The role of N2 must be related to its by-products reacting on the surface of the electrodeThe role of N2 must be related to its by-products reacting on the surface of the electrode

The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established

Ab 8 t f O

The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established

Ab 8 t f OAbove 8 wt of O3

1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)

Above 8 wt of O3

1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)case without pampp)

2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of the

case without pampp)

2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of thethem A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface

them A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface

The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation

Three possibilities have to be considered for the oxygen-fedozone generator

Three possibilities have to be considered for the oxygen-fedozone generatorozone generator

bull Excited N2 molecules lead to an increased O2 dissociation in

ozone generator

bull Excited N2 molecules lead to an increased O2 dissociation in2 2such case an increased efficiency is correlated to the N2admixture

2 2such case an increased efficiency is correlated to the N2admixture

bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial

bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial

bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2

bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2g p g 3 pp y 2g p g 3 pp y 2

Effect of methane on ozone efficiency and specific powerEffect of methane on ozone efficiency and specific power

Effect of Methane on Ozone Content in Outlet Gas and on Specific Power Pure O2

13 12

10

11

12

t 8

10

8

9

10

ne c

onte

nt w

t

6

8

ecifi

c po

wer

kW

hlb

5

6

7

Ozo

n

2

4 Spe

400E+00 20E+03 40E+03 60E+03 80E+03 10E+04 12E+04

Methane in feedgas ppm

0

Ozone content in the outlet gas Specif ic pow er of the ozone generatorg p p g

Effects of N2 and CH4Effects of N2 and CH4

Pi t f h t lli N O t tPicture of an amorphous-crystalline N2O5 structurecaptured at the Orlando Skylake water plant in 2006

Plasma Chemistry with CH4 Impurities

OxygenO2 N2

e - e -

CHO N2

NO2

O NO

O2 N O2 O3

NOH

CH4e-

O3 NO

NO2

O2O3NO N

NO2 O

NO2

NO2

N2ONO3

N

O3

NO2

NO

HNO3

N2O4

N2O5

NO2

NO3

N2O5

Effect of methane on the electrode surfaces

a) b)

Inlet Outlet Outlet

) d)

I l t I l t

c) d)

Electrode of the ozone generator afterseveral hours in CH8O2 and up to 2 wt of methane (a b c)

Inlet Inlet

three hours in CH8O2+traces of N2 and up to 1 wt of methane (d) Visible change of discharge character at about 13 length of electrode (a d)

Kinetics of CHx Conversion without N2

conversion by collisions

O2 + CHx 12wt O3 + CO2 +H2O

deposition vaporizationby sputtering

ibl b l 1000 CHreversible process below 1000ppm CH4

Effect of water on electrode surface with N2

Inlet

OutletOutlet

Electrode of the ozone generator after several hours in H OO N

Inlet

Electrode of the ozone generator after several hours in H2OO2N2

Effect of water on electrode surface

Long term effect (800 hrs) of H2OO2N2

Kinetics of CHx Conversion with N2

conversion by collisionsHNO3 formation

O2 + N2 +CHx 12wtO2 + CO2 +H2O + HNO3

deposition vaporizationby sputtering

H2O + HNO3

by sputtering

irreversible process above a N2 threshold () ltlt 1000ppm N2

sticky deposit

p 2 ( ) pp 2 any CH4 concentration (60ppm)

Plasma Chemistry with CH4 ImpuritiesPlasma Chemistry with CH4 Impurities4

bull Formation of NO and NO2 depends on O3 N2 and gas temperature Conclusion N2 admixture is the key factor

SummarySummaryyyThe mechanisms of formed NOx by-products follows the sameThe mechanisms of formed NOx by-products follows the sameprinciples as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentration

principles as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentrationozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)

ozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)g p ( g p )

The conversion of methane to OH and H2O is found to depend on

g p ( g p )

The conversion of methane to OH and H2O is found to depend ondissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)

dissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)discharge gap)discharge gap)

How do you optimize an ozone generatorg

Scientific ApproachScientific ApproachTheoretical Experimental

pppp

c [wt]

f [Hz]

c [wt]

f [Hz]

[kW]UUUβ1

1Cf4αPn

1iiminpeakimin

iiD

q [kWm2]q [kWm2]

150

180

][V]voltagepeakUpeak

[]cylinder perslicesofamountnsliceii

whereth

09 00

30

60

90

120

effic

ienc

y [

][0tdj t bl[F]sliceisdielectricofecapacitancC

[Hz]frequencyf[V]sliceivoltageminimumiUmin

thiD

th

10

28

46

64

82

39

107

176

244 power density

[kWm2]

ozone conc [wt][]CCβ

][0parameteradjustableα

iDiGi

Impact of Power Inductionp

350

400

wer

200

250

300

App

lied

Pow

Arr C 2Arr D +0

Arr E +45Arr F +7

Arr G +3

5 0

100

150

Frac

tion

of

1 2 3 4

ReferenceArr B unstable

Arr C -2

00

50

4Position (1inlet 4outlet)

Experimental Test Rigp g

Experimental Test Rigp g

Outer grounded electrode (left picture) and the dielectric covered inner electrodes (right) d e ect c cove ed e e ect odes ( g t)

Reference (Traditional) Arrangement

Inlet OutletGas flow direction

Optimized Arrangement

Inlet OutletGas flow direction

Intelligent Gap System (IGS)g p y ( )

Molecular Oxygen (O2) Ozone (O3)

O2 O3

yg ( 2) ( 3)

Particle Size SynthesisParticle Size SynthesisByBy--Products Cluster FormationProducts Cluster Formationyy

high diffusion and deposition to surfaces

low diffusion rate good transport

high sedimentation on the structurehigh sedimentation on the structure

Degreacutemont Technologies ndash OzoniaIntelligent Gap SystemIntelligent Gap System

G Vezzuacute JL Lopez A Freilich and K Becker Optimizationof Large-Scale Ozone Generators IEEE Transactions onPlasma Science Vol 37 No 6 p 890-896 (2009)

ConclusionsConclusionsConclusionsConclusionsFundamentals of ozone synthesis in a DBD plasmay p

ndash Highly filamented DBD discharges are best-suitedfor the production of ozone concentrations in therange of 6 to 14 wtrange of 6 to 14 wt

ndash The preferred characteristic of the microdischargesare Townsend-like at reduced electric fields Enaround 190 Townsend

ndash Detrimental side-effects induced by by-productscan be avoided by a proper design of the electrodecan be avoided by a proper design of the electrodearrangement The phenomenon is related to thediffusion rates of formed by-product clusters

ConclusionsConclusionsConclusionsConclusionsBenefits from DBD microplasma tailoring

ndash Reduced power consumption of up to 10 improvement

ndash Increased ozone concentrations of up to 14 now achievable

ndash Improved neutralization and conditioning of detrimental by-products

ndash Reduced system capital and operational cost

New technologies to improve ozone p

generatorg

HV Pulsed Power SwitchingHV Pulsed Power Switching

Microchannel Generation of Ozone

Channel ArrayChannel Array

Microchannel

330 microm 230 microm

Some Cap-DBD Devices Operating in Air

Increase of 60 of

Spacing 225 μmof 60 of plasma

No space

Cap‐DBD ozone generation

bull Ozone concentration is evaluated via Eco S d l UV 100 O A l (0 01Sensors model UV-100 Ozone Analyzer (001 ndash 900 ppm wiht an accuracy of plusmn2)

bull Three reactors 6 tubings 6rdquo with spacings of 0 μm 225 μm and 500 μm running at 3 kV μ μ μ g

SpacingOzone Concentration

3 kV rms 4 kV rms3 kV rms 4 kV rms

0 μm 660 ppm

225 μm 550 ppm

For a device of such small scale these ozone levels are promising

500 μm 380 ppm

J Mahoney W Zhu VS Johnson KH Becker and JL Lopez Electrical and optical emissionmeasurements of a capillary dielectric barrier discharge European Physics Journal D Vol 60 441-447(2010)

QuestionsQuestions

Thank YouFor more informationProf Jose L Lopez PhD

Thank YouFor more informationDepartment of Physics

Telephone (973) 761-9057Email joselopez1shuedu

Website wwwshueduacademicsartsciphysicsWebsite wwwshueduacademicsartsciphysics

Page 32: Dielectric Barrier Discharge (DBD) & Progress in Large ...bonitz/si12/talks/august_8/lopez_si12.pdf · Dielectric Barrier Discharge (DBD) & Progress in Large-Scale Ozone Generation

Numerical Results of Microdischarge Formationin Dielectric Barrier Discharges

Cathode Layer Formation

E0=34 kVcm1010 cm-39 3 0

1mm

1010 cm-3

10 cmne=109 cm-31014

10131014

1013

10 cm1012

Just before the peak of the total current

Peak currentof the total current

Numerical Results of Microdischarge Formationin Dielectric Barrier Discharges

Local Field Collapse in Area Defined by Surface Discharge

ne=109cm-3 ne=1014 cm-3

Gap

Principals of DBD MicroplasmasPrincipals of DBD MicroplasmasPrincipals of DBD MicroplasmasPrincipals of DBD Microplasmas

C C-- - --- - - CG

CD

-- - - CG

CD

Principals of DBD MicroplasmasPrincipals of DBD MicroplasmasPrincipals of DBD MicroplasmasPrincipals of DBD Microplasmas

Dielectric Barrier Discharge (DBD)Dielectric Barrier Discharge (DBD)Electric Field

B kdBreakdown

Electrons amp Ions Discharge Physics

Excited SpeciesPlasma Chemistry

Chemical Reactions

OzoneGeneration

SurfaceTreatment

PollutionControl

ExcimerFormation CO2 Lasers Hydrogenation

of CO2

Excimer Lamps Plasma Displays

How A Plasma Display Works

How A Plasma Display Work

Plasma Display TelevisionsPlasma Display Televisions

Ozone Generator

3 O 2 O

Dielectric Barrier Discharge

3 O2 2 O3

OO22 OO33++OO22Ondash ndashO3O2

O2O2

Ondash ndash

endash O2Ondash ndash O2endash

O3

O3O2O2 O2

HeatHeatHeatHeat

Properties of Ozone (O3)

T i t i f f Tri-atomic form of oxygen

Most powerful commercial oxidizing agent

Unstable - must be generated and used onsite

Limited solubility in water but more so than oxygenLimited solubility in water but more so than oxygen

Leaves a dissolved residual which ultimately converts back to oxygenconverts back to oxygen

Discharge Tubes in Ozone GeneratorsDischarge Tubes in Ozone Generators

Traditional

Ozone Generator

with Glass Tubes

Generation of OzoneGeneration of Ozone

Generation of OzoneAdvantages of Enamel Dielectrics

Proven Patented Designbull Simplicity

Si l Di l i Cbull Single Dielectric Componentndash Reduced number of Dielectrics

bull Safety ndash Lower operating voltage

(lt 4000 V)bull Reliabilty

ndash Fused Dielectrics ensure continuous production

bull Lowest Power Consumption Operational Savingsndash Operational Savings

Modern Ozone GeneratorModern Ozone Generator

Ozonia Advanced Technology Ozone GeneratorOzone Generator

Generation of OzoneGeneration of Ozone

Generation of Ozone

Power Supply UnitPower Supply Unit

IGBT Inverter CircuitMain Circuit Breaker

HV 480 Volts60 Hz3 Phase Supply

C I

450KVAPow er to

GeneratorFILTER

CONVERTER INVERTERTRANSFORMER

C I450KVA Power Stage

CONTACTOR

bull Latest in Power Semiconductor Technology Modular Design

bull Utilizes IGBTrsquos (Insulated Gate Bi‐Polar Transistors) Converter and Inverter Components

Ozone Water Treatment

B bbl Diff iB bbl Diff iBubble DiffusionBubble Diffusion

Easy to use

Low energy usage Low energy usage

Mass transfer efficiencies to gt 90

Ozone Process Flow DiagramOzone Process Flow DiagramVent to

Atmosphere

O OOxygen

Off-Gas Blower

Ozone Destruct Unit

10 12

O3O2

LOX

10-12 O3

Ozone Generators

Ozone Contact ChamberLOX T k Generators Chamber

VaporizersLOX Tank

Municipal Ozone Installations

Ozonia Installations Ozone Plant Size [lbday] Start-Up DateKey Ozonia Installations (Partial List)

Los Angeles CA 10000 1986Fairfax VA ndash Corbalis 9000 2003MWD CA ndash Mills 9 000 2003

Ozonia Installations Ozone Plant Size [lbday] Start Up Date

MWD CA Mills 9000 2003Fairfax Co VA ndash Griffith 9000 2004MWD CA ndash Jensen 18750 2005Indianapolis IN ndash Belmont AWT 12000 2007I di li IN 12 000 2007Indianapolis IN ndash Southport AWT 12000 2007MWD CA ndash Diemer 13400 2008MWD CA ndash Weymouth 13400 2009

Ozonia North America - Potable Water SummaryTotal Number of Installations 90Total Installed Production gt 265000 lbsdayTotal Installed Production 265000 lbsday

Revision -B

Ozone Water TreatmentOzone Water Treatment

MWD Mills WTP - California

3 3 000 lbsda of o one3 3 000 lbsda of o one3 x 3000 lbsday of ozone3 x 3000 lbsday of ozone

Ozone Water TreatmentOzone Water TreatmentOzone Ozone -- How it worksHow it works

OxidantOxidant DisinfectantDisinfectant

bullbull Breaks double carbon Breaks double carbon bondsbonds

bullbull Kills by cell lysing or Kills by cell lysing or causing the cell wall tocausing the cell wall tobondsbonds

bullbull Creates OHCreates OHbullbull radicals radicals which break higher carbon which break higher carbon

causing the cell wall to causing the cell wall to rupture rupture

bullbull AttacksAttacks allall bacteriabacteriabondsbondsbullbull Increased temp and pH Increased temp and pH

accelerates Oaccelerates O33

Attacks Attacks allall bacteria bacteria virus cysts and spores virus cysts and spores in varying degreesin varying degreesaccelerates Oaccelerates O33

decomposition to OHdecomposition to OHbullbull

Micro-organism DNA

Capsule AdenineAdenine

Cell wall ThymineThymine

CytosineCytosine

GuanineGuanine

NuclearmaterialCellmembrane

material

Typical Bacterium DNA

Microbial Growth at Various Ozone ConcentrationsConcentrations

Growth likely

Growth possibleGrowth possible

NO GROWTH

0004 0008 0012 0016 0020

Ozone concentration (mgl)Ozone concentration (mgl)

Typical Water Treatment UsageTypical Water Treatment Usage

Application O3 mgl Contact timeUltra Pure Water 005 - 025 sec ndash min

Water bottling 04 ndash 10 5 ndash 10 min

Swimming pools ampspas

01 ndash 075 4 minutes

Potable taste amp odor 15 ndash 50 5 ndash 10 mindisinfection

Microfloculation 10 ndash 30 5 ndash 10 min

Lignin amp tammin 3 0 10 0 10 30 minLignin amp tamminremoval

30 ndash 100 10 ndash 30 min

Municipal wastewater 50 ndash 150+ 15 ndash 30 min

Ozone Water TreatmentOzone Water TreatmentOzone Ozone ndashndash Municipal ApplicationsMunicipal Applications

bullbull Taste and OdorTaste and Odor

bullbull Color RemovalColor Removal

bullbull Disinfection Without Trihalomethanes (THMs)Disinfection Without Trihalomethanes (THMs)

bullbull Improved Filtration Efficiency and FlocculationImproved Filtration Efficiency and Flocculation

bullbull Cryptosporidium DeactivationCryptosporidium Deactivation

bullbull Giardia amp Virus InactivationGiardia amp Virus Inactivation

bullbull Oxidation Oxidation -- Organics Fe amp MnOrganics Fe amp Mn

bullbull Wastewater disinfectionWastewater disinfection

bullbull BOD COD and TOC reductionBOD COD and TOC reduction

Applications of Ozone

Wastewater Treatmentbull Disinfection of Secondary and Tertiary Effluentsbull Color Reductionbull Color Reductionbull TOC Oxidation (Industrial)bull Oxidation of Odor Causing Compoundsbull Oxidation of Endocrine Disruptors (EDCrsquos) and p ( )

Pharmaceutically Active Compounds (PACrsquos)

Applications of Ozone

What are Endocrine Disruptors (EDCrsquos) and What are Endocrine Disruptors (EDCrsquos) and Ph ti ll A ti C d (PACrsquo )Ph ti ll A ti C d (PACrsquo )Pharmaceutically Active Compounds (PACrsquos)Pharmaceutically Active Compounds (PACrsquos)

bullbull EDCrsquosEDCrsquos andand PACrsquosPACrsquos areare NaturallyNaturally andand SyntheticSyntheticdd th tth t ff tff t thth b lb l llcompoundscompounds thatthat maymay affectaffect thethe balancebalance oror normalnormal

functionsfunctions inin animalsanimals andand humanshumans

What can EDCrsquos and PACrsquos doWhat can EDCrsquos and PACrsquos do

bullbull Even in very small concentrations these compounds Even in very small concentrations these compounds y py pcan can disruptdisrupt normal bodily functionsnormal bodily functions

bullbull ManMan--made chemicals can trick the bodies endocrine made chemicals can trick the bodies endocrine system system

Applications of Ozone

Examples of Endocrine Disruptors1000rsquos of compounds that may be Investigated as EDCs ndash Some examples are

bullbull Synthetic HormonesSynthetic Hormonesbullbull Naturally Occurring Estrogens Naturally Occurring Estrogens

Health and Beauty AidsHealth and Beauty Aidsbullbull Health and Beauty AidsHealth and Beauty Aidsbullbull SolventsSolventsbullbull PesticidesPesticidesbullbull SurfactantsSurfactantsbullbull PlasticsPlastics

F i idF i idbullbull FungicidesFungicides

Ozone Water TreatmentOzone Water Treatment

Ozone Ozone -- Industrial ApplicationsIndustrial Applications-- Ultrapure Water for Pharmaceutical ApplicationsUltrapure Water for Pharmaceutical Applications

-- Wastewater disinfection color removalWastewater disinfection color removal

-- Soil and Groundwater Remediation Soil and Groundwater Remediation

-- Cooling Tower Water TreatmentCooling Tower Water Treatment

-- Food ProcessingFood Processing

-- Aquaculture AquariumsAquaculture AquariumsAquaculture AquariumsAquaculture Aquariums

-- Beverage ApplicationsBeverage Applications

P l amp P Bl hiP l amp P Bl hi-- Pulp amp Paper BleachingPulp amp Paper Bleaching

High Purity OzonationHigh Purity Ozonation

Microchip manufacturingMicrochip manufacturing

What are the current issues in large-scale gozone generationg

Experimental Setup

Front view of the two units after the redesign and reworking ofthe gas water and instruments connectionsthe gas water and instruments connections

Experimental Setup

Top view of the twoexperimental unitsexperimental unitsSpectroscope (notshown) is to the left ofthe DBD The units weredifferent with respect todifferent with respect totheir electrodes onehad only the electrodecoated with thedielectric (ldquosingle-dielectric ( single-coatedrdquo) the other onehad the electrode andthe anode coated withthe dielectric (ldquodouble-the dielectric ( double-coatedrdquo)

Basics Generation of OzoneBasics Generation of Ozone

SpectroscopyPlasma

Plasma Absorption SpectroscopyPlasma Absorption Spectroscopy

Infrared Absorption SpectroscopyInfrared Absorption Spectroscopy

IR spectra in pure oxygen (black curve) and at approximately 10wt N2 admixture (red line) N2O5 peaks appear at124 1 d 1 2 11245 cm-1 and at 1725 cm-1

Infrared Absorption SpectroscopyInfrared Absorption Spectroscopy

IR spectra of several methane variations The green curve envelopes all of the methane peaks at 1325 cm-1recorded at smaller methane admixtures Simultaneously the N2O5 peaks disappear as the methane peaks appear

N2O5 FormationN2O5 Formation2 52 5p=2 bara cwt=20degC q=35kWm2 f=1450Hz

45N2O5 AT95

30

35

40

N

2 B

lend

ing

N2O AT95N2O5 IGSN2O IGSN2O5 LGN2O LG

1 5

20

25

nt [p

pmV]

3

wt

05

10

15

NO

x co

nten

005 7 9 11 13 15 17

ozone conc [wt]

Amount of formed N2O5 and N2O as a function of ozone concentration at 3 wt of nitrogen admixture and fori l dvarious electrode arrangements

Plasma Emission SpectroscopyPlasma Emission Spectroscopyp pyp py

Relative Emissions of the Ozonizer plasmaRelative Emissions of the Ozonizer plasma

Region 300- 850 nm from individual (calibrated) regions (smoothed by PeakFit) Single-coated ozone generator Inlet side

3 5E+06

30E+06

35E+06

7 9

20E+06

25E+06

nten

sity

au

2

311 12

10E+06

15E+06

In 4

5

6 8 10

14

15

16

17

00E+00

50E+05

280 300 320 340 360 380 400 420 440 460 480 500 520 540 560 580 600 620 640 660 680 700 720 740 760 780 800 820 840 860

Wavelength nm

1 13

Wavelength nm

Absolute Emission of the DBD PlasmaAbsolute Emission of the DBD Plasma

Intensities in (O2+3 wtN2) plasma

1 20E+04

100E+04

120E+04

600E+03

800E+03

nten

sity

(au

)

200E+03

400E+03

In

O(777)

000E+00200 250 300 350 400 450 500 550 600 650 700 750 800 850

Wavelength nm

Intensities in 3 wtN2+O2 plasmaIntensities in 3 wtN2+O2 plasma

Plasma Chemistry in OzonizersPlasma Chemistry in Ozonizers

Dry Air O2 N2

e - e -

O N2 N O2

O3 NO

O2 N O2

O3

N

3

NO2

O2 O3

NO

N

NO2 O3

N2O

NO3 N

N2O4

NO2

NO2

N2O5

NO3

Primary electron-driven chemical reactions leading to the formation of N2O5 and N2O in a dry air plasma

Plasma emission diagnostics role of N2Plasma emission diagnostics role of N2

Dry Air O2 N2

e - e -

O N2 N O2

O3 NO

O2 N O2

O3

O

N

ON

NO2

O2O3

N

NO N

NO2 O3

N2O

NO3 N

N2O4

NO2

NO2

N2O5

NO3

ONbullWith N2 present ndash less oxygen atoms are formed However the difference in intensity is

very small

Modeling of plasma chemistry incl the NxOy chemistry up to N2O5 for different Oxygen Nitrogen mixtures varying power deposition scenarios

and initial ozone background concentrations (up to 15) previously done

The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation

The role of N2 must be related to its by-products reacting on the surface of the electrodeThe role of N2 must be related to its by-products reacting on the surface of the electrode

The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established

Ab 8 t f O

The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established

Ab 8 t f OAbove 8 wt of O3

1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)

Above 8 wt of O3

1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)case without pampp)

2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of the

case without pampp)

2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of thethem A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface

them A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface

The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation

Three possibilities have to be considered for the oxygen-fedozone generator

Three possibilities have to be considered for the oxygen-fedozone generatorozone generator

bull Excited N2 molecules lead to an increased O2 dissociation in

ozone generator

bull Excited N2 molecules lead to an increased O2 dissociation in2 2such case an increased efficiency is correlated to the N2admixture

2 2such case an increased efficiency is correlated to the N2admixture

bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial

bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial

bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2

bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2g p g 3 pp y 2g p g 3 pp y 2

Effect of methane on ozone efficiency and specific powerEffect of methane on ozone efficiency and specific power

Effect of Methane on Ozone Content in Outlet Gas and on Specific Power Pure O2

13 12

10

11

12

t 8

10

8

9

10

ne c

onte

nt w

t

6

8

ecifi

c po

wer

kW

hlb

5

6

7

Ozo

n

2

4 Spe

400E+00 20E+03 40E+03 60E+03 80E+03 10E+04 12E+04

Methane in feedgas ppm

0

Ozone content in the outlet gas Specif ic pow er of the ozone generatorg p p g

Effects of N2 and CH4Effects of N2 and CH4

Pi t f h t lli N O t tPicture of an amorphous-crystalline N2O5 structurecaptured at the Orlando Skylake water plant in 2006

Plasma Chemistry with CH4 Impurities

OxygenO2 N2

e - e -

CHO N2

NO2

O NO

O2 N O2 O3

NOH

CH4e-

O3 NO

NO2

O2O3NO N

NO2 O

NO2

NO2

N2ONO3

N

O3

NO2

NO

HNO3

N2O4

N2O5

NO2

NO3

N2O5

Effect of methane on the electrode surfaces

a) b)

Inlet Outlet Outlet

) d)

I l t I l t

c) d)

Electrode of the ozone generator afterseveral hours in CH8O2 and up to 2 wt of methane (a b c)

Inlet Inlet

three hours in CH8O2+traces of N2 and up to 1 wt of methane (d) Visible change of discharge character at about 13 length of electrode (a d)

Kinetics of CHx Conversion without N2

conversion by collisions

O2 + CHx 12wt O3 + CO2 +H2O

deposition vaporizationby sputtering

ibl b l 1000 CHreversible process below 1000ppm CH4

Effect of water on electrode surface with N2

Inlet

OutletOutlet

Electrode of the ozone generator after several hours in H OO N

Inlet

Electrode of the ozone generator after several hours in H2OO2N2

Effect of water on electrode surface

Long term effect (800 hrs) of H2OO2N2

Kinetics of CHx Conversion with N2

conversion by collisionsHNO3 formation

O2 + N2 +CHx 12wtO2 + CO2 +H2O + HNO3

deposition vaporizationby sputtering

H2O + HNO3

by sputtering

irreversible process above a N2 threshold () ltlt 1000ppm N2

sticky deposit

p 2 ( ) pp 2 any CH4 concentration (60ppm)

Plasma Chemistry with CH4 ImpuritiesPlasma Chemistry with CH4 Impurities4

bull Formation of NO and NO2 depends on O3 N2 and gas temperature Conclusion N2 admixture is the key factor

SummarySummaryyyThe mechanisms of formed NOx by-products follows the sameThe mechanisms of formed NOx by-products follows the sameprinciples as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentration

principles as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentrationozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)

ozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)g p ( g p )

The conversion of methane to OH and H2O is found to depend on

g p ( g p )

The conversion of methane to OH and H2O is found to depend ondissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)

dissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)discharge gap)discharge gap)

How do you optimize an ozone generatorg

Scientific ApproachScientific ApproachTheoretical Experimental

pppp

c [wt]

f [Hz]

c [wt]

f [Hz]

[kW]UUUβ1

1Cf4αPn

1iiminpeakimin

iiD

q [kWm2]q [kWm2]

150

180

][V]voltagepeakUpeak

[]cylinder perslicesofamountnsliceii

whereth

09 00

30

60

90

120

effic

ienc

y [

][0tdj t bl[F]sliceisdielectricofecapacitancC

[Hz]frequencyf[V]sliceivoltageminimumiUmin

thiD

th

10

28

46

64

82

39

107

176

244 power density

[kWm2]

ozone conc [wt][]CCβ

][0parameteradjustableα

iDiGi

Impact of Power Inductionp

350

400

wer

200

250

300

App

lied

Pow

Arr C 2Arr D +0

Arr E +45Arr F +7

Arr G +3

5 0

100

150

Frac

tion

of

1 2 3 4

ReferenceArr B unstable

Arr C -2

00

50

4Position (1inlet 4outlet)

Experimental Test Rigp g

Experimental Test Rigp g

Outer grounded electrode (left picture) and the dielectric covered inner electrodes (right) d e ect c cove ed e e ect odes ( g t)

Reference (Traditional) Arrangement

Inlet OutletGas flow direction

Optimized Arrangement

Inlet OutletGas flow direction

Intelligent Gap System (IGS)g p y ( )

Molecular Oxygen (O2) Ozone (O3)

O2 O3

yg ( 2) ( 3)

Particle Size SynthesisParticle Size SynthesisByBy--Products Cluster FormationProducts Cluster Formationyy

high diffusion and deposition to surfaces

low diffusion rate good transport

high sedimentation on the structurehigh sedimentation on the structure

Degreacutemont Technologies ndash OzoniaIntelligent Gap SystemIntelligent Gap System

G Vezzuacute JL Lopez A Freilich and K Becker Optimizationof Large-Scale Ozone Generators IEEE Transactions onPlasma Science Vol 37 No 6 p 890-896 (2009)

ConclusionsConclusionsConclusionsConclusionsFundamentals of ozone synthesis in a DBD plasmay p

ndash Highly filamented DBD discharges are best-suitedfor the production of ozone concentrations in therange of 6 to 14 wtrange of 6 to 14 wt

ndash The preferred characteristic of the microdischargesare Townsend-like at reduced electric fields Enaround 190 Townsend

ndash Detrimental side-effects induced by by-productscan be avoided by a proper design of the electrodecan be avoided by a proper design of the electrodearrangement The phenomenon is related to thediffusion rates of formed by-product clusters

ConclusionsConclusionsConclusionsConclusionsBenefits from DBD microplasma tailoring

ndash Reduced power consumption of up to 10 improvement

ndash Increased ozone concentrations of up to 14 now achievable

ndash Improved neutralization and conditioning of detrimental by-products

ndash Reduced system capital and operational cost

New technologies to improve ozone p

generatorg

HV Pulsed Power SwitchingHV Pulsed Power Switching

Microchannel Generation of Ozone

Channel ArrayChannel Array

Microchannel

330 microm 230 microm

Some Cap-DBD Devices Operating in Air

Increase of 60 of

Spacing 225 μmof 60 of plasma

No space

Cap‐DBD ozone generation

bull Ozone concentration is evaluated via Eco S d l UV 100 O A l (0 01Sensors model UV-100 Ozone Analyzer (001 ndash 900 ppm wiht an accuracy of plusmn2)

bull Three reactors 6 tubings 6rdquo with spacings of 0 μm 225 μm and 500 μm running at 3 kV μ μ μ g

SpacingOzone Concentration

3 kV rms 4 kV rms3 kV rms 4 kV rms

0 μm 660 ppm

225 μm 550 ppm

For a device of such small scale these ozone levels are promising

500 μm 380 ppm

J Mahoney W Zhu VS Johnson KH Becker and JL Lopez Electrical and optical emissionmeasurements of a capillary dielectric barrier discharge European Physics Journal D Vol 60 441-447(2010)

QuestionsQuestions

Thank YouFor more informationProf Jose L Lopez PhD

Thank YouFor more informationDepartment of Physics

Telephone (973) 761-9057Email joselopez1shuedu

Website wwwshueduacademicsartsciphysicsWebsite wwwshueduacademicsartsciphysics

Page 33: Dielectric Barrier Discharge (DBD) & Progress in Large ...bonitz/si12/talks/august_8/lopez_si12.pdf · Dielectric Barrier Discharge (DBD) & Progress in Large-Scale Ozone Generation

Numerical Results of Microdischarge Formationin Dielectric Barrier Discharges

Local Field Collapse in Area Defined by Surface Discharge

ne=109cm-3 ne=1014 cm-3

Gap

Principals of DBD MicroplasmasPrincipals of DBD MicroplasmasPrincipals of DBD MicroplasmasPrincipals of DBD Microplasmas

C C-- - --- - - CG

CD

-- - - CG

CD

Principals of DBD MicroplasmasPrincipals of DBD MicroplasmasPrincipals of DBD MicroplasmasPrincipals of DBD Microplasmas

Dielectric Barrier Discharge (DBD)Dielectric Barrier Discharge (DBD)Electric Field

B kdBreakdown

Electrons amp Ions Discharge Physics

Excited SpeciesPlasma Chemistry

Chemical Reactions

OzoneGeneration

SurfaceTreatment

PollutionControl

ExcimerFormation CO2 Lasers Hydrogenation

of CO2

Excimer Lamps Plasma Displays

How A Plasma Display Works

How A Plasma Display Work

Plasma Display TelevisionsPlasma Display Televisions

Ozone Generator

3 O 2 O

Dielectric Barrier Discharge

3 O2 2 O3

OO22 OO33++OO22Ondash ndashO3O2

O2O2

Ondash ndash

endash O2Ondash ndash O2endash

O3

O3O2O2 O2

HeatHeatHeatHeat

Properties of Ozone (O3)

T i t i f f Tri-atomic form of oxygen

Most powerful commercial oxidizing agent

Unstable - must be generated and used onsite

Limited solubility in water but more so than oxygenLimited solubility in water but more so than oxygen

Leaves a dissolved residual which ultimately converts back to oxygenconverts back to oxygen

Discharge Tubes in Ozone GeneratorsDischarge Tubes in Ozone Generators

Traditional

Ozone Generator

with Glass Tubes

Generation of OzoneGeneration of Ozone

Generation of OzoneAdvantages of Enamel Dielectrics

Proven Patented Designbull Simplicity

Si l Di l i Cbull Single Dielectric Componentndash Reduced number of Dielectrics

bull Safety ndash Lower operating voltage

(lt 4000 V)bull Reliabilty

ndash Fused Dielectrics ensure continuous production

bull Lowest Power Consumption Operational Savingsndash Operational Savings

Modern Ozone GeneratorModern Ozone Generator

Ozonia Advanced Technology Ozone GeneratorOzone Generator

Generation of OzoneGeneration of Ozone

Generation of Ozone

Power Supply UnitPower Supply Unit

IGBT Inverter CircuitMain Circuit Breaker

HV 480 Volts60 Hz3 Phase Supply

C I

450KVAPow er to

GeneratorFILTER

CONVERTER INVERTERTRANSFORMER

C I450KVA Power Stage

CONTACTOR

bull Latest in Power Semiconductor Technology Modular Design

bull Utilizes IGBTrsquos (Insulated Gate Bi‐Polar Transistors) Converter and Inverter Components

Ozone Water Treatment

B bbl Diff iB bbl Diff iBubble DiffusionBubble Diffusion

Easy to use

Low energy usage Low energy usage

Mass transfer efficiencies to gt 90

Ozone Process Flow DiagramOzone Process Flow DiagramVent to

Atmosphere

O OOxygen

Off-Gas Blower

Ozone Destruct Unit

10 12

O3O2

LOX

10-12 O3

Ozone Generators

Ozone Contact ChamberLOX T k Generators Chamber

VaporizersLOX Tank

Municipal Ozone Installations

Ozonia Installations Ozone Plant Size [lbday] Start-Up DateKey Ozonia Installations (Partial List)

Los Angeles CA 10000 1986Fairfax VA ndash Corbalis 9000 2003MWD CA ndash Mills 9 000 2003

Ozonia Installations Ozone Plant Size [lbday] Start Up Date

MWD CA Mills 9000 2003Fairfax Co VA ndash Griffith 9000 2004MWD CA ndash Jensen 18750 2005Indianapolis IN ndash Belmont AWT 12000 2007I di li IN 12 000 2007Indianapolis IN ndash Southport AWT 12000 2007MWD CA ndash Diemer 13400 2008MWD CA ndash Weymouth 13400 2009

Ozonia North America - Potable Water SummaryTotal Number of Installations 90Total Installed Production gt 265000 lbsdayTotal Installed Production 265000 lbsday

Revision -B

Ozone Water TreatmentOzone Water Treatment

MWD Mills WTP - California

3 3 000 lbsda of o one3 3 000 lbsda of o one3 x 3000 lbsday of ozone3 x 3000 lbsday of ozone

Ozone Water TreatmentOzone Water TreatmentOzone Ozone -- How it worksHow it works

OxidantOxidant DisinfectantDisinfectant

bullbull Breaks double carbon Breaks double carbon bondsbonds

bullbull Kills by cell lysing or Kills by cell lysing or causing the cell wall tocausing the cell wall tobondsbonds

bullbull Creates OHCreates OHbullbull radicals radicals which break higher carbon which break higher carbon

causing the cell wall to causing the cell wall to rupture rupture

bullbull AttacksAttacks allall bacteriabacteriabondsbondsbullbull Increased temp and pH Increased temp and pH

accelerates Oaccelerates O33

Attacks Attacks allall bacteria bacteria virus cysts and spores virus cysts and spores in varying degreesin varying degreesaccelerates Oaccelerates O33

decomposition to OHdecomposition to OHbullbull

Micro-organism DNA

Capsule AdenineAdenine

Cell wall ThymineThymine

CytosineCytosine

GuanineGuanine

NuclearmaterialCellmembrane

material

Typical Bacterium DNA

Microbial Growth at Various Ozone ConcentrationsConcentrations

Growth likely

Growth possibleGrowth possible

NO GROWTH

0004 0008 0012 0016 0020

Ozone concentration (mgl)Ozone concentration (mgl)

Typical Water Treatment UsageTypical Water Treatment Usage

Application O3 mgl Contact timeUltra Pure Water 005 - 025 sec ndash min

Water bottling 04 ndash 10 5 ndash 10 min

Swimming pools ampspas

01 ndash 075 4 minutes

Potable taste amp odor 15 ndash 50 5 ndash 10 mindisinfection

Microfloculation 10 ndash 30 5 ndash 10 min

Lignin amp tammin 3 0 10 0 10 30 minLignin amp tamminremoval

30 ndash 100 10 ndash 30 min

Municipal wastewater 50 ndash 150+ 15 ndash 30 min

Ozone Water TreatmentOzone Water TreatmentOzone Ozone ndashndash Municipal ApplicationsMunicipal Applications

bullbull Taste and OdorTaste and Odor

bullbull Color RemovalColor Removal

bullbull Disinfection Without Trihalomethanes (THMs)Disinfection Without Trihalomethanes (THMs)

bullbull Improved Filtration Efficiency and FlocculationImproved Filtration Efficiency and Flocculation

bullbull Cryptosporidium DeactivationCryptosporidium Deactivation

bullbull Giardia amp Virus InactivationGiardia amp Virus Inactivation

bullbull Oxidation Oxidation -- Organics Fe amp MnOrganics Fe amp Mn

bullbull Wastewater disinfectionWastewater disinfection

bullbull BOD COD and TOC reductionBOD COD and TOC reduction

Applications of Ozone

Wastewater Treatmentbull Disinfection of Secondary and Tertiary Effluentsbull Color Reductionbull Color Reductionbull TOC Oxidation (Industrial)bull Oxidation of Odor Causing Compoundsbull Oxidation of Endocrine Disruptors (EDCrsquos) and p ( )

Pharmaceutically Active Compounds (PACrsquos)

Applications of Ozone

What are Endocrine Disruptors (EDCrsquos) and What are Endocrine Disruptors (EDCrsquos) and Ph ti ll A ti C d (PACrsquo )Ph ti ll A ti C d (PACrsquo )Pharmaceutically Active Compounds (PACrsquos)Pharmaceutically Active Compounds (PACrsquos)

bullbull EDCrsquosEDCrsquos andand PACrsquosPACrsquos areare NaturallyNaturally andand SyntheticSyntheticdd th tth t ff tff t thth b lb l llcompoundscompounds thatthat maymay affectaffect thethe balancebalance oror normalnormal

functionsfunctions inin animalsanimals andand humanshumans

What can EDCrsquos and PACrsquos doWhat can EDCrsquos and PACrsquos do

bullbull Even in very small concentrations these compounds Even in very small concentrations these compounds y py pcan can disruptdisrupt normal bodily functionsnormal bodily functions

bullbull ManMan--made chemicals can trick the bodies endocrine made chemicals can trick the bodies endocrine system system

Applications of Ozone

Examples of Endocrine Disruptors1000rsquos of compounds that may be Investigated as EDCs ndash Some examples are

bullbull Synthetic HormonesSynthetic Hormonesbullbull Naturally Occurring Estrogens Naturally Occurring Estrogens

Health and Beauty AidsHealth and Beauty Aidsbullbull Health and Beauty AidsHealth and Beauty Aidsbullbull SolventsSolventsbullbull PesticidesPesticidesbullbull SurfactantsSurfactantsbullbull PlasticsPlastics

F i idF i idbullbull FungicidesFungicides

Ozone Water TreatmentOzone Water Treatment

Ozone Ozone -- Industrial ApplicationsIndustrial Applications-- Ultrapure Water for Pharmaceutical ApplicationsUltrapure Water for Pharmaceutical Applications

-- Wastewater disinfection color removalWastewater disinfection color removal

-- Soil and Groundwater Remediation Soil and Groundwater Remediation

-- Cooling Tower Water TreatmentCooling Tower Water Treatment

-- Food ProcessingFood Processing

-- Aquaculture AquariumsAquaculture AquariumsAquaculture AquariumsAquaculture Aquariums

-- Beverage ApplicationsBeverage Applications

P l amp P Bl hiP l amp P Bl hi-- Pulp amp Paper BleachingPulp amp Paper Bleaching

High Purity OzonationHigh Purity Ozonation

Microchip manufacturingMicrochip manufacturing

What are the current issues in large-scale gozone generationg

Experimental Setup

Front view of the two units after the redesign and reworking ofthe gas water and instruments connectionsthe gas water and instruments connections

Experimental Setup

Top view of the twoexperimental unitsexperimental unitsSpectroscope (notshown) is to the left ofthe DBD The units weredifferent with respect todifferent with respect totheir electrodes onehad only the electrodecoated with thedielectric (ldquosingle-dielectric ( single-coatedrdquo) the other onehad the electrode andthe anode coated withthe dielectric (ldquodouble-the dielectric ( double-coatedrdquo)

Basics Generation of OzoneBasics Generation of Ozone

SpectroscopyPlasma

Plasma Absorption SpectroscopyPlasma Absorption Spectroscopy

Infrared Absorption SpectroscopyInfrared Absorption Spectroscopy

IR spectra in pure oxygen (black curve) and at approximately 10wt N2 admixture (red line) N2O5 peaks appear at124 1 d 1 2 11245 cm-1 and at 1725 cm-1

Infrared Absorption SpectroscopyInfrared Absorption Spectroscopy

IR spectra of several methane variations The green curve envelopes all of the methane peaks at 1325 cm-1recorded at smaller methane admixtures Simultaneously the N2O5 peaks disappear as the methane peaks appear

N2O5 FormationN2O5 Formation2 52 5p=2 bara cwt=20degC q=35kWm2 f=1450Hz

45N2O5 AT95

30

35

40

N

2 B

lend

ing

N2O AT95N2O5 IGSN2O IGSN2O5 LGN2O LG

1 5

20

25

nt [p

pmV]

3

wt

05

10

15

NO

x co

nten

005 7 9 11 13 15 17

ozone conc [wt]

Amount of formed N2O5 and N2O as a function of ozone concentration at 3 wt of nitrogen admixture and fori l dvarious electrode arrangements

Plasma Emission SpectroscopyPlasma Emission Spectroscopyp pyp py

Relative Emissions of the Ozonizer plasmaRelative Emissions of the Ozonizer plasma

Region 300- 850 nm from individual (calibrated) regions (smoothed by PeakFit) Single-coated ozone generator Inlet side

3 5E+06

30E+06

35E+06

7 9

20E+06

25E+06

nten

sity

au

2

311 12

10E+06

15E+06

In 4

5

6 8 10

14

15

16

17

00E+00

50E+05

280 300 320 340 360 380 400 420 440 460 480 500 520 540 560 580 600 620 640 660 680 700 720 740 760 780 800 820 840 860

Wavelength nm

1 13

Wavelength nm

Absolute Emission of the DBD PlasmaAbsolute Emission of the DBD Plasma

Intensities in (O2+3 wtN2) plasma

1 20E+04

100E+04

120E+04

600E+03

800E+03

nten

sity

(au

)

200E+03

400E+03

In

O(777)

000E+00200 250 300 350 400 450 500 550 600 650 700 750 800 850

Wavelength nm

Intensities in 3 wtN2+O2 plasmaIntensities in 3 wtN2+O2 plasma

Plasma Chemistry in OzonizersPlasma Chemistry in Ozonizers

Dry Air O2 N2

e - e -

O N2 N O2

O3 NO

O2 N O2

O3

N

3

NO2

O2 O3

NO

N

NO2 O3

N2O

NO3 N

N2O4

NO2

NO2

N2O5

NO3

Primary electron-driven chemical reactions leading to the formation of N2O5 and N2O in a dry air plasma

Plasma emission diagnostics role of N2Plasma emission diagnostics role of N2

Dry Air O2 N2

e - e -

O N2 N O2

O3 NO

O2 N O2

O3

O

N

ON

NO2

O2O3

N

NO N

NO2 O3

N2O

NO3 N

N2O4

NO2

NO2

N2O5

NO3

ONbullWith N2 present ndash less oxygen atoms are formed However the difference in intensity is

very small

Modeling of plasma chemistry incl the NxOy chemistry up to N2O5 for different Oxygen Nitrogen mixtures varying power deposition scenarios

and initial ozone background concentrations (up to 15) previously done

The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation

The role of N2 must be related to its by-products reacting on the surface of the electrodeThe role of N2 must be related to its by-products reacting on the surface of the electrode

The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established

Ab 8 t f O

The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established

Ab 8 t f OAbove 8 wt of O3

1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)

Above 8 wt of O3

1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)case without pampp)

2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of the

case without pampp)

2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of thethem A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface

them A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface

The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation

Three possibilities have to be considered for the oxygen-fedozone generator

Three possibilities have to be considered for the oxygen-fedozone generatorozone generator

bull Excited N2 molecules lead to an increased O2 dissociation in

ozone generator

bull Excited N2 molecules lead to an increased O2 dissociation in2 2such case an increased efficiency is correlated to the N2admixture

2 2such case an increased efficiency is correlated to the N2admixture

bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial

bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial

bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2

bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2g p g 3 pp y 2g p g 3 pp y 2

Effect of methane on ozone efficiency and specific powerEffect of methane on ozone efficiency and specific power

Effect of Methane on Ozone Content in Outlet Gas and on Specific Power Pure O2

13 12

10

11

12

t 8

10

8

9

10

ne c

onte

nt w

t

6

8

ecifi

c po

wer

kW

hlb

5

6

7

Ozo

n

2

4 Spe

400E+00 20E+03 40E+03 60E+03 80E+03 10E+04 12E+04

Methane in feedgas ppm

0

Ozone content in the outlet gas Specif ic pow er of the ozone generatorg p p g

Effects of N2 and CH4Effects of N2 and CH4

Pi t f h t lli N O t tPicture of an amorphous-crystalline N2O5 structurecaptured at the Orlando Skylake water plant in 2006

Plasma Chemistry with CH4 Impurities

OxygenO2 N2

e - e -

CHO N2

NO2

O NO

O2 N O2 O3

NOH

CH4e-

O3 NO

NO2

O2O3NO N

NO2 O

NO2

NO2

N2ONO3

N

O3

NO2

NO

HNO3

N2O4

N2O5

NO2

NO3

N2O5

Effect of methane on the electrode surfaces

a) b)

Inlet Outlet Outlet

) d)

I l t I l t

c) d)

Electrode of the ozone generator afterseveral hours in CH8O2 and up to 2 wt of methane (a b c)

Inlet Inlet

three hours in CH8O2+traces of N2 and up to 1 wt of methane (d) Visible change of discharge character at about 13 length of electrode (a d)

Kinetics of CHx Conversion without N2

conversion by collisions

O2 + CHx 12wt O3 + CO2 +H2O

deposition vaporizationby sputtering

ibl b l 1000 CHreversible process below 1000ppm CH4

Effect of water on electrode surface with N2

Inlet

OutletOutlet

Electrode of the ozone generator after several hours in H OO N

Inlet

Electrode of the ozone generator after several hours in H2OO2N2

Effect of water on electrode surface

Long term effect (800 hrs) of H2OO2N2

Kinetics of CHx Conversion with N2

conversion by collisionsHNO3 formation

O2 + N2 +CHx 12wtO2 + CO2 +H2O + HNO3

deposition vaporizationby sputtering

H2O + HNO3

by sputtering

irreversible process above a N2 threshold () ltlt 1000ppm N2

sticky deposit

p 2 ( ) pp 2 any CH4 concentration (60ppm)

Plasma Chemistry with CH4 ImpuritiesPlasma Chemistry with CH4 Impurities4

bull Formation of NO and NO2 depends on O3 N2 and gas temperature Conclusion N2 admixture is the key factor

SummarySummaryyyThe mechanisms of formed NOx by-products follows the sameThe mechanisms of formed NOx by-products follows the sameprinciples as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentration

principles as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentrationozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)

ozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)g p ( g p )

The conversion of methane to OH and H2O is found to depend on

g p ( g p )

The conversion of methane to OH and H2O is found to depend ondissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)

dissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)discharge gap)discharge gap)

How do you optimize an ozone generatorg

Scientific ApproachScientific ApproachTheoretical Experimental

pppp

c [wt]

f [Hz]

c [wt]

f [Hz]

[kW]UUUβ1

1Cf4αPn

1iiminpeakimin

iiD

q [kWm2]q [kWm2]

150

180

][V]voltagepeakUpeak

[]cylinder perslicesofamountnsliceii

whereth

09 00

30

60

90

120

effic

ienc

y [

][0tdj t bl[F]sliceisdielectricofecapacitancC

[Hz]frequencyf[V]sliceivoltageminimumiUmin

thiD

th

10

28

46

64

82

39

107

176

244 power density

[kWm2]

ozone conc [wt][]CCβ

][0parameteradjustableα

iDiGi

Impact of Power Inductionp

350

400

wer

200

250

300

App

lied

Pow

Arr C 2Arr D +0

Arr E +45Arr F +7

Arr G +3

5 0

100

150

Frac

tion

of

1 2 3 4

ReferenceArr B unstable

Arr C -2

00

50

4Position (1inlet 4outlet)

Experimental Test Rigp g

Experimental Test Rigp g

Outer grounded electrode (left picture) and the dielectric covered inner electrodes (right) d e ect c cove ed e e ect odes ( g t)

Reference (Traditional) Arrangement

Inlet OutletGas flow direction

Optimized Arrangement

Inlet OutletGas flow direction

Intelligent Gap System (IGS)g p y ( )

Molecular Oxygen (O2) Ozone (O3)

O2 O3

yg ( 2) ( 3)

Particle Size SynthesisParticle Size SynthesisByBy--Products Cluster FormationProducts Cluster Formationyy

high diffusion and deposition to surfaces

low diffusion rate good transport

high sedimentation on the structurehigh sedimentation on the structure

Degreacutemont Technologies ndash OzoniaIntelligent Gap SystemIntelligent Gap System

G Vezzuacute JL Lopez A Freilich and K Becker Optimizationof Large-Scale Ozone Generators IEEE Transactions onPlasma Science Vol 37 No 6 p 890-896 (2009)

ConclusionsConclusionsConclusionsConclusionsFundamentals of ozone synthesis in a DBD plasmay p

ndash Highly filamented DBD discharges are best-suitedfor the production of ozone concentrations in therange of 6 to 14 wtrange of 6 to 14 wt

ndash The preferred characteristic of the microdischargesare Townsend-like at reduced electric fields Enaround 190 Townsend

ndash Detrimental side-effects induced by by-productscan be avoided by a proper design of the electrodecan be avoided by a proper design of the electrodearrangement The phenomenon is related to thediffusion rates of formed by-product clusters

ConclusionsConclusionsConclusionsConclusionsBenefits from DBD microplasma tailoring

ndash Reduced power consumption of up to 10 improvement

ndash Increased ozone concentrations of up to 14 now achievable

ndash Improved neutralization and conditioning of detrimental by-products

ndash Reduced system capital and operational cost

New technologies to improve ozone p

generatorg

HV Pulsed Power SwitchingHV Pulsed Power Switching

Microchannel Generation of Ozone

Channel ArrayChannel Array

Microchannel

330 microm 230 microm

Some Cap-DBD Devices Operating in Air

Increase of 60 of

Spacing 225 μmof 60 of plasma

No space

Cap‐DBD ozone generation

bull Ozone concentration is evaluated via Eco S d l UV 100 O A l (0 01Sensors model UV-100 Ozone Analyzer (001 ndash 900 ppm wiht an accuracy of plusmn2)

bull Three reactors 6 tubings 6rdquo with spacings of 0 μm 225 μm and 500 μm running at 3 kV μ μ μ g

SpacingOzone Concentration

3 kV rms 4 kV rms3 kV rms 4 kV rms

0 μm 660 ppm

225 μm 550 ppm

For a device of such small scale these ozone levels are promising

500 μm 380 ppm

J Mahoney W Zhu VS Johnson KH Becker and JL Lopez Electrical and optical emissionmeasurements of a capillary dielectric barrier discharge European Physics Journal D Vol 60 441-447(2010)

QuestionsQuestions

Thank YouFor more informationProf Jose L Lopez PhD

Thank YouFor more informationDepartment of Physics

Telephone (973) 761-9057Email joselopez1shuedu

Website wwwshueduacademicsartsciphysicsWebsite wwwshueduacademicsartsciphysics

Page 34: Dielectric Barrier Discharge (DBD) & Progress in Large ...bonitz/si12/talks/august_8/lopez_si12.pdf · Dielectric Barrier Discharge (DBD) & Progress in Large-Scale Ozone Generation

Principals of DBD MicroplasmasPrincipals of DBD MicroplasmasPrincipals of DBD MicroplasmasPrincipals of DBD Microplasmas

C C-- - --- - - CG

CD

-- - - CG

CD

Principals of DBD MicroplasmasPrincipals of DBD MicroplasmasPrincipals of DBD MicroplasmasPrincipals of DBD Microplasmas

Dielectric Barrier Discharge (DBD)Dielectric Barrier Discharge (DBD)Electric Field

B kdBreakdown

Electrons amp Ions Discharge Physics

Excited SpeciesPlasma Chemistry

Chemical Reactions

OzoneGeneration

SurfaceTreatment

PollutionControl

ExcimerFormation CO2 Lasers Hydrogenation

of CO2

Excimer Lamps Plasma Displays

How A Plasma Display Works

How A Plasma Display Work

Plasma Display TelevisionsPlasma Display Televisions

Ozone Generator

3 O 2 O

Dielectric Barrier Discharge

3 O2 2 O3

OO22 OO33++OO22Ondash ndashO3O2

O2O2

Ondash ndash

endash O2Ondash ndash O2endash

O3

O3O2O2 O2

HeatHeatHeatHeat

Properties of Ozone (O3)

T i t i f f Tri-atomic form of oxygen

Most powerful commercial oxidizing agent

Unstable - must be generated and used onsite

Limited solubility in water but more so than oxygenLimited solubility in water but more so than oxygen

Leaves a dissolved residual which ultimately converts back to oxygenconverts back to oxygen

Discharge Tubes in Ozone GeneratorsDischarge Tubes in Ozone Generators

Traditional

Ozone Generator

with Glass Tubes

Generation of OzoneGeneration of Ozone

Generation of OzoneAdvantages of Enamel Dielectrics

Proven Patented Designbull Simplicity

Si l Di l i Cbull Single Dielectric Componentndash Reduced number of Dielectrics

bull Safety ndash Lower operating voltage

(lt 4000 V)bull Reliabilty

ndash Fused Dielectrics ensure continuous production

bull Lowest Power Consumption Operational Savingsndash Operational Savings

Modern Ozone GeneratorModern Ozone Generator

Ozonia Advanced Technology Ozone GeneratorOzone Generator

Generation of OzoneGeneration of Ozone

Generation of Ozone

Power Supply UnitPower Supply Unit

IGBT Inverter CircuitMain Circuit Breaker

HV 480 Volts60 Hz3 Phase Supply

C I

450KVAPow er to

GeneratorFILTER

CONVERTER INVERTERTRANSFORMER

C I450KVA Power Stage

CONTACTOR

bull Latest in Power Semiconductor Technology Modular Design

bull Utilizes IGBTrsquos (Insulated Gate Bi‐Polar Transistors) Converter and Inverter Components

Ozone Water Treatment

B bbl Diff iB bbl Diff iBubble DiffusionBubble Diffusion

Easy to use

Low energy usage Low energy usage

Mass transfer efficiencies to gt 90

Ozone Process Flow DiagramOzone Process Flow DiagramVent to

Atmosphere

O OOxygen

Off-Gas Blower

Ozone Destruct Unit

10 12

O3O2

LOX

10-12 O3

Ozone Generators

Ozone Contact ChamberLOX T k Generators Chamber

VaporizersLOX Tank

Municipal Ozone Installations

Ozonia Installations Ozone Plant Size [lbday] Start-Up DateKey Ozonia Installations (Partial List)

Los Angeles CA 10000 1986Fairfax VA ndash Corbalis 9000 2003MWD CA ndash Mills 9 000 2003

Ozonia Installations Ozone Plant Size [lbday] Start Up Date

MWD CA Mills 9000 2003Fairfax Co VA ndash Griffith 9000 2004MWD CA ndash Jensen 18750 2005Indianapolis IN ndash Belmont AWT 12000 2007I di li IN 12 000 2007Indianapolis IN ndash Southport AWT 12000 2007MWD CA ndash Diemer 13400 2008MWD CA ndash Weymouth 13400 2009

Ozonia North America - Potable Water SummaryTotal Number of Installations 90Total Installed Production gt 265000 lbsdayTotal Installed Production 265000 lbsday

Revision -B

Ozone Water TreatmentOzone Water Treatment

MWD Mills WTP - California

3 3 000 lbsda of o one3 3 000 lbsda of o one3 x 3000 lbsday of ozone3 x 3000 lbsday of ozone

Ozone Water TreatmentOzone Water TreatmentOzone Ozone -- How it worksHow it works

OxidantOxidant DisinfectantDisinfectant

bullbull Breaks double carbon Breaks double carbon bondsbonds

bullbull Kills by cell lysing or Kills by cell lysing or causing the cell wall tocausing the cell wall tobondsbonds

bullbull Creates OHCreates OHbullbull radicals radicals which break higher carbon which break higher carbon

causing the cell wall to causing the cell wall to rupture rupture

bullbull AttacksAttacks allall bacteriabacteriabondsbondsbullbull Increased temp and pH Increased temp and pH

accelerates Oaccelerates O33

Attacks Attacks allall bacteria bacteria virus cysts and spores virus cysts and spores in varying degreesin varying degreesaccelerates Oaccelerates O33

decomposition to OHdecomposition to OHbullbull

Micro-organism DNA

Capsule AdenineAdenine

Cell wall ThymineThymine

CytosineCytosine

GuanineGuanine

NuclearmaterialCellmembrane

material

Typical Bacterium DNA

Microbial Growth at Various Ozone ConcentrationsConcentrations

Growth likely

Growth possibleGrowth possible

NO GROWTH

0004 0008 0012 0016 0020

Ozone concentration (mgl)Ozone concentration (mgl)

Typical Water Treatment UsageTypical Water Treatment Usage

Application O3 mgl Contact timeUltra Pure Water 005 - 025 sec ndash min

Water bottling 04 ndash 10 5 ndash 10 min

Swimming pools ampspas

01 ndash 075 4 minutes

Potable taste amp odor 15 ndash 50 5 ndash 10 mindisinfection

Microfloculation 10 ndash 30 5 ndash 10 min

Lignin amp tammin 3 0 10 0 10 30 minLignin amp tamminremoval

30 ndash 100 10 ndash 30 min

Municipal wastewater 50 ndash 150+ 15 ndash 30 min

Ozone Water TreatmentOzone Water TreatmentOzone Ozone ndashndash Municipal ApplicationsMunicipal Applications

bullbull Taste and OdorTaste and Odor

bullbull Color RemovalColor Removal

bullbull Disinfection Without Trihalomethanes (THMs)Disinfection Without Trihalomethanes (THMs)

bullbull Improved Filtration Efficiency and FlocculationImproved Filtration Efficiency and Flocculation

bullbull Cryptosporidium DeactivationCryptosporidium Deactivation

bullbull Giardia amp Virus InactivationGiardia amp Virus Inactivation

bullbull Oxidation Oxidation -- Organics Fe amp MnOrganics Fe amp Mn

bullbull Wastewater disinfectionWastewater disinfection

bullbull BOD COD and TOC reductionBOD COD and TOC reduction

Applications of Ozone

Wastewater Treatmentbull Disinfection of Secondary and Tertiary Effluentsbull Color Reductionbull Color Reductionbull TOC Oxidation (Industrial)bull Oxidation of Odor Causing Compoundsbull Oxidation of Endocrine Disruptors (EDCrsquos) and p ( )

Pharmaceutically Active Compounds (PACrsquos)

Applications of Ozone

What are Endocrine Disruptors (EDCrsquos) and What are Endocrine Disruptors (EDCrsquos) and Ph ti ll A ti C d (PACrsquo )Ph ti ll A ti C d (PACrsquo )Pharmaceutically Active Compounds (PACrsquos)Pharmaceutically Active Compounds (PACrsquos)

bullbull EDCrsquosEDCrsquos andand PACrsquosPACrsquos areare NaturallyNaturally andand SyntheticSyntheticdd th tth t ff tff t thth b lb l llcompoundscompounds thatthat maymay affectaffect thethe balancebalance oror normalnormal

functionsfunctions inin animalsanimals andand humanshumans

What can EDCrsquos and PACrsquos doWhat can EDCrsquos and PACrsquos do

bullbull Even in very small concentrations these compounds Even in very small concentrations these compounds y py pcan can disruptdisrupt normal bodily functionsnormal bodily functions

bullbull ManMan--made chemicals can trick the bodies endocrine made chemicals can trick the bodies endocrine system system

Applications of Ozone

Examples of Endocrine Disruptors1000rsquos of compounds that may be Investigated as EDCs ndash Some examples are

bullbull Synthetic HormonesSynthetic Hormonesbullbull Naturally Occurring Estrogens Naturally Occurring Estrogens

Health and Beauty AidsHealth and Beauty Aidsbullbull Health and Beauty AidsHealth and Beauty Aidsbullbull SolventsSolventsbullbull PesticidesPesticidesbullbull SurfactantsSurfactantsbullbull PlasticsPlastics

F i idF i idbullbull FungicidesFungicides

Ozone Water TreatmentOzone Water Treatment

Ozone Ozone -- Industrial ApplicationsIndustrial Applications-- Ultrapure Water for Pharmaceutical ApplicationsUltrapure Water for Pharmaceutical Applications

-- Wastewater disinfection color removalWastewater disinfection color removal

-- Soil and Groundwater Remediation Soil and Groundwater Remediation

-- Cooling Tower Water TreatmentCooling Tower Water Treatment

-- Food ProcessingFood Processing

-- Aquaculture AquariumsAquaculture AquariumsAquaculture AquariumsAquaculture Aquariums

-- Beverage ApplicationsBeverage Applications

P l amp P Bl hiP l amp P Bl hi-- Pulp amp Paper BleachingPulp amp Paper Bleaching

High Purity OzonationHigh Purity Ozonation

Microchip manufacturingMicrochip manufacturing

What are the current issues in large-scale gozone generationg

Experimental Setup

Front view of the two units after the redesign and reworking ofthe gas water and instruments connectionsthe gas water and instruments connections

Experimental Setup

Top view of the twoexperimental unitsexperimental unitsSpectroscope (notshown) is to the left ofthe DBD The units weredifferent with respect todifferent with respect totheir electrodes onehad only the electrodecoated with thedielectric (ldquosingle-dielectric ( single-coatedrdquo) the other onehad the electrode andthe anode coated withthe dielectric (ldquodouble-the dielectric ( double-coatedrdquo)

Basics Generation of OzoneBasics Generation of Ozone

SpectroscopyPlasma

Plasma Absorption SpectroscopyPlasma Absorption Spectroscopy

Infrared Absorption SpectroscopyInfrared Absorption Spectroscopy

IR spectra in pure oxygen (black curve) and at approximately 10wt N2 admixture (red line) N2O5 peaks appear at124 1 d 1 2 11245 cm-1 and at 1725 cm-1

Infrared Absorption SpectroscopyInfrared Absorption Spectroscopy

IR spectra of several methane variations The green curve envelopes all of the methane peaks at 1325 cm-1recorded at smaller methane admixtures Simultaneously the N2O5 peaks disappear as the methane peaks appear

N2O5 FormationN2O5 Formation2 52 5p=2 bara cwt=20degC q=35kWm2 f=1450Hz

45N2O5 AT95

30

35

40

N

2 B

lend

ing

N2O AT95N2O5 IGSN2O IGSN2O5 LGN2O LG

1 5

20

25

nt [p

pmV]

3

wt

05

10

15

NO

x co

nten

005 7 9 11 13 15 17

ozone conc [wt]

Amount of formed N2O5 and N2O as a function of ozone concentration at 3 wt of nitrogen admixture and fori l dvarious electrode arrangements

Plasma Emission SpectroscopyPlasma Emission Spectroscopyp pyp py

Relative Emissions of the Ozonizer plasmaRelative Emissions of the Ozonizer plasma

Region 300- 850 nm from individual (calibrated) regions (smoothed by PeakFit) Single-coated ozone generator Inlet side

3 5E+06

30E+06

35E+06

7 9

20E+06

25E+06

nten

sity

au

2

311 12

10E+06

15E+06

In 4

5

6 8 10

14

15

16

17

00E+00

50E+05

280 300 320 340 360 380 400 420 440 460 480 500 520 540 560 580 600 620 640 660 680 700 720 740 760 780 800 820 840 860

Wavelength nm

1 13

Wavelength nm

Absolute Emission of the DBD PlasmaAbsolute Emission of the DBD Plasma

Intensities in (O2+3 wtN2) plasma

1 20E+04

100E+04

120E+04

600E+03

800E+03

nten

sity

(au

)

200E+03

400E+03

In

O(777)

000E+00200 250 300 350 400 450 500 550 600 650 700 750 800 850

Wavelength nm

Intensities in 3 wtN2+O2 plasmaIntensities in 3 wtN2+O2 plasma

Plasma Chemistry in OzonizersPlasma Chemistry in Ozonizers

Dry Air O2 N2

e - e -

O N2 N O2

O3 NO

O2 N O2

O3

N

3

NO2

O2 O3

NO

N

NO2 O3

N2O

NO3 N

N2O4

NO2

NO2

N2O5

NO3

Primary electron-driven chemical reactions leading to the formation of N2O5 and N2O in a dry air plasma

Plasma emission diagnostics role of N2Plasma emission diagnostics role of N2

Dry Air O2 N2

e - e -

O N2 N O2

O3 NO

O2 N O2

O3

O

N

ON

NO2

O2O3

N

NO N

NO2 O3

N2O

NO3 N

N2O4

NO2

NO2

N2O5

NO3

ONbullWith N2 present ndash less oxygen atoms are formed However the difference in intensity is

very small

Modeling of plasma chemistry incl the NxOy chemistry up to N2O5 for different Oxygen Nitrogen mixtures varying power deposition scenarios

and initial ozone background concentrations (up to 15) previously done

The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation

The role of N2 must be related to its by-products reacting on the surface of the electrodeThe role of N2 must be related to its by-products reacting on the surface of the electrode

The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established

Ab 8 t f O

The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established

Ab 8 t f OAbove 8 wt of O3

1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)

Above 8 wt of O3

1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)case without pampp)

2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of the

case without pampp)

2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of thethem A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface

them A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface

The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation

Three possibilities have to be considered for the oxygen-fedozone generator

Three possibilities have to be considered for the oxygen-fedozone generatorozone generator

bull Excited N2 molecules lead to an increased O2 dissociation in

ozone generator

bull Excited N2 molecules lead to an increased O2 dissociation in2 2such case an increased efficiency is correlated to the N2admixture

2 2such case an increased efficiency is correlated to the N2admixture

bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial

bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial

bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2

bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2g p g 3 pp y 2g p g 3 pp y 2

Effect of methane on ozone efficiency and specific powerEffect of methane on ozone efficiency and specific power

Effect of Methane on Ozone Content in Outlet Gas and on Specific Power Pure O2

13 12

10

11

12

t 8

10

8

9

10

ne c

onte

nt w

t

6

8

ecifi

c po

wer

kW

hlb

5

6

7

Ozo

n

2

4 Spe

400E+00 20E+03 40E+03 60E+03 80E+03 10E+04 12E+04

Methane in feedgas ppm

0

Ozone content in the outlet gas Specif ic pow er of the ozone generatorg p p g

Effects of N2 and CH4Effects of N2 and CH4

Pi t f h t lli N O t tPicture of an amorphous-crystalline N2O5 structurecaptured at the Orlando Skylake water plant in 2006

Plasma Chemistry with CH4 Impurities

OxygenO2 N2

e - e -

CHO N2

NO2

O NO

O2 N O2 O3

NOH

CH4e-

O3 NO

NO2

O2O3NO N

NO2 O

NO2

NO2

N2ONO3

N

O3

NO2

NO

HNO3

N2O4

N2O5

NO2

NO3

N2O5

Effect of methane on the electrode surfaces

a) b)

Inlet Outlet Outlet

) d)

I l t I l t

c) d)

Electrode of the ozone generator afterseveral hours in CH8O2 and up to 2 wt of methane (a b c)

Inlet Inlet

three hours in CH8O2+traces of N2 and up to 1 wt of methane (d) Visible change of discharge character at about 13 length of electrode (a d)

Kinetics of CHx Conversion without N2

conversion by collisions

O2 + CHx 12wt O3 + CO2 +H2O

deposition vaporizationby sputtering

ibl b l 1000 CHreversible process below 1000ppm CH4

Effect of water on electrode surface with N2

Inlet

OutletOutlet

Electrode of the ozone generator after several hours in H OO N

Inlet

Electrode of the ozone generator after several hours in H2OO2N2

Effect of water on electrode surface

Long term effect (800 hrs) of H2OO2N2

Kinetics of CHx Conversion with N2

conversion by collisionsHNO3 formation

O2 + N2 +CHx 12wtO2 + CO2 +H2O + HNO3

deposition vaporizationby sputtering

H2O + HNO3

by sputtering

irreversible process above a N2 threshold () ltlt 1000ppm N2

sticky deposit

p 2 ( ) pp 2 any CH4 concentration (60ppm)

Plasma Chemistry with CH4 ImpuritiesPlasma Chemistry with CH4 Impurities4

bull Formation of NO and NO2 depends on O3 N2 and gas temperature Conclusion N2 admixture is the key factor

SummarySummaryyyThe mechanisms of formed NOx by-products follows the sameThe mechanisms of formed NOx by-products follows the sameprinciples as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentration

principles as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentrationozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)

ozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)g p ( g p )

The conversion of methane to OH and H2O is found to depend on

g p ( g p )

The conversion of methane to OH and H2O is found to depend ondissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)

dissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)discharge gap)discharge gap)

How do you optimize an ozone generatorg

Scientific ApproachScientific ApproachTheoretical Experimental

pppp

c [wt]

f [Hz]

c [wt]

f [Hz]

[kW]UUUβ1

1Cf4αPn

1iiminpeakimin

iiD

q [kWm2]q [kWm2]

150

180

][V]voltagepeakUpeak

[]cylinder perslicesofamountnsliceii

whereth

09 00

30

60

90

120

effic

ienc

y [

][0tdj t bl[F]sliceisdielectricofecapacitancC

[Hz]frequencyf[V]sliceivoltageminimumiUmin

thiD

th

10

28

46

64

82

39

107

176

244 power density

[kWm2]

ozone conc [wt][]CCβ

][0parameteradjustableα

iDiGi

Impact of Power Inductionp

350

400

wer

200

250

300

App

lied

Pow

Arr C 2Arr D +0

Arr E +45Arr F +7

Arr G +3

5 0

100

150

Frac

tion

of

1 2 3 4

ReferenceArr B unstable

Arr C -2

00

50

4Position (1inlet 4outlet)

Experimental Test Rigp g

Experimental Test Rigp g

Outer grounded electrode (left picture) and the dielectric covered inner electrodes (right) d e ect c cove ed e e ect odes ( g t)

Reference (Traditional) Arrangement

Inlet OutletGas flow direction

Optimized Arrangement

Inlet OutletGas flow direction

Intelligent Gap System (IGS)g p y ( )

Molecular Oxygen (O2) Ozone (O3)

O2 O3

yg ( 2) ( 3)

Particle Size SynthesisParticle Size SynthesisByBy--Products Cluster FormationProducts Cluster Formationyy

high diffusion and deposition to surfaces

low diffusion rate good transport

high sedimentation on the structurehigh sedimentation on the structure

Degreacutemont Technologies ndash OzoniaIntelligent Gap SystemIntelligent Gap System

G Vezzuacute JL Lopez A Freilich and K Becker Optimizationof Large-Scale Ozone Generators IEEE Transactions onPlasma Science Vol 37 No 6 p 890-896 (2009)

ConclusionsConclusionsConclusionsConclusionsFundamentals of ozone synthesis in a DBD plasmay p

ndash Highly filamented DBD discharges are best-suitedfor the production of ozone concentrations in therange of 6 to 14 wtrange of 6 to 14 wt

ndash The preferred characteristic of the microdischargesare Townsend-like at reduced electric fields Enaround 190 Townsend

ndash Detrimental side-effects induced by by-productscan be avoided by a proper design of the electrodecan be avoided by a proper design of the electrodearrangement The phenomenon is related to thediffusion rates of formed by-product clusters

ConclusionsConclusionsConclusionsConclusionsBenefits from DBD microplasma tailoring

ndash Reduced power consumption of up to 10 improvement

ndash Increased ozone concentrations of up to 14 now achievable

ndash Improved neutralization and conditioning of detrimental by-products

ndash Reduced system capital and operational cost

New technologies to improve ozone p

generatorg

HV Pulsed Power SwitchingHV Pulsed Power Switching

Microchannel Generation of Ozone

Channel ArrayChannel Array

Microchannel

330 microm 230 microm

Some Cap-DBD Devices Operating in Air

Increase of 60 of

Spacing 225 μmof 60 of plasma

No space

Cap‐DBD ozone generation

bull Ozone concentration is evaluated via Eco S d l UV 100 O A l (0 01Sensors model UV-100 Ozone Analyzer (001 ndash 900 ppm wiht an accuracy of plusmn2)

bull Three reactors 6 tubings 6rdquo with spacings of 0 μm 225 μm and 500 μm running at 3 kV μ μ μ g

SpacingOzone Concentration

3 kV rms 4 kV rms3 kV rms 4 kV rms

0 μm 660 ppm

225 μm 550 ppm

For a device of such small scale these ozone levels are promising

500 μm 380 ppm

J Mahoney W Zhu VS Johnson KH Becker and JL Lopez Electrical and optical emissionmeasurements of a capillary dielectric barrier discharge European Physics Journal D Vol 60 441-447(2010)

QuestionsQuestions

Thank YouFor more informationProf Jose L Lopez PhD

Thank YouFor more informationDepartment of Physics

Telephone (973) 761-9057Email joselopez1shuedu

Website wwwshueduacademicsartsciphysicsWebsite wwwshueduacademicsartsciphysics

Page 35: Dielectric Barrier Discharge (DBD) & Progress in Large ...bonitz/si12/talks/august_8/lopez_si12.pdf · Dielectric Barrier Discharge (DBD) & Progress in Large-Scale Ozone Generation

Principals of DBD MicroplasmasPrincipals of DBD MicroplasmasPrincipals of DBD MicroplasmasPrincipals of DBD Microplasmas

Dielectric Barrier Discharge (DBD)Dielectric Barrier Discharge (DBD)Electric Field

B kdBreakdown

Electrons amp Ions Discharge Physics

Excited SpeciesPlasma Chemistry

Chemical Reactions

OzoneGeneration

SurfaceTreatment

PollutionControl

ExcimerFormation CO2 Lasers Hydrogenation

of CO2

Excimer Lamps Plasma Displays

How A Plasma Display Works

How A Plasma Display Work

Plasma Display TelevisionsPlasma Display Televisions

Ozone Generator

3 O 2 O

Dielectric Barrier Discharge

3 O2 2 O3

OO22 OO33++OO22Ondash ndashO3O2

O2O2

Ondash ndash

endash O2Ondash ndash O2endash

O3

O3O2O2 O2

HeatHeatHeatHeat

Properties of Ozone (O3)

T i t i f f Tri-atomic form of oxygen

Most powerful commercial oxidizing agent

Unstable - must be generated and used onsite

Limited solubility in water but more so than oxygenLimited solubility in water but more so than oxygen

Leaves a dissolved residual which ultimately converts back to oxygenconverts back to oxygen

Discharge Tubes in Ozone GeneratorsDischarge Tubes in Ozone Generators

Traditional

Ozone Generator

with Glass Tubes

Generation of OzoneGeneration of Ozone

Generation of OzoneAdvantages of Enamel Dielectrics

Proven Patented Designbull Simplicity

Si l Di l i Cbull Single Dielectric Componentndash Reduced number of Dielectrics

bull Safety ndash Lower operating voltage

(lt 4000 V)bull Reliabilty

ndash Fused Dielectrics ensure continuous production

bull Lowest Power Consumption Operational Savingsndash Operational Savings

Modern Ozone GeneratorModern Ozone Generator

Ozonia Advanced Technology Ozone GeneratorOzone Generator

Generation of OzoneGeneration of Ozone

Generation of Ozone

Power Supply UnitPower Supply Unit

IGBT Inverter CircuitMain Circuit Breaker

HV 480 Volts60 Hz3 Phase Supply

C I

450KVAPow er to

GeneratorFILTER

CONVERTER INVERTERTRANSFORMER

C I450KVA Power Stage

CONTACTOR

bull Latest in Power Semiconductor Technology Modular Design

bull Utilizes IGBTrsquos (Insulated Gate Bi‐Polar Transistors) Converter and Inverter Components

Ozone Water Treatment

B bbl Diff iB bbl Diff iBubble DiffusionBubble Diffusion

Easy to use

Low energy usage Low energy usage

Mass transfer efficiencies to gt 90

Ozone Process Flow DiagramOzone Process Flow DiagramVent to

Atmosphere

O OOxygen

Off-Gas Blower

Ozone Destruct Unit

10 12

O3O2

LOX

10-12 O3

Ozone Generators

Ozone Contact ChamberLOX T k Generators Chamber

VaporizersLOX Tank

Municipal Ozone Installations

Ozonia Installations Ozone Plant Size [lbday] Start-Up DateKey Ozonia Installations (Partial List)

Los Angeles CA 10000 1986Fairfax VA ndash Corbalis 9000 2003MWD CA ndash Mills 9 000 2003

Ozonia Installations Ozone Plant Size [lbday] Start Up Date

MWD CA Mills 9000 2003Fairfax Co VA ndash Griffith 9000 2004MWD CA ndash Jensen 18750 2005Indianapolis IN ndash Belmont AWT 12000 2007I di li IN 12 000 2007Indianapolis IN ndash Southport AWT 12000 2007MWD CA ndash Diemer 13400 2008MWD CA ndash Weymouth 13400 2009

Ozonia North America - Potable Water SummaryTotal Number of Installations 90Total Installed Production gt 265000 lbsdayTotal Installed Production 265000 lbsday

Revision -B

Ozone Water TreatmentOzone Water Treatment

MWD Mills WTP - California

3 3 000 lbsda of o one3 3 000 lbsda of o one3 x 3000 lbsday of ozone3 x 3000 lbsday of ozone

Ozone Water TreatmentOzone Water TreatmentOzone Ozone -- How it worksHow it works

OxidantOxidant DisinfectantDisinfectant

bullbull Breaks double carbon Breaks double carbon bondsbonds

bullbull Kills by cell lysing or Kills by cell lysing or causing the cell wall tocausing the cell wall tobondsbonds

bullbull Creates OHCreates OHbullbull radicals radicals which break higher carbon which break higher carbon

causing the cell wall to causing the cell wall to rupture rupture

bullbull AttacksAttacks allall bacteriabacteriabondsbondsbullbull Increased temp and pH Increased temp and pH

accelerates Oaccelerates O33

Attacks Attacks allall bacteria bacteria virus cysts and spores virus cysts and spores in varying degreesin varying degreesaccelerates Oaccelerates O33

decomposition to OHdecomposition to OHbullbull

Micro-organism DNA

Capsule AdenineAdenine

Cell wall ThymineThymine

CytosineCytosine

GuanineGuanine

NuclearmaterialCellmembrane

material

Typical Bacterium DNA

Microbial Growth at Various Ozone ConcentrationsConcentrations

Growth likely

Growth possibleGrowth possible

NO GROWTH

0004 0008 0012 0016 0020

Ozone concentration (mgl)Ozone concentration (mgl)

Typical Water Treatment UsageTypical Water Treatment Usage

Application O3 mgl Contact timeUltra Pure Water 005 - 025 sec ndash min

Water bottling 04 ndash 10 5 ndash 10 min

Swimming pools ampspas

01 ndash 075 4 minutes

Potable taste amp odor 15 ndash 50 5 ndash 10 mindisinfection

Microfloculation 10 ndash 30 5 ndash 10 min

Lignin amp tammin 3 0 10 0 10 30 minLignin amp tamminremoval

30 ndash 100 10 ndash 30 min

Municipal wastewater 50 ndash 150+ 15 ndash 30 min

Ozone Water TreatmentOzone Water TreatmentOzone Ozone ndashndash Municipal ApplicationsMunicipal Applications

bullbull Taste and OdorTaste and Odor

bullbull Color RemovalColor Removal

bullbull Disinfection Without Trihalomethanes (THMs)Disinfection Without Trihalomethanes (THMs)

bullbull Improved Filtration Efficiency and FlocculationImproved Filtration Efficiency and Flocculation

bullbull Cryptosporidium DeactivationCryptosporidium Deactivation

bullbull Giardia amp Virus InactivationGiardia amp Virus Inactivation

bullbull Oxidation Oxidation -- Organics Fe amp MnOrganics Fe amp Mn

bullbull Wastewater disinfectionWastewater disinfection

bullbull BOD COD and TOC reductionBOD COD and TOC reduction

Applications of Ozone

Wastewater Treatmentbull Disinfection of Secondary and Tertiary Effluentsbull Color Reductionbull Color Reductionbull TOC Oxidation (Industrial)bull Oxidation of Odor Causing Compoundsbull Oxidation of Endocrine Disruptors (EDCrsquos) and p ( )

Pharmaceutically Active Compounds (PACrsquos)

Applications of Ozone

What are Endocrine Disruptors (EDCrsquos) and What are Endocrine Disruptors (EDCrsquos) and Ph ti ll A ti C d (PACrsquo )Ph ti ll A ti C d (PACrsquo )Pharmaceutically Active Compounds (PACrsquos)Pharmaceutically Active Compounds (PACrsquos)

bullbull EDCrsquosEDCrsquos andand PACrsquosPACrsquos areare NaturallyNaturally andand SyntheticSyntheticdd th tth t ff tff t thth b lb l llcompoundscompounds thatthat maymay affectaffect thethe balancebalance oror normalnormal

functionsfunctions inin animalsanimals andand humanshumans

What can EDCrsquos and PACrsquos doWhat can EDCrsquos and PACrsquos do

bullbull Even in very small concentrations these compounds Even in very small concentrations these compounds y py pcan can disruptdisrupt normal bodily functionsnormal bodily functions

bullbull ManMan--made chemicals can trick the bodies endocrine made chemicals can trick the bodies endocrine system system

Applications of Ozone

Examples of Endocrine Disruptors1000rsquos of compounds that may be Investigated as EDCs ndash Some examples are

bullbull Synthetic HormonesSynthetic Hormonesbullbull Naturally Occurring Estrogens Naturally Occurring Estrogens

Health and Beauty AidsHealth and Beauty Aidsbullbull Health and Beauty AidsHealth and Beauty Aidsbullbull SolventsSolventsbullbull PesticidesPesticidesbullbull SurfactantsSurfactantsbullbull PlasticsPlastics

F i idF i idbullbull FungicidesFungicides

Ozone Water TreatmentOzone Water Treatment

Ozone Ozone -- Industrial ApplicationsIndustrial Applications-- Ultrapure Water for Pharmaceutical ApplicationsUltrapure Water for Pharmaceutical Applications

-- Wastewater disinfection color removalWastewater disinfection color removal

-- Soil and Groundwater Remediation Soil and Groundwater Remediation

-- Cooling Tower Water TreatmentCooling Tower Water Treatment

-- Food ProcessingFood Processing

-- Aquaculture AquariumsAquaculture AquariumsAquaculture AquariumsAquaculture Aquariums

-- Beverage ApplicationsBeverage Applications

P l amp P Bl hiP l amp P Bl hi-- Pulp amp Paper BleachingPulp amp Paper Bleaching

High Purity OzonationHigh Purity Ozonation

Microchip manufacturingMicrochip manufacturing

What are the current issues in large-scale gozone generationg

Experimental Setup

Front view of the two units after the redesign and reworking ofthe gas water and instruments connectionsthe gas water and instruments connections

Experimental Setup

Top view of the twoexperimental unitsexperimental unitsSpectroscope (notshown) is to the left ofthe DBD The units weredifferent with respect todifferent with respect totheir electrodes onehad only the electrodecoated with thedielectric (ldquosingle-dielectric ( single-coatedrdquo) the other onehad the electrode andthe anode coated withthe dielectric (ldquodouble-the dielectric ( double-coatedrdquo)

Basics Generation of OzoneBasics Generation of Ozone

SpectroscopyPlasma

Plasma Absorption SpectroscopyPlasma Absorption Spectroscopy

Infrared Absorption SpectroscopyInfrared Absorption Spectroscopy

IR spectra in pure oxygen (black curve) and at approximately 10wt N2 admixture (red line) N2O5 peaks appear at124 1 d 1 2 11245 cm-1 and at 1725 cm-1

Infrared Absorption SpectroscopyInfrared Absorption Spectroscopy

IR spectra of several methane variations The green curve envelopes all of the methane peaks at 1325 cm-1recorded at smaller methane admixtures Simultaneously the N2O5 peaks disappear as the methane peaks appear

N2O5 FormationN2O5 Formation2 52 5p=2 bara cwt=20degC q=35kWm2 f=1450Hz

45N2O5 AT95

30

35

40

N

2 B

lend

ing

N2O AT95N2O5 IGSN2O IGSN2O5 LGN2O LG

1 5

20

25

nt [p

pmV]

3

wt

05

10

15

NO

x co

nten

005 7 9 11 13 15 17

ozone conc [wt]

Amount of formed N2O5 and N2O as a function of ozone concentration at 3 wt of nitrogen admixture and fori l dvarious electrode arrangements

Plasma Emission SpectroscopyPlasma Emission Spectroscopyp pyp py

Relative Emissions of the Ozonizer plasmaRelative Emissions of the Ozonizer plasma

Region 300- 850 nm from individual (calibrated) regions (smoothed by PeakFit) Single-coated ozone generator Inlet side

3 5E+06

30E+06

35E+06

7 9

20E+06

25E+06

nten

sity

au

2

311 12

10E+06

15E+06

In 4

5

6 8 10

14

15

16

17

00E+00

50E+05

280 300 320 340 360 380 400 420 440 460 480 500 520 540 560 580 600 620 640 660 680 700 720 740 760 780 800 820 840 860

Wavelength nm

1 13

Wavelength nm

Absolute Emission of the DBD PlasmaAbsolute Emission of the DBD Plasma

Intensities in (O2+3 wtN2) plasma

1 20E+04

100E+04

120E+04

600E+03

800E+03

nten

sity

(au

)

200E+03

400E+03

In

O(777)

000E+00200 250 300 350 400 450 500 550 600 650 700 750 800 850

Wavelength nm

Intensities in 3 wtN2+O2 plasmaIntensities in 3 wtN2+O2 plasma

Plasma Chemistry in OzonizersPlasma Chemistry in Ozonizers

Dry Air O2 N2

e - e -

O N2 N O2

O3 NO

O2 N O2

O3

N

3

NO2

O2 O3

NO

N

NO2 O3

N2O

NO3 N

N2O4

NO2

NO2

N2O5

NO3

Primary electron-driven chemical reactions leading to the formation of N2O5 and N2O in a dry air plasma

Plasma emission diagnostics role of N2Plasma emission diagnostics role of N2

Dry Air O2 N2

e - e -

O N2 N O2

O3 NO

O2 N O2

O3

O

N

ON

NO2

O2O3

N

NO N

NO2 O3

N2O

NO3 N

N2O4

NO2

NO2

N2O5

NO3

ONbullWith N2 present ndash less oxygen atoms are formed However the difference in intensity is

very small

Modeling of plasma chemistry incl the NxOy chemistry up to N2O5 for different Oxygen Nitrogen mixtures varying power deposition scenarios

and initial ozone background concentrations (up to 15) previously done

The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation

The role of N2 must be related to its by-products reacting on the surface of the electrodeThe role of N2 must be related to its by-products reacting on the surface of the electrode

The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established

Ab 8 t f O

The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established

Ab 8 t f OAbove 8 wt of O3

1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)

Above 8 wt of O3

1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)case without pampp)

2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of the

case without pampp)

2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of thethem A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface

them A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface

The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation

Three possibilities have to be considered for the oxygen-fedozone generator

Three possibilities have to be considered for the oxygen-fedozone generatorozone generator

bull Excited N2 molecules lead to an increased O2 dissociation in

ozone generator

bull Excited N2 molecules lead to an increased O2 dissociation in2 2such case an increased efficiency is correlated to the N2admixture

2 2such case an increased efficiency is correlated to the N2admixture

bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial

bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial

bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2

bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2g p g 3 pp y 2g p g 3 pp y 2

Effect of methane on ozone efficiency and specific powerEffect of methane on ozone efficiency and specific power

Effect of Methane on Ozone Content in Outlet Gas and on Specific Power Pure O2

13 12

10

11

12

t 8

10

8

9

10

ne c

onte

nt w

t

6

8

ecifi

c po

wer

kW

hlb

5

6

7

Ozo

n

2

4 Spe

400E+00 20E+03 40E+03 60E+03 80E+03 10E+04 12E+04

Methane in feedgas ppm

0

Ozone content in the outlet gas Specif ic pow er of the ozone generatorg p p g

Effects of N2 and CH4Effects of N2 and CH4

Pi t f h t lli N O t tPicture of an amorphous-crystalline N2O5 structurecaptured at the Orlando Skylake water plant in 2006

Plasma Chemistry with CH4 Impurities

OxygenO2 N2

e - e -

CHO N2

NO2

O NO

O2 N O2 O3

NOH

CH4e-

O3 NO

NO2

O2O3NO N

NO2 O

NO2

NO2

N2ONO3

N

O3

NO2

NO

HNO3

N2O4

N2O5

NO2

NO3

N2O5

Effect of methane on the electrode surfaces

a) b)

Inlet Outlet Outlet

) d)

I l t I l t

c) d)

Electrode of the ozone generator afterseveral hours in CH8O2 and up to 2 wt of methane (a b c)

Inlet Inlet

three hours in CH8O2+traces of N2 and up to 1 wt of methane (d) Visible change of discharge character at about 13 length of electrode (a d)

Kinetics of CHx Conversion without N2

conversion by collisions

O2 + CHx 12wt O3 + CO2 +H2O

deposition vaporizationby sputtering

ibl b l 1000 CHreversible process below 1000ppm CH4

Effect of water on electrode surface with N2

Inlet

OutletOutlet

Electrode of the ozone generator after several hours in H OO N

Inlet

Electrode of the ozone generator after several hours in H2OO2N2

Effect of water on electrode surface

Long term effect (800 hrs) of H2OO2N2

Kinetics of CHx Conversion with N2

conversion by collisionsHNO3 formation

O2 + N2 +CHx 12wtO2 + CO2 +H2O + HNO3

deposition vaporizationby sputtering

H2O + HNO3

by sputtering

irreversible process above a N2 threshold () ltlt 1000ppm N2

sticky deposit

p 2 ( ) pp 2 any CH4 concentration (60ppm)

Plasma Chemistry with CH4 ImpuritiesPlasma Chemistry with CH4 Impurities4

bull Formation of NO and NO2 depends on O3 N2 and gas temperature Conclusion N2 admixture is the key factor

SummarySummaryyyThe mechanisms of formed NOx by-products follows the sameThe mechanisms of formed NOx by-products follows the sameprinciples as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentration

principles as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentrationozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)

ozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)g p ( g p )

The conversion of methane to OH and H2O is found to depend on

g p ( g p )

The conversion of methane to OH and H2O is found to depend ondissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)

dissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)discharge gap)discharge gap)

How do you optimize an ozone generatorg

Scientific ApproachScientific ApproachTheoretical Experimental

pppp

c [wt]

f [Hz]

c [wt]

f [Hz]

[kW]UUUβ1

1Cf4αPn

1iiminpeakimin

iiD

q [kWm2]q [kWm2]

150

180

][V]voltagepeakUpeak

[]cylinder perslicesofamountnsliceii

whereth

09 00

30

60

90

120

effic

ienc

y [

][0tdj t bl[F]sliceisdielectricofecapacitancC

[Hz]frequencyf[V]sliceivoltageminimumiUmin

thiD

th

10

28

46

64

82

39

107

176

244 power density

[kWm2]

ozone conc [wt][]CCβ

][0parameteradjustableα

iDiGi

Impact of Power Inductionp

350

400

wer

200

250

300

App

lied

Pow

Arr C 2Arr D +0

Arr E +45Arr F +7

Arr G +3

5 0

100

150

Frac

tion

of

1 2 3 4

ReferenceArr B unstable

Arr C -2

00

50

4Position (1inlet 4outlet)

Experimental Test Rigp g

Experimental Test Rigp g

Outer grounded electrode (left picture) and the dielectric covered inner electrodes (right) d e ect c cove ed e e ect odes ( g t)

Reference (Traditional) Arrangement

Inlet OutletGas flow direction

Optimized Arrangement

Inlet OutletGas flow direction

Intelligent Gap System (IGS)g p y ( )

Molecular Oxygen (O2) Ozone (O3)

O2 O3

yg ( 2) ( 3)

Particle Size SynthesisParticle Size SynthesisByBy--Products Cluster FormationProducts Cluster Formationyy

high diffusion and deposition to surfaces

low diffusion rate good transport

high sedimentation on the structurehigh sedimentation on the structure

Degreacutemont Technologies ndash OzoniaIntelligent Gap SystemIntelligent Gap System

G Vezzuacute JL Lopez A Freilich and K Becker Optimizationof Large-Scale Ozone Generators IEEE Transactions onPlasma Science Vol 37 No 6 p 890-896 (2009)

ConclusionsConclusionsConclusionsConclusionsFundamentals of ozone synthesis in a DBD plasmay p

ndash Highly filamented DBD discharges are best-suitedfor the production of ozone concentrations in therange of 6 to 14 wtrange of 6 to 14 wt

ndash The preferred characteristic of the microdischargesare Townsend-like at reduced electric fields Enaround 190 Townsend

ndash Detrimental side-effects induced by by-productscan be avoided by a proper design of the electrodecan be avoided by a proper design of the electrodearrangement The phenomenon is related to thediffusion rates of formed by-product clusters

ConclusionsConclusionsConclusionsConclusionsBenefits from DBD microplasma tailoring

ndash Reduced power consumption of up to 10 improvement

ndash Increased ozone concentrations of up to 14 now achievable

ndash Improved neutralization and conditioning of detrimental by-products

ndash Reduced system capital and operational cost

New technologies to improve ozone p

generatorg

HV Pulsed Power SwitchingHV Pulsed Power Switching

Microchannel Generation of Ozone

Channel ArrayChannel Array

Microchannel

330 microm 230 microm

Some Cap-DBD Devices Operating in Air

Increase of 60 of

Spacing 225 μmof 60 of plasma

No space

Cap‐DBD ozone generation

bull Ozone concentration is evaluated via Eco S d l UV 100 O A l (0 01Sensors model UV-100 Ozone Analyzer (001 ndash 900 ppm wiht an accuracy of plusmn2)

bull Three reactors 6 tubings 6rdquo with spacings of 0 μm 225 μm and 500 μm running at 3 kV μ μ μ g

SpacingOzone Concentration

3 kV rms 4 kV rms3 kV rms 4 kV rms

0 μm 660 ppm

225 μm 550 ppm

For a device of such small scale these ozone levels are promising

500 μm 380 ppm

J Mahoney W Zhu VS Johnson KH Becker and JL Lopez Electrical and optical emissionmeasurements of a capillary dielectric barrier discharge European Physics Journal D Vol 60 441-447(2010)

QuestionsQuestions

Thank YouFor more informationProf Jose L Lopez PhD

Thank YouFor more informationDepartment of Physics

Telephone (973) 761-9057Email joselopez1shuedu

Website wwwshueduacademicsartsciphysicsWebsite wwwshueduacademicsartsciphysics

Page 36: Dielectric Barrier Discharge (DBD) & Progress in Large ...bonitz/si12/talks/august_8/lopez_si12.pdf · Dielectric Barrier Discharge (DBD) & Progress in Large-Scale Ozone Generation

Dielectric Barrier Discharge (DBD)Dielectric Barrier Discharge (DBD)Electric Field

B kdBreakdown

Electrons amp Ions Discharge Physics

Excited SpeciesPlasma Chemistry

Chemical Reactions

OzoneGeneration

SurfaceTreatment

PollutionControl

ExcimerFormation CO2 Lasers Hydrogenation

of CO2

Excimer Lamps Plasma Displays

How A Plasma Display Works

How A Plasma Display Work

Plasma Display TelevisionsPlasma Display Televisions

Ozone Generator

3 O 2 O

Dielectric Barrier Discharge

3 O2 2 O3

OO22 OO33++OO22Ondash ndashO3O2

O2O2

Ondash ndash

endash O2Ondash ndash O2endash

O3

O3O2O2 O2

HeatHeatHeatHeat

Properties of Ozone (O3)

T i t i f f Tri-atomic form of oxygen

Most powerful commercial oxidizing agent

Unstable - must be generated and used onsite

Limited solubility in water but more so than oxygenLimited solubility in water but more so than oxygen

Leaves a dissolved residual which ultimately converts back to oxygenconverts back to oxygen

Discharge Tubes in Ozone GeneratorsDischarge Tubes in Ozone Generators

Traditional

Ozone Generator

with Glass Tubes

Generation of OzoneGeneration of Ozone

Generation of OzoneAdvantages of Enamel Dielectrics

Proven Patented Designbull Simplicity

Si l Di l i Cbull Single Dielectric Componentndash Reduced number of Dielectrics

bull Safety ndash Lower operating voltage

(lt 4000 V)bull Reliabilty

ndash Fused Dielectrics ensure continuous production

bull Lowest Power Consumption Operational Savingsndash Operational Savings

Modern Ozone GeneratorModern Ozone Generator

Ozonia Advanced Technology Ozone GeneratorOzone Generator

Generation of OzoneGeneration of Ozone

Generation of Ozone

Power Supply UnitPower Supply Unit

IGBT Inverter CircuitMain Circuit Breaker

HV 480 Volts60 Hz3 Phase Supply

C I

450KVAPow er to

GeneratorFILTER

CONVERTER INVERTERTRANSFORMER

C I450KVA Power Stage

CONTACTOR

bull Latest in Power Semiconductor Technology Modular Design

bull Utilizes IGBTrsquos (Insulated Gate Bi‐Polar Transistors) Converter and Inverter Components

Ozone Water Treatment

B bbl Diff iB bbl Diff iBubble DiffusionBubble Diffusion

Easy to use

Low energy usage Low energy usage

Mass transfer efficiencies to gt 90

Ozone Process Flow DiagramOzone Process Flow DiagramVent to

Atmosphere

O OOxygen

Off-Gas Blower

Ozone Destruct Unit

10 12

O3O2

LOX

10-12 O3

Ozone Generators

Ozone Contact ChamberLOX T k Generators Chamber

VaporizersLOX Tank

Municipal Ozone Installations

Ozonia Installations Ozone Plant Size [lbday] Start-Up DateKey Ozonia Installations (Partial List)

Los Angeles CA 10000 1986Fairfax VA ndash Corbalis 9000 2003MWD CA ndash Mills 9 000 2003

Ozonia Installations Ozone Plant Size [lbday] Start Up Date

MWD CA Mills 9000 2003Fairfax Co VA ndash Griffith 9000 2004MWD CA ndash Jensen 18750 2005Indianapolis IN ndash Belmont AWT 12000 2007I di li IN 12 000 2007Indianapolis IN ndash Southport AWT 12000 2007MWD CA ndash Diemer 13400 2008MWD CA ndash Weymouth 13400 2009

Ozonia North America - Potable Water SummaryTotal Number of Installations 90Total Installed Production gt 265000 lbsdayTotal Installed Production 265000 lbsday

Revision -B

Ozone Water TreatmentOzone Water Treatment

MWD Mills WTP - California

3 3 000 lbsda of o one3 3 000 lbsda of o one3 x 3000 lbsday of ozone3 x 3000 lbsday of ozone

Ozone Water TreatmentOzone Water TreatmentOzone Ozone -- How it worksHow it works

OxidantOxidant DisinfectantDisinfectant

bullbull Breaks double carbon Breaks double carbon bondsbonds

bullbull Kills by cell lysing or Kills by cell lysing or causing the cell wall tocausing the cell wall tobondsbonds

bullbull Creates OHCreates OHbullbull radicals radicals which break higher carbon which break higher carbon

causing the cell wall to causing the cell wall to rupture rupture

bullbull AttacksAttacks allall bacteriabacteriabondsbondsbullbull Increased temp and pH Increased temp and pH

accelerates Oaccelerates O33

Attacks Attacks allall bacteria bacteria virus cysts and spores virus cysts and spores in varying degreesin varying degreesaccelerates Oaccelerates O33

decomposition to OHdecomposition to OHbullbull

Micro-organism DNA

Capsule AdenineAdenine

Cell wall ThymineThymine

CytosineCytosine

GuanineGuanine

NuclearmaterialCellmembrane

material

Typical Bacterium DNA

Microbial Growth at Various Ozone ConcentrationsConcentrations

Growth likely

Growth possibleGrowth possible

NO GROWTH

0004 0008 0012 0016 0020

Ozone concentration (mgl)Ozone concentration (mgl)

Typical Water Treatment UsageTypical Water Treatment Usage

Application O3 mgl Contact timeUltra Pure Water 005 - 025 sec ndash min

Water bottling 04 ndash 10 5 ndash 10 min

Swimming pools ampspas

01 ndash 075 4 minutes

Potable taste amp odor 15 ndash 50 5 ndash 10 mindisinfection

Microfloculation 10 ndash 30 5 ndash 10 min

Lignin amp tammin 3 0 10 0 10 30 minLignin amp tamminremoval

30 ndash 100 10 ndash 30 min

Municipal wastewater 50 ndash 150+ 15 ndash 30 min

Ozone Water TreatmentOzone Water TreatmentOzone Ozone ndashndash Municipal ApplicationsMunicipal Applications

bullbull Taste and OdorTaste and Odor

bullbull Color RemovalColor Removal

bullbull Disinfection Without Trihalomethanes (THMs)Disinfection Without Trihalomethanes (THMs)

bullbull Improved Filtration Efficiency and FlocculationImproved Filtration Efficiency and Flocculation

bullbull Cryptosporidium DeactivationCryptosporidium Deactivation

bullbull Giardia amp Virus InactivationGiardia amp Virus Inactivation

bullbull Oxidation Oxidation -- Organics Fe amp MnOrganics Fe amp Mn

bullbull Wastewater disinfectionWastewater disinfection

bullbull BOD COD and TOC reductionBOD COD and TOC reduction

Applications of Ozone

Wastewater Treatmentbull Disinfection of Secondary and Tertiary Effluentsbull Color Reductionbull Color Reductionbull TOC Oxidation (Industrial)bull Oxidation of Odor Causing Compoundsbull Oxidation of Endocrine Disruptors (EDCrsquos) and p ( )

Pharmaceutically Active Compounds (PACrsquos)

Applications of Ozone

What are Endocrine Disruptors (EDCrsquos) and What are Endocrine Disruptors (EDCrsquos) and Ph ti ll A ti C d (PACrsquo )Ph ti ll A ti C d (PACrsquo )Pharmaceutically Active Compounds (PACrsquos)Pharmaceutically Active Compounds (PACrsquos)

bullbull EDCrsquosEDCrsquos andand PACrsquosPACrsquos areare NaturallyNaturally andand SyntheticSyntheticdd th tth t ff tff t thth b lb l llcompoundscompounds thatthat maymay affectaffect thethe balancebalance oror normalnormal

functionsfunctions inin animalsanimals andand humanshumans

What can EDCrsquos and PACrsquos doWhat can EDCrsquos and PACrsquos do

bullbull Even in very small concentrations these compounds Even in very small concentrations these compounds y py pcan can disruptdisrupt normal bodily functionsnormal bodily functions

bullbull ManMan--made chemicals can trick the bodies endocrine made chemicals can trick the bodies endocrine system system

Applications of Ozone

Examples of Endocrine Disruptors1000rsquos of compounds that may be Investigated as EDCs ndash Some examples are

bullbull Synthetic HormonesSynthetic Hormonesbullbull Naturally Occurring Estrogens Naturally Occurring Estrogens

Health and Beauty AidsHealth and Beauty Aidsbullbull Health and Beauty AidsHealth and Beauty Aidsbullbull SolventsSolventsbullbull PesticidesPesticidesbullbull SurfactantsSurfactantsbullbull PlasticsPlastics

F i idF i idbullbull FungicidesFungicides

Ozone Water TreatmentOzone Water Treatment

Ozone Ozone -- Industrial ApplicationsIndustrial Applications-- Ultrapure Water for Pharmaceutical ApplicationsUltrapure Water for Pharmaceutical Applications

-- Wastewater disinfection color removalWastewater disinfection color removal

-- Soil and Groundwater Remediation Soil and Groundwater Remediation

-- Cooling Tower Water TreatmentCooling Tower Water Treatment

-- Food ProcessingFood Processing

-- Aquaculture AquariumsAquaculture AquariumsAquaculture AquariumsAquaculture Aquariums

-- Beverage ApplicationsBeverage Applications

P l amp P Bl hiP l amp P Bl hi-- Pulp amp Paper BleachingPulp amp Paper Bleaching

High Purity OzonationHigh Purity Ozonation

Microchip manufacturingMicrochip manufacturing

What are the current issues in large-scale gozone generationg

Experimental Setup

Front view of the two units after the redesign and reworking ofthe gas water and instruments connectionsthe gas water and instruments connections

Experimental Setup

Top view of the twoexperimental unitsexperimental unitsSpectroscope (notshown) is to the left ofthe DBD The units weredifferent with respect todifferent with respect totheir electrodes onehad only the electrodecoated with thedielectric (ldquosingle-dielectric ( single-coatedrdquo) the other onehad the electrode andthe anode coated withthe dielectric (ldquodouble-the dielectric ( double-coatedrdquo)

Basics Generation of OzoneBasics Generation of Ozone

SpectroscopyPlasma

Plasma Absorption SpectroscopyPlasma Absorption Spectroscopy

Infrared Absorption SpectroscopyInfrared Absorption Spectroscopy

IR spectra in pure oxygen (black curve) and at approximately 10wt N2 admixture (red line) N2O5 peaks appear at124 1 d 1 2 11245 cm-1 and at 1725 cm-1

Infrared Absorption SpectroscopyInfrared Absorption Spectroscopy

IR spectra of several methane variations The green curve envelopes all of the methane peaks at 1325 cm-1recorded at smaller methane admixtures Simultaneously the N2O5 peaks disappear as the methane peaks appear

N2O5 FormationN2O5 Formation2 52 5p=2 bara cwt=20degC q=35kWm2 f=1450Hz

45N2O5 AT95

30

35

40

N

2 B

lend

ing

N2O AT95N2O5 IGSN2O IGSN2O5 LGN2O LG

1 5

20

25

nt [p

pmV]

3

wt

05

10

15

NO

x co

nten

005 7 9 11 13 15 17

ozone conc [wt]

Amount of formed N2O5 and N2O as a function of ozone concentration at 3 wt of nitrogen admixture and fori l dvarious electrode arrangements

Plasma Emission SpectroscopyPlasma Emission Spectroscopyp pyp py

Relative Emissions of the Ozonizer plasmaRelative Emissions of the Ozonizer plasma

Region 300- 850 nm from individual (calibrated) regions (smoothed by PeakFit) Single-coated ozone generator Inlet side

3 5E+06

30E+06

35E+06

7 9

20E+06

25E+06

nten

sity

au

2

311 12

10E+06

15E+06

In 4

5

6 8 10

14

15

16

17

00E+00

50E+05

280 300 320 340 360 380 400 420 440 460 480 500 520 540 560 580 600 620 640 660 680 700 720 740 760 780 800 820 840 860

Wavelength nm

1 13

Wavelength nm

Absolute Emission of the DBD PlasmaAbsolute Emission of the DBD Plasma

Intensities in (O2+3 wtN2) plasma

1 20E+04

100E+04

120E+04

600E+03

800E+03

nten

sity

(au

)

200E+03

400E+03

In

O(777)

000E+00200 250 300 350 400 450 500 550 600 650 700 750 800 850

Wavelength nm

Intensities in 3 wtN2+O2 plasmaIntensities in 3 wtN2+O2 plasma

Plasma Chemistry in OzonizersPlasma Chemistry in Ozonizers

Dry Air O2 N2

e - e -

O N2 N O2

O3 NO

O2 N O2

O3

N

3

NO2

O2 O3

NO

N

NO2 O3

N2O

NO3 N

N2O4

NO2

NO2

N2O5

NO3

Primary electron-driven chemical reactions leading to the formation of N2O5 and N2O in a dry air plasma

Plasma emission diagnostics role of N2Plasma emission diagnostics role of N2

Dry Air O2 N2

e - e -

O N2 N O2

O3 NO

O2 N O2

O3

O

N

ON

NO2

O2O3

N

NO N

NO2 O3

N2O

NO3 N

N2O4

NO2

NO2

N2O5

NO3

ONbullWith N2 present ndash less oxygen atoms are formed However the difference in intensity is

very small

Modeling of plasma chemistry incl the NxOy chemistry up to N2O5 for different Oxygen Nitrogen mixtures varying power deposition scenarios

and initial ozone background concentrations (up to 15) previously done

The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation

The role of N2 must be related to its by-products reacting on the surface of the electrodeThe role of N2 must be related to its by-products reacting on the surface of the electrode

The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established

Ab 8 t f O

The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established

Ab 8 t f OAbove 8 wt of O3

1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)

Above 8 wt of O3

1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)case without pampp)

2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of the

case without pampp)

2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of thethem A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface

them A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface

The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation

Three possibilities have to be considered for the oxygen-fedozone generator

Three possibilities have to be considered for the oxygen-fedozone generatorozone generator

bull Excited N2 molecules lead to an increased O2 dissociation in

ozone generator

bull Excited N2 molecules lead to an increased O2 dissociation in2 2such case an increased efficiency is correlated to the N2admixture

2 2such case an increased efficiency is correlated to the N2admixture

bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial

bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial

bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2

bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2g p g 3 pp y 2g p g 3 pp y 2

Effect of methane on ozone efficiency and specific powerEffect of methane on ozone efficiency and specific power

Effect of Methane on Ozone Content in Outlet Gas and on Specific Power Pure O2

13 12

10

11

12

t 8

10

8

9

10

ne c

onte

nt w

t

6

8

ecifi

c po

wer

kW

hlb

5

6

7

Ozo

n

2

4 Spe

400E+00 20E+03 40E+03 60E+03 80E+03 10E+04 12E+04

Methane in feedgas ppm

0

Ozone content in the outlet gas Specif ic pow er of the ozone generatorg p p g

Effects of N2 and CH4Effects of N2 and CH4

Pi t f h t lli N O t tPicture of an amorphous-crystalline N2O5 structurecaptured at the Orlando Skylake water plant in 2006

Plasma Chemistry with CH4 Impurities

OxygenO2 N2

e - e -

CHO N2

NO2

O NO

O2 N O2 O3

NOH

CH4e-

O3 NO

NO2

O2O3NO N

NO2 O

NO2

NO2

N2ONO3

N

O3

NO2

NO

HNO3

N2O4

N2O5

NO2

NO3

N2O5

Effect of methane on the electrode surfaces

a) b)

Inlet Outlet Outlet

) d)

I l t I l t

c) d)

Electrode of the ozone generator afterseveral hours in CH8O2 and up to 2 wt of methane (a b c)

Inlet Inlet

three hours in CH8O2+traces of N2 and up to 1 wt of methane (d) Visible change of discharge character at about 13 length of electrode (a d)

Kinetics of CHx Conversion without N2

conversion by collisions

O2 + CHx 12wt O3 + CO2 +H2O

deposition vaporizationby sputtering

ibl b l 1000 CHreversible process below 1000ppm CH4

Effect of water on electrode surface with N2

Inlet

OutletOutlet

Electrode of the ozone generator after several hours in H OO N

Inlet

Electrode of the ozone generator after several hours in H2OO2N2

Effect of water on electrode surface

Long term effect (800 hrs) of H2OO2N2

Kinetics of CHx Conversion with N2

conversion by collisionsHNO3 formation

O2 + N2 +CHx 12wtO2 + CO2 +H2O + HNO3

deposition vaporizationby sputtering

H2O + HNO3

by sputtering

irreversible process above a N2 threshold () ltlt 1000ppm N2

sticky deposit

p 2 ( ) pp 2 any CH4 concentration (60ppm)

Plasma Chemistry with CH4 ImpuritiesPlasma Chemistry with CH4 Impurities4

bull Formation of NO and NO2 depends on O3 N2 and gas temperature Conclusion N2 admixture is the key factor

SummarySummaryyyThe mechanisms of formed NOx by-products follows the sameThe mechanisms of formed NOx by-products follows the sameprinciples as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentration

principles as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentrationozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)

ozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)g p ( g p )

The conversion of methane to OH and H2O is found to depend on

g p ( g p )

The conversion of methane to OH and H2O is found to depend ondissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)

dissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)discharge gap)discharge gap)

How do you optimize an ozone generatorg

Scientific ApproachScientific ApproachTheoretical Experimental

pppp

c [wt]

f [Hz]

c [wt]

f [Hz]

[kW]UUUβ1

1Cf4αPn

1iiminpeakimin

iiD

q [kWm2]q [kWm2]

150

180

][V]voltagepeakUpeak

[]cylinder perslicesofamountnsliceii

whereth

09 00

30

60

90

120

effic

ienc

y [

][0tdj t bl[F]sliceisdielectricofecapacitancC

[Hz]frequencyf[V]sliceivoltageminimumiUmin

thiD

th

10

28

46

64

82

39

107

176

244 power density

[kWm2]

ozone conc [wt][]CCβ

][0parameteradjustableα

iDiGi

Impact of Power Inductionp

350

400

wer

200

250

300

App

lied

Pow

Arr C 2Arr D +0

Arr E +45Arr F +7

Arr G +3

5 0

100

150

Frac

tion

of

1 2 3 4

ReferenceArr B unstable

Arr C -2

00

50

4Position (1inlet 4outlet)

Experimental Test Rigp g

Experimental Test Rigp g

Outer grounded electrode (left picture) and the dielectric covered inner electrodes (right) d e ect c cove ed e e ect odes ( g t)

Reference (Traditional) Arrangement

Inlet OutletGas flow direction

Optimized Arrangement

Inlet OutletGas flow direction

Intelligent Gap System (IGS)g p y ( )

Molecular Oxygen (O2) Ozone (O3)

O2 O3

yg ( 2) ( 3)

Particle Size SynthesisParticle Size SynthesisByBy--Products Cluster FormationProducts Cluster Formationyy

high diffusion and deposition to surfaces

low diffusion rate good transport

high sedimentation on the structurehigh sedimentation on the structure

Degreacutemont Technologies ndash OzoniaIntelligent Gap SystemIntelligent Gap System

G Vezzuacute JL Lopez A Freilich and K Becker Optimizationof Large-Scale Ozone Generators IEEE Transactions onPlasma Science Vol 37 No 6 p 890-896 (2009)

ConclusionsConclusionsConclusionsConclusionsFundamentals of ozone synthesis in a DBD plasmay p

ndash Highly filamented DBD discharges are best-suitedfor the production of ozone concentrations in therange of 6 to 14 wtrange of 6 to 14 wt

ndash The preferred characteristic of the microdischargesare Townsend-like at reduced electric fields Enaround 190 Townsend

ndash Detrimental side-effects induced by by-productscan be avoided by a proper design of the electrodecan be avoided by a proper design of the electrodearrangement The phenomenon is related to thediffusion rates of formed by-product clusters

ConclusionsConclusionsConclusionsConclusionsBenefits from DBD microplasma tailoring

ndash Reduced power consumption of up to 10 improvement

ndash Increased ozone concentrations of up to 14 now achievable

ndash Improved neutralization and conditioning of detrimental by-products

ndash Reduced system capital and operational cost

New technologies to improve ozone p

generatorg

HV Pulsed Power SwitchingHV Pulsed Power Switching

Microchannel Generation of Ozone

Channel ArrayChannel Array

Microchannel

330 microm 230 microm

Some Cap-DBD Devices Operating in Air

Increase of 60 of

Spacing 225 μmof 60 of plasma

No space

Cap‐DBD ozone generation

bull Ozone concentration is evaluated via Eco S d l UV 100 O A l (0 01Sensors model UV-100 Ozone Analyzer (001 ndash 900 ppm wiht an accuracy of plusmn2)

bull Three reactors 6 tubings 6rdquo with spacings of 0 μm 225 μm and 500 μm running at 3 kV μ μ μ g

SpacingOzone Concentration

3 kV rms 4 kV rms3 kV rms 4 kV rms

0 μm 660 ppm

225 μm 550 ppm

For a device of such small scale these ozone levels are promising

500 μm 380 ppm

J Mahoney W Zhu VS Johnson KH Becker and JL Lopez Electrical and optical emissionmeasurements of a capillary dielectric barrier discharge European Physics Journal D Vol 60 441-447(2010)

QuestionsQuestions

Thank YouFor more informationProf Jose L Lopez PhD

Thank YouFor more informationDepartment of Physics

Telephone (973) 761-9057Email joselopez1shuedu

Website wwwshueduacademicsartsciphysicsWebsite wwwshueduacademicsartsciphysics

Page 37: Dielectric Barrier Discharge (DBD) & Progress in Large ...bonitz/si12/talks/august_8/lopez_si12.pdf · Dielectric Barrier Discharge (DBD) & Progress in Large-Scale Ozone Generation

How A Plasma Display Works

How A Plasma Display Work

Plasma Display TelevisionsPlasma Display Televisions

Ozone Generator

3 O 2 O

Dielectric Barrier Discharge

3 O2 2 O3

OO22 OO33++OO22Ondash ndashO3O2

O2O2

Ondash ndash

endash O2Ondash ndash O2endash

O3

O3O2O2 O2

HeatHeatHeatHeat

Properties of Ozone (O3)

T i t i f f Tri-atomic form of oxygen

Most powerful commercial oxidizing agent

Unstable - must be generated and used onsite

Limited solubility in water but more so than oxygenLimited solubility in water but more so than oxygen

Leaves a dissolved residual which ultimately converts back to oxygenconverts back to oxygen

Discharge Tubes in Ozone GeneratorsDischarge Tubes in Ozone Generators

Traditional

Ozone Generator

with Glass Tubes

Generation of OzoneGeneration of Ozone

Generation of OzoneAdvantages of Enamel Dielectrics

Proven Patented Designbull Simplicity

Si l Di l i Cbull Single Dielectric Componentndash Reduced number of Dielectrics

bull Safety ndash Lower operating voltage

(lt 4000 V)bull Reliabilty

ndash Fused Dielectrics ensure continuous production

bull Lowest Power Consumption Operational Savingsndash Operational Savings

Modern Ozone GeneratorModern Ozone Generator

Ozonia Advanced Technology Ozone GeneratorOzone Generator

Generation of OzoneGeneration of Ozone

Generation of Ozone

Power Supply UnitPower Supply Unit

IGBT Inverter CircuitMain Circuit Breaker

HV 480 Volts60 Hz3 Phase Supply

C I

450KVAPow er to

GeneratorFILTER

CONVERTER INVERTERTRANSFORMER

C I450KVA Power Stage

CONTACTOR

bull Latest in Power Semiconductor Technology Modular Design

bull Utilizes IGBTrsquos (Insulated Gate Bi‐Polar Transistors) Converter and Inverter Components

Ozone Water Treatment

B bbl Diff iB bbl Diff iBubble DiffusionBubble Diffusion

Easy to use

Low energy usage Low energy usage

Mass transfer efficiencies to gt 90

Ozone Process Flow DiagramOzone Process Flow DiagramVent to

Atmosphere

O OOxygen

Off-Gas Blower

Ozone Destruct Unit

10 12

O3O2

LOX

10-12 O3

Ozone Generators

Ozone Contact ChamberLOX T k Generators Chamber

VaporizersLOX Tank

Municipal Ozone Installations

Ozonia Installations Ozone Plant Size [lbday] Start-Up DateKey Ozonia Installations (Partial List)

Los Angeles CA 10000 1986Fairfax VA ndash Corbalis 9000 2003MWD CA ndash Mills 9 000 2003

Ozonia Installations Ozone Plant Size [lbday] Start Up Date

MWD CA Mills 9000 2003Fairfax Co VA ndash Griffith 9000 2004MWD CA ndash Jensen 18750 2005Indianapolis IN ndash Belmont AWT 12000 2007I di li IN 12 000 2007Indianapolis IN ndash Southport AWT 12000 2007MWD CA ndash Diemer 13400 2008MWD CA ndash Weymouth 13400 2009

Ozonia North America - Potable Water SummaryTotal Number of Installations 90Total Installed Production gt 265000 lbsdayTotal Installed Production 265000 lbsday

Revision -B

Ozone Water TreatmentOzone Water Treatment

MWD Mills WTP - California

3 3 000 lbsda of o one3 3 000 lbsda of o one3 x 3000 lbsday of ozone3 x 3000 lbsday of ozone

Ozone Water TreatmentOzone Water TreatmentOzone Ozone -- How it worksHow it works

OxidantOxidant DisinfectantDisinfectant

bullbull Breaks double carbon Breaks double carbon bondsbonds

bullbull Kills by cell lysing or Kills by cell lysing or causing the cell wall tocausing the cell wall tobondsbonds

bullbull Creates OHCreates OHbullbull radicals radicals which break higher carbon which break higher carbon

causing the cell wall to causing the cell wall to rupture rupture

bullbull AttacksAttacks allall bacteriabacteriabondsbondsbullbull Increased temp and pH Increased temp and pH

accelerates Oaccelerates O33

Attacks Attacks allall bacteria bacteria virus cysts and spores virus cysts and spores in varying degreesin varying degreesaccelerates Oaccelerates O33

decomposition to OHdecomposition to OHbullbull

Micro-organism DNA

Capsule AdenineAdenine

Cell wall ThymineThymine

CytosineCytosine

GuanineGuanine

NuclearmaterialCellmembrane

material

Typical Bacterium DNA

Microbial Growth at Various Ozone ConcentrationsConcentrations

Growth likely

Growth possibleGrowth possible

NO GROWTH

0004 0008 0012 0016 0020

Ozone concentration (mgl)Ozone concentration (mgl)

Typical Water Treatment UsageTypical Water Treatment Usage

Application O3 mgl Contact timeUltra Pure Water 005 - 025 sec ndash min

Water bottling 04 ndash 10 5 ndash 10 min

Swimming pools ampspas

01 ndash 075 4 minutes

Potable taste amp odor 15 ndash 50 5 ndash 10 mindisinfection

Microfloculation 10 ndash 30 5 ndash 10 min

Lignin amp tammin 3 0 10 0 10 30 minLignin amp tamminremoval

30 ndash 100 10 ndash 30 min

Municipal wastewater 50 ndash 150+ 15 ndash 30 min

Ozone Water TreatmentOzone Water TreatmentOzone Ozone ndashndash Municipal ApplicationsMunicipal Applications

bullbull Taste and OdorTaste and Odor

bullbull Color RemovalColor Removal

bullbull Disinfection Without Trihalomethanes (THMs)Disinfection Without Trihalomethanes (THMs)

bullbull Improved Filtration Efficiency and FlocculationImproved Filtration Efficiency and Flocculation

bullbull Cryptosporidium DeactivationCryptosporidium Deactivation

bullbull Giardia amp Virus InactivationGiardia amp Virus Inactivation

bullbull Oxidation Oxidation -- Organics Fe amp MnOrganics Fe amp Mn

bullbull Wastewater disinfectionWastewater disinfection

bullbull BOD COD and TOC reductionBOD COD and TOC reduction

Applications of Ozone

Wastewater Treatmentbull Disinfection of Secondary and Tertiary Effluentsbull Color Reductionbull Color Reductionbull TOC Oxidation (Industrial)bull Oxidation of Odor Causing Compoundsbull Oxidation of Endocrine Disruptors (EDCrsquos) and p ( )

Pharmaceutically Active Compounds (PACrsquos)

Applications of Ozone

What are Endocrine Disruptors (EDCrsquos) and What are Endocrine Disruptors (EDCrsquos) and Ph ti ll A ti C d (PACrsquo )Ph ti ll A ti C d (PACrsquo )Pharmaceutically Active Compounds (PACrsquos)Pharmaceutically Active Compounds (PACrsquos)

bullbull EDCrsquosEDCrsquos andand PACrsquosPACrsquos areare NaturallyNaturally andand SyntheticSyntheticdd th tth t ff tff t thth b lb l llcompoundscompounds thatthat maymay affectaffect thethe balancebalance oror normalnormal

functionsfunctions inin animalsanimals andand humanshumans

What can EDCrsquos and PACrsquos doWhat can EDCrsquos and PACrsquos do

bullbull Even in very small concentrations these compounds Even in very small concentrations these compounds y py pcan can disruptdisrupt normal bodily functionsnormal bodily functions

bullbull ManMan--made chemicals can trick the bodies endocrine made chemicals can trick the bodies endocrine system system

Applications of Ozone

Examples of Endocrine Disruptors1000rsquos of compounds that may be Investigated as EDCs ndash Some examples are

bullbull Synthetic HormonesSynthetic Hormonesbullbull Naturally Occurring Estrogens Naturally Occurring Estrogens

Health and Beauty AidsHealth and Beauty Aidsbullbull Health and Beauty AidsHealth and Beauty Aidsbullbull SolventsSolventsbullbull PesticidesPesticidesbullbull SurfactantsSurfactantsbullbull PlasticsPlastics

F i idF i idbullbull FungicidesFungicides

Ozone Water TreatmentOzone Water Treatment

Ozone Ozone -- Industrial ApplicationsIndustrial Applications-- Ultrapure Water for Pharmaceutical ApplicationsUltrapure Water for Pharmaceutical Applications

-- Wastewater disinfection color removalWastewater disinfection color removal

-- Soil and Groundwater Remediation Soil and Groundwater Remediation

-- Cooling Tower Water TreatmentCooling Tower Water Treatment

-- Food ProcessingFood Processing

-- Aquaculture AquariumsAquaculture AquariumsAquaculture AquariumsAquaculture Aquariums

-- Beverage ApplicationsBeverage Applications

P l amp P Bl hiP l amp P Bl hi-- Pulp amp Paper BleachingPulp amp Paper Bleaching

High Purity OzonationHigh Purity Ozonation

Microchip manufacturingMicrochip manufacturing

What are the current issues in large-scale gozone generationg

Experimental Setup

Front view of the two units after the redesign and reworking ofthe gas water and instruments connectionsthe gas water and instruments connections

Experimental Setup

Top view of the twoexperimental unitsexperimental unitsSpectroscope (notshown) is to the left ofthe DBD The units weredifferent with respect todifferent with respect totheir electrodes onehad only the electrodecoated with thedielectric (ldquosingle-dielectric ( single-coatedrdquo) the other onehad the electrode andthe anode coated withthe dielectric (ldquodouble-the dielectric ( double-coatedrdquo)

Basics Generation of OzoneBasics Generation of Ozone

SpectroscopyPlasma

Plasma Absorption SpectroscopyPlasma Absorption Spectroscopy

Infrared Absorption SpectroscopyInfrared Absorption Spectroscopy

IR spectra in pure oxygen (black curve) and at approximately 10wt N2 admixture (red line) N2O5 peaks appear at124 1 d 1 2 11245 cm-1 and at 1725 cm-1

Infrared Absorption SpectroscopyInfrared Absorption Spectroscopy

IR spectra of several methane variations The green curve envelopes all of the methane peaks at 1325 cm-1recorded at smaller methane admixtures Simultaneously the N2O5 peaks disappear as the methane peaks appear

N2O5 FormationN2O5 Formation2 52 5p=2 bara cwt=20degC q=35kWm2 f=1450Hz

45N2O5 AT95

30

35

40

N

2 B

lend

ing

N2O AT95N2O5 IGSN2O IGSN2O5 LGN2O LG

1 5

20

25

nt [p

pmV]

3

wt

05

10

15

NO

x co

nten

005 7 9 11 13 15 17

ozone conc [wt]

Amount of formed N2O5 and N2O as a function of ozone concentration at 3 wt of nitrogen admixture and fori l dvarious electrode arrangements

Plasma Emission SpectroscopyPlasma Emission Spectroscopyp pyp py

Relative Emissions of the Ozonizer plasmaRelative Emissions of the Ozonizer plasma

Region 300- 850 nm from individual (calibrated) regions (smoothed by PeakFit) Single-coated ozone generator Inlet side

3 5E+06

30E+06

35E+06

7 9

20E+06

25E+06

nten

sity

au

2

311 12

10E+06

15E+06

In 4

5

6 8 10

14

15

16

17

00E+00

50E+05

280 300 320 340 360 380 400 420 440 460 480 500 520 540 560 580 600 620 640 660 680 700 720 740 760 780 800 820 840 860

Wavelength nm

1 13

Wavelength nm

Absolute Emission of the DBD PlasmaAbsolute Emission of the DBD Plasma

Intensities in (O2+3 wtN2) plasma

1 20E+04

100E+04

120E+04

600E+03

800E+03

nten

sity

(au

)

200E+03

400E+03

In

O(777)

000E+00200 250 300 350 400 450 500 550 600 650 700 750 800 850

Wavelength nm

Intensities in 3 wtN2+O2 plasmaIntensities in 3 wtN2+O2 plasma

Plasma Chemistry in OzonizersPlasma Chemistry in Ozonizers

Dry Air O2 N2

e - e -

O N2 N O2

O3 NO

O2 N O2

O3

N

3

NO2

O2 O3

NO

N

NO2 O3

N2O

NO3 N

N2O4

NO2

NO2

N2O5

NO3

Primary electron-driven chemical reactions leading to the formation of N2O5 and N2O in a dry air plasma

Plasma emission diagnostics role of N2Plasma emission diagnostics role of N2

Dry Air O2 N2

e - e -

O N2 N O2

O3 NO

O2 N O2

O3

O

N

ON

NO2

O2O3

N

NO N

NO2 O3

N2O

NO3 N

N2O4

NO2

NO2

N2O5

NO3

ONbullWith N2 present ndash less oxygen atoms are formed However the difference in intensity is

very small

Modeling of plasma chemistry incl the NxOy chemistry up to N2O5 for different Oxygen Nitrogen mixtures varying power deposition scenarios

and initial ozone background concentrations (up to 15) previously done

The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation

The role of N2 must be related to its by-products reacting on the surface of the electrodeThe role of N2 must be related to its by-products reacting on the surface of the electrode

The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established

Ab 8 t f O

The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established

Ab 8 t f OAbove 8 wt of O3

1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)

Above 8 wt of O3

1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)case without pampp)

2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of the

case without pampp)

2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of thethem A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface

them A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface

The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation

Three possibilities have to be considered for the oxygen-fedozone generator

Three possibilities have to be considered for the oxygen-fedozone generatorozone generator

bull Excited N2 molecules lead to an increased O2 dissociation in

ozone generator

bull Excited N2 molecules lead to an increased O2 dissociation in2 2such case an increased efficiency is correlated to the N2admixture

2 2such case an increased efficiency is correlated to the N2admixture

bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial

bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial

bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2

bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2g p g 3 pp y 2g p g 3 pp y 2

Effect of methane on ozone efficiency and specific powerEffect of methane on ozone efficiency and specific power

Effect of Methane on Ozone Content in Outlet Gas and on Specific Power Pure O2

13 12

10

11

12

t 8

10

8

9

10

ne c

onte

nt w

t

6

8

ecifi

c po

wer

kW

hlb

5

6

7

Ozo

n

2

4 Spe

400E+00 20E+03 40E+03 60E+03 80E+03 10E+04 12E+04

Methane in feedgas ppm

0

Ozone content in the outlet gas Specif ic pow er of the ozone generatorg p p g

Effects of N2 and CH4Effects of N2 and CH4

Pi t f h t lli N O t tPicture of an amorphous-crystalline N2O5 structurecaptured at the Orlando Skylake water plant in 2006

Plasma Chemistry with CH4 Impurities

OxygenO2 N2

e - e -

CHO N2

NO2

O NO

O2 N O2 O3

NOH

CH4e-

O3 NO

NO2

O2O3NO N

NO2 O

NO2

NO2

N2ONO3

N

O3

NO2

NO

HNO3

N2O4

N2O5

NO2

NO3

N2O5

Effect of methane on the electrode surfaces

a) b)

Inlet Outlet Outlet

) d)

I l t I l t

c) d)

Electrode of the ozone generator afterseveral hours in CH8O2 and up to 2 wt of methane (a b c)

Inlet Inlet

three hours in CH8O2+traces of N2 and up to 1 wt of methane (d) Visible change of discharge character at about 13 length of electrode (a d)

Kinetics of CHx Conversion without N2

conversion by collisions

O2 + CHx 12wt O3 + CO2 +H2O

deposition vaporizationby sputtering

ibl b l 1000 CHreversible process below 1000ppm CH4

Effect of water on electrode surface with N2

Inlet

OutletOutlet

Electrode of the ozone generator after several hours in H OO N

Inlet

Electrode of the ozone generator after several hours in H2OO2N2

Effect of water on electrode surface

Long term effect (800 hrs) of H2OO2N2

Kinetics of CHx Conversion with N2

conversion by collisionsHNO3 formation

O2 + N2 +CHx 12wtO2 + CO2 +H2O + HNO3

deposition vaporizationby sputtering

H2O + HNO3

by sputtering

irreversible process above a N2 threshold () ltlt 1000ppm N2

sticky deposit

p 2 ( ) pp 2 any CH4 concentration (60ppm)

Plasma Chemistry with CH4 ImpuritiesPlasma Chemistry with CH4 Impurities4

bull Formation of NO and NO2 depends on O3 N2 and gas temperature Conclusion N2 admixture is the key factor

SummarySummaryyyThe mechanisms of formed NOx by-products follows the sameThe mechanisms of formed NOx by-products follows the sameprinciples as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentration

principles as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentrationozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)

ozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)g p ( g p )

The conversion of methane to OH and H2O is found to depend on

g p ( g p )

The conversion of methane to OH and H2O is found to depend ondissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)

dissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)discharge gap)discharge gap)

How do you optimize an ozone generatorg

Scientific ApproachScientific ApproachTheoretical Experimental

pppp

c [wt]

f [Hz]

c [wt]

f [Hz]

[kW]UUUβ1

1Cf4αPn

1iiminpeakimin

iiD

q [kWm2]q [kWm2]

150

180

][V]voltagepeakUpeak

[]cylinder perslicesofamountnsliceii

whereth

09 00

30

60

90

120

effic

ienc

y [

][0tdj t bl[F]sliceisdielectricofecapacitancC

[Hz]frequencyf[V]sliceivoltageminimumiUmin

thiD

th

10

28

46

64

82

39

107

176

244 power density

[kWm2]

ozone conc [wt][]CCβ

][0parameteradjustableα

iDiGi

Impact of Power Inductionp

350

400

wer

200

250

300

App

lied

Pow

Arr C 2Arr D +0

Arr E +45Arr F +7

Arr G +3

5 0

100

150

Frac

tion

of

1 2 3 4

ReferenceArr B unstable

Arr C -2

00

50

4Position (1inlet 4outlet)

Experimental Test Rigp g

Experimental Test Rigp g

Outer grounded electrode (left picture) and the dielectric covered inner electrodes (right) d e ect c cove ed e e ect odes ( g t)

Reference (Traditional) Arrangement

Inlet OutletGas flow direction

Optimized Arrangement

Inlet OutletGas flow direction

Intelligent Gap System (IGS)g p y ( )

Molecular Oxygen (O2) Ozone (O3)

O2 O3

yg ( 2) ( 3)

Particle Size SynthesisParticle Size SynthesisByBy--Products Cluster FormationProducts Cluster Formationyy

high diffusion and deposition to surfaces

low diffusion rate good transport

high sedimentation on the structurehigh sedimentation on the structure

Degreacutemont Technologies ndash OzoniaIntelligent Gap SystemIntelligent Gap System

G Vezzuacute JL Lopez A Freilich and K Becker Optimizationof Large-Scale Ozone Generators IEEE Transactions onPlasma Science Vol 37 No 6 p 890-896 (2009)

ConclusionsConclusionsConclusionsConclusionsFundamentals of ozone synthesis in a DBD plasmay p

ndash Highly filamented DBD discharges are best-suitedfor the production of ozone concentrations in therange of 6 to 14 wtrange of 6 to 14 wt

ndash The preferred characteristic of the microdischargesare Townsend-like at reduced electric fields Enaround 190 Townsend

ndash Detrimental side-effects induced by by-productscan be avoided by a proper design of the electrodecan be avoided by a proper design of the electrodearrangement The phenomenon is related to thediffusion rates of formed by-product clusters

ConclusionsConclusionsConclusionsConclusionsBenefits from DBD microplasma tailoring

ndash Reduced power consumption of up to 10 improvement

ndash Increased ozone concentrations of up to 14 now achievable

ndash Improved neutralization and conditioning of detrimental by-products

ndash Reduced system capital and operational cost

New technologies to improve ozone p

generatorg

HV Pulsed Power SwitchingHV Pulsed Power Switching

Microchannel Generation of Ozone

Channel ArrayChannel Array

Microchannel

330 microm 230 microm

Some Cap-DBD Devices Operating in Air

Increase of 60 of

Spacing 225 μmof 60 of plasma

No space

Cap‐DBD ozone generation

bull Ozone concentration is evaluated via Eco S d l UV 100 O A l (0 01Sensors model UV-100 Ozone Analyzer (001 ndash 900 ppm wiht an accuracy of plusmn2)

bull Three reactors 6 tubings 6rdquo with spacings of 0 μm 225 μm and 500 μm running at 3 kV μ μ μ g

SpacingOzone Concentration

3 kV rms 4 kV rms3 kV rms 4 kV rms

0 μm 660 ppm

225 μm 550 ppm

For a device of such small scale these ozone levels are promising

500 μm 380 ppm

J Mahoney W Zhu VS Johnson KH Becker and JL Lopez Electrical and optical emissionmeasurements of a capillary dielectric barrier discharge European Physics Journal D Vol 60 441-447(2010)

QuestionsQuestions

Thank YouFor more informationProf Jose L Lopez PhD

Thank YouFor more informationDepartment of Physics

Telephone (973) 761-9057Email joselopez1shuedu

Website wwwshueduacademicsartsciphysicsWebsite wwwshueduacademicsartsciphysics

Page 38: Dielectric Barrier Discharge (DBD) & Progress in Large ...bonitz/si12/talks/august_8/lopez_si12.pdf · Dielectric Barrier Discharge (DBD) & Progress in Large-Scale Ozone Generation

How A Plasma Display Work

Plasma Display TelevisionsPlasma Display Televisions

Ozone Generator

3 O 2 O

Dielectric Barrier Discharge

3 O2 2 O3

OO22 OO33++OO22Ondash ndashO3O2

O2O2

Ondash ndash

endash O2Ondash ndash O2endash

O3

O3O2O2 O2

HeatHeatHeatHeat

Properties of Ozone (O3)

T i t i f f Tri-atomic form of oxygen

Most powerful commercial oxidizing agent

Unstable - must be generated and used onsite

Limited solubility in water but more so than oxygenLimited solubility in water but more so than oxygen

Leaves a dissolved residual which ultimately converts back to oxygenconverts back to oxygen

Discharge Tubes in Ozone GeneratorsDischarge Tubes in Ozone Generators

Traditional

Ozone Generator

with Glass Tubes

Generation of OzoneGeneration of Ozone

Generation of OzoneAdvantages of Enamel Dielectrics

Proven Patented Designbull Simplicity

Si l Di l i Cbull Single Dielectric Componentndash Reduced number of Dielectrics

bull Safety ndash Lower operating voltage

(lt 4000 V)bull Reliabilty

ndash Fused Dielectrics ensure continuous production

bull Lowest Power Consumption Operational Savingsndash Operational Savings

Modern Ozone GeneratorModern Ozone Generator

Ozonia Advanced Technology Ozone GeneratorOzone Generator

Generation of OzoneGeneration of Ozone

Generation of Ozone

Power Supply UnitPower Supply Unit

IGBT Inverter CircuitMain Circuit Breaker

HV 480 Volts60 Hz3 Phase Supply

C I

450KVAPow er to

GeneratorFILTER

CONVERTER INVERTERTRANSFORMER

C I450KVA Power Stage

CONTACTOR

bull Latest in Power Semiconductor Technology Modular Design

bull Utilizes IGBTrsquos (Insulated Gate Bi‐Polar Transistors) Converter and Inverter Components

Ozone Water Treatment

B bbl Diff iB bbl Diff iBubble DiffusionBubble Diffusion

Easy to use

Low energy usage Low energy usage

Mass transfer efficiencies to gt 90

Ozone Process Flow DiagramOzone Process Flow DiagramVent to

Atmosphere

O OOxygen

Off-Gas Blower

Ozone Destruct Unit

10 12

O3O2

LOX

10-12 O3

Ozone Generators

Ozone Contact ChamberLOX T k Generators Chamber

VaporizersLOX Tank

Municipal Ozone Installations

Ozonia Installations Ozone Plant Size [lbday] Start-Up DateKey Ozonia Installations (Partial List)

Los Angeles CA 10000 1986Fairfax VA ndash Corbalis 9000 2003MWD CA ndash Mills 9 000 2003

Ozonia Installations Ozone Plant Size [lbday] Start Up Date

MWD CA Mills 9000 2003Fairfax Co VA ndash Griffith 9000 2004MWD CA ndash Jensen 18750 2005Indianapolis IN ndash Belmont AWT 12000 2007I di li IN 12 000 2007Indianapolis IN ndash Southport AWT 12000 2007MWD CA ndash Diemer 13400 2008MWD CA ndash Weymouth 13400 2009

Ozonia North America - Potable Water SummaryTotal Number of Installations 90Total Installed Production gt 265000 lbsdayTotal Installed Production 265000 lbsday

Revision -B

Ozone Water TreatmentOzone Water Treatment

MWD Mills WTP - California

3 3 000 lbsda of o one3 3 000 lbsda of o one3 x 3000 lbsday of ozone3 x 3000 lbsday of ozone

Ozone Water TreatmentOzone Water TreatmentOzone Ozone -- How it worksHow it works

OxidantOxidant DisinfectantDisinfectant

bullbull Breaks double carbon Breaks double carbon bondsbonds

bullbull Kills by cell lysing or Kills by cell lysing or causing the cell wall tocausing the cell wall tobondsbonds

bullbull Creates OHCreates OHbullbull radicals radicals which break higher carbon which break higher carbon

causing the cell wall to causing the cell wall to rupture rupture

bullbull AttacksAttacks allall bacteriabacteriabondsbondsbullbull Increased temp and pH Increased temp and pH

accelerates Oaccelerates O33

Attacks Attacks allall bacteria bacteria virus cysts and spores virus cysts and spores in varying degreesin varying degreesaccelerates Oaccelerates O33

decomposition to OHdecomposition to OHbullbull

Micro-organism DNA

Capsule AdenineAdenine

Cell wall ThymineThymine

CytosineCytosine

GuanineGuanine

NuclearmaterialCellmembrane

material

Typical Bacterium DNA

Microbial Growth at Various Ozone ConcentrationsConcentrations

Growth likely

Growth possibleGrowth possible

NO GROWTH

0004 0008 0012 0016 0020

Ozone concentration (mgl)Ozone concentration (mgl)

Typical Water Treatment UsageTypical Water Treatment Usage

Application O3 mgl Contact timeUltra Pure Water 005 - 025 sec ndash min

Water bottling 04 ndash 10 5 ndash 10 min

Swimming pools ampspas

01 ndash 075 4 minutes

Potable taste amp odor 15 ndash 50 5 ndash 10 mindisinfection

Microfloculation 10 ndash 30 5 ndash 10 min

Lignin amp tammin 3 0 10 0 10 30 minLignin amp tamminremoval

30 ndash 100 10 ndash 30 min

Municipal wastewater 50 ndash 150+ 15 ndash 30 min

Ozone Water TreatmentOzone Water TreatmentOzone Ozone ndashndash Municipal ApplicationsMunicipal Applications

bullbull Taste and OdorTaste and Odor

bullbull Color RemovalColor Removal

bullbull Disinfection Without Trihalomethanes (THMs)Disinfection Without Trihalomethanes (THMs)

bullbull Improved Filtration Efficiency and FlocculationImproved Filtration Efficiency and Flocculation

bullbull Cryptosporidium DeactivationCryptosporidium Deactivation

bullbull Giardia amp Virus InactivationGiardia amp Virus Inactivation

bullbull Oxidation Oxidation -- Organics Fe amp MnOrganics Fe amp Mn

bullbull Wastewater disinfectionWastewater disinfection

bullbull BOD COD and TOC reductionBOD COD and TOC reduction

Applications of Ozone

Wastewater Treatmentbull Disinfection of Secondary and Tertiary Effluentsbull Color Reductionbull Color Reductionbull TOC Oxidation (Industrial)bull Oxidation of Odor Causing Compoundsbull Oxidation of Endocrine Disruptors (EDCrsquos) and p ( )

Pharmaceutically Active Compounds (PACrsquos)

Applications of Ozone

What are Endocrine Disruptors (EDCrsquos) and What are Endocrine Disruptors (EDCrsquos) and Ph ti ll A ti C d (PACrsquo )Ph ti ll A ti C d (PACrsquo )Pharmaceutically Active Compounds (PACrsquos)Pharmaceutically Active Compounds (PACrsquos)

bullbull EDCrsquosEDCrsquos andand PACrsquosPACrsquos areare NaturallyNaturally andand SyntheticSyntheticdd th tth t ff tff t thth b lb l llcompoundscompounds thatthat maymay affectaffect thethe balancebalance oror normalnormal

functionsfunctions inin animalsanimals andand humanshumans

What can EDCrsquos and PACrsquos doWhat can EDCrsquos and PACrsquos do

bullbull Even in very small concentrations these compounds Even in very small concentrations these compounds y py pcan can disruptdisrupt normal bodily functionsnormal bodily functions

bullbull ManMan--made chemicals can trick the bodies endocrine made chemicals can trick the bodies endocrine system system

Applications of Ozone

Examples of Endocrine Disruptors1000rsquos of compounds that may be Investigated as EDCs ndash Some examples are

bullbull Synthetic HormonesSynthetic Hormonesbullbull Naturally Occurring Estrogens Naturally Occurring Estrogens

Health and Beauty AidsHealth and Beauty Aidsbullbull Health and Beauty AidsHealth and Beauty Aidsbullbull SolventsSolventsbullbull PesticidesPesticidesbullbull SurfactantsSurfactantsbullbull PlasticsPlastics

F i idF i idbullbull FungicidesFungicides

Ozone Water TreatmentOzone Water Treatment

Ozone Ozone -- Industrial ApplicationsIndustrial Applications-- Ultrapure Water for Pharmaceutical ApplicationsUltrapure Water for Pharmaceutical Applications

-- Wastewater disinfection color removalWastewater disinfection color removal

-- Soil and Groundwater Remediation Soil and Groundwater Remediation

-- Cooling Tower Water TreatmentCooling Tower Water Treatment

-- Food ProcessingFood Processing

-- Aquaculture AquariumsAquaculture AquariumsAquaculture AquariumsAquaculture Aquariums

-- Beverage ApplicationsBeverage Applications

P l amp P Bl hiP l amp P Bl hi-- Pulp amp Paper BleachingPulp amp Paper Bleaching

High Purity OzonationHigh Purity Ozonation

Microchip manufacturingMicrochip manufacturing

What are the current issues in large-scale gozone generationg

Experimental Setup

Front view of the two units after the redesign and reworking ofthe gas water and instruments connectionsthe gas water and instruments connections

Experimental Setup

Top view of the twoexperimental unitsexperimental unitsSpectroscope (notshown) is to the left ofthe DBD The units weredifferent with respect todifferent with respect totheir electrodes onehad only the electrodecoated with thedielectric (ldquosingle-dielectric ( single-coatedrdquo) the other onehad the electrode andthe anode coated withthe dielectric (ldquodouble-the dielectric ( double-coatedrdquo)

Basics Generation of OzoneBasics Generation of Ozone

SpectroscopyPlasma

Plasma Absorption SpectroscopyPlasma Absorption Spectroscopy

Infrared Absorption SpectroscopyInfrared Absorption Spectroscopy

IR spectra in pure oxygen (black curve) and at approximately 10wt N2 admixture (red line) N2O5 peaks appear at124 1 d 1 2 11245 cm-1 and at 1725 cm-1

Infrared Absorption SpectroscopyInfrared Absorption Spectroscopy

IR spectra of several methane variations The green curve envelopes all of the methane peaks at 1325 cm-1recorded at smaller methane admixtures Simultaneously the N2O5 peaks disappear as the methane peaks appear

N2O5 FormationN2O5 Formation2 52 5p=2 bara cwt=20degC q=35kWm2 f=1450Hz

45N2O5 AT95

30

35

40

N

2 B

lend

ing

N2O AT95N2O5 IGSN2O IGSN2O5 LGN2O LG

1 5

20

25

nt [p

pmV]

3

wt

05

10

15

NO

x co

nten

005 7 9 11 13 15 17

ozone conc [wt]

Amount of formed N2O5 and N2O as a function of ozone concentration at 3 wt of nitrogen admixture and fori l dvarious electrode arrangements

Plasma Emission SpectroscopyPlasma Emission Spectroscopyp pyp py

Relative Emissions of the Ozonizer plasmaRelative Emissions of the Ozonizer plasma

Region 300- 850 nm from individual (calibrated) regions (smoothed by PeakFit) Single-coated ozone generator Inlet side

3 5E+06

30E+06

35E+06

7 9

20E+06

25E+06

nten

sity

au

2

311 12

10E+06

15E+06

In 4

5

6 8 10

14

15

16

17

00E+00

50E+05

280 300 320 340 360 380 400 420 440 460 480 500 520 540 560 580 600 620 640 660 680 700 720 740 760 780 800 820 840 860

Wavelength nm

1 13

Wavelength nm

Absolute Emission of the DBD PlasmaAbsolute Emission of the DBD Plasma

Intensities in (O2+3 wtN2) plasma

1 20E+04

100E+04

120E+04

600E+03

800E+03

nten

sity

(au

)

200E+03

400E+03

In

O(777)

000E+00200 250 300 350 400 450 500 550 600 650 700 750 800 850

Wavelength nm

Intensities in 3 wtN2+O2 plasmaIntensities in 3 wtN2+O2 plasma

Plasma Chemistry in OzonizersPlasma Chemistry in Ozonizers

Dry Air O2 N2

e - e -

O N2 N O2

O3 NO

O2 N O2

O3

N

3

NO2

O2 O3

NO

N

NO2 O3

N2O

NO3 N

N2O4

NO2

NO2

N2O5

NO3

Primary electron-driven chemical reactions leading to the formation of N2O5 and N2O in a dry air plasma

Plasma emission diagnostics role of N2Plasma emission diagnostics role of N2

Dry Air O2 N2

e - e -

O N2 N O2

O3 NO

O2 N O2

O3

O

N

ON

NO2

O2O3

N

NO N

NO2 O3

N2O

NO3 N

N2O4

NO2

NO2

N2O5

NO3

ONbullWith N2 present ndash less oxygen atoms are formed However the difference in intensity is

very small

Modeling of plasma chemistry incl the NxOy chemistry up to N2O5 for different Oxygen Nitrogen mixtures varying power deposition scenarios

and initial ozone background concentrations (up to 15) previously done

The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation

The role of N2 must be related to its by-products reacting on the surface of the electrodeThe role of N2 must be related to its by-products reacting on the surface of the electrode

The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established

Ab 8 t f O

The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established

Ab 8 t f OAbove 8 wt of O3

1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)

Above 8 wt of O3

1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)case without pampp)

2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of the

case without pampp)

2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of thethem A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface

them A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface

The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation

Three possibilities have to be considered for the oxygen-fedozone generator

Three possibilities have to be considered for the oxygen-fedozone generatorozone generator

bull Excited N2 molecules lead to an increased O2 dissociation in

ozone generator

bull Excited N2 molecules lead to an increased O2 dissociation in2 2such case an increased efficiency is correlated to the N2admixture

2 2such case an increased efficiency is correlated to the N2admixture

bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial

bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial

bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2

bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2g p g 3 pp y 2g p g 3 pp y 2

Effect of methane on ozone efficiency and specific powerEffect of methane on ozone efficiency and specific power

Effect of Methane on Ozone Content in Outlet Gas and on Specific Power Pure O2

13 12

10

11

12

t 8

10

8

9

10

ne c

onte

nt w

t

6

8

ecifi

c po

wer

kW

hlb

5

6

7

Ozo

n

2

4 Spe

400E+00 20E+03 40E+03 60E+03 80E+03 10E+04 12E+04

Methane in feedgas ppm

0

Ozone content in the outlet gas Specif ic pow er of the ozone generatorg p p g

Effects of N2 and CH4Effects of N2 and CH4

Pi t f h t lli N O t tPicture of an amorphous-crystalline N2O5 structurecaptured at the Orlando Skylake water plant in 2006

Plasma Chemistry with CH4 Impurities

OxygenO2 N2

e - e -

CHO N2

NO2

O NO

O2 N O2 O3

NOH

CH4e-

O3 NO

NO2

O2O3NO N

NO2 O

NO2

NO2

N2ONO3

N

O3

NO2

NO

HNO3

N2O4

N2O5

NO2

NO3

N2O5

Effect of methane on the electrode surfaces

a) b)

Inlet Outlet Outlet

) d)

I l t I l t

c) d)

Electrode of the ozone generator afterseveral hours in CH8O2 and up to 2 wt of methane (a b c)

Inlet Inlet

three hours in CH8O2+traces of N2 and up to 1 wt of methane (d) Visible change of discharge character at about 13 length of electrode (a d)

Kinetics of CHx Conversion without N2

conversion by collisions

O2 + CHx 12wt O3 + CO2 +H2O

deposition vaporizationby sputtering

ibl b l 1000 CHreversible process below 1000ppm CH4

Effect of water on electrode surface with N2

Inlet

OutletOutlet

Electrode of the ozone generator after several hours in H OO N

Inlet

Electrode of the ozone generator after several hours in H2OO2N2

Effect of water on electrode surface

Long term effect (800 hrs) of H2OO2N2

Kinetics of CHx Conversion with N2

conversion by collisionsHNO3 formation

O2 + N2 +CHx 12wtO2 + CO2 +H2O + HNO3

deposition vaporizationby sputtering

H2O + HNO3

by sputtering

irreversible process above a N2 threshold () ltlt 1000ppm N2

sticky deposit

p 2 ( ) pp 2 any CH4 concentration (60ppm)

Plasma Chemistry with CH4 ImpuritiesPlasma Chemistry with CH4 Impurities4

bull Formation of NO and NO2 depends on O3 N2 and gas temperature Conclusion N2 admixture is the key factor

SummarySummaryyyThe mechanisms of formed NOx by-products follows the sameThe mechanisms of formed NOx by-products follows the sameprinciples as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentration

principles as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentrationozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)

ozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)g p ( g p )

The conversion of methane to OH and H2O is found to depend on

g p ( g p )

The conversion of methane to OH and H2O is found to depend ondissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)

dissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)discharge gap)discharge gap)

How do you optimize an ozone generatorg

Scientific ApproachScientific ApproachTheoretical Experimental

pppp

c [wt]

f [Hz]

c [wt]

f [Hz]

[kW]UUUβ1

1Cf4αPn

1iiminpeakimin

iiD

q [kWm2]q [kWm2]

150

180

][V]voltagepeakUpeak

[]cylinder perslicesofamountnsliceii

whereth

09 00

30

60

90

120

effic

ienc

y [

][0tdj t bl[F]sliceisdielectricofecapacitancC

[Hz]frequencyf[V]sliceivoltageminimumiUmin

thiD

th

10

28

46

64

82

39

107

176

244 power density

[kWm2]

ozone conc [wt][]CCβ

][0parameteradjustableα

iDiGi

Impact of Power Inductionp

350

400

wer

200

250

300

App

lied

Pow

Arr C 2Arr D +0

Arr E +45Arr F +7

Arr G +3

5 0

100

150

Frac

tion

of

1 2 3 4

ReferenceArr B unstable

Arr C -2

00

50

4Position (1inlet 4outlet)

Experimental Test Rigp g

Experimental Test Rigp g

Outer grounded electrode (left picture) and the dielectric covered inner electrodes (right) d e ect c cove ed e e ect odes ( g t)

Reference (Traditional) Arrangement

Inlet OutletGas flow direction

Optimized Arrangement

Inlet OutletGas flow direction

Intelligent Gap System (IGS)g p y ( )

Molecular Oxygen (O2) Ozone (O3)

O2 O3

yg ( 2) ( 3)

Particle Size SynthesisParticle Size SynthesisByBy--Products Cluster FormationProducts Cluster Formationyy

high diffusion and deposition to surfaces

low diffusion rate good transport

high sedimentation on the structurehigh sedimentation on the structure

Degreacutemont Technologies ndash OzoniaIntelligent Gap SystemIntelligent Gap System

G Vezzuacute JL Lopez A Freilich and K Becker Optimizationof Large-Scale Ozone Generators IEEE Transactions onPlasma Science Vol 37 No 6 p 890-896 (2009)

ConclusionsConclusionsConclusionsConclusionsFundamentals of ozone synthesis in a DBD plasmay p

ndash Highly filamented DBD discharges are best-suitedfor the production of ozone concentrations in therange of 6 to 14 wtrange of 6 to 14 wt

ndash The preferred characteristic of the microdischargesare Townsend-like at reduced electric fields Enaround 190 Townsend

ndash Detrimental side-effects induced by by-productscan be avoided by a proper design of the electrodecan be avoided by a proper design of the electrodearrangement The phenomenon is related to thediffusion rates of formed by-product clusters

ConclusionsConclusionsConclusionsConclusionsBenefits from DBD microplasma tailoring

ndash Reduced power consumption of up to 10 improvement

ndash Increased ozone concentrations of up to 14 now achievable

ndash Improved neutralization and conditioning of detrimental by-products

ndash Reduced system capital and operational cost

New technologies to improve ozone p

generatorg

HV Pulsed Power SwitchingHV Pulsed Power Switching

Microchannel Generation of Ozone

Channel ArrayChannel Array

Microchannel

330 microm 230 microm

Some Cap-DBD Devices Operating in Air

Increase of 60 of

Spacing 225 μmof 60 of plasma

No space

Cap‐DBD ozone generation

bull Ozone concentration is evaluated via Eco S d l UV 100 O A l (0 01Sensors model UV-100 Ozone Analyzer (001 ndash 900 ppm wiht an accuracy of plusmn2)

bull Three reactors 6 tubings 6rdquo with spacings of 0 μm 225 μm and 500 μm running at 3 kV μ μ μ g

SpacingOzone Concentration

3 kV rms 4 kV rms3 kV rms 4 kV rms

0 μm 660 ppm

225 μm 550 ppm

For a device of such small scale these ozone levels are promising

500 μm 380 ppm

J Mahoney W Zhu VS Johnson KH Becker and JL Lopez Electrical and optical emissionmeasurements of a capillary dielectric barrier discharge European Physics Journal D Vol 60 441-447(2010)

QuestionsQuestions

Thank YouFor more informationProf Jose L Lopez PhD

Thank YouFor more informationDepartment of Physics

Telephone (973) 761-9057Email joselopez1shuedu

Website wwwshueduacademicsartsciphysicsWebsite wwwshueduacademicsartsciphysics

Page 39: Dielectric Barrier Discharge (DBD) & Progress in Large ...bonitz/si12/talks/august_8/lopez_si12.pdf · Dielectric Barrier Discharge (DBD) & Progress in Large-Scale Ozone Generation

Plasma Display TelevisionsPlasma Display Televisions

Ozone Generator

3 O 2 O

Dielectric Barrier Discharge

3 O2 2 O3

OO22 OO33++OO22Ondash ndashO3O2

O2O2

Ondash ndash

endash O2Ondash ndash O2endash

O3

O3O2O2 O2

HeatHeatHeatHeat

Properties of Ozone (O3)

T i t i f f Tri-atomic form of oxygen

Most powerful commercial oxidizing agent

Unstable - must be generated and used onsite

Limited solubility in water but more so than oxygenLimited solubility in water but more so than oxygen

Leaves a dissolved residual which ultimately converts back to oxygenconverts back to oxygen

Discharge Tubes in Ozone GeneratorsDischarge Tubes in Ozone Generators

Traditional

Ozone Generator

with Glass Tubes

Generation of OzoneGeneration of Ozone

Generation of OzoneAdvantages of Enamel Dielectrics

Proven Patented Designbull Simplicity

Si l Di l i Cbull Single Dielectric Componentndash Reduced number of Dielectrics

bull Safety ndash Lower operating voltage

(lt 4000 V)bull Reliabilty

ndash Fused Dielectrics ensure continuous production

bull Lowest Power Consumption Operational Savingsndash Operational Savings

Modern Ozone GeneratorModern Ozone Generator

Ozonia Advanced Technology Ozone GeneratorOzone Generator

Generation of OzoneGeneration of Ozone

Generation of Ozone

Power Supply UnitPower Supply Unit

IGBT Inverter CircuitMain Circuit Breaker

HV 480 Volts60 Hz3 Phase Supply

C I

450KVAPow er to

GeneratorFILTER

CONVERTER INVERTERTRANSFORMER

C I450KVA Power Stage

CONTACTOR

bull Latest in Power Semiconductor Technology Modular Design

bull Utilizes IGBTrsquos (Insulated Gate Bi‐Polar Transistors) Converter and Inverter Components

Ozone Water Treatment

B bbl Diff iB bbl Diff iBubble DiffusionBubble Diffusion

Easy to use

Low energy usage Low energy usage

Mass transfer efficiencies to gt 90

Ozone Process Flow DiagramOzone Process Flow DiagramVent to

Atmosphere

O OOxygen

Off-Gas Blower

Ozone Destruct Unit

10 12

O3O2

LOX

10-12 O3

Ozone Generators

Ozone Contact ChamberLOX T k Generators Chamber

VaporizersLOX Tank

Municipal Ozone Installations

Ozonia Installations Ozone Plant Size [lbday] Start-Up DateKey Ozonia Installations (Partial List)

Los Angeles CA 10000 1986Fairfax VA ndash Corbalis 9000 2003MWD CA ndash Mills 9 000 2003

Ozonia Installations Ozone Plant Size [lbday] Start Up Date

MWD CA Mills 9000 2003Fairfax Co VA ndash Griffith 9000 2004MWD CA ndash Jensen 18750 2005Indianapolis IN ndash Belmont AWT 12000 2007I di li IN 12 000 2007Indianapolis IN ndash Southport AWT 12000 2007MWD CA ndash Diemer 13400 2008MWD CA ndash Weymouth 13400 2009

Ozonia North America - Potable Water SummaryTotal Number of Installations 90Total Installed Production gt 265000 lbsdayTotal Installed Production 265000 lbsday

Revision -B

Ozone Water TreatmentOzone Water Treatment

MWD Mills WTP - California

3 3 000 lbsda of o one3 3 000 lbsda of o one3 x 3000 lbsday of ozone3 x 3000 lbsday of ozone

Ozone Water TreatmentOzone Water TreatmentOzone Ozone -- How it worksHow it works

OxidantOxidant DisinfectantDisinfectant

bullbull Breaks double carbon Breaks double carbon bondsbonds

bullbull Kills by cell lysing or Kills by cell lysing or causing the cell wall tocausing the cell wall tobondsbonds

bullbull Creates OHCreates OHbullbull radicals radicals which break higher carbon which break higher carbon

causing the cell wall to causing the cell wall to rupture rupture

bullbull AttacksAttacks allall bacteriabacteriabondsbondsbullbull Increased temp and pH Increased temp and pH

accelerates Oaccelerates O33

Attacks Attacks allall bacteria bacteria virus cysts and spores virus cysts and spores in varying degreesin varying degreesaccelerates Oaccelerates O33

decomposition to OHdecomposition to OHbullbull

Micro-organism DNA

Capsule AdenineAdenine

Cell wall ThymineThymine

CytosineCytosine

GuanineGuanine

NuclearmaterialCellmembrane

material

Typical Bacterium DNA

Microbial Growth at Various Ozone ConcentrationsConcentrations

Growth likely

Growth possibleGrowth possible

NO GROWTH

0004 0008 0012 0016 0020

Ozone concentration (mgl)Ozone concentration (mgl)

Typical Water Treatment UsageTypical Water Treatment Usage

Application O3 mgl Contact timeUltra Pure Water 005 - 025 sec ndash min

Water bottling 04 ndash 10 5 ndash 10 min

Swimming pools ampspas

01 ndash 075 4 minutes

Potable taste amp odor 15 ndash 50 5 ndash 10 mindisinfection

Microfloculation 10 ndash 30 5 ndash 10 min

Lignin amp tammin 3 0 10 0 10 30 minLignin amp tamminremoval

30 ndash 100 10 ndash 30 min

Municipal wastewater 50 ndash 150+ 15 ndash 30 min

Ozone Water TreatmentOzone Water TreatmentOzone Ozone ndashndash Municipal ApplicationsMunicipal Applications

bullbull Taste and OdorTaste and Odor

bullbull Color RemovalColor Removal

bullbull Disinfection Without Trihalomethanes (THMs)Disinfection Without Trihalomethanes (THMs)

bullbull Improved Filtration Efficiency and FlocculationImproved Filtration Efficiency and Flocculation

bullbull Cryptosporidium DeactivationCryptosporidium Deactivation

bullbull Giardia amp Virus InactivationGiardia amp Virus Inactivation

bullbull Oxidation Oxidation -- Organics Fe amp MnOrganics Fe amp Mn

bullbull Wastewater disinfectionWastewater disinfection

bullbull BOD COD and TOC reductionBOD COD and TOC reduction

Applications of Ozone

Wastewater Treatmentbull Disinfection of Secondary and Tertiary Effluentsbull Color Reductionbull Color Reductionbull TOC Oxidation (Industrial)bull Oxidation of Odor Causing Compoundsbull Oxidation of Endocrine Disruptors (EDCrsquos) and p ( )

Pharmaceutically Active Compounds (PACrsquos)

Applications of Ozone

What are Endocrine Disruptors (EDCrsquos) and What are Endocrine Disruptors (EDCrsquos) and Ph ti ll A ti C d (PACrsquo )Ph ti ll A ti C d (PACrsquo )Pharmaceutically Active Compounds (PACrsquos)Pharmaceutically Active Compounds (PACrsquos)

bullbull EDCrsquosEDCrsquos andand PACrsquosPACrsquos areare NaturallyNaturally andand SyntheticSyntheticdd th tth t ff tff t thth b lb l llcompoundscompounds thatthat maymay affectaffect thethe balancebalance oror normalnormal

functionsfunctions inin animalsanimals andand humanshumans

What can EDCrsquos and PACrsquos doWhat can EDCrsquos and PACrsquos do

bullbull Even in very small concentrations these compounds Even in very small concentrations these compounds y py pcan can disruptdisrupt normal bodily functionsnormal bodily functions

bullbull ManMan--made chemicals can trick the bodies endocrine made chemicals can trick the bodies endocrine system system

Applications of Ozone

Examples of Endocrine Disruptors1000rsquos of compounds that may be Investigated as EDCs ndash Some examples are

bullbull Synthetic HormonesSynthetic Hormonesbullbull Naturally Occurring Estrogens Naturally Occurring Estrogens

Health and Beauty AidsHealth and Beauty Aidsbullbull Health and Beauty AidsHealth and Beauty Aidsbullbull SolventsSolventsbullbull PesticidesPesticidesbullbull SurfactantsSurfactantsbullbull PlasticsPlastics

F i idF i idbullbull FungicidesFungicides

Ozone Water TreatmentOzone Water Treatment

Ozone Ozone -- Industrial ApplicationsIndustrial Applications-- Ultrapure Water for Pharmaceutical ApplicationsUltrapure Water for Pharmaceutical Applications

-- Wastewater disinfection color removalWastewater disinfection color removal

-- Soil and Groundwater Remediation Soil and Groundwater Remediation

-- Cooling Tower Water TreatmentCooling Tower Water Treatment

-- Food ProcessingFood Processing

-- Aquaculture AquariumsAquaculture AquariumsAquaculture AquariumsAquaculture Aquariums

-- Beverage ApplicationsBeverage Applications

P l amp P Bl hiP l amp P Bl hi-- Pulp amp Paper BleachingPulp amp Paper Bleaching

High Purity OzonationHigh Purity Ozonation

Microchip manufacturingMicrochip manufacturing

What are the current issues in large-scale gozone generationg

Experimental Setup

Front view of the two units after the redesign and reworking ofthe gas water and instruments connectionsthe gas water and instruments connections

Experimental Setup

Top view of the twoexperimental unitsexperimental unitsSpectroscope (notshown) is to the left ofthe DBD The units weredifferent with respect todifferent with respect totheir electrodes onehad only the electrodecoated with thedielectric (ldquosingle-dielectric ( single-coatedrdquo) the other onehad the electrode andthe anode coated withthe dielectric (ldquodouble-the dielectric ( double-coatedrdquo)

Basics Generation of OzoneBasics Generation of Ozone

SpectroscopyPlasma

Plasma Absorption SpectroscopyPlasma Absorption Spectroscopy

Infrared Absorption SpectroscopyInfrared Absorption Spectroscopy

IR spectra in pure oxygen (black curve) and at approximately 10wt N2 admixture (red line) N2O5 peaks appear at124 1 d 1 2 11245 cm-1 and at 1725 cm-1

Infrared Absorption SpectroscopyInfrared Absorption Spectroscopy

IR spectra of several methane variations The green curve envelopes all of the methane peaks at 1325 cm-1recorded at smaller methane admixtures Simultaneously the N2O5 peaks disappear as the methane peaks appear

N2O5 FormationN2O5 Formation2 52 5p=2 bara cwt=20degC q=35kWm2 f=1450Hz

45N2O5 AT95

30

35

40

N

2 B

lend

ing

N2O AT95N2O5 IGSN2O IGSN2O5 LGN2O LG

1 5

20

25

nt [p

pmV]

3

wt

05

10

15

NO

x co

nten

005 7 9 11 13 15 17

ozone conc [wt]

Amount of formed N2O5 and N2O as a function of ozone concentration at 3 wt of nitrogen admixture and fori l dvarious electrode arrangements

Plasma Emission SpectroscopyPlasma Emission Spectroscopyp pyp py

Relative Emissions of the Ozonizer plasmaRelative Emissions of the Ozonizer plasma

Region 300- 850 nm from individual (calibrated) regions (smoothed by PeakFit) Single-coated ozone generator Inlet side

3 5E+06

30E+06

35E+06

7 9

20E+06

25E+06

nten

sity

au

2

311 12

10E+06

15E+06

In 4

5

6 8 10

14

15

16

17

00E+00

50E+05

280 300 320 340 360 380 400 420 440 460 480 500 520 540 560 580 600 620 640 660 680 700 720 740 760 780 800 820 840 860

Wavelength nm

1 13

Wavelength nm

Absolute Emission of the DBD PlasmaAbsolute Emission of the DBD Plasma

Intensities in (O2+3 wtN2) plasma

1 20E+04

100E+04

120E+04

600E+03

800E+03

nten

sity

(au

)

200E+03

400E+03

In

O(777)

000E+00200 250 300 350 400 450 500 550 600 650 700 750 800 850

Wavelength nm

Intensities in 3 wtN2+O2 plasmaIntensities in 3 wtN2+O2 plasma

Plasma Chemistry in OzonizersPlasma Chemistry in Ozonizers

Dry Air O2 N2

e - e -

O N2 N O2

O3 NO

O2 N O2

O3

N

3

NO2

O2 O3

NO

N

NO2 O3

N2O

NO3 N

N2O4

NO2

NO2

N2O5

NO3

Primary electron-driven chemical reactions leading to the formation of N2O5 and N2O in a dry air plasma

Plasma emission diagnostics role of N2Plasma emission diagnostics role of N2

Dry Air O2 N2

e - e -

O N2 N O2

O3 NO

O2 N O2

O3

O

N

ON

NO2

O2O3

N

NO N

NO2 O3

N2O

NO3 N

N2O4

NO2

NO2

N2O5

NO3

ONbullWith N2 present ndash less oxygen atoms are formed However the difference in intensity is

very small

Modeling of plasma chemistry incl the NxOy chemistry up to N2O5 for different Oxygen Nitrogen mixtures varying power deposition scenarios

and initial ozone background concentrations (up to 15) previously done

The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation

The role of N2 must be related to its by-products reacting on the surface of the electrodeThe role of N2 must be related to its by-products reacting on the surface of the electrode

The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established

Ab 8 t f O

The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established

Ab 8 t f OAbove 8 wt of O3

1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)

Above 8 wt of O3

1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)case without pampp)

2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of the

case without pampp)

2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of thethem A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface

them A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface

The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation

Three possibilities have to be considered for the oxygen-fedozone generator

Three possibilities have to be considered for the oxygen-fedozone generatorozone generator

bull Excited N2 molecules lead to an increased O2 dissociation in

ozone generator

bull Excited N2 molecules lead to an increased O2 dissociation in2 2such case an increased efficiency is correlated to the N2admixture

2 2such case an increased efficiency is correlated to the N2admixture

bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial

bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial

bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2

bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2g p g 3 pp y 2g p g 3 pp y 2

Effect of methane on ozone efficiency and specific powerEffect of methane on ozone efficiency and specific power

Effect of Methane on Ozone Content in Outlet Gas and on Specific Power Pure O2

13 12

10

11

12

t 8

10

8

9

10

ne c

onte

nt w

t

6

8

ecifi

c po

wer

kW

hlb

5

6

7

Ozo

n

2

4 Spe

400E+00 20E+03 40E+03 60E+03 80E+03 10E+04 12E+04

Methane in feedgas ppm

0

Ozone content in the outlet gas Specif ic pow er of the ozone generatorg p p g

Effects of N2 and CH4Effects of N2 and CH4

Pi t f h t lli N O t tPicture of an amorphous-crystalline N2O5 structurecaptured at the Orlando Skylake water plant in 2006

Plasma Chemistry with CH4 Impurities

OxygenO2 N2

e - e -

CHO N2

NO2

O NO

O2 N O2 O3

NOH

CH4e-

O3 NO

NO2

O2O3NO N

NO2 O

NO2

NO2

N2ONO3

N

O3

NO2

NO

HNO3

N2O4

N2O5

NO2

NO3

N2O5

Effect of methane on the electrode surfaces

a) b)

Inlet Outlet Outlet

) d)

I l t I l t

c) d)

Electrode of the ozone generator afterseveral hours in CH8O2 and up to 2 wt of methane (a b c)

Inlet Inlet

three hours in CH8O2+traces of N2 and up to 1 wt of methane (d) Visible change of discharge character at about 13 length of electrode (a d)

Kinetics of CHx Conversion without N2

conversion by collisions

O2 + CHx 12wt O3 + CO2 +H2O

deposition vaporizationby sputtering

ibl b l 1000 CHreversible process below 1000ppm CH4

Effect of water on electrode surface with N2

Inlet

OutletOutlet

Electrode of the ozone generator after several hours in H OO N

Inlet

Electrode of the ozone generator after several hours in H2OO2N2

Effect of water on electrode surface

Long term effect (800 hrs) of H2OO2N2

Kinetics of CHx Conversion with N2

conversion by collisionsHNO3 formation

O2 + N2 +CHx 12wtO2 + CO2 +H2O + HNO3

deposition vaporizationby sputtering

H2O + HNO3

by sputtering

irreversible process above a N2 threshold () ltlt 1000ppm N2

sticky deposit

p 2 ( ) pp 2 any CH4 concentration (60ppm)

Plasma Chemistry with CH4 ImpuritiesPlasma Chemistry with CH4 Impurities4

bull Formation of NO and NO2 depends on O3 N2 and gas temperature Conclusion N2 admixture is the key factor

SummarySummaryyyThe mechanisms of formed NOx by-products follows the sameThe mechanisms of formed NOx by-products follows the sameprinciples as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentration

principles as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentrationozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)

ozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)g p ( g p )

The conversion of methane to OH and H2O is found to depend on

g p ( g p )

The conversion of methane to OH and H2O is found to depend ondissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)

dissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)discharge gap)discharge gap)

How do you optimize an ozone generatorg

Scientific ApproachScientific ApproachTheoretical Experimental

pppp

c [wt]

f [Hz]

c [wt]

f [Hz]

[kW]UUUβ1

1Cf4αPn

1iiminpeakimin

iiD

q [kWm2]q [kWm2]

150

180

][V]voltagepeakUpeak

[]cylinder perslicesofamountnsliceii

whereth

09 00

30

60

90

120

effic

ienc

y [

][0tdj t bl[F]sliceisdielectricofecapacitancC

[Hz]frequencyf[V]sliceivoltageminimumiUmin

thiD

th

10

28

46

64

82

39

107

176

244 power density

[kWm2]

ozone conc [wt][]CCβ

][0parameteradjustableα

iDiGi

Impact of Power Inductionp

350

400

wer

200

250

300

App

lied

Pow

Arr C 2Arr D +0

Arr E +45Arr F +7

Arr G +3

5 0

100

150

Frac

tion

of

1 2 3 4

ReferenceArr B unstable

Arr C -2

00

50

4Position (1inlet 4outlet)

Experimental Test Rigp g

Experimental Test Rigp g

Outer grounded electrode (left picture) and the dielectric covered inner electrodes (right) d e ect c cove ed e e ect odes ( g t)

Reference (Traditional) Arrangement

Inlet OutletGas flow direction

Optimized Arrangement

Inlet OutletGas flow direction

Intelligent Gap System (IGS)g p y ( )

Molecular Oxygen (O2) Ozone (O3)

O2 O3

yg ( 2) ( 3)

Particle Size SynthesisParticle Size SynthesisByBy--Products Cluster FormationProducts Cluster Formationyy

high diffusion and deposition to surfaces

low diffusion rate good transport

high sedimentation on the structurehigh sedimentation on the structure

Degreacutemont Technologies ndash OzoniaIntelligent Gap SystemIntelligent Gap System

G Vezzuacute JL Lopez A Freilich and K Becker Optimizationof Large-Scale Ozone Generators IEEE Transactions onPlasma Science Vol 37 No 6 p 890-896 (2009)

ConclusionsConclusionsConclusionsConclusionsFundamentals of ozone synthesis in a DBD plasmay p

ndash Highly filamented DBD discharges are best-suitedfor the production of ozone concentrations in therange of 6 to 14 wtrange of 6 to 14 wt

ndash The preferred characteristic of the microdischargesare Townsend-like at reduced electric fields Enaround 190 Townsend

ndash Detrimental side-effects induced by by-productscan be avoided by a proper design of the electrodecan be avoided by a proper design of the electrodearrangement The phenomenon is related to thediffusion rates of formed by-product clusters

ConclusionsConclusionsConclusionsConclusionsBenefits from DBD microplasma tailoring

ndash Reduced power consumption of up to 10 improvement

ndash Increased ozone concentrations of up to 14 now achievable

ndash Improved neutralization and conditioning of detrimental by-products

ndash Reduced system capital and operational cost

New technologies to improve ozone p

generatorg

HV Pulsed Power SwitchingHV Pulsed Power Switching

Microchannel Generation of Ozone

Channel ArrayChannel Array

Microchannel

330 microm 230 microm

Some Cap-DBD Devices Operating in Air

Increase of 60 of

Spacing 225 μmof 60 of plasma

No space

Cap‐DBD ozone generation

bull Ozone concentration is evaluated via Eco S d l UV 100 O A l (0 01Sensors model UV-100 Ozone Analyzer (001 ndash 900 ppm wiht an accuracy of plusmn2)

bull Three reactors 6 tubings 6rdquo with spacings of 0 μm 225 μm and 500 μm running at 3 kV μ μ μ g

SpacingOzone Concentration

3 kV rms 4 kV rms3 kV rms 4 kV rms

0 μm 660 ppm

225 μm 550 ppm

For a device of such small scale these ozone levels are promising

500 μm 380 ppm

J Mahoney W Zhu VS Johnson KH Becker and JL Lopez Electrical and optical emissionmeasurements of a capillary dielectric barrier discharge European Physics Journal D Vol 60 441-447(2010)

QuestionsQuestions

Thank YouFor more informationProf Jose L Lopez PhD

Thank YouFor more informationDepartment of Physics

Telephone (973) 761-9057Email joselopez1shuedu

Website wwwshueduacademicsartsciphysicsWebsite wwwshueduacademicsartsciphysics

Page 40: Dielectric Barrier Discharge (DBD) & Progress in Large ...bonitz/si12/talks/august_8/lopez_si12.pdf · Dielectric Barrier Discharge (DBD) & Progress in Large-Scale Ozone Generation

Ozone Generator

3 O 2 O

Dielectric Barrier Discharge

3 O2 2 O3

OO22 OO33++OO22Ondash ndashO3O2

O2O2

Ondash ndash

endash O2Ondash ndash O2endash

O3

O3O2O2 O2

HeatHeatHeatHeat

Properties of Ozone (O3)

T i t i f f Tri-atomic form of oxygen

Most powerful commercial oxidizing agent

Unstable - must be generated and used onsite

Limited solubility in water but more so than oxygenLimited solubility in water but more so than oxygen

Leaves a dissolved residual which ultimately converts back to oxygenconverts back to oxygen

Discharge Tubes in Ozone GeneratorsDischarge Tubes in Ozone Generators

Traditional

Ozone Generator

with Glass Tubes

Generation of OzoneGeneration of Ozone

Generation of OzoneAdvantages of Enamel Dielectrics

Proven Patented Designbull Simplicity

Si l Di l i Cbull Single Dielectric Componentndash Reduced number of Dielectrics

bull Safety ndash Lower operating voltage

(lt 4000 V)bull Reliabilty

ndash Fused Dielectrics ensure continuous production

bull Lowest Power Consumption Operational Savingsndash Operational Savings

Modern Ozone GeneratorModern Ozone Generator

Ozonia Advanced Technology Ozone GeneratorOzone Generator

Generation of OzoneGeneration of Ozone

Generation of Ozone

Power Supply UnitPower Supply Unit

IGBT Inverter CircuitMain Circuit Breaker

HV 480 Volts60 Hz3 Phase Supply

C I

450KVAPow er to

GeneratorFILTER

CONVERTER INVERTERTRANSFORMER

C I450KVA Power Stage

CONTACTOR

bull Latest in Power Semiconductor Technology Modular Design

bull Utilizes IGBTrsquos (Insulated Gate Bi‐Polar Transistors) Converter and Inverter Components

Ozone Water Treatment

B bbl Diff iB bbl Diff iBubble DiffusionBubble Diffusion

Easy to use

Low energy usage Low energy usage

Mass transfer efficiencies to gt 90

Ozone Process Flow DiagramOzone Process Flow DiagramVent to

Atmosphere

O OOxygen

Off-Gas Blower

Ozone Destruct Unit

10 12

O3O2

LOX

10-12 O3

Ozone Generators

Ozone Contact ChamberLOX T k Generators Chamber

VaporizersLOX Tank

Municipal Ozone Installations

Ozonia Installations Ozone Plant Size [lbday] Start-Up DateKey Ozonia Installations (Partial List)

Los Angeles CA 10000 1986Fairfax VA ndash Corbalis 9000 2003MWD CA ndash Mills 9 000 2003

Ozonia Installations Ozone Plant Size [lbday] Start Up Date

MWD CA Mills 9000 2003Fairfax Co VA ndash Griffith 9000 2004MWD CA ndash Jensen 18750 2005Indianapolis IN ndash Belmont AWT 12000 2007I di li IN 12 000 2007Indianapolis IN ndash Southport AWT 12000 2007MWD CA ndash Diemer 13400 2008MWD CA ndash Weymouth 13400 2009

Ozonia North America - Potable Water SummaryTotal Number of Installations 90Total Installed Production gt 265000 lbsdayTotal Installed Production 265000 lbsday

Revision -B

Ozone Water TreatmentOzone Water Treatment

MWD Mills WTP - California

3 3 000 lbsda of o one3 3 000 lbsda of o one3 x 3000 lbsday of ozone3 x 3000 lbsday of ozone

Ozone Water TreatmentOzone Water TreatmentOzone Ozone -- How it worksHow it works

OxidantOxidant DisinfectantDisinfectant

bullbull Breaks double carbon Breaks double carbon bondsbonds

bullbull Kills by cell lysing or Kills by cell lysing or causing the cell wall tocausing the cell wall tobondsbonds

bullbull Creates OHCreates OHbullbull radicals radicals which break higher carbon which break higher carbon

causing the cell wall to causing the cell wall to rupture rupture

bullbull AttacksAttacks allall bacteriabacteriabondsbondsbullbull Increased temp and pH Increased temp and pH

accelerates Oaccelerates O33

Attacks Attacks allall bacteria bacteria virus cysts and spores virus cysts and spores in varying degreesin varying degreesaccelerates Oaccelerates O33

decomposition to OHdecomposition to OHbullbull

Micro-organism DNA

Capsule AdenineAdenine

Cell wall ThymineThymine

CytosineCytosine

GuanineGuanine

NuclearmaterialCellmembrane

material

Typical Bacterium DNA

Microbial Growth at Various Ozone ConcentrationsConcentrations

Growth likely

Growth possibleGrowth possible

NO GROWTH

0004 0008 0012 0016 0020

Ozone concentration (mgl)Ozone concentration (mgl)

Typical Water Treatment UsageTypical Water Treatment Usage

Application O3 mgl Contact timeUltra Pure Water 005 - 025 sec ndash min

Water bottling 04 ndash 10 5 ndash 10 min

Swimming pools ampspas

01 ndash 075 4 minutes

Potable taste amp odor 15 ndash 50 5 ndash 10 mindisinfection

Microfloculation 10 ndash 30 5 ndash 10 min

Lignin amp tammin 3 0 10 0 10 30 minLignin amp tamminremoval

30 ndash 100 10 ndash 30 min

Municipal wastewater 50 ndash 150+ 15 ndash 30 min

Ozone Water TreatmentOzone Water TreatmentOzone Ozone ndashndash Municipal ApplicationsMunicipal Applications

bullbull Taste and OdorTaste and Odor

bullbull Color RemovalColor Removal

bullbull Disinfection Without Trihalomethanes (THMs)Disinfection Without Trihalomethanes (THMs)

bullbull Improved Filtration Efficiency and FlocculationImproved Filtration Efficiency and Flocculation

bullbull Cryptosporidium DeactivationCryptosporidium Deactivation

bullbull Giardia amp Virus InactivationGiardia amp Virus Inactivation

bullbull Oxidation Oxidation -- Organics Fe amp MnOrganics Fe amp Mn

bullbull Wastewater disinfectionWastewater disinfection

bullbull BOD COD and TOC reductionBOD COD and TOC reduction

Applications of Ozone

Wastewater Treatmentbull Disinfection of Secondary and Tertiary Effluentsbull Color Reductionbull Color Reductionbull TOC Oxidation (Industrial)bull Oxidation of Odor Causing Compoundsbull Oxidation of Endocrine Disruptors (EDCrsquos) and p ( )

Pharmaceutically Active Compounds (PACrsquos)

Applications of Ozone

What are Endocrine Disruptors (EDCrsquos) and What are Endocrine Disruptors (EDCrsquos) and Ph ti ll A ti C d (PACrsquo )Ph ti ll A ti C d (PACrsquo )Pharmaceutically Active Compounds (PACrsquos)Pharmaceutically Active Compounds (PACrsquos)

bullbull EDCrsquosEDCrsquos andand PACrsquosPACrsquos areare NaturallyNaturally andand SyntheticSyntheticdd th tth t ff tff t thth b lb l llcompoundscompounds thatthat maymay affectaffect thethe balancebalance oror normalnormal

functionsfunctions inin animalsanimals andand humanshumans

What can EDCrsquos and PACrsquos doWhat can EDCrsquos and PACrsquos do

bullbull Even in very small concentrations these compounds Even in very small concentrations these compounds y py pcan can disruptdisrupt normal bodily functionsnormal bodily functions

bullbull ManMan--made chemicals can trick the bodies endocrine made chemicals can trick the bodies endocrine system system

Applications of Ozone

Examples of Endocrine Disruptors1000rsquos of compounds that may be Investigated as EDCs ndash Some examples are

bullbull Synthetic HormonesSynthetic Hormonesbullbull Naturally Occurring Estrogens Naturally Occurring Estrogens

Health and Beauty AidsHealth and Beauty Aidsbullbull Health and Beauty AidsHealth and Beauty Aidsbullbull SolventsSolventsbullbull PesticidesPesticidesbullbull SurfactantsSurfactantsbullbull PlasticsPlastics

F i idF i idbullbull FungicidesFungicides

Ozone Water TreatmentOzone Water Treatment

Ozone Ozone -- Industrial ApplicationsIndustrial Applications-- Ultrapure Water for Pharmaceutical ApplicationsUltrapure Water for Pharmaceutical Applications

-- Wastewater disinfection color removalWastewater disinfection color removal

-- Soil and Groundwater Remediation Soil and Groundwater Remediation

-- Cooling Tower Water TreatmentCooling Tower Water Treatment

-- Food ProcessingFood Processing

-- Aquaculture AquariumsAquaculture AquariumsAquaculture AquariumsAquaculture Aquariums

-- Beverage ApplicationsBeverage Applications

P l amp P Bl hiP l amp P Bl hi-- Pulp amp Paper BleachingPulp amp Paper Bleaching

High Purity OzonationHigh Purity Ozonation

Microchip manufacturingMicrochip manufacturing

What are the current issues in large-scale gozone generationg

Experimental Setup

Front view of the two units after the redesign and reworking ofthe gas water and instruments connectionsthe gas water and instruments connections

Experimental Setup

Top view of the twoexperimental unitsexperimental unitsSpectroscope (notshown) is to the left ofthe DBD The units weredifferent with respect todifferent with respect totheir electrodes onehad only the electrodecoated with thedielectric (ldquosingle-dielectric ( single-coatedrdquo) the other onehad the electrode andthe anode coated withthe dielectric (ldquodouble-the dielectric ( double-coatedrdquo)

Basics Generation of OzoneBasics Generation of Ozone

SpectroscopyPlasma

Plasma Absorption SpectroscopyPlasma Absorption Spectroscopy

Infrared Absorption SpectroscopyInfrared Absorption Spectroscopy

IR spectra in pure oxygen (black curve) and at approximately 10wt N2 admixture (red line) N2O5 peaks appear at124 1 d 1 2 11245 cm-1 and at 1725 cm-1

Infrared Absorption SpectroscopyInfrared Absorption Spectroscopy

IR spectra of several methane variations The green curve envelopes all of the methane peaks at 1325 cm-1recorded at smaller methane admixtures Simultaneously the N2O5 peaks disappear as the methane peaks appear

N2O5 FormationN2O5 Formation2 52 5p=2 bara cwt=20degC q=35kWm2 f=1450Hz

45N2O5 AT95

30

35

40

N

2 B

lend

ing

N2O AT95N2O5 IGSN2O IGSN2O5 LGN2O LG

1 5

20

25

nt [p

pmV]

3

wt

05

10

15

NO

x co

nten

005 7 9 11 13 15 17

ozone conc [wt]

Amount of formed N2O5 and N2O as a function of ozone concentration at 3 wt of nitrogen admixture and fori l dvarious electrode arrangements

Plasma Emission SpectroscopyPlasma Emission Spectroscopyp pyp py

Relative Emissions of the Ozonizer plasmaRelative Emissions of the Ozonizer plasma

Region 300- 850 nm from individual (calibrated) regions (smoothed by PeakFit) Single-coated ozone generator Inlet side

3 5E+06

30E+06

35E+06

7 9

20E+06

25E+06

nten

sity

au

2

311 12

10E+06

15E+06

In 4

5

6 8 10

14

15

16

17

00E+00

50E+05

280 300 320 340 360 380 400 420 440 460 480 500 520 540 560 580 600 620 640 660 680 700 720 740 760 780 800 820 840 860

Wavelength nm

1 13

Wavelength nm

Absolute Emission of the DBD PlasmaAbsolute Emission of the DBD Plasma

Intensities in (O2+3 wtN2) plasma

1 20E+04

100E+04

120E+04

600E+03

800E+03

nten

sity

(au

)

200E+03

400E+03

In

O(777)

000E+00200 250 300 350 400 450 500 550 600 650 700 750 800 850

Wavelength nm

Intensities in 3 wtN2+O2 plasmaIntensities in 3 wtN2+O2 plasma

Plasma Chemistry in OzonizersPlasma Chemistry in Ozonizers

Dry Air O2 N2

e - e -

O N2 N O2

O3 NO

O2 N O2

O3

N

3

NO2

O2 O3

NO

N

NO2 O3

N2O

NO3 N

N2O4

NO2

NO2

N2O5

NO3

Primary electron-driven chemical reactions leading to the formation of N2O5 and N2O in a dry air plasma

Plasma emission diagnostics role of N2Plasma emission diagnostics role of N2

Dry Air O2 N2

e - e -

O N2 N O2

O3 NO

O2 N O2

O3

O

N

ON

NO2

O2O3

N

NO N

NO2 O3

N2O

NO3 N

N2O4

NO2

NO2

N2O5

NO3

ONbullWith N2 present ndash less oxygen atoms are formed However the difference in intensity is

very small

Modeling of plasma chemistry incl the NxOy chemistry up to N2O5 for different Oxygen Nitrogen mixtures varying power deposition scenarios

and initial ozone background concentrations (up to 15) previously done

The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation

The role of N2 must be related to its by-products reacting on the surface of the electrodeThe role of N2 must be related to its by-products reacting on the surface of the electrode

The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established

Ab 8 t f O

The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established

Ab 8 t f OAbove 8 wt of O3

1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)

Above 8 wt of O3

1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)case without pampp)

2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of the

case without pampp)

2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of thethem A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface

them A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface

The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation

Three possibilities have to be considered for the oxygen-fedozone generator

Three possibilities have to be considered for the oxygen-fedozone generatorozone generator

bull Excited N2 molecules lead to an increased O2 dissociation in

ozone generator

bull Excited N2 molecules lead to an increased O2 dissociation in2 2such case an increased efficiency is correlated to the N2admixture

2 2such case an increased efficiency is correlated to the N2admixture

bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial

bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial

bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2

bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2g p g 3 pp y 2g p g 3 pp y 2

Effect of methane on ozone efficiency and specific powerEffect of methane on ozone efficiency and specific power

Effect of Methane on Ozone Content in Outlet Gas and on Specific Power Pure O2

13 12

10

11

12

t 8

10

8

9

10

ne c

onte

nt w

t

6

8

ecifi

c po

wer

kW

hlb

5

6

7

Ozo

n

2

4 Spe

400E+00 20E+03 40E+03 60E+03 80E+03 10E+04 12E+04

Methane in feedgas ppm

0

Ozone content in the outlet gas Specif ic pow er of the ozone generatorg p p g

Effects of N2 and CH4Effects of N2 and CH4

Pi t f h t lli N O t tPicture of an amorphous-crystalline N2O5 structurecaptured at the Orlando Skylake water plant in 2006

Plasma Chemistry with CH4 Impurities

OxygenO2 N2

e - e -

CHO N2

NO2

O NO

O2 N O2 O3

NOH

CH4e-

O3 NO

NO2

O2O3NO N

NO2 O

NO2

NO2

N2ONO3

N

O3

NO2

NO

HNO3

N2O4

N2O5

NO2

NO3

N2O5

Effect of methane on the electrode surfaces

a) b)

Inlet Outlet Outlet

) d)

I l t I l t

c) d)

Electrode of the ozone generator afterseveral hours in CH8O2 and up to 2 wt of methane (a b c)

Inlet Inlet

three hours in CH8O2+traces of N2 and up to 1 wt of methane (d) Visible change of discharge character at about 13 length of electrode (a d)

Kinetics of CHx Conversion without N2

conversion by collisions

O2 + CHx 12wt O3 + CO2 +H2O

deposition vaporizationby sputtering

ibl b l 1000 CHreversible process below 1000ppm CH4

Effect of water on electrode surface with N2

Inlet

OutletOutlet

Electrode of the ozone generator after several hours in H OO N

Inlet

Electrode of the ozone generator after several hours in H2OO2N2

Effect of water on electrode surface

Long term effect (800 hrs) of H2OO2N2

Kinetics of CHx Conversion with N2

conversion by collisionsHNO3 formation

O2 + N2 +CHx 12wtO2 + CO2 +H2O + HNO3

deposition vaporizationby sputtering

H2O + HNO3

by sputtering

irreversible process above a N2 threshold () ltlt 1000ppm N2

sticky deposit

p 2 ( ) pp 2 any CH4 concentration (60ppm)

Plasma Chemistry with CH4 ImpuritiesPlasma Chemistry with CH4 Impurities4

bull Formation of NO and NO2 depends on O3 N2 and gas temperature Conclusion N2 admixture is the key factor

SummarySummaryyyThe mechanisms of formed NOx by-products follows the sameThe mechanisms of formed NOx by-products follows the sameprinciples as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentration

principles as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentrationozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)

ozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)g p ( g p )

The conversion of methane to OH and H2O is found to depend on

g p ( g p )

The conversion of methane to OH and H2O is found to depend ondissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)

dissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)discharge gap)discharge gap)

How do you optimize an ozone generatorg

Scientific ApproachScientific ApproachTheoretical Experimental

pppp

c [wt]

f [Hz]

c [wt]

f [Hz]

[kW]UUUβ1

1Cf4αPn

1iiminpeakimin

iiD

q [kWm2]q [kWm2]

150

180

][V]voltagepeakUpeak

[]cylinder perslicesofamountnsliceii

whereth

09 00

30

60

90

120

effic

ienc

y [

][0tdj t bl[F]sliceisdielectricofecapacitancC

[Hz]frequencyf[V]sliceivoltageminimumiUmin

thiD

th

10

28

46

64

82

39

107

176

244 power density

[kWm2]

ozone conc [wt][]CCβ

][0parameteradjustableα

iDiGi

Impact of Power Inductionp

350

400

wer

200

250

300

App

lied

Pow

Arr C 2Arr D +0

Arr E +45Arr F +7

Arr G +3

5 0

100

150

Frac

tion

of

1 2 3 4

ReferenceArr B unstable

Arr C -2

00

50

4Position (1inlet 4outlet)

Experimental Test Rigp g

Experimental Test Rigp g

Outer grounded electrode (left picture) and the dielectric covered inner electrodes (right) d e ect c cove ed e e ect odes ( g t)

Reference (Traditional) Arrangement

Inlet OutletGas flow direction

Optimized Arrangement

Inlet OutletGas flow direction

Intelligent Gap System (IGS)g p y ( )

Molecular Oxygen (O2) Ozone (O3)

O2 O3

yg ( 2) ( 3)

Particle Size SynthesisParticle Size SynthesisByBy--Products Cluster FormationProducts Cluster Formationyy

high diffusion and deposition to surfaces

low diffusion rate good transport

high sedimentation on the structurehigh sedimentation on the structure

Degreacutemont Technologies ndash OzoniaIntelligent Gap SystemIntelligent Gap System

G Vezzuacute JL Lopez A Freilich and K Becker Optimizationof Large-Scale Ozone Generators IEEE Transactions onPlasma Science Vol 37 No 6 p 890-896 (2009)

ConclusionsConclusionsConclusionsConclusionsFundamentals of ozone synthesis in a DBD plasmay p

ndash Highly filamented DBD discharges are best-suitedfor the production of ozone concentrations in therange of 6 to 14 wtrange of 6 to 14 wt

ndash The preferred characteristic of the microdischargesare Townsend-like at reduced electric fields Enaround 190 Townsend

ndash Detrimental side-effects induced by by-productscan be avoided by a proper design of the electrodecan be avoided by a proper design of the electrodearrangement The phenomenon is related to thediffusion rates of formed by-product clusters

ConclusionsConclusionsConclusionsConclusionsBenefits from DBD microplasma tailoring

ndash Reduced power consumption of up to 10 improvement

ndash Increased ozone concentrations of up to 14 now achievable

ndash Improved neutralization and conditioning of detrimental by-products

ndash Reduced system capital and operational cost

New technologies to improve ozone p

generatorg

HV Pulsed Power SwitchingHV Pulsed Power Switching

Microchannel Generation of Ozone

Channel ArrayChannel Array

Microchannel

330 microm 230 microm

Some Cap-DBD Devices Operating in Air

Increase of 60 of

Spacing 225 μmof 60 of plasma

No space

Cap‐DBD ozone generation

bull Ozone concentration is evaluated via Eco S d l UV 100 O A l (0 01Sensors model UV-100 Ozone Analyzer (001 ndash 900 ppm wiht an accuracy of plusmn2)

bull Three reactors 6 tubings 6rdquo with spacings of 0 μm 225 μm and 500 μm running at 3 kV μ μ μ g

SpacingOzone Concentration

3 kV rms 4 kV rms3 kV rms 4 kV rms

0 μm 660 ppm

225 μm 550 ppm

For a device of such small scale these ozone levels are promising

500 μm 380 ppm

J Mahoney W Zhu VS Johnson KH Becker and JL Lopez Electrical and optical emissionmeasurements of a capillary dielectric barrier discharge European Physics Journal D Vol 60 441-447(2010)

QuestionsQuestions

Thank YouFor more informationProf Jose L Lopez PhD

Thank YouFor more informationDepartment of Physics

Telephone (973) 761-9057Email joselopez1shuedu

Website wwwshueduacademicsartsciphysicsWebsite wwwshueduacademicsartsciphysics

Page 41: Dielectric Barrier Discharge (DBD) & Progress in Large ...bonitz/si12/talks/august_8/lopez_si12.pdf · Dielectric Barrier Discharge (DBD) & Progress in Large-Scale Ozone Generation

Properties of Ozone (O3)

T i t i f f Tri-atomic form of oxygen

Most powerful commercial oxidizing agent

Unstable - must be generated and used onsite

Limited solubility in water but more so than oxygenLimited solubility in water but more so than oxygen

Leaves a dissolved residual which ultimately converts back to oxygenconverts back to oxygen

Discharge Tubes in Ozone GeneratorsDischarge Tubes in Ozone Generators

Traditional

Ozone Generator

with Glass Tubes

Generation of OzoneGeneration of Ozone

Generation of OzoneAdvantages of Enamel Dielectrics

Proven Patented Designbull Simplicity

Si l Di l i Cbull Single Dielectric Componentndash Reduced number of Dielectrics

bull Safety ndash Lower operating voltage

(lt 4000 V)bull Reliabilty

ndash Fused Dielectrics ensure continuous production

bull Lowest Power Consumption Operational Savingsndash Operational Savings

Modern Ozone GeneratorModern Ozone Generator

Ozonia Advanced Technology Ozone GeneratorOzone Generator

Generation of OzoneGeneration of Ozone

Generation of Ozone

Power Supply UnitPower Supply Unit

IGBT Inverter CircuitMain Circuit Breaker

HV 480 Volts60 Hz3 Phase Supply

C I

450KVAPow er to

GeneratorFILTER

CONVERTER INVERTERTRANSFORMER

C I450KVA Power Stage

CONTACTOR

bull Latest in Power Semiconductor Technology Modular Design

bull Utilizes IGBTrsquos (Insulated Gate Bi‐Polar Transistors) Converter and Inverter Components

Ozone Water Treatment

B bbl Diff iB bbl Diff iBubble DiffusionBubble Diffusion

Easy to use

Low energy usage Low energy usage

Mass transfer efficiencies to gt 90

Ozone Process Flow DiagramOzone Process Flow DiagramVent to

Atmosphere

O OOxygen

Off-Gas Blower

Ozone Destruct Unit

10 12

O3O2

LOX

10-12 O3

Ozone Generators

Ozone Contact ChamberLOX T k Generators Chamber

VaporizersLOX Tank

Municipal Ozone Installations

Ozonia Installations Ozone Plant Size [lbday] Start-Up DateKey Ozonia Installations (Partial List)

Los Angeles CA 10000 1986Fairfax VA ndash Corbalis 9000 2003MWD CA ndash Mills 9 000 2003

Ozonia Installations Ozone Plant Size [lbday] Start Up Date

MWD CA Mills 9000 2003Fairfax Co VA ndash Griffith 9000 2004MWD CA ndash Jensen 18750 2005Indianapolis IN ndash Belmont AWT 12000 2007I di li IN 12 000 2007Indianapolis IN ndash Southport AWT 12000 2007MWD CA ndash Diemer 13400 2008MWD CA ndash Weymouth 13400 2009

Ozonia North America - Potable Water SummaryTotal Number of Installations 90Total Installed Production gt 265000 lbsdayTotal Installed Production 265000 lbsday

Revision -B

Ozone Water TreatmentOzone Water Treatment

MWD Mills WTP - California

3 3 000 lbsda of o one3 3 000 lbsda of o one3 x 3000 lbsday of ozone3 x 3000 lbsday of ozone

Ozone Water TreatmentOzone Water TreatmentOzone Ozone -- How it worksHow it works

OxidantOxidant DisinfectantDisinfectant

bullbull Breaks double carbon Breaks double carbon bondsbonds

bullbull Kills by cell lysing or Kills by cell lysing or causing the cell wall tocausing the cell wall tobondsbonds

bullbull Creates OHCreates OHbullbull radicals radicals which break higher carbon which break higher carbon

causing the cell wall to causing the cell wall to rupture rupture

bullbull AttacksAttacks allall bacteriabacteriabondsbondsbullbull Increased temp and pH Increased temp and pH

accelerates Oaccelerates O33

Attacks Attacks allall bacteria bacteria virus cysts and spores virus cysts and spores in varying degreesin varying degreesaccelerates Oaccelerates O33

decomposition to OHdecomposition to OHbullbull

Micro-organism DNA

Capsule AdenineAdenine

Cell wall ThymineThymine

CytosineCytosine

GuanineGuanine

NuclearmaterialCellmembrane

material

Typical Bacterium DNA

Microbial Growth at Various Ozone ConcentrationsConcentrations

Growth likely

Growth possibleGrowth possible

NO GROWTH

0004 0008 0012 0016 0020

Ozone concentration (mgl)Ozone concentration (mgl)

Typical Water Treatment UsageTypical Water Treatment Usage

Application O3 mgl Contact timeUltra Pure Water 005 - 025 sec ndash min

Water bottling 04 ndash 10 5 ndash 10 min

Swimming pools ampspas

01 ndash 075 4 minutes

Potable taste amp odor 15 ndash 50 5 ndash 10 mindisinfection

Microfloculation 10 ndash 30 5 ndash 10 min

Lignin amp tammin 3 0 10 0 10 30 minLignin amp tamminremoval

30 ndash 100 10 ndash 30 min

Municipal wastewater 50 ndash 150+ 15 ndash 30 min

Ozone Water TreatmentOzone Water TreatmentOzone Ozone ndashndash Municipal ApplicationsMunicipal Applications

bullbull Taste and OdorTaste and Odor

bullbull Color RemovalColor Removal

bullbull Disinfection Without Trihalomethanes (THMs)Disinfection Without Trihalomethanes (THMs)

bullbull Improved Filtration Efficiency and FlocculationImproved Filtration Efficiency and Flocculation

bullbull Cryptosporidium DeactivationCryptosporidium Deactivation

bullbull Giardia amp Virus InactivationGiardia amp Virus Inactivation

bullbull Oxidation Oxidation -- Organics Fe amp MnOrganics Fe amp Mn

bullbull Wastewater disinfectionWastewater disinfection

bullbull BOD COD and TOC reductionBOD COD and TOC reduction

Applications of Ozone

Wastewater Treatmentbull Disinfection of Secondary and Tertiary Effluentsbull Color Reductionbull Color Reductionbull TOC Oxidation (Industrial)bull Oxidation of Odor Causing Compoundsbull Oxidation of Endocrine Disruptors (EDCrsquos) and p ( )

Pharmaceutically Active Compounds (PACrsquos)

Applications of Ozone

What are Endocrine Disruptors (EDCrsquos) and What are Endocrine Disruptors (EDCrsquos) and Ph ti ll A ti C d (PACrsquo )Ph ti ll A ti C d (PACrsquo )Pharmaceutically Active Compounds (PACrsquos)Pharmaceutically Active Compounds (PACrsquos)

bullbull EDCrsquosEDCrsquos andand PACrsquosPACrsquos areare NaturallyNaturally andand SyntheticSyntheticdd th tth t ff tff t thth b lb l llcompoundscompounds thatthat maymay affectaffect thethe balancebalance oror normalnormal

functionsfunctions inin animalsanimals andand humanshumans

What can EDCrsquos and PACrsquos doWhat can EDCrsquos and PACrsquos do

bullbull Even in very small concentrations these compounds Even in very small concentrations these compounds y py pcan can disruptdisrupt normal bodily functionsnormal bodily functions

bullbull ManMan--made chemicals can trick the bodies endocrine made chemicals can trick the bodies endocrine system system

Applications of Ozone

Examples of Endocrine Disruptors1000rsquos of compounds that may be Investigated as EDCs ndash Some examples are

bullbull Synthetic HormonesSynthetic Hormonesbullbull Naturally Occurring Estrogens Naturally Occurring Estrogens

Health and Beauty AidsHealth and Beauty Aidsbullbull Health and Beauty AidsHealth and Beauty Aidsbullbull SolventsSolventsbullbull PesticidesPesticidesbullbull SurfactantsSurfactantsbullbull PlasticsPlastics

F i idF i idbullbull FungicidesFungicides

Ozone Water TreatmentOzone Water Treatment

Ozone Ozone -- Industrial ApplicationsIndustrial Applications-- Ultrapure Water for Pharmaceutical ApplicationsUltrapure Water for Pharmaceutical Applications

-- Wastewater disinfection color removalWastewater disinfection color removal

-- Soil and Groundwater Remediation Soil and Groundwater Remediation

-- Cooling Tower Water TreatmentCooling Tower Water Treatment

-- Food ProcessingFood Processing

-- Aquaculture AquariumsAquaculture AquariumsAquaculture AquariumsAquaculture Aquariums

-- Beverage ApplicationsBeverage Applications

P l amp P Bl hiP l amp P Bl hi-- Pulp amp Paper BleachingPulp amp Paper Bleaching

High Purity OzonationHigh Purity Ozonation

Microchip manufacturingMicrochip manufacturing

What are the current issues in large-scale gozone generationg

Experimental Setup

Front view of the two units after the redesign and reworking ofthe gas water and instruments connectionsthe gas water and instruments connections

Experimental Setup

Top view of the twoexperimental unitsexperimental unitsSpectroscope (notshown) is to the left ofthe DBD The units weredifferent with respect todifferent with respect totheir electrodes onehad only the electrodecoated with thedielectric (ldquosingle-dielectric ( single-coatedrdquo) the other onehad the electrode andthe anode coated withthe dielectric (ldquodouble-the dielectric ( double-coatedrdquo)

Basics Generation of OzoneBasics Generation of Ozone

SpectroscopyPlasma

Plasma Absorption SpectroscopyPlasma Absorption Spectroscopy

Infrared Absorption SpectroscopyInfrared Absorption Spectroscopy

IR spectra in pure oxygen (black curve) and at approximately 10wt N2 admixture (red line) N2O5 peaks appear at124 1 d 1 2 11245 cm-1 and at 1725 cm-1

Infrared Absorption SpectroscopyInfrared Absorption Spectroscopy

IR spectra of several methane variations The green curve envelopes all of the methane peaks at 1325 cm-1recorded at smaller methane admixtures Simultaneously the N2O5 peaks disappear as the methane peaks appear

N2O5 FormationN2O5 Formation2 52 5p=2 bara cwt=20degC q=35kWm2 f=1450Hz

45N2O5 AT95

30

35

40

N

2 B

lend

ing

N2O AT95N2O5 IGSN2O IGSN2O5 LGN2O LG

1 5

20

25

nt [p

pmV]

3

wt

05

10

15

NO

x co

nten

005 7 9 11 13 15 17

ozone conc [wt]

Amount of formed N2O5 and N2O as a function of ozone concentration at 3 wt of nitrogen admixture and fori l dvarious electrode arrangements

Plasma Emission SpectroscopyPlasma Emission Spectroscopyp pyp py

Relative Emissions of the Ozonizer plasmaRelative Emissions of the Ozonizer plasma

Region 300- 850 nm from individual (calibrated) regions (smoothed by PeakFit) Single-coated ozone generator Inlet side

3 5E+06

30E+06

35E+06

7 9

20E+06

25E+06

nten

sity

au

2

311 12

10E+06

15E+06

In 4

5

6 8 10

14

15

16

17

00E+00

50E+05

280 300 320 340 360 380 400 420 440 460 480 500 520 540 560 580 600 620 640 660 680 700 720 740 760 780 800 820 840 860

Wavelength nm

1 13

Wavelength nm

Absolute Emission of the DBD PlasmaAbsolute Emission of the DBD Plasma

Intensities in (O2+3 wtN2) plasma

1 20E+04

100E+04

120E+04

600E+03

800E+03

nten

sity

(au

)

200E+03

400E+03

In

O(777)

000E+00200 250 300 350 400 450 500 550 600 650 700 750 800 850

Wavelength nm

Intensities in 3 wtN2+O2 plasmaIntensities in 3 wtN2+O2 plasma

Plasma Chemistry in OzonizersPlasma Chemistry in Ozonizers

Dry Air O2 N2

e - e -

O N2 N O2

O3 NO

O2 N O2

O3

N

3

NO2

O2 O3

NO

N

NO2 O3

N2O

NO3 N

N2O4

NO2

NO2

N2O5

NO3

Primary electron-driven chemical reactions leading to the formation of N2O5 and N2O in a dry air plasma

Plasma emission diagnostics role of N2Plasma emission diagnostics role of N2

Dry Air O2 N2

e - e -

O N2 N O2

O3 NO

O2 N O2

O3

O

N

ON

NO2

O2O3

N

NO N

NO2 O3

N2O

NO3 N

N2O4

NO2

NO2

N2O5

NO3

ONbullWith N2 present ndash less oxygen atoms are formed However the difference in intensity is

very small

Modeling of plasma chemistry incl the NxOy chemistry up to N2O5 for different Oxygen Nitrogen mixtures varying power deposition scenarios

and initial ozone background concentrations (up to 15) previously done

The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation

The role of N2 must be related to its by-products reacting on the surface of the electrodeThe role of N2 must be related to its by-products reacting on the surface of the electrode

The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established

Ab 8 t f O

The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established

Ab 8 t f OAbove 8 wt of O3

1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)

Above 8 wt of O3

1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)case without pampp)

2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of the

case without pampp)

2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of thethem A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface

them A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface

The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation

Three possibilities have to be considered for the oxygen-fedozone generator

Three possibilities have to be considered for the oxygen-fedozone generatorozone generator

bull Excited N2 molecules lead to an increased O2 dissociation in

ozone generator

bull Excited N2 molecules lead to an increased O2 dissociation in2 2such case an increased efficiency is correlated to the N2admixture

2 2such case an increased efficiency is correlated to the N2admixture

bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial

bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial

bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2

bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2g p g 3 pp y 2g p g 3 pp y 2

Effect of methane on ozone efficiency and specific powerEffect of methane on ozone efficiency and specific power

Effect of Methane on Ozone Content in Outlet Gas and on Specific Power Pure O2

13 12

10

11

12

t 8

10

8

9

10

ne c

onte

nt w

t

6

8

ecifi

c po

wer

kW

hlb

5

6

7

Ozo

n

2

4 Spe

400E+00 20E+03 40E+03 60E+03 80E+03 10E+04 12E+04

Methane in feedgas ppm

0

Ozone content in the outlet gas Specif ic pow er of the ozone generatorg p p g

Effects of N2 and CH4Effects of N2 and CH4

Pi t f h t lli N O t tPicture of an amorphous-crystalline N2O5 structurecaptured at the Orlando Skylake water plant in 2006

Plasma Chemistry with CH4 Impurities

OxygenO2 N2

e - e -

CHO N2

NO2

O NO

O2 N O2 O3

NOH

CH4e-

O3 NO

NO2

O2O3NO N

NO2 O

NO2

NO2

N2ONO3

N

O3

NO2

NO

HNO3

N2O4

N2O5

NO2

NO3

N2O5

Effect of methane on the electrode surfaces

a) b)

Inlet Outlet Outlet

) d)

I l t I l t

c) d)

Electrode of the ozone generator afterseveral hours in CH8O2 and up to 2 wt of methane (a b c)

Inlet Inlet

three hours in CH8O2+traces of N2 and up to 1 wt of methane (d) Visible change of discharge character at about 13 length of electrode (a d)

Kinetics of CHx Conversion without N2

conversion by collisions

O2 + CHx 12wt O3 + CO2 +H2O

deposition vaporizationby sputtering

ibl b l 1000 CHreversible process below 1000ppm CH4

Effect of water on electrode surface with N2

Inlet

OutletOutlet

Electrode of the ozone generator after several hours in H OO N

Inlet

Electrode of the ozone generator after several hours in H2OO2N2

Effect of water on electrode surface

Long term effect (800 hrs) of H2OO2N2

Kinetics of CHx Conversion with N2

conversion by collisionsHNO3 formation

O2 + N2 +CHx 12wtO2 + CO2 +H2O + HNO3

deposition vaporizationby sputtering

H2O + HNO3

by sputtering

irreversible process above a N2 threshold () ltlt 1000ppm N2

sticky deposit

p 2 ( ) pp 2 any CH4 concentration (60ppm)

Plasma Chemistry with CH4 ImpuritiesPlasma Chemistry with CH4 Impurities4

bull Formation of NO and NO2 depends on O3 N2 and gas temperature Conclusion N2 admixture is the key factor

SummarySummaryyyThe mechanisms of formed NOx by-products follows the sameThe mechanisms of formed NOx by-products follows the sameprinciples as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentration

principles as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentrationozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)

ozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)g p ( g p )

The conversion of methane to OH and H2O is found to depend on

g p ( g p )

The conversion of methane to OH and H2O is found to depend ondissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)

dissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)discharge gap)discharge gap)

How do you optimize an ozone generatorg

Scientific ApproachScientific ApproachTheoretical Experimental

pppp

c [wt]

f [Hz]

c [wt]

f [Hz]

[kW]UUUβ1

1Cf4αPn

1iiminpeakimin

iiD

q [kWm2]q [kWm2]

150

180

][V]voltagepeakUpeak

[]cylinder perslicesofamountnsliceii

whereth

09 00

30

60

90

120

effic

ienc

y [

][0tdj t bl[F]sliceisdielectricofecapacitancC

[Hz]frequencyf[V]sliceivoltageminimumiUmin

thiD

th

10

28

46

64

82

39

107

176

244 power density

[kWm2]

ozone conc [wt][]CCβ

][0parameteradjustableα

iDiGi

Impact of Power Inductionp

350

400

wer

200

250

300

App

lied

Pow

Arr C 2Arr D +0

Arr E +45Arr F +7

Arr G +3

5 0

100

150

Frac

tion

of

1 2 3 4

ReferenceArr B unstable

Arr C -2

00

50

4Position (1inlet 4outlet)

Experimental Test Rigp g

Experimental Test Rigp g

Outer grounded electrode (left picture) and the dielectric covered inner electrodes (right) d e ect c cove ed e e ect odes ( g t)

Reference (Traditional) Arrangement

Inlet OutletGas flow direction

Optimized Arrangement

Inlet OutletGas flow direction

Intelligent Gap System (IGS)g p y ( )

Molecular Oxygen (O2) Ozone (O3)

O2 O3

yg ( 2) ( 3)

Particle Size SynthesisParticle Size SynthesisByBy--Products Cluster FormationProducts Cluster Formationyy

high diffusion and deposition to surfaces

low diffusion rate good transport

high sedimentation on the structurehigh sedimentation on the structure

Degreacutemont Technologies ndash OzoniaIntelligent Gap SystemIntelligent Gap System

G Vezzuacute JL Lopez A Freilich and K Becker Optimizationof Large-Scale Ozone Generators IEEE Transactions onPlasma Science Vol 37 No 6 p 890-896 (2009)

ConclusionsConclusionsConclusionsConclusionsFundamentals of ozone synthesis in a DBD plasmay p

ndash Highly filamented DBD discharges are best-suitedfor the production of ozone concentrations in therange of 6 to 14 wtrange of 6 to 14 wt

ndash The preferred characteristic of the microdischargesare Townsend-like at reduced electric fields Enaround 190 Townsend

ndash Detrimental side-effects induced by by-productscan be avoided by a proper design of the electrodecan be avoided by a proper design of the electrodearrangement The phenomenon is related to thediffusion rates of formed by-product clusters

ConclusionsConclusionsConclusionsConclusionsBenefits from DBD microplasma tailoring

ndash Reduced power consumption of up to 10 improvement

ndash Increased ozone concentrations of up to 14 now achievable

ndash Improved neutralization and conditioning of detrimental by-products

ndash Reduced system capital and operational cost

New technologies to improve ozone p

generatorg

HV Pulsed Power SwitchingHV Pulsed Power Switching

Microchannel Generation of Ozone

Channel ArrayChannel Array

Microchannel

330 microm 230 microm

Some Cap-DBD Devices Operating in Air

Increase of 60 of

Spacing 225 μmof 60 of plasma

No space

Cap‐DBD ozone generation

bull Ozone concentration is evaluated via Eco S d l UV 100 O A l (0 01Sensors model UV-100 Ozone Analyzer (001 ndash 900 ppm wiht an accuracy of plusmn2)

bull Three reactors 6 tubings 6rdquo with spacings of 0 μm 225 μm and 500 μm running at 3 kV μ μ μ g

SpacingOzone Concentration

3 kV rms 4 kV rms3 kV rms 4 kV rms

0 μm 660 ppm

225 μm 550 ppm

For a device of such small scale these ozone levels are promising

500 μm 380 ppm

J Mahoney W Zhu VS Johnson KH Becker and JL Lopez Electrical and optical emissionmeasurements of a capillary dielectric barrier discharge European Physics Journal D Vol 60 441-447(2010)

QuestionsQuestions

Thank YouFor more informationProf Jose L Lopez PhD

Thank YouFor more informationDepartment of Physics

Telephone (973) 761-9057Email joselopez1shuedu

Website wwwshueduacademicsartsciphysicsWebsite wwwshueduacademicsartsciphysics

Page 42: Dielectric Barrier Discharge (DBD) & Progress in Large ...bonitz/si12/talks/august_8/lopez_si12.pdf · Dielectric Barrier Discharge (DBD) & Progress in Large-Scale Ozone Generation

Discharge Tubes in Ozone GeneratorsDischarge Tubes in Ozone Generators

Traditional

Ozone Generator

with Glass Tubes

Generation of OzoneGeneration of Ozone

Generation of OzoneAdvantages of Enamel Dielectrics

Proven Patented Designbull Simplicity

Si l Di l i Cbull Single Dielectric Componentndash Reduced number of Dielectrics

bull Safety ndash Lower operating voltage

(lt 4000 V)bull Reliabilty

ndash Fused Dielectrics ensure continuous production

bull Lowest Power Consumption Operational Savingsndash Operational Savings

Modern Ozone GeneratorModern Ozone Generator

Ozonia Advanced Technology Ozone GeneratorOzone Generator

Generation of OzoneGeneration of Ozone

Generation of Ozone

Power Supply UnitPower Supply Unit

IGBT Inverter CircuitMain Circuit Breaker

HV 480 Volts60 Hz3 Phase Supply

C I

450KVAPow er to

GeneratorFILTER

CONVERTER INVERTERTRANSFORMER

C I450KVA Power Stage

CONTACTOR

bull Latest in Power Semiconductor Technology Modular Design

bull Utilizes IGBTrsquos (Insulated Gate Bi‐Polar Transistors) Converter and Inverter Components

Ozone Water Treatment

B bbl Diff iB bbl Diff iBubble DiffusionBubble Diffusion

Easy to use

Low energy usage Low energy usage

Mass transfer efficiencies to gt 90

Ozone Process Flow DiagramOzone Process Flow DiagramVent to

Atmosphere

O OOxygen

Off-Gas Blower

Ozone Destruct Unit

10 12

O3O2

LOX

10-12 O3

Ozone Generators

Ozone Contact ChamberLOX T k Generators Chamber

VaporizersLOX Tank

Municipal Ozone Installations

Ozonia Installations Ozone Plant Size [lbday] Start-Up DateKey Ozonia Installations (Partial List)

Los Angeles CA 10000 1986Fairfax VA ndash Corbalis 9000 2003MWD CA ndash Mills 9 000 2003

Ozonia Installations Ozone Plant Size [lbday] Start Up Date

MWD CA Mills 9000 2003Fairfax Co VA ndash Griffith 9000 2004MWD CA ndash Jensen 18750 2005Indianapolis IN ndash Belmont AWT 12000 2007I di li IN 12 000 2007Indianapolis IN ndash Southport AWT 12000 2007MWD CA ndash Diemer 13400 2008MWD CA ndash Weymouth 13400 2009

Ozonia North America - Potable Water SummaryTotal Number of Installations 90Total Installed Production gt 265000 lbsdayTotal Installed Production 265000 lbsday

Revision -B

Ozone Water TreatmentOzone Water Treatment

MWD Mills WTP - California

3 3 000 lbsda of o one3 3 000 lbsda of o one3 x 3000 lbsday of ozone3 x 3000 lbsday of ozone

Ozone Water TreatmentOzone Water TreatmentOzone Ozone -- How it worksHow it works

OxidantOxidant DisinfectantDisinfectant

bullbull Breaks double carbon Breaks double carbon bondsbonds

bullbull Kills by cell lysing or Kills by cell lysing or causing the cell wall tocausing the cell wall tobondsbonds

bullbull Creates OHCreates OHbullbull radicals radicals which break higher carbon which break higher carbon

causing the cell wall to causing the cell wall to rupture rupture

bullbull AttacksAttacks allall bacteriabacteriabondsbondsbullbull Increased temp and pH Increased temp and pH

accelerates Oaccelerates O33

Attacks Attacks allall bacteria bacteria virus cysts and spores virus cysts and spores in varying degreesin varying degreesaccelerates Oaccelerates O33

decomposition to OHdecomposition to OHbullbull

Micro-organism DNA

Capsule AdenineAdenine

Cell wall ThymineThymine

CytosineCytosine

GuanineGuanine

NuclearmaterialCellmembrane

material

Typical Bacterium DNA

Microbial Growth at Various Ozone ConcentrationsConcentrations

Growth likely

Growth possibleGrowth possible

NO GROWTH

0004 0008 0012 0016 0020

Ozone concentration (mgl)Ozone concentration (mgl)

Typical Water Treatment UsageTypical Water Treatment Usage

Application O3 mgl Contact timeUltra Pure Water 005 - 025 sec ndash min

Water bottling 04 ndash 10 5 ndash 10 min

Swimming pools ampspas

01 ndash 075 4 minutes

Potable taste amp odor 15 ndash 50 5 ndash 10 mindisinfection

Microfloculation 10 ndash 30 5 ndash 10 min

Lignin amp tammin 3 0 10 0 10 30 minLignin amp tamminremoval

30 ndash 100 10 ndash 30 min

Municipal wastewater 50 ndash 150+ 15 ndash 30 min

Ozone Water TreatmentOzone Water TreatmentOzone Ozone ndashndash Municipal ApplicationsMunicipal Applications

bullbull Taste and OdorTaste and Odor

bullbull Color RemovalColor Removal

bullbull Disinfection Without Trihalomethanes (THMs)Disinfection Without Trihalomethanes (THMs)

bullbull Improved Filtration Efficiency and FlocculationImproved Filtration Efficiency and Flocculation

bullbull Cryptosporidium DeactivationCryptosporidium Deactivation

bullbull Giardia amp Virus InactivationGiardia amp Virus Inactivation

bullbull Oxidation Oxidation -- Organics Fe amp MnOrganics Fe amp Mn

bullbull Wastewater disinfectionWastewater disinfection

bullbull BOD COD and TOC reductionBOD COD and TOC reduction

Applications of Ozone

Wastewater Treatmentbull Disinfection of Secondary and Tertiary Effluentsbull Color Reductionbull Color Reductionbull TOC Oxidation (Industrial)bull Oxidation of Odor Causing Compoundsbull Oxidation of Endocrine Disruptors (EDCrsquos) and p ( )

Pharmaceutically Active Compounds (PACrsquos)

Applications of Ozone

What are Endocrine Disruptors (EDCrsquos) and What are Endocrine Disruptors (EDCrsquos) and Ph ti ll A ti C d (PACrsquo )Ph ti ll A ti C d (PACrsquo )Pharmaceutically Active Compounds (PACrsquos)Pharmaceutically Active Compounds (PACrsquos)

bullbull EDCrsquosEDCrsquos andand PACrsquosPACrsquos areare NaturallyNaturally andand SyntheticSyntheticdd th tth t ff tff t thth b lb l llcompoundscompounds thatthat maymay affectaffect thethe balancebalance oror normalnormal

functionsfunctions inin animalsanimals andand humanshumans

What can EDCrsquos and PACrsquos doWhat can EDCrsquos and PACrsquos do

bullbull Even in very small concentrations these compounds Even in very small concentrations these compounds y py pcan can disruptdisrupt normal bodily functionsnormal bodily functions

bullbull ManMan--made chemicals can trick the bodies endocrine made chemicals can trick the bodies endocrine system system

Applications of Ozone

Examples of Endocrine Disruptors1000rsquos of compounds that may be Investigated as EDCs ndash Some examples are

bullbull Synthetic HormonesSynthetic Hormonesbullbull Naturally Occurring Estrogens Naturally Occurring Estrogens

Health and Beauty AidsHealth and Beauty Aidsbullbull Health and Beauty AidsHealth and Beauty Aidsbullbull SolventsSolventsbullbull PesticidesPesticidesbullbull SurfactantsSurfactantsbullbull PlasticsPlastics

F i idF i idbullbull FungicidesFungicides

Ozone Water TreatmentOzone Water Treatment

Ozone Ozone -- Industrial ApplicationsIndustrial Applications-- Ultrapure Water for Pharmaceutical ApplicationsUltrapure Water for Pharmaceutical Applications

-- Wastewater disinfection color removalWastewater disinfection color removal

-- Soil and Groundwater Remediation Soil and Groundwater Remediation

-- Cooling Tower Water TreatmentCooling Tower Water Treatment

-- Food ProcessingFood Processing

-- Aquaculture AquariumsAquaculture AquariumsAquaculture AquariumsAquaculture Aquariums

-- Beverage ApplicationsBeverage Applications

P l amp P Bl hiP l amp P Bl hi-- Pulp amp Paper BleachingPulp amp Paper Bleaching

High Purity OzonationHigh Purity Ozonation

Microchip manufacturingMicrochip manufacturing

What are the current issues in large-scale gozone generationg

Experimental Setup

Front view of the two units after the redesign and reworking ofthe gas water and instruments connectionsthe gas water and instruments connections

Experimental Setup

Top view of the twoexperimental unitsexperimental unitsSpectroscope (notshown) is to the left ofthe DBD The units weredifferent with respect todifferent with respect totheir electrodes onehad only the electrodecoated with thedielectric (ldquosingle-dielectric ( single-coatedrdquo) the other onehad the electrode andthe anode coated withthe dielectric (ldquodouble-the dielectric ( double-coatedrdquo)

Basics Generation of OzoneBasics Generation of Ozone

SpectroscopyPlasma

Plasma Absorption SpectroscopyPlasma Absorption Spectroscopy

Infrared Absorption SpectroscopyInfrared Absorption Spectroscopy

IR spectra in pure oxygen (black curve) and at approximately 10wt N2 admixture (red line) N2O5 peaks appear at124 1 d 1 2 11245 cm-1 and at 1725 cm-1

Infrared Absorption SpectroscopyInfrared Absorption Spectroscopy

IR spectra of several methane variations The green curve envelopes all of the methane peaks at 1325 cm-1recorded at smaller methane admixtures Simultaneously the N2O5 peaks disappear as the methane peaks appear

N2O5 FormationN2O5 Formation2 52 5p=2 bara cwt=20degC q=35kWm2 f=1450Hz

45N2O5 AT95

30

35

40

N

2 B

lend

ing

N2O AT95N2O5 IGSN2O IGSN2O5 LGN2O LG

1 5

20

25

nt [p

pmV]

3

wt

05

10

15

NO

x co

nten

005 7 9 11 13 15 17

ozone conc [wt]

Amount of formed N2O5 and N2O as a function of ozone concentration at 3 wt of nitrogen admixture and fori l dvarious electrode arrangements

Plasma Emission SpectroscopyPlasma Emission Spectroscopyp pyp py

Relative Emissions of the Ozonizer plasmaRelative Emissions of the Ozonizer plasma

Region 300- 850 nm from individual (calibrated) regions (smoothed by PeakFit) Single-coated ozone generator Inlet side

3 5E+06

30E+06

35E+06

7 9

20E+06

25E+06

nten

sity

au

2

311 12

10E+06

15E+06

In 4

5

6 8 10

14

15

16

17

00E+00

50E+05

280 300 320 340 360 380 400 420 440 460 480 500 520 540 560 580 600 620 640 660 680 700 720 740 760 780 800 820 840 860

Wavelength nm

1 13

Wavelength nm

Absolute Emission of the DBD PlasmaAbsolute Emission of the DBD Plasma

Intensities in (O2+3 wtN2) plasma

1 20E+04

100E+04

120E+04

600E+03

800E+03

nten

sity

(au

)

200E+03

400E+03

In

O(777)

000E+00200 250 300 350 400 450 500 550 600 650 700 750 800 850

Wavelength nm

Intensities in 3 wtN2+O2 plasmaIntensities in 3 wtN2+O2 plasma

Plasma Chemistry in OzonizersPlasma Chemistry in Ozonizers

Dry Air O2 N2

e - e -

O N2 N O2

O3 NO

O2 N O2

O3

N

3

NO2

O2 O3

NO

N

NO2 O3

N2O

NO3 N

N2O4

NO2

NO2

N2O5

NO3

Primary electron-driven chemical reactions leading to the formation of N2O5 and N2O in a dry air plasma

Plasma emission diagnostics role of N2Plasma emission diagnostics role of N2

Dry Air O2 N2

e - e -

O N2 N O2

O3 NO

O2 N O2

O3

O

N

ON

NO2

O2O3

N

NO N

NO2 O3

N2O

NO3 N

N2O4

NO2

NO2

N2O5

NO3

ONbullWith N2 present ndash less oxygen atoms are formed However the difference in intensity is

very small

Modeling of plasma chemistry incl the NxOy chemistry up to N2O5 for different Oxygen Nitrogen mixtures varying power deposition scenarios

and initial ozone background concentrations (up to 15) previously done

The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation

The role of N2 must be related to its by-products reacting on the surface of the electrodeThe role of N2 must be related to its by-products reacting on the surface of the electrode

The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established

Ab 8 t f O

The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established

Ab 8 t f OAbove 8 wt of O3

1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)

Above 8 wt of O3

1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)case without pampp)

2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of the

case without pampp)

2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of thethem A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface

them A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface

The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation

Three possibilities have to be considered for the oxygen-fedozone generator

Three possibilities have to be considered for the oxygen-fedozone generatorozone generator

bull Excited N2 molecules lead to an increased O2 dissociation in

ozone generator

bull Excited N2 molecules lead to an increased O2 dissociation in2 2such case an increased efficiency is correlated to the N2admixture

2 2such case an increased efficiency is correlated to the N2admixture

bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial

bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial

bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2

bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2g p g 3 pp y 2g p g 3 pp y 2

Effect of methane on ozone efficiency and specific powerEffect of methane on ozone efficiency and specific power

Effect of Methane on Ozone Content in Outlet Gas and on Specific Power Pure O2

13 12

10

11

12

t 8

10

8

9

10

ne c

onte

nt w

t

6

8

ecifi

c po

wer

kW

hlb

5

6

7

Ozo

n

2

4 Spe

400E+00 20E+03 40E+03 60E+03 80E+03 10E+04 12E+04

Methane in feedgas ppm

0

Ozone content in the outlet gas Specif ic pow er of the ozone generatorg p p g

Effects of N2 and CH4Effects of N2 and CH4

Pi t f h t lli N O t tPicture of an amorphous-crystalline N2O5 structurecaptured at the Orlando Skylake water plant in 2006

Plasma Chemistry with CH4 Impurities

OxygenO2 N2

e - e -

CHO N2

NO2

O NO

O2 N O2 O3

NOH

CH4e-

O3 NO

NO2

O2O3NO N

NO2 O

NO2

NO2

N2ONO3

N

O3

NO2

NO

HNO3

N2O4

N2O5

NO2

NO3

N2O5

Effect of methane on the electrode surfaces

a) b)

Inlet Outlet Outlet

) d)

I l t I l t

c) d)

Electrode of the ozone generator afterseveral hours in CH8O2 and up to 2 wt of methane (a b c)

Inlet Inlet

three hours in CH8O2+traces of N2 and up to 1 wt of methane (d) Visible change of discharge character at about 13 length of electrode (a d)

Kinetics of CHx Conversion without N2

conversion by collisions

O2 + CHx 12wt O3 + CO2 +H2O

deposition vaporizationby sputtering

ibl b l 1000 CHreversible process below 1000ppm CH4

Effect of water on electrode surface with N2

Inlet

OutletOutlet

Electrode of the ozone generator after several hours in H OO N

Inlet

Electrode of the ozone generator after several hours in H2OO2N2

Effect of water on electrode surface

Long term effect (800 hrs) of H2OO2N2

Kinetics of CHx Conversion with N2

conversion by collisionsHNO3 formation

O2 + N2 +CHx 12wtO2 + CO2 +H2O + HNO3

deposition vaporizationby sputtering

H2O + HNO3

by sputtering

irreversible process above a N2 threshold () ltlt 1000ppm N2

sticky deposit

p 2 ( ) pp 2 any CH4 concentration (60ppm)

Plasma Chemistry with CH4 ImpuritiesPlasma Chemistry with CH4 Impurities4

bull Formation of NO and NO2 depends on O3 N2 and gas temperature Conclusion N2 admixture is the key factor

SummarySummaryyyThe mechanisms of formed NOx by-products follows the sameThe mechanisms of formed NOx by-products follows the sameprinciples as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentration

principles as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentrationozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)

ozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)g p ( g p )

The conversion of methane to OH and H2O is found to depend on

g p ( g p )

The conversion of methane to OH and H2O is found to depend ondissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)

dissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)discharge gap)discharge gap)

How do you optimize an ozone generatorg

Scientific ApproachScientific ApproachTheoretical Experimental

pppp

c [wt]

f [Hz]

c [wt]

f [Hz]

[kW]UUUβ1

1Cf4αPn

1iiminpeakimin

iiD

q [kWm2]q [kWm2]

150

180

][V]voltagepeakUpeak

[]cylinder perslicesofamountnsliceii

whereth

09 00

30

60

90

120

effic

ienc

y [

][0tdj t bl[F]sliceisdielectricofecapacitancC

[Hz]frequencyf[V]sliceivoltageminimumiUmin

thiD

th

10

28

46

64

82

39

107

176

244 power density

[kWm2]

ozone conc [wt][]CCβ

][0parameteradjustableα

iDiGi

Impact of Power Inductionp

350

400

wer

200

250

300

App

lied

Pow

Arr C 2Arr D +0

Arr E +45Arr F +7

Arr G +3

5 0

100

150

Frac

tion

of

1 2 3 4

ReferenceArr B unstable

Arr C -2

00

50

4Position (1inlet 4outlet)

Experimental Test Rigp g

Experimental Test Rigp g

Outer grounded electrode (left picture) and the dielectric covered inner electrodes (right) d e ect c cove ed e e ect odes ( g t)

Reference (Traditional) Arrangement

Inlet OutletGas flow direction

Optimized Arrangement

Inlet OutletGas flow direction

Intelligent Gap System (IGS)g p y ( )

Molecular Oxygen (O2) Ozone (O3)

O2 O3

yg ( 2) ( 3)

Particle Size SynthesisParticle Size SynthesisByBy--Products Cluster FormationProducts Cluster Formationyy

high diffusion and deposition to surfaces

low diffusion rate good transport

high sedimentation on the structurehigh sedimentation on the structure

Degreacutemont Technologies ndash OzoniaIntelligent Gap SystemIntelligent Gap System

G Vezzuacute JL Lopez A Freilich and K Becker Optimizationof Large-Scale Ozone Generators IEEE Transactions onPlasma Science Vol 37 No 6 p 890-896 (2009)

ConclusionsConclusionsConclusionsConclusionsFundamentals of ozone synthesis in a DBD plasmay p

ndash Highly filamented DBD discharges are best-suitedfor the production of ozone concentrations in therange of 6 to 14 wtrange of 6 to 14 wt

ndash The preferred characteristic of the microdischargesare Townsend-like at reduced electric fields Enaround 190 Townsend

ndash Detrimental side-effects induced by by-productscan be avoided by a proper design of the electrodecan be avoided by a proper design of the electrodearrangement The phenomenon is related to thediffusion rates of formed by-product clusters

ConclusionsConclusionsConclusionsConclusionsBenefits from DBD microplasma tailoring

ndash Reduced power consumption of up to 10 improvement

ndash Increased ozone concentrations of up to 14 now achievable

ndash Improved neutralization and conditioning of detrimental by-products

ndash Reduced system capital and operational cost

New technologies to improve ozone p

generatorg

HV Pulsed Power SwitchingHV Pulsed Power Switching

Microchannel Generation of Ozone

Channel ArrayChannel Array

Microchannel

330 microm 230 microm

Some Cap-DBD Devices Operating in Air

Increase of 60 of

Spacing 225 μmof 60 of plasma

No space

Cap‐DBD ozone generation

bull Ozone concentration is evaluated via Eco S d l UV 100 O A l (0 01Sensors model UV-100 Ozone Analyzer (001 ndash 900 ppm wiht an accuracy of plusmn2)

bull Three reactors 6 tubings 6rdquo with spacings of 0 μm 225 μm and 500 μm running at 3 kV μ μ μ g

SpacingOzone Concentration

3 kV rms 4 kV rms3 kV rms 4 kV rms

0 μm 660 ppm

225 μm 550 ppm

For a device of such small scale these ozone levels are promising

500 μm 380 ppm

J Mahoney W Zhu VS Johnson KH Becker and JL Lopez Electrical and optical emissionmeasurements of a capillary dielectric barrier discharge European Physics Journal D Vol 60 441-447(2010)

QuestionsQuestions

Thank YouFor more informationProf Jose L Lopez PhD

Thank YouFor more informationDepartment of Physics

Telephone (973) 761-9057Email joselopez1shuedu

Website wwwshueduacademicsartsciphysicsWebsite wwwshueduacademicsartsciphysics

Page 43: Dielectric Barrier Discharge (DBD) & Progress in Large ...bonitz/si12/talks/august_8/lopez_si12.pdf · Dielectric Barrier Discharge (DBD) & Progress in Large-Scale Ozone Generation

Traditional

Ozone Generator

with Glass Tubes

Generation of OzoneGeneration of Ozone

Generation of OzoneAdvantages of Enamel Dielectrics

Proven Patented Designbull Simplicity

Si l Di l i Cbull Single Dielectric Componentndash Reduced number of Dielectrics

bull Safety ndash Lower operating voltage

(lt 4000 V)bull Reliabilty

ndash Fused Dielectrics ensure continuous production

bull Lowest Power Consumption Operational Savingsndash Operational Savings

Modern Ozone GeneratorModern Ozone Generator

Ozonia Advanced Technology Ozone GeneratorOzone Generator

Generation of OzoneGeneration of Ozone

Generation of Ozone

Power Supply UnitPower Supply Unit

IGBT Inverter CircuitMain Circuit Breaker

HV 480 Volts60 Hz3 Phase Supply

C I

450KVAPow er to

GeneratorFILTER

CONVERTER INVERTERTRANSFORMER

C I450KVA Power Stage

CONTACTOR

bull Latest in Power Semiconductor Technology Modular Design

bull Utilizes IGBTrsquos (Insulated Gate Bi‐Polar Transistors) Converter and Inverter Components

Ozone Water Treatment

B bbl Diff iB bbl Diff iBubble DiffusionBubble Diffusion

Easy to use

Low energy usage Low energy usage

Mass transfer efficiencies to gt 90

Ozone Process Flow DiagramOzone Process Flow DiagramVent to

Atmosphere

O OOxygen

Off-Gas Blower

Ozone Destruct Unit

10 12

O3O2

LOX

10-12 O3

Ozone Generators

Ozone Contact ChamberLOX T k Generators Chamber

VaporizersLOX Tank

Municipal Ozone Installations

Ozonia Installations Ozone Plant Size [lbday] Start-Up DateKey Ozonia Installations (Partial List)

Los Angeles CA 10000 1986Fairfax VA ndash Corbalis 9000 2003MWD CA ndash Mills 9 000 2003

Ozonia Installations Ozone Plant Size [lbday] Start Up Date

MWD CA Mills 9000 2003Fairfax Co VA ndash Griffith 9000 2004MWD CA ndash Jensen 18750 2005Indianapolis IN ndash Belmont AWT 12000 2007I di li IN 12 000 2007Indianapolis IN ndash Southport AWT 12000 2007MWD CA ndash Diemer 13400 2008MWD CA ndash Weymouth 13400 2009

Ozonia North America - Potable Water SummaryTotal Number of Installations 90Total Installed Production gt 265000 lbsdayTotal Installed Production 265000 lbsday

Revision -B

Ozone Water TreatmentOzone Water Treatment

MWD Mills WTP - California

3 3 000 lbsda of o one3 3 000 lbsda of o one3 x 3000 lbsday of ozone3 x 3000 lbsday of ozone

Ozone Water TreatmentOzone Water TreatmentOzone Ozone -- How it worksHow it works

OxidantOxidant DisinfectantDisinfectant

bullbull Breaks double carbon Breaks double carbon bondsbonds

bullbull Kills by cell lysing or Kills by cell lysing or causing the cell wall tocausing the cell wall tobondsbonds

bullbull Creates OHCreates OHbullbull radicals radicals which break higher carbon which break higher carbon

causing the cell wall to causing the cell wall to rupture rupture

bullbull AttacksAttacks allall bacteriabacteriabondsbondsbullbull Increased temp and pH Increased temp and pH

accelerates Oaccelerates O33

Attacks Attacks allall bacteria bacteria virus cysts and spores virus cysts and spores in varying degreesin varying degreesaccelerates Oaccelerates O33

decomposition to OHdecomposition to OHbullbull

Micro-organism DNA

Capsule AdenineAdenine

Cell wall ThymineThymine

CytosineCytosine

GuanineGuanine

NuclearmaterialCellmembrane

material

Typical Bacterium DNA

Microbial Growth at Various Ozone ConcentrationsConcentrations

Growth likely

Growth possibleGrowth possible

NO GROWTH

0004 0008 0012 0016 0020

Ozone concentration (mgl)Ozone concentration (mgl)

Typical Water Treatment UsageTypical Water Treatment Usage

Application O3 mgl Contact timeUltra Pure Water 005 - 025 sec ndash min

Water bottling 04 ndash 10 5 ndash 10 min

Swimming pools ampspas

01 ndash 075 4 minutes

Potable taste amp odor 15 ndash 50 5 ndash 10 mindisinfection

Microfloculation 10 ndash 30 5 ndash 10 min

Lignin amp tammin 3 0 10 0 10 30 minLignin amp tamminremoval

30 ndash 100 10 ndash 30 min

Municipal wastewater 50 ndash 150+ 15 ndash 30 min

Ozone Water TreatmentOzone Water TreatmentOzone Ozone ndashndash Municipal ApplicationsMunicipal Applications

bullbull Taste and OdorTaste and Odor

bullbull Color RemovalColor Removal

bullbull Disinfection Without Trihalomethanes (THMs)Disinfection Without Trihalomethanes (THMs)

bullbull Improved Filtration Efficiency and FlocculationImproved Filtration Efficiency and Flocculation

bullbull Cryptosporidium DeactivationCryptosporidium Deactivation

bullbull Giardia amp Virus InactivationGiardia amp Virus Inactivation

bullbull Oxidation Oxidation -- Organics Fe amp MnOrganics Fe amp Mn

bullbull Wastewater disinfectionWastewater disinfection

bullbull BOD COD and TOC reductionBOD COD and TOC reduction

Applications of Ozone

Wastewater Treatmentbull Disinfection of Secondary and Tertiary Effluentsbull Color Reductionbull Color Reductionbull TOC Oxidation (Industrial)bull Oxidation of Odor Causing Compoundsbull Oxidation of Endocrine Disruptors (EDCrsquos) and p ( )

Pharmaceutically Active Compounds (PACrsquos)

Applications of Ozone

What are Endocrine Disruptors (EDCrsquos) and What are Endocrine Disruptors (EDCrsquos) and Ph ti ll A ti C d (PACrsquo )Ph ti ll A ti C d (PACrsquo )Pharmaceutically Active Compounds (PACrsquos)Pharmaceutically Active Compounds (PACrsquos)

bullbull EDCrsquosEDCrsquos andand PACrsquosPACrsquos areare NaturallyNaturally andand SyntheticSyntheticdd th tth t ff tff t thth b lb l llcompoundscompounds thatthat maymay affectaffect thethe balancebalance oror normalnormal

functionsfunctions inin animalsanimals andand humanshumans

What can EDCrsquos and PACrsquos doWhat can EDCrsquos and PACrsquos do

bullbull Even in very small concentrations these compounds Even in very small concentrations these compounds y py pcan can disruptdisrupt normal bodily functionsnormal bodily functions

bullbull ManMan--made chemicals can trick the bodies endocrine made chemicals can trick the bodies endocrine system system

Applications of Ozone

Examples of Endocrine Disruptors1000rsquos of compounds that may be Investigated as EDCs ndash Some examples are

bullbull Synthetic HormonesSynthetic Hormonesbullbull Naturally Occurring Estrogens Naturally Occurring Estrogens

Health and Beauty AidsHealth and Beauty Aidsbullbull Health and Beauty AidsHealth and Beauty Aidsbullbull SolventsSolventsbullbull PesticidesPesticidesbullbull SurfactantsSurfactantsbullbull PlasticsPlastics

F i idF i idbullbull FungicidesFungicides

Ozone Water TreatmentOzone Water Treatment

Ozone Ozone -- Industrial ApplicationsIndustrial Applications-- Ultrapure Water for Pharmaceutical ApplicationsUltrapure Water for Pharmaceutical Applications

-- Wastewater disinfection color removalWastewater disinfection color removal

-- Soil and Groundwater Remediation Soil and Groundwater Remediation

-- Cooling Tower Water TreatmentCooling Tower Water Treatment

-- Food ProcessingFood Processing

-- Aquaculture AquariumsAquaculture AquariumsAquaculture AquariumsAquaculture Aquariums

-- Beverage ApplicationsBeverage Applications

P l amp P Bl hiP l amp P Bl hi-- Pulp amp Paper BleachingPulp amp Paper Bleaching

High Purity OzonationHigh Purity Ozonation

Microchip manufacturingMicrochip manufacturing

What are the current issues in large-scale gozone generationg

Experimental Setup

Front view of the two units after the redesign and reworking ofthe gas water and instruments connectionsthe gas water and instruments connections

Experimental Setup

Top view of the twoexperimental unitsexperimental unitsSpectroscope (notshown) is to the left ofthe DBD The units weredifferent with respect todifferent with respect totheir electrodes onehad only the electrodecoated with thedielectric (ldquosingle-dielectric ( single-coatedrdquo) the other onehad the electrode andthe anode coated withthe dielectric (ldquodouble-the dielectric ( double-coatedrdquo)

Basics Generation of OzoneBasics Generation of Ozone

SpectroscopyPlasma

Plasma Absorption SpectroscopyPlasma Absorption Spectroscopy

Infrared Absorption SpectroscopyInfrared Absorption Spectroscopy

IR spectra in pure oxygen (black curve) and at approximately 10wt N2 admixture (red line) N2O5 peaks appear at124 1 d 1 2 11245 cm-1 and at 1725 cm-1

Infrared Absorption SpectroscopyInfrared Absorption Spectroscopy

IR spectra of several methane variations The green curve envelopes all of the methane peaks at 1325 cm-1recorded at smaller methane admixtures Simultaneously the N2O5 peaks disappear as the methane peaks appear

N2O5 FormationN2O5 Formation2 52 5p=2 bara cwt=20degC q=35kWm2 f=1450Hz

45N2O5 AT95

30

35

40

N

2 B

lend

ing

N2O AT95N2O5 IGSN2O IGSN2O5 LGN2O LG

1 5

20

25

nt [p

pmV]

3

wt

05

10

15

NO

x co

nten

005 7 9 11 13 15 17

ozone conc [wt]

Amount of formed N2O5 and N2O as a function of ozone concentration at 3 wt of nitrogen admixture and fori l dvarious electrode arrangements

Plasma Emission SpectroscopyPlasma Emission Spectroscopyp pyp py

Relative Emissions of the Ozonizer plasmaRelative Emissions of the Ozonizer plasma

Region 300- 850 nm from individual (calibrated) regions (smoothed by PeakFit) Single-coated ozone generator Inlet side

3 5E+06

30E+06

35E+06

7 9

20E+06

25E+06

nten

sity

au

2

311 12

10E+06

15E+06

In 4

5

6 8 10

14

15

16

17

00E+00

50E+05

280 300 320 340 360 380 400 420 440 460 480 500 520 540 560 580 600 620 640 660 680 700 720 740 760 780 800 820 840 860

Wavelength nm

1 13

Wavelength nm

Absolute Emission of the DBD PlasmaAbsolute Emission of the DBD Plasma

Intensities in (O2+3 wtN2) plasma

1 20E+04

100E+04

120E+04

600E+03

800E+03

nten

sity

(au

)

200E+03

400E+03

In

O(777)

000E+00200 250 300 350 400 450 500 550 600 650 700 750 800 850

Wavelength nm

Intensities in 3 wtN2+O2 plasmaIntensities in 3 wtN2+O2 plasma

Plasma Chemistry in OzonizersPlasma Chemistry in Ozonizers

Dry Air O2 N2

e - e -

O N2 N O2

O3 NO

O2 N O2

O3

N

3

NO2

O2 O3

NO

N

NO2 O3

N2O

NO3 N

N2O4

NO2

NO2

N2O5

NO3

Primary electron-driven chemical reactions leading to the formation of N2O5 and N2O in a dry air plasma

Plasma emission diagnostics role of N2Plasma emission diagnostics role of N2

Dry Air O2 N2

e - e -

O N2 N O2

O3 NO

O2 N O2

O3

O

N

ON

NO2

O2O3

N

NO N

NO2 O3

N2O

NO3 N

N2O4

NO2

NO2

N2O5

NO3

ONbullWith N2 present ndash less oxygen atoms are formed However the difference in intensity is

very small

Modeling of plasma chemistry incl the NxOy chemistry up to N2O5 for different Oxygen Nitrogen mixtures varying power deposition scenarios

and initial ozone background concentrations (up to 15) previously done

The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation

The role of N2 must be related to its by-products reacting on the surface of the electrodeThe role of N2 must be related to its by-products reacting on the surface of the electrode

The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established

Ab 8 t f O

The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established

Ab 8 t f OAbove 8 wt of O3

1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)

Above 8 wt of O3

1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)case without pampp)

2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of the

case without pampp)

2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of thethem A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface

them A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface

The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation

Three possibilities have to be considered for the oxygen-fedozone generator

Three possibilities have to be considered for the oxygen-fedozone generatorozone generator

bull Excited N2 molecules lead to an increased O2 dissociation in

ozone generator

bull Excited N2 molecules lead to an increased O2 dissociation in2 2such case an increased efficiency is correlated to the N2admixture

2 2such case an increased efficiency is correlated to the N2admixture

bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial

bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial

bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2

bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2g p g 3 pp y 2g p g 3 pp y 2

Effect of methane on ozone efficiency and specific powerEffect of methane on ozone efficiency and specific power

Effect of Methane on Ozone Content in Outlet Gas and on Specific Power Pure O2

13 12

10

11

12

t 8

10

8

9

10

ne c

onte

nt w

t

6

8

ecifi

c po

wer

kW

hlb

5

6

7

Ozo

n

2

4 Spe

400E+00 20E+03 40E+03 60E+03 80E+03 10E+04 12E+04

Methane in feedgas ppm

0

Ozone content in the outlet gas Specif ic pow er of the ozone generatorg p p g

Effects of N2 and CH4Effects of N2 and CH4

Pi t f h t lli N O t tPicture of an amorphous-crystalline N2O5 structurecaptured at the Orlando Skylake water plant in 2006

Plasma Chemistry with CH4 Impurities

OxygenO2 N2

e - e -

CHO N2

NO2

O NO

O2 N O2 O3

NOH

CH4e-

O3 NO

NO2

O2O3NO N

NO2 O

NO2

NO2

N2ONO3

N

O3

NO2

NO

HNO3

N2O4

N2O5

NO2

NO3

N2O5

Effect of methane on the electrode surfaces

a) b)

Inlet Outlet Outlet

) d)

I l t I l t

c) d)

Electrode of the ozone generator afterseveral hours in CH8O2 and up to 2 wt of methane (a b c)

Inlet Inlet

three hours in CH8O2+traces of N2 and up to 1 wt of methane (d) Visible change of discharge character at about 13 length of electrode (a d)

Kinetics of CHx Conversion without N2

conversion by collisions

O2 + CHx 12wt O3 + CO2 +H2O

deposition vaporizationby sputtering

ibl b l 1000 CHreversible process below 1000ppm CH4

Effect of water on electrode surface with N2

Inlet

OutletOutlet

Electrode of the ozone generator after several hours in H OO N

Inlet

Electrode of the ozone generator after several hours in H2OO2N2

Effect of water on electrode surface

Long term effect (800 hrs) of H2OO2N2

Kinetics of CHx Conversion with N2

conversion by collisionsHNO3 formation

O2 + N2 +CHx 12wtO2 + CO2 +H2O + HNO3

deposition vaporizationby sputtering

H2O + HNO3

by sputtering

irreversible process above a N2 threshold () ltlt 1000ppm N2

sticky deposit

p 2 ( ) pp 2 any CH4 concentration (60ppm)

Plasma Chemistry with CH4 ImpuritiesPlasma Chemistry with CH4 Impurities4

bull Formation of NO and NO2 depends on O3 N2 and gas temperature Conclusion N2 admixture is the key factor

SummarySummaryyyThe mechanisms of formed NOx by-products follows the sameThe mechanisms of formed NOx by-products follows the sameprinciples as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentration

principles as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentrationozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)

ozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)g p ( g p )

The conversion of methane to OH and H2O is found to depend on

g p ( g p )

The conversion of methane to OH and H2O is found to depend ondissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)

dissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)discharge gap)discharge gap)

How do you optimize an ozone generatorg

Scientific ApproachScientific ApproachTheoretical Experimental

pppp

c [wt]

f [Hz]

c [wt]

f [Hz]

[kW]UUUβ1

1Cf4αPn

1iiminpeakimin

iiD

q [kWm2]q [kWm2]

150

180

][V]voltagepeakUpeak

[]cylinder perslicesofamountnsliceii

whereth

09 00

30

60

90

120

effic

ienc

y [

][0tdj t bl[F]sliceisdielectricofecapacitancC

[Hz]frequencyf[V]sliceivoltageminimumiUmin

thiD

th

10

28

46

64

82

39

107

176

244 power density

[kWm2]

ozone conc [wt][]CCβ

][0parameteradjustableα

iDiGi

Impact of Power Inductionp

350

400

wer

200

250

300

App

lied

Pow

Arr C 2Arr D +0

Arr E +45Arr F +7

Arr G +3

5 0

100

150

Frac

tion

of

1 2 3 4

ReferenceArr B unstable

Arr C -2

00

50

4Position (1inlet 4outlet)

Experimental Test Rigp g

Experimental Test Rigp g

Outer grounded electrode (left picture) and the dielectric covered inner electrodes (right) d e ect c cove ed e e ect odes ( g t)

Reference (Traditional) Arrangement

Inlet OutletGas flow direction

Optimized Arrangement

Inlet OutletGas flow direction

Intelligent Gap System (IGS)g p y ( )

Molecular Oxygen (O2) Ozone (O3)

O2 O3

yg ( 2) ( 3)

Particle Size SynthesisParticle Size SynthesisByBy--Products Cluster FormationProducts Cluster Formationyy

high diffusion and deposition to surfaces

low diffusion rate good transport

high sedimentation on the structurehigh sedimentation on the structure

Degreacutemont Technologies ndash OzoniaIntelligent Gap SystemIntelligent Gap System

G Vezzuacute JL Lopez A Freilich and K Becker Optimizationof Large-Scale Ozone Generators IEEE Transactions onPlasma Science Vol 37 No 6 p 890-896 (2009)

ConclusionsConclusionsConclusionsConclusionsFundamentals of ozone synthesis in a DBD plasmay p

ndash Highly filamented DBD discharges are best-suitedfor the production of ozone concentrations in therange of 6 to 14 wtrange of 6 to 14 wt

ndash The preferred characteristic of the microdischargesare Townsend-like at reduced electric fields Enaround 190 Townsend

ndash Detrimental side-effects induced by by-productscan be avoided by a proper design of the electrodecan be avoided by a proper design of the electrodearrangement The phenomenon is related to thediffusion rates of formed by-product clusters

ConclusionsConclusionsConclusionsConclusionsBenefits from DBD microplasma tailoring

ndash Reduced power consumption of up to 10 improvement

ndash Increased ozone concentrations of up to 14 now achievable

ndash Improved neutralization and conditioning of detrimental by-products

ndash Reduced system capital and operational cost

New technologies to improve ozone p

generatorg

HV Pulsed Power SwitchingHV Pulsed Power Switching

Microchannel Generation of Ozone

Channel ArrayChannel Array

Microchannel

330 microm 230 microm

Some Cap-DBD Devices Operating in Air

Increase of 60 of

Spacing 225 μmof 60 of plasma

No space

Cap‐DBD ozone generation

bull Ozone concentration is evaluated via Eco S d l UV 100 O A l (0 01Sensors model UV-100 Ozone Analyzer (001 ndash 900 ppm wiht an accuracy of plusmn2)

bull Three reactors 6 tubings 6rdquo with spacings of 0 μm 225 μm and 500 μm running at 3 kV μ μ μ g

SpacingOzone Concentration

3 kV rms 4 kV rms3 kV rms 4 kV rms

0 μm 660 ppm

225 μm 550 ppm

For a device of such small scale these ozone levels are promising

500 μm 380 ppm

J Mahoney W Zhu VS Johnson KH Becker and JL Lopez Electrical and optical emissionmeasurements of a capillary dielectric barrier discharge European Physics Journal D Vol 60 441-447(2010)

QuestionsQuestions

Thank YouFor more informationProf Jose L Lopez PhD

Thank YouFor more informationDepartment of Physics

Telephone (973) 761-9057Email joselopez1shuedu

Website wwwshueduacademicsartsciphysicsWebsite wwwshueduacademicsartsciphysics

Page 44: Dielectric Barrier Discharge (DBD) & Progress in Large ...bonitz/si12/talks/august_8/lopez_si12.pdf · Dielectric Barrier Discharge (DBD) & Progress in Large-Scale Ozone Generation

Generation of OzoneGeneration of Ozone

Generation of OzoneAdvantages of Enamel Dielectrics

Proven Patented Designbull Simplicity

Si l Di l i Cbull Single Dielectric Componentndash Reduced number of Dielectrics

bull Safety ndash Lower operating voltage

(lt 4000 V)bull Reliabilty

ndash Fused Dielectrics ensure continuous production

bull Lowest Power Consumption Operational Savingsndash Operational Savings

Modern Ozone GeneratorModern Ozone Generator

Ozonia Advanced Technology Ozone GeneratorOzone Generator

Generation of OzoneGeneration of Ozone

Generation of Ozone

Power Supply UnitPower Supply Unit

IGBT Inverter CircuitMain Circuit Breaker

HV 480 Volts60 Hz3 Phase Supply

C I

450KVAPow er to

GeneratorFILTER

CONVERTER INVERTERTRANSFORMER

C I450KVA Power Stage

CONTACTOR

bull Latest in Power Semiconductor Technology Modular Design

bull Utilizes IGBTrsquos (Insulated Gate Bi‐Polar Transistors) Converter and Inverter Components

Ozone Water Treatment

B bbl Diff iB bbl Diff iBubble DiffusionBubble Diffusion

Easy to use

Low energy usage Low energy usage

Mass transfer efficiencies to gt 90

Ozone Process Flow DiagramOzone Process Flow DiagramVent to

Atmosphere

O OOxygen

Off-Gas Blower

Ozone Destruct Unit

10 12

O3O2

LOX

10-12 O3

Ozone Generators

Ozone Contact ChamberLOX T k Generators Chamber

VaporizersLOX Tank

Municipal Ozone Installations

Ozonia Installations Ozone Plant Size [lbday] Start-Up DateKey Ozonia Installations (Partial List)

Los Angeles CA 10000 1986Fairfax VA ndash Corbalis 9000 2003MWD CA ndash Mills 9 000 2003

Ozonia Installations Ozone Plant Size [lbday] Start Up Date

MWD CA Mills 9000 2003Fairfax Co VA ndash Griffith 9000 2004MWD CA ndash Jensen 18750 2005Indianapolis IN ndash Belmont AWT 12000 2007I di li IN 12 000 2007Indianapolis IN ndash Southport AWT 12000 2007MWD CA ndash Diemer 13400 2008MWD CA ndash Weymouth 13400 2009

Ozonia North America - Potable Water SummaryTotal Number of Installations 90Total Installed Production gt 265000 lbsdayTotal Installed Production 265000 lbsday

Revision -B

Ozone Water TreatmentOzone Water Treatment

MWD Mills WTP - California

3 3 000 lbsda of o one3 3 000 lbsda of o one3 x 3000 lbsday of ozone3 x 3000 lbsday of ozone

Ozone Water TreatmentOzone Water TreatmentOzone Ozone -- How it worksHow it works

OxidantOxidant DisinfectantDisinfectant

bullbull Breaks double carbon Breaks double carbon bondsbonds

bullbull Kills by cell lysing or Kills by cell lysing or causing the cell wall tocausing the cell wall tobondsbonds

bullbull Creates OHCreates OHbullbull radicals radicals which break higher carbon which break higher carbon

causing the cell wall to causing the cell wall to rupture rupture

bullbull AttacksAttacks allall bacteriabacteriabondsbondsbullbull Increased temp and pH Increased temp and pH

accelerates Oaccelerates O33

Attacks Attacks allall bacteria bacteria virus cysts and spores virus cysts and spores in varying degreesin varying degreesaccelerates Oaccelerates O33

decomposition to OHdecomposition to OHbullbull

Micro-organism DNA

Capsule AdenineAdenine

Cell wall ThymineThymine

CytosineCytosine

GuanineGuanine

NuclearmaterialCellmembrane

material

Typical Bacterium DNA

Microbial Growth at Various Ozone ConcentrationsConcentrations

Growth likely

Growth possibleGrowth possible

NO GROWTH

0004 0008 0012 0016 0020

Ozone concentration (mgl)Ozone concentration (mgl)

Typical Water Treatment UsageTypical Water Treatment Usage

Application O3 mgl Contact timeUltra Pure Water 005 - 025 sec ndash min

Water bottling 04 ndash 10 5 ndash 10 min

Swimming pools ampspas

01 ndash 075 4 minutes

Potable taste amp odor 15 ndash 50 5 ndash 10 mindisinfection

Microfloculation 10 ndash 30 5 ndash 10 min

Lignin amp tammin 3 0 10 0 10 30 minLignin amp tamminremoval

30 ndash 100 10 ndash 30 min

Municipal wastewater 50 ndash 150+ 15 ndash 30 min

Ozone Water TreatmentOzone Water TreatmentOzone Ozone ndashndash Municipal ApplicationsMunicipal Applications

bullbull Taste and OdorTaste and Odor

bullbull Color RemovalColor Removal

bullbull Disinfection Without Trihalomethanes (THMs)Disinfection Without Trihalomethanes (THMs)

bullbull Improved Filtration Efficiency and FlocculationImproved Filtration Efficiency and Flocculation

bullbull Cryptosporidium DeactivationCryptosporidium Deactivation

bullbull Giardia amp Virus InactivationGiardia amp Virus Inactivation

bullbull Oxidation Oxidation -- Organics Fe amp MnOrganics Fe amp Mn

bullbull Wastewater disinfectionWastewater disinfection

bullbull BOD COD and TOC reductionBOD COD and TOC reduction

Applications of Ozone

Wastewater Treatmentbull Disinfection of Secondary and Tertiary Effluentsbull Color Reductionbull Color Reductionbull TOC Oxidation (Industrial)bull Oxidation of Odor Causing Compoundsbull Oxidation of Endocrine Disruptors (EDCrsquos) and p ( )

Pharmaceutically Active Compounds (PACrsquos)

Applications of Ozone

What are Endocrine Disruptors (EDCrsquos) and What are Endocrine Disruptors (EDCrsquos) and Ph ti ll A ti C d (PACrsquo )Ph ti ll A ti C d (PACrsquo )Pharmaceutically Active Compounds (PACrsquos)Pharmaceutically Active Compounds (PACrsquos)

bullbull EDCrsquosEDCrsquos andand PACrsquosPACrsquos areare NaturallyNaturally andand SyntheticSyntheticdd th tth t ff tff t thth b lb l llcompoundscompounds thatthat maymay affectaffect thethe balancebalance oror normalnormal

functionsfunctions inin animalsanimals andand humanshumans

What can EDCrsquos and PACrsquos doWhat can EDCrsquos and PACrsquos do

bullbull Even in very small concentrations these compounds Even in very small concentrations these compounds y py pcan can disruptdisrupt normal bodily functionsnormal bodily functions

bullbull ManMan--made chemicals can trick the bodies endocrine made chemicals can trick the bodies endocrine system system

Applications of Ozone

Examples of Endocrine Disruptors1000rsquos of compounds that may be Investigated as EDCs ndash Some examples are

bullbull Synthetic HormonesSynthetic Hormonesbullbull Naturally Occurring Estrogens Naturally Occurring Estrogens

Health and Beauty AidsHealth and Beauty Aidsbullbull Health and Beauty AidsHealth and Beauty Aidsbullbull SolventsSolventsbullbull PesticidesPesticidesbullbull SurfactantsSurfactantsbullbull PlasticsPlastics

F i idF i idbullbull FungicidesFungicides

Ozone Water TreatmentOzone Water Treatment

Ozone Ozone -- Industrial ApplicationsIndustrial Applications-- Ultrapure Water for Pharmaceutical ApplicationsUltrapure Water for Pharmaceutical Applications

-- Wastewater disinfection color removalWastewater disinfection color removal

-- Soil and Groundwater Remediation Soil and Groundwater Remediation

-- Cooling Tower Water TreatmentCooling Tower Water Treatment

-- Food ProcessingFood Processing

-- Aquaculture AquariumsAquaculture AquariumsAquaculture AquariumsAquaculture Aquariums

-- Beverage ApplicationsBeverage Applications

P l amp P Bl hiP l amp P Bl hi-- Pulp amp Paper BleachingPulp amp Paper Bleaching

High Purity OzonationHigh Purity Ozonation

Microchip manufacturingMicrochip manufacturing

What are the current issues in large-scale gozone generationg

Experimental Setup

Front view of the two units after the redesign and reworking ofthe gas water and instruments connectionsthe gas water and instruments connections

Experimental Setup

Top view of the twoexperimental unitsexperimental unitsSpectroscope (notshown) is to the left ofthe DBD The units weredifferent with respect todifferent with respect totheir electrodes onehad only the electrodecoated with thedielectric (ldquosingle-dielectric ( single-coatedrdquo) the other onehad the electrode andthe anode coated withthe dielectric (ldquodouble-the dielectric ( double-coatedrdquo)

Basics Generation of OzoneBasics Generation of Ozone

SpectroscopyPlasma

Plasma Absorption SpectroscopyPlasma Absorption Spectroscopy

Infrared Absorption SpectroscopyInfrared Absorption Spectroscopy

IR spectra in pure oxygen (black curve) and at approximately 10wt N2 admixture (red line) N2O5 peaks appear at124 1 d 1 2 11245 cm-1 and at 1725 cm-1

Infrared Absorption SpectroscopyInfrared Absorption Spectroscopy

IR spectra of several methane variations The green curve envelopes all of the methane peaks at 1325 cm-1recorded at smaller methane admixtures Simultaneously the N2O5 peaks disappear as the methane peaks appear

N2O5 FormationN2O5 Formation2 52 5p=2 bara cwt=20degC q=35kWm2 f=1450Hz

45N2O5 AT95

30

35

40

N

2 B

lend

ing

N2O AT95N2O5 IGSN2O IGSN2O5 LGN2O LG

1 5

20

25

nt [p

pmV]

3

wt

05

10

15

NO

x co

nten

005 7 9 11 13 15 17

ozone conc [wt]

Amount of formed N2O5 and N2O as a function of ozone concentration at 3 wt of nitrogen admixture and fori l dvarious electrode arrangements

Plasma Emission SpectroscopyPlasma Emission Spectroscopyp pyp py

Relative Emissions of the Ozonizer plasmaRelative Emissions of the Ozonizer plasma

Region 300- 850 nm from individual (calibrated) regions (smoothed by PeakFit) Single-coated ozone generator Inlet side

3 5E+06

30E+06

35E+06

7 9

20E+06

25E+06

nten

sity

au

2

311 12

10E+06

15E+06

In 4

5

6 8 10

14

15

16

17

00E+00

50E+05

280 300 320 340 360 380 400 420 440 460 480 500 520 540 560 580 600 620 640 660 680 700 720 740 760 780 800 820 840 860

Wavelength nm

1 13

Wavelength nm

Absolute Emission of the DBD PlasmaAbsolute Emission of the DBD Plasma

Intensities in (O2+3 wtN2) plasma

1 20E+04

100E+04

120E+04

600E+03

800E+03

nten

sity

(au

)

200E+03

400E+03

In

O(777)

000E+00200 250 300 350 400 450 500 550 600 650 700 750 800 850

Wavelength nm

Intensities in 3 wtN2+O2 plasmaIntensities in 3 wtN2+O2 plasma

Plasma Chemistry in OzonizersPlasma Chemistry in Ozonizers

Dry Air O2 N2

e - e -

O N2 N O2

O3 NO

O2 N O2

O3

N

3

NO2

O2 O3

NO

N

NO2 O3

N2O

NO3 N

N2O4

NO2

NO2

N2O5

NO3

Primary electron-driven chemical reactions leading to the formation of N2O5 and N2O in a dry air plasma

Plasma emission diagnostics role of N2Plasma emission diagnostics role of N2

Dry Air O2 N2

e - e -

O N2 N O2

O3 NO

O2 N O2

O3

O

N

ON

NO2

O2O3

N

NO N

NO2 O3

N2O

NO3 N

N2O4

NO2

NO2

N2O5

NO3

ONbullWith N2 present ndash less oxygen atoms are formed However the difference in intensity is

very small

Modeling of plasma chemistry incl the NxOy chemistry up to N2O5 for different Oxygen Nitrogen mixtures varying power deposition scenarios

and initial ozone background concentrations (up to 15) previously done

The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation

The role of N2 must be related to its by-products reacting on the surface of the electrodeThe role of N2 must be related to its by-products reacting on the surface of the electrode

The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established

Ab 8 t f O

The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established

Ab 8 t f OAbove 8 wt of O3

1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)

Above 8 wt of O3

1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)case without pampp)

2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of the

case without pampp)

2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of thethem A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface

them A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface

The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation

Three possibilities have to be considered for the oxygen-fedozone generator

Three possibilities have to be considered for the oxygen-fedozone generatorozone generator

bull Excited N2 molecules lead to an increased O2 dissociation in

ozone generator

bull Excited N2 molecules lead to an increased O2 dissociation in2 2such case an increased efficiency is correlated to the N2admixture

2 2such case an increased efficiency is correlated to the N2admixture

bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial

bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial

bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2

bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2g p g 3 pp y 2g p g 3 pp y 2

Effect of methane on ozone efficiency and specific powerEffect of methane on ozone efficiency and specific power

Effect of Methane on Ozone Content in Outlet Gas and on Specific Power Pure O2

13 12

10

11

12

t 8

10

8

9

10

ne c

onte

nt w

t

6

8

ecifi

c po

wer

kW

hlb

5

6

7

Ozo

n

2

4 Spe

400E+00 20E+03 40E+03 60E+03 80E+03 10E+04 12E+04

Methane in feedgas ppm

0

Ozone content in the outlet gas Specif ic pow er of the ozone generatorg p p g

Effects of N2 and CH4Effects of N2 and CH4

Pi t f h t lli N O t tPicture of an amorphous-crystalline N2O5 structurecaptured at the Orlando Skylake water plant in 2006

Plasma Chemistry with CH4 Impurities

OxygenO2 N2

e - e -

CHO N2

NO2

O NO

O2 N O2 O3

NOH

CH4e-

O3 NO

NO2

O2O3NO N

NO2 O

NO2

NO2

N2ONO3

N

O3

NO2

NO

HNO3

N2O4

N2O5

NO2

NO3

N2O5

Effect of methane on the electrode surfaces

a) b)

Inlet Outlet Outlet

) d)

I l t I l t

c) d)

Electrode of the ozone generator afterseveral hours in CH8O2 and up to 2 wt of methane (a b c)

Inlet Inlet

three hours in CH8O2+traces of N2 and up to 1 wt of methane (d) Visible change of discharge character at about 13 length of electrode (a d)

Kinetics of CHx Conversion without N2

conversion by collisions

O2 + CHx 12wt O3 + CO2 +H2O

deposition vaporizationby sputtering

ibl b l 1000 CHreversible process below 1000ppm CH4

Effect of water on electrode surface with N2

Inlet

OutletOutlet

Electrode of the ozone generator after several hours in H OO N

Inlet

Electrode of the ozone generator after several hours in H2OO2N2

Effect of water on electrode surface

Long term effect (800 hrs) of H2OO2N2

Kinetics of CHx Conversion with N2

conversion by collisionsHNO3 formation

O2 + N2 +CHx 12wtO2 + CO2 +H2O + HNO3

deposition vaporizationby sputtering

H2O + HNO3

by sputtering

irreversible process above a N2 threshold () ltlt 1000ppm N2

sticky deposit

p 2 ( ) pp 2 any CH4 concentration (60ppm)

Plasma Chemistry with CH4 ImpuritiesPlasma Chemistry with CH4 Impurities4

bull Formation of NO and NO2 depends on O3 N2 and gas temperature Conclusion N2 admixture is the key factor

SummarySummaryyyThe mechanisms of formed NOx by-products follows the sameThe mechanisms of formed NOx by-products follows the sameprinciples as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentration

principles as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentrationozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)

ozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)g p ( g p )

The conversion of methane to OH and H2O is found to depend on

g p ( g p )

The conversion of methane to OH and H2O is found to depend ondissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)

dissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)discharge gap)discharge gap)

How do you optimize an ozone generatorg

Scientific ApproachScientific ApproachTheoretical Experimental

pppp

c [wt]

f [Hz]

c [wt]

f [Hz]

[kW]UUUβ1

1Cf4αPn

1iiminpeakimin

iiD

q [kWm2]q [kWm2]

150

180

][V]voltagepeakUpeak

[]cylinder perslicesofamountnsliceii

whereth

09 00

30

60

90

120

effic

ienc

y [

][0tdj t bl[F]sliceisdielectricofecapacitancC

[Hz]frequencyf[V]sliceivoltageminimumiUmin

thiD

th

10

28

46

64

82

39

107

176

244 power density

[kWm2]

ozone conc [wt][]CCβ

][0parameteradjustableα

iDiGi

Impact of Power Inductionp

350

400

wer

200

250

300

App

lied

Pow

Arr C 2Arr D +0

Arr E +45Arr F +7

Arr G +3

5 0

100

150

Frac

tion

of

1 2 3 4

ReferenceArr B unstable

Arr C -2

00

50

4Position (1inlet 4outlet)

Experimental Test Rigp g

Experimental Test Rigp g

Outer grounded electrode (left picture) and the dielectric covered inner electrodes (right) d e ect c cove ed e e ect odes ( g t)

Reference (Traditional) Arrangement

Inlet OutletGas flow direction

Optimized Arrangement

Inlet OutletGas flow direction

Intelligent Gap System (IGS)g p y ( )

Molecular Oxygen (O2) Ozone (O3)

O2 O3

yg ( 2) ( 3)

Particle Size SynthesisParticle Size SynthesisByBy--Products Cluster FormationProducts Cluster Formationyy

high diffusion and deposition to surfaces

low diffusion rate good transport

high sedimentation on the structurehigh sedimentation on the structure

Degreacutemont Technologies ndash OzoniaIntelligent Gap SystemIntelligent Gap System

G Vezzuacute JL Lopez A Freilich and K Becker Optimizationof Large-Scale Ozone Generators IEEE Transactions onPlasma Science Vol 37 No 6 p 890-896 (2009)

ConclusionsConclusionsConclusionsConclusionsFundamentals of ozone synthesis in a DBD plasmay p

ndash Highly filamented DBD discharges are best-suitedfor the production of ozone concentrations in therange of 6 to 14 wtrange of 6 to 14 wt

ndash The preferred characteristic of the microdischargesare Townsend-like at reduced electric fields Enaround 190 Townsend

ndash Detrimental side-effects induced by by-productscan be avoided by a proper design of the electrodecan be avoided by a proper design of the electrodearrangement The phenomenon is related to thediffusion rates of formed by-product clusters

ConclusionsConclusionsConclusionsConclusionsBenefits from DBD microplasma tailoring

ndash Reduced power consumption of up to 10 improvement

ndash Increased ozone concentrations of up to 14 now achievable

ndash Improved neutralization and conditioning of detrimental by-products

ndash Reduced system capital and operational cost

New technologies to improve ozone p

generatorg

HV Pulsed Power SwitchingHV Pulsed Power Switching

Microchannel Generation of Ozone

Channel ArrayChannel Array

Microchannel

330 microm 230 microm

Some Cap-DBD Devices Operating in Air

Increase of 60 of

Spacing 225 μmof 60 of plasma

No space

Cap‐DBD ozone generation

bull Ozone concentration is evaluated via Eco S d l UV 100 O A l (0 01Sensors model UV-100 Ozone Analyzer (001 ndash 900 ppm wiht an accuracy of plusmn2)

bull Three reactors 6 tubings 6rdquo with spacings of 0 μm 225 μm and 500 μm running at 3 kV μ μ μ g

SpacingOzone Concentration

3 kV rms 4 kV rms3 kV rms 4 kV rms

0 μm 660 ppm

225 μm 550 ppm

For a device of such small scale these ozone levels are promising

500 μm 380 ppm

J Mahoney W Zhu VS Johnson KH Becker and JL Lopez Electrical and optical emissionmeasurements of a capillary dielectric barrier discharge European Physics Journal D Vol 60 441-447(2010)

QuestionsQuestions

Thank YouFor more informationProf Jose L Lopez PhD

Thank YouFor more informationDepartment of Physics

Telephone (973) 761-9057Email joselopez1shuedu

Website wwwshueduacademicsartsciphysicsWebsite wwwshueduacademicsartsciphysics

Page 45: Dielectric Barrier Discharge (DBD) & Progress in Large ...bonitz/si12/talks/august_8/lopez_si12.pdf · Dielectric Barrier Discharge (DBD) & Progress in Large-Scale Ozone Generation

Generation of OzoneAdvantages of Enamel Dielectrics

Proven Patented Designbull Simplicity

Si l Di l i Cbull Single Dielectric Componentndash Reduced number of Dielectrics

bull Safety ndash Lower operating voltage

(lt 4000 V)bull Reliabilty

ndash Fused Dielectrics ensure continuous production

bull Lowest Power Consumption Operational Savingsndash Operational Savings

Modern Ozone GeneratorModern Ozone Generator

Ozonia Advanced Technology Ozone GeneratorOzone Generator

Generation of OzoneGeneration of Ozone

Generation of Ozone

Power Supply UnitPower Supply Unit

IGBT Inverter CircuitMain Circuit Breaker

HV 480 Volts60 Hz3 Phase Supply

C I

450KVAPow er to

GeneratorFILTER

CONVERTER INVERTERTRANSFORMER

C I450KVA Power Stage

CONTACTOR

bull Latest in Power Semiconductor Technology Modular Design

bull Utilizes IGBTrsquos (Insulated Gate Bi‐Polar Transistors) Converter and Inverter Components

Ozone Water Treatment

B bbl Diff iB bbl Diff iBubble DiffusionBubble Diffusion

Easy to use

Low energy usage Low energy usage

Mass transfer efficiencies to gt 90

Ozone Process Flow DiagramOzone Process Flow DiagramVent to

Atmosphere

O OOxygen

Off-Gas Blower

Ozone Destruct Unit

10 12

O3O2

LOX

10-12 O3

Ozone Generators

Ozone Contact ChamberLOX T k Generators Chamber

VaporizersLOX Tank

Municipal Ozone Installations

Ozonia Installations Ozone Plant Size [lbday] Start-Up DateKey Ozonia Installations (Partial List)

Los Angeles CA 10000 1986Fairfax VA ndash Corbalis 9000 2003MWD CA ndash Mills 9 000 2003

Ozonia Installations Ozone Plant Size [lbday] Start Up Date

MWD CA Mills 9000 2003Fairfax Co VA ndash Griffith 9000 2004MWD CA ndash Jensen 18750 2005Indianapolis IN ndash Belmont AWT 12000 2007I di li IN 12 000 2007Indianapolis IN ndash Southport AWT 12000 2007MWD CA ndash Diemer 13400 2008MWD CA ndash Weymouth 13400 2009

Ozonia North America - Potable Water SummaryTotal Number of Installations 90Total Installed Production gt 265000 lbsdayTotal Installed Production 265000 lbsday

Revision -B

Ozone Water TreatmentOzone Water Treatment

MWD Mills WTP - California

3 3 000 lbsda of o one3 3 000 lbsda of o one3 x 3000 lbsday of ozone3 x 3000 lbsday of ozone

Ozone Water TreatmentOzone Water TreatmentOzone Ozone -- How it worksHow it works

OxidantOxidant DisinfectantDisinfectant

bullbull Breaks double carbon Breaks double carbon bondsbonds

bullbull Kills by cell lysing or Kills by cell lysing or causing the cell wall tocausing the cell wall tobondsbonds

bullbull Creates OHCreates OHbullbull radicals radicals which break higher carbon which break higher carbon

causing the cell wall to causing the cell wall to rupture rupture

bullbull AttacksAttacks allall bacteriabacteriabondsbondsbullbull Increased temp and pH Increased temp and pH

accelerates Oaccelerates O33

Attacks Attacks allall bacteria bacteria virus cysts and spores virus cysts and spores in varying degreesin varying degreesaccelerates Oaccelerates O33

decomposition to OHdecomposition to OHbullbull

Micro-organism DNA

Capsule AdenineAdenine

Cell wall ThymineThymine

CytosineCytosine

GuanineGuanine

NuclearmaterialCellmembrane

material

Typical Bacterium DNA

Microbial Growth at Various Ozone ConcentrationsConcentrations

Growth likely

Growth possibleGrowth possible

NO GROWTH

0004 0008 0012 0016 0020

Ozone concentration (mgl)Ozone concentration (mgl)

Typical Water Treatment UsageTypical Water Treatment Usage

Application O3 mgl Contact timeUltra Pure Water 005 - 025 sec ndash min

Water bottling 04 ndash 10 5 ndash 10 min

Swimming pools ampspas

01 ndash 075 4 minutes

Potable taste amp odor 15 ndash 50 5 ndash 10 mindisinfection

Microfloculation 10 ndash 30 5 ndash 10 min

Lignin amp tammin 3 0 10 0 10 30 minLignin amp tamminremoval

30 ndash 100 10 ndash 30 min

Municipal wastewater 50 ndash 150+ 15 ndash 30 min

Ozone Water TreatmentOzone Water TreatmentOzone Ozone ndashndash Municipal ApplicationsMunicipal Applications

bullbull Taste and OdorTaste and Odor

bullbull Color RemovalColor Removal

bullbull Disinfection Without Trihalomethanes (THMs)Disinfection Without Trihalomethanes (THMs)

bullbull Improved Filtration Efficiency and FlocculationImproved Filtration Efficiency and Flocculation

bullbull Cryptosporidium DeactivationCryptosporidium Deactivation

bullbull Giardia amp Virus InactivationGiardia amp Virus Inactivation

bullbull Oxidation Oxidation -- Organics Fe amp MnOrganics Fe amp Mn

bullbull Wastewater disinfectionWastewater disinfection

bullbull BOD COD and TOC reductionBOD COD and TOC reduction

Applications of Ozone

Wastewater Treatmentbull Disinfection of Secondary and Tertiary Effluentsbull Color Reductionbull Color Reductionbull TOC Oxidation (Industrial)bull Oxidation of Odor Causing Compoundsbull Oxidation of Endocrine Disruptors (EDCrsquos) and p ( )

Pharmaceutically Active Compounds (PACrsquos)

Applications of Ozone

What are Endocrine Disruptors (EDCrsquos) and What are Endocrine Disruptors (EDCrsquos) and Ph ti ll A ti C d (PACrsquo )Ph ti ll A ti C d (PACrsquo )Pharmaceutically Active Compounds (PACrsquos)Pharmaceutically Active Compounds (PACrsquos)

bullbull EDCrsquosEDCrsquos andand PACrsquosPACrsquos areare NaturallyNaturally andand SyntheticSyntheticdd th tth t ff tff t thth b lb l llcompoundscompounds thatthat maymay affectaffect thethe balancebalance oror normalnormal

functionsfunctions inin animalsanimals andand humanshumans

What can EDCrsquos and PACrsquos doWhat can EDCrsquos and PACrsquos do

bullbull Even in very small concentrations these compounds Even in very small concentrations these compounds y py pcan can disruptdisrupt normal bodily functionsnormal bodily functions

bullbull ManMan--made chemicals can trick the bodies endocrine made chemicals can trick the bodies endocrine system system

Applications of Ozone

Examples of Endocrine Disruptors1000rsquos of compounds that may be Investigated as EDCs ndash Some examples are

bullbull Synthetic HormonesSynthetic Hormonesbullbull Naturally Occurring Estrogens Naturally Occurring Estrogens

Health and Beauty AidsHealth and Beauty Aidsbullbull Health and Beauty AidsHealth and Beauty Aidsbullbull SolventsSolventsbullbull PesticidesPesticidesbullbull SurfactantsSurfactantsbullbull PlasticsPlastics

F i idF i idbullbull FungicidesFungicides

Ozone Water TreatmentOzone Water Treatment

Ozone Ozone -- Industrial ApplicationsIndustrial Applications-- Ultrapure Water for Pharmaceutical ApplicationsUltrapure Water for Pharmaceutical Applications

-- Wastewater disinfection color removalWastewater disinfection color removal

-- Soil and Groundwater Remediation Soil and Groundwater Remediation

-- Cooling Tower Water TreatmentCooling Tower Water Treatment

-- Food ProcessingFood Processing

-- Aquaculture AquariumsAquaculture AquariumsAquaculture AquariumsAquaculture Aquariums

-- Beverage ApplicationsBeverage Applications

P l amp P Bl hiP l amp P Bl hi-- Pulp amp Paper BleachingPulp amp Paper Bleaching

High Purity OzonationHigh Purity Ozonation

Microchip manufacturingMicrochip manufacturing

What are the current issues in large-scale gozone generationg

Experimental Setup

Front view of the two units after the redesign and reworking ofthe gas water and instruments connectionsthe gas water and instruments connections

Experimental Setup

Top view of the twoexperimental unitsexperimental unitsSpectroscope (notshown) is to the left ofthe DBD The units weredifferent with respect todifferent with respect totheir electrodes onehad only the electrodecoated with thedielectric (ldquosingle-dielectric ( single-coatedrdquo) the other onehad the electrode andthe anode coated withthe dielectric (ldquodouble-the dielectric ( double-coatedrdquo)

Basics Generation of OzoneBasics Generation of Ozone

SpectroscopyPlasma

Plasma Absorption SpectroscopyPlasma Absorption Spectroscopy

Infrared Absorption SpectroscopyInfrared Absorption Spectroscopy

IR spectra in pure oxygen (black curve) and at approximately 10wt N2 admixture (red line) N2O5 peaks appear at124 1 d 1 2 11245 cm-1 and at 1725 cm-1

Infrared Absorption SpectroscopyInfrared Absorption Spectroscopy

IR spectra of several methane variations The green curve envelopes all of the methane peaks at 1325 cm-1recorded at smaller methane admixtures Simultaneously the N2O5 peaks disappear as the methane peaks appear

N2O5 FormationN2O5 Formation2 52 5p=2 bara cwt=20degC q=35kWm2 f=1450Hz

45N2O5 AT95

30

35

40

N

2 B

lend

ing

N2O AT95N2O5 IGSN2O IGSN2O5 LGN2O LG

1 5

20

25

nt [p

pmV]

3

wt

05

10

15

NO

x co

nten

005 7 9 11 13 15 17

ozone conc [wt]

Amount of formed N2O5 and N2O as a function of ozone concentration at 3 wt of nitrogen admixture and fori l dvarious electrode arrangements

Plasma Emission SpectroscopyPlasma Emission Spectroscopyp pyp py

Relative Emissions of the Ozonizer plasmaRelative Emissions of the Ozonizer plasma

Region 300- 850 nm from individual (calibrated) regions (smoothed by PeakFit) Single-coated ozone generator Inlet side

3 5E+06

30E+06

35E+06

7 9

20E+06

25E+06

nten

sity

au

2

311 12

10E+06

15E+06

In 4

5

6 8 10

14

15

16

17

00E+00

50E+05

280 300 320 340 360 380 400 420 440 460 480 500 520 540 560 580 600 620 640 660 680 700 720 740 760 780 800 820 840 860

Wavelength nm

1 13

Wavelength nm

Absolute Emission of the DBD PlasmaAbsolute Emission of the DBD Plasma

Intensities in (O2+3 wtN2) plasma

1 20E+04

100E+04

120E+04

600E+03

800E+03

nten

sity

(au

)

200E+03

400E+03

In

O(777)

000E+00200 250 300 350 400 450 500 550 600 650 700 750 800 850

Wavelength nm

Intensities in 3 wtN2+O2 plasmaIntensities in 3 wtN2+O2 plasma

Plasma Chemistry in OzonizersPlasma Chemistry in Ozonizers

Dry Air O2 N2

e - e -

O N2 N O2

O3 NO

O2 N O2

O3

N

3

NO2

O2 O3

NO

N

NO2 O3

N2O

NO3 N

N2O4

NO2

NO2

N2O5

NO3

Primary electron-driven chemical reactions leading to the formation of N2O5 and N2O in a dry air plasma

Plasma emission diagnostics role of N2Plasma emission diagnostics role of N2

Dry Air O2 N2

e - e -

O N2 N O2

O3 NO

O2 N O2

O3

O

N

ON

NO2

O2O3

N

NO N

NO2 O3

N2O

NO3 N

N2O4

NO2

NO2

N2O5

NO3

ONbullWith N2 present ndash less oxygen atoms are formed However the difference in intensity is

very small

Modeling of plasma chemistry incl the NxOy chemistry up to N2O5 for different Oxygen Nitrogen mixtures varying power deposition scenarios

and initial ozone background concentrations (up to 15) previously done

The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation

The role of N2 must be related to its by-products reacting on the surface of the electrodeThe role of N2 must be related to its by-products reacting on the surface of the electrode

The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established

Ab 8 t f O

The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established

Ab 8 t f OAbove 8 wt of O3

1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)

Above 8 wt of O3

1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)case without pampp)

2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of the

case without pampp)

2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of thethem A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface

them A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface

The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation

Three possibilities have to be considered for the oxygen-fedozone generator

Three possibilities have to be considered for the oxygen-fedozone generatorozone generator

bull Excited N2 molecules lead to an increased O2 dissociation in

ozone generator

bull Excited N2 molecules lead to an increased O2 dissociation in2 2such case an increased efficiency is correlated to the N2admixture

2 2such case an increased efficiency is correlated to the N2admixture

bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial

bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial

bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2

bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2g p g 3 pp y 2g p g 3 pp y 2

Effect of methane on ozone efficiency and specific powerEffect of methane on ozone efficiency and specific power

Effect of Methane on Ozone Content in Outlet Gas and on Specific Power Pure O2

13 12

10

11

12

t 8

10

8

9

10

ne c

onte

nt w

t

6

8

ecifi

c po

wer

kW

hlb

5

6

7

Ozo

n

2

4 Spe

400E+00 20E+03 40E+03 60E+03 80E+03 10E+04 12E+04

Methane in feedgas ppm

0

Ozone content in the outlet gas Specif ic pow er of the ozone generatorg p p g

Effects of N2 and CH4Effects of N2 and CH4

Pi t f h t lli N O t tPicture of an amorphous-crystalline N2O5 structurecaptured at the Orlando Skylake water plant in 2006

Plasma Chemistry with CH4 Impurities

OxygenO2 N2

e - e -

CHO N2

NO2

O NO

O2 N O2 O3

NOH

CH4e-

O3 NO

NO2

O2O3NO N

NO2 O

NO2

NO2

N2ONO3

N

O3

NO2

NO

HNO3

N2O4

N2O5

NO2

NO3

N2O5

Effect of methane on the electrode surfaces

a) b)

Inlet Outlet Outlet

) d)

I l t I l t

c) d)

Electrode of the ozone generator afterseveral hours in CH8O2 and up to 2 wt of methane (a b c)

Inlet Inlet

three hours in CH8O2+traces of N2 and up to 1 wt of methane (d) Visible change of discharge character at about 13 length of electrode (a d)

Kinetics of CHx Conversion without N2

conversion by collisions

O2 + CHx 12wt O3 + CO2 +H2O

deposition vaporizationby sputtering

ibl b l 1000 CHreversible process below 1000ppm CH4

Effect of water on electrode surface with N2

Inlet

OutletOutlet

Electrode of the ozone generator after several hours in H OO N

Inlet

Electrode of the ozone generator after several hours in H2OO2N2

Effect of water on electrode surface

Long term effect (800 hrs) of H2OO2N2

Kinetics of CHx Conversion with N2

conversion by collisionsHNO3 formation

O2 + N2 +CHx 12wtO2 + CO2 +H2O + HNO3

deposition vaporizationby sputtering

H2O + HNO3

by sputtering

irreversible process above a N2 threshold () ltlt 1000ppm N2

sticky deposit

p 2 ( ) pp 2 any CH4 concentration (60ppm)

Plasma Chemistry with CH4 ImpuritiesPlasma Chemistry with CH4 Impurities4

bull Formation of NO and NO2 depends on O3 N2 and gas temperature Conclusion N2 admixture is the key factor

SummarySummaryyyThe mechanisms of formed NOx by-products follows the sameThe mechanisms of formed NOx by-products follows the sameprinciples as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentration

principles as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentrationozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)

ozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)g p ( g p )

The conversion of methane to OH and H2O is found to depend on

g p ( g p )

The conversion of methane to OH and H2O is found to depend ondissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)

dissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)discharge gap)discharge gap)

How do you optimize an ozone generatorg

Scientific ApproachScientific ApproachTheoretical Experimental

pppp

c [wt]

f [Hz]

c [wt]

f [Hz]

[kW]UUUβ1

1Cf4αPn

1iiminpeakimin

iiD

q [kWm2]q [kWm2]

150

180

][V]voltagepeakUpeak

[]cylinder perslicesofamountnsliceii

whereth

09 00

30

60

90

120

effic

ienc

y [

][0tdj t bl[F]sliceisdielectricofecapacitancC

[Hz]frequencyf[V]sliceivoltageminimumiUmin

thiD

th

10

28

46

64

82

39

107

176

244 power density

[kWm2]

ozone conc [wt][]CCβ

][0parameteradjustableα

iDiGi

Impact of Power Inductionp

350

400

wer

200

250

300

App

lied

Pow

Arr C 2Arr D +0

Arr E +45Arr F +7

Arr G +3

5 0

100

150

Frac

tion

of

1 2 3 4

ReferenceArr B unstable

Arr C -2

00

50

4Position (1inlet 4outlet)

Experimental Test Rigp g

Experimental Test Rigp g

Outer grounded electrode (left picture) and the dielectric covered inner electrodes (right) d e ect c cove ed e e ect odes ( g t)

Reference (Traditional) Arrangement

Inlet OutletGas flow direction

Optimized Arrangement

Inlet OutletGas flow direction

Intelligent Gap System (IGS)g p y ( )

Molecular Oxygen (O2) Ozone (O3)

O2 O3

yg ( 2) ( 3)

Particle Size SynthesisParticle Size SynthesisByBy--Products Cluster FormationProducts Cluster Formationyy

high diffusion and deposition to surfaces

low diffusion rate good transport

high sedimentation on the structurehigh sedimentation on the structure

Degreacutemont Technologies ndash OzoniaIntelligent Gap SystemIntelligent Gap System

G Vezzuacute JL Lopez A Freilich and K Becker Optimizationof Large-Scale Ozone Generators IEEE Transactions onPlasma Science Vol 37 No 6 p 890-896 (2009)

ConclusionsConclusionsConclusionsConclusionsFundamentals of ozone synthesis in a DBD plasmay p

ndash Highly filamented DBD discharges are best-suitedfor the production of ozone concentrations in therange of 6 to 14 wtrange of 6 to 14 wt

ndash The preferred characteristic of the microdischargesare Townsend-like at reduced electric fields Enaround 190 Townsend

ndash Detrimental side-effects induced by by-productscan be avoided by a proper design of the electrodecan be avoided by a proper design of the electrodearrangement The phenomenon is related to thediffusion rates of formed by-product clusters

ConclusionsConclusionsConclusionsConclusionsBenefits from DBD microplasma tailoring

ndash Reduced power consumption of up to 10 improvement

ndash Increased ozone concentrations of up to 14 now achievable

ndash Improved neutralization and conditioning of detrimental by-products

ndash Reduced system capital and operational cost

New technologies to improve ozone p

generatorg

HV Pulsed Power SwitchingHV Pulsed Power Switching

Microchannel Generation of Ozone

Channel ArrayChannel Array

Microchannel

330 microm 230 microm

Some Cap-DBD Devices Operating in Air

Increase of 60 of

Spacing 225 μmof 60 of plasma

No space

Cap‐DBD ozone generation

bull Ozone concentration is evaluated via Eco S d l UV 100 O A l (0 01Sensors model UV-100 Ozone Analyzer (001 ndash 900 ppm wiht an accuracy of plusmn2)

bull Three reactors 6 tubings 6rdquo with spacings of 0 μm 225 μm and 500 μm running at 3 kV μ μ μ g

SpacingOzone Concentration

3 kV rms 4 kV rms3 kV rms 4 kV rms

0 μm 660 ppm

225 μm 550 ppm

For a device of such small scale these ozone levels are promising

500 μm 380 ppm

J Mahoney W Zhu VS Johnson KH Becker and JL Lopez Electrical and optical emissionmeasurements of a capillary dielectric barrier discharge European Physics Journal D Vol 60 441-447(2010)

QuestionsQuestions

Thank YouFor more informationProf Jose L Lopez PhD

Thank YouFor more informationDepartment of Physics

Telephone (973) 761-9057Email joselopez1shuedu

Website wwwshueduacademicsartsciphysicsWebsite wwwshueduacademicsartsciphysics

Page 46: Dielectric Barrier Discharge (DBD) & Progress in Large ...bonitz/si12/talks/august_8/lopez_si12.pdf · Dielectric Barrier Discharge (DBD) & Progress in Large-Scale Ozone Generation

Modern Ozone GeneratorModern Ozone Generator

Ozonia Advanced Technology Ozone GeneratorOzone Generator

Generation of OzoneGeneration of Ozone

Generation of Ozone

Power Supply UnitPower Supply Unit

IGBT Inverter CircuitMain Circuit Breaker

HV 480 Volts60 Hz3 Phase Supply

C I

450KVAPow er to

GeneratorFILTER

CONVERTER INVERTERTRANSFORMER

C I450KVA Power Stage

CONTACTOR

bull Latest in Power Semiconductor Technology Modular Design

bull Utilizes IGBTrsquos (Insulated Gate Bi‐Polar Transistors) Converter and Inverter Components

Ozone Water Treatment

B bbl Diff iB bbl Diff iBubble DiffusionBubble Diffusion

Easy to use

Low energy usage Low energy usage

Mass transfer efficiencies to gt 90

Ozone Process Flow DiagramOzone Process Flow DiagramVent to

Atmosphere

O OOxygen

Off-Gas Blower

Ozone Destruct Unit

10 12

O3O2

LOX

10-12 O3

Ozone Generators

Ozone Contact ChamberLOX T k Generators Chamber

VaporizersLOX Tank

Municipal Ozone Installations

Ozonia Installations Ozone Plant Size [lbday] Start-Up DateKey Ozonia Installations (Partial List)

Los Angeles CA 10000 1986Fairfax VA ndash Corbalis 9000 2003MWD CA ndash Mills 9 000 2003

Ozonia Installations Ozone Plant Size [lbday] Start Up Date

MWD CA Mills 9000 2003Fairfax Co VA ndash Griffith 9000 2004MWD CA ndash Jensen 18750 2005Indianapolis IN ndash Belmont AWT 12000 2007I di li IN 12 000 2007Indianapolis IN ndash Southport AWT 12000 2007MWD CA ndash Diemer 13400 2008MWD CA ndash Weymouth 13400 2009

Ozonia North America - Potable Water SummaryTotal Number of Installations 90Total Installed Production gt 265000 lbsdayTotal Installed Production 265000 lbsday

Revision -B

Ozone Water TreatmentOzone Water Treatment

MWD Mills WTP - California

3 3 000 lbsda of o one3 3 000 lbsda of o one3 x 3000 lbsday of ozone3 x 3000 lbsday of ozone

Ozone Water TreatmentOzone Water TreatmentOzone Ozone -- How it worksHow it works

OxidantOxidant DisinfectantDisinfectant

bullbull Breaks double carbon Breaks double carbon bondsbonds

bullbull Kills by cell lysing or Kills by cell lysing or causing the cell wall tocausing the cell wall tobondsbonds

bullbull Creates OHCreates OHbullbull radicals radicals which break higher carbon which break higher carbon

causing the cell wall to causing the cell wall to rupture rupture

bullbull AttacksAttacks allall bacteriabacteriabondsbondsbullbull Increased temp and pH Increased temp and pH

accelerates Oaccelerates O33

Attacks Attacks allall bacteria bacteria virus cysts and spores virus cysts and spores in varying degreesin varying degreesaccelerates Oaccelerates O33

decomposition to OHdecomposition to OHbullbull

Micro-organism DNA

Capsule AdenineAdenine

Cell wall ThymineThymine

CytosineCytosine

GuanineGuanine

NuclearmaterialCellmembrane

material

Typical Bacterium DNA

Microbial Growth at Various Ozone ConcentrationsConcentrations

Growth likely

Growth possibleGrowth possible

NO GROWTH

0004 0008 0012 0016 0020

Ozone concentration (mgl)Ozone concentration (mgl)

Typical Water Treatment UsageTypical Water Treatment Usage

Application O3 mgl Contact timeUltra Pure Water 005 - 025 sec ndash min

Water bottling 04 ndash 10 5 ndash 10 min

Swimming pools ampspas

01 ndash 075 4 minutes

Potable taste amp odor 15 ndash 50 5 ndash 10 mindisinfection

Microfloculation 10 ndash 30 5 ndash 10 min

Lignin amp tammin 3 0 10 0 10 30 minLignin amp tamminremoval

30 ndash 100 10 ndash 30 min

Municipal wastewater 50 ndash 150+ 15 ndash 30 min

Ozone Water TreatmentOzone Water TreatmentOzone Ozone ndashndash Municipal ApplicationsMunicipal Applications

bullbull Taste and OdorTaste and Odor

bullbull Color RemovalColor Removal

bullbull Disinfection Without Trihalomethanes (THMs)Disinfection Without Trihalomethanes (THMs)

bullbull Improved Filtration Efficiency and FlocculationImproved Filtration Efficiency and Flocculation

bullbull Cryptosporidium DeactivationCryptosporidium Deactivation

bullbull Giardia amp Virus InactivationGiardia amp Virus Inactivation

bullbull Oxidation Oxidation -- Organics Fe amp MnOrganics Fe amp Mn

bullbull Wastewater disinfectionWastewater disinfection

bullbull BOD COD and TOC reductionBOD COD and TOC reduction

Applications of Ozone

Wastewater Treatmentbull Disinfection of Secondary and Tertiary Effluentsbull Color Reductionbull Color Reductionbull TOC Oxidation (Industrial)bull Oxidation of Odor Causing Compoundsbull Oxidation of Endocrine Disruptors (EDCrsquos) and p ( )

Pharmaceutically Active Compounds (PACrsquos)

Applications of Ozone

What are Endocrine Disruptors (EDCrsquos) and What are Endocrine Disruptors (EDCrsquos) and Ph ti ll A ti C d (PACrsquo )Ph ti ll A ti C d (PACrsquo )Pharmaceutically Active Compounds (PACrsquos)Pharmaceutically Active Compounds (PACrsquos)

bullbull EDCrsquosEDCrsquos andand PACrsquosPACrsquos areare NaturallyNaturally andand SyntheticSyntheticdd th tth t ff tff t thth b lb l llcompoundscompounds thatthat maymay affectaffect thethe balancebalance oror normalnormal

functionsfunctions inin animalsanimals andand humanshumans

What can EDCrsquos and PACrsquos doWhat can EDCrsquos and PACrsquos do

bullbull Even in very small concentrations these compounds Even in very small concentrations these compounds y py pcan can disruptdisrupt normal bodily functionsnormal bodily functions

bullbull ManMan--made chemicals can trick the bodies endocrine made chemicals can trick the bodies endocrine system system

Applications of Ozone

Examples of Endocrine Disruptors1000rsquos of compounds that may be Investigated as EDCs ndash Some examples are

bullbull Synthetic HormonesSynthetic Hormonesbullbull Naturally Occurring Estrogens Naturally Occurring Estrogens

Health and Beauty AidsHealth and Beauty Aidsbullbull Health and Beauty AidsHealth and Beauty Aidsbullbull SolventsSolventsbullbull PesticidesPesticidesbullbull SurfactantsSurfactantsbullbull PlasticsPlastics

F i idF i idbullbull FungicidesFungicides

Ozone Water TreatmentOzone Water Treatment

Ozone Ozone -- Industrial ApplicationsIndustrial Applications-- Ultrapure Water for Pharmaceutical ApplicationsUltrapure Water for Pharmaceutical Applications

-- Wastewater disinfection color removalWastewater disinfection color removal

-- Soil and Groundwater Remediation Soil and Groundwater Remediation

-- Cooling Tower Water TreatmentCooling Tower Water Treatment

-- Food ProcessingFood Processing

-- Aquaculture AquariumsAquaculture AquariumsAquaculture AquariumsAquaculture Aquariums

-- Beverage ApplicationsBeverage Applications

P l amp P Bl hiP l amp P Bl hi-- Pulp amp Paper BleachingPulp amp Paper Bleaching

High Purity OzonationHigh Purity Ozonation

Microchip manufacturingMicrochip manufacturing

What are the current issues in large-scale gozone generationg

Experimental Setup

Front view of the two units after the redesign and reworking ofthe gas water and instruments connectionsthe gas water and instruments connections

Experimental Setup

Top view of the twoexperimental unitsexperimental unitsSpectroscope (notshown) is to the left ofthe DBD The units weredifferent with respect todifferent with respect totheir electrodes onehad only the electrodecoated with thedielectric (ldquosingle-dielectric ( single-coatedrdquo) the other onehad the electrode andthe anode coated withthe dielectric (ldquodouble-the dielectric ( double-coatedrdquo)

Basics Generation of OzoneBasics Generation of Ozone

SpectroscopyPlasma

Plasma Absorption SpectroscopyPlasma Absorption Spectroscopy

Infrared Absorption SpectroscopyInfrared Absorption Spectroscopy

IR spectra in pure oxygen (black curve) and at approximately 10wt N2 admixture (red line) N2O5 peaks appear at124 1 d 1 2 11245 cm-1 and at 1725 cm-1

Infrared Absorption SpectroscopyInfrared Absorption Spectroscopy

IR spectra of several methane variations The green curve envelopes all of the methane peaks at 1325 cm-1recorded at smaller methane admixtures Simultaneously the N2O5 peaks disappear as the methane peaks appear

N2O5 FormationN2O5 Formation2 52 5p=2 bara cwt=20degC q=35kWm2 f=1450Hz

45N2O5 AT95

30

35

40

N

2 B

lend

ing

N2O AT95N2O5 IGSN2O IGSN2O5 LGN2O LG

1 5

20

25

nt [p

pmV]

3

wt

05

10

15

NO

x co

nten

005 7 9 11 13 15 17

ozone conc [wt]

Amount of formed N2O5 and N2O as a function of ozone concentration at 3 wt of nitrogen admixture and fori l dvarious electrode arrangements

Plasma Emission SpectroscopyPlasma Emission Spectroscopyp pyp py

Relative Emissions of the Ozonizer plasmaRelative Emissions of the Ozonizer plasma

Region 300- 850 nm from individual (calibrated) regions (smoothed by PeakFit) Single-coated ozone generator Inlet side

3 5E+06

30E+06

35E+06

7 9

20E+06

25E+06

nten

sity

au

2

311 12

10E+06

15E+06

In 4

5

6 8 10

14

15

16

17

00E+00

50E+05

280 300 320 340 360 380 400 420 440 460 480 500 520 540 560 580 600 620 640 660 680 700 720 740 760 780 800 820 840 860

Wavelength nm

1 13

Wavelength nm

Absolute Emission of the DBD PlasmaAbsolute Emission of the DBD Plasma

Intensities in (O2+3 wtN2) plasma

1 20E+04

100E+04

120E+04

600E+03

800E+03

nten

sity

(au

)

200E+03

400E+03

In

O(777)

000E+00200 250 300 350 400 450 500 550 600 650 700 750 800 850

Wavelength nm

Intensities in 3 wtN2+O2 plasmaIntensities in 3 wtN2+O2 plasma

Plasma Chemistry in OzonizersPlasma Chemistry in Ozonizers

Dry Air O2 N2

e - e -

O N2 N O2

O3 NO

O2 N O2

O3

N

3

NO2

O2 O3

NO

N

NO2 O3

N2O

NO3 N

N2O4

NO2

NO2

N2O5

NO3

Primary electron-driven chemical reactions leading to the formation of N2O5 and N2O in a dry air plasma

Plasma emission diagnostics role of N2Plasma emission diagnostics role of N2

Dry Air O2 N2

e - e -

O N2 N O2

O3 NO

O2 N O2

O3

O

N

ON

NO2

O2O3

N

NO N

NO2 O3

N2O

NO3 N

N2O4

NO2

NO2

N2O5

NO3

ONbullWith N2 present ndash less oxygen atoms are formed However the difference in intensity is

very small

Modeling of plasma chemistry incl the NxOy chemistry up to N2O5 for different Oxygen Nitrogen mixtures varying power deposition scenarios

and initial ozone background concentrations (up to 15) previously done

The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation

The role of N2 must be related to its by-products reacting on the surface of the electrodeThe role of N2 must be related to its by-products reacting on the surface of the electrode

The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established

Ab 8 t f O

The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established

Ab 8 t f OAbove 8 wt of O3

1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)

Above 8 wt of O3

1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)case without pampp)

2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of the

case without pampp)

2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of thethem A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface

them A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface

The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation

Three possibilities have to be considered for the oxygen-fedozone generator

Three possibilities have to be considered for the oxygen-fedozone generatorozone generator

bull Excited N2 molecules lead to an increased O2 dissociation in

ozone generator

bull Excited N2 molecules lead to an increased O2 dissociation in2 2such case an increased efficiency is correlated to the N2admixture

2 2such case an increased efficiency is correlated to the N2admixture

bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial

bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial

bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2

bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2g p g 3 pp y 2g p g 3 pp y 2

Effect of methane on ozone efficiency and specific powerEffect of methane on ozone efficiency and specific power

Effect of Methane on Ozone Content in Outlet Gas and on Specific Power Pure O2

13 12

10

11

12

t 8

10

8

9

10

ne c

onte

nt w

t

6

8

ecifi

c po

wer

kW

hlb

5

6

7

Ozo

n

2

4 Spe

400E+00 20E+03 40E+03 60E+03 80E+03 10E+04 12E+04

Methane in feedgas ppm

0

Ozone content in the outlet gas Specif ic pow er of the ozone generatorg p p g

Effects of N2 and CH4Effects of N2 and CH4

Pi t f h t lli N O t tPicture of an amorphous-crystalline N2O5 structurecaptured at the Orlando Skylake water plant in 2006

Plasma Chemistry with CH4 Impurities

OxygenO2 N2

e - e -

CHO N2

NO2

O NO

O2 N O2 O3

NOH

CH4e-

O3 NO

NO2

O2O3NO N

NO2 O

NO2

NO2

N2ONO3

N

O3

NO2

NO

HNO3

N2O4

N2O5

NO2

NO3

N2O5

Effect of methane on the electrode surfaces

a) b)

Inlet Outlet Outlet

) d)

I l t I l t

c) d)

Electrode of the ozone generator afterseveral hours in CH8O2 and up to 2 wt of methane (a b c)

Inlet Inlet

three hours in CH8O2+traces of N2 and up to 1 wt of methane (d) Visible change of discharge character at about 13 length of electrode (a d)

Kinetics of CHx Conversion without N2

conversion by collisions

O2 + CHx 12wt O3 + CO2 +H2O

deposition vaporizationby sputtering

ibl b l 1000 CHreversible process below 1000ppm CH4

Effect of water on electrode surface with N2

Inlet

OutletOutlet

Electrode of the ozone generator after several hours in H OO N

Inlet

Electrode of the ozone generator after several hours in H2OO2N2

Effect of water on electrode surface

Long term effect (800 hrs) of H2OO2N2

Kinetics of CHx Conversion with N2

conversion by collisionsHNO3 formation

O2 + N2 +CHx 12wtO2 + CO2 +H2O + HNO3

deposition vaporizationby sputtering

H2O + HNO3

by sputtering

irreversible process above a N2 threshold () ltlt 1000ppm N2

sticky deposit

p 2 ( ) pp 2 any CH4 concentration (60ppm)

Plasma Chemistry with CH4 ImpuritiesPlasma Chemistry with CH4 Impurities4

bull Formation of NO and NO2 depends on O3 N2 and gas temperature Conclusion N2 admixture is the key factor

SummarySummaryyyThe mechanisms of formed NOx by-products follows the sameThe mechanisms of formed NOx by-products follows the sameprinciples as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentration

principles as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentrationozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)

ozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)g p ( g p )

The conversion of methane to OH and H2O is found to depend on

g p ( g p )

The conversion of methane to OH and H2O is found to depend ondissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)

dissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)discharge gap)discharge gap)

How do you optimize an ozone generatorg

Scientific ApproachScientific ApproachTheoretical Experimental

pppp

c [wt]

f [Hz]

c [wt]

f [Hz]

[kW]UUUβ1

1Cf4αPn

1iiminpeakimin

iiD

q [kWm2]q [kWm2]

150

180

][V]voltagepeakUpeak

[]cylinder perslicesofamountnsliceii

whereth

09 00

30

60

90

120

effic

ienc

y [

][0tdj t bl[F]sliceisdielectricofecapacitancC

[Hz]frequencyf[V]sliceivoltageminimumiUmin

thiD

th

10

28

46

64

82

39

107

176

244 power density

[kWm2]

ozone conc [wt][]CCβ

][0parameteradjustableα

iDiGi

Impact of Power Inductionp

350

400

wer

200

250

300

App

lied

Pow

Arr C 2Arr D +0

Arr E +45Arr F +7

Arr G +3

5 0

100

150

Frac

tion

of

1 2 3 4

ReferenceArr B unstable

Arr C -2

00

50

4Position (1inlet 4outlet)

Experimental Test Rigp g

Experimental Test Rigp g

Outer grounded electrode (left picture) and the dielectric covered inner electrodes (right) d e ect c cove ed e e ect odes ( g t)

Reference (Traditional) Arrangement

Inlet OutletGas flow direction

Optimized Arrangement

Inlet OutletGas flow direction

Intelligent Gap System (IGS)g p y ( )

Molecular Oxygen (O2) Ozone (O3)

O2 O3

yg ( 2) ( 3)

Particle Size SynthesisParticle Size SynthesisByBy--Products Cluster FormationProducts Cluster Formationyy

high diffusion and deposition to surfaces

low diffusion rate good transport

high sedimentation on the structurehigh sedimentation on the structure

Degreacutemont Technologies ndash OzoniaIntelligent Gap SystemIntelligent Gap System

G Vezzuacute JL Lopez A Freilich and K Becker Optimizationof Large-Scale Ozone Generators IEEE Transactions onPlasma Science Vol 37 No 6 p 890-896 (2009)

ConclusionsConclusionsConclusionsConclusionsFundamentals of ozone synthesis in a DBD plasmay p

ndash Highly filamented DBD discharges are best-suitedfor the production of ozone concentrations in therange of 6 to 14 wtrange of 6 to 14 wt

ndash The preferred characteristic of the microdischargesare Townsend-like at reduced electric fields Enaround 190 Townsend

ndash Detrimental side-effects induced by by-productscan be avoided by a proper design of the electrodecan be avoided by a proper design of the electrodearrangement The phenomenon is related to thediffusion rates of formed by-product clusters

ConclusionsConclusionsConclusionsConclusionsBenefits from DBD microplasma tailoring

ndash Reduced power consumption of up to 10 improvement

ndash Increased ozone concentrations of up to 14 now achievable

ndash Improved neutralization and conditioning of detrimental by-products

ndash Reduced system capital and operational cost

New technologies to improve ozone p

generatorg

HV Pulsed Power SwitchingHV Pulsed Power Switching

Microchannel Generation of Ozone

Channel ArrayChannel Array

Microchannel

330 microm 230 microm

Some Cap-DBD Devices Operating in Air

Increase of 60 of

Spacing 225 μmof 60 of plasma

No space

Cap‐DBD ozone generation

bull Ozone concentration is evaluated via Eco S d l UV 100 O A l (0 01Sensors model UV-100 Ozone Analyzer (001 ndash 900 ppm wiht an accuracy of plusmn2)

bull Three reactors 6 tubings 6rdquo with spacings of 0 μm 225 μm and 500 μm running at 3 kV μ μ μ g

SpacingOzone Concentration

3 kV rms 4 kV rms3 kV rms 4 kV rms

0 μm 660 ppm

225 μm 550 ppm

For a device of such small scale these ozone levels are promising

500 μm 380 ppm

J Mahoney W Zhu VS Johnson KH Becker and JL Lopez Electrical and optical emissionmeasurements of a capillary dielectric barrier discharge European Physics Journal D Vol 60 441-447(2010)

QuestionsQuestions

Thank YouFor more informationProf Jose L Lopez PhD

Thank YouFor more informationDepartment of Physics

Telephone (973) 761-9057Email joselopez1shuedu

Website wwwshueduacademicsartsciphysicsWebsite wwwshueduacademicsartsciphysics

Page 47: Dielectric Barrier Discharge (DBD) & Progress in Large ...bonitz/si12/talks/august_8/lopez_si12.pdf · Dielectric Barrier Discharge (DBD) & Progress in Large-Scale Ozone Generation

Ozonia Advanced Technology Ozone GeneratorOzone Generator

Generation of OzoneGeneration of Ozone

Generation of Ozone

Power Supply UnitPower Supply Unit

IGBT Inverter CircuitMain Circuit Breaker

HV 480 Volts60 Hz3 Phase Supply

C I

450KVAPow er to

GeneratorFILTER

CONVERTER INVERTERTRANSFORMER

C I450KVA Power Stage

CONTACTOR

bull Latest in Power Semiconductor Technology Modular Design

bull Utilizes IGBTrsquos (Insulated Gate Bi‐Polar Transistors) Converter and Inverter Components

Ozone Water Treatment

B bbl Diff iB bbl Diff iBubble DiffusionBubble Diffusion

Easy to use

Low energy usage Low energy usage

Mass transfer efficiencies to gt 90

Ozone Process Flow DiagramOzone Process Flow DiagramVent to

Atmosphere

O OOxygen

Off-Gas Blower

Ozone Destruct Unit

10 12

O3O2

LOX

10-12 O3

Ozone Generators

Ozone Contact ChamberLOX T k Generators Chamber

VaporizersLOX Tank

Municipal Ozone Installations

Ozonia Installations Ozone Plant Size [lbday] Start-Up DateKey Ozonia Installations (Partial List)

Los Angeles CA 10000 1986Fairfax VA ndash Corbalis 9000 2003MWD CA ndash Mills 9 000 2003

Ozonia Installations Ozone Plant Size [lbday] Start Up Date

MWD CA Mills 9000 2003Fairfax Co VA ndash Griffith 9000 2004MWD CA ndash Jensen 18750 2005Indianapolis IN ndash Belmont AWT 12000 2007I di li IN 12 000 2007Indianapolis IN ndash Southport AWT 12000 2007MWD CA ndash Diemer 13400 2008MWD CA ndash Weymouth 13400 2009

Ozonia North America - Potable Water SummaryTotal Number of Installations 90Total Installed Production gt 265000 lbsdayTotal Installed Production 265000 lbsday

Revision -B

Ozone Water TreatmentOzone Water Treatment

MWD Mills WTP - California

3 3 000 lbsda of o one3 3 000 lbsda of o one3 x 3000 lbsday of ozone3 x 3000 lbsday of ozone

Ozone Water TreatmentOzone Water TreatmentOzone Ozone -- How it worksHow it works

OxidantOxidant DisinfectantDisinfectant

bullbull Breaks double carbon Breaks double carbon bondsbonds

bullbull Kills by cell lysing or Kills by cell lysing or causing the cell wall tocausing the cell wall tobondsbonds

bullbull Creates OHCreates OHbullbull radicals radicals which break higher carbon which break higher carbon

causing the cell wall to causing the cell wall to rupture rupture

bullbull AttacksAttacks allall bacteriabacteriabondsbondsbullbull Increased temp and pH Increased temp and pH

accelerates Oaccelerates O33

Attacks Attacks allall bacteria bacteria virus cysts and spores virus cysts and spores in varying degreesin varying degreesaccelerates Oaccelerates O33

decomposition to OHdecomposition to OHbullbull

Micro-organism DNA

Capsule AdenineAdenine

Cell wall ThymineThymine

CytosineCytosine

GuanineGuanine

NuclearmaterialCellmembrane

material

Typical Bacterium DNA

Microbial Growth at Various Ozone ConcentrationsConcentrations

Growth likely

Growth possibleGrowth possible

NO GROWTH

0004 0008 0012 0016 0020

Ozone concentration (mgl)Ozone concentration (mgl)

Typical Water Treatment UsageTypical Water Treatment Usage

Application O3 mgl Contact timeUltra Pure Water 005 - 025 sec ndash min

Water bottling 04 ndash 10 5 ndash 10 min

Swimming pools ampspas

01 ndash 075 4 minutes

Potable taste amp odor 15 ndash 50 5 ndash 10 mindisinfection

Microfloculation 10 ndash 30 5 ndash 10 min

Lignin amp tammin 3 0 10 0 10 30 minLignin amp tamminremoval

30 ndash 100 10 ndash 30 min

Municipal wastewater 50 ndash 150+ 15 ndash 30 min

Ozone Water TreatmentOzone Water TreatmentOzone Ozone ndashndash Municipal ApplicationsMunicipal Applications

bullbull Taste and OdorTaste and Odor

bullbull Color RemovalColor Removal

bullbull Disinfection Without Trihalomethanes (THMs)Disinfection Without Trihalomethanes (THMs)

bullbull Improved Filtration Efficiency and FlocculationImproved Filtration Efficiency and Flocculation

bullbull Cryptosporidium DeactivationCryptosporidium Deactivation

bullbull Giardia amp Virus InactivationGiardia amp Virus Inactivation

bullbull Oxidation Oxidation -- Organics Fe amp MnOrganics Fe amp Mn

bullbull Wastewater disinfectionWastewater disinfection

bullbull BOD COD and TOC reductionBOD COD and TOC reduction

Applications of Ozone

Wastewater Treatmentbull Disinfection of Secondary and Tertiary Effluentsbull Color Reductionbull Color Reductionbull TOC Oxidation (Industrial)bull Oxidation of Odor Causing Compoundsbull Oxidation of Endocrine Disruptors (EDCrsquos) and p ( )

Pharmaceutically Active Compounds (PACrsquos)

Applications of Ozone

What are Endocrine Disruptors (EDCrsquos) and What are Endocrine Disruptors (EDCrsquos) and Ph ti ll A ti C d (PACrsquo )Ph ti ll A ti C d (PACrsquo )Pharmaceutically Active Compounds (PACrsquos)Pharmaceutically Active Compounds (PACrsquos)

bullbull EDCrsquosEDCrsquos andand PACrsquosPACrsquos areare NaturallyNaturally andand SyntheticSyntheticdd th tth t ff tff t thth b lb l llcompoundscompounds thatthat maymay affectaffect thethe balancebalance oror normalnormal

functionsfunctions inin animalsanimals andand humanshumans

What can EDCrsquos and PACrsquos doWhat can EDCrsquos and PACrsquos do

bullbull Even in very small concentrations these compounds Even in very small concentrations these compounds y py pcan can disruptdisrupt normal bodily functionsnormal bodily functions

bullbull ManMan--made chemicals can trick the bodies endocrine made chemicals can trick the bodies endocrine system system

Applications of Ozone

Examples of Endocrine Disruptors1000rsquos of compounds that may be Investigated as EDCs ndash Some examples are

bullbull Synthetic HormonesSynthetic Hormonesbullbull Naturally Occurring Estrogens Naturally Occurring Estrogens

Health and Beauty AidsHealth and Beauty Aidsbullbull Health and Beauty AidsHealth and Beauty Aidsbullbull SolventsSolventsbullbull PesticidesPesticidesbullbull SurfactantsSurfactantsbullbull PlasticsPlastics

F i idF i idbullbull FungicidesFungicides

Ozone Water TreatmentOzone Water Treatment

Ozone Ozone -- Industrial ApplicationsIndustrial Applications-- Ultrapure Water for Pharmaceutical ApplicationsUltrapure Water for Pharmaceutical Applications

-- Wastewater disinfection color removalWastewater disinfection color removal

-- Soil and Groundwater Remediation Soil and Groundwater Remediation

-- Cooling Tower Water TreatmentCooling Tower Water Treatment

-- Food ProcessingFood Processing

-- Aquaculture AquariumsAquaculture AquariumsAquaculture AquariumsAquaculture Aquariums

-- Beverage ApplicationsBeverage Applications

P l amp P Bl hiP l amp P Bl hi-- Pulp amp Paper BleachingPulp amp Paper Bleaching

High Purity OzonationHigh Purity Ozonation

Microchip manufacturingMicrochip manufacturing

What are the current issues in large-scale gozone generationg

Experimental Setup

Front view of the two units after the redesign and reworking ofthe gas water and instruments connectionsthe gas water and instruments connections

Experimental Setup

Top view of the twoexperimental unitsexperimental unitsSpectroscope (notshown) is to the left ofthe DBD The units weredifferent with respect todifferent with respect totheir electrodes onehad only the electrodecoated with thedielectric (ldquosingle-dielectric ( single-coatedrdquo) the other onehad the electrode andthe anode coated withthe dielectric (ldquodouble-the dielectric ( double-coatedrdquo)

Basics Generation of OzoneBasics Generation of Ozone

SpectroscopyPlasma

Plasma Absorption SpectroscopyPlasma Absorption Spectroscopy

Infrared Absorption SpectroscopyInfrared Absorption Spectroscopy

IR spectra in pure oxygen (black curve) and at approximately 10wt N2 admixture (red line) N2O5 peaks appear at124 1 d 1 2 11245 cm-1 and at 1725 cm-1

Infrared Absorption SpectroscopyInfrared Absorption Spectroscopy

IR spectra of several methane variations The green curve envelopes all of the methane peaks at 1325 cm-1recorded at smaller methane admixtures Simultaneously the N2O5 peaks disappear as the methane peaks appear

N2O5 FormationN2O5 Formation2 52 5p=2 bara cwt=20degC q=35kWm2 f=1450Hz

45N2O5 AT95

30

35

40

N

2 B

lend

ing

N2O AT95N2O5 IGSN2O IGSN2O5 LGN2O LG

1 5

20

25

nt [p

pmV]

3

wt

05

10

15

NO

x co

nten

005 7 9 11 13 15 17

ozone conc [wt]

Amount of formed N2O5 and N2O as a function of ozone concentration at 3 wt of nitrogen admixture and fori l dvarious electrode arrangements

Plasma Emission SpectroscopyPlasma Emission Spectroscopyp pyp py

Relative Emissions of the Ozonizer plasmaRelative Emissions of the Ozonizer plasma

Region 300- 850 nm from individual (calibrated) regions (smoothed by PeakFit) Single-coated ozone generator Inlet side

3 5E+06

30E+06

35E+06

7 9

20E+06

25E+06

nten

sity

au

2

311 12

10E+06

15E+06

In 4

5

6 8 10

14

15

16

17

00E+00

50E+05

280 300 320 340 360 380 400 420 440 460 480 500 520 540 560 580 600 620 640 660 680 700 720 740 760 780 800 820 840 860

Wavelength nm

1 13

Wavelength nm

Absolute Emission of the DBD PlasmaAbsolute Emission of the DBD Plasma

Intensities in (O2+3 wtN2) plasma

1 20E+04

100E+04

120E+04

600E+03

800E+03

nten

sity

(au

)

200E+03

400E+03

In

O(777)

000E+00200 250 300 350 400 450 500 550 600 650 700 750 800 850

Wavelength nm

Intensities in 3 wtN2+O2 plasmaIntensities in 3 wtN2+O2 plasma

Plasma Chemistry in OzonizersPlasma Chemistry in Ozonizers

Dry Air O2 N2

e - e -

O N2 N O2

O3 NO

O2 N O2

O3

N

3

NO2

O2 O3

NO

N

NO2 O3

N2O

NO3 N

N2O4

NO2

NO2

N2O5

NO3

Primary electron-driven chemical reactions leading to the formation of N2O5 and N2O in a dry air plasma

Plasma emission diagnostics role of N2Plasma emission diagnostics role of N2

Dry Air O2 N2

e - e -

O N2 N O2

O3 NO

O2 N O2

O3

O

N

ON

NO2

O2O3

N

NO N

NO2 O3

N2O

NO3 N

N2O4

NO2

NO2

N2O5

NO3

ONbullWith N2 present ndash less oxygen atoms are formed However the difference in intensity is

very small

Modeling of plasma chemistry incl the NxOy chemistry up to N2O5 for different Oxygen Nitrogen mixtures varying power deposition scenarios

and initial ozone background concentrations (up to 15) previously done

The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation

The role of N2 must be related to its by-products reacting on the surface of the electrodeThe role of N2 must be related to its by-products reacting on the surface of the electrode

The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established

Ab 8 t f O

The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established

Ab 8 t f OAbove 8 wt of O3

1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)

Above 8 wt of O3

1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)case without pampp)

2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of the

case without pampp)

2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of thethem A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface

them A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface

The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation

Three possibilities have to be considered for the oxygen-fedozone generator

Three possibilities have to be considered for the oxygen-fedozone generatorozone generator

bull Excited N2 molecules lead to an increased O2 dissociation in

ozone generator

bull Excited N2 molecules lead to an increased O2 dissociation in2 2such case an increased efficiency is correlated to the N2admixture

2 2such case an increased efficiency is correlated to the N2admixture

bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial

bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial

bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2

bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2g p g 3 pp y 2g p g 3 pp y 2

Effect of methane on ozone efficiency and specific powerEffect of methane on ozone efficiency and specific power

Effect of Methane on Ozone Content in Outlet Gas and on Specific Power Pure O2

13 12

10

11

12

t 8

10

8

9

10

ne c

onte

nt w

t

6

8

ecifi

c po

wer

kW

hlb

5

6

7

Ozo

n

2

4 Spe

400E+00 20E+03 40E+03 60E+03 80E+03 10E+04 12E+04

Methane in feedgas ppm

0

Ozone content in the outlet gas Specif ic pow er of the ozone generatorg p p g

Effects of N2 and CH4Effects of N2 and CH4

Pi t f h t lli N O t tPicture of an amorphous-crystalline N2O5 structurecaptured at the Orlando Skylake water plant in 2006

Plasma Chemistry with CH4 Impurities

OxygenO2 N2

e - e -

CHO N2

NO2

O NO

O2 N O2 O3

NOH

CH4e-

O3 NO

NO2

O2O3NO N

NO2 O

NO2

NO2

N2ONO3

N

O3

NO2

NO

HNO3

N2O4

N2O5

NO2

NO3

N2O5

Effect of methane on the electrode surfaces

a) b)

Inlet Outlet Outlet

) d)

I l t I l t

c) d)

Electrode of the ozone generator afterseveral hours in CH8O2 and up to 2 wt of methane (a b c)

Inlet Inlet

three hours in CH8O2+traces of N2 and up to 1 wt of methane (d) Visible change of discharge character at about 13 length of electrode (a d)

Kinetics of CHx Conversion without N2

conversion by collisions

O2 + CHx 12wt O3 + CO2 +H2O

deposition vaporizationby sputtering

ibl b l 1000 CHreversible process below 1000ppm CH4

Effect of water on electrode surface with N2

Inlet

OutletOutlet

Electrode of the ozone generator after several hours in H OO N

Inlet

Electrode of the ozone generator after several hours in H2OO2N2

Effect of water on electrode surface

Long term effect (800 hrs) of H2OO2N2

Kinetics of CHx Conversion with N2

conversion by collisionsHNO3 formation

O2 + N2 +CHx 12wtO2 + CO2 +H2O + HNO3

deposition vaporizationby sputtering

H2O + HNO3

by sputtering

irreversible process above a N2 threshold () ltlt 1000ppm N2

sticky deposit

p 2 ( ) pp 2 any CH4 concentration (60ppm)

Plasma Chemistry with CH4 ImpuritiesPlasma Chemistry with CH4 Impurities4

bull Formation of NO and NO2 depends on O3 N2 and gas temperature Conclusion N2 admixture is the key factor

SummarySummaryyyThe mechanisms of formed NOx by-products follows the sameThe mechanisms of formed NOx by-products follows the sameprinciples as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentration

principles as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentrationozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)

ozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)g p ( g p )

The conversion of methane to OH and H2O is found to depend on

g p ( g p )

The conversion of methane to OH and H2O is found to depend ondissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)

dissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)discharge gap)discharge gap)

How do you optimize an ozone generatorg

Scientific ApproachScientific ApproachTheoretical Experimental

pppp

c [wt]

f [Hz]

c [wt]

f [Hz]

[kW]UUUβ1

1Cf4αPn

1iiminpeakimin

iiD

q [kWm2]q [kWm2]

150

180

][V]voltagepeakUpeak

[]cylinder perslicesofamountnsliceii

whereth

09 00

30

60

90

120

effic

ienc

y [

][0tdj t bl[F]sliceisdielectricofecapacitancC

[Hz]frequencyf[V]sliceivoltageminimumiUmin

thiD

th

10

28

46

64

82

39

107

176

244 power density

[kWm2]

ozone conc [wt][]CCβ

][0parameteradjustableα

iDiGi

Impact of Power Inductionp

350

400

wer

200

250

300

App

lied

Pow

Arr C 2Arr D +0

Arr E +45Arr F +7

Arr G +3

5 0

100

150

Frac

tion

of

1 2 3 4

ReferenceArr B unstable

Arr C -2

00

50

4Position (1inlet 4outlet)

Experimental Test Rigp g

Experimental Test Rigp g

Outer grounded electrode (left picture) and the dielectric covered inner electrodes (right) d e ect c cove ed e e ect odes ( g t)

Reference (Traditional) Arrangement

Inlet OutletGas flow direction

Optimized Arrangement

Inlet OutletGas flow direction

Intelligent Gap System (IGS)g p y ( )

Molecular Oxygen (O2) Ozone (O3)

O2 O3

yg ( 2) ( 3)

Particle Size SynthesisParticle Size SynthesisByBy--Products Cluster FormationProducts Cluster Formationyy

high diffusion and deposition to surfaces

low diffusion rate good transport

high sedimentation on the structurehigh sedimentation on the structure

Degreacutemont Technologies ndash OzoniaIntelligent Gap SystemIntelligent Gap System

G Vezzuacute JL Lopez A Freilich and K Becker Optimizationof Large-Scale Ozone Generators IEEE Transactions onPlasma Science Vol 37 No 6 p 890-896 (2009)

ConclusionsConclusionsConclusionsConclusionsFundamentals of ozone synthesis in a DBD plasmay p

ndash Highly filamented DBD discharges are best-suitedfor the production of ozone concentrations in therange of 6 to 14 wtrange of 6 to 14 wt

ndash The preferred characteristic of the microdischargesare Townsend-like at reduced electric fields Enaround 190 Townsend

ndash Detrimental side-effects induced by by-productscan be avoided by a proper design of the electrodecan be avoided by a proper design of the electrodearrangement The phenomenon is related to thediffusion rates of formed by-product clusters

ConclusionsConclusionsConclusionsConclusionsBenefits from DBD microplasma tailoring

ndash Reduced power consumption of up to 10 improvement

ndash Increased ozone concentrations of up to 14 now achievable

ndash Improved neutralization and conditioning of detrimental by-products

ndash Reduced system capital and operational cost

New technologies to improve ozone p

generatorg

HV Pulsed Power SwitchingHV Pulsed Power Switching

Microchannel Generation of Ozone

Channel ArrayChannel Array

Microchannel

330 microm 230 microm

Some Cap-DBD Devices Operating in Air

Increase of 60 of

Spacing 225 μmof 60 of plasma

No space

Cap‐DBD ozone generation

bull Ozone concentration is evaluated via Eco S d l UV 100 O A l (0 01Sensors model UV-100 Ozone Analyzer (001 ndash 900 ppm wiht an accuracy of plusmn2)

bull Three reactors 6 tubings 6rdquo with spacings of 0 μm 225 μm and 500 μm running at 3 kV μ μ μ g

SpacingOzone Concentration

3 kV rms 4 kV rms3 kV rms 4 kV rms

0 μm 660 ppm

225 μm 550 ppm

For a device of such small scale these ozone levels are promising

500 μm 380 ppm

J Mahoney W Zhu VS Johnson KH Becker and JL Lopez Electrical and optical emissionmeasurements of a capillary dielectric barrier discharge European Physics Journal D Vol 60 441-447(2010)

QuestionsQuestions

Thank YouFor more informationProf Jose L Lopez PhD

Thank YouFor more informationDepartment of Physics

Telephone (973) 761-9057Email joselopez1shuedu

Website wwwshueduacademicsartsciphysicsWebsite wwwshueduacademicsartsciphysics

Page 48: Dielectric Barrier Discharge (DBD) & Progress in Large ...bonitz/si12/talks/august_8/lopez_si12.pdf · Dielectric Barrier Discharge (DBD) & Progress in Large-Scale Ozone Generation

Generation of OzoneGeneration of Ozone

Generation of Ozone

Power Supply UnitPower Supply Unit

IGBT Inverter CircuitMain Circuit Breaker

HV 480 Volts60 Hz3 Phase Supply

C I

450KVAPow er to

GeneratorFILTER

CONVERTER INVERTERTRANSFORMER

C I450KVA Power Stage

CONTACTOR

bull Latest in Power Semiconductor Technology Modular Design

bull Utilizes IGBTrsquos (Insulated Gate Bi‐Polar Transistors) Converter and Inverter Components

Ozone Water Treatment

B bbl Diff iB bbl Diff iBubble DiffusionBubble Diffusion

Easy to use

Low energy usage Low energy usage

Mass transfer efficiencies to gt 90

Ozone Process Flow DiagramOzone Process Flow DiagramVent to

Atmosphere

O OOxygen

Off-Gas Blower

Ozone Destruct Unit

10 12

O3O2

LOX

10-12 O3

Ozone Generators

Ozone Contact ChamberLOX T k Generators Chamber

VaporizersLOX Tank

Municipal Ozone Installations

Ozonia Installations Ozone Plant Size [lbday] Start-Up DateKey Ozonia Installations (Partial List)

Los Angeles CA 10000 1986Fairfax VA ndash Corbalis 9000 2003MWD CA ndash Mills 9 000 2003

Ozonia Installations Ozone Plant Size [lbday] Start Up Date

MWD CA Mills 9000 2003Fairfax Co VA ndash Griffith 9000 2004MWD CA ndash Jensen 18750 2005Indianapolis IN ndash Belmont AWT 12000 2007I di li IN 12 000 2007Indianapolis IN ndash Southport AWT 12000 2007MWD CA ndash Diemer 13400 2008MWD CA ndash Weymouth 13400 2009

Ozonia North America - Potable Water SummaryTotal Number of Installations 90Total Installed Production gt 265000 lbsdayTotal Installed Production 265000 lbsday

Revision -B

Ozone Water TreatmentOzone Water Treatment

MWD Mills WTP - California

3 3 000 lbsda of o one3 3 000 lbsda of o one3 x 3000 lbsday of ozone3 x 3000 lbsday of ozone

Ozone Water TreatmentOzone Water TreatmentOzone Ozone -- How it worksHow it works

OxidantOxidant DisinfectantDisinfectant

bullbull Breaks double carbon Breaks double carbon bondsbonds

bullbull Kills by cell lysing or Kills by cell lysing or causing the cell wall tocausing the cell wall tobondsbonds

bullbull Creates OHCreates OHbullbull radicals radicals which break higher carbon which break higher carbon

causing the cell wall to causing the cell wall to rupture rupture

bullbull AttacksAttacks allall bacteriabacteriabondsbondsbullbull Increased temp and pH Increased temp and pH

accelerates Oaccelerates O33

Attacks Attacks allall bacteria bacteria virus cysts and spores virus cysts and spores in varying degreesin varying degreesaccelerates Oaccelerates O33

decomposition to OHdecomposition to OHbullbull

Micro-organism DNA

Capsule AdenineAdenine

Cell wall ThymineThymine

CytosineCytosine

GuanineGuanine

NuclearmaterialCellmembrane

material

Typical Bacterium DNA

Microbial Growth at Various Ozone ConcentrationsConcentrations

Growth likely

Growth possibleGrowth possible

NO GROWTH

0004 0008 0012 0016 0020

Ozone concentration (mgl)Ozone concentration (mgl)

Typical Water Treatment UsageTypical Water Treatment Usage

Application O3 mgl Contact timeUltra Pure Water 005 - 025 sec ndash min

Water bottling 04 ndash 10 5 ndash 10 min

Swimming pools ampspas

01 ndash 075 4 minutes

Potable taste amp odor 15 ndash 50 5 ndash 10 mindisinfection

Microfloculation 10 ndash 30 5 ndash 10 min

Lignin amp tammin 3 0 10 0 10 30 minLignin amp tamminremoval

30 ndash 100 10 ndash 30 min

Municipal wastewater 50 ndash 150+ 15 ndash 30 min

Ozone Water TreatmentOzone Water TreatmentOzone Ozone ndashndash Municipal ApplicationsMunicipal Applications

bullbull Taste and OdorTaste and Odor

bullbull Color RemovalColor Removal

bullbull Disinfection Without Trihalomethanes (THMs)Disinfection Without Trihalomethanes (THMs)

bullbull Improved Filtration Efficiency and FlocculationImproved Filtration Efficiency and Flocculation

bullbull Cryptosporidium DeactivationCryptosporidium Deactivation

bullbull Giardia amp Virus InactivationGiardia amp Virus Inactivation

bullbull Oxidation Oxidation -- Organics Fe amp MnOrganics Fe amp Mn

bullbull Wastewater disinfectionWastewater disinfection

bullbull BOD COD and TOC reductionBOD COD and TOC reduction

Applications of Ozone

Wastewater Treatmentbull Disinfection of Secondary and Tertiary Effluentsbull Color Reductionbull Color Reductionbull TOC Oxidation (Industrial)bull Oxidation of Odor Causing Compoundsbull Oxidation of Endocrine Disruptors (EDCrsquos) and p ( )

Pharmaceutically Active Compounds (PACrsquos)

Applications of Ozone

What are Endocrine Disruptors (EDCrsquos) and What are Endocrine Disruptors (EDCrsquos) and Ph ti ll A ti C d (PACrsquo )Ph ti ll A ti C d (PACrsquo )Pharmaceutically Active Compounds (PACrsquos)Pharmaceutically Active Compounds (PACrsquos)

bullbull EDCrsquosEDCrsquos andand PACrsquosPACrsquos areare NaturallyNaturally andand SyntheticSyntheticdd th tth t ff tff t thth b lb l llcompoundscompounds thatthat maymay affectaffect thethe balancebalance oror normalnormal

functionsfunctions inin animalsanimals andand humanshumans

What can EDCrsquos and PACrsquos doWhat can EDCrsquos and PACrsquos do

bullbull Even in very small concentrations these compounds Even in very small concentrations these compounds y py pcan can disruptdisrupt normal bodily functionsnormal bodily functions

bullbull ManMan--made chemicals can trick the bodies endocrine made chemicals can trick the bodies endocrine system system

Applications of Ozone

Examples of Endocrine Disruptors1000rsquos of compounds that may be Investigated as EDCs ndash Some examples are

bullbull Synthetic HormonesSynthetic Hormonesbullbull Naturally Occurring Estrogens Naturally Occurring Estrogens

Health and Beauty AidsHealth and Beauty Aidsbullbull Health and Beauty AidsHealth and Beauty Aidsbullbull SolventsSolventsbullbull PesticidesPesticidesbullbull SurfactantsSurfactantsbullbull PlasticsPlastics

F i idF i idbullbull FungicidesFungicides

Ozone Water TreatmentOzone Water Treatment

Ozone Ozone -- Industrial ApplicationsIndustrial Applications-- Ultrapure Water for Pharmaceutical ApplicationsUltrapure Water for Pharmaceutical Applications

-- Wastewater disinfection color removalWastewater disinfection color removal

-- Soil and Groundwater Remediation Soil and Groundwater Remediation

-- Cooling Tower Water TreatmentCooling Tower Water Treatment

-- Food ProcessingFood Processing

-- Aquaculture AquariumsAquaculture AquariumsAquaculture AquariumsAquaculture Aquariums

-- Beverage ApplicationsBeverage Applications

P l amp P Bl hiP l amp P Bl hi-- Pulp amp Paper BleachingPulp amp Paper Bleaching

High Purity OzonationHigh Purity Ozonation

Microchip manufacturingMicrochip manufacturing

What are the current issues in large-scale gozone generationg

Experimental Setup

Front view of the two units after the redesign and reworking ofthe gas water and instruments connectionsthe gas water and instruments connections

Experimental Setup

Top view of the twoexperimental unitsexperimental unitsSpectroscope (notshown) is to the left ofthe DBD The units weredifferent with respect todifferent with respect totheir electrodes onehad only the electrodecoated with thedielectric (ldquosingle-dielectric ( single-coatedrdquo) the other onehad the electrode andthe anode coated withthe dielectric (ldquodouble-the dielectric ( double-coatedrdquo)

Basics Generation of OzoneBasics Generation of Ozone

SpectroscopyPlasma

Plasma Absorption SpectroscopyPlasma Absorption Spectroscopy

Infrared Absorption SpectroscopyInfrared Absorption Spectroscopy

IR spectra in pure oxygen (black curve) and at approximately 10wt N2 admixture (red line) N2O5 peaks appear at124 1 d 1 2 11245 cm-1 and at 1725 cm-1

Infrared Absorption SpectroscopyInfrared Absorption Spectroscopy

IR spectra of several methane variations The green curve envelopes all of the methane peaks at 1325 cm-1recorded at smaller methane admixtures Simultaneously the N2O5 peaks disappear as the methane peaks appear

N2O5 FormationN2O5 Formation2 52 5p=2 bara cwt=20degC q=35kWm2 f=1450Hz

45N2O5 AT95

30

35

40

N

2 B

lend

ing

N2O AT95N2O5 IGSN2O IGSN2O5 LGN2O LG

1 5

20

25

nt [p

pmV]

3

wt

05

10

15

NO

x co

nten

005 7 9 11 13 15 17

ozone conc [wt]

Amount of formed N2O5 and N2O as a function of ozone concentration at 3 wt of nitrogen admixture and fori l dvarious electrode arrangements

Plasma Emission SpectroscopyPlasma Emission Spectroscopyp pyp py

Relative Emissions of the Ozonizer plasmaRelative Emissions of the Ozonizer plasma

Region 300- 850 nm from individual (calibrated) regions (smoothed by PeakFit) Single-coated ozone generator Inlet side

3 5E+06

30E+06

35E+06

7 9

20E+06

25E+06

nten

sity

au

2

311 12

10E+06

15E+06

In 4

5

6 8 10

14

15

16

17

00E+00

50E+05

280 300 320 340 360 380 400 420 440 460 480 500 520 540 560 580 600 620 640 660 680 700 720 740 760 780 800 820 840 860

Wavelength nm

1 13

Wavelength nm

Absolute Emission of the DBD PlasmaAbsolute Emission of the DBD Plasma

Intensities in (O2+3 wtN2) plasma

1 20E+04

100E+04

120E+04

600E+03

800E+03

nten

sity

(au

)

200E+03

400E+03

In

O(777)

000E+00200 250 300 350 400 450 500 550 600 650 700 750 800 850

Wavelength nm

Intensities in 3 wtN2+O2 plasmaIntensities in 3 wtN2+O2 plasma

Plasma Chemistry in OzonizersPlasma Chemistry in Ozonizers

Dry Air O2 N2

e - e -

O N2 N O2

O3 NO

O2 N O2

O3

N

3

NO2

O2 O3

NO

N

NO2 O3

N2O

NO3 N

N2O4

NO2

NO2

N2O5

NO3

Primary electron-driven chemical reactions leading to the formation of N2O5 and N2O in a dry air plasma

Plasma emission diagnostics role of N2Plasma emission diagnostics role of N2

Dry Air O2 N2

e - e -

O N2 N O2

O3 NO

O2 N O2

O3

O

N

ON

NO2

O2O3

N

NO N

NO2 O3

N2O

NO3 N

N2O4

NO2

NO2

N2O5

NO3

ONbullWith N2 present ndash less oxygen atoms are formed However the difference in intensity is

very small

Modeling of plasma chemistry incl the NxOy chemistry up to N2O5 for different Oxygen Nitrogen mixtures varying power deposition scenarios

and initial ozone background concentrations (up to 15) previously done

The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation

The role of N2 must be related to its by-products reacting on the surface of the electrodeThe role of N2 must be related to its by-products reacting on the surface of the electrode

The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established

Ab 8 t f O

The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established

Ab 8 t f OAbove 8 wt of O3

1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)

Above 8 wt of O3

1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)case without pampp)

2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of the

case without pampp)

2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of thethem A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface

them A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface

The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation

Three possibilities have to be considered for the oxygen-fedozone generator

Three possibilities have to be considered for the oxygen-fedozone generatorozone generator

bull Excited N2 molecules lead to an increased O2 dissociation in

ozone generator

bull Excited N2 molecules lead to an increased O2 dissociation in2 2such case an increased efficiency is correlated to the N2admixture

2 2such case an increased efficiency is correlated to the N2admixture

bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial

bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial

bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2

bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2g p g 3 pp y 2g p g 3 pp y 2

Effect of methane on ozone efficiency and specific powerEffect of methane on ozone efficiency and specific power

Effect of Methane on Ozone Content in Outlet Gas and on Specific Power Pure O2

13 12

10

11

12

t 8

10

8

9

10

ne c

onte

nt w

t

6

8

ecifi

c po

wer

kW

hlb

5

6

7

Ozo

n

2

4 Spe

400E+00 20E+03 40E+03 60E+03 80E+03 10E+04 12E+04

Methane in feedgas ppm

0

Ozone content in the outlet gas Specif ic pow er of the ozone generatorg p p g

Effects of N2 and CH4Effects of N2 and CH4

Pi t f h t lli N O t tPicture of an amorphous-crystalline N2O5 structurecaptured at the Orlando Skylake water plant in 2006

Plasma Chemistry with CH4 Impurities

OxygenO2 N2

e - e -

CHO N2

NO2

O NO

O2 N O2 O3

NOH

CH4e-

O3 NO

NO2

O2O3NO N

NO2 O

NO2

NO2

N2ONO3

N

O3

NO2

NO

HNO3

N2O4

N2O5

NO2

NO3

N2O5

Effect of methane on the electrode surfaces

a) b)

Inlet Outlet Outlet

) d)

I l t I l t

c) d)

Electrode of the ozone generator afterseveral hours in CH8O2 and up to 2 wt of methane (a b c)

Inlet Inlet

three hours in CH8O2+traces of N2 and up to 1 wt of methane (d) Visible change of discharge character at about 13 length of electrode (a d)

Kinetics of CHx Conversion without N2

conversion by collisions

O2 + CHx 12wt O3 + CO2 +H2O

deposition vaporizationby sputtering

ibl b l 1000 CHreversible process below 1000ppm CH4

Effect of water on electrode surface with N2

Inlet

OutletOutlet

Electrode of the ozone generator after several hours in H OO N

Inlet

Electrode of the ozone generator after several hours in H2OO2N2

Effect of water on electrode surface

Long term effect (800 hrs) of H2OO2N2

Kinetics of CHx Conversion with N2

conversion by collisionsHNO3 formation

O2 + N2 +CHx 12wtO2 + CO2 +H2O + HNO3

deposition vaporizationby sputtering

H2O + HNO3

by sputtering

irreversible process above a N2 threshold () ltlt 1000ppm N2

sticky deposit

p 2 ( ) pp 2 any CH4 concentration (60ppm)

Plasma Chemistry with CH4 ImpuritiesPlasma Chemistry with CH4 Impurities4

bull Formation of NO and NO2 depends on O3 N2 and gas temperature Conclusion N2 admixture is the key factor

SummarySummaryyyThe mechanisms of formed NOx by-products follows the sameThe mechanisms of formed NOx by-products follows the sameprinciples as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentration

principles as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentrationozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)

ozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)g p ( g p )

The conversion of methane to OH and H2O is found to depend on

g p ( g p )

The conversion of methane to OH and H2O is found to depend ondissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)

dissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)discharge gap)discharge gap)

How do you optimize an ozone generatorg

Scientific ApproachScientific ApproachTheoretical Experimental

pppp

c [wt]

f [Hz]

c [wt]

f [Hz]

[kW]UUUβ1

1Cf4αPn

1iiminpeakimin

iiD

q [kWm2]q [kWm2]

150

180

][V]voltagepeakUpeak

[]cylinder perslicesofamountnsliceii

whereth

09 00

30

60

90

120

effic

ienc

y [

][0tdj t bl[F]sliceisdielectricofecapacitancC

[Hz]frequencyf[V]sliceivoltageminimumiUmin

thiD

th

10

28

46

64

82

39

107

176

244 power density

[kWm2]

ozone conc [wt][]CCβ

][0parameteradjustableα

iDiGi

Impact of Power Inductionp

350

400

wer

200

250

300

App

lied

Pow

Arr C 2Arr D +0

Arr E +45Arr F +7

Arr G +3

5 0

100

150

Frac

tion

of

1 2 3 4

ReferenceArr B unstable

Arr C -2

00

50

4Position (1inlet 4outlet)

Experimental Test Rigp g

Experimental Test Rigp g

Outer grounded electrode (left picture) and the dielectric covered inner electrodes (right) d e ect c cove ed e e ect odes ( g t)

Reference (Traditional) Arrangement

Inlet OutletGas flow direction

Optimized Arrangement

Inlet OutletGas flow direction

Intelligent Gap System (IGS)g p y ( )

Molecular Oxygen (O2) Ozone (O3)

O2 O3

yg ( 2) ( 3)

Particle Size SynthesisParticle Size SynthesisByBy--Products Cluster FormationProducts Cluster Formationyy

high diffusion and deposition to surfaces

low diffusion rate good transport

high sedimentation on the structurehigh sedimentation on the structure

Degreacutemont Technologies ndash OzoniaIntelligent Gap SystemIntelligent Gap System

G Vezzuacute JL Lopez A Freilich and K Becker Optimizationof Large-Scale Ozone Generators IEEE Transactions onPlasma Science Vol 37 No 6 p 890-896 (2009)

ConclusionsConclusionsConclusionsConclusionsFundamentals of ozone synthesis in a DBD plasmay p

ndash Highly filamented DBD discharges are best-suitedfor the production of ozone concentrations in therange of 6 to 14 wtrange of 6 to 14 wt

ndash The preferred characteristic of the microdischargesare Townsend-like at reduced electric fields Enaround 190 Townsend

ndash Detrimental side-effects induced by by-productscan be avoided by a proper design of the electrodecan be avoided by a proper design of the electrodearrangement The phenomenon is related to thediffusion rates of formed by-product clusters

ConclusionsConclusionsConclusionsConclusionsBenefits from DBD microplasma tailoring

ndash Reduced power consumption of up to 10 improvement

ndash Increased ozone concentrations of up to 14 now achievable

ndash Improved neutralization and conditioning of detrimental by-products

ndash Reduced system capital and operational cost

New technologies to improve ozone p

generatorg

HV Pulsed Power SwitchingHV Pulsed Power Switching

Microchannel Generation of Ozone

Channel ArrayChannel Array

Microchannel

330 microm 230 microm

Some Cap-DBD Devices Operating in Air

Increase of 60 of

Spacing 225 μmof 60 of plasma

No space

Cap‐DBD ozone generation

bull Ozone concentration is evaluated via Eco S d l UV 100 O A l (0 01Sensors model UV-100 Ozone Analyzer (001 ndash 900 ppm wiht an accuracy of plusmn2)

bull Three reactors 6 tubings 6rdquo with spacings of 0 μm 225 μm and 500 μm running at 3 kV μ μ μ g

SpacingOzone Concentration

3 kV rms 4 kV rms3 kV rms 4 kV rms

0 μm 660 ppm

225 μm 550 ppm

For a device of such small scale these ozone levels are promising

500 μm 380 ppm

J Mahoney W Zhu VS Johnson KH Becker and JL Lopez Electrical and optical emissionmeasurements of a capillary dielectric barrier discharge European Physics Journal D Vol 60 441-447(2010)

QuestionsQuestions

Thank YouFor more informationProf Jose L Lopez PhD

Thank YouFor more informationDepartment of Physics

Telephone (973) 761-9057Email joselopez1shuedu

Website wwwshueduacademicsartsciphysicsWebsite wwwshueduacademicsartsciphysics

Page 49: Dielectric Barrier Discharge (DBD) & Progress in Large ...bonitz/si12/talks/august_8/lopez_si12.pdf · Dielectric Barrier Discharge (DBD) & Progress in Large-Scale Ozone Generation

Generation of Ozone

Power Supply UnitPower Supply Unit

IGBT Inverter CircuitMain Circuit Breaker

HV 480 Volts60 Hz3 Phase Supply

C I

450KVAPow er to

GeneratorFILTER

CONVERTER INVERTERTRANSFORMER

C I450KVA Power Stage

CONTACTOR

bull Latest in Power Semiconductor Technology Modular Design

bull Utilizes IGBTrsquos (Insulated Gate Bi‐Polar Transistors) Converter and Inverter Components

Ozone Water Treatment

B bbl Diff iB bbl Diff iBubble DiffusionBubble Diffusion

Easy to use

Low energy usage Low energy usage

Mass transfer efficiencies to gt 90

Ozone Process Flow DiagramOzone Process Flow DiagramVent to

Atmosphere

O OOxygen

Off-Gas Blower

Ozone Destruct Unit

10 12

O3O2

LOX

10-12 O3

Ozone Generators

Ozone Contact ChamberLOX T k Generators Chamber

VaporizersLOX Tank

Municipal Ozone Installations

Ozonia Installations Ozone Plant Size [lbday] Start-Up DateKey Ozonia Installations (Partial List)

Los Angeles CA 10000 1986Fairfax VA ndash Corbalis 9000 2003MWD CA ndash Mills 9 000 2003

Ozonia Installations Ozone Plant Size [lbday] Start Up Date

MWD CA Mills 9000 2003Fairfax Co VA ndash Griffith 9000 2004MWD CA ndash Jensen 18750 2005Indianapolis IN ndash Belmont AWT 12000 2007I di li IN 12 000 2007Indianapolis IN ndash Southport AWT 12000 2007MWD CA ndash Diemer 13400 2008MWD CA ndash Weymouth 13400 2009

Ozonia North America - Potable Water SummaryTotal Number of Installations 90Total Installed Production gt 265000 lbsdayTotal Installed Production 265000 lbsday

Revision -B

Ozone Water TreatmentOzone Water Treatment

MWD Mills WTP - California

3 3 000 lbsda of o one3 3 000 lbsda of o one3 x 3000 lbsday of ozone3 x 3000 lbsday of ozone

Ozone Water TreatmentOzone Water TreatmentOzone Ozone -- How it worksHow it works

OxidantOxidant DisinfectantDisinfectant

bullbull Breaks double carbon Breaks double carbon bondsbonds

bullbull Kills by cell lysing or Kills by cell lysing or causing the cell wall tocausing the cell wall tobondsbonds

bullbull Creates OHCreates OHbullbull radicals radicals which break higher carbon which break higher carbon

causing the cell wall to causing the cell wall to rupture rupture

bullbull AttacksAttacks allall bacteriabacteriabondsbondsbullbull Increased temp and pH Increased temp and pH

accelerates Oaccelerates O33

Attacks Attacks allall bacteria bacteria virus cysts and spores virus cysts and spores in varying degreesin varying degreesaccelerates Oaccelerates O33

decomposition to OHdecomposition to OHbullbull

Micro-organism DNA

Capsule AdenineAdenine

Cell wall ThymineThymine

CytosineCytosine

GuanineGuanine

NuclearmaterialCellmembrane

material

Typical Bacterium DNA

Microbial Growth at Various Ozone ConcentrationsConcentrations

Growth likely

Growth possibleGrowth possible

NO GROWTH

0004 0008 0012 0016 0020

Ozone concentration (mgl)Ozone concentration (mgl)

Typical Water Treatment UsageTypical Water Treatment Usage

Application O3 mgl Contact timeUltra Pure Water 005 - 025 sec ndash min

Water bottling 04 ndash 10 5 ndash 10 min

Swimming pools ampspas

01 ndash 075 4 minutes

Potable taste amp odor 15 ndash 50 5 ndash 10 mindisinfection

Microfloculation 10 ndash 30 5 ndash 10 min

Lignin amp tammin 3 0 10 0 10 30 minLignin amp tamminremoval

30 ndash 100 10 ndash 30 min

Municipal wastewater 50 ndash 150+ 15 ndash 30 min

Ozone Water TreatmentOzone Water TreatmentOzone Ozone ndashndash Municipal ApplicationsMunicipal Applications

bullbull Taste and OdorTaste and Odor

bullbull Color RemovalColor Removal

bullbull Disinfection Without Trihalomethanes (THMs)Disinfection Without Trihalomethanes (THMs)

bullbull Improved Filtration Efficiency and FlocculationImproved Filtration Efficiency and Flocculation

bullbull Cryptosporidium DeactivationCryptosporidium Deactivation

bullbull Giardia amp Virus InactivationGiardia amp Virus Inactivation

bullbull Oxidation Oxidation -- Organics Fe amp MnOrganics Fe amp Mn

bullbull Wastewater disinfectionWastewater disinfection

bullbull BOD COD and TOC reductionBOD COD and TOC reduction

Applications of Ozone

Wastewater Treatmentbull Disinfection of Secondary and Tertiary Effluentsbull Color Reductionbull Color Reductionbull TOC Oxidation (Industrial)bull Oxidation of Odor Causing Compoundsbull Oxidation of Endocrine Disruptors (EDCrsquos) and p ( )

Pharmaceutically Active Compounds (PACrsquos)

Applications of Ozone

What are Endocrine Disruptors (EDCrsquos) and What are Endocrine Disruptors (EDCrsquos) and Ph ti ll A ti C d (PACrsquo )Ph ti ll A ti C d (PACrsquo )Pharmaceutically Active Compounds (PACrsquos)Pharmaceutically Active Compounds (PACrsquos)

bullbull EDCrsquosEDCrsquos andand PACrsquosPACrsquos areare NaturallyNaturally andand SyntheticSyntheticdd th tth t ff tff t thth b lb l llcompoundscompounds thatthat maymay affectaffect thethe balancebalance oror normalnormal

functionsfunctions inin animalsanimals andand humanshumans

What can EDCrsquos and PACrsquos doWhat can EDCrsquos and PACrsquos do

bullbull Even in very small concentrations these compounds Even in very small concentrations these compounds y py pcan can disruptdisrupt normal bodily functionsnormal bodily functions

bullbull ManMan--made chemicals can trick the bodies endocrine made chemicals can trick the bodies endocrine system system

Applications of Ozone

Examples of Endocrine Disruptors1000rsquos of compounds that may be Investigated as EDCs ndash Some examples are

bullbull Synthetic HormonesSynthetic Hormonesbullbull Naturally Occurring Estrogens Naturally Occurring Estrogens

Health and Beauty AidsHealth and Beauty Aidsbullbull Health and Beauty AidsHealth and Beauty Aidsbullbull SolventsSolventsbullbull PesticidesPesticidesbullbull SurfactantsSurfactantsbullbull PlasticsPlastics

F i idF i idbullbull FungicidesFungicides

Ozone Water TreatmentOzone Water Treatment

Ozone Ozone -- Industrial ApplicationsIndustrial Applications-- Ultrapure Water for Pharmaceutical ApplicationsUltrapure Water for Pharmaceutical Applications

-- Wastewater disinfection color removalWastewater disinfection color removal

-- Soil and Groundwater Remediation Soil and Groundwater Remediation

-- Cooling Tower Water TreatmentCooling Tower Water Treatment

-- Food ProcessingFood Processing

-- Aquaculture AquariumsAquaculture AquariumsAquaculture AquariumsAquaculture Aquariums

-- Beverage ApplicationsBeverage Applications

P l amp P Bl hiP l amp P Bl hi-- Pulp amp Paper BleachingPulp amp Paper Bleaching

High Purity OzonationHigh Purity Ozonation

Microchip manufacturingMicrochip manufacturing

What are the current issues in large-scale gozone generationg

Experimental Setup

Front view of the two units after the redesign and reworking ofthe gas water and instruments connectionsthe gas water and instruments connections

Experimental Setup

Top view of the twoexperimental unitsexperimental unitsSpectroscope (notshown) is to the left ofthe DBD The units weredifferent with respect todifferent with respect totheir electrodes onehad only the electrodecoated with thedielectric (ldquosingle-dielectric ( single-coatedrdquo) the other onehad the electrode andthe anode coated withthe dielectric (ldquodouble-the dielectric ( double-coatedrdquo)

Basics Generation of OzoneBasics Generation of Ozone

SpectroscopyPlasma

Plasma Absorption SpectroscopyPlasma Absorption Spectroscopy

Infrared Absorption SpectroscopyInfrared Absorption Spectroscopy

IR spectra in pure oxygen (black curve) and at approximately 10wt N2 admixture (red line) N2O5 peaks appear at124 1 d 1 2 11245 cm-1 and at 1725 cm-1

Infrared Absorption SpectroscopyInfrared Absorption Spectroscopy

IR spectra of several methane variations The green curve envelopes all of the methane peaks at 1325 cm-1recorded at smaller methane admixtures Simultaneously the N2O5 peaks disappear as the methane peaks appear

N2O5 FormationN2O5 Formation2 52 5p=2 bara cwt=20degC q=35kWm2 f=1450Hz

45N2O5 AT95

30

35

40

N

2 B

lend

ing

N2O AT95N2O5 IGSN2O IGSN2O5 LGN2O LG

1 5

20

25

nt [p

pmV]

3

wt

05

10

15

NO

x co

nten

005 7 9 11 13 15 17

ozone conc [wt]

Amount of formed N2O5 and N2O as a function of ozone concentration at 3 wt of nitrogen admixture and fori l dvarious electrode arrangements

Plasma Emission SpectroscopyPlasma Emission Spectroscopyp pyp py

Relative Emissions of the Ozonizer plasmaRelative Emissions of the Ozonizer plasma

Region 300- 850 nm from individual (calibrated) regions (smoothed by PeakFit) Single-coated ozone generator Inlet side

3 5E+06

30E+06

35E+06

7 9

20E+06

25E+06

nten

sity

au

2

311 12

10E+06

15E+06

In 4

5

6 8 10

14

15

16

17

00E+00

50E+05

280 300 320 340 360 380 400 420 440 460 480 500 520 540 560 580 600 620 640 660 680 700 720 740 760 780 800 820 840 860

Wavelength nm

1 13

Wavelength nm

Absolute Emission of the DBD PlasmaAbsolute Emission of the DBD Plasma

Intensities in (O2+3 wtN2) plasma

1 20E+04

100E+04

120E+04

600E+03

800E+03

nten

sity

(au

)

200E+03

400E+03

In

O(777)

000E+00200 250 300 350 400 450 500 550 600 650 700 750 800 850

Wavelength nm

Intensities in 3 wtN2+O2 plasmaIntensities in 3 wtN2+O2 plasma

Plasma Chemistry in OzonizersPlasma Chemistry in Ozonizers

Dry Air O2 N2

e - e -

O N2 N O2

O3 NO

O2 N O2

O3

N

3

NO2

O2 O3

NO

N

NO2 O3

N2O

NO3 N

N2O4

NO2

NO2

N2O5

NO3

Primary electron-driven chemical reactions leading to the formation of N2O5 and N2O in a dry air plasma

Plasma emission diagnostics role of N2Plasma emission diagnostics role of N2

Dry Air O2 N2

e - e -

O N2 N O2

O3 NO

O2 N O2

O3

O

N

ON

NO2

O2O3

N

NO N

NO2 O3

N2O

NO3 N

N2O4

NO2

NO2

N2O5

NO3

ONbullWith N2 present ndash less oxygen atoms are formed However the difference in intensity is

very small

Modeling of plasma chemistry incl the NxOy chemistry up to N2O5 for different Oxygen Nitrogen mixtures varying power deposition scenarios

and initial ozone background concentrations (up to 15) previously done

The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation

The role of N2 must be related to its by-products reacting on the surface of the electrodeThe role of N2 must be related to its by-products reacting on the surface of the electrode

The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established

Ab 8 t f O

The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established

Ab 8 t f OAbove 8 wt of O3

1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)

Above 8 wt of O3

1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)case without pampp)

2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of the

case without pampp)

2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of thethem A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface

them A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface

The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation

Three possibilities have to be considered for the oxygen-fedozone generator

Three possibilities have to be considered for the oxygen-fedozone generatorozone generator

bull Excited N2 molecules lead to an increased O2 dissociation in

ozone generator

bull Excited N2 molecules lead to an increased O2 dissociation in2 2such case an increased efficiency is correlated to the N2admixture

2 2such case an increased efficiency is correlated to the N2admixture

bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial

bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial

bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2

bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2g p g 3 pp y 2g p g 3 pp y 2

Effect of methane on ozone efficiency and specific powerEffect of methane on ozone efficiency and specific power

Effect of Methane on Ozone Content in Outlet Gas and on Specific Power Pure O2

13 12

10

11

12

t 8

10

8

9

10

ne c

onte

nt w

t

6

8

ecifi

c po

wer

kW

hlb

5

6

7

Ozo

n

2

4 Spe

400E+00 20E+03 40E+03 60E+03 80E+03 10E+04 12E+04

Methane in feedgas ppm

0

Ozone content in the outlet gas Specif ic pow er of the ozone generatorg p p g

Effects of N2 and CH4Effects of N2 and CH4

Pi t f h t lli N O t tPicture of an amorphous-crystalline N2O5 structurecaptured at the Orlando Skylake water plant in 2006

Plasma Chemistry with CH4 Impurities

OxygenO2 N2

e - e -

CHO N2

NO2

O NO

O2 N O2 O3

NOH

CH4e-

O3 NO

NO2

O2O3NO N

NO2 O

NO2

NO2

N2ONO3

N

O3

NO2

NO

HNO3

N2O4

N2O5

NO2

NO3

N2O5

Effect of methane on the electrode surfaces

a) b)

Inlet Outlet Outlet

) d)

I l t I l t

c) d)

Electrode of the ozone generator afterseveral hours in CH8O2 and up to 2 wt of methane (a b c)

Inlet Inlet

three hours in CH8O2+traces of N2 and up to 1 wt of methane (d) Visible change of discharge character at about 13 length of electrode (a d)

Kinetics of CHx Conversion without N2

conversion by collisions

O2 + CHx 12wt O3 + CO2 +H2O

deposition vaporizationby sputtering

ibl b l 1000 CHreversible process below 1000ppm CH4

Effect of water on electrode surface with N2

Inlet

OutletOutlet

Electrode of the ozone generator after several hours in H OO N

Inlet

Electrode of the ozone generator after several hours in H2OO2N2

Effect of water on electrode surface

Long term effect (800 hrs) of H2OO2N2

Kinetics of CHx Conversion with N2

conversion by collisionsHNO3 formation

O2 + N2 +CHx 12wtO2 + CO2 +H2O + HNO3

deposition vaporizationby sputtering

H2O + HNO3

by sputtering

irreversible process above a N2 threshold () ltlt 1000ppm N2

sticky deposit

p 2 ( ) pp 2 any CH4 concentration (60ppm)

Plasma Chemistry with CH4 ImpuritiesPlasma Chemistry with CH4 Impurities4

bull Formation of NO and NO2 depends on O3 N2 and gas temperature Conclusion N2 admixture is the key factor

SummarySummaryyyThe mechanisms of formed NOx by-products follows the sameThe mechanisms of formed NOx by-products follows the sameprinciples as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentration

principles as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentrationozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)

ozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)g p ( g p )

The conversion of methane to OH and H2O is found to depend on

g p ( g p )

The conversion of methane to OH and H2O is found to depend ondissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)

dissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)discharge gap)discharge gap)

How do you optimize an ozone generatorg

Scientific ApproachScientific ApproachTheoretical Experimental

pppp

c [wt]

f [Hz]

c [wt]

f [Hz]

[kW]UUUβ1

1Cf4αPn

1iiminpeakimin

iiD

q [kWm2]q [kWm2]

150

180

][V]voltagepeakUpeak

[]cylinder perslicesofamountnsliceii

whereth

09 00

30

60

90

120

effic

ienc

y [

][0tdj t bl[F]sliceisdielectricofecapacitancC

[Hz]frequencyf[V]sliceivoltageminimumiUmin

thiD

th

10

28

46

64

82

39

107

176

244 power density

[kWm2]

ozone conc [wt][]CCβ

][0parameteradjustableα

iDiGi

Impact of Power Inductionp

350

400

wer

200

250

300

App

lied

Pow

Arr C 2Arr D +0

Arr E +45Arr F +7

Arr G +3

5 0

100

150

Frac

tion

of

1 2 3 4

ReferenceArr B unstable

Arr C -2

00

50

4Position (1inlet 4outlet)

Experimental Test Rigp g

Experimental Test Rigp g

Outer grounded electrode (left picture) and the dielectric covered inner electrodes (right) d e ect c cove ed e e ect odes ( g t)

Reference (Traditional) Arrangement

Inlet OutletGas flow direction

Optimized Arrangement

Inlet OutletGas flow direction

Intelligent Gap System (IGS)g p y ( )

Molecular Oxygen (O2) Ozone (O3)

O2 O3

yg ( 2) ( 3)

Particle Size SynthesisParticle Size SynthesisByBy--Products Cluster FormationProducts Cluster Formationyy

high diffusion and deposition to surfaces

low diffusion rate good transport

high sedimentation on the structurehigh sedimentation on the structure

Degreacutemont Technologies ndash OzoniaIntelligent Gap SystemIntelligent Gap System

G Vezzuacute JL Lopez A Freilich and K Becker Optimizationof Large-Scale Ozone Generators IEEE Transactions onPlasma Science Vol 37 No 6 p 890-896 (2009)

ConclusionsConclusionsConclusionsConclusionsFundamentals of ozone synthesis in a DBD plasmay p

ndash Highly filamented DBD discharges are best-suitedfor the production of ozone concentrations in therange of 6 to 14 wtrange of 6 to 14 wt

ndash The preferred characteristic of the microdischargesare Townsend-like at reduced electric fields Enaround 190 Townsend

ndash Detrimental side-effects induced by by-productscan be avoided by a proper design of the electrodecan be avoided by a proper design of the electrodearrangement The phenomenon is related to thediffusion rates of formed by-product clusters

ConclusionsConclusionsConclusionsConclusionsBenefits from DBD microplasma tailoring

ndash Reduced power consumption of up to 10 improvement

ndash Increased ozone concentrations of up to 14 now achievable

ndash Improved neutralization and conditioning of detrimental by-products

ndash Reduced system capital and operational cost

New technologies to improve ozone p

generatorg

HV Pulsed Power SwitchingHV Pulsed Power Switching

Microchannel Generation of Ozone

Channel ArrayChannel Array

Microchannel

330 microm 230 microm

Some Cap-DBD Devices Operating in Air

Increase of 60 of

Spacing 225 μmof 60 of plasma

No space

Cap‐DBD ozone generation

bull Ozone concentration is evaluated via Eco S d l UV 100 O A l (0 01Sensors model UV-100 Ozone Analyzer (001 ndash 900 ppm wiht an accuracy of plusmn2)

bull Three reactors 6 tubings 6rdquo with spacings of 0 μm 225 μm and 500 μm running at 3 kV μ μ μ g

SpacingOzone Concentration

3 kV rms 4 kV rms3 kV rms 4 kV rms

0 μm 660 ppm

225 μm 550 ppm

For a device of such small scale these ozone levels are promising

500 μm 380 ppm

J Mahoney W Zhu VS Johnson KH Becker and JL Lopez Electrical and optical emissionmeasurements of a capillary dielectric barrier discharge European Physics Journal D Vol 60 441-447(2010)

QuestionsQuestions

Thank YouFor more informationProf Jose L Lopez PhD

Thank YouFor more informationDepartment of Physics

Telephone (973) 761-9057Email joselopez1shuedu

Website wwwshueduacademicsartsciphysicsWebsite wwwshueduacademicsartsciphysics

Page 50: Dielectric Barrier Discharge (DBD) & Progress in Large ...bonitz/si12/talks/august_8/lopez_si12.pdf · Dielectric Barrier Discharge (DBD) & Progress in Large-Scale Ozone Generation

IGBT Inverter CircuitMain Circuit Breaker

HV 480 Volts60 Hz3 Phase Supply

C I

450KVAPow er to

GeneratorFILTER

CONVERTER INVERTERTRANSFORMER

C I450KVA Power Stage

CONTACTOR

bull Latest in Power Semiconductor Technology Modular Design

bull Utilizes IGBTrsquos (Insulated Gate Bi‐Polar Transistors) Converter and Inverter Components

Ozone Water Treatment

B bbl Diff iB bbl Diff iBubble DiffusionBubble Diffusion

Easy to use

Low energy usage Low energy usage

Mass transfer efficiencies to gt 90

Ozone Process Flow DiagramOzone Process Flow DiagramVent to

Atmosphere

O OOxygen

Off-Gas Blower

Ozone Destruct Unit

10 12

O3O2

LOX

10-12 O3

Ozone Generators

Ozone Contact ChamberLOX T k Generators Chamber

VaporizersLOX Tank

Municipal Ozone Installations

Ozonia Installations Ozone Plant Size [lbday] Start-Up DateKey Ozonia Installations (Partial List)

Los Angeles CA 10000 1986Fairfax VA ndash Corbalis 9000 2003MWD CA ndash Mills 9 000 2003

Ozonia Installations Ozone Plant Size [lbday] Start Up Date

MWD CA Mills 9000 2003Fairfax Co VA ndash Griffith 9000 2004MWD CA ndash Jensen 18750 2005Indianapolis IN ndash Belmont AWT 12000 2007I di li IN 12 000 2007Indianapolis IN ndash Southport AWT 12000 2007MWD CA ndash Diemer 13400 2008MWD CA ndash Weymouth 13400 2009

Ozonia North America - Potable Water SummaryTotal Number of Installations 90Total Installed Production gt 265000 lbsdayTotal Installed Production 265000 lbsday

Revision -B

Ozone Water TreatmentOzone Water Treatment

MWD Mills WTP - California

3 3 000 lbsda of o one3 3 000 lbsda of o one3 x 3000 lbsday of ozone3 x 3000 lbsday of ozone

Ozone Water TreatmentOzone Water TreatmentOzone Ozone -- How it worksHow it works

OxidantOxidant DisinfectantDisinfectant

bullbull Breaks double carbon Breaks double carbon bondsbonds

bullbull Kills by cell lysing or Kills by cell lysing or causing the cell wall tocausing the cell wall tobondsbonds

bullbull Creates OHCreates OHbullbull radicals radicals which break higher carbon which break higher carbon

causing the cell wall to causing the cell wall to rupture rupture

bullbull AttacksAttacks allall bacteriabacteriabondsbondsbullbull Increased temp and pH Increased temp and pH

accelerates Oaccelerates O33

Attacks Attacks allall bacteria bacteria virus cysts and spores virus cysts and spores in varying degreesin varying degreesaccelerates Oaccelerates O33

decomposition to OHdecomposition to OHbullbull

Micro-organism DNA

Capsule AdenineAdenine

Cell wall ThymineThymine

CytosineCytosine

GuanineGuanine

NuclearmaterialCellmembrane

material

Typical Bacterium DNA

Microbial Growth at Various Ozone ConcentrationsConcentrations

Growth likely

Growth possibleGrowth possible

NO GROWTH

0004 0008 0012 0016 0020

Ozone concentration (mgl)Ozone concentration (mgl)

Typical Water Treatment UsageTypical Water Treatment Usage

Application O3 mgl Contact timeUltra Pure Water 005 - 025 sec ndash min

Water bottling 04 ndash 10 5 ndash 10 min

Swimming pools ampspas

01 ndash 075 4 minutes

Potable taste amp odor 15 ndash 50 5 ndash 10 mindisinfection

Microfloculation 10 ndash 30 5 ndash 10 min

Lignin amp tammin 3 0 10 0 10 30 minLignin amp tamminremoval

30 ndash 100 10 ndash 30 min

Municipal wastewater 50 ndash 150+ 15 ndash 30 min

Ozone Water TreatmentOzone Water TreatmentOzone Ozone ndashndash Municipal ApplicationsMunicipal Applications

bullbull Taste and OdorTaste and Odor

bullbull Color RemovalColor Removal

bullbull Disinfection Without Trihalomethanes (THMs)Disinfection Without Trihalomethanes (THMs)

bullbull Improved Filtration Efficiency and FlocculationImproved Filtration Efficiency and Flocculation

bullbull Cryptosporidium DeactivationCryptosporidium Deactivation

bullbull Giardia amp Virus InactivationGiardia amp Virus Inactivation

bullbull Oxidation Oxidation -- Organics Fe amp MnOrganics Fe amp Mn

bullbull Wastewater disinfectionWastewater disinfection

bullbull BOD COD and TOC reductionBOD COD and TOC reduction

Applications of Ozone

Wastewater Treatmentbull Disinfection of Secondary and Tertiary Effluentsbull Color Reductionbull Color Reductionbull TOC Oxidation (Industrial)bull Oxidation of Odor Causing Compoundsbull Oxidation of Endocrine Disruptors (EDCrsquos) and p ( )

Pharmaceutically Active Compounds (PACrsquos)

Applications of Ozone

What are Endocrine Disruptors (EDCrsquos) and What are Endocrine Disruptors (EDCrsquos) and Ph ti ll A ti C d (PACrsquo )Ph ti ll A ti C d (PACrsquo )Pharmaceutically Active Compounds (PACrsquos)Pharmaceutically Active Compounds (PACrsquos)

bullbull EDCrsquosEDCrsquos andand PACrsquosPACrsquos areare NaturallyNaturally andand SyntheticSyntheticdd th tth t ff tff t thth b lb l llcompoundscompounds thatthat maymay affectaffect thethe balancebalance oror normalnormal

functionsfunctions inin animalsanimals andand humanshumans

What can EDCrsquos and PACrsquos doWhat can EDCrsquos and PACrsquos do

bullbull Even in very small concentrations these compounds Even in very small concentrations these compounds y py pcan can disruptdisrupt normal bodily functionsnormal bodily functions

bullbull ManMan--made chemicals can trick the bodies endocrine made chemicals can trick the bodies endocrine system system

Applications of Ozone

Examples of Endocrine Disruptors1000rsquos of compounds that may be Investigated as EDCs ndash Some examples are

bullbull Synthetic HormonesSynthetic Hormonesbullbull Naturally Occurring Estrogens Naturally Occurring Estrogens

Health and Beauty AidsHealth and Beauty Aidsbullbull Health and Beauty AidsHealth and Beauty Aidsbullbull SolventsSolventsbullbull PesticidesPesticidesbullbull SurfactantsSurfactantsbullbull PlasticsPlastics

F i idF i idbullbull FungicidesFungicides

Ozone Water TreatmentOzone Water Treatment

Ozone Ozone -- Industrial ApplicationsIndustrial Applications-- Ultrapure Water for Pharmaceutical ApplicationsUltrapure Water for Pharmaceutical Applications

-- Wastewater disinfection color removalWastewater disinfection color removal

-- Soil and Groundwater Remediation Soil and Groundwater Remediation

-- Cooling Tower Water TreatmentCooling Tower Water Treatment

-- Food ProcessingFood Processing

-- Aquaculture AquariumsAquaculture AquariumsAquaculture AquariumsAquaculture Aquariums

-- Beverage ApplicationsBeverage Applications

P l amp P Bl hiP l amp P Bl hi-- Pulp amp Paper BleachingPulp amp Paper Bleaching

High Purity OzonationHigh Purity Ozonation

Microchip manufacturingMicrochip manufacturing

What are the current issues in large-scale gozone generationg

Experimental Setup

Front view of the two units after the redesign and reworking ofthe gas water and instruments connectionsthe gas water and instruments connections

Experimental Setup

Top view of the twoexperimental unitsexperimental unitsSpectroscope (notshown) is to the left ofthe DBD The units weredifferent with respect todifferent with respect totheir electrodes onehad only the electrodecoated with thedielectric (ldquosingle-dielectric ( single-coatedrdquo) the other onehad the electrode andthe anode coated withthe dielectric (ldquodouble-the dielectric ( double-coatedrdquo)

Basics Generation of OzoneBasics Generation of Ozone

SpectroscopyPlasma

Plasma Absorption SpectroscopyPlasma Absorption Spectroscopy

Infrared Absorption SpectroscopyInfrared Absorption Spectroscopy

IR spectra in pure oxygen (black curve) and at approximately 10wt N2 admixture (red line) N2O5 peaks appear at124 1 d 1 2 11245 cm-1 and at 1725 cm-1

Infrared Absorption SpectroscopyInfrared Absorption Spectroscopy

IR spectra of several methane variations The green curve envelopes all of the methane peaks at 1325 cm-1recorded at smaller methane admixtures Simultaneously the N2O5 peaks disappear as the methane peaks appear

N2O5 FormationN2O5 Formation2 52 5p=2 bara cwt=20degC q=35kWm2 f=1450Hz

45N2O5 AT95

30

35

40

N

2 B

lend

ing

N2O AT95N2O5 IGSN2O IGSN2O5 LGN2O LG

1 5

20

25

nt [p

pmV]

3

wt

05

10

15

NO

x co

nten

005 7 9 11 13 15 17

ozone conc [wt]

Amount of formed N2O5 and N2O as a function of ozone concentration at 3 wt of nitrogen admixture and fori l dvarious electrode arrangements

Plasma Emission SpectroscopyPlasma Emission Spectroscopyp pyp py

Relative Emissions of the Ozonizer plasmaRelative Emissions of the Ozonizer plasma

Region 300- 850 nm from individual (calibrated) regions (smoothed by PeakFit) Single-coated ozone generator Inlet side

3 5E+06

30E+06

35E+06

7 9

20E+06

25E+06

nten

sity

au

2

311 12

10E+06

15E+06

In 4

5

6 8 10

14

15

16

17

00E+00

50E+05

280 300 320 340 360 380 400 420 440 460 480 500 520 540 560 580 600 620 640 660 680 700 720 740 760 780 800 820 840 860

Wavelength nm

1 13

Wavelength nm

Absolute Emission of the DBD PlasmaAbsolute Emission of the DBD Plasma

Intensities in (O2+3 wtN2) plasma

1 20E+04

100E+04

120E+04

600E+03

800E+03

nten

sity

(au

)

200E+03

400E+03

In

O(777)

000E+00200 250 300 350 400 450 500 550 600 650 700 750 800 850

Wavelength nm

Intensities in 3 wtN2+O2 plasmaIntensities in 3 wtN2+O2 plasma

Plasma Chemistry in OzonizersPlasma Chemistry in Ozonizers

Dry Air O2 N2

e - e -

O N2 N O2

O3 NO

O2 N O2

O3

N

3

NO2

O2 O3

NO

N

NO2 O3

N2O

NO3 N

N2O4

NO2

NO2

N2O5

NO3

Primary electron-driven chemical reactions leading to the formation of N2O5 and N2O in a dry air plasma

Plasma emission diagnostics role of N2Plasma emission diagnostics role of N2

Dry Air O2 N2

e - e -

O N2 N O2

O3 NO

O2 N O2

O3

O

N

ON

NO2

O2O3

N

NO N

NO2 O3

N2O

NO3 N

N2O4

NO2

NO2

N2O5

NO3

ONbullWith N2 present ndash less oxygen atoms are formed However the difference in intensity is

very small

Modeling of plasma chemistry incl the NxOy chemistry up to N2O5 for different Oxygen Nitrogen mixtures varying power deposition scenarios

and initial ozone background concentrations (up to 15) previously done

The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation

The role of N2 must be related to its by-products reacting on the surface of the electrodeThe role of N2 must be related to its by-products reacting on the surface of the electrode

The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established

Ab 8 t f O

The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established

Ab 8 t f OAbove 8 wt of O3

1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)

Above 8 wt of O3

1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)case without pampp)

2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of the

case without pampp)

2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of thethem A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface

them A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface

The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation

Three possibilities have to be considered for the oxygen-fedozone generator

Three possibilities have to be considered for the oxygen-fedozone generatorozone generator

bull Excited N2 molecules lead to an increased O2 dissociation in

ozone generator

bull Excited N2 molecules lead to an increased O2 dissociation in2 2such case an increased efficiency is correlated to the N2admixture

2 2such case an increased efficiency is correlated to the N2admixture

bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial

bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial

bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2

bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2g p g 3 pp y 2g p g 3 pp y 2

Effect of methane on ozone efficiency and specific powerEffect of methane on ozone efficiency and specific power

Effect of Methane on Ozone Content in Outlet Gas and on Specific Power Pure O2

13 12

10

11

12

t 8

10

8

9

10

ne c

onte

nt w

t

6

8

ecifi

c po

wer

kW

hlb

5

6

7

Ozo

n

2

4 Spe

400E+00 20E+03 40E+03 60E+03 80E+03 10E+04 12E+04

Methane in feedgas ppm

0

Ozone content in the outlet gas Specif ic pow er of the ozone generatorg p p g

Effects of N2 and CH4Effects of N2 and CH4

Pi t f h t lli N O t tPicture of an amorphous-crystalline N2O5 structurecaptured at the Orlando Skylake water plant in 2006

Plasma Chemistry with CH4 Impurities

OxygenO2 N2

e - e -

CHO N2

NO2

O NO

O2 N O2 O3

NOH

CH4e-

O3 NO

NO2

O2O3NO N

NO2 O

NO2

NO2

N2ONO3

N

O3

NO2

NO

HNO3

N2O4

N2O5

NO2

NO3

N2O5

Effect of methane on the electrode surfaces

a) b)

Inlet Outlet Outlet

) d)

I l t I l t

c) d)

Electrode of the ozone generator afterseveral hours in CH8O2 and up to 2 wt of methane (a b c)

Inlet Inlet

three hours in CH8O2+traces of N2 and up to 1 wt of methane (d) Visible change of discharge character at about 13 length of electrode (a d)

Kinetics of CHx Conversion without N2

conversion by collisions

O2 + CHx 12wt O3 + CO2 +H2O

deposition vaporizationby sputtering

ibl b l 1000 CHreversible process below 1000ppm CH4

Effect of water on electrode surface with N2

Inlet

OutletOutlet

Electrode of the ozone generator after several hours in H OO N

Inlet

Electrode of the ozone generator after several hours in H2OO2N2

Effect of water on electrode surface

Long term effect (800 hrs) of H2OO2N2

Kinetics of CHx Conversion with N2

conversion by collisionsHNO3 formation

O2 + N2 +CHx 12wtO2 + CO2 +H2O + HNO3

deposition vaporizationby sputtering

H2O + HNO3

by sputtering

irreversible process above a N2 threshold () ltlt 1000ppm N2

sticky deposit

p 2 ( ) pp 2 any CH4 concentration (60ppm)

Plasma Chemistry with CH4 ImpuritiesPlasma Chemistry with CH4 Impurities4

bull Formation of NO and NO2 depends on O3 N2 and gas temperature Conclusion N2 admixture is the key factor

SummarySummaryyyThe mechanisms of formed NOx by-products follows the sameThe mechanisms of formed NOx by-products follows the sameprinciples as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentration

principles as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentrationozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)

ozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)g p ( g p )

The conversion of methane to OH and H2O is found to depend on

g p ( g p )

The conversion of methane to OH and H2O is found to depend ondissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)

dissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)discharge gap)discharge gap)

How do you optimize an ozone generatorg

Scientific ApproachScientific ApproachTheoretical Experimental

pppp

c [wt]

f [Hz]

c [wt]

f [Hz]

[kW]UUUβ1

1Cf4αPn

1iiminpeakimin

iiD

q [kWm2]q [kWm2]

150

180

][V]voltagepeakUpeak

[]cylinder perslicesofamountnsliceii

whereth

09 00

30

60

90

120

effic

ienc

y [

][0tdj t bl[F]sliceisdielectricofecapacitancC

[Hz]frequencyf[V]sliceivoltageminimumiUmin

thiD

th

10

28

46

64

82

39

107

176

244 power density

[kWm2]

ozone conc [wt][]CCβ

][0parameteradjustableα

iDiGi

Impact of Power Inductionp

350

400

wer

200

250

300

App

lied

Pow

Arr C 2Arr D +0

Arr E +45Arr F +7

Arr G +3

5 0

100

150

Frac

tion

of

1 2 3 4

ReferenceArr B unstable

Arr C -2

00

50

4Position (1inlet 4outlet)

Experimental Test Rigp g

Experimental Test Rigp g

Outer grounded electrode (left picture) and the dielectric covered inner electrodes (right) d e ect c cove ed e e ect odes ( g t)

Reference (Traditional) Arrangement

Inlet OutletGas flow direction

Optimized Arrangement

Inlet OutletGas flow direction

Intelligent Gap System (IGS)g p y ( )

Molecular Oxygen (O2) Ozone (O3)

O2 O3

yg ( 2) ( 3)

Particle Size SynthesisParticle Size SynthesisByBy--Products Cluster FormationProducts Cluster Formationyy

high diffusion and deposition to surfaces

low diffusion rate good transport

high sedimentation on the structurehigh sedimentation on the structure

Degreacutemont Technologies ndash OzoniaIntelligent Gap SystemIntelligent Gap System

G Vezzuacute JL Lopez A Freilich and K Becker Optimizationof Large-Scale Ozone Generators IEEE Transactions onPlasma Science Vol 37 No 6 p 890-896 (2009)

ConclusionsConclusionsConclusionsConclusionsFundamentals of ozone synthesis in a DBD plasmay p

ndash Highly filamented DBD discharges are best-suitedfor the production of ozone concentrations in therange of 6 to 14 wtrange of 6 to 14 wt

ndash The preferred characteristic of the microdischargesare Townsend-like at reduced electric fields Enaround 190 Townsend

ndash Detrimental side-effects induced by by-productscan be avoided by a proper design of the electrodecan be avoided by a proper design of the electrodearrangement The phenomenon is related to thediffusion rates of formed by-product clusters

ConclusionsConclusionsConclusionsConclusionsBenefits from DBD microplasma tailoring

ndash Reduced power consumption of up to 10 improvement

ndash Increased ozone concentrations of up to 14 now achievable

ndash Improved neutralization and conditioning of detrimental by-products

ndash Reduced system capital and operational cost

New technologies to improve ozone p

generatorg

HV Pulsed Power SwitchingHV Pulsed Power Switching

Microchannel Generation of Ozone

Channel ArrayChannel Array

Microchannel

330 microm 230 microm

Some Cap-DBD Devices Operating in Air

Increase of 60 of

Spacing 225 μmof 60 of plasma

No space

Cap‐DBD ozone generation

bull Ozone concentration is evaluated via Eco S d l UV 100 O A l (0 01Sensors model UV-100 Ozone Analyzer (001 ndash 900 ppm wiht an accuracy of plusmn2)

bull Three reactors 6 tubings 6rdquo with spacings of 0 μm 225 μm and 500 μm running at 3 kV μ μ μ g

SpacingOzone Concentration

3 kV rms 4 kV rms3 kV rms 4 kV rms

0 μm 660 ppm

225 μm 550 ppm

For a device of such small scale these ozone levels are promising

500 μm 380 ppm

J Mahoney W Zhu VS Johnson KH Becker and JL Lopez Electrical and optical emissionmeasurements of a capillary dielectric barrier discharge European Physics Journal D Vol 60 441-447(2010)

QuestionsQuestions

Thank YouFor more informationProf Jose L Lopez PhD

Thank YouFor more informationDepartment of Physics

Telephone (973) 761-9057Email joselopez1shuedu

Website wwwshueduacademicsartsciphysicsWebsite wwwshueduacademicsartsciphysics

Page 51: Dielectric Barrier Discharge (DBD) & Progress in Large ...bonitz/si12/talks/august_8/lopez_si12.pdf · Dielectric Barrier Discharge (DBD) & Progress in Large-Scale Ozone Generation

Ozone Water Treatment

B bbl Diff iB bbl Diff iBubble DiffusionBubble Diffusion

Easy to use

Low energy usage Low energy usage

Mass transfer efficiencies to gt 90

Ozone Process Flow DiagramOzone Process Flow DiagramVent to

Atmosphere

O OOxygen

Off-Gas Blower

Ozone Destruct Unit

10 12

O3O2

LOX

10-12 O3

Ozone Generators

Ozone Contact ChamberLOX T k Generators Chamber

VaporizersLOX Tank

Municipal Ozone Installations

Ozonia Installations Ozone Plant Size [lbday] Start-Up DateKey Ozonia Installations (Partial List)

Los Angeles CA 10000 1986Fairfax VA ndash Corbalis 9000 2003MWD CA ndash Mills 9 000 2003

Ozonia Installations Ozone Plant Size [lbday] Start Up Date

MWD CA Mills 9000 2003Fairfax Co VA ndash Griffith 9000 2004MWD CA ndash Jensen 18750 2005Indianapolis IN ndash Belmont AWT 12000 2007I di li IN 12 000 2007Indianapolis IN ndash Southport AWT 12000 2007MWD CA ndash Diemer 13400 2008MWD CA ndash Weymouth 13400 2009

Ozonia North America - Potable Water SummaryTotal Number of Installations 90Total Installed Production gt 265000 lbsdayTotal Installed Production 265000 lbsday

Revision -B

Ozone Water TreatmentOzone Water Treatment

MWD Mills WTP - California

3 3 000 lbsda of o one3 3 000 lbsda of o one3 x 3000 lbsday of ozone3 x 3000 lbsday of ozone

Ozone Water TreatmentOzone Water TreatmentOzone Ozone -- How it worksHow it works

OxidantOxidant DisinfectantDisinfectant

bullbull Breaks double carbon Breaks double carbon bondsbonds

bullbull Kills by cell lysing or Kills by cell lysing or causing the cell wall tocausing the cell wall tobondsbonds

bullbull Creates OHCreates OHbullbull radicals radicals which break higher carbon which break higher carbon

causing the cell wall to causing the cell wall to rupture rupture

bullbull AttacksAttacks allall bacteriabacteriabondsbondsbullbull Increased temp and pH Increased temp and pH

accelerates Oaccelerates O33

Attacks Attacks allall bacteria bacteria virus cysts and spores virus cysts and spores in varying degreesin varying degreesaccelerates Oaccelerates O33

decomposition to OHdecomposition to OHbullbull

Micro-organism DNA

Capsule AdenineAdenine

Cell wall ThymineThymine

CytosineCytosine

GuanineGuanine

NuclearmaterialCellmembrane

material

Typical Bacterium DNA

Microbial Growth at Various Ozone ConcentrationsConcentrations

Growth likely

Growth possibleGrowth possible

NO GROWTH

0004 0008 0012 0016 0020

Ozone concentration (mgl)Ozone concentration (mgl)

Typical Water Treatment UsageTypical Water Treatment Usage

Application O3 mgl Contact timeUltra Pure Water 005 - 025 sec ndash min

Water bottling 04 ndash 10 5 ndash 10 min

Swimming pools ampspas

01 ndash 075 4 minutes

Potable taste amp odor 15 ndash 50 5 ndash 10 mindisinfection

Microfloculation 10 ndash 30 5 ndash 10 min

Lignin amp tammin 3 0 10 0 10 30 minLignin amp tamminremoval

30 ndash 100 10 ndash 30 min

Municipal wastewater 50 ndash 150+ 15 ndash 30 min

Ozone Water TreatmentOzone Water TreatmentOzone Ozone ndashndash Municipal ApplicationsMunicipal Applications

bullbull Taste and OdorTaste and Odor

bullbull Color RemovalColor Removal

bullbull Disinfection Without Trihalomethanes (THMs)Disinfection Without Trihalomethanes (THMs)

bullbull Improved Filtration Efficiency and FlocculationImproved Filtration Efficiency and Flocculation

bullbull Cryptosporidium DeactivationCryptosporidium Deactivation

bullbull Giardia amp Virus InactivationGiardia amp Virus Inactivation

bullbull Oxidation Oxidation -- Organics Fe amp MnOrganics Fe amp Mn

bullbull Wastewater disinfectionWastewater disinfection

bullbull BOD COD and TOC reductionBOD COD and TOC reduction

Applications of Ozone

Wastewater Treatmentbull Disinfection of Secondary and Tertiary Effluentsbull Color Reductionbull Color Reductionbull TOC Oxidation (Industrial)bull Oxidation of Odor Causing Compoundsbull Oxidation of Endocrine Disruptors (EDCrsquos) and p ( )

Pharmaceutically Active Compounds (PACrsquos)

Applications of Ozone

What are Endocrine Disruptors (EDCrsquos) and What are Endocrine Disruptors (EDCrsquos) and Ph ti ll A ti C d (PACrsquo )Ph ti ll A ti C d (PACrsquo )Pharmaceutically Active Compounds (PACrsquos)Pharmaceutically Active Compounds (PACrsquos)

bullbull EDCrsquosEDCrsquos andand PACrsquosPACrsquos areare NaturallyNaturally andand SyntheticSyntheticdd th tth t ff tff t thth b lb l llcompoundscompounds thatthat maymay affectaffect thethe balancebalance oror normalnormal

functionsfunctions inin animalsanimals andand humanshumans

What can EDCrsquos and PACrsquos doWhat can EDCrsquos and PACrsquos do

bullbull Even in very small concentrations these compounds Even in very small concentrations these compounds y py pcan can disruptdisrupt normal bodily functionsnormal bodily functions

bullbull ManMan--made chemicals can trick the bodies endocrine made chemicals can trick the bodies endocrine system system

Applications of Ozone

Examples of Endocrine Disruptors1000rsquos of compounds that may be Investigated as EDCs ndash Some examples are

bullbull Synthetic HormonesSynthetic Hormonesbullbull Naturally Occurring Estrogens Naturally Occurring Estrogens

Health and Beauty AidsHealth and Beauty Aidsbullbull Health and Beauty AidsHealth and Beauty Aidsbullbull SolventsSolventsbullbull PesticidesPesticidesbullbull SurfactantsSurfactantsbullbull PlasticsPlastics

F i idF i idbullbull FungicidesFungicides

Ozone Water TreatmentOzone Water Treatment

Ozone Ozone -- Industrial ApplicationsIndustrial Applications-- Ultrapure Water for Pharmaceutical ApplicationsUltrapure Water for Pharmaceutical Applications

-- Wastewater disinfection color removalWastewater disinfection color removal

-- Soil and Groundwater Remediation Soil and Groundwater Remediation

-- Cooling Tower Water TreatmentCooling Tower Water Treatment

-- Food ProcessingFood Processing

-- Aquaculture AquariumsAquaculture AquariumsAquaculture AquariumsAquaculture Aquariums

-- Beverage ApplicationsBeverage Applications

P l amp P Bl hiP l amp P Bl hi-- Pulp amp Paper BleachingPulp amp Paper Bleaching

High Purity OzonationHigh Purity Ozonation

Microchip manufacturingMicrochip manufacturing

What are the current issues in large-scale gozone generationg

Experimental Setup

Front view of the two units after the redesign and reworking ofthe gas water and instruments connectionsthe gas water and instruments connections

Experimental Setup

Top view of the twoexperimental unitsexperimental unitsSpectroscope (notshown) is to the left ofthe DBD The units weredifferent with respect todifferent with respect totheir electrodes onehad only the electrodecoated with thedielectric (ldquosingle-dielectric ( single-coatedrdquo) the other onehad the electrode andthe anode coated withthe dielectric (ldquodouble-the dielectric ( double-coatedrdquo)

Basics Generation of OzoneBasics Generation of Ozone

SpectroscopyPlasma

Plasma Absorption SpectroscopyPlasma Absorption Spectroscopy

Infrared Absorption SpectroscopyInfrared Absorption Spectroscopy

IR spectra in pure oxygen (black curve) and at approximately 10wt N2 admixture (red line) N2O5 peaks appear at124 1 d 1 2 11245 cm-1 and at 1725 cm-1

Infrared Absorption SpectroscopyInfrared Absorption Spectroscopy

IR spectra of several methane variations The green curve envelopes all of the methane peaks at 1325 cm-1recorded at smaller methane admixtures Simultaneously the N2O5 peaks disappear as the methane peaks appear

N2O5 FormationN2O5 Formation2 52 5p=2 bara cwt=20degC q=35kWm2 f=1450Hz

45N2O5 AT95

30

35

40

N

2 B

lend

ing

N2O AT95N2O5 IGSN2O IGSN2O5 LGN2O LG

1 5

20

25

nt [p

pmV]

3

wt

05

10

15

NO

x co

nten

005 7 9 11 13 15 17

ozone conc [wt]

Amount of formed N2O5 and N2O as a function of ozone concentration at 3 wt of nitrogen admixture and fori l dvarious electrode arrangements

Plasma Emission SpectroscopyPlasma Emission Spectroscopyp pyp py

Relative Emissions of the Ozonizer plasmaRelative Emissions of the Ozonizer plasma

Region 300- 850 nm from individual (calibrated) regions (smoothed by PeakFit) Single-coated ozone generator Inlet side

3 5E+06

30E+06

35E+06

7 9

20E+06

25E+06

nten

sity

au

2

311 12

10E+06

15E+06

In 4

5

6 8 10

14

15

16

17

00E+00

50E+05

280 300 320 340 360 380 400 420 440 460 480 500 520 540 560 580 600 620 640 660 680 700 720 740 760 780 800 820 840 860

Wavelength nm

1 13

Wavelength nm

Absolute Emission of the DBD PlasmaAbsolute Emission of the DBD Plasma

Intensities in (O2+3 wtN2) plasma

1 20E+04

100E+04

120E+04

600E+03

800E+03

nten

sity

(au

)

200E+03

400E+03

In

O(777)

000E+00200 250 300 350 400 450 500 550 600 650 700 750 800 850

Wavelength nm

Intensities in 3 wtN2+O2 plasmaIntensities in 3 wtN2+O2 plasma

Plasma Chemistry in OzonizersPlasma Chemistry in Ozonizers

Dry Air O2 N2

e - e -

O N2 N O2

O3 NO

O2 N O2

O3

N

3

NO2

O2 O3

NO

N

NO2 O3

N2O

NO3 N

N2O4

NO2

NO2

N2O5

NO3

Primary electron-driven chemical reactions leading to the formation of N2O5 and N2O in a dry air plasma

Plasma emission diagnostics role of N2Plasma emission diagnostics role of N2

Dry Air O2 N2

e - e -

O N2 N O2

O3 NO

O2 N O2

O3

O

N

ON

NO2

O2O3

N

NO N

NO2 O3

N2O

NO3 N

N2O4

NO2

NO2

N2O5

NO3

ONbullWith N2 present ndash less oxygen atoms are formed However the difference in intensity is

very small

Modeling of plasma chemistry incl the NxOy chemistry up to N2O5 for different Oxygen Nitrogen mixtures varying power deposition scenarios

and initial ozone background concentrations (up to 15) previously done

The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation

The role of N2 must be related to its by-products reacting on the surface of the electrodeThe role of N2 must be related to its by-products reacting on the surface of the electrode

The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established

Ab 8 t f O

The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established

Ab 8 t f OAbove 8 wt of O3

1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)

Above 8 wt of O3

1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)case without pampp)

2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of the

case without pampp)

2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of thethem A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface

them A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface

The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation

Three possibilities have to be considered for the oxygen-fedozone generator

Three possibilities have to be considered for the oxygen-fedozone generatorozone generator

bull Excited N2 molecules lead to an increased O2 dissociation in

ozone generator

bull Excited N2 molecules lead to an increased O2 dissociation in2 2such case an increased efficiency is correlated to the N2admixture

2 2such case an increased efficiency is correlated to the N2admixture

bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial

bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial

bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2

bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2g p g 3 pp y 2g p g 3 pp y 2

Effect of methane on ozone efficiency and specific powerEffect of methane on ozone efficiency and specific power

Effect of Methane on Ozone Content in Outlet Gas and on Specific Power Pure O2

13 12

10

11

12

t 8

10

8

9

10

ne c

onte

nt w

t

6

8

ecifi

c po

wer

kW

hlb

5

6

7

Ozo

n

2

4 Spe

400E+00 20E+03 40E+03 60E+03 80E+03 10E+04 12E+04

Methane in feedgas ppm

0

Ozone content in the outlet gas Specif ic pow er of the ozone generatorg p p g

Effects of N2 and CH4Effects of N2 and CH4

Pi t f h t lli N O t tPicture of an amorphous-crystalline N2O5 structurecaptured at the Orlando Skylake water plant in 2006

Plasma Chemistry with CH4 Impurities

OxygenO2 N2

e - e -

CHO N2

NO2

O NO

O2 N O2 O3

NOH

CH4e-

O3 NO

NO2

O2O3NO N

NO2 O

NO2

NO2

N2ONO3

N

O3

NO2

NO

HNO3

N2O4

N2O5

NO2

NO3

N2O5

Effect of methane on the electrode surfaces

a) b)

Inlet Outlet Outlet

) d)

I l t I l t

c) d)

Electrode of the ozone generator afterseveral hours in CH8O2 and up to 2 wt of methane (a b c)

Inlet Inlet

three hours in CH8O2+traces of N2 and up to 1 wt of methane (d) Visible change of discharge character at about 13 length of electrode (a d)

Kinetics of CHx Conversion without N2

conversion by collisions

O2 + CHx 12wt O3 + CO2 +H2O

deposition vaporizationby sputtering

ibl b l 1000 CHreversible process below 1000ppm CH4

Effect of water on electrode surface with N2

Inlet

OutletOutlet

Electrode of the ozone generator after several hours in H OO N

Inlet

Electrode of the ozone generator after several hours in H2OO2N2

Effect of water on electrode surface

Long term effect (800 hrs) of H2OO2N2

Kinetics of CHx Conversion with N2

conversion by collisionsHNO3 formation

O2 + N2 +CHx 12wtO2 + CO2 +H2O + HNO3

deposition vaporizationby sputtering

H2O + HNO3

by sputtering

irreversible process above a N2 threshold () ltlt 1000ppm N2

sticky deposit

p 2 ( ) pp 2 any CH4 concentration (60ppm)

Plasma Chemistry with CH4 ImpuritiesPlasma Chemistry with CH4 Impurities4

bull Formation of NO and NO2 depends on O3 N2 and gas temperature Conclusion N2 admixture is the key factor

SummarySummaryyyThe mechanisms of formed NOx by-products follows the sameThe mechanisms of formed NOx by-products follows the sameprinciples as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentration

principles as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentrationozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)

ozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)g p ( g p )

The conversion of methane to OH and H2O is found to depend on

g p ( g p )

The conversion of methane to OH and H2O is found to depend ondissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)

dissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)discharge gap)discharge gap)

How do you optimize an ozone generatorg

Scientific ApproachScientific ApproachTheoretical Experimental

pppp

c [wt]

f [Hz]

c [wt]

f [Hz]

[kW]UUUβ1

1Cf4αPn

1iiminpeakimin

iiD

q [kWm2]q [kWm2]

150

180

][V]voltagepeakUpeak

[]cylinder perslicesofamountnsliceii

whereth

09 00

30

60

90

120

effic

ienc

y [

][0tdj t bl[F]sliceisdielectricofecapacitancC

[Hz]frequencyf[V]sliceivoltageminimumiUmin

thiD

th

10

28

46

64

82

39

107

176

244 power density

[kWm2]

ozone conc [wt][]CCβ

][0parameteradjustableα

iDiGi

Impact of Power Inductionp

350

400

wer

200

250

300

App

lied

Pow

Arr C 2Arr D +0

Arr E +45Arr F +7

Arr G +3

5 0

100

150

Frac

tion

of

1 2 3 4

ReferenceArr B unstable

Arr C -2

00

50

4Position (1inlet 4outlet)

Experimental Test Rigp g

Experimental Test Rigp g

Outer grounded electrode (left picture) and the dielectric covered inner electrodes (right) d e ect c cove ed e e ect odes ( g t)

Reference (Traditional) Arrangement

Inlet OutletGas flow direction

Optimized Arrangement

Inlet OutletGas flow direction

Intelligent Gap System (IGS)g p y ( )

Molecular Oxygen (O2) Ozone (O3)

O2 O3

yg ( 2) ( 3)

Particle Size SynthesisParticle Size SynthesisByBy--Products Cluster FormationProducts Cluster Formationyy

high diffusion and deposition to surfaces

low diffusion rate good transport

high sedimentation on the structurehigh sedimentation on the structure

Degreacutemont Technologies ndash OzoniaIntelligent Gap SystemIntelligent Gap System

G Vezzuacute JL Lopez A Freilich and K Becker Optimizationof Large-Scale Ozone Generators IEEE Transactions onPlasma Science Vol 37 No 6 p 890-896 (2009)

ConclusionsConclusionsConclusionsConclusionsFundamentals of ozone synthesis in a DBD plasmay p

ndash Highly filamented DBD discharges are best-suitedfor the production of ozone concentrations in therange of 6 to 14 wtrange of 6 to 14 wt

ndash The preferred characteristic of the microdischargesare Townsend-like at reduced electric fields Enaround 190 Townsend

ndash Detrimental side-effects induced by by-productscan be avoided by a proper design of the electrodecan be avoided by a proper design of the electrodearrangement The phenomenon is related to thediffusion rates of formed by-product clusters

ConclusionsConclusionsConclusionsConclusionsBenefits from DBD microplasma tailoring

ndash Reduced power consumption of up to 10 improvement

ndash Increased ozone concentrations of up to 14 now achievable

ndash Improved neutralization and conditioning of detrimental by-products

ndash Reduced system capital and operational cost

New technologies to improve ozone p

generatorg

HV Pulsed Power SwitchingHV Pulsed Power Switching

Microchannel Generation of Ozone

Channel ArrayChannel Array

Microchannel

330 microm 230 microm

Some Cap-DBD Devices Operating in Air

Increase of 60 of

Spacing 225 μmof 60 of plasma

No space

Cap‐DBD ozone generation

bull Ozone concentration is evaluated via Eco S d l UV 100 O A l (0 01Sensors model UV-100 Ozone Analyzer (001 ndash 900 ppm wiht an accuracy of plusmn2)

bull Three reactors 6 tubings 6rdquo with spacings of 0 μm 225 μm and 500 μm running at 3 kV μ μ μ g

SpacingOzone Concentration

3 kV rms 4 kV rms3 kV rms 4 kV rms

0 μm 660 ppm

225 μm 550 ppm

For a device of such small scale these ozone levels are promising

500 μm 380 ppm

J Mahoney W Zhu VS Johnson KH Becker and JL Lopez Electrical and optical emissionmeasurements of a capillary dielectric barrier discharge European Physics Journal D Vol 60 441-447(2010)

QuestionsQuestions

Thank YouFor more informationProf Jose L Lopez PhD

Thank YouFor more informationDepartment of Physics

Telephone (973) 761-9057Email joselopez1shuedu

Website wwwshueduacademicsartsciphysicsWebsite wwwshueduacademicsartsciphysics

Page 52: Dielectric Barrier Discharge (DBD) & Progress in Large ...bonitz/si12/talks/august_8/lopez_si12.pdf · Dielectric Barrier Discharge (DBD) & Progress in Large-Scale Ozone Generation

Ozone Process Flow DiagramOzone Process Flow DiagramVent to

Atmosphere

O OOxygen

Off-Gas Blower

Ozone Destruct Unit

10 12

O3O2

LOX

10-12 O3

Ozone Generators

Ozone Contact ChamberLOX T k Generators Chamber

VaporizersLOX Tank

Municipal Ozone Installations

Ozonia Installations Ozone Plant Size [lbday] Start-Up DateKey Ozonia Installations (Partial List)

Los Angeles CA 10000 1986Fairfax VA ndash Corbalis 9000 2003MWD CA ndash Mills 9 000 2003

Ozonia Installations Ozone Plant Size [lbday] Start Up Date

MWD CA Mills 9000 2003Fairfax Co VA ndash Griffith 9000 2004MWD CA ndash Jensen 18750 2005Indianapolis IN ndash Belmont AWT 12000 2007I di li IN 12 000 2007Indianapolis IN ndash Southport AWT 12000 2007MWD CA ndash Diemer 13400 2008MWD CA ndash Weymouth 13400 2009

Ozonia North America - Potable Water SummaryTotal Number of Installations 90Total Installed Production gt 265000 lbsdayTotal Installed Production 265000 lbsday

Revision -B

Ozone Water TreatmentOzone Water Treatment

MWD Mills WTP - California

3 3 000 lbsda of o one3 3 000 lbsda of o one3 x 3000 lbsday of ozone3 x 3000 lbsday of ozone

Ozone Water TreatmentOzone Water TreatmentOzone Ozone -- How it worksHow it works

OxidantOxidant DisinfectantDisinfectant

bullbull Breaks double carbon Breaks double carbon bondsbonds

bullbull Kills by cell lysing or Kills by cell lysing or causing the cell wall tocausing the cell wall tobondsbonds

bullbull Creates OHCreates OHbullbull radicals radicals which break higher carbon which break higher carbon

causing the cell wall to causing the cell wall to rupture rupture

bullbull AttacksAttacks allall bacteriabacteriabondsbondsbullbull Increased temp and pH Increased temp and pH

accelerates Oaccelerates O33

Attacks Attacks allall bacteria bacteria virus cysts and spores virus cysts and spores in varying degreesin varying degreesaccelerates Oaccelerates O33

decomposition to OHdecomposition to OHbullbull

Micro-organism DNA

Capsule AdenineAdenine

Cell wall ThymineThymine

CytosineCytosine

GuanineGuanine

NuclearmaterialCellmembrane

material

Typical Bacterium DNA

Microbial Growth at Various Ozone ConcentrationsConcentrations

Growth likely

Growth possibleGrowth possible

NO GROWTH

0004 0008 0012 0016 0020

Ozone concentration (mgl)Ozone concentration (mgl)

Typical Water Treatment UsageTypical Water Treatment Usage

Application O3 mgl Contact timeUltra Pure Water 005 - 025 sec ndash min

Water bottling 04 ndash 10 5 ndash 10 min

Swimming pools ampspas

01 ndash 075 4 minutes

Potable taste amp odor 15 ndash 50 5 ndash 10 mindisinfection

Microfloculation 10 ndash 30 5 ndash 10 min

Lignin amp tammin 3 0 10 0 10 30 minLignin amp tamminremoval

30 ndash 100 10 ndash 30 min

Municipal wastewater 50 ndash 150+ 15 ndash 30 min

Ozone Water TreatmentOzone Water TreatmentOzone Ozone ndashndash Municipal ApplicationsMunicipal Applications

bullbull Taste and OdorTaste and Odor

bullbull Color RemovalColor Removal

bullbull Disinfection Without Trihalomethanes (THMs)Disinfection Without Trihalomethanes (THMs)

bullbull Improved Filtration Efficiency and FlocculationImproved Filtration Efficiency and Flocculation

bullbull Cryptosporidium DeactivationCryptosporidium Deactivation

bullbull Giardia amp Virus InactivationGiardia amp Virus Inactivation

bullbull Oxidation Oxidation -- Organics Fe amp MnOrganics Fe amp Mn

bullbull Wastewater disinfectionWastewater disinfection

bullbull BOD COD and TOC reductionBOD COD and TOC reduction

Applications of Ozone

Wastewater Treatmentbull Disinfection of Secondary and Tertiary Effluentsbull Color Reductionbull Color Reductionbull TOC Oxidation (Industrial)bull Oxidation of Odor Causing Compoundsbull Oxidation of Endocrine Disruptors (EDCrsquos) and p ( )

Pharmaceutically Active Compounds (PACrsquos)

Applications of Ozone

What are Endocrine Disruptors (EDCrsquos) and What are Endocrine Disruptors (EDCrsquos) and Ph ti ll A ti C d (PACrsquo )Ph ti ll A ti C d (PACrsquo )Pharmaceutically Active Compounds (PACrsquos)Pharmaceutically Active Compounds (PACrsquos)

bullbull EDCrsquosEDCrsquos andand PACrsquosPACrsquos areare NaturallyNaturally andand SyntheticSyntheticdd th tth t ff tff t thth b lb l llcompoundscompounds thatthat maymay affectaffect thethe balancebalance oror normalnormal

functionsfunctions inin animalsanimals andand humanshumans

What can EDCrsquos and PACrsquos doWhat can EDCrsquos and PACrsquos do

bullbull Even in very small concentrations these compounds Even in very small concentrations these compounds y py pcan can disruptdisrupt normal bodily functionsnormal bodily functions

bullbull ManMan--made chemicals can trick the bodies endocrine made chemicals can trick the bodies endocrine system system

Applications of Ozone

Examples of Endocrine Disruptors1000rsquos of compounds that may be Investigated as EDCs ndash Some examples are

bullbull Synthetic HormonesSynthetic Hormonesbullbull Naturally Occurring Estrogens Naturally Occurring Estrogens

Health and Beauty AidsHealth and Beauty Aidsbullbull Health and Beauty AidsHealth and Beauty Aidsbullbull SolventsSolventsbullbull PesticidesPesticidesbullbull SurfactantsSurfactantsbullbull PlasticsPlastics

F i idF i idbullbull FungicidesFungicides

Ozone Water TreatmentOzone Water Treatment

Ozone Ozone -- Industrial ApplicationsIndustrial Applications-- Ultrapure Water for Pharmaceutical ApplicationsUltrapure Water for Pharmaceutical Applications

-- Wastewater disinfection color removalWastewater disinfection color removal

-- Soil and Groundwater Remediation Soil and Groundwater Remediation

-- Cooling Tower Water TreatmentCooling Tower Water Treatment

-- Food ProcessingFood Processing

-- Aquaculture AquariumsAquaculture AquariumsAquaculture AquariumsAquaculture Aquariums

-- Beverage ApplicationsBeverage Applications

P l amp P Bl hiP l amp P Bl hi-- Pulp amp Paper BleachingPulp amp Paper Bleaching

High Purity OzonationHigh Purity Ozonation

Microchip manufacturingMicrochip manufacturing

What are the current issues in large-scale gozone generationg

Experimental Setup

Front view of the two units after the redesign and reworking ofthe gas water and instruments connectionsthe gas water and instruments connections

Experimental Setup

Top view of the twoexperimental unitsexperimental unitsSpectroscope (notshown) is to the left ofthe DBD The units weredifferent with respect todifferent with respect totheir electrodes onehad only the electrodecoated with thedielectric (ldquosingle-dielectric ( single-coatedrdquo) the other onehad the electrode andthe anode coated withthe dielectric (ldquodouble-the dielectric ( double-coatedrdquo)

Basics Generation of OzoneBasics Generation of Ozone

SpectroscopyPlasma

Plasma Absorption SpectroscopyPlasma Absorption Spectroscopy

Infrared Absorption SpectroscopyInfrared Absorption Spectroscopy

IR spectra in pure oxygen (black curve) and at approximately 10wt N2 admixture (red line) N2O5 peaks appear at124 1 d 1 2 11245 cm-1 and at 1725 cm-1

Infrared Absorption SpectroscopyInfrared Absorption Spectroscopy

IR spectra of several methane variations The green curve envelopes all of the methane peaks at 1325 cm-1recorded at smaller methane admixtures Simultaneously the N2O5 peaks disappear as the methane peaks appear

N2O5 FormationN2O5 Formation2 52 5p=2 bara cwt=20degC q=35kWm2 f=1450Hz

45N2O5 AT95

30

35

40

N

2 B

lend

ing

N2O AT95N2O5 IGSN2O IGSN2O5 LGN2O LG

1 5

20

25

nt [p

pmV]

3

wt

05

10

15

NO

x co

nten

005 7 9 11 13 15 17

ozone conc [wt]

Amount of formed N2O5 and N2O as a function of ozone concentration at 3 wt of nitrogen admixture and fori l dvarious electrode arrangements

Plasma Emission SpectroscopyPlasma Emission Spectroscopyp pyp py

Relative Emissions of the Ozonizer plasmaRelative Emissions of the Ozonizer plasma

Region 300- 850 nm from individual (calibrated) regions (smoothed by PeakFit) Single-coated ozone generator Inlet side

3 5E+06

30E+06

35E+06

7 9

20E+06

25E+06

nten

sity

au

2

311 12

10E+06

15E+06

In 4

5

6 8 10

14

15

16

17

00E+00

50E+05

280 300 320 340 360 380 400 420 440 460 480 500 520 540 560 580 600 620 640 660 680 700 720 740 760 780 800 820 840 860

Wavelength nm

1 13

Wavelength nm

Absolute Emission of the DBD PlasmaAbsolute Emission of the DBD Plasma

Intensities in (O2+3 wtN2) plasma

1 20E+04

100E+04

120E+04

600E+03

800E+03

nten

sity

(au

)

200E+03

400E+03

In

O(777)

000E+00200 250 300 350 400 450 500 550 600 650 700 750 800 850

Wavelength nm

Intensities in 3 wtN2+O2 plasmaIntensities in 3 wtN2+O2 plasma

Plasma Chemistry in OzonizersPlasma Chemistry in Ozonizers

Dry Air O2 N2

e - e -

O N2 N O2

O3 NO

O2 N O2

O3

N

3

NO2

O2 O3

NO

N

NO2 O3

N2O

NO3 N

N2O4

NO2

NO2

N2O5

NO3

Primary electron-driven chemical reactions leading to the formation of N2O5 and N2O in a dry air plasma

Plasma emission diagnostics role of N2Plasma emission diagnostics role of N2

Dry Air O2 N2

e - e -

O N2 N O2

O3 NO

O2 N O2

O3

O

N

ON

NO2

O2O3

N

NO N

NO2 O3

N2O

NO3 N

N2O4

NO2

NO2

N2O5

NO3

ONbullWith N2 present ndash less oxygen atoms are formed However the difference in intensity is

very small

Modeling of plasma chemistry incl the NxOy chemistry up to N2O5 for different Oxygen Nitrogen mixtures varying power deposition scenarios

and initial ozone background concentrations (up to 15) previously done

The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation

The role of N2 must be related to its by-products reacting on the surface of the electrodeThe role of N2 must be related to its by-products reacting on the surface of the electrode

The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established

Ab 8 t f O

The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established

Ab 8 t f OAbove 8 wt of O3

1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)

Above 8 wt of O3

1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)case without pampp)

2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of the

case without pampp)

2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of thethem A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface

them A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface

The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation

Three possibilities have to be considered for the oxygen-fedozone generator

Three possibilities have to be considered for the oxygen-fedozone generatorozone generator

bull Excited N2 molecules lead to an increased O2 dissociation in

ozone generator

bull Excited N2 molecules lead to an increased O2 dissociation in2 2such case an increased efficiency is correlated to the N2admixture

2 2such case an increased efficiency is correlated to the N2admixture

bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial

bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial

bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2

bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2g p g 3 pp y 2g p g 3 pp y 2

Effect of methane on ozone efficiency and specific powerEffect of methane on ozone efficiency and specific power

Effect of Methane on Ozone Content in Outlet Gas and on Specific Power Pure O2

13 12

10

11

12

t 8

10

8

9

10

ne c

onte

nt w

t

6

8

ecifi

c po

wer

kW

hlb

5

6

7

Ozo

n

2

4 Spe

400E+00 20E+03 40E+03 60E+03 80E+03 10E+04 12E+04

Methane in feedgas ppm

0

Ozone content in the outlet gas Specif ic pow er of the ozone generatorg p p g

Effects of N2 and CH4Effects of N2 and CH4

Pi t f h t lli N O t tPicture of an amorphous-crystalline N2O5 structurecaptured at the Orlando Skylake water plant in 2006

Plasma Chemistry with CH4 Impurities

OxygenO2 N2

e - e -

CHO N2

NO2

O NO

O2 N O2 O3

NOH

CH4e-

O3 NO

NO2

O2O3NO N

NO2 O

NO2

NO2

N2ONO3

N

O3

NO2

NO

HNO3

N2O4

N2O5

NO2

NO3

N2O5

Effect of methane on the electrode surfaces

a) b)

Inlet Outlet Outlet

) d)

I l t I l t

c) d)

Electrode of the ozone generator afterseveral hours in CH8O2 and up to 2 wt of methane (a b c)

Inlet Inlet

three hours in CH8O2+traces of N2 and up to 1 wt of methane (d) Visible change of discharge character at about 13 length of electrode (a d)

Kinetics of CHx Conversion without N2

conversion by collisions

O2 + CHx 12wt O3 + CO2 +H2O

deposition vaporizationby sputtering

ibl b l 1000 CHreversible process below 1000ppm CH4

Effect of water on electrode surface with N2

Inlet

OutletOutlet

Electrode of the ozone generator after several hours in H OO N

Inlet

Electrode of the ozone generator after several hours in H2OO2N2

Effect of water on electrode surface

Long term effect (800 hrs) of H2OO2N2

Kinetics of CHx Conversion with N2

conversion by collisionsHNO3 formation

O2 + N2 +CHx 12wtO2 + CO2 +H2O + HNO3

deposition vaporizationby sputtering

H2O + HNO3

by sputtering

irreversible process above a N2 threshold () ltlt 1000ppm N2

sticky deposit

p 2 ( ) pp 2 any CH4 concentration (60ppm)

Plasma Chemistry with CH4 ImpuritiesPlasma Chemistry with CH4 Impurities4

bull Formation of NO and NO2 depends on O3 N2 and gas temperature Conclusion N2 admixture is the key factor

SummarySummaryyyThe mechanisms of formed NOx by-products follows the sameThe mechanisms of formed NOx by-products follows the sameprinciples as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentration

principles as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentrationozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)

ozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)g p ( g p )

The conversion of methane to OH and H2O is found to depend on

g p ( g p )

The conversion of methane to OH and H2O is found to depend ondissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)

dissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)discharge gap)discharge gap)

How do you optimize an ozone generatorg

Scientific ApproachScientific ApproachTheoretical Experimental

pppp

c [wt]

f [Hz]

c [wt]

f [Hz]

[kW]UUUβ1

1Cf4αPn

1iiminpeakimin

iiD

q [kWm2]q [kWm2]

150

180

][V]voltagepeakUpeak

[]cylinder perslicesofamountnsliceii

whereth

09 00

30

60

90

120

effic

ienc

y [

][0tdj t bl[F]sliceisdielectricofecapacitancC

[Hz]frequencyf[V]sliceivoltageminimumiUmin

thiD

th

10

28

46

64

82

39

107

176

244 power density

[kWm2]

ozone conc [wt][]CCβ

][0parameteradjustableα

iDiGi

Impact of Power Inductionp

350

400

wer

200

250

300

App

lied

Pow

Arr C 2Arr D +0

Arr E +45Arr F +7

Arr G +3

5 0

100

150

Frac

tion

of

1 2 3 4

ReferenceArr B unstable

Arr C -2

00

50

4Position (1inlet 4outlet)

Experimental Test Rigp g

Experimental Test Rigp g

Outer grounded electrode (left picture) and the dielectric covered inner electrodes (right) d e ect c cove ed e e ect odes ( g t)

Reference (Traditional) Arrangement

Inlet OutletGas flow direction

Optimized Arrangement

Inlet OutletGas flow direction

Intelligent Gap System (IGS)g p y ( )

Molecular Oxygen (O2) Ozone (O3)

O2 O3

yg ( 2) ( 3)

Particle Size SynthesisParticle Size SynthesisByBy--Products Cluster FormationProducts Cluster Formationyy

high diffusion and deposition to surfaces

low diffusion rate good transport

high sedimentation on the structurehigh sedimentation on the structure

Degreacutemont Technologies ndash OzoniaIntelligent Gap SystemIntelligent Gap System

G Vezzuacute JL Lopez A Freilich and K Becker Optimizationof Large-Scale Ozone Generators IEEE Transactions onPlasma Science Vol 37 No 6 p 890-896 (2009)

ConclusionsConclusionsConclusionsConclusionsFundamentals of ozone synthesis in a DBD plasmay p

ndash Highly filamented DBD discharges are best-suitedfor the production of ozone concentrations in therange of 6 to 14 wtrange of 6 to 14 wt

ndash The preferred characteristic of the microdischargesare Townsend-like at reduced electric fields Enaround 190 Townsend

ndash Detrimental side-effects induced by by-productscan be avoided by a proper design of the electrodecan be avoided by a proper design of the electrodearrangement The phenomenon is related to thediffusion rates of formed by-product clusters

ConclusionsConclusionsConclusionsConclusionsBenefits from DBD microplasma tailoring

ndash Reduced power consumption of up to 10 improvement

ndash Increased ozone concentrations of up to 14 now achievable

ndash Improved neutralization and conditioning of detrimental by-products

ndash Reduced system capital and operational cost

New technologies to improve ozone p

generatorg

HV Pulsed Power SwitchingHV Pulsed Power Switching

Microchannel Generation of Ozone

Channel ArrayChannel Array

Microchannel

330 microm 230 microm

Some Cap-DBD Devices Operating in Air

Increase of 60 of

Spacing 225 μmof 60 of plasma

No space

Cap‐DBD ozone generation

bull Ozone concentration is evaluated via Eco S d l UV 100 O A l (0 01Sensors model UV-100 Ozone Analyzer (001 ndash 900 ppm wiht an accuracy of plusmn2)

bull Three reactors 6 tubings 6rdquo with spacings of 0 μm 225 μm and 500 μm running at 3 kV μ μ μ g

SpacingOzone Concentration

3 kV rms 4 kV rms3 kV rms 4 kV rms

0 μm 660 ppm

225 μm 550 ppm

For a device of such small scale these ozone levels are promising

500 μm 380 ppm

J Mahoney W Zhu VS Johnson KH Becker and JL Lopez Electrical and optical emissionmeasurements of a capillary dielectric barrier discharge European Physics Journal D Vol 60 441-447(2010)

QuestionsQuestions

Thank YouFor more informationProf Jose L Lopez PhD

Thank YouFor more informationDepartment of Physics

Telephone (973) 761-9057Email joselopez1shuedu

Website wwwshueduacademicsartsciphysicsWebsite wwwshueduacademicsartsciphysics

Page 53: Dielectric Barrier Discharge (DBD) & Progress in Large ...bonitz/si12/talks/august_8/lopez_si12.pdf · Dielectric Barrier Discharge (DBD) & Progress in Large-Scale Ozone Generation

Municipal Ozone Installations

Ozonia Installations Ozone Plant Size [lbday] Start-Up DateKey Ozonia Installations (Partial List)

Los Angeles CA 10000 1986Fairfax VA ndash Corbalis 9000 2003MWD CA ndash Mills 9 000 2003

Ozonia Installations Ozone Plant Size [lbday] Start Up Date

MWD CA Mills 9000 2003Fairfax Co VA ndash Griffith 9000 2004MWD CA ndash Jensen 18750 2005Indianapolis IN ndash Belmont AWT 12000 2007I di li IN 12 000 2007Indianapolis IN ndash Southport AWT 12000 2007MWD CA ndash Diemer 13400 2008MWD CA ndash Weymouth 13400 2009

Ozonia North America - Potable Water SummaryTotal Number of Installations 90Total Installed Production gt 265000 lbsdayTotal Installed Production 265000 lbsday

Revision -B

Ozone Water TreatmentOzone Water Treatment

MWD Mills WTP - California

3 3 000 lbsda of o one3 3 000 lbsda of o one3 x 3000 lbsday of ozone3 x 3000 lbsday of ozone

Ozone Water TreatmentOzone Water TreatmentOzone Ozone -- How it worksHow it works

OxidantOxidant DisinfectantDisinfectant

bullbull Breaks double carbon Breaks double carbon bondsbonds

bullbull Kills by cell lysing or Kills by cell lysing or causing the cell wall tocausing the cell wall tobondsbonds

bullbull Creates OHCreates OHbullbull radicals radicals which break higher carbon which break higher carbon

causing the cell wall to causing the cell wall to rupture rupture

bullbull AttacksAttacks allall bacteriabacteriabondsbondsbullbull Increased temp and pH Increased temp and pH

accelerates Oaccelerates O33

Attacks Attacks allall bacteria bacteria virus cysts and spores virus cysts and spores in varying degreesin varying degreesaccelerates Oaccelerates O33

decomposition to OHdecomposition to OHbullbull

Micro-organism DNA

Capsule AdenineAdenine

Cell wall ThymineThymine

CytosineCytosine

GuanineGuanine

NuclearmaterialCellmembrane

material

Typical Bacterium DNA

Microbial Growth at Various Ozone ConcentrationsConcentrations

Growth likely

Growth possibleGrowth possible

NO GROWTH

0004 0008 0012 0016 0020

Ozone concentration (mgl)Ozone concentration (mgl)

Typical Water Treatment UsageTypical Water Treatment Usage

Application O3 mgl Contact timeUltra Pure Water 005 - 025 sec ndash min

Water bottling 04 ndash 10 5 ndash 10 min

Swimming pools ampspas

01 ndash 075 4 minutes

Potable taste amp odor 15 ndash 50 5 ndash 10 mindisinfection

Microfloculation 10 ndash 30 5 ndash 10 min

Lignin amp tammin 3 0 10 0 10 30 minLignin amp tamminremoval

30 ndash 100 10 ndash 30 min

Municipal wastewater 50 ndash 150+ 15 ndash 30 min

Ozone Water TreatmentOzone Water TreatmentOzone Ozone ndashndash Municipal ApplicationsMunicipal Applications

bullbull Taste and OdorTaste and Odor

bullbull Color RemovalColor Removal

bullbull Disinfection Without Trihalomethanes (THMs)Disinfection Without Trihalomethanes (THMs)

bullbull Improved Filtration Efficiency and FlocculationImproved Filtration Efficiency and Flocculation

bullbull Cryptosporidium DeactivationCryptosporidium Deactivation

bullbull Giardia amp Virus InactivationGiardia amp Virus Inactivation

bullbull Oxidation Oxidation -- Organics Fe amp MnOrganics Fe amp Mn

bullbull Wastewater disinfectionWastewater disinfection

bullbull BOD COD and TOC reductionBOD COD and TOC reduction

Applications of Ozone

Wastewater Treatmentbull Disinfection of Secondary and Tertiary Effluentsbull Color Reductionbull Color Reductionbull TOC Oxidation (Industrial)bull Oxidation of Odor Causing Compoundsbull Oxidation of Endocrine Disruptors (EDCrsquos) and p ( )

Pharmaceutically Active Compounds (PACrsquos)

Applications of Ozone

What are Endocrine Disruptors (EDCrsquos) and What are Endocrine Disruptors (EDCrsquos) and Ph ti ll A ti C d (PACrsquo )Ph ti ll A ti C d (PACrsquo )Pharmaceutically Active Compounds (PACrsquos)Pharmaceutically Active Compounds (PACrsquos)

bullbull EDCrsquosEDCrsquos andand PACrsquosPACrsquos areare NaturallyNaturally andand SyntheticSyntheticdd th tth t ff tff t thth b lb l llcompoundscompounds thatthat maymay affectaffect thethe balancebalance oror normalnormal

functionsfunctions inin animalsanimals andand humanshumans

What can EDCrsquos and PACrsquos doWhat can EDCrsquos and PACrsquos do

bullbull Even in very small concentrations these compounds Even in very small concentrations these compounds y py pcan can disruptdisrupt normal bodily functionsnormal bodily functions

bullbull ManMan--made chemicals can trick the bodies endocrine made chemicals can trick the bodies endocrine system system

Applications of Ozone

Examples of Endocrine Disruptors1000rsquos of compounds that may be Investigated as EDCs ndash Some examples are

bullbull Synthetic HormonesSynthetic Hormonesbullbull Naturally Occurring Estrogens Naturally Occurring Estrogens

Health and Beauty AidsHealth and Beauty Aidsbullbull Health and Beauty AidsHealth and Beauty Aidsbullbull SolventsSolventsbullbull PesticidesPesticidesbullbull SurfactantsSurfactantsbullbull PlasticsPlastics

F i idF i idbullbull FungicidesFungicides

Ozone Water TreatmentOzone Water Treatment

Ozone Ozone -- Industrial ApplicationsIndustrial Applications-- Ultrapure Water for Pharmaceutical ApplicationsUltrapure Water for Pharmaceutical Applications

-- Wastewater disinfection color removalWastewater disinfection color removal

-- Soil and Groundwater Remediation Soil and Groundwater Remediation

-- Cooling Tower Water TreatmentCooling Tower Water Treatment

-- Food ProcessingFood Processing

-- Aquaculture AquariumsAquaculture AquariumsAquaculture AquariumsAquaculture Aquariums

-- Beverage ApplicationsBeverage Applications

P l amp P Bl hiP l amp P Bl hi-- Pulp amp Paper BleachingPulp amp Paper Bleaching

High Purity OzonationHigh Purity Ozonation

Microchip manufacturingMicrochip manufacturing

What are the current issues in large-scale gozone generationg

Experimental Setup

Front view of the two units after the redesign and reworking ofthe gas water and instruments connectionsthe gas water and instruments connections

Experimental Setup

Top view of the twoexperimental unitsexperimental unitsSpectroscope (notshown) is to the left ofthe DBD The units weredifferent with respect todifferent with respect totheir electrodes onehad only the electrodecoated with thedielectric (ldquosingle-dielectric ( single-coatedrdquo) the other onehad the electrode andthe anode coated withthe dielectric (ldquodouble-the dielectric ( double-coatedrdquo)

Basics Generation of OzoneBasics Generation of Ozone

SpectroscopyPlasma

Plasma Absorption SpectroscopyPlasma Absorption Spectroscopy

Infrared Absorption SpectroscopyInfrared Absorption Spectroscopy

IR spectra in pure oxygen (black curve) and at approximately 10wt N2 admixture (red line) N2O5 peaks appear at124 1 d 1 2 11245 cm-1 and at 1725 cm-1

Infrared Absorption SpectroscopyInfrared Absorption Spectroscopy

IR spectra of several methane variations The green curve envelopes all of the methane peaks at 1325 cm-1recorded at smaller methane admixtures Simultaneously the N2O5 peaks disappear as the methane peaks appear

N2O5 FormationN2O5 Formation2 52 5p=2 bara cwt=20degC q=35kWm2 f=1450Hz

45N2O5 AT95

30

35

40

N

2 B

lend

ing

N2O AT95N2O5 IGSN2O IGSN2O5 LGN2O LG

1 5

20

25

nt [p

pmV]

3

wt

05

10

15

NO

x co

nten

005 7 9 11 13 15 17

ozone conc [wt]

Amount of formed N2O5 and N2O as a function of ozone concentration at 3 wt of nitrogen admixture and fori l dvarious electrode arrangements

Plasma Emission SpectroscopyPlasma Emission Spectroscopyp pyp py

Relative Emissions of the Ozonizer plasmaRelative Emissions of the Ozonizer plasma

Region 300- 850 nm from individual (calibrated) regions (smoothed by PeakFit) Single-coated ozone generator Inlet side

3 5E+06

30E+06

35E+06

7 9

20E+06

25E+06

nten

sity

au

2

311 12

10E+06

15E+06

In 4

5

6 8 10

14

15

16

17

00E+00

50E+05

280 300 320 340 360 380 400 420 440 460 480 500 520 540 560 580 600 620 640 660 680 700 720 740 760 780 800 820 840 860

Wavelength nm

1 13

Wavelength nm

Absolute Emission of the DBD PlasmaAbsolute Emission of the DBD Plasma

Intensities in (O2+3 wtN2) plasma

1 20E+04

100E+04

120E+04

600E+03

800E+03

nten

sity

(au

)

200E+03

400E+03

In

O(777)

000E+00200 250 300 350 400 450 500 550 600 650 700 750 800 850

Wavelength nm

Intensities in 3 wtN2+O2 plasmaIntensities in 3 wtN2+O2 plasma

Plasma Chemistry in OzonizersPlasma Chemistry in Ozonizers

Dry Air O2 N2

e - e -

O N2 N O2

O3 NO

O2 N O2

O3

N

3

NO2

O2 O3

NO

N

NO2 O3

N2O

NO3 N

N2O4

NO2

NO2

N2O5

NO3

Primary electron-driven chemical reactions leading to the formation of N2O5 and N2O in a dry air plasma

Plasma emission diagnostics role of N2Plasma emission diagnostics role of N2

Dry Air O2 N2

e - e -

O N2 N O2

O3 NO

O2 N O2

O3

O

N

ON

NO2

O2O3

N

NO N

NO2 O3

N2O

NO3 N

N2O4

NO2

NO2

N2O5

NO3

ONbullWith N2 present ndash less oxygen atoms are formed However the difference in intensity is

very small

Modeling of plasma chemistry incl the NxOy chemistry up to N2O5 for different Oxygen Nitrogen mixtures varying power deposition scenarios

and initial ozone background concentrations (up to 15) previously done

The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation

The role of N2 must be related to its by-products reacting on the surface of the electrodeThe role of N2 must be related to its by-products reacting on the surface of the electrode

The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established

Ab 8 t f O

The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established

Ab 8 t f OAbove 8 wt of O3

1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)

Above 8 wt of O3

1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)case without pampp)

2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of the

case without pampp)

2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of thethem A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface

them A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface

The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation

Three possibilities have to be considered for the oxygen-fedozone generator

Three possibilities have to be considered for the oxygen-fedozone generatorozone generator

bull Excited N2 molecules lead to an increased O2 dissociation in

ozone generator

bull Excited N2 molecules lead to an increased O2 dissociation in2 2such case an increased efficiency is correlated to the N2admixture

2 2such case an increased efficiency is correlated to the N2admixture

bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial

bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial

bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2

bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2g p g 3 pp y 2g p g 3 pp y 2

Effect of methane on ozone efficiency and specific powerEffect of methane on ozone efficiency and specific power

Effect of Methane on Ozone Content in Outlet Gas and on Specific Power Pure O2

13 12

10

11

12

t 8

10

8

9

10

ne c

onte

nt w

t

6

8

ecifi

c po

wer

kW

hlb

5

6

7

Ozo

n

2

4 Spe

400E+00 20E+03 40E+03 60E+03 80E+03 10E+04 12E+04

Methane in feedgas ppm

0

Ozone content in the outlet gas Specif ic pow er of the ozone generatorg p p g

Effects of N2 and CH4Effects of N2 and CH4

Pi t f h t lli N O t tPicture of an amorphous-crystalline N2O5 structurecaptured at the Orlando Skylake water plant in 2006

Plasma Chemistry with CH4 Impurities

OxygenO2 N2

e - e -

CHO N2

NO2

O NO

O2 N O2 O3

NOH

CH4e-

O3 NO

NO2

O2O3NO N

NO2 O

NO2

NO2

N2ONO3

N

O3

NO2

NO

HNO3

N2O4

N2O5

NO2

NO3

N2O5

Effect of methane on the electrode surfaces

a) b)

Inlet Outlet Outlet

) d)

I l t I l t

c) d)

Electrode of the ozone generator afterseveral hours in CH8O2 and up to 2 wt of methane (a b c)

Inlet Inlet

three hours in CH8O2+traces of N2 and up to 1 wt of methane (d) Visible change of discharge character at about 13 length of electrode (a d)

Kinetics of CHx Conversion without N2

conversion by collisions

O2 + CHx 12wt O3 + CO2 +H2O

deposition vaporizationby sputtering

ibl b l 1000 CHreversible process below 1000ppm CH4

Effect of water on electrode surface with N2

Inlet

OutletOutlet

Electrode of the ozone generator after several hours in H OO N

Inlet

Electrode of the ozone generator after several hours in H2OO2N2

Effect of water on electrode surface

Long term effect (800 hrs) of H2OO2N2

Kinetics of CHx Conversion with N2

conversion by collisionsHNO3 formation

O2 + N2 +CHx 12wtO2 + CO2 +H2O + HNO3

deposition vaporizationby sputtering

H2O + HNO3

by sputtering

irreversible process above a N2 threshold () ltlt 1000ppm N2

sticky deposit

p 2 ( ) pp 2 any CH4 concentration (60ppm)

Plasma Chemistry with CH4 ImpuritiesPlasma Chemistry with CH4 Impurities4

bull Formation of NO and NO2 depends on O3 N2 and gas temperature Conclusion N2 admixture is the key factor

SummarySummaryyyThe mechanisms of formed NOx by-products follows the sameThe mechanisms of formed NOx by-products follows the sameprinciples as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentration

principles as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentrationozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)

ozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)g p ( g p )

The conversion of methane to OH and H2O is found to depend on

g p ( g p )

The conversion of methane to OH and H2O is found to depend ondissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)

dissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)discharge gap)discharge gap)

How do you optimize an ozone generatorg

Scientific ApproachScientific ApproachTheoretical Experimental

pppp

c [wt]

f [Hz]

c [wt]

f [Hz]

[kW]UUUβ1

1Cf4αPn

1iiminpeakimin

iiD

q [kWm2]q [kWm2]

150

180

][V]voltagepeakUpeak

[]cylinder perslicesofamountnsliceii

whereth

09 00

30

60

90

120

effic

ienc

y [

][0tdj t bl[F]sliceisdielectricofecapacitancC

[Hz]frequencyf[V]sliceivoltageminimumiUmin

thiD

th

10

28

46

64

82

39

107

176

244 power density

[kWm2]

ozone conc [wt][]CCβ

][0parameteradjustableα

iDiGi

Impact of Power Inductionp

350

400

wer

200

250

300

App

lied

Pow

Arr C 2Arr D +0

Arr E +45Arr F +7

Arr G +3

5 0

100

150

Frac

tion

of

1 2 3 4

ReferenceArr B unstable

Arr C -2

00

50

4Position (1inlet 4outlet)

Experimental Test Rigp g

Experimental Test Rigp g

Outer grounded electrode (left picture) and the dielectric covered inner electrodes (right) d e ect c cove ed e e ect odes ( g t)

Reference (Traditional) Arrangement

Inlet OutletGas flow direction

Optimized Arrangement

Inlet OutletGas flow direction

Intelligent Gap System (IGS)g p y ( )

Molecular Oxygen (O2) Ozone (O3)

O2 O3

yg ( 2) ( 3)

Particle Size SynthesisParticle Size SynthesisByBy--Products Cluster FormationProducts Cluster Formationyy

high diffusion and deposition to surfaces

low diffusion rate good transport

high sedimentation on the structurehigh sedimentation on the structure

Degreacutemont Technologies ndash OzoniaIntelligent Gap SystemIntelligent Gap System

G Vezzuacute JL Lopez A Freilich and K Becker Optimizationof Large-Scale Ozone Generators IEEE Transactions onPlasma Science Vol 37 No 6 p 890-896 (2009)

ConclusionsConclusionsConclusionsConclusionsFundamentals of ozone synthesis in a DBD plasmay p

ndash Highly filamented DBD discharges are best-suitedfor the production of ozone concentrations in therange of 6 to 14 wtrange of 6 to 14 wt

ndash The preferred characteristic of the microdischargesare Townsend-like at reduced electric fields Enaround 190 Townsend

ndash Detrimental side-effects induced by by-productscan be avoided by a proper design of the electrodecan be avoided by a proper design of the electrodearrangement The phenomenon is related to thediffusion rates of formed by-product clusters

ConclusionsConclusionsConclusionsConclusionsBenefits from DBD microplasma tailoring

ndash Reduced power consumption of up to 10 improvement

ndash Increased ozone concentrations of up to 14 now achievable

ndash Improved neutralization and conditioning of detrimental by-products

ndash Reduced system capital and operational cost

New technologies to improve ozone p

generatorg

HV Pulsed Power SwitchingHV Pulsed Power Switching

Microchannel Generation of Ozone

Channel ArrayChannel Array

Microchannel

330 microm 230 microm

Some Cap-DBD Devices Operating in Air

Increase of 60 of

Spacing 225 μmof 60 of plasma

No space

Cap‐DBD ozone generation

bull Ozone concentration is evaluated via Eco S d l UV 100 O A l (0 01Sensors model UV-100 Ozone Analyzer (001 ndash 900 ppm wiht an accuracy of plusmn2)

bull Three reactors 6 tubings 6rdquo with spacings of 0 μm 225 μm and 500 μm running at 3 kV μ μ μ g

SpacingOzone Concentration

3 kV rms 4 kV rms3 kV rms 4 kV rms

0 μm 660 ppm

225 μm 550 ppm

For a device of such small scale these ozone levels are promising

500 μm 380 ppm

J Mahoney W Zhu VS Johnson KH Becker and JL Lopez Electrical and optical emissionmeasurements of a capillary dielectric barrier discharge European Physics Journal D Vol 60 441-447(2010)

QuestionsQuestions

Thank YouFor more informationProf Jose L Lopez PhD

Thank YouFor more informationDepartment of Physics

Telephone (973) 761-9057Email joselopez1shuedu

Website wwwshueduacademicsartsciphysicsWebsite wwwshueduacademicsartsciphysics

Page 54: Dielectric Barrier Discharge (DBD) & Progress in Large ...bonitz/si12/talks/august_8/lopez_si12.pdf · Dielectric Barrier Discharge (DBD) & Progress in Large-Scale Ozone Generation

Ozone Water TreatmentOzone Water Treatment

MWD Mills WTP - California

3 3 000 lbsda of o one3 3 000 lbsda of o one3 x 3000 lbsday of ozone3 x 3000 lbsday of ozone

Ozone Water TreatmentOzone Water TreatmentOzone Ozone -- How it worksHow it works

OxidantOxidant DisinfectantDisinfectant

bullbull Breaks double carbon Breaks double carbon bondsbonds

bullbull Kills by cell lysing or Kills by cell lysing or causing the cell wall tocausing the cell wall tobondsbonds

bullbull Creates OHCreates OHbullbull radicals radicals which break higher carbon which break higher carbon

causing the cell wall to causing the cell wall to rupture rupture

bullbull AttacksAttacks allall bacteriabacteriabondsbondsbullbull Increased temp and pH Increased temp and pH

accelerates Oaccelerates O33

Attacks Attacks allall bacteria bacteria virus cysts and spores virus cysts and spores in varying degreesin varying degreesaccelerates Oaccelerates O33

decomposition to OHdecomposition to OHbullbull

Micro-organism DNA

Capsule AdenineAdenine

Cell wall ThymineThymine

CytosineCytosine

GuanineGuanine

NuclearmaterialCellmembrane

material

Typical Bacterium DNA

Microbial Growth at Various Ozone ConcentrationsConcentrations

Growth likely

Growth possibleGrowth possible

NO GROWTH

0004 0008 0012 0016 0020

Ozone concentration (mgl)Ozone concentration (mgl)

Typical Water Treatment UsageTypical Water Treatment Usage

Application O3 mgl Contact timeUltra Pure Water 005 - 025 sec ndash min

Water bottling 04 ndash 10 5 ndash 10 min

Swimming pools ampspas

01 ndash 075 4 minutes

Potable taste amp odor 15 ndash 50 5 ndash 10 mindisinfection

Microfloculation 10 ndash 30 5 ndash 10 min

Lignin amp tammin 3 0 10 0 10 30 minLignin amp tamminremoval

30 ndash 100 10 ndash 30 min

Municipal wastewater 50 ndash 150+ 15 ndash 30 min

Ozone Water TreatmentOzone Water TreatmentOzone Ozone ndashndash Municipal ApplicationsMunicipal Applications

bullbull Taste and OdorTaste and Odor

bullbull Color RemovalColor Removal

bullbull Disinfection Without Trihalomethanes (THMs)Disinfection Without Trihalomethanes (THMs)

bullbull Improved Filtration Efficiency and FlocculationImproved Filtration Efficiency and Flocculation

bullbull Cryptosporidium DeactivationCryptosporidium Deactivation

bullbull Giardia amp Virus InactivationGiardia amp Virus Inactivation

bullbull Oxidation Oxidation -- Organics Fe amp MnOrganics Fe amp Mn

bullbull Wastewater disinfectionWastewater disinfection

bullbull BOD COD and TOC reductionBOD COD and TOC reduction

Applications of Ozone

Wastewater Treatmentbull Disinfection of Secondary and Tertiary Effluentsbull Color Reductionbull Color Reductionbull TOC Oxidation (Industrial)bull Oxidation of Odor Causing Compoundsbull Oxidation of Endocrine Disruptors (EDCrsquos) and p ( )

Pharmaceutically Active Compounds (PACrsquos)

Applications of Ozone

What are Endocrine Disruptors (EDCrsquos) and What are Endocrine Disruptors (EDCrsquos) and Ph ti ll A ti C d (PACrsquo )Ph ti ll A ti C d (PACrsquo )Pharmaceutically Active Compounds (PACrsquos)Pharmaceutically Active Compounds (PACrsquos)

bullbull EDCrsquosEDCrsquos andand PACrsquosPACrsquos areare NaturallyNaturally andand SyntheticSyntheticdd th tth t ff tff t thth b lb l llcompoundscompounds thatthat maymay affectaffect thethe balancebalance oror normalnormal

functionsfunctions inin animalsanimals andand humanshumans

What can EDCrsquos and PACrsquos doWhat can EDCrsquos and PACrsquos do

bullbull Even in very small concentrations these compounds Even in very small concentrations these compounds y py pcan can disruptdisrupt normal bodily functionsnormal bodily functions

bullbull ManMan--made chemicals can trick the bodies endocrine made chemicals can trick the bodies endocrine system system

Applications of Ozone

Examples of Endocrine Disruptors1000rsquos of compounds that may be Investigated as EDCs ndash Some examples are

bullbull Synthetic HormonesSynthetic Hormonesbullbull Naturally Occurring Estrogens Naturally Occurring Estrogens

Health and Beauty AidsHealth and Beauty Aidsbullbull Health and Beauty AidsHealth and Beauty Aidsbullbull SolventsSolventsbullbull PesticidesPesticidesbullbull SurfactantsSurfactantsbullbull PlasticsPlastics

F i idF i idbullbull FungicidesFungicides

Ozone Water TreatmentOzone Water Treatment

Ozone Ozone -- Industrial ApplicationsIndustrial Applications-- Ultrapure Water for Pharmaceutical ApplicationsUltrapure Water for Pharmaceutical Applications

-- Wastewater disinfection color removalWastewater disinfection color removal

-- Soil and Groundwater Remediation Soil and Groundwater Remediation

-- Cooling Tower Water TreatmentCooling Tower Water Treatment

-- Food ProcessingFood Processing

-- Aquaculture AquariumsAquaculture AquariumsAquaculture AquariumsAquaculture Aquariums

-- Beverage ApplicationsBeverage Applications

P l amp P Bl hiP l amp P Bl hi-- Pulp amp Paper BleachingPulp amp Paper Bleaching

High Purity OzonationHigh Purity Ozonation

Microchip manufacturingMicrochip manufacturing

What are the current issues in large-scale gozone generationg

Experimental Setup

Front view of the two units after the redesign and reworking ofthe gas water and instruments connectionsthe gas water and instruments connections

Experimental Setup

Top view of the twoexperimental unitsexperimental unitsSpectroscope (notshown) is to the left ofthe DBD The units weredifferent with respect todifferent with respect totheir electrodes onehad only the electrodecoated with thedielectric (ldquosingle-dielectric ( single-coatedrdquo) the other onehad the electrode andthe anode coated withthe dielectric (ldquodouble-the dielectric ( double-coatedrdquo)

Basics Generation of OzoneBasics Generation of Ozone

SpectroscopyPlasma

Plasma Absorption SpectroscopyPlasma Absorption Spectroscopy

Infrared Absorption SpectroscopyInfrared Absorption Spectroscopy

IR spectra in pure oxygen (black curve) and at approximately 10wt N2 admixture (red line) N2O5 peaks appear at124 1 d 1 2 11245 cm-1 and at 1725 cm-1

Infrared Absorption SpectroscopyInfrared Absorption Spectroscopy

IR spectra of several methane variations The green curve envelopes all of the methane peaks at 1325 cm-1recorded at smaller methane admixtures Simultaneously the N2O5 peaks disappear as the methane peaks appear

N2O5 FormationN2O5 Formation2 52 5p=2 bara cwt=20degC q=35kWm2 f=1450Hz

45N2O5 AT95

30

35

40

N

2 B

lend

ing

N2O AT95N2O5 IGSN2O IGSN2O5 LGN2O LG

1 5

20

25

nt [p

pmV]

3

wt

05

10

15

NO

x co

nten

005 7 9 11 13 15 17

ozone conc [wt]

Amount of formed N2O5 and N2O as a function of ozone concentration at 3 wt of nitrogen admixture and fori l dvarious electrode arrangements

Plasma Emission SpectroscopyPlasma Emission Spectroscopyp pyp py

Relative Emissions of the Ozonizer plasmaRelative Emissions of the Ozonizer plasma

Region 300- 850 nm from individual (calibrated) regions (smoothed by PeakFit) Single-coated ozone generator Inlet side

3 5E+06

30E+06

35E+06

7 9

20E+06

25E+06

nten

sity

au

2

311 12

10E+06

15E+06

In 4

5

6 8 10

14

15

16

17

00E+00

50E+05

280 300 320 340 360 380 400 420 440 460 480 500 520 540 560 580 600 620 640 660 680 700 720 740 760 780 800 820 840 860

Wavelength nm

1 13

Wavelength nm

Absolute Emission of the DBD PlasmaAbsolute Emission of the DBD Plasma

Intensities in (O2+3 wtN2) plasma

1 20E+04

100E+04

120E+04

600E+03

800E+03

nten

sity

(au

)

200E+03

400E+03

In

O(777)

000E+00200 250 300 350 400 450 500 550 600 650 700 750 800 850

Wavelength nm

Intensities in 3 wtN2+O2 plasmaIntensities in 3 wtN2+O2 plasma

Plasma Chemistry in OzonizersPlasma Chemistry in Ozonizers

Dry Air O2 N2

e - e -

O N2 N O2

O3 NO

O2 N O2

O3

N

3

NO2

O2 O3

NO

N

NO2 O3

N2O

NO3 N

N2O4

NO2

NO2

N2O5

NO3

Primary electron-driven chemical reactions leading to the formation of N2O5 and N2O in a dry air plasma

Plasma emission diagnostics role of N2Plasma emission diagnostics role of N2

Dry Air O2 N2

e - e -

O N2 N O2

O3 NO

O2 N O2

O3

O

N

ON

NO2

O2O3

N

NO N

NO2 O3

N2O

NO3 N

N2O4

NO2

NO2

N2O5

NO3

ONbullWith N2 present ndash less oxygen atoms are formed However the difference in intensity is

very small

Modeling of plasma chemistry incl the NxOy chemistry up to N2O5 for different Oxygen Nitrogen mixtures varying power deposition scenarios

and initial ozone background concentrations (up to 15) previously done

The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation

The role of N2 must be related to its by-products reacting on the surface of the electrodeThe role of N2 must be related to its by-products reacting on the surface of the electrode

The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established

Ab 8 t f O

The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established

Ab 8 t f OAbove 8 wt of O3

1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)

Above 8 wt of O3

1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)case without pampp)

2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of the

case without pampp)

2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of thethem A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface

them A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface

The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation

Three possibilities have to be considered for the oxygen-fedozone generator

Three possibilities have to be considered for the oxygen-fedozone generatorozone generator

bull Excited N2 molecules lead to an increased O2 dissociation in

ozone generator

bull Excited N2 molecules lead to an increased O2 dissociation in2 2such case an increased efficiency is correlated to the N2admixture

2 2such case an increased efficiency is correlated to the N2admixture

bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial

bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial

bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2

bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2g p g 3 pp y 2g p g 3 pp y 2

Effect of methane on ozone efficiency and specific powerEffect of methane on ozone efficiency and specific power

Effect of Methane on Ozone Content in Outlet Gas and on Specific Power Pure O2

13 12

10

11

12

t 8

10

8

9

10

ne c

onte

nt w

t

6

8

ecifi

c po

wer

kW

hlb

5

6

7

Ozo

n

2

4 Spe

400E+00 20E+03 40E+03 60E+03 80E+03 10E+04 12E+04

Methane in feedgas ppm

0

Ozone content in the outlet gas Specif ic pow er of the ozone generatorg p p g

Effects of N2 and CH4Effects of N2 and CH4

Pi t f h t lli N O t tPicture of an amorphous-crystalline N2O5 structurecaptured at the Orlando Skylake water plant in 2006

Plasma Chemistry with CH4 Impurities

OxygenO2 N2

e - e -

CHO N2

NO2

O NO

O2 N O2 O3

NOH

CH4e-

O3 NO

NO2

O2O3NO N

NO2 O

NO2

NO2

N2ONO3

N

O3

NO2

NO

HNO3

N2O4

N2O5

NO2

NO3

N2O5

Effect of methane on the electrode surfaces

a) b)

Inlet Outlet Outlet

) d)

I l t I l t

c) d)

Electrode of the ozone generator afterseveral hours in CH8O2 and up to 2 wt of methane (a b c)

Inlet Inlet

three hours in CH8O2+traces of N2 and up to 1 wt of methane (d) Visible change of discharge character at about 13 length of electrode (a d)

Kinetics of CHx Conversion without N2

conversion by collisions

O2 + CHx 12wt O3 + CO2 +H2O

deposition vaporizationby sputtering

ibl b l 1000 CHreversible process below 1000ppm CH4

Effect of water on electrode surface with N2

Inlet

OutletOutlet

Electrode of the ozone generator after several hours in H OO N

Inlet

Electrode of the ozone generator after several hours in H2OO2N2

Effect of water on electrode surface

Long term effect (800 hrs) of H2OO2N2

Kinetics of CHx Conversion with N2

conversion by collisionsHNO3 formation

O2 + N2 +CHx 12wtO2 + CO2 +H2O + HNO3

deposition vaporizationby sputtering

H2O + HNO3

by sputtering

irreversible process above a N2 threshold () ltlt 1000ppm N2

sticky deposit

p 2 ( ) pp 2 any CH4 concentration (60ppm)

Plasma Chemistry with CH4 ImpuritiesPlasma Chemistry with CH4 Impurities4

bull Formation of NO and NO2 depends on O3 N2 and gas temperature Conclusion N2 admixture is the key factor

SummarySummaryyyThe mechanisms of formed NOx by-products follows the sameThe mechanisms of formed NOx by-products follows the sameprinciples as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentration

principles as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentrationozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)

ozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)g p ( g p )

The conversion of methane to OH and H2O is found to depend on

g p ( g p )

The conversion of methane to OH and H2O is found to depend ondissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)

dissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)discharge gap)discharge gap)

How do you optimize an ozone generatorg

Scientific ApproachScientific ApproachTheoretical Experimental

pppp

c [wt]

f [Hz]

c [wt]

f [Hz]

[kW]UUUβ1

1Cf4αPn

1iiminpeakimin

iiD

q [kWm2]q [kWm2]

150

180

][V]voltagepeakUpeak

[]cylinder perslicesofamountnsliceii

whereth

09 00

30

60

90

120

effic

ienc

y [

][0tdj t bl[F]sliceisdielectricofecapacitancC

[Hz]frequencyf[V]sliceivoltageminimumiUmin

thiD

th

10

28

46

64

82

39

107

176

244 power density

[kWm2]

ozone conc [wt][]CCβ

][0parameteradjustableα

iDiGi

Impact of Power Inductionp

350

400

wer

200

250

300

App

lied

Pow

Arr C 2Arr D +0

Arr E +45Arr F +7

Arr G +3

5 0

100

150

Frac

tion

of

1 2 3 4

ReferenceArr B unstable

Arr C -2

00

50

4Position (1inlet 4outlet)

Experimental Test Rigp g

Experimental Test Rigp g

Outer grounded electrode (left picture) and the dielectric covered inner electrodes (right) d e ect c cove ed e e ect odes ( g t)

Reference (Traditional) Arrangement

Inlet OutletGas flow direction

Optimized Arrangement

Inlet OutletGas flow direction

Intelligent Gap System (IGS)g p y ( )

Molecular Oxygen (O2) Ozone (O3)

O2 O3

yg ( 2) ( 3)

Particle Size SynthesisParticle Size SynthesisByBy--Products Cluster FormationProducts Cluster Formationyy

high diffusion and deposition to surfaces

low diffusion rate good transport

high sedimentation on the structurehigh sedimentation on the structure

Degreacutemont Technologies ndash OzoniaIntelligent Gap SystemIntelligent Gap System

G Vezzuacute JL Lopez A Freilich and K Becker Optimizationof Large-Scale Ozone Generators IEEE Transactions onPlasma Science Vol 37 No 6 p 890-896 (2009)

ConclusionsConclusionsConclusionsConclusionsFundamentals of ozone synthesis in a DBD plasmay p

ndash Highly filamented DBD discharges are best-suitedfor the production of ozone concentrations in therange of 6 to 14 wtrange of 6 to 14 wt

ndash The preferred characteristic of the microdischargesare Townsend-like at reduced electric fields Enaround 190 Townsend

ndash Detrimental side-effects induced by by-productscan be avoided by a proper design of the electrodecan be avoided by a proper design of the electrodearrangement The phenomenon is related to thediffusion rates of formed by-product clusters

ConclusionsConclusionsConclusionsConclusionsBenefits from DBD microplasma tailoring

ndash Reduced power consumption of up to 10 improvement

ndash Increased ozone concentrations of up to 14 now achievable

ndash Improved neutralization and conditioning of detrimental by-products

ndash Reduced system capital and operational cost

New technologies to improve ozone p

generatorg

HV Pulsed Power SwitchingHV Pulsed Power Switching

Microchannel Generation of Ozone

Channel ArrayChannel Array

Microchannel

330 microm 230 microm

Some Cap-DBD Devices Operating in Air

Increase of 60 of

Spacing 225 μmof 60 of plasma

No space

Cap‐DBD ozone generation

bull Ozone concentration is evaluated via Eco S d l UV 100 O A l (0 01Sensors model UV-100 Ozone Analyzer (001 ndash 900 ppm wiht an accuracy of plusmn2)

bull Three reactors 6 tubings 6rdquo with spacings of 0 μm 225 μm and 500 μm running at 3 kV μ μ μ g

SpacingOzone Concentration

3 kV rms 4 kV rms3 kV rms 4 kV rms

0 μm 660 ppm

225 μm 550 ppm

For a device of such small scale these ozone levels are promising

500 μm 380 ppm

J Mahoney W Zhu VS Johnson KH Becker and JL Lopez Electrical and optical emissionmeasurements of a capillary dielectric barrier discharge European Physics Journal D Vol 60 441-447(2010)

QuestionsQuestions

Thank YouFor more informationProf Jose L Lopez PhD

Thank YouFor more informationDepartment of Physics

Telephone (973) 761-9057Email joselopez1shuedu

Website wwwshueduacademicsartsciphysicsWebsite wwwshueduacademicsartsciphysics

Page 55: Dielectric Barrier Discharge (DBD) & Progress in Large ...bonitz/si12/talks/august_8/lopez_si12.pdf · Dielectric Barrier Discharge (DBD) & Progress in Large-Scale Ozone Generation

Ozone Water TreatmentOzone Water TreatmentOzone Ozone -- How it worksHow it works

OxidantOxidant DisinfectantDisinfectant

bullbull Breaks double carbon Breaks double carbon bondsbonds

bullbull Kills by cell lysing or Kills by cell lysing or causing the cell wall tocausing the cell wall tobondsbonds

bullbull Creates OHCreates OHbullbull radicals radicals which break higher carbon which break higher carbon

causing the cell wall to causing the cell wall to rupture rupture

bullbull AttacksAttacks allall bacteriabacteriabondsbondsbullbull Increased temp and pH Increased temp and pH

accelerates Oaccelerates O33

Attacks Attacks allall bacteria bacteria virus cysts and spores virus cysts and spores in varying degreesin varying degreesaccelerates Oaccelerates O33

decomposition to OHdecomposition to OHbullbull

Micro-organism DNA

Capsule AdenineAdenine

Cell wall ThymineThymine

CytosineCytosine

GuanineGuanine

NuclearmaterialCellmembrane

material

Typical Bacterium DNA

Microbial Growth at Various Ozone ConcentrationsConcentrations

Growth likely

Growth possibleGrowth possible

NO GROWTH

0004 0008 0012 0016 0020

Ozone concentration (mgl)Ozone concentration (mgl)

Typical Water Treatment UsageTypical Water Treatment Usage

Application O3 mgl Contact timeUltra Pure Water 005 - 025 sec ndash min

Water bottling 04 ndash 10 5 ndash 10 min

Swimming pools ampspas

01 ndash 075 4 minutes

Potable taste amp odor 15 ndash 50 5 ndash 10 mindisinfection

Microfloculation 10 ndash 30 5 ndash 10 min

Lignin amp tammin 3 0 10 0 10 30 minLignin amp tamminremoval

30 ndash 100 10 ndash 30 min

Municipal wastewater 50 ndash 150+ 15 ndash 30 min

Ozone Water TreatmentOzone Water TreatmentOzone Ozone ndashndash Municipal ApplicationsMunicipal Applications

bullbull Taste and OdorTaste and Odor

bullbull Color RemovalColor Removal

bullbull Disinfection Without Trihalomethanes (THMs)Disinfection Without Trihalomethanes (THMs)

bullbull Improved Filtration Efficiency and FlocculationImproved Filtration Efficiency and Flocculation

bullbull Cryptosporidium DeactivationCryptosporidium Deactivation

bullbull Giardia amp Virus InactivationGiardia amp Virus Inactivation

bullbull Oxidation Oxidation -- Organics Fe amp MnOrganics Fe amp Mn

bullbull Wastewater disinfectionWastewater disinfection

bullbull BOD COD and TOC reductionBOD COD and TOC reduction

Applications of Ozone

Wastewater Treatmentbull Disinfection of Secondary and Tertiary Effluentsbull Color Reductionbull Color Reductionbull TOC Oxidation (Industrial)bull Oxidation of Odor Causing Compoundsbull Oxidation of Endocrine Disruptors (EDCrsquos) and p ( )

Pharmaceutically Active Compounds (PACrsquos)

Applications of Ozone

What are Endocrine Disruptors (EDCrsquos) and What are Endocrine Disruptors (EDCrsquos) and Ph ti ll A ti C d (PACrsquo )Ph ti ll A ti C d (PACrsquo )Pharmaceutically Active Compounds (PACrsquos)Pharmaceutically Active Compounds (PACrsquos)

bullbull EDCrsquosEDCrsquos andand PACrsquosPACrsquos areare NaturallyNaturally andand SyntheticSyntheticdd th tth t ff tff t thth b lb l llcompoundscompounds thatthat maymay affectaffect thethe balancebalance oror normalnormal

functionsfunctions inin animalsanimals andand humanshumans

What can EDCrsquos and PACrsquos doWhat can EDCrsquos and PACrsquos do

bullbull Even in very small concentrations these compounds Even in very small concentrations these compounds y py pcan can disruptdisrupt normal bodily functionsnormal bodily functions

bullbull ManMan--made chemicals can trick the bodies endocrine made chemicals can trick the bodies endocrine system system

Applications of Ozone

Examples of Endocrine Disruptors1000rsquos of compounds that may be Investigated as EDCs ndash Some examples are

bullbull Synthetic HormonesSynthetic Hormonesbullbull Naturally Occurring Estrogens Naturally Occurring Estrogens

Health and Beauty AidsHealth and Beauty Aidsbullbull Health and Beauty AidsHealth and Beauty Aidsbullbull SolventsSolventsbullbull PesticidesPesticidesbullbull SurfactantsSurfactantsbullbull PlasticsPlastics

F i idF i idbullbull FungicidesFungicides

Ozone Water TreatmentOzone Water Treatment

Ozone Ozone -- Industrial ApplicationsIndustrial Applications-- Ultrapure Water for Pharmaceutical ApplicationsUltrapure Water for Pharmaceutical Applications

-- Wastewater disinfection color removalWastewater disinfection color removal

-- Soil and Groundwater Remediation Soil and Groundwater Remediation

-- Cooling Tower Water TreatmentCooling Tower Water Treatment

-- Food ProcessingFood Processing

-- Aquaculture AquariumsAquaculture AquariumsAquaculture AquariumsAquaculture Aquariums

-- Beverage ApplicationsBeverage Applications

P l amp P Bl hiP l amp P Bl hi-- Pulp amp Paper BleachingPulp amp Paper Bleaching

High Purity OzonationHigh Purity Ozonation

Microchip manufacturingMicrochip manufacturing

What are the current issues in large-scale gozone generationg

Experimental Setup

Front view of the two units after the redesign and reworking ofthe gas water and instruments connectionsthe gas water and instruments connections

Experimental Setup

Top view of the twoexperimental unitsexperimental unitsSpectroscope (notshown) is to the left ofthe DBD The units weredifferent with respect todifferent with respect totheir electrodes onehad only the electrodecoated with thedielectric (ldquosingle-dielectric ( single-coatedrdquo) the other onehad the electrode andthe anode coated withthe dielectric (ldquodouble-the dielectric ( double-coatedrdquo)

Basics Generation of OzoneBasics Generation of Ozone

SpectroscopyPlasma

Plasma Absorption SpectroscopyPlasma Absorption Spectroscopy

Infrared Absorption SpectroscopyInfrared Absorption Spectroscopy

IR spectra in pure oxygen (black curve) and at approximately 10wt N2 admixture (red line) N2O5 peaks appear at124 1 d 1 2 11245 cm-1 and at 1725 cm-1

Infrared Absorption SpectroscopyInfrared Absorption Spectroscopy

IR spectra of several methane variations The green curve envelopes all of the methane peaks at 1325 cm-1recorded at smaller methane admixtures Simultaneously the N2O5 peaks disappear as the methane peaks appear

N2O5 FormationN2O5 Formation2 52 5p=2 bara cwt=20degC q=35kWm2 f=1450Hz

45N2O5 AT95

30

35

40

N

2 B

lend

ing

N2O AT95N2O5 IGSN2O IGSN2O5 LGN2O LG

1 5

20

25

nt [p

pmV]

3

wt

05

10

15

NO

x co

nten

005 7 9 11 13 15 17

ozone conc [wt]

Amount of formed N2O5 and N2O as a function of ozone concentration at 3 wt of nitrogen admixture and fori l dvarious electrode arrangements

Plasma Emission SpectroscopyPlasma Emission Spectroscopyp pyp py

Relative Emissions of the Ozonizer plasmaRelative Emissions of the Ozonizer plasma

Region 300- 850 nm from individual (calibrated) regions (smoothed by PeakFit) Single-coated ozone generator Inlet side

3 5E+06

30E+06

35E+06

7 9

20E+06

25E+06

nten

sity

au

2

311 12

10E+06

15E+06

In 4

5

6 8 10

14

15

16

17

00E+00

50E+05

280 300 320 340 360 380 400 420 440 460 480 500 520 540 560 580 600 620 640 660 680 700 720 740 760 780 800 820 840 860

Wavelength nm

1 13

Wavelength nm

Absolute Emission of the DBD PlasmaAbsolute Emission of the DBD Plasma

Intensities in (O2+3 wtN2) plasma

1 20E+04

100E+04

120E+04

600E+03

800E+03

nten

sity

(au

)

200E+03

400E+03

In

O(777)

000E+00200 250 300 350 400 450 500 550 600 650 700 750 800 850

Wavelength nm

Intensities in 3 wtN2+O2 plasmaIntensities in 3 wtN2+O2 plasma

Plasma Chemistry in OzonizersPlasma Chemistry in Ozonizers

Dry Air O2 N2

e - e -

O N2 N O2

O3 NO

O2 N O2

O3

N

3

NO2

O2 O3

NO

N

NO2 O3

N2O

NO3 N

N2O4

NO2

NO2

N2O5

NO3

Primary electron-driven chemical reactions leading to the formation of N2O5 and N2O in a dry air plasma

Plasma emission diagnostics role of N2Plasma emission diagnostics role of N2

Dry Air O2 N2

e - e -

O N2 N O2

O3 NO

O2 N O2

O3

O

N

ON

NO2

O2O3

N

NO N

NO2 O3

N2O

NO3 N

N2O4

NO2

NO2

N2O5

NO3

ONbullWith N2 present ndash less oxygen atoms are formed However the difference in intensity is

very small

Modeling of plasma chemistry incl the NxOy chemistry up to N2O5 for different Oxygen Nitrogen mixtures varying power deposition scenarios

and initial ozone background concentrations (up to 15) previously done

The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation

The role of N2 must be related to its by-products reacting on the surface of the electrodeThe role of N2 must be related to its by-products reacting on the surface of the electrode

The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established

Ab 8 t f O

The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established

Ab 8 t f OAbove 8 wt of O3

1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)

Above 8 wt of O3

1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)case without pampp)

2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of the

case without pampp)

2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of thethem A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface

them A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface

The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation

Three possibilities have to be considered for the oxygen-fedozone generator

Three possibilities have to be considered for the oxygen-fedozone generatorozone generator

bull Excited N2 molecules lead to an increased O2 dissociation in

ozone generator

bull Excited N2 molecules lead to an increased O2 dissociation in2 2such case an increased efficiency is correlated to the N2admixture

2 2such case an increased efficiency is correlated to the N2admixture

bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial

bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial

bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2

bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2g p g 3 pp y 2g p g 3 pp y 2

Effect of methane on ozone efficiency and specific powerEffect of methane on ozone efficiency and specific power

Effect of Methane on Ozone Content in Outlet Gas and on Specific Power Pure O2

13 12

10

11

12

t 8

10

8

9

10

ne c

onte

nt w

t

6

8

ecifi

c po

wer

kW

hlb

5

6

7

Ozo

n

2

4 Spe

400E+00 20E+03 40E+03 60E+03 80E+03 10E+04 12E+04

Methane in feedgas ppm

0

Ozone content in the outlet gas Specif ic pow er of the ozone generatorg p p g

Effects of N2 and CH4Effects of N2 and CH4

Pi t f h t lli N O t tPicture of an amorphous-crystalline N2O5 structurecaptured at the Orlando Skylake water plant in 2006

Plasma Chemistry with CH4 Impurities

OxygenO2 N2

e - e -

CHO N2

NO2

O NO

O2 N O2 O3

NOH

CH4e-

O3 NO

NO2

O2O3NO N

NO2 O

NO2

NO2

N2ONO3

N

O3

NO2

NO

HNO3

N2O4

N2O5

NO2

NO3

N2O5

Effect of methane on the electrode surfaces

a) b)

Inlet Outlet Outlet

) d)

I l t I l t

c) d)

Electrode of the ozone generator afterseveral hours in CH8O2 and up to 2 wt of methane (a b c)

Inlet Inlet

three hours in CH8O2+traces of N2 and up to 1 wt of methane (d) Visible change of discharge character at about 13 length of electrode (a d)

Kinetics of CHx Conversion without N2

conversion by collisions

O2 + CHx 12wt O3 + CO2 +H2O

deposition vaporizationby sputtering

ibl b l 1000 CHreversible process below 1000ppm CH4

Effect of water on electrode surface with N2

Inlet

OutletOutlet

Electrode of the ozone generator after several hours in H OO N

Inlet

Electrode of the ozone generator after several hours in H2OO2N2

Effect of water on electrode surface

Long term effect (800 hrs) of H2OO2N2

Kinetics of CHx Conversion with N2

conversion by collisionsHNO3 formation

O2 + N2 +CHx 12wtO2 + CO2 +H2O + HNO3

deposition vaporizationby sputtering

H2O + HNO3

by sputtering

irreversible process above a N2 threshold () ltlt 1000ppm N2

sticky deposit

p 2 ( ) pp 2 any CH4 concentration (60ppm)

Plasma Chemistry with CH4 ImpuritiesPlasma Chemistry with CH4 Impurities4

bull Formation of NO and NO2 depends on O3 N2 and gas temperature Conclusion N2 admixture is the key factor

SummarySummaryyyThe mechanisms of formed NOx by-products follows the sameThe mechanisms of formed NOx by-products follows the sameprinciples as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentration

principles as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentrationozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)

ozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)g p ( g p )

The conversion of methane to OH and H2O is found to depend on

g p ( g p )

The conversion of methane to OH and H2O is found to depend ondissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)

dissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)discharge gap)discharge gap)

How do you optimize an ozone generatorg

Scientific ApproachScientific ApproachTheoretical Experimental

pppp

c [wt]

f [Hz]

c [wt]

f [Hz]

[kW]UUUβ1

1Cf4αPn

1iiminpeakimin

iiD

q [kWm2]q [kWm2]

150

180

][V]voltagepeakUpeak

[]cylinder perslicesofamountnsliceii

whereth

09 00

30

60

90

120

effic

ienc

y [

][0tdj t bl[F]sliceisdielectricofecapacitancC

[Hz]frequencyf[V]sliceivoltageminimumiUmin

thiD

th

10

28

46

64

82

39

107

176

244 power density

[kWm2]

ozone conc [wt][]CCβ

][0parameteradjustableα

iDiGi

Impact of Power Inductionp

350

400

wer

200

250

300

App

lied

Pow

Arr C 2Arr D +0

Arr E +45Arr F +7

Arr G +3

5 0

100

150

Frac

tion

of

1 2 3 4

ReferenceArr B unstable

Arr C -2

00

50

4Position (1inlet 4outlet)

Experimental Test Rigp g

Experimental Test Rigp g

Outer grounded electrode (left picture) and the dielectric covered inner electrodes (right) d e ect c cove ed e e ect odes ( g t)

Reference (Traditional) Arrangement

Inlet OutletGas flow direction

Optimized Arrangement

Inlet OutletGas flow direction

Intelligent Gap System (IGS)g p y ( )

Molecular Oxygen (O2) Ozone (O3)

O2 O3

yg ( 2) ( 3)

Particle Size SynthesisParticle Size SynthesisByBy--Products Cluster FormationProducts Cluster Formationyy

high diffusion and deposition to surfaces

low diffusion rate good transport

high sedimentation on the structurehigh sedimentation on the structure

Degreacutemont Technologies ndash OzoniaIntelligent Gap SystemIntelligent Gap System

G Vezzuacute JL Lopez A Freilich and K Becker Optimizationof Large-Scale Ozone Generators IEEE Transactions onPlasma Science Vol 37 No 6 p 890-896 (2009)

ConclusionsConclusionsConclusionsConclusionsFundamentals of ozone synthesis in a DBD plasmay p

ndash Highly filamented DBD discharges are best-suitedfor the production of ozone concentrations in therange of 6 to 14 wtrange of 6 to 14 wt

ndash The preferred characteristic of the microdischargesare Townsend-like at reduced electric fields Enaround 190 Townsend

ndash Detrimental side-effects induced by by-productscan be avoided by a proper design of the electrodecan be avoided by a proper design of the electrodearrangement The phenomenon is related to thediffusion rates of formed by-product clusters

ConclusionsConclusionsConclusionsConclusionsBenefits from DBD microplasma tailoring

ndash Reduced power consumption of up to 10 improvement

ndash Increased ozone concentrations of up to 14 now achievable

ndash Improved neutralization and conditioning of detrimental by-products

ndash Reduced system capital and operational cost

New technologies to improve ozone p

generatorg

HV Pulsed Power SwitchingHV Pulsed Power Switching

Microchannel Generation of Ozone

Channel ArrayChannel Array

Microchannel

330 microm 230 microm

Some Cap-DBD Devices Operating in Air

Increase of 60 of

Spacing 225 μmof 60 of plasma

No space

Cap‐DBD ozone generation

bull Ozone concentration is evaluated via Eco S d l UV 100 O A l (0 01Sensors model UV-100 Ozone Analyzer (001 ndash 900 ppm wiht an accuracy of plusmn2)

bull Three reactors 6 tubings 6rdquo with spacings of 0 μm 225 μm and 500 μm running at 3 kV μ μ μ g

SpacingOzone Concentration

3 kV rms 4 kV rms3 kV rms 4 kV rms

0 μm 660 ppm

225 μm 550 ppm

For a device of such small scale these ozone levels are promising

500 μm 380 ppm

J Mahoney W Zhu VS Johnson KH Becker and JL Lopez Electrical and optical emissionmeasurements of a capillary dielectric barrier discharge European Physics Journal D Vol 60 441-447(2010)

QuestionsQuestions

Thank YouFor more informationProf Jose L Lopez PhD

Thank YouFor more informationDepartment of Physics

Telephone (973) 761-9057Email joselopez1shuedu

Website wwwshueduacademicsartsciphysicsWebsite wwwshueduacademicsartsciphysics

Page 56: Dielectric Barrier Discharge (DBD) & Progress in Large ...bonitz/si12/talks/august_8/lopez_si12.pdf · Dielectric Barrier Discharge (DBD) & Progress in Large-Scale Ozone Generation

Micro-organism DNA

Capsule AdenineAdenine

Cell wall ThymineThymine

CytosineCytosine

GuanineGuanine

NuclearmaterialCellmembrane

material

Typical Bacterium DNA

Microbial Growth at Various Ozone ConcentrationsConcentrations

Growth likely

Growth possibleGrowth possible

NO GROWTH

0004 0008 0012 0016 0020

Ozone concentration (mgl)Ozone concentration (mgl)

Typical Water Treatment UsageTypical Water Treatment Usage

Application O3 mgl Contact timeUltra Pure Water 005 - 025 sec ndash min

Water bottling 04 ndash 10 5 ndash 10 min

Swimming pools ampspas

01 ndash 075 4 minutes

Potable taste amp odor 15 ndash 50 5 ndash 10 mindisinfection

Microfloculation 10 ndash 30 5 ndash 10 min

Lignin amp tammin 3 0 10 0 10 30 minLignin amp tamminremoval

30 ndash 100 10 ndash 30 min

Municipal wastewater 50 ndash 150+ 15 ndash 30 min

Ozone Water TreatmentOzone Water TreatmentOzone Ozone ndashndash Municipal ApplicationsMunicipal Applications

bullbull Taste and OdorTaste and Odor

bullbull Color RemovalColor Removal

bullbull Disinfection Without Trihalomethanes (THMs)Disinfection Without Trihalomethanes (THMs)

bullbull Improved Filtration Efficiency and FlocculationImproved Filtration Efficiency and Flocculation

bullbull Cryptosporidium DeactivationCryptosporidium Deactivation

bullbull Giardia amp Virus InactivationGiardia amp Virus Inactivation

bullbull Oxidation Oxidation -- Organics Fe amp MnOrganics Fe amp Mn

bullbull Wastewater disinfectionWastewater disinfection

bullbull BOD COD and TOC reductionBOD COD and TOC reduction

Applications of Ozone

Wastewater Treatmentbull Disinfection of Secondary and Tertiary Effluentsbull Color Reductionbull Color Reductionbull TOC Oxidation (Industrial)bull Oxidation of Odor Causing Compoundsbull Oxidation of Endocrine Disruptors (EDCrsquos) and p ( )

Pharmaceutically Active Compounds (PACrsquos)

Applications of Ozone

What are Endocrine Disruptors (EDCrsquos) and What are Endocrine Disruptors (EDCrsquos) and Ph ti ll A ti C d (PACrsquo )Ph ti ll A ti C d (PACrsquo )Pharmaceutically Active Compounds (PACrsquos)Pharmaceutically Active Compounds (PACrsquos)

bullbull EDCrsquosEDCrsquos andand PACrsquosPACrsquos areare NaturallyNaturally andand SyntheticSyntheticdd th tth t ff tff t thth b lb l llcompoundscompounds thatthat maymay affectaffect thethe balancebalance oror normalnormal

functionsfunctions inin animalsanimals andand humanshumans

What can EDCrsquos and PACrsquos doWhat can EDCrsquos and PACrsquos do

bullbull Even in very small concentrations these compounds Even in very small concentrations these compounds y py pcan can disruptdisrupt normal bodily functionsnormal bodily functions

bullbull ManMan--made chemicals can trick the bodies endocrine made chemicals can trick the bodies endocrine system system

Applications of Ozone

Examples of Endocrine Disruptors1000rsquos of compounds that may be Investigated as EDCs ndash Some examples are

bullbull Synthetic HormonesSynthetic Hormonesbullbull Naturally Occurring Estrogens Naturally Occurring Estrogens

Health and Beauty AidsHealth and Beauty Aidsbullbull Health and Beauty AidsHealth and Beauty Aidsbullbull SolventsSolventsbullbull PesticidesPesticidesbullbull SurfactantsSurfactantsbullbull PlasticsPlastics

F i idF i idbullbull FungicidesFungicides

Ozone Water TreatmentOzone Water Treatment

Ozone Ozone -- Industrial ApplicationsIndustrial Applications-- Ultrapure Water for Pharmaceutical ApplicationsUltrapure Water for Pharmaceutical Applications

-- Wastewater disinfection color removalWastewater disinfection color removal

-- Soil and Groundwater Remediation Soil and Groundwater Remediation

-- Cooling Tower Water TreatmentCooling Tower Water Treatment

-- Food ProcessingFood Processing

-- Aquaculture AquariumsAquaculture AquariumsAquaculture AquariumsAquaculture Aquariums

-- Beverage ApplicationsBeverage Applications

P l amp P Bl hiP l amp P Bl hi-- Pulp amp Paper BleachingPulp amp Paper Bleaching

High Purity OzonationHigh Purity Ozonation

Microchip manufacturingMicrochip manufacturing

What are the current issues in large-scale gozone generationg

Experimental Setup

Front view of the two units after the redesign and reworking ofthe gas water and instruments connectionsthe gas water and instruments connections

Experimental Setup

Top view of the twoexperimental unitsexperimental unitsSpectroscope (notshown) is to the left ofthe DBD The units weredifferent with respect todifferent with respect totheir electrodes onehad only the electrodecoated with thedielectric (ldquosingle-dielectric ( single-coatedrdquo) the other onehad the electrode andthe anode coated withthe dielectric (ldquodouble-the dielectric ( double-coatedrdquo)

Basics Generation of OzoneBasics Generation of Ozone

SpectroscopyPlasma

Plasma Absorption SpectroscopyPlasma Absorption Spectroscopy

Infrared Absorption SpectroscopyInfrared Absorption Spectroscopy

IR spectra in pure oxygen (black curve) and at approximately 10wt N2 admixture (red line) N2O5 peaks appear at124 1 d 1 2 11245 cm-1 and at 1725 cm-1

Infrared Absorption SpectroscopyInfrared Absorption Spectroscopy

IR spectra of several methane variations The green curve envelopes all of the methane peaks at 1325 cm-1recorded at smaller methane admixtures Simultaneously the N2O5 peaks disappear as the methane peaks appear

N2O5 FormationN2O5 Formation2 52 5p=2 bara cwt=20degC q=35kWm2 f=1450Hz

45N2O5 AT95

30

35

40

N

2 B

lend

ing

N2O AT95N2O5 IGSN2O IGSN2O5 LGN2O LG

1 5

20

25

nt [p

pmV]

3

wt

05

10

15

NO

x co

nten

005 7 9 11 13 15 17

ozone conc [wt]

Amount of formed N2O5 and N2O as a function of ozone concentration at 3 wt of nitrogen admixture and fori l dvarious electrode arrangements

Plasma Emission SpectroscopyPlasma Emission Spectroscopyp pyp py

Relative Emissions of the Ozonizer plasmaRelative Emissions of the Ozonizer plasma

Region 300- 850 nm from individual (calibrated) regions (smoothed by PeakFit) Single-coated ozone generator Inlet side

3 5E+06

30E+06

35E+06

7 9

20E+06

25E+06

nten

sity

au

2

311 12

10E+06

15E+06

In 4

5

6 8 10

14

15

16

17

00E+00

50E+05

280 300 320 340 360 380 400 420 440 460 480 500 520 540 560 580 600 620 640 660 680 700 720 740 760 780 800 820 840 860

Wavelength nm

1 13

Wavelength nm

Absolute Emission of the DBD PlasmaAbsolute Emission of the DBD Plasma

Intensities in (O2+3 wtN2) plasma

1 20E+04

100E+04

120E+04

600E+03

800E+03

nten

sity

(au

)

200E+03

400E+03

In

O(777)

000E+00200 250 300 350 400 450 500 550 600 650 700 750 800 850

Wavelength nm

Intensities in 3 wtN2+O2 plasmaIntensities in 3 wtN2+O2 plasma

Plasma Chemistry in OzonizersPlasma Chemistry in Ozonizers

Dry Air O2 N2

e - e -

O N2 N O2

O3 NO

O2 N O2

O3

N

3

NO2

O2 O3

NO

N

NO2 O3

N2O

NO3 N

N2O4

NO2

NO2

N2O5

NO3

Primary electron-driven chemical reactions leading to the formation of N2O5 and N2O in a dry air plasma

Plasma emission diagnostics role of N2Plasma emission diagnostics role of N2

Dry Air O2 N2

e - e -

O N2 N O2

O3 NO

O2 N O2

O3

O

N

ON

NO2

O2O3

N

NO N

NO2 O3

N2O

NO3 N

N2O4

NO2

NO2

N2O5

NO3

ONbullWith N2 present ndash less oxygen atoms are formed However the difference in intensity is

very small

Modeling of plasma chemistry incl the NxOy chemistry up to N2O5 for different Oxygen Nitrogen mixtures varying power deposition scenarios

and initial ozone background concentrations (up to 15) previously done

The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation

The role of N2 must be related to its by-products reacting on the surface of the electrodeThe role of N2 must be related to its by-products reacting on the surface of the electrode

The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established

Ab 8 t f O

The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established

Ab 8 t f OAbove 8 wt of O3

1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)

Above 8 wt of O3

1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)case without pampp)

2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of the

case without pampp)

2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of thethem A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface

them A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface

The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation

Three possibilities have to be considered for the oxygen-fedozone generator

Three possibilities have to be considered for the oxygen-fedozone generatorozone generator

bull Excited N2 molecules lead to an increased O2 dissociation in

ozone generator

bull Excited N2 molecules lead to an increased O2 dissociation in2 2such case an increased efficiency is correlated to the N2admixture

2 2such case an increased efficiency is correlated to the N2admixture

bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial

bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial

bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2

bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2g p g 3 pp y 2g p g 3 pp y 2

Effect of methane on ozone efficiency and specific powerEffect of methane on ozone efficiency and specific power

Effect of Methane on Ozone Content in Outlet Gas and on Specific Power Pure O2

13 12

10

11

12

t 8

10

8

9

10

ne c

onte

nt w

t

6

8

ecifi

c po

wer

kW

hlb

5

6

7

Ozo

n

2

4 Spe

400E+00 20E+03 40E+03 60E+03 80E+03 10E+04 12E+04

Methane in feedgas ppm

0

Ozone content in the outlet gas Specif ic pow er of the ozone generatorg p p g

Effects of N2 and CH4Effects of N2 and CH4

Pi t f h t lli N O t tPicture of an amorphous-crystalline N2O5 structurecaptured at the Orlando Skylake water plant in 2006

Plasma Chemistry with CH4 Impurities

OxygenO2 N2

e - e -

CHO N2

NO2

O NO

O2 N O2 O3

NOH

CH4e-

O3 NO

NO2

O2O3NO N

NO2 O

NO2

NO2

N2ONO3

N

O3

NO2

NO

HNO3

N2O4

N2O5

NO2

NO3

N2O5

Effect of methane on the electrode surfaces

a) b)

Inlet Outlet Outlet

) d)

I l t I l t

c) d)

Electrode of the ozone generator afterseveral hours in CH8O2 and up to 2 wt of methane (a b c)

Inlet Inlet

three hours in CH8O2+traces of N2 and up to 1 wt of methane (d) Visible change of discharge character at about 13 length of electrode (a d)

Kinetics of CHx Conversion without N2

conversion by collisions

O2 + CHx 12wt O3 + CO2 +H2O

deposition vaporizationby sputtering

ibl b l 1000 CHreversible process below 1000ppm CH4

Effect of water on electrode surface with N2

Inlet

OutletOutlet

Electrode of the ozone generator after several hours in H OO N

Inlet

Electrode of the ozone generator after several hours in H2OO2N2

Effect of water on electrode surface

Long term effect (800 hrs) of H2OO2N2

Kinetics of CHx Conversion with N2

conversion by collisionsHNO3 formation

O2 + N2 +CHx 12wtO2 + CO2 +H2O + HNO3

deposition vaporizationby sputtering

H2O + HNO3

by sputtering

irreversible process above a N2 threshold () ltlt 1000ppm N2

sticky deposit

p 2 ( ) pp 2 any CH4 concentration (60ppm)

Plasma Chemistry with CH4 ImpuritiesPlasma Chemistry with CH4 Impurities4

bull Formation of NO and NO2 depends on O3 N2 and gas temperature Conclusion N2 admixture is the key factor

SummarySummaryyyThe mechanisms of formed NOx by-products follows the sameThe mechanisms of formed NOx by-products follows the sameprinciples as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentration

principles as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentrationozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)

ozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)g p ( g p )

The conversion of methane to OH and H2O is found to depend on

g p ( g p )

The conversion of methane to OH and H2O is found to depend ondissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)

dissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)discharge gap)discharge gap)

How do you optimize an ozone generatorg

Scientific ApproachScientific ApproachTheoretical Experimental

pppp

c [wt]

f [Hz]

c [wt]

f [Hz]

[kW]UUUβ1

1Cf4αPn

1iiminpeakimin

iiD

q [kWm2]q [kWm2]

150

180

][V]voltagepeakUpeak

[]cylinder perslicesofamountnsliceii

whereth

09 00

30

60

90

120

effic

ienc

y [

][0tdj t bl[F]sliceisdielectricofecapacitancC

[Hz]frequencyf[V]sliceivoltageminimumiUmin

thiD

th

10

28

46

64

82

39

107

176

244 power density

[kWm2]

ozone conc [wt][]CCβ

][0parameteradjustableα

iDiGi

Impact of Power Inductionp

350

400

wer

200

250

300

App

lied

Pow

Arr C 2Arr D +0

Arr E +45Arr F +7

Arr G +3

5 0

100

150

Frac

tion

of

1 2 3 4

ReferenceArr B unstable

Arr C -2

00

50

4Position (1inlet 4outlet)

Experimental Test Rigp g

Experimental Test Rigp g

Outer grounded electrode (left picture) and the dielectric covered inner electrodes (right) d e ect c cove ed e e ect odes ( g t)

Reference (Traditional) Arrangement

Inlet OutletGas flow direction

Optimized Arrangement

Inlet OutletGas flow direction

Intelligent Gap System (IGS)g p y ( )

Molecular Oxygen (O2) Ozone (O3)

O2 O3

yg ( 2) ( 3)

Particle Size SynthesisParticle Size SynthesisByBy--Products Cluster FormationProducts Cluster Formationyy

high diffusion and deposition to surfaces

low diffusion rate good transport

high sedimentation on the structurehigh sedimentation on the structure

Degreacutemont Technologies ndash OzoniaIntelligent Gap SystemIntelligent Gap System

G Vezzuacute JL Lopez A Freilich and K Becker Optimizationof Large-Scale Ozone Generators IEEE Transactions onPlasma Science Vol 37 No 6 p 890-896 (2009)

ConclusionsConclusionsConclusionsConclusionsFundamentals of ozone synthesis in a DBD plasmay p

ndash Highly filamented DBD discharges are best-suitedfor the production of ozone concentrations in therange of 6 to 14 wtrange of 6 to 14 wt

ndash The preferred characteristic of the microdischargesare Townsend-like at reduced electric fields Enaround 190 Townsend

ndash Detrimental side-effects induced by by-productscan be avoided by a proper design of the electrodecan be avoided by a proper design of the electrodearrangement The phenomenon is related to thediffusion rates of formed by-product clusters

ConclusionsConclusionsConclusionsConclusionsBenefits from DBD microplasma tailoring

ndash Reduced power consumption of up to 10 improvement

ndash Increased ozone concentrations of up to 14 now achievable

ndash Improved neutralization and conditioning of detrimental by-products

ndash Reduced system capital and operational cost

New technologies to improve ozone p

generatorg

HV Pulsed Power SwitchingHV Pulsed Power Switching

Microchannel Generation of Ozone

Channel ArrayChannel Array

Microchannel

330 microm 230 microm

Some Cap-DBD Devices Operating in Air

Increase of 60 of

Spacing 225 μmof 60 of plasma

No space

Cap‐DBD ozone generation

bull Ozone concentration is evaluated via Eco S d l UV 100 O A l (0 01Sensors model UV-100 Ozone Analyzer (001 ndash 900 ppm wiht an accuracy of plusmn2)

bull Three reactors 6 tubings 6rdquo with spacings of 0 μm 225 μm and 500 μm running at 3 kV μ μ μ g

SpacingOzone Concentration

3 kV rms 4 kV rms3 kV rms 4 kV rms

0 μm 660 ppm

225 μm 550 ppm

For a device of such small scale these ozone levels are promising

500 μm 380 ppm

J Mahoney W Zhu VS Johnson KH Becker and JL Lopez Electrical and optical emissionmeasurements of a capillary dielectric barrier discharge European Physics Journal D Vol 60 441-447(2010)

QuestionsQuestions

Thank YouFor more informationProf Jose L Lopez PhD

Thank YouFor more informationDepartment of Physics

Telephone (973) 761-9057Email joselopez1shuedu

Website wwwshueduacademicsartsciphysicsWebsite wwwshueduacademicsartsciphysics

Page 57: Dielectric Barrier Discharge (DBD) & Progress in Large ...bonitz/si12/talks/august_8/lopez_si12.pdf · Dielectric Barrier Discharge (DBD) & Progress in Large-Scale Ozone Generation

Microbial Growth at Various Ozone ConcentrationsConcentrations

Growth likely

Growth possibleGrowth possible

NO GROWTH

0004 0008 0012 0016 0020

Ozone concentration (mgl)Ozone concentration (mgl)

Typical Water Treatment UsageTypical Water Treatment Usage

Application O3 mgl Contact timeUltra Pure Water 005 - 025 sec ndash min

Water bottling 04 ndash 10 5 ndash 10 min

Swimming pools ampspas

01 ndash 075 4 minutes

Potable taste amp odor 15 ndash 50 5 ndash 10 mindisinfection

Microfloculation 10 ndash 30 5 ndash 10 min

Lignin amp tammin 3 0 10 0 10 30 minLignin amp tamminremoval

30 ndash 100 10 ndash 30 min

Municipal wastewater 50 ndash 150+ 15 ndash 30 min

Ozone Water TreatmentOzone Water TreatmentOzone Ozone ndashndash Municipal ApplicationsMunicipal Applications

bullbull Taste and OdorTaste and Odor

bullbull Color RemovalColor Removal

bullbull Disinfection Without Trihalomethanes (THMs)Disinfection Without Trihalomethanes (THMs)

bullbull Improved Filtration Efficiency and FlocculationImproved Filtration Efficiency and Flocculation

bullbull Cryptosporidium DeactivationCryptosporidium Deactivation

bullbull Giardia amp Virus InactivationGiardia amp Virus Inactivation

bullbull Oxidation Oxidation -- Organics Fe amp MnOrganics Fe amp Mn

bullbull Wastewater disinfectionWastewater disinfection

bullbull BOD COD and TOC reductionBOD COD and TOC reduction

Applications of Ozone

Wastewater Treatmentbull Disinfection of Secondary and Tertiary Effluentsbull Color Reductionbull Color Reductionbull TOC Oxidation (Industrial)bull Oxidation of Odor Causing Compoundsbull Oxidation of Endocrine Disruptors (EDCrsquos) and p ( )

Pharmaceutically Active Compounds (PACrsquos)

Applications of Ozone

What are Endocrine Disruptors (EDCrsquos) and What are Endocrine Disruptors (EDCrsquos) and Ph ti ll A ti C d (PACrsquo )Ph ti ll A ti C d (PACrsquo )Pharmaceutically Active Compounds (PACrsquos)Pharmaceutically Active Compounds (PACrsquos)

bullbull EDCrsquosEDCrsquos andand PACrsquosPACrsquos areare NaturallyNaturally andand SyntheticSyntheticdd th tth t ff tff t thth b lb l llcompoundscompounds thatthat maymay affectaffect thethe balancebalance oror normalnormal

functionsfunctions inin animalsanimals andand humanshumans

What can EDCrsquos and PACrsquos doWhat can EDCrsquos and PACrsquos do

bullbull Even in very small concentrations these compounds Even in very small concentrations these compounds y py pcan can disruptdisrupt normal bodily functionsnormal bodily functions

bullbull ManMan--made chemicals can trick the bodies endocrine made chemicals can trick the bodies endocrine system system

Applications of Ozone

Examples of Endocrine Disruptors1000rsquos of compounds that may be Investigated as EDCs ndash Some examples are

bullbull Synthetic HormonesSynthetic Hormonesbullbull Naturally Occurring Estrogens Naturally Occurring Estrogens

Health and Beauty AidsHealth and Beauty Aidsbullbull Health and Beauty AidsHealth and Beauty Aidsbullbull SolventsSolventsbullbull PesticidesPesticidesbullbull SurfactantsSurfactantsbullbull PlasticsPlastics

F i idF i idbullbull FungicidesFungicides

Ozone Water TreatmentOzone Water Treatment

Ozone Ozone -- Industrial ApplicationsIndustrial Applications-- Ultrapure Water for Pharmaceutical ApplicationsUltrapure Water for Pharmaceutical Applications

-- Wastewater disinfection color removalWastewater disinfection color removal

-- Soil and Groundwater Remediation Soil and Groundwater Remediation

-- Cooling Tower Water TreatmentCooling Tower Water Treatment

-- Food ProcessingFood Processing

-- Aquaculture AquariumsAquaculture AquariumsAquaculture AquariumsAquaculture Aquariums

-- Beverage ApplicationsBeverage Applications

P l amp P Bl hiP l amp P Bl hi-- Pulp amp Paper BleachingPulp amp Paper Bleaching

High Purity OzonationHigh Purity Ozonation

Microchip manufacturingMicrochip manufacturing

What are the current issues in large-scale gozone generationg

Experimental Setup

Front view of the two units after the redesign and reworking ofthe gas water and instruments connectionsthe gas water and instruments connections

Experimental Setup

Top view of the twoexperimental unitsexperimental unitsSpectroscope (notshown) is to the left ofthe DBD The units weredifferent with respect todifferent with respect totheir electrodes onehad only the electrodecoated with thedielectric (ldquosingle-dielectric ( single-coatedrdquo) the other onehad the electrode andthe anode coated withthe dielectric (ldquodouble-the dielectric ( double-coatedrdquo)

Basics Generation of OzoneBasics Generation of Ozone

SpectroscopyPlasma

Plasma Absorption SpectroscopyPlasma Absorption Spectroscopy

Infrared Absorption SpectroscopyInfrared Absorption Spectroscopy

IR spectra in pure oxygen (black curve) and at approximately 10wt N2 admixture (red line) N2O5 peaks appear at124 1 d 1 2 11245 cm-1 and at 1725 cm-1

Infrared Absorption SpectroscopyInfrared Absorption Spectroscopy

IR spectra of several methane variations The green curve envelopes all of the methane peaks at 1325 cm-1recorded at smaller methane admixtures Simultaneously the N2O5 peaks disappear as the methane peaks appear

N2O5 FormationN2O5 Formation2 52 5p=2 bara cwt=20degC q=35kWm2 f=1450Hz

45N2O5 AT95

30

35

40

N

2 B

lend

ing

N2O AT95N2O5 IGSN2O IGSN2O5 LGN2O LG

1 5

20

25

nt [p

pmV]

3

wt

05

10

15

NO

x co

nten

005 7 9 11 13 15 17

ozone conc [wt]

Amount of formed N2O5 and N2O as a function of ozone concentration at 3 wt of nitrogen admixture and fori l dvarious electrode arrangements

Plasma Emission SpectroscopyPlasma Emission Spectroscopyp pyp py

Relative Emissions of the Ozonizer plasmaRelative Emissions of the Ozonizer plasma

Region 300- 850 nm from individual (calibrated) regions (smoothed by PeakFit) Single-coated ozone generator Inlet side

3 5E+06

30E+06

35E+06

7 9

20E+06

25E+06

nten

sity

au

2

311 12

10E+06

15E+06

In 4

5

6 8 10

14

15

16

17

00E+00

50E+05

280 300 320 340 360 380 400 420 440 460 480 500 520 540 560 580 600 620 640 660 680 700 720 740 760 780 800 820 840 860

Wavelength nm

1 13

Wavelength nm

Absolute Emission of the DBD PlasmaAbsolute Emission of the DBD Plasma

Intensities in (O2+3 wtN2) plasma

1 20E+04

100E+04

120E+04

600E+03

800E+03

nten

sity

(au

)

200E+03

400E+03

In

O(777)

000E+00200 250 300 350 400 450 500 550 600 650 700 750 800 850

Wavelength nm

Intensities in 3 wtN2+O2 plasmaIntensities in 3 wtN2+O2 plasma

Plasma Chemistry in OzonizersPlasma Chemistry in Ozonizers

Dry Air O2 N2

e - e -

O N2 N O2

O3 NO

O2 N O2

O3

N

3

NO2

O2 O3

NO

N

NO2 O3

N2O

NO3 N

N2O4

NO2

NO2

N2O5

NO3

Primary electron-driven chemical reactions leading to the formation of N2O5 and N2O in a dry air plasma

Plasma emission diagnostics role of N2Plasma emission diagnostics role of N2

Dry Air O2 N2

e - e -

O N2 N O2

O3 NO

O2 N O2

O3

O

N

ON

NO2

O2O3

N

NO N

NO2 O3

N2O

NO3 N

N2O4

NO2

NO2

N2O5

NO3

ONbullWith N2 present ndash less oxygen atoms are formed However the difference in intensity is

very small

Modeling of plasma chemistry incl the NxOy chemistry up to N2O5 for different Oxygen Nitrogen mixtures varying power deposition scenarios

and initial ozone background concentrations (up to 15) previously done

The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation

The role of N2 must be related to its by-products reacting on the surface of the electrodeThe role of N2 must be related to its by-products reacting on the surface of the electrode

The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established

Ab 8 t f O

The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established

Ab 8 t f OAbove 8 wt of O3

1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)

Above 8 wt of O3

1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)case without pampp)

2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of the

case without pampp)

2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of thethem A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface

them A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface

The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation

Three possibilities have to be considered for the oxygen-fedozone generator

Three possibilities have to be considered for the oxygen-fedozone generatorozone generator

bull Excited N2 molecules lead to an increased O2 dissociation in

ozone generator

bull Excited N2 molecules lead to an increased O2 dissociation in2 2such case an increased efficiency is correlated to the N2admixture

2 2such case an increased efficiency is correlated to the N2admixture

bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial

bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial

bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2

bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2g p g 3 pp y 2g p g 3 pp y 2

Effect of methane on ozone efficiency and specific powerEffect of methane on ozone efficiency and specific power

Effect of Methane on Ozone Content in Outlet Gas and on Specific Power Pure O2

13 12

10

11

12

t 8

10

8

9

10

ne c

onte

nt w

t

6

8

ecifi

c po

wer

kW

hlb

5

6

7

Ozo

n

2

4 Spe

400E+00 20E+03 40E+03 60E+03 80E+03 10E+04 12E+04

Methane in feedgas ppm

0

Ozone content in the outlet gas Specif ic pow er of the ozone generatorg p p g

Effects of N2 and CH4Effects of N2 and CH4

Pi t f h t lli N O t tPicture of an amorphous-crystalline N2O5 structurecaptured at the Orlando Skylake water plant in 2006

Plasma Chemistry with CH4 Impurities

OxygenO2 N2

e - e -

CHO N2

NO2

O NO

O2 N O2 O3

NOH

CH4e-

O3 NO

NO2

O2O3NO N

NO2 O

NO2

NO2

N2ONO3

N

O3

NO2

NO

HNO3

N2O4

N2O5

NO2

NO3

N2O5

Effect of methane on the electrode surfaces

a) b)

Inlet Outlet Outlet

) d)

I l t I l t

c) d)

Electrode of the ozone generator afterseveral hours in CH8O2 and up to 2 wt of methane (a b c)

Inlet Inlet

three hours in CH8O2+traces of N2 and up to 1 wt of methane (d) Visible change of discharge character at about 13 length of electrode (a d)

Kinetics of CHx Conversion without N2

conversion by collisions

O2 + CHx 12wt O3 + CO2 +H2O

deposition vaporizationby sputtering

ibl b l 1000 CHreversible process below 1000ppm CH4

Effect of water on electrode surface with N2

Inlet

OutletOutlet

Electrode of the ozone generator after several hours in H OO N

Inlet

Electrode of the ozone generator after several hours in H2OO2N2

Effect of water on electrode surface

Long term effect (800 hrs) of H2OO2N2

Kinetics of CHx Conversion with N2

conversion by collisionsHNO3 formation

O2 + N2 +CHx 12wtO2 + CO2 +H2O + HNO3

deposition vaporizationby sputtering

H2O + HNO3

by sputtering

irreversible process above a N2 threshold () ltlt 1000ppm N2

sticky deposit

p 2 ( ) pp 2 any CH4 concentration (60ppm)

Plasma Chemistry with CH4 ImpuritiesPlasma Chemistry with CH4 Impurities4

bull Formation of NO and NO2 depends on O3 N2 and gas temperature Conclusion N2 admixture is the key factor

SummarySummaryyyThe mechanisms of formed NOx by-products follows the sameThe mechanisms of formed NOx by-products follows the sameprinciples as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentration

principles as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentrationozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)

ozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)g p ( g p )

The conversion of methane to OH and H2O is found to depend on

g p ( g p )

The conversion of methane to OH and H2O is found to depend ondissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)

dissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)discharge gap)discharge gap)

How do you optimize an ozone generatorg

Scientific ApproachScientific ApproachTheoretical Experimental

pppp

c [wt]

f [Hz]

c [wt]

f [Hz]

[kW]UUUβ1

1Cf4αPn

1iiminpeakimin

iiD

q [kWm2]q [kWm2]

150

180

][V]voltagepeakUpeak

[]cylinder perslicesofamountnsliceii

whereth

09 00

30

60

90

120

effic

ienc

y [

][0tdj t bl[F]sliceisdielectricofecapacitancC

[Hz]frequencyf[V]sliceivoltageminimumiUmin

thiD

th

10

28

46

64

82

39

107

176

244 power density

[kWm2]

ozone conc [wt][]CCβ

][0parameteradjustableα

iDiGi

Impact of Power Inductionp

350

400

wer

200

250

300

App

lied

Pow

Arr C 2Arr D +0

Arr E +45Arr F +7

Arr G +3

5 0

100

150

Frac

tion

of

1 2 3 4

ReferenceArr B unstable

Arr C -2

00

50

4Position (1inlet 4outlet)

Experimental Test Rigp g

Experimental Test Rigp g

Outer grounded electrode (left picture) and the dielectric covered inner electrodes (right) d e ect c cove ed e e ect odes ( g t)

Reference (Traditional) Arrangement

Inlet OutletGas flow direction

Optimized Arrangement

Inlet OutletGas flow direction

Intelligent Gap System (IGS)g p y ( )

Molecular Oxygen (O2) Ozone (O3)

O2 O3

yg ( 2) ( 3)

Particle Size SynthesisParticle Size SynthesisByBy--Products Cluster FormationProducts Cluster Formationyy

high diffusion and deposition to surfaces

low diffusion rate good transport

high sedimentation on the structurehigh sedimentation on the structure

Degreacutemont Technologies ndash OzoniaIntelligent Gap SystemIntelligent Gap System

G Vezzuacute JL Lopez A Freilich and K Becker Optimizationof Large-Scale Ozone Generators IEEE Transactions onPlasma Science Vol 37 No 6 p 890-896 (2009)

ConclusionsConclusionsConclusionsConclusionsFundamentals of ozone synthesis in a DBD plasmay p

ndash Highly filamented DBD discharges are best-suitedfor the production of ozone concentrations in therange of 6 to 14 wtrange of 6 to 14 wt

ndash The preferred characteristic of the microdischargesare Townsend-like at reduced electric fields Enaround 190 Townsend

ndash Detrimental side-effects induced by by-productscan be avoided by a proper design of the electrodecan be avoided by a proper design of the electrodearrangement The phenomenon is related to thediffusion rates of formed by-product clusters

ConclusionsConclusionsConclusionsConclusionsBenefits from DBD microplasma tailoring

ndash Reduced power consumption of up to 10 improvement

ndash Increased ozone concentrations of up to 14 now achievable

ndash Improved neutralization and conditioning of detrimental by-products

ndash Reduced system capital and operational cost

New technologies to improve ozone p

generatorg

HV Pulsed Power SwitchingHV Pulsed Power Switching

Microchannel Generation of Ozone

Channel ArrayChannel Array

Microchannel

330 microm 230 microm

Some Cap-DBD Devices Operating in Air

Increase of 60 of

Spacing 225 μmof 60 of plasma

No space

Cap‐DBD ozone generation

bull Ozone concentration is evaluated via Eco S d l UV 100 O A l (0 01Sensors model UV-100 Ozone Analyzer (001 ndash 900 ppm wiht an accuracy of plusmn2)

bull Three reactors 6 tubings 6rdquo with spacings of 0 μm 225 μm and 500 μm running at 3 kV μ μ μ g

SpacingOzone Concentration

3 kV rms 4 kV rms3 kV rms 4 kV rms

0 μm 660 ppm

225 μm 550 ppm

For a device of such small scale these ozone levels are promising

500 μm 380 ppm

J Mahoney W Zhu VS Johnson KH Becker and JL Lopez Electrical and optical emissionmeasurements of a capillary dielectric barrier discharge European Physics Journal D Vol 60 441-447(2010)

QuestionsQuestions

Thank YouFor more informationProf Jose L Lopez PhD

Thank YouFor more informationDepartment of Physics

Telephone (973) 761-9057Email joselopez1shuedu

Website wwwshueduacademicsartsciphysicsWebsite wwwshueduacademicsartsciphysics

Page 58: Dielectric Barrier Discharge (DBD) & Progress in Large ...bonitz/si12/talks/august_8/lopez_si12.pdf · Dielectric Barrier Discharge (DBD) & Progress in Large-Scale Ozone Generation

Typical Water Treatment UsageTypical Water Treatment Usage

Application O3 mgl Contact timeUltra Pure Water 005 - 025 sec ndash min

Water bottling 04 ndash 10 5 ndash 10 min

Swimming pools ampspas

01 ndash 075 4 minutes

Potable taste amp odor 15 ndash 50 5 ndash 10 mindisinfection

Microfloculation 10 ndash 30 5 ndash 10 min

Lignin amp tammin 3 0 10 0 10 30 minLignin amp tamminremoval

30 ndash 100 10 ndash 30 min

Municipal wastewater 50 ndash 150+ 15 ndash 30 min

Ozone Water TreatmentOzone Water TreatmentOzone Ozone ndashndash Municipal ApplicationsMunicipal Applications

bullbull Taste and OdorTaste and Odor

bullbull Color RemovalColor Removal

bullbull Disinfection Without Trihalomethanes (THMs)Disinfection Without Trihalomethanes (THMs)

bullbull Improved Filtration Efficiency and FlocculationImproved Filtration Efficiency and Flocculation

bullbull Cryptosporidium DeactivationCryptosporidium Deactivation

bullbull Giardia amp Virus InactivationGiardia amp Virus Inactivation

bullbull Oxidation Oxidation -- Organics Fe amp MnOrganics Fe amp Mn

bullbull Wastewater disinfectionWastewater disinfection

bullbull BOD COD and TOC reductionBOD COD and TOC reduction

Applications of Ozone

Wastewater Treatmentbull Disinfection of Secondary and Tertiary Effluentsbull Color Reductionbull Color Reductionbull TOC Oxidation (Industrial)bull Oxidation of Odor Causing Compoundsbull Oxidation of Endocrine Disruptors (EDCrsquos) and p ( )

Pharmaceutically Active Compounds (PACrsquos)

Applications of Ozone

What are Endocrine Disruptors (EDCrsquos) and What are Endocrine Disruptors (EDCrsquos) and Ph ti ll A ti C d (PACrsquo )Ph ti ll A ti C d (PACrsquo )Pharmaceutically Active Compounds (PACrsquos)Pharmaceutically Active Compounds (PACrsquos)

bullbull EDCrsquosEDCrsquos andand PACrsquosPACrsquos areare NaturallyNaturally andand SyntheticSyntheticdd th tth t ff tff t thth b lb l llcompoundscompounds thatthat maymay affectaffect thethe balancebalance oror normalnormal

functionsfunctions inin animalsanimals andand humanshumans

What can EDCrsquos and PACrsquos doWhat can EDCrsquos and PACrsquos do

bullbull Even in very small concentrations these compounds Even in very small concentrations these compounds y py pcan can disruptdisrupt normal bodily functionsnormal bodily functions

bullbull ManMan--made chemicals can trick the bodies endocrine made chemicals can trick the bodies endocrine system system

Applications of Ozone

Examples of Endocrine Disruptors1000rsquos of compounds that may be Investigated as EDCs ndash Some examples are

bullbull Synthetic HormonesSynthetic Hormonesbullbull Naturally Occurring Estrogens Naturally Occurring Estrogens

Health and Beauty AidsHealth and Beauty Aidsbullbull Health and Beauty AidsHealth and Beauty Aidsbullbull SolventsSolventsbullbull PesticidesPesticidesbullbull SurfactantsSurfactantsbullbull PlasticsPlastics

F i idF i idbullbull FungicidesFungicides

Ozone Water TreatmentOzone Water Treatment

Ozone Ozone -- Industrial ApplicationsIndustrial Applications-- Ultrapure Water for Pharmaceutical ApplicationsUltrapure Water for Pharmaceutical Applications

-- Wastewater disinfection color removalWastewater disinfection color removal

-- Soil and Groundwater Remediation Soil and Groundwater Remediation

-- Cooling Tower Water TreatmentCooling Tower Water Treatment

-- Food ProcessingFood Processing

-- Aquaculture AquariumsAquaculture AquariumsAquaculture AquariumsAquaculture Aquariums

-- Beverage ApplicationsBeverage Applications

P l amp P Bl hiP l amp P Bl hi-- Pulp amp Paper BleachingPulp amp Paper Bleaching

High Purity OzonationHigh Purity Ozonation

Microchip manufacturingMicrochip manufacturing

What are the current issues in large-scale gozone generationg

Experimental Setup

Front view of the two units after the redesign and reworking ofthe gas water and instruments connectionsthe gas water and instruments connections

Experimental Setup

Top view of the twoexperimental unitsexperimental unitsSpectroscope (notshown) is to the left ofthe DBD The units weredifferent with respect todifferent with respect totheir electrodes onehad only the electrodecoated with thedielectric (ldquosingle-dielectric ( single-coatedrdquo) the other onehad the electrode andthe anode coated withthe dielectric (ldquodouble-the dielectric ( double-coatedrdquo)

Basics Generation of OzoneBasics Generation of Ozone

SpectroscopyPlasma

Plasma Absorption SpectroscopyPlasma Absorption Spectroscopy

Infrared Absorption SpectroscopyInfrared Absorption Spectroscopy

IR spectra in pure oxygen (black curve) and at approximately 10wt N2 admixture (red line) N2O5 peaks appear at124 1 d 1 2 11245 cm-1 and at 1725 cm-1

Infrared Absorption SpectroscopyInfrared Absorption Spectroscopy

IR spectra of several methane variations The green curve envelopes all of the methane peaks at 1325 cm-1recorded at smaller methane admixtures Simultaneously the N2O5 peaks disappear as the methane peaks appear

N2O5 FormationN2O5 Formation2 52 5p=2 bara cwt=20degC q=35kWm2 f=1450Hz

45N2O5 AT95

30

35

40

N

2 B

lend

ing

N2O AT95N2O5 IGSN2O IGSN2O5 LGN2O LG

1 5

20

25

nt [p

pmV]

3

wt

05

10

15

NO

x co

nten

005 7 9 11 13 15 17

ozone conc [wt]

Amount of formed N2O5 and N2O as a function of ozone concentration at 3 wt of nitrogen admixture and fori l dvarious electrode arrangements

Plasma Emission SpectroscopyPlasma Emission Spectroscopyp pyp py

Relative Emissions of the Ozonizer plasmaRelative Emissions of the Ozonizer plasma

Region 300- 850 nm from individual (calibrated) regions (smoothed by PeakFit) Single-coated ozone generator Inlet side

3 5E+06

30E+06

35E+06

7 9

20E+06

25E+06

nten

sity

au

2

311 12

10E+06

15E+06

In 4

5

6 8 10

14

15

16

17

00E+00

50E+05

280 300 320 340 360 380 400 420 440 460 480 500 520 540 560 580 600 620 640 660 680 700 720 740 760 780 800 820 840 860

Wavelength nm

1 13

Wavelength nm

Absolute Emission of the DBD PlasmaAbsolute Emission of the DBD Plasma

Intensities in (O2+3 wtN2) plasma

1 20E+04

100E+04

120E+04

600E+03

800E+03

nten

sity

(au

)

200E+03

400E+03

In

O(777)

000E+00200 250 300 350 400 450 500 550 600 650 700 750 800 850

Wavelength nm

Intensities in 3 wtN2+O2 plasmaIntensities in 3 wtN2+O2 plasma

Plasma Chemistry in OzonizersPlasma Chemistry in Ozonizers

Dry Air O2 N2

e - e -

O N2 N O2

O3 NO

O2 N O2

O3

N

3

NO2

O2 O3

NO

N

NO2 O3

N2O

NO3 N

N2O4

NO2

NO2

N2O5

NO3

Primary electron-driven chemical reactions leading to the formation of N2O5 and N2O in a dry air plasma

Plasma emission diagnostics role of N2Plasma emission diagnostics role of N2

Dry Air O2 N2

e - e -

O N2 N O2

O3 NO

O2 N O2

O3

O

N

ON

NO2

O2O3

N

NO N

NO2 O3

N2O

NO3 N

N2O4

NO2

NO2

N2O5

NO3

ONbullWith N2 present ndash less oxygen atoms are formed However the difference in intensity is

very small

Modeling of plasma chemistry incl the NxOy chemistry up to N2O5 for different Oxygen Nitrogen mixtures varying power deposition scenarios

and initial ozone background concentrations (up to 15) previously done

The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation

The role of N2 must be related to its by-products reacting on the surface of the electrodeThe role of N2 must be related to its by-products reacting on the surface of the electrode

The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established

Ab 8 t f O

The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established

Ab 8 t f OAbove 8 wt of O3

1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)

Above 8 wt of O3

1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)case without pampp)

2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of the

case without pampp)

2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of thethem A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface

them A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface

The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation

Three possibilities have to be considered for the oxygen-fedozone generator

Three possibilities have to be considered for the oxygen-fedozone generatorozone generator

bull Excited N2 molecules lead to an increased O2 dissociation in

ozone generator

bull Excited N2 molecules lead to an increased O2 dissociation in2 2such case an increased efficiency is correlated to the N2admixture

2 2such case an increased efficiency is correlated to the N2admixture

bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial

bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial

bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2

bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2g p g 3 pp y 2g p g 3 pp y 2

Effect of methane on ozone efficiency and specific powerEffect of methane on ozone efficiency and specific power

Effect of Methane on Ozone Content in Outlet Gas and on Specific Power Pure O2

13 12

10

11

12

t 8

10

8

9

10

ne c

onte

nt w

t

6

8

ecifi

c po

wer

kW

hlb

5

6

7

Ozo

n

2

4 Spe

400E+00 20E+03 40E+03 60E+03 80E+03 10E+04 12E+04

Methane in feedgas ppm

0

Ozone content in the outlet gas Specif ic pow er of the ozone generatorg p p g

Effects of N2 and CH4Effects of N2 and CH4

Pi t f h t lli N O t tPicture of an amorphous-crystalline N2O5 structurecaptured at the Orlando Skylake water plant in 2006

Plasma Chemistry with CH4 Impurities

OxygenO2 N2

e - e -

CHO N2

NO2

O NO

O2 N O2 O3

NOH

CH4e-

O3 NO

NO2

O2O3NO N

NO2 O

NO2

NO2

N2ONO3

N

O3

NO2

NO

HNO3

N2O4

N2O5

NO2

NO3

N2O5

Effect of methane on the electrode surfaces

a) b)

Inlet Outlet Outlet

) d)

I l t I l t

c) d)

Electrode of the ozone generator afterseveral hours in CH8O2 and up to 2 wt of methane (a b c)

Inlet Inlet

three hours in CH8O2+traces of N2 and up to 1 wt of methane (d) Visible change of discharge character at about 13 length of electrode (a d)

Kinetics of CHx Conversion without N2

conversion by collisions

O2 + CHx 12wt O3 + CO2 +H2O

deposition vaporizationby sputtering

ibl b l 1000 CHreversible process below 1000ppm CH4

Effect of water on electrode surface with N2

Inlet

OutletOutlet

Electrode of the ozone generator after several hours in H OO N

Inlet

Electrode of the ozone generator after several hours in H2OO2N2

Effect of water on electrode surface

Long term effect (800 hrs) of H2OO2N2

Kinetics of CHx Conversion with N2

conversion by collisionsHNO3 formation

O2 + N2 +CHx 12wtO2 + CO2 +H2O + HNO3

deposition vaporizationby sputtering

H2O + HNO3

by sputtering

irreversible process above a N2 threshold () ltlt 1000ppm N2

sticky deposit

p 2 ( ) pp 2 any CH4 concentration (60ppm)

Plasma Chemistry with CH4 ImpuritiesPlasma Chemistry with CH4 Impurities4

bull Formation of NO and NO2 depends on O3 N2 and gas temperature Conclusion N2 admixture is the key factor

SummarySummaryyyThe mechanisms of formed NOx by-products follows the sameThe mechanisms of formed NOx by-products follows the sameprinciples as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentration

principles as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentrationozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)

ozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)g p ( g p )

The conversion of methane to OH and H2O is found to depend on

g p ( g p )

The conversion of methane to OH and H2O is found to depend ondissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)

dissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)discharge gap)discharge gap)

How do you optimize an ozone generatorg

Scientific ApproachScientific ApproachTheoretical Experimental

pppp

c [wt]

f [Hz]

c [wt]

f [Hz]

[kW]UUUβ1

1Cf4αPn

1iiminpeakimin

iiD

q [kWm2]q [kWm2]

150

180

][V]voltagepeakUpeak

[]cylinder perslicesofamountnsliceii

whereth

09 00

30

60

90

120

effic

ienc

y [

][0tdj t bl[F]sliceisdielectricofecapacitancC

[Hz]frequencyf[V]sliceivoltageminimumiUmin

thiD

th

10

28

46

64

82

39

107

176

244 power density

[kWm2]

ozone conc [wt][]CCβ

][0parameteradjustableα

iDiGi

Impact of Power Inductionp

350

400

wer

200

250

300

App

lied

Pow

Arr C 2Arr D +0

Arr E +45Arr F +7

Arr G +3

5 0

100

150

Frac

tion

of

1 2 3 4

ReferenceArr B unstable

Arr C -2

00

50

4Position (1inlet 4outlet)

Experimental Test Rigp g

Experimental Test Rigp g

Outer grounded electrode (left picture) and the dielectric covered inner electrodes (right) d e ect c cove ed e e ect odes ( g t)

Reference (Traditional) Arrangement

Inlet OutletGas flow direction

Optimized Arrangement

Inlet OutletGas flow direction

Intelligent Gap System (IGS)g p y ( )

Molecular Oxygen (O2) Ozone (O3)

O2 O3

yg ( 2) ( 3)

Particle Size SynthesisParticle Size SynthesisByBy--Products Cluster FormationProducts Cluster Formationyy

high diffusion and deposition to surfaces

low diffusion rate good transport

high sedimentation on the structurehigh sedimentation on the structure

Degreacutemont Technologies ndash OzoniaIntelligent Gap SystemIntelligent Gap System

G Vezzuacute JL Lopez A Freilich and K Becker Optimizationof Large-Scale Ozone Generators IEEE Transactions onPlasma Science Vol 37 No 6 p 890-896 (2009)

ConclusionsConclusionsConclusionsConclusionsFundamentals of ozone synthesis in a DBD plasmay p

ndash Highly filamented DBD discharges are best-suitedfor the production of ozone concentrations in therange of 6 to 14 wtrange of 6 to 14 wt

ndash The preferred characteristic of the microdischargesare Townsend-like at reduced electric fields Enaround 190 Townsend

ndash Detrimental side-effects induced by by-productscan be avoided by a proper design of the electrodecan be avoided by a proper design of the electrodearrangement The phenomenon is related to thediffusion rates of formed by-product clusters

ConclusionsConclusionsConclusionsConclusionsBenefits from DBD microplasma tailoring

ndash Reduced power consumption of up to 10 improvement

ndash Increased ozone concentrations of up to 14 now achievable

ndash Improved neutralization and conditioning of detrimental by-products

ndash Reduced system capital and operational cost

New technologies to improve ozone p

generatorg

HV Pulsed Power SwitchingHV Pulsed Power Switching

Microchannel Generation of Ozone

Channel ArrayChannel Array

Microchannel

330 microm 230 microm

Some Cap-DBD Devices Operating in Air

Increase of 60 of

Spacing 225 μmof 60 of plasma

No space

Cap‐DBD ozone generation

bull Ozone concentration is evaluated via Eco S d l UV 100 O A l (0 01Sensors model UV-100 Ozone Analyzer (001 ndash 900 ppm wiht an accuracy of plusmn2)

bull Three reactors 6 tubings 6rdquo with spacings of 0 μm 225 μm and 500 μm running at 3 kV μ μ μ g

SpacingOzone Concentration

3 kV rms 4 kV rms3 kV rms 4 kV rms

0 μm 660 ppm

225 μm 550 ppm

For a device of such small scale these ozone levels are promising

500 μm 380 ppm

J Mahoney W Zhu VS Johnson KH Becker and JL Lopez Electrical and optical emissionmeasurements of a capillary dielectric barrier discharge European Physics Journal D Vol 60 441-447(2010)

QuestionsQuestions

Thank YouFor more informationProf Jose L Lopez PhD

Thank YouFor more informationDepartment of Physics

Telephone (973) 761-9057Email joselopez1shuedu

Website wwwshueduacademicsartsciphysicsWebsite wwwshueduacademicsartsciphysics

Page 59: Dielectric Barrier Discharge (DBD) & Progress in Large ...bonitz/si12/talks/august_8/lopez_si12.pdf · Dielectric Barrier Discharge (DBD) & Progress in Large-Scale Ozone Generation

Ozone Water TreatmentOzone Water TreatmentOzone Ozone ndashndash Municipal ApplicationsMunicipal Applications

bullbull Taste and OdorTaste and Odor

bullbull Color RemovalColor Removal

bullbull Disinfection Without Trihalomethanes (THMs)Disinfection Without Trihalomethanes (THMs)

bullbull Improved Filtration Efficiency and FlocculationImproved Filtration Efficiency and Flocculation

bullbull Cryptosporidium DeactivationCryptosporidium Deactivation

bullbull Giardia amp Virus InactivationGiardia amp Virus Inactivation

bullbull Oxidation Oxidation -- Organics Fe amp MnOrganics Fe amp Mn

bullbull Wastewater disinfectionWastewater disinfection

bullbull BOD COD and TOC reductionBOD COD and TOC reduction

Applications of Ozone

Wastewater Treatmentbull Disinfection of Secondary and Tertiary Effluentsbull Color Reductionbull Color Reductionbull TOC Oxidation (Industrial)bull Oxidation of Odor Causing Compoundsbull Oxidation of Endocrine Disruptors (EDCrsquos) and p ( )

Pharmaceutically Active Compounds (PACrsquos)

Applications of Ozone

What are Endocrine Disruptors (EDCrsquos) and What are Endocrine Disruptors (EDCrsquos) and Ph ti ll A ti C d (PACrsquo )Ph ti ll A ti C d (PACrsquo )Pharmaceutically Active Compounds (PACrsquos)Pharmaceutically Active Compounds (PACrsquos)

bullbull EDCrsquosEDCrsquos andand PACrsquosPACrsquos areare NaturallyNaturally andand SyntheticSyntheticdd th tth t ff tff t thth b lb l llcompoundscompounds thatthat maymay affectaffect thethe balancebalance oror normalnormal

functionsfunctions inin animalsanimals andand humanshumans

What can EDCrsquos and PACrsquos doWhat can EDCrsquos and PACrsquos do

bullbull Even in very small concentrations these compounds Even in very small concentrations these compounds y py pcan can disruptdisrupt normal bodily functionsnormal bodily functions

bullbull ManMan--made chemicals can trick the bodies endocrine made chemicals can trick the bodies endocrine system system

Applications of Ozone

Examples of Endocrine Disruptors1000rsquos of compounds that may be Investigated as EDCs ndash Some examples are

bullbull Synthetic HormonesSynthetic Hormonesbullbull Naturally Occurring Estrogens Naturally Occurring Estrogens

Health and Beauty AidsHealth and Beauty Aidsbullbull Health and Beauty AidsHealth and Beauty Aidsbullbull SolventsSolventsbullbull PesticidesPesticidesbullbull SurfactantsSurfactantsbullbull PlasticsPlastics

F i idF i idbullbull FungicidesFungicides

Ozone Water TreatmentOzone Water Treatment

Ozone Ozone -- Industrial ApplicationsIndustrial Applications-- Ultrapure Water for Pharmaceutical ApplicationsUltrapure Water for Pharmaceutical Applications

-- Wastewater disinfection color removalWastewater disinfection color removal

-- Soil and Groundwater Remediation Soil and Groundwater Remediation

-- Cooling Tower Water TreatmentCooling Tower Water Treatment

-- Food ProcessingFood Processing

-- Aquaculture AquariumsAquaculture AquariumsAquaculture AquariumsAquaculture Aquariums

-- Beverage ApplicationsBeverage Applications

P l amp P Bl hiP l amp P Bl hi-- Pulp amp Paper BleachingPulp amp Paper Bleaching

High Purity OzonationHigh Purity Ozonation

Microchip manufacturingMicrochip manufacturing

What are the current issues in large-scale gozone generationg

Experimental Setup

Front view of the two units after the redesign and reworking ofthe gas water and instruments connectionsthe gas water and instruments connections

Experimental Setup

Top view of the twoexperimental unitsexperimental unitsSpectroscope (notshown) is to the left ofthe DBD The units weredifferent with respect todifferent with respect totheir electrodes onehad only the electrodecoated with thedielectric (ldquosingle-dielectric ( single-coatedrdquo) the other onehad the electrode andthe anode coated withthe dielectric (ldquodouble-the dielectric ( double-coatedrdquo)

Basics Generation of OzoneBasics Generation of Ozone

SpectroscopyPlasma

Plasma Absorption SpectroscopyPlasma Absorption Spectroscopy

Infrared Absorption SpectroscopyInfrared Absorption Spectroscopy

IR spectra in pure oxygen (black curve) and at approximately 10wt N2 admixture (red line) N2O5 peaks appear at124 1 d 1 2 11245 cm-1 and at 1725 cm-1

Infrared Absorption SpectroscopyInfrared Absorption Spectroscopy

IR spectra of several methane variations The green curve envelopes all of the methane peaks at 1325 cm-1recorded at smaller methane admixtures Simultaneously the N2O5 peaks disappear as the methane peaks appear

N2O5 FormationN2O5 Formation2 52 5p=2 bara cwt=20degC q=35kWm2 f=1450Hz

45N2O5 AT95

30

35

40

N

2 B

lend

ing

N2O AT95N2O5 IGSN2O IGSN2O5 LGN2O LG

1 5

20

25

nt [p

pmV]

3

wt

05

10

15

NO

x co

nten

005 7 9 11 13 15 17

ozone conc [wt]

Amount of formed N2O5 and N2O as a function of ozone concentration at 3 wt of nitrogen admixture and fori l dvarious electrode arrangements

Plasma Emission SpectroscopyPlasma Emission Spectroscopyp pyp py

Relative Emissions of the Ozonizer plasmaRelative Emissions of the Ozonizer plasma

Region 300- 850 nm from individual (calibrated) regions (smoothed by PeakFit) Single-coated ozone generator Inlet side

3 5E+06

30E+06

35E+06

7 9

20E+06

25E+06

nten

sity

au

2

311 12

10E+06

15E+06

In 4

5

6 8 10

14

15

16

17

00E+00

50E+05

280 300 320 340 360 380 400 420 440 460 480 500 520 540 560 580 600 620 640 660 680 700 720 740 760 780 800 820 840 860

Wavelength nm

1 13

Wavelength nm

Absolute Emission of the DBD PlasmaAbsolute Emission of the DBD Plasma

Intensities in (O2+3 wtN2) plasma

1 20E+04

100E+04

120E+04

600E+03

800E+03

nten

sity

(au

)

200E+03

400E+03

In

O(777)

000E+00200 250 300 350 400 450 500 550 600 650 700 750 800 850

Wavelength nm

Intensities in 3 wtN2+O2 plasmaIntensities in 3 wtN2+O2 plasma

Plasma Chemistry in OzonizersPlasma Chemistry in Ozonizers

Dry Air O2 N2

e - e -

O N2 N O2

O3 NO

O2 N O2

O3

N

3

NO2

O2 O3

NO

N

NO2 O3

N2O

NO3 N

N2O4

NO2

NO2

N2O5

NO3

Primary electron-driven chemical reactions leading to the formation of N2O5 and N2O in a dry air plasma

Plasma emission diagnostics role of N2Plasma emission diagnostics role of N2

Dry Air O2 N2

e - e -

O N2 N O2

O3 NO

O2 N O2

O3

O

N

ON

NO2

O2O3

N

NO N

NO2 O3

N2O

NO3 N

N2O4

NO2

NO2

N2O5

NO3

ONbullWith N2 present ndash less oxygen atoms are formed However the difference in intensity is

very small

Modeling of plasma chemistry incl the NxOy chemistry up to N2O5 for different Oxygen Nitrogen mixtures varying power deposition scenarios

and initial ozone background concentrations (up to 15) previously done

The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation

The role of N2 must be related to its by-products reacting on the surface of the electrodeThe role of N2 must be related to its by-products reacting on the surface of the electrode

The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established

Ab 8 t f O

The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established

Ab 8 t f OAbove 8 wt of O3

1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)

Above 8 wt of O3

1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)case without pampp)

2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of the

case without pampp)

2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of thethem A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface

them A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface

The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation

Three possibilities have to be considered for the oxygen-fedozone generator

Three possibilities have to be considered for the oxygen-fedozone generatorozone generator

bull Excited N2 molecules lead to an increased O2 dissociation in

ozone generator

bull Excited N2 molecules lead to an increased O2 dissociation in2 2such case an increased efficiency is correlated to the N2admixture

2 2such case an increased efficiency is correlated to the N2admixture

bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial

bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial

bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2

bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2g p g 3 pp y 2g p g 3 pp y 2

Effect of methane on ozone efficiency and specific powerEffect of methane on ozone efficiency and specific power

Effect of Methane on Ozone Content in Outlet Gas and on Specific Power Pure O2

13 12

10

11

12

t 8

10

8

9

10

ne c

onte

nt w

t

6

8

ecifi

c po

wer

kW

hlb

5

6

7

Ozo

n

2

4 Spe

400E+00 20E+03 40E+03 60E+03 80E+03 10E+04 12E+04

Methane in feedgas ppm

0

Ozone content in the outlet gas Specif ic pow er of the ozone generatorg p p g

Effects of N2 and CH4Effects of N2 and CH4

Pi t f h t lli N O t tPicture of an amorphous-crystalline N2O5 structurecaptured at the Orlando Skylake water plant in 2006

Plasma Chemistry with CH4 Impurities

OxygenO2 N2

e - e -

CHO N2

NO2

O NO

O2 N O2 O3

NOH

CH4e-

O3 NO

NO2

O2O3NO N

NO2 O

NO2

NO2

N2ONO3

N

O3

NO2

NO

HNO3

N2O4

N2O5

NO2

NO3

N2O5

Effect of methane on the electrode surfaces

a) b)

Inlet Outlet Outlet

) d)

I l t I l t

c) d)

Electrode of the ozone generator afterseveral hours in CH8O2 and up to 2 wt of methane (a b c)

Inlet Inlet

three hours in CH8O2+traces of N2 and up to 1 wt of methane (d) Visible change of discharge character at about 13 length of electrode (a d)

Kinetics of CHx Conversion without N2

conversion by collisions

O2 + CHx 12wt O3 + CO2 +H2O

deposition vaporizationby sputtering

ibl b l 1000 CHreversible process below 1000ppm CH4

Effect of water on electrode surface with N2

Inlet

OutletOutlet

Electrode of the ozone generator after several hours in H OO N

Inlet

Electrode of the ozone generator after several hours in H2OO2N2

Effect of water on electrode surface

Long term effect (800 hrs) of H2OO2N2

Kinetics of CHx Conversion with N2

conversion by collisionsHNO3 formation

O2 + N2 +CHx 12wtO2 + CO2 +H2O + HNO3

deposition vaporizationby sputtering

H2O + HNO3

by sputtering

irreversible process above a N2 threshold () ltlt 1000ppm N2

sticky deposit

p 2 ( ) pp 2 any CH4 concentration (60ppm)

Plasma Chemistry with CH4 ImpuritiesPlasma Chemistry with CH4 Impurities4

bull Formation of NO and NO2 depends on O3 N2 and gas temperature Conclusion N2 admixture is the key factor

SummarySummaryyyThe mechanisms of formed NOx by-products follows the sameThe mechanisms of formed NOx by-products follows the sameprinciples as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentration

principles as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentrationozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)

ozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)g p ( g p )

The conversion of methane to OH and H2O is found to depend on

g p ( g p )

The conversion of methane to OH and H2O is found to depend ondissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)

dissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)discharge gap)discharge gap)

How do you optimize an ozone generatorg

Scientific ApproachScientific ApproachTheoretical Experimental

pppp

c [wt]

f [Hz]

c [wt]

f [Hz]

[kW]UUUβ1

1Cf4αPn

1iiminpeakimin

iiD

q [kWm2]q [kWm2]

150

180

][V]voltagepeakUpeak

[]cylinder perslicesofamountnsliceii

whereth

09 00

30

60

90

120

effic

ienc

y [

][0tdj t bl[F]sliceisdielectricofecapacitancC

[Hz]frequencyf[V]sliceivoltageminimumiUmin

thiD

th

10

28

46

64

82

39

107

176

244 power density

[kWm2]

ozone conc [wt][]CCβ

][0parameteradjustableα

iDiGi

Impact of Power Inductionp

350

400

wer

200

250

300

App

lied

Pow

Arr C 2Arr D +0

Arr E +45Arr F +7

Arr G +3

5 0

100

150

Frac

tion

of

1 2 3 4

ReferenceArr B unstable

Arr C -2

00

50

4Position (1inlet 4outlet)

Experimental Test Rigp g

Experimental Test Rigp g

Outer grounded electrode (left picture) and the dielectric covered inner electrodes (right) d e ect c cove ed e e ect odes ( g t)

Reference (Traditional) Arrangement

Inlet OutletGas flow direction

Optimized Arrangement

Inlet OutletGas flow direction

Intelligent Gap System (IGS)g p y ( )

Molecular Oxygen (O2) Ozone (O3)

O2 O3

yg ( 2) ( 3)

Particle Size SynthesisParticle Size SynthesisByBy--Products Cluster FormationProducts Cluster Formationyy

high diffusion and deposition to surfaces

low diffusion rate good transport

high sedimentation on the structurehigh sedimentation on the structure

Degreacutemont Technologies ndash OzoniaIntelligent Gap SystemIntelligent Gap System

G Vezzuacute JL Lopez A Freilich and K Becker Optimizationof Large-Scale Ozone Generators IEEE Transactions onPlasma Science Vol 37 No 6 p 890-896 (2009)

ConclusionsConclusionsConclusionsConclusionsFundamentals of ozone synthesis in a DBD plasmay p

ndash Highly filamented DBD discharges are best-suitedfor the production of ozone concentrations in therange of 6 to 14 wtrange of 6 to 14 wt

ndash The preferred characteristic of the microdischargesare Townsend-like at reduced electric fields Enaround 190 Townsend

ndash Detrimental side-effects induced by by-productscan be avoided by a proper design of the electrodecan be avoided by a proper design of the electrodearrangement The phenomenon is related to thediffusion rates of formed by-product clusters

ConclusionsConclusionsConclusionsConclusionsBenefits from DBD microplasma tailoring

ndash Reduced power consumption of up to 10 improvement

ndash Increased ozone concentrations of up to 14 now achievable

ndash Improved neutralization and conditioning of detrimental by-products

ndash Reduced system capital and operational cost

New technologies to improve ozone p

generatorg

HV Pulsed Power SwitchingHV Pulsed Power Switching

Microchannel Generation of Ozone

Channel ArrayChannel Array

Microchannel

330 microm 230 microm

Some Cap-DBD Devices Operating in Air

Increase of 60 of

Spacing 225 μmof 60 of plasma

No space

Cap‐DBD ozone generation

bull Ozone concentration is evaluated via Eco S d l UV 100 O A l (0 01Sensors model UV-100 Ozone Analyzer (001 ndash 900 ppm wiht an accuracy of plusmn2)

bull Three reactors 6 tubings 6rdquo with spacings of 0 μm 225 μm and 500 μm running at 3 kV μ μ μ g

SpacingOzone Concentration

3 kV rms 4 kV rms3 kV rms 4 kV rms

0 μm 660 ppm

225 μm 550 ppm

For a device of such small scale these ozone levels are promising

500 μm 380 ppm

J Mahoney W Zhu VS Johnson KH Becker and JL Lopez Electrical and optical emissionmeasurements of a capillary dielectric barrier discharge European Physics Journal D Vol 60 441-447(2010)

QuestionsQuestions

Thank YouFor more informationProf Jose L Lopez PhD

Thank YouFor more informationDepartment of Physics

Telephone (973) 761-9057Email joselopez1shuedu

Website wwwshueduacademicsartsciphysicsWebsite wwwshueduacademicsartsciphysics

Page 60: Dielectric Barrier Discharge (DBD) & Progress in Large ...bonitz/si12/talks/august_8/lopez_si12.pdf · Dielectric Barrier Discharge (DBD) & Progress in Large-Scale Ozone Generation

Applications of Ozone

Wastewater Treatmentbull Disinfection of Secondary and Tertiary Effluentsbull Color Reductionbull Color Reductionbull TOC Oxidation (Industrial)bull Oxidation of Odor Causing Compoundsbull Oxidation of Endocrine Disruptors (EDCrsquos) and p ( )

Pharmaceutically Active Compounds (PACrsquos)

Applications of Ozone

What are Endocrine Disruptors (EDCrsquos) and What are Endocrine Disruptors (EDCrsquos) and Ph ti ll A ti C d (PACrsquo )Ph ti ll A ti C d (PACrsquo )Pharmaceutically Active Compounds (PACrsquos)Pharmaceutically Active Compounds (PACrsquos)

bullbull EDCrsquosEDCrsquos andand PACrsquosPACrsquos areare NaturallyNaturally andand SyntheticSyntheticdd th tth t ff tff t thth b lb l llcompoundscompounds thatthat maymay affectaffect thethe balancebalance oror normalnormal

functionsfunctions inin animalsanimals andand humanshumans

What can EDCrsquos and PACrsquos doWhat can EDCrsquos and PACrsquos do

bullbull Even in very small concentrations these compounds Even in very small concentrations these compounds y py pcan can disruptdisrupt normal bodily functionsnormal bodily functions

bullbull ManMan--made chemicals can trick the bodies endocrine made chemicals can trick the bodies endocrine system system

Applications of Ozone

Examples of Endocrine Disruptors1000rsquos of compounds that may be Investigated as EDCs ndash Some examples are

bullbull Synthetic HormonesSynthetic Hormonesbullbull Naturally Occurring Estrogens Naturally Occurring Estrogens

Health and Beauty AidsHealth and Beauty Aidsbullbull Health and Beauty AidsHealth and Beauty Aidsbullbull SolventsSolventsbullbull PesticidesPesticidesbullbull SurfactantsSurfactantsbullbull PlasticsPlastics

F i idF i idbullbull FungicidesFungicides

Ozone Water TreatmentOzone Water Treatment

Ozone Ozone -- Industrial ApplicationsIndustrial Applications-- Ultrapure Water for Pharmaceutical ApplicationsUltrapure Water for Pharmaceutical Applications

-- Wastewater disinfection color removalWastewater disinfection color removal

-- Soil and Groundwater Remediation Soil and Groundwater Remediation

-- Cooling Tower Water TreatmentCooling Tower Water Treatment

-- Food ProcessingFood Processing

-- Aquaculture AquariumsAquaculture AquariumsAquaculture AquariumsAquaculture Aquariums

-- Beverage ApplicationsBeverage Applications

P l amp P Bl hiP l amp P Bl hi-- Pulp amp Paper BleachingPulp amp Paper Bleaching

High Purity OzonationHigh Purity Ozonation

Microchip manufacturingMicrochip manufacturing

What are the current issues in large-scale gozone generationg

Experimental Setup

Front view of the two units after the redesign and reworking ofthe gas water and instruments connectionsthe gas water and instruments connections

Experimental Setup

Top view of the twoexperimental unitsexperimental unitsSpectroscope (notshown) is to the left ofthe DBD The units weredifferent with respect todifferent with respect totheir electrodes onehad only the electrodecoated with thedielectric (ldquosingle-dielectric ( single-coatedrdquo) the other onehad the electrode andthe anode coated withthe dielectric (ldquodouble-the dielectric ( double-coatedrdquo)

Basics Generation of OzoneBasics Generation of Ozone

SpectroscopyPlasma

Plasma Absorption SpectroscopyPlasma Absorption Spectroscopy

Infrared Absorption SpectroscopyInfrared Absorption Spectroscopy

IR spectra in pure oxygen (black curve) and at approximately 10wt N2 admixture (red line) N2O5 peaks appear at124 1 d 1 2 11245 cm-1 and at 1725 cm-1

Infrared Absorption SpectroscopyInfrared Absorption Spectroscopy

IR spectra of several methane variations The green curve envelopes all of the methane peaks at 1325 cm-1recorded at smaller methane admixtures Simultaneously the N2O5 peaks disappear as the methane peaks appear

N2O5 FormationN2O5 Formation2 52 5p=2 bara cwt=20degC q=35kWm2 f=1450Hz

45N2O5 AT95

30

35

40

N

2 B

lend

ing

N2O AT95N2O5 IGSN2O IGSN2O5 LGN2O LG

1 5

20

25

nt [p

pmV]

3

wt

05

10

15

NO

x co

nten

005 7 9 11 13 15 17

ozone conc [wt]

Amount of formed N2O5 and N2O as a function of ozone concentration at 3 wt of nitrogen admixture and fori l dvarious electrode arrangements

Plasma Emission SpectroscopyPlasma Emission Spectroscopyp pyp py

Relative Emissions of the Ozonizer plasmaRelative Emissions of the Ozonizer plasma

Region 300- 850 nm from individual (calibrated) regions (smoothed by PeakFit) Single-coated ozone generator Inlet side

3 5E+06

30E+06

35E+06

7 9

20E+06

25E+06

nten

sity

au

2

311 12

10E+06

15E+06

In 4

5

6 8 10

14

15

16

17

00E+00

50E+05

280 300 320 340 360 380 400 420 440 460 480 500 520 540 560 580 600 620 640 660 680 700 720 740 760 780 800 820 840 860

Wavelength nm

1 13

Wavelength nm

Absolute Emission of the DBD PlasmaAbsolute Emission of the DBD Plasma

Intensities in (O2+3 wtN2) plasma

1 20E+04

100E+04

120E+04

600E+03

800E+03

nten

sity

(au

)

200E+03

400E+03

In

O(777)

000E+00200 250 300 350 400 450 500 550 600 650 700 750 800 850

Wavelength nm

Intensities in 3 wtN2+O2 plasmaIntensities in 3 wtN2+O2 plasma

Plasma Chemistry in OzonizersPlasma Chemistry in Ozonizers

Dry Air O2 N2

e - e -

O N2 N O2

O3 NO

O2 N O2

O3

N

3

NO2

O2 O3

NO

N

NO2 O3

N2O

NO3 N

N2O4

NO2

NO2

N2O5

NO3

Primary electron-driven chemical reactions leading to the formation of N2O5 and N2O in a dry air plasma

Plasma emission diagnostics role of N2Plasma emission diagnostics role of N2

Dry Air O2 N2

e - e -

O N2 N O2

O3 NO

O2 N O2

O3

O

N

ON

NO2

O2O3

N

NO N

NO2 O3

N2O

NO3 N

N2O4

NO2

NO2

N2O5

NO3

ONbullWith N2 present ndash less oxygen atoms are formed However the difference in intensity is

very small

Modeling of plasma chemistry incl the NxOy chemistry up to N2O5 for different Oxygen Nitrogen mixtures varying power deposition scenarios

and initial ozone background concentrations (up to 15) previously done

The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation

The role of N2 must be related to its by-products reacting on the surface of the electrodeThe role of N2 must be related to its by-products reacting on the surface of the electrode

The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established

Ab 8 t f O

The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established

Ab 8 t f OAbove 8 wt of O3

1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)

Above 8 wt of O3

1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)case without pampp)

2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of the

case without pampp)

2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of thethem A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface

them A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface

The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation

Three possibilities have to be considered for the oxygen-fedozone generator

Three possibilities have to be considered for the oxygen-fedozone generatorozone generator

bull Excited N2 molecules lead to an increased O2 dissociation in

ozone generator

bull Excited N2 molecules lead to an increased O2 dissociation in2 2such case an increased efficiency is correlated to the N2admixture

2 2such case an increased efficiency is correlated to the N2admixture

bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial

bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial

bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2

bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2g p g 3 pp y 2g p g 3 pp y 2

Effect of methane on ozone efficiency and specific powerEffect of methane on ozone efficiency and specific power

Effect of Methane on Ozone Content in Outlet Gas and on Specific Power Pure O2

13 12

10

11

12

t 8

10

8

9

10

ne c

onte

nt w

t

6

8

ecifi

c po

wer

kW

hlb

5

6

7

Ozo

n

2

4 Spe

400E+00 20E+03 40E+03 60E+03 80E+03 10E+04 12E+04

Methane in feedgas ppm

0

Ozone content in the outlet gas Specif ic pow er of the ozone generatorg p p g

Effects of N2 and CH4Effects of N2 and CH4

Pi t f h t lli N O t tPicture of an amorphous-crystalline N2O5 structurecaptured at the Orlando Skylake water plant in 2006

Plasma Chemistry with CH4 Impurities

OxygenO2 N2

e - e -

CHO N2

NO2

O NO

O2 N O2 O3

NOH

CH4e-

O3 NO

NO2

O2O3NO N

NO2 O

NO2

NO2

N2ONO3

N

O3

NO2

NO

HNO3

N2O4

N2O5

NO2

NO3

N2O5

Effect of methane on the electrode surfaces

a) b)

Inlet Outlet Outlet

) d)

I l t I l t

c) d)

Electrode of the ozone generator afterseveral hours in CH8O2 and up to 2 wt of methane (a b c)

Inlet Inlet

three hours in CH8O2+traces of N2 and up to 1 wt of methane (d) Visible change of discharge character at about 13 length of electrode (a d)

Kinetics of CHx Conversion without N2

conversion by collisions

O2 + CHx 12wt O3 + CO2 +H2O

deposition vaporizationby sputtering

ibl b l 1000 CHreversible process below 1000ppm CH4

Effect of water on electrode surface with N2

Inlet

OutletOutlet

Electrode of the ozone generator after several hours in H OO N

Inlet

Electrode of the ozone generator after several hours in H2OO2N2

Effect of water on electrode surface

Long term effect (800 hrs) of H2OO2N2

Kinetics of CHx Conversion with N2

conversion by collisionsHNO3 formation

O2 + N2 +CHx 12wtO2 + CO2 +H2O + HNO3

deposition vaporizationby sputtering

H2O + HNO3

by sputtering

irreversible process above a N2 threshold () ltlt 1000ppm N2

sticky deposit

p 2 ( ) pp 2 any CH4 concentration (60ppm)

Plasma Chemistry with CH4 ImpuritiesPlasma Chemistry with CH4 Impurities4

bull Formation of NO and NO2 depends on O3 N2 and gas temperature Conclusion N2 admixture is the key factor

SummarySummaryyyThe mechanisms of formed NOx by-products follows the sameThe mechanisms of formed NOx by-products follows the sameprinciples as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentration

principles as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentrationozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)

ozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)g p ( g p )

The conversion of methane to OH and H2O is found to depend on

g p ( g p )

The conversion of methane to OH and H2O is found to depend ondissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)

dissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)discharge gap)discharge gap)

How do you optimize an ozone generatorg

Scientific ApproachScientific ApproachTheoretical Experimental

pppp

c [wt]

f [Hz]

c [wt]

f [Hz]

[kW]UUUβ1

1Cf4αPn

1iiminpeakimin

iiD

q [kWm2]q [kWm2]

150

180

][V]voltagepeakUpeak

[]cylinder perslicesofamountnsliceii

whereth

09 00

30

60

90

120

effic

ienc

y [

][0tdj t bl[F]sliceisdielectricofecapacitancC

[Hz]frequencyf[V]sliceivoltageminimumiUmin

thiD

th

10

28

46

64

82

39

107

176

244 power density

[kWm2]

ozone conc [wt][]CCβ

][0parameteradjustableα

iDiGi

Impact of Power Inductionp

350

400

wer

200

250

300

App

lied

Pow

Arr C 2Arr D +0

Arr E +45Arr F +7

Arr G +3

5 0

100

150

Frac

tion

of

1 2 3 4

ReferenceArr B unstable

Arr C -2

00

50

4Position (1inlet 4outlet)

Experimental Test Rigp g

Experimental Test Rigp g

Outer grounded electrode (left picture) and the dielectric covered inner electrodes (right) d e ect c cove ed e e ect odes ( g t)

Reference (Traditional) Arrangement

Inlet OutletGas flow direction

Optimized Arrangement

Inlet OutletGas flow direction

Intelligent Gap System (IGS)g p y ( )

Molecular Oxygen (O2) Ozone (O3)

O2 O3

yg ( 2) ( 3)

Particle Size SynthesisParticle Size SynthesisByBy--Products Cluster FormationProducts Cluster Formationyy

high diffusion and deposition to surfaces

low diffusion rate good transport

high sedimentation on the structurehigh sedimentation on the structure

Degreacutemont Technologies ndash OzoniaIntelligent Gap SystemIntelligent Gap System

G Vezzuacute JL Lopez A Freilich and K Becker Optimizationof Large-Scale Ozone Generators IEEE Transactions onPlasma Science Vol 37 No 6 p 890-896 (2009)

ConclusionsConclusionsConclusionsConclusionsFundamentals of ozone synthesis in a DBD plasmay p

ndash Highly filamented DBD discharges are best-suitedfor the production of ozone concentrations in therange of 6 to 14 wtrange of 6 to 14 wt

ndash The preferred characteristic of the microdischargesare Townsend-like at reduced electric fields Enaround 190 Townsend

ndash Detrimental side-effects induced by by-productscan be avoided by a proper design of the electrodecan be avoided by a proper design of the electrodearrangement The phenomenon is related to thediffusion rates of formed by-product clusters

ConclusionsConclusionsConclusionsConclusionsBenefits from DBD microplasma tailoring

ndash Reduced power consumption of up to 10 improvement

ndash Increased ozone concentrations of up to 14 now achievable

ndash Improved neutralization and conditioning of detrimental by-products

ndash Reduced system capital and operational cost

New technologies to improve ozone p

generatorg

HV Pulsed Power SwitchingHV Pulsed Power Switching

Microchannel Generation of Ozone

Channel ArrayChannel Array

Microchannel

330 microm 230 microm

Some Cap-DBD Devices Operating in Air

Increase of 60 of

Spacing 225 μmof 60 of plasma

No space

Cap‐DBD ozone generation

bull Ozone concentration is evaluated via Eco S d l UV 100 O A l (0 01Sensors model UV-100 Ozone Analyzer (001 ndash 900 ppm wiht an accuracy of plusmn2)

bull Three reactors 6 tubings 6rdquo with spacings of 0 μm 225 μm and 500 μm running at 3 kV μ μ μ g

SpacingOzone Concentration

3 kV rms 4 kV rms3 kV rms 4 kV rms

0 μm 660 ppm

225 μm 550 ppm

For a device of such small scale these ozone levels are promising

500 μm 380 ppm

J Mahoney W Zhu VS Johnson KH Becker and JL Lopez Electrical and optical emissionmeasurements of a capillary dielectric barrier discharge European Physics Journal D Vol 60 441-447(2010)

QuestionsQuestions

Thank YouFor more informationProf Jose L Lopez PhD

Thank YouFor more informationDepartment of Physics

Telephone (973) 761-9057Email joselopez1shuedu

Website wwwshueduacademicsartsciphysicsWebsite wwwshueduacademicsartsciphysics

Page 61: Dielectric Barrier Discharge (DBD) & Progress in Large ...bonitz/si12/talks/august_8/lopez_si12.pdf · Dielectric Barrier Discharge (DBD) & Progress in Large-Scale Ozone Generation

Applications of Ozone

What are Endocrine Disruptors (EDCrsquos) and What are Endocrine Disruptors (EDCrsquos) and Ph ti ll A ti C d (PACrsquo )Ph ti ll A ti C d (PACrsquo )Pharmaceutically Active Compounds (PACrsquos)Pharmaceutically Active Compounds (PACrsquos)

bullbull EDCrsquosEDCrsquos andand PACrsquosPACrsquos areare NaturallyNaturally andand SyntheticSyntheticdd th tth t ff tff t thth b lb l llcompoundscompounds thatthat maymay affectaffect thethe balancebalance oror normalnormal

functionsfunctions inin animalsanimals andand humanshumans

What can EDCrsquos and PACrsquos doWhat can EDCrsquos and PACrsquos do

bullbull Even in very small concentrations these compounds Even in very small concentrations these compounds y py pcan can disruptdisrupt normal bodily functionsnormal bodily functions

bullbull ManMan--made chemicals can trick the bodies endocrine made chemicals can trick the bodies endocrine system system

Applications of Ozone

Examples of Endocrine Disruptors1000rsquos of compounds that may be Investigated as EDCs ndash Some examples are

bullbull Synthetic HormonesSynthetic Hormonesbullbull Naturally Occurring Estrogens Naturally Occurring Estrogens

Health and Beauty AidsHealth and Beauty Aidsbullbull Health and Beauty AidsHealth and Beauty Aidsbullbull SolventsSolventsbullbull PesticidesPesticidesbullbull SurfactantsSurfactantsbullbull PlasticsPlastics

F i idF i idbullbull FungicidesFungicides

Ozone Water TreatmentOzone Water Treatment

Ozone Ozone -- Industrial ApplicationsIndustrial Applications-- Ultrapure Water for Pharmaceutical ApplicationsUltrapure Water for Pharmaceutical Applications

-- Wastewater disinfection color removalWastewater disinfection color removal

-- Soil and Groundwater Remediation Soil and Groundwater Remediation

-- Cooling Tower Water TreatmentCooling Tower Water Treatment

-- Food ProcessingFood Processing

-- Aquaculture AquariumsAquaculture AquariumsAquaculture AquariumsAquaculture Aquariums

-- Beverage ApplicationsBeverage Applications

P l amp P Bl hiP l amp P Bl hi-- Pulp amp Paper BleachingPulp amp Paper Bleaching

High Purity OzonationHigh Purity Ozonation

Microchip manufacturingMicrochip manufacturing

What are the current issues in large-scale gozone generationg

Experimental Setup

Front view of the two units after the redesign and reworking ofthe gas water and instruments connectionsthe gas water and instruments connections

Experimental Setup

Top view of the twoexperimental unitsexperimental unitsSpectroscope (notshown) is to the left ofthe DBD The units weredifferent with respect todifferent with respect totheir electrodes onehad only the electrodecoated with thedielectric (ldquosingle-dielectric ( single-coatedrdquo) the other onehad the electrode andthe anode coated withthe dielectric (ldquodouble-the dielectric ( double-coatedrdquo)

Basics Generation of OzoneBasics Generation of Ozone

SpectroscopyPlasma

Plasma Absorption SpectroscopyPlasma Absorption Spectroscopy

Infrared Absorption SpectroscopyInfrared Absorption Spectroscopy

IR spectra in pure oxygen (black curve) and at approximately 10wt N2 admixture (red line) N2O5 peaks appear at124 1 d 1 2 11245 cm-1 and at 1725 cm-1

Infrared Absorption SpectroscopyInfrared Absorption Spectroscopy

IR spectra of several methane variations The green curve envelopes all of the methane peaks at 1325 cm-1recorded at smaller methane admixtures Simultaneously the N2O5 peaks disappear as the methane peaks appear

N2O5 FormationN2O5 Formation2 52 5p=2 bara cwt=20degC q=35kWm2 f=1450Hz

45N2O5 AT95

30

35

40

N

2 B

lend

ing

N2O AT95N2O5 IGSN2O IGSN2O5 LGN2O LG

1 5

20

25

nt [p

pmV]

3

wt

05

10

15

NO

x co

nten

005 7 9 11 13 15 17

ozone conc [wt]

Amount of formed N2O5 and N2O as a function of ozone concentration at 3 wt of nitrogen admixture and fori l dvarious electrode arrangements

Plasma Emission SpectroscopyPlasma Emission Spectroscopyp pyp py

Relative Emissions of the Ozonizer plasmaRelative Emissions of the Ozonizer plasma

Region 300- 850 nm from individual (calibrated) regions (smoothed by PeakFit) Single-coated ozone generator Inlet side

3 5E+06

30E+06

35E+06

7 9

20E+06

25E+06

nten

sity

au

2

311 12

10E+06

15E+06

In 4

5

6 8 10

14

15

16

17

00E+00

50E+05

280 300 320 340 360 380 400 420 440 460 480 500 520 540 560 580 600 620 640 660 680 700 720 740 760 780 800 820 840 860

Wavelength nm

1 13

Wavelength nm

Absolute Emission of the DBD PlasmaAbsolute Emission of the DBD Plasma

Intensities in (O2+3 wtN2) plasma

1 20E+04

100E+04

120E+04

600E+03

800E+03

nten

sity

(au

)

200E+03

400E+03

In

O(777)

000E+00200 250 300 350 400 450 500 550 600 650 700 750 800 850

Wavelength nm

Intensities in 3 wtN2+O2 plasmaIntensities in 3 wtN2+O2 plasma

Plasma Chemistry in OzonizersPlasma Chemistry in Ozonizers

Dry Air O2 N2

e - e -

O N2 N O2

O3 NO

O2 N O2

O3

N

3

NO2

O2 O3

NO

N

NO2 O3

N2O

NO3 N

N2O4

NO2

NO2

N2O5

NO3

Primary electron-driven chemical reactions leading to the formation of N2O5 and N2O in a dry air plasma

Plasma emission diagnostics role of N2Plasma emission diagnostics role of N2

Dry Air O2 N2

e - e -

O N2 N O2

O3 NO

O2 N O2

O3

O

N

ON

NO2

O2O3

N

NO N

NO2 O3

N2O

NO3 N

N2O4

NO2

NO2

N2O5

NO3

ONbullWith N2 present ndash less oxygen atoms are formed However the difference in intensity is

very small

Modeling of plasma chemistry incl the NxOy chemistry up to N2O5 for different Oxygen Nitrogen mixtures varying power deposition scenarios

and initial ozone background concentrations (up to 15) previously done

The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation

The role of N2 must be related to its by-products reacting on the surface of the electrodeThe role of N2 must be related to its by-products reacting on the surface of the electrode

The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established

Ab 8 t f O

The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established

Ab 8 t f OAbove 8 wt of O3

1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)

Above 8 wt of O3

1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)case without pampp)

2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of the

case without pampp)

2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of thethem A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface

them A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface

The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation

Three possibilities have to be considered for the oxygen-fedozone generator

Three possibilities have to be considered for the oxygen-fedozone generatorozone generator

bull Excited N2 molecules lead to an increased O2 dissociation in

ozone generator

bull Excited N2 molecules lead to an increased O2 dissociation in2 2such case an increased efficiency is correlated to the N2admixture

2 2such case an increased efficiency is correlated to the N2admixture

bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial

bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial

bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2

bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2g p g 3 pp y 2g p g 3 pp y 2

Effect of methane on ozone efficiency and specific powerEffect of methane on ozone efficiency and specific power

Effect of Methane on Ozone Content in Outlet Gas and on Specific Power Pure O2

13 12

10

11

12

t 8

10

8

9

10

ne c

onte

nt w

t

6

8

ecifi

c po

wer

kW

hlb

5

6

7

Ozo

n

2

4 Spe

400E+00 20E+03 40E+03 60E+03 80E+03 10E+04 12E+04

Methane in feedgas ppm

0

Ozone content in the outlet gas Specif ic pow er of the ozone generatorg p p g

Effects of N2 and CH4Effects of N2 and CH4

Pi t f h t lli N O t tPicture of an amorphous-crystalline N2O5 structurecaptured at the Orlando Skylake water plant in 2006

Plasma Chemistry with CH4 Impurities

OxygenO2 N2

e - e -

CHO N2

NO2

O NO

O2 N O2 O3

NOH

CH4e-

O3 NO

NO2

O2O3NO N

NO2 O

NO2

NO2

N2ONO3

N

O3

NO2

NO

HNO3

N2O4

N2O5

NO2

NO3

N2O5

Effect of methane on the electrode surfaces

a) b)

Inlet Outlet Outlet

) d)

I l t I l t

c) d)

Electrode of the ozone generator afterseveral hours in CH8O2 and up to 2 wt of methane (a b c)

Inlet Inlet

three hours in CH8O2+traces of N2 and up to 1 wt of methane (d) Visible change of discharge character at about 13 length of electrode (a d)

Kinetics of CHx Conversion without N2

conversion by collisions

O2 + CHx 12wt O3 + CO2 +H2O

deposition vaporizationby sputtering

ibl b l 1000 CHreversible process below 1000ppm CH4

Effect of water on electrode surface with N2

Inlet

OutletOutlet

Electrode of the ozone generator after several hours in H OO N

Inlet

Electrode of the ozone generator after several hours in H2OO2N2

Effect of water on electrode surface

Long term effect (800 hrs) of H2OO2N2

Kinetics of CHx Conversion with N2

conversion by collisionsHNO3 formation

O2 + N2 +CHx 12wtO2 + CO2 +H2O + HNO3

deposition vaporizationby sputtering

H2O + HNO3

by sputtering

irreversible process above a N2 threshold () ltlt 1000ppm N2

sticky deposit

p 2 ( ) pp 2 any CH4 concentration (60ppm)

Plasma Chemistry with CH4 ImpuritiesPlasma Chemistry with CH4 Impurities4

bull Formation of NO and NO2 depends on O3 N2 and gas temperature Conclusion N2 admixture is the key factor

SummarySummaryyyThe mechanisms of formed NOx by-products follows the sameThe mechanisms of formed NOx by-products follows the sameprinciples as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentration

principles as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentrationozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)

ozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)g p ( g p )

The conversion of methane to OH and H2O is found to depend on

g p ( g p )

The conversion of methane to OH and H2O is found to depend ondissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)

dissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)discharge gap)discharge gap)

How do you optimize an ozone generatorg

Scientific ApproachScientific ApproachTheoretical Experimental

pppp

c [wt]

f [Hz]

c [wt]

f [Hz]

[kW]UUUβ1

1Cf4αPn

1iiminpeakimin

iiD

q [kWm2]q [kWm2]

150

180

][V]voltagepeakUpeak

[]cylinder perslicesofamountnsliceii

whereth

09 00

30

60

90

120

effic

ienc

y [

][0tdj t bl[F]sliceisdielectricofecapacitancC

[Hz]frequencyf[V]sliceivoltageminimumiUmin

thiD

th

10

28

46

64

82

39

107

176

244 power density

[kWm2]

ozone conc [wt][]CCβ

][0parameteradjustableα

iDiGi

Impact of Power Inductionp

350

400

wer

200

250

300

App

lied

Pow

Arr C 2Arr D +0

Arr E +45Arr F +7

Arr G +3

5 0

100

150

Frac

tion

of

1 2 3 4

ReferenceArr B unstable

Arr C -2

00

50

4Position (1inlet 4outlet)

Experimental Test Rigp g

Experimental Test Rigp g

Outer grounded electrode (left picture) and the dielectric covered inner electrodes (right) d e ect c cove ed e e ect odes ( g t)

Reference (Traditional) Arrangement

Inlet OutletGas flow direction

Optimized Arrangement

Inlet OutletGas flow direction

Intelligent Gap System (IGS)g p y ( )

Molecular Oxygen (O2) Ozone (O3)

O2 O3

yg ( 2) ( 3)

Particle Size SynthesisParticle Size SynthesisByBy--Products Cluster FormationProducts Cluster Formationyy

high diffusion and deposition to surfaces

low diffusion rate good transport

high sedimentation on the structurehigh sedimentation on the structure

Degreacutemont Technologies ndash OzoniaIntelligent Gap SystemIntelligent Gap System

G Vezzuacute JL Lopez A Freilich and K Becker Optimizationof Large-Scale Ozone Generators IEEE Transactions onPlasma Science Vol 37 No 6 p 890-896 (2009)

ConclusionsConclusionsConclusionsConclusionsFundamentals of ozone synthesis in a DBD plasmay p

ndash Highly filamented DBD discharges are best-suitedfor the production of ozone concentrations in therange of 6 to 14 wtrange of 6 to 14 wt

ndash The preferred characteristic of the microdischargesare Townsend-like at reduced electric fields Enaround 190 Townsend

ndash Detrimental side-effects induced by by-productscan be avoided by a proper design of the electrodecan be avoided by a proper design of the electrodearrangement The phenomenon is related to thediffusion rates of formed by-product clusters

ConclusionsConclusionsConclusionsConclusionsBenefits from DBD microplasma tailoring

ndash Reduced power consumption of up to 10 improvement

ndash Increased ozone concentrations of up to 14 now achievable

ndash Improved neutralization and conditioning of detrimental by-products

ndash Reduced system capital and operational cost

New technologies to improve ozone p

generatorg

HV Pulsed Power SwitchingHV Pulsed Power Switching

Microchannel Generation of Ozone

Channel ArrayChannel Array

Microchannel

330 microm 230 microm

Some Cap-DBD Devices Operating in Air

Increase of 60 of

Spacing 225 μmof 60 of plasma

No space

Cap‐DBD ozone generation

bull Ozone concentration is evaluated via Eco S d l UV 100 O A l (0 01Sensors model UV-100 Ozone Analyzer (001 ndash 900 ppm wiht an accuracy of plusmn2)

bull Three reactors 6 tubings 6rdquo with spacings of 0 μm 225 μm and 500 μm running at 3 kV μ μ μ g

SpacingOzone Concentration

3 kV rms 4 kV rms3 kV rms 4 kV rms

0 μm 660 ppm

225 μm 550 ppm

For a device of such small scale these ozone levels are promising

500 μm 380 ppm

J Mahoney W Zhu VS Johnson KH Becker and JL Lopez Electrical and optical emissionmeasurements of a capillary dielectric barrier discharge European Physics Journal D Vol 60 441-447(2010)

QuestionsQuestions

Thank YouFor more informationProf Jose L Lopez PhD

Thank YouFor more informationDepartment of Physics

Telephone (973) 761-9057Email joselopez1shuedu

Website wwwshueduacademicsartsciphysicsWebsite wwwshueduacademicsartsciphysics

Page 62: Dielectric Barrier Discharge (DBD) & Progress in Large ...bonitz/si12/talks/august_8/lopez_si12.pdf · Dielectric Barrier Discharge (DBD) & Progress in Large-Scale Ozone Generation

Applications of Ozone

Examples of Endocrine Disruptors1000rsquos of compounds that may be Investigated as EDCs ndash Some examples are

bullbull Synthetic HormonesSynthetic Hormonesbullbull Naturally Occurring Estrogens Naturally Occurring Estrogens

Health and Beauty AidsHealth and Beauty Aidsbullbull Health and Beauty AidsHealth and Beauty Aidsbullbull SolventsSolventsbullbull PesticidesPesticidesbullbull SurfactantsSurfactantsbullbull PlasticsPlastics

F i idF i idbullbull FungicidesFungicides

Ozone Water TreatmentOzone Water Treatment

Ozone Ozone -- Industrial ApplicationsIndustrial Applications-- Ultrapure Water for Pharmaceutical ApplicationsUltrapure Water for Pharmaceutical Applications

-- Wastewater disinfection color removalWastewater disinfection color removal

-- Soil and Groundwater Remediation Soil and Groundwater Remediation

-- Cooling Tower Water TreatmentCooling Tower Water Treatment

-- Food ProcessingFood Processing

-- Aquaculture AquariumsAquaculture AquariumsAquaculture AquariumsAquaculture Aquariums

-- Beverage ApplicationsBeverage Applications

P l amp P Bl hiP l amp P Bl hi-- Pulp amp Paper BleachingPulp amp Paper Bleaching

High Purity OzonationHigh Purity Ozonation

Microchip manufacturingMicrochip manufacturing

What are the current issues in large-scale gozone generationg

Experimental Setup

Front view of the two units after the redesign and reworking ofthe gas water and instruments connectionsthe gas water and instruments connections

Experimental Setup

Top view of the twoexperimental unitsexperimental unitsSpectroscope (notshown) is to the left ofthe DBD The units weredifferent with respect todifferent with respect totheir electrodes onehad only the electrodecoated with thedielectric (ldquosingle-dielectric ( single-coatedrdquo) the other onehad the electrode andthe anode coated withthe dielectric (ldquodouble-the dielectric ( double-coatedrdquo)

Basics Generation of OzoneBasics Generation of Ozone

SpectroscopyPlasma

Plasma Absorption SpectroscopyPlasma Absorption Spectroscopy

Infrared Absorption SpectroscopyInfrared Absorption Spectroscopy

IR spectra in pure oxygen (black curve) and at approximately 10wt N2 admixture (red line) N2O5 peaks appear at124 1 d 1 2 11245 cm-1 and at 1725 cm-1

Infrared Absorption SpectroscopyInfrared Absorption Spectroscopy

IR spectra of several methane variations The green curve envelopes all of the methane peaks at 1325 cm-1recorded at smaller methane admixtures Simultaneously the N2O5 peaks disappear as the methane peaks appear

N2O5 FormationN2O5 Formation2 52 5p=2 bara cwt=20degC q=35kWm2 f=1450Hz

45N2O5 AT95

30

35

40

N

2 B

lend

ing

N2O AT95N2O5 IGSN2O IGSN2O5 LGN2O LG

1 5

20

25

nt [p

pmV]

3

wt

05

10

15

NO

x co

nten

005 7 9 11 13 15 17

ozone conc [wt]

Amount of formed N2O5 and N2O as a function of ozone concentration at 3 wt of nitrogen admixture and fori l dvarious electrode arrangements

Plasma Emission SpectroscopyPlasma Emission Spectroscopyp pyp py

Relative Emissions of the Ozonizer plasmaRelative Emissions of the Ozonizer plasma

Region 300- 850 nm from individual (calibrated) regions (smoothed by PeakFit) Single-coated ozone generator Inlet side

3 5E+06

30E+06

35E+06

7 9

20E+06

25E+06

nten

sity

au

2

311 12

10E+06

15E+06

In 4

5

6 8 10

14

15

16

17

00E+00

50E+05

280 300 320 340 360 380 400 420 440 460 480 500 520 540 560 580 600 620 640 660 680 700 720 740 760 780 800 820 840 860

Wavelength nm

1 13

Wavelength nm

Absolute Emission of the DBD PlasmaAbsolute Emission of the DBD Plasma

Intensities in (O2+3 wtN2) plasma

1 20E+04

100E+04

120E+04

600E+03

800E+03

nten

sity

(au

)

200E+03

400E+03

In

O(777)

000E+00200 250 300 350 400 450 500 550 600 650 700 750 800 850

Wavelength nm

Intensities in 3 wtN2+O2 plasmaIntensities in 3 wtN2+O2 plasma

Plasma Chemistry in OzonizersPlasma Chemistry in Ozonizers

Dry Air O2 N2

e - e -

O N2 N O2

O3 NO

O2 N O2

O3

N

3

NO2

O2 O3

NO

N

NO2 O3

N2O

NO3 N

N2O4

NO2

NO2

N2O5

NO3

Primary electron-driven chemical reactions leading to the formation of N2O5 and N2O in a dry air plasma

Plasma emission diagnostics role of N2Plasma emission diagnostics role of N2

Dry Air O2 N2

e - e -

O N2 N O2

O3 NO

O2 N O2

O3

O

N

ON

NO2

O2O3

N

NO N

NO2 O3

N2O

NO3 N

N2O4

NO2

NO2

N2O5

NO3

ONbullWith N2 present ndash less oxygen atoms are formed However the difference in intensity is

very small

Modeling of plasma chemistry incl the NxOy chemistry up to N2O5 for different Oxygen Nitrogen mixtures varying power deposition scenarios

and initial ozone background concentrations (up to 15) previously done

The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation

The role of N2 must be related to its by-products reacting on the surface of the electrodeThe role of N2 must be related to its by-products reacting on the surface of the electrode

The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established

Ab 8 t f O

The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established

Ab 8 t f OAbove 8 wt of O3

1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)

Above 8 wt of O3

1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)case without pampp)

2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of the

case without pampp)

2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of thethem A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface

them A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface

The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation

Three possibilities have to be considered for the oxygen-fedozone generator

Three possibilities have to be considered for the oxygen-fedozone generatorozone generator

bull Excited N2 molecules lead to an increased O2 dissociation in

ozone generator

bull Excited N2 molecules lead to an increased O2 dissociation in2 2such case an increased efficiency is correlated to the N2admixture

2 2such case an increased efficiency is correlated to the N2admixture

bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial

bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial

bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2

bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2g p g 3 pp y 2g p g 3 pp y 2

Effect of methane on ozone efficiency and specific powerEffect of methane on ozone efficiency and specific power

Effect of Methane on Ozone Content in Outlet Gas and on Specific Power Pure O2

13 12

10

11

12

t 8

10

8

9

10

ne c

onte

nt w

t

6

8

ecifi

c po

wer

kW

hlb

5

6

7

Ozo

n

2

4 Spe

400E+00 20E+03 40E+03 60E+03 80E+03 10E+04 12E+04

Methane in feedgas ppm

0

Ozone content in the outlet gas Specif ic pow er of the ozone generatorg p p g

Effects of N2 and CH4Effects of N2 and CH4

Pi t f h t lli N O t tPicture of an amorphous-crystalline N2O5 structurecaptured at the Orlando Skylake water plant in 2006

Plasma Chemistry with CH4 Impurities

OxygenO2 N2

e - e -

CHO N2

NO2

O NO

O2 N O2 O3

NOH

CH4e-

O3 NO

NO2

O2O3NO N

NO2 O

NO2

NO2

N2ONO3

N

O3

NO2

NO

HNO3

N2O4

N2O5

NO2

NO3

N2O5

Effect of methane on the electrode surfaces

a) b)

Inlet Outlet Outlet

) d)

I l t I l t

c) d)

Electrode of the ozone generator afterseveral hours in CH8O2 and up to 2 wt of methane (a b c)

Inlet Inlet

three hours in CH8O2+traces of N2 and up to 1 wt of methane (d) Visible change of discharge character at about 13 length of electrode (a d)

Kinetics of CHx Conversion without N2

conversion by collisions

O2 + CHx 12wt O3 + CO2 +H2O

deposition vaporizationby sputtering

ibl b l 1000 CHreversible process below 1000ppm CH4

Effect of water on electrode surface with N2

Inlet

OutletOutlet

Electrode of the ozone generator after several hours in H OO N

Inlet

Electrode of the ozone generator after several hours in H2OO2N2

Effect of water on electrode surface

Long term effect (800 hrs) of H2OO2N2

Kinetics of CHx Conversion with N2

conversion by collisionsHNO3 formation

O2 + N2 +CHx 12wtO2 + CO2 +H2O + HNO3

deposition vaporizationby sputtering

H2O + HNO3

by sputtering

irreversible process above a N2 threshold () ltlt 1000ppm N2

sticky deposit

p 2 ( ) pp 2 any CH4 concentration (60ppm)

Plasma Chemistry with CH4 ImpuritiesPlasma Chemistry with CH4 Impurities4

bull Formation of NO and NO2 depends on O3 N2 and gas temperature Conclusion N2 admixture is the key factor

SummarySummaryyyThe mechanisms of formed NOx by-products follows the sameThe mechanisms of formed NOx by-products follows the sameprinciples as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentration

principles as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentrationozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)

ozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)g p ( g p )

The conversion of methane to OH and H2O is found to depend on

g p ( g p )

The conversion of methane to OH and H2O is found to depend ondissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)

dissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)discharge gap)discharge gap)

How do you optimize an ozone generatorg

Scientific ApproachScientific ApproachTheoretical Experimental

pppp

c [wt]

f [Hz]

c [wt]

f [Hz]

[kW]UUUβ1

1Cf4αPn

1iiminpeakimin

iiD

q [kWm2]q [kWm2]

150

180

][V]voltagepeakUpeak

[]cylinder perslicesofamountnsliceii

whereth

09 00

30

60

90

120

effic

ienc

y [

][0tdj t bl[F]sliceisdielectricofecapacitancC

[Hz]frequencyf[V]sliceivoltageminimumiUmin

thiD

th

10

28

46

64

82

39

107

176

244 power density

[kWm2]

ozone conc [wt][]CCβ

][0parameteradjustableα

iDiGi

Impact of Power Inductionp

350

400

wer

200

250

300

App

lied

Pow

Arr C 2Arr D +0

Arr E +45Arr F +7

Arr G +3

5 0

100

150

Frac

tion

of

1 2 3 4

ReferenceArr B unstable

Arr C -2

00

50

4Position (1inlet 4outlet)

Experimental Test Rigp g

Experimental Test Rigp g

Outer grounded electrode (left picture) and the dielectric covered inner electrodes (right) d e ect c cove ed e e ect odes ( g t)

Reference (Traditional) Arrangement

Inlet OutletGas flow direction

Optimized Arrangement

Inlet OutletGas flow direction

Intelligent Gap System (IGS)g p y ( )

Molecular Oxygen (O2) Ozone (O3)

O2 O3

yg ( 2) ( 3)

Particle Size SynthesisParticle Size SynthesisByBy--Products Cluster FormationProducts Cluster Formationyy

high diffusion and deposition to surfaces

low diffusion rate good transport

high sedimentation on the structurehigh sedimentation on the structure

Degreacutemont Technologies ndash OzoniaIntelligent Gap SystemIntelligent Gap System

G Vezzuacute JL Lopez A Freilich and K Becker Optimizationof Large-Scale Ozone Generators IEEE Transactions onPlasma Science Vol 37 No 6 p 890-896 (2009)

ConclusionsConclusionsConclusionsConclusionsFundamentals of ozone synthesis in a DBD plasmay p

ndash Highly filamented DBD discharges are best-suitedfor the production of ozone concentrations in therange of 6 to 14 wtrange of 6 to 14 wt

ndash The preferred characteristic of the microdischargesare Townsend-like at reduced electric fields Enaround 190 Townsend

ndash Detrimental side-effects induced by by-productscan be avoided by a proper design of the electrodecan be avoided by a proper design of the electrodearrangement The phenomenon is related to thediffusion rates of formed by-product clusters

ConclusionsConclusionsConclusionsConclusionsBenefits from DBD microplasma tailoring

ndash Reduced power consumption of up to 10 improvement

ndash Increased ozone concentrations of up to 14 now achievable

ndash Improved neutralization and conditioning of detrimental by-products

ndash Reduced system capital and operational cost

New technologies to improve ozone p

generatorg

HV Pulsed Power SwitchingHV Pulsed Power Switching

Microchannel Generation of Ozone

Channel ArrayChannel Array

Microchannel

330 microm 230 microm

Some Cap-DBD Devices Operating in Air

Increase of 60 of

Spacing 225 μmof 60 of plasma

No space

Cap‐DBD ozone generation

bull Ozone concentration is evaluated via Eco S d l UV 100 O A l (0 01Sensors model UV-100 Ozone Analyzer (001 ndash 900 ppm wiht an accuracy of plusmn2)

bull Three reactors 6 tubings 6rdquo with spacings of 0 μm 225 μm and 500 μm running at 3 kV μ μ μ g

SpacingOzone Concentration

3 kV rms 4 kV rms3 kV rms 4 kV rms

0 μm 660 ppm

225 μm 550 ppm

For a device of such small scale these ozone levels are promising

500 μm 380 ppm

J Mahoney W Zhu VS Johnson KH Becker and JL Lopez Electrical and optical emissionmeasurements of a capillary dielectric barrier discharge European Physics Journal D Vol 60 441-447(2010)

QuestionsQuestions

Thank YouFor more informationProf Jose L Lopez PhD

Thank YouFor more informationDepartment of Physics

Telephone (973) 761-9057Email joselopez1shuedu

Website wwwshueduacademicsartsciphysicsWebsite wwwshueduacademicsartsciphysics

Page 63: Dielectric Barrier Discharge (DBD) & Progress in Large ...bonitz/si12/talks/august_8/lopez_si12.pdf · Dielectric Barrier Discharge (DBD) & Progress in Large-Scale Ozone Generation

Ozone Water TreatmentOzone Water Treatment

Ozone Ozone -- Industrial ApplicationsIndustrial Applications-- Ultrapure Water for Pharmaceutical ApplicationsUltrapure Water for Pharmaceutical Applications

-- Wastewater disinfection color removalWastewater disinfection color removal

-- Soil and Groundwater Remediation Soil and Groundwater Remediation

-- Cooling Tower Water TreatmentCooling Tower Water Treatment

-- Food ProcessingFood Processing

-- Aquaculture AquariumsAquaculture AquariumsAquaculture AquariumsAquaculture Aquariums

-- Beverage ApplicationsBeverage Applications

P l amp P Bl hiP l amp P Bl hi-- Pulp amp Paper BleachingPulp amp Paper Bleaching

High Purity OzonationHigh Purity Ozonation

Microchip manufacturingMicrochip manufacturing

What are the current issues in large-scale gozone generationg

Experimental Setup

Front view of the two units after the redesign and reworking ofthe gas water and instruments connectionsthe gas water and instruments connections

Experimental Setup

Top view of the twoexperimental unitsexperimental unitsSpectroscope (notshown) is to the left ofthe DBD The units weredifferent with respect todifferent with respect totheir electrodes onehad only the electrodecoated with thedielectric (ldquosingle-dielectric ( single-coatedrdquo) the other onehad the electrode andthe anode coated withthe dielectric (ldquodouble-the dielectric ( double-coatedrdquo)

Basics Generation of OzoneBasics Generation of Ozone

SpectroscopyPlasma

Plasma Absorption SpectroscopyPlasma Absorption Spectroscopy

Infrared Absorption SpectroscopyInfrared Absorption Spectroscopy

IR spectra in pure oxygen (black curve) and at approximately 10wt N2 admixture (red line) N2O5 peaks appear at124 1 d 1 2 11245 cm-1 and at 1725 cm-1

Infrared Absorption SpectroscopyInfrared Absorption Spectroscopy

IR spectra of several methane variations The green curve envelopes all of the methane peaks at 1325 cm-1recorded at smaller methane admixtures Simultaneously the N2O5 peaks disappear as the methane peaks appear

N2O5 FormationN2O5 Formation2 52 5p=2 bara cwt=20degC q=35kWm2 f=1450Hz

45N2O5 AT95

30

35

40

N

2 B

lend

ing

N2O AT95N2O5 IGSN2O IGSN2O5 LGN2O LG

1 5

20

25

nt [p

pmV]

3

wt

05

10

15

NO

x co

nten

005 7 9 11 13 15 17

ozone conc [wt]

Amount of formed N2O5 and N2O as a function of ozone concentration at 3 wt of nitrogen admixture and fori l dvarious electrode arrangements

Plasma Emission SpectroscopyPlasma Emission Spectroscopyp pyp py

Relative Emissions of the Ozonizer plasmaRelative Emissions of the Ozonizer plasma

Region 300- 850 nm from individual (calibrated) regions (smoothed by PeakFit) Single-coated ozone generator Inlet side

3 5E+06

30E+06

35E+06

7 9

20E+06

25E+06

nten

sity

au

2

311 12

10E+06

15E+06

In 4

5

6 8 10

14

15

16

17

00E+00

50E+05

280 300 320 340 360 380 400 420 440 460 480 500 520 540 560 580 600 620 640 660 680 700 720 740 760 780 800 820 840 860

Wavelength nm

1 13

Wavelength nm

Absolute Emission of the DBD PlasmaAbsolute Emission of the DBD Plasma

Intensities in (O2+3 wtN2) plasma

1 20E+04

100E+04

120E+04

600E+03

800E+03

nten

sity

(au

)

200E+03

400E+03

In

O(777)

000E+00200 250 300 350 400 450 500 550 600 650 700 750 800 850

Wavelength nm

Intensities in 3 wtN2+O2 plasmaIntensities in 3 wtN2+O2 plasma

Plasma Chemistry in OzonizersPlasma Chemistry in Ozonizers

Dry Air O2 N2

e - e -

O N2 N O2

O3 NO

O2 N O2

O3

N

3

NO2

O2 O3

NO

N

NO2 O3

N2O

NO3 N

N2O4

NO2

NO2

N2O5

NO3

Primary electron-driven chemical reactions leading to the formation of N2O5 and N2O in a dry air plasma

Plasma emission diagnostics role of N2Plasma emission diagnostics role of N2

Dry Air O2 N2

e - e -

O N2 N O2

O3 NO

O2 N O2

O3

O

N

ON

NO2

O2O3

N

NO N

NO2 O3

N2O

NO3 N

N2O4

NO2

NO2

N2O5

NO3

ONbullWith N2 present ndash less oxygen atoms are formed However the difference in intensity is

very small

Modeling of plasma chemistry incl the NxOy chemistry up to N2O5 for different Oxygen Nitrogen mixtures varying power deposition scenarios

and initial ozone background concentrations (up to 15) previously done

The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation

The role of N2 must be related to its by-products reacting on the surface of the electrodeThe role of N2 must be related to its by-products reacting on the surface of the electrode

The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established

Ab 8 t f O

The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established

Ab 8 t f OAbove 8 wt of O3

1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)

Above 8 wt of O3

1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)case without pampp)

2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of the

case without pampp)

2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of thethem A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface

them A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface

The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation

Three possibilities have to be considered for the oxygen-fedozone generator

Three possibilities have to be considered for the oxygen-fedozone generatorozone generator

bull Excited N2 molecules lead to an increased O2 dissociation in

ozone generator

bull Excited N2 molecules lead to an increased O2 dissociation in2 2such case an increased efficiency is correlated to the N2admixture

2 2such case an increased efficiency is correlated to the N2admixture

bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial

bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial

bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2

bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2g p g 3 pp y 2g p g 3 pp y 2

Effect of methane on ozone efficiency and specific powerEffect of methane on ozone efficiency and specific power

Effect of Methane on Ozone Content in Outlet Gas and on Specific Power Pure O2

13 12

10

11

12

t 8

10

8

9

10

ne c

onte

nt w

t

6

8

ecifi

c po

wer

kW

hlb

5

6

7

Ozo

n

2

4 Spe

400E+00 20E+03 40E+03 60E+03 80E+03 10E+04 12E+04

Methane in feedgas ppm

0

Ozone content in the outlet gas Specif ic pow er of the ozone generatorg p p g

Effects of N2 and CH4Effects of N2 and CH4

Pi t f h t lli N O t tPicture of an amorphous-crystalline N2O5 structurecaptured at the Orlando Skylake water plant in 2006

Plasma Chemistry with CH4 Impurities

OxygenO2 N2

e - e -

CHO N2

NO2

O NO

O2 N O2 O3

NOH

CH4e-

O3 NO

NO2

O2O3NO N

NO2 O

NO2

NO2

N2ONO3

N

O3

NO2

NO

HNO3

N2O4

N2O5

NO2

NO3

N2O5

Effect of methane on the electrode surfaces

a) b)

Inlet Outlet Outlet

) d)

I l t I l t

c) d)

Electrode of the ozone generator afterseveral hours in CH8O2 and up to 2 wt of methane (a b c)

Inlet Inlet

three hours in CH8O2+traces of N2 and up to 1 wt of methane (d) Visible change of discharge character at about 13 length of electrode (a d)

Kinetics of CHx Conversion without N2

conversion by collisions

O2 + CHx 12wt O3 + CO2 +H2O

deposition vaporizationby sputtering

ibl b l 1000 CHreversible process below 1000ppm CH4

Effect of water on electrode surface with N2

Inlet

OutletOutlet

Electrode of the ozone generator after several hours in H OO N

Inlet

Electrode of the ozone generator after several hours in H2OO2N2

Effect of water on electrode surface

Long term effect (800 hrs) of H2OO2N2

Kinetics of CHx Conversion with N2

conversion by collisionsHNO3 formation

O2 + N2 +CHx 12wtO2 + CO2 +H2O + HNO3

deposition vaporizationby sputtering

H2O + HNO3

by sputtering

irreversible process above a N2 threshold () ltlt 1000ppm N2

sticky deposit

p 2 ( ) pp 2 any CH4 concentration (60ppm)

Plasma Chemistry with CH4 ImpuritiesPlasma Chemistry with CH4 Impurities4

bull Formation of NO and NO2 depends on O3 N2 and gas temperature Conclusion N2 admixture is the key factor

SummarySummaryyyThe mechanisms of formed NOx by-products follows the sameThe mechanisms of formed NOx by-products follows the sameprinciples as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentration

principles as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentrationozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)

ozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)g p ( g p )

The conversion of methane to OH and H2O is found to depend on

g p ( g p )

The conversion of methane to OH and H2O is found to depend ondissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)

dissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)discharge gap)discharge gap)

How do you optimize an ozone generatorg

Scientific ApproachScientific ApproachTheoretical Experimental

pppp

c [wt]

f [Hz]

c [wt]

f [Hz]

[kW]UUUβ1

1Cf4αPn

1iiminpeakimin

iiD

q [kWm2]q [kWm2]

150

180

][V]voltagepeakUpeak

[]cylinder perslicesofamountnsliceii

whereth

09 00

30

60

90

120

effic

ienc

y [

][0tdj t bl[F]sliceisdielectricofecapacitancC

[Hz]frequencyf[V]sliceivoltageminimumiUmin

thiD

th

10

28

46

64

82

39

107

176

244 power density

[kWm2]

ozone conc [wt][]CCβ

][0parameteradjustableα

iDiGi

Impact of Power Inductionp

350

400

wer

200

250

300

App

lied

Pow

Arr C 2Arr D +0

Arr E +45Arr F +7

Arr G +3

5 0

100

150

Frac

tion

of

1 2 3 4

ReferenceArr B unstable

Arr C -2

00

50

4Position (1inlet 4outlet)

Experimental Test Rigp g

Experimental Test Rigp g

Outer grounded electrode (left picture) and the dielectric covered inner electrodes (right) d e ect c cove ed e e ect odes ( g t)

Reference (Traditional) Arrangement

Inlet OutletGas flow direction

Optimized Arrangement

Inlet OutletGas flow direction

Intelligent Gap System (IGS)g p y ( )

Molecular Oxygen (O2) Ozone (O3)

O2 O3

yg ( 2) ( 3)

Particle Size SynthesisParticle Size SynthesisByBy--Products Cluster FormationProducts Cluster Formationyy

high diffusion and deposition to surfaces

low diffusion rate good transport

high sedimentation on the structurehigh sedimentation on the structure

Degreacutemont Technologies ndash OzoniaIntelligent Gap SystemIntelligent Gap System

G Vezzuacute JL Lopez A Freilich and K Becker Optimizationof Large-Scale Ozone Generators IEEE Transactions onPlasma Science Vol 37 No 6 p 890-896 (2009)

ConclusionsConclusionsConclusionsConclusionsFundamentals of ozone synthesis in a DBD plasmay p

ndash Highly filamented DBD discharges are best-suitedfor the production of ozone concentrations in therange of 6 to 14 wtrange of 6 to 14 wt

ndash The preferred characteristic of the microdischargesare Townsend-like at reduced electric fields Enaround 190 Townsend

ndash Detrimental side-effects induced by by-productscan be avoided by a proper design of the electrodecan be avoided by a proper design of the electrodearrangement The phenomenon is related to thediffusion rates of formed by-product clusters

ConclusionsConclusionsConclusionsConclusionsBenefits from DBD microplasma tailoring

ndash Reduced power consumption of up to 10 improvement

ndash Increased ozone concentrations of up to 14 now achievable

ndash Improved neutralization and conditioning of detrimental by-products

ndash Reduced system capital and operational cost

New technologies to improve ozone p

generatorg

HV Pulsed Power SwitchingHV Pulsed Power Switching

Microchannel Generation of Ozone

Channel ArrayChannel Array

Microchannel

330 microm 230 microm

Some Cap-DBD Devices Operating in Air

Increase of 60 of

Spacing 225 μmof 60 of plasma

No space

Cap‐DBD ozone generation

bull Ozone concentration is evaluated via Eco S d l UV 100 O A l (0 01Sensors model UV-100 Ozone Analyzer (001 ndash 900 ppm wiht an accuracy of plusmn2)

bull Three reactors 6 tubings 6rdquo with spacings of 0 μm 225 μm and 500 μm running at 3 kV μ μ μ g

SpacingOzone Concentration

3 kV rms 4 kV rms3 kV rms 4 kV rms

0 μm 660 ppm

225 μm 550 ppm

For a device of such small scale these ozone levels are promising

500 μm 380 ppm

J Mahoney W Zhu VS Johnson KH Becker and JL Lopez Electrical and optical emissionmeasurements of a capillary dielectric barrier discharge European Physics Journal D Vol 60 441-447(2010)

QuestionsQuestions

Thank YouFor more informationProf Jose L Lopez PhD

Thank YouFor more informationDepartment of Physics

Telephone (973) 761-9057Email joselopez1shuedu

Website wwwshueduacademicsartsciphysicsWebsite wwwshueduacademicsartsciphysics

Page 64: Dielectric Barrier Discharge (DBD) & Progress in Large ...bonitz/si12/talks/august_8/lopez_si12.pdf · Dielectric Barrier Discharge (DBD) & Progress in Large-Scale Ozone Generation

High Purity OzonationHigh Purity Ozonation

Microchip manufacturingMicrochip manufacturing

What are the current issues in large-scale gozone generationg

Experimental Setup

Front view of the two units after the redesign and reworking ofthe gas water and instruments connectionsthe gas water and instruments connections

Experimental Setup

Top view of the twoexperimental unitsexperimental unitsSpectroscope (notshown) is to the left ofthe DBD The units weredifferent with respect todifferent with respect totheir electrodes onehad only the electrodecoated with thedielectric (ldquosingle-dielectric ( single-coatedrdquo) the other onehad the electrode andthe anode coated withthe dielectric (ldquodouble-the dielectric ( double-coatedrdquo)

Basics Generation of OzoneBasics Generation of Ozone

SpectroscopyPlasma

Plasma Absorption SpectroscopyPlasma Absorption Spectroscopy

Infrared Absorption SpectroscopyInfrared Absorption Spectroscopy

IR spectra in pure oxygen (black curve) and at approximately 10wt N2 admixture (red line) N2O5 peaks appear at124 1 d 1 2 11245 cm-1 and at 1725 cm-1

Infrared Absorption SpectroscopyInfrared Absorption Spectroscopy

IR spectra of several methane variations The green curve envelopes all of the methane peaks at 1325 cm-1recorded at smaller methane admixtures Simultaneously the N2O5 peaks disappear as the methane peaks appear

N2O5 FormationN2O5 Formation2 52 5p=2 bara cwt=20degC q=35kWm2 f=1450Hz

45N2O5 AT95

30

35

40

N

2 B

lend

ing

N2O AT95N2O5 IGSN2O IGSN2O5 LGN2O LG

1 5

20

25

nt [p

pmV]

3

wt

05

10

15

NO

x co

nten

005 7 9 11 13 15 17

ozone conc [wt]

Amount of formed N2O5 and N2O as a function of ozone concentration at 3 wt of nitrogen admixture and fori l dvarious electrode arrangements

Plasma Emission SpectroscopyPlasma Emission Spectroscopyp pyp py

Relative Emissions of the Ozonizer plasmaRelative Emissions of the Ozonizer plasma

Region 300- 850 nm from individual (calibrated) regions (smoothed by PeakFit) Single-coated ozone generator Inlet side

3 5E+06

30E+06

35E+06

7 9

20E+06

25E+06

nten

sity

au

2

311 12

10E+06

15E+06

In 4

5

6 8 10

14

15

16

17

00E+00

50E+05

280 300 320 340 360 380 400 420 440 460 480 500 520 540 560 580 600 620 640 660 680 700 720 740 760 780 800 820 840 860

Wavelength nm

1 13

Wavelength nm

Absolute Emission of the DBD PlasmaAbsolute Emission of the DBD Plasma

Intensities in (O2+3 wtN2) plasma

1 20E+04

100E+04

120E+04

600E+03

800E+03

nten

sity

(au

)

200E+03

400E+03

In

O(777)

000E+00200 250 300 350 400 450 500 550 600 650 700 750 800 850

Wavelength nm

Intensities in 3 wtN2+O2 plasmaIntensities in 3 wtN2+O2 plasma

Plasma Chemistry in OzonizersPlasma Chemistry in Ozonizers

Dry Air O2 N2

e - e -

O N2 N O2

O3 NO

O2 N O2

O3

N

3

NO2

O2 O3

NO

N

NO2 O3

N2O

NO3 N

N2O4

NO2

NO2

N2O5

NO3

Primary electron-driven chemical reactions leading to the formation of N2O5 and N2O in a dry air plasma

Plasma emission diagnostics role of N2Plasma emission diagnostics role of N2

Dry Air O2 N2

e - e -

O N2 N O2

O3 NO

O2 N O2

O3

O

N

ON

NO2

O2O3

N

NO N

NO2 O3

N2O

NO3 N

N2O4

NO2

NO2

N2O5

NO3

ONbullWith N2 present ndash less oxygen atoms are formed However the difference in intensity is

very small

Modeling of plasma chemistry incl the NxOy chemistry up to N2O5 for different Oxygen Nitrogen mixtures varying power deposition scenarios

and initial ozone background concentrations (up to 15) previously done

The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation

The role of N2 must be related to its by-products reacting on the surface of the electrodeThe role of N2 must be related to its by-products reacting on the surface of the electrode

The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established

Ab 8 t f O

The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established

Ab 8 t f OAbove 8 wt of O3

1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)

Above 8 wt of O3

1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)case without pampp)

2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of the

case without pampp)

2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of thethem A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface

them A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface

The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation

Three possibilities have to be considered for the oxygen-fedozone generator

Three possibilities have to be considered for the oxygen-fedozone generatorozone generator

bull Excited N2 molecules lead to an increased O2 dissociation in

ozone generator

bull Excited N2 molecules lead to an increased O2 dissociation in2 2such case an increased efficiency is correlated to the N2admixture

2 2such case an increased efficiency is correlated to the N2admixture

bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial

bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial

bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2

bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2g p g 3 pp y 2g p g 3 pp y 2

Effect of methane on ozone efficiency and specific powerEffect of methane on ozone efficiency and specific power

Effect of Methane on Ozone Content in Outlet Gas and on Specific Power Pure O2

13 12

10

11

12

t 8

10

8

9

10

ne c

onte

nt w

t

6

8

ecifi

c po

wer

kW

hlb

5

6

7

Ozo

n

2

4 Spe

400E+00 20E+03 40E+03 60E+03 80E+03 10E+04 12E+04

Methane in feedgas ppm

0

Ozone content in the outlet gas Specif ic pow er of the ozone generatorg p p g

Effects of N2 and CH4Effects of N2 and CH4

Pi t f h t lli N O t tPicture of an amorphous-crystalline N2O5 structurecaptured at the Orlando Skylake water plant in 2006

Plasma Chemistry with CH4 Impurities

OxygenO2 N2

e - e -

CHO N2

NO2

O NO

O2 N O2 O3

NOH

CH4e-

O3 NO

NO2

O2O3NO N

NO2 O

NO2

NO2

N2ONO3

N

O3

NO2

NO

HNO3

N2O4

N2O5

NO2

NO3

N2O5

Effect of methane on the electrode surfaces

a) b)

Inlet Outlet Outlet

) d)

I l t I l t

c) d)

Electrode of the ozone generator afterseveral hours in CH8O2 and up to 2 wt of methane (a b c)

Inlet Inlet

three hours in CH8O2+traces of N2 and up to 1 wt of methane (d) Visible change of discharge character at about 13 length of electrode (a d)

Kinetics of CHx Conversion without N2

conversion by collisions

O2 + CHx 12wt O3 + CO2 +H2O

deposition vaporizationby sputtering

ibl b l 1000 CHreversible process below 1000ppm CH4

Effect of water on electrode surface with N2

Inlet

OutletOutlet

Electrode of the ozone generator after several hours in H OO N

Inlet

Electrode of the ozone generator after several hours in H2OO2N2

Effect of water on electrode surface

Long term effect (800 hrs) of H2OO2N2

Kinetics of CHx Conversion with N2

conversion by collisionsHNO3 formation

O2 + N2 +CHx 12wtO2 + CO2 +H2O + HNO3

deposition vaporizationby sputtering

H2O + HNO3

by sputtering

irreversible process above a N2 threshold () ltlt 1000ppm N2

sticky deposit

p 2 ( ) pp 2 any CH4 concentration (60ppm)

Plasma Chemistry with CH4 ImpuritiesPlasma Chemistry with CH4 Impurities4

bull Formation of NO and NO2 depends on O3 N2 and gas temperature Conclusion N2 admixture is the key factor

SummarySummaryyyThe mechanisms of formed NOx by-products follows the sameThe mechanisms of formed NOx by-products follows the sameprinciples as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentration

principles as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentrationozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)

ozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)g p ( g p )

The conversion of methane to OH and H2O is found to depend on

g p ( g p )

The conversion of methane to OH and H2O is found to depend ondissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)

dissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)discharge gap)discharge gap)

How do you optimize an ozone generatorg

Scientific ApproachScientific ApproachTheoretical Experimental

pppp

c [wt]

f [Hz]

c [wt]

f [Hz]

[kW]UUUβ1

1Cf4αPn

1iiminpeakimin

iiD

q [kWm2]q [kWm2]

150

180

][V]voltagepeakUpeak

[]cylinder perslicesofamountnsliceii

whereth

09 00

30

60

90

120

effic

ienc

y [

][0tdj t bl[F]sliceisdielectricofecapacitancC

[Hz]frequencyf[V]sliceivoltageminimumiUmin

thiD

th

10

28

46

64

82

39

107

176

244 power density

[kWm2]

ozone conc [wt][]CCβ

][0parameteradjustableα

iDiGi

Impact of Power Inductionp

350

400

wer

200

250

300

App

lied

Pow

Arr C 2Arr D +0

Arr E +45Arr F +7

Arr G +3

5 0

100

150

Frac

tion

of

1 2 3 4

ReferenceArr B unstable

Arr C -2

00

50

4Position (1inlet 4outlet)

Experimental Test Rigp g

Experimental Test Rigp g

Outer grounded electrode (left picture) and the dielectric covered inner electrodes (right) d e ect c cove ed e e ect odes ( g t)

Reference (Traditional) Arrangement

Inlet OutletGas flow direction

Optimized Arrangement

Inlet OutletGas flow direction

Intelligent Gap System (IGS)g p y ( )

Molecular Oxygen (O2) Ozone (O3)

O2 O3

yg ( 2) ( 3)

Particle Size SynthesisParticle Size SynthesisByBy--Products Cluster FormationProducts Cluster Formationyy

high diffusion and deposition to surfaces

low diffusion rate good transport

high sedimentation on the structurehigh sedimentation on the structure

Degreacutemont Technologies ndash OzoniaIntelligent Gap SystemIntelligent Gap System

G Vezzuacute JL Lopez A Freilich and K Becker Optimizationof Large-Scale Ozone Generators IEEE Transactions onPlasma Science Vol 37 No 6 p 890-896 (2009)

ConclusionsConclusionsConclusionsConclusionsFundamentals of ozone synthesis in a DBD plasmay p

ndash Highly filamented DBD discharges are best-suitedfor the production of ozone concentrations in therange of 6 to 14 wtrange of 6 to 14 wt

ndash The preferred characteristic of the microdischargesare Townsend-like at reduced electric fields Enaround 190 Townsend

ndash Detrimental side-effects induced by by-productscan be avoided by a proper design of the electrodecan be avoided by a proper design of the electrodearrangement The phenomenon is related to thediffusion rates of formed by-product clusters

ConclusionsConclusionsConclusionsConclusionsBenefits from DBD microplasma tailoring

ndash Reduced power consumption of up to 10 improvement

ndash Increased ozone concentrations of up to 14 now achievable

ndash Improved neutralization and conditioning of detrimental by-products

ndash Reduced system capital and operational cost

New technologies to improve ozone p

generatorg

HV Pulsed Power SwitchingHV Pulsed Power Switching

Microchannel Generation of Ozone

Channel ArrayChannel Array

Microchannel

330 microm 230 microm

Some Cap-DBD Devices Operating in Air

Increase of 60 of

Spacing 225 μmof 60 of plasma

No space

Cap‐DBD ozone generation

bull Ozone concentration is evaluated via Eco S d l UV 100 O A l (0 01Sensors model UV-100 Ozone Analyzer (001 ndash 900 ppm wiht an accuracy of plusmn2)

bull Three reactors 6 tubings 6rdquo with spacings of 0 μm 225 μm and 500 μm running at 3 kV μ μ μ g

SpacingOzone Concentration

3 kV rms 4 kV rms3 kV rms 4 kV rms

0 μm 660 ppm

225 μm 550 ppm

For a device of such small scale these ozone levels are promising

500 μm 380 ppm

J Mahoney W Zhu VS Johnson KH Becker and JL Lopez Electrical and optical emissionmeasurements of a capillary dielectric barrier discharge European Physics Journal D Vol 60 441-447(2010)

QuestionsQuestions

Thank YouFor more informationProf Jose L Lopez PhD

Thank YouFor more informationDepartment of Physics

Telephone (973) 761-9057Email joselopez1shuedu

Website wwwshueduacademicsartsciphysicsWebsite wwwshueduacademicsartsciphysics

Page 65: Dielectric Barrier Discharge (DBD) & Progress in Large ...bonitz/si12/talks/august_8/lopez_si12.pdf · Dielectric Barrier Discharge (DBD) & Progress in Large-Scale Ozone Generation

What are the current issues in large-scale gozone generationg

Experimental Setup

Front view of the two units after the redesign and reworking ofthe gas water and instruments connectionsthe gas water and instruments connections

Experimental Setup

Top view of the twoexperimental unitsexperimental unitsSpectroscope (notshown) is to the left ofthe DBD The units weredifferent with respect todifferent with respect totheir electrodes onehad only the electrodecoated with thedielectric (ldquosingle-dielectric ( single-coatedrdquo) the other onehad the electrode andthe anode coated withthe dielectric (ldquodouble-the dielectric ( double-coatedrdquo)

Basics Generation of OzoneBasics Generation of Ozone

SpectroscopyPlasma

Plasma Absorption SpectroscopyPlasma Absorption Spectroscopy

Infrared Absorption SpectroscopyInfrared Absorption Spectroscopy

IR spectra in pure oxygen (black curve) and at approximately 10wt N2 admixture (red line) N2O5 peaks appear at124 1 d 1 2 11245 cm-1 and at 1725 cm-1

Infrared Absorption SpectroscopyInfrared Absorption Spectroscopy

IR spectra of several methane variations The green curve envelopes all of the methane peaks at 1325 cm-1recorded at smaller methane admixtures Simultaneously the N2O5 peaks disappear as the methane peaks appear

N2O5 FormationN2O5 Formation2 52 5p=2 bara cwt=20degC q=35kWm2 f=1450Hz

45N2O5 AT95

30

35

40

N

2 B

lend

ing

N2O AT95N2O5 IGSN2O IGSN2O5 LGN2O LG

1 5

20

25

nt [p

pmV]

3

wt

05

10

15

NO

x co

nten

005 7 9 11 13 15 17

ozone conc [wt]

Amount of formed N2O5 and N2O as a function of ozone concentration at 3 wt of nitrogen admixture and fori l dvarious electrode arrangements

Plasma Emission SpectroscopyPlasma Emission Spectroscopyp pyp py

Relative Emissions of the Ozonizer plasmaRelative Emissions of the Ozonizer plasma

Region 300- 850 nm from individual (calibrated) regions (smoothed by PeakFit) Single-coated ozone generator Inlet side

3 5E+06

30E+06

35E+06

7 9

20E+06

25E+06

nten

sity

au

2

311 12

10E+06

15E+06

In 4

5

6 8 10

14

15

16

17

00E+00

50E+05

280 300 320 340 360 380 400 420 440 460 480 500 520 540 560 580 600 620 640 660 680 700 720 740 760 780 800 820 840 860

Wavelength nm

1 13

Wavelength nm

Absolute Emission of the DBD PlasmaAbsolute Emission of the DBD Plasma

Intensities in (O2+3 wtN2) plasma

1 20E+04

100E+04

120E+04

600E+03

800E+03

nten

sity

(au

)

200E+03

400E+03

In

O(777)

000E+00200 250 300 350 400 450 500 550 600 650 700 750 800 850

Wavelength nm

Intensities in 3 wtN2+O2 plasmaIntensities in 3 wtN2+O2 plasma

Plasma Chemistry in OzonizersPlasma Chemistry in Ozonizers

Dry Air O2 N2

e - e -

O N2 N O2

O3 NO

O2 N O2

O3

N

3

NO2

O2 O3

NO

N

NO2 O3

N2O

NO3 N

N2O4

NO2

NO2

N2O5

NO3

Primary electron-driven chemical reactions leading to the formation of N2O5 and N2O in a dry air plasma

Plasma emission diagnostics role of N2Plasma emission diagnostics role of N2

Dry Air O2 N2

e - e -

O N2 N O2

O3 NO

O2 N O2

O3

O

N

ON

NO2

O2O3

N

NO N

NO2 O3

N2O

NO3 N

N2O4

NO2

NO2

N2O5

NO3

ONbullWith N2 present ndash less oxygen atoms are formed However the difference in intensity is

very small

Modeling of plasma chemistry incl the NxOy chemistry up to N2O5 for different Oxygen Nitrogen mixtures varying power deposition scenarios

and initial ozone background concentrations (up to 15) previously done

The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation

The role of N2 must be related to its by-products reacting on the surface of the electrodeThe role of N2 must be related to its by-products reacting on the surface of the electrode

The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established

Ab 8 t f O

The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established

Ab 8 t f OAbove 8 wt of O3

1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)

Above 8 wt of O3

1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)case without pampp)

2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of the

case without pampp)

2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of thethem A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface

them A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface

The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation

Three possibilities have to be considered for the oxygen-fedozone generator

Three possibilities have to be considered for the oxygen-fedozone generatorozone generator

bull Excited N2 molecules lead to an increased O2 dissociation in

ozone generator

bull Excited N2 molecules lead to an increased O2 dissociation in2 2such case an increased efficiency is correlated to the N2admixture

2 2such case an increased efficiency is correlated to the N2admixture

bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial

bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial

bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2

bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2g p g 3 pp y 2g p g 3 pp y 2

Effect of methane on ozone efficiency and specific powerEffect of methane on ozone efficiency and specific power

Effect of Methane on Ozone Content in Outlet Gas and on Specific Power Pure O2

13 12

10

11

12

t 8

10

8

9

10

ne c

onte

nt w

t

6

8

ecifi

c po

wer

kW

hlb

5

6

7

Ozo

n

2

4 Spe

400E+00 20E+03 40E+03 60E+03 80E+03 10E+04 12E+04

Methane in feedgas ppm

0

Ozone content in the outlet gas Specif ic pow er of the ozone generatorg p p g

Effects of N2 and CH4Effects of N2 and CH4

Pi t f h t lli N O t tPicture of an amorphous-crystalline N2O5 structurecaptured at the Orlando Skylake water plant in 2006

Plasma Chemistry with CH4 Impurities

OxygenO2 N2

e - e -

CHO N2

NO2

O NO

O2 N O2 O3

NOH

CH4e-

O3 NO

NO2

O2O3NO N

NO2 O

NO2

NO2

N2ONO3

N

O3

NO2

NO

HNO3

N2O4

N2O5

NO2

NO3

N2O5

Effect of methane on the electrode surfaces

a) b)

Inlet Outlet Outlet

) d)

I l t I l t

c) d)

Electrode of the ozone generator afterseveral hours in CH8O2 and up to 2 wt of methane (a b c)

Inlet Inlet

three hours in CH8O2+traces of N2 and up to 1 wt of methane (d) Visible change of discharge character at about 13 length of electrode (a d)

Kinetics of CHx Conversion without N2

conversion by collisions

O2 + CHx 12wt O3 + CO2 +H2O

deposition vaporizationby sputtering

ibl b l 1000 CHreversible process below 1000ppm CH4

Effect of water on electrode surface with N2

Inlet

OutletOutlet

Electrode of the ozone generator after several hours in H OO N

Inlet

Electrode of the ozone generator after several hours in H2OO2N2

Effect of water on electrode surface

Long term effect (800 hrs) of H2OO2N2

Kinetics of CHx Conversion with N2

conversion by collisionsHNO3 formation

O2 + N2 +CHx 12wtO2 + CO2 +H2O + HNO3

deposition vaporizationby sputtering

H2O + HNO3

by sputtering

irreversible process above a N2 threshold () ltlt 1000ppm N2

sticky deposit

p 2 ( ) pp 2 any CH4 concentration (60ppm)

Plasma Chemistry with CH4 ImpuritiesPlasma Chemistry with CH4 Impurities4

bull Formation of NO and NO2 depends on O3 N2 and gas temperature Conclusion N2 admixture is the key factor

SummarySummaryyyThe mechanisms of formed NOx by-products follows the sameThe mechanisms of formed NOx by-products follows the sameprinciples as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentration

principles as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentrationozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)

ozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)g p ( g p )

The conversion of methane to OH and H2O is found to depend on

g p ( g p )

The conversion of methane to OH and H2O is found to depend ondissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)

dissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)discharge gap)discharge gap)

How do you optimize an ozone generatorg

Scientific ApproachScientific ApproachTheoretical Experimental

pppp

c [wt]

f [Hz]

c [wt]

f [Hz]

[kW]UUUβ1

1Cf4αPn

1iiminpeakimin

iiD

q [kWm2]q [kWm2]

150

180

][V]voltagepeakUpeak

[]cylinder perslicesofamountnsliceii

whereth

09 00

30

60

90

120

effic

ienc

y [

][0tdj t bl[F]sliceisdielectricofecapacitancC

[Hz]frequencyf[V]sliceivoltageminimumiUmin

thiD

th

10

28

46

64

82

39

107

176

244 power density

[kWm2]

ozone conc [wt][]CCβ

][0parameteradjustableα

iDiGi

Impact of Power Inductionp

350

400

wer

200

250

300

App

lied

Pow

Arr C 2Arr D +0

Arr E +45Arr F +7

Arr G +3

5 0

100

150

Frac

tion

of

1 2 3 4

ReferenceArr B unstable

Arr C -2

00

50

4Position (1inlet 4outlet)

Experimental Test Rigp g

Experimental Test Rigp g

Outer grounded electrode (left picture) and the dielectric covered inner electrodes (right) d e ect c cove ed e e ect odes ( g t)

Reference (Traditional) Arrangement

Inlet OutletGas flow direction

Optimized Arrangement

Inlet OutletGas flow direction

Intelligent Gap System (IGS)g p y ( )

Molecular Oxygen (O2) Ozone (O3)

O2 O3

yg ( 2) ( 3)

Particle Size SynthesisParticle Size SynthesisByBy--Products Cluster FormationProducts Cluster Formationyy

high diffusion and deposition to surfaces

low diffusion rate good transport

high sedimentation on the structurehigh sedimentation on the structure

Degreacutemont Technologies ndash OzoniaIntelligent Gap SystemIntelligent Gap System

G Vezzuacute JL Lopez A Freilich and K Becker Optimizationof Large-Scale Ozone Generators IEEE Transactions onPlasma Science Vol 37 No 6 p 890-896 (2009)

ConclusionsConclusionsConclusionsConclusionsFundamentals of ozone synthesis in a DBD plasmay p

ndash Highly filamented DBD discharges are best-suitedfor the production of ozone concentrations in therange of 6 to 14 wtrange of 6 to 14 wt

ndash The preferred characteristic of the microdischargesare Townsend-like at reduced electric fields Enaround 190 Townsend

ndash Detrimental side-effects induced by by-productscan be avoided by a proper design of the electrodecan be avoided by a proper design of the electrodearrangement The phenomenon is related to thediffusion rates of formed by-product clusters

ConclusionsConclusionsConclusionsConclusionsBenefits from DBD microplasma tailoring

ndash Reduced power consumption of up to 10 improvement

ndash Increased ozone concentrations of up to 14 now achievable

ndash Improved neutralization and conditioning of detrimental by-products

ndash Reduced system capital and operational cost

New technologies to improve ozone p

generatorg

HV Pulsed Power SwitchingHV Pulsed Power Switching

Microchannel Generation of Ozone

Channel ArrayChannel Array

Microchannel

330 microm 230 microm

Some Cap-DBD Devices Operating in Air

Increase of 60 of

Spacing 225 μmof 60 of plasma

No space

Cap‐DBD ozone generation

bull Ozone concentration is evaluated via Eco S d l UV 100 O A l (0 01Sensors model UV-100 Ozone Analyzer (001 ndash 900 ppm wiht an accuracy of plusmn2)

bull Three reactors 6 tubings 6rdquo with spacings of 0 μm 225 μm and 500 μm running at 3 kV μ μ μ g

SpacingOzone Concentration

3 kV rms 4 kV rms3 kV rms 4 kV rms

0 μm 660 ppm

225 μm 550 ppm

For a device of such small scale these ozone levels are promising

500 μm 380 ppm

J Mahoney W Zhu VS Johnson KH Becker and JL Lopez Electrical and optical emissionmeasurements of a capillary dielectric barrier discharge European Physics Journal D Vol 60 441-447(2010)

QuestionsQuestions

Thank YouFor more informationProf Jose L Lopez PhD

Thank YouFor more informationDepartment of Physics

Telephone (973) 761-9057Email joselopez1shuedu

Website wwwshueduacademicsartsciphysicsWebsite wwwshueduacademicsartsciphysics

Page 66: Dielectric Barrier Discharge (DBD) & Progress in Large ...bonitz/si12/talks/august_8/lopez_si12.pdf · Dielectric Barrier Discharge (DBD) & Progress in Large-Scale Ozone Generation

Experimental Setup

Front view of the two units after the redesign and reworking ofthe gas water and instruments connectionsthe gas water and instruments connections

Experimental Setup

Top view of the twoexperimental unitsexperimental unitsSpectroscope (notshown) is to the left ofthe DBD The units weredifferent with respect todifferent with respect totheir electrodes onehad only the electrodecoated with thedielectric (ldquosingle-dielectric ( single-coatedrdquo) the other onehad the electrode andthe anode coated withthe dielectric (ldquodouble-the dielectric ( double-coatedrdquo)

Basics Generation of OzoneBasics Generation of Ozone

SpectroscopyPlasma

Plasma Absorption SpectroscopyPlasma Absorption Spectroscopy

Infrared Absorption SpectroscopyInfrared Absorption Spectroscopy

IR spectra in pure oxygen (black curve) and at approximately 10wt N2 admixture (red line) N2O5 peaks appear at124 1 d 1 2 11245 cm-1 and at 1725 cm-1

Infrared Absorption SpectroscopyInfrared Absorption Spectroscopy

IR spectra of several methane variations The green curve envelopes all of the methane peaks at 1325 cm-1recorded at smaller methane admixtures Simultaneously the N2O5 peaks disappear as the methane peaks appear

N2O5 FormationN2O5 Formation2 52 5p=2 bara cwt=20degC q=35kWm2 f=1450Hz

45N2O5 AT95

30

35

40

N

2 B

lend

ing

N2O AT95N2O5 IGSN2O IGSN2O5 LGN2O LG

1 5

20

25

nt [p

pmV]

3

wt

05

10

15

NO

x co

nten

005 7 9 11 13 15 17

ozone conc [wt]

Amount of formed N2O5 and N2O as a function of ozone concentration at 3 wt of nitrogen admixture and fori l dvarious electrode arrangements

Plasma Emission SpectroscopyPlasma Emission Spectroscopyp pyp py

Relative Emissions of the Ozonizer plasmaRelative Emissions of the Ozonizer plasma

Region 300- 850 nm from individual (calibrated) regions (smoothed by PeakFit) Single-coated ozone generator Inlet side

3 5E+06

30E+06

35E+06

7 9

20E+06

25E+06

nten

sity

au

2

311 12

10E+06

15E+06

In 4

5

6 8 10

14

15

16

17

00E+00

50E+05

280 300 320 340 360 380 400 420 440 460 480 500 520 540 560 580 600 620 640 660 680 700 720 740 760 780 800 820 840 860

Wavelength nm

1 13

Wavelength nm

Absolute Emission of the DBD PlasmaAbsolute Emission of the DBD Plasma

Intensities in (O2+3 wtN2) plasma

1 20E+04

100E+04

120E+04

600E+03

800E+03

nten

sity

(au

)

200E+03

400E+03

In

O(777)

000E+00200 250 300 350 400 450 500 550 600 650 700 750 800 850

Wavelength nm

Intensities in 3 wtN2+O2 plasmaIntensities in 3 wtN2+O2 plasma

Plasma Chemistry in OzonizersPlasma Chemistry in Ozonizers

Dry Air O2 N2

e - e -

O N2 N O2

O3 NO

O2 N O2

O3

N

3

NO2

O2 O3

NO

N

NO2 O3

N2O

NO3 N

N2O4

NO2

NO2

N2O5

NO3

Primary electron-driven chemical reactions leading to the formation of N2O5 and N2O in a dry air plasma

Plasma emission diagnostics role of N2Plasma emission diagnostics role of N2

Dry Air O2 N2

e - e -

O N2 N O2

O3 NO

O2 N O2

O3

O

N

ON

NO2

O2O3

N

NO N

NO2 O3

N2O

NO3 N

N2O4

NO2

NO2

N2O5

NO3

ONbullWith N2 present ndash less oxygen atoms are formed However the difference in intensity is

very small

Modeling of plasma chemistry incl the NxOy chemistry up to N2O5 for different Oxygen Nitrogen mixtures varying power deposition scenarios

and initial ozone background concentrations (up to 15) previously done

The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation

The role of N2 must be related to its by-products reacting on the surface of the electrodeThe role of N2 must be related to its by-products reacting on the surface of the electrode

The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established

Ab 8 t f O

The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established

Ab 8 t f OAbove 8 wt of O3

1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)

Above 8 wt of O3

1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)case without pampp)

2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of the

case without pampp)

2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of thethem A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface

them A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface

The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation

Three possibilities have to be considered for the oxygen-fedozone generator

Three possibilities have to be considered for the oxygen-fedozone generatorozone generator

bull Excited N2 molecules lead to an increased O2 dissociation in

ozone generator

bull Excited N2 molecules lead to an increased O2 dissociation in2 2such case an increased efficiency is correlated to the N2admixture

2 2such case an increased efficiency is correlated to the N2admixture

bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial

bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial

bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2

bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2g p g 3 pp y 2g p g 3 pp y 2

Effect of methane on ozone efficiency and specific powerEffect of methane on ozone efficiency and specific power

Effect of Methane on Ozone Content in Outlet Gas and on Specific Power Pure O2

13 12

10

11

12

t 8

10

8

9

10

ne c

onte

nt w

t

6

8

ecifi

c po

wer

kW

hlb

5

6

7

Ozo

n

2

4 Spe

400E+00 20E+03 40E+03 60E+03 80E+03 10E+04 12E+04

Methane in feedgas ppm

0

Ozone content in the outlet gas Specif ic pow er of the ozone generatorg p p g

Effects of N2 and CH4Effects of N2 and CH4

Pi t f h t lli N O t tPicture of an amorphous-crystalline N2O5 structurecaptured at the Orlando Skylake water plant in 2006

Plasma Chemistry with CH4 Impurities

OxygenO2 N2

e - e -

CHO N2

NO2

O NO

O2 N O2 O3

NOH

CH4e-

O3 NO

NO2

O2O3NO N

NO2 O

NO2

NO2

N2ONO3

N

O3

NO2

NO

HNO3

N2O4

N2O5

NO2

NO3

N2O5

Effect of methane on the electrode surfaces

a) b)

Inlet Outlet Outlet

) d)

I l t I l t

c) d)

Electrode of the ozone generator afterseveral hours in CH8O2 and up to 2 wt of methane (a b c)

Inlet Inlet

three hours in CH8O2+traces of N2 and up to 1 wt of methane (d) Visible change of discharge character at about 13 length of electrode (a d)

Kinetics of CHx Conversion without N2

conversion by collisions

O2 + CHx 12wt O3 + CO2 +H2O

deposition vaporizationby sputtering

ibl b l 1000 CHreversible process below 1000ppm CH4

Effect of water on electrode surface with N2

Inlet

OutletOutlet

Electrode of the ozone generator after several hours in H OO N

Inlet

Electrode of the ozone generator after several hours in H2OO2N2

Effect of water on electrode surface

Long term effect (800 hrs) of H2OO2N2

Kinetics of CHx Conversion with N2

conversion by collisionsHNO3 formation

O2 + N2 +CHx 12wtO2 + CO2 +H2O + HNO3

deposition vaporizationby sputtering

H2O + HNO3

by sputtering

irreversible process above a N2 threshold () ltlt 1000ppm N2

sticky deposit

p 2 ( ) pp 2 any CH4 concentration (60ppm)

Plasma Chemistry with CH4 ImpuritiesPlasma Chemistry with CH4 Impurities4

bull Formation of NO and NO2 depends on O3 N2 and gas temperature Conclusion N2 admixture is the key factor

SummarySummaryyyThe mechanisms of formed NOx by-products follows the sameThe mechanisms of formed NOx by-products follows the sameprinciples as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentration

principles as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentrationozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)

ozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)g p ( g p )

The conversion of methane to OH and H2O is found to depend on

g p ( g p )

The conversion of methane to OH and H2O is found to depend ondissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)

dissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)discharge gap)discharge gap)

How do you optimize an ozone generatorg

Scientific ApproachScientific ApproachTheoretical Experimental

pppp

c [wt]

f [Hz]

c [wt]

f [Hz]

[kW]UUUβ1

1Cf4αPn

1iiminpeakimin

iiD

q [kWm2]q [kWm2]

150

180

][V]voltagepeakUpeak

[]cylinder perslicesofamountnsliceii

whereth

09 00

30

60

90

120

effic

ienc

y [

][0tdj t bl[F]sliceisdielectricofecapacitancC

[Hz]frequencyf[V]sliceivoltageminimumiUmin

thiD

th

10

28

46

64

82

39

107

176

244 power density

[kWm2]

ozone conc [wt][]CCβ

][0parameteradjustableα

iDiGi

Impact of Power Inductionp

350

400

wer

200

250

300

App

lied

Pow

Arr C 2Arr D +0

Arr E +45Arr F +7

Arr G +3

5 0

100

150

Frac

tion

of

1 2 3 4

ReferenceArr B unstable

Arr C -2

00

50

4Position (1inlet 4outlet)

Experimental Test Rigp g

Experimental Test Rigp g

Outer grounded electrode (left picture) and the dielectric covered inner electrodes (right) d e ect c cove ed e e ect odes ( g t)

Reference (Traditional) Arrangement

Inlet OutletGas flow direction

Optimized Arrangement

Inlet OutletGas flow direction

Intelligent Gap System (IGS)g p y ( )

Molecular Oxygen (O2) Ozone (O3)

O2 O3

yg ( 2) ( 3)

Particle Size SynthesisParticle Size SynthesisByBy--Products Cluster FormationProducts Cluster Formationyy

high diffusion and deposition to surfaces

low diffusion rate good transport

high sedimentation on the structurehigh sedimentation on the structure

Degreacutemont Technologies ndash OzoniaIntelligent Gap SystemIntelligent Gap System

G Vezzuacute JL Lopez A Freilich and K Becker Optimizationof Large-Scale Ozone Generators IEEE Transactions onPlasma Science Vol 37 No 6 p 890-896 (2009)

ConclusionsConclusionsConclusionsConclusionsFundamentals of ozone synthesis in a DBD plasmay p

ndash Highly filamented DBD discharges are best-suitedfor the production of ozone concentrations in therange of 6 to 14 wtrange of 6 to 14 wt

ndash The preferred characteristic of the microdischargesare Townsend-like at reduced electric fields Enaround 190 Townsend

ndash Detrimental side-effects induced by by-productscan be avoided by a proper design of the electrodecan be avoided by a proper design of the electrodearrangement The phenomenon is related to thediffusion rates of formed by-product clusters

ConclusionsConclusionsConclusionsConclusionsBenefits from DBD microplasma tailoring

ndash Reduced power consumption of up to 10 improvement

ndash Increased ozone concentrations of up to 14 now achievable

ndash Improved neutralization and conditioning of detrimental by-products

ndash Reduced system capital and operational cost

New technologies to improve ozone p

generatorg

HV Pulsed Power SwitchingHV Pulsed Power Switching

Microchannel Generation of Ozone

Channel ArrayChannel Array

Microchannel

330 microm 230 microm

Some Cap-DBD Devices Operating in Air

Increase of 60 of

Spacing 225 μmof 60 of plasma

No space

Cap‐DBD ozone generation

bull Ozone concentration is evaluated via Eco S d l UV 100 O A l (0 01Sensors model UV-100 Ozone Analyzer (001 ndash 900 ppm wiht an accuracy of plusmn2)

bull Three reactors 6 tubings 6rdquo with spacings of 0 μm 225 μm and 500 μm running at 3 kV μ μ μ g

SpacingOzone Concentration

3 kV rms 4 kV rms3 kV rms 4 kV rms

0 μm 660 ppm

225 μm 550 ppm

For a device of such small scale these ozone levels are promising

500 μm 380 ppm

J Mahoney W Zhu VS Johnson KH Becker and JL Lopez Electrical and optical emissionmeasurements of a capillary dielectric barrier discharge European Physics Journal D Vol 60 441-447(2010)

QuestionsQuestions

Thank YouFor more informationProf Jose L Lopez PhD

Thank YouFor more informationDepartment of Physics

Telephone (973) 761-9057Email joselopez1shuedu

Website wwwshueduacademicsartsciphysicsWebsite wwwshueduacademicsartsciphysics

Page 67: Dielectric Barrier Discharge (DBD) & Progress in Large ...bonitz/si12/talks/august_8/lopez_si12.pdf · Dielectric Barrier Discharge (DBD) & Progress in Large-Scale Ozone Generation

Experimental Setup

Top view of the twoexperimental unitsexperimental unitsSpectroscope (notshown) is to the left ofthe DBD The units weredifferent with respect todifferent with respect totheir electrodes onehad only the electrodecoated with thedielectric (ldquosingle-dielectric ( single-coatedrdquo) the other onehad the electrode andthe anode coated withthe dielectric (ldquodouble-the dielectric ( double-coatedrdquo)

Basics Generation of OzoneBasics Generation of Ozone

SpectroscopyPlasma

Plasma Absorption SpectroscopyPlasma Absorption Spectroscopy

Infrared Absorption SpectroscopyInfrared Absorption Spectroscopy

IR spectra in pure oxygen (black curve) and at approximately 10wt N2 admixture (red line) N2O5 peaks appear at124 1 d 1 2 11245 cm-1 and at 1725 cm-1

Infrared Absorption SpectroscopyInfrared Absorption Spectroscopy

IR spectra of several methane variations The green curve envelopes all of the methane peaks at 1325 cm-1recorded at smaller methane admixtures Simultaneously the N2O5 peaks disappear as the methane peaks appear

N2O5 FormationN2O5 Formation2 52 5p=2 bara cwt=20degC q=35kWm2 f=1450Hz

45N2O5 AT95

30

35

40

N

2 B

lend

ing

N2O AT95N2O5 IGSN2O IGSN2O5 LGN2O LG

1 5

20

25

nt [p

pmV]

3

wt

05

10

15

NO

x co

nten

005 7 9 11 13 15 17

ozone conc [wt]

Amount of formed N2O5 and N2O as a function of ozone concentration at 3 wt of nitrogen admixture and fori l dvarious electrode arrangements

Plasma Emission SpectroscopyPlasma Emission Spectroscopyp pyp py

Relative Emissions of the Ozonizer plasmaRelative Emissions of the Ozonizer plasma

Region 300- 850 nm from individual (calibrated) regions (smoothed by PeakFit) Single-coated ozone generator Inlet side

3 5E+06

30E+06

35E+06

7 9

20E+06

25E+06

nten

sity

au

2

311 12

10E+06

15E+06

In 4

5

6 8 10

14

15

16

17

00E+00

50E+05

280 300 320 340 360 380 400 420 440 460 480 500 520 540 560 580 600 620 640 660 680 700 720 740 760 780 800 820 840 860

Wavelength nm

1 13

Wavelength nm

Absolute Emission of the DBD PlasmaAbsolute Emission of the DBD Plasma

Intensities in (O2+3 wtN2) plasma

1 20E+04

100E+04

120E+04

600E+03

800E+03

nten

sity

(au

)

200E+03

400E+03

In

O(777)

000E+00200 250 300 350 400 450 500 550 600 650 700 750 800 850

Wavelength nm

Intensities in 3 wtN2+O2 plasmaIntensities in 3 wtN2+O2 plasma

Plasma Chemistry in OzonizersPlasma Chemistry in Ozonizers

Dry Air O2 N2

e - e -

O N2 N O2

O3 NO

O2 N O2

O3

N

3

NO2

O2 O3

NO

N

NO2 O3

N2O

NO3 N

N2O4

NO2

NO2

N2O5

NO3

Primary electron-driven chemical reactions leading to the formation of N2O5 and N2O in a dry air plasma

Plasma emission diagnostics role of N2Plasma emission diagnostics role of N2

Dry Air O2 N2

e - e -

O N2 N O2

O3 NO

O2 N O2

O3

O

N

ON

NO2

O2O3

N

NO N

NO2 O3

N2O

NO3 N

N2O4

NO2

NO2

N2O5

NO3

ONbullWith N2 present ndash less oxygen atoms are formed However the difference in intensity is

very small

Modeling of plasma chemistry incl the NxOy chemistry up to N2O5 for different Oxygen Nitrogen mixtures varying power deposition scenarios

and initial ozone background concentrations (up to 15) previously done

The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation

The role of N2 must be related to its by-products reacting on the surface of the electrodeThe role of N2 must be related to its by-products reacting on the surface of the electrode

The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established

Ab 8 t f O

The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established

Ab 8 t f OAbove 8 wt of O3

1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)

Above 8 wt of O3

1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)case without pampp)

2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of the

case without pampp)

2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of thethem A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface

them A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface

The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation

Three possibilities have to be considered for the oxygen-fedozone generator

Three possibilities have to be considered for the oxygen-fedozone generatorozone generator

bull Excited N2 molecules lead to an increased O2 dissociation in

ozone generator

bull Excited N2 molecules lead to an increased O2 dissociation in2 2such case an increased efficiency is correlated to the N2admixture

2 2such case an increased efficiency is correlated to the N2admixture

bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial

bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial

bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2

bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2g p g 3 pp y 2g p g 3 pp y 2

Effect of methane on ozone efficiency and specific powerEffect of methane on ozone efficiency and specific power

Effect of Methane on Ozone Content in Outlet Gas and on Specific Power Pure O2

13 12

10

11

12

t 8

10

8

9

10

ne c

onte

nt w

t

6

8

ecifi

c po

wer

kW

hlb

5

6

7

Ozo

n

2

4 Spe

400E+00 20E+03 40E+03 60E+03 80E+03 10E+04 12E+04

Methane in feedgas ppm

0

Ozone content in the outlet gas Specif ic pow er of the ozone generatorg p p g

Effects of N2 and CH4Effects of N2 and CH4

Pi t f h t lli N O t tPicture of an amorphous-crystalline N2O5 structurecaptured at the Orlando Skylake water plant in 2006

Plasma Chemistry with CH4 Impurities

OxygenO2 N2

e - e -

CHO N2

NO2

O NO

O2 N O2 O3

NOH

CH4e-

O3 NO

NO2

O2O3NO N

NO2 O

NO2

NO2

N2ONO3

N

O3

NO2

NO

HNO3

N2O4

N2O5

NO2

NO3

N2O5

Effect of methane on the electrode surfaces

a) b)

Inlet Outlet Outlet

) d)

I l t I l t

c) d)

Electrode of the ozone generator afterseveral hours in CH8O2 and up to 2 wt of methane (a b c)

Inlet Inlet

three hours in CH8O2+traces of N2 and up to 1 wt of methane (d) Visible change of discharge character at about 13 length of electrode (a d)

Kinetics of CHx Conversion without N2

conversion by collisions

O2 + CHx 12wt O3 + CO2 +H2O

deposition vaporizationby sputtering

ibl b l 1000 CHreversible process below 1000ppm CH4

Effect of water on electrode surface with N2

Inlet

OutletOutlet

Electrode of the ozone generator after several hours in H OO N

Inlet

Electrode of the ozone generator after several hours in H2OO2N2

Effect of water on electrode surface

Long term effect (800 hrs) of H2OO2N2

Kinetics of CHx Conversion with N2

conversion by collisionsHNO3 formation

O2 + N2 +CHx 12wtO2 + CO2 +H2O + HNO3

deposition vaporizationby sputtering

H2O + HNO3

by sputtering

irreversible process above a N2 threshold () ltlt 1000ppm N2

sticky deposit

p 2 ( ) pp 2 any CH4 concentration (60ppm)

Plasma Chemistry with CH4 ImpuritiesPlasma Chemistry with CH4 Impurities4

bull Formation of NO and NO2 depends on O3 N2 and gas temperature Conclusion N2 admixture is the key factor

SummarySummaryyyThe mechanisms of formed NOx by-products follows the sameThe mechanisms of formed NOx by-products follows the sameprinciples as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentration

principles as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentrationozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)

ozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)g p ( g p )

The conversion of methane to OH and H2O is found to depend on

g p ( g p )

The conversion of methane to OH and H2O is found to depend ondissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)

dissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)discharge gap)discharge gap)

How do you optimize an ozone generatorg

Scientific ApproachScientific ApproachTheoretical Experimental

pppp

c [wt]

f [Hz]

c [wt]

f [Hz]

[kW]UUUβ1

1Cf4αPn

1iiminpeakimin

iiD

q [kWm2]q [kWm2]

150

180

][V]voltagepeakUpeak

[]cylinder perslicesofamountnsliceii

whereth

09 00

30

60

90

120

effic

ienc

y [

][0tdj t bl[F]sliceisdielectricofecapacitancC

[Hz]frequencyf[V]sliceivoltageminimumiUmin

thiD

th

10

28

46

64

82

39

107

176

244 power density

[kWm2]

ozone conc [wt][]CCβ

][0parameteradjustableα

iDiGi

Impact of Power Inductionp

350

400

wer

200

250

300

App

lied

Pow

Arr C 2Arr D +0

Arr E +45Arr F +7

Arr G +3

5 0

100

150

Frac

tion

of

1 2 3 4

ReferenceArr B unstable

Arr C -2

00

50

4Position (1inlet 4outlet)

Experimental Test Rigp g

Experimental Test Rigp g

Outer grounded electrode (left picture) and the dielectric covered inner electrodes (right) d e ect c cove ed e e ect odes ( g t)

Reference (Traditional) Arrangement

Inlet OutletGas flow direction

Optimized Arrangement

Inlet OutletGas flow direction

Intelligent Gap System (IGS)g p y ( )

Molecular Oxygen (O2) Ozone (O3)

O2 O3

yg ( 2) ( 3)

Particle Size SynthesisParticle Size SynthesisByBy--Products Cluster FormationProducts Cluster Formationyy

high diffusion and deposition to surfaces

low diffusion rate good transport

high sedimentation on the structurehigh sedimentation on the structure

Degreacutemont Technologies ndash OzoniaIntelligent Gap SystemIntelligent Gap System

G Vezzuacute JL Lopez A Freilich and K Becker Optimizationof Large-Scale Ozone Generators IEEE Transactions onPlasma Science Vol 37 No 6 p 890-896 (2009)

ConclusionsConclusionsConclusionsConclusionsFundamentals of ozone synthesis in a DBD plasmay p

ndash Highly filamented DBD discharges are best-suitedfor the production of ozone concentrations in therange of 6 to 14 wtrange of 6 to 14 wt

ndash The preferred characteristic of the microdischargesare Townsend-like at reduced electric fields Enaround 190 Townsend

ndash Detrimental side-effects induced by by-productscan be avoided by a proper design of the electrodecan be avoided by a proper design of the electrodearrangement The phenomenon is related to thediffusion rates of formed by-product clusters

ConclusionsConclusionsConclusionsConclusionsBenefits from DBD microplasma tailoring

ndash Reduced power consumption of up to 10 improvement

ndash Increased ozone concentrations of up to 14 now achievable

ndash Improved neutralization and conditioning of detrimental by-products

ndash Reduced system capital and operational cost

New technologies to improve ozone p

generatorg

HV Pulsed Power SwitchingHV Pulsed Power Switching

Microchannel Generation of Ozone

Channel ArrayChannel Array

Microchannel

330 microm 230 microm

Some Cap-DBD Devices Operating in Air

Increase of 60 of

Spacing 225 μmof 60 of plasma

No space

Cap‐DBD ozone generation

bull Ozone concentration is evaluated via Eco S d l UV 100 O A l (0 01Sensors model UV-100 Ozone Analyzer (001 ndash 900 ppm wiht an accuracy of plusmn2)

bull Three reactors 6 tubings 6rdquo with spacings of 0 μm 225 μm and 500 μm running at 3 kV μ μ μ g

SpacingOzone Concentration

3 kV rms 4 kV rms3 kV rms 4 kV rms

0 μm 660 ppm

225 μm 550 ppm

For a device of such small scale these ozone levels are promising

500 μm 380 ppm

J Mahoney W Zhu VS Johnson KH Becker and JL Lopez Electrical and optical emissionmeasurements of a capillary dielectric barrier discharge European Physics Journal D Vol 60 441-447(2010)

QuestionsQuestions

Thank YouFor more informationProf Jose L Lopez PhD

Thank YouFor more informationDepartment of Physics

Telephone (973) 761-9057Email joselopez1shuedu

Website wwwshueduacademicsartsciphysicsWebsite wwwshueduacademicsartsciphysics

Page 68: Dielectric Barrier Discharge (DBD) & Progress in Large ...bonitz/si12/talks/august_8/lopez_si12.pdf · Dielectric Barrier Discharge (DBD) & Progress in Large-Scale Ozone Generation

Basics Generation of OzoneBasics Generation of Ozone

SpectroscopyPlasma

Plasma Absorption SpectroscopyPlasma Absorption Spectroscopy

Infrared Absorption SpectroscopyInfrared Absorption Spectroscopy

IR spectra in pure oxygen (black curve) and at approximately 10wt N2 admixture (red line) N2O5 peaks appear at124 1 d 1 2 11245 cm-1 and at 1725 cm-1

Infrared Absorption SpectroscopyInfrared Absorption Spectroscopy

IR spectra of several methane variations The green curve envelopes all of the methane peaks at 1325 cm-1recorded at smaller methane admixtures Simultaneously the N2O5 peaks disappear as the methane peaks appear

N2O5 FormationN2O5 Formation2 52 5p=2 bara cwt=20degC q=35kWm2 f=1450Hz

45N2O5 AT95

30

35

40

N

2 B

lend

ing

N2O AT95N2O5 IGSN2O IGSN2O5 LGN2O LG

1 5

20

25

nt [p

pmV]

3

wt

05

10

15

NO

x co

nten

005 7 9 11 13 15 17

ozone conc [wt]

Amount of formed N2O5 and N2O as a function of ozone concentration at 3 wt of nitrogen admixture and fori l dvarious electrode arrangements

Plasma Emission SpectroscopyPlasma Emission Spectroscopyp pyp py

Relative Emissions of the Ozonizer plasmaRelative Emissions of the Ozonizer plasma

Region 300- 850 nm from individual (calibrated) regions (smoothed by PeakFit) Single-coated ozone generator Inlet side

3 5E+06

30E+06

35E+06

7 9

20E+06

25E+06

nten

sity

au

2

311 12

10E+06

15E+06

In 4

5

6 8 10

14

15

16

17

00E+00

50E+05

280 300 320 340 360 380 400 420 440 460 480 500 520 540 560 580 600 620 640 660 680 700 720 740 760 780 800 820 840 860

Wavelength nm

1 13

Wavelength nm

Absolute Emission of the DBD PlasmaAbsolute Emission of the DBD Plasma

Intensities in (O2+3 wtN2) plasma

1 20E+04

100E+04

120E+04

600E+03

800E+03

nten

sity

(au

)

200E+03

400E+03

In

O(777)

000E+00200 250 300 350 400 450 500 550 600 650 700 750 800 850

Wavelength nm

Intensities in 3 wtN2+O2 plasmaIntensities in 3 wtN2+O2 plasma

Plasma Chemistry in OzonizersPlasma Chemistry in Ozonizers

Dry Air O2 N2

e - e -

O N2 N O2

O3 NO

O2 N O2

O3

N

3

NO2

O2 O3

NO

N

NO2 O3

N2O

NO3 N

N2O4

NO2

NO2

N2O5

NO3

Primary electron-driven chemical reactions leading to the formation of N2O5 and N2O in a dry air plasma

Plasma emission diagnostics role of N2Plasma emission diagnostics role of N2

Dry Air O2 N2

e - e -

O N2 N O2

O3 NO

O2 N O2

O3

O

N

ON

NO2

O2O3

N

NO N

NO2 O3

N2O

NO3 N

N2O4

NO2

NO2

N2O5

NO3

ONbullWith N2 present ndash less oxygen atoms are formed However the difference in intensity is

very small

Modeling of plasma chemistry incl the NxOy chemistry up to N2O5 for different Oxygen Nitrogen mixtures varying power deposition scenarios

and initial ozone background concentrations (up to 15) previously done

The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation

The role of N2 must be related to its by-products reacting on the surface of the electrodeThe role of N2 must be related to its by-products reacting on the surface of the electrode

The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established

Ab 8 t f O

The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established

Ab 8 t f OAbove 8 wt of O3

1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)

Above 8 wt of O3

1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)case without pampp)

2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of the

case without pampp)

2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of thethem A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface

them A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface

The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation

Three possibilities have to be considered for the oxygen-fedozone generator

Three possibilities have to be considered for the oxygen-fedozone generatorozone generator

bull Excited N2 molecules lead to an increased O2 dissociation in

ozone generator

bull Excited N2 molecules lead to an increased O2 dissociation in2 2such case an increased efficiency is correlated to the N2admixture

2 2such case an increased efficiency is correlated to the N2admixture

bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial

bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial

bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2

bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2g p g 3 pp y 2g p g 3 pp y 2

Effect of methane on ozone efficiency and specific powerEffect of methane on ozone efficiency and specific power

Effect of Methane on Ozone Content in Outlet Gas and on Specific Power Pure O2

13 12

10

11

12

t 8

10

8

9

10

ne c

onte

nt w

t

6

8

ecifi

c po

wer

kW

hlb

5

6

7

Ozo

n

2

4 Spe

400E+00 20E+03 40E+03 60E+03 80E+03 10E+04 12E+04

Methane in feedgas ppm

0

Ozone content in the outlet gas Specif ic pow er of the ozone generatorg p p g

Effects of N2 and CH4Effects of N2 and CH4

Pi t f h t lli N O t tPicture of an amorphous-crystalline N2O5 structurecaptured at the Orlando Skylake water plant in 2006

Plasma Chemistry with CH4 Impurities

OxygenO2 N2

e - e -

CHO N2

NO2

O NO

O2 N O2 O3

NOH

CH4e-

O3 NO

NO2

O2O3NO N

NO2 O

NO2

NO2

N2ONO3

N

O3

NO2

NO

HNO3

N2O4

N2O5

NO2

NO3

N2O5

Effect of methane on the electrode surfaces

a) b)

Inlet Outlet Outlet

) d)

I l t I l t

c) d)

Electrode of the ozone generator afterseveral hours in CH8O2 and up to 2 wt of methane (a b c)

Inlet Inlet

three hours in CH8O2+traces of N2 and up to 1 wt of methane (d) Visible change of discharge character at about 13 length of electrode (a d)

Kinetics of CHx Conversion without N2

conversion by collisions

O2 + CHx 12wt O3 + CO2 +H2O

deposition vaporizationby sputtering

ibl b l 1000 CHreversible process below 1000ppm CH4

Effect of water on electrode surface with N2

Inlet

OutletOutlet

Electrode of the ozone generator after several hours in H OO N

Inlet

Electrode of the ozone generator after several hours in H2OO2N2

Effect of water on electrode surface

Long term effect (800 hrs) of H2OO2N2

Kinetics of CHx Conversion with N2

conversion by collisionsHNO3 formation

O2 + N2 +CHx 12wtO2 + CO2 +H2O + HNO3

deposition vaporizationby sputtering

H2O + HNO3

by sputtering

irreversible process above a N2 threshold () ltlt 1000ppm N2

sticky deposit

p 2 ( ) pp 2 any CH4 concentration (60ppm)

Plasma Chemistry with CH4 ImpuritiesPlasma Chemistry with CH4 Impurities4

bull Formation of NO and NO2 depends on O3 N2 and gas temperature Conclusion N2 admixture is the key factor

SummarySummaryyyThe mechanisms of formed NOx by-products follows the sameThe mechanisms of formed NOx by-products follows the sameprinciples as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentration

principles as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentrationozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)

ozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)g p ( g p )

The conversion of methane to OH and H2O is found to depend on

g p ( g p )

The conversion of methane to OH and H2O is found to depend ondissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)

dissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)discharge gap)discharge gap)

How do you optimize an ozone generatorg

Scientific ApproachScientific ApproachTheoretical Experimental

pppp

c [wt]

f [Hz]

c [wt]

f [Hz]

[kW]UUUβ1

1Cf4αPn

1iiminpeakimin

iiD

q [kWm2]q [kWm2]

150

180

][V]voltagepeakUpeak

[]cylinder perslicesofamountnsliceii

whereth

09 00

30

60

90

120

effic

ienc

y [

][0tdj t bl[F]sliceisdielectricofecapacitancC

[Hz]frequencyf[V]sliceivoltageminimumiUmin

thiD

th

10

28

46

64

82

39

107

176

244 power density

[kWm2]

ozone conc [wt][]CCβ

][0parameteradjustableα

iDiGi

Impact of Power Inductionp

350

400

wer

200

250

300

App

lied

Pow

Arr C 2Arr D +0

Arr E +45Arr F +7

Arr G +3

5 0

100

150

Frac

tion

of

1 2 3 4

ReferenceArr B unstable

Arr C -2

00

50

4Position (1inlet 4outlet)

Experimental Test Rigp g

Experimental Test Rigp g

Outer grounded electrode (left picture) and the dielectric covered inner electrodes (right) d e ect c cove ed e e ect odes ( g t)

Reference (Traditional) Arrangement

Inlet OutletGas flow direction

Optimized Arrangement

Inlet OutletGas flow direction

Intelligent Gap System (IGS)g p y ( )

Molecular Oxygen (O2) Ozone (O3)

O2 O3

yg ( 2) ( 3)

Particle Size SynthesisParticle Size SynthesisByBy--Products Cluster FormationProducts Cluster Formationyy

high diffusion and deposition to surfaces

low diffusion rate good transport

high sedimentation on the structurehigh sedimentation on the structure

Degreacutemont Technologies ndash OzoniaIntelligent Gap SystemIntelligent Gap System

G Vezzuacute JL Lopez A Freilich and K Becker Optimizationof Large-Scale Ozone Generators IEEE Transactions onPlasma Science Vol 37 No 6 p 890-896 (2009)

ConclusionsConclusionsConclusionsConclusionsFundamentals of ozone synthesis in a DBD plasmay p

ndash Highly filamented DBD discharges are best-suitedfor the production of ozone concentrations in therange of 6 to 14 wtrange of 6 to 14 wt

ndash The preferred characteristic of the microdischargesare Townsend-like at reduced electric fields Enaround 190 Townsend

ndash Detrimental side-effects induced by by-productscan be avoided by a proper design of the electrodecan be avoided by a proper design of the electrodearrangement The phenomenon is related to thediffusion rates of formed by-product clusters

ConclusionsConclusionsConclusionsConclusionsBenefits from DBD microplasma tailoring

ndash Reduced power consumption of up to 10 improvement

ndash Increased ozone concentrations of up to 14 now achievable

ndash Improved neutralization and conditioning of detrimental by-products

ndash Reduced system capital and operational cost

New technologies to improve ozone p

generatorg

HV Pulsed Power SwitchingHV Pulsed Power Switching

Microchannel Generation of Ozone

Channel ArrayChannel Array

Microchannel

330 microm 230 microm

Some Cap-DBD Devices Operating in Air

Increase of 60 of

Spacing 225 μmof 60 of plasma

No space

Cap‐DBD ozone generation

bull Ozone concentration is evaluated via Eco S d l UV 100 O A l (0 01Sensors model UV-100 Ozone Analyzer (001 ndash 900 ppm wiht an accuracy of plusmn2)

bull Three reactors 6 tubings 6rdquo with spacings of 0 μm 225 μm and 500 μm running at 3 kV μ μ μ g

SpacingOzone Concentration

3 kV rms 4 kV rms3 kV rms 4 kV rms

0 μm 660 ppm

225 μm 550 ppm

For a device of such small scale these ozone levels are promising

500 μm 380 ppm

J Mahoney W Zhu VS Johnson KH Becker and JL Lopez Electrical and optical emissionmeasurements of a capillary dielectric barrier discharge European Physics Journal D Vol 60 441-447(2010)

QuestionsQuestions

Thank YouFor more informationProf Jose L Lopez PhD

Thank YouFor more informationDepartment of Physics

Telephone (973) 761-9057Email joselopez1shuedu

Website wwwshueduacademicsartsciphysicsWebsite wwwshueduacademicsartsciphysics

Page 69: Dielectric Barrier Discharge (DBD) & Progress in Large ...bonitz/si12/talks/august_8/lopez_si12.pdf · Dielectric Barrier Discharge (DBD) & Progress in Large-Scale Ozone Generation

SpectroscopyPlasma

Plasma Absorption SpectroscopyPlasma Absorption Spectroscopy

Infrared Absorption SpectroscopyInfrared Absorption Spectroscopy

IR spectra in pure oxygen (black curve) and at approximately 10wt N2 admixture (red line) N2O5 peaks appear at124 1 d 1 2 11245 cm-1 and at 1725 cm-1

Infrared Absorption SpectroscopyInfrared Absorption Spectroscopy

IR spectra of several methane variations The green curve envelopes all of the methane peaks at 1325 cm-1recorded at smaller methane admixtures Simultaneously the N2O5 peaks disappear as the methane peaks appear

N2O5 FormationN2O5 Formation2 52 5p=2 bara cwt=20degC q=35kWm2 f=1450Hz

45N2O5 AT95

30

35

40

N

2 B

lend

ing

N2O AT95N2O5 IGSN2O IGSN2O5 LGN2O LG

1 5

20

25

nt [p

pmV]

3

wt

05

10

15

NO

x co

nten

005 7 9 11 13 15 17

ozone conc [wt]

Amount of formed N2O5 and N2O as a function of ozone concentration at 3 wt of nitrogen admixture and fori l dvarious electrode arrangements

Plasma Emission SpectroscopyPlasma Emission Spectroscopyp pyp py

Relative Emissions of the Ozonizer plasmaRelative Emissions of the Ozonizer plasma

Region 300- 850 nm from individual (calibrated) regions (smoothed by PeakFit) Single-coated ozone generator Inlet side

3 5E+06

30E+06

35E+06

7 9

20E+06

25E+06

nten

sity

au

2

311 12

10E+06

15E+06

In 4

5

6 8 10

14

15

16

17

00E+00

50E+05

280 300 320 340 360 380 400 420 440 460 480 500 520 540 560 580 600 620 640 660 680 700 720 740 760 780 800 820 840 860

Wavelength nm

1 13

Wavelength nm

Absolute Emission of the DBD PlasmaAbsolute Emission of the DBD Plasma

Intensities in (O2+3 wtN2) plasma

1 20E+04

100E+04

120E+04

600E+03

800E+03

nten

sity

(au

)

200E+03

400E+03

In

O(777)

000E+00200 250 300 350 400 450 500 550 600 650 700 750 800 850

Wavelength nm

Intensities in 3 wtN2+O2 plasmaIntensities in 3 wtN2+O2 plasma

Plasma Chemistry in OzonizersPlasma Chemistry in Ozonizers

Dry Air O2 N2

e - e -

O N2 N O2

O3 NO

O2 N O2

O3

N

3

NO2

O2 O3

NO

N

NO2 O3

N2O

NO3 N

N2O4

NO2

NO2

N2O5

NO3

Primary electron-driven chemical reactions leading to the formation of N2O5 and N2O in a dry air plasma

Plasma emission diagnostics role of N2Plasma emission diagnostics role of N2

Dry Air O2 N2

e - e -

O N2 N O2

O3 NO

O2 N O2

O3

O

N

ON

NO2

O2O3

N

NO N

NO2 O3

N2O

NO3 N

N2O4

NO2

NO2

N2O5

NO3

ONbullWith N2 present ndash less oxygen atoms are formed However the difference in intensity is

very small

Modeling of plasma chemistry incl the NxOy chemistry up to N2O5 for different Oxygen Nitrogen mixtures varying power deposition scenarios

and initial ozone background concentrations (up to 15) previously done

The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation

The role of N2 must be related to its by-products reacting on the surface of the electrodeThe role of N2 must be related to its by-products reacting on the surface of the electrode

The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established

Ab 8 t f O

The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established

Ab 8 t f OAbove 8 wt of O3

1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)

Above 8 wt of O3

1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)case without pampp)

2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of the

case without pampp)

2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of thethem A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface

them A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface

The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation

Three possibilities have to be considered for the oxygen-fedozone generator

Three possibilities have to be considered for the oxygen-fedozone generatorozone generator

bull Excited N2 molecules lead to an increased O2 dissociation in

ozone generator

bull Excited N2 molecules lead to an increased O2 dissociation in2 2such case an increased efficiency is correlated to the N2admixture

2 2such case an increased efficiency is correlated to the N2admixture

bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial

bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial

bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2

bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2g p g 3 pp y 2g p g 3 pp y 2

Effect of methane on ozone efficiency and specific powerEffect of methane on ozone efficiency and specific power

Effect of Methane on Ozone Content in Outlet Gas and on Specific Power Pure O2

13 12

10

11

12

t 8

10

8

9

10

ne c

onte

nt w

t

6

8

ecifi

c po

wer

kW

hlb

5

6

7

Ozo

n

2

4 Spe

400E+00 20E+03 40E+03 60E+03 80E+03 10E+04 12E+04

Methane in feedgas ppm

0

Ozone content in the outlet gas Specif ic pow er of the ozone generatorg p p g

Effects of N2 and CH4Effects of N2 and CH4

Pi t f h t lli N O t tPicture of an amorphous-crystalline N2O5 structurecaptured at the Orlando Skylake water plant in 2006

Plasma Chemistry with CH4 Impurities

OxygenO2 N2

e - e -

CHO N2

NO2

O NO

O2 N O2 O3

NOH

CH4e-

O3 NO

NO2

O2O3NO N

NO2 O

NO2

NO2

N2ONO3

N

O3

NO2

NO

HNO3

N2O4

N2O5

NO2

NO3

N2O5

Effect of methane on the electrode surfaces

a) b)

Inlet Outlet Outlet

) d)

I l t I l t

c) d)

Electrode of the ozone generator afterseveral hours in CH8O2 and up to 2 wt of methane (a b c)

Inlet Inlet

three hours in CH8O2+traces of N2 and up to 1 wt of methane (d) Visible change of discharge character at about 13 length of electrode (a d)

Kinetics of CHx Conversion without N2

conversion by collisions

O2 + CHx 12wt O3 + CO2 +H2O

deposition vaporizationby sputtering

ibl b l 1000 CHreversible process below 1000ppm CH4

Effect of water on electrode surface with N2

Inlet

OutletOutlet

Electrode of the ozone generator after several hours in H OO N

Inlet

Electrode of the ozone generator after several hours in H2OO2N2

Effect of water on electrode surface

Long term effect (800 hrs) of H2OO2N2

Kinetics of CHx Conversion with N2

conversion by collisionsHNO3 formation

O2 + N2 +CHx 12wtO2 + CO2 +H2O + HNO3

deposition vaporizationby sputtering

H2O + HNO3

by sputtering

irreversible process above a N2 threshold () ltlt 1000ppm N2

sticky deposit

p 2 ( ) pp 2 any CH4 concentration (60ppm)

Plasma Chemistry with CH4 ImpuritiesPlasma Chemistry with CH4 Impurities4

bull Formation of NO and NO2 depends on O3 N2 and gas temperature Conclusion N2 admixture is the key factor

SummarySummaryyyThe mechanisms of formed NOx by-products follows the sameThe mechanisms of formed NOx by-products follows the sameprinciples as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentration

principles as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentrationozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)

ozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)g p ( g p )

The conversion of methane to OH and H2O is found to depend on

g p ( g p )

The conversion of methane to OH and H2O is found to depend ondissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)

dissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)discharge gap)discharge gap)

How do you optimize an ozone generatorg

Scientific ApproachScientific ApproachTheoretical Experimental

pppp

c [wt]

f [Hz]

c [wt]

f [Hz]

[kW]UUUβ1

1Cf4αPn

1iiminpeakimin

iiD

q [kWm2]q [kWm2]

150

180

][V]voltagepeakUpeak

[]cylinder perslicesofamountnsliceii

whereth

09 00

30

60

90

120

effic

ienc

y [

][0tdj t bl[F]sliceisdielectricofecapacitancC

[Hz]frequencyf[V]sliceivoltageminimumiUmin

thiD

th

10

28

46

64

82

39

107

176

244 power density

[kWm2]

ozone conc [wt][]CCβ

][0parameteradjustableα

iDiGi

Impact of Power Inductionp

350

400

wer

200

250

300

App

lied

Pow

Arr C 2Arr D +0

Arr E +45Arr F +7

Arr G +3

5 0

100

150

Frac

tion

of

1 2 3 4

ReferenceArr B unstable

Arr C -2

00

50

4Position (1inlet 4outlet)

Experimental Test Rigp g

Experimental Test Rigp g

Outer grounded electrode (left picture) and the dielectric covered inner electrodes (right) d e ect c cove ed e e ect odes ( g t)

Reference (Traditional) Arrangement

Inlet OutletGas flow direction

Optimized Arrangement

Inlet OutletGas flow direction

Intelligent Gap System (IGS)g p y ( )

Molecular Oxygen (O2) Ozone (O3)

O2 O3

yg ( 2) ( 3)

Particle Size SynthesisParticle Size SynthesisByBy--Products Cluster FormationProducts Cluster Formationyy

high diffusion and deposition to surfaces

low diffusion rate good transport

high sedimentation on the structurehigh sedimentation on the structure

Degreacutemont Technologies ndash OzoniaIntelligent Gap SystemIntelligent Gap System

G Vezzuacute JL Lopez A Freilich and K Becker Optimizationof Large-Scale Ozone Generators IEEE Transactions onPlasma Science Vol 37 No 6 p 890-896 (2009)

ConclusionsConclusionsConclusionsConclusionsFundamentals of ozone synthesis in a DBD plasmay p

ndash Highly filamented DBD discharges are best-suitedfor the production of ozone concentrations in therange of 6 to 14 wtrange of 6 to 14 wt

ndash The preferred characteristic of the microdischargesare Townsend-like at reduced electric fields Enaround 190 Townsend

ndash Detrimental side-effects induced by by-productscan be avoided by a proper design of the electrodecan be avoided by a proper design of the electrodearrangement The phenomenon is related to thediffusion rates of formed by-product clusters

ConclusionsConclusionsConclusionsConclusionsBenefits from DBD microplasma tailoring

ndash Reduced power consumption of up to 10 improvement

ndash Increased ozone concentrations of up to 14 now achievable

ndash Improved neutralization and conditioning of detrimental by-products

ndash Reduced system capital and operational cost

New technologies to improve ozone p

generatorg

HV Pulsed Power SwitchingHV Pulsed Power Switching

Microchannel Generation of Ozone

Channel ArrayChannel Array

Microchannel

330 microm 230 microm

Some Cap-DBD Devices Operating in Air

Increase of 60 of

Spacing 225 μmof 60 of plasma

No space

Cap‐DBD ozone generation

bull Ozone concentration is evaluated via Eco S d l UV 100 O A l (0 01Sensors model UV-100 Ozone Analyzer (001 ndash 900 ppm wiht an accuracy of plusmn2)

bull Three reactors 6 tubings 6rdquo with spacings of 0 μm 225 μm and 500 μm running at 3 kV μ μ μ g

SpacingOzone Concentration

3 kV rms 4 kV rms3 kV rms 4 kV rms

0 μm 660 ppm

225 μm 550 ppm

For a device of such small scale these ozone levels are promising

500 μm 380 ppm

J Mahoney W Zhu VS Johnson KH Becker and JL Lopez Electrical and optical emissionmeasurements of a capillary dielectric barrier discharge European Physics Journal D Vol 60 441-447(2010)

QuestionsQuestions

Thank YouFor more informationProf Jose L Lopez PhD

Thank YouFor more informationDepartment of Physics

Telephone (973) 761-9057Email joselopez1shuedu

Website wwwshueduacademicsartsciphysicsWebsite wwwshueduacademicsartsciphysics

Page 70: Dielectric Barrier Discharge (DBD) & Progress in Large ...bonitz/si12/talks/august_8/lopez_si12.pdf · Dielectric Barrier Discharge (DBD) & Progress in Large-Scale Ozone Generation

Plasma Absorption SpectroscopyPlasma Absorption Spectroscopy

Infrared Absorption SpectroscopyInfrared Absorption Spectroscopy

IR spectra in pure oxygen (black curve) and at approximately 10wt N2 admixture (red line) N2O5 peaks appear at124 1 d 1 2 11245 cm-1 and at 1725 cm-1

Infrared Absorption SpectroscopyInfrared Absorption Spectroscopy

IR spectra of several methane variations The green curve envelopes all of the methane peaks at 1325 cm-1recorded at smaller methane admixtures Simultaneously the N2O5 peaks disappear as the methane peaks appear

N2O5 FormationN2O5 Formation2 52 5p=2 bara cwt=20degC q=35kWm2 f=1450Hz

45N2O5 AT95

30

35

40

N

2 B

lend

ing

N2O AT95N2O5 IGSN2O IGSN2O5 LGN2O LG

1 5

20

25

nt [p

pmV]

3

wt

05

10

15

NO

x co

nten

005 7 9 11 13 15 17

ozone conc [wt]

Amount of formed N2O5 and N2O as a function of ozone concentration at 3 wt of nitrogen admixture and fori l dvarious electrode arrangements

Plasma Emission SpectroscopyPlasma Emission Spectroscopyp pyp py

Relative Emissions of the Ozonizer plasmaRelative Emissions of the Ozonizer plasma

Region 300- 850 nm from individual (calibrated) regions (smoothed by PeakFit) Single-coated ozone generator Inlet side

3 5E+06

30E+06

35E+06

7 9

20E+06

25E+06

nten

sity

au

2

311 12

10E+06

15E+06

In 4

5

6 8 10

14

15

16

17

00E+00

50E+05

280 300 320 340 360 380 400 420 440 460 480 500 520 540 560 580 600 620 640 660 680 700 720 740 760 780 800 820 840 860

Wavelength nm

1 13

Wavelength nm

Absolute Emission of the DBD PlasmaAbsolute Emission of the DBD Plasma

Intensities in (O2+3 wtN2) plasma

1 20E+04

100E+04

120E+04

600E+03

800E+03

nten

sity

(au

)

200E+03

400E+03

In

O(777)

000E+00200 250 300 350 400 450 500 550 600 650 700 750 800 850

Wavelength nm

Intensities in 3 wtN2+O2 plasmaIntensities in 3 wtN2+O2 plasma

Plasma Chemistry in OzonizersPlasma Chemistry in Ozonizers

Dry Air O2 N2

e - e -

O N2 N O2

O3 NO

O2 N O2

O3

N

3

NO2

O2 O3

NO

N

NO2 O3

N2O

NO3 N

N2O4

NO2

NO2

N2O5

NO3

Primary electron-driven chemical reactions leading to the formation of N2O5 and N2O in a dry air plasma

Plasma emission diagnostics role of N2Plasma emission diagnostics role of N2

Dry Air O2 N2

e - e -

O N2 N O2

O3 NO

O2 N O2

O3

O

N

ON

NO2

O2O3

N

NO N

NO2 O3

N2O

NO3 N

N2O4

NO2

NO2

N2O5

NO3

ONbullWith N2 present ndash less oxygen atoms are formed However the difference in intensity is

very small

Modeling of plasma chemistry incl the NxOy chemistry up to N2O5 for different Oxygen Nitrogen mixtures varying power deposition scenarios

and initial ozone background concentrations (up to 15) previously done

The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation

The role of N2 must be related to its by-products reacting on the surface of the electrodeThe role of N2 must be related to its by-products reacting on the surface of the electrode

The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established

Ab 8 t f O

The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established

Ab 8 t f OAbove 8 wt of O3

1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)

Above 8 wt of O3

1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)case without pampp)

2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of the

case without pampp)

2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of thethem A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface

them A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface

The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation

Three possibilities have to be considered for the oxygen-fedozone generator

Three possibilities have to be considered for the oxygen-fedozone generatorozone generator

bull Excited N2 molecules lead to an increased O2 dissociation in

ozone generator

bull Excited N2 molecules lead to an increased O2 dissociation in2 2such case an increased efficiency is correlated to the N2admixture

2 2such case an increased efficiency is correlated to the N2admixture

bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial

bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial

bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2

bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2g p g 3 pp y 2g p g 3 pp y 2

Effect of methane on ozone efficiency and specific powerEffect of methane on ozone efficiency and specific power

Effect of Methane on Ozone Content in Outlet Gas and on Specific Power Pure O2

13 12

10

11

12

t 8

10

8

9

10

ne c

onte

nt w

t

6

8

ecifi

c po

wer

kW

hlb

5

6

7

Ozo

n

2

4 Spe

400E+00 20E+03 40E+03 60E+03 80E+03 10E+04 12E+04

Methane in feedgas ppm

0

Ozone content in the outlet gas Specif ic pow er of the ozone generatorg p p g

Effects of N2 and CH4Effects of N2 and CH4

Pi t f h t lli N O t tPicture of an amorphous-crystalline N2O5 structurecaptured at the Orlando Skylake water plant in 2006

Plasma Chemistry with CH4 Impurities

OxygenO2 N2

e - e -

CHO N2

NO2

O NO

O2 N O2 O3

NOH

CH4e-

O3 NO

NO2

O2O3NO N

NO2 O

NO2

NO2

N2ONO3

N

O3

NO2

NO

HNO3

N2O4

N2O5

NO2

NO3

N2O5

Effect of methane on the electrode surfaces

a) b)

Inlet Outlet Outlet

) d)

I l t I l t

c) d)

Electrode of the ozone generator afterseveral hours in CH8O2 and up to 2 wt of methane (a b c)

Inlet Inlet

three hours in CH8O2+traces of N2 and up to 1 wt of methane (d) Visible change of discharge character at about 13 length of electrode (a d)

Kinetics of CHx Conversion without N2

conversion by collisions

O2 + CHx 12wt O3 + CO2 +H2O

deposition vaporizationby sputtering

ibl b l 1000 CHreversible process below 1000ppm CH4

Effect of water on electrode surface with N2

Inlet

OutletOutlet

Electrode of the ozone generator after several hours in H OO N

Inlet

Electrode of the ozone generator after several hours in H2OO2N2

Effect of water on electrode surface

Long term effect (800 hrs) of H2OO2N2

Kinetics of CHx Conversion with N2

conversion by collisionsHNO3 formation

O2 + N2 +CHx 12wtO2 + CO2 +H2O + HNO3

deposition vaporizationby sputtering

H2O + HNO3

by sputtering

irreversible process above a N2 threshold () ltlt 1000ppm N2

sticky deposit

p 2 ( ) pp 2 any CH4 concentration (60ppm)

Plasma Chemistry with CH4 ImpuritiesPlasma Chemistry with CH4 Impurities4

bull Formation of NO and NO2 depends on O3 N2 and gas temperature Conclusion N2 admixture is the key factor

SummarySummaryyyThe mechanisms of formed NOx by-products follows the sameThe mechanisms of formed NOx by-products follows the sameprinciples as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentration

principles as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentrationozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)

ozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)g p ( g p )

The conversion of methane to OH and H2O is found to depend on

g p ( g p )

The conversion of methane to OH and H2O is found to depend ondissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)

dissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)discharge gap)discharge gap)

How do you optimize an ozone generatorg

Scientific ApproachScientific ApproachTheoretical Experimental

pppp

c [wt]

f [Hz]

c [wt]

f [Hz]

[kW]UUUβ1

1Cf4αPn

1iiminpeakimin

iiD

q [kWm2]q [kWm2]

150

180

][V]voltagepeakUpeak

[]cylinder perslicesofamountnsliceii

whereth

09 00

30

60

90

120

effic

ienc

y [

][0tdj t bl[F]sliceisdielectricofecapacitancC

[Hz]frequencyf[V]sliceivoltageminimumiUmin

thiD

th

10

28

46

64

82

39

107

176

244 power density

[kWm2]

ozone conc [wt][]CCβ

][0parameteradjustableα

iDiGi

Impact of Power Inductionp

350

400

wer

200

250

300

App

lied

Pow

Arr C 2Arr D +0

Arr E +45Arr F +7

Arr G +3

5 0

100

150

Frac

tion

of

1 2 3 4

ReferenceArr B unstable

Arr C -2

00

50

4Position (1inlet 4outlet)

Experimental Test Rigp g

Experimental Test Rigp g

Outer grounded electrode (left picture) and the dielectric covered inner electrodes (right) d e ect c cove ed e e ect odes ( g t)

Reference (Traditional) Arrangement

Inlet OutletGas flow direction

Optimized Arrangement

Inlet OutletGas flow direction

Intelligent Gap System (IGS)g p y ( )

Molecular Oxygen (O2) Ozone (O3)

O2 O3

yg ( 2) ( 3)

Particle Size SynthesisParticle Size SynthesisByBy--Products Cluster FormationProducts Cluster Formationyy

high diffusion and deposition to surfaces

low diffusion rate good transport

high sedimentation on the structurehigh sedimentation on the structure

Degreacutemont Technologies ndash OzoniaIntelligent Gap SystemIntelligent Gap System

G Vezzuacute JL Lopez A Freilich and K Becker Optimizationof Large-Scale Ozone Generators IEEE Transactions onPlasma Science Vol 37 No 6 p 890-896 (2009)

ConclusionsConclusionsConclusionsConclusionsFundamentals of ozone synthesis in a DBD plasmay p

ndash Highly filamented DBD discharges are best-suitedfor the production of ozone concentrations in therange of 6 to 14 wtrange of 6 to 14 wt

ndash The preferred characteristic of the microdischargesare Townsend-like at reduced electric fields Enaround 190 Townsend

ndash Detrimental side-effects induced by by-productscan be avoided by a proper design of the electrodecan be avoided by a proper design of the electrodearrangement The phenomenon is related to thediffusion rates of formed by-product clusters

ConclusionsConclusionsConclusionsConclusionsBenefits from DBD microplasma tailoring

ndash Reduced power consumption of up to 10 improvement

ndash Increased ozone concentrations of up to 14 now achievable

ndash Improved neutralization and conditioning of detrimental by-products

ndash Reduced system capital and operational cost

New technologies to improve ozone p

generatorg

HV Pulsed Power SwitchingHV Pulsed Power Switching

Microchannel Generation of Ozone

Channel ArrayChannel Array

Microchannel

330 microm 230 microm

Some Cap-DBD Devices Operating in Air

Increase of 60 of

Spacing 225 μmof 60 of plasma

No space

Cap‐DBD ozone generation

bull Ozone concentration is evaluated via Eco S d l UV 100 O A l (0 01Sensors model UV-100 Ozone Analyzer (001 ndash 900 ppm wiht an accuracy of plusmn2)

bull Three reactors 6 tubings 6rdquo with spacings of 0 μm 225 μm and 500 μm running at 3 kV μ μ μ g

SpacingOzone Concentration

3 kV rms 4 kV rms3 kV rms 4 kV rms

0 μm 660 ppm

225 μm 550 ppm

For a device of such small scale these ozone levels are promising

500 μm 380 ppm

J Mahoney W Zhu VS Johnson KH Becker and JL Lopez Electrical and optical emissionmeasurements of a capillary dielectric barrier discharge European Physics Journal D Vol 60 441-447(2010)

QuestionsQuestions

Thank YouFor more informationProf Jose L Lopez PhD

Thank YouFor more informationDepartment of Physics

Telephone (973) 761-9057Email joselopez1shuedu

Website wwwshueduacademicsartsciphysicsWebsite wwwshueduacademicsartsciphysics

Page 71: Dielectric Barrier Discharge (DBD) & Progress in Large ...bonitz/si12/talks/august_8/lopez_si12.pdf · Dielectric Barrier Discharge (DBD) & Progress in Large-Scale Ozone Generation

Infrared Absorption SpectroscopyInfrared Absorption Spectroscopy

IR spectra in pure oxygen (black curve) and at approximately 10wt N2 admixture (red line) N2O5 peaks appear at124 1 d 1 2 11245 cm-1 and at 1725 cm-1

Infrared Absorption SpectroscopyInfrared Absorption Spectroscopy

IR spectra of several methane variations The green curve envelopes all of the methane peaks at 1325 cm-1recorded at smaller methane admixtures Simultaneously the N2O5 peaks disappear as the methane peaks appear

N2O5 FormationN2O5 Formation2 52 5p=2 bara cwt=20degC q=35kWm2 f=1450Hz

45N2O5 AT95

30

35

40

N

2 B

lend

ing

N2O AT95N2O5 IGSN2O IGSN2O5 LGN2O LG

1 5

20

25

nt [p

pmV]

3

wt

05

10

15

NO

x co

nten

005 7 9 11 13 15 17

ozone conc [wt]

Amount of formed N2O5 and N2O as a function of ozone concentration at 3 wt of nitrogen admixture and fori l dvarious electrode arrangements

Plasma Emission SpectroscopyPlasma Emission Spectroscopyp pyp py

Relative Emissions of the Ozonizer plasmaRelative Emissions of the Ozonizer plasma

Region 300- 850 nm from individual (calibrated) regions (smoothed by PeakFit) Single-coated ozone generator Inlet side

3 5E+06

30E+06

35E+06

7 9

20E+06

25E+06

nten

sity

au

2

311 12

10E+06

15E+06

In 4

5

6 8 10

14

15

16

17

00E+00

50E+05

280 300 320 340 360 380 400 420 440 460 480 500 520 540 560 580 600 620 640 660 680 700 720 740 760 780 800 820 840 860

Wavelength nm

1 13

Wavelength nm

Absolute Emission of the DBD PlasmaAbsolute Emission of the DBD Plasma

Intensities in (O2+3 wtN2) plasma

1 20E+04

100E+04

120E+04

600E+03

800E+03

nten

sity

(au

)

200E+03

400E+03

In

O(777)

000E+00200 250 300 350 400 450 500 550 600 650 700 750 800 850

Wavelength nm

Intensities in 3 wtN2+O2 plasmaIntensities in 3 wtN2+O2 plasma

Plasma Chemistry in OzonizersPlasma Chemistry in Ozonizers

Dry Air O2 N2

e - e -

O N2 N O2

O3 NO

O2 N O2

O3

N

3

NO2

O2 O3

NO

N

NO2 O3

N2O

NO3 N

N2O4

NO2

NO2

N2O5

NO3

Primary electron-driven chemical reactions leading to the formation of N2O5 and N2O in a dry air plasma

Plasma emission diagnostics role of N2Plasma emission diagnostics role of N2

Dry Air O2 N2

e - e -

O N2 N O2

O3 NO

O2 N O2

O3

O

N

ON

NO2

O2O3

N

NO N

NO2 O3

N2O

NO3 N

N2O4

NO2

NO2

N2O5

NO3

ONbullWith N2 present ndash less oxygen atoms are formed However the difference in intensity is

very small

Modeling of plasma chemistry incl the NxOy chemistry up to N2O5 for different Oxygen Nitrogen mixtures varying power deposition scenarios

and initial ozone background concentrations (up to 15) previously done

The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation

The role of N2 must be related to its by-products reacting on the surface of the electrodeThe role of N2 must be related to its by-products reacting on the surface of the electrode

The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established

Ab 8 t f O

The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established

Ab 8 t f OAbove 8 wt of O3

1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)

Above 8 wt of O3

1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)case without pampp)

2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of the

case without pampp)

2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of thethem A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface

them A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface

The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation

Three possibilities have to be considered for the oxygen-fedozone generator

Three possibilities have to be considered for the oxygen-fedozone generatorozone generator

bull Excited N2 molecules lead to an increased O2 dissociation in

ozone generator

bull Excited N2 molecules lead to an increased O2 dissociation in2 2such case an increased efficiency is correlated to the N2admixture

2 2such case an increased efficiency is correlated to the N2admixture

bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial

bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial

bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2

bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2g p g 3 pp y 2g p g 3 pp y 2

Effect of methane on ozone efficiency and specific powerEffect of methane on ozone efficiency and specific power

Effect of Methane on Ozone Content in Outlet Gas and on Specific Power Pure O2

13 12

10

11

12

t 8

10

8

9

10

ne c

onte

nt w

t

6

8

ecifi

c po

wer

kW

hlb

5

6

7

Ozo

n

2

4 Spe

400E+00 20E+03 40E+03 60E+03 80E+03 10E+04 12E+04

Methane in feedgas ppm

0

Ozone content in the outlet gas Specif ic pow er of the ozone generatorg p p g

Effects of N2 and CH4Effects of N2 and CH4

Pi t f h t lli N O t tPicture of an amorphous-crystalline N2O5 structurecaptured at the Orlando Skylake water plant in 2006

Plasma Chemistry with CH4 Impurities

OxygenO2 N2

e - e -

CHO N2

NO2

O NO

O2 N O2 O3

NOH

CH4e-

O3 NO

NO2

O2O3NO N

NO2 O

NO2

NO2

N2ONO3

N

O3

NO2

NO

HNO3

N2O4

N2O5

NO2

NO3

N2O5

Effect of methane on the electrode surfaces

a) b)

Inlet Outlet Outlet

) d)

I l t I l t

c) d)

Electrode of the ozone generator afterseveral hours in CH8O2 and up to 2 wt of methane (a b c)

Inlet Inlet

three hours in CH8O2+traces of N2 and up to 1 wt of methane (d) Visible change of discharge character at about 13 length of electrode (a d)

Kinetics of CHx Conversion without N2

conversion by collisions

O2 + CHx 12wt O3 + CO2 +H2O

deposition vaporizationby sputtering

ibl b l 1000 CHreversible process below 1000ppm CH4

Effect of water on electrode surface with N2

Inlet

OutletOutlet

Electrode of the ozone generator after several hours in H OO N

Inlet

Electrode of the ozone generator after several hours in H2OO2N2

Effect of water on electrode surface

Long term effect (800 hrs) of H2OO2N2

Kinetics of CHx Conversion with N2

conversion by collisionsHNO3 formation

O2 + N2 +CHx 12wtO2 + CO2 +H2O + HNO3

deposition vaporizationby sputtering

H2O + HNO3

by sputtering

irreversible process above a N2 threshold () ltlt 1000ppm N2

sticky deposit

p 2 ( ) pp 2 any CH4 concentration (60ppm)

Plasma Chemistry with CH4 ImpuritiesPlasma Chemistry with CH4 Impurities4

bull Formation of NO and NO2 depends on O3 N2 and gas temperature Conclusion N2 admixture is the key factor

SummarySummaryyyThe mechanisms of formed NOx by-products follows the sameThe mechanisms of formed NOx by-products follows the sameprinciples as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentration

principles as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentrationozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)

ozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)g p ( g p )

The conversion of methane to OH and H2O is found to depend on

g p ( g p )

The conversion of methane to OH and H2O is found to depend ondissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)

dissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)discharge gap)discharge gap)

How do you optimize an ozone generatorg

Scientific ApproachScientific ApproachTheoretical Experimental

pppp

c [wt]

f [Hz]

c [wt]

f [Hz]

[kW]UUUβ1

1Cf4αPn

1iiminpeakimin

iiD

q [kWm2]q [kWm2]

150

180

][V]voltagepeakUpeak

[]cylinder perslicesofamountnsliceii

whereth

09 00

30

60

90

120

effic

ienc

y [

][0tdj t bl[F]sliceisdielectricofecapacitancC

[Hz]frequencyf[V]sliceivoltageminimumiUmin

thiD

th

10

28

46

64

82

39

107

176

244 power density

[kWm2]

ozone conc [wt][]CCβ

][0parameteradjustableα

iDiGi

Impact of Power Inductionp

350

400

wer

200

250

300

App

lied

Pow

Arr C 2Arr D +0

Arr E +45Arr F +7

Arr G +3

5 0

100

150

Frac

tion

of

1 2 3 4

ReferenceArr B unstable

Arr C -2

00

50

4Position (1inlet 4outlet)

Experimental Test Rigp g

Experimental Test Rigp g

Outer grounded electrode (left picture) and the dielectric covered inner electrodes (right) d e ect c cove ed e e ect odes ( g t)

Reference (Traditional) Arrangement

Inlet OutletGas flow direction

Optimized Arrangement

Inlet OutletGas flow direction

Intelligent Gap System (IGS)g p y ( )

Molecular Oxygen (O2) Ozone (O3)

O2 O3

yg ( 2) ( 3)

Particle Size SynthesisParticle Size SynthesisByBy--Products Cluster FormationProducts Cluster Formationyy

high diffusion and deposition to surfaces

low diffusion rate good transport

high sedimentation on the structurehigh sedimentation on the structure

Degreacutemont Technologies ndash OzoniaIntelligent Gap SystemIntelligent Gap System

G Vezzuacute JL Lopez A Freilich and K Becker Optimizationof Large-Scale Ozone Generators IEEE Transactions onPlasma Science Vol 37 No 6 p 890-896 (2009)

ConclusionsConclusionsConclusionsConclusionsFundamentals of ozone synthesis in a DBD plasmay p

ndash Highly filamented DBD discharges are best-suitedfor the production of ozone concentrations in therange of 6 to 14 wtrange of 6 to 14 wt

ndash The preferred characteristic of the microdischargesare Townsend-like at reduced electric fields Enaround 190 Townsend

ndash Detrimental side-effects induced by by-productscan be avoided by a proper design of the electrodecan be avoided by a proper design of the electrodearrangement The phenomenon is related to thediffusion rates of formed by-product clusters

ConclusionsConclusionsConclusionsConclusionsBenefits from DBD microplasma tailoring

ndash Reduced power consumption of up to 10 improvement

ndash Increased ozone concentrations of up to 14 now achievable

ndash Improved neutralization and conditioning of detrimental by-products

ndash Reduced system capital and operational cost

New technologies to improve ozone p

generatorg

HV Pulsed Power SwitchingHV Pulsed Power Switching

Microchannel Generation of Ozone

Channel ArrayChannel Array

Microchannel

330 microm 230 microm

Some Cap-DBD Devices Operating in Air

Increase of 60 of

Spacing 225 μmof 60 of plasma

No space

Cap‐DBD ozone generation

bull Ozone concentration is evaluated via Eco S d l UV 100 O A l (0 01Sensors model UV-100 Ozone Analyzer (001 ndash 900 ppm wiht an accuracy of plusmn2)

bull Three reactors 6 tubings 6rdquo with spacings of 0 μm 225 μm and 500 μm running at 3 kV μ μ μ g

SpacingOzone Concentration

3 kV rms 4 kV rms3 kV rms 4 kV rms

0 μm 660 ppm

225 μm 550 ppm

For a device of such small scale these ozone levels are promising

500 μm 380 ppm

J Mahoney W Zhu VS Johnson KH Becker and JL Lopez Electrical and optical emissionmeasurements of a capillary dielectric barrier discharge European Physics Journal D Vol 60 441-447(2010)

QuestionsQuestions

Thank YouFor more informationProf Jose L Lopez PhD

Thank YouFor more informationDepartment of Physics

Telephone (973) 761-9057Email joselopez1shuedu

Website wwwshueduacademicsartsciphysicsWebsite wwwshueduacademicsartsciphysics

Page 72: Dielectric Barrier Discharge (DBD) & Progress in Large ...bonitz/si12/talks/august_8/lopez_si12.pdf · Dielectric Barrier Discharge (DBD) & Progress in Large-Scale Ozone Generation

Infrared Absorption SpectroscopyInfrared Absorption Spectroscopy

IR spectra of several methane variations The green curve envelopes all of the methane peaks at 1325 cm-1recorded at smaller methane admixtures Simultaneously the N2O5 peaks disappear as the methane peaks appear

N2O5 FormationN2O5 Formation2 52 5p=2 bara cwt=20degC q=35kWm2 f=1450Hz

45N2O5 AT95

30

35

40

N

2 B

lend

ing

N2O AT95N2O5 IGSN2O IGSN2O5 LGN2O LG

1 5

20

25

nt [p

pmV]

3

wt

05

10

15

NO

x co

nten

005 7 9 11 13 15 17

ozone conc [wt]

Amount of formed N2O5 and N2O as a function of ozone concentration at 3 wt of nitrogen admixture and fori l dvarious electrode arrangements

Plasma Emission SpectroscopyPlasma Emission Spectroscopyp pyp py

Relative Emissions of the Ozonizer plasmaRelative Emissions of the Ozonizer plasma

Region 300- 850 nm from individual (calibrated) regions (smoothed by PeakFit) Single-coated ozone generator Inlet side

3 5E+06

30E+06

35E+06

7 9

20E+06

25E+06

nten

sity

au

2

311 12

10E+06

15E+06

In 4

5

6 8 10

14

15

16

17

00E+00

50E+05

280 300 320 340 360 380 400 420 440 460 480 500 520 540 560 580 600 620 640 660 680 700 720 740 760 780 800 820 840 860

Wavelength nm

1 13

Wavelength nm

Absolute Emission of the DBD PlasmaAbsolute Emission of the DBD Plasma

Intensities in (O2+3 wtN2) plasma

1 20E+04

100E+04

120E+04

600E+03

800E+03

nten

sity

(au

)

200E+03

400E+03

In

O(777)

000E+00200 250 300 350 400 450 500 550 600 650 700 750 800 850

Wavelength nm

Intensities in 3 wtN2+O2 plasmaIntensities in 3 wtN2+O2 plasma

Plasma Chemistry in OzonizersPlasma Chemistry in Ozonizers

Dry Air O2 N2

e - e -

O N2 N O2

O3 NO

O2 N O2

O3

N

3

NO2

O2 O3

NO

N

NO2 O3

N2O

NO3 N

N2O4

NO2

NO2

N2O5

NO3

Primary electron-driven chemical reactions leading to the formation of N2O5 and N2O in a dry air plasma

Plasma emission diagnostics role of N2Plasma emission diagnostics role of N2

Dry Air O2 N2

e - e -

O N2 N O2

O3 NO

O2 N O2

O3

O

N

ON

NO2

O2O3

N

NO N

NO2 O3

N2O

NO3 N

N2O4

NO2

NO2

N2O5

NO3

ONbullWith N2 present ndash less oxygen atoms are formed However the difference in intensity is

very small

Modeling of plasma chemistry incl the NxOy chemistry up to N2O5 for different Oxygen Nitrogen mixtures varying power deposition scenarios

and initial ozone background concentrations (up to 15) previously done

The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation

The role of N2 must be related to its by-products reacting on the surface of the electrodeThe role of N2 must be related to its by-products reacting on the surface of the electrode

The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established

Ab 8 t f O

The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established

Ab 8 t f OAbove 8 wt of O3

1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)

Above 8 wt of O3

1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)case without pampp)

2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of the

case without pampp)

2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of thethem A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface

them A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface

The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation

Three possibilities have to be considered for the oxygen-fedozone generator

Three possibilities have to be considered for the oxygen-fedozone generatorozone generator

bull Excited N2 molecules lead to an increased O2 dissociation in

ozone generator

bull Excited N2 molecules lead to an increased O2 dissociation in2 2such case an increased efficiency is correlated to the N2admixture

2 2such case an increased efficiency is correlated to the N2admixture

bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial

bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial

bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2

bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2g p g 3 pp y 2g p g 3 pp y 2

Effect of methane on ozone efficiency and specific powerEffect of methane on ozone efficiency and specific power

Effect of Methane on Ozone Content in Outlet Gas and on Specific Power Pure O2

13 12

10

11

12

t 8

10

8

9

10

ne c

onte

nt w

t

6

8

ecifi

c po

wer

kW

hlb

5

6

7

Ozo

n

2

4 Spe

400E+00 20E+03 40E+03 60E+03 80E+03 10E+04 12E+04

Methane in feedgas ppm

0

Ozone content in the outlet gas Specif ic pow er of the ozone generatorg p p g

Effects of N2 and CH4Effects of N2 and CH4

Pi t f h t lli N O t tPicture of an amorphous-crystalline N2O5 structurecaptured at the Orlando Skylake water plant in 2006

Plasma Chemistry with CH4 Impurities

OxygenO2 N2

e - e -

CHO N2

NO2

O NO

O2 N O2 O3

NOH

CH4e-

O3 NO

NO2

O2O3NO N

NO2 O

NO2

NO2

N2ONO3

N

O3

NO2

NO

HNO3

N2O4

N2O5

NO2

NO3

N2O5

Effect of methane on the electrode surfaces

a) b)

Inlet Outlet Outlet

) d)

I l t I l t

c) d)

Electrode of the ozone generator afterseveral hours in CH8O2 and up to 2 wt of methane (a b c)

Inlet Inlet

three hours in CH8O2+traces of N2 and up to 1 wt of methane (d) Visible change of discharge character at about 13 length of electrode (a d)

Kinetics of CHx Conversion without N2

conversion by collisions

O2 + CHx 12wt O3 + CO2 +H2O

deposition vaporizationby sputtering

ibl b l 1000 CHreversible process below 1000ppm CH4

Effect of water on electrode surface with N2

Inlet

OutletOutlet

Electrode of the ozone generator after several hours in H OO N

Inlet

Electrode of the ozone generator after several hours in H2OO2N2

Effect of water on electrode surface

Long term effect (800 hrs) of H2OO2N2

Kinetics of CHx Conversion with N2

conversion by collisionsHNO3 formation

O2 + N2 +CHx 12wtO2 + CO2 +H2O + HNO3

deposition vaporizationby sputtering

H2O + HNO3

by sputtering

irreversible process above a N2 threshold () ltlt 1000ppm N2

sticky deposit

p 2 ( ) pp 2 any CH4 concentration (60ppm)

Plasma Chemistry with CH4 ImpuritiesPlasma Chemistry with CH4 Impurities4

bull Formation of NO and NO2 depends on O3 N2 and gas temperature Conclusion N2 admixture is the key factor

SummarySummaryyyThe mechanisms of formed NOx by-products follows the sameThe mechanisms of formed NOx by-products follows the sameprinciples as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentration

principles as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentrationozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)

ozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)g p ( g p )

The conversion of methane to OH and H2O is found to depend on

g p ( g p )

The conversion of methane to OH and H2O is found to depend ondissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)

dissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)discharge gap)discharge gap)

How do you optimize an ozone generatorg

Scientific ApproachScientific ApproachTheoretical Experimental

pppp

c [wt]

f [Hz]

c [wt]

f [Hz]

[kW]UUUβ1

1Cf4αPn

1iiminpeakimin

iiD

q [kWm2]q [kWm2]

150

180

][V]voltagepeakUpeak

[]cylinder perslicesofamountnsliceii

whereth

09 00

30

60

90

120

effic

ienc

y [

][0tdj t bl[F]sliceisdielectricofecapacitancC

[Hz]frequencyf[V]sliceivoltageminimumiUmin

thiD

th

10

28

46

64

82

39

107

176

244 power density

[kWm2]

ozone conc [wt][]CCβ

][0parameteradjustableα

iDiGi

Impact of Power Inductionp

350

400

wer

200

250

300

App

lied

Pow

Arr C 2Arr D +0

Arr E +45Arr F +7

Arr G +3

5 0

100

150

Frac

tion

of

1 2 3 4

ReferenceArr B unstable

Arr C -2

00

50

4Position (1inlet 4outlet)

Experimental Test Rigp g

Experimental Test Rigp g

Outer grounded electrode (left picture) and the dielectric covered inner electrodes (right) d e ect c cove ed e e ect odes ( g t)

Reference (Traditional) Arrangement

Inlet OutletGas flow direction

Optimized Arrangement

Inlet OutletGas flow direction

Intelligent Gap System (IGS)g p y ( )

Molecular Oxygen (O2) Ozone (O3)

O2 O3

yg ( 2) ( 3)

Particle Size SynthesisParticle Size SynthesisByBy--Products Cluster FormationProducts Cluster Formationyy

high diffusion and deposition to surfaces

low diffusion rate good transport

high sedimentation on the structurehigh sedimentation on the structure

Degreacutemont Technologies ndash OzoniaIntelligent Gap SystemIntelligent Gap System

G Vezzuacute JL Lopez A Freilich and K Becker Optimizationof Large-Scale Ozone Generators IEEE Transactions onPlasma Science Vol 37 No 6 p 890-896 (2009)

ConclusionsConclusionsConclusionsConclusionsFundamentals of ozone synthesis in a DBD plasmay p

ndash Highly filamented DBD discharges are best-suitedfor the production of ozone concentrations in therange of 6 to 14 wtrange of 6 to 14 wt

ndash The preferred characteristic of the microdischargesare Townsend-like at reduced electric fields Enaround 190 Townsend

ndash Detrimental side-effects induced by by-productscan be avoided by a proper design of the electrodecan be avoided by a proper design of the electrodearrangement The phenomenon is related to thediffusion rates of formed by-product clusters

ConclusionsConclusionsConclusionsConclusionsBenefits from DBD microplasma tailoring

ndash Reduced power consumption of up to 10 improvement

ndash Increased ozone concentrations of up to 14 now achievable

ndash Improved neutralization and conditioning of detrimental by-products

ndash Reduced system capital and operational cost

New technologies to improve ozone p

generatorg

HV Pulsed Power SwitchingHV Pulsed Power Switching

Microchannel Generation of Ozone

Channel ArrayChannel Array

Microchannel

330 microm 230 microm

Some Cap-DBD Devices Operating in Air

Increase of 60 of

Spacing 225 μmof 60 of plasma

No space

Cap‐DBD ozone generation

bull Ozone concentration is evaluated via Eco S d l UV 100 O A l (0 01Sensors model UV-100 Ozone Analyzer (001 ndash 900 ppm wiht an accuracy of plusmn2)

bull Three reactors 6 tubings 6rdquo with spacings of 0 μm 225 μm and 500 μm running at 3 kV μ μ μ g

SpacingOzone Concentration

3 kV rms 4 kV rms3 kV rms 4 kV rms

0 μm 660 ppm

225 μm 550 ppm

For a device of such small scale these ozone levels are promising

500 μm 380 ppm

J Mahoney W Zhu VS Johnson KH Becker and JL Lopez Electrical and optical emissionmeasurements of a capillary dielectric barrier discharge European Physics Journal D Vol 60 441-447(2010)

QuestionsQuestions

Thank YouFor more informationProf Jose L Lopez PhD

Thank YouFor more informationDepartment of Physics

Telephone (973) 761-9057Email joselopez1shuedu

Website wwwshueduacademicsartsciphysicsWebsite wwwshueduacademicsartsciphysics

Page 73: Dielectric Barrier Discharge (DBD) & Progress in Large ...bonitz/si12/talks/august_8/lopez_si12.pdf · Dielectric Barrier Discharge (DBD) & Progress in Large-Scale Ozone Generation

N2O5 FormationN2O5 Formation2 52 5p=2 bara cwt=20degC q=35kWm2 f=1450Hz

45N2O5 AT95

30

35

40

N

2 B

lend

ing

N2O AT95N2O5 IGSN2O IGSN2O5 LGN2O LG

1 5

20

25

nt [p

pmV]

3

wt

05

10

15

NO

x co

nten

005 7 9 11 13 15 17

ozone conc [wt]

Amount of formed N2O5 and N2O as a function of ozone concentration at 3 wt of nitrogen admixture and fori l dvarious electrode arrangements

Plasma Emission SpectroscopyPlasma Emission Spectroscopyp pyp py

Relative Emissions of the Ozonizer plasmaRelative Emissions of the Ozonizer plasma

Region 300- 850 nm from individual (calibrated) regions (smoothed by PeakFit) Single-coated ozone generator Inlet side

3 5E+06

30E+06

35E+06

7 9

20E+06

25E+06

nten

sity

au

2

311 12

10E+06

15E+06

In 4

5

6 8 10

14

15

16

17

00E+00

50E+05

280 300 320 340 360 380 400 420 440 460 480 500 520 540 560 580 600 620 640 660 680 700 720 740 760 780 800 820 840 860

Wavelength nm

1 13

Wavelength nm

Absolute Emission of the DBD PlasmaAbsolute Emission of the DBD Plasma

Intensities in (O2+3 wtN2) plasma

1 20E+04

100E+04

120E+04

600E+03

800E+03

nten

sity

(au

)

200E+03

400E+03

In

O(777)

000E+00200 250 300 350 400 450 500 550 600 650 700 750 800 850

Wavelength nm

Intensities in 3 wtN2+O2 plasmaIntensities in 3 wtN2+O2 plasma

Plasma Chemistry in OzonizersPlasma Chemistry in Ozonizers

Dry Air O2 N2

e - e -

O N2 N O2

O3 NO

O2 N O2

O3

N

3

NO2

O2 O3

NO

N

NO2 O3

N2O

NO3 N

N2O4

NO2

NO2

N2O5

NO3

Primary electron-driven chemical reactions leading to the formation of N2O5 and N2O in a dry air plasma

Plasma emission diagnostics role of N2Plasma emission diagnostics role of N2

Dry Air O2 N2

e - e -

O N2 N O2

O3 NO

O2 N O2

O3

O

N

ON

NO2

O2O3

N

NO N

NO2 O3

N2O

NO3 N

N2O4

NO2

NO2

N2O5

NO3

ONbullWith N2 present ndash less oxygen atoms are formed However the difference in intensity is

very small

Modeling of plasma chemistry incl the NxOy chemistry up to N2O5 for different Oxygen Nitrogen mixtures varying power deposition scenarios

and initial ozone background concentrations (up to 15) previously done

The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation

The role of N2 must be related to its by-products reacting on the surface of the electrodeThe role of N2 must be related to its by-products reacting on the surface of the electrode

The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established

Ab 8 t f O

The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established

Ab 8 t f OAbove 8 wt of O3

1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)

Above 8 wt of O3

1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)case without pampp)

2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of the

case without pampp)

2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of thethem A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface

them A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface

The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation

Three possibilities have to be considered for the oxygen-fedozone generator

Three possibilities have to be considered for the oxygen-fedozone generatorozone generator

bull Excited N2 molecules lead to an increased O2 dissociation in

ozone generator

bull Excited N2 molecules lead to an increased O2 dissociation in2 2such case an increased efficiency is correlated to the N2admixture

2 2such case an increased efficiency is correlated to the N2admixture

bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial

bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial

bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2

bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2g p g 3 pp y 2g p g 3 pp y 2

Effect of methane on ozone efficiency and specific powerEffect of methane on ozone efficiency and specific power

Effect of Methane on Ozone Content in Outlet Gas and on Specific Power Pure O2

13 12

10

11

12

t 8

10

8

9

10

ne c

onte

nt w

t

6

8

ecifi

c po

wer

kW

hlb

5

6

7

Ozo

n

2

4 Spe

400E+00 20E+03 40E+03 60E+03 80E+03 10E+04 12E+04

Methane in feedgas ppm

0

Ozone content in the outlet gas Specif ic pow er of the ozone generatorg p p g

Effects of N2 and CH4Effects of N2 and CH4

Pi t f h t lli N O t tPicture of an amorphous-crystalline N2O5 structurecaptured at the Orlando Skylake water plant in 2006

Plasma Chemistry with CH4 Impurities

OxygenO2 N2

e - e -

CHO N2

NO2

O NO

O2 N O2 O3

NOH

CH4e-

O3 NO

NO2

O2O3NO N

NO2 O

NO2

NO2

N2ONO3

N

O3

NO2

NO

HNO3

N2O4

N2O5

NO2

NO3

N2O5

Effect of methane on the electrode surfaces

a) b)

Inlet Outlet Outlet

) d)

I l t I l t

c) d)

Electrode of the ozone generator afterseveral hours in CH8O2 and up to 2 wt of methane (a b c)

Inlet Inlet

three hours in CH8O2+traces of N2 and up to 1 wt of methane (d) Visible change of discharge character at about 13 length of electrode (a d)

Kinetics of CHx Conversion without N2

conversion by collisions

O2 + CHx 12wt O3 + CO2 +H2O

deposition vaporizationby sputtering

ibl b l 1000 CHreversible process below 1000ppm CH4

Effect of water on electrode surface with N2

Inlet

OutletOutlet

Electrode of the ozone generator after several hours in H OO N

Inlet

Electrode of the ozone generator after several hours in H2OO2N2

Effect of water on electrode surface

Long term effect (800 hrs) of H2OO2N2

Kinetics of CHx Conversion with N2

conversion by collisionsHNO3 formation

O2 + N2 +CHx 12wtO2 + CO2 +H2O + HNO3

deposition vaporizationby sputtering

H2O + HNO3

by sputtering

irreversible process above a N2 threshold () ltlt 1000ppm N2

sticky deposit

p 2 ( ) pp 2 any CH4 concentration (60ppm)

Plasma Chemistry with CH4 ImpuritiesPlasma Chemistry with CH4 Impurities4

bull Formation of NO and NO2 depends on O3 N2 and gas temperature Conclusion N2 admixture is the key factor

SummarySummaryyyThe mechanisms of formed NOx by-products follows the sameThe mechanisms of formed NOx by-products follows the sameprinciples as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentration

principles as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentrationozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)

ozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)g p ( g p )

The conversion of methane to OH and H2O is found to depend on

g p ( g p )

The conversion of methane to OH and H2O is found to depend ondissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)

dissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)discharge gap)discharge gap)

How do you optimize an ozone generatorg

Scientific ApproachScientific ApproachTheoretical Experimental

pppp

c [wt]

f [Hz]

c [wt]

f [Hz]

[kW]UUUβ1

1Cf4αPn

1iiminpeakimin

iiD

q [kWm2]q [kWm2]

150

180

][V]voltagepeakUpeak

[]cylinder perslicesofamountnsliceii

whereth

09 00

30

60

90

120

effic

ienc

y [

][0tdj t bl[F]sliceisdielectricofecapacitancC

[Hz]frequencyf[V]sliceivoltageminimumiUmin

thiD

th

10

28

46

64

82

39

107

176

244 power density

[kWm2]

ozone conc [wt][]CCβ

][0parameteradjustableα

iDiGi

Impact of Power Inductionp

350

400

wer

200

250

300

App

lied

Pow

Arr C 2Arr D +0

Arr E +45Arr F +7

Arr G +3

5 0

100

150

Frac

tion

of

1 2 3 4

ReferenceArr B unstable

Arr C -2

00

50

4Position (1inlet 4outlet)

Experimental Test Rigp g

Experimental Test Rigp g

Outer grounded electrode (left picture) and the dielectric covered inner electrodes (right) d e ect c cove ed e e ect odes ( g t)

Reference (Traditional) Arrangement

Inlet OutletGas flow direction

Optimized Arrangement

Inlet OutletGas flow direction

Intelligent Gap System (IGS)g p y ( )

Molecular Oxygen (O2) Ozone (O3)

O2 O3

yg ( 2) ( 3)

Particle Size SynthesisParticle Size SynthesisByBy--Products Cluster FormationProducts Cluster Formationyy

high diffusion and deposition to surfaces

low diffusion rate good transport

high sedimentation on the structurehigh sedimentation on the structure

Degreacutemont Technologies ndash OzoniaIntelligent Gap SystemIntelligent Gap System

G Vezzuacute JL Lopez A Freilich and K Becker Optimizationof Large-Scale Ozone Generators IEEE Transactions onPlasma Science Vol 37 No 6 p 890-896 (2009)

ConclusionsConclusionsConclusionsConclusionsFundamentals of ozone synthesis in a DBD plasmay p

ndash Highly filamented DBD discharges are best-suitedfor the production of ozone concentrations in therange of 6 to 14 wtrange of 6 to 14 wt

ndash The preferred characteristic of the microdischargesare Townsend-like at reduced electric fields Enaround 190 Townsend

ndash Detrimental side-effects induced by by-productscan be avoided by a proper design of the electrodecan be avoided by a proper design of the electrodearrangement The phenomenon is related to thediffusion rates of formed by-product clusters

ConclusionsConclusionsConclusionsConclusionsBenefits from DBD microplasma tailoring

ndash Reduced power consumption of up to 10 improvement

ndash Increased ozone concentrations of up to 14 now achievable

ndash Improved neutralization and conditioning of detrimental by-products

ndash Reduced system capital and operational cost

New technologies to improve ozone p

generatorg

HV Pulsed Power SwitchingHV Pulsed Power Switching

Microchannel Generation of Ozone

Channel ArrayChannel Array

Microchannel

330 microm 230 microm

Some Cap-DBD Devices Operating in Air

Increase of 60 of

Spacing 225 μmof 60 of plasma

No space

Cap‐DBD ozone generation

bull Ozone concentration is evaluated via Eco S d l UV 100 O A l (0 01Sensors model UV-100 Ozone Analyzer (001 ndash 900 ppm wiht an accuracy of plusmn2)

bull Three reactors 6 tubings 6rdquo with spacings of 0 μm 225 μm and 500 μm running at 3 kV μ μ μ g

SpacingOzone Concentration

3 kV rms 4 kV rms3 kV rms 4 kV rms

0 μm 660 ppm

225 μm 550 ppm

For a device of such small scale these ozone levels are promising

500 μm 380 ppm

J Mahoney W Zhu VS Johnson KH Becker and JL Lopez Electrical and optical emissionmeasurements of a capillary dielectric barrier discharge European Physics Journal D Vol 60 441-447(2010)

QuestionsQuestions

Thank YouFor more informationProf Jose L Lopez PhD

Thank YouFor more informationDepartment of Physics

Telephone (973) 761-9057Email joselopez1shuedu

Website wwwshueduacademicsartsciphysicsWebsite wwwshueduacademicsartsciphysics

Page 74: Dielectric Barrier Discharge (DBD) & Progress in Large ...bonitz/si12/talks/august_8/lopez_si12.pdf · Dielectric Barrier Discharge (DBD) & Progress in Large-Scale Ozone Generation

Plasma Emission SpectroscopyPlasma Emission Spectroscopyp pyp py

Relative Emissions of the Ozonizer plasmaRelative Emissions of the Ozonizer plasma

Region 300- 850 nm from individual (calibrated) regions (smoothed by PeakFit) Single-coated ozone generator Inlet side

3 5E+06

30E+06

35E+06

7 9

20E+06

25E+06

nten

sity

au

2

311 12

10E+06

15E+06

In 4

5

6 8 10

14

15

16

17

00E+00

50E+05

280 300 320 340 360 380 400 420 440 460 480 500 520 540 560 580 600 620 640 660 680 700 720 740 760 780 800 820 840 860

Wavelength nm

1 13

Wavelength nm

Absolute Emission of the DBD PlasmaAbsolute Emission of the DBD Plasma

Intensities in (O2+3 wtN2) plasma

1 20E+04

100E+04

120E+04

600E+03

800E+03

nten

sity

(au

)

200E+03

400E+03

In

O(777)

000E+00200 250 300 350 400 450 500 550 600 650 700 750 800 850

Wavelength nm

Intensities in 3 wtN2+O2 plasmaIntensities in 3 wtN2+O2 plasma

Plasma Chemistry in OzonizersPlasma Chemistry in Ozonizers

Dry Air O2 N2

e - e -

O N2 N O2

O3 NO

O2 N O2

O3

N

3

NO2

O2 O3

NO

N

NO2 O3

N2O

NO3 N

N2O4

NO2

NO2

N2O5

NO3

Primary electron-driven chemical reactions leading to the formation of N2O5 and N2O in a dry air plasma

Plasma emission diagnostics role of N2Plasma emission diagnostics role of N2

Dry Air O2 N2

e - e -

O N2 N O2

O3 NO

O2 N O2

O3

O

N

ON

NO2

O2O3

N

NO N

NO2 O3

N2O

NO3 N

N2O4

NO2

NO2

N2O5

NO3

ONbullWith N2 present ndash less oxygen atoms are formed However the difference in intensity is

very small

Modeling of plasma chemistry incl the NxOy chemistry up to N2O5 for different Oxygen Nitrogen mixtures varying power deposition scenarios

and initial ozone background concentrations (up to 15) previously done

The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation

The role of N2 must be related to its by-products reacting on the surface of the electrodeThe role of N2 must be related to its by-products reacting on the surface of the electrode

The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established

Ab 8 t f O

The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established

Ab 8 t f OAbove 8 wt of O3

1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)

Above 8 wt of O3

1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)case without pampp)

2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of the

case without pampp)

2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of thethem A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface

them A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface

The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation

Three possibilities have to be considered for the oxygen-fedozone generator

Three possibilities have to be considered for the oxygen-fedozone generatorozone generator

bull Excited N2 molecules lead to an increased O2 dissociation in

ozone generator

bull Excited N2 molecules lead to an increased O2 dissociation in2 2such case an increased efficiency is correlated to the N2admixture

2 2such case an increased efficiency is correlated to the N2admixture

bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial

bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial

bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2

bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2g p g 3 pp y 2g p g 3 pp y 2

Effect of methane on ozone efficiency and specific powerEffect of methane on ozone efficiency and specific power

Effect of Methane on Ozone Content in Outlet Gas and on Specific Power Pure O2

13 12

10

11

12

t 8

10

8

9

10

ne c

onte

nt w

t

6

8

ecifi

c po

wer

kW

hlb

5

6

7

Ozo

n

2

4 Spe

400E+00 20E+03 40E+03 60E+03 80E+03 10E+04 12E+04

Methane in feedgas ppm

0

Ozone content in the outlet gas Specif ic pow er of the ozone generatorg p p g

Effects of N2 and CH4Effects of N2 and CH4

Pi t f h t lli N O t tPicture of an amorphous-crystalline N2O5 structurecaptured at the Orlando Skylake water plant in 2006

Plasma Chemistry with CH4 Impurities

OxygenO2 N2

e - e -

CHO N2

NO2

O NO

O2 N O2 O3

NOH

CH4e-

O3 NO

NO2

O2O3NO N

NO2 O

NO2

NO2

N2ONO3

N

O3

NO2

NO

HNO3

N2O4

N2O5

NO2

NO3

N2O5

Effect of methane on the electrode surfaces

a) b)

Inlet Outlet Outlet

) d)

I l t I l t

c) d)

Electrode of the ozone generator afterseveral hours in CH8O2 and up to 2 wt of methane (a b c)

Inlet Inlet

three hours in CH8O2+traces of N2 and up to 1 wt of methane (d) Visible change of discharge character at about 13 length of electrode (a d)

Kinetics of CHx Conversion without N2

conversion by collisions

O2 + CHx 12wt O3 + CO2 +H2O

deposition vaporizationby sputtering

ibl b l 1000 CHreversible process below 1000ppm CH4

Effect of water on electrode surface with N2

Inlet

OutletOutlet

Electrode of the ozone generator after several hours in H OO N

Inlet

Electrode of the ozone generator after several hours in H2OO2N2

Effect of water on electrode surface

Long term effect (800 hrs) of H2OO2N2

Kinetics of CHx Conversion with N2

conversion by collisionsHNO3 formation

O2 + N2 +CHx 12wtO2 + CO2 +H2O + HNO3

deposition vaporizationby sputtering

H2O + HNO3

by sputtering

irreversible process above a N2 threshold () ltlt 1000ppm N2

sticky deposit

p 2 ( ) pp 2 any CH4 concentration (60ppm)

Plasma Chemistry with CH4 ImpuritiesPlasma Chemistry with CH4 Impurities4

bull Formation of NO and NO2 depends on O3 N2 and gas temperature Conclusion N2 admixture is the key factor

SummarySummaryyyThe mechanisms of formed NOx by-products follows the sameThe mechanisms of formed NOx by-products follows the sameprinciples as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentration

principles as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentrationozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)

ozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)g p ( g p )

The conversion of methane to OH and H2O is found to depend on

g p ( g p )

The conversion of methane to OH and H2O is found to depend ondissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)

dissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)discharge gap)discharge gap)

How do you optimize an ozone generatorg

Scientific ApproachScientific ApproachTheoretical Experimental

pppp

c [wt]

f [Hz]

c [wt]

f [Hz]

[kW]UUUβ1

1Cf4αPn

1iiminpeakimin

iiD

q [kWm2]q [kWm2]

150

180

][V]voltagepeakUpeak

[]cylinder perslicesofamountnsliceii

whereth

09 00

30

60

90

120

effic

ienc

y [

][0tdj t bl[F]sliceisdielectricofecapacitancC

[Hz]frequencyf[V]sliceivoltageminimumiUmin

thiD

th

10

28

46

64

82

39

107

176

244 power density

[kWm2]

ozone conc [wt][]CCβ

][0parameteradjustableα

iDiGi

Impact of Power Inductionp

350

400

wer

200

250

300

App

lied

Pow

Arr C 2Arr D +0

Arr E +45Arr F +7

Arr G +3

5 0

100

150

Frac

tion

of

1 2 3 4

ReferenceArr B unstable

Arr C -2

00

50

4Position (1inlet 4outlet)

Experimental Test Rigp g

Experimental Test Rigp g

Outer grounded electrode (left picture) and the dielectric covered inner electrodes (right) d e ect c cove ed e e ect odes ( g t)

Reference (Traditional) Arrangement

Inlet OutletGas flow direction

Optimized Arrangement

Inlet OutletGas flow direction

Intelligent Gap System (IGS)g p y ( )

Molecular Oxygen (O2) Ozone (O3)

O2 O3

yg ( 2) ( 3)

Particle Size SynthesisParticle Size SynthesisByBy--Products Cluster FormationProducts Cluster Formationyy

high diffusion and deposition to surfaces

low diffusion rate good transport

high sedimentation on the structurehigh sedimentation on the structure

Degreacutemont Technologies ndash OzoniaIntelligent Gap SystemIntelligent Gap System

G Vezzuacute JL Lopez A Freilich and K Becker Optimizationof Large-Scale Ozone Generators IEEE Transactions onPlasma Science Vol 37 No 6 p 890-896 (2009)

ConclusionsConclusionsConclusionsConclusionsFundamentals of ozone synthesis in a DBD plasmay p

ndash Highly filamented DBD discharges are best-suitedfor the production of ozone concentrations in therange of 6 to 14 wtrange of 6 to 14 wt

ndash The preferred characteristic of the microdischargesare Townsend-like at reduced electric fields Enaround 190 Townsend

ndash Detrimental side-effects induced by by-productscan be avoided by a proper design of the electrodecan be avoided by a proper design of the electrodearrangement The phenomenon is related to thediffusion rates of formed by-product clusters

ConclusionsConclusionsConclusionsConclusionsBenefits from DBD microplasma tailoring

ndash Reduced power consumption of up to 10 improvement

ndash Increased ozone concentrations of up to 14 now achievable

ndash Improved neutralization and conditioning of detrimental by-products

ndash Reduced system capital and operational cost

New technologies to improve ozone p

generatorg

HV Pulsed Power SwitchingHV Pulsed Power Switching

Microchannel Generation of Ozone

Channel ArrayChannel Array

Microchannel

330 microm 230 microm

Some Cap-DBD Devices Operating in Air

Increase of 60 of

Spacing 225 μmof 60 of plasma

No space

Cap‐DBD ozone generation

bull Ozone concentration is evaluated via Eco S d l UV 100 O A l (0 01Sensors model UV-100 Ozone Analyzer (001 ndash 900 ppm wiht an accuracy of plusmn2)

bull Three reactors 6 tubings 6rdquo with spacings of 0 μm 225 μm and 500 μm running at 3 kV μ μ μ g

SpacingOzone Concentration

3 kV rms 4 kV rms3 kV rms 4 kV rms

0 μm 660 ppm

225 μm 550 ppm

For a device of such small scale these ozone levels are promising

500 μm 380 ppm

J Mahoney W Zhu VS Johnson KH Becker and JL Lopez Electrical and optical emissionmeasurements of a capillary dielectric barrier discharge European Physics Journal D Vol 60 441-447(2010)

QuestionsQuestions

Thank YouFor more informationProf Jose L Lopez PhD

Thank YouFor more informationDepartment of Physics

Telephone (973) 761-9057Email joselopez1shuedu

Website wwwshueduacademicsartsciphysicsWebsite wwwshueduacademicsartsciphysics

Page 75: Dielectric Barrier Discharge (DBD) & Progress in Large ...bonitz/si12/talks/august_8/lopez_si12.pdf · Dielectric Barrier Discharge (DBD) & Progress in Large-Scale Ozone Generation

Relative Emissions of the Ozonizer plasmaRelative Emissions of the Ozonizer plasma

Region 300- 850 nm from individual (calibrated) regions (smoothed by PeakFit) Single-coated ozone generator Inlet side

3 5E+06

30E+06

35E+06

7 9

20E+06

25E+06

nten

sity

au

2

311 12

10E+06

15E+06

In 4

5

6 8 10

14

15

16

17

00E+00

50E+05

280 300 320 340 360 380 400 420 440 460 480 500 520 540 560 580 600 620 640 660 680 700 720 740 760 780 800 820 840 860

Wavelength nm

1 13

Wavelength nm

Absolute Emission of the DBD PlasmaAbsolute Emission of the DBD Plasma

Intensities in (O2+3 wtN2) plasma

1 20E+04

100E+04

120E+04

600E+03

800E+03

nten

sity

(au

)

200E+03

400E+03

In

O(777)

000E+00200 250 300 350 400 450 500 550 600 650 700 750 800 850

Wavelength nm

Intensities in 3 wtN2+O2 plasmaIntensities in 3 wtN2+O2 plasma

Plasma Chemistry in OzonizersPlasma Chemistry in Ozonizers

Dry Air O2 N2

e - e -

O N2 N O2

O3 NO

O2 N O2

O3

N

3

NO2

O2 O3

NO

N

NO2 O3

N2O

NO3 N

N2O4

NO2

NO2

N2O5

NO3

Primary electron-driven chemical reactions leading to the formation of N2O5 and N2O in a dry air plasma

Plasma emission diagnostics role of N2Plasma emission diagnostics role of N2

Dry Air O2 N2

e - e -

O N2 N O2

O3 NO

O2 N O2

O3

O

N

ON

NO2

O2O3

N

NO N

NO2 O3

N2O

NO3 N

N2O4

NO2

NO2

N2O5

NO3

ONbullWith N2 present ndash less oxygen atoms are formed However the difference in intensity is

very small

Modeling of plasma chemistry incl the NxOy chemistry up to N2O5 for different Oxygen Nitrogen mixtures varying power deposition scenarios

and initial ozone background concentrations (up to 15) previously done

The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation

The role of N2 must be related to its by-products reacting on the surface of the electrodeThe role of N2 must be related to its by-products reacting on the surface of the electrode

The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established

Ab 8 t f O

The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established

Ab 8 t f OAbove 8 wt of O3

1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)

Above 8 wt of O3

1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)case without pampp)

2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of the

case without pampp)

2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of thethem A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface

them A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface

The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation

Three possibilities have to be considered for the oxygen-fedozone generator

Three possibilities have to be considered for the oxygen-fedozone generatorozone generator

bull Excited N2 molecules lead to an increased O2 dissociation in

ozone generator

bull Excited N2 molecules lead to an increased O2 dissociation in2 2such case an increased efficiency is correlated to the N2admixture

2 2such case an increased efficiency is correlated to the N2admixture

bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial

bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial

bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2

bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2g p g 3 pp y 2g p g 3 pp y 2

Effect of methane on ozone efficiency and specific powerEffect of methane on ozone efficiency and specific power

Effect of Methane on Ozone Content in Outlet Gas and on Specific Power Pure O2

13 12

10

11

12

t 8

10

8

9

10

ne c

onte

nt w

t

6

8

ecifi

c po

wer

kW

hlb

5

6

7

Ozo

n

2

4 Spe

400E+00 20E+03 40E+03 60E+03 80E+03 10E+04 12E+04

Methane in feedgas ppm

0

Ozone content in the outlet gas Specif ic pow er of the ozone generatorg p p g

Effects of N2 and CH4Effects of N2 and CH4

Pi t f h t lli N O t tPicture of an amorphous-crystalline N2O5 structurecaptured at the Orlando Skylake water plant in 2006

Plasma Chemistry with CH4 Impurities

OxygenO2 N2

e - e -

CHO N2

NO2

O NO

O2 N O2 O3

NOH

CH4e-

O3 NO

NO2

O2O3NO N

NO2 O

NO2

NO2

N2ONO3

N

O3

NO2

NO

HNO3

N2O4

N2O5

NO2

NO3

N2O5

Effect of methane on the electrode surfaces

a) b)

Inlet Outlet Outlet

) d)

I l t I l t

c) d)

Electrode of the ozone generator afterseveral hours in CH8O2 and up to 2 wt of methane (a b c)

Inlet Inlet

three hours in CH8O2+traces of N2 and up to 1 wt of methane (d) Visible change of discharge character at about 13 length of electrode (a d)

Kinetics of CHx Conversion without N2

conversion by collisions

O2 + CHx 12wt O3 + CO2 +H2O

deposition vaporizationby sputtering

ibl b l 1000 CHreversible process below 1000ppm CH4

Effect of water on electrode surface with N2

Inlet

OutletOutlet

Electrode of the ozone generator after several hours in H OO N

Inlet

Electrode of the ozone generator after several hours in H2OO2N2

Effect of water on electrode surface

Long term effect (800 hrs) of H2OO2N2

Kinetics of CHx Conversion with N2

conversion by collisionsHNO3 formation

O2 + N2 +CHx 12wtO2 + CO2 +H2O + HNO3

deposition vaporizationby sputtering

H2O + HNO3

by sputtering

irreversible process above a N2 threshold () ltlt 1000ppm N2

sticky deposit

p 2 ( ) pp 2 any CH4 concentration (60ppm)

Plasma Chemistry with CH4 ImpuritiesPlasma Chemistry with CH4 Impurities4

bull Formation of NO and NO2 depends on O3 N2 and gas temperature Conclusion N2 admixture is the key factor

SummarySummaryyyThe mechanisms of formed NOx by-products follows the sameThe mechanisms of formed NOx by-products follows the sameprinciples as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentration

principles as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentrationozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)

ozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)g p ( g p )

The conversion of methane to OH and H2O is found to depend on

g p ( g p )

The conversion of methane to OH and H2O is found to depend ondissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)

dissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)discharge gap)discharge gap)

How do you optimize an ozone generatorg

Scientific ApproachScientific ApproachTheoretical Experimental

pppp

c [wt]

f [Hz]

c [wt]

f [Hz]

[kW]UUUβ1

1Cf4αPn

1iiminpeakimin

iiD

q [kWm2]q [kWm2]

150

180

][V]voltagepeakUpeak

[]cylinder perslicesofamountnsliceii

whereth

09 00

30

60

90

120

effic

ienc

y [

][0tdj t bl[F]sliceisdielectricofecapacitancC

[Hz]frequencyf[V]sliceivoltageminimumiUmin

thiD

th

10

28

46

64

82

39

107

176

244 power density

[kWm2]

ozone conc [wt][]CCβ

][0parameteradjustableα

iDiGi

Impact of Power Inductionp

350

400

wer

200

250

300

App

lied

Pow

Arr C 2Arr D +0

Arr E +45Arr F +7

Arr G +3

5 0

100

150

Frac

tion

of

1 2 3 4

ReferenceArr B unstable

Arr C -2

00

50

4Position (1inlet 4outlet)

Experimental Test Rigp g

Experimental Test Rigp g

Outer grounded electrode (left picture) and the dielectric covered inner electrodes (right) d e ect c cove ed e e ect odes ( g t)

Reference (Traditional) Arrangement

Inlet OutletGas flow direction

Optimized Arrangement

Inlet OutletGas flow direction

Intelligent Gap System (IGS)g p y ( )

Molecular Oxygen (O2) Ozone (O3)

O2 O3

yg ( 2) ( 3)

Particle Size SynthesisParticle Size SynthesisByBy--Products Cluster FormationProducts Cluster Formationyy

high diffusion and deposition to surfaces

low diffusion rate good transport

high sedimentation on the structurehigh sedimentation on the structure

Degreacutemont Technologies ndash OzoniaIntelligent Gap SystemIntelligent Gap System

G Vezzuacute JL Lopez A Freilich and K Becker Optimizationof Large-Scale Ozone Generators IEEE Transactions onPlasma Science Vol 37 No 6 p 890-896 (2009)

ConclusionsConclusionsConclusionsConclusionsFundamentals of ozone synthesis in a DBD plasmay p

ndash Highly filamented DBD discharges are best-suitedfor the production of ozone concentrations in therange of 6 to 14 wtrange of 6 to 14 wt

ndash The preferred characteristic of the microdischargesare Townsend-like at reduced electric fields Enaround 190 Townsend

ndash Detrimental side-effects induced by by-productscan be avoided by a proper design of the electrodecan be avoided by a proper design of the electrodearrangement The phenomenon is related to thediffusion rates of formed by-product clusters

ConclusionsConclusionsConclusionsConclusionsBenefits from DBD microplasma tailoring

ndash Reduced power consumption of up to 10 improvement

ndash Increased ozone concentrations of up to 14 now achievable

ndash Improved neutralization and conditioning of detrimental by-products

ndash Reduced system capital and operational cost

New technologies to improve ozone p

generatorg

HV Pulsed Power SwitchingHV Pulsed Power Switching

Microchannel Generation of Ozone

Channel ArrayChannel Array

Microchannel

330 microm 230 microm

Some Cap-DBD Devices Operating in Air

Increase of 60 of

Spacing 225 μmof 60 of plasma

No space

Cap‐DBD ozone generation

bull Ozone concentration is evaluated via Eco S d l UV 100 O A l (0 01Sensors model UV-100 Ozone Analyzer (001 ndash 900 ppm wiht an accuracy of plusmn2)

bull Three reactors 6 tubings 6rdquo with spacings of 0 μm 225 μm and 500 μm running at 3 kV μ μ μ g

SpacingOzone Concentration

3 kV rms 4 kV rms3 kV rms 4 kV rms

0 μm 660 ppm

225 μm 550 ppm

For a device of such small scale these ozone levels are promising

500 μm 380 ppm

J Mahoney W Zhu VS Johnson KH Becker and JL Lopez Electrical and optical emissionmeasurements of a capillary dielectric barrier discharge European Physics Journal D Vol 60 441-447(2010)

QuestionsQuestions

Thank YouFor more informationProf Jose L Lopez PhD

Thank YouFor more informationDepartment of Physics

Telephone (973) 761-9057Email joselopez1shuedu

Website wwwshueduacademicsartsciphysicsWebsite wwwshueduacademicsartsciphysics

Page 76: Dielectric Barrier Discharge (DBD) & Progress in Large ...bonitz/si12/talks/august_8/lopez_si12.pdf · Dielectric Barrier Discharge (DBD) & Progress in Large-Scale Ozone Generation

Absolute Emission of the DBD PlasmaAbsolute Emission of the DBD Plasma

Intensities in (O2+3 wtN2) plasma

1 20E+04

100E+04

120E+04

600E+03

800E+03

nten

sity

(au

)

200E+03

400E+03

In

O(777)

000E+00200 250 300 350 400 450 500 550 600 650 700 750 800 850

Wavelength nm

Intensities in 3 wtN2+O2 plasmaIntensities in 3 wtN2+O2 plasma

Plasma Chemistry in OzonizersPlasma Chemistry in Ozonizers

Dry Air O2 N2

e - e -

O N2 N O2

O3 NO

O2 N O2

O3

N

3

NO2

O2 O3

NO

N

NO2 O3

N2O

NO3 N

N2O4

NO2

NO2

N2O5

NO3

Primary electron-driven chemical reactions leading to the formation of N2O5 and N2O in a dry air plasma

Plasma emission diagnostics role of N2Plasma emission diagnostics role of N2

Dry Air O2 N2

e - e -

O N2 N O2

O3 NO

O2 N O2

O3

O

N

ON

NO2

O2O3

N

NO N

NO2 O3

N2O

NO3 N

N2O4

NO2

NO2

N2O5

NO3

ONbullWith N2 present ndash less oxygen atoms are formed However the difference in intensity is

very small

Modeling of plasma chemistry incl the NxOy chemistry up to N2O5 for different Oxygen Nitrogen mixtures varying power deposition scenarios

and initial ozone background concentrations (up to 15) previously done

The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation

The role of N2 must be related to its by-products reacting on the surface of the electrodeThe role of N2 must be related to its by-products reacting on the surface of the electrode

The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established

Ab 8 t f O

The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established

Ab 8 t f OAbove 8 wt of O3

1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)

Above 8 wt of O3

1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)case without pampp)

2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of the

case without pampp)

2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of thethem A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface

them A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface

The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation

Three possibilities have to be considered for the oxygen-fedozone generator

Three possibilities have to be considered for the oxygen-fedozone generatorozone generator

bull Excited N2 molecules lead to an increased O2 dissociation in

ozone generator

bull Excited N2 molecules lead to an increased O2 dissociation in2 2such case an increased efficiency is correlated to the N2admixture

2 2such case an increased efficiency is correlated to the N2admixture

bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial

bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial

bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2

bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2g p g 3 pp y 2g p g 3 pp y 2

Effect of methane on ozone efficiency and specific powerEffect of methane on ozone efficiency and specific power

Effect of Methane on Ozone Content in Outlet Gas and on Specific Power Pure O2

13 12

10

11

12

t 8

10

8

9

10

ne c

onte

nt w

t

6

8

ecifi

c po

wer

kW

hlb

5

6

7

Ozo

n

2

4 Spe

400E+00 20E+03 40E+03 60E+03 80E+03 10E+04 12E+04

Methane in feedgas ppm

0

Ozone content in the outlet gas Specif ic pow er of the ozone generatorg p p g

Effects of N2 and CH4Effects of N2 and CH4

Pi t f h t lli N O t tPicture of an amorphous-crystalline N2O5 structurecaptured at the Orlando Skylake water plant in 2006

Plasma Chemistry with CH4 Impurities

OxygenO2 N2

e - e -

CHO N2

NO2

O NO

O2 N O2 O3

NOH

CH4e-

O3 NO

NO2

O2O3NO N

NO2 O

NO2

NO2

N2ONO3

N

O3

NO2

NO

HNO3

N2O4

N2O5

NO2

NO3

N2O5

Effect of methane on the electrode surfaces

a) b)

Inlet Outlet Outlet

) d)

I l t I l t

c) d)

Electrode of the ozone generator afterseveral hours in CH8O2 and up to 2 wt of methane (a b c)

Inlet Inlet

three hours in CH8O2+traces of N2 and up to 1 wt of methane (d) Visible change of discharge character at about 13 length of electrode (a d)

Kinetics of CHx Conversion without N2

conversion by collisions

O2 + CHx 12wt O3 + CO2 +H2O

deposition vaporizationby sputtering

ibl b l 1000 CHreversible process below 1000ppm CH4

Effect of water on electrode surface with N2

Inlet

OutletOutlet

Electrode of the ozone generator after several hours in H OO N

Inlet

Electrode of the ozone generator after several hours in H2OO2N2

Effect of water on electrode surface

Long term effect (800 hrs) of H2OO2N2

Kinetics of CHx Conversion with N2

conversion by collisionsHNO3 formation

O2 + N2 +CHx 12wtO2 + CO2 +H2O + HNO3

deposition vaporizationby sputtering

H2O + HNO3

by sputtering

irreversible process above a N2 threshold () ltlt 1000ppm N2

sticky deposit

p 2 ( ) pp 2 any CH4 concentration (60ppm)

Plasma Chemistry with CH4 ImpuritiesPlasma Chemistry with CH4 Impurities4

bull Formation of NO and NO2 depends on O3 N2 and gas temperature Conclusion N2 admixture is the key factor

SummarySummaryyyThe mechanisms of formed NOx by-products follows the sameThe mechanisms of formed NOx by-products follows the sameprinciples as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentration

principles as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentrationozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)

ozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)g p ( g p )

The conversion of methane to OH and H2O is found to depend on

g p ( g p )

The conversion of methane to OH and H2O is found to depend ondissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)

dissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)discharge gap)discharge gap)

How do you optimize an ozone generatorg

Scientific ApproachScientific ApproachTheoretical Experimental

pppp

c [wt]

f [Hz]

c [wt]

f [Hz]

[kW]UUUβ1

1Cf4αPn

1iiminpeakimin

iiD

q [kWm2]q [kWm2]

150

180

][V]voltagepeakUpeak

[]cylinder perslicesofamountnsliceii

whereth

09 00

30

60

90

120

effic

ienc

y [

][0tdj t bl[F]sliceisdielectricofecapacitancC

[Hz]frequencyf[V]sliceivoltageminimumiUmin

thiD

th

10

28

46

64

82

39

107

176

244 power density

[kWm2]

ozone conc [wt][]CCβ

][0parameteradjustableα

iDiGi

Impact of Power Inductionp

350

400

wer

200

250

300

App

lied

Pow

Arr C 2Arr D +0

Arr E +45Arr F +7

Arr G +3

5 0

100

150

Frac

tion

of

1 2 3 4

ReferenceArr B unstable

Arr C -2

00

50

4Position (1inlet 4outlet)

Experimental Test Rigp g

Experimental Test Rigp g

Outer grounded electrode (left picture) and the dielectric covered inner electrodes (right) d e ect c cove ed e e ect odes ( g t)

Reference (Traditional) Arrangement

Inlet OutletGas flow direction

Optimized Arrangement

Inlet OutletGas flow direction

Intelligent Gap System (IGS)g p y ( )

Molecular Oxygen (O2) Ozone (O3)

O2 O3

yg ( 2) ( 3)

Particle Size SynthesisParticle Size SynthesisByBy--Products Cluster FormationProducts Cluster Formationyy

high diffusion and deposition to surfaces

low diffusion rate good transport

high sedimentation on the structurehigh sedimentation on the structure

Degreacutemont Technologies ndash OzoniaIntelligent Gap SystemIntelligent Gap System

G Vezzuacute JL Lopez A Freilich and K Becker Optimizationof Large-Scale Ozone Generators IEEE Transactions onPlasma Science Vol 37 No 6 p 890-896 (2009)

ConclusionsConclusionsConclusionsConclusionsFundamentals of ozone synthesis in a DBD plasmay p

ndash Highly filamented DBD discharges are best-suitedfor the production of ozone concentrations in therange of 6 to 14 wtrange of 6 to 14 wt

ndash The preferred characteristic of the microdischargesare Townsend-like at reduced electric fields Enaround 190 Townsend

ndash Detrimental side-effects induced by by-productscan be avoided by a proper design of the electrodecan be avoided by a proper design of the electrodearrangement The phenomenon is related to thediffusion rates of formed by-product clusters

ConclusionsConclusionsConclusionsConclusionsBenefits from DBD microplasma tailoring

ndash Reduced power consumption of up to 10 improvement

ndash Increased ozone concentrations of up to 14 now achievable

ndash Improved neutralization and conditioning of detrimental by-products

ndash Reduced system capital and operational cost

New technologies to improve ozone p

generatorg

HV Pulsed Power SwitchingHV Pulsed Power Switching

Microchannel Generation of Ozone

Channel ArrayChannel Array

Microchannel

330 microm 230 microm

Some Cap-DBD Devices Operating in Air

Increase of 60 of

Spacing 225 μmof 60 of plasma

No space

Cap‐DBD ozone generation

bull Ozone concentration is evaluated via Eco S d l UV 100 O A l (0 01Sensors model UV-100 Ozone Analyzer (001 ndash 900 ppm wiht an accuracy of plusmn2)

bull Three reactors 6 tubings 6rdquo with spacings of 0 μm 225 μm and 500 μm running at 3 kV μ μ μ g

SpacingOzone Concentration

3 kV rms 4 kV rms3 kV rms 4 kV rms

0 μm 660 ppm

225 μm 550 ppm

For a device of such small scale these ozone levels are promising

500 μm 380 ppm

J Mahoney W Zhu VS Johnson KH Becker and JL Lopez Electrical and optical emissionmeasurements of a capillary dielectric barrier discharge European Physics Journal D Vol 60 441-447(2010)

QuestionsQuestions

Thank YouFor more informationProf Jose L Lopez PhD

Thank YouFor more informationDepartment of Physics

Telephone (973) 761-9057Email joselopez1shuedu

Website wwwshueduacademicsartsciphysicsWebsite wwwshueduacademicsartsciphysics

Page 77: Dielectric Barrier Discharge (DBD) & Progress in Large ...bonitz/si12/talks/august_8/lopez_si12.pdf · Dielectric Barrier Discharge (DBD) & Progress in Large-Scale Ozone Generation

Plasma Chemistry in OzonizersPlasma Chemistry in Ozonizers

Dry Air O2 N2

e - e -

O N2 N O2

O3 NO

O2 N O2

O3

N

3

NO2

O2 O3

NO

N

NO2 O3

N2O

NO3 N

N2O4

NO2

NO2

N2O5

NO3

Primary electron-driven chemical reactions leading to the formation of N2O5 and N2O in a dry air plasma

Plasma emission diagnostics role of N2Plasma emission diagnostics role of N2

Dry Air O2 N2

e - e -

O N2 N O2

O3 NO

O2 N O2

O3

O

N

ON

NO2

O2O3

N

NO N

NO2 O3

N2O

NO3 N

N2O4

NO2

NO2

N2O5

NO3

ONbullWith N2 present ndash less oxygen atoms are formed However the difference in intensity is

very small

Modeling of plasma chemistry incl the NxOy chemistry up to N2O5 for different Oxygen Nitrogen mixtures varying power deposition scenarios

and initial ozone background concentrations (up to 15) previously done

The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation

The role of N2 must be related to its by-products reacting on the surface of the electrodeThe role of N2 must be related to its by-products reacting on the surface of the electrode

The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established

Ab 8 t f O

The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established

Ab 8 t f OAbove 8 wt of O3

1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)

Above 8 wt of O3

1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)case without pampp)

2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of the

case without pampp)

2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of thethem A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface

them A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface

The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation

Three possibilities have to be considered for the oxygen-fedozone generator

Three possibilities have to be considered for the oxygen-fedozone generatorozone generator

bull Excited N2 molecules lead to an increased O2 dissociation in

ozone generator

bull Excited N2 molecules lead to an increased O2 dissociation in2 2such case an increased efficiency is correlated to the N2admixture

2 2such case an increased efficiency is correlated to the N2admixture

bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial

bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial

bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2

bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2g p g 3 pp y 2g p g 3 pp y 2

Effect of methane on ozone efficiency and specific powerEffect of methane on ozone efficiency and specific power

Effect of Methane on Ozone Content in Outlet Gas and on Specific Power Pure O2

13 12

10

11

12

t 8

10

8

9

10

ne c

onte

nt w

t

6

8

ecifi

c po

wer

kW

hlb

5

6

7

Ozo

n

2

4 Spe

400E+00 20E+03 40E+03 60E+03 80E+03 10E+04 12E+04

Methane in feedgas ppm

0

Ozone content in the outlet gas Specif ic pow er of the ozone generatorg p p g

Effects of N2 and CH4Effects of N2 and CH4

Pi t f h t lli N O t tPicture of an amorphous-crystalline N2O5 structurecaptured at the Orlando Skylake water plant in 2006

Plasma Chemistry with CH4 Impurities

OxygenO2 N2

e - e -

CHO N2

NO2

O NO

O2 N O2 O3

NOH

CH4e-

O3 NO

NO2

O2O3NO N

NO2 O

NO2

NO2

N2ONO3

N

O3

NO2

NO

HNO3

N2O4

N2O5

NO2

NO3

N2O5

Effect of methane on the electrode surfaces

a) b)

Inlet Outlet Outlet

) d)

I l t I l t

c) d)

Electrode of the ozone generator afterseveral hours in CH8O2 and up to 2 wt of methane (a b c)

Inlet Inlet

three hours in CH8O2+traces of N2 and up to 1 wt of methane (d) Visible change of discharge character at about 13 length of electrode (a d)

Kinetics of CHx Conversion without N2

conversion by collisions

O2 + CHx 12wt O3 + CO2 +H2O

deposition vaporizationby sputtering

ibl b l 1000 CHreversible process below 1000ppm CH4

Effect of water on electrode surface with N2

Inlet

OutletOutlet

Electrode of the ozone generator after several hours in H OO N

Inlet

Electrode of the ozone generator after several hours in H2OO2N2

Effect of water on electrode surface

Long term effect (800 hrs) of H2OO2N2

Kinetics of CHx Conversion with N2

conversion by collisionsHNO3 formation

O2 + N2 +CHx 12wtO2 + CO2 +H2O + HNO3

deposition vaporizationby sputtering

H2O + HNO3

by sputtering

irreversible process above a N2 threshold () ltlt 1000ppm N2

sticky deposit

p 2 ( ) pp 2 any CH4 concentration (60ppm)

Plasma Chemistry with CH4 ImpuritiesPlasma Chemistry with CH4 Impurities4

bull Formation of NO and NO2 depends on O3 N2 and gas temperature Conclusion N2 admixture is the key factor

SummarySummaryyyThe mechanisms of formed NOx by-products follows the sameThe mechanisms of formed NOx by-products follows the sameprinciples as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentration

principles as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentrationozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)

ozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)g p ( g p )

The conversion of methane to OH and H2O is found to depend on

g p ( g p )

The conversion of methane to OH and H2O is found to depend ondissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)

dissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)discharge gap)discharge gap)

How do you optimize an ozone generatorg

Scientific ApproachScientific ApproachTheoretical Experimental

pppp

c [wt]

f [Hz]

c [wt]

f [Hz]

[kW]UUUβ1

1Cf4αPn

1iiminpeakimin

iiD

q [kWm2]q [kWm2]

150

180

][V]voltagepeakUpeak

[]cylinder perslicesofamountnsliceii

whereth

09 00

30

60

90

120

effic

ienc

y [

][0tdj t bl[F]sliceisdielectricofecapacitancC

[Hz]frequencyf[V]sliceivoltageminimumiUmin

thiD

th

10

28

46

64

82

39

107

176

244 power density

[kWm2]

ozone conc [wt][]CCβ

][0parameteradjustableα

iDiGi

Impact of Power Inductionp

350

400

wer

200

250

300

App

lied

Pow

Arr C 2Arr D +0

Arr E +45Arr F +7

Arr G +3

5 0

100

150

Frac

tion

of

1 2 3 4

ReferenceArr B unstable

Arr C -2

00

50

4Position (1inlet 4outlet)

Experimental Test Rigp g

Experimental Test Rigp g

Outer grounded electrode (left picture) and the dielectric covered inner electrodes (right) d e ect c cove ed e e ect odes ( g t)

Reference (Traditional) Arrangement

Inlet OutletGas flow direction

Optimized Arrangement

Inlet OutletGas flow direction

Intelligent Gap System (IGS)g p y ( )

Molecular Oxygen (O2) Ozone (O3)

O2 O3

yg ( 2) ( 3)

Particle Size SynthesisParticle Size SynthesisByBy--Products Cluster FormationProducts Cluster Formationyy

high diffusion and deposition to surfaces

low diffusion rate good transport

high sedimentation on the structurehigh sedimentation on the structure

Degreacutemont Technologies ndash OzoniaIntelligent Gap SystemIntelligent Gap System

G Vezzuacute JL Lopez A Freilich and K Becker Optimizationof Large-Scale Ozone Generators IEEE Transactions onPlasma Science Vol 37 No 6 p 890-896 (2009)

ConclusionsConclusionsConclusionsConclusionsFundamentals of ozone synthesis in a DBD plasmay p

ndash Highly filamented DBD discharges are best-suitedfor the production of ozone concentrations in therange of 6 to 14 wtrange of 6 to 14 wt

ndash The preferred characteristic of the microdischargesare Townsend-like at reduced electric fields Enaround 190 Townsend

ndash Detrimental side-effects induced by by-productscan be avoided by a proper design of the electrodecan be avoided by a proper design of the electrodearrangement The phenomenon is related to thediffusion rates of formed by-product clusters

ConclusionsConclusionsConclusionsConclusionsBenefits from DBD microplasma tailoring

ndash Reduced power consumption of up to 10 improvement

ndash Increased ozone concentrations of up to 14 now achievable

ndash Improved neutralization and conditioning of detrimental by-products

ndash Reduced system capital and operational cost

New technologies to improve ozone p

generatorg

HV Pulsed Power SwitchingHV Pulsed Power Switching

Microchannel Generation of Ozone

Channel ArrayChannel Array

Microchannel

330 microm 230 microm

Some Cap-DBD Devices Operating in Air

Increase of 60 of

Spacing 225 μmof 60 of plasma

No space

Cap‐DBD ozone generation

bull Ozone concentration is evaluated via Eco S d l UV 100 O A l (0 01Sensors model UV-100 Ozone Analyzer (001 ndash 900 ppm wiht an accuracy of plusmn2)

bull Three reactors 6 tubings 6rdquo with spacings of 0 μm 225 μm and 500 μm running at 3 kV μ μ μ g

SpacingOzone Concentration

3 kV rms 4 kV rms3 kV rms 4 kV rms

0 μm 660 ppm

225 μm 550 ppm

For a device of such small scale these ozone levels are promising

500 μm 380 ppm

J Mahoney W Zhu VS Johnson KH Becker and JL Lopez Electrical and optical emissionmeasurements of a capillary dielectric barrier discharge European Physics Journal D Vol 60 441-447(2010)

QuestionsQuestions

Thank YouFor more informationProf Jose L Lopez PhD

Thank YouFor more informationDepartment of Physics

Telephone (973) 761-9057Email joselopez1shuedu

Website wwwshueduacademicsartsciphysicsWebsite wwwshueduacademicsartsciphysics

Page 78: Dielectric Barrier Discharge (DBD) & Progress in Large ...bonitz/si12/talks/august_8/lopez_si12.pdf · Dielectric Barrier Discharge (DBD) & Progress in Large-Scale Ozone Generation

Plasma emission diagnostics role of N2Plasma emission diagnostics role of N2

Dry Air O2 N2

e - e -

O N2 N O2

O3 NO

O2 N O2

O3

O

N

ON

NO2

O2O3

N

NO N

NO2 O3

N2O

NO3 N

N2O4

NO2

NO2

N2O5

NO3

ONbullWith N2 present ndash less oxygen atoms are formed However the difference in intensity is

very small

Modeling of plasma chemistry incl the NxOy chemistry up to N2O5 for different Oxygen Nitrogen mixtures varying power deposition scenarios

and initial ozone background concentrations (up to 15) previously done

The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation

The role of N2 must be related to its by-products reacting on the surface of the electrodeThe role of N2 must be related to its by-products reacting on the surface of the electrode

The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established

Ab 8 t f O

The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established

Ab 8 t f OAbove 8 wt of O3

1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)

Above 8 wt of O3

1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)case without pampp)

2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of the

case without pampp)

2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of thethem A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface

them A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface

The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation

Three possibilities have to be considered for the oxygen-fedozone generator

Three possibilities have to be considered for the oxygen-fedozone generatorozone generator

bull Excited N2 molecules lead to an increased O2 dissociation in

ozone generator

bull Excited N2 molecules lead to an increased O2 dissociation in2 2such case an increased efficiency is correlated to the N2admixture

2 2such case an increased efficiency is correlated to the N2admixture

bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial

bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial

bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2

bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2g p g 3 pp y 2g p g 3 pp y 2

Effect of methane on ozone efficiency and specific powerEffect of methane on ozone efficiency and specific power

Effect of Methane on Ozone Content in Outlet Gas and on Specific Power Pure O2

13 12

10

11

12

t 8

10

8

9

10

ne c

onte

nt w

t

6

8

ecifi

c po

wer

kW

hlb

5

6

7

Ozo

n

2

4 Spe

400E+00 20E+03 40E+03 60E+03 80E+03 10E+04 12E+04

Methane in feedgas ppm

0

Ozone content in the outlet gas Specif ic pow er of the ozone generatorg p p g

Effects of N2 and CH4Effects of N2 and CH4

Pi t f h t lli N O t tPicture of an amorphous-crystalline N2O5 structurecaptured at the Orlando Skylake water plant in 2006

Plasma Chemistry with CH4 Impurities

OxygenO2 N2

e - e -

CHO N2

NO2

O NO

O2 N O2 O3

NOH

CH4e-

O3 NO

NO2

O2O3NO N

NO2 O

NO2

NO2

N2ONO3

N

O3

NO2

NO

HNO3

N2O4

N2O5

NO2

NO3

N2O5

Effect of methane on the electrode surfaces

a) b)

Inlet Outlet Outlet

) d)

I l t I l t

c) d)

Electrode of the ozone generator afterseveral hours in CH8O2 and up to 2 wt of methane (a b c)

Inlet Inlet

three hours in CH8O2+traces of N2 and up to 1 wt of methane (d) Visible change of discharge character at about 13 length of electrode (a d)

Kinetics of CHx Conversion without N2

conversion by collisions

O2 + CHx 12wt O3 + CO2 +H2O

deposition vaporizationby sputtering

ibl b l 1000 CHreversible process below 1000ppm CH4

Effect of water on electrode surface with N2

Inlet

OutletOutlet

Electrode of the ozone generator after several hours in H OO N

Inlet

Electrode of the ozone generator after several hours in H2OO2N2

Effect of water on electrode surface

Long term effect (800 hrs) of H2OO2N2

Kinetics of CHx Conversion with N2

conversion by collisionsHNO3 formation

O2 + N2 +CHx 12wtO2 + CO2 +H2O + HNO3

deposition vaporizationby sputtering

H2O + HNO3

by sputtering

irreversible process above a N2 threshold () ltlt 1000ppm N2

sticky deposit

p 2 ( ) pp 2 any CH4 concentration (60ppm)

Plasma Chemistry with CH4 ImpuritiesPlasma Chemistry with CH4 Impurities4

bull Formation of NO and NO2 depends on O3 N2 and gas temperature Conclusion N2 admixture is the key factor

SummarySummaryyyThe mechanisms of formed NOx by-products follows the sameThe mechanisms of formed NOx by-products follows the sameprinciples as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentration

principles as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentrationozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)

ozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)g p ( g p )

The conversion of methane to OH and H2O is found to depend on

g p ( g p )

The conversion of methane to OH and H2O is found to depend ondissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)

dissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)discharge gap)discharge gap)

How do you optimize an ozone generatorg

Scientific ApproachScientific ApproachTheoretical Experimental

pppp

c [wt]

f [Hz]

c [wt]

f [Hz]

[kW]UUUβ1

1Cf4αPn

1iiminpeakimin

iiD

q [kWm2]q [kWm2]

150

180

][V]voltagepeakUpeak

[]cylinder perslicesofamountnsliceii

whereth

09 00

30

60

90

120

effic

ienc

y [

][0tdj t bl[F]sliceisdielectricofecapacitancC

[Hz]frequencyf[V]sliceivoltageminimumiUmin

thiD

th

10

28

46

64

82

39

107

176

244 power density

[kWm2]

ozone conc [wt][]CCβ

][0parameteradjustableα

iDiGi

Impact of Power Inductionp

350

400

wer

200

250

300

App

lied

Pow

Arr C 2Arr D +0

Arr E +45Arr F +7

Arr G +3

5 0

100

150

Frac

tion

of

1 2 3 4

ReferenceArr B unstable

Arr C -2

00

50

4Position (1inlet 4outlet)

Experimental Test Rigp g

Experimental Test Rigp g

Outer grounded electrode (left picture) and the dielectric covered inner electrodes (right) d e ect c cove ed e e ect odes ( g t)

Reference (Traditional) Arrangement

Inlet OutletGas flow direction

Optimized Arrangement

Inlet OutletGas flow direction

Intelligent Gap System (IGS)g p y ( )

Molecular Oxygen (O2) Ozone (O3)

O2 O3

yg ( 2) ( 3)

Particle Size SynthesisParticle Size SynthesisByBy--Products Cluster FormationProducts Cluster Formationyy

high diffusion and deposition to surfaces

low diffusion rate good transport

high sedimentation on the structurehigh sedimentation on the structure

Degreacutemont Technologies ndash OzoniaIntelligent Gap SystemIntelligent Gap System

G Vezzuacute JL Lopez A Freilich and K Becker Optimizationof Large-Scale Ozone Generators IEEE Transactions onPlasma Science Vol 37 No 6 p 890-896 (2009)

ConclusionsConclusionsConclusionsConclusionsFundamentals of ozone synthesis in a DBD plasmay p

ndash Highly filamented DBD discharges are best-suitedfor the production of ozone concentrations in therange of 6 to 14 wtrange of 6 to 14 wt

ndash The preferred characteristic of the microdischargesare Townsend-like at reduced electric fields Enaround 190 Townsend

ndash Detrimental side-effects induced by by-productscan be avoided by a proper design of the electrodecan be avoided by a proper design of the electrodearrangement The phenomenon is related to thediffusion rates of formed by-product clusters

ConclusionsConclusionsConclusionsConclusionsBenefits from DBD microplasma tailoring

ndash Reduced power consumption of up to 10 improvement

ndash Increased ozone concentrations of up to 14 now achievable

ndash Improved neutralization and conditioning of detrimental by-products

ndash Reduced system capital and operational cost

New technologies to improve ozone p

generatorg

HV Pulsed Power SwitchingHV Pulsed Power Switching

Microchannel Generation of Ozone

Channel ArrayChannel Array

Microchannel

330 microm 230 microm

Some Cap-DBD Devices Operating in Air

Increase of 60 of

Spacing 225 μmof 60 of plasma

No space

Cap‐DBD ozone generation

bull Ozone concentration is evaluated via Eco S d l UV 100 O A l (0 01Sensors model UV-100 Ozone Analyzer (001 ndash 900 ppm wiht an accuracy of plusmn2)

bull Three reactors 6 tubings 6rdquo with spacings of 0 μm 225 μm and 500 μm running at 3 kV μ μ μ g

SpacingOzone Concentration

3 kV rms 4 kV rms3 kV rms 4 kV rms

0 μm 660 ppm

225 μm 550 ppm

For a device of such small scale these ozone levels are promising

500 μm 380 ppm

J Mahoney W Zhu VS Johnson KH Becker and JL Lopez Electrical and optical emissionmeasurements of a capillary dielectric barrier discharge European Physics Journal D Vol 60 441-447(2010)

QuestionsQuestions

Thank YouFor more informationProf Jose L Lopez PhD

Thank YouFor more informationDepartment of Physics

Telephone (973) 761-9057Email joselopez1shuedu

Website wwwshueduacademicsartsciphysicsWebsite wwwshueduacademicsartsciphysics

Page 79: Dielectric Barrier Discharge (DBD) & Progress in Large ...bonitz/si12/talks/august_8/lopez_si12.pdf · Dielectric Barrier Discharge (DBD) & Progress in Large-Scale Ozone Generation

The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation

The role of N2 must be related to its by-products reacting on the surface of the electrodeThe role of N2 must be related to its by-products reacting on the surface of the electrode

The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established

Ab 8 t f O

The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established

Ab 8 t f OAbove 8 wt of O3

1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)

Above 8 wt of O3

1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)case without pampp)

2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of the

case without pampp)

2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of thethem A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface

them A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface

The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation

Three possibilities have to be considered for the oxygen-fedozone generator

Three possibilities have to be considered for the oxygen-fedozone generatorozone generator

bull Excited N2 molecules lead to an increased O2 dissociation in

ozone generator

bull Excited N2 molecules lead to an increased O2 dissociation in2 2such case an increased efficiency is correlated to the N2admixture

2 2such case an increased efficiency is correlated to the N2admixture

bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial

bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial

bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2

bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2g p g 3 pp y 2g p g 3 pp y 2

Effect of methane on ozone efficiency and specific powerEffect of methane on ozone efficiency and specific power

Effect of Methane on Ozone Content in Outlet Gas and on Specific Power Pure O2

13 12

10

11

12

t 8

10

8

9

10

ne c

onte

nt w

t

6

8

ecifi

c po

wer

kW

hlb

5

6

7

Ozo

n

2

4 Spe

400E+00 20E+03 40E+03 60E+03 80E+03 10E+04 12E+04

Methane in feedgas ppm

0

Ozone content in the outlet gas Specif ic pow er of the ozone generatorg p p g

Effects of N2 and CH4Effects of N2 and CH4

Pi t f h t lli N O t tPicture of an amorphous-crystalline N2O5 structurecaptured at the Orlando Skylake water plant in 2006

Plasma Chemistry with CH4 Impurities

OxygenO2 N2

e - e -

CHO N2

NO2

O NO

O2 N O2 O3

NOH

CH4e-

O3 NO

NO2

O2O3NO N

NO2 O

NO2

NO2

N2ONO3

N

O3

NO2

NO

HNO3

N2O4

N2O5

NO2

NO3

N2O5

Effect of methane on the electrode surfaces

a) b)

Inlet Outlet Outlet

) d)

I l t I l t

c) d)

Electrode of the ozone generator afterseveral hours in CH8O2 and up to 2 wt of methane (a b c)

Inlet Inlet

three hours in CH8O2+traces of N2 and up to 1 wt of methane (d) Visible change of discharge character at about 13 length of electrode (a d)

Kinetics of CHx Conversion without N2

conversion by collisions

O2 + CHx 12wt O3 + CO2 +H2O

deposition vaporizationby sputtering

ibl b l 1000 CHreversible process below 1000ppm CH4

Effect of water on electrode surface with N2

Inlet

OutletOutlet

Electrode of the ozone generator after several hours in H OO N

Inlet

Electrode of the ozone generator after several hours in H2OO2N2

Effect of water on electrode surface

Long term effect (800 hrs) of H2OO2N2

Kinetics of CHx Conversion with N2

conversion by collisionsHNO3 formation

O2 + N2 +CHx 12wtO2 + CO2 +H2O + HNO3

deposition vaporizationby sputtering

H2O + HNO3

by sputtering

irreversible process above a N2 threshold () ltlt 1000ppm N2

sticky deposit

p 2 ( ) pp 2 any CH4 concentration (60ppm)

Plasma Chemistry with CH4 ImpuritiesPlasma Chemistry with CH4 Impurities4

bull Formation of NO and NO2 depends on O3 N2 and gas temperature Conclusion N2 admixture is the key factor

SummarySummaryyyThe mechanisms of formed NOx by-products follows the sameThe mechanisms of formed NOx by-products follows the sameprinciples as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentration

principles as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentrationozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)

ozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)g p ( g p )

The conversion of methane to OH and H2O is found to depend on

g p ( g p )

The conversion of methane to OH and H2O is found to depend ondissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)

dissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)discharge gap)discharge gap)

How do you optimize an ozone generatorg

Scientific ApproachScientific ApproachTheoretical Experimental

pppp

c [wt]

f [Hz]

c [wt]

f [Hz]

[kW]UUUβ1

1Cf4αPn

1iiminpeakimin

iiD

q [kWm2]q [kWm2]

150

180

][V]voltagepeakUpeak

[]cylinder perslicesofamountnsliceii

whereth

09 00

30

60

90

120

effic

ienc

y [

][0tdj t bl[F]sliceisdielectricofecapacitancC

[Hz]frequencyf[V]sliceivoltageminimumiUmin

thiD

th

10

28

46

64

82

39

107

176

244 power density

[kWm2]

ozone conc [wt][]CCβ

][0parameteradjustableα

iDiGi

Impact of Power Inductionp

350

400

wer

200

250

300

App

lied

Pow

Arr C 2Arr D +0

Arr E +45Arr F +7

Arr G +3

5 0

100

150

Frac

tion

of

1 2 3 4

ReferenceArr B unstable

Arr C -2

00

50

4Position (1inlet 4outlet)

Experimental Test Rigp g

Experimental Test Rigp g

Outer grounded electrode (left picture) and the dielectric covered inner electrodes (right) d e ect c cove ed e e ect odes ( g t)

Reference (Traditional) Arrangement

Inlet OutletGas flow direction

Optimized Arrangement

Inlet OutletGas flow direction

Intelligent Gap System (IGS)g p y ( )

Molecular Oxygen (O2) Ozone (O3)

O2 O3

yg ( 2) ( 3)

Particle Size SynthesisParticle Size SynthesisByBy--Products Cluster FormationProducts Cluster Formationyy

high diffusion and deposition to surfaces

low diffusion rate good transport

high sedimentation on the structurehigh sedimentation on the structure

Degreacutemont Technologies ndash OzoniaIntelligent Gap SystemIntelligent Gap System

G Vezzuacute JL Lopez A Freilich and K Becker Optimizationof Large-Scale Ozone Generators IEEE Transactions onPlasma Science Vol 37 No 6 p 890-896 (2009)

ConclusionsConclusionsConclusionsConclusionsFundamentals of ozone synthesis in a DBD plasmay p

ndash Highly filamented DBD discharges are best-suitedfor the production of ozone concentrations in therange of 6 to 14 wtrange of 6 to 14 wt

ndash The preferred characteristic of the microdischargesare Townsend-like at reduced electric fields Enaround 190 Townsend

ndash Detrimental side-effects induced by by-productscan be avoided by a proper design of the electrodecan be avoided by a proper design of the electrodearrangement The phenomenon is related to thediffusion rates of formed by-product clusters

ConclusionsConclusionsConclusionsConclusionsBenefits from DBD microplasma tailoring

ndash Reduced power consumption of up to 10 improvement

ndash Increased ozone concentrations of up to 14 now achievable

ndash Improved neutralization and conditioning of detrimental by-products

ndash Reduced system capital and operational cost

New technologies to improve ozone p

generatorg

HV Pulsed Power SwitchingHV Pulsed Power Switching

Microchannel Generation of Ozone

Channel ArrayChannel Array

Microchannel

330 microm 230 microm

Some Cap-DBD Devices Operating in Air

Increase of 60 of

Spacing 225 μmof 60 of plasma

No space

Cap‐DBD ozone generation

bull Ozone concentration is evaluated via Eco S d l UV 100 O A l (0 01Sensors model UV-100 Ozone Analyzer (001 ndash 900 ppm wiht an accuracy of plusmn2)

bull Three reactors 6 tubings 6rdquo with spacings of 0 μm 225 μm and 500 μm running at 3 kV μ μ μ g

SpacingOzone Concentration

3 kV rms 4 kV rms3 kV rms 4 kV rms

0 μm 660 ppm

225 μm 550 ppm

For a device of such small scale these ozone levels are promising

500 μm 380 ppm

J Mahoney W Zhu VS Johnson KH Becker and JL Lopez Electrical and optical emissionmeasurements of a capillary dielectric barrier discharge European Physics Journal D Vol 60 441-447(2010)

QuestionsQuestions

Thank YouFor more informationProf Jose L Lopez PhD

Thank YouFor more informationDepartment of Physics

Telephone (973) 761-9057Email joselopez1shuedu

Website wwwshueduacademicsartsciphysicsWebsite wwwshueduacademicsartsciphysics

Page 80: Dielectric Barrier Discharge (DBD) & Progress in Large ...bonitz/si12/talks/august_8/lopez_si12.pdf · Dielectric Barrier Discharge (DBD) & Progress in Large-Scale Ozone Generation

The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation

Three possibilities have to be considered for the oxygen-fedozone generator

Three possibilities have to be considered for the oxygen-fedozone generatorozone generator

bull Excited N2 molecules lead to an increased O2 dissociation in

ozone generator

bull Excited N2 molecules lead to an increased O2 dissociation in2 2such case an increased efficiency is correlated to the N2admixture

2 2such case an increased efficiency is correlated to the N2admixture

bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial

bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial

bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2

bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2g p g 3 pp y 2g p g 3 pp y 2

Effect of methane on ozone efficiency and specific powerEffect of methane on ozone efficiency and specific power

Effect of Methane on Ozone Content in Outlet Gas and on Specific Power Pure O2

13 12

10

11

12

t 8

10

8

9

10

ne c

onte

nt w

t

6

8

ecifi

c po

wer

kW

hlb

5

6

7

Ozo

n

2

4 Spe

400E+00 20E+03 40E+03 60E+03 80E+03 10E+04 12E+04

Methane in feedgas ppm

0

Ozone content in the outlet gas Specif ic pow er of the ozone generatorg p p g

Effects of N2 and CH4Effects of N2 and CH4

Pi t f h t lli N O t tPicture of an amorphous-crystalline N2O5 structurecaptured at the Orlando Skylake water plant in 2006

Plasma Chemistry with CH4 Impurities

OxygenO2 N2

e - e -

CHO N2

NO2

O NO

O2 N O2 O3

NOH

CH4e-

O3 NO

NO2

O2O3NO N

NO2 O

NO2

NO2

N2ONO3

N

O3

NO2

NO

HNO3

N2O4

N2O5

NO2

NO3

N2O5

Effect of methane on the electrode surfaces

a) b)

Inlet Outlet Outlet

) d)

I l t I l t

c) d)

Electrode of the ozone generator afterseveral hours in CH8O2 and up to 2 wt of methane (a b c)

Inlet Inlet

three hours in CH8O2+traces of N2 and up to 1 wt of methane (d) Visible change of discharge character at about 13 length of electrode (a d)

Kinetics of CHx Conversion without N2

conversion by collisions

O2 + CHx 12wt O3 + CO2 +H2O

deposition vaporizationby sputtering

ibl b l 1000 CHreversible process below 1000ppm CH4

Effect of water on electrode surface with N2

Inlet

OutletOutlet

Electrode of the ozone generator after several hours in H OO N

Inlet

Electrode of the ozone generator after several hours in H2OO2N2

Effect of water on electrode surface

Long term effect (800 hrs) of H2OO2N2

Kinetics of CHx Conversion with N2

conversion by collisionsHNO3 formation

O2 + N2 +CHx 12wtO2 + CO2 +H2O + HNO3

deposition vaporizationby sputtering

H2O + HNO3

by sputtering

irreversible process above a N2 threshold () ltlt 1000ppm N2

sticky deposit

p 2 ( ) pp 2 any CH4 concentration (60ppm)

Plasma Chemistry with CH4 ImpuritiesPlasma Chemistry with CH4 Impurities4

bull Formation of NO and NO2 depends on O3 N2 and gas temperature Conclusion N2 admixture is the key factor

SummarySummaryyyThe mechanisms of formed NOx by-products follows the sameThe mechanisms of formed NOx by-products follows the sameprinciples as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentration

principles as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentrationozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)

ozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)g p ( g p )

The conversion of methane to OH and H2O is found to depend on

g p ( g p )

The conversion of methane to OH and H2O is found to depend ondissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)

dissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)discharge gap)discharge gap)

How do you optimize an ozone generatorg

Scientific ApproachScientific ApproachTheoretical Experimental

pppp

c [wt]

f [Hz]

c [wt]

f [Hz]

[kW]UUUβ1

1Cf4αPn

1iiminpeakimin

iiD

q [kWm2]q [kWm2]

150

180

][V]voltagepeakUpeak

[]cylinder perslicesofamountnsliceii

whereth

09 00

30

60

90

120

effic

ienc

y [

][0tdj t bl[F]sliceisdielectricofecapacitancC

[Hz]frequencyf[V]sliceivoltageminimumiUmin

thiD

th

10

28

46

64

82

39

107

176

244 power density

[kWm2]

ozone conc [wt][]CCβ

][0parameteradjustableα

iDiGi

Impact of Power Inductionp

350

400

wer

200

250

300

App

lied

Pow

Arr C 2Arr D +0

Arr E +45Arr F +7

Arr G +3

5 0

100

150

Frac

tion

of

1 2 3 4

ReferenceArr B unstable

Arr C -2

00

50

4Position (1inlet 4outlet)

Experimental Test Rigp g

Experimental Test Rigp g

Outer grounded electrode (left picture) and the dielectric covered inner electrodes (right) d e ect c cove ed e e ect odes ( g t)

Reference (Traditional) Arrangement

Inlet OutletGas flow direction

Optimized Arrangement

Inlet OutletGas flow direction

Intelligent Gap System (IGS)g p y ( )

Molecular Oxygen (O2) Ozone (O3)

O2 O3

yg ( 2) ( 3)

Particle Size SynthesisParticle Size SynthesisByBy--Products Cluster FormationProducts Cluster Formationyy

high diffusion and deposition to surfaces

low diffusion rate good transport

high sedimentation on the structurehigh sedimentation on the structure

Degreacutemont Technologies ndash OzoniaIntelligent Gap SystemIntelligent Gap System

G Vezzuacute JL Lopez A Freilich and K Becker Optimizationof Large-Scale Ozone Generators IEEE Transactions onPlasma Science Vol 37 No 6 p 890-896 (2009)

ConclusionsConclusionsConclusionsConclusionsFundamentals of ozone synthesis in a DBD plasmay p

ndash Highly filamented DBD discharges are best-suitedfor the production of ozone concentrations in therange of 6 to 14 wtrange of 6 to 14 wt

ndash The preferred characteristic of the microdischargesare Townsend-like at reduced electric fields Enaround 190 Townsend

ndash Detrimental side-effects induced by by-productscan be avoided by a proper design of the electrodecan be avoided by a proper design of the electrodearrangement The phenomenon is related to thediffusion rates of formed by-product clusters

ConclusionsConclusionsConclusionsConclusionsBenefits from DBD microplasma tailoring

ndash Reduced power consumption of up to 10 improvement

ndash Increased ozone concentrations of up to 14 now achievable

ndash Improved neutralization and conditioning of detrimental by-products

ndash Reduced system capital and operational cost

New technologies to improve ozone p

generatorg

HV Pulsed Power SwitchingHV Pulsed Power Switching

Microchannel Generation of Ozone

Channel ArrayChannel Array

Microchannel

330 microm 230 microm

Some Cap-DBD Devices Operating in Air

Increase of 60 of

Spacing 225 μmof 60 of plasma

No space

Cap‐DBD ozone generation

bull Ozone concentration is evaluated via Eco S d l UV 100 O A l (0 01Sensors model UV-100 Ozone Analyzer (001 ndash 900 ppm wiht an accuracy of plusmn2)

bull Three reactors 6 tubings 6rdquo with spacings of 0 μm 225 μm and 500 μm running at 3 kV μ μ μ g

SpacingOzone Concentration

3 kV rms 4 kV rms3 kV rms 4 kV rms

0 μm 660 ppm

225 μm 550 ppm

For a device of such small scale these ozone levels are promising

500 μm 380 ppm

J Mahoney W Zhu VS Johnson KH Becker and JL Lopez Electrical and optical emissionmeasurements of a capillary dielectric barrier discharge European Physics Journal D Vol 60 441-447(2010)

QuestionsQuestions

Thank YouFor more informationProf Jose L Lopez PhD

Thank YouFor more informationDepartment of Physics

Telephone (973) 761-9057Email joselopez1shuedu

Website wwwshueduacademicsartsciphysicsWebsite wwwshueduacademicsartsciphysics

Page 81: Dielectric Barrier Discharge (DBD) & Progress in Large ...bonitz/si12/talks/august_8/lopez_si12.pdf · Dielectric Barrier Discharge (DBD) & Progress in Large-Scale Ozone Generation

Effect of methane on ozone efficiency and specific powerEffect of methane on ozone efficiency and specific power

Effect of Methane on Ozone Content in Outlet Gas and on Specific Power Pure O2

13 12

10

11

12

t 8

10

8

9

10

ne c

onte

nt w

t

6

8

ecifi

c po

wer

kW

hlb

5

6

7

Ozo

n

2

4 Spe

400E+00 20E+03 40E+03 60E+03 80E+03 10E+04 12E+04

Methane in feedgas ppm

0

Ozone content in the outlet gas Specif ic pow er of the ozone generatorg p p g

Effects of N2 and CH4Effects of N2 and CH4

Pi t f h t lli N O t tPicture of an amorphous-crystalline N2O5 structurecaptured at the Orlando Skylake water plant in 2006

Plasma Chemistry with CH4 Impurities

OxygenO2 N2

e - e -

CHO N2

NO2

O NO

O2 N O2 O3

NOH

CH4e-

O3 NO

NO2

O2O3NO N

NO2 O

NO2

NO2

N2ONO3

N

O3

NO2

NO

HNO3

N2O4

N2O5

NO2

NO3

N2O5

Effect of methane on the electrode surfaces

a) b)

Inlet Outlet Outlet

) d)

I l t I l t

c) d)

Electrode of the ozone generator afterseveral hours in CH8O2 and up to 2 wt of methane (a b c)

Inlet Inlet

three hours in CH8O2+traces of N2 and up to 1 wt of methane (d) Visible change of discharge character at about 13 length of electrode (a d)

Kinetics of CHx Conversion without N2

conversion by collisions

O2 + CHx 12wt O3 + CO2 +H2O

deposition vaporizationby sputtering

ibl b l 1000 CHreversible process below 1000ppm CH4

Effect of water on electrode surface with N2

Inlet

OutletOutlet

Electrode of the ozone generator after several hours in H OO N

Inlet

Electrode of the ozone generator after several hours in H2OO2N2

Effect of water on electrode surface

Long term effect (800 hrs) of H2OO2N2

Kinetics of CHx Conversion with N2

conversion by collisionsHNO3 formation

O2 + N2 +CHx 12wtO2 + CO2 +H2O + HNO3

deposition vaporizationby sputtering

H2O + HNO3

by sputtering

irreversible process above a N2 threshold () ltlt 1000ppm N2

sticky deposit

p 2 ( ) pp 2 any CH4 concentration (60ppm)

Plasma Chemistry with CH4 ImpuritiesPlasma Chemistry with CH4 Impurities4

bull Formation of NO and NO2 depends on O3 N2 and gas temperature Conclusion N2 admixture is the key factor

SummarySummaryyyThe mechanisms of formed NOx by-products follows the sameThe mechanisms of formed NOx by-products follows the sameprinciples as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentration

principles as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentrationozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)

ozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)g p ( g p )

The conversion of methane to OH and H2O is found to depend on

g p ( g p )

The conversion of methane to OH and H2O is found to depend ondissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)

dissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)discharge gap)discharge gap)

How do you optimize an ozone generatorg

Scientific ApproachScientific ApproachTheoretical Experimental

pppp

c [wt]

f [Hz]

c [wt]

f [Hz]

[kW]UUUβ1

1Cf4αPn

1iiminpeakimin

iiD

q [kWm2]q [kWm2]

150

180

][V]voltagepeakUpeak

[]cylinder perslicesofamountnsliceii

whereth

09 00

30

60

90

120

effic

ienc

y [

][0tdj t bl[F]sliceisdielectricofecapacitancC

[Hz]frequencyf[V]sliceivoltageminimumiUmin

thiD

th

10

28

46

64

82

39

107

176

244 power density

[kWm2]

ozone conc [wt][]CCβ

][0parameteradjustableα

iDiGi

Impact of Power Inductionp

350

400

wer

200

250

300

App

lied

Pow

Arr C 2Arr D +0

Arr E +45Arr F +7

Arr G +3

5 0

100

150

Frac

tion

of

1 2 3 4

ReferenceArr B unstable

Arr C -2

00

50

4Position (1inlet 4outlet)

Experimental Test Rigp g

Experimental Test Rigp g

Outer grounded electrode (left picture) and the dielectric covered inner electrodes (right) d e ect c cove ed e e ect odes ( g t)

Reference (Traditional) Arrangement

Inlet OutletGas flow direction

Optimized Arrangement

Inlet OutletGas flow direction

Intelligent Gap System (IGS)g p y ( )

Molecular Oxygen (O2) Ozone (O3)

O2 O3

yg ( 2) ( 3)

Particle Size SynthesisParticle Size SynthesisByBy--Products Cluster FormationProducts Cluster Formationyy

high diffusion and deposition to surfaces

low diffusion rate good transport

high sedimentation on the structurehigh sedimentation on the structure

Degreacutemont Technologies ndash OzoniaIntelligent Gap SystemIntelligent Gap System

G Vezzuacute JL Lopez A Freilich and K Becker Optimizationof Large-Scale Ozone Generators IEEE Transactions onPlasma Science Vol 37 No 6 p 890-896 (2009)

ConclusionsConclusionsConclusionsConclusionsFundamentals of ozone synthesis in a DBD plasmay p

ndash Highly filamented DBD discharges are best-suitedfor the production of ozone concentrations in therange of 6 to 14 wtrange of 6 to 14 wt

ndash The preferred characteristic of the microdischargesare Townsend-like at reduced electric fields Enaround 190 Townsend

ndash Detrimental side-effects induced by by-productscan be avoided by a proper design of the electrodecan be avoided by a proper design of the electrodearrangement The phenomenon is related to thediffusion rates of formed by-product clusters

ConclusionsConclusionsConclusionsConclusionsBenefits from DBD microplasma tailoring

ndash Reduced power consumption of up to 10 improvement

ndash Increased ozone concentrations of up to 14 now achievable

ndash Improved neutralization and conditioning of detrimental by-products

ndash Reduced system capital and operational cost

New technologies to improve ozone p

generatorg

HV Pulsed Power SwitchingHV Pulsed Power Switching

Microchannel Generation of Ozone

Channel ArrayChannel Array

Microchannel

330 microm 230 microm

Some Cap-DBD Devices Operating in Air

Increase of 60 of

Spacing 225 μmof 60 of plasma

No space

Cap‐DBD ozone generation

bull Ozone concentration is evaluated via Eco S d l UV 100 O A l (0 01Sensors model UV-100 Ozone Analyzer (001 ndash 900 ppm wiht an accuracy of plusmn2)

bull Three reactors 6 tubings 6rdquo with spacings of 0 μm 225 μm and 500 μm running at 3 kV μ μ μ g

SpacingOzone Concentration

3 kV rms 4 kV rms3 kV rms 4 kV rms

0 μm 660 ppm

225 μm 550 ppm

For a device of such small scale these ozone levels are promising

500 μm 380 ppm

J Mahoney W Zhu VS Johnson KH Becker and JL Lopez Electrical and optical emissionmeasurements of a capillary dielectric barrier discharge European Physics Journal D Vol 60 441-447(2010)

QuestionsQuestions

Thank YouFor more informationProf Jose L Lopez PhD

Thank YouFor more informationDepartment of Physics

Telephone (973) 761-9057Email joselopez1shuedu

Website wwwshueduacademicsartsciphysicsWebsite wwwshueduacademicsartsciphysics

Page 82: Dielectric Barrier Discharge (DBD) & Progress in Large ...bonitz/si12/talks/august_8/lopez_si12.pdf · Dielectric Barrier Discharge (DBD) & Progress in Large-Scale Ozone Generation

Effects of N2 and CH4Effects of N2 and CH4

Pi t f h t lli N O t tPicture of an amorphous-crystalline N2O5 structurecaptured at the Orlando Skylake water plant in 2006

Plasma Chemistry with CH4 Impurities

OxygenO2 N2

e - e -

CHO N2

NO2

O NO

O2 N O2 O3

NOH

CH4e-

O3 NO

NO2

O2O3NO N

NO2 O

NO2

NO2

N2ONO3

N

O3

NO2

NO

HNO3

N2O4

N2O5

NO2

NO3

N2O5

Effect of methane on the electrode surfaces

a) b)

Inlet Outlet Outlet

) d)

I l t I l t

c) d)

Electrode of the ozone generator afterseveral hours in CH8O2 and up to 2 wt of methane (a b c)

Inlet Inlet

three hours in CH8O2+traces of N2 and up to 1 wt of methane (d) Visible change of discharge character at about 13 length of electrode (a d)

Kinetics of CHx Conversion without N2

conversion by collisions

O2 + CHx 12wt O3 + CO2 +H2O

deposition vaporizationby sputtering

ibl b l 1000 CHreversible process below 1000ppm CH4

Effect of water on electrode surface with N2

Inlet

OutletOutlet

Electrode of the ozone generator after several hours in H OO N

Inlet

Electrode of the ozone generator after several hours in H2OO2N2

Effect of water on electrode surface

Long term effect (800 hrs) of H2OO2N2

Kinetics of CHx Conversion with N2

conversion by collisionsHNO3 formation

O2 + N2 +CHx 12wtO2 + CO2 +H2O + HNO3

deposition vaporizationby sputtering

H2O + HNO3

by sputtering

irreversible process above a N2 threshold () ltlt 1000ppm N2

sticky deposit

p 2 ( ) pp 2 any CH4 concentration (60ppm)

Plasma Chemistry with CH4 ImpuritiesPlasma Chemistry with CH4 Impurities4

bull Formation of NO and NO2 depends on O3 N2 and gas temperature Conclusion N2 admixture is the key factor

SummarySummaryyyThe mechanisms of formed NOx by-products follows the sameThe mechanisms of formed NOx by-products follows the sameprinciples as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentration

principles as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentrationozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)

ozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)g p ( g p )

The conversion of methane to OH and H2O is found to depend on

g p ( g p )

The conversion of methane to OH and H2O is found to depend ondissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)

dissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)discharge gap)discharge gap)

How do you optimize an ozone generatorg

Scientific ApproachScientific ApproachTheoretical Experimental

pppp

c [wt]

f [Hz]

c [wt]

f [Hz]

[kW]UUUβ1

1Cf4αPn

1iiminpeakimin

iiD

q [kWm2]q [kWm2]

150

180

][V]voltagepeakUpeak

[]cylinder perslicesofamountnsliceii

whereth

09 00

30

60

90

120

effic

ienc

y [

][0tdj t bl[F]sliceisdielectricofecapacitancC

[Hz]frequencyf[V]sliceivoltageminimumiUmin

thiD

th

10

28

46

64

82

39

107

176

244 power density

[kWm2]

ozone conc [wt][]CCβ

][0parameteradjustableα

iDiGi

Impact of Power Inductionp

350

400

wer

200

250

300

App

lied

Pow

Arr C 2Arr D +0

Arr E +45Arr F +7

Arr G +3

5 0

100

150

Frac

tion

of

1 2 3 4

ReferenceArr B unstable

Arr C -2

00

50

4Position (1inlet 4outlet)

Experimental Test Rigp g

Experimental Test Rigp g

Outer grounded electrode (left picture) and the dielectric covered inner electrodes (right) d e ect c cove ed e e ect odes ( g t)

Reference (Traditional) Arrangement

Inlet OutletGas flow direction

Optimized Arrangement

Inlet OutletGas flow direction

Intelligent Gap System (IGS)g p y ( )

Molecular Oxygen (O2) Ozone (O3)

O2 O3

yg ( 2) ( 3)

Particle Size SynthesisParticle Size SynthesisByBy--Products Cluster FormationProducts Cluster Formationyy

high diffusion and deposition to surfaces

low diffusion rate good transport

high sedimentation on the structurehigh sedimentation on the structure

Degreacutemont Technologies ndash OzoniaIntelligent Gap SystemIntelligent Gap System

G Vezzuacute JL Lopez A Freilich and K Becker Optimizationof Large-Scale Ozone Generators IEEE Transactions onPlasma Science Vol 37 No 6 p 890-896 (2009)

ConclusionsConclusionsConclusionsConclusionsFundamentals of ozone synthesis in a DBD plasmay p

ndash Highly filamented DBD discharges are best-suitedfor the production of ozone concentrations in therange of 6 to 14 wtrange of 6 to 14 wt

ndash The preferred characteristic of the microdischargesare Townsend-like at reduced electric fields Enaround 190 Townsend

ndash Detrimental side-effects induced by by-productscan be avoided by a proper design of the electrodecan be avoided by a proper design of the electrodearrangement The phenomenon is related to thediffusion rates of formed by-product clusters

ConclusionsConclusionsConclusionsConclusionsBenefits from DBD microplasma tailoring

ndash Reduced power consumption of up to 10 improvement

ndash Increased ozone concentrations of up to 14 now achievable

ndash Improved neutralization and conditioning of detrimental by-products

ndash Reduced system capital and operational cost

New technologies to improve ozone p

generatorg

HV Pulsed Power SwitchingHV Pulsed Power Switching

Microchannel Generation of Ozone

Channel ArrayChannel Array

Microchannel

330 microm 230 microm

Some Cap-DBD Devices Operating in Air

Increase of 60 of

Spacing 225 μmof 60 of plasma

No space

Cap‐DBD ozone generation

bull Ozone concentration is evaluated via Eco S d l UV 100 O A l (0 01Sensors model UV-100 Ozone Analyzer (001 ndash 900 ppm wiht an accuracy of plusmn2)

bull Three reactors 6 tubings 6rdquo with spacings of 0 μm 225 μm and 500 μm running at 3 kV μ μ μ g

SpacingOzone Concentration

3 kV rms 4 kV rms3 kV rms 4 kV rms

0 μm 660 ppm

225 μm 550 ppm

For a device of such small scale these ozone levels are promising

500 μm 380 ppm

J Mahoney W Zhu VS Johnson KH Becker and JL Lopez Electrical and optical emissionmeasurements of a capillary dielectric barrier discharge European Physics Journal D Vol 60 441-447(2010)

QuestionsQuestions

Thank YouFor more informationProf Jose L Lopez PhD

Thank YouFor more informationDepartment of Physics

Telephone (973) 761-9057Email joselopez1shuedu

Website wwwshueduacademicsartsciphysicsWebsite wwwshueduacademicsartsciphysics

Page 83: Dielectric Barrier Discharge (DBD) & Progress in Large ...bonitz/si12/talks/august_8/lopez_si12.pdf · Dielectric Barrier Discharge (DBD) & Progress in Large-Scale Ozone Generation

Plasma Chemistry with CH4 Impurities

OxygenO2 N2

e - e -

CHO N2

NO2

O NO

O2 N O2 O3

NOH

CH4e-

O3 NO

NO2

O2O3NO N

NO2 O

NO2

NO2

N2ONO3

N

O3

NO2

NO

HNO3

N2O4

N2O5

NO2

NO3

N2O5

Effect of methane on the electrode surfaces

a) b)

Inlet Outlet Outlet

) d)

I l t I l t

c) d)

Electrode of the ozone generator afterseveral hours in CH8O2 and up to 2 wt of methane (a b c)

Inlet Inlet

three hours in CH8O2+traces of N2 and up to 1 wt of methane (d) Visible change of discharge character at about 13 length of electrode (a d)

Kinetics of CHx Conversion without N2

conversion by collisions

O2 + CHx 12wt O3 + CO2 +H2O

deposition vaporizationby sputtering

ibl b l 1000 CHreversible process below 1000ppm CH4

Effect of water on electrode surface with N2

Inlet

OutletOutlet

Electrode of the ozone generator after several hours in H OO N

Inlet

Electrode of the ozone generator after several hours in H2OO2N2

Effect of water on electrode surface

Long term effect (800 hrs) of H2OO2N2

Kinetics of CHx Conversion with N2

conversion by collisionsHNO3 formation

O2 + N2 +CHx 12wtO2 + CO2 +H2O + HNO3

deposition vaporizationby sputtering

H2O + HNO3

by sputtering

irreversible process above a N2 threshold () ltlt 1000ppm N2

sticky deposit

p 2 ( ) pp 2 any CH4 concentration (60ppm)

Plasma Chemistry with CH4 ImpuritiesPlasma Chemistry with CH4 Impurities4

bull Formation of NO and NO2 depends on O3 N2 and gas temperature Conclusion N2 admixture is the key factor

SummarySummaryyyThe mechanisms of formed NOx by-products follows the sameThe mechanisms of formed NOx by-products follows the sameprinciples as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentration

principles as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentrationozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)

ozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)g p ( g p )

The conversion of methane to OH and H2O is found to depend on

g p ( g p )

The conversion of methane to OH and H2O is found to depend ondissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)

dissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)discharge gap)discharge gap)

How do you optimize an ozone generatorg

Scientific ApproachScientific ApproachTheoretical Experimental

pppp

c [wt]

f [Hz]

c [wt]

f [Hz]

[kW]UUUβ1

1Cf4αPn

1iiminpeakimin

iiD

q [kWm2]q [kWm2]

150

180

][V]voltagepeakUpeak

[]cylinder perslicesofamountnsliceii

whereth

09 00

30

60

90

120

effic

ienc

y [

][0tdj t bl[F]sliceisdielectricofecapacitancC

[Hz]frequencyf[V]sliceivoltageminimumiUmin

thiD

th

10

28

46

64

82

39

107

176

244 power density

[kWm2]

ozone conc [wt][]CCβ

][0parameteradjustableα

iDiGi

Impact of Power Inductionp

350

400

wer

200

250

300

App

lied

Pow

Arr C 2Arr D +0

Arr E +45Arr F +7

Arr G +3

5 0

100

150

Frac

tion

of

1 2 3 4

ReferenceArr B unstable

Arr C -2

00

50

4Position (1inlet 4outlet)

Experimental Test Rigp g

Experimental Test Rigp g

Outer grounded electrode (left picture) and the dielectric covered inner electrodes (right) d e ect c cove ed e e ect odes ( g t)

Reference (Traditional) Arrangement

Inlet OutletGas flow direction

Optimized Arrangement

Inlet OutletGas flow direction

Intelligent Gap System (IGS)g p y ( )

Molecular Oxygen (O2) Ozone (O3)

O2 O3

yg ( 2) ( 3)

Particle Size SynthesisParticle Size SynthesisByBy--Products Cluster FormationProducts Cluster Formationyy

high diffusion and deposition to surfaces

low diffusion rate good transport

high sedimentation on the structurehigh sedimentation on the structure

Degreacutemont Technologies ndash OzoniaIntelligent Gap SystemIntelligent Gap System

G Vezzuacute JL Lopez A Freilich and K Becker Optimizationof Large-Scale Ozone Generators IEEE Transactions onPlasma Science Vol 37 No 6 p 890-896 (2009)

ConclusionsConclusionsConclusionsConclusionsFundamentals of ozone synthesis in a DBD plasmay p

ndash Highly filamented DBD discharges are best-suitedfor the production of ozone concentrations in therange of 6 to 14 wtrange of 6 to 14 wt

ndash The preferred characteristic of the microdischargesare Townsend-like at reduced electric fields Enaround 190 Townsend

ndash Detrimental side-effects induced by by-productscan be avoided by a proper design of the electrodecan be avoided by a proper design of the electrodearrangement The phenomenon is related to thediffusion rates of formed by-product clusters

ConclusionsConclusionsConclusionsConclusionsBenefits from DBD microplasma tailoring

ndash Reduced power consumption of up to 10 improvement

ndash Increased ozone concentrations of up to 14 now achievable

ndash Improved neutralization and conditioning of detrimental by-products

ndash Reduced system capital and operational cost

New technologies to improve ozone p

generatorg

HV Pulsed Power SwitchingHV Pulsed Power Switching

Microchannel Generation of Ozone

Channel ArrayChannel Array

Microchannel

330 microm 230 microm

Some Cap-DBD Devices Operating in Air

Increase of 60 of

Spacing 225 μmof 60 of plasma

No space

Cap‐DBD ozone generation

bull Ozone concentration is evaluated via Eco S d l UV 100 O A l (0 01Sensors model UV-100 Ozone Analyzer (001 ndash 900 ppm wiht an accuracy of plusmn2)

bull Three reactors 6 tubings 6rdquo with spacings of 0 μm 225 μm and 500 μm running at 3 kV μ μ μ g

SpacingOzone Concentration

3 kV rms 4 kV rms3 kV rms 4 kV rms

0 μm 660 ppm

225 μm 550 ppm

For a device of such small scale these ozone levels are promising

500 μm 380 ppm

J Mahoney W Zhu VS Johnson KH Becker and JL Lopez Electrical and optical emissionmeasurements of a capillary dielectric barrier discharge European Physics Journal D Vol 60 441-447(2010)

QuestionsQuestions

Thank YouFor more informationProf Jose L Lopez PhD

Thank YouFor more informationDepartment of Physics

Telephone (973) 761-9057Email joselopez1shuedu

Website wwwshueduacademicsartsciphysicsWebsite wwwshueduacademicsartsciphysics

Page 84: Dielectric Barrier Discharge (DBD) & Progress in Large ...bonitz/si12/talks/august_8/lopez_si12.pdf · Dielectric Barrier Discharge (DBD) & Progress in Large-Scale Ozone Generation

Effect of methane on the electrode surfaces

a) b)

Inlet Outlet Outlet

) d)

I l t I l t

c) d)

Electrode of the ozone generator afterseveral hours in CH8O2 and up to 2 wt of methane (a b c)

Inlet Inlet

three hours in CH8O2+traces of N2 and up to 1 wt of methane (d) Visible change of discharge character at about 13 length of electrode (a d)

Kinetics of CHx Conversion without N2

conversion by collisions

O2 + CHx 12wt O3 + CO2 +H2O

deposition vaporizationby sputtering

ibl b l 1000 CHreversible process below 1000ppm CH4

Effect of water on electrode surface with N2

Inlet

OutletOutlet

Electrode of the ozone generator after several hours in H OO N

Inlet

Electrode of the ozone generator after several hours in H2OO2N2

Effect of water on electrode surface

Long term effect (800 hrs) of H2OO2N2

Kinetics of CHx Conversion with N2

conversion by collisionsHNO3 formation

O2 + N2 +CHx 12wtO2 + CO2 +H2O + HNO3

deposition vaporizationby sputtering

H2O + HNO3

by sputtering

irreversible process above a N2 threshold () ltlt 1000ppm N2

sticky deposit

p 2 ( ) pp 2 any CH4 concentration (60ppm)

Plasma Chemistry with CH4 ImpuritiesPlasma Chemistry with CH4 Impurities4

bull Formation of NO and NO2 depends on O3 N2 and gas temperature Conclusion N2 admixture is the key factor

SummarySummaryyyThe mechanisms of formed NOx by-products follows the sameThe mechanisms of formed NOx by-products follows the sameprinciples as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentration

principles as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentrationozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)

ozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)g p ( g p )

The conversion of methane to OH and H2O is found to depend on

g p ( g p )

The conversion of methane to OH and H2O is found to depend ondissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)

dissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)discharge gap)discharge gap)

How do you optimize an ozone generatorg

Scientific ApproachScientific ApproachTheoretical Experimental

pppp

c [wt]

f [Hz]

c [wt]

f [Hz]

[kW]UUUβ1

1Cf4αPn

1iiminpeakimin

iiD

q [kWm2]q [kWm2]

150

180

][V]voltagepeakUpeak

[]cylinder perslicesofamountnsliceii

whereth

09 00

30

60

90

120

effic

ienc

y [

][0tdj t bl[F]sliceisdielectricofecapacitancC

[Hz]frequencyf[V]sliceivoltageminimumiUmin

thiD

th

10

28

46

64

82

39

107

176

244 power density

[kWm2]

ozone conc [wt][]CCβ

][0parameteradjustableα

iDiGi

Impact of Power Inductionp

350

400

wer

200

250

300

App

lied

Pow

Arr C 2Arr D +0

Arr E +45Arr F +7

Arr G +3

5 0

100

150

Frac

tion

of

1 2 3 4

ReferenceArr B unstable

Arr C -2

00

50

4Position (1inlet 4outlet)

Experimental Test Rigp g

Experimental Test Rigp g

Outer grounded electrode (left picture) and the dielectric covered inner electrodes (right) d e ect c cove ed e e ect odes ( g t)

Reference (Traditional) Arrangement

Inlet OutletGas flow direction

Optimized Arrangement

Inlet OutletGas flow direction

Intelligent Gap System (IGS)g p y ( )

Molecular Oxygen (O2) Ozone (O3)

O2 O3

yg ( 2) ( 3)

Particle Size SynthesisParticle Size SynthesisByBy--Products Cluster FormationProducts Cluster Formationyy

high diffusion and deposition to surfaces

low diffusion rate good transport

high sedimentation on the structurehigh sedimentation on the structure

Degreacutemont Technologies ndash OzoniaIntelligent Gap SystemIntelligent Gap System

G Vezzuacute JL Lopez A Freilich and K Becker Optimizationof Large-Scale Ozone Generators IEEE Transactions onPlasma Science Vol 37 No 6 p 890-896 (2009)

ConclusionsConclusionsConclusionsConclusionsFundamentals of ozone synthesis in a DBD plasmay p

ndash Highly filamented DBD discharges are best-suitedfor the production of ozone concentrations in therange of 6 to 14 wtrange of 6 to 14 wt

ndash The preferred characteristic of the microdischargesare Townsend-like at reduced electric fields Enaround 190 Townsend

ndash Detrimental side-effects induced by by-productscan be avoided by a proper design of the electrodecan be avoided by a proper design of the electrodearrangement The phenomenon is related to thediffusion rates of formed by-product clusters

ConclusionsConclusionsConclusionsConclusionsBenefits from DBD microplasma tailoring

ndash Reduced power consumption of up to 10 improvement

ndash Increased ozone concentrations of up to 14 now achievable

ndash Improved neutralization and conditioning of detrimental by-products

ndash Reduced system capital and operational cost

New technologies to improve ozone p

generatorg

HV Pulsed Power SwitchingHV Pulsed Power Switching

Microchannel Generation of Ozone

Channel ArrayChannel Array

Microchannel

330 microm 230 microm

Some Cap-DBD Devices Operating in Air

Increase of 60 of

Spacing 225 μmof 60 of plasma

No space

Cap‐DBD ozone generation

bull Ozone concentration is evaluated via Eco S d l UV 100 O A l (0 01Sensors model UV-100 Ozone Analyzer (001 ndash 900 ppm wiht an accuracy of plusmn2)

bull Three reactors 6 tubings 6rdquo with spacings of 0 μm 225 μm and 500 μm running at 3 kV μ μ μ g

SpacingOzone Concentration

3 kV rms 4 kV rms3 kV rms 4 kV rms

0 μm 660 ppm

225 μm 550 ppm

For a device of such small scale these ozone levels are promising

500 μm 380 ppm

J Mahoney W Zhu VS Johnson KH Becker and JL Lopez Electrical and optical emissionmeasurements of a capillary dielectric barrier discharge European Physics Journal D Vol 60 441-447(2010)

QuestionsQuestions

Thank YouFor more informationProf Jose L Lopez PhD

Thank YouFor more informationDepartment of Physics

Telephone (973) 761-9057Email joselopez1shuedu

Website wwwshueduacademicsartsciphysicsWebsite wwwshueduacademicsartsciphysics

Page 85: Dielectric Barrier Discharge (DBD) & Progress in Large ...bonitz/si12/talks/august_8/lopez_si12.pdf · Dielectric Barrier Discharge (DBD) & Progress in Large-Scale Ozone Generation

Kinetics of CHx Conversion without N2

conversion by collisions

O2 + CHx 12wt O3 + CO2 +H2O

deposition vaporizationby sputtering

ibl b l 1000 CHreversible process below 1000ppm CH4

Effect of water on electrode surface with N2

Inlet

OutletOutlet

Electrode of the ozone generator after several hours in H OO N

Inlet

Electrode of the ozone generator after several hours in H2OO2N2

Effect of water on electrode surface

Long term effect (800 hrs) of H2OO2N2

Kinetics of CHx Conversion with N2

conversion by collisionsHNO3 formation

O2 + N2 +CHx 12wtO2 + CO2 +H2O + HNO3

deposition vaporizationby sputtering

H2O + HNO3

by sputtering

irreversible process above a N2 threshold () ltlt 1000ppm N2

sticky deposit

p 2 ( ) pp 2 any CH4 concentration (60ppm)

Plasma Chemistry with CH4 ImpuritiesPlasma Chemistry with CH4 Impurities4

bull Formation of NO and NO2 depends on O3 N2 and gas temperature Conclusion N2 admixture is the key factor

SummarySummaryyyThe mechanisms of formed NOx by-products follows the sameThe mechanisms of formed NOx by-products follows the sameprinciples as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentration

principles as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentrationozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)

ozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)g p ( g p )

The conversion of methane to OH and H2O is found to depend on

g p ( g p )

The conversion of methane to OH and H2O is found to depend ondissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)

dissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)discharge gap)discharge gap)

How do you optimize an ozone generatorg

Scientific ApproachScientific ApproachTheoretical Experimental

pppp

c [wt]

f [Hz]

c [wt]

f [Hz]

[kW]UUUβ1

1Cf4αPn

1iiminpeakimin

iiD

q [kWm2]q [kWm2]

150

180

][V]voltagepeakUpeak

[]cylinder perslicesofamountnsliceii

whereth

09 00

30

60

90

120

effic

ienc

y [

][0tdj t bl[F]sliceisdielectricofecapacitancC

[Hz]frequencyf[V]sliceivoltageminimumiUmin

thiD

th

10

28

46

64

82

39

107

176

244 power density

[kWm2]

ozone conc [wt][]CCβ

][0parameteradjustableα

iDiGi

Impact of Power Inductionp

350

400

wer

200

250

300

App

lied

Pow

Arr C 2Arr D +0

Arr E +45Arr F +7

Arr G +3

5 0

100

150

Frac

tion

of

1 2 3 4

ReferenceArr B unstable

Arr C -2

00

50

4Position (1inlet 4outlet)

Experimental Test Rigp g

Experimental Test Rigp g

Outer grounded electrode (left picture) and the dielectric covered inner electrodes (right) d e ect c cove ed e e ect odes ( g t)

Reference (Traditional) Arrangement

Inlet OutletGas flow direction

Optimized Arrangement

Inlet OutletGas flow direction

Intelligent Gap System (IGS)g p y ( )

Molecular Oxygen (O2) Ozone (O3)

O2 O3

yg ( 2) ( 3)

Particle Size SynthesisParticle Size SynthesisByBy--Products Cluster FormationProducts Cluster Formationyy

high diffusion and deposition to surfaces

low diffusion rate good transport

high sedimentation on the structurehigh sedimentation on the structure

Degreacutemont Technologies ndash OzoniaIntelligent Gap SystemIntelligent Gap System

G Vezzuacute JL Lopez A Freilich and K Becker Optimizationof Large-Scale Ozone Generators IEEE Transactions onPlasma Science Vol 37 No 6 p 890-896 (2009)

ConclusionsConclusionsConclusionsConclusionsFundamentals of ozone synthesis in a DBD plasmay p

ndash Highly filamented DBD discharges are best-suitedfor the production of ozone concentrations in therange of 6 to 14 wtrange of 6 to 14 wt

ndash The preferred characteristic of the microdischargesare Townsend-like at reduced electric fields Enaround 190 Townsend

ndash Detrimental side-effects induced by by-productscan be avoided by a proper design of the electrodecan be avoided by a proper design of the electrodearrangement The phenomenon is related to thediffusion rates of formed by-product clusters

ConclusionsConclusionsConclusionsConclusionsBenefits from DBD microplasma tailoring

ndash Reduced power consumption of up to 10 improvement

ndash Increased ozone concentrations of up to 14 now achievable

ndash Improved neutralization and conditioning of detrimental by-products

ndash Reduced system capital and operational cost

New technologies to improve ozone p

generatorg

HV Pulsed Power SwitchingHV Pulsed Power Switching

Microchannel Generation of Ozone

Channel ArrayChannel Array

Microchannel

330 microm 230 microm

Some Cap-DBD Devices Operating in Air

Increase of 60 of

Spacing 225 μmof 60 of plasma

No space

Cap‐DBD ozone generation

bull Ozone concentration is evaluated via Eco S d l UV 100 O A l (0 01Sensors model UV-100 Ozone Analyzer (001 ndash 900 ppm wiht an accuracy of plusmn2)

bull Three reactors 6 tubings 6rdquo with spacings of 0 μm 225 μm and 500 μm running at 3 kV μ μ μ g

SpacingOzone Concentration

3 kV rms 4 kV rms3 kV rms 4 kV rms

0 μm 660 ppm

225 μm 550 ppm

For a device of such small scale these ozone levels are promising

500 μm 380 ppm

J Mahoney W Zhu VS Johnson KH Becker and JL Lopez Electrical and optical emissionmeasurements of a capillary dielectric barrier discharge European Physics Journal D Vol 60 441-447(2010)

QuestionsQuestions

Thank YouFor more informationProf Jose L Lopez PhD

Thank YouFor more informationDepartment of Physics

Telephone (973) 761-9057Email joselopez1shuedu

Website wwwshueduacademicsartsciphysicsWebsite wwwshueduacademicsartsciphysics

Page 86: Dielectric Barrier Discharge (DBD) & Progress in Large ...bonitz/si12/talks/august_8/lopez_si12.pdf · Dielectric Barrier Discharge (DBD) & Progress in Large-Scale Ozone Generation

Effect of water on electrode surface with N2

Inlet

OutletOutlet

Electrode of the ozone generator after several hours in H OO N

Inlet

Electrode of the ozone generator after several hours in H2OO2N2

Effect of water on electrode surface

Long term effect (800 hrs) of H2OO2N2

Kinetics of CHx Conversion with N2

conversion by collisionsHNO3 formation

O2 + N2 +CHx 12wtO2 + CO2 +H2O + HNO3

deposition vaporizationby sputtering

H2O + HNO3

by sputtering

irreversible process above a N2 threshold () ltlt 1000ppm N2

sticky deposit

p 2 ( ) pp 2 any CH4 concentration (60ppm)

Plasma Chemistry with CH4 ImpuritiesPlasma Chemistry with CH4 Impurities4

bull Formation of NO and NO2 depends on O3 N2 and gas temperature Conclusion N2 admixture is the key factor

SummarySummaryyyThe mechanisms of formed NOx by-products follows the sameThe mechanisms of formed NOx by-products follows the sameprinciples as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentration

principles as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentrationozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)

ozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)g p ( g p )

The conversion of methane to OH and H2O is found to depend on

g p ( g p )

The conversion of methane to OH and H2O is found to depend ondissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)

dissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)discharge gap)discharge gap)

How do you optimize an ozone generatorg

Scientific ApproachScientific ApproachTheoretical Experimental

pppp

c [wt]

f [Hz]

c [wt]

f [Hz]

[kW]UUUβ1

1Cf4αPn

1iiminpeakimin

iiD

q [kWm2]q [kWm2]

150

180

][V]voltagepeakUpeak

[]cylinder perslicesofamountnsliceii

whereth

09 00

30

60

90

120

effic

ienc

y [

][0tdj t bl[F]sliceisdielectricofecapacitancC

[Hz]frequencyf[V]sliceivoltageminimumiUmin

thiD

th

10

28

46

64

82

39

107

176

244 power density

[kWm2]

ozone conc [wt][]CCβ

][0parameteradjustableα

iDiGi

Impact of Power Inductionp

350

400

wer

200

250

300

App

lied

Pow

Arr C 2Arr D +0

Arr E +45Arr F +7

Arr G +3

5 0

100

150

Frac

tion

of

1 2 3 4

ReferenceArr B unstable

Arr C -2

00

50

4Position (1inlet 4outlet)

Experimental Test Rigp g

Experimental Test Rigp g

Outer grounded electrode (left picture) and the dielectric covered inner electrodes (right) d e ect c cove ed e e ect odes ( g t)

Reference (Traditional) Arrangement

Inlet OutletGas flow direction

Optimized Arrangement

Inlet OutletGas flow direction

Intelligent Gap System (IGS)g p y ( )

Molecular Oxygen (O2) Ozone (O3)

O2 O3

yg ( 2) ( 3)

Particle Size SynthesisParticle Size SynthesisByBy--Products Cluster FormationProducts Cluster Formationyy

high diffusion and deposition to surfaces

low diffusion rate good transport

high sedimentation on the structurehigh sedimentation on the structure

Degreacutemont Technologies ndash OzoniaIntelligent Gap SystemIntelligent Gap System

G Vezzuacute JL Lopez A Freilich and K Becker Optimizationof Large-Scale Ozone Generators IEEE Transactions onPlasma Science Vol 37 No 6 p 890-896 (2009)

ConclusionsConclusionsConclusionsConclusionsFundamentals of ozone synthesis in a DBD plasmay p

ndash Highly filamented DBD discharges are best-suitedfor the production of ozone concentrations in therange of 6 to 14 wtrange of 6 to 14 wt

ndash The preferred characteristic of the microdischargesare Townsend-like at reduced electric fields Enaround 190 Townsend

ndash Detrimental side-effects induced by by-productscan be avoided by a proper design of the electrodecan be avoided by a proper design of the electrodearrangement The phenomenon is related to thediffusion rates of formed by-product clusters

ConclusionsConclusionsConclusionsConclusionsBenefits from DBD microplasma tailoring

ndash Reduced power consumption of up to 10 improvement

ndash Increased ozone concentrations of up to 14 now achievable

ndash Improved neutralization and conditioning of detrimental by-products

ndash Reduced system capital and operational cost

New technologies to improve ozone p

generatorg

HV Pulsed Power SwitchingHV Pulsed Power Switching

Microchannel Generation of Ozone

Channel ArrayChannel Array

Microchannel

330 microm 230 microm

Some Cap-DBD Devices Operating in Air

Increase of 60 of

Spacing 225 μmof 60 of plasma

No space

Cap‐DBD ozone generation

bull Ozone concentration is evaluated via Eco S d l UV 100 O A l (0 01Sensors model UV-100 Ozone Analyzer (001 ndash 900 ppm wiht an accuracy of plusmn2)

bull Three reactors 6 tubings 6rdquo with spacings of 0 μm 225 μm and 500 μm running at 3 kV μ μ μ g

SpacingOzone Concentration

3 kV rms 4 kV rms3 kV rms 4 kV rms

0 μm 660 ppm

225 μm 550 ppm

For a device of such small scale these ozone levels are promising

500 μm 380 ppm

J Mahoney W Zhu VS Johnson KH Becker and JL Lopez Electrical and optical emissionmeasurements of a capillary dielectric barrier discharge European Physics Journal D Vol 60 441-447(2010)

QuestionsQuestions

Thank YouFor more informationProf Jose L Lopez PhD

Thank YouFor more informationDepartment of Physics

Telephone (973) 761-9057Email joselopez1shuedu

Website wwwshueduacademicsartsciphysicsWebsite wwwshueduacademicsartsciphysics

Page 87: Dielectric Barrier Discharge (DBD) & Progress in Large ...bonitz/si12/talks/august_8/lopez_si12.pdf · Dielectric Barrier Discharge (DBD) & Progress in Large-Scale Ozone Generation

Effect of water on electrode surface

Long term effect (800 hrs) of H2OO2N2

Kinetics of CHx Conversion with N2

conversion by collisionsHNO3 formation

O2 + N2 +CHx 12wtO2 + CO2 +H2O + HNO3

deposition vaporizationby sputtering

H2O + HNO3

by sputtering

irreversible process above a N2 threshold () ltlt 1000ppm N2

sticky deposit

p 2 ( ) pp 2 any CH4 concentration (60ppm)

Plasma Chemistry with CH4 ImpuritiesPlasma Chemistry with CH4 Impurities4

bull Formation of NO and NO2 depends on O3 N2 and gas temperature Conclusion N2 admixture is the key factor

SummarySummaryyyThe mechanisms of formed NOx by-products follows the sameThe mechanisms of formed NOx by-products follows the sameprinciples as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentration

principles as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentrationozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)

ozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)g p ( g p )

The conversion of methane to OH and H2O is found to depend on

g p ( g p )

The conversion of methane to OH and H2O is found to depend ondissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)

dissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)discharge gap)discharge gap)

How do you optimize an ozone generatorg

Scientific ApproachScientific ApproachTheoretical Experimental

pppp

c [wt]

f [Hz]

c [wt]

f [Hz]

[kW]UUUβ1

1Cf4αPn

1iiminpeakimin

iiD

q [kWm2]q [kWm2]

150

180

][V]voltagepeakUpeak

[]cylinder perslicesofamountnsliceii

whereth

09 00

30

60

90

120

effic

ienc

y [

][0tdj t bl[F]sliceisdielectricofecapacitancC

[Hz]frequencyf[V]sliceivoltageminimumiUmin

thiD

th

10

28

46

64

82

39

107

176

244 power density

[kWm2]

ozone conc [wt][]CCβ

][0parameteradjustableα

iDiGi

Impact of Power Inductionp

350

400

wer

200

250

300

App

lied

Pow

Arr C 2Arr D +0

Arr E +45Arr F +7

Arr G +3

5 0

100

150

Frac

tion

of

1 2 3 4

ReferenceArr B unstable

Arr C -2

00

50

4Position (1inlet 4outlet)

Experimental Test Rigp g

Experimental Test Rigp g

Outer grounded electrode (left picture) and the dielectric covered inner electrodes (right) d e ect c cove ed e e ect odes ( g t)

Reference (Traditional) Arrangement

Inlet OutletGas flow direction

Optimized Arrangement

Inlet OutletGas flow direction

Intelligent Gap System (IGS)g p y ( )

Molecular Oxygen (O2) Ozone (O3)

O2 O3

yg ( 2) ( 3)

Particle Size SynthesisParticle Size SynthesisByBy--Products Cluster FormationProducts Cluster Formationyy

high diffusion and deposition to surfaces

low diffusion rate good transport

high sedimentation on the structurehigh sedimentation on the structure

Degreacutemont Technologies ndash OzoniaIntelligent Gap SystemIntelligent Gap System

G Vezzuacute JL Lopez A Freilich and K Becker Optimizationof Large-Scale Ozone Generators IEEE Transactions onPlasma Science Vol 37 No 6 p 890-896 (2009)

ConclusionsConclusionsConclusionsConclusionsFundamentals of ozone synthesis in a DBD plasmay p

ndash Highly filamented DBD discharges are best-suitedfor the production of ozone concentrations in therange of 6 to 14 wtrange of 6 to 14 wt

ndash The preferred characteristic of the microdischargesare Townsend-like at reduced electric fields Enaround 190 Townsend

ndash Detrimental side-effects induced by by-productscan be avoided by a proper design of the electrodecan be avoided by a proper design of the electrodearrangement The phenomenon is related to thediffusion rates of formed by-product clusters

ConclusionsConclusionsConclusionsConclusionsBenefits from DBD microplasma tailoring

ndash Reduced power consumption of up to 10 improvement

ndash Increased ozone concentrations of up to 14 now achievable

ndash Improved neutralization and conditioning of detrimental by-products

ndash Reduced system capital and operational cost

New technologies to improve ozone p

generatorg

HV Pulsed Power SwitchingHV Pulsed Power Switching

Microchannel Generation of Ozone

Channel ArrayChannel Array

Microchannel

330 microm 230 microm

Some Cap-DBD Devices Operating in Air

Increase of 60 of

Spacing 225 μmof 60 of plasma

No space

Cap‐DBD ozone generation

bull Ozone concentration is evaluated via Eco S d l UV 100 O A l (0 01Sensors model UV-100 Ozone Analyzer (001 ndash 900 ppm wiht an accuracy of plusmn2)

bull Three reactors 6 tubings 6rdquo with spacings of 0 μm 225 μm and 500 μm running at 3 kV μ μ μ g

SpacingOzone Concentration

3 kV rms 4 kV rms3 kV rms 4 kV rms

0 μm 660 ppm

225 μm 550 ppm

For a device of such small scale these ozone levels are promising

500 μm 380 ppm

J Mahoney W Zhu VS Johnson KH Becker and JL Lopez Electrical and optical emissionmeasurements of a capillary dielectric barrier discharge European Physics Journal D Vol 60 441-447(2010)

QuestionsQuestions

Thank YouFor more informationProf Jose L Lopez PhD

Thank YouFor more informationDepartment of Physics

Telephone (973) 761-9057Email joselopez1shuedu

Website wwwshueduacademicsartsciphysicsWebsite wwwshueduacademicsartsciphysics

Page 88: Dielectric Barrier Discharge (DBD) & Progress in Large ...bonitz/si12/talks/august_8/lopez_si12.pdf · Dielectric Barrier Discharge (DBD) & Progress in Large-Scale Ozone Generation

Kinetics of CHx Conversion with N2

conversion by collisionsHNO3 formation

O2 + N2 +CHx 12wtO2 + CO2 +H2O + HNO3

deposition vaporizationby sputtering

H2O + HNO3

by sputtering

irreversible process above a N2 threshold () ltlt 1000ppm N2

sticky deposit

p 2 ( ) pp 2 any CH4 concentration (60ppm)

Plasma Chemistry with CH4 ImpuritiesPlasma Chemistry with CH4 Impurities4

bull Formation of NO and NO2 depends on O3 N2 and gas temperature Conclusion N2 admixture is the key factor

SummarySummaryyyThe mechanisms of formed NOx by-products follows the sameThe mechanisms of formed NOx by-products follows the sameprinciples as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentration

principles as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentrationozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)

ozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)g p ( g p )

The conversion of methane to OH and H2O is found to depend on

g p ( g p )

The conversion of methane to OH and H2O is found to depend ondissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)

dissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)discharge gap)discharge gap)

How do you optimize an ozone generatorg

Scientific ApproachScientific ApproachTheoretical Experimental

pppp

c [wt]

f [Hz]

c [wt]

f [Hz]

[kW]UUUβ1

1Cf4αPn

1iiminpeakimin

iiD

q [kWm2]q [kWm2]

150

180

][V]voltagepeakUpeak

[]cylinder perslicesofamountnsliceii

whereth

09 00

30

60

90

120

effic

ienc

y [

][0tdj t bl[F]sliceisdielectricofecapacitancC

[Hz]frequencyf[V]sliceivoltageminimumiUmin

thiD

th

10

28

46

64

82

39

107

176

244 power density

[kWm2]

ozone conc [wt][]CCβ

][0parameteradjustableα

iDiGi

Impact of Power Inductionp

350

400

wer

200

250

300

App

lied

Pow

Arr C 2Arr D +0

Arr E +45Arr F +7

Arr G +3

5 0

100

150

Frac

tion

of

1 2 3 4

ReferenceArr B unstable

Arr C -2

00

50

4Position (1inlet 4outlet)

Experimental Test Rigp g

Experimental Test Rigp g

Outer grounded electrode (left picture) and the dielectric covered inner electrodes (right) d e ect c cove ed e e ect odes ( g t)

Reference (Traditional) Arrangement

Inlet OutletGas flow direction

Optimized Arrangement

Inlet OutletGas flow direction

Intelligent Gap System (IGS)g p y ( )

Molecular Oxygen (O2) Ozone (O3)

O2 O3

yg ( 2) ( 3)

Particle Size SynthesisParticle Size SynthesisByBy--Products Cluster FormationProducts Cluster Formationyy

high diffusion and deposition to surfaces

low diffusion rate good transport

high sedimentation on the structurehigh sedimentation on the structure

Degreacutemont Technologies ndash OzoniaIntelligent Gap SystemIntelligent Gap System

G Vezzuacute JL Lopez A Freilich and K Becker Optimizationof Large-Scale Ozone Generators IEEE Transactions onPlasma Science Vol 37 No 6 p 890-896 (2009)

ConclusionsConclusionsConclusionsConclusionsFundamentals of ozone synthesis in a DBD plasmay p

ndash Highly filamented DBD discharges are best-suitedfor the production of ozone concentrations in therange of 6 to 14 wtrange of 6 to 14 wt

ndash The preferred characteristic of the microdischargesare Townsend-like at reduced electric fields Enaround 190 Townsend

ndash Detrimental side-effects induced by by-productscan be avoided by a proper design of the electrodecan be avoided by a proper design of the electrodearrangement The phenomenon is related to thediffusion rates of formed by-product clusters

ConclusionsConclusionsConclusionsConclusionsBenefits from DBD microplasma tailoring

ndash Reduced power consumption of up to 10 improvement

ndash Increased ozone concentrations of up to 14 now achievable

ndash Improved neutralization and conditioning of detrimental by-products

ndash Reduced system capital and operational cost

New technologies to improve ozone p

generatorg

HV Pulsed Power SwitchingHV Pulsed Power Switching

Microchannel Generation of Ozone

Channel ArrayChannel Array

Microchannel

330 microm 230 microm

Some Cap-DBD Devices Operating in Air

Increase of 60 of

Spacing 225 μmof 60 of plasma

No space

Cap‐DBD ozone generation

bull Ozone concentration is evaluated via Eco S d l UV 100 O A l (0 01Sensors model UV-100 Ozone Analyzer (001 ndash 900 ppm wiht an accuracy of plusmn2)

bull Three reactors 6 tubings 6rdquo with spacings of 0 μm 225 μm and 500 μm running at 3 kV μ μ μ g

SpacingOzone Concentration

3 kV rms 4 kV rms3 kV rms 4 kV rms

0 μm 660 ppm

225 μm 550 ppm

For a device of such small scale these ozone levels are promising

500 μm 380 ppm

J Mahoney W Zhu VS Johnson KH Becker and JL Lopez Electrical and optical emissionmeasurements of a capillary dielectric barrier discharge European Physics Journal D Vol 60 441-447(2010)

QuestionsQuestions

Thank YouFor more informationProf Jose L Lopez PhD

Thank YouFor more informationDepartment of Physics

Telephone (973) 761-9057Email joselopez1shuedu

Website wwwshueduacademicsartsciphysicsWebsite wwwshueduacademicsartsciphysics

Page 89: Dielectric Barrier Discharge (DBD) & Progress in Large ...bonitz/si12/talks/august_8/lopez_si12.pdf · Dielectric Barrier Discharge (DBD) & Progress in Large-Scale Ozone Generation

Plasma Chemistry with CH4 ImpuritiesPlasma Chemistry with CH4 Impurities4

bull Formation of NO and NO2 depends on O3 N2 and gas temperature Conclusion N2 admixture is the key factor

SummarySummaryyyThe mechanisms of formed NOx by-products follows the sameThe mechanisms of formed NOx by-products follows the sameprinciples as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentration

principles as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentrationozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)

ozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)g p ( g p )

The conversion of methane to OH and H2O is found to depend on

g p ( g p )

The conversion of methane to OH and H2O is found to depend ondissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)

dissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)discharge gap)discharge gap)

How do you optimize an ozone generatorg

Scientific ApproachScientific ApproachTheoretical Experimental

pppp

c [wt]

f [Hz]

c [wt]

f [Hz]

[kW]UUUβ1

1Cf4αPn

1iiminpeakimin

iiD

q [kWm2]q [kWm2]

150

180

][V]voltagepeakUpeak

[]cylinder perslicesofamountnsliceii

whereth

09 00

30

60

90

120

effic

ienc

y [

][0tdj t bl[F]sliceisdielectricofecapacitancC

[Hz]frequencyf[V]sliceivoltageminimumiUmin

thiD

th

10

28

46

64

82

39

107

176

244 power density

[kWm2]

ozone conc [wt][]CCβ

][0parameteradjustableα

iDiGi

Impact of Power Inductionp

350

400

wer

200

250

300

App

lied

Pow

Arr C 2Arr D +0

Arr E +45Arr F +7

Arr G +3

5 0

100

150

Frac

tion

of

1 2 3 4

ReferenceArr B unstable

Arr C -2

00

50

4Position (1inlet 4outlet)

Experimental Test Rigp g

Experimental Test Rigp g

Outer grounded electrode (left picture) and the dielectric covered inner electrodes (right) d e ect c cove ed e e ect odes ( g t)

Reference (Traditional) Arrangement

Inlet OutletGas flow direction

Optimized Arrangement

Inlet OutletGas flow direction

Intelligent Gap System (IGS)g p y ( )

Molecular Oxygen (O2) Ozone (O3)

O2 O3

yg ( 2) ( 3)

Particle Size SynthesisParticle Size SynthesisByBy--Products Cluster FormationProducts Cluster Formationyy

high diffusion and deposition to surfaces

low diffusion rate good transport

high sedimentation on the structurehigh sedimentation on the structure

Degreacutemont Technologies ndash OzoniaIntelligent Gap SystemIntelligent Gap System

G Vezzuacute JL Lopez A Freilich and K Becker Optimizationof Large-Scale Ozone Generators IEEE Transactions onPlasma Science Vol 37 No 6 p 890-896 (2009)

ConclusionsConclusionsConclusionsConclusionsFundamentals of ozone synthesis in a DBD plasmay p

ndash Highly filamented DBD discharges are best-suitedfor the production of ozone concentrations in therange of 6 to 14 wtrange of 6 to 14 wt

ndash The preferred characteristic of the microdischargesare Townsend-like at reduced electric fields Enaround 190 Townsend

ndash Detrimental side-effects induced by by-productscan be avoided by a proper design of the electrodecan be avoided by a proper design of the electrodearrangement The phenomenon is related to thediffusion rates of formed by-product clusters

ConclusionsConclusionsConclusionsConclusionsBenefits from DBD microplasma tailoring

ndash Reduced power consumption of up to 10 improvement

ndash Increased ozone concentrations of up to 14 now achievable

ndash Improved neutralization and conditioning of detrimental by-products

ndash Reduced system capital and operational cost

New technologies to improve ozone p

generatorg

HV Pulsed Power SwitchingHV Pulsed Power Switching

Microchannel Generation of Ozone

Channel ArrayChannel Array

Microchannel

330 microm 230 microm

Some Cap-DBD Devices Operating in Air

Increase of 60 of

Spacing 225 μmof 60 of plasma

No space

Cap‐DBD ozone generation

bull Ozone concentration is evaluated via Eco S d l UV 100 O A l (0 01Sensors model UV-100 Ozone Analyzer (001 ndash 900 ppm wiht an accuracy of plusmn2)

bull Three reactors 6 tubings 6rdquo with spacings of 0 μm 225 μm and 500 μm running at 3 kV μ μ μ g

SpacingOzone Concentration

3 kV rms 4 kV rms3 kV rms 4 kV rms

0 μm 660 ppm

225 μm 550 ppm

For a device of such small scale these ozone levels are promising

500 μm 380 ppm

J Mahoney W Zhu VS Johnson KH Becker and JL Lopez Electrical and optical emissionmeasurements of a capillary dielectric barrier discharge European Physics Journal D Vol 60 441-447(2010)

QuestionsQuestions

Thank YouFor more informationProf Jose L Lopez PhD

Thank YouFor more informationDepartment of Physics

Telephone (973) 761-9057Email joselopez1shuedu

Website wwwshueduacademicsartsciphysicsWebsite wwwshueduacademicsartsciphysics

Page 90: Dielectric Barrier Discharge (DBD) & Progress in Large ...bonitz/si12/talks/august_8/lopez_si12.pdf · Dielectric Barrier Discharge (DBD) & Progress in Large-Scale Ozone Generation

SummarySummaryyyThe mechanisms of formed NOx by-products follows the sameThe mechanisms of formed NOx by-products follows the sameprinciples as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentration

principles as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentrationozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)

ozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)g p ( g p )

The conversion of methane to OH and H2O is found to depend on

g p ( g p )

The conversion of methane to OH and H2O is found to depend ondissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)

dissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)discharge gap)discharge gap)

How do you optimize an ozone generatorg

Scientific ApproachScientific ApproachTheoretical Experimental

pppp

c [wt]

f [Hz]

c [wt]

f [Hz]

[kW]UUUβ1

1Cf4αPn

1iiminpeakimin

iiD

q [kWm2]q [kWm2]

150

180

][V]voltagepeakUpeak

[]cylinder perslicesofamountnsliceii

whereth

09 00

30

60

90

120

effic

ienc

y [

][0tdj t bl[F]sliceisdielectricofecapacitancC

[Hz]frequencyf[V]sliceivoltageminimumiUmin

thiD

th

10

28

46

64

82

39

107

176

244 power density

[kWm2]

ozone conc [wt][]CCβ

][0parameteradjustableα

iDiGi

Impact of Power Inductionp

350

400

wer

200

250

300

App

lied

Pow

Arr C 2Arr D +0

Arr E +45Arr F +7

Arr G +3

5 0

100

150

Frac

tion

of

1 2 3 4

ReferenceArr B unstable

Arr C -2

00

50

4Position (1inlet 4outlet)

Experimental Test Rigp g

Experimental Test Rigp g

Outer grounded electrode (left picture) and the dielectric covered inner electrodes (right) d e ect c cove ed e e ect odes ( g t)

Reference (Traditional) Arrangement

Inlet OutletGas flow direction

Optimized Arrangement

Inlet OutletGas flow direction

Intelligent Gap System (IGS)g p y ( )

Molecular Oxygen (O2) Ozone (O3)

O2 O3

yg ( 2) ( 3)

Particle Size SynthesisParticle Size SynthesisByBy--Products Cluster FormationProducts Cluster Formationyy

high diffusion and deposition to surfaces

low diffusion rate good transport

high sedimentation on the structurehigh sedimentation on the structure

Degreacutemont Technologies ndash OzoniaIntelligent Gap SystemIntelligent Gap System

G Vezzuacute JL Lopez A Freilich and K Becker Optimizationof Large-Scale Ozone Generators IEEE Transactions onPlasma Science Vol 37 No 6 p 890-896 (2009)

ConclusionsConclusionsConclusionsConclusionsFundamentals of ozone synthesis in a DBD plasmay p

ndash Highly filamented DBD discharges are best-suitedfor the production of ozone concentrations in therange of 6 to 14 wtrange of 6 to 14 wt

ndash The preferred characteristic of the microdischargesare Townsend-like at reduced electric fields Enaround 190 Townsend

ndash Detrimental side-effects induced by by-productscan be avoided by a proper design of the electrodecan be avoided by a proper design of the electrodearrangement The phenomenon is related to thediffusion rates of formed by-product clusters

ConclusionsConclusionsConclusionsConclusionsBenefits from DBD microplasma tailoring

ndash Reduced power consumption of up to 10 improvement

ndash Increased ozone concentrations of up to 14 now achievable

ndash Improved neutralization and conditioning of detrimental by-products

ndash Reduced system capital and operational cost

New technologies to improve ozone p

generatorg

HV Pulsed Power SwitchingHV Pulsed Power Switching

Microchannel Generation of Ozone

Channel ArrayChannel Array

Microchannel

330 microm 230 microm

Some Cap-DBD Devices Operating in Air

Increase of 60 of

Spacing 225 μmof 60 of plasma

No space

Cap‐DBD ozone generation

bull Ozone concentration is evaluated via Eco S d l UV 100 O A l (0 01Sensors model UV-100 Ozone Analyzer (001 ndash 900 ppm wiht an accuracy of plusmn2)

bull Three reactors 6 tubings 6rdquo with spacings of 0 μm 225 μm and 500 μm running at 3 kV μ μ μ g

SpacingOzone Concentration

3 kV rms 4 kV rms3 kV rms 4 kV rms

0 μm 660 ppm

225 μm 550 ppm

For a device of such small scale these ozone levels are promising

500 μm 380 ppm

J Mahoney W Zhu VS Johnson KH Becker and JL Lopez Electrical and optical emissionmeasurements of a capillary dielectric barrier discharge European Physics Journal D Vol 60 441-447(2010)

QuestionsQuestions

Thank YouFor more informationProf Jose L Lopez PhD

Thank YouFor more informationDepartment of Physics

Telephone (973) 761-9057Email joselopez1shuedu

Website wwwshueduacademicsartsciphysicsWebsite wwwshueduacademicsartsciphysics

Page 91: Dielectric Barrier Discharge (DBD) & Progress in Large ...bonitz/si12/talks/august_8/lopez_si12.pdf · Dielectric Barrier Discharge (DBD) & Progress in Large-Scale Ozone Generation

How do you optimize an ozone generatorg

Scientific ApproachScientific ApproachTheoretical Experimental

pppp

c [wt]

f [Hz]

c [wt]

f [Hz]

[kW]UUUβ1

1Cf4αPn

1iiminpeakimin

iiD

q [kWm2]q [kWm2]

150

180

][V]voltagepeakUpeak

[]cylinder perslicesofamountnsliceii

whereth

09 00

30

60

90

120

effic

ienc

y [

][0tdj t bl[F]sliceisdielectricofecapacitancC

[Hz]frequencyf[V]sliceivoltageminimumiUmin

thiD

th

10

28

46

64

82

39

107

176

244 power density

[kWm2]

ozone conc [wt][]CCβ

][0parameteradjustableα

iDiGi

Impact of Power Inductionp

350

400

wer

200

250

300

App

lied

Pow

Arr C 2Arr D +0

Arr E +45Arr F +7

Arr G +3

5 0

100

150

Frac

tion

of

1 2 3 4

ReferenceArr B unstable

Arr C -2

00

50

4Position (1inlet 4outlet)

Experimental Test Rigp g

Experimental Test Rigp g

Outer grounded electrode (left picture) and the dielectric covered inner electrodes (right) d e ect c cove ed e e ect odes ( g t)

Reference (Traditional) Arrangement

Inlet OutletGas flow direction

Optimized Arrangement

Inlet OutletGas flow direction

Intelligent Gap System (IGS)g p y ( )

Molecular Oxygen (O2) Ozone (O3)

O2 O3

yg ( 2) ( 3)

Particle Size SynthesisParticle Size SynthesisByBy--Products Cluster FormationProducts Cluster Formationyy

high diffusion and deposition to surfaces

low diffusion rate good transport

high sedimentation on the structurehigh sedimentation on the structure

Degreacutemont Technologies ndash OzoniaIntelligent Gap SystemIntelligent Gap System

G Vezzuacute JL Lopez A Freilich and K Becker Optimizationof Large-Scale Ozone Generators IEEE Transactions onPlasma Science Vol 37 No 6 p 890-896 (2009)

ConclusionsConclusionsConclusionsConclusionsFundamentals of ozone synthesis in a DBD plasmay p

ndash Highly filamented DBD discharges are best-suitedfor the production of ozone concentrations in therange of 6 to 14 wtrange of 6 to 14 wt

ndash The preferred characteristic of the microdischargesare Townsend-like at reduced electric fields Enaround 190 Townsend

ndash Detrimental side-effects induced by by-productscan be avoided by a proper design of the electrodecan be avoided by a proper design of the electrodearrangement The phenomenon is related to thediffusion rates of formed by-product clusters

ConclusionsConclusionsConclusionsConclusionsBenefits from DBD microplasma tailoring

ndash Reduced power consumption of up to 10 improvement

ndash Increased ozone concentrations of up to 14 now achievable

ndash Improved neutralization and conditioning of detrimental by-products

ndash Reduced system capital and operational cost

New technologies to improve ozone p

generatorg

HV Pulsed Power SwitchingHV Pulsed Power Switching

Microchannel Generation of Ozone

Channel ArrayChannel Array

Microchannel

330 microm 230 microm

Some Cap-DBD Devices Operating in Air

Increase of 60 of

Spacing 225 μmof 60 of plasma

No space

Cap‐DBD ozone generation

bull Ozone concentration is evaluated via Eco S d l UV 100 O A l (0 01Sensors model UV-100 Ozone Analyzer (001 ndash 900 ppm wiht an accuracy of plusmn2)

bull Three reactors 6 tubings 6rdquo with spacings of 0 μm 225 μm and 500 μm running at 3 kV μ μ μ g

SpacingOzone Concentration

3 kV rms 4 kV rms3 kV rms 4 kV rms

0 μm 660 ppm

225 μm 550 ppm

For a device of such small scale these ozone levels are promising

500 μm 380 ppm

J Mahoney W Zhu VS Johnson KH Becker and JL Lopez Electrical and optical emissionmeasurements of a capillary dielectric barrier discharge European Physics Journal D Vol 60 441-447(2010)

QuestionsQuestions

Thank YouFor more informationProf Jose L Lopez PhD

Thank YouFor more informationDepartment of Physics

Telephone (973) 761-9057Email joselopez1shuedu

Website wwwshueduacademicsartsciphysicsWebsite wwwshueduacademicsartsciphysics

Page 92: Dielectric Barrier Discharge (DBD) & Progress in Large ...bonitz/si12/talks/august_8/lopez_si12.pdf · Dielectric Barrier Discharge (DBD) & Progress in Large-Scale Ozone Generation

Scientific ApproachScientific ApproachTheoretical Experimental

pppp

c [wt]

f [Hz]

c [wt]

f [Hz]

[kW]UUUβ1

1Cf4αPn

1iiminpeakimin

iiD

q [kWm2]q [kWm2]

150

180

][V]voltagepeakUpeak

[]cylinder perslicesofamountnsliceii

whereth

09 00

30

60

90

120

effic

ienc

y [

][0tdj t bl[F]sliceisdielectricofecapacitancC

[Hz]frequencyf[V]sliceivoltageminimumiUmin

thiD

th

10

28

46

64

82

39

107

176

244 power density

[kWm2]

ozone conc [wt][]CCβ

][0parameteradjustableα

iDiGi

Impact of Power Inductionp

350

400

wer

200

250

300

App

lied

Pow

Arr C 2Arr D +0

Arr E +45Arr F +7

Arr G +3

5 0

100

150

Frac

tion

of

1 2 3 4

ReferenceArr B unstable

Arr C -2

00

50

4Position (1inlet 4outlet)

Experimental Test Rigp g

Experimental Test Rigp g

Outer grounded electrode (left picture) and the dielectric covered inner electrodes (right) d e ect c cove ed e e ect odes ( g t)

Reference (Traditional) Arrangement

Inlet OutletGas flow direction

Optimized Arrangement

Inlet OutletGas flow direction

Intelligent Gap System (IGS)g p y ( )

Molecular Oxygen (O2) Ozone (O3)

O2 O3

yg ( 2) ( 3)

Particle Size SynthesisParticle Size SynthesisByBy--Products Cluster FormationProducts Cluster Formationyy

high diffusion and deposition to surfaces

low diffusion rate good transport

high sedimentation on the structurehigh sedimentation on the structure

Degreacutemont Technologies ndash OzoniaIntelligent Gap SystemIntelligent Gap System

G Vezzuacute JL Lopez A Freilich and K Becker Optimizationof Large-Scale Ozone Generators IEEE Transactions onPlasma Science Vol 37 No 6 p 890-896 (2009)

ConclusionsConclusionsConclusionsConclusionsFundamentals of ozone synthesis in a DBD plasmay p

ndash Highly filamented DBD discharges are best-suitedfor the production of ozone concentrations in therange of 6 to 14 wtrange of 6 to 14 wt

ndash The preferred characteristic of the microdischargesare Townsend-like at reduced electric fields Enaround 190 Townsend

ndash Detrimental side-effects induced by by-productscan be avoided by a proper design of the electrodecan be avoided by a proper design of the electrodearrangement The phenomenon is related to thediffusion rates of formed by-product clusters

ConclusionsConclusionsConclusionsConclusionsBenefits from DBD microplasma tailoring

ndash Reduced power consumption of up to 10 improvement

ndash Increased ozone concentrations of up to 14 now achievable

ndash Improved neutralization and conditioning of detrimental by-products

ndash Reduced system capital and operational cost

New technologies to improve ozone p

generatorg

HV Pulsed Power SwitchingHV Pulsed Power Switching

Microchannel Generation of Ozone

Channel ArrayChannel Array

Microchannel

330 microm 230 microm

Some Cap-DBD Devices Operating in Air

Increase of 60 of

Spacing 225 μmof 60 of plasma

No space

Cap‐DBD ozone generation

bull Ozone concentration is evaluated via Eco S d l UV 100 O A l (0 01Sensors model UV-100 Ozone Analyzer (001 ndash 900 ppm wiht an accuracy of plusmn2)

bull Three reactors 6 tubings 6rdquo with spacings of 0 μm 225 μm and 500 μm running at 3 kV μ μ μ g

SpacingOzone Concentration

3 kV rms 4 kV rms3 kV rms 4 kV rms

0 μm 660 ppm

225 μm 550 ppm

For a device of such small scale these ozone levels are promising

500 μm 380 ppm

J Mahoney W Zhu VS Johnson KH Becker and JL Lopez Electrical and optical emissionmeasurements of a capillary dielectric barrier discharge European Physics Journal D Vol 60 441-447(2010)

QuestionsQuestions

Thank YouFor more informationProf Jose L Lopez PhD

Thank YouFor more informationDepartment of Physics

Telephone (973) 761-9057Email joselopez1shuedu

Website wwwshueduacademicsartsciphysicsWebsite wwwshueduacademicsartsciphysics

Page 93: Dielectric Barrier Discharge (DBD) & Progress in Large ...bonitz/si12/talks/august_8/lopez_si12.pdf · Dielectric Barrier Discharge (DBD) & Progress in Large-Scale Ozone Generation

Impact of Power Inductionp

350

400

wer

200

250

300

App

lied

Pow

Arr C 2Arr D +0

Arr E +45Arr F +7

Arr G +3

5 0

100

150

Frac

tion

of

1 2 3 4

ReferenceArr B unstable

Arr C -2

00

50

4Position (1inlet 4outlet)

Experimental Test Rigp g

Experimental Test Rigp g

Outer grounded electrode (left picture) and the dielectric covered inner electrodes (right) d e ect c cove ed e e ect odes ( g t)

Reference (Traditional) Arrangement

Inlet OutletGas flow direction

Optimized Arrangement

Inlet OutletGas flow direction

Intelligent Gap System (IGS)g p y ( )

Molecular Oxygen (O2) Ozone (O3)

O2 O3

yg ( 2) ( 3)

Particle Size SynthesisParticle Size SynthesisByBy--Products Cluster FormationProducts Cluster Formationyy

high diffusion and deposition to surfaces

low diffusion rate good transport

high sedimentation on the structurehigh sedimentation on the structure

Degreacutemont Technologies ndash OzoniaIntelligent Gap SystemIntelligent Gap System

G Vezzuacute JL Lopez A Freilich and K Becker Optimizationof Large-Scale Ozone Generators IEEE Transactions onPlasma Science Vol 37 No 6 p 890-896 (2009)

ConclusionsConclusionsConclusionsConclusionsFundamentals of ozone synthesis in a DBD plasmay p

ndash Highly filamented DBD discharges are best-suitedfor the production of ozone concentrations in therange of 6 to 14 wtrange of 6 to 14 wt

ndash The preferred characteristic of the microdischargesare Townsend-like at reduced electric fields Enaround 190 Townsend

ndash Detrimental side-effects induced by by-productscan be avoided by a proper design of the electrodecan be avoided by a proper design of the electrodearrangement The phenomenon is related to thediffusion rates of formed by-product clusters

ConclusionsConclusionsConclusionsConclusionsBenefits from DBD microplasma tailoring

ndash Reduced power consumption of up to 10 improvement

ndash Increased ozone concentrations of up to 14 now achievable

ndash Improved neutralization and conditioning of detrimental by-products

ndash Reduced system capital and operational cost

New technologies to improve ozone p

generatorg

HV Pulsed Power SwitchingHV Pulsed Power Switching

Microchannel Generation of Ozone

Channel ArrayChannel Array

Microchannel

330 microm 230 microm

Some Cap-DBD Devices Operating in Air

Increase of 60 of

Spacing 225 μmof 60 of plasma

No space

Cap‐DBD ozone generation

bull Ozone concentration is evaluated via Eco S d l UV 100 O A l (0 01Sensors model UV-100 Ozone Analyzer (001 ndash 900 ppm wiht an accuracy of plusmn2)

bull Three reactors 6 tubings 6rdquo with spacings of 0 μm 225 μm and 500 μm running at 3 kV μ μ μ g

SpacingOzone Concentration

3 kV rms 4 kV rms3 kV rms 4 kV rms

0 μm 660 ppm

225 μm 550 ppm

For a device of such small scale these ozone levels are promising

500 μm 380 ppm

J Mahoney W Zhu VS Johnson KH Becker and JL Lopez Electrical and optical emissionmeasurements of a capillary dielectric barrier discharge European Physics Journal D Vol 60 441-447(2010)

QuestionsQuestions

Thank YouFor more informationProf Jose L Lopez PhD

Thank YouFor more informationDepartment of Physics

Telephone (973) 761-9057Email joselopez1shuedu

Website wwwshueduacademicsartsciphysicsWebsite wwwshueduacademicsartsciphysics

Page 94: Dielectric Barrier Discharge (DBD) & Progress in Large ...bonitz/si12/talks/august_8/lopez_si12.pdf · Dielectric Barrier Discharge (DBD) & Progress in Large-Scale Ozone Generation

Experimental Test Rigp g

Experimental Test Rigp g

Outer grounded electrode (left picture) and the dielectric covered inner electrodes (right) d e ect c cove ed e e ect odes ( g t)

Reference (Traditional) Arrangement

Inlet OutletGas flow direction

Optimized Arrangement

Inlet OutletGas flow direction

Intelligent Gap System (IGS)g p y ( )

Molecular Oxygen (O2) Ozone (O3)

O2 O3

yg ( 2) ( 3)

Particle Size SynthesisParticle Size SynthesisByBy--Products Cluster FormationProducts Cluster Formationyy

high diffusion and deposition to surfaces

low diffusion rate good transport

high sedimentation on the structurehigh sedimentation on the structure

Degreacutemont Technologies ndash OzoniaIntelligent Gap SystemIntelligent Gap System

G Vezzuacute JL Lopez A Freilich and K Becker Optimizationof Large-Scale Ozone Generators IEEE Transactions onPlasma Science Vol 37 No 6 p 890-896 (2009)

ConclusionsConclusionsConclusionsConclusionsFundamentals of ozone synthesis in a DBD plasmay p

ndash Highly filamented DBD discharges are best-suitedfor the production of ozone concentrations in therange of 6 to 14 wtrange of 6 to 14 wt

ndash The preferred characteristic of the microdischargesare Townsend-like at reduced electric fields Enaround 190 Townsend

ndash Detrimental side-effects induced by by-productscan be avoided by a proper design of the electrodecan be avoided by a proper design of the electrodearrangement The phenomenon is related to thediffusion rates of formed by-product clusters

ConclusionsConclusionsConclusionsConclusionsBenefits from DBD microplasma tailoring

ndash Reduced power consumption of up to 10 improvement

ndash Increased ozone concentrations of up to 14 now achievable

ndash Improved neutralization and conditioning of detrimental by-products

ndash Reduced system capital and operational cost

New technologies to improve ozone p

generatorg

HV Pulsed Power SwitchingHV Pulsed Power Switching

Microchannel Generation of Ozone

Channel ArrayChannel Array

Microchannel

330 microm 230 microm

Some Cap-DBD Devices Operating in Air

Increase of 60 of

Spacing 225 μmof 60 of plasma

No space

Cap‐DBD ozone generation

bull Ozone concentration is evaluated via Eco S d l UV 100 O A l (0 01Sensors model UV-100 Ozone Analyzer (001 ndash 900 ppm wiht an accuracy of plusmn2)

bull Three reactors 6 tubings 6rdquo with spacings of 0 μm 225 μm and 500 μm running at 3 kV μ μ μ g

SpacingOzone Concentration

3 kV rms 4 kV rms3 kV rms 4 kV rms

0 μm 660 ppm

225 μm 550 ppm

For a device of such small scale these ozone levels are promising

500 μm 380 ppm

J Mahoney W Zhu VS Johnson KH Becker and JL Lopez Electrical and optical emissionmeasurements of a capillary dielectric barrier discharge European Physics Journal D Vol 60 441-447(2010)

QuestionsQuestions

Thank YouFor more informationProf Jose L Lopez PhD

Thank YouFor more informationDepartment of Physics

Telephone (973) 761-9057Email joselopez1shuedu

Website wwwshueduacademicsartsciphysicsWebsite wwwshueduacademicsartsciphysics

Page 95: Dielectric Barrier Discharge (DBD) & Progress in Large ...bonitz/si12/talks/august_8/lopez_si12.pdf · Dielectric Barrier Discharge (DBD) & Progress in Large-Scale Ozone Generation

Experimental Test Rigp g

Outer grounded electrode (left picture) and the dielectric covered inner electrodes (right) d e ect c cove ed e e ect odes ( g t)

Reference (Traditional) Arrangement

Inlet OutletGas flow direction

Optimized Arrangement

Inlet OutletGas flow direction

Intelligent Gap System (IGS)g p y ( )

Molecular Oxygen (O2) Ozone (O3)

O2 O3

yg ( 2) ( 3)

Particle Size SynthesisParticle Size SynthesisByBy--Products Cluster FormationProducts Cluster Formationyy

high diffusion and deposition to surfaces

low diffusion rate good transport

high sedimentation on the structurehigh sedimentation on the structure

Degreacutemont Technologies ndash OzoniaIntelligent Gap SystemIntelligent Gap System

G Vezzuacute JL Lopez A Freilich and K Becker Optimizationof Large-Scale Ozone Generators IEEE Transactions onPlasma Science Vol 37 No 6 p 890-896 (2009)

ConclusionsConclusionsConclusionsConclusionsFundamentals of ozone synthesis in a DBD plasmay p

ndash Highly filamented DBD discharges are best-suitedfor the production of ozone concentrations in therange of 6 to 14 wtrange of 6 to 14 wt

ndash The preferred characteristic of the microdischargesare Townsend-like at reduced electric fields Enaround 190 Townsend

ndash Detrimental side-effects induced by by-productscan be avoided by a proper design of the electrodecan be avoided by a proper design of the electrodearrangement The phenomenon is related to thediffusion rates of formed by-product clusters

ConclusionsConclusionsConclusionsConclusionsBenefits from DBD microplasma tailoring

ndash Reduced power consumption of up to 10 improvement

ndash Increased ozone concentrations of up to 14 now achievable

ndash Improved neutralization and conditioning of detrimental by-products

ndash Reduced system capital and operational cost

New technologies to improve ozone p

generatorg

HV Pulsed Power SwitchingHV Pulsed Power Switching

Microchannel Generation of Ozone

Channel ArrayChannel Array

Microchannel

330 microm 230 microm

Some Cap-DBD Devices Operating in Air

Increase of 60 of

Spacing 225 μmof 60 of plasma

No space

Cap‐DBD ozone generation

bull Ozone concentration is evaluated via Eco S d l UV 100 O A l (0 01Sensors model UV-100 Ozone Analyzer (001 ndash 900 ppm wiht an accuracy of plusmn2)

bull Three reactors 6 tubings 6rdquo with spacings of 0 μm 225 μm and 500 μm running at 3 kV μ μ μ g

SpacingOzone Concentration

3 kV rms 4 kV rms3 kV rms 4 kV rms

0 μm 660 ppm

225 μm 550 ppm

For a device of such small scale these ozone levels are promising

500 μm 380 ppm

J Mahoney W Zhu VS Johnson KH Becker and JL Lopez Electrical and optical emissionmeasurements of a capillary dielectric barrier discharge European Physics Journal D Vol 60 441-447(2010)

QuestionsQuestions

Thank YouFor more informationProf Jose L Lopez PhD

Thank YouFor more informationDepartment of Physics

Telephone (973) 761-9057Email joselopez1shuedu

Website wwwshueduacademicsartsciphysicsWebsite wwwshueduacademicsartsciphysics

Page 96: Dielectric Barrier Discharge (DBD) & Progress in Large ...bonitz/si12/talks/august_8/lopez_si12.pdf · Dielectric Barrier Discharge (DBD) & Progress in Large-Scale Ozone Generation

Reference (Traditional) Arrangement

Inlet OutletGas flow direction

Optimized Arrangement

Inlet OutletGas flow direction

Intelligent Gap System (IGS)g p y ( )

Molecular Oxygen (O2) Ozone (O3)

O2 O3

yg ( 2) ( 3)

Particle Size SynthesisParticle Size SynthesisByBy--Products Cluster FormationProducts Cluster Formationyy

high diffusion and deposition to surfaces

low diffusion rate good transport

high sedimentation on the structurehigh sedimentation on the structure

Degreacutemont Technologies ndash OzoniaIntelligent Gap SystemIntelligent Gap System

G Vezzuacute JL Lopez A Freilich and K Becker Optimizationof Large-Scale Ozone Generators IEEE Transactions onPlasma Science Vol 37 No 6 p 890-896 (2009)

ConclusionsConclusionsConclusionsConclusionsFundamentals of ozone synthesis in a DBD plasmay p

ndash Highly filamented DBD discharges are best-suitedfor the production of ozone concentrations in therange of 6 to 14 wtrange of 6 to 14 wt

ndash The preferred characteristic of the microdischargesare Townsend-like at reduced electric fields Enaround 190 Townsend

ndash Detrimental side-effects induced by by-productscan be avoided by a proper design of the electrodecan be avoided by a proper design of the electrodearrangement The phenomenon is related to thediffusion rates of formed by-product clusters

ConclusionsConclusionsConclusionsConclusionsBenefits from DBD microplasma tailoring

ndash Reduced power consumption of up to 10 improvement

ndash Increased ozone concentrations of up to 14 now achievable

ndash Improved neutralization and conditioning of detrimental by-products

ndash Reduced system capital and operational cost

New technologies to improve ozone p

generatorg

HV Pulsed Power SwitchingHV Pulsed Power Switching

Microchannel Generation of Ozone

Channel ArrayChannel Array

Microchannel

330 microm 230 microm

Some Cap-DBD Devices Operating in Air

Increase of 60 of

Spacing 225 μmof 60 of plasma

No space

Cap‐DBD ozone generation

bull Ozone concentration is evaluated via Eco S d l UV 100 O A l (0 01Sensors model UV-100 Ozone Analyzer (001 ndash 900 ppm wiht an accuracy of plusmn2)

bull Three reactors 6 tubings 6rdquo with spacings of 0 μm 225 μm and 500 μm running at 3 kV μ μ μ g

SpacingOzone Concentration

3 kV rms 4 kV rms3 kV rms 4 kV rms

0 μm 660 ppm

225 μm 550 ppm

For a device of such small scale these ozone levels are promising

500 μm 380 ppm

J Mahoney W Zhu VS Johnson KH Becker and JL Lopez Electrical and optical emissionmeasurements of a capillary dielectric barrier discharge European Physics Journal D Vol 60 441-447(2010)

QuestionsQuestions

Thank YouFor more informationProf Jose L Lopez PhD

Thank YouFor more informationDepartment of Physics

Telephone (973) 761-9057Email joselopez1shuedu

Website wwwshueduacademicsartsciphysicsWebsite wwwshueduacademicsartsciphysics

Page 97: Dielectric Barrier Discharge (DBD) & Progress in Large ...bonitz/si12/talks/august_8/lopez_si12.pdf · Dielectric Barrier Discharge (DBD) & Progress in Large-Scale Ozone Generation

Optimized Arrangement

Inlet OutletGas flow direction

Intelligent Gap System (IGS)g p y ( )

Molecular Oxygen (O2) Ozone (O3)

O2 O3

yg ( 2) ( 3)

Particle Size SynthesisParticle Size SynthesisByBy--Products Cluster FormationProducts Cluster Formationyy

high diffusion and deposition to surfaces

low diffusion rate good transport

high sedimentation on the structurehigh sedimentation on the structure

Degreacutemont Technologies ndash OzoniaIntelligent Gap SystemIntelligent Gap System

G Vezzuacute JL Lopez A Freilich and K Becker Optimizationof Large-Scale Ozone Generators IEEE Transactions onPlasma Science Vol 37 No 6 p 890-896 (2009)

ConclusionsConclusionsConclusionsConclusionsFundamentals of ozone synthesis in a DBD plasmay p

ndash Highly filamented DBD discharges are best-suitedfor the production of ozone concentrations in therange of 6 to 14 wtrange of 6 to 14 wt

ndash The preferred characteristic of the microdischargesare Townsend-like at reduced electric fields Enaround 190 Townsend

ndash Detrimental side-effects induced by by-productscan be avoided by a proper design of the electrodecan be avoided by a proper design of the electrodearrangement The phenomenon is related to thediffusion rates of formed by-product clusters

ConclusionsConclusionsConclusionsConclusionsBenefits from DBD microplasma tailoring

ndash Reduced power consumption of up to 10 improvement

ndash Increased ozone concentrations of up to 14 now achievable

ndash Improved neutralization and conditioning of detrimental by-products

ndash Reduced system capital and operational cost

New technologies to improve ozone p

generatorg

HV Pulsed Power SwitchingHV Pulsed Power Switching

Microchannel Generation of Ozone

Channel ArrayChannel Array

Microchannel

330 microm 230 microm

Some Cap-DBD Devices Operating in Air

Increase of 60 of

Spacing 225 μmof 60 of plasma

No space

Cap‐DBD ozone generation

bull Ozone concentration is evaluated via Eco S d l UV 100 O A l (0 01Sensors model UV-100 Ozone Analyzer (001 ndash 900 ppm wiht an accuracy of plusmn2)

bull Three reactors 6 tubings 6rdquo with spacings of 0 μm 225 μm and 500 μm running at 3 kV μ μ μ g

SpacingOzone Concentration

3 kV rms 4 kV rms3 kV rms 4 kV rms

0 μm 660 ppm

225 μm 550 ppm

For a device of such small scale these ozone levels are promising

500 μm 380 ppm

J Mahoney W Zhu VS Johnson KH Becker and JL Lopez Electrical and optical emissionmeasurements of a capillary dielectric barrier discharge European Physics Journal D Vol 60 441-447(2010)

QuestionsQuestions

Thank YouFor more informationProf Jose L Lopez PhD

Thank YouFor more informationDepartment of Physics

Telephone (973) 761-9057Email joselopez1shuedu

Website wwwshueduacademicsartsciphysicsWebsite wwwshueduacademicsartsciphysics

Page 98: Dielectric Barrier Discharge (DBD) & Progress in Large ...bonitz/si12/talks/august_8/lopez_si12.pdf · Dielectric Barrier Discharge (DBD) & Progress in Large-Scale Ozone Generation

Intelligent Gap System (IGS)g p y ( )

Molecular Oxygen (O2) Ozone (O3)

O2 O3

yg ( 2) ( 3)

Particle Size SynthesisParticle Size SynthesisByBy--Products Cluster FormationProducts Cluster Formationyy

high diffusion and deposition to surfaces

low diffusion rate good transport

high sedimentation on the structurehigh sedimentation on the structure

Degreacutemont Technologies ndash OzoniaIntelligent Gap SystemIntelligent Gap System

G Vezzuacute JL Lopez A Freilich and K Becker Optimizationof Large-Scale Ozone Generators IEEE Transactions onPlasma Science Vol 37 No 6 p 890-896 (2009)

ConclusionsConclusionsConclusionsConclusionsFundamentals of ozone synthesis in a DBD plasmay p

ndash Highly filamented DBD discharges are best-suitedfor the production of ozone concentrations in therange of 6 to 14 wtrange of 6 to 14 wt

ndash The preferred characteristic of the microdischargesare Townsend-like at reduced electric fields Enaround 190 Townsend

ndash Detrimental side-effects induced by by-productscan be avoided by a proper design of the electrodecan be avoided by a proper design of the electrodearrangement The phenomenon is related to thediffusion rates of formed by-product clusters

ConclusionsConclusionsConclusionsConclusionsBenefits from DBD microplasma tailoring

ndash Reduced power consumption of up to 10 improvement

ndash Increased ozone concentrations of up to 14 now achievable

ndash Improved neutralization and conditioning of detrimental by-products

ndash Reduced system capital and operational cost

New technologies to improve ozone p

generatorg

HV Pulsed Power SwitchingHV Pulsed Power Switching

Microchannel Generation of Ozone

Channel ArrayChannel Array

Microchannel

330 microm 230 microm

Some Cap-DBD Devices Operating in Air

Increase of 60 of

Spacing 225 μmof 60 of plasma

No space

Cap‐DBD ozone generation

bull Ozone concentration is evaluated via Eco S d l UV 100 O A l (0 01Sensors model UV-100 Ozone Analyzer (001 ndash 900 ppm wiht an accuracy of plusmn2)

bull Three reactors 6 tubings 6rdquo with spacings of 0 μm 225 μm and 500 μm running at 3 kV μ μ μ g

SpacingOzone Concentration

3 kV rms 4 kV rms3 kV rms 4 kV rms

0 μm 660 ppm

225 μm 550 ppm

For a device of such small scale these ozone levels are promising

500 μm 380 ppm

J Mahoney W Zhu VS Johnson KH Becker and JL Lopez Electrical and optical emissionmeasurements of a capillary dielectric barrier discharge European Physics Journal D Vol 60 441-447(2010)

QuestionsQuestions

Thank YouFor more informationProf Jose L Lopez PhD

Thank YouFor more informationDepartment of Physics

Telephone (973) 761-9057Email joselopez1shuedu

Website wwwshueduacademicsartsciphysicsWebsite wwwshueduacademicsartsciphysics

Page 99: Dielectric Barrier Discharge (DBD) & Progress in Large ...bonitz/si12/talks/august_8/lopez_si12.pdf · Dielectric Barrier Discharge (DBD) & Progress in Large-Scale Ozone Generation

Particle Size SynthesisParticle Size SynthesisByBy--Products Cluster FormationProducts Cluster Formationyy

high diffusion and deposition to surfaces

low diffusion rate good transport

high sedimentation on the structurehigh sedimentation on the structure

Degreacutemont Technologies ndash OzoniaIntelligent Gap SystemIntelligent Gap System

G Vezzuacute JL Lopez A Freilich and K Becker Optimizationof Large-Scale Ozone Generators IEEE Transactions onPlasma Science Vol 37 No 6 p 890-896 (2009)

ConclusionsConclusionsConclusionsConclusionsFundamentals of ozone synthesis in a DBD plasmay p

ndash Highly filamented DBD discharges are best-suitedfor the production of ozone concentrations in therange of 6 to 14 wtrange of 6 to 14 wt

ndash The preferred characteristic of the microdischargesare Townsend-like at reduced electric fields Enaround 190 Townsend

ndash Detrimental side-effects induced by by-productscan be avoided by a proper design of the electrodecan be avoided by a proper design of the electrodearrangement The phenomenon is related to thediffusion rates of formed by-product clusters

ConclusionsConclusionsConclusionsConclusionsBenefits from DBD microplasma tailoring

ndash Reduced power consumption of up to 10 improvement

ndash Increased ozone concentrations of up to 14 now achievable

ndash Improved neutralization and conditioning of detrimental by-products

ndash Reduced system capital and operational cost

New technologies to improve ozone p

generatorg

HV Pulsed Power SwitchingHV Pulsed Power Switching

Microchannel Generation of Ozone

Channel ArrayChannel Array

Microchannel

330 microm 230 microm

Some Cap-DBD Devices Operating in Air

Increase of 60 of

Spacing 225 μmof 60 of plasma

No space

Cap‐DBD ozone generation

bull Ozone concentration is evaluated via Eco S d l UV 100 O A l (0 01Sensors model UV-100 Ozone Analyzer (001 ndash 900 ppm wiht an accuracy of plusmn2)

bull Three reactors 6 tubings 6rdquo with spacings of 0 μm 225 μm and 500 μm running at 3 kV μ μ μ g

SpacingOzone Concentration

3 kV rms 4 kV rms3 kV rms 4 kV rms

0 μm 660 ppm

225 μm 550 ppm

For a device of such small scale these ozone levels are promising

500 μm 380 ppm

J Mahoney W Zhu VS Johnson KH Becker and JL Lopez Electrical and optical emissionmeasurements of a capillary dielectric barrier discharge European Physics Journal D Vol 60 441-447(2010)

QuestionsQuestions

Thank YouFor more informationProf Jose L Lopez PhD

Thank YouFor more informationDepartment of Physics

Telephone (973) 761-9057Email joselopez1shuedu

Website wwwshueduacademicsartsciphysicsWebsite wwwshueduacademicsartsciphysics

Page 100: Dielectric Barrier Discharge (DBD) & Progress in Large ...bonitz/si12/talks/august_8/lopez_si12.pdf · Dielectric Barrier Discharge (DBD) & Progress in Large-Scale Ozone Generation

Degreacutemont Technologies ndash OzoniaIntelligent Gap SystemIntelligent Gap System

G Vezzuacute JL Lopez A Freilich and K Becker Optimizationof Large-Scale Ozone Generators IEEE Transactions onPlasma Science Vol 37 No 6 p 890-896 (2009)

ConclusionsConclusionsConclusionsConclusionsFundamentals of ozone synthesis in a DBD plasmay p

ndash Highly filamented DBD discharges are best-suitedfor the production of ozone concentrations in therange of 6 to 14 wtrange of 6 to 14 wt

ndash The preferred characteristic of the microdischargesare Townsend-like at reduced electric fields Enaround 190 Townsend

ndash Detrimental side-effects induced by by-productscan be avoided by a proper design of the electrodecan be avoided by a proper design of the electrodearrangement The phenomenon is related to thediffusion rates of formed by-product clusters

ConclusionsConclusionsConclusionsConclusionsBenefits from DBD microplasma tailoring

ndash Reduced power consumption of up to 10 improvement

ndash Increased ozone concentrations of up to 14 now achievable

ndash Improved neutralization and conditioning of detrimental by-products

ndash Reduced system capital and operational cost

New technologies to improve ozone p

generatorg

HV Pulsed Power SwitchingHV Pulsed Power Switching

Microchannel Generation of Ozone

Channel ArrayChannel Array

Microchannel

330 microm 230 microm

Some Cap-DBD Devices Operating in Air

Increase of 60 of

Spacing 225 μmof 60 of plasma

No space

Cap‐DBD ozone generation

bull Ozone concentration is evaluated via Eco S d l UV 100 O A l (0 01Sensors model UV-100 Ozone Analyzer (001 ndash 900 ppm wiht an accuracy of plusmn2)

bull Three reactors 6 tubings 6rdquo with spacings of 0 μm 225 μm and 500 μm running at 3 kV μ μ μ g

SpacingOzone Concentration

3 kV rms 4 kV rms3 kV rms 4 kV rms

0 μm 660 ppm

225 μm 550 ppm

For a device of such small scale these ozone levels are promising

500 μm 380 ppm

J Mahoney W Zhu VS Johnson KH Becker and JL Lopez Electrical and optical emissionmeasurements of a capillary dielectric barrier discharge European Physics Journal D Vol 60 441-447(2010)

QuestionsQuestions

Thank YouFor more informationProf Jose L Lopez PhD

Thank YouFor more informationDepartment of Physics

Telephone (973) 761-9057Email joselopez1shuedu

Website wwwshueduacademicsartsciphysicsWebsite wwwshueduacademicsartsciphysics

Page 101: Dielectric Barrier Discharge (DBD) & Progress in Large ...bonitz/si12/talks/august_8/lopez_si12.pdf · Dielectric Barrier Discharge (DBD) & Progress in Large-Scale Ozone Generation

ConclusionsConclusionsConclusionsConclusionsFundamentals of ozone synthesis in a DBD plasmay p

ndash Highly filamented DBD discharges are best-suitedfor the production of ozone concentrations in therange of 6 to 14 wtrange of 6 to 14 wt

ndash The preferred characteristic of the microdischargesare Townsend-like at reduced electric fields Enaround 190 Townsend

ndash Detrimental side-effects induced by by-productscan be avoided by a proper design of the electrodecan be avoided by a proper design of the electrodearrangement The phenomenon is related to thediffusion rates of formed by-product clusters

ConclusionsConclusionsConclusionsConclusionsBenefits from DBD microplasma tailoring

ndash Reduced power consumption of up to 10 improvement

ndash Increased ozone concentrations of up to 14 now achievable

ndash Improved neutralization and conditioning of detrimental by-products

ndash Reduced system capital and operational cost

New technologies to improve ozone p

generatorg

HV Pulsed Power SwitchingHV Pulsed Power Switching

Microchannel Generation of Ozone

Channel ArrayChannel Array

Microchannel

330 microm 230 microm

Some Cap-DBD Devices Operating in Air

Increase of 60 of

Spacing 225 μmof 60 of plasma

No space

Cap‐DBD ozone generation

bull Ozone concentration is evaluated via Eco S d l UV 100 O A l (0 01Sensors model UV-100 Ozone Analyzer (001 ndash 900 ppm wiht an accuracy of plusmn2)

bull Three reactors 6 tubings 6rdquo with spacings of 0 μm 225 μm and 500 μm running at 3 kV μ μ μ g

SpacingOzone Concentration

3 kV rms 4 kV rms3 kV rms 4 kV rms

0 μm 660 ppm

225 μm 550 ppm

For a device of such small scale these ozone levels are promising

500 μm 380 ppm

J Mahoney W Zhu VS Johnson KH Becker and JL Lopez Electrical and optical emissionmeasurements of a capillary dielectric barrier discharge European Physics Journal D Vol 60 441-447(2010)

QuestionsQuestions

Thank YouFor more informationProf Jose L Lopez PhD

Thank YouFor more informationDepartment of Physics

Telephone (973) 761-9057Email joselopez1shuedu

Website wwwshueduacademicsartsciphysicsWebsite wwwshueduacademicsartsciphysics

Page 102: Dielectric Barrier Discharge (DBD) & Progress in Large ...bonitz/si12/talks/august_8/lopez_si12.pdf · Dielectric Barrier Discharge (DBD) & Progress in Large-Scale Ozone Generation

ConclusionsConclusionsConclusionsConclusionsBenefits from DBD microplasma tailoring

ndash Reduced power consumption of up to 10 improvement

ndash Increased ozone concentrations of up to 14 now achievable

ndash Improved neutralization and conditioning of detrimental by-products

ndash Reduced system capital and operational cost

New technologies to improve ozone p

generatorg

HV Pulsed Power SwitchingHV Pulsed Power Switching

Microchannel Generation of Ozone

Channel ArrayChannel Array

Microchannel

330 microm 230 microm

Some Cap-DBD Devices Operating in Air

Increase of 60 of

Spacing 225 μmof 60 of plasma

No space

Cap‐DBD ozone generation

bull Ozone concentration is evaluated via Eco S d l UV 100 O A l (0 01Sensors model UV-100 Ozone Analyzer (001 ndash 900 ppm wiht an accuracy of plusmn2)

bull Three reactors 6 tubings 6rdquo with spacings of 0 μm 225 μm and 500 μm running at 3 kV μ μ μ g

SpacingOzone Concentration

3 kV rms 4 kV rms3 kV rms 4 kV rms

0 μm 660 ppm

225 μm 550 ppm

For a device of such small scale these ozone levels are promising

500 μm 380 ppm

J Mahoney W Zhu VS Johnson KH Becker and JL Lopez Electrical and optical emissionmeasurements of a capillary dielectric barrier discharge European Physics Journal D Vol 60 441-447(2010)

QuestionsQuestions

Thank YouFor more informationProf Jose L Lopez PhD

Thank YouFor more informationDepartment of Physics

Telephone (973) 761-9057Email joselopez1shuedu

Website wwwshueduacademicsartsciphysicsWebsite wwwshueduacademicsartsciphysics

Page 103: Dielectric Barrier Discharge (DBD) & Progress in Large ...bonitz/si12/talks/august_8/lopez_si12.pdf · Dielectric Barrier Discharge (DBD) & Progress in Large-Scale Ozone Generation

New technologies to improve ozone p

generatorg

HV Pulsed Power SwitchingHV Pulsed Power Switching

Microchannel Generation of Ozone

Channel ArrayChannel Array

Microchannel

330 microm 230 microm

Some Cap-DBD Devices Operating in Air

Increase of 60 of

Spacing 225 μmof 60 of plasma

No space

Cap‐DBD ozone generation

bull Ozone concentration is evaluated via Eco S d l UV 100 O A l (0 01Sensors model UV-100 Ozone Analyzer (001 ndash 900 ppm wiht an accuracy of plusmn2)

bull Three reactors 6 tubings 6rdquo with spacings of 0 μm 225 μm and 500 μm running at 3 kV μ μ μ g

SpacingOzone Concentration

3 kV rms 4 kV rms3 kV rms 4 kV rms

0 μm 660 ppm

225 μm 550 ppm

For a device of such small scale these ozone levels are promising

500 μm 380 ppm

J Mahoney W Zhu VS Johnson KH Becker and JL Lopez Electrical and optical emissionmeasurements of a capillary dielectric barrier discharge European Physics Journal D Vol 60 441-447(2010)

QuestionsQuestions

Thank YouFor more informationProf Jose L Lopez PhD

Thank YouFor more informationDepartment of Physics

Telephone (973) 761-9057Email joselopez1shuedu

Website wwwshueduacademicsartsciphysicsWebsite wwwshueduacademicsartsciphysics

Page 104: Dielectric Barrier Discharge (DBD) & Progress in Large ...bonitz/si12/talks/august_8/lopez_si12.pdf · Dielectric Barrier Discharge (DBD) & Progress in Large-Scale Ozone Generation

HV Pulsed Power SwitchingHV Pulsed Power Switching

Microchannel Generation of Ozone

Channel ArrayChannel Array

Microchannel

330 microm 230 microm

Some Cap-DBD Devices Operating in Air

Increase of 60 of

Spacing 225 μmof 60 of plasma

No space

Cap‐DBD ozone generation

bull Ozone concentration is evaluated via Eco S d l UV 100 O A l (0 01Sensors model UV-100 Ozone Analyzer (001 ndash 900 ppm wiht an accuracy of plusmn2)

bull Three reactors 6 tubings 6rdquo with spacings of 0 μm 225 μm and 500 μm running at 3 kV μ μ μ g

SpacingOzone Concentration

3 kV rms 4 kV rms3 kV rms 4 kV rms

0 μm 660 ppm

225 μm 550 ppm

For a device of such small scale these ozone levels are promising

500 μm 380 ppm

J Mahoney W Zhu VS Johnson KH Becker and JL Lopez Electrical and optical emissionmeasurements of a capillary dielectric barrier discharge European Physics Journal D Vol 60 441-447(2010)

QuestionsQuestions

Thank YouFor more informationProf Jose L Lopez PhD

Thank YouFor more informationDepartment of Physics

Telephone (973) 761-9057Email joselopez1shuedu

Website wwwshueduacademicsartsciphysicsWebsite wwwshueduacademicsartsciphysics

Page 105: Dielectric Barrier Discharge (DBD) & Progress in Large ...bonitz/si12/talks/august_8/lopez_si12.pdf · Dielectric Barrier Discharge (DBD) & Progress in Large-Scale Ozone Generation

Microchannel Generation of Ozone

Channel ArrayChannel Array

Microchannel

330 microm 230 microm

Some Cap-DBD Devices Operating in Air

Increase of 60 of

Spacing 225 μmof 60 of plasma

No space

Cap‐DBD ozone generation

bull Ozone concentration is evaluated via Eco S d l UV 100 O A l (0 01Sensors model UV-100 Ozone Analyzer (001 ndash 900 ppm wiht an accuracy of plusmn2)

bull Three reactors 6 tubings 6rdquo with spacings of 0 μm 225 μm and 500 μm running at 3 kV μ μ μ g

SpacingOzone Concentration

3 kV rms 4 kV rms3 kV rms 4 kV rms

0 μm 660 ppm

225 μm 550 ppm

For a device of such small scale these ozone levels are promising

500 μm 380 ppm

J Mahoney W Zhu VS Johnson KH Becker and JL Lopez Electrical and optical emissionmeasurements of a capillary dielectric barrier discharge European Physics Journal D Vol 60 441-447(2010)

QuestionsQuestions

Thank YouFor more informationProf Jose L Lopez PhD

Thank YouFor more informationDepartment of Physics

Telephone (973) 761-9057Email joselopez1shuedu

Website wwwshueduacademicsartsciphysicsWebsite wwwshueduacademicsartsciphysics

Page 106: Dielectric Barrier Discharge (DBD) & Progress in Large ...bonitz/si12/talks/august_8/lopez_si12.pdf · Dielectric Barrier Discharge (DBD) & Progress in Large-Scale Ozone Generation

Some Cap-DBD Devices Operating in Air

Increase of 60 of

Spacing 225 μmof 60 of plasma

No space

Cap‐DBD ozone generation

bull Ozone concentration is evaluated via Eco S d l UV 100 O A l (0 01Sensors model UV-100 Ozone Analyzer (001 ndash 900 ppm wiht an accuracy of plusmn2)

bull Three reactors 6 tubings 6rdquo with spacings of 0 μm 225 μm and 500 μm running at 3 kV μ μ μ g

SpacingOzone Concentration

3 kV rms 4 kV rms3 kV rms 4 kV rms

0 μm 660 ppm

225 μm 550 ppm

For a device of such small scale these ozone levels are promising

500 μm 380 ppm

J Mahoney W Zhu VS Johnson KH Becker and JL Lopez Electrical and optical emissionmeasurements of a capillary dielectric barrier discharge European Physics Journal D Vol 60 441-447(2010)

QuestionsQuestions

Thank YouFor more informationProf Jose L Lopez PhD

Thank YouFor more informationDepartment of Physics

Telephone (973) 761-9057Email joselopez1shuedu

Website wwwshueduacademicsartsciphysicsWebsite wwwshueduacademicsartsciphysics

Page 107: Dielectric Barrier Discharge (DBD) & Progress in Large ...bonitz/si12/talks/august_8/lopez_si12.pdf · Dielectric Barrier Discharge (DBD) & Progress in Large-Scale Ozone Generation

Cap‐DBD ozone generation

bull Ozone concentration is evaluated via Eco S d l UV 100 O A l (0 01Sensors model UV-100 Ozone Analyzer (001 ndash 900 ppm wiht an accuracy of plusmn2)

bull Three reactors 6 tubings 6rdquo with spacings of 0 μm 225 μm and 500 μm running at 3 kV μ μ μ g

SpacingOzone Concentration

3 kV rms 4 kV rms3 kV rms 4 kV rms

0 μm 660 ppm

225 μm 550 ppm

For a device of such small scale these ozone levels are promising

500 μm 380 ppm

J Mahoney W Zhu VS Johnson KH Becker and JL Lopez Electrical and optical emissionmeasurements of a capillary dielectric barrier discharge European Physics Journal D Vol 60 441-447(2010)

QuestionsQuestions

Thank YouFor more informationProf Jose L Lopez PhD

Thank YouFor more informationDepartment of Physics

Telephone (973) 761-9057Email joselopez1shuedu

Website wwwshueduacademicsartsciphysicsWebsite wwwshueduacademicsartsciphysics

Page 108: Dielectric Barrier Discharge (DBD) & Progress in Large ...bonitz/si12/talks/august_8/lopez_si12.pdf · Dielectric Barrier Discharge (DBD) & Progress in Large-Scale Ozone Generation

QuestionsQuestions

Thank YouFor more informationProf Jose L Lopez PhD

Thank YouFor more informationDepartment of Physics

Telephone (973) 761-9057Email joselopez1shuedu

Website wwwshueduacademicsartsciphysicsWebsite wwwshueduacademicsartsciphysics

Page 109: Dielectric Barrier Discharge (DBD) & Progress in Large ...bonitz/si12/talks/august_8/lopez_si12.pdf · Dielectric Barrier Discharge (DBD) & Progress in Large-Scale Ozone Generation

Thank YouFor more informationProf Jose L Lopez PhD

Thank YouFor more informationDepartment of Physics

Telephone (973) 761-9057Email joselopez1shuedu

Website wwwshueduacademicsartsciphysicsWebsite wwwshueduacademicsartsciphysics