Characterizing Source EmissionsCharacterizing Source EmissionsJohn G. Watson (johnw@dri.edu)

Judith C. Chow

Desert Research InstituteReno, NV, USA

Presented at

The Workshop on Air Quality Management, Measurement, Modeling, and Health Effects

University of Zagreb, Zagreb, Croatia

24 May 2007

ObjectivesObjectives

•Review past and current source sampling methods for PM emission rates and source profiles

• Illustrate recent testing protocols for dilution sampling systems

Important Emissions SourcesImportant Emissions Sources• Fugitive dust from wind erosion, agricultural activities,

construction, storage piles, and vehicle traffic on paved and unpaved roads.

• Ducted exhaust from industrial facilities (e.g., coal- and oil-fired power stations, smelting, cement plants, chemical plants, petroleum extraction and refining, glass manufacturing, paper making, shipping).

• Vehicle exhaust from cars, trucks, motorcycles, and buses.

• Burning and cooking from stoves, charbroilers, trash, forest fires, and agricultural burning.

• Ammonia from animal husbandry and fertilization.

Important Emissions CharacteristicsImportant Emissions Characteristics• Emissions Rate:

Amount emitted per unit time or unit of activity.

• Particle Size:Determines transport and deposition properties.

• Chemical Composition:Fractional abundance of gaseous and particulate chemical components in emissions. Used to speciate inventory and to apportion ambient concentrations to sources.

• Temporal Variation:Emissions change on daily, weekly, seasonal, and annual cycles. Timing of emissions affects atmospheric transport and dilution as well as human exposure to outdoor air pollution.

Emissions are Measured for Different Emissions are Measured for Different PurposesPurposes• Certification:

Verify that a process design is capable of achieving emissions below a regulated limit. (e.g., FTP engine tests)

• Compliance: Determine that in-use processes are within permitted values (e.g., vehicle smog tests, periodic stack tests, opacity tests)

• Emissions trading: Relate actual emissions to allowances (e.g., continuous SO2 monitors).

• Emission inventories: Real-world emissions for pollution planning.

• Source apportionment: Speciated emissions for source and receptor modeling.

•Emissions measured for one purpose are typically inaccurate for other purposes!

Emissions ModelEmissions Model

Component i emissions fluxes =

Σij fraction of component i in source j

x emission factor (mass/activity) for source j

x activity of source j

x [particle size fraction]

x [control efficiency]

x [temporal profile]

PM Source ProfilesPM Source ProfilesVehicle Exhaust

0.001

0.01

0.1

1

10

100

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ate

Sul

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Am

mon

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Sol

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as

Org

anic

Car

bon

Ele.

Car

bon

Alu

min

um

Silic

on

Pho

spor

us

Sul

fur

Chl

orin

e

Pota

ssiu

m

Cal

cium

Tita

nium

Va

nadi

um

Ch

rom

ium

Man

gane

se Iron

Nic

kel

Cop

per

Zin

c

Ars

enic

Sel

eniu

m

Bro

min

e

Str

ontiu

m

Lead

Chemical Compound

Ab

un

dan

ce

(%)

Wood Burning

0.001

0.01

0.1

1

10

100

Chl

orid

e

Nitr

ate

Sulfa

te

Amm

oniu

m

Sol

. Pot

as

Org

anic

Car

bon

Ele.

Car

bon

Alu

min

um

Silic

on

Phos

poru

s

Sulfu

r

Chl

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e

Pot

assi

um

Cal

cium

Tita

nium

Van

adiu

m

Chr

omiu

m

Man

gane

se Iron

Nick

el

Copp

er Zinc

Arse

nic

Sel

eniu

m

Brom

ine

Stro

ntiu

m

Lead

Chemical Compound

Abu

nda

nce

(%)

Road Dust

0.001

0.01

0.1

1

10

100

Chl

oride

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ate

Sul

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um

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as

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anic

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ese Iron

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Zinc

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enic

Sele

nium

Bro

mine

Str

ontiu

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Lead

Chemical Compound

Abu

ndan

ce (

%)

Coal-fired Power Plant

0.001

0.01

0.1

1

10

100

Chl

orid

e

Nitra

te

Sulfa

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ium

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as

Org

anic

Car

bon

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Alum

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Man

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Nick

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Cop

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Zinc

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Brom

ine

Stro

ntiu

m

Lead

Chemical Compound

Abu

ndan

ce (

%)

Emissions Rates/Factors Emissions Rates/Factors (PM(PM1010, PM, PM2.52.5, SO, SO22, NO, NOXX, NH, NH33))

• Existing gridded inventories: specialized modeling studies

• Emissions factor models: http://www.epa.gov/OMSWWW/models.htm http://www.epa.gov/ttn/chief/

• Continuous emission monitors: http://www.epa.gov/acidrain/edata.html

• Large point sources: http://www.epa.gov/airsweb/

Inventory GIS Activity LayersInventory GIS Activity Layers

• Land use and terrain: geological survey, satellite

• Population: Census

• Roadways: Census, mapping companies

• Soil and coal types: Soil Conservation Service

• Fuel volumes and composition: sales records, taxes, certification tests

• Light-medium commercial/industrial: Census, stock listings

• Large point sources: Census, production records

Important Sources of Primary PM Important Sources of Primary PM and Secondary Precursorsand Secondary Precursors

• PM Fugitive dust from wind erosion, agricultural activities, construction, storage piles, and vehicle traffic on paved and unpaved roads.

• PM, NOx, VOC, SO2 Ducted exhaust from industrial facilities (e.g., coal- and oil-fired power stations, smelting, cement plants, chemical plants, petroleum extraction and refining, glass manufacturing, paper making, shipping).

• PM, NOx, VOC, SO2 Vehicle exhaust from cars, trucks, motorcycles, and buses.

• PM, VOC Burning and cooking from stoves, charbroilers, trash, forest fires, and agricultural burning.

• NH3 Animal husbandry and fertilization.

Source Characterization Source Characterization Measurement MethodsMeasurement Methods

• Laboratory suspension: Dust or residue samples resuspended in laboratory chamber.

• Source-dominated sampling: Samples taken at locations and times when a single source dominates ambient concentrations.

• Vehicle dynamometer testing: Simulate driving cycles on fixed roller.

• Vehicle on-road testing: Roadside or tunnel, integrated or individual vehicle samples

• Diluted duct sampling: Samples drawn into aging chamber and cooled with clean air.

Laboratory Dust ResuspensionLaboratory Dust Resuspension

Source-Dominated SamplingSource-Dominated SamplingUnpaved Road Dust EmissionsUnpaved Road Dust Emissions

Road Dust EmissionsRoad Dust Emissions

•Use TRAKER (Testing Re-entrained Aerosol Kinetic Emissions from Roads) vehicle to map road dust emissions.

•Calibrate TRAKER with unpaved road dust emissions.

TRAKER MeasurementsTRAKER Measurements

Location of inlets (right side and

background shown).

Generator and pumps are mounted on a

platform on the back of the van.

TRAKER Measurements TRAKER Measurements (continued)

Two sampling plenums, DustTrak and GRIMM particle

monitors, and rotameters.

GPS logs the TRAKER’s position every 1

second.

Results from the Treasure Valley, Results from the Treasure Valley, Idaho, Road Dust StudyIdaho, Road Dust Study

Source-Dominated SamplingSource-Dominated Sampling(Cooking)(Cooking)

Real-World Cooking Simulated Cooking

New Vehicle Emissions Testing New Vehicle Emissions Testing MethodsMethods• Remote Sensing of Vehicle Emissions:

Allows emission rates to be determined for certain chemical components (VOC, NOX, CO, PM).

• Fast Response VOC and NOX Speciation Measurements and Normalizing to CO2: Can determine individual on-road vehicle emissions with respect to fuel consumption. Can be applied to other sources with high emissions of other gases.

• Dense Spatial Monitoring: Battery-powered PM monitors as well as passive VOC, NO2, and CO absorbers are located within and around source complexes. Emissions are inferred from complex dispersion models or spatial receptor models.

• Tunnel Studies: Measurements are taken in tunnels to minimize contamination from other sources (VOC, NOX, CO, PM).

Source-Dominated SamplingSource-Dominated Sampling((Vehicle Exhaust)Vehicle Exhaust)

Roadside sampling Diesel exhaust sampling

Estimate Emissions of Vehicle Estimate Emissions of Vehicle ExhaustExhaust

• Sample real-time CO2 and pollutants in a source-dominated environment to obtain fuel-based emissions factors.

• Use road tube counters to classify vehicles.

• Use area fuel sales to estimate emissions.

• Compare results with MOBILE6 emissions factors.

Estimate Vehicle Estimate Vehicle Exhaust Emission RateExhaust Emission Rate• Fourier Transform Infrared

Spectroscope measures CO2, CO, NO2, NO, and propane.

• Correlation of pollutants with CO2 yields fuel-based emissions factors.

• Real-time particle counters (e.g., Grimm 1.108) can quantify particles between 0.3 to 1.8 µm at 1-sec resolution.

Remote Sensing of In-Use Vehicle Remote Sensing of In-Use Vehicle ExhaustExhaust

TRANSMITTER

TerminusPlate

ExhaustPlume

BackscatteredLight

Lic #

DATAACQUISITION

Absorption and Backscatter

~10-15 m

RECEIVER

LORAX: Lidar On-Road Aerosol LORAX: Lidar On-Road Aerosol ExperimentExperiment

In-Plume Vehicle Emission SamplingIn-Plume Vehicle Emission Sampling

Ducted Emissions: Hot sampleDucted Emissions: Hot sample

• Total Suspended Particulate (TSP)

– EPA Method 17: in-stack filter (at stack temperature)

– EPA Method 5: heated out-of-stack filter (at 120 or 160 °C)

¤ EPA Method 5, 5A, 5B, 5C, 5D, 5F, 5G, 5H, 5I

• PM10 and PM2.5, including condensable PM

– Method 201A: combines Method 17 with in-stack 10 µm cyclone to collect PM10

– Method PRE-004: combines Method 201A with in-stack 2.5 µm cyclone to collect PM2.5

– EPA Method 202: collect condensable PM as those which pass through filter and are captured in water-filled bubblers (impingers) in an ice bath

Method 201/202 Filter/Impinger MethodsMethod 201/202 Filter/Impinger Methods

EPA Methods PRE4 & 202

Filterable PM

Condensable PM (<1 µm)

PM10 and PM2.5cyclones and

filter(in-stack)

VTT

Filter

Glass orTeflon®

probe liner(heated)Teflon®

tubing(heated

Sample gas is cooled to 60-70F in iced impingers

Analysis:

• Organic extraction

• Titration of inorganic fraction

• Dry and weigh organic and inorganic residue

• SO4= and Cl-

Analysis:

• Evaporation of rinses

• Gravimetric analysis

Post Test Purge with N2 or AirRange of chemical

speciation techniques is limited due to high

temperatures, moisture, interfering

particles & gases

Method 202 ArtifactMethod 202 Artifact

Findings

• Condensable PM2.5 may be overestimated using impinger-based methods

– Sulfate artifacts significant even for gas-fired sources

– If Method 202 is performed, a post-test nitrogen purge should always be done

– Further investigation of artifacts and differences between impinger and dilution sampling methods is needed

• Dilution sampling allows broader speciation of PM2.5 for improved speciation profiles

Difference in PMDifference in PM2.52.5 Mass Mass

between In-Stack and Dilution Samplingbetween In-Stack and Dilution SamplingGas-Fired Boiler - Field Data

0

0.002

0.004

0.006

0.008

0.01

0.012

0.014

0.016

0.018

Run 1 Run 2 Run 3 Run 1 Run 2 Run 3 AP42

lb/M

MB

tu

inorganic condensable (M202)organic condensable (M202)Filterable PM (M201A)PM2.5 (dilution)

Dilution Method

In-Stack Methods

Dilution Sampling of Dilution Sampling of Emissions from Meat CookingEmissions from Meat Cooking

Dilution Sampling SystemDilution Sampling System

aa

StackGas

HEPAFilter

CarbonFilter

Rotameter

VenturiProbe

T

RH

AmbientAir

Flow Control

Pump

ResidenceTime

ChamberPM2.5

Cyclones

To SampleCollection

Trains

•Stainless steel

•Cross-flow jet mixing

•Dilution Ratio 10-40:1

•Residence time 80-90 sec

Sample gas is cooled to ambient temperature by dilution with ambient air

Flow meter

PM10 Cyclone

Particle Characteristics Often Vary Particle Characteristics Often Vary During Emissions TestsDuring Emissions Tests(ELPI and Grimm OPC Size Distributions)(ELPI and Grimm OPC Size Distributions)

Mass concentration Number concentrationDp (um)

dp

0.1

1.0

2.5

Shakeout (15min)

Shakeout (15min)

Nucleation/ reactions from binder

Pouring

Loose sand mass

Recently Developed DRI/BEI Dilution SystemRecently Developed DRI/BEI Dilution System26”

12.5”

28”

8.5”

7”

3”A

B

C

A: 1.875 in

B: 5.875 in

C: 8.375 in

Inner Diameter

Thermocouple Positions on each Collar• Red points are

measurement points 0.5”, 1.25”, 1.75”, 2.25” and 2.875” (center) from inner wall.

• Grey rods indicate thermocouple locations and typical starting points for each thermocouple

Recently Developed DRI/BEI Dilution System Recently Developed DRI/BEI Dilution System (continued)(continued)

Thermocouples 1, 6, 10

Thermocouples 2, 7, 11

Thermocouples 3, 8, 13

Thermocouples 4, 9, 14

Thermocouples 5, 10, 15

Characterizing the DRI/BEI Dilution Characterizing the DRI/BEI Dilution SystemSystem

• Temperature profile at different depths and along various distances from inlet.

• Determine loses and mixing characteristic as a function of particle size, dilution ratios, and distance from inlet for polystyrene latex sphere (PSL) particles from 0.06 – 30 µm.

• Determine optimum range of dilution ratios and aging time using a diesel generator at idle and full load.

Diluted Stack Test FindingsDiluted Stack Test Findings

• Residence time and dilution ratio do not change particulate mass emission rate, but do affect size distribution and total number of particles emitted. Longer residence times shift particulate mass to larger size and decrease total number concentration.

• Higher dilution rates increase ultrafine particle concentrations.

ConclusionsConclusions• Road dust emission potential can be measured

continuously.

• Mobile emissions are more accurate from on-road sensing of many vehicles than from dynamometer testing of a few vehicles.

• Dilution sampling provides more accurate estimates of PM stack emission rates than hot stack and impinger samples.

• Chemical source profiles should be measured with emission rates.