Process Intensification with Downflow Gas Contactor (DGC ... tools and... · DGC Design DGC-...

Process Intensification with

Downflow Gas Contactor (DGC)

Reactor

Dr M G Palekar

STEP Pvt Ltd.

SERB- IGCW Award 2017

Process Intensification

Any engineering development that leads to

a substantially smaller, cleaner, safer and

more energy efficient technology.

Proprietary Technology

➢ DGC (Downflow Gas Contactor) Reactor

▪ Highly Efficient Mass Transfer

▪ Single stage system

▪ Contacting of liquid continuum with

dispersed gas or liquid

▪ Low energy usage

▪ Applicable to a wide range of

industrial processes

DGC Design➢ DGC- downflow co-current

device, is a cylinder or has a

cylindrical upper section &

inverted conical lower section (if

needed)

➢ Specially Designed Inlet (SDI)

➢ High velocity liquid generates

intense shear & energy; and

produces a highly agitated gas-

liquid dispersion with increased

interfacial area and improved

mass transfer.

➢ Suitable control system include

heating, cooling, pressure, flow

rates etc.

DGC- Bubble Dispersion

DGC- Key Advantages

➢ Lower power

consumption

➢ Smaller operating volumes

➢ Close 100% Gas

utilisation

➢ High gas hold-up: 40-50%

➢ Accurate control of

interfacial area (upto

6000 m2/m3)

➢ No internal moving parts

➢ Tolerance to particulates

➢ Ease of scale-up with no

loss of efficiency

DGC

Feed Vessel with heater

Control Panel

Receiver

High Pressure pump

Heat Exchanger

Specially Designed Inlet

Gas Absorption

Outlet gas concentration in relation to pressure

showing the close approach to equlibrium

of the DGC and a Venturi contacting device

Operating Pressure

Gas

Dis

solv

ed

in

Ou

tlet

Str

eam

(p

pm

)

Venturi

DGC

Equilibrium Value

Gas Absorption- Reactor Comparison

Gas Absorption as a Function of Pressurefor a variety of contacting devices

Operating Pressure

Gas

Abs

orbe

d (%

)

DGC

Stirred Tank Absorbers

Venturi

100

DGC- Industrial Applications

• Gas-Liquid and Liquid-liquid reactions

(Hydrogenation, Oxidation, Carbonylation, Amonolysis, Ethoxylation,

Chlorination, Biodiesel production)

• Effluent treatment (COD/ BOD reduction, Wet Air

Oxidation, Non-biodegradable effluent)

• Gas Absorption (CO2 capture from Biogas/ Flue gas,

Ammonia recovery)

DGC- Chemical Reactions

• Catalytic Hydrogenation- Vegetable oils, Itaconic

acid, Crotonaldehyde, Cinnamaldehyde, Glucose,

Benzaldehyde in slurry or packed bed form

• Hydrogenation- ozonised Rapeseed oil

• Catalytic Oxidation- p-cresol

• Biodiesel production- Edible, Non-edible & Waste oils

• New opportunities- sulfonation, alkylation,

chlorination, amonolysis

06-10-2017 12

Chemical Reaction- p-Cresol Oxidation

• Oxidation proceeded at rate of 0.02 kg of O2 /s/m3.

Reaction rate was limited by cooling capability of the

reactor setup.

• Reaction carried out at below 100 C and slight pressure in

presence of a catalyst.

• p-cresol conversion of 99.5% was obtained with selectivity

to p-hydroxybenzaldehyde above 90%.

• “Reaction rate was easy to control by controlling the

dispersion level, which makes the DGC system

flexible, safe and efficient.”

Chemical Reaction- Hydrogenation

• DGC has been employed as a slurry reactor with and without added tangential flow (swirl flow) for (i) itaconicacid hydrogenation (ii) rape seed oil hydrogenation and (iii) as a flxed bed reactor for itaconic acid and soybean oil hydrogenation using palladium and nickel catalysts.

• Due to the large values of mass transfer rate, all the reactions were operated under largely surface reaction controlled conditions.

• Hydrogenation of triglycerides was observed to occur with greater selectivity than in stirred reactors. Use of swirl flow further enhanced mass transfer and reaction rate.

Chemical Reaction: Biodiesel Production

• The experimental results showed high yield of biodiesel

compared to those in other biodiesel processes.

• Yield of >96.5% of FAME were achieved in a short contact

time of 2.5 min at low temp of 40 C, low molar ratio of

methanol (4.5:1) and lo catalyst loading of 0.43%.

• Biodiesel produced does not require water wash.

DGC- Biogas Upgrading

Biogas upgraded by removal of CO2 & H2S (Patent applied):

• 99+% absorption of CO2 and H2S • Methane concentration in the gas outlet attained > 98%• Absorbent solution used – ABSOLV- is water based• Biogas of improved quality with enhanced Calorific value• Significant cost savings for power generation.• Removal of H2S allows increased plant longevity• Upgraded Biogas can be used as CNG fuel for transportation.• Recovery of the absorbed CO2 from ABSOLV possible. Hence

ABSOLV can be recycled.Building a Pilot Plant for 50 m3/hr biogas in collaboration with United Envirotech Pvt. Ltd., Pune; to establish the technology

DGC- Effluent Treatment

• Can be used efficiently in biological waste & effluent

treatment and in Advanced Oxidation processes

• Operates with Air/ Oxygen/ Ozone/ H2O2/ UV or with a

catalyst (Titanium Dioxide), individually or in combination

• Photocatalytic process can breakdown “difficult” pollutants

• Effective in treatment of saturated and chloro-

hydrocarbons, solvents, pesticides, aromatics etc.

• Can be integrated into existing processes or used on

stand alone basis.

DGC- Effluent Treatment

COD Reduction in

• Industrial wastes (chlorophenols, propylene glycol,

methanol, cyclohexanedione, phenols, mixed alcohols,

sugar condensate, pharma & specialty chemicals,

acetaldehyde, nitrogen containing streams)

• Treatment of Landfill Leachates

• Food industry’s waste effluents (Dairy, Whey, Orange,

Beverage)

• Photocatalytic degradation of Chlorine & Chloroamines

in swimming pool water

• Treatment and breakdown of Endocrine Disruptors in

Sewage water

06-10-2017 18

Common Effluent Treatment Plant (CETP)

• The treatment was carried out using air or oxygen only

• Results of the trials were as shown below.

- COD reduction - ~ 55-80%

- BOD reduction- ~40%

- TSS reduction- ~ 38 to 48 %

- TDS reduction- ~ 30-50%

• Actual residence time for the material in the reactor was

65 to 100 min, whereas the trials were conducted for 6-8

hrs

MEE Condensate (Pharma Industry)

• Trials conducted for 5 hour

using air, H2O2 and UV

• COD reduced by 30 to 49 %

• TDS reduced by 15 to 93 %

• Ammonial Nitrogen reduced

by 10 to 36 %

• Actual residence time for the

material in the reactor was ~

25 to 30 min. 0

5000

10000

15000

20000

0 2 4 6C

OD

pp

m

time (hr)

COD Reduction

Commodity/specialty chemicals

• Three trials were conducted using Air +UV , Air+ UV +

H202 and only air.

• The results obtained using Air H2O2 and UV were

encouraging.

• COD: Reduced by 28 to 68%

• BOD : Reduced by 29 % to 70 % .The BOD results were

in line with COD results.

• Actual residence time for the material in the reactor is 25

min

• Strong initial odor was odorless at the end of the trial.

Phenols containing Stream

• The effluent contained

phenols

• 1 trial was conducted

using air & H202/UV for 6

hrs

• COD & BOD reduced by

80% .

• Actual residence time for

the material in the reactor

is ~25 to 30 min

Initial and treated effluent stream

Alcohol Stream

• This effluent contained couple of alcohols and nitrogen

containing chemicals

• H2O2 & air as oxidizing agents; trials for 4 hours.

• COD reduced by 35% in both the trials.

• BOD reduction was similar to COD by in both the trials (~

35%).

• Ammonical nitrogen reduced from 93 ppm to <1ppm in

both the trials. It is interesting and positive feature.

• The actual residence time for material in reactor was 35

min

Effluent Treatment- Dairy

• Milk waste Effluent

• Volume: 15 litres batch

• Treatment with air

Initial COD: 99000 mg/l, Final COD: 33000 mg/l; Time: 96 hrs

(67% COD reduction)

• Treatment with Oxygen

Initial COD: 99000 mg/l, Final COD: 9400 mg/l, Time: 95 hrs (90% COD reduction)

Welcome to the game-changing reactor –

DGC!