Oil & Gas Processing Plants

Design and Operation

Training Course

DGEP/SCR/ED/ECP - 24th March-4th April 2003

GAS SWEETENING PROCESSES

DGEP/SCR/ED/ECP - 24th March-4th April 2003

DGEP/SCR/ED/ECP 3

GAS SWEETENING

• SALES GAS SPECIFICATION- To meet the H2S content Specification

H2S Content < 4 ppm Vol.

- To increase THE GROSS CALORIFIC VALUE

CO2 Removal

• PROCESS CONSTRAINTS- CRYOGENIC PROCESSES (Ethane extraction, LNG Manufacture) CO2

Solidification at temperatures below - 70/80°C

• CRUDE SWEETENING USING STRIPPING GAS- To remove H2S From the Stripping Gas

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GAS SWEETENING PROCESSES

PROCESSES DEPENDING ON CONTAMINANTS TO BE REMOVED :

• CO2 ONLY

• H2S ONLY

• CO2 & H2S SIMULTANEOUSLY

• SELECTIVE REMOVAL OF H2S

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GAS SWEETENING PROCESSES

• CHEMICAL ABSORPTION

• PHYSICAL ABSORPTION

• PHYSICO- CHEMICAL ABSORPTION

• PHYSICAL ADSORPTION

• CRYOGENIC PROCESS (CO2 Removal only)

• MEMBRANES

• Direct Conversion To SULPHUR

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• CHEMICAL ABSORPTION

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CHEMICAL ABSORPTION

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CHEMICAL ABSORPTION

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CHEMICAL ABSORPTION

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CHEMICAL ABSORPTION

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CHEMICAL ABSORPTION

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DEA PROCESS

• ADVANTAGES :- No degradation by COS & CS2- Absorption of mercaptans- Good stability- low absorption of HC- No reclaimer- reduced vaporization losses- public

• DISADVANTAGES :- Higher circulation rate (lower activity)- Higher utility requirements- Oxydation- No selectivity between H2S & CO2

• UTILIZATION : H2S, CO2, COS, CS2, RSH (up to 20%)

• SPLIT FLOW

• SNEA-DEA : higher concentration

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MDEA PROCESS

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MDEA PROCESS

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CHEMICAL ABSORPTION

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HOT CARBONATE PROCESS

• ADVANTAGES :- No degradation by COS & CS2- Good chemical stability- No reaction with air- low absorption of HC- No reclaimer- Low heat requirement (50% of corresponding amine unit)

• DISADVANTAGES :- Low reactivity with H2S- No mercaptans absorption- higher water content of treated gas- licensing fee

• UTILIZATION : HIGH CO2- if H2S in two steps :

K2CO3 + mol. Sieves

K2CO3 + AMINE

• SPLIT FLOW : solution cooling / two stages process / LO HEAT

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HOT CARBONATE PROCESS

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HOT CARBONATE PROCESS

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• PHYSICAL ABSORPTION

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PHYSICAL ABSORPTION

• WATER WASH : partial treatment• SELEXOL PROCESS : NORTON (dimethyl ether of polyethylene glycol)

- up to 65% of CO2- light gas sweetening- regeneration by flash

• FLUOR SOLVENT : propylene carbonate

- up to 50% of CO2- Gas dehydration by as solvent and heat regeneration

• PURISOL : LURGI

- Selective process to remove H2S even in case of low H2S/CO2 ratio- Gas dehydration by add solvent and heat regeneration

• RECTISOL : LURGI - Refrigerated solution of MeOH (high selectivity for CO2)

• ESTASOLVAN : UHDE

- Recompression of flashed gas

• SEPASOLV-MPE : BASF

- Recoompression of flashed gas

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SELEXOL PROCESS

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MORPHYSORB PROCESS

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PHYSICAL ABSORPTION

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AMINE PROCESS GUIDELINE

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PHYSICO-CHEMICAL PROCESS

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SULFINOL PROCESS

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• CHEMICO-PHYSICAL ABSORPTION

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SULIFINOL (SHELL)

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SULFINOL (SHELL)

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HYBRISOL PROCESS

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HYBRISOL PROCESS

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• PHYSICAL ADSORPTION

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PHYSICAL ADSORPTION

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PHYSICAL ADSORPTION

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CRYOGENIC PROCESS

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CO2 REMOVAL BY CRYOGENICS

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SPREX

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• PERMEATION (Membranes)

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MEMBRANE PROCESS

• MEMBRANE TECHNOLOGY For bulk removal of CO2

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LOW PRESSUREPERMEATE GAS

HIGH PRESSUREGAS MIXTURE RESIDUAL GAS

PERMEATE TUBERESIDUAL GAS

RESIDUAL GAS

HIGH PRESSURECHANNEL SPACER

PERMEATE CHANNEL SPACER

HIGH PRESSURE GAS MIXTURE

MEMBRANE/CLOTH COMPOSITE

HIGH PRESSURE GAS MIXTURE

Figure XI - B18 : SPIRAL WOUND ELEMENT CONSTRUCTION

DGEP/SCR/ED/ECP 42

CO2 RICH GAS

Seal Gasket

Epoxy coating

Aluminium TubeDiam. 3 to 4 cmHolesDiam. 5 to 7 mm

RESIDUE GAS

FibersBundleDiam. 4’’ and 9 1/2’’Length 1 m

FEED GAS

CO2 RICH GAS

(CYNARA)

Figure XI - B19 : HOLLOW FIBER MEMBRANE ELEMENT

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FIBER MEMBRANE

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FIBER MEMBRANE

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FIBER MEMBRANE

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TYPICAL ONE STAGE MEMBRANE PFD

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MEMBRANE PROCESS

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MEMBRANE PROCESS

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MEMBRANE PROCESS

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MEMBRANE PROCESS

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PROCESS COMPARISON

DIRECT CONVERSIONTO SULPHUR

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PROCESS COMPARISON

ABSORPTION :

H2S + 2 Fe3+(L) -------> 2 H+ + S° + 2 Fe2+(L)

REGENERATION :

1/2 O2 + H2O + 2 Fe2+(L) ------> 2 OH- + 2 Fe3+(L)

OVERALL :

H2S + 1/2 O2 -------> H2O + S°

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SULFINT (IFP)

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DIRECT CONVERSION TO SULPHUR

FIELD OF APPLICATIONLOW FLOWRATE• LOW PRESSURE (EXCEPT SULFINT FROM IFP)• LOW H2S CONTENT ( < 1000 ppm )

LICENSORS• US FILTER ( LO-CAT)• IFP with Le Gaz Intégral (SULFINT)• SHELL ( SULFEROX )

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PROCESS COMPARISON

GUIDE LINE FOR PROCESS SELECTION

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CHEMICAL ABSORPTION

ADVANTAGES DRAWBACKS

Not affected by acid gaspartial pressure

Low absorption of HC

In public domain

Reasonable cost ofsolvent

Extensive industrialreferences

High steamconsumption

Foaming tendency(except hot carbonate)

Boiler water for make-up

Corrosion tendency

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PHYSICAL ABSORPTION

ADVANTAGES DRAWBACKS

Low energy requirement

Low corrosion

Remove mercaptans

Low water content inproduced gas

No need of pure watermake-up

Depends on acid gaspartial pressure andtemperature

HC absorption (Clausunit affected)

High cost of solvents

Proprietary processes

Most of conclusions are valide for the physico-chemical processes

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PHYSICAL ADSORPTION

ADVANTAGES DRAWBACKS

Low CO2 content in theproduced gas

Low corrosion

May removemercaptans

Combined with waterdrying

Valid for low CO2 initialcontents

High regenerationtemperature (furnace)

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MEMBRANE

ADVANTAGES DRAWBACKS

Low energyrequirement

Low corrosion

Low water content inproduced gas

No need of puresolvent make-up

Can be operated un-manned (offshore)

Depends on acid gaspartial pressure andtemperature

High residual CO2content (a few percent)

Sensitive to somecontaminants

Low life time ofmembranes (3 to 5 years)

Proprietary processes

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GUIDELINE FOR PROCESS SELECTION

APPLICATION PROCESS NOTE

CO2 ABSORP.

BULKREMOVAL

LOW ACIDGASCONTENT

WATER WASH

MEMBRANE

DEA, aMDEA

HOTCARBONTE

PHYS.SOLVENTS

DEA, aMDEA

SMALLFLOWRATE

SENSIBLE TOCONTAMINANT

NOT WITH H2S

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GUIDELINE FOR PROCESS SELECTION

APPLICATION PROCESS NOTE

CO2 AND H2SABSORPTION DEA, a MDEA

PHYSICALSOLVENT

HC ABSORTION(CLAUS UNIT)

SELECTIVE H2SABSORPTION GENERIC

MDEA, ADIP

SULFINOL

HC ABSORTION(CLAUS UNIT)

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GUIDELINE FOR PROCESS SELECTION

APPLICATION PROCESS NOTE

POLISHING

IRON SPONGEZnOCHARCOAL

DIRECTCONVERSIONTO SULPHUR

WASTE SOLIDTO BETREATED

LOW FLOWANDPRESSURE(EXCEPTSULFINT)

SWEETENINGWITHMERCAPTANREMOVAL

AMINE WITHMOLECULARSIEVE

SULFINOL

NOT FULLYREFERENCED

HC ABSORTION(CLAUS UNIT)