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Slide 1
SS TSS-07 Understanding Sour SystemTreatment using Amines
Laurie Wang, PhD, P.Eng.InvensysOctober 17, 2013
© 2013 Invensys. All Rights Reserved. The names, logos, and taglines identifying the products and services of Invensys are proprietary marks of Invensys or its subsidiaries.All third party trademarks and service marks are the proprietary marks of their respective owners.
Laurie Wang, PhD, P.Eng.InvensysOctober 17, 2013
Topics
• Amine-based gas treating processes
• Amine process modeling
Slide 3
Gas/NGL Sweetening and Treating
• Separation of acid gases from gas or liquid streams
Acid gases: H2S, CO2, SO2
Other impurities: COS, CS2, RSH (MeSH, EtSH), H2O, CO, VOCs, etc.
Sour Gas/NGL Acid Gases
Sweet Gas/NGL
Slide 4
• Separation of acid gases from gas or liquid streams
Acid gases: H2S, CO2, SO2
Other impurities: COS, CS2, RSH (MeSH, EtSH), H2O, CO, VOCs, etc.
Other impurities
Gas/NGL Sweetening and Treating
• Importance of acid gas removal
• Maintain safe environment from poisonous materials
• Prevent equipment and pipeline corrosion
• Prevent catalyst poisoning
• Maintain heating value
• Further chemical process
Slide 5
• Importance of acid gas removal
• Maintain safe environment from poisonous materials
• Prevent equipment and pipeline corrosion
• Prevent catalyst poisoning
• Maintain heating value
• Further chemical process
Industries that need gas treatingProcess Common clean up targets
Natural GasPurification
< 4 ppm H2S; < 1% CO2
Refinery Fuel GasTreating
< 100 ppm H2S
Synthetic Gas forChemicals
< 0.01 ppm H2S; < 500 ppm CO2
Slide 6
Synthetic Gas forChemicalsEthyleneManufacture
~ 1 ppm H2S; 1 ppm CO2
HydrogenManufacture
10 ppm H2S; < 0.1% CO2
Ammonia Synthesis <16% ppm CO2 + CO; 0.01 ppmH2S
Coal Gasification 0.01 ppm H2S; <500 ppm CO2
* Gas Treating with Chemical Solvents by Gianni Astarita, David Savage, and Attilio Bisio, 1983
Gas/NGL Sweetening and Treating
• Remove H2S from natural gas using amines• H2S is Toxic and Flammable
• Remove COS, CS2, Mercaptans if present
• Remove CO2 if economically favorable
• Common operating problems:
• Corrosion at high temperatures / concentration
• Foaming
• Amine losses• entrainment loss
• degradation loss
• solubility loss
• vaporization loss
Slide 7
• Remove H2S from natural gas using amines• H2S is Toxic and Flammable
• Remove COS, CS2, Mercaptans if present
• Remove CO2 if economically favorable
• Common operating problems:
• Corrosion at high temperatures / concentration
• Foaming
• Amine losses• entrainment loss
• degradation loss
• solubility loss
• vaporization loss
Gas/NGL Treating Technologies
• Aqueous alkanolamines (chemical solvents)
• Physical solvents (physical absorption)
• Physical-Chemical blended solvents
• Carbonate process
• Others• Molecular sieves
• Membranes
• Extractive distillations
Slide 8
• Aqueous alkanolamines (chemical solvents)
• Physical solvents (physical absorption)
• Physical-Chemical blended solvents
• Carbonate process
• Others• Molecular sieves
• Membranes
• Extractive distillations
Technology Based Gas Treating Facilities
Chem
. Sol
vent
s
Phy.
Sol
vent
s
Dire
ct C
onvn
Ext.
Dist
.
Mol
. Sie
ve
Mem
bran
es
Unkn
own
Plants
Capacity0%10%20%30%40%50%60%70%80%
Slide 9
Chem
. Sol
vent
s
Phy.
Sol
vent
s
Dire
ct C
onvn
Ext.
Dist
.
Mol
. Sie
ve
Mem
bran
es
Unkn
own
Plants
Capacity0%10%20%30%40%50%60%70%80%
* Schlumberger DBR
Chemical Solvents – Aqueous Amines• MEA – Monoethanolamine
• DEA – Diethanolamine
• MDEA - Methyldiethanolamine
• DGA – Diglycolamine
• DIPA – Diisopropanolamine
• TEA - Triethanolamine
Slide 10
• MEA – Monoethanolamine
• DEA – Diethanolamine
• MDEA - Methyldiethanolamine
• DGA – Diglycolamine
• DIPA – Diisopropanolamine
• TEA - Triethanolamine
Trends in Gas Treating Technologyusing Amines
MDEAMDEA
ProprietaryProprietarySolventsSolvents
19401940 19501950 19601960 19701970 19801980 19901990 20002000
Slide 11
MEAMEADEADEA
MDEAMDEA
ProprietaryProprietarySolventsSolvents
* Schlumberger DBR
Molecular Structures of Common Amines
• Amines are derivatives from ammonia with one or more of itshydrogen atoms being replaced by a substituent, such as an alkyl oraryl group
• In Primary Amines, only one of the hydrogen atoms in the ammoniamolecule is replaced
• In Secondary Amines, two of the hydrogen atoms in the ammoniamolecule are replaced
• In Tertiary Amines, all three hydrogen atoms in the ammoniamolecule are replaced
Slide 12
• Amines are derivatives from ammonia with one or more of itshydrogen atoms being replaced by a substituent, such as an alkyl oraryl group
• In Primary Amines, only one of the hydrogen atoms in the ammoniamolecule is replaced
• In Secondary Amines, two of the hydrogen atoms in the ammoniamolecule are replaced
• In Tertiary Amines, all three hydrogen atoms in the ammoniamolecule are replaced
Molecular Structures of Common Amines
H
Primary Amines
Monoethanolamine (MEA)
H
Diglycolamine (DGA)
Slide 13
H
HNCH2CH2OH
H
HNC2H4OC2H4OH
Molecular Structures of Common Amines
Secondary Amines
Diethanolamine (DEA)
CH2CH2OH
Diisopropanolamine (DIPA)
CH2CHOHCH3
Slide 14
NCH2CH2OH
CH2CH2OHH N
CH2CHOH
CH2CHOHH
CH3
Methyldiethanolamine (MDEA)
Molecular Structures of Common Amines
Tertiary Amines
CH2CH2OH
Triethanolamine (TEA)
CH2CH2OH
Slide 15
CH3 N
CH2CH2OH
CH2CH2OH
NCH2CH2OH
CH2CH2OHHOCH2CH2
Pros and Cons of Amines
Advantage Disadvantage1-/2- Amine(MEA / DEA)
• Fast reaction• Low solvent cost• Thermal stable
• Lack of selectivity• High energy cost• Highly corrosive
Slide 16
• Fast reaction• Low solvent cost• Thermal stable
• Lack of selectivity• High energy cost• Highly corrosive
3- Amine(MDEA)
• Selectivity• Less energy cost• Less corrosive• High resistance to degradation
• Slow reactions with CO2• High solvent cost• Minimal COS/CS2 removal
Physical Solvents
• Water
• Methanol (trade name Rectisol by Linde and Lurgi)
• DEPG, dimethyl ethers of polyethylene glycol, (Selexol by UnionCarbide, DOW, UOP, and Coastal by AGR)
• Tetramethylene sulfone (Sulfolane by Shell)
• Glycols (EG, DEG, and TEG)
• NMP, n-methyl pyrrolidone (Purisol by Lurgi)
• Propylene Carbonate (Flour SolventTM)
Slide 17
• Water
• Methanol (trade name Rectisol by Linde and Lurgi)
• DEPG, dimethyl ethers of polyethylene glycol, (Selexol by UnionCarbide, DOW, UOP, and Coastal by AGR)
• Tetramethylene sulfone (Sulfolane by Shell)
• Glycols (EG, DEG, and TEG)
• NMP, n-methyl pyrrolidone (Purisol by Lurgi)
• Propylene Carbonate (Flour SolventTM)
Pros and Cons of Physical Solvents
Advantage Disadvantage
• Little heat needed for solvent recovery• Low operating costs• Treatment of high acid gas contents• Possible for simultaneous gas dehydration
• High capital cost• High solvent cost
Slide 18
• Little heat needed for solvent recovery• Low operating costs• Treatment of high acid gas contents• Possible for simultaneous gas dehydration
Proprietary Solvents
• Sulfinol-D, Sulfinol-M, Sulfinol-X (Shell)
• Selexol (Union Carbide)
• Flexsorb (Exxon)
• TEX-TREATS (Huntsman)
• UCARSOLS (Union Carbide)
• GAS/SPEC (DOW)
• MDEA (BASF)
Slide 19
• Sulfinol-D, Sulfinol-M, Sulfinol-X (Shell)
• Selexol (Union Carbide)
• Flexsorb (Exxon)
• TEX-TREATS (Huntsman)
• UCARSOLS (Union Carbide)
• GAS/SPEC (DOW)
• MDEA (BASF)
Acid Gases with Amine Solutions
H2S: Bronsted acid (gives proton)2 RNH2 + H2S = (RNH2)2 H2SA very fast kinetics
CO2: Lewis acids (accepts electron)R1R2NH + CO2 = R1R2NCOO- + H+
CO2 + H2O = H++ HCO3-
Chemical reaction equilibrium involved
Slide 20
H2S: Bronsted acid (gives proton)2 RNH2 + H2S = (RNH2)2 H2SA very fast kinetics
CO2: Lewis acids (accepts electron)R1R2NH + CO2 = R1R2NCOO- + H+
CO2 + H2O = H++ HCO3-
Chemical reaction equilibrium involved
Acid Gases with Amine Solutions
• At low temperatures, amines absorb acid gas
• High temperatures favor desorption
• Mono- and di-ethanol-amine commonly used
• MDEA removes H2S but not CO2
• Mixtures of different amines
Slide 21
Typical Amine Treating Process
Lean amine removesH2S and CO2 fromnatural gas in thecontactor at low T
H2S and CO2 areremoved from richamine in regeneratorat high temperature
Slide 22
Lean amine removesH2S and CO2 fromnatural gas in thecontactor at low T
H2S and CO2 areremoved from richamine in regeneratorat high temperature
Benefits of Amine Treating Process Modeling
• Increase design certainty
• Evaluate various process configurations/different types of solvents
• Assess energy costs
• Predict the purity of products
• Determine the size of equipment
• Troubleshoot and pinpoint problems
Slide 23
• Increase design certainty
• Evaluate various process configurations/different types of solvents
• Assess energy costs
• Predict the purity of products
• Determine the size of equipment
• Troubleshoot and pinpoint problems
Amine Treating Process Modeling
• Using PRO/II AMINE package
Slide 24
– Support single amine system, such as MEA, DEA, DGA, DIPA, and MDEA
– Dimensionless residence time corrections to amine K-value calculationmay be specified by user for systems involving MDEA or DGA.
Amine Treating Process Modeling
• Using PRO/II OLI Electrolyte package
Slide 25
– For single amine systems
– Use ELDIST or RATERFAC algorithms
Acid Amine Process Modeling
• Using AMSIM technology from Schlumberger DBR via PRO/II
– Developed by D. B. Robinson and Associates in the 1980’s
– Stand-alone simulator
– Available as a module embedded within PRO/II
– Single or any combination of two blended amines
– Physical Solvent Model (DEPG)
– Non-equilibrium stage model with different column configurations
– Simulation of gas or LPG treating processes
– Mercaptans and COS removal based on in-house measured data
– VLLE (3-Phase) flash calculation
– Aromatics components (BTEX) supported
Slide 26
• Using AMSIM technology from Schlumberger DBR via PRO/II
– Developed by D. B. Robinson and Associates in the 1980’s
– Stand-alone simulator
– Available as a module embedded within PRO/II
– Single or any combination of two blended amines
– Physical Solvent Model (DEPG)
– Non-equilibrium stage model with different column configurations
– Simulation of gas or LPG treating processes
– Mercaptans and COS removal based on in-house measured data
– VLLE (3-Phase) flash calculation
– Aromatics components (BTEX) supported
http://www.slb.com/services/characterization/core_pvt_lab/fluid_lab_services/fluid_lab_software.aspx
• Phase Equilibrium (VLE & LLE)
• Chemical Reaction Equilibrium
• Mass Balance
• Electroneutrality
Thermodynamic Framework in AMSIM
Slide 27
• Kent-Eisenberg Model, 1976 (Empirical)
• Ideal Solution: = 1
• Equilibrium constants tuned against experimental data
• Li-Mather Model (Electrolyte Model), 1994
Thermodynamic Methods in AMSIM
Slide 28
jjkj
k
kk m
Ib
IAz 2
1ln
5.0
5.02
iiii xK )(
Using AMSIM in PRO/II• AMSIM is a unit operation in PRO/II
Slide 29
Simulation Options• Simulate the entire unit in AMSIM and pass only net feeds and
products to PRO/II
• Simulate individual columns in AMSIM and let PRO/II solve theflowsheet
Slide 30
Working with AMSIM• Each AMSIM unit has its own file (.apj) which is used to store
configuration information
• This file is zipped along with *.prz file
Slide 31
Working With AMSIM• Project Setup is where you define base configuration
Slide 32
• Component Selection
Working With AMSIM
Slide 33
Working with AMSIM (cont.)
• Select a red box to add/remove optional equipment
Slide 34
Working With AMSIM (cont.)
• Click on Enter Data button and click on items to enter data
Slide 35
Using AMSIM in PRO/II (cont.)
• Click on Run button or Run from PRO/II Run menu
Slide 36
Warning on Thermodynamics• AMSIM thermodynamics are NOT identical to PRO/II – ensure
outlet conditions are set properly in AMSIM unit operation
Slide 37
Gas Treating with MEA
2
1
1
AbsorberHigh PresLow Temp
RegeneratorHigh TempLow Pres
Lean Amine< 15 wt% MEA
Sweet GasAlmost no H2S
Acid GasMakeupCooler
MEA andWater loss
Slide 38
95
AbsorberHigh PresLow Temp
RegeneratorHigh TempLow Pres
Lean Amine< 15 wt% MEA
Sour Gas10
Rich Amine0.5 mole acid gas/mole MEA Anti-Corrosion
measures
Gas Treating DemoSteps:1. Add component data and thermo data (use Amine)2. Estimate the Lean Amine Recycle Rate (using Excel)
(moles acid gas/moles of MEA) = 0.5MW of MEA =61 ; 15% by weight MEA
3. Simulate the absorber using AMSIM4. Add controller to impose the acid gas pickup specification5. Add hydrocarbon purge valve and Feed-Btms exchanger6. Add the regenerator using AMSIM7. Setup Makeup Stream Calculator8. Close the recycle loop
Slide 39
Steps:1. Add component data and thermo data (use Amine)2. Estimate the Lean Amine Recycle Rate (using Excel)
(moles acid gas/moles of MEA) = 0.5MW of MEA =61 ; 15% by weight MEA
3. Simulate the absorber using AMSIM4. Add controller to impose the acid gas pickup specification5. Add hydrocarbon purge valve and Feed-Btms exchanger6. Add the regenerator using AMSIM7. Setup Makeup Stream Calculator8. Close the recycle loop
Step 2: Lean Amine recycle rate estimate?
• You know its Temperature and Pressure
• Composition is approximately 15 wt % MEA, 85% water
• Determine rate from acid gas pickup spec
• Acid gas in feed / MEA in rich amine = 0.3 mole ratio
Step 4: How to impose the acid gas pickup specification?
• Use a controller to impose acid gas pickup specification
• Vary the lean amine flow rate
Details
Slide 40
Step 2: Lean Amine recycle rate estimate?
• You know its Temperature and Pressure
• Composition is approximately 15 wt % MEA, 85% water
• Determine rate from acid gas pickup spec
• Acid gas in feed / MEA in rich amine = 0.3 mole ratio
Step 4: How to impose the acid gas pickup specification?
• Use a controller to impose acid gas pickup specification
• Vary the lean amine flow rate
Known Information
230 psig244.7psia 100°F
230 psig15wt% MEA
75°F7.5 psig22.2 psia
8 psig22.7 psia
Molarrefluxratio=4
120°F7 psig21.7 psia
Slide 41
Sour gas feed
249.7 psia
231.5 psig246.2 psia
0.5 mole acid gas/mole MEA10 psig24.7 psia
180°F
ΔP=2psi
9.5 psig24.2 psia
Recommended Procedure• Add AMSIM unit
• Open AMSIM unit and start AMSIM GUI
• Select Project | Setup and configure base configuration
– Model selection
– Solvent selection
– Feed selection
– Flowsheet Selection
– Component selection
• Add/remove optional equipment on the AMSIM PFD
Slide 42
• Add AMSIM unit
• Open AMSIM unit and start AMSIM GUI
• Select Project | Setup and configure base configuration
– Model selection
– Solvent selection
– Feed selection
– Flowsheet Selection
– Component selection
• Add/remove optional equipment on the AMSIM PFD
Recommended Procedure (cont.)
• Click on Enter Data button
– Enter stream and column information
• Save and exit (automatically creates PRO/II components andstreams)
• Run
• After successful solution one can connect to existing PRO/II streams
– Do not remove feed/product streams from AMSIM unit
– Use a dummy unit-op (valve with zero DP) if necessary to join to existingstreams
Slide 43
• Click on Enter Data button
– Enter stream and column information
• Save and exit (automatically creates PRO/II components andstreams)
• Run
• After successful solution one can connect to existing PRO/II streams
– Do not remove feed/product streams from AMSIM unit
– Use a dummy unit-op (valve with zero DP) if necessary to join to existingstreams
Thank You for Attending This Session
For Technical Support
1-800-SIMSCI-1 (1-800-746-7241)
Email: [email protected]
Slide 44
For Technical Support
1-800-SIMSCI-1 (1-800-746-7241)
Email: [email protected]
Slide 45