claire adjiman
TRANSCRIPT
© 2012 Process Systems Enterprise Limited
19th March 2012
L. Avaulléea, C.S. Adjimanb, F. Caladoc, P. Duchet‐Suchauxa, J. Fuentesc, A. Galindob, G. Jacksonb, T. Lafitteb, C.C. Pantelidesb,c*, V. Papaioannoub, T.H. Williamsc
a Total S.A.b Imperial College Londonc Process Systems Enterprise Ltd.
gSAFT: Application of the SAFT‐‐Mie EOS in the oil/gas industryFrom academic research to industrial deployment
© 2012 Process Systems Enterprise Limited2
Outline
gSAFT technology – brief overview
SAFT‐Mie, a group contribution equation of state
gSAFT for oil/gas systems – Methodology
gSAFT for oil/gas systems – Application examples
Concluding remarks
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PSE’s gSAFT technologyBrief overview – I
Developed by Molecular Systems Engineering group at Imperial College acquired by PSE from Imperial College in 2009 on‐going support/technology pipeline
Objective: provide advanced thermodynamics for complex mixtures in gPROMS® a single platform that meets a wide range of modelling needs
Collaboration with Total initiated in late 2010 to test the applicability of gSAFT technology to oil and gas applications assess gSAFT’s capabilities against other technologies develop a parameter databank for oil and gas applications
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PSE’s gSAFT technologyBrief overview – II
A family of Equations of State, employing different types of molecular descriptions (homonuclear vs. heteronuclear/Group
Contribution) repulsive/dispersive interactions
Interfaced to gPROMS as a Foreign Object
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SAFT‐VR SW SAFT‐ SW SAFT‐Mie
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SAFT‐Mie fundamentals
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Lymperiadis et al., J. Chem. Phys. 127, 234903 (2007)Lymperiadis et al., Fluid Phase Equil. 274, 85 (2008)Lafitte et al., in preparation (2012)Papaioannou et al., in preparation (2012)
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The SAFT‐VR equation of state
One of a generation of more advanced models specifically developed for chain and associating molecules SAFT: Chapman, Gubbins, Jackson, Radosz, Ind. Eng. Chem. Res., 29, 1709 (1990) SAFT‐VR (potentials with variable range): Gil‐Villegas, Galindo, Whitehead, Mills, Jackson,
Burgess, J. Chem. Phys., 106, 4168 (1997)
SAFT‐VR is derived from molecular theory and statistical mechanics repulsions and attractions of variable range non‐spherical molecules (e.g. polymers) association (chemical or hydrogen bonding)
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Group Contribution (GC) MethodsBasic principles
Molecules are divided into functional (chemical) groups CH3, CH2, OH, NH2, …
Properties predicted as function of group parameters given number of occurrences of each group type
Parameters estimated from large database of experimental data
Can predict properties of compounds for which there are no experimental data, provided group parameters are available
GC models are an important class of predictive methods
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SAFT‐molecular model
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2‐ethyl‐5‐methylphenol
SAFThomonuclear model
SAFT ‐ heteronuclear model
C6H3CH2CH3aCCH3
aCH
Lymperiadis et al., J. Chem. Phys. 127, 234903 (2007)Lymperiadis et al., Fluid Phase Equil. 274, 85 (2008)
aCO
H
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SAFT‐molecular model parameterisation
Segment‐segment dispersive interactions described via pair potential with attractive/repulsive interactions
segment diameter kk
segment dispersive energy kk segment dispersive range a,kk r,kk
cross‐interactions may be estimated from experimental data
pure component and/or mixture
computed via combining rules
Effective contribution of each segment to molecular shape shape factor Sk
Site‐site associative interactions energy hb
kkab
cut‐off range rckkab
Variable‐rangesquare‐well potential
Mie potential
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gSAFT for oil/gas systemsMethodology
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gSAFT for oil/gas industry
Methodology
1. Identify key systems of interest to oil/gas industry both upstream and downstream
2. Analyse molecules in mixtures to identify complete sets of groups and group‐group interactions that are needed to characterise these systems
3. For each group, identify pure component experimental data sets that can be used to determine like and unlike group parameters typically, saturated liquid density and vapour pressure transferability of SAFT‐ parametersmolecules do not have to be those appearing in the systems of interest
4. For each group‐group interaction, identify pure component/binary mixture experimental data sets that can be used to determine group/group interaction parameters typically saturated liquid density and vapour pressure (for pure components)
and phase envelopes (for binary mixtures) group/group interaction parameters can often be estimated from pure
component data e.g. pure component data for propane parameters for CH3/CH2 interactions
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gSAFT for oil/gas industry
Workflow
Defined standardised formats for experimental data sets for pure components & binary mixtures SAFT‐Mie parameter databank
Devised streamlined workflow allowing user to specify group parameters to be estimated select appropriate subset of relevant experimental data initiate parameter estimation
Implemented within MS Excel environment eliminates need for manual data transcription significantly reduces probability of errors
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Systems of interest to the oil/gas industryand SAFT‐ constituent groups (partial)
System ID Description SAFT‐ groups
001 Carbon dioxide CO2002 Carbon dioxide + Water CO2; H2O 003a Methane + Carbon dioxide CH4; CO2
003b Methane + Carbon dioxide + Water (Hydrates) CH4; CO2; H2O
004 CO2‐SO2‐N2‐Ar‐O2 CO2; SO2; N2; Ar; O2005 Methane + Water CH4; H2O006 Methane + Methanol CH4; CH3OH007 Methane + Methanol + Water CH4; CH3OH; H2O008 Methanol + n‐Hexane + Water CH3OH; CH3; CH2; H2O009 Methanol + Toluene + Water CH3OH; aCCH3; aCH; H2O010 Methanol + Water (Heat of mixing) CH3OH; H2O
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
. . . . . . . . . . . . . . . . . . . .
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CH3 CH2 aCH aCCH3 aCCH2 CH4 H2O CH3OH CO2 CH2=C=CH2 C2H6
CH3
CH2
aCH
aCCH3
aCCH2
CH4
H2O
CH3OH
CO2
CH2=C=CH2
C2H6
Groups & group/group interactions
Existing group & group/group interactions in the databank (ingreen)
Most binary group/group interaction parameters were obtained from pure component data
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Example of SAFT‐Mie group parameters
kl/kB [K] CH3 CH2
CH3 256.766
CH2 350.772 473.389
Group No. segments S [Å] a r
No. site types
No. sites - type e
No. sites - type H
CH3 1 0.573 4.077 6.000 15.050 0 ---- ----
CH2 1 0.229 4.880 6.000 19.871 0 ---- ----
Parameters obtained by fitting to pure VLE of n‐propane to n‐decane Other unlike parameters (kl, a,kl, r,kl ) are obtained via combining rules Resulting %AAD up to and including critical point:
1.8% in vapour pressure 0.7% in saturated liquid density
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gSAFT for oil/gas systemsApplication examples
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Pure component: CO2
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kl and r,kl are estimated from mixture data
Binary mixture H2O + CO2
Isotherms:
T=323.2 K (red)T=333.2 K (yellow)T=353.1 K (green)
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Binary mixture H2O + CO2
Isotherms:
T=288.15 K (green)
T=293.15 K (yellow)
T=298.15 K (blue)
T=308.15 K (red)
T=313.15 K (black)
CO2 rich phase – low temperatures
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Binary mixture CO2 + CH4
kl and r,kl are estimated from mixture data
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Binary mixtures CO2 + n‐alkanes
kl and r,kl for CO2 + CH3 and CO2 + CH2 are estimated from mixture data
same set of parameters is used for the entire series of CO2 + n‐alkane mixtures CO2 + n‐C3H8
Predicted
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Binary mixtures CO2 + n‐alkanes
CO2 + n‐C4H10
CO2 + n‐C10H22
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Binary mixtures: C6H6 + n‐C6H14 to n‐C8H18
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From binary to ternary mixtures: H2O + n‐C6H14 + CH3OH
n‐C6H14 + H2O at 473.15 K
Predictionat 298.15 K, 0.1 MPa
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Concluding remarks
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Concluding remarks
gSAFT technology based on SAFT‐VR EOS includes recent developments such as
third‐order perturbation expansion (improved critical region) Mie potential (improved derivative properties) group contribution formalism (improved predictive capabilities)
allows reliable modelling of phase equilibria and derivative properties
Three‐way collaboration has resulted in group parameters for oil & gas application evidence of the suitability of SAFT‐Mie for modelling the
thermodynamics of many industrially‐relevant mixtures demonstration of the predictive capabilities of SAFT‐Mie
ability to derive group/group interaction parameters from pure component data transferability of group parameters
© 2012 Process Systems Enterprise Limited
19th March 2012
L. Avaulléea, C.S. Adjimanb, F. Caladoc, P. Duchet‐Suchauxa, J. Fuentesc, A. Galindob, G. Jacksonb, T. Lafitteb, C.C. Pantelidesb,c*, V. Papaioannoub, T.H. Williamsc
a Total S.A.b Imperial College Londonc Process Systems Enterprise Ltd.
gSAFT: Application of the SAFT‐‐Mie EOS in the oil/gas industryFrom academic research to industrial deployment
© 2012 Process Systems Enterprise Limited28
Binary mixture CO2 + CH4 (including Peng‐Robinson EoS)
kl and r,kl are estimated from mixture data
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CO2 + H2O mixture: CO2 rich phase (including CPA)
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Binary mixture: n‐pentane + methanol at 0.14 MPa
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Excess enthalpies for CO2 + C5H12 mixtures
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