PSE is commercialising the SAFT technology from Imperial College London as the gSAFT product
Accurate design and optimisation of chemical processes requires accurate physical property predictions over a wide range of conditions.
Statistical Associating Fluid Theory, or SAFT, is an advanced molecular thermodynamic method that can predict a wide variety of thermodynamic properties of mixtures accurately based on physically-realistic models of molecules and their interactions with other molecules.
gSAFT
PSE has acquired the rights to commercialise the SAFT technology from Imperial College London and is making it available as the gSAFT product.
SAFT representation of ethanol
SAFT continues to be the subject of substantial ongoing research within the Molecular Systems Engineering research group of Imperial. PSE will bring new developments to the market within the gSAFT framework as they arise.
Technology
The underlying SAFT models have a more formal physical basis than those of the more well-known cubic equations of state.
Molecules are treated as associating chains of spherical segments with variable attractive interactions. This means that SAFT fluid models have many advantages when it comes to accurately predicting properties of pure components and mixtures from limited experimental data.
The current gSAFT implementation is based on the SAFT-VR ("variable range") version of SAFT. SAFT-VR is an extension of the original SAFT methodology (Chapman et al, below) which extends its capability to deal with systems with variable attractive range (polarity).
Key application areas and advantages
Because of the underlying model, SAFT can provide a prediction of properties of the following complex mixtures with an accuracy that has not been possible in the past. Systems of interest include:
SAFT article, the chemical engineer (tce) February 2010
- polar fluids (e.g. CO2, refrigerants)
- strongly associating / hydrogen bonding (e.g. carboxylic acids, HF, water)
- mixed electrolytes (e.g. inorganic salts, charged surfactants)
- polymers
- gas hydrates & asphaltenes.
In particular SAFT allows for the treatment of systems with varying polarity, from the standard Lennard-Jones dispersion to highly polar interaction. General association schemes can be incorporated into the treatment.
The underlying model also allows for predictions are valid over a wide range of operating conditions. This is a particular advantage for systems where there is limited experimental data in the areas of operation being studied.
Implementation
gSAFT is available as an option for gPROMS industrial and academic gPROMS licences. PSE is also considering making gSAFT available as a stand-alone application in the future.
References
You can find out more about the theory behind SAFT-VR in the following references:
A. Gil-Villegas, A. Galindo, P. J. Whitehead, S. J. Mills, G. Jackson, and A. N. Burgess, Statistical associating fluid theory for chain molecules with attractive potentials of variable range (SAFT-VR), Journal of Chemical Physics, 106, 4168-4186 (1997).
A. Galindo, L. A. Davies, A. Gil-Villegas, and G. Jackson, The thermodynamics of mixtures and the corresponding mixing rules in the SAFT-VR approach for potentials of variable range, Molecular Physics, 93, 241-252 (1998).
W. G. Chapman, K. E. Gubbins, G. Jackson, and M. Radosz, SAFT: Equation of state model for associating fluids, Fluid Phase Equilibria, 52, (1989), 31-38.
W. G. Chapman, K. E. Gubbins, G. Jackson, and M. Radosz, New reference equation of state for associating liquids, Industrial & Engineering Chemistry Res., 29, (1990), 1709-1721.
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