Project description: Cubic-Plus-Association Thermodynamic Model

Water and many other substances of importance to industry (e.g. alcohols, amines, acids, glycols, esters and ethers) exhibit hydrogen bonds, which affect the thermodynamic properties. Conventional models such as cubic equations of state (EoS) are not adequate for such systems. Cubic-Plus-Association (CPA) is a novel EoS, which combines the well-known SRK EoS with the association term of SAFT, from statistical mechanics. The results so far have led to substantial improvements in e.g. the calculation of the amount of the gas hydrate inhibitors such as methanol which should be used in oil and gas production. The economic importance of such improvements is very significant.

Results achieved

IVC-SEP (Centre for Phase Equilibria and Separation Processes, Department of Chemical Engineering, Technical University of Denmark) has now developed this model in a CAPE-OPEN thermo system called IVCSEPThermoSystem. This thermo system offers the user to configure a thermodynamic property package in which four thermodynamic models are available: SRK, PR, CPA and PC-SAFT. The software thermodynamic core consists of a strong and efficient FORTRAN code, as its wrapper follows the released CAPE-OPEN interface specifications (version 0.9.3) and has been written in COM IDL.

The project, in which the development of the IVCSEPThermoSystem is the dissemination part, is financed by a research consortium whose members are: BP, Maersk Oil and Gas, Statoil and TOTAL. The pure-component parameters and binary interaction parameters are being added to the thermo system to the extent that they are determined. Tests with different process simulators are performed in order to further develop the software. Currently, the thermo system runs successfully in Aspen Plus 2004, Aspen Hysys and COCO of AmsterCHEM.

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