A thermodynamic model of the φ/φ class of methods that can be easily used with commercial process simulators is proposed. The vapor-liquid equilibrium (VLE) is calculated by means of a Redlich-Kwong-type equation of state (EoS) that uses modified Huron-Vidal mixing rules with activity coefficients: the activity coefficients are derived from the NRTL model whose parameters are evaluated by fitting VLE data of binary mixtures. By means of the Aspen PLUS process simulator, a comparison is made between the performances of both the proposed method with user-created adaptive parameters that can be forced into the simulator database and the Predictive-Soave-Redlich-Kwong (PSRK) method that uses UNIFAC to compute the excess free energy. The ethanol-water separation by extractive distillation is analyzed to point out how an incorrect prediction of the azeotrope can lead to underestimation of the overall process energy requirement.

Using an Adaptive Parameter Method for Process Simulation of Nonideal Systems

PELLEGRINI, LAURA ANNAMARIA;GAMBA, SIMONE;MOIOLI, STEFANIA
2010

Abstract

A thermodynamic model of the φ/φ class of methods that can be easily used with commercial process simulators is proposed. The vapor-liquid equilibrium (VLE) is calculated by means of a Redlich-Kwong-type equation of state (EoS) that uses modified Huron-Vidal mixing rules with activity coefficients: the activity coefficients are derived from the NRTL model whose parameters are evaluated by fitting VLE data of binary mixtures. By means of the Aspen PLUS process simulator, a comparison is made between the performances of both the proposed method with user-created adaptive parameters that can be forced into the simulator database and the Predictive-Soave-Redlich-Kwong (PSRK) method that uses UNIFAC to compute the excess free energy. The ethanol-water separation by extractive distillation is analyzed to point out how an incorrect prediction of the azeotrope can lead to underestimation of the overall process energy requirement.
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Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/11311/570410
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