IMPROVED MODELING OF VAPOR-LIQUID-EQUILIBRIA UP TO THE CRITICAL REGION - APPLICATION TO THE CO2-CH4-N-2 SYSTEM

A new procedure for extending the applicability of cubic EOS to critic al conditions is described. This method requires to determine two sets of optimum binary interaction parameters for the non-critical and cri tical parts of PTx experimental data of binary systems. The effective binary interaction parameters are calculated by interpolation between these two sets of binary interaction parameters. The interpolation fac tor is a function of a distance from critical conditions, which is eva luated from an a priori calculation of the molar volumes of coexistent liquid and vapour. The algorithm is shown to improve the prediction o f the Soave-Redlich-Kwon equation of state in the ternary CO2-CH4-N-2 system. Application conditions of this approach to other systems are d iscussed.