Binary interaction coefficients of Schmidt-Wenzel and Patel-Teja equations of state for vapor-liquid equilibrium calculations of light hydrocarbon and carbondioxide systems

Abstract

The Schmidt-Wenzel (SW) and Patel-Teja (PT) equations of state have been applied to the calculation of vapor-liquid equilibrium of carbondioxide-hydrocarbon, methane-heavier hydrocarbon, and ethane-heavier hydrocarbon mixtures. A comparison of the results has been made with the Soave-Redlich-Kwong (SRK) and Peng-Robinson (PR) equations. Binary interaction coefficients for all equations and all systems are obtained through the optimization of two objective functions, the bubble point pressure criterion and the fugacity criterion. The results from the two criteria show that the former yields better Kᵢj values for the VLE prediction while the latter provides an acceptable prediction with a considerable reduction in computing time requirement. It is also proved that incorporation of the Kᵢj term offers accuracy improvement for all equations. A comparison of the VLE results indicates that the SRK and PT equations perform slightly better than the PR and SW equations for all three types of mixtures.