Modeling of fluid phase equilibrium of multicomponent hydrocarbon mixtures in the critical region

Abstract

Smith, D.H., Lynch, J.J., 1994. Modeling of fluid phase equilibrium of multicomponent hydrocarbon mixtures in the critical region. Fluid Phase Equilibria, 98: 35-48. Fluid phase equilibrium algorithms have an important role in the modeling of processes throughout the chemical industry. Conventional methods based on cubic equations of state often fail to converge or are inaccurate in the critical region. A model based on two-scale factor universality that conforms to critical scaling laws using effective exponents has been generalized to mixtures with multiple components. The modified Leung-Griffiths theory is a non-cubic, corresponding states model that has produced excellent correlations of many sets of two-component mixture vapor-liquid equilibrium (VLE) data. It has also successfully predicted the fluid phase boundaries of a few ternary fluid mixtures from correlations of the three constituent binary mixtures. The model has recently been extended further to predict N-component VLE boundaries from previous data correlations of the N(N-1)/2 limiting binary fluid mixtures. Where data are unavailable the binary parameters are estimated with simple relations suggested by factor analysis. Predicted coexistence boundaries are compared with experimental VLE data for several multicomponent hydrocarbon systems.