Prediction of complex phase behaviour

Abstract

A correlation of phase behaviour based on the Redlich-Kwong equation of state is presented. Its success in cal culating phase equilibria is demonstrated for all of the binari es that can be formed from water, hydrogen sulphide , carbon dioxide, nitrogen, methane, ethane, and propaneg Some limited success is demonstrated with binaries involving hydrogen and nitrogen, methane, and ethane. Soave's correlation for the a coefficient, with a small modification for water, is used. Empirical interaction parameters are included in the mixing rules for a and b. The types of complex phase behaviour reproduced by this correlation include three phase equilibrium states, azeotropism, and retrograde phenomena. Predicted and experimental phase behaviour for the three ternaries methane-ethane-propane~ nitrogen-methane-ethane, and nitrogen-carbon dioxide-methane are compared. This demonstrates that the correlation can be extended to multicomponent systems without further modification.