Three‐phase equilibria using equations of state

It is demonstrated that a single equation of state may be used to describe all three phases in liquid‐liquid‐vapor equilibrium situations. Wilson's version of the Redlich‐Kwong equation is shown to predict accurately the water solubility in normal paraffins with interaction parameters k 12 = 0.50. A simple procedure for three‐phase flash computations is presented. Results obtained using this procedure for the system methane, n ‐butane, water exhibit many of the characteristics of the experimental data of McKetta and Katz (1948). In particular, the water content of the vapor phase and the liquid hydrocarbon phase are accurately predicted.