MODELING OF THE 3-PHASE LLV REGION FOR TERNARY HYDROCARBON MIXTURES WITH THE SOAVE-REDLICH-KWONG EQUATION OF STATE

The prediction of the three phase liquid-liquid-vapour (L2L1V) region for the ternary mixtures ethane + propane + eicosane (C2 + C3 + C20) a nd methane + ethane + eicosane (C1 + C2 + C20) was performed using the Soave-Redlich-Kwong equation of state. A procedure for finding K- and L-points is presented. It is based on the solution of thermodynamic c onditions for the K- and L-point using the Newton iteration technique with carefully chosen starting points. The calculations were performed with ail binary interaction parameters set to zero and with binary in teraction parameters fitted to vapour-liquid equilibrium data of the b inary subsystems. In the latter case for all binary subsystems two adj ustable parameters with classical mixing rules were used. The results obtained show only qualitative agreement with experimental data for bo th sets of interaction parameters.