Prediction of liquid-liquid-vapor equilibria in asymmetric hydrocarbon mixtures

Three-phase liquid-liquid-vapor (LLV) equilibria in asymmetric hydrocarbon mixtures were calculated with the Peng-Robinson (PR) and statistical associ ating fluid theory (SAFT) equations of state. For the Peng-Robinson equatio n, two types of mixing rules, one-fluid mixing rules and Wong-Sandler mixin g rules, were used. The SAFT equation was coupled with the van der Waals on e-fluid mixing rules. Calculations were performed for binary and ternary mi xtures composed of short- and long-chain hydrocarbons. The results of the c alculations were compared with experimental data. On the basis of the obtai ned results, the influence on the LLV equilibria of the pure-component prop erties of the low volatile component, the mixing rules, the binary interact ion parameter, and the equation of state itself is discussed.