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 associating fluid theory (SAFT) equations of state. For the Peng−Robinson equation, two types of mixing rules, one-fluid mixing rules and Wong−Sandler mixing rules, were used. The SAFT equation was coupled with the van der Waals one-fluid mixing rules. Calculations were performed for binary and ternary mixtures composed of short- and long-chain hydrocarbons. The results of the calculations were compared with experimental data. On the basis of the obtained results, the influence on the LLV equilibria of the pure-component properties of the low volatile component, the mixing rules, the binary interaction parameter, and the equation of state itself is discussed.