Calculation of Phase Equilibria of Binary Hydrocarbon Mixtures Using the PC-SAFT Equation of State and Direct Energy Minimization

The introduction of environmentally friendly technologies in the oil and gas industry requires numerical simulation methods for phase equilibria of multicomponent mixtures. In this paper, the PC-SAFT equation of state, which is gaining popularity in this field, was applied to calculate the parameters of the vapor–liquid equilibrium of six binary mixtures of n-alkanes: methane and ethane, methane and propane, methane and n-butane, ethane and propane, ethane and n-butane, and propane and n-butane. Calculations were performed using the direct minimization of the Helmholtz energy of an isochoric–isothermal binary system. Analysis showed that the PC-SAFT equation of state in combination with direct energy minimization successfully predicts the parameters of phase equilibria of binary mixtures of light hydrocarbons, which indicates prospects for the further development of this approach for the numerical simulation of the phase behavior of hydrocarbon systems.