New Local Composition-Equation of State Mixing Rules for High Pressure Vapor-Liquid Equilibria Using EOS/AE

In this study using Equation of State/ Helmholtz excess energy function,  EOS/AE, two new local composition-Equation-of State mixing rules, LCEOS1 and LCEOS2 were developed in which the energy interaction parameters were expressed in terms of attractive and repulsive parameters of the cubic equation of state. The EOS/AE models are applied for equilibrium calculation of natural gas that consists of light to heavy hydrocarbons with water and acid gases, i.e. H2S and CO2. Applying these new mixing rules, the bubble point pressure and vapor phase compositions at high pressure were simulated. The binary interaction parameters and a lumped nonrandomness parameter for the binary systems containing CO2, H2S, H2O, CH4, C2H6, EG, TEG were obtained. Using the binary parameters, solubility of CH4 and C2H6 in ternary systems CH4+EG+H2O and C2H6+EG+H2O were predicted, respectively. A comparison of these two new mixing rules with experimental data showed that both LCEOS1 and LCEOS2 demonstrated high accuracy.