PREDICTION OF THE SOLUBILITY AND GAS-LIQUID EQUILIBRIA FOR GAS-WATER AND LIGHT HYDROCARBON-WATER SYSTEMS AT HIGH-TEMPERATURES AND PRESSURESWITH A GROUP-CONTRIBUTION EQUATION OF STATE

A group contribution equation of state has been proposed. The model is based on the Weidlich-Gmehling modified UNIFAC and Soave-Redlich-Kwon g equation of state, in which the modified Huron-Vidal excess Gibbs fr ee energy mixing rule is used, the residual term of the modified UNIFA C is changed a little and the combinatorial term is improved. Nine int eraction parameters between gas groups CO2, CO, N-2, H-2, H2S, CH4, C2 H6, C3H8, C4H10 and water are fitted. The model parameters have been u sed to predict solubility and gas-liquid equilibria for seven gas-wate r, and thirty-nine light hydrocarbon-water data sets in large temperat ure and pressure ranges (278-637 K, 1-1972 bar). The predicted results are in good agreement with the experiments, which makes it possible t hat the real phase behavior at high temperatures and pressures for gas -water and light hydrocarbon-water systems which are of interest to pe troleum and natural gas exploitation industries, can be predicted reli ably. (C) 1997 Elsevier Science B.V.