Development of Predictive Methods of Water–Heavy Oil Phase Equilibrium for Supercritical Water Upgrading Process

Abstract

Predictive methodology was developed for water-hydrocarbon systems under high temperature and pressure conditions based on reported phase equilibrium data using the Peng-Robinson equation of state (EOS) for vapor-liquid equilibrium (VLE) and liquid-liquid equilibrium (LLE). The available experimental data for hydrocarbons with low molecular weight and interaction parameter, k_ij, with/without a size parameter, l_ij, included in the Peng-Robinson EOS were fitted to experimental data and accumulated for constructing a predictive equation for hydrocarbons with high molecular weight. As a result, l_ij was found to be negligible for VLE in water-hydrocarbon systems, and only the fitting parameter k_ij was necessary in some hydrocarbon and water systems. Consequently, prediction of VLE diagrams was possible using the estimated k_ij in the Peng-Robinson EOS for water-hydrocarbon systems under high temperature and pressure conditions.