Vapor-Liquid Equilibrium of Coal Liquefied Oil Fractions
1. Research Institute of Petroleum Processing, East China University of Science and Technology, Shanghai 200237, China; 2. China Shenhua Coal to Liquid and Chemical Shanghai Research Institute, Shanghai 201108, China
Abstract：Direct coal liquefaction reaction system at high temperature and high pressure has vapor-liquid-solid three phases. The liquid phase is mainly composed of hydrocarbons with different carbon number, the vapor phase includes H2, CH4, C2H6, C2H4, C3H8, C4H10, etc, and the solid phase has coal and residue. Since the vapor-liquid equilibrium (VLE) data are the design basis for the process, we used Aspen Plus flash module to study VLE of coal liquefaction under high pressure in high and low temperature separators. By comparing the simulation results with reported data in the literature, an appropriate set of property method was then identified for the high pressure coal liquefaction system. The simulation indicates that UNIQUAC-RKS method and GRAYSON method are suitable for high and low temperature separators, respectively. Using UNIQUAC-RKS physical property method in a high temperature separator, the average relative errors between calculated values and experimental data of phase composition of vapor and liquid are 18.7% and 5.49%, respectively; using GRAYSON physical property method in a low temperature separator, the average relative errors between calculated values and experimental data of phase composition of vapor and liquid are 19.8% and 42.5%, respectively.
