Calculation of High-pressure Vapor-Liquid Equilibria for the Ethylene-Polyethylene System Using Continuous Thermodynamic Approach

Abstract

Phase equilibrium data of polymer systems are needed for process design of separation and recovery processes in polymer industries. Nevertheless, the phase equilibrium data of polymer systems are scarce. Therefore, it is desired to develop a correlative or predictive procedure for the phase equilibria of polymer systems. The molecular weight distribution of polymer should be incorporated in the phase equilibrium calculation.
In this study, the equation of state proposed by Schotte was used to calculate the high-pressure vapor-liquid equilibria of the ethylene-polyethylene system. The Γ distribution function was used to describe the molecular weight distribution of polyethylene and the Gaussian quadrature method was adopted to determine the composition of the pseudo-components. The calculated results show fairly good agreements with the experimental data shown in the literature.