“Calculation of Simultaneous Chemical and Phase Equilibrium”
Abstract:
Simultaneous chemical and phase equilibrium (CPE) plays a key-role in the chemical and petroleum industry, from heterogeneous chemical synthesis to reactive distillation. Even when equilibrium is not attained due to kinetics, CPE calculations can provide a thermodynamic limit for the process.
The purpose of this work is to develop a general, reliable and efficient algorithm, which will be able to deal with multiple reactions in multiphase systems. The algorithm follows the method of Lagrange multipliers (constrained minimization of the Gibbs energy) and consists of two successive steps. Another method that has been widely used to solve this problem is the RAND algorithm, where the working equations are linearized around the composition estimate, satisfying the material balance constraint at all iterations.
The algorithm in this work has been successfully tested on Vapor-Liquid and Vapor-Liquid-Liquid Equilibrium of reactive systems. Future work is focused on improving robustness, to allow calculations for more complex mixtures.