A non-ideal multiphase chemical equilibrium algorithm

Two non-ideal, multiphase chemical reaction equilibrium algorithms are presented. An approach to multiphase equilibrium calculations due to Abdel-Ghani et al. [R.M. Abdel-Ghani, EOS mixing rules for multi-phase behaviour, MS thesis, University of Calgary, Calgary, 1995; R.M. Abdel-Ghani, R.A. Heidemann, A.V. Phoenix, Paper presented at the 1994 AIChE Conference, San Francisco, CA, 1994] was modified to include reaction equilibrium, exploiting two proposals by Michelsen [M.L. Michelsen, Fluid Phase Equilibria 53 (1989) 73–80; M.L. Michelsen, Computers Chem. Eng. 18 (1994) 545–550]. In both algorithms, nested processes are used with an inner loop treating the phases as ideal solutions and an outer loop updating non-ideal parts of the models. Both of the algorithms were initiated with a number of phases which were reduced in the outer loop by combining phases as they approach the same composition and density. Initiation strategies for phase amounts and compositions are presented.