A successive substitution approach with embedded phase stability for simultaneous chemical and phase equilibrium calculations

Julien Coatléven (1) , Anthony Michel (1)

1 IFPEN - IFP Energies nouvelles

We propose a nested Gibbs energy minimization method for simultaneous chemical and phase equilibrium calculations, relying on a new formulation of the Lagrange multiplier based inner sub-problem with fixed activity coefficients. Using a sufficient condition for global optimality with fixed activity coefficients equivalent in this case to the tangent plane distance criterion, we describe two equivalent algorithms, a combinatorial and a complementarity based one, allowing to robustly solve this new sub-problem always incorporating all phases. The outer-loop of the global successive substitution reactive flash then only consists in updating the values of the activity coefficients from the non necessarily normalized species fractions for all phases calculated by the inner sub-problem. Numerical experiments from the literature illustrate the correct behavior of the proposed approach.

Mots clés: Reactive equilibrium; Flash calculations; Successive substitution; Gibbs energy minimization

Domaines: Mathématiques [math]; Chimie

Julien Coatléven, Anthony Michel. A successive substitution approach with embedded phase stability for simultaneous chemical and phase equilibrium calculations. Computers & Chemical Engineering, 2022, 168, pp.108041. ⟨10.1016/j.compchemeng.2022.108041⟩. ⟨hal-03994265⟩