A pseudo transient nonequilibrium method for rigorous simulation of multicomponent separation columns

Abstract

Nonequilibrium stage model is a significant improvement in multicomponent separation process simulation, but more equations are involved and the solution of the model equations, which relies on an adequate initial guess for convergence of the Newton method, is difficult. In this work, based on the concept of pseudo-transient continuation approach, we proposed a new pseudo-transient (PT) nonequilibrium method. The proposed method decouples the strongly coupled model equations by introducing dynamic equations for material and energy conservation, as well as transition equations. Thus, the steady-state solution of the nonequilibrium stage model can be obtained through a robust and fast integration process, and the initial guess issue in Newton method can be effectively avoided. Two simulation cases were used to demonstrate the advantages and applicability of the proposed PT nonequilibrium method.