Modeling and simulation of reactive distillation columns using computer algebra

This work presents an extension of a computer algebra (CA) program, Thermath, originally developed for the automatic implementation of physical property calculations, to generate computer codes in Fortran for the simulation of steady-state reactive distillation columns. The adopted procedure requires the simultaneous solution, using the Newton–Raphson method, of mass and energy balances, phase equilibrium equations, chemical equilibrium or rates of reaction equations and an additional equation needed to match the number of degrees of freedom. The Thermath program was used to obtain Fortran subroutines that implement these equations and their derivatives with respect to the process variables and the equation of state and/or excess Gibbs free energy model used in the simulation. The results are in excellent agreement with those available in the literature. By using Thermath, it was possible to reduce the time and effort needed to implement the mathematical models of multistage reaction–separation equipment.