CFD models for methanol synthesis three-phase reactors: reactor optimization

Two Computational Fluid Dynamics (CFD) models have been developed for slurry bubble columns. The first model is based on the kinetic theory of granular flow with a measured restitution coefficient in a slurry bubble column. The model was used to predict Air Products/DOE La Porte reactor's slurry height, gas hold-up and the rate of methanol production. It showed an unfavorable high solids concentration at the bottom of the reactor. The second model with a catalyst viscosity as an input has computed the measured flow patterns and Reynolds stresses in agreement with measurements in a laboratory slurry bubble column. Here, we have rearranged the heat exchangers in the La Porte unit and constructed a CFD model for a baffled reactor that has a higher concentration of the catalyst in the upper portion of the reactor. In this arrangement, the conversion to products is higher than in the La Porte unit, because there is more catalyst in the region of decreased reactant concentration. The baffled arrangement of the heat exchangers prevents the mixing of the catalyst from the upper stage, allowing continued operation of the reactor with a high concentration in the upper stage. Thus. an optimum catalyst concentration is maintained during the course of the production of the liquid fuels. (C) 2002 Elsevier Science B.V. All rights reserved.