Reduced Microkinetics Model for Computational Fluid Dynamics (CFD) Simulation of the Fixed-Bed Partial Oxidation of Ethylene

Abstract

An implementation of a simplified microkinetics model in three-dimensional computational fluid dynamics (CFD) simulations of an ethylene oxide fixed-bed reactor is proposed. An existing microkinetics model in the literature is simplified to a model with general rate expressions to reduce the complexity of the computations. It then is coupled with CFD simulations of flow in the fixed bed and transport inside the catalyst particles. Illustrative CFD simulations are carried out in a randomly packed bed of 120 spherical particles, which take into account surface species under steady-state conditions in the particles. The proposed approach represents a practical method to integrate simplified surface chemistry with a realistic-scale fixed bed for more in-depth analysis. It is shown that the surface coverages can be greatly affected by the surrounding flow conditions; furthermore, the effects of transport limitations, products, and different inlet compositions on the ethylene oxide selectivity are studied.