Computational Fluid Dynamics Modelling of Fixed-Bed Reactors Using Particle-Resolved Approach

Abstract

Traditional designs often ignore the effect of catalyst particle shape, which suffers from capturing detailed local flow hydrodynamics, mass transport and reaction behaviors, and further significantly affects reactor phenomena. This study aims to perform particle-resolved computational fluid dynamics (CFD) simulations to investigate the influence of operating conditions and various catalyst particle shapes on fixed-bed reactor performance. Three important industrial reaction systems, including methanol to dimethyl ether, CO2 hydrogenation to methanol, and levulinic acid esterification, are discussed in fixed-bed reactors. The numerical results demonstrate that reactor performance varies from the important interactive contributions of hydrodynamics characteristics and reaction behaviors. Specifically, exothermic reactions such as methanol to dimethyl ether and CO2 hydrogenation to methanol are characterized by a gradual increase in temperature along the reactor height, while endothermic reactions such as valeric acid esterification exhibit a gradual decrease in temperature along the reactor height. For the methanol to dimethyl ether system, the increase in operating temperature leads to a decrease in axial methanol concentration, as well as an improvement in axial dimethyl ether concentration. However, the change in methanol molar concentration has little influence on its conversion. Furthermore, reactor phenomena strongly vary from the different catalyst shapes. The numerical results demonstrate that the fixed bed with hollow cylinders facilitates a more uniform flow distribution, whereas the fixed bed with solid cylinders achieves higher conversion rates within a specific temperature range (483.15 K to 523.15 K). This research provides valuable insights for fixed-bed reactor optimized design, emphasizing the need for precise control over temperature, feed rate, and catalyst configuration to improve reactant conversion in industrial applications.