Modeling of a catalytic fluidized bed reactor via coupled CFD-DEM with MGM: From intra-particle scale to reactor scale

Abstract

The Computational Fluid Dynamics - Discrete Element Method (CFD-DEM) method is extended by coupling with the multi-grain model (MGM) to include particle growth due to a gas-solid reaction, as well as intra- and inter-particle phenomena such as heat and mass transfer, and reaction, next to the inter-particle and fluid-particle interactions in the reactor. This comprehensive model treats each particle individually and accounts for changes in particle properties due to both the particle growth and temporal and spatial variations of the process conditions. It also captures the impact of the change in the particles' properties on the fluidized bed reactor characteristics, such as the hydrodynamic regime. The results of the model revealed that the fluidization characteristics and solids mixing can be altered by particle growth. Particle growth also led to the formation of a particle size gradient along the height of the reactor. The coupling allows for monitoring of both external and internal mass transfer limitations. For the adopted reaction kinetics, growth rate and properties the external mass transfer limitations remained negligible, however the internal mass transfer limitation plays a significant role in the process performance.