CFD-DEM study of reactive gas-solid flows with cohesive particles in a high temperature polymerization fluidized bed

The cohesive particles are commonly encountered in high temperature polymerization fluidized bed reactors. However, detailed studies on the effect of cohesiveness on the hydrodynamics, heat transfer, and reaction characteristics in such reactors have been rarely reported. In this work, a CFD-DEM approach coupled with solid bridge force model and polymerization reaction kinetics model is established to sim-ulate the reactive gas-solid flows with cohesive particles. The results demonstrate that cohesive particle agglomeration significantly increases the inhomogeneity of concentration and velocity fields, and hinders particle circulation. The hindered particle circulation further results in pronounced temperature inhomo-geneity. Moreover, the local hot spots are readily formed in the agglomerates, which expand and deteri-orate rapidly if not controlled promptly. Besides, how the cohesion model parameters, namely contact time and maximum cohesive force limitation, affect the onset temperature and the severity of particle agglomeration is revealed. The established model extends the particle-scale study of cohesive gas-solid flows to reactive systems.(c) 2022 Elsevier Ltd. All rights reserved.

Automated summary

Detailed studies on the effect of cohesiveness on the hydrodynamics, heat transfer, and reaction characteristics in high-temperature polymerization fluidized bed reactors have been rarely reported. This work establishes a CFD-DEM approach coupled with a solid bridge force model and polymerization reaction kinetics model to simulate the reactive gas-solid flows with cohesive particles. The results show that cohesive particle agglomeration significantly affects the concentration, velocity fields, and temperature distribution in the reactor. The model also reveals the influence of cohesion model parameters on the onset temperature and severity of particle agglomeration.