Simulation of a Wurster fluidized bed by CFD–DEM with a cohesive contact model

Abstract

A CFD–DEM coupled with a cohesive contact model is developed for simulation of a Wurster fluidized bed with heat and mass transfer. First, the water evaporation and cohesive contact sub-models are tested, respectively. Second, a Wurster fluidized bed with heating, drying, and wet particle fluidization is simulated. Results show that the particle temperature in the bottom and draft tube rises faster than that in the annular region, which leads to the probability density distribution of the particle temperature presents two peaks. The circulation pattern also has a significant effect on particle drying. Under conditions with a small amount of liquid injection, the water evaporates immediately and the particles are fluidized normally. Increasing the liquid injection rate, the stability of the particle circulation decreases. Under conditions with significant particle cohesion, large agglomerates are formed and the fluidization breaks down. The current study provides an effective method for studying hydrodynamics of Wurster fluidized beds with simultaneous processes of heating, drying, and wet particle fluidization.