Hydrodynamics of gas–solid turbulent fluidized bed of polydisperse binary particles

Abstract

The hydrodynamics of binary mixture of polydisperse particles in a turbulent fluidized bed was investigated by experiment and numerical simulation in this paper. A computational fluid dynamics model (CFD) coupled with population balance model (PBM) was developed, which combined the advantage of CFD model and PBM. The CFD model is applied to simulate the flow field and PBM is used to represent the particle size distribution (PSD). The effects of particle attrition and aggregation on particle behaviors were also considered. The model was validated by comparing simulation results with experimental data. Furthermore, five cases with different types of polydispersity, involving a continuous PSD of single component, a binary mixture of continuous PSDs without much difference between predominant sizes, a binary mixture of continuous PSDs with significant difference between predominant sizes, a continuous PSD of single component undergoing attrition and a continuous PSD of single component undergoing aggregation, were tested. The mixing behavior of polydisperse binary mixture in the turbulent fluidized bed was also obtained numerically. The results showed that the model was effective in describing the mixing behavior of binary mixture of polydisperse particles. In the binary mixture of particles with PSDs of minor difference system, the large particles first sink down into the small particle layer along the wall, and then along the central axis. However, for the binary mixture of which PSDs are with significant difference, the large particles go into the small particle layer along the central axis first.