Numerical investigation of particle mixing and segregation in spouted beds with binary mixtures of particles

Abstract

When spouting binary mixtures of fine and coarse particles, poor mixing and particle segregation are often observed under certain operating conditions. The underlying mechanism of particle segregation is considered to be related to inter-particle and intra-particle friction stresses. In this work, computational fluid dynamics (CFD) simulations with a multi fluid model (MFM) were employed to investigate the particle mixing and segregation in spouted beds with binary mixtures. Results show that when particle segregation occurs, coarse particles tend to circulate in the outer ring while fine particles are circulating in the inner circle. The mixing and segregation in the spouted bed of binary mixtures is greatly influenced by the particle density of coarse particles. This effect is more profound than that of the particle size of coarse particles used. The extent of particle segregation is found to decrease by increasing the spouting velocity. From the simulation results, particle segregation in a spouted bed of binary mixtures is observed in a region where there is a significant difference in the gas-solid drags of different particles.