Multi-fluid Eulerian simulation of mixing of binary particles in a gas–solid fluidized bed with a cohesive particle‒particle drag model

Abstract

A particle‒particle (p‒p) drag model is extended to cohesive particle flow by introducing solid surface energy to characterize cohesive collision energy loss. The effects of the proportion of cohesive particles on the mixing of binary particles were numerically investigated with the use of a Eulerian multiphase flow model incorporating the p‒p drag model. The bed expansion, mixing, and segregation of Geldart-A and C particles were simulated with varying superficial velocities and Geldart-C particle proportions, from which we found that the p‒p drag model can reasonably predict bed expansion of binary particles. Two segregation types of jetsam-mixture-flotsam and mixture-flotsam processes were observed during the fluidization processes for the Geldart-A and C binary particle system. The mixing processes of the binary particle system can be divided into three scales: macro-scale mixing, meso-scale mixing, and micro-scale mixing. At a constant superficial velocity the optimal mixing was observed for a certain cohesive particle proportion.