CFD-PBM Simulation on Gas-Liquid Mass Transfer in a Gas-Liquid-Solid Circulating Fluidized Bed

The three-dimensional transient flow field and gas-liquid mass transfer behavior in a gas-liquid-solid circulating fluidized bed (CFB) riser were simulated using E-E-E model coupled with PBM model (population balance model) and gas-liquid mass transfer model. With PBM model, the bubble size distribution could be obtained through bubble coalescence and breakup, and the effects of the bubble size on the interphase forces were also considered. The gas-liquid interfacial area could be calculated from gas holdup and average bubble diameter. Mass transfer coefficient calculated from four classical mass transfer models, named as penetration model, surface renewal model, eddy cell model and rigid model, were compared and tested. Reasonable simulations of gas-liquid interfacial area and mass transfer coefficient were achieved under varied operating conditions, e.g. superficial gas velocity, superficial liquid velocity and solid holdup. The simulation results shows that CFD-PBM coupled model is an effective method for predicting the hydrodynamics and mass transfer behavior in a gas-liquid-solid CFB riser.