CFD simulations of gas–liquid–solid flow in fluidized bed reactors — A review

Gas–liquid–solid fluidized bed reactors (FBRs) are of considerable importance as proved by their widespread use and popularity in various industrial processes, which results in extensive theoretical analyses, experimental investigations and computational fluid dynamics (CFD) studies in the past. Many reviews have been published concerning the theoretical and experimental works of three-phase FBRs while little effort is on the CFD approach of three-phase fluidization system. This review attempts to summarize and analyze CFD simulations for these three-phase fluidization systems from two aspects: the fundamentals and their applications, which are of paramount importance to the formulation of strategies for scale-up, design and control of three-phase FBRs. The fundamentals of CFD approach in the three-phase FBRs are focusing on various multi-scale models, such as pseudo two fluid model, three fluid model, two fluid model + discrete particle method (DPM), CFD + the front tracking (FT)/front capturing (FC) + DPM etc. and the coupling fundamental theories of interaction forces. With the emphasis on the hydrodynamics of individual phase at macroscopic or microscopic level, the applications of CFD approach for three-phase fluidization system are analyzed. This review also proposes that future emphasis and challenges of CFD simulation for three-phase FBRs are to present specific and appropriate closure laws for interphase momentum exchange, incorporate chemical reactions transport phenomena properties into numerical models, and develop measurement techniques and provide more experimental data for three-phase systems.