CFD-DEM investigation of the flow characteristic of biomass particles and heat carrier in a novel V-shaped down-tube pyrolysis reactor

During biomass thermochemical conversion, addition of inert heat carriers such as sand, metal and ceramic balls into the reactor can effectively promote the flow mixing and conduction heat transfer of biomass. Therefore, it is important to understand the flow behavior of the binary mixture containing biomass and heat carrier for efficient utilization of biomass energy. In this study, computational fluid dynamics and discrete element method (CFDDEM) were used to evaluate the flow behavior and law of the binary mixture of heat carrier and biomass in a novel down-tube pyrolysis reactor. The results show important effects of different ceramic ball sizes and different mass ratios on the flow behavior of binary mixtures. Under the same mass ratio, the smaller the particle size of ceramic balls were, the greater the effect to promote the motion of biomass particles. The fluid-like motion changed more obvious with the increase of mass ratio and biomass particles.