The unique hydrodynamic features of the gas–liquid–solid circulating fluidized bed downer reactor make it a subject worthy of research attention. The CFD–VOF–DEM model is used to enable the analysis of the dynamic spatiotemporal characteristics of both bubbles and particles in the downer. The presence of dense particle dispersion leads to pronounced bubble deformation and reduces the bubble oscillation amplitude. The large particles enhance bubble oscillation, thereby prolonging the bubbles’ rise path. The bubble-squeezing and wake effects generate the nonuniformity of particle spatial distribution. The enhanced inertial effect resulting from larger and heavier particles contributes to the spatial uniformity of the particle distribution. While bubbles alter particle trajectories, they do not cause significant particle backmixing. Continuous bubbling flow exacerbates spatial nonuniformity in particle distribution. However, it exerts only a limited influence on particle backmixing. This study offers fundamental hydrodynamic knowledge that serves as a basis for the future design and implementation of gas–liquid–solid circulating fluidized bed downer reactors.
Zhan et al. (Fri,) studied this question.