Experimental Study and Numerical Simulation of Bubbling Fluidized Beds with Fine Particles in Two and Three Dimensions

The present study provides a deeply analysis of the flow behavior of bubbling fluidized beds with fine particles in two- (2D) and three-dimensional (3D) conditions, and computational fluid dynamics (CFD) simulations of agglomerates fluidization are carried out coupled with the modified agglomerate-force balance model, correspondingly. The experimental results indicate that the fluidized bed can be divided into bottom unfluidized, middle ascending fluidized, and upper descending back-mixing sections. The local solids volume fraction value ranges from 0.11 to 0.30, which depends on the interaction between bubble phase (epsilon(s) = 0-0.04) and emulsion phase (epsilon(s) = 0.26-0.30). The wall effect appears to be weakened, and the cohesive particles fluidize more uniformly in 3D fluidized beds. The simulations are in reasonable agreement with the experimental findings. However, at the top region of the bed the predicted solids holdup slightly deviates from experimental measurement. The vector plots of computed agglomerates velocity support the central and wall falling down-both sides rising up flow pattern of solids, two core-annular flows exist in the bed, which can be also observed experimentally.