A comparative investigation on mixing and dispersion in fluidized bed equipped with a conical distributor for catalytic processes

Fluidized beds find wide application in catalytic processes where optimal contact between solid and gaseous phases is required. Spout-fluidized beds, in particular, can improve the mixing of the solids and thus the process efficiency. Numerical models are able to investigate bed behavior while avoiding the need to perform time consuming experiments. The present research explored experimentally and numerically the fluid-dynamics of a spout-fluidized bed equipped with conical distributor for fluidization of Geldart B particles. The MFIX-Two Fluid Model software was validated using experimental high frequency time-series of pressures obtained for a bed of glass beads, examining the change of signal characteristics upon variation of feed partition between spout and distributor, and a good agreement was observed for well-developed fluidization regimes (surface gas velocity/Umf ≥ 1.4). The model was thus used to predict the mixing for a bed of alumina particles and obtain correlations of the average diffusion and lateral coefficients with the dimensionless parameters of spout to total feed ratio and total fluidization ratio. Both coefficients showed Pearson type dependence on the former parameter and polynomial dependence on the latter. These correlations may be used to obtain guidelines for optimization of solid mixing regime in spout-fluidized beds.