HYDRODYNAMIC BEHAVIOR IN SPOUT-FLUID BEDS OF BINARY-MIXTURES OF PARTICLES

The objectives of this study are to investigate the basic fluid charac teristics for spout-fluid beds of binary mixtures of particles, and to compare the hydrodynamics with that of coarse particles only. As resu lts, two patterns of flow in spout-fluid beds, that is, spouting with aeration (SA) and spouting with fluidization (SF), were mapped as the regions depending on the relative values of the central and auxiliary gas flow rates. The operation regions for SA were reduced by the incre ase of the ratio of fine particles. Also, a correlation for predicting the minimum SF velocity was presented. It was found that the overall bed pressure drop under minimum SA condition increased linearly and al so the gas velocity through the annulus increased, as the proportion o f the auxiliary flow rate to a fixed total gas flow rate was increased for operation in the SA region of binary mixtures. The values as desc ribed above were smaller than those in the case of using coarse partic les only. Moreover, the particle circulation rate increased and also b oth the average spout diameter and the fountain height decreased, as t he proportion of the auxiliary flow rate to a fixed total gas flow rat e was increased.