Experimental fluidization results were compared for three gas distributors with the same opening ratio but different orifice in clinations (30,45 , and 90 ). Hydrodynamic studies were con ducted with glass beads (diam...Experimental fluidization results were compared for three gas distributors with the same opening ratio but different orifice in clinations (30,45 , and 90 ). Hydrodynamic studies were con ducted with glass beads (diameter 154p.m) to evaluate the impacts of orifice inclination and static bed depth on pressure drop, pressure drop fluctuations, bed expansion, and minimum fluidization velocity. Solids residence time distributions were determined using phosphoresce nt tracer particles (mea n diameter 76 pm), activated by ultraviolet light. The bed pressure drop was higher with the inclined-hole distributors and increased with static bed height. In a shallow bed, the inclined-hole distributors gave less expansion;however, in deep beds, the orifice angle had negligible influence on bed expansion. The minimum fluidization velocity varied with static bed height for the inclined-hole distributors and was higher for steeper angles. The turnover time estimated using bubbling-bed equations matched the experimental results well for vertical mixing. Probes and ports at the walls of the fluidization column reduced the dense-phase downward velocity by up to 40%. The tangential particle velocity was highest for the 30 -hole distributor and decreased with increasing orifice angle. Tangential mixing was described by a dispersion model;the dispersion coefficient for the inclined-hole distributors was approximately twice that for the 90 -hole distributor in a shallow bed.展开更多
文摘Experimental fluidization results were compared for three gas distributors with the same opening ratio but different orifice in clinations (30,45 , and 90 ). Hydrodynamic studies were con ducted with glass beads (diameter 154p.m) to evaluate the impacts of orifice inclination and static bed depth on pressure drop, pressure drop fluctuations, bed expansion, and minimum fluidization velocity. Solids residence time distributions were determined using phosphoresce nt tracer particles (mea n diameter 76 pm), activated by ultraviolet light. The bed pressure drop was higher with the inclined-hole distributors and increased with static bed height. In a shallow bed, the inclined-hole distributors gave less expansion;however, in deep beds, the orifice angle had negligible influence on bed expansion. The minimum fluidization velocity varied with static bed height for the inclined-hole distributors and was higher for steeper angles. The turnover time estimated using bubbling-bed equations matched the experimental results well for vertical mixing. Probes and ports at the walls of the fluidization column reduced the dense-phase downward velocity by up to 40%. The tangential particle velocity was highest for the 30 -hole distributor and decreased with increasing orifice angle. Tangential mixing was described by a dispersion model;the dispersion coefficient for the inclined-hole distributors was approximately twice that for the 90 -hole distributor in a shallow bed.
