INTERACTION BETWEEN HORIZONTAL TUBES AND GAS BUBBLES IN A FLUIDIZED BED

The purpose of the work described here was to study the interaction between horizontal tubes and gas bubbles injected singly into an incipiently fluidized bed of alumina powder. The bed was observed directly with X-rays and the bubble-tube interactions recorded on cine film for subsequent analysis. Various geometrical arrangements of tubes were investigated and both the horizontal and vertical distances between tubes were varied. In this way tube arrangements that led to bubble break-up and the resulting effect on the volumetric flow of bubble gas were established. The results indicate that under some circumstances horizontal tubes cause split bubbles to recombine thus nullifying the beneficial effects of splitting. In general when a bubble is split by a tube the sum of the volumes of the daughter bubbles is less than the volume of the parent indicating the some of the original bubble gas leaks into the emulsion phase of the bed during the splitting process. Furthermore the amount of leakage increases as the number of daughter bubbles increases. These facts could be of importance in the design of fluidized-bed reactors.