Properties of a Large Bubble in a Bubble Swarm in a Three-Phase Fluidized Bed

Abstract

Experiments were performed to investigate the properties of a large bubble in a bubble swarm of a three-phase fluidized bed using video camera moving at the same speed as the large bubble. The rising velocity of a large bubble in a bubble swarm relative to liquid phase is extremely high compared to that of single bubbles, probably due to the wake velocity of the bubble swarm, which shows a distinct upward flow at the center and a downward flow near the column wall. Assuming that bubbles of uniform size are generated regularly from all holes in the perforated plate and that the interaction between bubbles in the lateral direction is negligible, the rising velocity of a large bubble in a bubble swarm can be roughly estimated by applying the concept of the wake velocity for in-fine bubbles. This means that the rising velocity of the coalesced bubble in a three-phase fluidized bed can be estimated from the terminal velocity of the coalesced bubble in isolation and the size of bubbles in the swarm also.