The local structure of gas fluidized beds —II. The spatial distribution of bubbles

Abstract The spatial distribution of bubbles in gas fluidized beds has been investigated with the measuring system described in Part I of this paper in beds of 0.10, 0.20, 0.45 and 1.0 m dia. The results indicate that in gas fluidized beds a characteristic flow profile of the bubble phase exists such that near the distributor a zone of increased bubble development exists in an annulus near the wall. This zone moves towards the vessel centre-line with increasing height above the distributor. The merging of the annular zone in the vessel centre-line marks the beginning of the transition of the fluidized bed to the state of slugging. The spatial flow profile of the bubble phase is shown to be responsible for the existence of characteristic solids circulation patterns in gas fluidized beds.