BUBBLE PROPERTIES IN LARGE-PARTICLE FLUIDIZED-BEDS

Bubble properties were studied in a two-dimensional bed and a square bed 1. 2m wide fluidized with large particles (1 mm average diameter). Horizontal and vertical arrays of optical probes were used to measure the bubble characteristics. The velocity of a bubble depends on the proximity of bubbles above it; the average velocity is closely approximated by the J. F. Davidson and D. Harrison expression. At high flow rate, the initial bubble size is closely estmated by a Froude number correlation. The rate of bubble coalescence is well-correlated by the void fraction of bubbles in the bed and can be predicted by allowing for the random spatial distribution of bubbles. A one-dimensional model for the bubble growth is presented.