BEHAVIOR OF RISING BUBBLES IN A GAS-FLUIDIZED BED AT ELEVATED TEMPERATURE

Abstract

Bubble size and the rise velocity of bubbles in fluidized beds at high temperature were measured by the electric capacitance method using an injection tube and a sintered-plate distributor. The bubble frequency increased with rise in temperature and the bubble size was rearranged as a function of bubble frequency and gas flow rate. The rise velocity of bubbles in swarms was divided into two terms, i.e., the rise velocity of isolated bubbles and the accelerated quantity due to bubble coalescence. The latter was correlated as a function of the ratio of distance between two successive bubbles to bubble radius. A model of bubble shape was proposed and effectively used to estimate the empirical coefficients included in the correlation for bubble size and rise velocity of bubbles.