BUBBLE FRACTION AND VOIDAGE IN AN EMULSION PHASE IN THE TRANSITION TO A TURBULENT FLUIDIZED-BED

In the range of gas velocity from bubbling to turbulent fluidized beds, the radial and axial profiles of bubble fraction were measured together with variations of axial pressure fluctuation through a bed and the pressure gradient at several heights in the bed. The bed stucture was examined on the basis of bubble fraction and pressure data, and the following was found. In the transition to the turbulent fluidized bed, the increase of bubble phase, which is caused by the increase of gas velocity, is moderated and the emulsion phase expands more than that in the bubbling condition. Gas velocity at which the emulsion phase begins to expand, uc', is estimated by the correlation Rec' =0.663 Ar0.467. © 1990, The Society of Chemical Engineers, Japan. All rights reserved.