A NEW BED-COLLAPSING TECHNIQUE FOR MEASURING THE DENSE PHASE PROPERTIES OF GAS-FLUIDIZED BEDS

A new bed-collapsing technique, the "optimum dual-drainage method", is proposed to determine the dense phase properties in gas-fluidized beds of fine powders. The effects of gas flow resistance of the distributor and the windbox volume on the bed collapse of UO2, ammonium uranyl carbonate (AUC) and alumina powders have been determined in a 0.07-m I.D. x 2.5-m high Plexiglas column. In the single-drainage method, the measured voidage and gas velocity in the dense phase increase with increasing windbox volume, gas flow resistance of distributor and gas velocity whereas in the optimum dual-drainage method, the dense phase properties are found to be independent of distributor resistance and windbox volume. It has been found that the period of bed expansion after the bubble escape stage on the bed-collapse curve varied with the type of powders, and the bed expansion was most pronounced in the bed of UO2 powders in the single-drainage method. Momentum transfers from the windbox to the bed have been correlated with the pertinent experimental variables (U(o), V(w), K(d)).