Holdup characteristics of three-phase fluidized beds of mixed particles

Abstract

The phase holdup characteristics of two(gas-liquid, liquid-solid) and three(gas-liquid-solid) phase fluidized beds have been studied in a 15cm diameter fluidized bed. Air and water were used as gas and liquid phase throughout the study, and three different sized glass balls were employed for uniform and mixed particle systems. The effects of gas velocity (0-12 cm/sec), liquid velocity (0-14 cm/sec), particle size (1.631, 2.916 and 7.850 mm) and particle weight fractions on the individual phase holdups and bed expansion were measured. Individual phase holdups were measured using a pressure profile technique. In the beds of mixed particles, the phase holdups were determined for the beds with no particle segregations. In three-phase beds of monosized particles, the liquid holdup increased with increasing liquid velocity and with decreasing particle size, whereas it decreased with increasing gas velocity. However, gas holdup increased with increasing particle size and gas velocity, and was nearly independent of liquid velocity. In the beds of mixed particles, the bed contraction or expansion phenomena, which could be observed in the beds of monosized particles, did not prevail at the same experimental conditions. The variation of bed porosity and liquid holdup showed minimum depending on the weight fraction change of the component particles. The minimum fluidization velocity of the mixed particle system was lower than that of the large component particles. Correlations of the phase holdups which can be applicable to both monosized and mixed particle systems were given for the individual phase holdups as follows ; ◁수식 삽입▷(원문을 참조하세요)