Experimental analysis of bed expansion properties in gas-liquid-solid three phase fluidized beds

Two types of particles with approximate diameter and different densities, plastic beads (wet bulk density 1 273 kg/m³ and mean diameter 750 μm ) and pottery (wet bulk density 1 680 kg/m³ and mean diameter 800 μm), were selected to study bed properties of gas-liquid-solid fluidization. The gas was oil-free air and the liquid was water. The plexiglas fluidized-bed column was 0.13 m in diameter, 4.75 m high, and the working water column was 3.5 m height to ensure sufficient space for bed expansion. To study the effects of gas or liquid velocities on bed expansion, the heights of solid phase were measured in ranges of superficial liquid and gas velocities 0-13 mm/s and 0-12 mm/s, respectively. The results show that the bed height should be decreased with increasing gas velocity when the liquid velocity is lower. However, the bed expansion ratio should be over zero at higher liquid velocity, which should be decreased firstly and transited to be increased from the critical gas velocity with increasing gas velocity. The bed expansion ratio was increased with increasing liquid velocity except of high gas velocity. Compared to the plastic particles, that of the pottery with higher density should be higher at the same gas and liquid condition.