High temperature and high pressure three-phase fluidization - Bed expansion phenomena

Bed contraction and expansion are investigated in a high pressure and high temperature gas-liquid-solid fluidized bed. The bed is operated at pressures from 0.1 to 17.4 MPa and temperatures from 20 to 94 degrees C. The bubble dynamic behavior in the bed is visualized through transparent windows. The study indicates that the pressure and temperature affect the bed expansion and contraction, mainly through the variations in bubble behavior and the changes of liquid properties. The extent of bed contraction decreases with an increase in pressure and/or temperature for 2.1 mm glass beads. This decrease is attributed to the reduction in size and number density of large bubbles. However, for 1 mm glass beads, bed contraction is observed to be more pronounced under higher pressures. The generalized wake model is modified to account for bed expansion or contraction phenomena by taking into account the bubble size distribution effects.