LIQUID AXIAL-DISPERSION CHARACTERISTICS OF 3-PHASE FLUIDIZED-BEDS WITH SMALL OR LIGHT PARTICLES

Three-phase fluidized systems comprising air/water/glass beads (diameter, 550μm), activated carbon particles (650 μm), polystyrene particles (3.1 mm) and Nylon-6particles (6.32 and 9.52 mm) were operated under gas-liquid cocurrent upflow conditions in a column of 6.5 cm inside diameter and 157 cm height. Experiments were conducted to investigate the axial dispersion coefficient using the axial dispersion model together with axial oxygen concentration profiles obtained from oxygen absorption experiments. As a result, the behavior of the axial dispersion coefficient in three-phase fluidized beds containing small or low-density particles is different from that in conventional three-phase fluidized beds containing heavy particles such as glass beads, silica, sand or various metal particles. The axial dispersion coefficient is an increasing function of liquid velocity but a decreasing function of gas velocity. Empirical correlations of the axial dispersion coefficient based on the correlation proposed by Kim et al. were obtained. © 1990, The Society of Chemical Engineers, Japan. All rights reserved.