Minimum fluidization velocity and bed expansion of the inverse fluidized bed

Abstract

To define the fluid-dynamic properties of inverse fluidized beds, studies of the minimum fluidization velocity and bed expansion were performed in this work. The experiments were performed in an inverse fluidized bed of polypropylene and polystyrene particles in a cylindrical column using water and an aqueous glycerol solution of different concentrations as fluidizing medium. The dependence of the bed porosity on the superficial velocity of the fluid was determined experimentally for all the particles studied and different fluidizing media. The influence of fluidizing medium viscosity and particle density on the expansion of the inverse fluidized bed and on the minimum fluidization velocity was investigated. Comparison of the experimental data for the expansion of the inverse fluidized bed and the values calculated by the Richardson-Zaki correlation for the conventional fluidized bed showed some deviation, but the experimentally determined data were found to follow the shape of the Richardson-Zaki curve. In this paper, a correlation for the expansion of inverse fluidized beds is proposed.