Hydrodynamic characteristics of a three-phase inverse fluidized-bed column

Gas–liquid–solid inverse fluidized beds were studied, in which the gas and the continuous liquid phase flow countercurrently fluidizing particles that are lighter than the liquid. Conductivity and static pressure measurements were combined to provide the vertical profiles of the gas, liquid and solid holdup, in beds of 4‐ or 6‐mm polypropylene particles with a density of about 870 kg/m3. Various bed heights were obtained with different measurement methods. The minimum fluidization velocity was estimated using the bed static pressure gradient. A new transition velocity, called the uniform fluidization velocity, was identified using conductivity measurements. This is the superficial liquid velocity at which the fluidization quality becomes the same throughout the bed.