Study on terminal velocity of objects moving in fluidized beds

The terminal velocity of an object moving in gas-solid fluidized beds was experimentally and theoretically studied. The results indicate that the apparent viscosity of the bed increases with the increase of fluidized particle size, but it varies little when some coarser particles are mixed with the fluidized particles. The resistance to a rising object is one order magnitude greater than that to a settling object. The efficient buoyancy on a flaky object, which lies flat on the gas distributor, is much less than that calculated according to the Archiimedes' principle. An object does not always rise or settle with minimal projective area owing to the radial motion of fluidized particles, but the bar-shaped objects tend to rise or settle with minimal projective area in the lower part of the bed.