FLOW CHARACTERISTICS IN PACKED AND FLUIDIZED ROTATING BEDS

Free particles in a rotating tapered cylindrical container are, as a consequence of the circular motion, forced radially outwards towards the circumference to form a packed annular bed. If the container wall is porous and a fluid is allowed to flow radially inward, the bed material may become fluidized. In the resultant centrifugal fluidized bed, radial accelerations many times one g can be generated, permitting much larger fluid flow rates during fluidization than are possible with a conventional fluidized bed. Entrainment of material can also be greatly reduced in such a geometry. The flow in both packed and fluidized beds in a rotating system is analyzed. Expressions are found for the shape of the bed as well as the distribution of particles in packed beds containing mixtures of materials having different size distributions and densities. Based on these results, equations predicting the pressure drop and radial flow distribution are deduced. The condition and location where initial fluidization of the packed bed occurs are predicted. Similarly, conditions in the fluidized state are analyzed, and it is shown that the tangential velocity distribution in the bed under these conditions is directly proportional to the bed radius. Experiments confirming the validity of the analytic models are conducted over a range of operating conditions for different bed materials. © 1979.