Solids flow between interconnected shallow fluidized beds

Many industrial processes utilising two or more fluidized beds are connected such that one bed flows through an opening into the other. By operating regions of the two beds at different superficial gas velocities, a bulk density difference can be created between them to effect a solids transfer through a submerged opening. The resultant flow of solids between fluidized beds of sand (194 μm and 224 μm) is modelled on the basis of a liquid analogy and force-momentum balances. The correct functional dependency of the solids flow rate is predicted for a range of gas velocities; experimental results are 70–90% of the predicted values. The prediction of the solids flow rate for changes in the size of the openings between the beds is less satisfactory, possibly because of the return flow of solids which is associated with the forward flow.