Mechanics of fluidization in centrifugal beds.

The effects of operating a fluidized bed in a force field resulting from centrifugal motion are investigated. Such a Centrifugal Fluidized Bed System consists of a cylindrical porous distributor, with its axis of rotation parallel to the gravitational acceleration. The bulk solids in the bed are held in the annular region at the circumference of the device by radial acceleration, while fluidizing gas flows radially inward through the distributor. Unlike conventional fluidized beds operating vertically against gravity, the allowable range in flow rate of the fluidizing gas, bounded by minimum fluidizing velocity and elutriation, may be extended considerably by varying the angular velocity of the bed. This makes it possible to achieve higher turndown ratios and gas flow rates per machine volume than are possible with stationary beds, making the system quite attractive for a variety of commercial applications including coal combustion. Experiments were performed near atmospheric temperature and pressure using glass particles as bed material and air as the fluidizing gas. Theoretical models are presented and compared with experimental results for bed pressure drop, minimum fluidizing velocity, and particle elutriation velocity. The system parameters varied are fluidizing gas flow rate, distributor