Flow rate of solids through recycle chamber of loop seal in a circulating fluidized bed

Abstract

This study investigated the flow rate of solids through the recycle chamber of a loop seal in a circulating fluidized bed (CFB) at atmospheric pressure and temperature. Flow characteristics of alumina particles were measured in the downcomer, horizontal passage, recycle chamber, and riser (0.05 m i.d., 2.7 m high).As the gas velocity in the riser increased, the pressure drop in the downcomer decreased, and thus, the aeration rate required at the bottom of the supply chamber to attain the minimum fluidization state for the bed of the downcomer increased. Based on experimental data, relationships that could predict the flow rate of solids through the recycle chamber Gs,r were derived by extending the correlation for the solids flow rate through the bubbling fluidized bed that discharged solids via overflow exit. Gs,r increased in proportion to the gauge pressure at the base of the recycle chamber. When the riser was under the fast bed condition, the back pressure against the flow of solids coming from the recycle chamber to the riser appeared significantly, and Gs,r was inversely proportional to the gauge pressure at the base of the riser. The derived relationships for Gs,r were in good agreement with measured data.