Solids Flow Characteristics in a Loop-seal of a Circulating Fluidized Bed

Abstract

The hydrodynamics of solids (FCC) recycle in a loop-seal (0.08 m) at the bottom of the downcomer (0.08 m-I.D. x 4.0 m-high) in a circulating fluidized bed (0.1 m-I.D. x 5.3 m-high) have been determined. Solid now rate through the loop-seal increases linearly with increasing aeration rate. At the same aeration rate, the maximum solid now rate can be obtained at a loop-seal height-to-diameter ratio of 2.5. The effects of solid inventory, solid circulation rate and gas velocity on pressure balance around the CFB have been determined. At a given gas velocity and solid circulation rate, pressure drops across the downcomer and loop-seal increase Linearly with increasing solids inventory in the bed. At a constant solid inventory, pressure drops across the riser and the downcomer increase with increasing solid circulation rate but decrease with increasing gas velocity in the riser. The obtained solid now rate has been correlated with pressure drop across the loop-seal.