L-valve behaviour with solids of different size and density

A small diameter L-valve, 27 mm i.d., was inserted in a circulating fluidized bed loop with no solids reservoir and operated under different experimental conditions. Five materials (three sands, a spent FCC [fluid cracking catalyst] and a magnetite), belonging to groups A and B of the Geldart classification, were selected in order to investigate separately the effect of particle size and density. For each solid, the workability range of the apparatus was determined by varying the flow rate of the aeration gas and measuring the corresponding solids flow rate through the valve. The static pressure balance around the loop was determined for each experimental condition. Results were compared with those of previous investigations in order to correlate the pressure drop throughout the L-valve with the solids discharge flux. (C) 1998 Elsevier Science S.A. All rights reserved.