Journal of Chemical Engineering of Japan, Vol.36, No.1, 98-104, 2003
Role of pressure drop in the counter-current multistage fluidized bed of the solid-liquid system - Effect of non-uniform liquid flow
An experimental study on the pressure drop has been carried out for a counter-current multistage fluidized bed having a downspout as well as on the particle holdup relating to a pressure drop. Three kinds of fluidized beds were used; a 3-stage column with 48.6 mm i.d., a 2-stage column with 99.6 mm i.d. and a batch-wise single stage column without downspout. The holdups for three kinds of ion exchange resins in the multistage fluidized bed are expressed by the correlation obtained for a batch-wise single stage fluidized bed. The pressure drop of the 48.6 mm column, however, varied little with the superficial liquid velocity, while that of the single stage column with the same diameter decreased with an increase in liquid velocity as expected from the theoretical consideration. A 99.6-mm column, where diameter of the downspout is small in comparison with the column diameter, shows that the pressure drop in the multistage column was the same as in the single stage column. By covering a part of stage-partitioning screen of the 99.6-mm column with a plate producing a non-uniform liquid flow, the pressure drop behavior approached the one that is observed for a 48.6-mm column. Discrepancy of the observed and the estimated pressure drops for the multistage fluidized bed is ascribed to the non-uniform flow generated by the downspout which is indispensable to the multistage operation.