Investigation of the bed types and particle residence time in a staged fluidised bed

Perforated plates were added to section the column and a fluidised bed was modified as a counter-current staged fluidised bed. The bed types and particle residence time were investigated in single-stage and two-stage fluidised bed systems. A stable bed (column I.D. = 3 cm, plate opening ratio = 0.2) exists at: 0.55 m/s ≦ gas velocity ≦ 1.70 m/s; 0.05 kg/s m2 ≦ solids feeding rate ≦ 1.50 kg/s m2. The bed types in the single-stage bed system and in the two-stage bed system can be different even at the same operating conditions and the differences are due to the different particle accumulating probabilities above the plate. In the particle residence time experiments, the mean residence time increases with the increase of the gas velocity and/or the solids feeding rate. The addition of one plate to the single-stage bed system increases 40% of the mean particle residence time. The one-parameter and two-parameter Continuous Stirred Tank Reactor (CSTR) models were used to predict the particle residence time in both systems. The results indicated that both models could quantitatively predict the particle residence time in the current staged fluidised bed systems.