Flow patterns of fine particles in a vibrated fluidized bed under atmospheric or reduced pressure

A vibrated fluidized bed under reduced pressure was constructed for the fluidization of cohesive, difficult-to-fluidize Geldart group C powders. The fluidization behavior of fine glass beads (6 mu m) in the vibrated bed was investigated at atmospheric or under reduced pressure. Fluidization of the glass beads could not be achieved if vibration was not applied. However, relatively stable fluidization could be obtained with vibration. A variation in the minimum fluidization velocity (u(mf)) with an increase in the vibration acceleration was noted at both pressure conditions but this effect was observed at a lower vibration acceleration under reduced pressure than at atmospheric pressure. This behavior could be related to the void fraction and flow patterns of the particle bed. (C) 1998 Elsevier Science S.A. All rights reserved.