Bubble phenomena in aerated vibrated beds of small particles

Beds of various model particles were vibrated vertically at frequencies varying from 0-25 Hz and half-amplitudes from 0-4 mm. Alumina, glass and molecular sieve particles (27 mu m to 1400 mu m) were used as model particles. Air flow rates varied from 0 to 3 times the minimum fluidizing velocity through a single slot, a single central orifice or a multiplicity of orifices in the supporting bottom plate. With increasing vibration frequency, the bubble size was found to attain a maximum while the bubble rise velocity and frequency reach minima at the resonance point which is achieved only in vibrated beds of fine particles (d(p) <150 mu m). At the resonant point, bubble sizes are up to 215% their value in the absence of vibration. On the other hand, bubble frequencies and bubble rise velocities are up to 75% lower than their values in the absence of vibration.