Abstract
The behaviour of cracking catalyst with mean size 60 mu m fluidized by air at pressure from 1 to 7 bars was observed by cinephotography in a two-dimensional column. A series of runs was performed with constant gas superficial velocity. The size and number of bubbles passing through the bed decreased markedly as the pressure was increased, the change being most marked around 4 bars. The decrease in bubble flow rate was accompanied by an increase in the void fraction of the particulate phase. The dominant mechanism of bubble splitting at all pressures was by division from the roof, and the maximum stable bubble size decreased with increasing pressure.