PRESSURE-FLUCTUATIONS AT INDIVIDUAL GRID HOLES OF A GAS-SOLID FLUIDIZED-BED

For most work on bubble formation models in fluidized beds, a single orifice was used. This was not representative of commercial fluidized beds. Therefore, individual grid holes of a multi-orificed grid, in a large column (0.61 m diameter) with FCC catalyst were studied by placing pressure taps on top of individual holes. This is a simple and robust technique. Analysis of the pressure signals gave the average bubbling frequency and the probability distribution of bubbling frequency. The effects of superficial gas velocity, bed height-to-diameter ratio, and grid height were examined. An increase in superficial gas velocity caused an increase in the bubbling frequency. The probability distributions of the bubbling frequencies were log-normal.