PARTICLE-PARTICLE COLLISIONS IN LIQUID-SOLID AND GAS-LIQUID-SOLID FLUIDIZED-BEDS

A new technique allows for the detection of particle-particle collisions in liquid-solid and gas-liquid-solid fluidized beds from perturbations in the diffusion current of tethered electrodes. A tethered particle, near its anchorage point, can give a good estimate of the collision frequency of a free-floating particle. The number of collisions to which fixed mass transfer probes were subjected was only about 25% of the number of collisions to which a tethered electrode was subjected. In the absence of gas, the collision frequency was maximum at minimum fluidization. The injection of gas into the fluidized bed increased the collision but further increases in gas velocity reduced the collision frequency.