Radial particle mixing in gas-solids fluidized beds

Difficulties involved in experimentally determining the mixing coefficients of particles in a gas-solids fluidized bed are well known. From the theoretical point of view, the mechanism of particle mixing in such a fluidized bed is influenced profoundly by complicated and stochastic phenomena, such as jetting and bubbling. It appears that a sufficiently effective deterministic approach is not available to analyse the mechanism. In the present work, the particle mixing in the radial or lateral direction of a gas-solids fluidized bed was studied by using heated particles as the tracer particles. The transient concentration distribution of these particles in the lateral direction was obtained by means of an impulse response technique; sensitive thermocouples were used for measurement. The mixing coefficients of particles have been estimated from the distribution by a stochastic approach, and the resultant coefficients are compared with those obtained by other investigators.