10 - Fluidization quality

Abstract

This chapter deals with the explanation of fluidization quality. The term “fluidization quality” is applied to describe the various fluid-dynamic conditions brought about by the fluidization process itself. The optimal combination of these conditions depends on the particular application in hand. Thus if the bed is to be employed as a filter, a stable, homogeneous particle suspension is desirable. The conversion in a fluidized reactor, on the other hand, depends on the extent of heat and mass transfer within and between the phases, and is thus strongly influenced by the mixing action of bubbles and other inhomogeneities associated with the unstable fluidized state; also on the fluid and particle flow characteristics that reflect such things as bubble size and frequency, fluid residence time distribution, phase holdups, and many other basic features that together determine the fluidization quality. The chapter also examines the relation of predicted ɛmb values to fluidization quality. This turns out to provide considerably more insight into bed behavior than has hitherto been appreciated, generalizing reported conclusions concerning the influence of measured ɛmb determinations over limited regions of applicability.