ABSTRACT

The minimum fluidization velocity, umf, is a fundamental characteristic of a fluid­ ized bed. Its accurate prediction is important for the successful design and opera­ tion of a fluidized-bed process. At minimum fluidization conditions, the drag force by upward-moving gas equals the weight of particles lifted in the fluidized bed. The following relationship can be shown to hold (see the Nomenclature section for terms):

( 1)

or

where

Working on the assumption that the particles constituting the bed can be approxi­ mated by a constant value of ф and that £mf remains constant over the entire range of operating conditions of temperature and pressure, various investigators have proposed values of Cx and C2 on the basis of experimental results to be in the range 18.75-33.7 and 0.0313-0.0651, respectively [3].