Fluidization of particles

The correlation due to Kelly (1965) indicates relatively modest coefficients below 200Wm-2K i for particles up to about 8mm in diameter. The equations proposed by Vazquez and Calvelo, based on the Chilton-Colburn j-factor model, suggest rather higher coefficients of fhe order of 300-400for the fluidization of particles up to 20mm in diameter at gas velocities reasonably in excess of those required for minimum fluidization. 

Countercurrent bubble flow with liquid-supported solids, which can be affected by downward liquid fluidization of particles having a density lower than that of the liquid, has been referred to as inverse three-phase fluidization. The mass transfer potential of such a countercurrent operation is worthy of study, especially for cases in which dispersion of the gas rather than the liquid is called for and the required gas-liquid ratio and throughput can be effected without flooding. In contrast, the corresponding cocurrent mode has received more attention than all other cases and constitutes the majority of the literature on three-phase fluidization. 

In most practical applications of dispersed multiphase flows, the suspension consists of non-spherical particles having different diameters. The range of particle diameters or particle size distribution may (non-reactive fluidization of particles) or... 

Fluidization of particles with density only slightly greater than the liquid does not create the large bifobles characteristic of fluidization with gases however, other fluidization phenomena such as movement of particles and expansion of the bed take place. 

Froude number A widely used dimensionless number, Fr, that represents the influence of gravity in the power relationship for fluid systems such as pumping, mixing in unbaffled tanks and reactors, and in determining the extent of fluidization of particles in a fluidized bed. For a fluidized bed it is expressed as ... 

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