Fast fluidization regime mass transfer

In general, nonuniform structures, in both time and space, is widespread in bubbling, turbulent, and fast fluidization regimes. On the one hand, such nonuniformity can enhance the mass and heat transfer of a bed. On the other hand, it decreases the contact efficiency of gas and solids and makes the scale-up rather difficult. Internals are usually introduced not to eliminate the nonuniform flow structure completely but to control its effect on chemical reactions. The function of internals varies in different fluidization regimes, as do the types and parameters of internals. Taking these purposes into consideration, internals may be successfully applied to catalytic reactors with high conversion and selectivity, and some other physical processes. 

Models similar to those described above for the bubbling regime may also be used to characterize beds operated in the slugging, turbulent and fast fluidization regimes, with appropriate changes in the relationships used to describe the mass transfer and other model parameters. The conditions needed to ensure that the bed is operating in these regimes are presented in Section 2. 

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