Approximate Prediction of Gas-Solid Conversion in Fluidized Bed Reactors

Abstract

A simple method is proposed to evaluate the performance of fluidized bed reactors where an nth-order gas-solid reaction occurs. The method takes into account the fluid dynamics of the fluidized bed by a two-phase flow model and the rates of diffusion in the solid reactant particles (internal and external) by a simple particle model. Approximate analytical expressions are derived in terms of three effectiveness factors: interphasic, external and intraparticle. These account for the contribution of fluid-dynamic and diffusional resistances to the overall mass-transfer resistance. Gas conversion is expressed in terms of four dimensionless governing quantities and the reaction order, in this way facilitating computations. Limiting cases of the general solution are discussed by comparison with analytical solutions found in literature. The methodology can be applied to catalytic or non-catalytic systems under isothermal conditions, where one heterogeneous reaction is involved.