Modeling of noncatalytic fluid-solid reactions: The quasi-steady state assumption

Abstract

An isothermal, topochemical model for noncatalytic fluid-solid reactions, in spherical pellets, is formulated, solved numerically, and investigated experimentally. The equations are transformed into dimensionless form in order to introduce characteristic dimensionless groups. The dimensionless groups represent the relative effects of the diffusional, fluid film transport, and chemical reaction rates on the system, as well as the ratio of the molar density of the reactant fluid to that of the reactant solid. The model is solved with and without the quasi-steady state assumption in order to investigate the effects of the values of the dimensionless groups on the error introduced by this assumption. The model, without the quasi-steady state assumption, is shown to be an accurate representation of a resin exchange system, and reduces to the quasi-steady state model for appropriate values of the dimensionless groups.