STUDIES ON THE STEADY-STATE BEHAVIOR OF GAS-LIQUID REACTORS

Various aspects in modeling and analysis of the steady-state behavior of gas-liquid CSTRs and bubble column reactors are studied with emphasis on model prediction of uniqueness and multiplicity of steady states.The generalized reaction factor is utilized in investigating the influence of liquid evaporation on occurrence of steady-state multiplicity in a nonadiabatic gas-liquid CSTR with an irreversible second-order reaction. Multiplicity regions and patterns are determined in parameter space, and analyzed for volatile and non-volatile liquids. It is found that large differences in model predictions of the region and number of multiple steady states are possible.Improved steady-state models are developed for nonadiabatic gas-liquid CSTRs and bubble column reactors for the industrially-common, fast pseudo-first-order reaction. The models are used for the derivation of necessary and sufficient criteria for steady-state uniqueness and multiplicity and thus limitations of previous models for both reactor types with this class of reactions are made evident.An analysis of the irreversible second-order reaction occurring in an isothermal gas-liquid CSTR under diverse kinetic conditions and operating modes is finally presented to delineate the behavioral features of this reacting system. The analysis also demonstrates the limited usefulness of the so-called explicit enhancement factors in the simulation of gas-liquid reactor behavior.For irreversible second-order gas-liquid reactions, the influence of volatility of the liquid reactant on enhancement of gas absorption by chemical reaction is investigated via derivation and numerical analysis of an approximate, generalized reaction-factor expression. The regimes of influence of liquid volatility are identified, and it is found that, in general, volatility is detrimental to enhancement of gas absorption.