Interfacial temperature rise and multiplicity in nonisothermal gas-liquid CSTRs

Abstract

For exothermic gas-liquid reactions.the interfacial temperature affects the gas-solubility, interfacial reaction rate, mass transfer rate and the bulk temperature of the reactor. An overall heat balance on the reaction-diffusion 'film' relates the interfacial temperature to the bulk variables (temperature, concentration), and the interfacial variables (enhancement factor, etc.). While the interfacial balance shows (apparent) multiplicity of interfacial temperature for a given bulk temperature, uniqueness results when the interfacial balances are solved together with the mass and energy balances for the reactor bulk. It is shown that the state of interface and bulk are intimately related, and thus, consideration of interfacial temperature does not increase the multiplicty of a gas-liquid CSTR. Simple a priori estimates are derived for the interfacial temperature. All of the results are found to be rather independent of kinetic details. The interfacial temperature rise is encouraged by low interfacial heat and mass transfer coefficients, by small liquid residence time in the bulk and by increased heat losses from the reactor bulk.