Mathematical models for macro-scale mass transfer in airlift loop reactors

Inter-phase mass transfer is an important issue for design and development of airlift loop reactors of high performance in either chemical or biochemical applications. In this work, the axial dispersion in both gas and liquid phases was taken into account for modeling the macro-scale mass transfer in airlift loop reactors. Finite difference method was used to numerically solve the differential equation system of the mass transfer model. For oxygen, the numerical results showed that the solute concentration of the gas phase can be treated as constant and the flow pattern of the liquid phase as a plug flow. Based on the conclusion obtained from numerical solution, the mass transfer model was simplified and the analytical solution of the simplified model was obtained. Comparison between the numerical and analytical solutions showed that the simplification of the model was reasonable and there was almost no influence on the calculated results. Experimental measurements on the mass transfer rate were carried out to verify the mathematical model. The comparison between the experimental and calculated results showed that the mass transfer model has satisfactory prediction ability and can be used to describe the mass transfer process in airlift loop reactors.