Modeling Mass Transfer Accompanied by Fast Chemical Reactions in Gas/Liquid Reactors

For the development of simulation models for gas/liquid reactors it is necessary to describe the mass transfer between the gas and liquid phase for pure physical absorption as well as for the case of chemisorption. As classical balancing approaches for the description of absorption and absorption accompanied by a fast chemical reaction lead to completely different equation systems, an a priori decision about the absorption regime is necessary. Depending on time and locus, different reaction conditions may occur within a reactor, so that an a priori decision is not possible. For practical purposes a hybrid model, which accounts for slow and fast chemical reaction conditions in like manner, seems to be an efficient approach. The model presented here, which can be developed from the classical approach with minor modifications, describes both pure absorption and absorption accompanied by a fast chemical reaction, as well as the transition regime. To use this model for a given reaction syst em, a depletion factor must be calculated beneath the classical enhancement factor. The depletion factor describes the ratio of the amount of substance leaving the liquid film unconverted to the amount of substance absorbed from the gas phase. A first implementation of this method was done in the software code BSR, a simulation programme for bubble column reactors.