The Physical Contacting of Reactants

Summary

The rates of chemical reactions can in many cases be limited by the rates of transport phenomena that act on the “intermediate scale”, that is to say on a scale on the order of millimeters. In this chapter the most important of these transport phenomena are reviewed: micro-mixing in single phase systems, and mass transfer in two- phase systems, particularly in dispersions. The concept of reactor configuration is introduced here. This concept denotes the way two or more phases are arranged with respect to each other. This may have consequences for the rate of chemical reactions, A two- or multi-phase system may also be used for separating reaction products in the reactor. Mass transfer in solid/gas, solid/liquid and liquid/gas dispersion processes are reviewed, and a brief survey is given of three phase-contacting. All these physical processes are considered without the occurrence of chemical reactions.