Non-ideal flow in chemical reactors and the residence time distribution

Abstract

Continuously operated chemical reactors with idealised flow patterns have played a central conceptual role in the development and teaching of chemical reaction engineering. Flow patterns in real processing equipment often depart from the two idealised types: the plug flow reactor; and the perfectly mixed stirred tank. In plug flow all fluid elements crossing a given plane are moving at the same speed and in the same direction, i.e. their velocities are all equal. Consideration of non-ideal flow leads to two broad questions. How can non-ideal flow be quantitatively described? What are the consequences of deviations from idealised flow, particularly with respect to heat transfer, mass transfer and chemical reaction? Some non-ideal flow patterns can be decomposed into a scheme of simpler elements, such as plug flow, perfectly mixed, dead zone and short circuit, which are interconnected in series and in parallel.