Question

Briefly discuss the difference between “plug flow” and “perfect mixing” and give examples of reactors which most closely fit these models.

Answer 1

In plug flow reactor, the composition of fluid varies from point to point along the flow path, composition is a function of location. It follows first order decay and growth kinetics. That is growth and decay follow exponential curve. Example, flocculation, BOD decay in waste water treatment, aeration,

Flow in flow cell, growth of biofilms, open flow

In completely mixed reactor, the composition of every particles in incoming, outgoing, and in between the reactor is same and thus follow straight line parallel to y axis. Feeding, reaction, and outgoing are at the same time of the particle. Example coagulation i.e coagulant mixing.