Comparison of Performance of Recycle Reactors with Plug Flow Reactors

Consider a second-order reaction (2A → B) with a reaction rate, . This reaction takes place in a plug flow reactor or a reactor with recycle. The recycle ratio is the volume of fluid returned to the reactor entrance divided by the volume leaving the system.
The ratio of the volume of the recycle reactor to the volume of the plug flow reactor, , is plotted versus the dimensionless exit concentration , where and are the concentration of the species A at the inlet and outlet, respectively.

There are two limiting cases:
gives the plug flow reactor without recycle case (the horizontal green line);
gives the mixed flow reactor behavior (the red line segment).
The recycle plug flow reactor presents a convenient way to approach the mixed flow reactor by increasing .