Feedback Control of Processes with Recycle

The loss in control loop performance for processes with recycles is quantified under two situations: (i) where the recycle dynamics is neglected for purposes of control design and (ii) where the controller type is restricted to the widely employed PID type controllers. It is demonstrated that, under many situations, the recycle dynamics and the simple structure of the PID controller do not hinder the achievement of high control loop performance using feedback control strategies.