Identification and Control of Recycle Process

The recycle stream is important to increase and optimize the conversion of the feed and also the selectivity of the desired product. Even though recycle brings a lot of advantages, in the process dynamics and control point of view, it causes a lot of problem to the whole dynamics of the process. In this project, three control strategies are used to control the recycle stream in two CSTR connected in series. The control strategies are recycle compensator, Ziegler-Nichols tuning method and Skogestad tuning method. The performances of these control strategies and their combinations are compared based on certain aspects such as response time and offset value to find the best control strategy or combination of control strategies. To gain a more precise way to compare the performance of the control strategies, each one of them are analysed by using the integral error analysis which are the Integral of the absolute value of the error, Integral of the squared error, Integral of time-weighed absolute error.