A Comparison of Different Control Design Methods for the Linearized CSTR Temperature Model

Continuous Stirred Tank Reactor (CSTR) has particular importance in chemical industry. CSTR has usually a nonlinear behavior which makes it difficult to control. The reactor has two parameters: the concentration and temperature of mixture both of which are uncertain. This case of CSTR has large disturbance in domain. In order for disturbance rejection, a controller has to be designed. In this paper, for modeling the CSTR system, first, the PI and PID controllers are designed by two methods, the automatic with Matlab Simulink and Ziegler-Nichols (Z-N) method. Then, reset control is replaced and tuned by their parameters. The main aim of this work is to compare the output responses (temperatures) of controllers with each other. In this work a reset controller is proposed for the thermal reactor model. Due to complexity of control of this plant, different design methods should be evaluated for disturbance rejection and input tracking. The results show that the reset controller is better than the PI controller in disturbance elimination. Finally, controller’s output response is investigated for improvement in disturbance rejection and change in the set-point.