Design of Internal Model Controller for an Open Loop Unstable CSTR Process

A CSTR is an Continuously Stirred Tank Reactor with the main function of agitation and to achieve constant composition. It has an important role in chemical process plants. A CSTR has an higher degree of nonlinearity when compared with other chemical reactors, this is mainly due to the temperature variations that occur because of uncertainity in feed. Hence, temperature control is a strenuous task. The proposed work focusses on control of temperature in a jacketed chemical reactor, by effectively designing a internal model controller (IMC). The process is a open loop unstable system due to the effect of scale-up on the steady state and other dynamic characteristics. The proposed digital controller is capable of providing system stability, set point tracking and disturbance rejection. The simulation result shows the suitability of using the proposed controllers for control of the unstable CSTR process.