Cascade - PID control of a nonlinear chemical process

Control of chemical processes in presence of strong online nonlinearities and extreme sensitivity to disturbances is a major challenge. For the successful operation of any complex chemical process, it is desirable to understand its dynamic characteristics. A good understanding of the dynamics of chemical processes effectively results in efficient control system design. The controller designed for nonlinear complex chemical processes should have the capability to supress the effect of practical variations that occur in the process. One of the most common choice is PID (Proportional Integral Derivative) controller, but PID controller finds it difficult to deal with the perturbations that appear in complex nonlinear processes. This paper presents cascade control methodology for the control of a nonlinear exothermic chemical reactor. Continuous Stirred Tank Reactors (CSTR) are the example of complex nonlinear dynamical chemical reactor systems which are used in chemical industries.