Automatic Control of Chemical Reactors at Unstable Steady-States

Abstract A tuning technique is developed to control unstable processes of unknown dynamics with conventional PID controllers. The tuning is accomplished by making use of the process knowledge which is constructed by closed-loop operation of the process with a relay controller. Performance and robustness tests are made both on linear systems and on nonlinear chemical processes including a styrene polymerization reactor. Limits and extensions of the tuning technique are carefully examined.