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Abstract

This research work has been carried out to investigate the performances of proportional-integral (PI) and proportional-integral-derivative (PID) controllers tuned with Cohen-Coon, Tyreus-Luyben and Ziegler-Nichols techniques on a reactive distillation process used for the production of a fuel additive. The fuel additive considered was isopropyl alcohol that was obtained from the top section of a prototype reactive distillation column plant developed with the aid of Aspen HYSYS. The model used for the process control was estimated using the data generated from Parametric Utility of the Aspen HYSYS prototype plant and pem command of System Identification Toolbox of MATLAB. Furthermore, the open-loop and the closed-loop Simulink models of the system were developed and simulated appropriately. The results obtained from the open-loop simulations carried out revealed that the system was a stable one because it was able toattain steady-states within the simulation times considered. Also observed from the closed-loop simulations was that the best tuning method for both PI and PID controllers in suppressing large and small errors was Tyreus-Luyben technique. However, in suppressing any error persisting for a long period of time, Ziegler-Nichols method was found to be the best for PI controller while for PID controller, it was Cohen-Coon tuning technique. Further comparing the performance values of the controllers, it was discovered that the PID controllers tuned with the different techniques were better than the PI controllers because the corresponding integral of square error (ISE), integral of the absolute value of the error (IAE) and integral of the time-weighted absolute error (ITAE) values of the PID controllers were found to be less than those of the PI controllers considered for the process.