An application of Smith predictor in PID controller for sucrose hydrolysis batch reactor model

Abstract

Temperature control in reaction systems, especially with exothermic reactions, is a challenging

problem in the field of process control. For processes with significant time delay, the control sys-
tems encounter difficulties in maintaining stable operation. Numerous methods have been pro-
posed to address the issues, among which O.J.M Smith suggested a method using a predictor com-
bined with a PID (Proportional – Integral – Derivative) controller. Subsequent studies have been

conducted and demonstrated the significant effectiveness of the Smith's method. In this study, we
applied the Smith's method with a PID controller called PID-Smith controller. PID-Smith controller
was employed to stabilize the temperature of a sucrose hydrolysis reactor and then compared its

performance with that of a conventional PID controller. Experiments carried out with the PID pa-
rameters KP, KI and KD being 80, 0.47 and 1600, respectively, showed that the PID-Smith controller

significantly enhanced the control of system. The experiments were conducted with setpoints of
42oC, 46oC and 44oC, the PID-Smith controller outperforms the PID controller with shorter settling
time, lower overshoot and taking substantially less time to stabilize the system. These result in a
more stable process compared to the PID controller and show Smith's promise in enhancing the
PID control systems.