Actuator fault monitoring and fault tolerant control in distillation columns

This work presents, from a practical viewpoint, an investigation of real-time actuator fault detection, propagation and accommodation in distillation columns. Addressing faults in industrial processes, coupled with the growing demand for higher performance, improved safety and reliability necessitates implementation of alternative control strategies in the events of malfunctions in actuators, sensors and or other system components. This work uses multivariate statistical process monitoring based fault detection and diagnosis techniques employing principal components analysis (PCA) and dynamic PCA for prompt and effective faults detection and isolation. The work also investigates effects of disturbances on fault propagation and detection. Alternative control strategy is then implemented to accommodate the actuator faults upon their identification. Specifically, the reflux and vapour boil-up control strategy used for the distillation column during normal operation is switched to one point control of the more valued composition by utilising the remaining healthy actuator. The proposed approach was implemented on a simulated methanol-water separation column to assess its effectiveness.