Catalyst control using a real-time process model

Controlling the reaction and the product quality in a large Polyester Intermediates plant has been an intractable problem for many years. Handling difficulties and the hazardous nature of the process has made it impossible to get real time measures of the product or of the dissolved catalyst. Model Predictive Control was implemented, but failed to give reliable control. Now a simplified Process Model is used with just the right level of detail to estimate the catalyst concentrations around the plant in continuous real-time. Data quality handling logic keeps the model sufficiently robust. The model is described and how it is implemented in the closed loop control schemes. The whole process has highlighted major lessons in the pragmatic approach to implementing Advanced Process Control in the process industry.