Nonlinear model predictive control of end-use properties in batch reactors under uncertainty

There are significant incentives in controlling the end-use properties in batch reactors to reduce the variability in the final product quality specifications. Here we define an approach for controlling the properties within a desired target region, instead of a set point, with an economic objective and with consideration of the model uncertainty. The approach to handling process-model mismatch is based on determining the uncertainty in the predicted final values of the properties, in the form of elliptical confidence regions. The controller then ensures that the complete confidence region is within the target set. A semi-infinite programming problem is solved to find the input values for the rest of the batch, utilizing techniques that reduce the complexity of the problem. An emulsion polymerization process for styrene is chosen as a case study and the methods developed here are demonstrated on this challenging example process.