NMPC-based control scheme for a semi-batch reactor under parameter uncertainty
Alex Kummer, Lajos Nagy, Tamás Varga
Abstract
Exothermic reactions are often performed in SBR because the generated reaction heat can be more easily kept under control in such construction. However, an unsuitable control system can lead to the development of thermal runaway, which may cause lethal damage. NMPC with implemented thermal runaway criteria is a promising tool to operate SBRs. However, engineers should always consider plant-model mismatch because uncertain predictions can cause undesirable scenarios. A novel control framework is proposed to operate SBRs and consists of NMPC with the implemented runaway criterion, extended Kalman filter and parameter identification algorithm. Both Multi-Stage NMPC and NMPC with the worst-case scenario are investigated and tested in terms of ability to handle parameter uncertainty. The former is 38 times slower than the latter with no noticeable increase in reactor performance. NMPC initialized based on the worst-case scenario with updating uncertain kinetic parameters results in a promising control structure for SBRs.