Safe-Parking of a Styrene Polymerization Process

This work considers the problem of control and fault-handling in living nitroxide-mediated radical polymerization (NMRP) of styrene subject to input constraints. First, a Lyapunov based model predictive controller is designed that allows for an explicit computation of the stability region. Next, a fault in one of the monomer feed streams is considered due to which operation of the reactor at the nominal operating point is no longer possible. It is shown that trying to continue nominal operation using the remaining functioning actuator drives the process to a point resulting in significantly off-spec product. A safe-parking framework is utilized to choose an operating point during fault rectification so that the styrene produced during fault rectification complies with the desired product specifications, and smooth resumption of nominal operation upon fault rectification is achieved.