Simultaneous Process Design and Control for Optimal Grade Transition in a Styrene Polymerization Reactor

ASTEASUAIN, MARIANO; BRANDOLIN, ADRIANA; SARMORIA, CLAUDIA; BANDONI, ALBERTO

Valencia

Congreso; IX Simposio Latinoamericano de Polímeros, VII Congreso Iberoamericano de Polímeros (SLAP 2004); 2004

Comité Organizador

In this work we focus on grade transition operation in a CSTR styrene polymerization reactor. A Mixed ? Integer Dynamic Optimization (MIDO) approach is used to simultaneously design the process and its control system for A « B grade transition sequences. The process design involves reactor size and initiator type selection (discrete decisions), and the two steady state operating points in which each polymer grade is produced (continuous decisions). Simultaneously, feedforward ? feedback controllers are optimally designed to drive the process between steady states. The proposed control superstructure for PI feedback controllers involves the monomer, initiator and coolant flow rates as possible manipulated variables, and the reactor temperature, jacket temperature, number average molecular weight and polymerization rate as possible controlled variables. Optimal pairings between them must be determined (discrete decisions) as well as the controllers tuning parameters and the set points of the controlled variables (continuous decisions). The feedforward controllers? signals consist of time-varying profiles for each manipulated variable, which are calculated by the optimizer.