Nonlinear Control of Continuous Polymer Reactors via Passivation

A nonlinear passive control to stabilize continuous free-radical solution polymer reactors is presented, with temperature, level and flow measurements. First, the state-feedback problem is addressed with a constructive control framework via passivation by backstepping, yielding the solvability conditions and the attainable closed-loop behavior, or the recovery target for the output-feedback (OF) design. The resulting OF control consists of volume and cascade temperature controllers, a ratio-type monomer controller, and an inventory-type MW controller. The temperature and monomer control components do not need polymerization kinetics and heat transfer models. The MW controller component only requires initiation and transfer rate constants. The proposed control technique has a systematic construction and a simple tuning scheme, and is tested with an industrial size reactor via simulations.