Multivariable nonlinear control of a continuous polymerization reactor: An experimental study

This experimental work concerns the multivariable nonlinear control of a continuous stirred‐tank polymerization reactor. The globally linearizing control (GLC) method is implemented to control conversion and temperature in the reactor in which the solution polymerization of methyl methacrylate takes place. Control of conversion and temperature is achieved by manipulating the flow rate of an inlet initiator stream and two coordinated heat input variables. Conversion is inferred from on‐line measurements of density and temperature. A reduced‐order state observer is utilized to estimate the concentrations of monomer, initiator and solvent in the reactor. The concentration estimates are used in the control law. This study demonstrates the considerable computational efficiency of the nonlinear controller, which is implemented on a microcomputer. The experimental results show the excellent performance of the controller in the presence of active state and input constraints. A systematic approach is also given for the synthesis of output feedback controllers within the GLC framework for processes with secondary outputs.