Applications of nonlinear observers and control: Improving productivity and control of free radical solution copolymerization

A nonlinear state observer that uses the rate of heat generation due to chemical reaction for the real-time evaluation of key parameters during free radical solution copolymerization is presented. These parameters include the cumulative and instantaneous copolymer compositions, the overall and individual monomer conversions, and the overall termination rate constant associated with the reaction. The information thus obtained is used to control the cumulative copolymer composition and to maintain the productivity of a semibatch reactor for the solution copolymerization of butyl acrylate (BuA) and vinyl acetate (VAc) in ethyl acetate (EAc) at its highest possible level. Both the state and parameter estimation of this observer were then used for the nonlinear control of copolymer composition and optimal reactor productivity.