Multi-rate nonlinear state estimation in a polymerization reactor

A new multi-rate nonlinear observer design method is presented. It can use a nonlinear process model in the estimator design directly, without any linear approximation. The multi-rate nonlinear state observer is easy to design and implement and is computationally efficient. The implementation and performance of the observer design method are shown by a polymerization reactor in which free-radical solution polymerization of styrene takes place. The initiator concentration and the three leading moments of the molecular weight distribution (MWD) of the polymer product are estimated continuously from: 1) the frequent measurements of the reactor temperature, jacket temperature and the reacting-mixture density; and 2) the infrequent and delayed measurements of the leading moments of the MWD