Multi-rate nonlinear state estimation in a polymerization reactor: a real-time study

Real-time implementation of a robust multi-rate state estimator on a continuous stirred tank, free-radical, styrene polymerization reactor is presented. The estimator was designed on the basis of a first-principles model of the process. The estimator had "integral action", which permitted robust estimation of polymer weight-average and number-average molecular weights, and monomer concentration. These were estimated from (a) on-line frequent measurements of the reactor temperature, and (b) off-line, infrequent and delayed measurements of polymer weight-average and number-average molecular weights and monomer concentration. Infrequent measurements of monomer concentration were obtained by gas chromatography and gravimetry, and those of weight-average and number-average molecular weights by gel permeation chromatography. The real-time study presented was carried out in DuPont\´s Marshall Laboratory, Philadelphia, PA.