On-line optimization of free radical bulk polymerization reactors in the presence of equipment failure

An on-line optimizing control scheme has been developed for bulk polymeriza tion of free radical systems. The effects of random errors, as well as one kind of a major disturbance (heating system failure), have been studied. A model-based, inferential state estimation scheme was incorporated to estima te, on-line, the parameters of the model land thereby, the monomer conversi on and molecular weight of the polymer) using experimental data on temperat ure and viscosity. A sequential quadratic programming technique was used fo r this purpose. A major disturbance, such as heating system failure, leads to a deteriorated final product unless an on-line optimal temperature traje ctory (history) is recomputed and implemented on the reactor. Genetic algor ithm was used for this purpose. It has been found that, if the "sensing" of the major temperature deviation from the optimal value and rectification o f the heating system is achieved well in advance of the onset of the Tromms droff effect, use of a reoptimized temperature history is sufficient to pro duce the desired product without significantly altering reaction time. Howe ver, if such a disturbance occurs late, a single-shot intermediate addition of an optimal amount of initiator needs to be used in addition to changing the temperature history to produce polymers having the desired properties in the minimum reaction time. Other types of failures can similarly be hand led using the methodology developed. (C) 1999 John Wiley & Sons, Inc.