APPLICATION OF ADVANCED PROCESS CONTROL TECHNIQUES TO CONTINUOUS EMULSION POLYMERIZATION

Several aspects of continuous emulsion polymerization in a series of stirred tank reactors make this operation particularly well suited for application of advanced process control theory. For many emulsion polymerized monomers, a steady state in conversion or number of polymer particles is never reached in a continuous system because of the phenomenon of sporadic polymer particle nucleation. This aspect of the operation requires that advanced control techniques be utilized. Additionally, in commercial systems effective deadtime in control loops in excess of an hour are experienced, also requiring special control strategies.;The control techniques developed in this work were evaluated by simulation of the vinyl acetate system, for which the mechanistic model had been previously tested. In addition, these control strategies were implemented successfully on an existing commercial facility to provide improved control of the process.;In this thesis, a mechanistic model of continuous emulsion polymerization in a train of tank reactors has been developed. This model has been incorporated into an analytical predictor algorithm which successfully compensates for process deadtime in conversion control of front-end reactors. Regulatory and servo control of conversion from the first reactor were significantly improved in both simulations of the vinyl acetate system and in an implemented commercial system. Reactor design modifications were suggested by experimental and simulation studies which allowed the controlled operation of a train of reactors using a "soap-starved" feed. Additionally, a control system was developed for conversion control of downstream reactors using z-transform design methods. On-line model parameter estimation techniques were incorporated to achieve adaptive control. Also, a decoupler network was defined to eliminate interaction between conversion and reaction temperature control loops.