Bifurcation control and eigenstructure assignment in continuous solution polymerization of vinyl acetate

The major difficulty in achieving good performance of industrial polymerization reactors lies in the lack of understanding of their nonlinear dynamics and the lack of well-developed techniques for the control of nonlinear processes, which are usually accompanied with bifurcation phenomenon. This work aims at investigating the nonlinear behavior of the parameterized nonlinear system of vinyl acetate polymerization and further modifying the bifurcation characteristics of this process via a washout filter-aid controller, with all the original steady state equilibria preserved. Advantages and possible extensions of the proposed methodology are discussed to provide scientific guide for further controller design and operation improvement.

This paper discussed the nonlinear behavior and oscillatory phenomenon of the parameterized nonlinear system of continuous solution polymerization of vinyl acetate (VA). Limit points such as Hopf bifurcation point corresponding to periodic solutions are obtained. A new procedure of implementing bifurcation control is further applied to modify the bifurcation characteristics of VA polymerization process via a washout filter-aid controller. The unstable solution branch, where the targeted operating point was located, has been rendered to stable branch by means of eigenstructure assignment. All the practically preferable operating points and the shape of the original equilibrium of the open-loop system are preserved.Figure optionsDownload as PowerPoint slide