Reduction of Transients between Steady States in the Continuous Production of High-Impact Polystyrene

LUCIANI, C. V.; ESTENOZ, D. A.; MEIRA, G. R.; OLIVA, H. M.

INDUSTRIAL & ENGINEERING CHEMICAL RESEARCH

Año: 2005 vol. 44 p. 8354 - 8367

0888-5885

This work theoretically investigates the reduction of transients during changes of grade in a continuous plant for the production of high-impact polystyrene (HIPS). A mathematical model was developed that predicts the global molecular structure and the melt flow index (MFI). The switching times of the off-specs accumulation period were selected on the basis of the admissible MFI ranges. Smoother transitions and reduced off-specs can be produced through a simple readjustment (with respect to the original plant policy) of the two intermediate chain transfer agent (CTA) loads into the batch dissolver. For the transitions that involve a large difference in their MFIs, the off-specs can be reduced by 60%, with respect to the original plant policy, by including a transient feed of CTA into an intermediate stirred reactor.