Nonlinear MPC for grade transitions in an industrial LDPE tubular reactor

A detailed physical model has been developed for an industrial 350 kt/year low-density polyethylene tubular reactor and implemented in a proprietary non-linear Model Predictive Control framework to control product quality during grade transitions. The controller is now at the end of the commissioning phase and is regularly used during transitions. Improved transition control reduces the amount of off-spec product, which improves the profit of the plant as well as the consistency during transitions compared to the manual transition control scheme used previously.