Grade transition strategy for polymerization process based on dynamic optimization and feedback control

In this work, an optimal grade transition strategy based on the combination of regulatory control and dynamic optimization for a continuous multi-grades polymerization process was proposed. The optimal grade transition of a continuous stirred tank reactor (CSTR) to minimize consumption of raw materials during transition operation was discussed, and the optimal trajectories of the reaction conditions and polymer quality are calculated using iterative dynamic programming. The path constraints on the reaction temperature change was introduced to alleviate the fluctuations during grade transition, and to obtain an easily tracked optimal trajectory as well. Through case study of a free radical styrene polymerization in a pilot CSTR, it is shown that the grade transition strategy can shorten the transition time and minimize the material consumption, and overcome the disturbance of feed temperature as well. ©, 2015, Chemical Industry Press. All right reserved.