Receding horizon control for grade transition of large-scale polypropylene production plants

Based on the receding horizon optimized control strategy, an optimal control method of grade transition was presented for the large-scale bi-tubular polypropylene production process. Firstly, with mechanism analysis, the Hammerstein model was used to represent the dynamics of resin quality in the grade transition process. Secondly, by receding optimization of the performance index of grade transition, the controlled variables in all reactors were computed in each sampling time, such as polymerization temperature, ratio of hydrogen to propylene and ratio of ethylene to propylene. Moreover, introducing the two-tie control structure and design of state estimator yielded receding optimized closed-loop control of polypropylene grade transition and predicted the dynamic trajectories of the polymer quality in all bi-tubular reactors. Finally, an example of simulation of multi-grade transition control was used to illustrate the effectiveness of the result in this paper. © All Rights Reserved.