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.