连续聚合过程中多牌号产品过渡的生产调度最优化

应用连续聚合过程中牌号切换的最优化模型，提出了以目标函数值为判别依据的多牌号切换的最优化调度策赂。对多牌号树脂的生产系统进行了调度最优化的仿真研究，并在安全生产的前提下，以动态规划的方法考察了6个聚乙烯树脂牌号的生产调度，计算了树脂牌号的最优生产序列以及相应的过渡料数量和过渡时间，并分析了计算结果的合理性。

Optimal Multi-Product Transition Operation in Continuous Polymerization Process

On the basis of optimal grade transition model in continuous polymerization process presented in the previous papers1], an optimal strategy of multi-product transition was discussed which is named as grade transition integration. After considering the restriction of technology, such as the type of catalyst and the priority of special resin grade, optimal strategy of multi-product transition was determined by a dynamic programming method in terms of the value of objective function J(u). The values of J(u) was compared with each other. The product grade with the smaller value of J(u) is produced first, then do the next consequently. Doing so, the quantities of off-specification product and the time of each grade transition can be minimized. Meanwhile the optimal manipulated variable profile for each transition are gained, such as polymerization temperature, the ratio of hydrogen to ethylene, the ratio of co-monomer to ethylene, catalyst feed rate, and bed level. The dynamic programming method reduces much more time of calculation during the optimization of schedule. An optimal operation strategy of six resin grades was scheduled as an example, which can clarify the optimal strategy of multi-product transition in detail. During each transition process, it is shown that polymerization temperature, hydrogen and co-monomer are sensitive to the quality of resin and it is always recommended that catalyst feed rate and bed level decrease in order to reduce the grade transition time and the quantity of off-specification product. At the same time, the quantity of off-specification product and the time of grade transition corresponding to each grade transition can be calculated by use of the optimal grade transition model. It is shown that the commercial process can be enormously beneficial from the optimal strategy. It is also shown that the integration of grade transition can be easily applied to the production schedule of homo-polymers and co-polymers simultaneously.