【摘要】 针对双环管聚丙烯反应过程熔融指数不能在线测量和牌号切换过渡时间长等问题,提出了一种新的牌号切换优化控制策略。首先,分别建立了双环管反应器的瞬时和积累熔融指数预报模型,并进一步提出一种模型系数在线更新方法以实现对牌号切换过程中熔融指数变化的准确跟踪。在此基础上,将牌号切换优化控制归结为一个带状态路径约束的非线性动态优化问题,并由全局正交配置法在线滚动求解。采用实际生产数据的切换控制仿真结果表明:质量预报模型能够准确跟踪牌号切换中熔融指数的变化,牌号切换策略在缩短切换过渡时间的同时保证了装置操作平稳性。更多还原

【Abstract】 The control of polymerization processes during grade transition is very difficult due to the lack of on-line measurements of the polymer properties and the rapidly changing product requirements.A control strategy is given here to achieve optimal transition control for an industrial scale propylene polymerization process with a dual-loop reactor.An inferential model for the polymer melt index(MI),which can trace the product changeovers is derived by incorporating the specific process characteristics with the just-in-time modeling approach.The optimal grade transition control problem is then reformulated as a dynamic optimization problem with state path constraints and is solved using global orthogonal collocation.Simulations confirm the effectiveness of this method.更多还原