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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。
In order to solve the problem that the melt index of double loop polypropylene pipe can not be measured online and the transition time of grade switching is long, a new brand switching optimization control strategy is proposed. First, the instantaneous and cumulative melt index forecasting model of the double loop reactor was established respectively, and a new online updating method of model coefficients was proposed to realize accurate tracking of the change of melt index during the brand switching. On this basis, the title switching optimization control is reduced to a nonlinear dynamic optimization problem with state path constraints, which is solved online by global orthogonal configuration method. The results of the switching control simulation using actual production data show that the quality prediction model can accurately track the change of melt index in the grade switching, and the grade switching strategy can shorten the switching transition time and ensure the plant operation stability.