乙烯精馏塔软仪表与先进控制工程实践

Process Observer and Advanced Process Control of Ethylene Rectifier

以乙烯装置乙烯精馏塔现有的常规控制为基础 ,提出乙烯精馏塔先进控制策略 ,通过化工机理分析 ,建立用于预测控制的动态机理数学模型 ,并线性化简化为状态空间模型和质量控制软仪表。塔顶侧线乙烯产品纯度和塔底馏出物乙烯浓度两个机理软仪表工业实施效果良好 ,其中乙烯产品纯度软仪表采用在线色谱分析数据实时校正。预测控制器控制塔顶产品纯度 (给定点控制 )和塔底循环乙烷浓度 (约束控制 ) ,操纵变量为塔顶侧线采出量和塔底再沸器加热蒸汽量。仿真实验表明预测控制器的有效性。状态反馈预测控制器用于工业装置 ,效果良好 ,可以实现塔顶侧线产品的“卡边控制”

Based on the regulatory control in existence,an advanced process control strategy on the ethylene rectifier of an ethylene complex was proposed that the specification of the ethylene product drawn at the top of the rectifier and the ethylene concentration at the bottom are controlled by the flowrates of the product at the top and the steam form the reboiler at the bottom.With the process analysis,a mechanism model was formulated,and a state space model was linearized for model predictive control (MPC) and process observers.Two process observers were built and applied commercially for the ethylene concentration of the product from the top and the cycle ethane from the bottom.The process oberver for the top is revised with the online gas chromatogram.The simulation and commercial application of MPC of the rectifier with the model proposed in the paper showed the high performance of the advanced process controller with the feedback of state variables,i.e.the temperature of plates in the rectifier.