面向在线分析应用的乙烯精馏装置复杂机理模型开发

传统的软仪表模型一般采用简化的机理模型或基于输入输出参数的关联模型，精度一般偏差较大，应用时需要进行定期校验和模型参数修正，虽然能在一定程度上满足控制要求，但是无法满足装置优化计算的需要。从满足在线分析应用需求的角度出发，开发了乙烯精馏塔的复杂机理模型，相平衡方程中建立了空间分布的塔板效率模型，考虑了塔板结构等多种因素的影响，将实际塔板与理论塔板进行了逐级关联，以非立方型多参数BWRS状态方程作为气-液平衡计算模型，完整地描述塔内气-液平衡关系和热力学状态。并以具有代表性的乙烯精馏塔作为模型验证对象，在某工况下将模型计算数据与Aspen Plus及实际测定值进行了对比，结果表明，所建立的严格稳态机理模型具有较高的准确性，为模型的在线分析应用奠定了基础。

Complicated Mechanism Model Development of Ethylene Distillation Column for Online Analysis Application

In some conventional soft sensors the simplified mechanism model or the association model based on input-output parameters was used,so there were some severe errors which need to be periodic verified and the model parameters need to be modified in practical application.Although they can be satisfied to requirement control in some degree,it is hardly to meet the need of optimization calculation for equipment.A rigorous steady mechanism model was built for a distillation column according to the standpoint of online analysis application.A spatial distribution tray efficiency model was adopted in phase balance equations with considering the influence of many factors like tray structure etc,so practical tray numbers and theoretical tray numbers of one tower can be associated stage by stage.The calculation model of gas-liquid equilibrium used the non cubic version of BWRS state equation,which can express the gas-liquid phase equilibrium relationship and thermodynamic state wholly and clearly.At last,an ethylene rectifier was chosen as a representative model verification object.Results of model calculation were compared with the results from lab data and calculation of Aspen Plus under an operating condition,which showed that the rigorous steady mechanism model developed for ethylene distillation column was of accurate and will lay the foundation for the industrial online analysis application.