基于联立法的乙烯淤浆聚合牌号切换过程动态模拟

Dynamic simulation of grade transition for ethylene slurry polymerization process based on simultaneous approach

以乙烯淤浆聚合流程为研究对象,建立了包含动力学和热力学的动态机理模型,采用有限元正交配置法对控制变量和状态变量同步离散化,实现了全联立动态模拟。热力学物性计算采用Kriging函数估计,可适用于多个工况,最大误差不超过2%。利用Aspen Plus 5个牌号工况的数据,进行了模型稳态验证,并实现了牌号切换动态模拟,计算了平均分子量等质量指标,与Aspen Dynamic曲线吻合较好,为牌号切换的优化奠定了基础。

Dynamic rigorous model including kinetics and thermodynamics is established for the ethylene slurry polymerization plant.Thermodynamic properties are estimated by Kriging technique with the maximum relative error less than 2%.Based on the equation oriented model,control and state variables are synchronously discretized using orthogonal collocation finite elements（OCFE） method to develop simultaneous dynamic simulation for grade transition operations.The results are validated by comparing steady state data of five different grades obtained by Aspen Plus.The dynamic grade transition based on average molecular weight is also presented,which is close to that in Aspen Dynamic.