考虑切料过程的乙烯裂解炉炉群调度建模与优化

乙烯裂解炉炉群通常由多台裂解炉并行运行,将烃类原料裂解成小分子烃类化合物。由于随着裂解炉连续运行不可避免地在炉管内壁产生结焦,结焦导致裂解炉运行效率下降,所以需要对裂解炉进行周期性的停炉清焦。对于不同价格参数的多种原料不同清焦费用的多台裂解炉来说,整个乙烯裂解炉炉群系统的循环调度应是求得最优解使得收益最大化。本文对此类裂解炉炉群循环调度问题提出了一个新的混合整数非线性（MINLP）模型,相比较以前的研究该模型能够得到更好的求解多原料多裂解炉的问题,同时解决了裂解过程中切料时机选择的问题。最后,以某乙烯厂为研究实例进行切料时机的优化,优化后裂解炉全周期的运行效益显著提高,为操作人员选择最佳切炉时机提供了理论依据,说明了此模型的有效性。     

Outlet Temperature Correlation and Prediction of Transfer Line Exchanger in an Industrial Steam Ethylene Cracking Process

Predicting the best shutdown time of a steam ethylene cracking furnace in industrial practice remains a challenge due to the complex coking process. As well known, the shutdown time of a furnace is mainly determined by coking condition of the transfer line exchangers （TLE） when naphtha or other heavy hydrocarbon feedstocks are cracked. In practice, it is difficult to measure the coke thickness in TLE through experimental method in the complex industrial situation. However, the outlet temperature of TLE （TLEOT） can indirectly characterize the coking situation in TLE since the coke accumulation in TLE has great influence on TLEOT. Thus, the TLEOT could be a critical factor in deciding when to shut down the furnace to decoke. To predict the TLEOT, a paramewic model was proposed in this work, based on theoretical analysis, mathematic reduction, and parameters estimation. The feasibility of the proposed model was further checked through industrial data and good agreements between model prediction and industrial data with maximum deviation 2% were observed.     

兼顾负荷变化的裂解炉炉群调度建模与优化

裂解炉是乙烯生产的核心装置,工业生产乙烯通常采用多台裂解炉并行运行,将烃类原料裂解成乙烯等小分子烃类化合物。在裂解炉的运行过程中会不可避免的在炉管内壁产生结焦,从而导致乙烯产率的下降,为此需要对裂解炉进行定期的停炉清焦。当多台裂解炉同时处理多种不同类型的原料,而且在操作成本和产品收率都在不断变化的情况下,对裂解炉炉群进行优化调度以取得生产利润的最大化具有重要意义。针对乙烯裂解炉炉群调度建模与优化问题,提出了一个同时考虑原料及其进料量负荷的新的调度模型,克服了之前炉群调度仅针对原料选择、裂解炉负荷依赖人工设定的不足,优化后使裂解炉炉群的生产效益得到提高,为工厂合理地安排生产提供了理论依据。