Abstract:

Several modification schemes were proposed for increasing the production of mixed xylene in the already operating fuel type reforming unit, and process simulation and comparative research were conducted on them. The reboiler load, steam and fuel consumption among the two-column thermal combined process, dividing wall column(DWC) process, and DWC + two-column thermal combined process were compared emphatically. By comparison, it is found that the comprehensive energy consumption is 53.1%, 22.7% and 71.2% lower than that of the basic scheme, respectively. The best energy saving effect is achieved by the DWC + two tower combined process which integrates the advantages of two-column thermal combined technology and DWC technology. The energy-saving effect of DWC are verified by two DWC application cases with more than 30% lower reboiler load than the sum of the reboiler load of the corresponding conventional two columns. The energy consumption of two-column thermal combined process with xylene column operated under a high pressure and the tower top stream used as reboiler heat source for deheptane tower is 25% lower than that of corresponding DWC, so the DWC is not recommended for similar cases. The research results can be used as reference for similar units which are under a revamping plan for reducing oil production and increasing chemical production.

Key words: CCR unit, xylene, product separation, dividing wall column, two-column thermal combined process, reboiler load, thermal integration, energy consumption

摘要：

针对已运行的燃料型重整装置进行增产混合二甲苯改造，提出了几种改造方案并对其进行了流程模拟和比较研究。着重对比了“两塔热联合流程”“分壁塔流程”“分壁塔+两塔热联合流程”3个方案的重沸器热负荷、蒸汽及燃料消耗，对比发现3个方案的综合能耗分别较基础方案低53.1%、22.7%、71.2%。集成了两塔热联合技术、分壁塔技术二者优点的“分壁塔+两塔热联合流程”方案节能效果最佳。分析了分壁塔工业应用的两个案例，其重沸器负荷均较常规两塔重沸器负荷之和降低30%以上，体现了分壁塔的节能效果。二甲苯塔加压操作，塔顶物料用作脱C7塔重沸器热源的两塔热联合流程相较于分壁塔节能25%,类似工况不建议采用分壁塔。研究结论可为同类装置实施“减油增化”改造提供借鉴。

关键词: 连续重整装置, 二甲苯, 产品分离, 分壁塔, 两塔热联合, 重沸器热负荷, 热集成, 能耗