芳烃联合装置节能改造方案探讨

Discussion on energy-saving revamping scheme for an aromatics complex

阐述了对某芳烃联合装置进行的以节能为主、扩能为辅的改造方案。对装置改造内容、规模选择、催化剂选择、热量集成方案、优化流程设计等进行了讨论。提出了可行的节能方案:装置改造尽量利用原有设备,如歧化和异构化反应器、反应炉、循环压缩机、吸附塔和转阀等关键设备;采用新型催化剂和新型吸附剂;充分挖掘装置潜力;合理配置热量集成方案,加强低温热利用,抽余液塔和抽出液塔加压操作,塔顶低温热用以发生低压蒸汽,脱庚烷塔塔顶低温热用以发生低压蒸汽;优化流程设计,歧化异构化反应部分采用热高分流程设计,异构化部分采用C8环烷烃部分循环流程。改造后装置能耗大幅降低,岐化、吸附分离、异构化和二甲苯精馏等装置能耗为506.90 GJ/h,折合12.16 GJ/t PX或10.91 GJ/t(PX+OX),仅为改造前能耗27.50 GJ/t PX的44%。

The revamping schemes of an aromatics complex to reduce energy consumption and expand ca- pacity are described. The revamping work, capacity selection, catalyst selection, heat integration, process flow scheme optimization are discussed. A practical energy-saving revamping plan is developed, such as maxi- mized utilization of existing equipment like disproportionation reactor, charge heaters, recycle hydrogen com- pressor, absorber, and rotary valve, etc, application of new catalyst and absorbent, fully tapping the potential of existing unit and optimized heat integration to utilize the low-temperature heat. Low-pressure steam can be generated by using the low-temperature heat of raffinate column and extract column overheads when they are operated at a higher pressure. And low-temperature heat of deheptanizer overhead is utilized to generate low- pressure steam. The process flow design is optimized, and hot HP separator is installed for disproportionation and isomerization＇ s reaction sections. Partial recycle flow of Cs is applied for naphthene isomerization unit. After revamping, the energy consumption of the unit is greatly reduced. The energy consumption of dispropor- tionation section, adsorption separation section, isomerization section and xylene fractionation section, etc is 506.90 GJ/h which is an equivalent of 12.16 GJ/t PX or 10.91 GJ/t （ PX ＋ OX）. It is only 44% of that （27.50 GJ/t Px. ） before the revamping.