芳烃联合装置节能改造方案探讨

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%。

Discussion on energy-saving revamping scheme for an aromatics complex

The revamping schemes of an aromatics complex to reduce energy consumption and expand capacity 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 maximized utilization of existing equipment like disproportionation reactor,charge heaters,recycle hydrogen compressor,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 C8 is applied for naphthene isomerization unit.After revamping,the energy consumption of the unit is greatly reduced.The energy consumption of disproportionation 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.