甲醇制烯烃(MTO)单元副产水,反应产物中水分占比达56%,单套装置水系统循环量高达2 400万t/a。因水系统存在汽提系统操作条件设置不合理和系统已有设备不匹配等问题,容易造成净化水COD值长期偏高、急冷水外排量长期偏高,使得甲醇制烯烃装置外排COD超标,对污水处理造成很大的生产和环保压力。以某MTO装置为例,介绍了MTO装置的水系统工艺流程,对实际运行过程中汽提系统操作条件的优化和系统已有设备的改进做出分析,并提出几种解决方案,以便更好地保障甲醇制烯烃工业装置水系统的安全、平稳和长周期运行。

Methanol to olefin (MTO) unit produces water as a by-product,and the water in the reaction products accounts for 56%.The circulation of water in a single unit is as high as 24 million tons/year.The water system has problems such as unreasonable operating conditions for the stripping system and mismatch of existing equipment in the system,which easily results in high COD value of the purified water and high discharge of the quench water for a long period of time,making the discharge of COD from the MTO unit exceed the standard and causing great pressure on production and environmental protection for wastewater treatment.Taking an MTO unit as an example,this paper introduces the water system process flow of MTO unit,analyzes the optimization of the operating conditions of the stripping system in the actual operation process and the improvement of the existing equipment of the system,and puts forward several solutions to better ensure the safe,stable and long-term operation of the water system in the MTO industrial unit.