液化天然气低温储罐吹扫干燥方法及应用探讨

液化天然气(LNG)储罐投产前要进行干燥,干燥不合格可能造成储罐冷量外漏,甚至管道、阀门堵塞。介绍了LNG储罐干燥的2种置换介质和2种吹扫方式及其单独、配合使用的优点和特点。针对合肥燃气10000 m 3双壁LNG储罐实施的分区吹扫干燥,即干空气+氮气为置换介质、持续式吹扫+升压式吹扫相结合的吹扫操作,分析了储罐底部干燥不达标、露点下降不明显的原因,提出并实施了加热氮气和提高氮气流量2条整改措施。监测数据分析表明,整改取得了较为满意的效果,对其他LNG储罐工程的吹扫、预冷有一定的借鉴意义。

Discussion on Purge Drying Method and Application of Liquefied Natural Gas Low Temperature Storage Tank

Liquefied natural gas(LNG)storage tanks should be dried before being put into production.Failure to comply with the requirements may result in leakage of cold storage tanks and even blockage of pipes and valves.Two types of replacement media and two purge methods for drying LNG storage tanks,as well as the advantages and characteristics of their separate and combined use were introduced.For purge operation of partitioned purge and drying for Hefei gas 10000 m 3 double wall LNG storage tank,the purge operation combined with dry air+nitrogen as the replacement medium with continuous purging plus booster purging,the reasons for the unsatisfactory drying of the bottom of the storage tank and the insignificant decrease in dew point were analyzed.Two rectification measures of heating nitrogen and increasing nitrogen flow were proposed and implemented.The analysis of the monitoring data shows that the rectification has achieved satisfactory results,which has certain reference significance for the purge and pre-cooling of other LNG storage tank projects.