LNG接收站在役管道二次预冷新工艺的应用

Application of New Technology of Secondary Precooling in Service Pipeline of LNG Terminal

LNG低温管道预冷是LNG接收站试生产的重要环节,管道预冷效果直接影响试生产工作进度及后期接收站生产安全。近几年LNG接收站改扩建项目增多,大多数项目投产前需对在役LNG管道排液后进行二次预冷,与管道首次预冷不同,二次预冷对温度监控、管道位移控制等过程提出更高要求,作业过程复杂、操作难度大。文章以国内某LNG接收站在役槽车外输管道二次预冷为例,采用液氮气化深冷+LNG预冷新工艺,有效解决了距离长、高差大、死角多等特殊管道的预冷难题,并通过现场查勘、数据分析,判断此工艺预冷效果较好,降低了操作难度、控制了安全风险。

The precooling of LNG cryogenic pipeline is an important link in the trial production of LNG terminal,and the precooling effect of pipeline directly affects the progress of trial production and the safety of terminal production in the later stage.In recent years,the number of LNG terminal reconstruction and expansion projects has increased.Most projects need to carry out secondary precooling after liquid discharge of LNG pipeline before putting into operation.Different from the f irst precooling of pipeline,the secondary precooling puts forward higher requirements for temperature monitoring,pipeline displacement control and other processes,and the operation process is complex and diff icult.Taking the secondary precooling of the in-service tank car export pipeline of a domestic LNG terminal as an example,the new process of liquid nitrogen gasif ication cryogenic+LNG precooling is adopted,which effectively solves the precooling problems of special pipelines such as long distance,large height difference and many dead angles.Through f ield investigation and data analysis,it is judged that the precooling effect of this process is good,the operation diff iculty is reduced and the safety risk is controlled.