LNG接收站液氮系统改造及应用

Modification and application of liquid nitrogen system in LNG terminal

某液化天然气(Liquefied Natural Gas, LNG)接收站液氮采用槽车方式,由空分厂装车后外运至接收站,这种运输方式存在耗费时间长、作业窗口时间短、易泄漏、操作不规范、抵达时效影响较多等问题。通过调研及分析液氮供应影响因素,在比选多种解决方案后确定新建液氮直供系统的解决方案。结果表明:新建液氮直供系统大幅降低液氮充装时间,由原来48 h缩减为8 h;延长作业窗口时间12 h,实现全天可接卸液氮;主要工作由集散控制系统操作员完成,全年可节约工时160 h;全年可节省液氮费用20万元(含槽车运输费及中间费用)。液氮直供系统的新建与应用为全国首例,可为国内接收站氮气供应提供新的工艺流程及可复制模板,极大降低生产成本,规避氮气供应风险。

A Liquefied Natural Gas(LNG)terminal uses tank trucks for transporting liquid nitrogen from the air separation plant,a method fraught with issues such as lengthy time consumption,short operating hours,susceptibility to leaks,non-standardized operations,and various factors compromising timely delivery.In response to the above,through investigation and analysis of the factors affecting the liquid nitrogen supply,a new liquid nitrogen direct supply system was chosen as the optimal solution.The results show that:the system significantly accelerates the liquid nitrogen filling process,reducing the response time from 48 hours to 8 hours.The short operating hours are extended by 12 hours,enabling around-the-clock liquid nitrogen handling.The main task is done by Distributed Control System(DCS)operators,saving 160 man-hours over one year.It can save 200000 yuan of liquid nitrogen cost over one year(including the intermediary cost and transportation cost of tank trucks).This pioneering modification and application of the new liquid nitrogen supply system sets a precedent nationwide.It offers a new process flow scheme and replicable template for nitrogen supply at domestic LNG terminals,substantially cutting operating costs and mitigating nitrogen supply risks.