LNG储罐与管道的冷却方法研究

Study on Cooling Method of LNG Tank and Pipeline

LNG储罐与管道的冷却是LNG接收站投入运营前最重要的环节之一,建立LNG储罐冷却控制模型,对现场储罐温降数据进行监控和分析以指导储罐冷却操作,使LNG储罐冷却速率控制在合理范围内,可实现储罐的平稳冷却。针对不同的冷源总结LNG管道冷却操作方法,重点研究液氮冷却LNG接收站卸料管道温降规律,提出采用“间歇式”液氮预冷方法代替BOG预冷方法对卸料管道进行预冷,可以改变管道内部气体的流通速度,使管道上下温差控制在设计值以内以达到均匀混合的目的。此方法可以减少BOG的排放,节省调试时间与费用。LNG储罐冷却控制模型与LNG管道液氮冷却方法在已投产项目调试中均得到了良好实践和应用,可供LNG行业操作人员参考。

The cooling of LNG storage tank and pipeline is one of the most important links before the LNG terminal is put into operation.The cooling control model of LNG storage tank is established to monitor and analyze the temperature drop data of on-site storage tank to guide the cooling operation of storage tank,so as to control the cooling rate of LNG storage tank within a reasonable range and realize the stable cooling of storage tank.In view of different cooling sources,this paper summarizes the cooling operation methods of LNG pipeline,focuses on the research of the temperature drop law of unloading pipeline in LNG terminal,and puts forward the“intermittent”Liquid Nitrogen Precooling method instead of BOG precooling method to precool the unloading pipeline,which can change the velocity of gas in the pipeline,and control the temperature difference between the upper and lower parts of the pipeline within the design value to achieve uniform mixing.This method can reduce the emission of BOG,save the debugging time and cost.The cooling control model of LNG tank and the liquid nitrogen cooling method of LNG pipeline have been well practiced and applied in the commissioning of projects in operation,which can be used as reference for the operators in the LNG industry.