Risk Study Of Lng Leakage And Vapor Cloud Diffusion In LNG Station

With the rapid development of China’s economy and the introduction and implementation of national energy-saving,low-carbon and environmental protection policies,the state requires different gas enterprises to assume the responsibility of gas storage and peak shaving,the construction of the Liquefied Natural Gas Station has ushered in a Golden Age.How to ensure the safety and reliability of the station has also been highlighted as an important issue.The main storage,transfer and processing medium of LNG field station is LNG,which is easy to evaporate.Once it leaks,the natural gas produced by evaporation is inflammable and explosive,which will do great harm to people,Property and atmospheric environment.According to the need of the project,this paper makes a deep research on the Quantitative Calculation of the vapor cloud diffusion range after LNG leakage according to the current domestic LNG field station related codes.Firstly,the paper identifies the risk factors of LNG storage tanks and process pipelines in LNG field stations,and predicts the types of leakage accidents.Secondly,it analyzes the physical process of LNG leakage,finally,combined with the actual conditions of the project,the calculation and analysis of the LNG pipeline with different working pressure and leakage aperture of 50 mm are carried out,under the meteorological conditions of 2F,5d and 7D respectively,the atmospheric single-tank and full-tank tanks with different discharge capacity of LNG submersible pump,the vacuum insulated tanks and tank groups with different specifications,and the sub-tanks and tank groups with different specifications are installed,numerical simulation and analysis are carried out on the vapor cloud diffusion range of the collecting pool and cofferdam formed after LNG leakage,and some data tables and curves are formed to guide the engineering design.The study shows that the scope of the diffusion isolation zone is related to the working pressure of LNG pipeline,design leakage,the form of LNG storage tank,the area of LNG collecting tank and cofferdam,wind speed and atmospheric stability.The bigger the working pressure is,the bigger the size of collecting tank is,and the bigger the radius of isolating zone is The isolation range of full-tank collecting tank is smaller than that of single-tank collecting tank,and the larger the nozzle diameter of vacuum insulated tank and sub-tank is,the larger the isolation radius of collecting tank is.The leakage of LNG in the cofferdam is related to the capacity of the single largest LNG tank.The larger the tank capacity and the number of tanks,the larger the radius of the isolation zone,under the condition of 2F,the radius of the LNG evaporation-diffusion isolation zone is larger than that of the LNG evaporation-diffusion isolation zone under the conditions of 5D and 7D.The results of this paper provide a reliable theoretical basis for the selection of LNG storage tanks,the location of LNG field stations,the layout of LNG storage tanks,the setting of LNG collection tanks and the piping layout of process zones.