Numerical Simulation For LNG Release&Dispersion And Hazard Evaluation Of LNG Storage Tank

Liquefied natural gas (LNG) is a new type of clean energy which is widely used in these years, and with the prompt growth of liquefied natural gas trades, the technique of LNG storage and transportation has developed a lot, and a large number of LNG projects have been set up. LNG tank is an important part of the LNG project and has a high level of danger because of the cryogenic, flammable and explosive physical property of LNG that is stored in the tank. The accident of LNG release from the storage tank will easily cause fire and explosion and pose a disastrous risk to people and structures. This article developed a research on the risk analysis of LNG tank and obtained the conclusions below.(1) As cryogenic valve is a part with a high level of danger, this article started the risk study with the finite element analysis on the cryogenic valve and found that the thermal stress concentrate at the connection position caused by the uneven temperature distribution is much more obvious than that in static stress analysis by about30times, and the cumulative fatigue usage equals to0.1178after1000cycles of cyclic loads.(2) The result of numerical simulation shows the cloud’s morphology characteristics of sedimentation, accumulation and back-flow during the releasing and diffusing. It also indicated that the furthest distance of different CH4mole fraction and the explosion area are changing regularly by the time.(3) The comparison of the influence of different factors (size of dam, wind speed, value of the tank and type of tank) indicates the effects to the release and diffusion. Diffusion range increases when the size of dam increasing, decreases when the wind speed increasing and increases when the value of rank increasing. The furthest distance of different CH4mole fraction and the explosion area changes regularly with the variety of the size of dam and wind speed.(4) In the end, this article revised the method by adding correction factor related to the size of dam and wind speed based on the simulated effects. It shows that the revised method is more applicable and accurate in the hazard evaluation of LNG tank.