Uncertainty Analysis And Numerical Simulation For LNG Tank Leakage And Dispersion

Liquefied natural gas(LNG)is the cleanest burning fossil fuel,obtained from natural gas.The tanks store large quantities of LNG,and once the tanks ruputure,the consequences could be disastrous,especially the chain accident.So it is important for the effective prediction of the LNG leakage and diffusion for the safety management and accident control.This paper systematically analyzed the risk of tank leakage and the consequences by simulation,and discussed the safety management of tank management,and provided theoretical guidance and technical support for the management.The specific research contents were as follows:1.Uncertainty analysis of leakage probability of LNG tankLNG tank is an important equipment for liquefied natural gas storage and transportation.Initially,a historical survey of accidents at LNG facilities,along with a detailed study of LNG carriers and LNG onshore and offshore terminals,was presented to support hazard identification based on Master Logic Diagram.Then a probabilistic potential hazard assessment was performed;moreover,leakage probability of LNG tank was estimated based on fuzzy fault tree.The LNG storage equipment failure analysis,risk factors and safety problems and consequences were analyzed.Analyze systematically the source of the uncertainty problem,collect the probability of the occurrence of the basic event,extract and select the data from the existing database,and make the uncertainty analysis of the leakage probability of the LNG storage tank.Lastly,calculate the probability of occurrence,and combine with importance analysis in order to identify the key factors on the leakage of the tank.2.Simulation analysis of wind field and disperison in storage tank areaThe 3D model of LNG storage tank was established by image height extraction method.CFD numerical model of LNG had a better prediction accuracy for LNG disperison,and the suitability and feasibility of the model tool were studied.Collecting the meteorological data of the storage tank area,and the wind field was simulated by Realizable k-? model.The Fluent multiphase flow model and the species transport model were selected to simulate the diffusion behavior after LNG leakage.3.Analysis of safety and prevention of leakage for tank areaThe impact factors on leakage in LNG tank area were analyzed entirely,including wind speed,wind direction and so on.With the increase of wind speed,the greater the inhibition of low temperature steam cloud,and the formation of dangerous areas gradually reduced.Compared with the downwind direction,the vertical wind direction and the upwind direction led to the larger area of the gas cloud damage area,because of the strength of mixing of the gas cloud and the air.The upwind direction was the worst for tank satety.Considering the chain effect of leakage accident based on event chains,the individual risk distribution under different conditions was analyzed.Combined with the tank leakage situation,the recommendations about engineering safety and emergency management were summed up.Draw lessons from the pipeline integrity management concept and build the tank management elements Tableand management cycle programs and processes.