Risk Analysis And Accident Consequence Simulation Of LNG Ship Leakage

In recent years,China’s demand for LNG continues to grow steadily.Waterborne shipping is one of the main ways to import LNG,and there may be leakage,diffusion,fire and explosion accidents and other risks in the process of transportation.LNG ship near port leakage occurs,may spread in the ground surface and stations,leakage after low temperature LNG gasification flammable gas cloud formation,when it is heated to burn the limit,meet a source would trigger a flash fire,jet fire,pool fire or explosion accident,and nearly port personnel,equipment,facilities,easy to cause secondary disasters and accidents.Therefore,LNG shipping safety has always been a hot issue in the field of energy and safety.In this paper,the meteorological environment of Dalian and "China Ocean Shipping Company(COSCO)603" LNG ship are selected as the research objects,and a simulation model is established to study the leakage fire accident near the port of LNG ship,and to analyze the concentration diffusion law of LNG on the water surface and the ground and the damage range of fire and explosion accident.On the basis of this analysis and prediction of single fire source and multiple fire source leakage fire consequences of LNG ship severity and disaster impact range.Firstly,the leakage and diffusion of LNG on the ground and open water with occasionally large obstacles are primarily analyzed,and the influence laws of leakage aperture,wind speed,atmospheric temperature,atmospheric stability and other factors on LNG leakage concentration,downwind distance and cloud width are mainly discussed.Studies show that the larger the leak aperture,the lower the wind speed,the more stable the atmosphere,the higher the temperature,the larger the diffusion range of LNG,and the more serious the accident consequences.Secondly,the risk assessment of LNG shipping fire and explosion accident consequence based on PHAST software is carried out.Based on the leakage and diffusion analysis results,the ground and surface pool fire,flash fire,jet fire and explosion scenarios were studied,and the geometrical characterization parameters such as radiation intensity level and downwind distance of diffusion were obtained.At the same time,the characteristic parameters of each influencing factor under the most dangerous conditions are discussed.The research results can provide a scientific basis for setting the initial condition parameters of fire scenario simulation.Thirdly,the combustion characteristics and empirical models of single pool fire and multiple pool fire are discussed to provide theoretical basis and comparative verification for parameter setting.At the same time,the simulation of LNG single pool fire and multiple pool fire based on PyroSim software was carried out,and the damage degree of various combustion conditions on the surface and the ground was compared and analyzed.In the form of flame height,temperature,thermal radiation flux and other combustion characteristics,the change rules and damage radius of single pool fire and multiple pool fire on water surface and ground were compared,and the calculation results of empirical formula were compared to determine the fire spacing and safety distance.Finally,based on the results of risk analysis and numerical simulation,the prevention and response measures for LNG ship near port leakage fire accidents are proposed from four aspects of strengthening safety control,deepening safety cognition,refining safety measures and optimizing safety layout.The research results can provide a scientific basis for the analysis and control of LNG shipping leakage fire accident,and provide reference for the safety prevention and emergency management of LNG shipping in China.