Research On Leakage Diffusion Analysis And Consequence Evaluation Technology Of LNG Storage Tank Area

Demand for liquefied natural gas(LNG)has increased largely recently in China.As the rapid development of LNG industry,safety consideration is among the first on the main concern.Due to the fact that a great deal of flammable,explosive and low temperature LNG is stored in tank areas,the accident of LNG release from the storage tank will pose a disastrous risk to people,structures and atmospheric environment in proximity to such release.The modeling of LNG vapor dispersion in air and the quantitative analysis of accident consequences can provide scientific guidelines for site of LNG receiving terminals,establishment of emergency response plan,and delimitation of exclusion zones.First of all,in order to choose an appropriate model among a wide range of vapor dispersion models,numerous previous research works were firstly referred to,the methodologies for quantitative assessing the validity of LNG dispersion models were set up.The suitability of Fluent for modeling LNG dispersion was quantitatively evaluated by means of the datasets from the large scale LNG release field trials.According to the theory of fluid mechanics,heat transfer and mass transfer,the process of liquid pool formation and vapor diffusion after LNG leakage is analyzed,to provide a theoretical basis for numerical simulation.The vapor diffusion behavior of LNG leakage under different environmental conditions was studied by Fluent numerical simulation method.Considering the different wind speed,different environment temperature and different cofferdam height,the vapor diffusion of LNG leakage was simulated,and the diffusion law and diffusion range of LNG vapor were obtained.As a result of the accidental effect of LNG leakage and diffusion in the tank area,a domino effect analysis model of LNG tank area accident was established.The damage problem of target equipment was analyzed from two aspects:heat radiation and overpressure.The empirical probability calculation model based on experience is given and the probability of occurrence of the domino scene is calculated.Based on the characteristics of LNG tank area,two types of accidents,such as pool fire and steam cloud explosion,were selected.According to the related consequence calculation model,the seriousness of accident consequences was quantified from both casualties and property losses.