Analysis of the influential factors on the risks of LNG storage tank leakage
摘要
The paper is engaged in an analysis of the influential factors on the risks of LNG storage tank leakage. In such a case,when LNG(liquefied natural gas) leaks on the ground,it will be followed by the heat transfer between the LNG content and the ground surface,leading to a large amount of cold LNG vapor release. If so,the diffusion of cold LNG vapor tends to be influenced by the ground surface type,the size of the cofferdam and the environmental conditions. In order to make up for the pollution of such leakage accidents,it is necessary to study effective prevention measures and the influential factors on the LNG vapor diffusion. For the like purposes,we have analyzed all the influential factors quantitatively on the UFL(explosion limit),the LFL(lower explosive limit) and the12 LFL of the methane in the downwind distance. In addition to studying the areas of the fire risks or the explosion dangers by using a software of ALOHA,we have studied the mechanism of how to reduce gradually the fire or explosion risks when LNG leaks to the water, the concrete ground,the wet sand and the dry sand for the thermal conductivity of the ground drops. When selecting the water temperature,we have found the sizes of the cofferdam and the environmental temperatures as 5 ℃,10 ℃,15 ℃,25 ℃,400 m2,600 m2,800m2,1 000 m2,and- 10 ℃,0 ℃,10 ℃,20 ℃,30 ℃,40℃,respectively,whereas the methane concentration distribution on the downwind should be analyzed quantitatively,implying that the diffusion distance of methane UFL,LFL and12 LFL on the downwind tends to increase with the rising of the water temperature,and the increase of the size of the cofferdam and environmental temperature,for the increase of water temperature,environmental temperature and contact area between LNG and ground may lead to the increase of the heat transfer between LNG and ground or the surrounding environment. The key parameters affecting methane diffusion can be said the heat transfer between LNG and environment,for the increa