LNG储罐泄漏危险性影响因素分析

Analysis of the influential factors on the risks of LNG storage tank leakage

LNG(液化天然气)泄漏后产生大量的蒸汽,蒸汽的扩散受液池尺寸、泄漏区域地面类型、环境条件的影响,为了研究以上因素对LNG蒸汽扩散的影响,以方便采取事故预防措施,采用ALOHA软件对以上因素影响甲烷UFL(爆炸上限)、LFL(爆炸下限)、1/2LFL在下风向扩散的最远距离进行了定量分析,划分了可能发生火灾或者爆炸的危险区域,得出LNG泄漏到水面、混凝土地面、湿沙层、干沙层上危险性依次降低。选取水面温度分别为5℃、10℃、15℃、25℃,围堰尺寸分别为400 m2、600 m2、800 m2、1 000 m2,环境温度分别为-10℃、0℃、10℃、20℃、30℃、40℃时,对下风向甲烷体积分数分布进行定量分析,结果表明,甲烷UFL、LFL、12LFL扩散最远距离随水面温度、围堰尺寸、环境温度增加而逐渐增大。

The paper is engaged in an analysis of the influential fac- tors 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 diffu- sion 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 needssary 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 methane in the downwind distance 1 limit） and the 1/2 LFL of the In addition to studying the areas of the fire risks or the explosion dangers by using a software of ALO- HA, 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 as5 ℃, 10 ℃, 15 ℃, 25 ℃, 400 m2, 600 m2, 800m2, 1 000 m2, and - 10 ℃ , 0 ℃, 10 ℃, 20 ℃ , 30 ℃ , 40 ℃, respective- ly, whereas the methane concentration distribution on the downwind should be analyzed quantitatively, implying that the diffusion distance UFL, LFL and 1/2 LFL on the downwind tends to increase of methane 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 be- tween 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 increase of heat transfer be- tween LNG and ground can result in the increase of the evaporation of LNG, which in turn leads to the increase of the methane diffusion distance in the downwind direction.