大型LNG储罐在高温状态下外壁温度场及应力分布有限元分析

Finite Element Analysis of Wall Temperature Field and Stress Distribution of Large LNG Storage Tank at High Temperature

为了分析LNG储罐在遭受长时间火灾后的应力分布,利用有限元软件ANSYS建立了火灾下储罐的有限元模型.首先对储罐进行了热分析,然后将求得的温度作为体载荷加到罐体上进行结构分析,重点分析了结构在高温作用下的内应力和应变的大小与分布.分析结果表明:在着火情况下,经过6,h,储罐内部温度升高不多,即耐火极限可以达到6,h;罐壁径向变形受高温荷载的影响较大;罐壁沿厚度方向上各点的应力变化趋势相近;罐壁的径向应力相对环向应力和轴向应力来说很小,可以近似认为储罐罐壁处于双轴受力状态.

The fire finite element model of the tank was established based on the finite element software ANSYS to analyze the stress distribution of the LNG storage tanks after the fires. First, its thermal analysis is conducted, and after getting the temperature as the body load researchers apply it to body structure analysis, focusing on the analysis of the structure under the effect of elevated temperature stress and strain distribution and size. The results show that in the case of fire, after 6 hours, the tank temperature is increased not much, which means that the limit of 6 hours of fire resistance can be reached. The radial deformation of tank wall is affected by temperature. The stress variation along the direction of tank wall thickness tends to be close. The radial stress of tank wall is very small compared to circumferential stress and axial stress. So the stress state of the tank wall can be regarded as under biaxial stress state.