大型LNG储罐罐壁隔热层保冷性能及其优化

Cold performances of insulation layers in large LNG storage tanks and its optimization

为了提高大型LNG储罐罐壁隔热层的保冷性能,对其隔热层厚度进行优化。采用理论分析与数值计算相结合的方法,在不同隔热层厚度下,从储罐的保冷损失、蒸发率、外罐壁受力及变形情况3个方面来评价隔热层保冷性能,并对隔热层的厚度进行优选。结果表明:太阳辐射对储罐温度场影响较大,在进行LNG储罐保冷分析及相关设计时不可忽略;LNG储罐罐壁隔热层(主要指膨胀珍珠岩)厚度与保冷损失率呈反比,当膨胀珍珠岩达到一定厚度后,随厚度增加,保冷损失减小缓慢;随着隔热层厚度的变化,外罐壁的受力和变形较大,因此应该关注不同隔热层厚度对罐壁结构的影响。

To enhance cold performances of thermal insulation layers in large LNG storage tanks, it is necessary to optimize the thickness of such thermal insulation layers. With combination of theoretical analysis and numerical calculation, cold performances of insulation layers with different thicknesses are assessed in respect of cold losses, vaporization rates, and stress and deformation of outer tank walls. Then, optimal thickness of the insulation layer is determined. Following conclusions are drawn from the study. Firstly, solar radiation should not be neglected in the cold performance analysis and related design of the insulation layer because it has a great infl uence on the temperature fi eld of storage tank. Secondly, thickness of the insulation layer（mainly expanded perlite） is inversely proportional to the cold loss rate. When the thickness of the expanded perlite reaches a certain value, the cold loss rates decrease slowly as the thicknesses increase. Thirdly, changes in thicknesses of the thermal insulation layers will affect stresses and deformation of the outer tank walls. Consequently, cares shall be taken for impacts of insulation layers with different thicknesses on structural safety of tank walls.