大型LNG储罐泄漏工况下外罐温度场分析

Temperature field analysis of outer tank of large LNG storage tank under leakage condition

LNG全容罐包含金属内罐和预应力混凝土外罐两层罐体结构,在正常运行条件下,低温LNG液体储存在内罐中,在泄漏工况下,内罐中的LNG液体将与外罐内侧接触,此时外罐内外壁之间产生巨大的温度差,此温差需作为外罐结构设计的输入数据。基于LUSAS有限元分析软件采用2D轴对称实体单元对20万m3LNG储罐的混凝土外罐进行温度场分析,分析中考虑了保冷材料导热系数随温度的变化,计算了外罐分别在夏、冬两季时正常运行、小泄漏、中泄漏、全泄漏共8个工况下混凝土外罐的温度分布。分析结果可作为预应力钢筋混凝土外罐结构设计的温度作用输入条件。

The full-containment LNG tank contains the two-layer tank structure of a metal inner tank and a prestressed concrete outer tank. Under normal operating condition, low temperature LNG liquid is stored in the inner tank. Under the leakage condition, the LNG liquid in the inner tank will contact with the outer tank. At this time, a huge temperature difference will be generated between the internal wall and the external wall of the outer tank. This temperature difference must be used as the input data in the outer tank structural design. Based on the finite element analysis software LUSAS, the 2D axisymmetric solid element is used to analyze the temperature field for the outer tank of the 200 000 m3 LNG storage tank, and the change of thermal conductivity of the cold insulating material with temperature is taken into account in the analysis. The temperature distributions of the concrete outer tank are calculated under eight working conditions including normal operation, small leakage, moderate leakage and complete leakage in both summer and winter. The analysis results can be used as the temperature input conditions in the prestressed concrete outer tank design.