超低温作用下LNG储罐热-结构耦合分析

在内罐泄漏等特殊工况下，预应力混凝土罐壁将直接暴露在-162℃的超低温环境中，由此产生的温度应力和变形可能会对储罐的结构安全带来威胁。因此，对LNG储罐混凝土外罐进行泄漏等低温条件下的力学验算和评估十分重要。本文利用有限元法（FEM）对内罐泄漏工况下的大型LNG预应力混凝土储罐进行热-结构耦合分析，结果表明：混凝土罐壁的降温过程较为缓慢，温度沿壁厚（0．8m）方向达到稳定需要大概一周的时间；热保护角范围以外的预应力钢绞线温度分别降低至-87℃（夏季）和-102℃冬季）；低温作用使混凝土罐壁产生较大的内力和变形，罐壁内外两侧温差越大，内力、变形越大，在设计中可通过设置热保护系统来防止其对储罐结构可能造成的破坏。研究成果对于评估超低温对混凝土外罐结构安全的影响、制定液化天然气储罐结构安全规范具有一定的指导意义。

Thermal-structural Coupling Analysis of LNG Tanks under Ultra-low Temperature

In the case of leakage of the inner tank, outer wall of pre-stressed concrete LNG tank would be directly exposed to -162℃ultra-low temperature environment, which may pose a threat to LNG tanks. So, it is necessary for concrete wall of LNG tank to be checked and evaluated for its mechanical properties in low temperature. The thermal-structural coupling analysis of large pre-stressed concrete LNG tanks is performed with finite element method （FEM） in the situation of inner tank leakage in this paper The result shows that the cooling process of outer wall is slow. Thermal distribution becomes constant after one week from initial of leakage of LNG. The temperature of pre-stressing tendon, which is unprotected by the thermal corner pro- tection, falls to -87 ℃ in summer and -102 ℃in winter due to LNG leakage. Low temperature creates large internal force and deformation to outer wall. Thermal protection system may prevent potential damage to LNG tanks. So it has an important significance to the safety assessment of concrete outer tank under ultra-low temperature and formulate relevant LNG tanks standards.