Temperature Field And Thermal Stress Analysis Of The LNG Storage Tanks Structures

Compared with the traditional energies, Liquefied Natural Gas (LNG) has some advantages such as high economy, stable operation, little contamination and so on, countries pay more attention to LNG and it has been developed all over the world. As an ultra-low temperature, flammable and explosive gas, in the event of leakage, LNG will cause serious secondary disasters. So it is very important to study the mechanical properties of LNG storage tank.In this paper, a 160 thousand cubic meters LNG tank will be studied as a sample. In normal use and cryogenic liquid leak case, the temperature and stress profile of the RC concrete outer tank are analyzed by finite element software ANSYS. The main research contents and results as follows:First, According to basic theories of heat transfer and thermal stress, the temperature field of the LNG tank is examined by theoretical calculation In different working conditions.Afterward the exact solutions of the tank wall is calculated.Second, Finite element model is formed and material parameters are confirmed through ANSYS. Comparing the result of theoretical calculation and finite element simulation, both results are consistent. Simultaneously, we can learn the temperature and thermal stress distribution of the tank wall and the important of Thermal Corner Protection (TCP).Third, In order to understand the tank wall temperature variation with time,time-history analysis of the temperature distribution of tank wall will be studied by using transient analysis methods. Under different conditions of the TCP and non-TCP, the tank wall will be modeled and analyzed respectively by the use of the third boundary condition.The research shows that no case of TCP tank wall temperature needs one week to achieve stability, there is the case of TCP takes about two weeks to reach a stable temperature of the tank wall.Finally, In normal use and cryogenic liquid leak case, three dimensional finite element model is formed, the displacement and stress of concrete storage tank will be studied by finite element analysis. And the effect of cryogenic liquid for concrete tank structure is analyzed. We can also get the relationship between the mechanical properties of LNG storage tank and the temperature field.This paper gives the temperature distribution of LNG storage tank wall in ultra-low temperature solution. And the stress profile of the outer tank are studied. The results show that the TCP have a superior shielding of cryogenic liquid in the situation of inner tank leakage. So this results is meaningful for improving the engineering level of LNG tank and has an important significance to the safety of outer tank under ultra-low temperature and formulate LNG tanks standards.