Research On Construction Scheme Optimization And Mechanical Properties Of LNG Stainless Steel Storage Tank

LNG(liquefied natural gas)has the advantages of small land occupation,convenient storage and transportation,and greenness.It has become the fastest growing type of energy structure.As the LNG receiving terminal,LNG storage tank is the key link of LNG storage and transportation.Due to the late development of Chinese LNG industry,the current construction of storage tanks is mostly based on the introduction of foreign technologies.There is no special design specification for large-scale LNG cryogenic storage tanks in China.The design is not standardized and leads to frequent accidents.Therefore,it is of great significance to study the construction mechanical properties for large-scale LNG storage tanks for promoting the development of Chinese LNG industry.In this paper,the 30000m~3 LNG stainless steel storage tank is taken as the research object,The low temperature mechanical properties of stainless steel are studied by experiments.Through the method of numerical simulation,the mechanical properties of storage tank in the construction process are studied.The research contents of the full text are as follows:Through the axial tensile test in the temperature range of-60 ℃ ～20 ℃,the variation laws of mechanical properties and plastic deformation resistance of the austenitic stainless steel S30408 base metal,butt weld,front fillet weld and side fillet weld components with temperature are obtained.By SEM,micro-structure change were obtained.During construction,the front fillet weld should be adopted at the connection of the tank bottom and the bottom of tank wall,and the tank walls can be connected by butt weld.Based on the basic theory of solar radiation,the finite element software ANSYS was used to simulate the non-uniform temperature field distribution of storage tank under solar radiation,and to explore the effects of different division angles,tank diameters,latitudes and other parameters on the structural temperature field distribution.The results show that the tank diameter has almost no effect on the temperature field distribution of the tank wall,the maximum temperature increases by7% when the latitude increases by 20°N.Based on the basic theory of fluid dynamics,using FLUENT,wind load simulation was carried out on the storage tank,and the distribution law of the wind field around the storage tank and the wind load were obtained.Compared with the code,the accuracy of numerical simulation is verified.According to the simulated wind pressure,the anti overturning stability analysis of tank construction is carried out to judge the safety of structural construction.ABAQUS was used to carry out the mechanical simulation study of the lifting construction process of hydraulic lifting upside-down method,and to explore the influence of the displacement error of the lifting point on the distribution of structural mechanics.Studies have shown that the error between the lifting points of the storage tank should not exceed 1/1000 of the lifting device.Based on the probability distribution model of lifting error,the parametric analysis is carried out,and the lifting coefficient of uneven lifting is 1.8.