Thermal Stress Analysis Of LNG Tank Considering The Deformation Of Perlite

With the rapid development of economy and society,energy consumption continues to increase.As a clean and efficient energy,the demand for LNG(liquefied natural gas)is expanding in China.Storage tank as the storage device of liquefied natural gas,ensuring its safety and effectiveness is of great significance.The expanded perlite is an important part of the tank wall cold insulation materials which deformation will do a negligible effect on its insulation effect.This paper takes a 220 thousand cubic metre LNG full storage tank as an example,the leakage of heat and temperature of the tank wall of each parts are calculated,and the temperature-stress coupled field analysis of the tank wall is carried out.The main contents of this paper include:Using basic theory of heat transfer,considering natural convection condition of large space outside storage tank,to determine the surface temperature and calculate the leakage heat of each part of the tank,then to get the overall evaporation rate of the tank,and finally to compare the results with relevant code.Without considering the natural convection condition of external large space,the leakage heat and daily evaporation rate of the tank are calculated assuming the outer wall temperature of the tank is consistent with the ambient temperature.Comparing the calculated results with the two methods,the rationality of calculating the heat leakage rate and daily evaporation rate of the tank with fixed temperature boundary condition is discussed.Using the finite element software ABAQUS,the refined two-dimensional model of the whole tank thermal insulation system is established.The steady-state temperature field of the tank is analyzed under two kinds of environmental temperature boundary conditions in summer and winter which will be compared with the previous theoretical results.Considering the compression deformation of expanded perlite in the tank wall part,at the top of which is provided with a 1m vacuum region,the heat leakage and surface temperature are calculated and compared with the result calculated without deformation.The expanded perlite material element within one meter of the top is cleared and replaced with thermal radiation conditions.Based on the sequential coupling analysis method,the DP constitutive model with ideal elastoplasticity and contact element are adopted to analyze thermal stress tank wall insulation system and discuss the input parameters which influence the deformation of perlite material.According to the commonly used Janssen formula of granular material in the silo,the stress of expanded perlite insulation system is calculated,and on this basis,the comparative analysis of the results of finite element analysis is carried out.