Numerical Simulation Of Inner Tank Leakage In LNG Storage Tanks

The outer tank of a double steel wall full containment LNG storage tank is generally constructed of steel that cannot withstand low temperatures.Leakage of the inner tank will cause damage to the insulation structure of the tank and the outer tank.In this paper,according to the structure of the double steel wall full containment LNG storage tank and the physical properties of the LNG,the internal flow field of the tank after the inner tank leaks is calculated by the MAC algorithm to determine the leakage mode of the LNG inner tank.Aiming at the small hole leakage mode of the LNG inner tank,thermal boundary conditions and initial conditions are set,the inner wall and the insulation grids number are divided,and the steady-state temperature field of the insulation layer under normal operating conditions and the temperature field under leakage conditions are calculated.By analyzing the convective heat transfer at the leak point,a two-dimensional unsteady seepage equation is established,and the flow field distribution of the leaked LNG in the thermal insulation layer is calculated;the calculated velocity is added to the two-dimensional unsteady heat transfer equation as a convection diffusion term,through the coupling of the velocity field and the temperature field,the temperature field of the insulation layer based on the flow field distribution is calculated.Analysis of the simulation results shows that when a leak occurs in the LNG inner tank,the leaked liquid first gathers at the bottom of the storage tank,and the elastic blanket insulation near the leak source first cools down to the temperature of the LNG,and the temperature gradient here is larger,and then along the bottom of the tank gradually penetrated into the expanded perlite insulation.The comparison of Fluent simulation results under the same initial conditions and leakage conditions verifies the results of this simulation calculation.Finally,through the analysis of the temperature data calculated for different leakage conditions,the distribution of leakage monitoring points when the inner tank leaks is obtained,and determine the location of the leak point by the fitting function,which provides a theoretical basis and scientific guidance for the rescue and accident analysis of inner tank leakage accidents,and minimizes the damage caused by leakage accidents.