Study On Thermal Insulation Capacity And Load-carrying Capacity Of A Cryogenic Storage Tank

Cryogenic storage tanks are more and more widely used in industrial productions. Because of instoring pressurized cryogenic media, the structure and operating conditions of the cryogenic storage tanks are more complicated compared with ordinary storage vessels. And in the design of cryogenic storage tanks, both the strength and thermal insulation requirements should be satified under the normal operations condition.In this thesis, beside experiments, finite element method was used to simulate the heat transfer of a cryogenic storage tank. Sensitivity analysis of the parameters of the multilayer insulation structure was carried out and a formula of calculating the heat transfer was proposed based on the numerical simulation results, which is helpful for designing the insulation layers of cryogenic tanks. Meanwhile, strength assessment of the cryogenic storage tank was conducted based on the design-by-analysis method. Multi-objective driven optimization was employed to optimize the structure of the reinforcement ribs on the outer vessel. The main work and results are listed below.(1) A steady-state heat transfer model was established to simulate the heat transfer of the cryogenic tank named FV1-2000-008/16 with the software of ANSYS Workbench. Measured by the static evaporation rate,differences between the umerical simulation results and the experimental ones are within 1.2%, indicating that the numerical simulation for the heat transfer of the cryogenic tank is reliable.(2) By using the numerical simulation method, the sensitivity analysis of the parameters of the multilayer insulation structure was carried out to study the thermal insulation capabilityof the cryogenic tank.Results show that increasing the length and reducing the thickness of the neck tube can reduce the heat loss of the cryogenic storage tank effectively. Increasing the thickness of insulation layers was also an effective way to reduce the heat loss. Based on the enough simulation results, a formula for the heat transfer of the cryogenic storage tank was fitted by using MATLAB.(3) A static evaporation test for the cryogenic storage tank CMSH-350 was carried out. Meanwhile, the static evaporation rate was calculated with numerical simulations and formula obtained in this thesis.Compared with experimental results, deviations for the numerical simulation and formula evaluation are is within 1.4% and 1.2%respectively, which again verified the reliability of the numerical simulation and the obtained formula.(4) The cryogenic storage tank CMSH-350 was designed with the software of SW6 based on the design-by-rules and the original strength parameters were obtained. Then stress analysis of the structure was carried out with ANSYS Workbench. Structural improvement of the cryogenic storage tank CMSH-350 was performed based on the stress analysis results. Strength assessment was completed conforming to JB4732-1995 Steel Pressure Vessels-----Analysis Design Code.(5) In order to enhance the anti-instability ability of outer vessle under external pressure load, reinforcement ribs were arranged on the vessel. Multi-objective driven optimization was conducted to optimize the reinforcement ribs under the given requirements for the critical buckling pressure. By reducing the weight of the equipment, the lightweight design of the equipment was realized.(6) Limit analysis was also performed on the outer vessel of the cryogenic storage tank CMSH-350 after optimization. Results show that strength requirement is satisfied based on JB4732-1995 Steel Pressure Vessels-----Analysis Design Code.