The Numerical Simulation Study Of Thermal And Strength Response Of Liquefied Petroleum Gas Tank Exposed To Pool Fire And Jet Fire

In recent years, release, fire and explosion accidents of liquefied petroleum gas(LPG) in Tanks happen more and more frequently due to considerable use of liquefied petroleum gas in industry and daily life as fuel, which can cause severe loss of human life and property. In many countries, therefore, great attention is paid to such accidents and a lot of experimental and numerical research works are carried out especially about the thermal response behavior of liquefied gas subjected to fire engulfment. Owing to the brevity and complexity of tank explosion, it is very difficult to investigate the mechanism of these fire and explosion accidents of liquefied gas completely only by experimental research. Accordingly, numerical simulating research has being carried out in this research field, i.e. analyzing physical phenomena based on experiments, setting up relevant physical models and mathematical models and modeling by computer imitate technique, and great progress has been made. Among these researches thermal response simulation of a liquefied gas tank exposed to a fire, mechanism of these fire and explosion accidents of liquefied gas are very important to avoid these accidents. In this thesis, the researches and analysis for this topic are conducted as followings.(1) The numerical simulation for fire environment of LPG tank is studied. Tank fire is a typical kind of pool fire or jet fire. In the past decades, many scholars carry out a lot of work on the characteristic of burning, mechanism, physical characteristics and disaster simulation calculation of indoor and outdoor pool fires and jet fire. Most research focuses on burning process, fire behavior and thermal radiation of flame. On the base of the study done by predecessor, some important parameters of the research on fire of LPG tank are analyzed, such as flame height, environment speed, diameter of pool fire and flame height, the distance of jet fire. And the cases of LPG horizontal tank exposed to the environment which pool fire and jet fire are together existed are simulated and numerated. (2) The numerical simulations of thermal response of LPG tank exposed to the veritable environment are carried out. The differential equations and the veritable boundary conditions that describe the thermal response of a liquefied gas tank subjected to a fire are built according to mass conservation, energy conservation and combined with research findings of the entire world. These equations including tanks wall and medium in the tanks form mathematic models for the thermal response of a liquefied gas tank subjected to accidental fire conditions. The models of thermal response of PLG tanks subjected to fire are set up. A more accurate physical model is described without using hypotheses of former researchers. In the article, three-dimensional numerical simulation has made. Importing outside boundary condition of the LPG tank exposed to pool fire and jet fire, this model is simulating thermal response of a long horizontal-cylindrical tank filled with 85% propane.(3) The numerical simulations of strength response of LPG tank exposed to the veritable environment are carried out. For liquefied gas horizontal tank exposed to fire environment, thermal response occurs due to the effect of thermal radiation, that is, temperature and pressure of medium change inside the horizontal tank, and temperature on the body of spherical tank exposed to fire environment, stress distribution of horizontal tank under the action of the different temperature and pressure was studied by use of thermal-structure coupling in the ANSYS software. According to the stress classifying method, the strength of the horizontal tank exposed to fire environment was calculated and safety of LPG horizontal tank at high temperature was evaluated.