【作者】 葛秀坤；

【导师】 蒋军成；

【作者基本信息】 南京工业大学 ， 安全技术与工程， 2004， 硕士

【摘要】 近年来,随着液化气作为燃料在工业和日常生活中大规模的使用,液化气泄漏、容器爆炸及火灾事故日益增多,造成了大量的财产损失和人员伤亡。因此,工业界安全问题的迫切需要和其学术上的综合性、复杂性,使得当今世界各个国家都在积极组织力量,从多角度、多侧面对事故的发生机理及原因特别是火灾环境下液化气储罐的热响应进行了大量的实验和模拟研究。但是由于储罐爆炸过程的短暂性和复杂性,只靠实验研究是难以对这些事故的发生机理进行全面细致的研究。因此,各个国家开展了广泛的数值模拟研究,即在实验基础上分析物理现象,建立相应的物理模型和数学模型,借助计算机仿真技术进行模拟,这将对预测、预防、控制事故的发生、保障生产的安全运行、提高生产效益具有重要的理论价值和实践意义。 本文根据质量守恒、能量守恒以及结合国内外研究成果建立起描述火灾环境中液化气储罐热响应的偏微分方程和相应的定解条件,包括容器壁的导热微分方程、容器内介质的传热传质微分方程,由此构成火灾环境下液化气储罐热响应的数学模型。 本文对液化气储罐热响应的数学模型采用有限差分的数值方法进行求解,对于储罐壁内节点采用直接法建立差分方程,对于边界节点采用热平衡法建立差分方程,应用全隐式差分方法求解出液化气容器壁的瞬态温度分布规律。对于容器内介质采用集总参数法,将时间离散的常微分方程的差分格式,求解出液相区和气相区的温度、密度和质量的变化规律。 对于火灾环境下液化气储罐液化气热响应行为的数值分析软件系统,采用面向对象的、可视化的快速应用程序开发软件C++Builder开发了主界面,并进行数值计算以及曲线模拟,利用Access数据库软件编制了相应的数据库对国内外著名实验条件及模拟结果进行保存和提取。该软件可以对不同火焰包围情况、不同容器形状、不同充装量等各种情况下的液化气容器的热响应行为进行模拟。 通过对火灾环境下液化气储罐热响应行为的数值模拟结果和HSE(英国健康与安全署)实验结果的比较可知,模拟结果与实验结果基本吻合,从而验证了更多还原

【Abstract】 In recent years, release, fire and explosion accidents of liquefied gas in vessel happen more and more frequently due to considerable use of liquefied 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 transitoriness 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.The differential equations and the relevant 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.A finite difference method is adopted to calculate mathematic models for the thermal response of a liquefied gas tank. The difference equations are built using a direct method for inner nodes of tank wall and using conversation of energy for boundary nodes. The transient temperature distribution of tank wall is solved using an implicit finite scheme. The temperature, density and mass variety of medium in tanks are calculated by lumped-heat-capacity method.The numerical analysis system for the thermal response of a liquefied gas tank subjected to accidental fire conditions is developed using object oriented and visual C++ Builder including the design of the main interface and drawing of simulating curves. And the relevant database is set up using Microsoft Access database to store modeling results and famous experiment conditions of the world. This software can simulate the thermal response process of a liquefied gas tank in condition of different fire environment, different shape of tank and different medium filling ratio.Comparison of simulation results and experimental results from HSE (Health and Safety Executive, UK) shows that the simulation results are consistent with the experimental results. Therefore, the physical models, the mathematical models, the. numerical methods and the program design of the numerical simulation system are proved to be reasonable.The thermal response of a tank in different conditions is simulated and the primary factors that affect the thermal response of a tank are analyzed. Several protective measures are put forward based on current conditions in which liquefied gas is used. The advantages and disadvantages of these measures are analyzed in detail. It is very helpful for the safe transportation and design of liquefied gas tanks更多还原