热载荷作用下天然气管道泄漏扩散分析

发布时间：2019-01-27 12:37

【摘要】：随着能源和经济的发展,具有清洁、高效、热值高等优点的能源越来越受到人们的青睐,天然气就是这样一种能源,并且具有丰富的储量,因此广泛的应用于人们的生产和生活中。与此同时,与天然气输送相配套的管道工业也得到了迅速的发展。目前,我国管道长度长、穿越范围广、易受环境的影响、且管道自身存在缺陷等因素,导致天然气管道发生泄漏继而引发火灾等事故。火灾发生时产生的热载荷对管道的正常使用和天然气的扩散过程有一定的影响。因此研究热载荷作用下管道泄漏天然气的扩散情况、泄漏扩散导致的危害后果及管道应力应变规律,对管道泄漏事故采取有效的救援措施并提出针对性的防火安全对策有着重要的应用价值。本文建立热载荷作用下天然气管道泄漏扩散模型,模拟管道泄漏时天然气的扩散云团,得到热载荷作用下天然气的扩散特性;采用ANSYS有限元软件建立管道热-结构耦合分析模型,分析了管道热应力的变化规律,最后对管道泄漏危害后果进行了分析。具体的研究内容如下:1.基于流体力学基本理论分析天然气管道泄漏扩散的流动特性,给出了天然气管道泄漏量计算公式,建立了气体流动的基本控制方程组,并讨论了天然气的燃烧机理及喷射火焰形状的计算方法。2.考虑到管道发生泄漏时,天然气扩散燃烧和环境火灾条件两种情况,建立热载荷作用下天然气扩散模型,利用已有文献数据验证了模型的正确性及求解方法的有效性,进一步模拟泄漏条件、环境条件、相邻距离等因素对天然气扩散过程的影响。3.针对天然气管道泄漏后果和伤害准则进行基础理论研究,得到喷射火灾伤害模型和其解析解,对其危害进行定量评价,即本文算例考虑极限破坏时,喷射火热辐射对周边建筑物损害半径接近93m,对人员伤害半径达到147m。4.考虑到火灾辐射和对流换热会引起管道热应力的变化,在热应力基本理论和有限元软件分析的基础上,建立考虑温度效应的天然气管道热-结构耦合分析模型,并与考虑温度效应及内压共同作用下的管道模型分析结果进行对比,发现仅考虑温度效应,泄漏孔径对各高温下的最大应力影响很小;考虑温度效应和内压共同作用的情况下,管道内压会引起泄漏孔局部应力重分布,且应变随内压的增加其增长趋势近乎呈指数增长,并得到泄漏孔可能开裂时极限内压的范围。通过本文的研究,建立了热载荷作用下天然气管道泄漏扩散模型和热-结构耦合分析模型,研究了天然气扩散特性和管道泄漏危害后果。该研究成果可为天然气管道事故的检测维护和消防安全工作提供基础数据和理论支持。
[Abstract]:With the development of energy and economy, energy with the advantages of cleanliness, high efficiency and high calorific value is more and more popular. Natural gas is such a kind of energy, and has abundant reserves. Therefore, it is widely used in people's production and life. At the same time, the pipeline industry matched with natural gas transportation has also been developed rapidly. At present, the long length of pipeline, wide crossing range, easy to be affected by environment, and the defects of pipeline itself lead to the leakage of natural gas pipeline and lead to fire and other accidents. The thermal load caused by fire has a certain influence on the normal use of pipeline and the diffusion process of natural gas. Therefore, the diffusion of natural gas leakage from pipeline under thermal load, the harmful consequences of leakage and diffusion and the stress-strain law of pipeline are studied. It is of great value to take effective rescue measures for pipeline leakage accidents and put forward targeted fire safety countermeasures. In this paper, the leakage diffusion model of natural gas pipeline under thermal load is established, and the diffusion characteristics of natural gas under thermal load are obtained by simulating the diffusion cloud of natural gas during pipeline leakage. The thermo-structural coupling analysis model of pipeline is established by using ANSYS finite element software. The variation law of thermal stress of pipeline is analyzed. Finally, the harmful effect of pipeline leakage is analyzed. The specific research contents are as follows: 1. Based on the basic theory of fluid mechanics, the flow characteristics of leakage and diffusion in natural gas pipeline are analyzed, the calculation formula of leakage volume of natural gas pipeline is given, and the basic governing equations of gas flow are established. The combustion mechanism of natural gas and the calculation method of jet flame shape are discussed. 2. Considering the condition of natural gas diffusion combustion and environmental fire when pipeline leakage occurs, a natural gas diffusion model under thermal load is established. The validity of the model and the validity of the solution method are verified by using the existing literature data. Further simulation of the leakage conditions, environmental conditions, adjacent distance and other factors on the natural gas diffusion process. 3. Based on the basic theoretical study of natural gas pipeline leakage consequence and damage criterion, the fire damage model and its analytical solution are obtained, and the damage is quantitatively evaluated. That is, when the limit failure is considered in this paper, The damage radius of the surrounding buildings was nearly 93 m and the damage radius to the personnel was 147m.4. Considering that fire radiation and convection heat transfer will cause the variation of thermal stress in pipeline, a thermal-structural coupled analysis model of natural gas pipeline considering temperature effect is established on the basis of the basic theory of thermal stress and finite element software analysis. Compared with the analysis results of pipeline model considering temperature effect and internal pressure, it is found that only considering temperature effect, leakage aperture has little effect on the maximum stress at each high temperature. Considering the effect of temperature and internal pressure, the internal pressure of the pipe will cause the local stress redistribution of the leak hole, and the strain increases exponentially with the increase of the internal pressure, and the range of the limit internal pressure when the leak hole may crack is obtained. Through the research in this paper, the leakage diffusion model and thermal-structural coupling analysis model of natural gas pipeline under thermal load are established, and the characteristics of natural gas diffusion and the harmful consequences of pipeline leakage are studied. The research results can provide basic data and theoretical support for the detection and maintenance of natural gas pipeline accidents and fire safety work.
【学位授予单位】：东北石油大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TE88

【参考文献】