天然气管道小孔泄露扩散规律研究

发布时间：2018-02-23 04:14

本文关键词： 天燃气架空管道埋地管道小孔泄漏扩散　出处：《西南石油大学》2014年硕士论文　论文类型：学位论文

【摘要】：随着经济增长,我国天然气的需求量每年快速增长,促进了燃气管道的快速发展,管道运行的安全的重要性日益突出。我国目前运行的管道,由于腐蚀穿孔、第三方破坏、管道自身原因等常发生燃气泄漏。泄漏往往会诱发中毒、爆炸、火灾等恶性事件,带来不可估量的经济损失和人员伤亡,危及国家能源的运输安全。在泄漏事故中小孔泄漏占了较大比例,而目前,多数检测方法对小孔的检测精度低,漏检、误检情况时有发生。特别是对埋地管道的小孔泄漏,由于环境嘈杂,泄漏信号混乱,难以检测到。因此,探究天然气小孔泄漏扩散规律,可为泄漏点的检测、定位提供理论性的依据,对防御事故的发生具有十分重要的意义,能够较为可靠地保障管道系统安全平稳运作和社会资产。首先根据渗流理论和Fick扩散理论对埋地管道小孔泄漏进行分析,建立d/D=0.2时的埋地燃气管道在地下空间中小孔泄漏的数学模型。结合Fick扩散理论分析土壤特性及土壤属性对燃气扩散的影响,并用量纲分析法对Fick扩散模型进行求解,得出燃气扩散浓度,以期揭示不同土壤属性和降雨环境下埋地燃气管道泄漏的规律,以提高管道运输的安全性。结合实例分析得出结论：泄漏孔径的大小、土壤的含水率、土壤种类均是影响扩散规律的重要因素,且土壤越松散越干燥,燃气扩散速率越大,扩散至地面并达到爆炸极限的时间越短。此外,又探讨了架空管道小泄漏的扩散规律,对经典的高斯烟羽扩散模型进行了求解,探讨不同压力、不同风速、不同高度障碍物、不同级别的大气稳定度及不同孔径下的小泄漏扩散规律。并用Fluent软件对不同泄漏孔径、风速、孔口位置、地形条件下架空管道小孔泄漏进行模拟。结果表明：扩散浓度与压力、孔径成正比；风速加快了燃气的扩散；大气越稳定,越不利于扩散；障碍物严重影响了扩散范围；与孔口朝上的泄漏相比,孔口侧向、向下的泄漏导致的危害较大。
[Abstract]:With the economic growth, the demand for natural gas in China increases rapidly every year, which promotes the rapid development of gas pipelines, and the importance of pipeline safety is becoming increasingly prominent. Gas leaks often occur because of the pipeline's own causes. The leakage often induces toxic, explosive, fire and other vicious events, resulting in incalculable economic losses and casualties. Endangering the transportation safety of national energy. Small hole leakage accounts for a large proportion of the leakage accidents, but at present, the detection accuracy of the small hole is low by most detection methods, and the situation of missed detection and false detection occurs from time to time. Especially for the small hole leakage of buried pipeline, Since the environment is noisy and the leak signal is chaotic, it is difficult to detect. Therefore, it is of great significance to explore the laws of leakage and diffusion of gas holes for the detection and location of leak points, which is of great significance for the prevention of accidents. It can ensure the safe and stable operation of pipeline system and social assets. Firstly, according to the seepage theory and Fick diffusion theory, the small hole leakage of buried pipeline is analyzed. The mathematical model of small hole leakage of buried gas pipeline with D / D = 0.2 in underground space is established. The effects of soil properties and soil properties on gas diffusion are analyzed with Fick diffusion theory, and the Fick diffusion model is solved by dimensional analysis. The gas diffusion concentration is obtained in order to reveal the leakage law of buried gas pipeline under different soil properties and rainfall conditions, so as to improve the safety of pipeline transportation. Soil species are important factors affecting diffusion law, and the looser the soil is, the greater the gas diffusion rate is, and the shorter the time of diffusion to the ground and reaching the explosion limit is. In addition, the diffusion law of small leakage in overhead pipeline is discussed. The classical Gao Si smoke plume diffusion model is solved, and the obstacles of different pressures, different wind speeds and different heights are discussed. Under different levels of atmospheric stability and small leakage diffusion law under different aperture, Fluent software was used to simulate the small hole leakage of overhead pipeline under different leakage aperture, wind speed, orifice location and topography. The results show that the diffusion concentration and pressure are the same. The wind speed accelerates the diffusion of gas; the more stable the atmosphere is, the more unfavorable the diffusion is; the obstacle seriously affects the diffusion range; compared with the leakage on the orifice side, the downward leakage of the orifice is more harmful.
【学位授予单位】：西南石油大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TU996

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