本文關鍵詞： 天燃氣 架空管道 埋地管道 小孔泄漏 擴散　出處：《西南石油大學》2014年碩士論文　論文類型：學位論文

【摘要】：隨著經濟增長,我國天然氣的需求量每年快速增長,促進了燃氣管道的快速發(fā)展,管道運行的安全的重要性日益突出。我國目前運行的管道,由于腐蝕穿孔、第三方破壞、管道自身原因等常發(fā)生燃氣泄漏。泄漏往往會誘發(fā)中毒、爆炸、火災等惡性事件,帶來不可估量的經濟損失和人員傷亡,危及國家能源的運輸安全。在泄漏事故中小孔泄漏占了較大比例,而目前,多數(shù)檢測方法對小孔的檢測精度低,漏檢、誤檢情況時有發(fā)生。特別是對埋地管道的小孔泄漏,由于環(huán)境嘈雜,泄漏信號混亂,難以檢測到。因此,探究天然氣小孔泄漏擴散規(guī)律,可為泄漏點的檢測、定位提供理論性的依據(jù),對防御事故的發(fā)生具有十分重要的意義,能夠較為可靠地保障管道系統(tǒng)安全平穩(wěn)運作和社會資產。 首先根據(jù)滲流理論和Fick擴散理論對埋地管道小孔泄漏進行分析,建立d/D=0.2時的埋地燃氣管道在地下空間中小孔泄漏的數(shù)學模型。結合Fick擴散理論分析土壤特性及土壤屬性對燃氣擴散的影響,并用量綱分析法對Fick擴散模型進行求解,得出燃氣擴散濃度,以期揭示不同土壤屬性和降雨環(huán)境下埋地燃氣管道泄漏的規(guī)律,以提高管道運輸?shù)陌踩�。結合實例分析得出結論：泄漏孔徑的大小、土壤的含水率、土壤種類均是影響擴散規(guī)律的重要因素,且土壤越松散越干燥,燃氣擴散速率越大,擴散至地面并達到爆炸極限的時間越短。 此外,又探討了架空管道小泄漏的擴散規(guī)律,對經典的高斯煙羽擴散模型進行了求解,探討不同壓力、不同風速、不同高度障礙物、不同級別的大氣穩(wěn)定度及不同孔徑下的小泄漏擴散規(guī)律。并用Fluent軟件對不同泄漏孔徑、風速、孔口位置、地形條件下架空管道小孔泄漏進行模擬。結果表明：擴散濃度與壓力、孔徑成正比；風速加快了燃氣的擴散；大氣越穩(wěn)定,越不利于擴散；障礙物嚴重影響了擴散范圍；與孔口朝上的泄漏相比,孔口側向、向下的泄漏導致的危害較大。
[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.
【學位授予單位】：西南石油大學
【學位級別】：碩士
【學位授予年份】：2014
【分類號】：TU996

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