本文選題：埋地天然氣管道 + 氣體泄漏擴散��； 參考：《北京化工大學》2015年碩士論文

【摘要】：天然氣的埋地管道運輸現(xiàn)已成為最為便捷、經(jīng)濟的運輸方式。但當埋地管道因土壤腐蝕、管道老化或者第三方破壞等原因發(fā)生穿孔泄漏時,不能及時探測到泄漏點的位置而影響搶險時間,因而探究埋地天然氣管道的泄漏擴散規(guī)律對于泄漏點的準確定位、泄漏防范等都具有十分重要的意義。本文主要針對埋地天然氣泄漏擴散規(guī)律進行研究,首先建立了埋地天然氣在土壤中泄漏擴散模型,考察各種條件下擴散規(guī)律,并對泄漏擴散的影響因素做了詳盡的分析討論。得出以下結(jié)論：(1)在埋地天然氣管道泄漏擴散模型,管道內(nèi)徑20mm,泄漏孔直徑2mm,土壤孔隙率0.48,管道入口壓力0.156MPa,泄漏孔處的泄漏量為2.25×104 kg·s-1。埋地的天然氣管道在發(fā)生泄漏時,主要以滲流擴散的方式,其泄漏擴散云圖近似一個圓形。通過對所建立的模型與公開文獻中實驗數(shù)據(jù)的對比分析,其相對誤差分別在10.78%和26.67%,基本驗證模型的準確性。埋地天然氣泄漏量及擴散距離隨土壤孔隙率、泄漏孔直徑以及管道壓力的增大而增加；泄漏孔形狀對泄漏范圍的影響從大到小依次為三角形、正方形、圓形；泄漏孔方向向下時的泄漏擴散距離較小；管道直徑和管道埋地深度對泄漏量和擴散距離的影響較小。(2)擬合出埋地天然氣泄漏孔泄漏量與管道壓力、泄漏孔直徑以及土壤孔隙率的關(guān)聯(lián)式如下,其模擬值與擬合公式計算值之間的誤差范圍約±15%。(3)在上述的研究基礎(chǔ)上,進而建立了埋地天然氣離開土壤在大氣中的擴散模型。模擬結(jié)果表明,風速對其縱向擴散距離具有先增加后減小的趨勢,其橫向擴散距離也有增加的趨勢；當風速超過1.5mm·s-1時,高濃度區(qū)域都富集在地表附近；建筑物可以增加埋地天然氣在大氣中的縱向擴散距離,并且建筑物距離泄漏孔越近,其對天然氣擴散的提升作用越明顯；隨著建筑物高度增加,天然氣的縱向擴散距離具有先增加后減小的趨勢,當建筑物高度在20m左右時對于氣體的提升作用最明顯。(4)建立了埋地天然氣離開土壤后在城市某小區(qū)內(nèi)的擴散模型。當發(fā)生埋地天然氣泄漏時,天然氣易于朝向較為空曠的地方擴散,2min以后其濃度為0.1%～1的擴散范圍接近穩(wěn)定；隨風速增加,高濃度甲烷區(qū)域變小,其縱向擴散距離也隨之減小。
[Abstract]:The buried pipeline transportation of natural gas has become the most convenient and economical transportation mode. However, when the buried pipeline is perforated and leaked due to soil corrosion, pipeline aging or third party damage, the location of the leak can not be detected in time and the rescue time will be affected. Therefore, it is very important to study the leakage and diffusion law of buried natural gas pipeline for accurate location of leakage point and prevention of leakage. In this paper, the laws of leakage and diffusion of buried natural gas are studied. Firstly, the model of leakage and diffusion of buried natural gas in soil is established, and the diffusion law under various conditions is investigated, and the influencing factors of leakage and diffusion are analyzed and discussed in detail. The following conclusions are obtained: (1) the leakage diffusion model of buried natural gas pipeline is: the diameter of pipeline is 20mm, the diameter of leak hole is 2mm, the porosity of soil is 0.48, the inlet pressure of pipeline is 0.156MPa, the leakage amount of leakage hole is 2.25 脳 104kg / s -1. When the buried natural gas pipeline is leaking, the seepage diffusion is the main way, and the leakage and diffusion cloud diagram is approximately a circular one. The relative error of the model is 10.78% and 26.67%, respectively. The accuracy of the model is basically verified by comparing the established model with the experimental data in the open literature. The leakage volume and diffusion distance of buried natural gas increase with the increase of soil porosity, leakage pore diameter and pipeline pressure, and the effect of leakage hole shape on leakage range is triangle, square and circular. The leakage diffusion distance is smaller when the leakage hole is downward, and the influence of pipeline diameter and buried depth on leakage volume and diffusion distance is smaller. The correlation formula of leakage pore diameter and soil porosity is as follows, the error range between the simulated value and the calculated value of the fitting formula is about 鹵15. 3) on the basis of the above research, the diffusion model of buried natural gas leaving the soil in the atmosphere is established. The simulation results show that the vertical diffusion distance of the wind speed increases first and then decreases, and the transverse diffusion distance increases, and when the wind speed exceeds 1.5mm s-1, the high concentration area is concentrated near the surface. Buildings can increase the vertical diffusion distance of buried natural gas in the atmosphere, and the closer the building is to the leak hole, the more obvious the effect of building on the gas diffusion is; as the height of the building increases, The vertical diffusion distance of natural gas increased first and then decreased. When the height of the building was about 20m, the effect of gas lifting was most obvious. 4) the diffusion model of buried natural gas after leaving the soil was established. When the buried gas leak occurs, the concentration of natural gas tends to be 0.1%, and the vertical diffusion distance decreases with the increase of wind speed, and the diffusion range of gas tends to be stable after 2 minutes of diffusion to a relatively open place, and with the increase of wind speed, the area of high concentration methane becomes smaller, and the longitudinal diffusion distance decreases.
【學位授予單位】：北京化工大學
【學位級別】：碩士
【學位授予年份】：2015
【分類號】：TE88

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本文編號：2039605