【摘要】：按照《天然氣發(fā)展“十二五”規(guī)劃》的要求，2015年我國(guó)天然氣消費(fèi)量將達(dá)到2300億立方米，用氣普及率將進(jìn)一步提高。根據(jù)目前中國(guó)天然氣利用政策和天然氣消費(fèi)市場(chǎng)需求，天然氣管道建設(shè)將迎來(lái)一個(gè)高潮。由泄漏導(dǎo)致的燃?xì)鈸p失及安全問(wèn)題，應(yīng)該被加以重視。為了解決好這兩個(gè)方面的問(wèn)題，對(duì)輸氣管道泄漏量計(jì)算及擴(kuò)散規(guī)律進(jìn)行研究成為目前急需解決的關(guān)鍵課題。本文旨在分析埋地天然氣管道泄漏量大小與原有泄漏量計(jì)算公式的關(guān)系，以及泄漏天然氣經(jīng)土壤滲透后的擴(kuò)散規(guī)律問(wèn)題，并分析外部條件對(duì)擴(kuò)散規(guī)律的影響。 在泄漏量計(jì)算的研究中，引入土壤密度的概念，將土壤分為自然土壤、密實(shí)土壤、結(jié)塊土壤三種類(lèi)型。測(cè)定三種土壤條件下，不同泄漏孔徑、不同工作壓力下的泄漏量大小，并與非埋地條件下泄漏量以及原有模型理論計(jì)算值進(jìn)行對(duì)比，得到密實(shí)土壤埋地時(shí)，泄漏量約為未埋地時(shí)的75%~85%，土壤密度較大，處于結(jié)塊狀態(tài)時(shí)，前者約為后者的5%左右。 在泄漏天然氣擴(kuò)散規(guī)律的研究中，將氣體在土壤中的流動(dòng)理解為滲流理論的范疇。在充分了解達(dá)西定律、多孔介質(zhì)理論的基礎(chǔ)上，通過(guò)建立實(shí)驗(yàn)平臺(tái)，測(cè)得密實(shí)土壤的內(nèi)部阻力系數(shù)及粘性阻力系數(shù)，并測(cè)得土壤孔隙率。 以某城鎮(zhèn)典型道路天然氣管道泄漏模型為例，建立物理模型，利用CFD數(shù)值模擬軟件，對(duì)多種工況下的泄漏進(jìn)行模擬，，得到甲烷濃度分布圖以及擴(kuò)散速度矢量圖。分析了土壤對(duì)泄漏擴(kuò)散的影響，以及風(fēng)速、溫度、埋地深度等外部條件對(duì)泄漏擴(kuò)散的影響。發(fā)現(xiàn)埋地條件下泄漏天然氣更易聚集，處于較高甲烷濃度的危險(xiǎn)范圍更大。所得結(jié)果可以幫助工程人員了解埋地管道泄漏后天然氣的擴(kuò)散規(guī)律，進(jìn)而根據(jù)監(jiān)測(cè)點(diǎn)甲烷濃度大小，大致判斷危險(xiǎn)范圍，從而采取更有效的應(yīng)急救援措施。文章最后對(duì)該課題未來(lái)可進(jìn)行的工作進(jìn)行了展望。
[Abstract]:According to the requirements of the 12th Five-Year Plan of Natural Gas Development, China's natural gas consumption will reach 230 billion cubic meters in 2015, and the popularization rate of gas consumption will be further increased. According to the current natural gas utilization policy and natural gas consumption market demand, natural gas pipeline construction will usher in a climax. Gas loss and safety problems caused by leakage should be taken seriously. In order to solve these two problems, the study on the calculation and diffusion law of gas pipeline leakage has become a key issue that needs to be solved. The purpose of this paper is to analyze the relationship between the leakage amount of buried natural gas pipeline and the original formula for calculating the leakage rate, and to analyze the diffusion law of the leaked natural gas through the soil, and the influence of external conditions on the diffusion law. The concept of soil density is introduced in the study of leakage calculation, and the soil is divided into three types: natural soil, dense soil and caking soil. The leakage amount under three different soil conditions, different leak aperture and different working pressure was measured, and compared with the leakage amount under the condition of non-buried soil and the theoretical calculation value of the original model, when the dense soil was buried, the results were obtained. The leakage is about 75% of that of the unburied area, and the density of the soil is high. When the soil is in the caking state, the former is about 5% of the latter. In the study of the diffusion law of leaking natural gas, the flow of gas in soil is understood as the category of seepage theory. Based on the understanding of Darcy's law and the theory of porous media, the internal resistance coefficient and viscous resistance coefficient of dense soil were measured by establishing an experimental platform, and the soil porosity was measured. Taking a typical road natural gas pipeline leakage model of a town as an example, the physical model is established. The leakage under various working conditions is simulated by using CFD numerical simulation software, and the methane concentration distribution map and diffusion velocity vector diagram are obtained. The influence of soil on leakage diffusion, and the influence of wind speed, temperature and depth of buried soil on leakage diffusion were analyzed. It is found that the leaking natural gas accumulates more easily under buried conditions, and the danger range of higher methane concentration is larger. The results obtained can help engineers to understand the diffusion law of natural gas after the leakage of buried pipeline, and then judge the dangerous range according to the concentration of methane in monitoring points, and then take more effective emergency rescue measures. Finally, the future work of this topic is prospected.
【學(xué)位授予單位】：重慶大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2014
【分類(lèi)號(hào)】：TU996

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