埋地燃气管道泄漏量计算及扩散规律研究

发布时间：2018-08-20 11:12

【摘要】：按照《天然气发展“十二五”规划》的要求，2015年我国天然气消费量将达到2300亿立方米，用气普及率将进一步提高。根据目前中国天然气利用政策和天然气消费市场需求，天然气管道建设将迎来一个高潮。由泄漏导致的燃气损失及安全问题，应该被加以重视。为了解决好这两个方面的问题，对输气管道泄漏量计算及扩散规律进行研究成为目前急需解决的关键课题。本文旨在分析埋地天然气管道泄漏量大小与原有泄漏量计算公式的关系，以及泄漏天然气经土壤渗透后的扩散规律问题，并分析外部条件对扩散规律的影响。在泄漏量计算的研究中，引入土壤密度的概念，将土壤分为自然土壤、密实土壤、结块土壤三种类型。测定三种土壤条件下，不同泄漏孔径、不同工作压力下的泄漏量大小，并与非埋地条件下泄漏量以及原有模型理论计算值进行对比，得到密实土壤埋地时，泄漏量约为未埋地时的75%~85%，土壤密度较大，处于结块状态时，前者约为后者的5%左右。在泄漏天然气扩散规律的研究中，将气体在土壤中的流动理解为渗流理论的范畴。在充分了解达西定律、多孔介质理论的基础上，通过建立实验平台，测得密实土壤的内部阻力系数及粘性阻力系数，并测得土壤孔隙率。以某城镇典型道路天然气管道泄漏模型为例，建立物理模型，利用CFD数值模拟软件，对多种工况下的泄漏进行模拟，，得到甲烷浓度分布图以及扩散速度矢量图。分析了土壤对泄漏扩散的影响，以及风速、温度、埋地深度等外部条件对泄漏扩散的影响。发现埋地条件下泄漏天然气更易聚集，处于较高甲烷浓度的危险范围更大。所得结果可以帮助工程人员了解埋地管道泄漏后天然气的扩散规律，进而根据监测点甲烷浓度大小，大致判断危险范围，从而采取更有效的应急救援措施。文章最后对该课题未来可进行的工作进行了展望。
[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.
【学位授予单位】：重庆大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TU996

【参考文献】