【作者】 赵金辉；

【导师】 谭羽非； 白莉；

【作者基本信息】 哈尔滨工业大学 ， 供热、供燃气、通风及空调工程， 2010， 博士

【摘要】 燃气管道由于腐蚀、老化、第三方破坏等原因会引发泄漏事故,燃气管道泄漏将直接造成能源浪费、环境污染和经济损失,因此在燃气管道的运行管理过程中,需及时检测到泄漏事故的发生,确定泄漏发生的位置,判断泄漏发生的程度。本文采用实验与理论相结合的研究方法,对城市燃气直管线及支状管线的泄漏检测定位做了以下研究:基于流体动力学理论和信号检测方法,搭建了燃气管道泄漏检测综合实验台,该实验台可针对燃气直管线及支状管线,实现在不同泄漏孔径下的在线监测、检测和定位的实验研究。针对直管道可测的参数情况,归纳为A、B两类边界,给出基于瞬态流动数学模型在两类边界条件下的泄漏检测方法,实验得出直管道泄漏与阀门调节、压缩机调节所具有的不同工况特征,使模型法更方便于工程实际泄漏检测的应用。对于直管线的泄漏,提出采用改进的激励响应法进行泄漏点的定位,对泄漏孔径超过管道直径4%的情况,可实现有效定位,同时解决了激励阀门动作时间不确定的问题,使定位精度大为提高,对实验台上距离末端4m、7m、10m处的泄漏点,定位精度分别提高了0.75%、1.9%和3.15%。对直管线上不同的泄漏孔径比,进行了泄漏信号的小波熵泄漏程度分析,提出泄漏程度的划分标准,进而给出不同泄漏程度下,泄漏量的计算方法。建立了支状管线气体流动数学模型,对模型进行了解析求解,分析了支状管线运行特性,得出可将复杂支状管线分解成多个只含有进气或分气支线的简单管线叠加。对运行压力为2.5MPa的支状管线进行了模拟计算,当进气支线泄漏孔径比为3.3%、6.6%和10%时,进气支线泄漏造成主管线压力波动分别为285Pa、545Pa和1014Pa;当分气支线泄漏孔径比3%、6%、10%时,分气支线泄漏造成主管线首端点压力波动分别为28.23Pa、112.94Pa和254.11Pa。针对支状管线存在分支节点会导致压力信号产生干扰噪声和白噪声的问题,通过对压力信号的小波变换,剔除了分支节点等压力突变点引起的信号奇异,分析了支状管线各点信号小波模极大值与泄漏的关系,考察了分支节点对小波模极大值泄漏检测的影响,确定出可检测的最小泄漏孔径比为6%。研究提出适于支状管线泄漏检测定位的小波基函数,根据小波奇异点位置,实现了带有进气和分气的支状管线泄漏判断和定位。随着城市燃气化进程的加快,管道安全运行问题日益突出。开展城市燃气管道系统泄漏检测定位的研究,不仅可以保证城市燃气供应系统的安全性,降低事故的危害;而且可以提高城市燃气供应系统的安全管理水平,延长城市燃气供应系统的使用寿命,进一步提高城市燃气供应系统的经济效益和社会效益。更多还原

【Abstract】 Corrosion, aging, and damage from third-party may cause leaking accidents of gas pipelines, which will result in energy waste, environmental pollution and economic loss. Therefore, timely detecting the leakage accident, ascertaining the leakage location and estimating the leakage level are badly needed during gas pipelines are in operation. With the methodology combining experimental and theoretical research, toward straight and branch municipal gas pipelines, researches on detection and locating of leakage are done as following:Based on the fluid dynamics theory and the signal detection methods, a gas pipeline leakage detection test bench is built. On the bench, online monitoring and inspection can be achieved on the different leakage aperture of straight and branch gas pipelinesAccording to measurable parameters of straight pipelines, two kinds of boundary conditions, A and B, are induced, and method of leakage detection which are based on transient-flow mathematical model is given under the two boundary conditions. The different operating characteristics of straight pipeline leakage, valve adjustment and compressor adjustment is determined through the experiment. This makes the mathematical method more convenient in the application of practical leakage detection. For the problems of leakage in straight pipelines, improved stimulus-response locating method is proposed. The method is efficient for the condition that leakage aperture ratio is bigger than 4% of the pipe diameter. Furthermore, the problem that time of valve stimulus action is uncertain can be solved; as a result, locating precision is greatly improved. Precision is respectively improved by 0.75%, 1.9% and 3.15% on 4m, 7m and 10m leakage spot in pipeline. Level of wavelet entropy leakage of the leakage signal is analyzed on different aperture ratio, criteria of classifying the leakage level is put forward, and the leakage calculating method on different leakage level is determined.By establishing the mathematical model of branch pipeline flow and analyzing the operation characteristic, the solution is worked out that the complex branch pipeline can be decomposed into simple pipelines with inlet branches or distributary branches only. Through the simulation research of a branch pipeline with 2.5MPa operation pressure, conclusions are obtained as following: when the leakage aperture-diameter ratio is up to 3.3%、6.6% and 10% in the inlet branch, it will result in 285Pa、545Pa and 1014Pa pressure fluctuations respectively; when the leakage aperture-diameter ratio is up to 3.3%、6.6% and 10% in the distributary branch, it will result in 28.23Pa、112.94Pa and 254.11Pa pressure fluctuations respectively.Considering that the existence of branch node on branch-like pipeline will bring interference noise and white noise to the pressure signals, the signal mutation caused by the pressure jump of branch node is removed by the signal wavelet transform. The relationship between wavelet modulus maximum and leakage is analyzed, and the influence of the branch node on the wavelet modulus maximum is inspected. The minimum detectable aperture-diameter ratio is ascertained,which is equal to 6%. The wavelet function qualified to detection and locationg of branch-like pipeline leakage is put forth, and leakage detection and location on branch pipeline with inlet and distributary is determined according to the wavelet mutation position.Along with the development of municipal gas, the safe problem of pipeline operation becomes much more important. Research on the detection and location of municipal gas pipeline system not only ensures the security of gas supply system and reduces accident damage, but also enhances the security management of municipal gas supply system, prolongs the service time of the system, and improves its economic and social benefits.更多还原