基于负压波法的管路泄漏检测及定位研究

发布时间：2018-09-19 15:30

【摘要】：管道输送在天然气、水等资源的输送方面具有其独特的优势,但由于人为等因素破坏或管道自身缺陷,不可避免地会发生泄漏。由于输送管道通常被安装在地下而且延绵数千里,使得人们无法通过直接接触管道而对泄漏进行检测和定位。本文研究所基于的负压波法,可以通过监测管道首末端的压力变化趋势,判断管道是否发生泄漏并进一步定位泄漏位置。研究中发现,影响泄漏定位精度的因素有很多,其中负压波波速和弯头对定位精度的影响特别大。因此,本文在原有的负压波泄漏检测及定位系统中,新增了辅助压力传感器,用于测定当地波速;且着重研究了弯头曲率半径对泄漏定位的影响。本文主要分析了含气率、温度对波速的影响,设计了测定波速的实验方案;比较了均值滤波、中值滤波和小波滤波对压力信号的降噪效果;分析了小波变换法、互相关法以及最大斜率法对于提取压力信号奇异点的优缺点;研究了泄漏孔大小、泄漏孔位置、管道进口压力、采样周期对泄漏检测灵敏度及定位精度的影响;采用CFD方法对管道泄漏孔附近的流场进行了模拟,分析了泄漏孔附近的速度场、压力场和湍流强度场,分析了不同泄漏孔大小、不同管道进口压力时的泄漏信号;分析了流体流经弯头后的压力变化,分析了负压波在不同曲率半径的管道弯头里的衰减规律,分析了弯头曲率半径对泄漏定位精度的影响。结果表明小波滤波的效果优于均值滤波和中值滤波;相比于互相关法和最大斜率法,采用小波分析法捕捉信号奇异点不仅准确而且可以判断出奇异点的属性。泄漏孔越大、进口压力越大、采样周期越小、泄漏孔位置越靠近管道的中间并远离弯头时,其泄漏检测的灵敏度及定位精度就越高;泄漏信号随着泄漏孔和进口压力的增大而变强;弯头曲率半径为管道直径的3倍或4倍时,其泄漏定位的精度较好。
[Abstract]:Pipeline transportation has its unique advantages in the transportation of natural gas, water and other resources, but it will inevitably leak due to the damage of man-made factors or the defects of the pipeline itself. Because pipelines are usually installed underground for thousands of miles, it is impossible to detect and locate leaks through direct contact with pipelines. In this paper, the negative pressure wave method based on this method can be used to monitor the pressure change trend at the end of the pipe head, to determine whether the leakage occurs in the pipeline and to locate the leakage position further. It is found that there are many factors that affect the accuracy of leak location, especially the velocity of negative pressure wave and the elbow. Therefore, in the original negative pressure wave leak detection and location system, a new auxiliary pressure sensor is added to measure the local wave velocity, and the effect of curvature radius of the elbow on the leakage location is emphatically studied. This paper mainly analyzes the influence of gas content and temperature on wave velocity, designs the experimental scheme of measuring wave velocity, compares the effect of mean filter, median filter and wavelet filter on the noise reduction of pressure signal, and analyzes the wavelet transform method. The advantages and disadvantages of cross-correlation method and maximum slope method for extracting singularity point of pressure signal are studied, and the effects of leak hole size, leak hole location, pipeline inlet pressure, sampling period on leak detection sensitivity and location accuracy are studied. The CFD method is used to simulate the flow field near the leak hole. The velocity field, pressure field and turbulence intensity field near the leak hole are analyzed, and the leakage signals with different leakage hole sizes and different inlet pressures are analyzed. The pressure variation of fluid flow through the bend is analyzed, the attenuation law of negative pressure wave in the pipe bend with different curvature radius is analyzed, and the influence of curvature radius of the bend on the accuracy of leak location is analyzed. The results show that the effect of wavelet filtering is better than mean filter and median filter, compared with cross-correlation method and maximum slope method, wavelet analysis method can not only capture the singularity of the signal accurately but also judge the attribute of the singularity point. The larger the leak hole, the greater the inlet pressure, the smaller the sampling period, the higher the sensitivity and positioning accuracy of leak detection when the leak hole is closer to the middle of the pipe and far away from the elbow. When the curvature radius of the elbow is 3 times or 4 times of the diameter of the pipe, the accuracy of the leak location is better.
【学位授予单位】：浙江理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：U178

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