Gas Pipeline Leak Location Study

With the progressive growing demand for high-quality clean energy and fuel, such as natural gas, and the exploitation and development of large quantities of gas field far from the center, The natural gas long-distance pipeline transmission system gradually becomes more complicated.Natural gas transmission pipeline generally have the phenomenon of "explode after leaking", that is to say, if the natural gas leaks in pipeline, and then the exploding of pieline is ongoing. The research on pipeline leakage localization is carried out in this paper. The main efforts accomplished can be summed up as the following aspects:Two crucial technologies in negative pressure wave leak-location method are analyzed in this paper. One is presented which can eliminate the dynamic response time difference between pressure sensors in the beginning and end of the pipeline; the other is to unify the system time between data collecting systems in two ends by adopting GPS.Because of its being affected by gas's density, pressure, specific heat, and pipeline material so on, the velocity of negative-pressure-wave is not the spread speed of sound wave in the air. The unsteady momentum conservation is employed; the expression formula of the velocity of negative-pressure-wave is established. Considering the influence of the velocity on negative-pressure-wave, the location formula was modified in some degree. When locating the leaks with the location formula, the iterative approach algorithm is employed to increase the location accuracy level of the system. Because the temperature along the pipeline is not a constant, it changes the velocity of the negative-pressure-wave; the Romberg algorithm of numeric integral and the searching for algorithm are emloyed to locate the leakage.Multi-scale decomposition and reconstruction of wavelet transform is applied to filter the noise of negative-pressure-wave, which was brought by leakage. With the capacity to detect the signal singularity fast and accurately, wavelet transform was used to catch the break point of pressure signal. The work improved the accuracy of Δt in location formula, and the location accuracy is improved.Through the analysis in this paper, the leak simulation of is carried out in a gas transport pipeline, the wavelet is applied to analyze the negative-pressure-wave signals. By analyzing, the catastrophe point of the signal is found out. To use the leak localization software, the leak point is determined. The result of leak localization indicates that the improved localization algorithms have improved the accuracy of leak localization.Finally, based on SCADA system a plan, to detect and locate the long natural gas pipeline leakage, is proposed in the paper.