Research On Detection And Localization Of City Gas Pipeline Leak

With the deterioration of the environment pollution, people began to search for aclean，efficient new energy to replace，natural gas began to enter people’s attention，and becoming more and more attention at home and abroad.The main means oftransportation of natural gas is pipeline, because of its explosive properties, the safetyof the pipeline is become more important.With the adjustment of the energy sourcestructure in China, urban underground gas pipeline is being developed.So the leakdetection and exclusion of natural gas is seem to be particular important.What’smore, due to the low pressure, multi-branch and layed in complex urban noise and soon，the detection and location of the pipeline leak are very difficult. Leak detectionand location of gas pipeline has become one of the key technologies to be solvedoperation of natural gas pipe network in the city of wisdom. In this paper, combinedthe theory of generalized acoustic emission with chaos theory，then applied themtheory to urban natural gas pipeline leakage detection and location.GeneralizedAcoustic Emission is a developing theory which is used to explain the stress wavecaused by leak of the pipeline’In this theory, the leak signal is considered ascontinuous signal. Unlike negative pressure wave theory, continuity of the leak signalwill not fail to detect the leakage signal just for not capturing negative wave intime.Weak signal detection which based on chaos is a brand-new domain in signalprocessing means. In this paper，combined the theory of generalized acoustic emissionwith chaos theory, then applied them theory to urban natural gas pipeline leakagedetection and location.The main works of this thesis are： 1)Based on acoustic emission detection technology，formed a natural gaspipeline leak detection system simulation, the system consists of a computer, datacollection edition? acoustic emission sensors and pipes and other components.2)Generalized acoustic emission theory was used to illuminate the stresswavephenomenon caused by the leakage. According to this theory researched thecharacteristics of the low-pressure gas pipeline leakage signal of the urban natural gaspipeline network.3)Basedon chaos theory, chaotic system has the characteristics that for the weakperiodic signal of the same frequency is very sensitive，but has a strong immunity tostrong noise signal, from this we researched the method of weak peirodic signaldetection and make the detection of leakage signal in the complicated and changeableenvironment noise come true；4)Introduce a single point of leakage model and cross-bispectrum theory, toachieve a single point positioning natural gas leak.Experimental results show thecorrectness and feasibility of this method on the project.The theory has very highapplication value for detecting range in detection and location of leakage of theindividual.A large number of ifeld experiment results show that the chaotic technology caneffectively achieve complex urban environmental noise in the underground mediumpressure and low pressure gas pipeline leak detection B. The cross bispectrum theoryto the city underground gas pipeline leak location，can effectively avoid the problemwhich due to the noise signal correlation that make the inaccurate positioning.Theresults show that this method can be more accurate for the pipe network leak locatingand positioning accuracy.