Experimental Research On The Leak Detection And Location For Gas Transmission Pipelines

Pipelines transport is the most important means of natural gas long distanse transmission, however, there are many causes that is hard to avoid leading to pipelines leakage, such as varied topography, corrosion of pipeline, damage by nature or people and self-default of pipeline. It not only causes great loss of material, but also pollutes the environment; what's more, it may lead to serious casualty, as a result, detection technique of gas transmission pipelines leakage is significant to maintain pipelines safety, safeguard the safety of people's life and property, and decrease the pollution to environment.On the basis of study and analysis of detection technique of pipelines leakage home and abroad, transient model is used to detect leakage and locate the leaking point in this paper. The fundamental principle of leak detection method based on transient model is described and the flow fundamental mathematical equations are established, furthermore, characteristic line method is used to solve the nonlinearity system of equations and it provides the theoretical principle for leak detection.A suit of acoustic leak detection device in high pressure gas transmission pipeline is designed. All kinds of parameters of this device and the size of all meters are defined by use of much simulation and calculation, most of all, the propagation characteristic is in-depth studied and the type of acoustical transducer is selected, then similarity between the test model and field gas transmission pipeline is analyzed and the popularization of the model test is verified; In the computer system, data acquisition system of the gas transmission pipeline, that is based on virtual instrumentation is designed by adopting LabVIEW environment.Indoor and field tests on gas transmission pipelines are made, then transient model method is used to detect the leakage and locate the leakage position and many the influencing rule of leak to flow parameters in pipelines are drawn. The test results make known that leak detection method based on transient model can detect and leakage accurately and quickly, and detect the leak rate quickly; The leakage position can be estimated roughly and the error of leakage location decreases with the increment, when the leak rate is greater than 4%, the error of leakage location in the indoor and field tests are both less than 10%. In addition, the velocity of pressure wave is calculated by adopting modified loop iteration method and on the base of field test results, the correctness and accuracy of calculation formulas are validated.