Long-distance Gas Pipeline Road Accident Diagnostic Techniques

As one of five main transport industries, long pipeline delivery system and its safe operation are of great significant importance due to the serious consequences that may result from different reasons. Leaks from the pipelines can not only lead to a great deal of product losses and environment pollution, but also cause many people hurt, even to die. In recently, with some artificial destruction such as stealing natural gas and so on, leakage cases became more and more seriously, so it's very important and very necessary to find the leak and locate it on time in order to reduce the losses and keep the system operate normally.With the "West Development" project carried on, the natural gas pipeline in our country will get into another high tide. Plenty of pipeline will be launched into building and running. In order to reduce the harm caused by leakage to the least to get to higher leak sensitivity and location accuracy, it's very necessary to research the leak detection and location technique.Because most nature gas are transported in hyperbaric environment, and it cannot be completely dehydrated, during the transportation, with the falling of press and temperature, hydrocele will come into being in low-lying place, and even ice barrier accident. At the same time, after the pipeline runs for some time, because of the corrosion and sediment of the natural gas in the pipeline inboard wall, certainly will influence pipeline, so it is very necessary to clear the pipeline regularly, but spherical pig accident occur often.The equipments of compressor station are not only complicated, but also various in style, and the trouble is various, so they need schedule maintenance. To the trouble taking place within maintenance interval, if it can't be maintain in time when the trouble appears, some heavy trouble maybe take place, even result in the complete damage of the equipments. So it is very necessary to invent a system of accident diagnose of pipeline to find the accident in time, confirm the accident spot and the types of trouble, which can reach a higher measuring sensitivity and precision of localization.To do some ductwork accident diagnoses, we must filter the impurity signal before our analyzing. On the basis of different signals and sampling frequency, after sample pretreatment, this text go on signal aftertreatment by method of mixed filtering which is combined by recursion average filtering and median filtering and wavelet filtering technology. Due to the windage of wavelet filtering and discontinuousness of the method of rigidity valve, the article put forward the middle course between flexible valve and rigidity valve to filter the noise.Because of the complexity of the long-distance pipeline, the pipeline laid newly isfurnished with SCAD A system, and there is abundant all kinds of spot data, at the same time, according to the actual conditions of pipeline delivery in our country, drawing lessons from the advanced detection methods as well as development trend in the world at present, this article make use of instantaneous simulation based on transient model, by analyzing the difference between simulated value and measured value, and the difference between start and terminal measured value to confirm the types of trouble. As to hydrocele and ice barrier accident, making use of wavelet transform to analyzing the singularity of simulant gydraulic grade linecurve and velocity curve, and the same singularity of simulant curve and velocity curve must be accident spot. As to spherical pig accident, we can clamp a pressure waving on start-point, calculate the time difference between barotropic wave and rarefaction wave by pressure transducer, then confirm the jam point by simulating the spread of pressure wave among pipeline. But to leakage accident, we can simulate the running of pipeline according to the boundary condition of start-point and end-point, the point of intersection of two pressure curve must be the leakage point.Large numbers of equipment in compressor station have many a types of trouble, multi-scale decomposition and reconstruction of wavelet transform and its capacity to detect the signal singularity fast and accurately, wavelet transform was used to catch the singularity of equipment vibration signal, pick-up the characteristic frequency, confirm the accident spot and the type of trouble. Because of the association of equipment running, the article introduce trouble repository, make use of symptom compages to confirm the accident and the types of trouble.Finally, software based on SCADA system for inspection and detection of natural gas leakage, is developed in the article.