Detection of leaks in underground gas pipelines.

摘要

Transport pipelines of hazardous gases are prone to leaks that can create dangerous situations in a very short time. Currently, available methods for continuous monitoring of gas-carrying, buried pipelines are limited to detection of relatively large leaks. A system that can reliably detect smaller leaks, and still be economical to implement and use is desired.; The system presented here detects leaks by monitoring the acoustic emissions that the leaks generates. The sound generated by a leak propagates through the metal walls of the pipe and can be detected from some distance away. Digital signal processing and pattern recognition techniques are used to detect these leak sounds and alert the user of their presence.; The system consists of signal analysis units placed at a predetermined distance from each other, along the entire length of the pipeline. The distance is chosen in such a way that at least one unit is able to detect the sound of a leak. Each unit is able to detect a near-by leak, while rejecting all other non-leak sounds. The units communicate with a central station, which is used as an interface between the system and the pipeline monitoring personnel.; This research is divided into five major parts. The first part consists of determining the sound transmission characteristics of the buried pipeline, modeling these characteristics and determining how the pipeline affects acoustic signals propagating through it. The second part involves analyzing the nature of the acoustic leak signals and selecting features that best represent these signals. The third part evaluates the performance of the system through extensive simulation. The fourth part contains the realization of the central station and the remote units. The last part involves experimental evaluation of the system under realistic conditions.