DOE-Funded Acoustic Monitor Passes Key Field Test
A new, lightweight device that uses natural gas itself to detect leaks in natural gas pipelines has been successfully tested on a transmission main owned and operated by Dominion Transmission Inc., in Morgantown, W.Va.
The test was conducted by the U.S. Department of Energy's National Energy Technology Laboratory (NETL) and West Virginia University, which has worked with NETL for the past 2 years to advance the detection system. The device is one of a suite of technologies being developed by the Energy Department's Office of Fossil Energy to effectively and efficiently monitor the 1.3 million miles of transmission and distribution pipelines which crisscross the United States.
Known as the Portable Acoustic Monitor Package (PAMP), the device—14 inches long, 18 inches tall, and weighing only 5 pounds—uses a variety of tools to capture and record sound waves that are transmitted by natural gas. Computer software included in the package analyzes and interprets the recorded signals to detect possible leaks. Natural gas compressor stations, which pump gas from one station to another, have a distinct sound, as does natural gas flowing normally through fittings and valves. Variations to these and other background sounds alert operators that a leak may exist.
The PAMP system interests the natural gas transportation industry because it could enable companies to spot leaks faster than they do now, and it may be useful in preventive maintenance. It could also detect "third party" damage. Operators using a back hoe to perform pipeline maintenance, for example, may dig deep enough to strike a pipe, carrying sound waves within the pipe to a PAMP unit. Alerted pipeline operators would be able to locate the source of the sound waves and the pipeline intrusion.
For the field test, two PAMP units were attached aboveground to a 12-inch pipeline operating at a pressure of 200 pounds per square inch. Both units were able to detect simulated strikes on the pipe and leaks in real time. The two units were able to pick up sound anomalies when a 1 inch steel ball was dropped 1 inch above the pipeline approximately a half a mile away. Location of leaks can be determined by measuring the time difference as a signal arrives at two PAMP units.
The PAMP prototype is rugged and versatile, and it costs less than $1,000. In addition, it can be connected to any pipe through a half-inch-wide fitting at operating pressures up to 1,000 pounds per square inch.
West Virginia University is now working on categorizing background sounds of natural gas pipelines. The university is also developing a sound generator to pull out real signals above the background noise of the pipe to determine how sensitive it is in pinpointing leaks.
The Energy Department funds the development of PAMP and similar remote sensing technologies through NETL's Natural Gas Delivery, Storage, and LNG Program. The program goal is to ensure reliable, efficient, and safe delivery of increasing volumes of natural gas.
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