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IMSS Detects Methane Leaks
Infrared Imaging Spectroscopy used to visualize hydrocarbon gas leaks

April 13, 2000

Because of the limitations of traditional leak detection instruments and due to the Clean Air Act amendments, there is renewed interest in the development of reliable, cost-effective detection and monitoring methods with enhanced capabilities. New state-of-the-art optical remote sensing technologies that have been developed for the Department of Defense (DoD) for military applications can be applied to meet these requirements. These new optical Infrared remote monitoring and image processing technologies are reliable, robust, and can provide a low cost, hand held imaging camera that can be applied to the leak detection and measurement problem for industry and the government.

By remotely imaging the leaks, the problem of accessibility is greatly reduced since an operator can view an image of the leaks from a distance.Under contract to the Department of Defense (DoD), Pacific Advanced Technology (PAT) has developed a field portable infrared imaging spectrometer (Image Multi-Spectral Sensing or IMSS) for numerous defense related applications.These include detection and warning targets such as missile plumes and chemical warfare agents. Key to this new detection methodology is a patented (US Patent Number 5,479,258) diffractive optical system, and new state of the art image processing technology. Recent breakthroughs in Digital Signal Processors (DSP) and Field Programmable Gate Arrays (FPGA) permit these sophisticated image processing techniques developed for the military to be applied in real-time to display fugitive gas leaks to the operator in real-time.

PAT has analyzed and successfully tested this new IMSS technology for environmental monitoring and gas leak detection applications. The IMSS instrument is small, rugged, sensitive and suitable for a wide variety of remote monitoring applications such as: fugitive gas leak detection, smoke stack emissions monitoring, flare monitoring, etc.

The IMSS has demonstrated that it can measure target spectral signatures consisting of multiple species simultaneously, and it can handle the effects of atmospheric absorption and scattering. The IMSS technology is ideal to be applied to monitoring of toxic metal and/or organic compound emissions from high temperature complex matrix sources such as incinerators, fossil fuel based power plants, and flares. It also can be applied to monitoring of released gases from complex point sources or area sources including tanks, pipes, valves, vents, etc. A key advantage of this technology is that it does not need artificial illumination sources such as a laser; only natural ambient illumination is required to image and analyze the gases or flames. In addition to providing an image, the IMSS is an imaging spectrometer that also provides a spectrum of any element in the image to identify species.

Test Results

PAT recently completed a Phase I STTR study for the Department of Energy to address the viability of this state of the art technology for detection and analysis of greenhouse gases such as methane. PAT's Phase I test results were highly successful. The goal was to detect and measure methane leaks as small as 1 cu.ft./min. This objective was achieved, and leaks as small as 0.01 cubic feet per minute were successfully imaged in ambient conditions, using both a building and also the sky as a background. This result significantly exceeded the goal by more than an order of magnitude. Imaging the leak with a sky background (from a roof vent) is particularly important since PAT was informed that roof vent gas leaks are particularly costly to detect with current instrumentation. Shown in figure 1, is the test setup using the PAT lab model IMSS I Infrared Imaging Spectrometer, and " vent pipe leaking 0.47 cu.ft./min. methane gas. Shown in figure 2 is the IMSS image of the leak processed to paint the leak in false color as it would be presented to the operator.

In addition, data was collected from a methane gas leak from a inch tube that was buried under ground at a depth of 12 inches. These underground methane leaks were also successfully imaged with the IMSS laboratory instrument. This is a significant achievement, and holds considerable promise for a low cost way to image leaks from the over 1 million miles of underground pipeline in the natural gas production, distribution and transmission systems in the U.S.

This technology holds much promise for significantly reducing the release of greenhouse gases as well as saving the industry significant costs in both labor and lost resources.

 
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