IR cameras: The new tool for emission leak detection
Since the beginning of the industrial age, the world has used natural resources to enable manufacturing and production. The use of gases, and the chemicals that produce them, have been pivotal in this evolution. Unfortunately, the majority of the gases used by industry are radiatively insulating in the infrared %%MDASSML%% in other words, greenhouse gases.
The IR camera allows users to visually discern a gas in its host atmosphere. With an IR imager, one can “see” where the gas is originating, as well as where the gas cloud is traveling. One can immediately recognize the health and safety impact of this tool and the environmental implications. From first detection to eventual gas containment and even remediation, the benefits of applying this technique are vast.
On December 15, 2008, the U.S. Environmental Protection Agency issued a final amendment to its leak detection and repair requirements, “allowing the use of optical gas imaging technology to locate emission leaks. The leaks are displayed on a video screen similar to the way night vision goggles are used to show the heat signature of objects. This amendment provides requirements for using the new technology; however, facilities may continue to use existing approved work practices to detect leaks,” the EPA said in a statement at www.epa.gov .
How it works
Greenhouse gases absorb infrared light; this is what makes them greenhouse gases in the first place. The gas restricts or insulates the IR radiation from passage through the atmosphere, retaining the thermal energy inherent in the radiation. As a consequence, the air warms up and shields the earth from effectively cooling itself.
Optical gas imaging grew from military applications. Now the practice of using infrared cameras to detect gases has permeated into the commercial domain. Whether it’s making sure precooked dinners reach the right temperature for food safety or maintaining power stations and plants, the IR camera has become an essential tool because of the cost savings, safety and environmental benefits it provides.
Gases to watch
IR cameras designed for gas detection are used by government, industrial safety hygienists and maintenance professionals. Many of the components and leaking gear found are not listed as potential emission sources, yet their existence is real.
Three families of greenhouse gases require examination: Methane (CH4); sulfur hexafluoride (SF6); hydro chloro/per fluorocarbons (HFCs); and carbon monoxide (CO).
Methane is a naturally occurring gas generated from the degradation of biomass. Methane concentrations have increased 150% since the industrial revolution.
Methane emissions in the U.S. result primarily from landfills and gas distribution systems, accounting for nearly 45% of total man-made emissions, according to the EPA. In 2002, the EPA estimated 2% of the methane drawn from wells in the U.S. leaked into the atmosphere before being burned by the end user. The American Gas Association estimated U.S. methane loss in 2006 was nearly $3 billion.
Sulfur hexafluoride has the highest GWP ever measured at 23,900, according to the Intergovernmental Panel on Climate Change . This means that it takes 23,900 grams of carbon dioxide to have the same greenhouse impact as 1 gram of sulfur hexafluoride. Sulfur hexafluoride is used primarily in electricity transmittance and semiconductor fabrication, however, according to an EPA report, most of it is believed to be emitted into the atmosphere. Based on the GWP of sulfur hexafluoride, this emission is equivalent to the CO 2 emission of 34 million automobiles annually. Most HFC species emissions are not regulated; neither is sulfur hexafluoride emission.
Carbon monoxide is an indirect greenhouse gas that is toxic and highly flammable. It poses a significant health and safety risk. IR camera technology can spot carbon monoxide emissions as low as 90 pap, well below the flammable threshold. A wide variety of carbon monoxide point monitors exist, however, they only sample the air at the monitoring inlet. If the monitoring device is not within the carbon monoxide vapor cloud, then it cannot detect the presence of the gas.
A practical technology
IR imaging is the best solution compared to the other methods for emission detection. Earlier technology and methods have relied on point contact sensors that “sniff” the air that happens to be passing near them at any given instant in time. An infrared camera displays a real-time visual image of gas and allows trained professionals to instantly analyze where and how much gas is being emitted.
Adopting, deploying, and mandating the use of IR technology will help make a real difference in the environment. Eliminating the equivalent carbon footprint of 34 million autos could be accomplished by regulating sulfur hexafluoride emissions and mandating leak surveys with this technology, an EPA report suggested. Saving $3 billion in annual methane emissions from leaking distribution systems could bolster the companies that service this sector and help reduce rising methane levels.
|R.G. Benson is a research scientist and serves as technical manager of vapor imaging for Flir Systems Inc.|