Lights up on emissions monitoring

This article takes a new look at optical remote sensing (ORS) technology — which has become simpler, more reliable and more accurate, yet its popularity for monitoring emissions has not grown.

By Nick Basta

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According to Minnich and his partner, Robert Scotto, his company and others have been doing such site assessments for years, and have proved the technology. But it is not required for site remediation, and managers of such projects are leaving themselves open to liability threats by not employing the technology more routinely. The same holds true for many industrial applications. Companies could perform comprehensive, ongoing monitoring of their facilities, but only do so when required by a state or local regulatory authority. “We’;ve heard that some insurance companies will consider reducing liability premiums if this technology is in place, so it can literally pay for itself,” Minnich says.

Minnich and others point to the situation in Europe, where ORS technology has been applied at numerous industrial sites and where regulatory authorities require ongoing monitoring of emissions, especially near communities.

Opsis AB, Furuland, Sweden, which was founded in 1985, is a leading developer of ORS technology, called differential optical absorption spectroscopy (DOAS), which uses a range of light wavelengths and a variety of spectroscopic techniques in one unit. The European ORS scene is benefiting from a European Union effort to standardize technologies and performance specifications for ORS equipment. The lead contractor in this effort is Sira Technology Ltd., Chislehurst, England, which is managing the remote optical sensing evaluation (ROSE) program. The company is testing both types of ORS equipment and suitable applications.

U.S.-based technology development is also moving ahead. Arcadis’; Hashmonay has taken research developed at the University of Washington and, with EPA sponsorship, has developed a technology called radial plume mapping (RPM). With this technique, one ORS system can take readings along multiple paths that have a mirror at the far end of the measuring range. With a suitable tower in the vicinity, readings along different heights can also be taken. With software developed by Arcadis, a 3-D map of a plume can be produced. Hashmonay, who is also chair of the Optical Remote Sensing Division of the Air and Waste Management Association, says the technology could provide multiple benefits for leak detection, routine monitoring or site remediation for industry. “The problem with many industrial sites is that the monitors are only located where emissions are suspected; if you’;re not monitoring the entire facility, you don’;t know about unpredicted leaks or emissions,” he says.

Robert Spellicy, president of the Industrial Monitor and Control Corp., Round Rock, Texas, is pursuing work in monitoring flare systems at chemical and refining sites. Preliminary studies have shown that flares sometimes emit VOCs when not properly operated. For example, steam is injected into the flare to control soot generation, but too much steam will lower the efficiency and cause only a fraction of the gases to combust. The first phase of a study was performed last year in cooperation with URS Corp., San Francisco, and John Zink, Tulsa, Okla., but additional studies are needed to fully develop the flare application. One of the inherent advantages of ORS in this application, Spellicy says, is that it depends on the spectral emissions of the burning gases in the flare themselves; an IR or other light emitter is not needed. This allows for totally remote measurement.

A relatively new entrant on the ORS scene is Avir Remote Sensing, Charlotteville, Va., which is commercializing technology developed at the University of Virginia, in combination with U.S. Department of Defense support. The technique, called differential absorption radiometry, is a passive technique, using a receiver to sense spectral emissions by chemical agents in an area. The company is proposing its technology as a resource for first responders and homeland security applications.

Nick Basta is editor at large for Chemical Processing magazine. E-mail him at nbasta@putman.net.

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