Southwest Research Institute^® (SwRI^®)  News

SwRI nonthermal plasma reactor neutralizes harmful emissions

SwRI engineers are exploring the use of an Institute-developed nonthermal plasma reactor to efficiently neutralize harmful elements in industrial and automotive emissions.

San Antonio — November 20, 1995 — For years, there have been serious concerns about the impact of air pollution on the environment. Pollutants created by power generation, industrial processes, and transportation have led to such problems as smog and acid rain and can contribute to potential global warming mechanisms. Southwest Research Institute^® (SwRI^®)  engineers are developing a new technology that breaks environmentally harmful air pollutants into less harmful constituents. Called a nonthermal plasma reactor, the technology has the potential to neutralize oxides of nitrogen (NOx), oxides of sulphur, particulate matter (PM), volatile organic compounds, and chemical and biological agents.

Dr. Michael Grothaus, senior research engineer in the Automation and Data Systems Division, reported progress on nonthermal plasma technology at SwRI’s 48th Annual Trustees Meeting November 20. He expects the technology to become increasingly important in future years. “Perhaps its biggest advantage is that it’s a cost saver over traditional thermal methods like incineration because it uses much less energy. It also promises to be more generic and less susceptible to poisoning than dry scrubbers.”

Using a nonthermal plasma to reduce harmful gaseous pollutants is a relatively new research area. Grothaus explained that a nonthermal plasma, such as that created in the SwRI pulsed corona reactor, adds a minimal amount of energy to a gas in a way that favors the production of high-energy electrons, while at the same time leaving the more massive ions which are formed at comparatively lower energies. The high-energy electrons collide with the background gas molecules, creating chemically active species called “radicals.” These radicals can react preferentially with the pollutant molecule species, breaking them into less hazardous compounds. These reactions take place without a significant increase in the background gas temperature, which translates into a substantial energy savings when compared with thermal methods.

Although this research started as an SwRI internal research program in collaboration with researchers at the Dahlgren Division of the Naval Surface Warfare Center, a related cooperative program funded by Caterpillar, Inc., Equipements Et Composants Pour L’Industrie Automobile (ECIA), and Renault VI-DITCM ERM/Mack Truck, Inc. will further research plasma’s effectiveness in reducing NOx and PM from diesel emissions. E. Robert Fanick, senior research scientist in the Automotive Products and Emissions Research Division, is heading that program.

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