Injection nozzle for ultraviolet light-enhanced H2O2 oxidation of air pollutants in flue gas
Abbreviated Journal Title
J. Environ. Eng.-ASCE
oxidation; gasoline; air pollution; pollutants; HYDROGEN-PEROXIDE; EMISSIONS; Engineering, Environmental; Engineering, Civil; Environmental Sciences
Injecting aqueous solutions of hydrogen peroxide (H2O2) into hot flue gases can split the peroxide into OH and HO2 radicals. These reactive radicals readily oxidize air pollutants such as CO, VOCs, NO, mercury, and others. H2O2 is thermally "activated" (split into free radicals) rapidly at temperatures of 500degreesC and above. At lower temperatures, such as found in boiler exhaust flue gases, ultraviolet (UV) light can be used to activate the peroxide molecules. However, placing the UV lamps directly in the flue gases can lead to operating and maintenance problems, and "dilutes" the UV energy due to absorption by other gases. A "UV nozzle" has been developed that produces H2O2 radicals and delivers them into a flowing stream of boiler flue gases. Using a previously constructed pilot scale system at NASA's Kennedy Space Center, experiments were run to prove the concept of the nozzle, measuring the oxidation of NO as an indicator of radical formation and delivery. Data were taken at three temperatures, with none, one, or two UV lamps on, and with various injection rates of peroxide. Flue gas temperatures ranged from 85 to 304degreesC (186 to 580degreesF), and the molar ratios (inlet peroxide to inlet NO,) ranged from about 1.5 to over 15. Conversions of NO varied from 0% (at the lowest temperature tested) to above 50% (at highest temperature). Although increasing temperature had a marked effect on conversion, the activation of hydrogen peroxide by UV light was demonstrated in the temperature range of final flue gas exhaust gases (290-350degreesF). These results indicate that radicals can be created from hydrogen peroxide at reasonable temperatures using UV light, and that the radicals can be delivered into a flue gas stream where they can oxidize pollutants.
Journal of Environmental Engineering-Asce
"Injection nozzle for ultraviolet light-enhanced H2O2 oxidation of air pollutants in flue gas" (2002). Faculty Bibliography 2000s. 3135.