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Microwave Process for NOx Abatement

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Meeting abstract 1 Mar 1997-21 Dec 1999

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The CHA Corporation has completed an U.S. Air Force Phase II Small Business Innovation Research program to investigate the feasibility of using a novel microwave-based filter device to remove and destroy unwanted by-products of combustion in exhaust gases. A Corning ceramic monolith soot filter that has about 90 soot removal efficiency was placed in a housing that allowed for microwave regeneration. Two filters were installed in parallel into the exhaust piping of a diesel engine. After 4-hour periods of operation, the filters were successfully regenerated with microwave energy for over 50 cycles. A prototype device for the destruction of NOx in exhaust gas generated by a 58- hp diesel engine was constructed and tested. The NOx control device comprised two separate fixed-bed reactors filled with catalyst beads. In the first, a PtPd catalyst was used to convert NO into NO2 in the diesel exhaust. A reducing agent JP-8 and microwaves were supplied to the second reactor, containing alumina-SiC pellets coated with a PtRhPd catalyst, to destroy NO2. Because NO oxidation efficiency 45-55 is suppressed by the high concentration of water in diesel engine exhaust, NOx destruction efficiencies were 30-40, 10-20 lower than the NOx destruction obtained from smaller reactors. Test results obtained for this prototype microwave device clearly identified technical and economic advantages as well as technical difficulties of applying microwave-based filter devices to control pollutants in diesel exhaust. Preliminary experimental data indicate that the microwave reactor system developed for NOx destruction can be used to destroy waste rocket fuels including hydrazine and unsymmetric dimethylhydrazine in nitrogen or air streams. Laboratory and prototype test results will be presented.

Subject Categories:

  • Combustion and Ignition
  • Reciprocating and Rotating Engines
  • Air Pollution and Control

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