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Microwave Treatment of Oxidizer Vapor

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Proceedings May 2001-May 2002

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During fueling of liquid rockets, transfer of the propellant, hydrazine and its monomethyl and 1,2-dimethyl derivatives, and of the oxidizer, dinitrogen tetraoxide N2O4 creates exhaust streams of nitrogen gas heavily contaminated with these constituents. Wet scrubbers provide -60 removal of these contaminants, and combustion devices emit unacceptable amounts of NOx as byproducts of treatment. The Air Force Research Laboratory, Weapon Systems Logistics Branch AFRLMLQL has developed a systematic assessment of needs for pollution prevention research within the space segment of Air Force activities. The MLQL team has identified development of a Toxic Propellant Vapor Treatment process to improve on current scrubber technology for treatment of this exhaust as one of two specific, high-priority needs of common concern to several locations. Toward that goal, CHA Corporation is conducting a staged development effort leading to a field demonstration of a full-scale microwave reactor system to decompose both N2O4 vapors and hydrazine vapors in SEPARATE nitrogen gas streams. We expect to carry the development through to deployment as an operational technology. During phase 1, we completed design optimization experiments and assembled a 5-lO-scfin prototype reactor system. Efficient reduction of NOx formed by dissociation of N2O4 is realized by passage through a bed of carbon during microwave irradiation. To extend the lifetime of the carbon bed, which is consumed as a reductant in this process, we introduced a slight stoichiometric excess of alcohol upstream of the bed. This approach achieves consistent 99 reduction of net NOx species over a range of irradiation power levels and residence times.

Subject Categories:

  • Inorganic Chemistry
  • Air Pollution and Control

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