A system for removing pollutants — primarily sulfur dioxide and mixed oxides of nitrogen (NOx) — from incinerator exhaust has been demonstrated. The system is also designed secondarily to remove particles, hydrocarbons, and CO. The system is intended for use in an enclosed environment, for which a prior NOx-and-SO2-removal system designed for industrial settings would not be suitable. The incinerator exhaust first encounters a cyclone separator, a primary heat exchanger, and a fabric filter that, together, remove particles and reduce the temperature to 500 °C. The exhaust then passes through a porous bed, maintained at ≈ 450 °C, that contains Na2CO3, which absorbs SO2.
Next, a commercial catalyst maintained at 400 °C accelerates the oxidation of the carbon in hydrocarbons to CO and CO2. A heat exchanger then cools the exhaust to ≈ 300 °C before passage over a catalyst that causes 95 percent of the NO to be oxidized to NO2. The first of two water scrubbers removes most of the NO2, which is converted to KNO3 and KNO2. The second water scrubber contains sodium bisulfite, which, with an aminophenol catalyst, converts most of the remaining NO2 to N2.
This work was done by David T. Wickham, James Bahr, Rita Dubovik, Steven C. Gebhard, and Jeffrey Lind of TDA Research, Inc. for Johnson Space Center. For further information, contact the JSC Innovative Partnerships Office at (281) 483-3809.
In accordance with Public Law 96-517, the contractor has elected to retain title to this invention. Inquiries concerning rights for its commercial use should be addressed to:
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Refer to MSC-23440-1, volume and number of this NASA Tech Briefs issue, and the page number.