| 摘要 |
The present invention relates to methods for selectively reducing NOx so that nitrogen can be removed from emission effluent streams and NOx emissions can be reduced to very low levels. In addition, the present invention teaches a method whereby NOx and SOx may be simultaneously removed from the effluent stream. The present invention teaches the reduction of NOx with cyanuric acid. Initially, cyanuric acid is decomposed to form decomposition products. The reaction of cyanuric acid to produce its decomposition products, such as isocyanic acid or related reaction intermediates, takes place in an oxygen-free, fuel rich, decomposition zone with the reaction temperature in the range of from about 1000 DEG F. to about 3000 DEG F. After the cyanuric acid is decomposed in the absence of oxygen, the decomposition stream is mixed with the effluent stream containing NOx. At this point the oxygen level of the stream must be carefully controlled to provide an excess of oxygen. It may be necessary at this point to inject air into the effluent stream in order to maintain the proper oxygen-rich (fuel-lean) conditions for NOx reduction. In the second "reaction zone," reduction takes place at temperatures of from approximately 1200 DEG F. to approximately 2600 DEG F. The present invention can also be combined with SOx control technology. Specifically, species used to control SOx, such as limestone, dolomite, quicklime, and hydrated lime, can be added to the cyanuric acid for injection into the effluent stream. Thus, simultaneous NOx and SOx control can be achieved.
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