1987•OSTI OAI (U.S. Department of Energy Office of Scientific and Technical Information)Requires access
NO/sub x/ and SO/sub x/ removal in a high sulfur spray dryer system
Paul S. Farber, Haizhou Huang, J.W. Allen
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Abstract
Potential acid-deposition legislation is likely to call for extensive reductions of sulfur dioxide (SO/sub 2/) emissions in the midwestern United States. These reductions will be aimed primarily at the older utility power plants that operate without scrubbers. A study by Argonne National Laboratory (ANL) has indicated that at least 25 plants in Illinois, Indiana, and Ohio would be affected by this legislation. If fuel switching is one of the allowable options under whatever legislation is mandated, the impact on the midwestern coal industry will be enormous, with dozens of mines being forced to close. There is also a growing realization that the role of nitrogen oxides (NO/sub x/), although not as critical as that of sulfur oxides (SO/sub x/), has to be included in any acid-deposition control scenario. The development of environmental control processes for the simultaneous control of NO/sub x/ and SO/sub x/ is one of the national priorities being pursued by the US Department of Energy. The specific effort to develop combined SO/sub x//NO/sub x/ control technology in spray dryers is centered around laboratory and field efforts at ANL. It has been found that a combination of modified process conditions and addition of caustic soda to the lime-basedmore » spray dryer system allowed for removal of some of the nitrogen oxides from the flue gases, with some increases in the sorbent ratio necessary for the system to maintain its ability to remove sulfur dioxide. The existence of a temperature ''window'' that is ideal for NO/sub x/ removal could not be verified during the field tests, primarily due to an upper limit of 210 to 215/sup 0/F in the tests. A distinct relationship (above 190/sup 0/F) between the equivalence (defined as the chemical combining capacity) ratio of the reactants and the pollutants, the thickness of the filter cake, and the ratio of sulfur oxides to nitrogen oxides at the system entrance was found for the removal of NO/sub x/ pollutants.« less