MINIMIZATION OF NO EMISSIONS FROM MULTI-BURNER COAL-FIRED BOILERS

[摘要] Reduction of NO{sub x} emission is an important environmental issue in pulverized coal combustion. Final emissions of NO{sub x} are strongly affected by the nitrogen release during devolatilization, which is the first stage of coal combustion. The most cost-effective approach to NO{sub x} reduction is air-staging which can also operate with additional down-stream techniques such as reburning [1]. Air staging promotes the conversion of NO{sub x} precursors (HCN, NH{sub 3}, etc.) to N{sub 2} by delaying the oxygen supply to the greatest extent when those nitrogen species are released during devolatilization. Such a delay gives the primary volatiles a chance to undergo secondary reactions, including tar cracking and soot formation. Secondary reactions of volatiles largely determine the fate of the ultimate NO{sub x} production from pyrolysis, therefore a detailed investigation into the transformation of nitrogen species during secondary reactions and effects of soot on nitrogen release is critical for design and implementation of new pollution control strategies. Current nitrogen models (including the CPD model at BYU) only simulate the nitrogen release during primary pyrolysis, which happens at low temperatures. This project helps to build a nitrogen release model that accounts for secondary reactions and the effects of soot at temperatures relevant to industrial burners.

[发布日期] 2000-04-01 [发布机构] National Energy Technology Laboratory (U.S.)

[关键词] Nitrogen Oxides;Boilers;Burners;01 Coal, Lignite, And Peat;Pyrolysis