科研之友
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摘要
To study the effect of NH3 on nitrogen oxides (NOx) formation and reduction in a fuel-rich zone during pulverized coal combustion, the reaction properties of urea solution with NOx have been investigated using a drop-tube furnace system. The results indicate that NOx could be reduced by urea solution effectively in a fuel-rich zone, when the temperatures are in the range of 1200-1400 degrees C. The lower stoichiometric ratio (SR) in the combustion zone makes NOx reduction more effective by the injection of urea solution. High normalized stoichiometric ratio (NSR) results in a high percentage of NOx reduction under strong reducing atmosphere conditions. The maximum NOx reduction efficiency can reach up to 94.1%, of which 13.4% is achieved by injecting urea solution in the fuel-rich zone. The concentration of NOx emission decreased with the increase of quantity of water. However, the extent of decrease was inconspicuous.
