Effect of Catalysts on the NO Reduction During the Returning with Coal Chars as the Fuel

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Abstract
This paper studies the reduction of NO in rebuming zone using three different Chinese chars (Xiao-longtan lignite char. Fulaerki lignite char and Datong bituminous char) as the reburning fuels. At first, the effect of metal oxides contained in char ashes on the NO reduction is investigated. Then the NO reduction rates of the Datong bituminous char impregnated in different catalyst solutions are investigated and are compared with the case without impregnation. Experiments were conducted under conditions with initial NO concentration of 1,000 ppm and reaction temperatures of 900°C and 1100 °C. Experimental results show that the metal oxides contained in the char ashes affect strongly the NO reduction in the reburning zone. The NO reduction rate of the bituminous chars can be enhanced appreciably after being added some cheap catalysts. The added catalysts can reduce the activation energy of the heterogeneous NO reduction reaction and thus increase the rate of the reduction reaction under conditions with appropriate temperatures and stoichiometric ratios.