SELF-DENITRIFICATION BEHAVIOR OF BIOBRIQUETTE ADDED WITH PULP BLACK LIQUID

The characteristics of self-denitrification in biobriquettes are studi ed experimentally. To enhance effective utilization of low-grade coals , and to control emission of environmental pollutants from combustion, a new artificial solid fuel, a biobriquette with a self-denitrificati on function, is developed. It was produced by the mixture of low-grade coal, cornstalk as biomass and pulp black liquid as denitrificazer un der a high compression pressure condition. Both experiments of pyrolys is and combustion were performed in order to reveal the mechanism of n itrogen-oxide formation and denitrification of the biobriquette.It is found that the release fraction of fuel-N is raised with increasing py rolysis temperature in both coal and biomass. The release fraction of fuel-N in biomass is much higher than coal at the same pyrolysis tempe rature. The conversion fraction of fuel-N to NO slightly ascends and t he fraction to N2O slowly descends with increasing furnace temperature , but the sum of conversion fraction of fuel-N to NO and N2O appears t o be independent of furnace temperature. The denitrification process o f the biobriquette with the pulp black liquid appears to proceed as tw o stages, namely the volatile combustion stage and the char combustion stage. Denitrification mainly happens in the char combustion stage. A denitrification efficiency of 40% can be obtained in the biobriquette combustion with a pulp black liquid of 10 mass%. Finally, it is confi rmed for the first time that the pulp black liquid has significant den itrification capabilities in the biobriquette combustion.