Effect of Co-combustion of Multiple Additives with Coal on NO Removal

Denitrification experiments of co-combustion of coal and additives were carried out in a horizontal tube furnace. The results showed that calcium acetate limited the production of NO₂. The optimum calcination temperature of CTAB-Zr-TiO₂ was 673 K. The denitrification efficiency reached up to 72.27%, and desulfurization efficiency reached 83.03% when corncob, calcium acetate, and CTAB-Zr-TiO₂ were added. Corncob, calcium acetate, and CTAB-Zr-TiO₂ all promoted coal combustion. The specific surface area of CTAB-Zr-TiO₂ (55.50 m²/g) was the largest, which was more than 4.5 times that of pure TiO₂ (12.20 m²/g). The denitrification process in the co-combustion of coal with multiple additives included a homogeneous reaction and heterogeneous reaction. The homogeneous reaction was that NO and NO₂ were reduced to N₂ by reducing gases produced in combustion. The heterogeneous reaction involved the reduction of NO and NO₂ by coal char. The additives increased the specific surface area of the coal char and enhanced the activity of the heterogeneous reduction of NO and NO₂. At the same time, the catalysis of alkali metal oxides in corncob and CTAB-Zr-TiO₂ promoted the heterogeneous reduction of NO and NO₂ by the coal char.