| 摘要 |
PURPOSE:To reduce NOx to harmless N2 by a method in which the lowest burner among burners set on the upper and lower parts of the grating of a combustor is taken as the burner where fuel is excessively supplied and nitrogenous compounds generated from the burner are used as reducing agents. CONSTITUTION:Plural burners are vertically set in the grating 1 of a boiler as a combustor, and a reducing burner 4 is set at the lower part of the upper three- stage burners as the main burner. On the upper furnace wall of these burners, an NO boat 2 is formed where two-stage combustion is made. In the reducing burner 4, the air ratio is set to 0.7 or less, that is where a strongly reducing combustion is made under an extremely excessive fuel supply condition with an average 17% or less oxygen concentration in all air amount to be supplied. Since highly reductive intermediate products are formed by nitrogen in fuels, NOx in the combustion gas of the main burner can be reduced to N2. |
