PURPOSE: To enable to use as the fuel of a boiler coal containing high iron content without the occurrence of slagging, by a method wherein burners at plural stages are installed, coal containing high iron content is fed to the burner at a lowermost stage, and the burner at the uppermost stage takes the form of a denitrificating burner.
CONSTITUTION: Burners 2, 3 and 4, positioned at the lower part of a boiler furnance 1, are aligned in 3 stages, the burners 2 at a lower stage and the burner 3 at a middle stage form a main burner, and the burner 4 at an upper stage forms a denitrating burner. Coal containing high iron content contained in a banker 5 is the coal which has the amount of iron in ash being 10% or more in consideration of the softening and the melting temperature of coal ash. Coal containing high iron content, pulverized by a mill 7, is fed to the burner at the lowermost stage through a fuel pipe 13 by an air fan 12 to charge it into the furnace 1. In the burner 2 at the lowermost stage, an air ratio is set to 1.0 to form an oxidizing atmosphere. Thus, ash content is prevented from softening and melting as in a reducing atmosphere. Meanwhile, in the burner 4 at the upper stage, an air ratio is set to 0.8 or less, whereby a reducing atmosphere is produced and a boiler is capable of achieving low NOX combustion.
MASAI TADAHISA
MIGAKI HITOSHI
MORITA SHIGEKI
ITAGAKI KIICHI
NAKASHITA SHIGETO
