PURPOSE: To reduce unburnt portion and NOx even if pulverized coals having different fuel ratios are burnt simultaneously, by a method wherein a burner is provided with a pulverized coal feed passage at least on the innermost side of the burner and with an additional pulverized coal feed passage outside the innermost pulverized coal feed passage.
CONSTITUTION: A burner throat 2 is formed on the wall of a furnace 1. Pulverized coal feed passages 4, 6 and air feed passages 3, 5 are provided on a concentric circle at the opening of the burner throat 2. Pulverized coal (low fuel ratio pulverized coal) which is low in the composition proportion of fixed carbon contents with respect to a volatile matter is fed to the innermost side pulverized coal feed passage 6 from the outside pulverized coal feed passage 4 to form a reducing flame in the furnace 1 and, on the other hand, pulverized coal (high fuel ratio pulverized coal) which is high in the composition proportion of fixed carbon contents with respect to volatile matter is fed to the outside pulverized coal feed passage 4 from the innermost side pulverized coal feed passage 6 to form an oxidizing flame in the furnace 1. The high fuel ratio pulverized coal is burnt at high speed due to sufficient air supply to decrease an unburnt portion, and NOx generated is decomposed by the reducing gas generated in the fuel region of the low fuel ratio pulverized coal, whereby NOx is reduced.
MASAI TADAHISA
UEMURA TOSHIO
MIGAKI HITOSHI
ITAGAKI KIICHI
KODA FUMIO
