| 摘要 |
PURPOSE:To increase a velocity of flow of air and to perform enough mixture of furnace gas and auxiliary air (OFA) by a method wherein a part of air for conveying pulverized coal is branched from a mill inlet to take it out and the air is fed in a furnace through an overfire air port above a burner. CONSTITUTION:Combustion air boosted by an FDF 1 is branched at the inlet part of an air preheater 2 into two ways. After the temperature of the one secondary air is increased by means of the air preheater 2, it is introduced in a furnace 7 through a burner part 3 and fed for combustion of pulverized coal. After the other combustion air is further boosted by means a PAF 5, the temperature thereof is increased by means of the air preheater 2 and fed to a mill 6 where coal is pulverized. The combustion air is introduced, in a state to be mixed with pulverized coal, as primary air to the furnace 7 through the burner part 3. Further, a line 9 branched from a point B located after the air preheater 2 of a primary air duct 8 and before the mill 6 is provided and connected to an OFA port 4b formed above the burner part 3 of the furnace 7. A sufficiently high velocity of flow is ensured for air introduced in the furnace through the OFA port 4b, mixture of furnace gas and OFA is promoted to reduce production of an unburnt content, and gas concentration in the furnace is uniformized. |
