| 摘要 |
PURPOSE:To improve ignition and to increase combustion efficiency of coal at the time of extremely low loading in a boiler, by dividing the grain of pulverized coal into smaller size in a secondary combustion line of a pulverized coal combustion boiler. CONSTITUTION:In a primary combustion line 90, a coal 53 in a coal hopper 54 is fed to a mill 50 by a coal feeder 52 through a feed pipe 56. In the mill 50, the coal is finely pulverized in such a manner that its grain size is 200 mesh and its passing rate is 70-80%. The coal is conveyed through a feed pipe 58, and is injected into a furnace 12 to be burned from a pulverized coal burner 82 via a distributor 80. In a secondary combustion line 100, a coal 33 in a coal hopper 34 is fed to a mill 30 by a coal feeder 32 through a feed pipe 36. In the mill 30, the coal is pulverized in such a manner that its grain size is 200 mesh and its passing rate is 80-90%. At the time of extremely low loading in a boiler, a secondary pulverized coal feed pipe 40 and a feed pipe 48 are opened respectively, and the pulverized coal is controlled to pass through the above-mentioned two pipelines juxtaposedly, while part of coal which is conveyed through a bypass line is joined again to the coal feed line 40 at its downstream side. The coal is injected into the furnace 12 to be burned from a secondary pulverized coal burner 46 via a distributor 42. In such a manner, a boiler is prevented from stopping even if a secondary mill 30 is suddenly stopped in an emergency.
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