| 摘要 |
PURPOSE:To decrease the generation of NOx, by sucking unburnt coal collected in an emission passage of exhaust gas by ejectors provided in the middle of pipelines to feed air to a burner,and by feeding the coal to the burner together with air to be burned in a freeboard zone. CONSTITUTION:Part of pulverized coal being fed into a boiler 1 from a small coal injection nozzle 7 passes through a flue 10 together with combustion exhaust gas, not being burned, and is collected by recesses 14 a cyclone 11. The collected small coal is fed to a burner 15 together with air by the effect of combustion air flowing through an auxiliary air feed pipe 20, interposed by ejectors 21 and 22, respectively, and is burned by the burner in a freeboard zone 16. Because the unburnt small coal is burned in the freeboard zone, the amount of primary combustion air to be fed into a plenum chamber is smaller than the case of unburnt content to be returned to the fluidized bed as conventional cases. Accordingly generation of NOx can be decreased, and it is further reduced because unburnt small coal can be burned in the freeboard zone. |
