| 摘要 |
PURPOSE:To reduce the effect of after air, and to obtain a combustion method reducing NOx without increasing CO and smoke dust in exhaust gas by providing a front section in a furnace with each burner at a lower stage, an intermediate stage and an upper stage and sections higher than the front section with front and rear after air ports and specifying the air ratios of each burner at the lower stage, the intermediate stage and the higher stage. CONSTITUTION:The front after air port 11 is arranged at a section higher than the rear after air port 12. The air ratio of the lower-stage burner 2 is made to reach 0.8-1.0, the air ratio of the intermediate-stage burner 3 to 0.6-0.8 and the air ratio of the lower-stage burner 4 to 0.4-0.6 as the conditions of combustion. The lower-stage burner 2 and the intermediate-stage burner 3 are burnt under approximately the same conditions of combustion as a conventional stage combustion method at that time, but the air ratio of the upper-stage burner 4 is reduced remarkably up to 0.4-0.6, and intermediate products in a combustion reaction are increased. Accordingly, flames generated by the lower-stage and intermediate-stage burners 2, 3 and a flame generated by the higher-stage burner 4 are mixed sufficiently because nitrogen oxide generated by the lower-stage and intermediate-stage burners is reduced by radicals generated by the higher- stage burner. |
