| 摘要 |
PURPOSE:To lower the rate of NOx in exhaust gas, by forming a combustion zone for the secondary air around a low O2 combustion zone for the primary air, and by forming a reducing intermediate compound by heightening the temperature in the primary combustion zone by combustion heat by the air for the secondary combustion. CONSTITUTION:Pulverized coal as a fuel is injected into a furnace with the primary air 1, and is burned with the air in low O2 in the primary combustion zone 11. The secondary air 3 is injected from annularly arranged secondary pores 4 provided around the primary air port 2 so as to encircle the primary combustion zone, and the secondary combustion zone 12 in high temperature is formed by the comparatively high O2 partial pressure around the primary combustion zone 11 where the rate of O2 is low. Because the secondary combustion zone is in high temperature, reduced substance, reduced radical is produced in large quantity in the primary combustion zone 11, that is an inner low O2 combustion zone, and produced NOx is reduced into a gas phase. Then the tertiary air 6 fed from a tertiary air port 7 joins to the primary and the secondary air in the downstream sides of the primary and the secondary combustion zones, by forming a complete combustion zone 14 together with those airs, buring the unburned content completely. With such an arrangement, the rate of NOx can be decresed, and the produced rate of NOx is reduced into a gas phase, so that the rate of NOx in exhaust gas can be lowered.
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