| 摘要 |
PURPOSE:To prevent the flammability under highly turned-down state from deteriorating by a structure wherein an air nozzle consists in dividing into a plurality of nozzles, each of which can separately control its flow rate, and at the same time a fuel nozzle is protruded in the downstream side of the air nozzle. CONSTITUTION:Fuel gas is jetted in a portion, in which strong swirling flow is formed by combustion air jetted inwards from air nozzles 13 and 14 arranged so as to surround a fuel nozzle 12. A part of the jetted fuel gas is mixed with the excessive amount of combustion air on the upstream side and burnt under the state of lean mixture. On the other hand, the remaining part of the jetted fuel gas is jetted to the flames formed by said burning under the state of lean mixture on the upstream side and burnt under the state of rich mixture, resulting in enabling to keep the mean amount of exhausted NOX at a lower value. Further, when the combustion rate owers below 50% of the rated fuel flow rate, either one of the inner flow nozzle 13 and the outer flow nozzle 14 is closed and combustion air is jetted from the remaining nozzle, resulting in forming combustion air into storng swirling flow and rapidly mixing the combustion air with fuel gas and at the same time spreading the resultant fuel gas-and- air mixture along the combustion chamber 24 of a port block 11. Consequently, the amount of NOX can be kept at a lower value, even when the combustion rate is 25%, by employing the titled burner.
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