| 摘要 |
A fuel burner for a boiler has a first assembly for delivering a flowable fuel into the boiler from a fuel delivery duct with or without combustion supporting primary air, and a second assembly for delivering secondary air in support of the combustion. The burner has a precombustion chamber defined by a wall extending into and opening in the combustion chamber in the boiler. The secondary air is delivered into the precombustion chamber close to the outlet of the fuel delivery duct, and a third assembly is provided for delivering tertiary air into the precombustion chamber downstream with respect to the secondary air outlet. This third assembly is disposed in the precombustion chamber. A jet flameholder is arranged with nozzles opposite to and spaced from the outlet of the fuel delivery duct. The jet flameholder is associated with an assembly which provides compressed fluid to eject fluid jets against the stream of the fuel, and this creates a recycle zone in the precombustion chamber. This arrangement allows combustion of lower grade fuels with reduced production of nitrogen oxides.
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