Abstract: The present invention concerns a low nitrogen oxides generating combustion apparatus and a low nitrogen oxides generating combustion method. The apparatus and method of the present invention, the effect of self-induced exhaust gas recirculation can be obtained to the maximum extent, and the lower flame temperature and the lower oxygen concentration assure remarkably low NOx generation.

Abstract: A water tube boiler using jet flames is disclosed which is capable of achieving low CO-emission combustion without enlarging a size of a combustion chamber. The water tube boiler comprises a combustion chamber 1 in which jet flames are generated and rows 3a to 3e of water tubes inserted through the combustion chamber. The group of water tubes provides a portion thick with the water tubes and a portion empty of the water tubes in a cross-section perpendicular to the direction of the jet flames, and at least the space Sa as an empty portion continuously extends through said group of water tubes in the direction of the jet flames. In the space Sa as an "empty" portion provided between the rows 3b and 3d of water tubes, recirculating flows (shown by arrows) of a combustion gas are generated. The recirculating flows are entrained by the jet flames existing the portion "thick" with the water tubes. Consequently, rapid temperature decrease of the jet flames is prevented.

Abstract: An object of the present invention is to achieve lower NOx combustion in response to the increasingly intensified NOx regulations for burners. The present invention provides a low nitrogen oxides generating combustion method and apparatus which utilizes effective self-induced exhaust gas recirculation before the initiation of the combustion of diffusion flames, or allows part of the combustion gas to be entrained by auxiliary fuel flow, air flow and fuel flow before the formation of the diffusion flames to further intensify the recirculation flow of the combustion gas by the diffusion flames or, in addition, which can achieve rich and lean combustion in the diffusion flames for decreasing the generation of NOx by a combination of these measures, and which are excellent in flame stability even in a low temperature atmosphere.