Importance

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Abstract

A staged, high efficiency burner for gaseous, liquid or pulverized solid fuels (including fuels having a high nitrogen content) in which NOX emissions are minimized. The burner includes a burner basket having a base including a throat and a concentric, tubular, frustroconically shaped wall that defines a primary combustion space. The fuel and primary air of about 75% of stoichiometric air are introduced into the basket which has a length so that the fuel has a residence time therein of between about 0.1 to 0.5 second. Secondary air is introduced into the flame downstream of the basket in the form of a multiplicity of individual air streams which are oriented to penetrate the flame and spin it about its axis so as to maintain a substantially cylindrical flame periphery. Part of the secondary air can be introduced through the tubular wall of the basket to shorten the flame length while maintaining the low level NOX emissions and the high efficiency of the burner by directing that part of the secondary air into the primary space so that the formation of pockets which have a high or excess air content cannot form. The flame basket can be disposed fully within the combustion chamber of the furnace or, to prevent it from penetrating excessively into the chamber, part of the basket can be disposed outside the chamber.

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First Claim