초록

The invention relates to an improved premix burner and a method of its operation for combustion with a minimum of NOx emissions. The improvement is achieved by combining staged combustion with a premix burner in a manner such that mixing of the secondary air with the flame is delayed.

대표청구항 ▼

A premixing burner for the combustion of fuel gas and air with reduced NOx production, said burner having a primary air-fuel gas combustion assembly and a secondary air combustion assembly, the primary air-fuel gas combustion assembly comprising a burner tube and a burner tile spaced from and surrou

A premixing burner for the combustion of fuel gas and air with reduced NOx production, said burner having a primary air-fuel gas combustion assembly and a secondary air combustion assembly, the primary air-fuel gas combustion assembly comprising a burner tube and a burner tile spaced from and surrounding the downstream end of said tube, the burner tube having a mixer connected to an extension tube and a burner tip mounted on the downstream end of said extension tube, the said mixer having inlets for fuel gas and primary air and adapted to mix said fuel and primary air prior to combustion at predetermined ratios, said burner tip having ports for passage of the gas from the extension tube, the burner tube and burner tile being adapted to support and stabilize a substoichiometric initial flame resulting from the combustion of the gases passing through the burner tip, said initial flame having a base in the region formed by said burner tile and burner tip, said secondary air combustion assembly comprising multiple secondary air ports and secondary air inlet means therefor, said secondary air ports being spaced radially from said burner tile and circumferentially from each other, the radial spacing being a sufficient distance to permit secondary air streams from the ports to react with the flame of the premixed gas substantially downstream of the burner tip, the circumferential spacing between ports being a sufficient distance to permit furnace flue gas to re-circulate to the base of the initial flame in amounts at least sufficient to achieve lower temperatures in the initial flame and to move the secondary air streams away from the initial flame, the primary air-fuel gas ratios including the range of about 25-65% of the stoichiometric air requirement of the fuel gas, the burner being adapted for a total air requirement of up to about 120 mol % of the stoichiometric air requirement of the fuel gas.