A method for reducing nitrogen oxide NOx emissions during combustion of a gaseous fuel in a burner intended for a naked-flame or controlled-atmosphere reheating furnace, for reheating steel products or for continuous coating and/or annealing of metal strips, wherein a first dilution is carried out by mixing combustion air with combustion products upstream from or in the body of the burner, and a second dilution is carried out directly at the level at which the gaseous fuel reacts with the combustion air, mixing the fuel with a recirculated portion of the flame or products of partial combustion, the double dilution enabling the physical and chemical properties of the gas to be modified in order for the burner to operate with low oxygen rates and obtain a flame that produces a very low level of NOx production regardless of the temperature of the enclosure in which the combustion takes place.

A plugging resistant, highly stable free jet burner and method which provide Ultra-Low NO.sub.x emissions for any fuel using angular ejection, large ejection ports, auxiliary burner tips, and wide tip-to-tip spacing, and which also permit the use of a high-hydrogen or 100% hydrogen fuel to reduce or substantially eliminate carbon dioxide emissions.

A burner includes a housing, a fan, a burning head and an ignition mechanism. An air inlet of the housing and an input end of the burning head form a pressure equalizing cavity. The ignition mechanism is arranged at an output end of the burning head. The burning head includes a main frame and at least one stable burning isolation strip, an interior of the main frame is divided into at least two ventilation areas by the stable burning isolation strip in a gas channel direction. A plurality of separation mechanisms is arranged in each ventilation area and divide the ventilation area into a plurality of through holes arranged in the gas channel direction, the through holes are used for allowing mixed gas to pass through and strengthening the mixing effect. The burning flame of a burning surface of the main frame can be divided into mutually independent flames by the stable burning isolation strip. The burner can be used in gas stoves, low-nitrogen combustion engines for a gas boiler, gas water heaters and gas heating water heaters.