Abstract: An improved burner for both liquid and gaseous fuels in which the combustion air is divided into at least two parts, comprising primary and secondary air. The primary air, which is insufficient to completely burn the fuel, creates a flame zone in which there is a deficiency of air, which produces quantities of carbon monoxide and hydrogen. The combustion products are recirculated, cooled and re-entered into the combustion zone in the region of the fuel and primary air entry, resulting in a reduction in the oxides of nitrogen. The secondary air, in quantities greater than the primary air, is introduced into a second combustion zone downstream of the first combustion zone. In the second combustion zone the deficiency in air is made up by the secondary air so that complete combustion can be carried out. If desired, a third quantity of air can be introduced still farther downstream in the flame zone.

Abstract: A noiseless premix burner comprising a cylindrical housing which is attached to the outer covering of the furnace wall, and closed at its opposite end by a closure plate which supports a concentric burner tube which extends from the closure plate through an opening in the furnace wall to the interior of the furnace. A gas fuel line is inserted along the axis of the burner tube. Pressurized fuel gas flows through an orifice in the fuel line in an expanding flow. The proximal end of the burner tube has a venturi type throat construction. The annular space between the burner tube and the cylindrical housing comprises two plenums, one adjacent the outer wall of the furnace supplying secondary air, which passes into the furnace through a narrow annular gap between the burner tube and the furnace lining.