Low NOx radiant wall burner

A low NOx radiant wall burner comprising a burner tile having a central opening surrounded by a radiant tile face and an elongated low NOx burner nozzle assembly extending through said opening, said nozzle assembly including an elongated hollow burner tube and a discharge nozzle, said burner tube having a central, longitudinally extending axis and defining a conduit extending along said axis for supplying a mixture of fuel and air to radiant combustion area in a combustion zone surrounding said discharge nozzle, said radiant combustion area being adjacent said face, said discharge nozzle being mounted on said tube at a downstream end of the conduit adjacent said area and being adapted for receiving said mixture of fuel and air from the conduit and directing the same into said area in an essentially radial direction relative to said axis, said discharge nozzle comprising:

• a plurality of flow directing members arranged in an array which extends circumferentially around said discharge nozzle, said members being arranged to define therebetween a plurality of passageways which extend in a generally radial direction relative to said axis;
• and
• an end cap mounted on said members in a location to close said conduit and prevent flow of said mixture in a direction along said axis, whereby the mixture is caused to flow through said passageways in a generally radial direction,
• wherein at least one duct is provided in said tile for directing oxygen to a location in said zone adjacent the outer peripheral extremity of the flame, wherein said duct has one end in communication with said zone at said face and another end in communication with said opening, and wherein said one end of the duct is arcuate in shape and projects a fan-shaped flow of air into said zone.

A low NOx burner nozzle assembly for a radiant wall burner including an elongated hollow burner tube, a discharge nozzle, and a central staged fuel nozzle, said burner tube having a central, longitudinally extending axis and defining a conduit extending along said axis for supplying a mixture of fuel and air to a radiant combustion area in combustion zone surrounding said discharge nozzle, said discharge nozzle being mounted on said tube at a downstream end of the conduit adjacent said area and being adapted for receiving said mixture of fuel and air from the conduit and directing the same in an essentially radial direction relative to said axis into said area, said discharge nozzle including an end cap positioned to prevent flow of said mixture in a direction along said axis, said central staged fuel nozzle comprising:

• a length of tubing which extends along the axis of said conduit;
• and
• a staged burner nozzle tip at a downstream end of said length of tubing,
• said staged fuel burner nozzle being arranged so as to protrude axially through a hole in said end cap,
• said tip having a fuel delivery orifice therein disposed for delivering fuel to said zone in spaced relationship to said area of said zone, said delivery orifice being disposed to eject fuel gas at an upward and outward angle relative to a plane that is perpendicular to said axis.

A method for burning fuel in a combustion zone comprising:

• providing a fuel lean mixture of fuel and air;
• delivering said mixture to a centrally located point adjacent a face of a burner tile, said being disposed adjacent said combustion zone;
• causing said mixture to flow radially outwardly from said point in a plurality of streams across the face of said tile;
• combusting the fuel in said mixture in an area of said combustion zone adjacent said face;
• and
• providing staged fuel to said zone at a location spaced from said area;
• and
• combusting said staged fuel in an environment containing flue gases and not more than about 4% oxygen by volume.