Patent ID: 6986658

Claim:
A burner, said burner being located adjacent a first opening in a furnace, said burner comprising: (a) a primary air chamber having a source of air; (b) a burner tube including a downstream end, an upstream end for receiving fuel and flue gas, air and mixtures thereof from said primary air chamber, a burner tip mounted on the downstream end of said burner tube adjacent the first opening in the furnace, so that combustion of the fuel gas takes place downstream of said burner tip; (c) at least one passageway having a first end at a second opening in the furnace and a second end opening into said primary air chamber, said primary air chamber being in fluid communication with the upstream end of said burner tube; (d) means for drawing flue gas from said furnace, through said passageway and into said primary air chamber; and (e) means for injecting steam into said at least one passageway, said means for injecting steam located upstream of said source of air, wherein the location of said means for injecting steam is effective to reduce the temperature of said at least one passageway.