BURNER EMPLOYING IMPROVED FGR DUCT DESIGN

摘要

A burner for reducing the temperature of the recirculated fuel/air/flue gas mixture in the FGR duct in connection with burners in furnaces such as those used in steam cracking. The burner includes: a primary air chamber; a burner tube having a downstream end, and having an upstream end for receiving air and fuel; a burner tip being mounted on the downstream end of said burner tube adjacent to a first flame opening in the furnace, so that combustion of the fuel takes place downstream of said burner tip; at least one passageway having a first end at a second opening in the furnace and a second end adjacent the upstream end of said burner tube, said passageway having an orifice, said first end being spaced an effective distance from said first opening for minimizing entrainment of a burner flame into said second opening; at least one bleed air duct having a first end and a second end, said first end in fluid communication with said orifice of said at least one passageway and said second end in fluid communication with a source of air which is cooler than the flue gas; and means for drawing flue gas from said furnace through said at least one passageway and air from said source of air from said at least one bleed air duct through said at least one passageway in response to an inspirating effect created by uncombusted fuel, flowing through said burner tube from its upstream end towards its downstream end, whereby the flue gas is mixed with air from said at least one air bleed duct prior to the zone of combustion of the fuel and air to thereby lower the temperature of the drawn flue gas.