Gas burner with very small nitrogen oxide emission

Abstract

A gas burner for discharging a mixture of a gaseous fuel and combustion air into a combustion chamber wherein the mixture is burned and flue gases are formed comprises a burner body having a peripheral wall defining a combustion air supply passage having a central axis and having an orifice communicating with the combustion chamber. Primary gaseous fuel is injected in a central part of the combustion air supply passage, and secondary gaseous fuel is injected through pipes in the combustion air supply passage peripherally distributed about the primary gaseous fuel injection. Conduits for recycling the flue gases are disposed in the combustion air supply passage and associated with the secondary gaseous fuel injection. The secondary gaseous fuel is injected into the conduits, the conduits have an axis extending parallel to the central axis and an orifice along their axis at one end thereof, the orifice communicating with the combustion chamber. An end of the conduits opposite to the one end communicate with a portion of the combustion chamber surrounding the peripheral wall of the combustion air supply passage through openings in the peripheral wall, and a flame stabilizer is arranged at the orifice of the combustion air supply passage.