Patent ID: 7878798

Claim:
A gas burner apparatus for discharging a mixture of fuel gas and air into a furnace wherein the mixture is burned in the presence of flue gas while producing a low content of nitrous oxides comprising: a plenum including a housing for attachment to said furnace, said housing including: an upper end attached to said furnace, said upper end having an air outlet disposed therein; a lower end opposing said upper end; and a sidewall connecting said upper end and said lower end together, wherein at least one of said sidewall and said lower end has an air inlet disposed therein; a burner tile having a central opening therein for receiving air from said air outlet of said housing, said tile including: a bottom end attached to said upper end of said housing over said air outlet; a top end opposing said bottom end, said top end including a discharge outlet; and a wall connecting said bottom end to said top end and surrounding said central opening, said wall extending into said furnace and having an interior surface, an exterior surface and at least one gas circulation port extending though said wall, said interior surface of said wall including an internal Coanda surface which bulges into said central opening for enhancing the mixing of flue gas with primary fuel gas therein; primary fuel gas injection means connected to a source of fuel gas and operably associated with said burner apparatus for injecting primary fuel gas into said central opening of said burner tile; and secondary fuel gas injection means connected to a source of fuel gas and operably associated with said burner apparatus for injecting secondary stage fuel gas from outside of said burner tile to a point adjacent to said discharge outlet of said burner tile.