Apparatus for burning fuel with low NOx formation

An improved burner apparatus for discharging a substantially stoichiometric mixture of fuel gas and air into a furnace wherein the mixture is burned and flue gases having low NOx content are formed therefrom comprising:

• a burner housing attached to said furnace having a forward end which includes a base portion and a wall portion, the wall portion extending into said furnace and surrounding a central area of said base portion;
• means connected to said housing for mixing a first portion of said fuel gas with a first portion of said air to form a primary fuel gas-air mixture and discharging said primary fuel gas-air mixture into a primary burning zone in said furnace from at least one primary fuel gas-air mixture discharge location within the space defined by said central area of said base portion and the interior of said wall portion of said burner housing;
• and
• means connected to said housing for mixing a second portion of said fuel gas with a second portion of said air to form a secondary fuel gas-air mixture and discharging said secondary fuel gas-air mixture into a secondary burning zone in said furnace from at least one secondary fuel gas-air mixture discharge location adjacent to an exterior side of said wall portion at a velocity whereby said secondary fuel gas-air mixture is not ignited and burned until said mixture spreads over said exterior side of said wall portion, mixes with flue gases in said furnace and flows beyond said wall portion.