Plugging resistant free-jet burner and method

A method of operating a burner for low NOx emissions, resistance to plugging, and enhanced stability, wherein (a) the burner comprises a burner wall having a forward end and an interior passageway through which a stream of air or other oxygen-containing gas flows out of the forward end of the burner wall, (b) the burner is operated in a heating system, and (c) the method comprises a step of ejecting a fuel from a series of ejectors in free-jet flow streams outside of the burner wall either directly or indirectly to a main burner flame at and/or forwardly of the forward end of the burner wall, wherein an improvement comprises:

• ejecting the fuel from large fuel ejection ports in the ejectors having a flow area of at least 0.0068 inch2;
• recirculating a flue gas in the heating system through flow channels between the ejectors to the main burner flame, the ejectors having a wide tip-to-tip spacing between the ejectors of from 2 to 14 inches;
• and
• operating each of one or more auxiliary burner tips positioned in the interior passageway of the burner wall to direct an auxiliary tip flame onto the forward end of the burner wall or onto a ledge or other interior feature of the burner wall, each of the one or more auxiliary burner tips having a large fuel discharge port with a flow area of at least 0.012 inch2;
• and
• the improvement further comprises for each of the one or more auxiliary burner tips
• a step (1) of discharging a gas fuel from the large fuel discharge port into a rearward longitudinal end of a mixing chamber of the auxiliary burner tip, the mixing chamber having a lateral base wall at the rearward longitudinal end of the mixing chamber and the lateral base wall having at least a central opening formed therethrough,
• a step (2) of using a flow momentum of the gas fuel discharged in step (1) to draw a sub-stoichiometric amount of the air, or other oxygen-containing gas, from the interior passageway of the burner through at least the central opening of the lateral base wall to form a fuel rich sub-stoichiometric mixture of the air, or other oxygen-containing gas, and the gas fuel in the mixing chamber,
• a step (3) of discharging the fuel rich sub-stoichiometric mixture of the air, or other oxygen-containing gas, and the gas fuel through a stabilization ring at a forward longitudinal end of the mixing chamber to form a reduced pressure area at or outside of the forward longitudinal end of the mixing chamber which stabilizes the auxiliary tip flame of the auxiliary burner tip, the auxiliary tip flame having an initial sub-stoichiometric combustion region in which a first portion of the gas fuel of the fuel rich sub-stoichiometric mixture of the air, or other oxygen-containing gas, and the gas fuel is burned, and
• a step (4) of diverting the auxiliary tip flame laterally outward, into the stream of air, or other oxygen-containing gas, in the interior passageway of the burner wall, to form a fuel lean combustion region in which a remaining portion of the gas fuel is combusted.

A method of operating a burner for low NOx emissions, resistance to plugging, and enhanced stability, wherein (a) the burner comprises a burner wall having a forward end and an interior passageway through which a stream of air or other oxygen-containing gas flows out of the forward end of the burner wall, (b) the burner is operated in a heating system, and (c) the method comprises a step of ejecting a fuel from a series of ejectors in free-jet flow streams outside of the burner wall either directly or indirectly to a main burner flame at and/or forwardly of the forward end of the burner wall, wherein an improvement comprises:

• operating each of one or more auxiliary burner tips positioned in the interior passageway of the burner wall to direct an auxiliary tip flame onto the forward end of the burner wall or onto a ledge or other interior feature of the burner wall and
• for each of the one or more auxiliary burner tips
• forming, in a mixing chamber of the auxiliary burner tip, a fuel rich sub-stoichiometric combustion mixture comprising a gas fuel supplied to the auxiliary burner tip and
• discharging the fuel rich sub-stoichiometric combustion mixture from the mixing chamber through a stabilization ring at a forward longitudinal end of the mixing chamber to form a reduced pressure area at or outside of the forward longitudinal end of the mixing chamber which stabilizes the auxiliary tip flame of the auxiliary burner tip.

A method of operating a burner for low NOx emissions, resistance to plugging, and enhanced stability, wherein (a) the burner comprises a burner wall having a forward end and an interior passageway through which a stream of air, or other oxygen-containing gas, flows out of the forward end of the burner wall, (b) the burner is operated in a heating system, and (c) the method comprises a step of ejecting a fuel from a series of ejectors in free-jet flow streams outside of the burner wall either directly or indirectly to a main burner flame at and/or forwardly of the forward end of the burner wall, wherein an improvement comprises:

• operating each of one or more auxiliary burner tips positioned in the interior passageway of the burner wall to direct an auxiliary tip flame onto the forward end of the burner wall or onto a ledge or other interior feature of the burner wall and
• for each of the one or more auxiliary burner tips the improvement further comprises
• forming a fuel rich sub-stoichiometric combustion mixture in the auxiliary burner tip comprising a gas fuel supplied to the auxiliary burner tip,
• burning a first portion of the gas fuel supplied to the auxiliary burner tip in a sub-stoichiometric combustion region of the auxiliary tip flame, and
• diverting the auxiliary tip flame laterally outward from the sub-stoichiometric combustion region into the stream of air, or other oxygen-containing gas, in the interior passageway of the burner wall, to form a fuel lean combustion region of the auxiliary tip flame in which a remaining portion of the gas fuel supplied to the auxiliary burner tip is burned.

A method of operating a burner for low NOx emissions, resistance to plugging, and enhanced stability, wherein (a) the burner comprises a burner wall having a forward end and an interior passageway through which a stream of air, or other oxygen-containing gas, flows out of the forward end of the burner wall, (b) the burner is operated in a heating system, and (c) the method comprises a step of ejecting a fuel from a series of ejectors in free-jet flow streams outside of the burner wall either directly or indirectly to a main burner flame at and/or forwardly of the forward end of the burner wall, wherein an improvement comprises:

• operating each of one or more auxiliary burner tips positioned in the interior passageway of the burner wall to direct an auxiliary tip flame onto the forward end of the burner wall or onto a ledge or other interior feature of the burner wall, each of the one or more auxiliary burner tips having a large fuel discharge port with a flow area of at least 0.012 inch2 and
• for each of the one or more auxiliary burner tips, delivering a gas fuel to the large fuel discharge port of the auxiliary burner tip through a flow orifice, the flow orifice having a flow area of at least 0.0068 inch2, the flow area of the large fuel discharge port being larger than the flow area of the flow orifice, and the flow orifice being positioned and accessible outside of the heating system.