Lean premixed, radial inflow, multi-annular staged nozzle, can-annular, dual-fuel combustor

Abstract

A lean premixed, radial inflow, multi-annular staged nozzle for creating three independent combustion zones within a can-annular, dual-fuel gas turbine combustor is provided. The nozzle includes a pilot zone fueled by a gas pilot nozzle and center cartridge; a flame holder zone fueled by an inner main gas fuel; a main flame zone fueled by an outer main gas fuel; a main radial swirler for mixing a portion of incoming air to the nozzle with the inner main gas fuel supply and the outer main gas fuel supply; an endcover; and means for controlling the ratio of an inner main gas fuel supplied and an outer main gas fuel supplied.

1 . A lean premixed, radial inflow, multi-annular staged nozzle for creating three independent combustion zones within a can-annular, dual fuel gas turbine combustor, the nozzle comprising:
 a pilot zone fueled by a center cartridge during liquid operation and a center gas pilot nozzle during gas operation;   a central flame holder zone fueled by an inner main gas fuel supply;   a main flame zone fueled by an outer main gas fuel supply;   a main radial swirler for mixing a portion of incoming air to the nozzle with the inner main gas fuel supply and the outer main gas fuel supply;   means for controlling the ratio of an inner main gas fuel supply and an outer main gas fuel supply; and   an endcover.   
   
   
       2 . The nozzle according to  claim 1 , the main radial swirler comprising:
 a backplate mechanically fastened in axial alignment to the endcover;   a plurality of swirl vanes spaced approximately equidistantly in a circular array around a central axis of the nozzle;   a premixing space in a circumferential space between individual swirl vanes;   a central hub including a central cavity within; and   an annular swirl volume between the plurality of swirl vanes and the central hub.   
   
   
       3 . The large single radial nozzle according to  claim 2 , the backplate comprising:
 a cylindrical plate;   a central hub projecting axially downstream from a downstream surface of the backplate, wherein the central hub includes a smooth conical surface, truncated at a downstream end;   a cavity connecting a outer main gas fuel supply from the endcover to the plurality of swirl vanes;   a plurality of injector nozzles mounted on the downstream surface of the backplate;   a cavity connecting a inner main gas fuel supply from the endcover to the plurality of injector nozzles;   liquid fuel atomizers mounted on the downstream surface of the backplate;   a cavity connecting a liquid fuel supply from the endcover to the plurality of liquid fuel atomizers; and   a central cavity along the central axis of the nozzle.   
   
   
       4 . The nozzle according to  claim 3 , the cavity connecting the outer main gas fuel from the endcover to the plurality of swirl vanes further comprising:
 an orifice with the cavity for regulating outer main gas fuel supply to each swirl vane.   
   
   
       5 . The nozzle according to  claim 3 , wherein the cavity connecting the liquid fuel supply includes a thermal insulating outer liner. 
   
   
       6 . The nozzle according to  claim 3 , the backplate further comprising:
 a plurality of radial-oriented cavities connecting an outer circumferential surface of the backplate with the central cavity for supplying air to the center cartridge and the gas pilot nozzle.   
   
   
       7 . The nozzle according to  claim 2 , the swirl vane comprising:
 an airfoil projecting axially downstream from a downstream surface of the backplate towards a combustion end of the nozzle, wherein a centerline of the airfoil making a predetermined angle with a radius from the central axis of the nozzle, thereby defines the circumferential premixing space for air flow from outside the main swirler to an annular swirl volume between the main swirl vanes and the central hub;   an internal cavity within each airfoil for the outer main gas fuel supply within the backplate; and   a plurality of gas fuel injector holes for distributing outer main gas fuel supply to the premixing space from the internal cavity.   
   
   
       8 . The nozzle according to  claim 7 , the airfoils further comprising:
 a leading edge;   a trailing edge;   sidewalls tapering from the leading edge to the trailing edge;   the internal cavity within each airfoil extending from a bottom surface of the airfoil along the axial length of the airfoil, and being aligned radially and circumferentially with the outer main gas fuel supply cavity in the backplate; and   the gas fuel injector holes being disposed axially along the length of the internal cavity with the airfoil, each individual hole extending from the internal cavity to an opening on at least one sidewall of the airfoil for injecting outer main gas fuel normal to the airflow between adjacent airfoils.   
   
   
       9 . The nozzle according to  claim 2 , the premixing volume in circumferential space between individual swirl vanes further comprising:
 a radial-flaring portion of an outer burner tube overhead forming a downstream roof.   
   
   
       10 . The nozzle according to  claim 9 , wherein the radial flaring portion of the outer burner tube is mechanically attached to the top surface of the plurality of airfoils by mechanical means. 
   
   
       11 . The nozzle according to  claim 1 , the endcover comprising:
 a cylindrical plate, including an outer radial mounting surface for mechanical attachment to the combustor and an inner radial mounting surface for attachment to the backplate;   a cavity connecting a outer main gas fuel supply the backplate;   a cavity connecting a inner main gas fuel supply to the backplate;   a plurality of cavities connecting a liquid fuel supply from the endcover to the backplate; and   a central cavity, including a mounting flange, for accepting and mounting a center gas pilot nozzle.   
   
   
       12 . The nozzle according to  claim 1 , the central flameholder zone comprising:
 a center hub;   an inner burner tube wall;   a perforated cup including a plurality of holes about a central axis with fillets between the holes and the perforated cup, a shroud around an upper open-end of the perforated cup, and a circular opening in the bottom of the cup, wherein the shroud mates with the inner burner tube wall and the circular opening in the bottom of the cup is open to the center gas pilot.   
   
   
       13 . The nozzle according to  claim 1 , the central flameholder zone comprising:
 a center hub;   an inner burner tube wall;   a deswirler for converting a circumferential flow of a fuel-air mixture in the annular swirl volume of the main radial swirler and redirecting the airflow in an axial downstream direction; and   a v-gutter flame pack holder.   
   
   
       14 . The nozzle according to  claim 13 , the deswirler comprising:
 a plurality of segmented radial compartments, each compartment formed as an annular segment bounded on an outer radius by an inner burner tube wall and on an inner radius by an outside wall of the center hub, wherein adjacent compartments are separated by vanes of circumferentially-sloping radial walls wherein the slope progressively increases from an upstream entrance to the compartment to the downstream exit from the compartment, for deswirling a portion of the fuel-air mixture in the annular swirl volume.   
   
   
       15 . The nozzle according to  claim 13 , the v-gutter flame holder pack comprising:
 a plurality of radial oriented arms spaced approximately equidistant circumferentially around the inner burner tube, the arms being attached and extending from a downstream end of the center hub to a downstream axial end of the inner burner tube, wherein the attachment at the inner burner wall is located downstream from the attachment at the hub extension thereby forming a predetermined radial-axial angle for the radial oriented arms, and a convex shaped depression in the radial-oriented arms, a vertex of the convex shaped depression pointing upstream.   
   
   
       16 . The nozzle according to  claim 13 , the center hub comprising:
 a cylindrical tube with a central cavity, an irregular shape of an inner surface of cylindrical tube to accommodate the central gas pilot nozzle, and adapted at an upstream end to mate with the central hub of the main radial swirler, further including a hub extension on a downstream axial end of the cylindrical tube, the hub extension being interrupted by v-gutters at equidistant intervals around the hub.   
   
   
       17 . The nozzle according to  claim 3 , the central gas pilot nozzle comprising:
 a generally cylindrical-shaped body with a center cavity and a radially-expanded bolting flange at an upstream end; wherein the nozzle body is adapted to fit within a central cavity of the endcover, the backplate and a center hub of the flameholder zone;   a plurality of radial air feed holes aligned axially on the body to accept airflow from the central cavity of the backplate; and   a central cartridge including a liquid fuel pilot disposed within the center cavity; an igniter disposed within the center cavity; an end tip, providing axial and radial support on the downstream end for the liquid fuel pilot and the igniter; a liquid pilot fuel supply; a gas pilot fuel supply; and a power supply connection for the igniter.   
   
   
       18 . The nozzle according to  claim 17 , the central gas pilot nozzle further comprising:
 an annulus formed between the central cavity of the backplate and the center hub of the flameholder for passing a portion of air supplied to the central cavity of the backplate to the gas pilot nozzle and the central cartridge;   an annulus, positioned inner radially from an inside wall of the central cartridge, for supplying pilot gas fuel to the gas pilot from a gas pilot supply at the downstream end of the central cartridge;   a plurality of pilot swirl vanes projecting radially outward between the outer surface of the central cartridge and the inner surface of the center hub of the flameholder for mixing air in the annulus with pilot gas fuel, the swirl vanes positioned equidistant around the outer surface;   a plurality of radially extending holes through the central cartridge wall, individual holes, radially-centered and axially-positioned at the upstream entrance between adjacent pilot swirl vanes; and   an annulus located downstream of the swirl vanes for supplying a swirled pilot gas-air mixture to the pilot zone.   
   
   
       19 . The nozzle according to  claim 17 , the central cartridge comprising:
 an axial body for the liquid fuel pilot;   an axial channel through the center of the liquid fuel pilot for liquid fuel;   an insulating annular air gap surrounding the axial body;   an air assist supply for the liquid fuel pilot;   an air assist annulus surrounding the axial body;   a truncated conical liquid fuel spin chamber;   a truncated conical heat shield surrounding the liquid fuel spin chamber;   a truncated conical annulus surrounding the heat shield and   a tip impingement shield with air passage holes for center cartridge air.   
   
   
       20 . The nozzle according to  claim 19 , the central cartridge further comprising:
 a center cartridge air chamber running the axial length of the center cavity of the central cartridge and bounded on the downstream end by the tip impingement shield;   the tip impingement shield including a plurality of axial holes;   an air chamber positioned axially between the tip impingement shield and the end tip;   a channel to the igniter from the air chamber; and   a channel to the truncated conical annulus surrounding the heat shield on the liquid fuel pilot.   
   
   
       21 . The nozzle according to  claim 1 , the main zone further comprising:
 a cylindrical inner burner tube wall centered on a central axis of the nozzle;   a cylindrical outer burner tube wall centered on the central axis of the nozzle, the outer burner tube wall projecting axially downstream from the downstream surface of the main radial swirler and being of larger diameter being than the inner burner tube wall; and   a flared portion of the outer burner tube at its upstream end extending outward radially as an annular circumferential surface, the circumferential surface forming a roof over the plurality of main swirl vanes and channeling the fuel and air into the annular mixing zone.   
   
   
       22 . The nozzle according to  claim 1 , the means for controlling the ratio of an inner main gas fuel supplied and an outer main gas fuel supplied comprising:
 at least one of means for throttling the fuel supplies and means for changing the pressure of the fuel supplies.   
   
   
       23 . A can-annular dual-fuel combustor for a gas turbine engine, comprising:
 a lean premixed, radial inflow, multi-annular staged nozzle, including an inner burner tube, an outer burner tube and a main radial swirler mounted on an endcover to a combustor casing;   a main combustion zone downstream from the outer burner tube of the nozzle;   a source of compressed air from a compressor;   an air inlet plenum radially surrounding the single large radial nozzle and bounded radially by an outer wall of the combustor;   a diffuser for the compressed air, the diffuser receiving the compressed air in a reverse flow path from the compressor and discharging the compressed air at a restored pressure to the inlet plenum; and   a fairing mounted atop the main radial swirler and surrounding a portion of the outer burner tube for smoothing air flow from the diffuser to the air inlet plenum.   
   
   
       24 . The can-annular dual-fuel combustor according to  claim 23 , the diffuser further comprising:
 an inner wall, the inner wall being coincident with the backside for a dome on the main combustion zone, thereby providing backside cooling to the dome from the compressed air passing through the diffuser.   
   
   
       25 . The can-annular dual-fuel combustor according to  claim 23 , the outer burner tube further comprising:
 a reinforced cylindrical segment in proximity to the downstream end of the tube, including a cylindrical ledge wherein the cylindrical ledge provides axial and radial support for the dome.   
   
   
       26 . The can-annular dual-fuel combustor according to  claim 23 , wherein the combustor further comprising:
 a plurality of supply and control connections to an endcover including:
 an outer main gas fuel supply; 
 an inner main gas fuel supply; 
 a gas pilot supply 
 a liquid fuel supply; 
 a liquid pilot fuel supply; 
 an air assist supply; 
 igniter controls; and 
 flame detector controls. 
   
   
   
       27 . A method for utilizing a lean premixed, radial inflow, multi-annular staged nozzle with independent combustion zones including a pilot zone, a flame holder zone and a main zone, within a can-annular dual-fuel gas turbine combustor for providing stable combustion with low Nitrogen Oxide (NOx) emissions, the method comprising
 providing a large supply of air to the nozzle;   intra-nozzle staging;   breaking up heat release into a multiplicity of discrete zones in space;   distributing the heat release in time; and   ventilating a downstream central recirculation zone.   
   
   
       28 . The method for utilizing a lean premixed, radial inflow, multi-annular staged nozzle within a gas turbine combustor for providing stable combustion with low NOx emissions according to  claim 27 , the step of providing a large supply of air to the nozzle comprising:
 providing a channeled reverse flow path for air to the nozzle from an air compressor;   recovering static air pressure by diffusing air flow through a diffuser tube positioned between the reverse flow path for air and an inlet plenum for the nozzle;   smoothing air flow entering the inlet plenum for the nozzle with a fairing shaped around the outer flame holder for the nozzle; and   flowing air through large flow passages of a single large radial nozzle.   
   
   
       29 . The method for utilizing a lean premixed, radial inflow, multi-annular staged nozzle within a gas turbine combustor for providing stable combustion with low NOx emissions according to  claim 27 , the step of intra-nozzle staging comprising:
 providing a outer main fuel supply;   providing a inner main fuel supply;   mixing the outer main fuel supply with air from the inlet plenum at an outboard injection point between adjacent swirl vanes of the main radial swirler, the injection point being outboard radially of the swirl vanes;   mixing the inner main fuel supply with air from the inlet plenum at an inboard injection points radially inboard of the swirl vanes;   controlling the ratio of fuel injected at the outboard injection point and the inboard injection point; and   biasing a fuel-air ratio to be richer near the central hub of the main radial swirler; and   burning fuel in the flame holder zone at a higher equivalence ratio relative to burning in the main zone.   
   
   
       30 . The method for utilizing a lean premixed, radial inflow, multi-annular staged nozzle within a gas turbine combustor for providing stable combustion with low NOx emissions according to  claim 27 , the step of breaking up the heat release into a multiplicity of discrete zones in space comprising:
 providing three spatially-separated burn zones including the pilot zone, the flame-holder zone and the main zone; and   employing a physical separation of a plurality sloping radial arms of the v-gutter pack to create a multiplicity of discrete reaction zones in space, each reacting at spatial scales that are much smaller than that of the overall combustion chamber effectively limiting the amount of energy release that can constructively couple at a particular resonant frequency within the combustion chamber.   
   
   
       31 . The method for utilizing a lean premixed, radial inflow, multi-annular staged nozzle within a gas turbine combustor for providing stable combustion with low NOx emissions according to  claim 27 , the step of distributing the heat release in time comprising:
 establishing a discrete fuel transport time for each point along a length of a v-gutter, effectively limiting the amount of energy release that can constructively couple at a particular resonant frequency within the combustion chamber.   
   
   
       32 . The method for utilizing a lean premixed, radial inflow, multi-annular staged nozzle within a gas turbine combustor for providing stable combustion with low NOx emissions according to  claim 27 , the step of ventilating a downstream central recirculation zone comprising:
 deswirling the a fuel-air mixture, from the main radial swirler, in the central flame-holder;   injecting non-swirling axial momentum into the central recirculation zone; and   limiting the average time that combustion-product molecules spend at flame temperatures in the combustion zone.