EP3314167B1

EP3314167B1 - Fuel nozzle assembly having a premix flame stabilizer

Info

Publication number: EP3314167B1
Application number: EP15825974.7A
Authority: EP
Inventors: Almaz Kamilevich Valeev; Leonid Borisovich Zvedenuk; Vladimir Vasilyevich BELYAEV
Original assignee: General Electric Co
Current assignee: General Electric Technology GmbH
Priority date: 2015-06-24
Filing date: 2015-06-24
Publication date: 2023-04-05
Anticipated expiration: 2035-06-24
Also published as: EP3314167A1; JP2018536132A; WO2016209101A1; JP6595010B2; CN107750322A

Description

TECHNICAL FIELD

The present invention generally relates to a fuel nozzle assembly for use in a combustor of a gas turbine. More particularly, this invention relates to a fuel nozzle assembly having a baffle plate for flame stabilization downstream from the fuel injection location.

BACKGROUND

A typical gas turbine includes an inlet section, a compressor section, a combustion section, a turbine section, and an exhaust section. The inlet section cleans and conditions a working fluid (e.g., air) and supplies the working fluid to the compressor section. The compressor section progressively increases the pressure of the working fluid and supplies a compressed working fluid to the combustion section. The compressed working fluid and a fuel are mixed within the combustion section and burned in a combustion chamber to generate combustion gases having a high temperature and pressure. The combustion gases are routed along a hot gas path into the turbine section where they expand to produce work. For example, expansion of the combustion gases in the turbine section may rotate a shaft connected to a generator to produce electricity.
The combustion section generally includes one or more combustors annularly arranged and disposed between the compressor section and the turbine section. Various parameters influence the design and operation of the combustors. For example, gas turbine manufacturers are regularly tasked to increase gas turbine efficiency without producing undesirable air polluting emissions. The primary air polluting emissions typically produced by gas turbines burning conventional hydrocarbon fuels are oxides of nitrogen (NOx), carbon monoxide (CO), and unburned hydrocarbons (UHCs). Oxidation of molecular nitrogen and thus the formation of NOx in air-breathing engines such as gas turbines is an exponential function of temperature. The higher the temperature of the combustion gases, the higher the rate of formation of the undesirable NOx emissions.
One way to lower the temperature of the combustion gases, thus controlling the formation of NOx, is to pre-mix fuel and air upstream from a combustion reaction zone within the combustion chamber using a premix type of fuel injector or fuel nozzle assembly, such as a swirler or swozzle type fuel nozzle assembly. In this type of fuel nozzle assembly, fuel is injected into a flow of compressed air within an annular flow or premix passage defined within the fuel nozzle assembly. The fuel and compressed air mixes within the annular passage and is then routed into the combustion chamber from a downstream end of the fuel nozzle assembly. During combustion, the heat capacity or thermal capacitance of excess air present in the air-rich or fuel-lean combustible mixture absorbs heat in the combustion chamber, thus reducing the temperature of the combustion gases, thereby decreasing or preventing the formation of NOx emissions.
A flow field of the lean combustible mixture exiting the premix passage and entering the combustion chamber at the injection point should be uniform or symmetric in order to reduce the potential for flame holding and to achieve desired emissions performance. Accordingly, continued improvements in current fuel nozzle assembly technologies would be useful.
US 2013/219899 A1 and US 2011/239653 each disclose a fuel nozzle assembly showing the features of the preamble of claim 1 in connection with each other.

BRIEF DESCRIPTION

Aspects and advantages of the invention are set forth below in the following description, or may be obvious from the description, or may be learned through practice of the invention.
A fuel nozzle assembly for a gas turbine in accordance with the invention as hereinafter claimed comprises the features of claim 1 below.
A combustor for a gas turbine in accordance with the invention as hereinafter claimed comprises the features of claim 8 below.
A gas turbine in accordance with the invention as hereinafter claimed comprises the features of claim 13 below.
Those of ordinary skill in the art will better appreciate the features and aspects of such embodiments, and others, upon review of the specification.

BRIEF DESCRIPTION OF THE DRAWINGS

A full and enabling disclosure of the present invention, including the best mode thereof to one skilled in the art, is set forth more particularly in the remainder of the specification, including reference to the accompanying figures, in which:

FIG. 1 is a functional block diagram of an exemplary gas turbine within the scope of the present invention;
FIG. 2 is a simplified cross-section side view of an exemplary combustor as may incorporate various embodiments of the present invention;
FIG. 3 is a perspective view of an exemplary fuel nozzle assembly according to at least one embodiment of the present invention;
FIG. 4 is a cross sectioned perspective view of the exemplary fuel nozzle assembly as shown in FIG. 3, according to at least one embodiment of the present invention;
FIG. 5 is a cross sectioned perspective view of the exemplary fuel nozzle assembly as shown in FIG. 3, according to at least one embodiment of the present invention;
FIG. 6 is an enlarged cross sectioned side view of a portion of an exemplary baffle plate of the exemplary fuel nozzle assembly as shown in FIG. 3, according to one embodiment of the present invention;
FIG. 7 is an enlarged cross-section side view of a portion of an exemplary baffle plate of the exemplary fuel nozzle assembly as shown in FIG. 3, according to one embodiment of the present invention; and
FIG. 8 is a downstream perspective view of a cross sectioned portion of the fuel nozzle assembly as shown in FIG. 3 and provides an operational flow diagram of a portion of the fuel nozzle assembly according to at least one embodiment of the present invention.

DETAILED DESCRIPTION

Reference will now be made in detail to present embodiments of the invention, one or more examples of which are illustrated in the accompanying drawings. The detailed description uses numerical and letter designations to refer to features in the drawings. Like or similar designations in the drawings and description have been used to refer to like or similar parts of the invention.
As used herein, the terms "first", "second", and "third" may be used interchangeably to distinguish one component from another and are not intended to signify location or importance of the individual components. The terms "upstream," "downstream," "radially," and "axially" refer to the relative direction with respect to fluid flow in a fluid pathway. For example, "upstream" refers to the direction from which the fluid flows, and "downstream" refers to the direction to which the fluid flows. Similarly, "radially" refers to the relative direction substantially perpendicular to the fluid flow, and "axially" refers to the relative direction substantially parallel to the fluid flow. The term "circumferentially" refers to a relative direction that extends around an axial centerline of a particular component.
Each example is provided by way of explanation of the invention, not limitation of the invention. In fact, it will be apparent to those skilled in the art that modifications and variations can be made in the present invention without departing from the scope thereof. For instance, features illustrated or described as part of one embodiment may be used on another embodiment to yield a still further embodiment. Thus, it is intended that the present invention covers such modifications and variations as come within the scope of the appended claims.
Referring now to the drawings, wherein identical numerals indicate the same elements throughout the figures, FIG. 1 provides a functional block diagram of an exemplary gas turbine 10 that may incorporate various embodiments of the present invention. As shown, the gas turbine 10 generally includes an inlet section 12 that may include a series of filters, cooling coils, moisture separators, and/or other devices to purify and otherwise condition a working fluid (e.g., air) 14 entering the gas turbine 10. The working fluid 14 flows to a compressor section where a compressor 16 progressively imparts kinetic energy to the working fluid 14 to produce a compressed working fluid 18 at a highly energized state.
The compressed working fluid 18 is mixed with a fuel 20 from a fuel supply system 22 to form a combustible mixture within one or more combustors 24. The combustible mixture is burned to produce combustion gases 26 having a high temperature and pressure. The combustion gases 26 flow through a turbine 28 of a turbine section to produce work. For example, the turbine 28 may be connected to a shaft 30 so that rotation of the turbine 28 drives the compressor 16 to produce the compressed working fluid 18. Alternately or in addition, the shaft 30 may connect the turbine 28 to a generator 32 for producing electricity. Exhaust gases 34 from the turbine 28 flow through an exhaust section 36 that connects the turbine 28 to an exhaust stack 38 downstream from the turbine 28. The exhaust section 36 may include, for example, a heat recovery steam generator (not shown) for cleaning and extracting additional heat from the exhaust gases 34 prior to release to the environment.
The combustors 24 may be any type of combustor known in the art, and the present invention is not limited to any particular combustor design unless specifically recited in the claims. For example, the combustor 24 may be a can-annular type of combustor. FIG. 2 provides a simplified cross-section side view of an exemplary combustor 24 that may incorporate various embodiments of the present invention. As shown in FIG. 2, a casing 40 (such as compressor discharge casing) and an end cover 42 may be coupled together via a combustor casing 44 to contain the compressed working fluid 18 flowing to the combustor 24 from the compressor 16 (FIG. 1). The compressed working fluid 18 may pass through flow holes 46 in an annular flow sleeve 48, such as an impingement sleeve or a combustion flow sleeve, to flow along the outside of a transition duct 50 and/or a liner 52 towards a head end 54 of the combustor 24.
The head end 54 is at least partially defined by the end cover 42 and/or the combustor casing 44. The compressed working fluid 18 may provide convective and/or conductive cooling to the transition duct 50 and/or to the liner 52 as it flows towards the head end 54. At the head end 54, the compressed working fluid 18 reverses in flow direction and flows through one or more fuel nozzle assemblies 56. The fuel 20 flows from the fuel supply system 22 through one or more fuel circuits (not shown) defined within the end cover 42 and into each or some of the fuel nozzle assemblies 56. The fuel supply system 22 may provide a gaseous and/or a liquid fuel to the combustor 24. The compressed working fluid 18 is premixed with the fuel 20 as it passes through and/or around the fuel nozzle assemblies 56 to form a combustible mixture 58. The combustible mixture 58 flows from the fuel nozzle assemblies 56 into a combustion chamber 60 for combustion.
FIG. 3 provides a perspective view of an exemplary fuel nozzle assembly 100 of the one or more fuel nozzle assemblies 56 as shown in FIG. 2, according to one embodiment of the present invention. FIG. 4 provides a cross sectioned side view of the fuel nozzle assembly 100 as shown in FIG. 3, according to one embodiment of the present invention. In various embodiments, as shown in FIG. 4, the fuel nozzle assembly 100 includes an annular center body 102, an annular outer tube 104 that at least partially surrounds the center body 102, a premix flow passage 106 that is defined radially between the center body 102 and the outer tube 104, a plurality of fuel ports 108 disposed between the center body 102 and the outer tube 104 within the premix flow passage 106, and a baffle plate 110 that extends radially outwardly from the center body 102 to the outer tube 104 at a downstream end portion 112 of the fuel nozzle assembly 100. As shown in FIG. 3, the baffle plate 110 extends circumferentially and radially across the downstream end portion 112 of the fuel nozzle assembly 100 with respect to an axial centerline 114 of the fuel nozzle assembly 100.
As shown in FIG. 4, the center body 102 is coaxially aligned with the axial centerline 114 of the fuel nozzle assembly 100. The center body 102 includes an upstream end portion 116 axially spaced from a downstream end portion 118. The center body 102 may be formed from one or more annular tubes. In particular embodiments, the center body 102 at least partially defines a center passage 120 that extends axially through the fuel nozzle assembly 100. The center passage 120 may be configured to receive a cartridge or insert (not shown). For example, the center passage 120 may accommodate a gas fuel only cartridge, a liquid fuel cartridge and/or a purge air cartridge. The cartridge may provide for dual fuel and/or purge air capability for the fuel nozzle assembly 100.
In particular embodiments, as shown in FIG. 4, the center body 102 includes a converging portion 122. The converging portion 122 converges radially inwardly along the axial centerline 114 in an axial direction towards the baffle plate 110 and/or the downstream end portion 118 of the center body 102. The converging portion 122 may progressively reduce a cross sectional flow area of the center passage 120 from a first cross sectional flow area 124 as measured upstream from the converging portion 122 to a smaller second cross sectional flow area 126 as measure from a point located along the converging portion 122. In addition, the converging portion 122 may progressively increase a cross sectional flow area of the premix flow passage 106 from a first cross sectional flow area 128 as measured upstream from the converging portion 122 to a larger second cross sectional flow area 130 as measured at a point located along the converging portion 122.
In particular embodiments, as shown in FIG. 4, at least a portion of the plurality of fuel ports 108 may be defined along a ring manifold 132. The ring manifold 132 may be substantially concentric with the center body 102 and may be positioned within the premix flow passage 106 between the center body 102 and the outer tube 104. The ring manifold 132 may include and/or define various fuel circuits or plenums 134 (don't see this number in FIGS.) that are in fluid communication with the fuel ports 108. In particular embodiments, the fuel plenums 134 may be fluidly segregated and may be operated or charged with fuel independently from one another. In particular embodiments, the fuel ports 108 may be axially spaced with respect to axial centerline 114, thus providing for axially staged fuel injection within the premix flow passage 106.
In particular embodiments, a plurality of struts or vanes 136 extend radially from the center body 102. In one embodiment, the struts 136 extend radially from the center body 102 to the ring manifold 132. The struts 136 may define various fuel passages or circuits 138 therein. In various embodiments, the fuel passages 138 are in fluid communication with one or more fuel circuits 140 defined within the center body 102. The fuel circuits 140 may be configured to provide a gaseous fuel and/or a liquid fuel to the fuel ports 108. The ring manifold 132 and/or the struts 136 may be shaped and/or configured to have a minimal aerodynamic effect on compressed air flowing across the ring manifold 132 within the premix flow passage 106. In particular embodiments, at least a portion of the plurality of fuel ports 108 may be disposed or defined along the struts 136. The fuel ports 108 provide for fluid communication between the fuel passages 138 defined within the struts 136 and the premix flow passage 106.
FIG. 5 provides a cross sectioned side view of the fuel nozzle assembly 100, according to another embodiment of the present invention. As shown in FIG. 5, the struts 136 may extend radially between the center body 102 and the outer tube 104 within the premix flow passage 106. At least a portion of the plurality of fuel ports 108 may be disposed or defined along the struts 136. In one embodiment, as shown in FIG. 5, at least a portion of the plurality of fuel ports 108 may be disposed along the center body 102 downstream from the struts 136.
In particular embodiments, as shown in FIGS. 3, 4 and 5, the fuel nozzle assembly 100 further includes a flow conditioning portion 142 that is disposed or defined upstream from the plurality of fuel ports 108 and/or the premix passage 106. In particular embodiments, as shown in FIGS. 4 and 5, the flow conditioning portion 142 may generally include one or more concentric vanes 144 coaxially aligned with the center body 102. The vane(s) 144 may manipulate the flow characteristics or flow profile of the compressed air 18 (FIG. 2) as it flows from the head end 54 of the combustor 24 into the premix passage 106 upstream from the plurality of fuel ports 108. In particular embodiments, as shown in FIG. 4, the fuel nozzle assembly 100 may include a plurality of apertures 146 defined by or within an outer sleeve 148 and/or an end plate 150. The plurality of apertures 146 may manipulate the flow characteristics or flow profile of the compressed air 18 (FIG. 2) as it flows from the head end 54 of the combustor 24 into the premix passage 106 upstream from the plurality of fuel ports 108.
In various embodiments, as shown in FIG. 3, the baffle plate 110 extends radially and circumferentially across the downstream end portion 112 of the fuel nozzle assembly 100. The baffle plate 110 generally provides a bluff body across the premix flow passage 106 upstream from the combustion chamber 60 (FIG. 2). In particular embodiments, as shown in FIGS. 3, 4 and 5, the baffle plate 110 may include a center portion 152 that defines an opening 154. The opening 154 is coaxially aligned with the center body 102 and/or the center passage 120. In particular embodiments, the opening 154 may partially define the center passage 120 and may be configured to receive the fuel or purge air cartridge (not shown) and/or a spark plug (not shown).
In various embodiments, as shown in FIGS. 4 and 5, the baffle plate 110 includes and upstream or inlet side 156 axially spaced from a downstream or outlet side 158. A plurality of passages 160 extend generally axially through the upstream and downstream sides 156, 158. In various embodiments, the passages 160 are annularly arranged about the opening 154 of the baffle plate 110. The passages 160 may be arranged so as to form multiple circumferential rows where each row is radially separated from an adjacent row. Although the passages 160 are shown as having a generally circular cross sectional shape, it is to be understood that the passages 160 are not limited to any particular cross sectional shape unless specifically provided in the claims. For example, the passages 160 may have an arcuate, rectangular, triangular or trapezoidal cross sectional shape.
As shown in FIGS. 4 and 5, each passage 160 includes an inlet 162 defined along the upstream side 156 and an outlet 164 defined along the downstream side 158. The inlets 162 are in fluid communication with the premix flow passage 106. At least some of the passages 160 provide for fluid flow from the premix flow passage 106, through the baffle plate 110 and into the combustion chamber 60 (FIG. 2). The inlets 162 and the outlets 164 may be provided with different shapes, such that the fuel-air mixture entering the passages 160 is maximized at the inlets 162 and that discrete fuel-air jets are formed at the outlets 164. To minimize the likelihood of flame holding, the transition from the shape of the inlets 162 to the shape of the outlets 164 is smooth. In one embodiment, the inlet shape 162 has a larger area than the outlet shape 164, thereby accelerating the flow of the fuel-air mixture through the baffle plate 110.
FIG. 6 provides a cross sectioned downstream perspective view of the downstream portion 112 of the fuel nozzle assembly 100 including the baffle plate 110 as shown in FIGS. 4 and 5, according to one embodiment of the present invention. As shown in FIG. 6, the upstream side 156 of the baffle plate 110 includes and/or defines a plurality of concentrically aligned annular walls 166 that extend axially and radially with respect to centerline 114 and circumferentially about the opening 154. Each annular wall 166 is radially spaced from an adjacent annular wall 166 or walls. The annular walls 166 radially separate or isolate the inlets 162 of radially adjacent passages 160. A plurality of circumferentially spaced radial walls 168 extend radially between radially adjacent annular walls 166. The radial walls 168 circumferentially separate or isolate circumferentially adjacent passages 160 and/or inlets 162 to adjacent passages 160. The annular walls 166 and the radial walls 168 surround and/or at least partially define the inlets 162 to each passage 160, thereby maximizing the area through which the fuel-air mixture flows into the baffle plate 110 and minimizing the dead space that would otherwise occur between adjacent passages, if their circular shape were continuous from the inlets 162 to the outlets 164.
FIG. 7 provides a cross sectioned downstream perspective view of the downstream portion 112 of the fuel nozzle assembly 100 including the baffle plate 110 as shown in FIGS. 4 and 5, according to one embodiment of the present invention. As shown in FIG. 7, the upstream side 156 of the baffle plate 110 may include one or more peaks 170 and one or more valleys 172 that at least partially define and/or surround the inlets 162 to one or more of the passages 160. The peaks 170 and valleys 172 may alternate, such that a valley 172 is between adjacent peaks 170 and a peak 170 is between adjacent valleys 172. In one exemplary embodiment, a cross-sectional profile of the baffle plate 110 may be generally waveform, with arcuate peaks 170 and valleys 172. Alternatively, the peaks 170 and valleys 172 may be linear, may be triangular with small radii at the apex of the peaks 170 (i.e. highest axial point) and/or at the valleys 172 (i.e. lowest axial point), or may have any other suitable cross-sectional profiles. In particular embodiments, an outer row 174 of the peaks 170 may blend into or with an inner surface 176 of the baffle plate 110.
FIG. 8 provides a downstream perspective view of a cross sectioned portion of the fuel nozzle assembly 100, according to one embodiment of the present invention, and also provides an operational flow diagram of a portion of the fuel nozzle assembly 100. During operation, as shown in FIG. 8, compressed air 18 from the head end 54 of the combustor 24 (FIG. 2) is routed through the flow conditioning section 142, while fuel 20 is routed through the various fuel circuits 140 (FIGS. 4 and 5) defined within the center body 102 to the plurality of fuel ports 108. In particular embodiments, the compressed air 18 may be preconditioned upstream from the conditioning portion 142 of the fuel nozzle assembly 100 as shown in FIGS. 4 and 5, thus manipulating the flow characteristics or flow profile of the compressed air 18 as it flows from the head end 54 of the combustor 24 into the premix passage 106 upstream from the plurality of fuel ports 108.
Fuel, as indicated by arrows 20 in FIG. 8, is then injected into the flow of compressed air 18 upstream from the inlets 162 of the baffle plate 110. The fuel 20 and compressed air 18 mix together within the premix passage 106, thus providing a fuel-air mixture as indicated by arrows 174 upstream from the inlets 162. The various surface features defined along the upstream or inlet side 156 of the baffle plate 110 such as the annular and radial walls 166, 168 as shown in FIGS. 6 and 8 or the peaks 170 and valleys 172 as shown in FIG. 7, provide generally aerodynamically clean inlets 162 to the passages 160, thus providing flame stabilization at and/or downstream from the outlets 164 of the passages 160. In addition or in the alternative, the passages 160 may promote further or more complete premixing of the fuel-air mixture 174 upstream from the combustion chamber 60, thus enhancing overall emissions performance of the combustor 24. The fuel-air mixture 174 enters the combustion chamber 60 in a flow direction that is substantially axial (that is, without the swirl, or tangential flow direction, typically associated with swirler or swozzle-type premixing fuel nozzles). As a result, the flame front is shorter and exhibits good flame stability.
This written description, which includes the best mode, uses examples to disclose the invention and to enable any person skilled in the art to practice the invention, including making and using any devices or systems.

Claims

A fuel nozzle assembly (100) comprising:
a center body (102);

an outer tube (104) that at least partially surrounds the center body;

a premix flow passage (106) defined radially between the center body and the outer tube;

a plurality of fuel ports (108) disposed between the center body and the outer tube within the premix flow passage; and

a baffle plate (110) that extends radially outwardly from the center body to the outer tube across a downstream end portion of the fuel nozzle assembly, wherein the baffle plate includes an upstream side (156) axially spaced from a downstream side (158) and a plurality of passages (160), wherein the passages provide for fluid flow from the premix flow passage through the baffle plate, characterized in that

the upstream side includes a plurality of concentrically aligned annular walls (166) and a plurality of circumferentially spaced radial walls (168) that extend radially between radially adjacent annular walls, wherein the annular walls and the radial walls at least partially define inlets (162) to each passage (160).
The fuel nozzle assembly (100) as in claim 1, wherein the upstream side includes one or more peaks (170) and one or more valleys (172) that at least partially define one or more respective inlets (162) to one or more respective passage (160) of the plurality of passages.
The fuel nozzle assembly (100) as in claim 2, wherein the peaks (170) and valleys (172) alternate such that a valley is defined between adjacent peaks and a peak is defined between adjacent valleys.
The fuel nozzle assembly (100) as in claim 1, wherein the baffle plate (110) comprises a center portion that defines an opening (154), wherein the opening is coaxially aligned with a center passage defined by the center body.
The fuel nozzle assembly (100) as in claim 1, wherein the plurality of fuel ports (108) is disposed along at least one of a ring concentrically disposed within the premix passage and concentrically aligned with the center body or a strut that extends radially between the center body and the outer tube.
The fuel nozzle assembly (100) as in claim 1, wherein the center body defines a center passage (120) configured to receive a cartridge.
The fuel nozzle assembly (100) as in claim 1, wherein the center body includes a converging portion (122).
A combustor (24) for a gas turbine (10), comprising:
a combustion chamber (60) defined within the combustor;

a fuel nozzle assembly (100) according to one of claims 1 to 4, 6 or 7 disposed upstream from the combustion chamber (60), said fuel nozzle assembly further comprising:
a ring manifold (132) disposed within the premix flow passage and concentric with the center body, the ring manifold defining the plurality of fuel ports (108) in fluid communication with a fuel circuit (140) of the fuel nozzle assembly; and wherein

the baffle plate (110) extends radially and circumferentially across a downstream end portion of the fuel nozzle assembly, and

each passage (160) has a respective inlet (162) defined along the upstream side (156) and an outlet (164) defined along the downstream side (158), wherein the passages provide for fluid flow from the premix flow passage through the baffle plate and into the combustion chamber.
The combustor (24) as in claim 8, wherein at least one strut (136) extends radially between the center body and the ring manifold, the at least one strut defining a fuel passage (138) therein and wherein the at least one strut defines at least one of the fuel ports (108) therethrough.
A gas turbine (10), comprising:
a compressor (16), a combustor (24) disposed downstream from the compressor and a turbine (28) disposed downstream from the combustor, wherein the combustor includes an end cover (42) coupled to an outer combustor casing (44), a combustion chamber (60) defined within the outer combustor casing and a fuel nozzle assembly (100) according to one of claims 1 to 7 that extends downstream from the end cover and terminates upstream from the combustion chamber;

wherein the plurality of fuel ports (108) include a plurality of fuel ports in fluid communication with the premix passage; and
the baffle plate (110) extends radially and circumferentially across a downstream end portion of the fuel nozzle assembly, wherein the passages provide for fluid flow from the premix flow passage through the baffle plate and into the combustion chamber.