U.S. patent application number 13/798012 was filed with the patent office on 2014-11-20 for system and method for tube level air flow conditioning.
This patent application is currently assigned to General Electric Company. The applicant listed for this patent is General Electric Company. Invention is credited to Gregory Allen Boardman, Ronald James Chila, Patrick Benedict Melton, James Harold Westmoreland.
Application Number | 20140338340 13/798012 |
Document ID | / |
Family ID | 51419081 |
Filed Date | 2014-11-20 |
United States Patent
Application |
20140338340 |
Kind Code |
A1 |
Melton; Patrick Benedict ;
et al. |
November 20, 2014 |
SYSTEM AND METHOD FOR TUBE LEVEL AIR FLOW CONDITIONING
Abstract
A system includes a multi-tube fuel nozzle. The multi-tube fuel
nozzle includes multiple tubes. Each tube includes a first end, a
second end, and an annular wall disposed about a central passage.
The first end is configured to be disposed about a fuel injector.
Each tube also includes an air flow conditioner having multiple air
ports disposed adjacent the first end. The multiple air ports
extend through the wall into the central passage.
Inventors: |
Melton; Patrick Benedict;
(Horse Shoe, NC) ; Chila; Ronald James;
(Greenfield Center, NY) ; Boardman; Gregory Allen;
(Greer, SC) ; Westmoreland; James Harold; (Greer,
SC) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
General Electric Company; |
|
|
US |
|
|
Assignee: |
General Electric Company
Schenectady
NY
|
Family ID: |
51419081 |
Appl. No.: |
13/798012 |
Filed: |
March 12, 2013 |
Current U.S.
Class: |
60/738 |
Current CPC
Class: |
F23D 14/62 20130101;
F23R 3/12 20130101; F23R 3/286 20130101 |
Class at
Publication: |
60/738 |
International
Class: |
F23R 3/28 20060101
F23R003/28; F23R 3/12 20060101 F23R003/12 |
Claims
1. A system, comprising: a multi-tube fuel nozzle, comprising: a
plurality of tubes, wherein each tube comprises: a first end; a
second end; an annular wall disposed about a central passage,
wherein the first end is configured to be disposed about a fuel
injector; and an air flow conditioner having a plurality of air
ports disposed adjacent the first end, wherein the plurality of air
ports extend through the wall into the central passage.
2. The system of claim 1, wherein the plurality of air ports are
circumferentially arranged about the annular wall.
3. The system of claim 2, wherein the plurality of air ports
comprises a first set of air ports and a second set of air ports,
wherein the second set of air ports are located downstream of the
first set of air ports relative to the first end.
4. The system of claim 3, wherein a first total area of each air
port of the first set of air ports is larger than a second total
area of each air port of the second set of air ports.
5. The system of claim 3, wherein the first set of air ports
comprises a first row and a second row of air ports
circumferentially arranged about the annular wall, and the first
row of air ports are offset from the second row of air ports in a
circumferential direction.
6. The system of claim 5, wherein the second set of air ports
comprises a third row and a fourth row of air ports
circumferentially arranged about the annular wall, and the third
row of air ports are offset from the fourth row of air ports in the
circumferential direction.
7. The system of claim 3, wherein the first set of air ports is
configured to guide air flow in a radial direction into the central
passage.
8. The system of claim 7, wherein the second set of air ports is
configured to guide the air with a swirling motion about a central
axis of the central passage.
9. The system of claim 1, wherein the plurality of air ports
comprise a plurality of sizes, shapes, angles, spacings, or any
combination thereof.
10. The system of claim 1, wherein each tube of the plurality of
tubes is configured to receive an equal distribution of air flow
via the air flow conditioner.
11. The system of claim 1, comprising a gas turbine engine or a
combustor having the multi-tube fuel nozzle.
12. A system, comprising: a combustor end cover assembly; a
multi-tube fuel nozzle coupled to the combustor end cover assembly,
comprising: a retainer plate; and a plurality of tubes disposed
between the end cover assembly and the retainer plate, wherein each
tube comprises: a first end adjacent the end cover assembly; a
second end adjacent the retainer plate; an annular wall disposed
about a central passage, wherein the first end is configured to be
disposed about a fuel injector; and an air flow conditioner having
a plurality of air ports disposed adjacent the first end, wherein
the plurality of air ports extend through the wall into the central
passage.
13. The system of claim 12, wherein each tube of the plurality of
tubes is configured to be individually removed from or installed
between the end cover assembly and the retainer plate.
14. The system of claim 13, wherein the retainer plate is
configured to be removed from the multi-tube fuel nozzle by sliding
the retainer plate along the plurality of tubes from the first end
to the second end of each tube upon removal of the end cover
assembly.
15. The system of claim 12, wherein the plurality of air ports are
circumferentially arranged about the annular wall.
16. The system of claim 15, wherein the plurality of air ports
comprises a first set of air ports and a second set of air ports,
wherein the second set of air ports are located downstream of the
first set of air ports relative to the first end.
17. The system of claim 16, wherein a first total area of each air
port of the first set of air ports is larger than a second total
area of each air port of the second set of air ports.
18. The system of claim 16, wherein the first set of air ports is
configured to guide air flow in a radial direction into the central
passage.
19. The system of claim 18, wherein the second set of holes is
configured to guide the air with a swirling motion about a central
axis of the central passage.
20. A system, comprising: a combustor end cover assembly; a
multi-tube fuel nozzle coupled to the combustor end cover assembly,
comprising: a retainer plate; and a tube disposed between the end
cover assembly and the retainer plate, wherein the tube comprises:
a first end adjacent the end cover assembly; a second end adjacent
the retainer plate; an annular wall disposed about a central
passage, wherein the first end is configured to be disposed about a
fuel injector; and an air flow conditioner having a plurality of
air ports disposed adjacent the first end, wherein the plurality of
air ports extend through the wall into the central passage.
Description
BACKGROUND OF THE INVENTION
[0001] The subject matter disclosed herein relates to tube level
air flow conditioning for turbine systems.
[0002] Gas turbine systems generally include one or more combustors
that combust a mixture of compressed air and fuel to produce hot
combustion gases. Unfortunately, existing combustors may receive
fuel and air at pressures and/or flow rates, which can fluctuate
due to various limitations of the combustors, fuel nozzles, and
associated equipment. These air and fuel fluctuations may drive or
cause fluctuations in the fuel to air ratio, thereby increasing the
possibility of flame holding, flashback, and/or increased emissions
(e.g., nitrogen oxides). Conventional systems can also be slower at
achieving mixing therefore reducing the overall efficiency of the
system. There is therefore a need for a system that can achieve
faster and more uniform fuel air mixing while also being durable
and easily maintainable.
BRIEF DESCRIPTION OF THE INVENTION
[0003] Certain embodiments commensurate in scope with the
originally claimed invention are summarized below. These
embodiments are not intended to limit the scope of the claimed
invention, but rather these embodiments are intended only to
provide a brief summary of possible forms of the invention. Indeed,
the invention may encompass a variety of forms that may be similar
to or different from the embodiments set forth below.
[0004] In accordance with a first embodiment, a system includes a
multi-tube fuel nozzle. The multi-tube fuel nozzle includes
multiple tubes. Each tube includes a first end, a second end, and
an annular wall disposed about a central passage. The first end is
configured to be disposed about a fuel injector. Each tube also
includes an air flow conditioner having multiple air ports disposed
adjacent the first end. The multiple air ports extend through the
wall into the central passage.
[0005] In accordance with a second embodiment a system includes a
combustor end cover assembly and a multi-tube fuel nozzle coupled
to the combustor end cover assembly. The multi-tube fuel nozzle
includes a retainer plate and multiple tubes disposed between the
end cover assembly and the retainer plate. Each tube includes a
first end adjacent the end cover assembly, a second end adjacent
the retainer plate, and an annular wall disposed about a central
passage. The first end is configured to be disposed about a fuel
injector. Each tube also includes an air flow conditioner having
multiple air ports disposed adjacent the first end. The multiple
air ports extend through the wall into the central passage.
[0006] In accordance with a third embodiment, a method for removal
of tubes from a multi-tube fuel nozzle includes removing the
multi-tube fuel nozzle having multiple tubes disposed between a
retainer plate and an end cover from a gas turbine engine. Each
tube includes a first end disposed adjacent the end cover and about
a fuel injector, a second end disposed adjacent the retainer plate,
and an annular wall disposed about a central passage. The method
also include removing the end cover from the multi-tube fuel
nozzle, removing the retainer plate from the multi-tube fuel nozzle
by sliding the retainer plate along the multiple tubes from the
second end to the first end of each tube, and removing at least one
tube from the multi-tube fuel nozzle.
BRIEF DESCRIPTION OF THE DRAWINGS
[0007] These and other features, aspects, and advantages of the
present invention will become better understood when the following
detailed description is read with reference to the accompanying
drawings in which like characters represent like parts throughout
the drawings, wherein:
[0008] FIG. 1 is a block diagram of an embodiment of a gas turbine
system having a multi-tube fuel nozzle within a combustor, wherein
the tubes are configured to uniformly distribute air;
[0009] FIG. 2 is a cutaway side view of the embodiment of a gas
turbine system of FIG. 1;
[0010] FIG. 3 is a cutaway side view of an embodiment of the
combustor of FIG. 2, taken within line 3-3, illustrating a
multi-tube fuel nozzle coupled to an end cover assembly of the
combustor;
[0011] FIG. 4 is an exploded perspective view of the multi-tube
fuel nozzle and end cover assembly of FIG. 3;
[0012] FIG. 5 is a partial cross-sectional side view of the
combustor of FIG. 3, illustrating multiple tubes and fuel injectors
of the multi-tube fuel nozzle;
[0013] FIG. 6 is a cross-sectional side view of an embodiment of
the first and second ends of an individual tube and respective fuel
injector of the multi-tube fuel nozzle of FIG. 5;
[0014] FIG. 7 is a perspective view of an embodiment of an
individual mixing tube, illustrating an air flow conditioner with
air ports in the mixing tube;
[0015] FIG. 8 is a partial perspective view of an embodiment of the
mixing tube of FIG. 7, taken within line 8-8, illustrating details
of an air flow conditioner with air ports along the first end of
the mixing tube;
[0016] FIG. 9 is a partial side view of an embodiment of the first
end of the mixing tube of FIG. 7, illustrating an air flow
conditioner with air ports;
[0017] FIG. 10 is a cross-sectional view of an embodiment of the
mixing tube of FIG. 9, taken along line 10-10 through air ports of
the air flow conditioner;
[0018] FIG. 11 is a cross-sectional side view of an embodiment of
the mixing tube of FIG. 9, taken along line 11-11 through air ports
of the air flow conditioner;
[0019] FIG. 12 is a cross-sectional side view of an embodiment of
the mixing tube of FIG. 9, taken along line 12-12 through air ports
of the air flow conditioner; and
[0020] FIGS. 13-16 are a series of views of an embodiment of a
multi-tube fuel nozzle and a combustor end cover, illustrating a
method of removal of tubes of the multi-tube fuel nozzle.
DETAILED DESCRIPTION OF THE INVENTION
[0021] One or more specific embodiments of the present invention
will be described below. In an effort to provide a concise
description of these embodiments, all features of an actual
implementation may not be described in the specification. It should
be appreciated that in the development of any such actual
implementation, as in any engineering or design project, numerous
implementation-specific decisions must be made to achieve the
developers' specific goals, such as compliance with system-related
and business-related constraints, which may vary from one
implementation to another. Moreover, it should be appreciated that
such a development effort might be complex and time consuming, but
would nevertheless be a routine undertaking of design, fabrication,
and manufacture for those of ordinary skill having the benefit of
this disclosure.
[0022] When introducing elements of various embodiments of the
present invention, the articles "a," "an," "the," and "said" are
intended to mean that there are one or more of the elements. The
terms "comprising," "including," and "having" are intended to be
inclusive and mean that there may be additional elements other than
the listed elements.
[0023] The present disclosure is directed to systems for
conditioning air flow within a multi-tube fuel nozzle of a turbine
system. The turbine system may include one or more multi-tube fuel
nozzles. Each multi-tube fuel nozzle includes multiple tubes (e.g.,
premixing tubes) wherein each tube has an air flow conditioner and
a fuel injector. In the multi-tube fuel nozzle, pressurized air may
enter each mixing tube through an air flow conditioner, which may
include multiple air ports extending through an annular wall of the
mixing tube. The annular wall of each tube is disposed about a
central passage. The individual mixing tubes are each configured to
be disposed about a fuel injector, which disperses fuel into the
central passage of the mixing tube, creating the fuel air mixture.
The air ports of the air flow conditioners are configured to
condition the air entering the mixing tubes to target specific
pressure drops and more uniformly mix air and fuel before it is
subsequently directed into the combustion region. The air ports of
each air flow conditioner may be configured with various features
to optimize air side system pressure drops and best provide uniform
air flow. Accordingly, the air ports of each air flow conditioner
may be circumferentially arranged about the annular wall to take
advantage of an air pressure profile that is substantially uniform
circumferentially. The air flow conditioner on each mixing tube may
include a first set and a second set of air ports, wherein the
second set of air ports are located downstream of the first set of
air ports. The second set of air ports may have a total area that
is larger than the area of the first set of air ports to compensate
for a region of lower air pressure area downstream in the fuel
nozzle air plenum. The sets of air ports of each air flow
conditioner may include multiple rows that are offset from each
other in a circumferential direction to more equally distribute air
pressure as the compressed air moves downstream. The air ports of
each air flow conditioner may be configured to guide air flow into
the mixing tubes in a substantially radial direction, but in other
embodiments they might be configured to guide the air flow in a
direction having various directional components (e.g., radial,
angled axially upstream, angled axially downstream, angled
circumferentially clockwise, angled circumferentially
counterclockwise, of any combination thereof). These angled air
ports (e.g., angled circumferentially clockwise or
counterclockwise) may impart swirl to the air directed within the
central passage of the mixing tubes which can increase the
uniformity of the fuel-air mixture. The tubes may each be
configured based on their location within the multi-tube fuel
nozzle to receive substantially equal distribution of air flow.
[0024] Turning now to the drawings and referring first to FIG. 1, a
block diagram of an embodiment of a gas turbine system 10 is
illustrated. The gas turbine system 10 includes one or more fuel
nozzles 12 (e.g., multi-tube fuel nozzles), a fuel supply 14, and a
combustor 16. The fuel nozzle 12 receives compressed air 18 from an
air compressor 20 and fuel 22 from a fuel supply 14. Although the
present embodiments are discussed in context of air as an oxidant,
the present embodiments may use air, oxygen, oxygen-enriched air,
oxygen-reduced air, oxygen mixtures, or any combination thereof. As
discussed in further detail below, the fuel nozzle 12 includes a
plurality of fuel injectors 24 (e.g., 10 to 1000) and associated
mixing tubes 26 (e.g., 10 to 1000), wherein each mixing tube 26 has
an air flow conditioner 27 with air ports 28 (e.g., 1 to 100) to
direct and condition an air flow into the respective tube 26, and
each mixing tube 26 has a respective fuel injector 24 (e.g., in a
coaxial or concentric arrangement) to inject fuel into the
respective tube 26. In turn, each mixing tube 26 mixes the air and
fuel along its length, and then outputs an air-fuel mixture 30 into
the combustor 16. In certain embodiments, the mixing tubes 26 may
be described as micromixing tubes, which may have diameters between
approximately 0.5 to 2, 0.75 to 1.75, or 1 to 1.5 centimeters. The
mixing tubes 26 may be arranged in one or more bundles (e.g., 1, 2,
3, 4, 5, 6, 7, 8, 9, 10, or more) of closely spaced tubes,
generally in a parallel arrangement relative to one another. In
this configuration, each mixing tube 26 is configured to mix (e.g.,
micromix) on a relatively small scale within each mixing tube 26,
which then outputs a fuel-air mixture 30 into the combustion
chamber. The air flow conditioner 27 (e.g., with ports 28) of the
disclosed embodiments provides air conditioning on a tube level
(i.e., for each individual mixing tube 26), such that the flow
and/or pressure of air into each tube 26 and among the plurality of
tubes 26 can be controlled to provide better mixing of fuel and
air.
[0025] The combustor 16 ignites the fuel-air mixture 30, thereby
generating pressurized exhaust gases 32 that flow into a turbine
34. The pressurized exhaust gases 32 flow against and between
blades in the turbine 34, driving the turbine 34 to rotate. The
turbine blades are coupled to a shaft 36, which in turn also
rotates as the exhaust gases 32 escape the combustor 16.
Eventually, the exhaust 32 of the combustion process exits the
turbine system 10 via an exhaust outlet 38. Blades within the
compressor 20 are additionally coupled to the shaft 36, and rotate
as the shaft 36 is driven to rotate by the turbine 34. The rotation
of the blades within the compressor 20 compresses air 40 that has
been drawn into the compressor 20 by an air intake 42. The
resulting compressed air 18 is then fed into the multi-tube fuel
nozzle 12 of the combustors 16, as discussed above, where it is
mixed with fuel 22 and ignited, creating a substantially
self-sustaining process. Further, the shaft 36 may be coupled to
load 44. As will be appreciated, the load 44 may be any suitable
device that may generate power via the rotational output of a
turbine system 10, such as a power generation plant or an external
mechanical load. The relationship between the consistency of the
fuel-air mixture 30 and the efficient operation of the gas turbine
system 10 can therefore be appreciated. The implementation of the
multiple mixing tubes 26, each having an air flow conditioner 27
with multiple air ports 28 to condition the air 18 will be
discussed in greater detail below.
[0026] FIG. 2 shows a cutaway side view of the embodiment of gas
turbine system 10 of FIG. 1. As depicted, the embodiment includes a
compressor 20, which is coupled to an annular array of combustors
16. Each combustor 16 includes at least one fuel nozzle 12 (e.g., a
multi-tube fuel nozzle) which feeds the fuel-air mixture 30 to a
combustion chamber 46 located within each combustor 16. As will be
discussed in detail below, certain embodiments of the mixing tubes
26 of the fuel nozzle 12 include unique features to more uniformly
distribute the compressed air 18 creating a more uniform fuel-air
mixture 30. Uniformity of the fuel-air mixture 30 provides more
efficient combustion, thereby increasing performance and reducing
emissions. Combustion of the fuel-air mixture 30 within combustors
16, as mentioned above in regard to FIG. 1, causes vanes or blades
within the turbine 24 to rotate as exhaust gases 22 (e.g.,
combustion gases) pass toward an exhaust outlet 38. Throughout the
discussion, a set of axes will be referenced. These axes are based
on a cylindrical coordinate system and point in an axial direction
48, a radial direction 50, and a circumferential direction 52. For
example, the axial direction 48 extends along a length or
longitudinal axis 54 of the fuel nozzle 12, the radial direction 50
extends away from the longitudinal axis 54, and the circumferential
direction 52 extends around the longitudinal axis 54.
[0027] FIG. 3 is a cutaway side view of the combustor 16 of the gas
turbine system 10 of FIG. 2 and taken within line 3-3 of FIG. 2. As
shown, the combustor 16 includes a head end 56 and a combustion
chamber 46. The fuel nozzle 12 is positioned within the head end 56
of the combustor 16. Within the fuel nozzle 12 are suspended the
multiple mixing tubes 26 (e.g. air-fuel pre-mixing tubes).
Illustrated is an embodiment of the mixing tubes 26 having air flow
conditioners 27 with air ports 28 that enable compressed air 18 to
enter and mix with fuel 22. The mixing tubes 26 generally extend
axially between an end cover assembly 58 of the combustor 16 and a
cap face assembly 60 of the fuel nozzle 12. The mixing tubes 26 may
be coupled to the end cover assembly 58 and the cap face assembly
60, as further described below. The end cover assembly 58 may
include a fuel inlet 62 and fuel plenum 64 for providing fuel 22 to
multiple fuel injectors 24. As discussed above, each individual
fuel injector 24 is coupled to an individual mixing tube 26. During
the combustion process, fuel 22 moves axially through each of the
mixing tubes 26 from the end cover assembly 58 (via the fuel
injectors 24) through the cap face assembly 60 and to the
combustion chamber 46. The direction of this movement along the
longitudinal axis 54 of the fuel nozzle 12 will be referred to as
the downstream direction 66. The opposite direction will be
referred to as the upstream direction 68.
[0028] As described above, the compressor 20 compresses air 40
received from the air intake 42. The resulting flow of pressurized
compressed air 18 is provided to the fuel nozzles 12 located in the
head end 56 of the combustor 16. The air enters the fuel nozzles 12
through air inlets 70 to be used in the combustion process. More
specifically, the pressurized air 18 flows from the compressor 20
in an upstream direction 68 through an annulus 72 formed between a
liner 74 (e.g., an annular liner) and a flow sleeve 76 (e.g., and
annular flow sleeve) of the combustor 16. At the end of this
annulus 72, the compressed air 18 is forced into the air inlets 70
of the fuel nozzle 12 and fills an air plenum 78 within the fuel
nozzle 12. The pressurized air 18 in the air plenum 78 then enters
the multiple mixing tubes 26 through the air ports 28 of the air
flow conditioner 27. In addition to allowing the air 18 to enter
the mixing tubes 26, the air ports 28 of the air flow conditioner
27 may condition the air 18 in various ways, as discussed further
below. Inside the mixing tubes 26, the air 18 is then mixed with
the fuel 22 provided by the fuel injectors 24. The fuel-air mixture
30 flows in a downstream direction 66 from the mixing tubes 26 into
the combustion chamber 46, where it is ignited and combusted to
form the combustion gases 22 (e.g., exhaust gases). The combustion
gases 32 flow from the combustion chamber 46 in the downstream
direction 66 to a transition piece 80. The combustion gases 22 then
pass from the transition piece 80 to the turbine 34, where the
combustion gases 22 drive the rotation of the blades within the
turbine 34.
[0029] FIG. 4 illustrates an exploded perspective view of the
multi-tube fuel nozzle 12 taken within line 4-4 of FIG. 3. This
figure further illustrates the arrangement, according to some
embodiments, of the multiple fuel injectors 24 on the end cover 58
and their relation to the multiple mixing tubes 26. The fuel
plenums 64 distribute the fuel 22 to the fuel injectors 24. As
discussed above, the mixing tubes 26 are arranged to be disposed
between the end cover assembly 58 and the cap face assembly 60. The
individual mixing tubes 26 are each paired with an individual fuel
injector 24 and are configured to be disposed about that fuel
injector 24 (e.g., in a coaxial or concentric arrangement). The air
ports 28 are located on this upstream 68 side of the mixing tubes
26 in proximity to the fuel injectors 24. In certain embodiments,
the fuel injectors 24 may be removably coupled to the end cover
assembly 58.
[0030] Additionally, FIG. 4 illustrates a support structure 82
(e.g., annular barrel, fuel nozzle cap) of the fuel nozzle 12 that
surrounds the mixing tubes 26 and other structures within the fuel
nozzle 12. The support structure 82 extends from the end cover
assembly 58 to the cap face assembly 60, generally protects and
supports the structures positioned within the fuel nozzle 12, and
defines the air plenum 78 within the fuel nozzle 12. The air inlets
70 are located on the support structure 82 and direct the
compressed air 18 radially into the air plenum 78 on the interior
of the fuel nozzle 12. A retainer plate 84 is located upstream 68
and proximate to the removable cap face assembly 60. In certain
embodiments, the nozzle 12 includes an annular air flow
conditioning diffuser 86 surrounding the air inlets 70.
[0031] FIG. 5 is a partial cross-sectional side view of the
combustor 16 as taken within line 5-5 of FIG. 3. The head end 56 of
the combustor 16 contains a portion of the multi-tube fuel nozzle
12. The support structure 82 surrounds the multi-tube fuel nozzle
12 and the multiple mixing tubes 26. As discussed above, in some
embodiments, each mixing tube 26 may extend axially between the end
cover assembly 58 and the cap face assembly 60. The mixing tubes 26
may further extend through the cap face assembly 60 to feed the
fuel-air mixture 30 directly to the combustion chamber 46. Each
mixing tube 26 is positioned to surround a fuel injector 24 (e.g.,
coaxial or concentric arrangement), such that the injector 24
receives fuel 22 from the fuel plenum 64 and directs the fuel into
the tube 26. The fuel plenum 64 is fed fuel 22 entering the fuel
inlet 62 located on the end cover assembly 58.
[0032] As described above, compressed air 18 enters the fuel nozzle
12 through air inlets 70, which may be surrounded by a diffuser 86.
The diffuser 86 may be annular and configured to pre-condition and
distribute the pressurized air into the fuel nozzle 12 across the
mixing tubes 26 in a variety of directions. The direction of the
air flow within the fuel nozzle 12 will be substantially radially
inward 88, but may have an upstream 68 component or downstream 66
component. The air flow will vary across mixing tubes 26 that are
located in more radially outward 90 locations within the fuel
nozzle 12, closer to the air inlets 70. After entering the fuel
nozzle 12 through the air inlet 70 and moving across the mixing
tubes 26, the pressurized air 18 enters each mixing tube 26 through
one or more air ports 28 of an air flow conditioner 27. In certain
embodiments, the configuration of air ports 28 of the air flow
conditioner 27 is varied among individual mixing tubes 26 based on
their radial 50 locations within the fuel nozzle air plenum 78.
This customization can compensate for the variations in air
pressure and movement across the mixing tubes 26, namely the
pressure drop that occurs in the radially inward 88 direction. In
certain embodiments, the axial 48 positions of the air ports 28
along the mixing tubes 26 may be varied to compensate for axial 48
variations in air pressure. For additional management of the flow
of pressurized air 18 the air ports 28 of the air flow conditioner
27 may be configured to have any of a variety of shapes, sizes, and
arrangements as will be further discussed below. As also shown in
FIG. 5, in some embodiments, the retainer plate 84 and/or an
impingement plate 92 may be positioned within the fuel nozzle 12
surrounding the downstream 66 end of the mixing tubes 26 generally
proximate to the cap face assembly 60. The impingement plate 92 may
include a plurality of impingement cooling orifices, which may
direct jets of air to impinge against a rear surface of the cap
face assembly 60 to provide impingement cooling.
[0033] Illustrated in FIG. 6 is a cross-sectional view of an
individual mixing tube 26 and fuel injector 24, as taken within
line 6-6 of FIG. 5. The central portion of tube 26 has been omitted
to show greater detail of the first and second ends 94 and 96. The
fuel injector 24 may be generally positioned within a central
passage 98 at the first end 94 (e.g., upstream 68 end) of each
mixing tube 26. This first end 94 is located on the upstream 68
side of the multi-tube fuel nozzle 12 adjacent to the end cover
assembly 58. In certain embodiments the air ports 28 of the air
flow conditioner 27 are located at or near this first end 94
generally proximate to the fuel injector 24. In other embodiments,
the air ports 28 of the air flow conditioner 27 are located in
locations further upstream 68 or downstream 66 from the fuel
injector 24. The location of the air ports 28 can be configured to
selectively direct the air 18 in various paths depending on the
flow of fuel 22 and pressurized air 18 in a specific location
within the fuel nozzle 12. In some embodiments, the retainer plate
84 may support a second end 96 of the mixing tubes 26 located on
the downstream 66 side. In certain embodiments, the retainer plate
84 may additionally help secure the second end 96 of the mixing
tubes 26 to the impingement plate 82.
[0034] FIG. 6 also illustrates an embodiment of the spatial
relationship among the mixing tubes 26, the cap face assembly 60
and/or the end cover assembly 58. In some embodiments, the mixing
tubes 26 may be attached to components within the head end 56 of
the combustor 16, such as the cap face assembly 60, the retainer
plate 84, and/or the impingement plate 92 by various fasteners or
connections, such as weld, brazed joints, brackets, threaded
fasteners, snap-fits, joints, or other connections. In other
embodiments, the mixing tubes 26 are held in a floating
configuration and are merely supported by one or more of the cap
face assembly 60, the retainer plate 84, the impingement plate 92,
various springs, or other supporting structures. Such floating
configurations may advantageously accommodate thermal growth of the
mixing tubes 18 and other components of the combustor 14. Floating
configurations also allow the customization and configuration of
mixing tubes 26 with various air port 28 configurations to be more
easily made. If fuel-air mixtures 20 are found to be non-uniform,
individual tubes 26 may be easily removed and replaced with tubes
26 that have different air port 28 (e.g. air flow conditioner 27)
configurations that better compensate for air pressure variations
within the fuel nozzle 12. The floating configurations may
additionally be implemented by the inclusion of an axial spring 100
to provide resilient axial 48 support and constraint to the
movement of the mixing tubes 26. In accordance with the illustrated
embodiment, the axial spring 100 may be positioned between a
retainer plate 84 and impingement plate 92. Further, a radial
spring 102 may be located between the fuel injector 24 and the
first end 94 of the mixing tube 26, and may provide resilient
radial 50 constraint to the movement and thermal growth of the
mixing tube 26. There may further be features implemented such as
additional springs, channels and/or guides, to block
circumferential 52 movement of the mixing tubes 26.
[0035] As further illustrated in FIG. 6, the fuel injector 24 has
an annular wall 103 around an inner fuel passage 104, which leads
to one or more fuel ports 106 in a tapered portion 108 of the fuel
injector 24 disposed inside of the mixing tube 26 (e.g., in a
coaxial or concentric arrangement). In operation, the fuel injector
24 flows fuel 22 from the fuel plenum 64 downstream 66 to a region
inside of the mixing tube 26 via the one or more fuel ports 106. In
certain embodiments, the fuel ports 106 may be positioned axially
upstream 68, axially downstream 66, axially aligned with, or any
combination thereof, relative to the air ports 28. In the
illustrated embodiment, the fuel ports 106 are located on the
tapered portion 108, which may have a linear or curved taper in the
downstream direction 66. For example, the tapered portion 108 may
be formed as a conical wall, an inwardly curved annular wall (e.g.,
curved inwardly toward the axis of the injector 24), an outwardly
curved annular wall (e.g., curved outwardly away from the axis of
the injector 24), or a combination thereof. In the illustrated
embodiment, the tapered portion 108 extends from a first position
upstream 68 of the air ports 28 to a second position downstream 66
of the air ports 28 of the mixing tube 26. As illustrated, the
tapered portion 108 of the fuel injector 24 gradually decreases in
diameter (i.e., converges) in the downstream direction 66, thereby
gradually increasing the cross-sectional area between the fuel
injector 24 and the mixing tube 26 in the downstream direction 66.
In this manner, the illustrated embodiment provides a gradual
pressure drop between the fuel injector 24 and the mixing tube 26,
thereby helping to improve the flow and mixing of fuel and air. In
the illustrated embodiment, the air flow conditioner 27 (e.g., air
ports 28) along the mixing tube 26 and the fuel ports 106 along the
fuel injector 24 (e.g., tapered portion 108) are both disposed
upstream from a tip 109 of the fuel injector 24, such that the air
and fuel at least partially mix along the decreasing
cross-sectional area between the fuel injector 24 and the mixing
tube 26. Furthermore, the illustrated air ports 28 are disposed
upstream of the fuel ports 106 to increase the pressure upstream of
the fuel ports 106.
[0036] In certain embodiments, the fuel ports 106 and the air ports
28 (e.g., axes of the ports) may be oriented in the radial
direction 50, the axial direction 48, an axially upstream angle, an
axially downstream angle, the circumferential direction 52 (e.g.,
clockwise or counter clockwise), or any combination thereof.
Furthermore the fuel and air ports 106 and 28 may be oriented in
the same direction and/or different directions. For example, the
fuel ports 106 may be oriented radially outward while the air ports
28 may be oriented radially outward, and the fuel ports 106 may be
oriented in the same and/or opposite circumferential directions 52
as the air ports 28. The circumferential direction of ports 28
and/or 106 may be used to facilitate a swirling flow. The
orientation of the fuel ports 106 and air ports 28 also may vary
circumferentially 52 around each tube 26, axially along each tube
26, or any combination thereof. Furthermore, the orientation of the
fuel ports 106 and air ports 28 also may vary from one tube 26 to
another tube 26 among the plurality of mixing tubes 26. In this
manner, the orientation of the fuel ports 106 and air ports 28 may
be used to improve the fuel-air mixing in each tube 26, while
adjusting for flow and pressure variations within the multi-tube
fuel nozzle 12. This ability to vary the orientation of ports 28
and 106, particularly the air ports 28, enables tube-level air flow
conditioning among the plurality of mixing tubes 26.
[0037] The number, size, and/or shape of the fuel ports 106 and the
air ports 28 may be the same and/or different from one another. In
certain embodiments, the air ports 28 may include hole diameters
that are equal to, greater than, and/or less than hole diameters of
the fuel ports 106. For example, the air ports 28 may have
diameters of approximately 0.1 to 10 times, 0.2 to 5 times, 0.3 to
4 times, 0.4 to 3 times, or 0.5 to 2 times the diameter of the fuel
ports 106. In certain embodiments, the number of air ports 28 may
be equal to, greater than, and/or less than the number of the fuel
ports 106. For example, the number of air ports 28 may be
approximately 0.5 to 50 times, 0.5 to 25 times, 1 to 10 times, or 2
to 5 times the number of fuel ports 106. As an example, the air
flow conditioner 27 of each mixing tube 26 may have 5 to 500, 10 to
100, or 15 to 50 air ports 28. In certain embodiments, the shape of
the fuel ports 106 and the air ports 28 may include circular ports,
rectangular ports, oval ports, triangular ports, polygonal ports,
or any combination thereof. Along with the variation in the
orientation, the number, size, and/or shape of the fuel ports 106
and air ports 28 also may vary circumferentially 52 around each
tube 26, axially along each tube 26, or any combination thereof.
Furthermore, the number, size, and/or shape of the fuel ports 106
and air ports 28 also may vary from one tube 26 to another tube 26
among the plurality of mixing tubes 26. In this manner, the number,
size, and/or shape of the fuel ports 106 and air ports 28 may be
used to improve the fuel-air mixing in each tube 26, while
adjusting for flow and pressure variations within the multi-tube
fuel nozzle 12. This ability to vary the number, size, and/or shape
of ports 28 and 106, particularly the air ports 28, enables
tube-level air flow conditioning among the plurality of mixing
tubes 26.
[0038] FIG. 7 is an illustration of a single mixing tube 26
separate from the fuel nozzle 12. In certain embodiments, the
mixing tubes 26 may be removable from the fuel nozzle 12 for
repair, inspection, or replacement. As discussed above, the mixing
tubes 26 may be selectively removed and replaced within mixing
tubes having alternate configurations of air ports 28 that may
better compensate for pressure drops within the fuel nozzle 12. A
method of removal and replacement of the mixing tubes 26 will be
discussed in greater detail below. FIG. 7 additionally illustrates
an entire mixing tube 26, with a first end 94, wherein the air
ports 28 are generally located in some embodiments, and a second
end 96, wherein the mixing tube 26 is coupled to the cap face
assembly 60, retainer plate 84 and/or impingement plate 92. Each
mixing tube 26 may further have any of a variety of shapes and
sizes. In some embodiments, each mixing tube 26 may have a
generally cylindrical shape, and may have a generally circular
cross-section, for example. Additionally, in some typical
embodiments, the mixing tube 26 may have a diameter of
approximately 5 to 20 mm, 5 to 10 mm, 10 to 15 mm, and all
subgroups therebetween. For example, a mixing tube 26 may have a
diameter of 5, 10, 15, or 20 millimeters, or any other diameter. In
certain embodiments, the mixing tube 26 may have a diameter of
approximately 6.35 millimeters. It should be understood that all
mixing tubes 26 within the combustor 16 may have a substantially
similar diameter, but that in certain embodiments it may be
advantageous for the mixing tubes 26 to have a variety of
diameters. Furthermore, each mixing tube 26 may have an axial
length of approximately 10 to 300 cm, 20 to 200 cm, 30 to 150 cm,
or any incremental length or range within these ranges. For
example, each mixing tube 26 may have an axial length of 10, 15,
20, 35, 30, 75, 80, 85, 90, or 150 cm, or any other length. In
certain embodiments, the mixing tubes 26 within the combustor 16
may have substantially similar lengths, although in some
embodiments the mixing tubes 26 may have two or more different
lengths. Furthermore, the air flow conditioner 27 (e.g., air ports
28) may be located along any axial portion of each tube 26, such as
within 0 to 10, 0 to 20, 0 to 30, 0 to 40, or 0 to 50 percent of
the length of each tube 26 measured from the upstream end 94 of the
tube 26. The air flow conditioner 27 also may include one or more
groups of closely spaced air ports 28 at one or more axial regions
along each tube 26.
[0039] FIG. 8 is a detailed view of the first end 94 of the mixing
tube 26 of FIG. 7, illustrating one embodiment of the air flow
conditioner 27 (e.g., air ports 28) on a mixing tube 26. As
discussed below, the air ports 28 may have a variety of shapes,
sizes, orientations, numbers, and configurations. FIG. 8
illustrates a configuration with two sets 110 and 112 of elliptical
air ports 28 arranged circumferentially 52 around the mixing tube
26, wherein the first set 110 of air ports 28 is located axially
upstream 68 from the second set 112 of air ports 28. In this
embodiment, the individual air ports 28 of the first set 110 have a
cross-sectional area 114 that is substantially larger than the
cross-sectional area 114 of the air ports 28 of the second set 112.
The larger area 114 of the more downstream air ports 28 can
compensate for the downstream drop in pressure experienced across
the tubes 26 within the air plenum 78. In other embodiments, air
ports 28 may be circular, teardrop shaped or rectangular in
cross-sectional shape, or any other shape. Each illustrated set 110
and 112 of air ports 28 includes a plurality of rows 116 and 118
(e.g., two rows) of air ports 28 evenly spaced circumferentially 52
about the mixing tube 26, with the air ports 28 of the first row
116 being offset in the axial direction 48 and the circumferential
direction 52 (e.g., staggered) from the air ports 28 in the second
row 118. In some embodiments, subsequent rows 118 may not be
circumferentially 52 offset (e.g., staggered), but may instead be
circumferentially aligned (e.g., in an axial line) with previous
rows 116 of air ports 28. In other embodiments, subsequent rows 118
may be partially offset from each other. In some embodiments, the
air ports 28 may range in area 114 from about 1 square mm to 100
square mm, 10 square mm to 50 square mm, 25 square mm to 75 square
mm, or any subgroup therebetween. For example, the individual air
ports 28 may have an area of 1, 5, 10, 15, 20, 25, 30, 75, 80, 85,
90, 95, or 100 square millimeters, or any other area. In the
illustrated embodiment, the air flow conditioner 27 includes two
rows 116 and 118 of air ports 28 in two sets 110 and 112 of air
ports 28. In other embodiments, the air flow conditioner 27 may
include 1 to 1000, 2 to 500, 3 to 250, 4 to 100, or 5 to 25 or more
sets and rows of air ports 28 with different sizes, shapes,
orientations, patterns, or a combination thereof. For example, the
air flow conditioner 27 may have 1 to 100 sets of differently sized
air ports 28, wherein each set has 1 to 100 rows of equal or
differently spaced, angled, or shaped air ports 28. By further
example, the size, number, and/or angle of the air ports 28 may be
the same, increase, and/or decrease in the axial direction 48
and/or the circumferential direction 52 along each mixing tube 26.
In certain embodiments, the air ports 28 may gradually increase or
decrease (or alternate) in diameter from one row to another along
the mixing tube 26.
[0040] FIG. 9 is an embodiment of the air flow conditioner 27
(e.g., air ports 28) on the first end 94 of a mixing tube 26,
wherein the air ports 28 are substantially the same shape and
cross-sectional area 114. An embodiment of air ports 28 such as
this may take advantage of an area where negligible pressure drop
is expected in either the axial 48 or circumferential 52
directions. The air ports 28 of this embodiment are arranged in six
rows 116. The axial 48 distance between each row 116 is equal and
the air ports 28 of each row 116 are evenly circumferentially 52
spaced about the mixing tube 26. Additionally, each row 116 is
fully offset from the next row 118, e.g., staggered in the
circumferential direction 52.
[0041] FIG. 10 is cross-section of the mixing tube 26 of FIG. 9,
taken through line 10-10 of FIG. 9. As illustrated, the air ports
28 are oriented directly inward toward a central axis 119 of the
mixing tube 26, thereby enabling a radially inward injection of air
into the mixing tube 26 as indicated by the arrows. As discussed
above, the compressed air 18 enters the mixing tubes 26 via the air
plenum 78 of the fuel nozzle 12. The air 18 is directed into the
air plenum 78 by a diffuser 86 and air inlet 70 in a substantially
radially inward 74 direction. As the air 18 enters the mixing tubes
26, the air ports 28 of the air flow conditioner 27 help direct,
distribute, and generally condition the air flow into the mixing
tube 26 for improved mixing with the fuel 22 from the fuel injector
24. In this embodiment, the air ports 28 are parallel to the radial
axis 48, and therefore impart no swirling motion to the air 18
entering the mixing tubes 26.
[0042] FIG. 11 is cross-section of the mixing tube 26 of FIG. 9,
taken through line 11-11 of FIG. 9. As illustrated by the arrows,
the air ports 28 are oriented radially inward toward, but offset
from, the central axis 119 of the mixing tube 26. In other words,
the air ports 28 are generally angled relative to the radial axis
50, as indicated by an angle 120, such that the air ports 28 impart
a swirling flow in the circumferential direction 52 about the
central axis 119 of the tube 26. As illustrated, the angle 120 of
the air port 28 in relation to the radial axis 50 is greater than
zero. The angle 120 of individual air ports 28 may range between
approximately 0 to 45 degrees, 0 to 30 degrees, 15 to 45 degrees,
15 to 30 degrees, or any subgroup therebetween. For example, the
angle 120 of some air ports 28 may be 5, 10, 15, 20, 25, 30, 35,
40, or 45 degrees, or any other angle, and the angle 120 of other
air ports 28 may be 5, 10, 15, 20, 25, 30, 40 or 45 degrees, or any
other angle. In some embodiments, air ports 28 may be configured to
swirl the air in a clockwise direction, while other air ports 28
may be configured to swirl the air in a counterclockwise direction.
This variation may be made based on the circumferential location of
the individual mixing tube 26 in relation to the fuel nozzle 12 air
inlet 70 to better capture the flow of compressed air 18 in the
fuel nozzle 12 air plenum 78.
[0043] FIG. 12 is cross-section of the mixing tube 26 of FIG. 9,
taken through line 12-12 of FIG. 9. As illustrated by the arrows,
the air ports 28 are oriented radially inward toward, but offset
from, the central axis 119 of the mixing tube 26. In other words,
the air ports 28 are generally angled relative to the radial axis
50, as indicated by the angle 120, such that the air ports 28
impart a swirling flow in the circumferential direction 52 about
the central axis 119 of the tube 26. In contrast to FIG. 11, the
angle 120 of the air ports 28 in FIG. 12 is greater to provide a
greater amount of swirling flow. That is, the angle 120 of the air
port 28 in relation to a radial axis 50 is a larger value than of
the angle 120 in FIG. 11. For example, the angle 120 of the air
ports 28 may range between approximately 45 to 90 degrees, 60 to 90
degrees, 45 to 75 degrees, or 60 to 75 degrees, or any subgroup
therebetween. It is also contemplated that individual air ports 28
within a set of air ports 28 may be configured with different
angles 120 to customize the flow of compressed air 18 within the
fuel nozzle 12. For example, in some embodiments, mixing tubes 26
installed within the fuel nozzle 12 in locations that are more
radially outward and closer to the air inlet 70 may be configured
to have air ports 28 that have greater angles 120 than the air
ports on mixing tubes 26 located within the more radially inward
locations within the fuel nozzle 12, further away from the air
inlets 70. In some embodiments, air ports 28 on the mixing tubes 26
may be angled to direct the air in directions with an axial 48
component. That is, the air port 28 may be configured to direct the
compressed air in a direction with a downstream 66 or upstream 68
component, for even greater control of the flow of compressed air
18 within the mixing tubes 26. These variations in the angular
configuration of the air ports 28 may compensate for variations of
compressed air flow within the mixing tube 26, variations of
injected fuel 22 dispersion from the fuel injectors 24, or other
varying conditions of the environment within the fuel nozzle 12
that may affect the uniformity of the fuel-air mixture 30.
[0044] FIGS. 13-16 are perspective vies of the fuel nozzle 12,
illustrating a series of steps of a method for removing at least
one mixing tube 26 in accordance with certain embodiments. As
illustrated in FIG. 13, the multi-tube fuel nozzle 12 is removed
from the head end 56 of the combustor 16 and coupled to the end
cover assembly 58. Illustrated is the end cover assembly 58 with
fuel inlet 62 coupled with the support structure 82 and cap face
assembly 60. To access the mixing tubes 26, as illustrated in FIG.
14, the end cover assembly 58 is separated from the support
structure 82 and cap face assembly 60. FIG. 14 reveals the fuel
injectors 24 coupled to the end cover assembly 58 of the fuel
nozzle 12. Next, as shown in FIG. 15, the retainer plate 84 is
removed from the cap face assembly 60 by sliding the retainer plate
84 along the mixing tubes 26 in an upstream 68 direction from the
second end 96 to the first end 94 of the mixing tubes 26. As shown
in FIG. 16, the mixing tubes 26 may then be removed from their
location on the cap face assembly 60. Removal of one or more mixing
tubes 26 may allow for inspection, replacement, repair, or any
other purpose found in the course of manufacturing, installation,
and operation of the fuel nozzle 12. Installation of mixing tubes
26 is achieved by following the steps illustrated in FIGS. 13-16 in
reverse order. Namely, the one or more mixing tubes 26 may be
inserted in place on the cap face assembly 60 (FIG. 16), then the
retainer plate 84 installed by sliding across the mixing tubes 26
from the first end 94 to the second end 96, until the tubes 26 are
flush with the cap face assembly 60 and/or impingement plate 92
(FIG. 15). The support structure 82 is then coupled with the end
cover assembly 58 by aligning the mixing tubes 26 with their
respective fuel injectors 24 (FIG. 14). The assembled fuel nozzle
12 (FIG. 13) may then be installed into the head end 56 of the
combustor 12.
[0045] Technical effects of the disclosed embodiments include
systems and methods for improving the mixing of the air and the
fuel within multi-tube fuel nozzles 12 of a gas turbine system. In
particular, the fuel nozzle 12 is equipped with multiple mixing
tubes 26 having air ports 28 (e.g., air flow conditioner 27)
through which pressurized compressed air 18 that enters the fuel
nozzle 12 is directed and mixes with fuel 22 injected by multiple
fuel injectors 24. The air ports 28 may be configured with
different shapes, sizes, spatial arrangements, and configured to
direct the air at various angles. This customization increases
mixing and uniformity, compensating for the varying air 18 and fuel
22 pressures among the multiple fuel injectors 24 in the multi-tube
fuel nozzle 12. The increased mixing of the air 18 and the fuel 22
increases the flame stability within the combustor 16 and reduces
the amount of undesirable combustion byproducts. The method of
removal and replacement of individual mixing tubes 26 allows for
cost-effective and efficient repair of the fuel nozzle 12.
[0046] Although some typical sizes and dimensions have been
provided above in the present disclosure, it should be understood
that the various components of the described combustor may be
scaled up or down, as well as individually adjusted for various
types of combustors and various applications. This written
description uses examples to disclose embodiments of the invention,
including the best mode, and also to enable any person skilled in
the art to practice the invention, including making and using any
devices or systems and performing any incorporated methods. The
patentable scope of the invention is defined by the claims, and may
include other examples that occur to those skilled in the art. Such
other examples are intended to be within the scope of the claims if
they have structural elements that do not differ from the literal
language of the claims, or if they include equivalent structural
elements with insubstantial differences from the literal languages
of the claims.
* * * * *