U.S. patent application number 11/325643 was filed with the patent office on 2007-07-05 for counterflow injection mechanism having coaxial fuel-air passages.
Invention is credited to Joel Meier Haynes.
Application Number | 20070151251 11/325643 |
Document ID | / |
Family ID | 38222927 |
Filed Date | 2007-07-05 |
United States Patent
Application |
20070151251 |
Kind Code |
A1 |
Haynes; Joel Meier |
July 5, 2007 |
Counterflow injection mechanism having coaxial fuel-air
passages
Abstract
In accordance with certain embodiments, a system includes a
fuel-air injection mechanism having coaxial fuel and air passages
leading to fuel and air injection openings. The fuel and air
injection openings are configured to reside at an off-axis position
of a gas turbine combustor, and the fuel and air injection openings
are configured to orient in an injection direction not aligned with
a flow direction through the gas turbine combustor to a
turbine.
Inventors: |
Haynes; Joel Meier;
(Schenectady, NY) |
Correspondence
Address: |
Patrick S. Yoder;FLETCHER YODER
P.O. Box 692289
Houston
TX
77269-2289
US
|
Family ID: |
38222927 |
Appl. No.: |
11/325643 |
Filed: |
January 3, 2006 |
Current U.S.
Class: |
60/772 ;
60/758 |
Current CPC
Class: |
F23R 3/28 20130101; F23C
2900/03006 20130101; F23R 3/02 20130101; F23R 3/54 20130101 |
Class at
Publication: |
060/772 ;
060/758 |
International
Class: |
F23R 3/02 20060101
F23R003/02 |
Claims
1. A system, comprising: a fuel-air injection mechanism comprising
coaxial fuel and air passages leading to fuel and air injection
openings, wherein the fuel and air injection openings are
configured to reside at an off-axis position of a gas turbine
combustor, and the fuel and air injection openings are configured
to orient in an injection direction not aligned with a flow
direction through the gas turbine combustor to a turbine.
2. The system of claim 1, wherein the fuel and air injection
openings are generally coaxial with one another.
3. The system of claim 1, wherein the fuel and air injection
openings are offset from one another along a common axis of the
coaxial fuel and air passages.
4. The system of claim 1, wherein the fuel and air injection
openings are oriented crosswise relative to one another.
5. The system of claim 4, wherein the fuel injection opening is
disposed in a circumferential wall of an air passage of the coaxial
fuel and air passages.
6. The system of claim 4, wherein the fuel injection opening is
disposed in a circumferential wall of a fuel passage of the coaxial
fuel and air passages.
7. The system of claim 1, wherein the coaxial fuel and air passages
comprise a fuel swirling mechanism, or an air swirling mechanism,
or counter swirling mechanisms, or a combination thereof.
8. The system of claim 1, comprising a plurality of fuel-air
injection mechanisms, including the fuel-air injection mechanism,
disposed at multiple radial positions in a circumferential
arrangement.
9. The system of claim 8, wherein the plurality of fuel-air
injection mechanisms is oriented in a generally converging
relationship.
10. The system of claim 1, comprising the gas turbine
combustor.
11. The system of claim 10, wherein the gas turbine combustor
comprises a combustion liner having an inner casing and an outer
casing, an air flow path between and along the inner and outer
casings, and the air flow path extends to the fuel-air injection
mechanism.
12. The system of claim 10, comprising a gas turbine engine having
the turbine and a compressor coupled to the gas turbine
combustor.
13. The system of claim 12, comprising a power generator, or a
propulsion system, or a vehicle, or a combinations thereof coupled
to the gas turbine engine.
14. A system, comprising: a gas turbine combustor, comprising: a
combustion liner having a generally lengthwise flow axis extending
from a stagnation zone to a turbine nozzle; and a counterflow
fuel-air injector disposed in the combustion liner at one or more
intermediate positions between the stagnation zone and the turbine
nozzle, wherein the counterflow fuel-air injector comprises coaxial
fuel and air passages extending to fuel and air injection openings
not aligned with a flow direction from the stagnation zone to the
turbine nozzle.
15. The system of claim 14, wherein the fuel and air injection
openings are generally coaxial with one another.
16. The system of claim 14, wherein the fuel and air injection
openings are oriented crosswise relative to one another.
17. The system of claim 16, wherein the fuel injection opening is
disposed in a circumferential wall of an air passage of the coaxial
fuel and air passages, or the fuel injection opening is disposed in
another circumferential wall of a fuel passage of the coaxial fuel
and air passages, or a combination thereof.
18. The system of claim 14, wherein the coaxial fuel and air
passages comprise a fuel swirling mechanism, or an air swirling
mechanism, or counter swirling mechanisms, or a combination
thereof.
19. The system of claim 14, wherein the combustion liner comprises
a hollow annular wall having a perforated outer casing disposed
about a substantially solid inner casing, and an air circulation
path extends throughout the hollow annular wall to air passages of
the coaxial fuel and air passages.
20. The system of claim 14, comprising a gas turbine engine
including a turbine and a compressor coupled to the gas turbine
combustor.
21. The system of claim 14, wherein the fuel and air injection
openings are oriented in a generally converging relationship toward
the stagnation zone.
22. The system of claim 14, wherein the counterflow fuel-air
injector is disposed in a generally off-axis configuration relative
to the generally lengthwise flow axis.
23. A method, comprising: coaxially flowing fuel and air to a
counterflow fuel-air injector oriented in a generally counterflow
direction relative to a generally lengthwise flow axis from a
stagnation zone to a turbine nozzle of a gas turbine combustor.
24. The method of claim 23, wherein coaxially flowing fuel and air
comprises coaxially injecting fuel and air through coaxial fuel-air
openings in the counterflow fuel-air injector.
25. The method of claim 23, wherein coaxially flowing fuel and air
comprises radially injecting fuel from a fuel port into an air
passage.
26. The method of claim 23, wherein coaxially flowing fuel and air
comprises swirling the air, or swirling the fuel, or swirling the
fuel and air in a common rotational direction, or counterswirling
the fuel and air in opposite rotational directions.
27. The method of claim 23, wherein coaxially flowing fuel and air
comprises injecting fuel and air from a plurality of counterflow
fuel-air injectors oriented to converge toward the stagnation
zone.
28. The method of claim 23, wherein coaxially flowing fuel and air
comprises circulating air through a hollow annular combustion liner
and injecting the air into the gas turbine combustor along with
fuel.
Description
BACKGROUND
[0001] This section is intended to introduce the reader to various
aspects of art that may be related to aspects of the present
invention, which are described and/or claimed below. This
discussion is believed to be helpful in providing the reader with
background information to facilitate a better understanding of the
various aspects of the present invention. Accordingly, it should be
understood that these statements are to be read in this light, and
not as admissions of prior art.
[0002] Combustion engines, such as gas turbine engines, produce a
variety of pollutant emissions. For example, pollutant emissions
generally include carbon oxides (COx), nitrogen oxides (NOx),
sulfur oxides (SOx), and particulate matter (PM). These pollutant
emissions are highly regulated in the United States and elsewhere.
NOx emissions from a gas turbine engine can be reduced by premixing
fuel and air. Unfortunately, premixing can result in unstable
flames that are difficult to anchor, and the best premixed systems
today cannot reach the NOx emission targets. Another approach is
selective catalytic reduction (SCR) of NOx through ammonia
injection. Unfortunately, the SCR approach is relatively
expensive.
[0003] Accordingly, an improved technique is needed to reduce
pollutant emissions, such as NOx emissions, from a gas turbine
combustor.
BRIEF DESCRIPTION
[0004] Certain aspects commensurate in scope with the originally
claimed invention are set forth below. It should be understood that
these aspects are presented merely to provide the reader with a
brief summary of certain forms the invention might take and that
these aspects are not intended to limit the scope of the invention.
Indeed, the invention may encompass a variety of aspects that may
not be set forth below.
[0005] In accordance with certain embodiments, a system includes a
fuel-air injection mechanism having coaxial fuel and air passages
leading to fuel and air injection openings. The fuel and air
injection openings are configured to reside at an off-axis position
of a gas turbine combustor, and the fuel and air injection openings
are configured to orient in an injection direction not aligned with
a flow direction through the gas turbine combustor to a
turbine.
[0006] In accordance with other embodiments, a system includes a
gas turbine combustor having a combustion liner with a generally
lengthwise flow axis extending from a stagnation zone to a turbine
nozzle. The gas turbine combustor also includes a counterflow
fuel-air injector disposed in the combustion liner at one or more
intermediate positions between the stagnation zone and the turbine
nozzle. The counterflow fuel-air injector includes coaxial fuel and
air passages extending to fuel and air injection openings not
aligned with a flow direction from the stagnation zone to the
turbine nozzle.
[0007] In accordance with further embodiments, a method includes
coaxially flowing fuel and air to a counterflow fuel-air injector
oriented in a generally counterflow direction relative to a
generally lengthwise flow axis from a stagnation zone to a turbine
nozzle of a gas turbine combustor.
[0008] Various refinements of the features noted above exist in
relation to the various aspects of the present invention. Further
features may also be incorporated in these various aspects as well.
These refinements and additional features may exist individually or
in any combination. For instance, various features discussed below
in relation to one or more of the illustrated embodiments may be
incorporated into any of the above-described aspects of the present
invention alone or in any combination. Again, the brief summary
presented above is intended only to familiarize the reader with
certain aspects and contexts of the present invention without
limitation to the claimed subject matter.
DRAWINGS
[0009] 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:
[0010] FIG. 1 is a block diagram of an exemplary system having a
gas turbine engine coupled to a load in accordance with certain
embodiments of the present technique;
[0011] FIG. 2 is a lengthwise diagrammatical view of an exemplary
combustor of the gas turbine engine as illustrated in FIG. 1,
further illustrating a counterflow injection mechanism having a
plurality of fuel-air injection lobes arranged circumferentially
along a solid inner casing of the combustor in accordance with
certain embodiments of the present technique;
[0012] FIG. 3 is a crosswise diagrammatical view of an embodiment
of the combustor as illustrated in FIG. 2, further illustrating the
plurality of fuel-air injection lobes disposed at multiple radial
positions along the circumference of the solid inner casing;
[0013] FIG. 4 is a lengthwise diagrammatical view of an alternative
embodiment of the combustor as illustrated in FIGS. 1 and 2,
further illustrating a counterflow injection mechanism having a
radial array of flush fuel-air injection regions arranged
circumferentially along a solid inner casing of the combustor;
[0014] FIG. 5 is a lengthwise diagrammatical view of an alternative
embodiment of the combustor as illustrated in FIGS. 1 and 2,
further illustrating a counterflow injection mechanism having a
radial array of inwardly cantilevered fuel-air injection members
arranged circumferentially along a solid inner casing of the
combustor, wherein each of the inwardly cantilevered fuel-air
injection members has a plurality of coaxial fuel-air ports
oriented generally lengthwise and counterflow relative to a
lengthwise flow axis of the combustor;
[0015] FIG. 6 is a crosswise diagrammatical view of an embodiment
of the combustor as illustrated in FIG. 5, further illustrating the
radial array of inwardly cantilevered fuel-air injection members
disposed at multiple radial positions along the circumference of
the solid inner casing;
[0016] FIG. 7 is a cross-sectional view of an embodiment of one of
the inwardly cantilevered fuel-air injection members as illustrated
in FIG. 5, further illustrating coaxial flow of fuel and air in a
direction generally lengthwise and counterflow relative to a
lengthwise flow axis of the combustor;
[0017] FIG. 8 is a lengthwise diagrammatical view of an alternative
embodiment of the combustor as illustrated in FIG. 5, wherein each
of the inwardly cantilevered fuel-air injection members further
includes a plurality of coaxial fuel-air port oriented generally
crosswise and counterflow relative to the lengthwise flow axis of
the combustor;
[0018] FIG. 9 is a crosswise diagrammatical view of an embodiment
of the combustor as illustrated in FIG. 8, further illustrating the
radial array of inwardly cantilevered fuel-air injection members
disposed at multiple radial positions along the circumference of
the solid inner casing;
[0019] FIG. 10 is a cross-sectional view of an embodiment of one of
the inwardly cantilevered fuel-air injection members as illustrated
in FIG. 8, further illustrating coaxial flow of fuel and air in a
direction generally lengthwise and counterflow relative to a
lengthwise flow axis of the combustor and, also, illustrating
coaxial flow of fuel and air in two opposite directions generally
crosswise and counterflow relative to the lengthwise flow axis of
the combustor;
[0020] FIG. 11 is a lengthwise diagrammatical view of another
embodiment of the combustor as illustrated in FIG. 1, further
illustrating a counterflow injection mechanism having a single
inwardly cantilevered fuel-air injection member disposed on a solid
inner casing of the combustor at or near a turbine nozzle, wherein
the inwardly cantilevered fuel-air injection member has a plurality
of coaxial fuel-air ports oriented generally lengthwise and
counterflow relative to a lengthwise flow axis of the
combustor;
[0021] FIG. 12 is a diagram of an exemplary fuel-air injector
having coaxial fuel and air flows in the same lengthwise or axial
direction in accordance with certain embodiments of the present
technique;
[0022] FIG. 13 is a diagram of an alternative embodiment of a
fuel-air injector having coaxial fuel and air flows, wherein the
fuel flow is redirected in a crosswise or outward radial direction
relative to the air flow;
[0023] FIG. 14 is a diagram of another alternative embodiment of a
fuel-air injector having a central axial air flow and outer fuel
flows directed in a crosswise or inwardly radial direction relative
to the air flow; and
[0024] FIG. 15 is a diagram of a further alternative embodiment of
a fuel-air injector having coaxial fuel and air flows including
swirl mechanisms for both the fuel and air flows.
DETAILED DESCRIPTION
[0025] 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 compliant 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.
[0026] FIG. 1 is a block diagram of an exemplary system 10
including a gas turbine engine 12 coupled to an application 14 in
accordance with certain embodiments of the present technique. In
certain embodiments, the system 10 may include an aircraft, a
watercraft, a locomotive, a power generation system, or
combinations thereof. Accordingly, the application 14 may include a
generator, a propeller, or combinations thereof. The illustrated
gas turbine engine 12 includes an air intake section 16, a
compressor 18, a combustor section 20, a turbine 22, and an exhaust
section 24. The turbine 22 is drivingly coupled to the compressor
18 via a shaft 26. As discussed in further detail below, the
disclosed embodiments of the combustor section 20 include a variety
of counterflow fuel-air injection mechanisms, which facilitate
mixing of fuel, air, and hot products of combustion within the
combustion section. More specifically, the disclosed counterflow
fuel-air injection mechanisms inject both fuel and air one or more
directions generally against or counter to the general flow through
the gas turbine engine 12 and, particularly, the combustor section
20.
[0027] As indicated by the arrows, air flows through the intake
section 16 and into the compressor 18, which compresses the air
prior to entry into the combustor section 20. The illustrated
combustor section 20 includes a combustor housing 28 disposed
concentrically or annularly about the shaft 26 between the
compressor 18 and the turbine 22. Inside the combustor housing 28,
the combustor section 20 includes a plurality of combustors 30
disposed at multiple radial positions in a circular or annular
configuration about the shaft 26. As discussed in further detail
below, the compressed air from the compressor 18 enters each of the
combustors 30, and then mixes and combusts with fuel within the
respective combustors 30 to drive the turbine 22.
[0028] In certain embodiments, the combustors 30 may be configured
as multi-stage combustors, wherein fuel injectors are positioned at
different stages along the length of respective combustors 30.
Alternatively, the combustors 30 may be configured as single stage
combustors, wherein fuel injectors are arranged for a single stage
or zone of combustion. In the following discussion, the combustors
30 are described as single stage combustors, yet the disclosed
embodiments may be utilized with either single stage or multi-stage
combustors within the scope of the present techniques.
[0029] The disclosed embodiments of the combustor 30 include a
variety of counterflow fuel-air injection mechanisms, which direct
the air and fuel in one or more directions generally against the
flow through the combustors 30. For example, the counterflow
fuel-air injection mechanisms may include a plurality of
lengthwise-directed fuel-air injectors, crosswise-directed fuel-air
injectors, or angled fuel-air injectors having both lengthwise and
crosswise directional portions. The lengthwise-directed fuel-air
injectors may be generally aligned in lengthwise directions along
the combustors 30, whereas the crosswise-directed fuel-air
injectors may be generally aligned in crosswise, transverse, or
radial directions relative to a lengthwise flow or axis along the
combustors 30. The angled fuel-air injectors may be oriented in an
acutely angled direction relative to a lengthwise flow axis or
inner surface of the combustor 30. The acutely angled direction
generally includes or can be broken down into lengthwise and
crosswise directional portions. Each of these lengthwise
directions, crosswise directions, and acutely angled directions may
be defined as counterflow directions.
[0030] As discussed in further detail below, the counterflow
fuel-air injection mechanisms inject the fuel and air away from the
turbine 22 in these counterflow directions toward an opposite end
of the combustor 30, such that the fuel and air mixes and combusts
in a stagnation zone. The stagnation zone at the opposite end of
the combustor 30 generally increases stability and anchoring of
flames within the combustor 30. The hot products of combustion then
travels back toward the turbine 22 past the counterflow fuel-air
injection mechanisms. Again, the counterflow fuel-air injection
mechanisms facilitate mixing of the fuel and air with the hot
products of combustion. The hot products of combustion then pass
through nozzles 32 leading to the turbine 22. These hot products of
combustion drive the turbine 22, thereby driving the compressor 18
and a load 34 of the application 14 via the shaft 26. The hot
products of combustion then exhaust through the exhaust section
24.
[0031] FIG. 2 is a lengthwise diagrammatical view of an exemplary
embodiment of the combustor 30 as illustrated in FIG. 1, wherein
the combustor 30 includes a counterflow injection mechanism 50
including a plurality of fuel-air injection lobes 52 disposed at
different radial positions around the inner circumference of a
combustion liner 54 in accordance with certain embodiments of the
present technique. The illustrated combustion liner 54 includes a
solid inner casing 56 surrounded by a perforated outer casing 58.
In other words, the combustion liner 54 has a hollow wall
structure, which has a generally continuous gap between the inner
and outer casings 56 and 58. The combustion liner 54 may include a
ceramic, a cermet, or another suitable material. The fuel-air
injection lobes 52 are generally formed with, or coupled to, the
solid inner casing 56. In the illustrated embodiment, the fuel-air
injection lobes 52 are disposed at multiple radial positions around
the solid inner casing 56 at one lengthwise position 60 relative to
a central lengthwise axis 62 along the combustor 30. Accordingly,
the illustrated combustor 30 is configured as a single stage
combustor. However, other embodiments of the combustor 30 may have
the fuel-air injection lobes 52 disposed at multiple lengthwise
positions relative to the axis 62.
[0032] The illustrated counterflow injection mechanism 50 includes
a fuel injection assembly 64 disposed adjacent an air injection
assembly 66. In certain embodiments, the fuel and air injections
assemblies 64 and 66 are arranged in close proximity to one
another. The fuel injection assembly 64 includes a plurality of
fuel injectors 68 having an elongated injector tip 70. The air
injection assembly 66 includes a plurality of acutely angled air
passages 72 disposed at various radial positions about the inner
circumference of the solid inner casing 56. In certain embodiments,
the elongated injector tip 70 may be disposed in close proximity to
the air passage 72. For example, in the illustrated embodiment of
FIG. 2, the elongated injector tip 70 is generally coaxial or
concentric with the air passage 72. The elongated injector tips 70
and the air passages 72 both extend through a lobe structure 74 at
multiple radial positions around the inner circumference of the
solid inner casing 56. In other words, each of the fuel-air
injection lobes 52 includes one of the elongated injector tips 70
and one of the air passages 72 disposed in one of the lobe
structures 74. As illustrated, the lobe structures 74 include a
protruding portion 76 and a recessed portion 78 on opposite
lengthwise sides of the position 60. In certain embodiments, the
lobe structures 74 each have a generally circular or annular
configuration (e.g., a donut-like shape), wherein the geometry
gradually changes between the protruding portion 76 and the
recessed portion 78.
[0033] In the illustrated embodiment of FIG. 2, the elongated
injector tips 70 and the air passages 72 of the respective fuel-air
injection lobes 52 are oriented in a generally opposite or
counterflow direction relative to the general flow 80 through the
gas turbine engine 12 as discussed above with reference to FIG. 1.
For example, the elongated injector tips 70 and the air passages 72
may be disposed at respective angles 82 and 84 relative to the axis
62 of the combustor 30. The angles 82 and 84 may be substantially
the same or different than one another. The angles 82 and 84 also
may vary between 0 and 90 degrees depending on the length of the
combustion liner 54 and other factors. For example, the angles 82
and 84 may be about 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60,
65, 70, 75, 80, or 85 degrees relative to the axis 62 or the inner
surface of the solid inner casing 56. Moreover, the elongated
injector tips 70 and the air passages 72 of the fuel-air injection
lobes 52 may be directed in a generally converging manner toward a
stagnation zone 86 within a closed rear portion 88 of the solid
inner casing 56. The stagnation zone 86 generally improves
stability and anchoring of flames near the closed rear portion 88
of the combustor 30.
[0034] In operation, the combustor 30 as illustrated in FIG. 2
receives compressed air from the compressor 18 through openings 90
in the perforated outer casing 58 as indicated by arrows 92. Upon
entering the combustion liner 54 through the perforated outer
casing 58, the compressed air resides in an annular space between
the solid inner casing 56 and the perforated outer casing 58. In
other words, the combustion liner 54 has a hollow wall, e.g., a
hollow annular or can-shaped wall, defined by the inner and outer
casings 56 and 58. Advantageously, the combustion liner 54 directs
the compressed air to flow along the solid inner casing 56 toward
the plurality of fuel-air injection lobes 52 as indicated by arrows
94. In this manner, the air flow 94 facilitates cooling of the
solid inner casing 56 prior to injection into the interior of the
combustor 30 via the air passages 72.
[0035] At the fuel-air injection lobes 52, the elongated injector
tips 70 inject fuel flows 96 that accompany air flows 98 from the
air passages 72. In the illustrated embodiment, the fuel and air
flows 96 and 98 are coaxial or concentric relative to one another.
Specifically, the air flows 98 are disposed concentrically about
the fuel flows 96 as a result of the concentric or coaxial
configuration of the elongated injector tips 70 within the air
passages 72. Again, the elongated injector tips 70 and air passages
72 are disposed at respective angles 82 and 84, thereby causing the
fuel and air flows 96 and 98 to travel at least initially at the
angles 82 and 84 in a converging manner toward the axis 62 and the
stagnation zone 86. Thus, the coaxial or concentric configuration
of the fuel-air injection lobes 52 and resultant flows 96 and 98
facilitate fuel-air mixing in the combustor 30 rather than
premixing. In addition, the converging relationship of the fuel-air
injection lobes 52 facilitates mixing of the fuel and air in the
stagnation zone 86, as indicated by flow/mixing arrows 100. As
illustrated, the flow 100 includes U-shaped flows inwardly toward
the axis 62 and outwardly toward the walls of the solid inner
casing 56. In other words, as the flows 100 move in the counterflow
direction from the fuel-air injection lobes 52 toward the closed
rear portion 88, the flows 100 generally reverse in a U-shaped
manner both toward the axis 62 and the walls of the solid inner
casing 56. A similar flow pattern occurs with the other embodiments
discussed below. The fuel-air mixture 100 combusts in the
stagnation zone 86 in the vicinity of the closed rear portion 88,
which advantageously holds or anchors the flame to improve flame
stability within the combustor 30.
[0036] Subsequently, the hot products of combustion travel from the
stagnation zone 86 lengthwise along the combustor 30 toward the
nozzle 32 as indicated by arrows 102. Thus, the hot products of
combustion 102 flow in the same general direction 80 of flow
through the gas turbine engine 12, whereas the fuel and air flows
96 and 98 injected from the fuel-air injection lobes 52 are
generally counterflow. Again, the counterflow may be directed in a
lengthwise direction toward the stagnation zone 86, or a crosswise
direction relative to the axis 62 or solid inner casing 56, or an
acutely angled direction having lengthwise and crosswise
directional portions, or combinations thereof. In this manner, the
counterflow injection mechanism 50 improves the mixture of fuel and
air along with the hot products of combustion within the combustor
30, thereby improving the combustion and reducing pollutant
emissions (e.g., NOx emissions) from the combustor 30. Also, the
lobe structures 74 slightly offset the elongated injector tips 70
and the air passages 72 relative to the inner circumference of the
solid inner casing 56, thereby positioning the injection of the
fuel and air flows 96 and 98 slightly away from the inner
circumference to improve the mixing of fuel, air, and hot products
of combustion.
[0037] FIG. 3 is a crosswise diagrammatical view of the embodiment
of the combustor 30 as illustrated in FIG. 2, further illustrating
a radial configuration of the fuel-air injection lobes 52 of the
counterflow injection mechanism 50 at multiple radial positions
110, 112, 114, 116, 118, 120, 122, and 124 about the solid inner
casing 56 in accordance with certain embodiments of the present
technique. As discussed above with reference to FIG. 2, the fuel
and air flows 96 and 98 of the plurality of fuel-air injection
lobes 52 generally converge toward the axis 62 within the
stagnation zone 86. In certain embodiments, the fuel and air flows
96 and 98 may generally converge on center with the axis 62 as
indicated by dashed lines 110, 112, 114, 116, 118, 120, 122, and
124.
[0038] In other embodiments, the fuel-air injection lobes 52 may be
oriented toward the stagnation zone 86 in a converging manner
toward the axis 62, while being at least slightly off-center
relative to the axis 62 as indicated by dashed arrow 126. As a
result of this off-center converging direction of the fuel-air
injection lobe 52, the fuel and air flows 96 and 98 may create a
swirling flow as indicated by dashed arrow 128. In either
configuration, the converging relationship between the fuel-air
injection lobes 52 facilitates fuel and air mixing within the
stagnation zone 86 (and also mixing with the hot products of
combustion). However, the addition of swirling flow 128 within the
stagnation zone 86 may further improve the fuel-air mixing and
combustion within the combustor 30. In some embodiments, the
fuel-air injection lobes 52 all may be oriented to create a
clockwise swirling flow or a counter clockwise swirling flow.
Alternatively, the fuel-air injection lobes 52 may be staggered to
produce both clockwise and counter clockwise swirling flows. For
example, the odd fuel-air injection lobes 52 (e.g., at radial
positions 110, 114, 118, and 122) may be oriented to produce a
clockwise swirling flow, while the even fuel-air injection lobes 52
(e.g., at radial positions 112, 116, 120, and 124) may be
configured to produce a counter clockwise swirling flow. Again,
certain embodiments of the illustrated combustor 30 may include the
annular array of fuel-air injection lobes 52 as illustrated in FIG.
3 at multiple lengthwise positions along the axis 62, such as in a
multi-stage combustor 30 as mentioned above.
[0039] FIG. 4 is a lengthwise diagrammatical view of an alternative
embodiment of the combustor 30 as illustrated in FIGS. 1-3, wherein
the counterflow injection mechanism 50 includes a radial array or
arrangement of flush fuel-air injection regions 140 in accordance
with certain embodiments of the present technique. As illustrated,
the elongated injector tip 70 and the air passage 72 of the fuel
and air injection assemblies 64 and 68 extend to positions that are
substantially flush with the solid inner casing 56 of the
combustion liner 54. In other words, the elongated injector tip 70
and the air passage 72 are generally recessed from the interior
surface 142 of the solid inner casing 56, yet the inner casing 56
does not protrude in the vicinity of the elongated injector tip 70
and the air passage 72. Thus, in contrast to the fuel-air injection
lobes 52 as illustrated in FIGS. 2 and 3, the radial array of flush
fuel-air injection regions 140 as illustrated in FIG. 4 does not
protrude into the interior of the combustor 30 beyond the solid
inner casing 56. However, in certain embodiments, the elongated
injector tips 70 may be oriented to partially protrude from the
interior surface 142 of the solid inner casing 56. Alternatively,
the elongated injector tips 70 may be retracted into the air
passages 72 as illustrated and described in further detail below
with reference to FIG. 12. Again, the counterflow injection
mechanism 50 as illustrated in FIG. 4 is configured to direct the
fuel and air flows 96 and 98 in a generally converging manner
toward the stagnation zone 86 against the general flow 80 through
the gas turbine engine 12. Subsequently, the hot products of
combustion travel from the stagnation zone 86, past the radial
array of flush fuel-air injection regions 140, and out of the
combustor 30 through the nozzle 32.
[0040] FIG. 5 is a lengthwise diagrammatical view of another
alternative embodiment of the combustor 30 as illustrated in FIG.
1, wherein the combustor 30 includes a counterflow injection
mechanism 150 having a radial array of inwardly cantilevered
fuel-air injection members 152 disposed along the interior of the
solid inner casing 56 in accordance with certain embodiment of the
present technique. In the illustrated embodiment, the fuel-air
injection members 152 protrude inwardly from the solid inner casing
56 of the combustion liner 54 toward, but not reaching, the central
lengthwise axis 62 of the combustor 30. In other words, the
fuel-air injection members 152 are cantilevered and off-center from
the axis 62.
[0041] The illustrated fuel-air injection members 152 have a
co-flow body 154 with coaxial fuel-air ports 156 and 157 disposed
along an edge 158 facing the stagnation zone 86. In the illustrated
embodiment, the coaxial fuel-air ports 156 include three ports 156
that are generally parallel with the axis 62, while the coaxial
fuel air port 157 includes a single port 157 that is angled
inwardly toward (or converging upon) the axis 62 in the counterflow
direction toward the stagnation zone 86. In alternative
embodiments, the fuel-air ports 156 and 157 may include any other
number or arrangement of ports disposed in a desired spacing along
the co-flow body 156. The coaxial fuel-airports 156 are coupled to
fuel pumps or injectors 160 and air passages 162 extending to the
space between the solid inner casing 56 and the perforated outer
casing 58 of the combustion liner 54.
[0042] Accordingly, the fuel-air injection members 152 receive both
fuel and air through the co-flow body 154, which then injects
co-flows of fuel and air from the coaxial fuel-air ports 156 and
157 into the combustor 30 in generally lengthwise directions toward
the stagnation zone 86, as indicated by arrows 164 and 165. In the
illustrated embodiment, the lengthwise flows 164 of fuel and air
are generally parallel with the axis 62 of the combustor 40, while
the flows 165 are generally converging toward the axis 62. However,
in other embodiments, the coaxial fuel-air ports 156 may be
oriented in a generally converging or diverging angle relative to
the axis 62. Moreover, the coaxial fuel-air ports 156 and 157 may
be directed in a generally clockwise or counter clockwise angle
about the axis 62, such that swirling flow may be created within
the combustor 30 as discussed above with reference to FIG. 3.
[0043] In operation, similar to the embodiment of FIG. 2, the
combustor 30 receives compressed air through the perforated outer
casing 58 and along the solid inner casing 56 toward the
counterflow injection mechanism 150 as illustrated by arrows 92 and
94. Upon reaching the counterflow injection mechanism 150, the
compressed air enters through the air passages 162 into the co-flow
body 154 while fuel is received from the fuel pumps or injectors
160. The fuel-air injection members 152 then inject co-flows of
both fuel and air from the ports 156 and 157 into the interior of
the solid inner casing 56 as indicated by arrows 164 and 165.
Again, these co-flows 164 and 165 are disposed at multiple
peripheral-radial positions that are offset from the axis 62. In
addition, the co-flows 164 and 165 are oriented toward the
stagnation zone 86 in a generally opposite or counterflow direction
relative to the general flow 80 through the gas turbine engine 12.
In this manner, the fuel-air co-flows 164 and 165 facilitate
fuel-air mixing, thereby improving combustion and reducing
pollutant emissions in the combustor 40. In the stagnation zone 86,
the fuel-air mixture 100 combusts, and the hot products of
combustion then travel back past the counterflow injection
mechanism 150 and onward to the nozzle 32 as indicated by arrows
102. Again, the fuel-air co-flows 164 and 165 are generally
counterflow relative to the flow 102 of the hot products of
combustion. Accordingly, this counterflow further improves the
fuel-air mixing along with the hot products of combustion within
the combustor 30, as discussed in detail above.
[0044] FIG. 6 is a crosswise diagrammatical view of the combustor
30 as illustrated in FIG. 5, further illustrating the radial array
of inwardly cantilevered fuel-air injection members 152 of the
counterflow injection mechanism 150 in accordance with certain
embodiments of the present technique. The embodiment of FIG. 6 is
slightly different than the embodiment of FIG. 5. Specifically, the
number of ports 156 is four rather than three, and the length of
the co-flow bodies 154 is relatively shorter than the embodiment of
FIG. 5. However, the number of ports 156 and 157 may be increased
or decreased as desired for the particular combustor 30. Moreover,
the length of the bodies 154 may be increased to extend closer to
the axis 62. Moreover, each of the ports 156 and 157 may be
inwardly angled toward the axis 62.
[0045] In the illustrated embodiment, the fuel-air injection
members 152 are disposed at multiple radial positions about the
inner circumference or periphery of the solid inner casing 56, as
indicated by dashed lines 166, 168, 170, 172, 174, 176, 178, and
180. In addition, the fuel-air injection members 152 are generally
aligned or centered with the axis 62. However, an inner or free end
of the inwardly cantilevered fuel-air injection members 152 is
generally offset or off-center from the axis 62 as indicated by
arrow 182. In certain embodiments, the fuel-air injection members
152 may be angled relative to the axis 62, thereby creating a
counter clockwise or clockwise swirling flow downstream in the
stagnation zone 86. For example, the fuel-air injection members 152
may be acutely angled relative to the inner surface of the solid
inner casing 56 rather than being substantially perpendicular. In
the illustrated embodiment, the counterflow injection mechanism 150
includes eight fuel-air injection members 152 in the
peripheral-radial configuration as illustrated in FIGS. 5 and 6.
However, other embodiments of the counterflow injection mechanism
150 may include another suitable number of fuel-air injection
members 152.
[0046] FIG. 7 is a cross-sectional view of an exemplary embodiment
of the fuel-air injection member 152 as illustrated in FIGS. 5 and
6, further illustrating co-flow passages within the interior of the
co-flow body 154 in accordance with certain embodiments of the
present technique. As illustrated, the co-flow body 154 has a
generally aerodynamic geometry or airfoil structure. In addition,
the co-flow body 154 includes a plurality of lateral fuel injection
passages 184 extending from a lengthwise or common fuel supply
passage 186 relative a lengthwise axis (e.g., perpendicular to the
drawing) of the co-flow body 154. These passages 184 and 186 are
generally supported by upper and lower support members 188 and 190
and one or more lateral support structures 192 having the passages
184. The co-flow body 154 also includes one or more air passages
194, 196, and 198. The illustrated fuel injection passages 184 and
the air passages 194, 196, and 198 lead toward the coaxial fuel-air
ports 156 and 157 along the edge 158 as discussed above.
Specifically, as illustrated in FIG. 7, the coaxial fuel-air ports
156 and 157 include a central fuel port 200 from the lateral fuel
injection passage 184 and a concentric or annular air port 202 from
the air passages 194, 196, and 198. Accordingly, in operation, the
fuel flows through the fuel-air injection member 152 as illustrated
by arrows 204, while the air flows through the fuel-air injection
member 152 as illustrated by arrows 206.
[0047] FIGS. 8-10 illustrate an alternative embodiment of the
combustor 30 as illustrated in FIGS. 5-7, wherein the radial array
of inwardly cantilevered fuel-air injection members 152 includes
additional coaxial fuel-air ports 210 and 211 along top and bottom
sides of the co-flow body 154 in accordance with certain
embodiments of the present technique. Turning first to FIG. 8, this
figure is a lengthwise diagrammatical view of the combustor 30,
illustrating a series of the coaxial fuel-air ports 156 and 157
along the edge 158 and a series of the coaxial fuel-air ports 210
and 211 along a face of the co-flow body 154. As discussed above
with reference to FIG. 5, the coaxial fuel-air ports 156 are
generally oriented lengthwise relative to the axis 62 of the
combustor 30, thereby producing coaxial flows of fuel and air as
indicted by arrows 164. Again, these coaxial flows 164 may be
generally aligned parallel with the axis 62, or converging relative
to the axis 62, or diverging relative to the axis 62. However,
these coaxial flows 164 are generally directed lengthwise along the
combustor 30 toward the stagnation zone 86. Similarly, the coaxial
fuel-air ports 157 (and the flows 165) are oriented along the
length of the combustor 30 toward the stagnation zone 86. However,
as discussed above, the coaxial fuel-air ports 157 (and the flows
165) generally converge toward the axis 62 in the counterflow
direction toward the stagnation zone 86.
[0048] In contrast, the coaxial fuel-air ports 210 are directed
crosswise at a distance relative to the axis 62. In other words,
the coaxial fuel-air ports 210 are oriented to produce flows
generally perpendicular to the view of FIG. 8. The coaxial fuel-air
ports 211 are also directed crosswise relative to the axis 62.
However, in contrast to the coaxial fuel-air ports 210, the coaxial
fuel-air ports 211 are directed radially inward in a directly
converging manner toward the axis 62, as indicated by arrows 167.
In other words, the coaxial fuel-air ports 211 all point straight
toward the axis 62 like spokes of a wheel or rays of the sun. In
this manner, the fuel-air injection members 152 produce both
lengthwise and crosswise flows to facilitate fuel and air mixing
within the combustor 30.
[0049] FIG. 9 is a crosswise diagrammatical view of the combustor
30 as illustrated in FIG. 8, further illustrating crosswise flows
214 and 216 of fuel and air from the coaxial fuel-air ports 210
disposed on opposite faces 212 and 218 of the co-flow body 154 in
accordance with certain embodiments of the present technique.
Again, the embodiment of FIG. 9 is slightly different than the
embodiment of FIG. 8. Specifically, the number of ports 156 and 210
is four rather than three, and the length of the co-flow bodies 154
is relatively shorter than the embodiment of FIG. 8. However, the
number of ports 156, 157, 210, and 211 may be increased or
decreased as desired for the particular combustor 30. Moreover, the
length of the bodies 154 may be increased to extend closer to the
axis 62. Moreover, each of the ports 156, 157, 210, and 211 may be
inwardly angled toward the axis 62.
[0050] As illustrated in FIG. 9, the coaxial flows 214 and 216 are
generally offset from the axis 62 by progressively greater
distances from the free end of the co-flow body 154 to the solid
inner casing 56 of the combustor liner 54. In addition, the
co-flows 214 are generally oriented in a clockwise orientation
about the axis 62, whereas the co-flows 216 are oriented in a
generally counter clockwise direction around the axis 62. In this
manner, the co-flows 214 and 216 may produce counter rotating or
swirling flows as indicated by arrows 220 and 222, respectively. In
addition, the coaxial flows 165 and 167 are generally converging
toward the axis 62, such that the coaxial flows 165 and 167 are
generally transverse or crosswise relative to the coaxial flows 214
and 216.
[0051] FIG. 10 is a cross-sectional view of the fuel-air injection
member 152 as illustrated in FIGS. 8 and 9, further illustrating
internal passages leading to the coaxial fuel-air ports 210 and 211
disposed on the faces 212 and 218 in accordance with certain
embodiments of the present technique. Again, similar to the
embodiment of FIG. 7, the co-flow body 154 has a generally
aerodynamic geometry or airfoil structure, and a plurality of
lateral fuel injection passages 184 extending from a first one of
the lengthwise or common fuel supply passage 186 relative a
lengthwise axis (e.g., perpendicular to the drawing) of the co-flow
body 154. The co-flow body 154 also includes one or more air
passages 194, 196, and 198. The illustrated fuel injection passages
184 and the air passages 194, 196, and 198 lead toward the coaxial
fuel-air ports 156 and 157 along the edge 158 as discussed above.
Specifically, as illustrated in FIG. 7, the coaxial fuel-air ports
156 and 157 include a central fuel port 200 from the lateral fuel
injection passage 184 and a concentric or annular air port 202 from
the air passages 194, 196, and 198.
[0052] In addition to the features of the embodiment of FIG. 7, the
upper and lower support members 188 and 190 of FIG. 10 include
upper and lower fuel injection passages 230 and 232 leading from a
second one of the lengthwise or common fuel supply passage 186 to
fuel injection ports 234 and 236 on the opposite faces 212 and 218,
respectively. In other words, the illustrated embodiment includes
two independent fuel supply passages 186, such that the ports 156
and 157 are supplied fuel independently from the ports 210 and 211.
In alternative embodiments, a single fuel supply passage 186 may be
used for all of the ports 156, 157, 210, and 211. In further
alternative embodiments, an independent fuel supply passage 186 may
be used for each set of ports 156, 157, 210, and 211. The coaxial
fuel-air ports 210 and 211 also include air injection ports 238 and
240 disposed concentrically or annularly about the fuel injection
ports 234 and 236, respectively. Accordingly, in operation, fuel
and air flows through the fuel-air injection member 152 as
indicated by arrows 204 and 206.
[0053] FIG. 11 is lengthwise diagrammatical view of another
embodiment of the combustor 30 as illustrated in FIG. 5, wherein
the counterflow injection mechanism 150 has a single inwardly
cantilevered fuel-air injection member 152 disposed at, or in close
proximity to, or inside the nozzle 32 in accordance with certain
embodiments of the present technique. As illustrated, the co-flow
body 154 of the single cantilevered fuel-air injection mechanism
152 protrudes from one side of the solid inner casing 56, and
extends across a substantial portion of the diameter at the nozzle
32. Accordingly, in this embodiment, the co-flow body 154 extends
across the central lengthwise axis 62 of the combustor 30 at the
nozzle 32. The coaxial fuel-air ports 156 are arranged across both
sides of the axis 62, such that the fuel-air injection member 152
provides the coaxial flows 164 of fuel and air at off-center or
offset positions relative to the axis 62. In the illustrated
embodiment, one of the coaxial fuel-air ports 156 is generally
aligned or centered along the axis 62, thereby providing one
coaxial flow 164 of fuel and air that is centered on the axis 62.
In some embodiments, the fuel-air injection member 152 may further
include coaxial fuel-air ports 210, such as those illustrated in
the embodiment of FIGS. 8-10. Moreover, it should be noted that the
combustor 30 may have a relatively shorter length as compared to
the embodiments of FIGS. 2, 4, 5, and 8, because the counterflow
injection mechanism 150 is disposed at or near the nozzle 32 rather
than at an intermediate position between the closed end 88 and the
nozzle 32 of the combustor 30.
[0054] FIGS. 12-15 are diagrammatical views illustrating various
alternative embodiments for fuel-air injection mechanisms, such as
the fuel-air injection lobes 52, the flush fuel-air injection
regions 140, and the inwardly cantilevered fuel-air injection
members 152, as discussed in detail above with reference to FIGS.
2-11. Turning first to the embodiment of FIG. 12, this figure
illustrates a coaxial fuel-air injection mechanism 260 in
accordance with certain embodiments of the present technique. As
illustrated, the coaxial fuel-air injection mechanism 260 includes
a central fuel passage 262 along an axis 264 and a concentric or
outer annular air passage 266 disposed concentrically about the
central fuel passage 262. In the illustrated embodiment, an end 268
of the central fuel passage 262 is disposed at an offset distance
270 relative to an end 272 of the concentric or outer annular air
passage 266. Specifically, the end 268 of the central fuel passage
262 is recessed relative to the end 272 of the concentric or outer
annular air passage 266. However, in other embodiments of the
coaxial fuel-air injection mechanism 260, the ends 268 and 272 may
be substantially flush with one another or the end 268 of the
central fuel passage 262 may protrude outwardly from the end 272 of
the concentric or outer annular air passage 266. In operation, the
coaxial fuel-air injection mechanism 260 produces a central fuel
flow 274 surrounded by an annular air flow 276, which facilitates
fuel-air mixing within the combustor 30.
[0055] FIG. 13 is a diagrammatical view of an exemplary
radial-axial fuel-air injection mechanism 280 having both radial
and axial flows that collide with one another to facilitate
fuel-air mixing in accordance with certain embodiments of the
present technique. In the illustrated embodiment, the radial-axial
fuel-air injection mechanism 280 includes a central fuel passage
282 along an axis 284 and a concentric or outer annular air passage
286 disposed about the central fuel passage 282. In addition, the
central fuel passage 282 includes one or more radial ports 288 that
are generally perpendicular relative to the axis 284. The central
fuel passage 282 also has a tapered section or end 290 downstream
from the radial ports 288. In operation, air travels through the
concentric or outer annular air passage 286 about the central fuel
passage 282 in an axial direction along the axis 284 as indicated
by arrows 292. In addition, fuel flows through the central fuel
passage 282 in a generally axial direction along the axis 284 as
indicated by arrow 294. Upon reaching the radial ports 288, the
fuel travels radially outward from the axis 284 into the air flow
292, as indicated by arrows 296. Thus, the air and fuel flows 292
and 296 are generally crosswise or perpendicular to one another to
facilitate fuel and air mixing within the radial-axial fuel-air
injection mechanism 280 just prior to injection into the combustor
30. In addition, the radial-axial fuel-air injection mechanism 280
facilitates fuel-air mixing within the combustor 30 rather than
premixing the fuel and air.
[0056] FIG. 14 is a diagrammatical view of an alternative
radial-axial fuel-air injection mechanism 300 in accordance with
certain embodiments of the present technique. As illustrated, a
fuel injection mechanism 302 is coupled to an outer wall 304 of a
central air passage 306. The illustrated fuel injection mechanism
302 includes a plurality of radial fuel ports 308 extending through
the outer wall 304. In operation, air flows through the central air
passage 306 in a generally axially direction 310 along an axis 312.
In contrast, fuel flows through the radial fuel ports 308 in a
generally radial or crosswise direction 314 relative to the axis
312. In this manner, the air and fuel flows 310 and 314 collide
with one another within the radial-axial fuel-air injection
mechanism 300. The collision of air and fuel flows 310 and 314
facilitates fuel-air mixing within the injection mechanism 300. In
addition, the radial-axial fuel-air injection mechanism 300
facilitates fuel-air mixing within the combustor 30 rather than
premixing the fuel and air.
[0057] FIG. 15 is a diagrammatical view of an alternative coaxial
fuel-air swirling injection mechanism 320 in accordance with
certain embodiments of the present technique. As illustrated, the
swirling injection mechanism 320 includes a central fuel passage
322 extending along an axis 324 and a concentric or outer annular
air passage 326 disposed about the central fuel passage 322. In
addition, the central fuel passage 322 includes a fuel swirling
mechanism 328 disposed at or near a fuel exit or port 330. The
concentric or outer annular air passage 326 also includes one or
more air swirling mechanisms 332 disposed upstream from the fuel
exit or port 330. In operation, fuel travels through the central
passage 322 in a generally axial direction 334 along the axis 324.
Upon reaching the fuel swirling mechanism 328, the fuel flow gains
a clockwise or counterclockwise rotation or swirl as indicated by
arrow 336. Similarly, the air flows through the concentric or outer
annular air passage 326 in a generally axial direction as indicated
by arrows 338. Upon reaching the air swirling mechanism 332, the
air flow gains rotation in a clockwise or counter clockwise
direction as indicated by arrow 340. In this manner, the rotating
or swirling fuel and air flows 336 and 340 facilitate fuel and air
mixing within the swirling injection mechanism 320.
[0058] In certain embodiments, the rotating or swirling fuel and
air flows 336 and 340 have a common rotational direction, such as
either clockwise or counter clockwise. However, in other
embodiments, the rotational or swirling fuel and air flows 336 and
340 may have opposite rotational directions, such as clockwise and
counter clockwise, or vice versa. Moreover, some embodiments of the
swirling injection mechanism 320 may include only the air swirling
mechanism 332 without the fuel swirling mechanism 328, or only the
fuel swirling mechanism 328 without the air swirling mechanism 332.
Other embodiments may include additional fuel or air swirling
mechanisms 328 and 332 disposed in series or in parallel with one
another. Again, these swirling mechanisms 328 and 332 facilitates
fuel and air mixing within the swirling injection mechanism 320. In
addition, the coaxial fuel-air swirling injection mechanism 320
facilitates fuel-air mixing within the combustor 30 rather than
premixing the fuel and air.
[0059] While the invention may be susceptible to various
modifications and alternative forms, specific embodiments have been
shown by way of example in the drawings and have been described in
detail herein. However, it should be understood that the invention
is not intended to be limited to the particular forms disclosed.
Rather, the invention is to cover all modifications, equivalents,
and alternatives falling within the spirit and scope of the
invention as defined by the following appended claims.
* * * * *