U.S. patent application number 13/723322 was filed with the patent office on 2014-06-26 for system for supplying fuel to a combustor.
This patent application is currently assigned to GENERAL ELECTRIC COMPANY. The applicant listed for this patent is GENERAL ELECTRIC COMPANY. Invention is credited to Wei Chen, Richard Martin DiCintio, Hasan Karim, Ilya Alexandrovich Slobodyanskiy.
Application Number | 20140174090 13/723322 |
Document ID | / |
Family ID | 49918416 |
Filed Date | 2014-06-26 |
United States Patent
Application |
20140174090 |
Kind Code |
A1 |
Chen; Wei ; et al. |
June 26, 2014 |
SYSTEM FOR SUPPLYING FUEL TO A COMBUSTOR
Abstract
A system for supplying fuel to a combustor includes a combustion
chamber and a liner that circumferentially surrounds at least a
portion of the combustion chamber. A plurality of fuel nozzles are
radially arranged across the combustor upstream from the combustion
chamber to supply a swirling flow of fuel into the combustion
chamber. A first fuel injector downstream from the plurality of
fuel nozzles provides fluid communication for fuel to flow through
the liner and into the combustion chamber. The first fuel injector
is circumferentially clocked with respect to the swirling flow of
fuel in the combustion chamber.
Inventors: |
Chen; Wei; (Greer, SC)
; DiCintio; Richard Martin; (Simpsonville, SC) ;
Karim; Hasan; (Simpsonville, SC) ; Slobodyanskiy;
Ilya Alexandrovich; (Simpsonville, SC) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
GENERAL ELECTRIC COMPANY |
Schenectady |
NY |
US |
|
|
Assignee: |
GENERAL ELECTRIC COMPANY
Schenectady
NY
|
Family ID: |
49918416 |
Appl. No.: |
13/723322 |
Filed: |
December 21, 2012 |
Current U.S.
Class: |
60/740 |
Current CPC
Class: |
F23R 3/346 20130101;
F23R 3/14 20130101; F23R 3/286 20130101; F23R 3/28 20130101 |
Class at
Publication: |
60/740 |
International
Class: |
F23R 3/28 20060101
F23R003/28 |
Claims
1. A system for supplying fuel to a combustor, comprising: a. a
combustion chamber; b. a liner that circumferentially surrounds at
least a portion of the combustion chamber; c. a plurality of fuel
nozzles radially arranged across the combustor upstream from the
combustion chamber, wherein the plurality of fuel nozzles supply a
swirling flow of fuel into the combustion chamber; d. a first fuel
injector downstream from the plurality of fuel nozzles, wherein the
first fuel injector provides fluid communication for fuel to flow
through the liner and into the combustion chamber; and e. wherein
the first fuel injector is circumferentially clocked with respect
to the swirling flow of fuel in the combustion chamber.
2. The system as in claim 1, wherein each fuel nozzle comprises a
plurality of swirler vanes that extend radially between a center
body and a shroud.
3. The system as in claim 1, wherein the first fuel injector
intersects the liner at a compound angle.
4. The system as in claim 1, further comprising a second fuel
injector downstream from the plurality of fuel nozzles, wherein the
second fuel injector provides fluid communication for fuel to flow
through the liner and into the combustion chamber, and wherein the
second fuel injector is circumferentially clocked with respect to
the swirling flow of fuel in the combustion chamber.
5. The system as in claim 4, wherein the second fuel injector is
axially aligned substantially even with the first fuel
injector.
6. The system as in claim 4, wherein the second fuel injector is
axially aligned in the combustion chamber downstream from the first
fuel injector.
7. The system as in claim 4, wherein the second fuel injector
intersects the liner at a compound angle.
8. The system as in claim 1, further comprising a flow sleeve that
circumferentially surrounds at least a portion of the liner and a
fuel plenum inside the flow sleeve in fluid communication with the
first fuel injector.
9. A system for supplying fuel to a combustor, comprising: a. a
combustion chamber; b. a liner that circumferentially surrounds at
least a portion of the combustion chamber; c. a plurality of fuel
nozzles radially arranged across the combustor upstream from the
combustion chamber, wherein the plurality of fuel nozzles supply a
swirling flow of fuel into the combustion chamber; d. a first set
of fuel injectors circumferentially arranged around the liner
downstream from the plurality of fuel nozzles, wherein the first
set of fuel injectors provide fluid communication for fuel to flow
through the liner and into the combustion chamber; and e. wherein
the first set of fuel injectors are circumferentially clocked with
respect to the swirling flow of fuel in the combustion chamber.
10. The system as in claim 9, wherein each fuel nozzle comprises a
plurality of swirler vanes that extend radially between a center
body and a shroud.
11. The system as in claim 9, wherein each fuel injector in the
first set of fuel injectors intersects the liner at a compound
angle.
12. The system as in claim 9, further comprising a second set of
fuel injectors circumferentially arranged around the liner
downstream from the first set of fuel injectors, wherein the second
set of fuel injectors provide fluid communication for fuel to flow
through the liner and into the combustion chamber, and wherein the
second set of fuel injectors are circumferentially clocked with
respect to the swirling flow of fuel in the combustion chamber.
13. The system as in claim 12, wherein the second set of fuel
injectors are axially aligned in the combustion chamber downstream
from the first set of fuel injectors.
14. The system as in claim 12, wherein each fuel injector in the
second set of fuel injectors intersects the liner at a compound
angle.
15. The system as in claim 9, further comprising a flow sleeve that
circumferentially surrounds at least a portion of the liner and a
fuel plenum inside the flow sleeve in fluid communication with the
first set of fuel injectors.
16. A gas turbine, comprising: a. a compressor; b. a combustor
downstream from the compressor; c. a turbine downstream from the
combustor; d. a plurality of fuel nozzles radially arranged inside
the combustor; e. a combustion chamber downstream from the
plurality of fuel nozzles, wherein the plurality of fuel nozzles
supply a swirling flow of fuel into the combustion chamber; f. a
first set of fuel injectors circumferentially arranged around the
combustion chamber downstream from the plurality of fuel nozzles,
wherein the first set of fuel injectors provide fluid communication
for fuel to flow into the combustion chamber; and g. wherein the
first set of fuel injectors are circumferentially clocked with
respect to the swirling flow of fuel in the combustion chamber.
17. The gas turbine as in claim 16, wherein each fuel injector in
the first set of fuel injectors intersects the liner at a compound
angle.
18. The gas turbine as in claim 16, further comprising a second set
of fuel injectors circumferentially arranged around the combustion
chamber downstream from the first set of fuel injectors, wherein
the second set of fuel injectors provide fluid communication for
fuel to flow into the combustion chamber, and wherein the second
set of fuel injectors are circumferentially clocked with respect to
the swirling flow of fuel in the combustion chamber.
19. The gas turbine as in claim 18, wherein the second set of fuel
injectors are axially aligned in the combustion chamber downstream
from the first set of fuel injectors.
20. The gas turbine as in claim 18, wherein each fuel injector in
the second set of fuel injectors intersects the combustion chamber
at a compound angle.
Description
FIELD OF THE INVENTION
[0001] The present invention generally involves a system for
supplying fuel to a combustor. In particular embodiments, the
combustor may be incorporated into a gas turbine or other
turbo-machine.
BACKGROUND OF THE INVENTION
[0002] Combustors are commonly used in industrial and power
generation operations to ignite fuel to produce combustion gases
having a high temperature and pressure. For example, turbo-machines
such as gas turbines typically include one or more combustors to
generate power or thrust. A typical gas turbine includes an inlet
section, a compressor section, a combustion section, a turbine
section, and an exhaust section. The inlet section cleans and
conditions a working fluid (e.g., air) and supplies the working
fluid to the compressor section. The compressor section increases
the pressure of the working fluid and supplies a compressed working
fluid to the combustion section. The combustion section mixes fuel
with the compressed working fluid and ignites the mixture to
generate combustion gases having a high temperature and pressure.
The combustion gases flow to the turbine section where they expand
to produce work. For example, expansion of the combustion gases in
the turbine section may rotate a shaft connected to a generator to
produce electricity.
[0003] The combustion section may include one or more combustors
annularly arranged between the compressor section and the turbine
section, and the temperature of the combustion gases directly
influences the thermodynamic efficiency, design margins, and
resulting emissions of the combustor. For example, higher
combustion gas temperatures generally improve the thermodynamic
efficiency of the combustor. However, higher combustion gas
temperatures also promote flame holding conditions in which the
combustion flame migrates towards the fuel being supplied by
nozzles, possibly causing accelerated damage to the nozzles in a
relatively short amount of time. In addition, higher combustion gas
temperatures generally increase the disassociation rate of diatomic
nitrogen, increasing the production of nitrogen oxides (NO.sub.x)
for the same residence time in the combustor. Conversely, a lower
combustion gas temperature associated with reduced fuel flow and/or
part load operation (turndown) generally reduces the chemical
reaction rates of the combustion gases, increasing the production
of carbon monoxide and unburned hydrocarbons for the same residence
time in the combustor.
[0004] In a particular combustor design, the combustor may include
a cap assembly that extends radially across at least a portion of
the combustor, and one or more fuel nozzles may be radially
arranged across the cap assembly to supply fuel to the combustor.
The fuel nozzles may include swirler vanes and/or other flow guides
to enhance mixing between the fuel and the compressed working fluid
to produce a lean fuel-air mixture for combustion. The swirling
fuel-air mixture flows into a combustion chamber where it ignites
to generate the combustion gases. The combustor may further include
one or more fuel injectors circumferentially arranged around the
combustion chamber to supply additional fuel for combustion. The
additional fuel supplied by the fuel injectors increases the firing
temperature of the combustor without producing a corresponding
increase in the residence time of the combustion gases inside the
combustion chamber.
[0005] Although effective at enabling higher operating
temperatures, the axial and circumferential location of the fuel
injectors around the combustion chamber may have a substantial
impact on undesirable emissions and/or component wear. For example,
fuel injectors that inject fuel directly into the combusting
fuel-air mixture flowing from the fuel nozzles may produce
undesirable hot streaks inside the combustor that may increase the
NO.sub.x emissions and reduce the low cycle fatigue of components.
Alternately, fuel injectors that inject fuel too far from the
combusting fuel-air mixture flowing from the fuel nozzles may lead
to incomplete combustion of the fuel, increasing the production of
carbon monoxide and unburned hydrocarbons. As a result, a system
for supplying fuel to a combustor that indexes or clocks the fuel
injectors to the fuel nozzles and/or the swirling fuel-air mixture
flowing from the fuel nozzles may allow for increased combustor
temperatures over a wider range of operating conditions without a
corresponding increase in undesirable emissions and/or component
wear.
BRIEF DESCRIPTION OF THE INVENTION
[0006] Aspects and advantages of the invention are set forth below
in the following description, or may be obvious from the
description, or may be learned through practice of the
invention.
[0007] One embodiment of the present invention is a system for
supplying fuel to a combustor that includes a combustion chamber
and a liner that circumferentially surrounds at least a portion of
the combustion chamber. A plurality of fuel nozzles are radially
arranged across the combustor upstream from the combustion chamber
to supply a swirling flow of fuel into the combustion chamber. A
first fuel injector downstream from the plurality of fuel nozzles
provides fluid communication for fuel to flow through the liner and
into the combustion chamber. The first fuel injector is
circumferentially clocked with respect to the swirling flow of fuel
in the combustion chamber.
[0008] Another embodiment of the present invention is a system for
supplying fuel to a combustor that includes a combustion chamber
and a liner that circumferentially surrounds at least a portion of
the combustion chamber. A plurality of fuel nozzles are radially
arranged across the combustor upstream from the combustion chamber
to supply a swirling flow of fuel into the combustion chamber. A
first set of fuel injectors are circumferentially arranged around
the liner downstream from the plurality of fuel nozzles. The first
set of fuel injectors provide fluid communication for fuel to flow
through the liner and into the combustion chamber and are
circumferentially clocked with respect to the swirling flow of fuel
in the combustion chamber.
[0009] The present invention may also include a gas turbine having
a compressor, a combustor downstream from the compressor, and a
turbine downstream from the combustor. A plurality of fuel nozzles
are radially arranged inside the combustor, and a combustion
chamber is downstream from the plurality of fuel nozzles. The
plurality of fuel nozzles supply a swirling flow of fuel into the
combustion chamber. A first set of fuel injectors are
circumferentially arranged around the combustion chamber downstream
from the plurality of fuel nozzles. The first set of fuel injectors
provide fluid communication for fuel to flow into the combustion
chamber and are circumferentially clocked with respect to the
swirling flow of fuel in the combustion chamber.
[0010] Those of ordinary skill in the art will better appreciate
the features and aspects of such embodiments, and others, upon
review of the specification.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] A full and enabling disclosure of the present invention,
including the best mode thereof to one skilled in the art, is set
forth more particularly in the remainder of the specification,
including reference to the accompanying figures, in which:
[0012] FIG. 1 is a functional block diagram of an exemplary gas
turbine within the scope of the present invention;
[0013] FIG. 2 is a simplified side cross-section view of an
exemplary combustor according to various embodiments of the present
invention;
[0014] FIG. 3 is an enlarged partial side cross-section view of the
cap assembly and fuel nozzles shown in FIG. 2;
[0015] FIG. 4 is an enlarged side cross-section view of an
exemplary fuel injector shown in FIG. 2;
[0016] FIG. 5 is an upstream partial perspective side cross-section
view of the combustor shown in FIG. 2 according to an embodiment of
the present invention; and
[0017] FIG. 6 is a set of emissions curves at various
temperatures.
DETAILED DESCRIPTION OF THE INVENTION
[0018] Reference will now be made in detail to present embodiments
of the invention, one or more examples of which are illustrated in
the accompanying drawings. The detailed description uses numerical
and letter designations to refer to features in the drawings. Like
or similar designations in the drawings and description have been
used to refer to like or similar parts of the invention. As used
herein, the terms "first", "second", and "third" may be used
interchangeably to distinguish one component from another and are
not intended to signify location or importance of the individual
components. The terms "upstream," "downstream," "radially," and
"axially" refer to the relative direction with respect to fluid
flow in a fluid pathway. For example, "upstream" refers to the
direction from which the fluid flows, and "downstream" refers to
the direction to which the fluid flows. Similarly, "radially"
refers to the relative direction substantially perpendicular to the
fluid flow, and "axially" refers to the relative direction
substantially parallel to the fluid flow.
[0019] Each example is provided by way of explanation of the
invention, not limitation of the invention. In fact, it will be
apparent to those skilled in the art that modifications and
variations can be made in the present invention without departing
from the scope or spirit thereof. For instance, features
illustrated or described as part of one embodiment may be used on
another embodiment to yield a still further embodiment. Thus, it is
intended that the present invention covers such modifications and
variations as come within the scope of the appended claims and
their equivalents.
[0020] Various embodiments of the present invention include a
system for supplying fuel to a combustor. The combustor generally
includes a cap assembly that extends radially across at least a
portion of the combustor, and a plurality of fuel nozzles radially
arranged in the cap assembly supply a swirling flow of fuel into a
combustion chamber. One or more fuel injectors may be
circumferentially arranged around the combustion chamber to supply
fuel into the combustion chamber, and each fuel injector is
circumferentially indexed or clocked with respect to the swirling
flow of fuel in the combustion chamber. In particular embodiments,
the fuel injectors may be axially aligned with one another, while
in other particular embodiments, the fuel injectors may be axially
staggered inside the combustion chamber. Alternately or in
addition, the fuel injectors may intersect the combustion chamber
perpendicular to a tangent of the combustion chamber or at a
compound angle, depending on the particular embodiment. As a
result, various embodiments of the present invention may allow
extended combustor operating conditions, extend the life and/or
maintenance intervals for various combustor components, maintain
adequate design margins of flame holding, and/or reduce undesirable
emissions. Although exemplary embodiments of the present invention
will be described generally in the context of a combustor
incorporated into a gas turbine for purposes of illustration, one
of ordinary skill in the art will readily appreciate that
embodiments of the present invention may be applied to any
combustor incorporated into any turbo-machine and are not limited
to a gas turbine combustor unless specifically recited in the
claims.
[0021] Referring now to the drawings, wherein identical numerals
indicate the same elements throughout the figures, FIG. 1 provides
a functional block diagram of an exemplary gas turbine 10 that may
incorporate various embodiments of the present invention. As shown,
the gas turbine 10 generally includes an inlet section 12 that may
include a series of filters, cooling coils, moisture separators,
and/or other devices to purify and otherwise condition a working
fluid (e.g., air) 14 entering the gas turbine 10. The working fluid
14 flows to a compressor section where a compressor 16
progressively imparts kinetic energy to the working fluid 14 to
produce a compressed working fluid 18 at a highly energized state.
The compressed working fluid 18 flows to a combustion section where
one or more combustors 20 ignite fuel 22 with the compressed
working fluid 18 to produce combustion gases 24 having a high
temperature and pressure. The combustion gases 24 flow through a
turbine section to produce work. For example, a turbine 26 may
connect to a shaft 28 so that rotation of the turbine 26 drives the
compressor 16 to produce the compressed working fluid 18.
Alternately or in addition, the shaft 28 may connect the turbine 26
to a generator 30 for producing electricity. Exhaust gases 32 from
the turbine 26 flow through an exhaust section 34 that may connect
the turbine 26 to an exhaust stack 36 downstream from the turbine
26. The exhaust section 34 may include, for example, a heat
recovery steam generator (not shown) for cleaning and extracting
additional heat from the exhaust gases 32 prior to release to the
environment.
[0022] The combustors 20 may be any type of combustor known in the
art, and the present invention is not limited to any particular
combustor design unless specifically recited in the claims. FIG. 2
provides a simplified side cross-section view of an exemplary
combustor 20 according to various embodiments of the present
invention. As shown in FIG. 2, a casing 40 and an end cover 42 may
combine to contain the compressed working fluid 18 flowing to the
combustor 20. A cap assembly 44 may extend radially across at least
a portion of the combustor 20, and one or more fuel nozzles 46 may
be radially arranged across the cap assembly 44 to supply the fuel
22 to a combustion chamber 48 downstream from the cap assembly 44.
A liner 50 may circumferentially surround at least a portion of the
combustion chamber 48, and a transition duct 52 downstream from the
liner 50 may connect the combustion chamber 48 to the inlet of the
turbine 26. An impingement sleeve 54 with flow holes 56 may
circumferentially surround the transition duct 52, and a flow
sleeve 58 may circumferentially surround the liner 50. In this
manner, the compressed working fluid 18 may pass through the flow
holes 56 in the impingement sleeve 54 to flow through an annular
passage 60 outside of the transition duct 52 and liner 50 to
provide convective cooling to the transition duct 52 and liner 50.
When the compressed working fluid 18 reaches the end cover 42, the
compressed working fluid 18 reverses direction to flow through the
fuel nozzles 46 and cap assembly 44 into the combustion chamber
48.
[0023] The present invention is not limited to any particular cap
assembly 44 or fuel nozzles 46 unless specifically recited in the
claims, and FIG. 3 provides an enlarged partial side cross-section
view of an exemplary cap assembly 44 and fuel nozzles 46 within the
scope of the present invention. As shown in FIG. 3, each fuel
nozzle 46 may generally include a center body 62 surrounded by a
shroud 64 to define an annular passage 66 between the center body
62 and the shroud 64. The center body 62 generally extends axially
from the end cover 42 toward the cap assembly 44 to provide fluid
communication for the fuel 22, diluents, and/or other additives to
flow from the end cover 42, through the center body 62, and into
the combustion chamber 48. The shroud 64 may include a bellmouth
opening 68 to enhance the radial distribution of the compressed
working fluid 18 flowing through the annular passage 66 between the
center body 62 and the shroud 64. In addition, one or more vanes 70
may extend radially between the center body 62 and the shroud 64 to
impart a tangential swirl to the compressed working fluid 18 to
enhance mixing between the compressed working fluid 18 and the fuel
22 prior to combustion.
[0024] Referring back to FIG. 2, the combustor 20 may further
include one or more fuel injectors 80 downstream from the fuel
nozzles 46 that that may provide a late lean injection of fuel 22
and compressed working fluid 18 for combustion. The present
invention is not limited to any particular fuel injector 80 unless
specifically recited in the claims, and FIG. 4 provides an enlarged
side cross-section view of an exemplary fuel injector 80 within the
scope of the present invention. As shown in FIG. 4, the fuel
injector 80 may include a tube 82 or other passage that provides
fluid communication through the flow sleeve 58 and the liner 50
into the combustion chamber 48. In the exemplary embodiment shown
in FIG. 4, the tube 82 is substantially perpendicular to the flow
sleeve 58 and liner 50 to inject the fuel-air mixture transverse to
the combustion chamber 48; however, in other embodiments, the tube
82 may be angled axially and/or circumferentially with respect to
the flow sleeve 58 and/or liner 50.
[0025] The flow sleeve 58 may include an internal fuel passage 84,
and each tube 82 may include one or more fuel ports 86
circumferentially arranged around the tube 82. The internal fuel
passage 84 may supply the same or a different fuel 22 to the fuel
ports 86 than is supplied to the fuel nozzles 34. The fuel ports 86
may thus provide fluid communication for the fuel 22 to flow into
the tubes 82 to allow the fuel 22 and compressed working fluid 18
to mix while flowing through the tubes 82 and into the combustion
chamber 48. In this manner, the tubes 82 may supply a lean mixture
of fuel 22 and compressed working fluid 18 for additional
combustion to raise the temperature, and thus the efficiency, of
the combustor 20.
[0026] FIG. 5 provides an upstream partial perspective side
cross-section view of the combustor 20 shown in FIG. 2 to
illustrate the position of the fuel injectors 80 with respect to
the fuel nozzles 46. As shown in FIG. 5, the vanes 70 in the fuel
nozzles 46 impart a tangential swirl to the fuel 22 and compressed
working fluid 18 flowing through the annular passage 66 between the
center body 62 and the shroud 64. As a result, each fuel nozzle 46
supplies a separate swirling flow of fuel 90 that slowly spirals
downstream through the combustion chamber 48 as it combusts. In the
particular embodiment shown in FIG. 5, a first set of fuel
injectors 92 are circumferentially arranged around the liner 50
downstream from the fuel nozzles 46, and a second set of fuel
injectors 94 are circumferentially arranged around the liner 50
downstream from the first set of fuel injectors 92. Each fuel
injector 80 in each set of fuel injectors 92, 94 has the same axial
position as the other fuel injectors 80 in the same set 92, 94. In
addition, each fuel injector 80 in the each set of fuel injectors
92, 94 is circumferentially indexed or clocked with respect to the
swirling flow of fuel 90 from a different fuel nozzle 46. As used
herein, the term "clocked" or "clocking" refers to positioning each
fuel injector 80 at a desired circumferential offset 96 with
respect to the swirling flow of fuel 90. The circumferential offset
96 between each fuel injector 80 and the swirling flow of fuel 90
avoids or reduces the undesirable hot streaks and incomplete
combustion of the fuel 22 associated with previous late lean
injections systems and methods. In addition, in the particular
embodiment shown in FIG. 5, each fuel injector 80 is angled axially
and circumferentially so that each fuel injector 80 intersects the
liner 50 at a compound angle to further enhance the benefit of
clocking the fuel injectors 80 with respect to the swirling flow of
fuel 90.
[0027] The optimum amount of clocking or circumferential offset 96
between each fuel injector 80 and the swirling flow of fuel 90 may
be varies according to various factors, such as the number of fuel
nozzles 46, the amount of swirl induced by each fuel nozzle 46, the
number of fuel injectors 80, the axial and/or circumferential angle
of the fuel injectors 80, and the anticipated operating level for
the combustor 20. For example, the optimum clocking or
circumferential offset 96 may be approximately .+-.2-15 degrees for
a combustor 20 with five or more fuel nozzles 46, approximately
.+-.10-25 degrees for a combustor 20 with four fuel nozzles 46, and
approximately .+-.20-45 degrees for a combustor 20 with three or
fewer fuel nozzles 46.
[0028] The particular clocking or circumferential offset 96 for
each embodiment may be determined empirically through computational
fluid dynamic models and/or through experimentation. For example,
FIG. 6 provides a set of emissions curves for a particular
circumferential offset 96 for the fuel nozzles 46 and first and
second sets of fuel injectors 92, 94. As expected, the carbon
monoxide emissions curve 100 indicates that carbon monoxide
emissions using only the fuel nozzles 46 increase significantly
below lower combustion temperatures associated with reduced fuel
flow and/or part load operation (turndown). Supplying additional
fuel 22 through the first set of fuel injectors 92 or through both
the first and second sets of fuel injectors 92, 94 during turndown
operations shifts the carbon monoxide emissions curve 100 to the
right. Conversely, the NO.sub.x emissions curve 102 indicates that
NO.sub.x emissions using only the fuel nozzles 46 increase
significantly above higher combustion temperatures associated with
full load operations, and supplying additional fuel 22 through the
first set of fuel injectors 92 or through both the first and second
sets of fuel injectors 92, 94 during full load operations shifts
the NO.sub.x emissions curve 102 to the right. As a result, the
NO.sub.x emissions curves 102 indicate that the lean fuel 22
supplied by the first and second set of fuel injectors 92, 94
enable higher combustion temperatures before the NO.sub.x emissions
increase significantly. Additional emissions curves 100, 102 as
shown in FIG. 6 may be empirically or experimentally created for
first and second sets of fuel injectors 92, 94 clocked at different
circumferential offsets 96, and the optimum circumferential offset
96 may be selected based on the collection of emissions curves 100,
102 and anticipated operating schedule for the combustor 20.
[0029] The various embodiments described and illustrated with
respect to FIGS. 1-5 may provide one or more advantages over
existing systems. For example, the various combinations of axial
positions of fuel injectors 80 clocked to the swirling flow of fuel
90 may allow for higher combustor temperatures before producing a
dramatic increase in NO.sub.x emissions. The wider range of
combustor temperatures thus enhances the thermodynamic efficiency
of the gas turbine 10 without a corresponding increase in
undesirable emissions.
[0030] This written description uses examples to disclose 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 include 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 language of the claims.
* * * * *