U.S. patent application number 13/457754 was filed with the patent office on 2013-10-31 for combustor.
This patent application is currently assigned to GENERAL ELECTRIC COMPANY. The applicant listed for this patent is Won-Wook Kim, Jeffrey Scott LeBegue, Kevin Weston McMahan. Invention is credited to Won-Wook Kim, Jeffrey Scott LeBegue, Kevin Weston McMahan.
Application Number | 20130283802 13/457754 |
Document ID | / |
Family ID | 47750510 |
Filed Date | 2013-10-31 |
United States Patent
Application |
20130283802 |
Kind Code |
A1 |
Kim; Won-Wook ; et
al. |
October 31, 2013 |
COMBUSTOR
Abstract
A combustor includes an end cap that extends radially across at
least a portion of the combustor, wherein the end cap comprises an
upstream surface axially separated from a downstream surface. A
shroud circumferentially surrounds at least a portion of the end
cap, wherein the shroud at least partially defines a fuel plenum
between the upstream surface and the downstream surface. A
combustion chamber downstream from the end cap defines a
longitudinal axis. A plurality of tubes extend from the upstream
surface through the downstream surface of the end cap to provide
fluid communication through the end cap to the combustion chamber.
A transition duct circumferentially surrounds at least a portion of
the combustion chamber downstream from the end cap and curves
tangentially from the longitudinal axis.
Inventors: |
Kim; Won-Wook;
(Simpsonville, SC) ; LeBegue; Jeffrey Scott;
(Simpsonville, SC) ; McMahan; Kevin Weston;
(Greer, SC) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Kim; Won-Wook
LeBegue; Jeffrey Scott
McMahan; Kevin Weston |
Simpsonville
Simpsonville
Greer |
SC
SC
SC |
US
US
US |
|
|
Assignee: |
GENERAL ELECTRIC COMPANY
Schenectady
NY
|
Family ID: |
47750510 |
Appl. No.: |
13/457754 |
Filed: |
April 27, 2012 |
Current U.S.
Class: |
60/737 ;
415/208.1; 60/752 |
Current CPC
Class: |
F23R 3/425 20130101;
F23R 3/286 20130101; F23R 3/46 20130101 |
Class at
Publication: |
60/737 ;
415/208.1; 60/752 |
International
Class: |
F23R 3/42 20060101
F23R003/42; F01D 9/02 20060101 F01D009/02; F23R 3/28 20060101
F23R003/28; F23R 3/10 20060101 F23R003/10 |
Goverment Interests
FEDERAL RESEARCH STATEMENT
[0001] This invention was made with Government support under
Contract No. DE-FC26-05NT42643, awarded by the Department of
Energy. The Government has certain rights in the invention.
Claims
1. A combustor, comprising: a. an end cap that extends radially
across at least a portion of the combustor, wherein the end cap
comprises an upstream surface axially separated from a downstream
surface; b. a shroud that circumferentially surrounds at least a
portion of the end cap, wherein the shroud at least partially
defines a fuel plenum between the upstream surface and the
downstream surface; c. a combustion chamber downstream from the end
cap, wherein the combustion chamber defines a longitudinal axis; d.
a plurality of tubes that extend from the upstream surface through
the downstream surface of the end cap, wherein the plurality of
tubes provide fluid communication through the end cap to the
combustion chamber; and e. a transition duct that circumferentially
surrounds at least a portion of the combustion chamber downstream
from the end cap, wherein the transition duct curves tangentially
from the longitudinal axis.
2. The combustor as in claim 1, further comprising a fuel port that
provides fluid communication from the fuel plenum into one or more
of the plurality of tubes.
3. The combustor as in claim 1, further comprising an air plenum
between the upstream and downstream surfaces and downstream from
the fuel plenum.
4. The combustor as in claim 3, further comprising one or more air
ports that provide fluid communication through the shroud to the
air plenum.
5. The combustor as in claim 1, further comprising a fuel nozzle
extending through the end cap, wherein the fuel nozzle provides
fluid communication through the end cap to the combustion
chamber.
6. The combustor as in claim 5, wherein the plurality of tubes
circumferentially surround the fuel nozzle.
7. The combustor as in claim 1, further comprising a baffle
extending axially from the upstream surface to the downstream
surface, wherein the baffle separates the plurality of tubes into a
plurality of tube bundles in the end cap.
8. The combustor as in claim 1, wherein the transition duct curves
radially from the longitudinal axis.
9. A combustor, comprising: a. an end cap that extends radially
across at least a portion of the combustor, wherein the end cap
comprises an upstream surface axially separated from a downstream
surface; b. a fuel plenum between the upstream and downstream
surfaces; c. a transition duct downstream from the end cap, wherein
the transition duct defines a longitudinal axis, a tangential axis,
and a radial axis; d. a plurality of tubes that extend from the
upstream surface through the downstream surface of the end cap,
wherein the plurality of tubes provide fluid communication through
the end cap to the transition duct; e. an inlet to the transition
duct; and f. an outlet to the transition duct displaced from the
inlet along the longitudinal axis and the tangential axis.
10. The combustor as in claim 9, further comprising an air plenum
between the upstream and downstream surfaces and downstream from
the fuel plenum.
11. The combustor as in claim 10, further comprising one or more
air ports that provide fluid communication through the end cap to
the air plenum.
12. The combustor as in claim 10, further comprising an air passage
between one or more of the plurality of tubes and the downstream
surface of the end cap.
13. The combustor as in claim 9, further comprising a fuel nozzle
extending through the end cap, wherein the fuel nozzle provides
fluid communication through the end cap to the transition duct.
14. The combustor as in claim 9, further comprising a baffle
extending axially from the upstream surface to the downstream
surface, wherein the baffle separates the plurality of tubes into a
plurality of tube bundles in the end cap.
15. The combustor as in claim 9, wherein the outlet to the
transition duct is displaced from the inlet along the radial
axis.
16. A combustor, comprising: a. a fuel plenum; b. a combustion
chamber downstream from the fuel plenum, wherein the combustion
chamber defines a longitudinal axis; c. a plurality of tubes that
provide fluid communication from the fuel plenum to the combustion
chamber; d. a transition duct that circumferentially surrounds at
least a portion of the combustion chamber downstream from the
plurality of tubes, wherein the transition duct curves tangentially
from the longitudinal axis.
17. The combustor as in claim 16, further comprising an air plenum
between the fuel plenum and the combustion chamber.
18. The combustor as in claim 16, wherein the transition duct
curves radially from the longitudinal axis.
19. The combustor as in claim 16, further comprising a baffle
extending axially through the fuel plenum, wherein the baffle
separates the plurality of tubes into a plurality of tube
bundles.
20. The combustor as in claim 16, further comprising a fuel nozzle
in fluid communication with the combustion chamber, wherein the
plurality of tubes circumferentially surround the fuel nozzle.
Description
FIELD OF THE INVENTION
[0002] The present invention generally involves a combustor. In
particular embodiments of the present invention, the combustor may
be incorporated into a gas turbine or other turbo- machine.
BACKGROUND OF THE INVENTION
[0003] 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, gas turbines
typically include one or more combustors to generate power or
thrust. A typical gas turbine used to generate electrical power
includes an axial compressor at the front, one or more combustors
around the middle, and a turbine at the rear. Ambient air may be
supplied to the compressor, and rotating blades and stationary
vanes in the compressor progressively impart kinetic energy to the
working fluid (air) to produce a compressed working fluid at a
highly energized state. The compressed working fluid exits the
compressor and flows through one or more fuel nozzles in the
combustor where the compressed working fluid mixes with fuel and
ignites in a combustion chamber to generate combustion gases having
a high temperature and pressure. The combustion gases flow through
a transition piece to the turbine where alternating stages of
stationary nozzles and rotating buckets redirect, accelerate, and
expand the combustion gases to generate work. For example,
expansion of the combustion gases in the turbine may rotate a shaft
connected to a generator to produce electricity.
[0004] Various design and operating parameters influence the design
and operation of combustors. 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 the 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). 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. One solution for
balancing the thermodynamic efficiency of the combustor,
accelerated damage, and/or undesirable emissions over a wide range
of combustor operating levels is to enhance mixing between the fuel
and compressed working fluid to produce a lean fuel-working fluid
mixture for combustion.
[0005] The enhanced mixing between the fuel and compressed working
fluid is often accomplished by various combinations of injecting,
atomizing, and/or swirling the fuel and/or working fluid prior to
combustion to reduce localized hot spots in the combustion chamber.
In some turbine designs, the stationary nozzles in the first stage
of the turbine include rounded leading edges with large radii to
accommodate swirling combustion gases impacting the first stage
nozzles at various angles of incidence. In particular turbine
designs, however, the first stage of stationary nozzles may be
replaced with transition ducts between each combustor and the
turbine. The transition ducts accelerate and redirect the
combustion gases flowing into the turbine in place of the first
stage nozzles. Although effective at enhancing turbine output
and/or efficiency, excessive swirling in the combustion gases
reduces the effectiveness of the transition ducts. As a result, an
improved combustor design that enhances mixing between the fuel and
working fluid without increasing swirling in the combustion gases
would be useful to enhancing combustor performance without
adversely affecting emissions.
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 combustor that
includes an end cap that extends radially across at least a portion
of the combustor, wherein the end cap comprises an upstream surface
axially separated from a downstream surface. A shroud
circumferentially surrounds at least a portion of the end cap,
wherein the shroud at least partially defines a fuel plenum between
the upstream surface and the downstream surface. A combustion
chamber downstream from the end cap defines a longitudinal axis. A
plurality of tubes extend from the upstream surface through the
downstream surface of the end cap to provide fluid communication
through the end cap to the combustion chamber. A transition duct
circumferentially surrounds at least a portion of the combustion
chamber downstream from the end cap and curves tangentially from
the longitudinal axis.
[0008] Another embodiment of the present invention is a combustor
that includes an end cap that extends radially across at least a
portion of the combustor, wherein the end cap comprises an upstream
surface axially separated from a downstream surface. A fuel plenum
is between the upstream and downstream surfaces, and a transition
duct downstream from the end cap defines a longitudinal axis, a
tangential axis, and a radial axis. A plurality of tubes extend
from the upstream surface through the downstream surface of the end
cap to provide fluid communication through the end cap to the
transition duct. The transition duct includes an inlet and an
outlet displaced from the inlet along the longitudinal axis and the
tangential axis.
[0009] The present invention may also include a combustor having a
fuel plenum and a combustion chamber downstream from the fuel
plenum, wherein the combustion chamber defines a longitudinal axis.
A plurality of tubes provide fluid communication from the fuel
plenum to the combustion chamber, and a transition duct
circumferentially surrounds at least a portion of the combustion
chamber downstream from the plurality of tubes and curves
tangentially from the longitudinal axis.
[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 simplified side cross-section view of an
exemplary gas turbine;
[0013] FIG. 2 is a simplified cross-section view of the exemplary
combustor shown in FIG. 1 according to one embodiment of the
present invention;
[0014] FIG. 3 is an enlarged cross-section view of a portion of the
combustor shown in FIGS. 1 and 2 according to one embodiment of the
present invention;
[0015] FIG. 4 is an enlarged cross-section view of a portion of the
combustor shown in FIG. 1 according to an alternate embodiment of
the present invention;
[0016] FIG. 5 is a partial perspective view of the end cap portion
of the combustor shown in FIG. 4;
[0017] FIG. 6 is a downstream axial view of the end cap according
to one embodiment of the present invention;
[0018] FIG. 7 is a downstream axial view of the end cap according
to an alternate embodiment of the present invention;
[0019] FIG. 8 is a downstream axial view of the end cap according
to an alternate embodiment of the present invention;
[0020] FIG. 9 is a perspective view of the transition duct and
impingement sleeve shown in FIG. 2; and
[0021] FIG. 10 is a perspective view of multiple transition ducts
circumferentially arranged around the gas turbine shown in FIG.
1.
DETAILED DESCRIPTION OF THE INVENTION
[0022] 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. In addition, the terms "upstream" and "downstream"
refer to the relative location of components in a fluid pathway.
For example, component A is upstream from component B if a fluid
flows from component A to component B. Conversely, component B is
downstream from component A if component B receives a fluid flow
from component A.
[0023] 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.
[0024] Various embodiments of the present invention include a
combustor that may be incorporated, for example, into a gas turbine
or other turbo-machine. The combustor generally includes a
plurality of premixer tubes that allow a fuel to be mixed with a
compressed working fluid to produce a lean fuel-working fluid
mixture with reduced amounts of swirl compared to conventional fuel
nozzles. The lean fuel-working fluid mixture flows into a
combustion chamber where it ignites to produce combustion gases
having a high temperature and pressure. The combustion gases flow
through a transition duct that accelerates and/or directs the
combustion gases onto a first stage of rotating blades where the
combustion gases expand and transfer energy to the rotating blades
to produce work. 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 and are not limited to a gas turbine combustor unless
specifically recited in the claims.
[0025] FIG. 1 provides a simplified cross-section view of an
exemplary gas turbine 10 that may incorporate various embodiments
of the present invention. As shown, the gas turbine 10 may
generally include a compressor 12 at the front, one or more
combustors 14 radially disposed around the middle, and a turbine 16
at the rear. The compressor 12 and the turbine 16 may share a
common rotor 18 connected to a generator 20 to produce
electricity.
[0026] The compressor 12 may be an axial flow compressor in which a
working fluid 22, such as ambient air, enters the compressor 12 and
passes through alternating stages of stationary vanes 24 and
rotating blades 26. A compressor casing 28 contains the working
fluid 22 as the stationary vanes 24 and rotating blades 26
accelerate and redirect the working fluid 22 to produce a
continuous flow of compressed working fluid 22. The majority of the
compressed working fluid 22 flows through a compressor discharge
plenum 30 to the combustor 14.
[0027] The combustor 14 may be any type of combustor known in the
art. For example, as shown in FIG. 1, a combustor casing 32 may
circumferentially surround some or all of the combustor 14 to
contain the compressed working fluid 22 flowing from the compressor
12. One or more fuel nozzles 34 may be radially arranged in an end
cover 36 to supply fuel to a combustion chamber 38 downstream from
the fuel nozzles 34. Possible fuels include, for example, one or
more of blast furnace gas, coke oven gas, natural gas, vaporized
liquefied natural gas (LNG), hydrogen, and propane. The compressed
working fluid 22 may flow from the compressor discharge passage 30
along the outside of the combustion chamber 38 before reaching the
end cover 36 and reversing direction to flow through the fuel
nozzles 34 to mix with the fuel. The mixture of fuel and compressed
working fluid 22 flows into the combustion chamber 38 where it
ignites to generate combustion gases having a high temperature and
pressure. A transition duct 40 circumferentially surrounds at least
a portion of the combustion chamber 38, and the combustion gases
flow through the transition duct 40 to the turbine 16.
[0028] The turbine 16 may include alternating stages of rotating
buckets 42 and stationary vanes 44. As will be described in more
detail, the transition duct 40 redirects and focuses the combustion
gases onto the first stage of rotating buckets 42. As the
combustion gases pass over the first stage of rotating buckets 42,
the combustion gases expand, causing the rotating buckets 42 and
rotor 18 to rotate. The combustion gases then flow to the next
stage of stationary vanes 44 which redirect the combustion gases to
the next stage of rotating buckets 42, and the process repeats for
the following stages.
[0029] FIG. 2 shows a simplified cross-section view of the
exemplary combustor 14 shown in FIG. 1 according to one embodiment
of the present invention. As shown, the combustor casing 32 and end
cover 36 may surround the combustor 14 to contain the working fluid
22 flowing from the compressor 12. An impingement sleeve 46 may
surround the transition duct 40, and the working fluid 22 may pass
through flow holes 48 in the impingement sleeve 46 to flow along
the outside of the transition duct 40 to provide convective cooling
to the transition duct 40. When the working fluid 22 reaches the
end cover 36, the working fluid 22 reverses direction to flow
through one or more fuel nozzles 34 and/or tubes 50 and into the
combustion chamber 38.
[0030] FIG. 3 provides an enlarged cross-section view of a portion
of the combustor 14 shown in FIGS. 1 and 2 according to one
embodiment of the present invention. As shown, the one or more fuel
nozzles 34 and tubes 50 may be radially arranged in an end cap 52
upstream from the combustion chamber 38. Various embodiments of the
combustor 14 may include different numbers and arrangements of fuel
nozzles 34 and tubes 50. For example, in the embodiment shown in
FIGS. 1-3, the combustor 14 includes a single fuel nozzle 34
aligned with an axial centerline 54 of the combustor 14, and the
tubes 50 are radially arranged around the single fuel nozzle 34 in
the end cap 52. The fuel nozzle 34 may extend through the end cap
52 to provide fluid communication through the end cap 52 to the
combustion chamber 38. The fuel nozzle 34 may include any suitable
structure known to one of ordinary skill in the art for mixing fuel
with the working fluid 22 prior to entry into the combustion
chamber 38, and the present invention is not limited to any
particular structure or design unless specifically recited in the
claims. For example, as shown in FIG. 3, the fuel nozzle 34 may
include a center body 56 and a bellmouth opening 58. The center
body 56 provides fluid communication for fuel to flow from the end
cover 36, through the center body 56, and into the combustion
chamber 38. The bellmouth opening 58 surrounds at least a portion
of the center body 56 to define an annular passage 60 between the
center body 56 and the bellmouth opening 58. In this manner, the
working fluid 22 may flow through the annular passage 60 to mix
with the fuel from the center body 56 prior to reaching the
combustion chamber 38. If desired, the fuel nozzle 34 may further
include one or more swirler vanes 62 that extend radially between
the center body 56 and the bellmouth opening 58 to impart swirl to
the fuel-working fluid mixture prior to reaching the combustion
chamber 38.
[0031] As shown in FIG. 3, the end cap 52 extends radially across
at least a portion of the combustor 14 and generally includes an
upstream surface 64 axially separated from a downstream surface 66.
The tubes 50 generally extend axially from the upstream surface 64
through the downstream surface 66 of the end cap 52 to provide
fluid communication for the working fluid 22 to flow through the
end cap 52 and into the combustion chamber 38. Although shown as
cylindrical tubes, the cross-section of the tubes 50 may be any
geometric shape, and the present invention is not limited to any
particular cross-section unless specifically recited in the claims.
A shroud 68 circumferentially surrounds at least a portion of the
end cap 52 to partially define a fuel plenum 70 between the
upstream and downstream surfaces 64, 66.
[0032] A fuel conduit 72 may extend from the end cover 36 through
the upstream surface 64 of the end cap 52 to provide fluid
communication for fuel to flow from the end cover 36, through the
fuel conduit 72, and into the fuel plenum 70. One or more of the
tubes 50 may include a fuel port 74 that provides fluid
communication from the fuel plenum 70 into one or more of the tubes
50. The fuel ports 74 may be angled radially, axially, and/or
azimuthally to project and/or impart swirl to the fuel flowing
through the fuel ports 74 and into the tubes 50. In this manner,
the working fluid 22 may flow into the tubes 50, and fuel from the
fuel conduit 72 may flow around the tubes 50 in the fuel plenum 70
to provide convective cooling to the tubes 50 before flowing
through the fuel ports 74 and into the tubes 50 to mix with the
working fluid 22. The fuel-working fluid mixture may then flow
through the tubes 50 and into the combustion chamber 38.
[0033] FIG. 4 provides an enlarged cross-section view of a portion
of the combustor 14 shown in FIG. 1 according to an alternate
embodiment of the present invention, and FIG. 5 provides a partial
perspective view of the end cap 52 portion of the combustor 14
shown in FIG. 4. As shown in FIGS. 4 and 5, the end cap 52 may
again include the upstream surface 64, downstream surface 66,
shroud 68, and fuel plenum 70 as previously described with respect
to the embodiment shown in FIG. 3. In addition, the end cap 52 may
include a generally horizontal barrier 74 that extends radially
between the upstream surface 64 and the downstream surface 66 to
axially separate the fuel plenum 70 from an air plenum 76. In this
manner, the upstream surface 64, shroud 68, and barrier 74 enclose
or define the fuel plenum 70 around the upstream portion of the
tubes 50, and the downstream surface 66, shroud 68, and barrier 74
enclose or define the air plenum 76 around the downstream portion
of the tubes 50. In particular embodiments, as shown most clearly
in FIG. 5, one or more generally vertical baffles 78 may extend
axially from the upstream surface 64 to the barrier 74 or
completely through the end cap 52 to the downstream surface 66 to
radially separate the tubes 50 into a plurality of groups or
bundles 80 in the end cap 52. The baffles 78 (if present) allow
each bundle 80 of tubes 50 to have a dedicated fuel plenum 70
and/or air plenum 76, allowing different fuels and/or fuel flow
rates to be supplied to each bundle 80 of tubes 50. Alternately,
the baffles 78 (if present) may include flow holes 82 or other
perforations to facilitate the flow of fuel between the fuel
plenums 70 associated with each bundle 80 of tubes 50.
[0034] As shown most clearly in FIGS. 4 and 5, the shroud 68 may
include a plurality of air ports 84 that provide fluid
communication for the working fluid 22 to flow through the shroud
68 and into the air plenum 76. In particular embodiments, as shown
most clearly in FIG. 4, an air passage 86 between one or more tubes
50 and the downstream surface 66 may provide fluid communication
from the air plenum 76, through the downstream surface 66, and into
the combustion chamber 38. In this manner, a portion of the working
fluid 22 may flow through the air ports 84 in the shroud 68 and
into the air plenum 76 to provide convective cooling around the
lower portion of the tubes 50 before flowing through the air
passages 86 and into the combustion chamber 38.
[0035] Various embodiments of the combustor 14 may include
different numbers and arrangements of fuel nozzles 34 and tubes 50,
and FIGS. 6-8 provide downstream axial views of the end cap 52
illustrating various arrangements within the scope of the present
invention. In the particular embodiment shown in FIG. 6, for
example, the tubes 50 are radially arranged across the end cap 52,
and fuel and working fluid 22 may be supplied through the tubes 50
to the combustion chamber 38. In the particular embodiment shown in
FIG. 7, the generally vertical baffles 78 may separate the tubes 50
into generally circular tube bundles 80 radially arranged around a
center circular tube bundle 80. Alternately, as shown in FIG. 8,
the generally vertical baffles 78 may separate the tubes 50 into
triangular or pie-shaped tube bundles 80 radially arranged around a
center fuel nozzle 34. One of ordinary skill in the art will
readily appreciate based on that teachings herein that the
particular embodiments of the present invention are not limited to
any particular arrangement, shape, or number of fuel nozzles 34,
tubes 50, and/or tube bundles 80 unless specifically recited in the
claims.
[0036] FIG. 9 provides a perspective view of the transition duct 40
and impingement sleeve 46 shown in FIG. 2, and FIG. 10 provides a
perspective view of multiple transition ducts 40 radially
circumferentially arranged around the gas turbine 10 shown in FIG.
1. As previously shown, the transition duct 40 generally surrounds
at least a portion of the combustion chamber 38 and extends each
end cap 52 and the turbine 16. In this manner, each transition duct
40 provides a path that conditions the flow of combustion gases
from each combustor 14 to the turbine 16. In particular
embodiments, the orientation and/or cross-section of the transition
ducts 40 may replace or eliminate the need for stationary vanes 44
immediately upstream from the first stage of rotating buckets 42,
thus increasing the efficiency and/or output of the turbine 16.
[0037] As shown in FIGS. 9 and 10, each transition duct 40
generally includes an inlet 90 and an outlet 92 downstream from the
inlet 90. The cross-section of the inlet 90 generally conforms to
the radial cross-section of the combustion chamber 38 proximate to
the end cap 52, and the cross-section of the transition duct 40 may
progressively narrow proximate to the outlet 92 to accelerate the
combustion gases into the turbine 16. In addition, the transition
duct 40 may curve between the inlet 90 and outlet 92 to enhance the
angle at which the combustion gases flow into the turbine 16. For
example, as shown in FIGS. 9 and 10, longitudinal, tangential, and
radial axes 94, 96, 98 superimposed over the transition ducts 40
illustrate that the transition ducts 40 may curve transversely,
tangentially, and/or radially from the longitudinal axis 94. It
should be understood that the radial and tangential axes 96, 98 are
defined individually for each transition duct 40 with respect to a
circumference defined by the annular array of transition ducts 40,
as shown in FIG. 10, and that the radial and tangential axes 96, 98
vary for each transition duct 40 about the circumference based on
the number of transition ducts 40 disposed in the annular array
about the longitudinal axis 94. As shown in FIGS. 9 and 10, the
outlet 92 of the transition duct 40 may be displaced or offset from
the inlet 90 along both the longitudinal and tangential axes 94,
98. In particular embodiments the transition ducts 40 may also
curve radially from the longitudinal axis 94 to enhance the impact
angle of the combustion gases against the rotating buckets 42. As a
result, the outlet 92 of the transition duct 40 may be displaced or
offset from the inlet 90 along the radial axis 96, as shown most
clearly in FIG. 10. The combination of the tangential and/or radial
offset of the outlet 92 with respect to the inlet 90 may obviate
the need for stationary vanes 44 upstream from the first stage of
rotating buckets 42.
[0038] The embodiments described and illustrated in FIGS. 2-10
provide one or more benefits over existing combustors and methods
of supplying fuel to combustors. For example, conventional
combustors often include fuel nozzles designed to swirl the fuel
and working fluid to enhance mixing prior to combustion. Although
effective at reducing undesirable NO.sub.x emissions, a first stage
of stationary vanes is often included between the combustor and the
turbine upstream from the first stage of rotating buckets to
redirect the resulting swirling combustion gases onto the first
stage of rotating buckets. The transition duct incorporated into
various embodiments of the present invention obviates the need for
the first stage of stationary vanes, leading to enhanced efficiency
of the turbine.
[0039] 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 languages of the claims.
* * * * *