U.S. patent application number 15/458545 was filed with the patent office on 2017-06-29 for system for injecting a liquid fuel into a combustion gas flow field.
The applicant listed for this patent is General Electric Company. Invention is credited to Abinash Baruah, William Francis Carnell, JR., Gilbert Otto Kraemer, Predrag Popovic.
Application Number | 20170184310 15/458545 |
Document ID | / |
Family ID | 52430348 |
Filed Date | 2017-06-29 |
United States Patent
Application |
20170184310 |
Kind Code |
A1 |
Baruah; Abinash ; et
al. |
June 29, 2017 |
System for Injecting a Liquid Fuel into a Combustion Gas Flow
Field
Abstract
A system for injecting a liquid fuel into a combustion gas flow
field includes an annular liner that defines a combustion gas flow
path. The annular liner includes an inner wall, an outer wall and a
fuel injector opening that extends through the inner wall and the
outer wall. The system further includes a gas fuel injector that is
coaxially aligned with the fuel injector opening. The gas fuel
injector includes an upstream end and a downstream end. The
downstream end terminates substantially adjacent to the inner wall.
A dilution air passage is at least partially defined by the gas
fuel injector. A liquid fuel injector extends partially through the
dilution air passage. The liquid fuel injector includes an
injection end that terminates upstream from the inner wall.
Inventors: |
Baruah; Abinash; (Bangalore,
IN) ; Kraemer; Gilbert Otto; (Greer, SC) ;
Popovic; Predrag; (Simpsonville, SC) ; Carnell, JR.;
William Francis; (Greer, SC) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
General Electric Company |
Schenectady |
NY |
US |
|
|
Family ID: |
52430348 |
Appl. No.: |
15/458545 |
Filed: |
March 14, 2017 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
13965657 |
Aug 13, 2013 |
|
|
|
15458545 |
|
|
|
|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
F23R 3/28 20130101; F23R
3/346 20130101; F23R 3/34 20130101 |
International
Class: |
F23R 3/34 20060101
F23R003/34 |
Claims
1. A system for injecting a liquid fuel into a combustion gas flow
field, comprising: a. an annular liner that defines a combustion
gas flow path within the combustor, the annular liner having an
inner wall, an outer wall and a fuel injector opening; and b. a
fuel injector coaxially aligned with the fuel injector opening, the
fuel injector comprising: i. an annular main body having an
upstream end and a downstream end, wherein the annular main body
defines a dilution air passage that provides for fluid
communication through the fuel injector into the combustion gas
flow path; ii. a gas fuel plenum defined within the main body; iii.
a liquid fuel plenum defined within the main body; and iv. a
plurality of liquid fuel injectors that extend from the main body
into the dilution air passage to provide for fluid communication
between the liquid fuel plenum and the dilution air passage,
wherein the plurality of liquid fuel injectors terminate upstream
from the inner wall of the annular liner.
2. The system as in claim 1, wherein the plurality of liquid fuel
injectors comprises a first liquid fuel injector, a second liquid
fuel injector and a third liquid fuel injector arranged in a
triangular array within the dilution air passage.
3. The system as in claim 2, wherein the first liquid fuel injector
is positioned upstream from the second liquid fuel injector and the
third liquid fuel injector with respect to a direction of flow of
combustion gases within the combustion gas flow path.
4. The system as in claim 2, wherein the first liquid fuel
injector, the second liquid fuel injector and the third liquid fuel
injector are arranged in a triangular array within the dilution air
passage.
5. The system as in claim 2, wherein the first liquid fuel injector
is spaced an equal distance from the second liquid fuel injector
and the third liquid fuel injector.
6. A gas turbine, comprising: a. a compressor; b. a combustor
disposed downstream from the compressor, the combustor having an
axially extending fuel nozzle that extends downstream from the end
cover, a combustion gas flow path defined downstream from the
axially extending fuel nozzle and an annular liner that at least
partially defines the combustion gas flow path within the
combustor, the annular liner having an inner wall, an outer wall
and a fuel injector opening; c. a turbine disposed downstream from
the combustor; and d. wherein the combustor further includes a
system for injecting a liquid fuel into a combustion gas flow field
within the combusor downstream from the axially extending fuel
nozzle, the system comprising: i. a dilution air passage that
provides for fluid communication through the annular liner into the
combustion gas flow path; and ii. a plurality of liquid fuel
injectors disposed within the dilution air passage, wherein the
plurality of liquid fuel injectors terminate within the dilution
air passage upstream from the inner wall of the annular liner.
7. The gas turbine as in claim 6, wherein the system comprises a
gas fuel injector disposed coaxially within the fuel injector
opening, the gas fuel injector having an upstream end and a
downstream end, wherein the downstream end terminates substantially
adjacent to the inner wall.
8. The gas turbine as in claim 7, wherein the liquid fuel injector
includes an injection end that terminates adjacent to or upstream
from the downstream end of the gas fuel injector.
9. The gas turbine as in claim 7, wherein the liquid fuel injector
further comprises a first liquid fuel injection port, a second
liquid fuel injection port and a third liquid fuel injection port
that are arranged in a triangular array across the injection end,
wherein the first liquid fuel injection port is positioned upstream
from the second liquid fuel injection port and the third liquid
fuel injection port with respect to a flow of combustion gases that
flow through the combustion gas flow path.
10. The gas turbine as in claim 9, wherein the system further
comprises: a. an annular main body having an upstream end and a
downstream end, wherein the annular main body defines the dilution
air passage; b. a gas fuel plenum that extends within the main
body; c. a liquid fuel plenum that extends within the main body;
and d. wherein the at least one liquid fuel injector extends from
the main body into the dilution air passage to provide for fluid
communication between the liquid fuel plenum and the dilution air
passage.
11. The gas turbine as in claim 9, wherein the at least one liquid
fuel injector comprises of a first liquid fuel injector, a second
liquid fuel injector and a third liquid fuel injector arranged in a
triangular array within the dilution air passage.
12. The gas turbine as in claim 9, wherein the first liquid fuel
injector is positioned upstream from the second liquid fuel
injector and the third liquid fuel injector with respect to a flow
of the combustion gases.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] The present application is a non-provisional application
which claims priority to U.S. application Ser. No. 13/965,657,
filed Aug. 13, 2013, the entire disclosure of which is incorporated
by reference herein.
FIELD OF THE INVENTION
[0002] The present invention generally involves a system for
supplying fuel to a combustor. In particular, the invention relates
to a system for increasing penetration of a axially staged liquid
fuel into a combustion gas flow field.
BACKGROUND OF THE INVENTION
[0003] A gas turbine generally includes a compressor section, a
combustion section having a combustor and a turbine section. The
compressor section progressively increases the pressure of the
working fluid to supply a compressed working fluid to the
combustion section. The compressed working fluid is routed through
and/or around an axially extending fuel nozzle that extends within
the combustor. A fuel is injected into the flow of the compressed
working fluid to form a combustible mixture. The combustible
mixture is burned within a combustion chamber to generate
combustion gases having a high temperature, pressure and velocity.
The combustion gases flow through one or more liners or ducts that
define a hot gas path into the turbine section. The combustion
gases expand as they flow through the turbine section 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.
[0004] 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 may increase
the disassociation rate of diatomic nitrogen, thereby increasing
the production of undesirable emissions such as oxides of nitrogen
(NO.sub.X) for a particular 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,
thereby increasing the production of carbon monoxide (CO) and
unburned hydrocarbons (UHCs) for the same residence time in the
combustor.
[0005] In order to balance overall emissions performance while
optimizing thermal efficiency of the combustor, certain combustor
designs include multiple fuel injectors that are arranged around
the liner and positioned generally downstream from the primary
combustion zone. The fuel injectors generally extend radially
through the liner to provide for fluid communication into the
combustion gas flow field. This type of system is commonly known in
the art and/or the gas turbine industry as Late Lean Injection
(LLI) and/or as axial fuel staging.
[0006] In operation, a portion of the compressed working fluid is
routed through and/or around each of the fuel injectors and into
the combustion gas flow field. A liquid or gaseous fuel from the
fuel injectors is injected into the flow of the compressed working
fluid to provide a lean or air-rich combustible mixture which
spontaneously combusts as it mixes with the hot combustion gases,
thereby increasing the firing temperature of the combustor without
producing a corresponding increase in the residence time of the
combustion gases inside the combustion chamber. As a result, the
overall thermodynamic efficiency of the combustor may be increased
without sacrificing overall emissions performance.
[0007] One challenge with injecting a liquid fuel into the
combustion gas flow field using existing LLI or axial fuel staging
systems is that the momentum of the combustion gases generally
inhibits adequate radial penetration of the liquid fuel into the
combustion gas flow field. As a result, local evaporation of the
liquid fuel occurs along an inner wall of the liner at or near the
fuel injection point, thereby resulting in a high temperature zone
and high thermal stresses.
[0008] Current solutions to address this issue include extending at
least a portion of the fuel injector radially inward through the
liner and into the combustion gas flow field. However, this
approach creates a bluff body in the combustion gas flow field that
results in the formation of a high temperature recirculation zone
downstream from the bluff body. In addition, this approach exposes
the fuel injectors to the hot combustion gases which may impact the
mechanical life of the component and lead to fuel coke buildup.
Therefore, an improved system for injecting a liquid fuel into the
combustion gas flow field for enhanced mixing would be useful.
BRIEF DESCRIPTION OF THE INVENTION
[0009] 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.
[0010] One embodiment of the present invention is a system for
injecting a liquid fuel into a combustion gas flow field. The
system includes an annular liner that defines a combustion gas flow
path. The annular liner includes an inner wall, an outer wall and a
fuel injector opening that extends through the inner wall and the
outer wall. The system further includes a gas fuel injector that is
coaxially aligned with the fuel injector opening. The gas fuel
injector includes an upstream end and a downstream end. The
downstream end terminates substantially adjacent to the inner wall.
A dilution air passage is at least partially defined by the gas
fuel injector. A liquid fuel injector extends partially through the
dilution air passage. The liquid fuel injector includes an
injection end that terminates upstream from the inner wall.
[0011] Another embodiment of the present invention is a system for
injecting a liquid fuel into a combustion gas flow field. The
system includes an annular liner that defines a combustion gas flow
path within a combustor. The annular liner having an inner wall, an
outer wall and a fuel injector opening. The system further includes
a fuel injector that is coaxially aligned with the fuel injector
opening. The fuel injector comprises an annular main body having an
upstream end and a downstream end. The annular main body defines a
dilution air passage that provides for fluid communication through
the fuel injector into the combustion gas flow path. A gas fuel
plenum is defined within the main body, and a liquid fuel plenum is
defined within the main body. A plurality of liquid fuel injectors
extend from the main body into the dilution air passage to provide
for fluid communication between the liquid fuel plenum and the
dilution air passage. The plurality of liquid fuel injectors
terminate upstream from the inner wall of the annular liner.
[0012] Another embodiment of the present invention includes a gas
turbine. The gas turbine includes a compressor and a combustor
disposed downstream from the compressor. The combustor includes an
axially extending fuel nozzle that extends downstream from an end
cover, a combustion gas flow path defined downstream from the
axially extending fuel nozzle and an annular liner that at least
partially defines the combustion gas flow path within the
combustor. The annular liner includes an inner wall, an outer wall
and a fuel injector opening. The gas turbine further includes a
turbine that is disposed downstream from the combustor. The
combustor further includes a system for injecting a liquid fuel
into a combustion gas flow field that is defined within the
combustor downstream from the axially extending fuel nozzle. The
system comprises a dilution air passage that provides for fluid
communication through the annular liner into the combustion gas
flow path, and a plurality of liquid fuel injectors disposed within
the dilution air passage, wherein the fuel injectors terminate
within the dilution air passage upstream from the inner wall of the
annular liner.
[0013] 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
[0014] 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:
[0015] FIG. 1 is a functional block diagram of an exemplary gas
turbine within the scope of the present invention;
[0016] FIG. 2 is a cross-section side view of a portion of an
exemplary can type combustor as may be incorporate various
embodiments of the present invention;
[0017] FIG. 3 is a downstream perspective view of an annular liner
according to various embodiments of the present invention;
[0018] FIG. 4 is a perspective view of a system for injecting a
liquid fuel into a combustion gas flow field, according to one
embodiment of the present invention;
[0019] FIG. 5 is a cross section side view of a fuel injector and a
portion of an annular liner taken along line A-A as shown in FIG.
4, according to one embodiment of the present invention;
[0020] FIG. 6 is a bottom view of a fuel injector including a
liquid fuel injector and a portion of an annular liner according to
various embodiments;
[0021] FIG. 7 is a perspective side view of the system as shown in
FIG. 4, according to another embodiment of the present
invention;
[0022] FIG. 8 is a cross section side view of the system taken
along section line B-B as shown in FIG. 7, according to one
embodiment of the present invention;
[0023] FIG. 9 is a top view of a fuel injector and a portion of an
annular liner as shown in FIG. 7, according to one embodiment of
the present invention; and
[0024] FIG. 10 is a bottom view of the fuel injector and the
portion of the liner as shown in FIG. 9.
DETAILED DESCRIPTION OF THE INVENTION
[0025] 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" and "downstream" 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. The term "radially" refers to the relative direction
that is substantially perpendicular to an axial centerline of a
particular component, and the term "axially" refers to the relative
direction that is substantially parallel to an axial centerline of
a particular component.
[0026] 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. 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 turbomachine and is not limited to
a gas turbine combustor unless specifically recited in the
claims.
[0027] 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.
[0028] The compressed working fluid 18 is mixed with a fuel 20 from
a fuel supply system 22 to form a combustible mixture within one or
more combustors 24. The combustible mixture is burned to produce
combustion gases 26 having a high temperature, pressure and
velocity. The combustion gases 26 flow through a turbine 28 of a
turbine section to produce work. For example, the turbine 28 may be
connected to a shaft 30 so that rotation of the turbine 28 drives
the compressor 16 to produce the compressed working fluid 18.
Alternately or in addition, the shaft 30 may connect the turbine 28
to a generator 32 for producing electricity. Exhaust gases 34 from
the turbine 28 flow through an exhaust section 36 that connects the
turbine 28 to an exhaust stack 38 downstream from the turbine 28.
The exhaust section 36 may include, for example, a heat recovery
steam generator (not shown) for cleaning and extracting additional
heat from the exhaust gases 34 prior to release to the
environment.
[0029] The combustors 24 may be any type of combustor known in the
art, and the present invention is not limited to any particular
combustor design unless specifically recited in the claims. For
example, the combustor 24 may be a can type or a can-annular type
of combustor. FIG. 2 provides a cross-section side view of a
portion of an exemplary gas turbine 10 including a portion of the
compressor 16 and an exemplary can type combustor 24. As shown in
FIG. 2, an outer casing 40 surrounds at least a portion of the
combustor 24. An end cover 42 is coupled to the outer casing 40 at
one end of the combustor 24. The end cover 42 and the outer casing
40 generally define a high pressure plenum 44. The high pressure
plenum 44 receives the compressed working fluid 18 from the
compressor 16.
[0030] At least one axially extending fuel nozzle 46 extends
downstream from the end cover 42 within the outer casing 40. An
annular liner 48 extends downstream from the axially extending fuel
nozzle 46 within the outer casing 40. The annular liner 48 extends
at least partially through the high pressure plenum 44 so as to at
least partially define a combustion gas flow path 50 within the
combustor 24 for routing the combustion gases 26 through the high
pressure plenum 44 towards the turbine 28 (FIG. 1).
[0031] The annular liner 48 may be a singular liner or may be
divided into separate components. For example, the annular liner 48
may comprise of a combustion liner 52 that is disposed proximate to
the axially extending fuel nozzle 46 and a transition duct 54 that
extends downstream from the combustion liner 52. The transition
duct 54 may be shaped so as to accelerate the flow of the
combustion gases 26 through the combustion gas flow path 50 just
upstream from a stage of stationary nozzles (not shown) that are
disposed proximate to an inlet of the turbine 28 within the
combustion gas flow path 50. A combustion chamber 56 is defined
downstream from the axially extending fuel nozzle 46. The
combustion chamber 56 may be at least partially defined by the
annular liner 48. As shown, the combustion gases 26 define a
combustion gas flow field 58 within the combustion gas flow path 50
downstream from the axially extending fuel nozzle 46.
[0032] FIG. 3 provides a downstream perspective view of the annular
liner 48 according to various embodiments of the present invention.
As shown, the annular liner 48 generally includes an inner wall 60,
an outer wall 62 and a fuel injector opening 64 that extends
through the inner wall 60 and the outer wall 62. The fuel injector
opening 64 provides for fluid communication through the annular
liner 48. As shown, the annular liner 48 may include multiple fuel
injector openings 64 arranged circumferentially around the annular
liner 48.
[0033] In particular embodiments, as shown in FIG. 2, the combustor
24 includes a system for injecting a liquid fuel into the
combustion gas flow field 58, herein referred to as "system 100".
The system generally includes the annular liner 48 and at least one
fuel injector 102 that provides for fluid communication through the
annular liner 48 and into the combustion gas flow field 58. The
fuel injector 102 may provide for fluid communication through the
annular liner 48 including the combustion liner 52 and the
transition duct 54 at any point that is downstream from the axially
extending fuel nozzle 46.
[0034] FIG. 4 provides a perspective view of the system 100
including a portion of the annular liner 48 and the fuel injector
102 according to one embodiment of the present invention. As shown,
the fuel injector 102 includes a gas fuel injector 104 and a liquid
fuel injector 106. The gas fuel injector 104 may be fluidly coupled
to a gas fuel source (not shown) and the liquid gas fuel injector
may be fluidly coupled to a liquid fuel supply (not shown).
[0035] FIG. 5 provides a cross section side view of the fuel
injector 102 and a portion of the annular liner 48 taken along line
A-A as shown in FIG. 4, according to one embodiment of the present
invention. As shown in FIG. 5, at least a portion of the gas fuel
injector 104 may be disposed within the fuel injector opening 64.
In one embodiment, the gas fuel injector 104 is coaxially aligned
within the fuel injector opening 64 with respect to a centerline of
the fuel injector opening 64. The gas fuel injector 104 generally
includes an annular main body 108. The annular main body 108
includes an upstream end 110 and a downstream end 112. In
particular embodiments, the downstream end 112 terminates
substantially adjacent to the inner wall 60 of the annular liner
48.
[0036] In particular embodiments, the annular main body 108 defines
a dilution air passage 114 that provides for fluid communication
through the fuel injector 102 and/or through the gas fuel injector
104 into the combustion gas flow path 50. The upstream end 110 of
the gas fuel injector 104 may define an inlet 116 of the dilution
air passage 114 and the downstream end 112 may define an outlet 118
of the dilution air passage 114.
[0037] In particular embodiments, the gas fuel injector 104
includes a gas fuel plenum 120 that is defined within the main body
108. As shown in FIG. 4, the gas fuel plenum 120 may extend
circumferentially around the main body 108. In one embodiment, the
gas fuel plenum 120 extends circumferentially around the main body
108 generally proximate to the upstream end 110. One or more gas
fuel ports 122 may provide for fluid communication between the gas
fuel plenum 120 and the dilution air passage 114.
[0038] In particular embodiments, as shown in FIG. 5, the liquid
fuel injector 106 extends partially through the dilution air
passage 114. The liquid fuel injector 106 includes an injection end
124 that terminates adjacent to or upstream from the downstream end
112 and/or the outlet 118. The injection end 124 of the liquid fuel
injector 106 is positioned outside of the combustion gas flow path
50. In one embodiment, the injection end 124 of the liquid fuel
injector 106 terminates at a point that is between the inner wall
60 and the outer wall 62 of the annular liner 48.
[0039] FIG. 6 provides a bottom view of the fuel injector 102
including the liquid fuel injector 106, particularly the injection
end 124 of the liquid fuel injector 106, and a portion of the
annular liner 48 according to various embodiments. As shown in FIG.
6, the liquid fuel injector 106 may further comprise a plurality of
liquid fuel injection ports 126 disposed across the injection end
124. In one embodiment, as shown in FIG. 6, the plurality of liquid
fuel injection ports 126 comprises a first liquid fuel injection
port 128, a second liquid fuel injection port 130 and a third
liquid fuel injection port 132.
[0040] As shown in FIG. 6, the first liquid fuel injection port
128, the second liquid fuel injection port 130 and the third liquid
fuel injection port 132 may be arranged in a triangular array
across the injection end 124. In one embodiment, the first liquid
fuel injection port 128 is spaced an equal distance 134 from the
second liquid fuel injection port 130 and from the third liquid
fuel injection port 132. In particular embodiments, the first
liquid fuel injection port 128 is positioned upstream from the
second liquid fuel injection port 130 and the third liquid fuel
injection port 132 with respect to the direction of flow of the
combustion gases 26 within the combustion gas flow path 50 (FIG.
5).
[0041] In operation, a portion of the compressed working fluid 18
(FIG. 2) flows through the dilution air passage 114 and into the
combustion gas flow path 50. The liquid fuel is injected
simultaneously within the dilution air passage 114 upstream from
the inner wall 60 of the liner. As the compressed working fluid 18
interacts with the combustion gas flow field 58, a low velocity
area is created within the combustion gas flow field 58. As a
result, the liquid fuel penetrates deep within the combustion gas
flow field 58, thereby enhancing mixing with the combustion gases
before combustion. Local evaporation of the liquid fuel close to
the inner wall 60 of the annular liner 48 is substantially reduced,
thereby reducing high temperature zones which are typically caused
by the evaporated liquid fuel burning close to the inner wall
60.
[0042] The relative momentum between the liquid fuel and the
compressed working fluid 18 provides for the effective atomization
of the liquid fuel. The triangular pattern and/or spacing of the
first, second and third liquid injection ports 128, 130, 132 in the
injector end 124 creates three discrete liquid fuel jets in a
tripod fashion which enhances penetration of the liquid fuel into
the combustion gas flow field 58, thereby contributing to more
complete mixing with the combustion gases. As a result, net NOx
production from fuel bound nitrogen is reduced. The exact
placement, size and number of liquid fuel injection ports 126 may
be optimized using various fluid dynamic analysis tools such as
computational fluid dynamic (CFD) models.
[0043] In addition, by terminating the injection end 124 outside of
the combustion gas flow path 50, the liquid fuel injector 106 is
shielded from direct exposure to the combustion gases 26, thereby
limiting thermal stress on the liquid fuel injector 106. In
addition, by positioning the liquid fuel injector 106 outside of
the combustion gas flow path 50, undesirable flow patterns such as
recirculation zones that are normally associated with flow around a
bluff body such as the liquid fuel injector 106 are eliminated at
and/or downstream from the fuel injector opening 64, thereby
preventing potentially life limiting hot streaks on the annular
liner 48 in that area.
[0044] FIG. 7 provides a perspective side view of the system 100
according to another embodiment of the present invention, and FIG.
8 provides a cross section side view of the system 100 taken along
section line B-B as shown in FIG. 7. In particular embodiments, as
shown in FIG. 7, the system 100 includes the liner 48 and a fuel
injector 150 that is coaxially aligned with the fuel injector
opening 64 (FIGS. 3 and 8). As shown in FIGS. 7 and 8, the fuel
injector 150 comprises an annular main body 152. As shown in FIG.
8, the annular main body 152 includes an upstream end 154 and a
downstream end 156. The annular main body 150 defines a dilution
air passage 158 that provides for fluid communication through the
fuel injector 150 and into the combustion gas flow path 50. The
upstream end 154 of the annular main body 152 defines an inlet 160
of the dilution air passage 158 and the downstream end 156 defines
an outlet 162 of the dilution air passage 158.
[0045] A gas fuel plenum 164 is defined within the main body 152.
In one embodiment, a plurality of gas fuel ports 166 provide for
fluid communication between the gas fuel plenum 158 and the
dilution air passage 158. In one embodiment, a liquid fuel plenum
168 is defined within the annular main body 152. The liquid fuel
plenum 168 and/or the gas fuel plenum 164 may be in fluid
communication with the fuel supply 22 (FIG. 1).
[0046] FIG. 9 provides a top view of the fuel injector 150 and a
portion of the liner 48 as shown in FIG. 7, according to one
embodiment. FIG. 10 provides a bottom view of the fuel injector 150
and a portion of the liner 48 as shown in FIG. 9. As shown in FIGS.
8, 9, and 10, a plurality of liquid fuel injectors 170 extend from
the annular main body 152 into the dilution air passage 158 to
provide for fluid communication between the liquid fuel plenum 168
(FIG. 8) and the dilution air passage 158.
[0047] In particular embodiments, as shown in FIG. 8, the plurality
of liquid fuel injectors 170 terminate upstream from the inner wall
60 of the annular liner 48 within the dilution air flow passage 158
and/or upstream from the downstream end 156 or outlet 162 of the
annular main body 152 within the dilution air flow passage 158. In
this manner, the plurality of liquid fuel injectors 170 are
positioned outside of the combustion gas flow path 50, thereby
shielding the liquid fuel injectors 170 from direct exposure to the
combustion gases 26, thereby limiting thermal stress on the liquid
fuel injectors 170. In addition, by positioning the liquid fuel
injectors 170 outside of the combustion gas flow path 50,
undesirable flow patterns such as recirculation zones that are
normally associated with flow around a bluff body such as the
liquid fuel injectors 170 are eliminated at and/or downstream from
the fuel injector opening 64, thereby preventing hot streaks on the
annular liner 48 and reducing thermal stress in that area.
[0048] In particular embodiments, as shown in FIG. 10, the
plurality of liquid fuel injectors 170 comprises a first liquid
fuel injector 172, a second liquid fuel injector 174 and a third
liquid fuel injector 176 that are arranged in a triangular array
within the dilution air passage 158. In one embodiment, the first
liquid fuel injector 172 is positioned upstream from the second
liquid fuel injector 174 and the third liquid fuel injector 176
with respect to the flow of combustion gases 26. In one embodiment,
the first liquid fuel injector 172 is spaced an equal distance 178
from the second liquid fuel injector 174 and the third liquid fuel
injector 176.
[0049] In operation, as illustrated in various FIGS., a portion of
the compressed working fluid 18 (FIG. 2) flows through the dilution
air passage 158 and into the combustion gas flow path 50. The
liquid fuel is injected simultaneously within the dilution air
passage 158 upstream from the inner wall 60 of the liner and/or the
downstream end 156 or outlet 162 of the annular main body 152. As
the compressed working fluid 18 interacts with the combustion gases
26, a low velocity area is created within the combustion gas flow
field 58. As a result, the liquid fuel penetrates into combustion
gas flow field 58, for example a distance equal to at least one
diameter of the fuel injector opening 64, thereby enhancing mixing
with the combustion gases before combustion.
[0050] Local evaporation of the liquid fuel close to the inner wall
60 of the annular liner 48 is substantially reduced, thereby
reducing high temperature zones which are typically caused by the
liquid fuel evaporating and burning close to the inner wall 60.
Relative momentum between the liquid fuel and the compressed
working fluid 18 provides for effective atomization of the liquid
fuel. The triangular pattern and/or spacing of the first, second
and third liquid fuel injectors 172, 174 and 176 creates three
discrete liquid fuel jets in a tripod fashion which enhances
penetration of the liquid fuel into the combustion gas flow field
58, thereby contributing to more complete mixing with the
combustion gases. The exact placement, size and number of the
liquid fuel injectors 170 may be optimized using various fluid
dynamic analysis tools such as computational fluid dynamic (CFD)
models.
[0051] In addition, by terminating the liquid fuel injectors 170
outside of the combustion gas flow path 50, the liquid fuel
injectors 170 are shielded from direct exposure to the combustion
gases 26, thereby limiting thermal stress on the liquid fuel
injectors 170. In addition, by positioning the liquid fuel
injectors 170 outside of the combustion gas flow path 50,
undesirable flow patterns such as recirculation zones that are
normally associated with flow around a bluff body such as the
liquid fuel injectors 170 are eliminated at and/or downstream from
the fuel injector opening 64, thereby preventing potentially life
limiting hot streaks on the annular liner 48 in that area.
[0052] 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.
* * * * *