U.S. patent application number 13/804199 was filed with the patent office on 2014-09-18 for diffusion combustor fuel nozzle for limiting nox emissions.
This patent application is currently assigned to GENERAL ELECTRIC COMPANY. The applicant listed for this patent is GENERAL ELECTRIC COMPANY. Invention is credited to Abinash Baruah, Gilbert Otto Kraemer, Arvind Venugopal Menon, Predrag Popovic.
Application Number | 20140260302 13/804199 |
Document ID | / |
Family ID | 51419072 |
Filed Date | 2014-09-18 |
United States Patent
Application |
20140260302 |
Kind Code |
A1 |
Menon; Arvind Venugopal ; et
al. |
September 18, 2014 |
DIFFUSION COMBUSTOR FUEL NOZZLE FOR LIMITING NOx EMISSIONS
Abstract
The present application and the resultant patent provide a
diffusion combustor fuel nozzle for a gas turbine engine. The fuel
nozzle may include one or more gas fuel passages for one or more
flows of gas fuel, a swirler surrounding the one or more gas fuel
passages and positioned about a downstream face of the fuel nozzle,
a number of swirler gas fuel ports defined in the swirler, and a
number of downstream face gas fuel ports defined in the downstream
face of the fuel nozzle. The swirler may include a number of swirl
vanes and a number of air chambers defined between adjacent swirl
vanes. The present application and the resultant patent further
provide a method of operating a diffusion combustor fuel nozzle of
a gas turbine engine.
Inventors: |
Menon; Arvind Venugopal;
(Greenville, SC) ; Kraemer; Gilbert Otto;
(Greenville, SC) ; Popovic; Predrag; (Greenville,
SC) ; Baruah; Abinash; (Bangalore, IN) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
GENERAL ELECTRIC COMPANY |
Schenectady |
NY |
US |
|
|
Assignee: |
GENERAL ELECTRIC COMPANY
Schenectady
NY
|
Family ID: |
51419072 |
Appl. No.: |
13/804199 |
Filed: |
March 14, 2013 |
Current U.S.
Class: |
60/776 ; 60/742;
60/748 |
Current CPC
Class: |
F23R 3/14 20130101; F23R
3/36 20130101 |
Class at
Publication: |
60/776 ; 60/748;
60/742 |
International
Class: |
F23R 3/36 20060101
F23R003/36; F23R 3/14 20060101 F23R003/14 |
Claims
1. A diffusion combustor fuel nozzle for a gas turbine engine, the
fuel nozzle comprising: one or more gas fuel passages for one or
more flows of gas fuel; a swirler surrounding the one or more gas
fuel passages and positioned about a downstream face of the fuel
nozzle, the swirler comprising a plurality of swirl vanes and a
plurality of air chambers each defined between adjacent swirl
vanes; a plurality of swirler gas fuel ports defined in the
swirler; and a plurality of downstream face gas fuel ports defined
in the downstream face of the fuel nozzle.
2. The diffusion combustor fuel nozzle of claim 1, wherein each of
the swirler gas fuel ports is defined in the swirler between
adjacent swirl vanes.
3. The diffusion combustor fuel nozzle of claim 1, wherein each of
the swirler gas fuel ports is defined in the swirler upstream of
the downstream face of the fuel nozzle.
4. The diffusion combustor fuel nozzle of claim 1, wherein each of
the swirler gas fuel ports extends from one of the gas fuel
passages to one of the air chambers.
5. The diffusion combustor fuel nozzle of claim 1, wherein each of
the swirler gas fuel ports extends towards the downstream face of
the fuel nozzle.
6. The diffusion combustor fuel nozzle of claim 1, wherein each of
the downstream face gas fuel ports extends from one of the gas fuel
passages to the downstream face of the fuel nozzle.
7. The diffusion combustor fuel nozzle of claim 1, wherein each of
the downstream face gas fuel ports is parallel to an axis of the
fuel nozzle.
8. The diffusion combustor fuel nozzle of claim 1, wherein each of
the downstream face gas fuel ports is angled relative to an axis of
the fuel nozzle.
9. The diffusion combustor fuel nozzle of claim 1, wherein the one
or more gas fuel passages extend towards the downstream face of the
fuel nozzle.
10. The diffusion combustor fuel nozzle of claim 1, wherein each of
the swirler gas fuel ports extends from a first gas fuel passage to
one of the air chambers, and each of the downstream face gas fuel
ports extends from the first gas fuel passage to the downstream
face of the fuel nozzle.
11. The diffusion combustor fuel nozzle of claim 1, wherein each of
the swirler gas fuel ports extends from a first gas fuel passage to
one of the air chambers, and wherein each of the downstream face
gas fuel ports extends from a second gas fuel passage to the
downstream face of the fuel nozzle.
12. The diffusion combustor fuel nozzle of claim 1, wherein each of
the swirler gas fuel ports is in fluid communication with a first
gas fuel source, and wherein each of the downstream face gas fuel
ports is in fluid communication with the first gas fuel source.
13. The diffusion combustor fuel nozzle of claim 1, wherein each of
the swirler gas fuel ports is in fluid communication with a first
gas fuel source, and wherein each of the downstream face gas fuel
ports is in fluid communication with a second gas fuel source.
14. The diffusion combustor fuel nozzle of claim 1, further
comprising a liquid fuel passage and a liquid fuel outlet for a
flow of liquid fuel, wherein the liquid fuel passage extends
towards the downstream face of the fuel nozzle, and wherein the
liquid fuel outlet is positioned about the downstream face of the
fuel nozzle.
15. A method of operating a diffusion combustor fuel nozzle of a
gas turbine engine, the method comprising: providing one or more
flows of gas fuel through the fuel nozzle; passing a first portion
of the one or more flows of gas fuel through a plurality of swirler
gas fuel ports defined in a swirler positioned about a downstream
face of the fuel nozzle; and passing a second portion of the one or
more flows of gas fuel through a plurality of downstream face gas
fuel ports defined in the downstream face of the fuel nozzle.
16. The method of claim 15, further comprising mixing the first
portion of the one or more flows of fuel with a flow of air within
air chambers of the swirler, and passing the mixed fuel-air flow
into a combustion chamber of the diffusion combustor.
17. A diffusion combustor fuel nozzle for a gas turbine engine, the
fuel nozzle comprising: one or more gas fuel passages for one or
more flows of gas fuel, the one or more gas fuel passages extending
towards a downstream face of the fuel nozzle; a swirler surrounding
the one or more gas fuel passages and positioned about the
downstream face of the fuel nozzle, the swirler comprising a
plurality of swirl vanes and a plurality of air chambers each
defined between adjacent swirl vanes; a plurality of swirler gas
fuel ports each defined in the swirler between adjacent swirl
vanes; and a plurality of downstream face gas fuel ports defined in
the downstream face of the fuel nozzle.
18. The diffusion combustor fuel nozzle of claim 17, wherein each
of the swirler gas fuel ports extends from a first gas fuel passage
to one of the air chambers, and each of the downstream face gas
fuel ports extends from the first gas fuel passage to the
downstream face of the fuel nozzle.
19. The diffusion combustor fuel nozzle of claim 17, wherein each
of the swirler gas fuel ports extends from a first gas fuel passage
to one of the air chambers, and wherein each of the downstream face
gas fuel ports extends from a second gas fuel passage to the
downstream face of the fuel nozzle.
20. The diffusion combustor fuel nozzle of claim 17, further
comprising a liquid fuel passage and a liquid fuel outlet for a
flow of liquid fuel, wherein the liquid fuel passage extends
towards the downstream face of the fuel nozzle, and wherein the
liquid fuel outlet is positioned about the downstream face of the
fuel nozzle.
Description
TECHNICAL FIELD
[0001] The present application and the resultant patent relate
generally to gas turbine engines and more particularly relate to a
diffusion combustor fuel nozzle including fuel ports configured to
limit emissions such as nitrogen oxides and the like while
maintaining efficient performance of the gas turbine engine.
BACKGROUND OF THE INVENTION
[0002] Operational efficiency in a gas turbine engine generally
increases as the temperature of the combustion stream increases.
Higher combustion stream temperatures, however, may result in the
production of high levels of nitrogen oxides (NO.sub.X) and other
types of undesirable emissions. Such emissions may be subject to
both federal and state regulations in the United States and also
may be subject to similar regulations abroad. A balancing act thus
exists between operating the gas turbine engine within an efficient
temperature range while also ensuring that the output of nitrogen
oxides and other types of regulated emissions remain well below
mandated levels. Many other types of operational parameters also
may be varied in providing such an optimized balance.
[0003] In a gas turbine engine that includes a diffusion-type
combustor, i.e., non-premixed, fuel is injected into an air swirler
of a fuel nozzle. Air flows through the air swirler so as to mix
with the fuel for downstream combustion. In certain air swirler
configurations, the mixing of the air and the fuel may produce high
combustion stream temperatures, which may result in the production
of high levels of NO.sub.X. Additionally, in certain air swirler
configurations, the fuel and the resultant hot combustion gases may
become entrained in a recirculation zone downstream of the air
swirler. As a result, the liner surrounding the fuel nozzles and
the combustion chamber may experience relatively high head-end
temperatures. Moreover, the relatively high head-end temperatures
may be increased even further when the combustor burns certain
types of liquid fuels. Such high temperatures may have an impact on
the integrity and the lifetime of the liner and other
components.
[0004] There is thus a desire for an improved fuel nozzle for use
in a combustor, particularly a diffusion type combustor in a gas
turbine engine. Such a fuel nozzle for a diffusion type combustor
may limit recirculation of the fuel and the hot combustion gases
downstream of the fuel nozzle. Additionally, such a fuel nozzle for
a diffusion combustor may efficiently combust the fuel and the air
streams therein with limited emissions while also limiting liner
temperatures for increased component lifetime.
SUMMARY OF THE INVENTION
[0005] The present application and the resultant patent thus
provide a diffusion combustor fuel nozzle for a gas turbine engine.
The fuel nozzle may include one or more gas fuel passages for one
or more flows of gas fuel, a swirler surrounding the one or more
gas fuel passages and positioned about a downstream face of the
fuel nozzle, a number of swirler gas fuel ports defined in the
swirler, and a number of downstream face gas fuel ports defined in
the downstream face of the fuel nozzle. The swirler may include a
number of swirl vanes and a number of air chambers defined between
adjacent swirl vanes.
[0006] The present application and the resultant patent further
provide a method of operating a diffusion combustor fuel nozzle of
a gas turbine engine. The method may include the steps of providing
one or more flows of gas fuel through the nozzle, passing a first
portion of the one or more flows of gas fuel through a number of
swirler gas fuel ports defined in a swirler positioned about a
downstream face of the fuel nozzle, and passing a second portion of
the one or more flows of gas fuel through a number of downstream
face gas fuel ports defined in the downstream face of the fuel
nozzle.
[0007] The present application and the resultant patent further
provide a diffusion combustor fuel nozzle for a gas turbine engine.
The fuel nozzle may include one or more gas fuel passages for one
or more flows of gas fuel, a swirler surrounding the one or more
gas fuel passages and positioned about a downstream face of the
fuel nozzle, a number of swirler gas fuel ports defined in the
swirler, and a number of downstream face gas fuel ports defined in
the downstream face of the fuel nozzle. The one or more gas fuel
passages may extend towards the downstream face of the fuel nozzle.
The swirler may include a number of swirl vanes and a number of air
chambers defined between adjacent swirl vanes. The number of
swirler gas fuel ports each may be defined in the swirler between
adjacent swirl vanes.
[0008] These and other features and improvements of the present
application and the resultant patent will become apparent to one of
ordinary skill in the art upon review of the following detailed
description when taken in conjunction with the several drawings and
the appended claims.
BRIEF DESCRIPTION OF THE DRAWINGS
[0009] FIG. 1 is a schematic diagram of a gas turbine engine
including a compressor, a combustor, and a turbine.
[0010] FIG. 2 is a side view of an example of a combustor such as
that shown in FIG. 1.
[0011] FIG. 3 is a side cross-sectional view of a fuel nozzle that
may be used in the combustor of FIG. 2.
[0012] FIG. 4 is a front plan view of the fuel nozzle of FIG.
3.
[0013] FIG. 5 is a side cross-sectional view of a fuel nozzle as
may be described herein.
[0014] FIG. 6 is a front plan view of the fuel nozzle of FIG.
5.
[0015] FIG. 7 is a side cross-sectional view of a fuel nozzle as
may be described herein.
DETAILED DESCRIPTION
[0016] Referring now to the drawings, in which like numerals refer
to like elements throughout the several views, FIG. 1 shows a
schematic view of a gas turbine engine 10 as may be used herein.
The gas turbine engine 10 may include a compressor 15. The
compressor 15 compresses an incoming flow of air 20. The compressor
15 delivers the compressed flow of air 20 to a combustor 25. The
combustor 25 mixes the compressed flow of air 20 with a pressurized
flow of fuel 30 and ignites the mixture to create a flow of
combustion gases 35. Although only a single combustor 25 is shown,
the gas turbine engine 10 may include any number of combustors 25.
The flow of combustion gases 35 is in turn delivered to a turbine
40. The flow of combustion gases 35 drives the turbine 40 so as to
produce mechanical work. The mechanical work produced in the
turbine 40 drives the compressor 15 via a shaft 45 and an external
load 50 such as an electrical generator and the like. Other
configurations and other components may be used herein.
[0017] The gas turbine engine 10 may use natural gas, various types
of syngas, and/or other types of fuels. The gas turbine engine 10
may be any one of a number of different gas turbine engines offered
by General Electric Company of Schenectady, N.Y., including, but
not limited to, those such as a 7 or a 9 series heavy duty gas
turbine engine and the like. The gas turbine engine 10 may have
different configurations and may use other types of components.
Other types of gas turbine engines also may be used herein.
Multiple gas turbine engines, other types of turbines, and other
types of power generation equipment also may be used herein
together.
[0018] FIG. 2 shows an example of the combustor 25 that may be used
with the gas turbine engine 10 and the like. The combustor 25 may
include a number of fuel nozzles 55 therein. Each of the fuel
nozzles 55 may direct the flow of air 20, the flow of fuel 30, and
optional flows of other fluids for combustion therein. Any number
of the fuel nozzles 55 may be used in any configuration. The fuel
nozzles 55 may be attached to an end cover 60 near a head-end 65 of
the combustor 25. The flows of the air 20 and the fuel 30 may be
directed through the end cover 60 and the head-end 65 into each of
the fuel nozzles 55 so as to distribute a fuel-air mixture
downstream thereof.
[0019] The combustor 25 also may include a combustion chamber 70
therein. The combustion chamber 70 may be defined by a combustion
casing 75, a combustion liner 80, a flow sleeve 85, and the like.
The liner 80 and the flow sleeve 85 may be coaxially positioned
with respect to one another so as to define an air pathway 90 for
the flow of air 20 therethrough. The combustion chamber 70 may lead
to a downstream transition piece 95. The flows of the air 20 and
the fuel 30 may mix downstream of the fuel nozzles 55 for
combustion within the combustion chamber 70. The flow of combustion
gases 35 then may be directed via the transition piece 95 towards
the turbine 40 so as to produce useful work therein. Other
components and other configuration also may be used herein.
[0020] FIGS. 3 and 4 show an example of the fuel nozzle 55 that may
be used with the combustor 25 and the like. The fuel nozzle 55 may
be a diffusion fuel nozzle 100. More specifically, the fuel nozzle
55 may be a dual fuel nozzle 105. Given such, the flow of fuel 30
may include one or more flows of a gas fuel 110 such as natural gas
and one or more flows of a liquid fuel 115 such as a syngas and the
like. Other types of fuel flows and other types of combinations of
fuel flows may be used herein.
[0021] The fuel nozzle 55 may include an outer tube 120. The outer
tube 120 may lead to a downstream face 125 with a fuel nozzle tip
130. The outer tube 120 may include a number of fuel, air, and
water passages therein. Specifically, a number of gas fuel passages
135 may extend through the outer tube 120 and may be axially
positioned about the downstream face 125. The gas fuel passages 135
may be in communication with the flow of gas fuel 110. A number of
tip outlets 140 also may extend through the outer tube 120 and may
be positioned about the fuel nozzle tip 130. The tip outlets 140
may include a liquid fuel outlet 145 in communication with the flow
of liquid fuel 115. The tip outlets 140 also may include an
atomizing air outlet 150 in communication with a flow of atomizing
air as well as a water outlet 155 in communication with a flow of
water. Other components and other configurations may be used
herein.
[0022] A swirler 160 may be positioned about the downstream face
125 of the fuel nozzle 55. The swirler 160 may include a number of
swirl vanes 165. The swirl vanes 165 may define a number of air
chambers 170. The air chambers 170 may be in fluid communication
with the flow of air 20 from the end cover 60. A number of gas fuel
ports 175 may extend from the gas fuel passages 135 to the air
chambers 170 for guiding and delivering at least a portion of the
flow of gas fuel 110. The flow of air 20 and the flow of gas fuel
110 thus may begin to mix about the swirler 160 for combustion
within the downstream combustion chamber 70. Generally described,
all of the flow of air 20 thus passes through the air chambers 170
of the swirler 160 as a swirler flow 180. A collar 185 may surround
the swirler 160. A cone (not shown) may extend from the fuel nozzle
55 to the liner 80. Other types of fuel nozzles 55 and other types
of combustors 25 may be used herein with differing types of fuel.
Likewise, other components and other configurations may be used
herein.
[0023] FIG. 5 and FIG. 6 show a fuel nozzle 200 as may be described
herein. The fuel nozzle 200 may be a diffusion nozzle with little
to no upstream fuel-air premixing. The fuel nozzle 200 also may be
a dual fuel nozzle 205 for use with both a flow of gas fuel 210 and
a flow of the liquid fuel 215. Other types of flows may be used
herein. In a manner similar to that described above, the fuel
nozzle 200 includes a downstream face 225, a fuel nozzle tip 230,
and one or more gas fuel passages 235 extending through the fuel
nozzle 200. The gas fuel passages 235 may extend towards the
downstream face 225. The fuel nozzle 200 also may include a number
of tip outlets 240. The tip outlets 240 may be positioned about the
fuel nozzle tip 230 about the downstream face 225. The fuel nozzle
200 also may include one or more liquid fuel passages 242, and the
tip outlets 240 may include one or more liquid fuel outlets 245
corresponding to the one or more liquid fuel passages 242. The tip
outlets 240 also may include outlets for atomizing air, water, and
the like. Other components and other configurations also may be
used herein.
[0024] The fuel nozzle 200 also may include a swirler 260
positioned about the downstream face 225 thereof. The swirler 260
surrounds the fuel nozzle tip 230. The swirler 260 may include a
number of swirl vanes 265 that define a number of air chambers 270
extending therethrough. The swirl vanes 265 and the air chambers
270 may have any size, shape, or configuration. Any number of the
swirl vanes 265 and the air chambers 270 may be used herein. A
number of swirler gas fuel ports 275 may be defined in the swirler
260. The swirler gas fuel ports 275 may extend from one of the gas
fuel passages 235 to the air chambers 270 for guiding and
delivering at least a portion of the flow of gas fuel 210
therethrough. Each of the swirler gas fuel ports 275 may be defined
in the swirler 260 between adjacent swirl vanes 265 and upstream of
the downstream face 225 of the nozzle 200. An air inlet 277 may be
defined on the upstream end of the swirler 260 in communication
with the flow of air 20 from the end cover 60. In a manner similar
to that described above, the flow of air 20 thus enters the air
inlet 277 and passes through the air chambers 270 as a swirler flow
280. The air inlet 277 may have any size, shape, or configuration.
Additionally, a collar 285 may surround the swirler 260, and a cone
(not shown) may extend from the fuel nozzle 200 to the liner 80.
The nozzle 200 also may include a number of downstream face gas
fuel ports 290 defined in the downstream face 225 of the nozzle
200. The downstream face gas fuel ports 290 may extend from one of
the gas fuel passages 235 to the downstream face 225 of the nozzle
200 for guiding and delivering at least a portion of the flow of
gas fuel 210 therethrough. The downstream face gas fuel ports 290
may be parallel to an axis of the fuel nozzle 200. Alternatively,
the downstream face gas fuel ports 290 may be angled relative to
the axis of the fuel nozzle 200. Other components and other
configurations also may be used herein.
[0025] In use, at least a first portion of the flow of gas fuel 210
passes through one of the gas fuel passages 235, through the
swirler gas fuel ports 275, and into the air chambers 270 of the
swirler 260. At least a second portion of the flow of gas fuel 210
passes through one of the gas fuel passages 235, through the
downstream face gas fuel ports 290, and out of the nozzle 200 into
the combustion chamber 70. Likewise, the flow of liquid fuel 215,
the atomizing airflow, and the water flow pass through the tip
outlets 240 and out of the nozzle 200 into the combustion chamber
70. The flow of air 20 passes through the air inlet 277 of the
swirler 260 and into the air chambers 270 as the swirler flow 280.
The first portion of the flow of gas fuel 210 and the swirler flow
280 begin to mix within the air chambers 270 of the swirler 260 to
create a mixed fuel-air flow passing into the combustion chamber
70. Accordingly, the combustion chamber 70 receives the mixed
fuel-air flow from the swirler 260 and the second portion of the
flow of gas fuel 210 from the downstream face gas fuel ports 290
for combustion within the combustion chamber 70.
[0026] As shown in FIG. 5, the swirler gas fuel ports 275 and the
downstream face gas fuel ports 290 may be in fluid communication
with the same gas fuel passage 235. Accordingly, the same type of
gas fuel would pass through the swirler gas fuel ports 275 and the
downstream face gas fuel ports 290, forming the mixed fuel-air flow
from the swirler 260 and the second portion of the flow of gas fuel
210 from the downstream face gas fuel ports 290. In this manner,
the gas fuel passage 235 may deliver gas fuel from a common fuel
source to the swirler gas fuel ports 275 and the downstream face
gas fuel ports 290. As discussed above, the nozzle 200 also may
include a liquid fuel passage 242 and a liquid fuel outlet 245 for
passing a flow of liquid fuel 215, such that the nozzle 200
operates as a dual fuel nozzle.
[0027] Alternatively, as shown in FIG. 7, the swirler gas fuel
ports 275 and the downstream face gas fuel ports 290 may be in
fluid communication with different gas fuel passages 235. For
example, the swirler gas fuel ports 275 may be in fluid
communication with a first gas fuel passage 292, and the downstream
face gas fuel ports 290 may be in fluid communication with a second
gas fuel passage 294. As shown, the first gas fuel passage 292 is
separate from, and thus is not in fluid communication with, the
second gas fuel passage 294. In this manner, a first type of gas
fuel may be delivered from a first fuel source, through the first
gas fuel passage 292, and through the swirler gas fuel ports 275,
while a second type of gas fuel may be delivered from a second fuel
source, through the second gas fuel passage 294, and through the
downstream face gas fuel ports 290, such that the nozzle 200
operates as a dual fuel nozzle. Additionally, the nozzle 200 also
may include a flow of liquid fuel 215, such that the nozzle 200
operates as a tri fuel nozzle.
[0028] In use, the different flows of fuel through the nozzle 200
may be varied according to the operational mode of the gas turbine
engine 10. For example, the dual fuel nozzle 200, as shown in FIG.
5, may be operated at startup or low load conditions by passing the
flow of liquid fuel 215 through the liquid fuel outlet 245 and into
the combustion chamber 70, while no gas fuel is passed through the
swirler gas fuel ports 275 or the downstream face gas fuel ports
290. In contrast, the dual fuel nozzle 200 may be operated at base
load conditions by passing the flow of gas fuel 210 through the
swirler gas fuel ports 275 and the downstream face gas fuel ports
290. The ratio of the area of the swirler gas fuel ports 275 and
the area of the downstream face gas fuel ports 290 may be selected
to achieve optimum emissions, lean blowout (LBO) margining,
dynamics, exit profile, and metal temperatures.
[0029] As another example, the tri fuel nozzle 200, as shown in
FIG. 7, may be operated at startup or low load conditions by
passing the flow of liquid fuel 215 through the liquid fuel outlet
245 and into the combustion chamber 70, while no gas fuel is passed
through the swirler gas fuel ports 275 or the downstream face gas
fuel ports 290. Alternatively, the tri fuel nozzle 200 may be
operated at startup or low load conditions by passing the first gas
fuel through the swirler gas fuel ports 275, while no fuel is
passed through the downstream face gas fuel ports 290 or the liquid
fuel outlet 245. In contrast, the tri fuel nozzle 200 may be
operated at base load conditions by passing the first portion of
the flow of gas fuel 210 through the swirler gas fuel ports 275 and
the second portion of the flow of gas fuel 210 through the
downstream face gas fuel ports 290, while no fuel is passed through
the liquid fuel outlet 245. The ratio of the area of the swirler
gas fuel ports 275 and the area of the downstream face gas fuel
ports 290 may be selected to achieve optimum emissions, LBO
margining, dynamics, exit profile, and metal temperatures.
[0030] Passing a flow of gas fuel 210 through both the swirler gas
fuel ports 275 and the downstream face gas fuel ports 290 prevents
the mixed fuel-air flow and/or the flow of combustion gases 35 from
being entrained in a recirculation zone about the fuel nozzle 200.
The configuration of the fuel ports 275, 290 thus limits NO.sub.x
emissions and the like. Accordingly, the fuel nozzle 200 produces
an unexpected result with respect to emissions because generally
accepted wisdom in the art teaches that a reduction in fuel-air
premixing will result in increased emissions. In other words, by
passing a portion of the flow of gas fuel 210 through the
downstream face gas fuel ports 290, and thus not premixing that
portion with the flow of air 20, the NO.sub.x emissions of the fuel
nozzle 200 are unexpectedly reduced even though the degree of
premixing carried out in the fuel nozzle 200 is reduced.
Furthermore, the reduction in premixing may reduce combustion
stream temperatures and thus extend the useful lifetime of the
liner 80 and other components in the hot gas path. The water to
fuel ratio also may be reduced as a result of the configuration of
the fuel ports 275, 290.
[0031] The fuel nozzle 200 described herein thus limits natural gas
emissions while providing wide fuel flexibility. Compared to the
traditional approach of increasing fuel-air premixing, the fuel
nozzle 200 described herein actually lowers premixing so as to
improve overall NO.sub.x emissions. This non-intuitive approach of
lowering fuel-air premixing is distinct from such traditional fuel
nozzle designs and operational theories. The use of the swirler gas
fuel ports 275 and the downstream face gas fuel ports 290 described
herein thus improves emissions and overall component lifetime.
[0032] It should be apparent that the foregoing relates only to
certain embodiments of the present application and the resultant
patent. Numerous changes and modifications may be made herein by
one of ordinary skill in the art without departing from the general
spirit and scope of the invention as defined by the following
claims and the equivalents thereof.
* * * * *