U.S. patent application number 12/872743 was filed with the patent office on 2012-03-01 for fuel nozzle and method for swirl control.
This patent application is currently assigned to GENERAL ELECTRIC COMPANY. Invention is credited to Mahesh Bathina, Ronald James Chila, Senthamil Selvan.
Application Number | 20120052451 12/872743 |
Document ID | / |
Family ID | 45697721 |
Filed Date | 2012-03-01 |
United States Patent
Application |
20120052451 |
Kind Code |
A1 |
Bathina; Mahesh ; et
al. |
March 1, 2012 |
FUEL NOZZLE AND METHOD FOR SWIRL CONTROL
Abstract
According to one aspect of the disclosure, an apparatus for
injecting fuel is provided, where the apparatus includes a cone
structure that includes a passage to form a swirl of an air-fuel
mixture in a combustion chamber. The apparatus also includes at
least one adjustable vane positioned in the passage configured to
control the swirl of the air-fuel mixture and control a flame
stability.
Inventors: |
Bathina; Mahesh; (Bangalore,
IN) ; Chila; Ronald James; (Greer, SC) ;
Selvan; Senthamil; (Bangalore, IN) |
Assignee: |
GENERAL ELECTRIC COMPANY
Schenectady
NY
|
Family ID: |
45697721 |
Appl. No.: |
12/872743 |
Filed: |
August 31, 2010 |
Current U.S.
Class: |
431/9 ;
431/350 |
Current CPC
Class: |
F23R 3/26 20130101; F23R
3/14 20130101; F23R 3/286 20130101; F23C 2900/07002 20130101 |
Class at
Publication: |
431/9 ;
431/350 |
International
Class: |
F23M 3/00 20060101
F23M003/00; F23D 14/46 20060101 F23D014/46 |
Claims
1. A fuel nozzle comprising: a cone structure that includes a
passage to form a swirl of an air-fuel mixture in a combustion
chamber; and at least one adjustable vane positioned in the passage
configured to control the swirl of the air-fuel mixture and control
a flame stability.
2. The fuel nozzle of claim 1, wherein the at least one adjustable
vane is configured control an axial flow component of the
swirl.
3. The fuel nozzle of claim 1, wherein the at least one adjustable
vane comprises a plurality of axially staged adjustable vanes.
4. The fuel nozzle of claim 1, wherein the cone structure comprises
an inner cone and an outer cone.
5. The fuel nozzle of claim 1, wherein the at least one adjustable
vane is configured to control a mean radius of the swirl.
6. The fuel nozzle of claim 1, wherein the cone structure comprises
an inner cone, an outer cone and a center cone.
7. The fuel nozzle of claim 1, wherein the at least one adjustable
vane comprises a plurality of radial adjustable vanes.
8. A method for injecting fuel, comprising: mixing air and fuel in
a passage within a cone structure to form an air-fuel mixture;
directing the air-fuel mixture from the passage into a combustion
chamber; forming a swirl with the air-fuel mixture; and adjusting a
position of at least one adjustable vane to control a property of
the swirl of the air-fuel mixture.
9. The method of claim 8, wherein adjusting a position of at least
one adjustable vane comprises reducing flame holding in a fuel
nozzle.
10. The method of claim 8, wherein adjusting a position of at least
one adjustable vane comprises pivoting the at least one adjustable
vane along a radial axis.
11. The method of claim 8, wherein adjusting a position of at least
one adjustable vane comprises pivoting the at least one adjustable
vane along a tangential axis.
12. The method of claim 8, wherein adjusting a position of at least
one adjustable vane controlling a mean radius of the swirl.
13. The method of claim 8, wherein adjusting a position of at least
one adjustable vane comprises controlling an axial flow component
of the swirl.
14. A combustor, comprising: a combustion chamber; an air supply in
fluid communication with at least one fuel nozzle positioned in the
combustion chamber; and a fuel supply in fluid communication with
the at least one fuel nozzle, wherein the at least one fuel nozzle
comprises: a cone structure that includes a passage to form an
air-fuel swirl in the combustion chamber; and at least one
adjustable vane positioned in the passage configured to control a
property of the air-fuel swirl and control a flame stability.
15. The combustor of claim 14, wherein the property of the air-fuel
swirl comprises an axial flow component of the air-fuel swirl.
16. The combustor of claim 15, wherein a position of the at least
one adjustable vane is configured to reduce flame holding.
17. The combustor of claim 14, wherein the property of the air-fuel
swirl comprises a mean radius of the swirl.
18. The combustor of claim 14, wherein the cone structure comprises
an inner cone and an outer cone.
19. The combustor of claim 14, wherein the at least one adjustable
vane comprises a plurality of axially staged adjustable vanes.
20. The combustor of claim 14, wherein the at least one adjustable
vane comprises a plurality of radial adjustable vanes.
Description
BACKGROUND OF THE INVENTION
[0001] The subject matter disclosed herein relates to gas turbines.
More particularly, the subject matter relates to combustors in gas
turbines.
[0002] In a gas turbine, a combustor converts chemical energy of a
fuel or an air-fuel mixture into thermal energy. The thermal energy
is conveyed by a fluid, often air from a compressor, to a turbine
where the thermal energy is converted to mechanical energy. Several
factors influence the efficiency of the conversion of thermal
energy to mechanical energy. The factors may include blade passing
frequencies, fuel supply fluctuations, fuel type and reactivity,
combustor head-end volume, fuel nozzle design, air-fuel profiles,
flame shape, air-fuel mixing, flame holding and flame
stabilization. For example, a highly reactive fuel is desirable due
to combustion characteristics and/or cost. However, highly reactive
fuel can increase incidences of flame holding. Flame stability is
influenced by the fuel nozzles as they project the air-fuel mixture
into the combustion chamber. Control over flame stability may lead
to control of the location of the combustion, where it is desirable
to prevent portions of the flame from forming in the fuel nozzle.
In addition, flame development in the nozzle can cause inefficient
combustion and shorten the life of the nozzle and combustor.
BRIEF DESCRIPTION OF THE INVENTION
[0003] According to one aspect of the invention, an apparatus for
injecting fuel is provided, where the apparatus includes a cone
structure that includes a passage to form a swirl of an air-fuel
mixture in a combustion chamber. The apparatus also includes at
least one adjustable vane positioned in the passage configured to
control the swirl of the air-fuel mixture and control a flame
stability.
[0004] According to another aspect of the invention, a method for
injecting fuel is provided, where the method includes mixing air
and fuel in a passage within a cone structure to form an air-fuel
mixture and directing the air-fuel mixture from the passage into in
a combustion chamber. The method further includes forming a swirl
with the air-fuel mixture and adjusting a position of at least one
adjustable vane to control a flame stability and control a property
of the swirl of the air-fuel mixture.
[0005] These and other advantages and features will become more
apparent from the following description taken in conjunction with
the drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0006] The subject matter, which is regarded as the invention, is
particularly pointed out and distinctly claimed in the claims at
the conclusion of the specification. The foregoing and other
features, and advantages of the invention are apparent from the
following detailed description taken in conjunction with the
accompanying drawings in which:
[0007] FIG. 1 is a sectional side view of a portion of an
embodiment of a gas turbine engine, including a combustor, fuel
nozzles and compressor;
[0008] FIG. 2 is a detailed sectional side view of an embodiment of
a fuel nozzle;
[0009] FIG. 3 is a detailed sectional side view of an embodiment of
a fuel nozzle;
[0010] FIG. 4 is a cross sectional view of an embodiment of an
adjustable vane, as shown in FIG. 2; and
[0011] FIG. 5 is a cross sectional view of an embodiment of
adjustable vanes and a cone structure, as shown in FIG. 3.
[0012] The detailed description explains embodiments of the
disclosure together with advantages and features, by way of example
with reference to the drawings.
DETAILED DESCRIPTION OF THE INVENTION
[0013] FIG. 1 is a sectional side view of a portion of an
embodiment of a gas turbine engine 10, including a combustor 100
and compressor 102. The gas turbine engine includes the compressor
102, combustor 100 and a turbine 103, wherein the turbine is
depicted schematically. In the turbine engine 10, combustion of an
air fuel mixture in the combustor 100 rotates the turbine 103 to
generate mechanical energy in the form of rotational output.
Rotation of the turbine 103 also compresses air within the
compressor 102. Further, the gas turbine engine may include a
plurality of compressors 102, combustors 100 and turbines 103.
[0014] In an aspect, the combustor 100 uses liquid and/or gas fuel,
such as natural gas or a hydrogen rich synthetic gas, to run the
engine. For example, fuel nozzles 104 are coupled to a cover plate
105 and intake an air supply 106 and a fuel supply 107. The air
supply 106 and fuel supply 107 are in fluid communication with the
fuel nozzles 104. The air flow or supply 106 is directed to the
fuel nozzles 104 from a discharge plenum 108 and diffuser 109 of
the compressor 102. The fuel nozzles 104 mix the fuel supply 107
with the air supply 106 to create an air-fuel mixture, and
discharge the air-fuel mixture into the combustor 100. As depicted,
air is directed from the diffuser 109 to the discharge plenum 108
and along an annular passage 110 to the fuel nozzles 104. The fuel
nozzles 104 direct an air-fuel mixture, shown by arrow 112, into a
combustion chamber 114, thereby causing a combustion that creates a
hot pressurized exhaust gas 116. The combustor 100 directs the hot
pressurized exhaust gas 116 through a transition piece 118 into a
turbine nozzle 120, causing turbine 103 rotation.
[0015] In an embodiment, the fuel nozzles 104 mix air supply 106
with the fuel supply 107 to create a swirl of the air-fuel mixture
that forms a flow 112 into the combustion chamber 114. For example,
the fuel nozzles 104 injects an air-fuel mixture into the combustor
114 in a suitable ratio for improved combustion, emissions, fuel
consumption, and power output. Properties of the air-fuel mixture
and the air-fuel swirl may affect combustion. For example, a fuel
nozzle 104 configuration changes a mean swirl radius and/or
velocity of the nozzle flow, thereby affecting the location of the
flame and reducing incidence of flame holding in the nozzle 104.
Flame holding may be described as a flame formation in an
undesirable location in the nozzle, wherein the flame causes high
temperatures that can damage the nozzle. Flame stability may be
described as control over a location and size of a flame in a
combustor, wherein a stable flame of a selected size is
consistently formed in a selected location in the combustion
chamber.
[0016] FIG. 2 is a sectional side view of an embodiment of a fuel
nozzle 200. The fuel nozzle 200 includes an outer cone 202 and
inner cone 204 coupled to a flange 206. A passage 208 for flow of
an air-fuel mixture is located between the outer cone 202 and inner
cone 204. The outer cone 202 and inner cone 204 are also described
as forming a cone structure. Adjustable vanes 210 are positioned
within the passage 208 to control a flow of the air-fuel mixture
into a conical chamber 211. Gaseous fuel flow 212 is directed along
fuel passage 214, where the fuel is injected through inlets 216 and
mixed with air from the compressor in passage 208. In an
embodiment, the adjustable vanes 210 are configured to control a
swirling of the air-fuel mixture as it enters the conical chamber
211, indicated by arrows 218. As depicted, liquid fuel port 220 is
located in an upstream portion of the nozzle 200 to direct a stream
222 of liquid fuel to mix with the air-fuel swirl mixture during
turbine engine startup.
[0017] In one embodiment, the adjustable vanes 210 are axially
staged, where the position of one or more of the vanes 210 is
adjusted to control an axial flow component of the air-fuel swirl
mixture. For example, the axially staged adjustable vanes 210 are
airfoil shaped and pivot along a radial axis 223, thereby affecting
an axial component of the nozzle flow, indicated by arrow 224, of
the air-fuel mixture as it flows 218 into the chamber 211. This is
described in detail in FIG. 4. Thus, the position of adjustable
vanes 210 and corresponding axial flow components cause a change in
the downstream or axial velocity of the nozzle flow 226, thereby
reducing flame holding propensity. Accordingly, the axially staged
adjustable vanes 210 improve combustion efficiency while reducing
wear and tear on the fuel nozzle 200. In addition, the adjustable
vanes 210 may be configured to control various properties of the
nozzle flow 226, such as swirl mean radius 228, radial flow
velocity, axial flow velocity, swirl vortex length and other
characteristics that affect combustion. As shown, the swirl mean
radius 228 is measured from a nozzle axis 230, where the swirl mean
radius 228 is one measure of the overall size of the nozzle vortex.
In some embodiments, the swirl mean radius 228 and vortex size
affect the air-fuel mixture and the combustion efficiency of the
turbine.
[0018] With continued reference to FIG. 2, the adjustable vanes 210
are configured to enable use of a highly reactive gaseous fuel by
adding an axial flow or velocity component to the air-fuel mixture
226. Specifically, the axially staged adjustable vanes 210 may be
configured to add an axial flow component to force the air-fuel
mixture in the combustion chamber. Therefore, the adjustable vanes
210 reduce the chances of flame holding or flashback when using
highly reactive or volatile fuel. In some embodiments, it is
desirable to use a highly reactive fuel, such as those with a high
hydrogen content (e.g., H.sub.2) and the higher order paraffins,
due to a high flame temperature and related chemical and
thermodynamic properties. Accordingly, the fuel nozzles 200 with
adjustable vanes 210 are configured to provide flow control of an
air-fuel mixture that enables use of a range of fuels in a turbine
engine. For example, when a fuel with low reactivity is used in the
turbine, at least one adjustable vane 210 is in a neutral position,
where no axial flow component is added to the air-fuel mixture.
This is desirable because the risk of flame holding and unwanted
combustion in the nozzle is be reduced with low reactivity fuel.
Further, when a highly reactive fuel is used, the at least one
adjustable vane 210 pivots along radial axis 223 in the passage 208
to add an axial flow component to the air-fuel mixture 226, thereby
directing the flow into the combustion chamber. In one embodiment,
the position of the adjustable vane 210 adds the axial velocity
component that causes desirable combustion in the combustion
chamber. Accordingly, by pushing or directing the air-fuel mixture
226 into the combustion chamber, the possibility of flame holding
in the fuel nozzle 200 is reduced while also increasing flame
stability and control over flame stability. The fuel nozzle 200 may
contain one or more adjustable vanes 210, which may be of any
suitable shape, such as an airfoil, configured to control a fluid
flow in a selected direction. In an embodiment, the adjustable
vanes 210 are synchronized, where each of vanes 210 are similarly
positioned to cause a substantially similar directional component
to the fluid flow across the fuel nozzle 200. Alternatively, each
adjustable vane 210 is independently moved to cause different fluid
flow from selected regions of the passage 208 into the conical
chamber 211. In addition, the adjustable vane 210 may be made of
any suitable durable and strong material, such as a steel alloy or
composite.
[0019] FIG. 3 is a sectional side view of another embodiment of a
fuel nozzle 300. The fuel nozzle 300 (or "fuel injector") includes
an outer cone 302, inner cone 304 and passage 306. The passage 306
is located between inner cone 302 and outer cone 304 to direct an
air-fuel flow into the nozzle 300. As depicted, a center cone 308
is located between the outer cone 302 and inner cone 304, where the
components form a cone structure in the nozzle 300. The center cone
308 divides the passage 306 into two passages for at least a
portion of the fuel nozzle 300. The outer cone 302, inner cone 304
and center cone 308 are each coupled to a flange 310. Adjustable
vanes 312 are positioned between outer cone 302 and center cone
308. Similarly, adjustable vanes 312 are positioned between inner
cone 304 and center cone 308. In an embodiment, the adjustable
vanes 312 are pivotally coupled to a portion of the cone structure.
For example, a first adjustable vane 312 is pivotally coupled to
the outer cone 302 and a second adjustable vane 312 is pivotally
coupled to the center cone 308, wherein the adjustable vanes 312
are positioned to control an air-fuel mixture as it flows through
passage 306. As depicted, the adjustable vanes 312 are coupled to
pivot along a tangential axis 313.
[0020] In one embodiment, gaseous fuel flow or supply 314 is routed
through passages 316 to fuel inlets 318, where the fuel is mixed
with air in the passages 306. The adjustable vanes 312 direct an
air-fuel mixture 320 into a conical chamber 321 that flows
downstream into the combustor chamber. A liquid fuel port 322 is
located in an upstream portion of the nozzle 300 to direct a stream
324 of liquid fuel into conical chamber 321 during turbine engine
startup. In one embodiment, the air-fuel mixture 320 flows
downstream 326, towards the combustor, forming an air-fuel mixture
vortex 328. In an embodiment, the adjustable vanes 312 may be
referred to as radial adjustable vanes because they control
properties of the air-fuel vortex 328, such as a swirl mean radius
330 of the vortex. As depicted, the swirl mean radius 330 is a
dimension measured from nozzle axis 332, where the radial
adjustable vanes 312 control the swirl mean radius 330 as it flows
into the combustor chamber. By controlling the swirl mean radius
330, flame stability is controlled to improve efficiency and reduce
wear on fuel nozzles 300 and other components. In addition, by
controlling the swirl mean radius 300, the radial adjustable vanes
312 also affect the axial length of the vortex 328. For example,
the radial adjustable vanes 312 are positioned to form a vortex 328
with a small swirl mean radius 330 and long axial length of the
vortex 328, thereby causing the air-fuel mixture to extend into the
combustion chamber. This causes the flame to form in a desired
location in the chamber, thereby controlling flame stability. In an
embodiment, adjustable vanes 312 also control the axial velocity as
the vortex 328 exits the fuel nozzle 300 to influence the size of a
recirculation bubble formed in the combustion chamber, where a
large recirculation bubble can also affect flame stability.
[0021] In embodiments, the radial adjustable vanes 312 are
positioned at angles relative to the flow path or the cone
structure. For example, a first radial adjustable vane 312 is in an
open position allowing unblocked flow into the conical chamber 321,
while a second radial adjustable vane 312 is in a closed position
completely blocking a flow into the chamber 321. In another
embodiment, the positions of the radial adjustable vanes 312 are
synchronized. In yet another embodiment, a single radial adjustable
vane 312 is positioned in the passage 306 to control a property of
the air-fuel swirl. As discussed herein, adjustable vanes 312 may
be configured to provide axial and/or tangential flow components to
change an axial and/or tangential flow velocity of an air-fuel
mixture, thereby improving the air-fuel mixture and controlling the
formation and size of the vortex. Further, by controlling
parameters of the air-fuel swirl, combustion and flame location are
controlled to reduced flame holding and prevent damage to the fuel
nozzle 300.
[0022] FIG. 4 is a cross sectional view of an embodiment of an
adjustable vane 400, taken along line 4-4 of FIG. 2. As depicted,
the adjustable guide vane 400 is in the shape of an airfoil and
includes a leading edge 402, trailing edge 404 and pivot point 406.
The adjustable guide vane moves about the pivot point 406, as shown
by arrow 408, where a position of the adjustable guide vane 400
controls a property of the air-fuel swirl in the combustor. An
angle 410 of the adjustable guide vane 400, with respect to
air-fuel flow 412, may add an axial flow component to the velocity
of the air-fuel swirl. In an embodiment, the adjustable guide vane
400 are described as an axial adjustable guide vane or axially
staged guide vane that pivots along a radial axis 414 to cause a
change in the axial flow component of the air-fuel mixture. In one
example, the angle 410 is between 0 and 90 degrees to change a flow
component of the air-fuel swirl. In another example, the angle 410
is between 5 and 60 degrees to change or add a flow component to
the air-fuel swirl.
[0023] FIG. 5 is a cross sectional view of a portion of an
embodiment of a fuel nozzle, taken along line 5-5 of FIG. 3. The
position of the fuel nozzle includes an outer cone 500, inner cone
502, center cone 504, first adjustable guide vane 506 and second
adjustable guide vane 508. The first adjustable guide vane 506 is
positioned in a first passage 510 and the second adjustable guide
vane 508 is positioned in a second passage 512. In one embodiment,
an air-fuel mixture flows through the first passage 510 and second
passage 512, as indicated by arrows 514 and 516, respectively. The
positions of the first adjustable guide vane 506 and the second
adjustable guide vane 508 may be adjusted, as shown by arrows 516
and 518, respectively. The first adjustable vane 506 includes a
pivot point 520 to enable pivotal movement 516. Similarly, the
second adjustable vane 508 includes a pivot point 522 to enable
pivotal movement 518. In embodiments, there are one or more
adjustable guide vanes (506, 508) positioned between the outer cone
500 and inner cone 502.
[0024] In one embodiment, the adjustable vanes 506 and 508 are
referred to as radial adjustable vanes, where the vanes 506 and 508
are configured to control a size and/or mean radius of the air-fuel
vortex in the nozzle and combustion chamber by adjusting the
position of one or more of the vanes 506 and 508. For example, an
angle 524 of the first guide vane 506, relative to an air-fuel flow
526 are adjusted to control a property of the vortex, such as the
swirl mean radius. As depicted, the radial guide vanes 506 and 508
are configured to pivot about two tangential axes to enable control
of an air-fuel swirl parameter. The one or more tangential axes are
substantially parallel to tangents of the circumference of the
nozzle cone structures. In an embodiment, the center cone 504 is
not to be located along the entire circumference of the conical
nozzle and is only located near the passage (510, 512) exits into
the conical chamber. For example, the inner cone 502 and outer cone
500 form a single passage for a portion of the nozzle and the
passages 510 and 512 are formed in the portion of the nozzle near
the passage exits where the center cone 504 structure is located.
In other embodiments, the adjustable vanes 506 and 508 control a
flow by changing a position or shape of the vanes using a shape
memory material, where the shape memory material is configured to
change from a first shape to a second shape when an energy is
applied to it. For example, adjustable vanes 506 and 508 may
include an alloy, such as Nickel Titanium, embedded in a flexible
carbon composite, where a current is selectively applied to the
alloy to alter a shape or dimension, such as an angle of the vane
or chord and/or span of the vanes.
[0025] While the invention has been described in detail in
connection with only a limited number of embodiments, it should be
readily understood that the invention is not limited to such
disclosed embodiments. Rather, the invention can be modified to
incorporate any number of variations, alterations, substitutions or
equivalent arrangements not heretofore described, but which are
commensurate with the spirit and scope of the invention.
Additionally, while various embodiments of the invention have been
described, it is to be understood that aspects of the invention may
include only some of the described embodiments. Accordingly, the
invention is not to be seen as limited by the foregoing
description, but is only limited by the scope of the appended
claims.
* * * * *