U.S. patent application number 11/035560 was filed with the patent office on 2006-07-20 for gas turbine combustor.
This patent application is currently assigned to Siemens Westinghouse Power Corporation. Invention is credited to Robert J. Bland.
Application Number | 20060156734 11/035560 |
Document ID | / |
Family ID | 36682425 |
Filed Date | 2006-07-20 |
United States Patent
Application |
20060156734 |
Kind Code |
A1 |
Bland; Robert J. |
July 20, 2006 |
Gas turbine combustor
Abstract
A combustor (18) for a gas turbine engine (10) includes a
combustor burner (34) receiving an oxidizer flow (36). The
combustor burner includes an annular vortex generator (38) disposed
around a central region (40) of the burner. A fuel outlet (46) is
disposed proximate the vortex generator for discharging a
combustible fuel (47) into the oxidizer flow. A pilot burner (56)
is disposed in the central region of the burner.
Inventors: |
Bland; Robert J.; (Oviedo,
FL) |
Correspondence
Address: |
Siemens Corporation;Intellectual Property Department
170 Wood Avenue South
Iselin
NJ
08830
US
|
Assignee: |
Siemens Westinghouse Power
Corporation
|
Family ID: |
36682425 |
Appl. No.: |
11/035560 |
Filed: |
January 15, 2005 |
Current U.S.
Class: |
60/776 ;
60/748 |
Current CPC
Class: |
F23R 3/12 20130101; F23R
3/286 20130101; F23R 3/343 20130101 |
Class at
Publication: |
060/776 ;
060/748 |
International
Class: |
F23R 3/14 20060101
F23R003/14 |
Claims
1. A combustor comprising: a burner receiving an oxidizer flow, the
burner comprising an annular vortex generator disposed around a
central region of the burner and separating a first portion of the
oxidizer flow from a second portion of the oxidizer flow; a fuel
outlet disposed proximate the vortex generator discharging a
combustible fuel into at least one of the portions of the oxidizer
flow; and a pilot burner disposed in the central region of the
burner.
2. The combustor of claim 1, the annular vortex generator
comprising: a plurality of circumferentially spaced apart radially
extending lobes defining a plurality of external flow directing
channels between the spaced apart lobes conducting the first
portion along external surfaces of each lobe; and the lobes
defining a plurality of internal flow directing channels conducting
the second portion along internal surfaces of each lobe.
3. The combustor of claim 2, wherein a first lobe comprises a
different geometry than a second lobe effective to generate
different respective vortex flow patterns.
4. The combustor of claim 3, wherein the fuel outlet comprises a
plurality of radially extending fuel pegs disposed to discharge the
combustible fuel into the first portion flowing through the
external flow directing channels.
5. The combustor of claim 4, wherein the fuel pegs are radially
aligned with the lobes to inject the combustible fuel into the
external flow directing channels.
6. The combustor of claim 5, wherein each fuel peg comprises
opposed fuel orifices spaced apart along a radial length of the peg
for directing respective jets of the combustible fuel at an oblique
angle to a flow direction of the first portion.
7. The combustor of claim 1, wherein the fuel outlet is disposed
upstream of the vortex generator.
8. The combustor of claim 1, wherein the fuel outlet is disposed
between an upstream end of the vortex generator and a downstream
end of the vortex generator.
9. The combustor of claim 8, wherein the fuel outlet comprises an
orifice positioned in a surface of the vortex generator 38.
10. The combustor of claim 1, wherein the fuel outlet is disposed
to discharge the combustible fuel into the first potion and the
second portion.
11. A gas turbine engine comprising the combustor of claim 1.
12. A combustor comprising: a plurality of combustor burners spaced
apart around a central region, each burner receiving an oxidizer
flow at an inlet of the burner; a lobe vortex generator disposed
around a central region of each burner downstream of the inlet and
separating a first portion of the oxidizer flow from a second
portion of the respective oxidizer flow; a pilot burner disposed in
the central region of the burner; and a fuel outlet disposed
proximate each vortex generator discharging a combustible fuel into
at least one of the respective portions of the oxidizer flow.
13. A combustion method comprising: dividing an oxidizer flow
flowing within a combustor into first and second portions;
injecting a combustible fuel into the first portion to produce a
fuel/oxidizer mixture; imparting a flow direction change to at
least one of the second portion and the fuel/oxidizer mixture so
that the second portion and the fuel/oxidizer mixture flow at
different angles with respect to each other; combining the second
portion and the fuel/oxidizer mixture after imparting the flow
direction change to create a vortex; and allowing the second
portion and the fuel/oxidizer mixture to mix downstream of the
vortex to create combustible mixture.
14. The method of claim 13, further comprising providing a pilot
burner proximate the downstream end of the burner to ignite the
combustible mixture.
15. A combustor comprising: a combustor burner receiving an
oxidizer flow, the burner comprising an annular vortex generator
disposed around a central region of the burner; a fuel outlet
disposed proximate the vortex generator discharging a combustible
fuel into the oxidizer flow; and a pilot burner disposed in the
central region of the burner.
16. The combustor of claim 15, wherein the annular vortex generator
comprises a plurality of flow directing elements.
17. The combustor of claim 16, wherein a first flow directing
element comprises a different geometry than a second flow directing
element to generate different respective vortex flow patterns of
the oxidizer flow.
18. A gas turbine engine comprising the combustor of claim 15.
Description
FIELD OF THE INVENTION
[0001] This invention relates generally to gas turbines, and, more
particularly, to a gas turbine combustor including a vortex
generator.
BACKGROUND OF THE INVENTION
[0002] Gas turbines having annular combustors are known to include
a plurality of individual burners disposed in a ring about an axial
centerline for providing a mixture of fuel and air to an annular
combustion chamber disposed upstream of a turbine inlet. Each
burner may include an annular main burner comprising a swirler
disposed annularly around a central pilot burner. The combustion
process of the plurality of burners interacts in the combustion
chamber because all burners discharge their respective combustible
mixtures into the single annular combustion chamber. Consequently,
combustion processes for one burner may affect the combustion
processes in the other burners. Burners for such annular combustors
are generally simple to fabricate and are mechanically robust.
[0003] Gas turbines having can-annular combustors are known wherein
individual cans, including a combustion zone within the can, feed
hot combustion gas into respective individual portions of an arc of
a turbine inlet. Each can includes a plurality of main burners
disposed in a ring around a central pilot burner. Each of the main
burners may comprise an annular swirler. Cross flame tubes may be
provided to connect the cans. Can annular combustors are generally
more expensive to fabricate as a result of the use of multiple
burners within each of the combustor burners.
[0004] Combustion dynamics concerns vary among the different types
of combustor designs. Annular combustion chamber dynamics are
generally dominated by circumferential pressure pulsation modes
between the plurality of burners. In contrast, each burner of a can
annular combustor is relatively isolated from interaction with the
combustion process of adjacent cans. Accordingly, can annular
combustion chamber dynamics are generally dominated by axial
pressure pulsation modes within the individual burners. Fuel
staging may be used to stabilize the combustion process. This
approach, however, may produce an undesirable level of exhaust
emissions, such as oxides of nitrogen (NO.sub.x).
[0005] The demand to decrease exhaust emissions while simplifying
combustor construction continues, thus improved techniques for
economically controlling the combustion conditions of a gas turbine
engine are needed.
BRIEF DESCRIPTION OF THE DRAWINGS
[0006] The invention will be more apparent from the following
description in view of the drawings that show:
[0007] FIG. 1 is a functional diagram of a gas turbine engine
having an improved combustor design.
[0008] FIG. 2 is a sectional view of an improved burner for use
with an annular embodiment of the combustor of FIG. 1.
[0009] FIG. 3 shows an end view of the burner of FIG. 2 as seen
along line 3-3.
[0010] FIG. 4 is a sectional view of an exemplary annular
embodiment of the combustor of FIG. 1 including a plurality of
improved burners.
[0011] FIG. 5 is a sectional view of an improved combustor burner
for use with a can-annular embodiment of the combustor of FIG.
1.
[0012] FIG. 6 is a sectional view of an improved burner for use
with the combustor of FIG. 1.
DETAILED DESCRIPTION OF THE INVENTION
[0013] FIG. 1 illustrates a gas turbine engine 10 having a
compressor 12 for receiving a flow of filtered ambient air 14 and
for producing a flow of compressed air 16. The compressed air 16 is
received by a combustor 18 where it is used to burn a flow of a
combustible fuel 20, such as natural gas or fuel oil provided by
fuel supply 24, to produce a flow of hot combustion gas 22. In one
embodiment, the combustor 18 may be a burner annular type combustor
including a plurality of combustor burners feeding hot combustion
gas into respective individual portions of an arc of a turbine
inlet 33. In another embodiment, the combustor 18 may be an annular
type combustor including a plurality of individual burners disposed
in a ring about an axial centerline of the combustor 18 for
providing a mixture of fuel and air to an annular combustion
chamber disposed upstream of the turbine inlet 33.
[0014] The hot combustion gas 22 from the combustor 18 is received
by a turbine 26, where it is expanded to extract mechanical shaft
power. A common shaft 28 may interconnect the turbine 26 with the
compressor 12, as well as an electrical generator 30, to provide
mechanical power for compressing the ambient air 14 and for
producing electrical power, respectively. The expanded combustion
gas 32 may be exhausted directly to the atmosphere or it may be
routed through additional heat recovery systems (not shown).
[0015] The gas turbine engine 10 provides improved structural
robustness and operability as a result of features of the combustor
18 that are shown more clearly in FIG. 2. FIG. 2 is a cross
sectional view of a combustor burner 34 used, for example, in an
annular type embodiment of the combustor 18. FIG. 2 illustrates a
cross section taken perpendicular to a direction of flow through
the combustor 18 and shows a portion 74 of an annular combustion
chamber 75 in fluid communication with the burner 34. The combustor
burner 34 generally includes a outer annulus 39, a fuel outlet 46,
and an annular vortex generator 38. The combustor burner 34
receives an oxidizer flow, such as a respective burner portion 36
of the compressed air 16 and a respective burner portion 37 of the
flow of combustible fuel 20, and discharges a respective burner
portion 23 of the hot combustion gas 22. The annular vortex
generator 38 may be disposed around a central region 40 of the
burner 34 for generating a vortex in a fluid flow flowing past the
vortex generator 38, thereby promoting mixing of fluid flows
downstream of the vortex generator 38. To avoid creation of flame
holding zones proximate a downstream end 50 of the vortex generator
38, vortex generator 38 may be configured to limit generation of
flow zones having flow speeds of less than 10 meters per second. In
an embodiment, the vortex generator 38 separates a first portion 42
of the respective burner portion 36 from a second portion 44 of the
respective burner portion 36 and imparts a flow direction change to
at least one of the portions 42, 44 so that the portions 42, 44
exit the vortex generator 38 at different angles with respect to
each other.
[0016] A fuel outlet 46 may be disposed proximate the vortex
generator 38, such as upstream of an upstream end 48 of the vortex
generator 38, for discharging a fuel outlet portion 47 of the
respective burner portion 37 into one, or both, of the portions 42,
44. At the downstream end 50 of the vortex generator 38, the
portions 42, 44 exiting the vortex generator 38 at different angles
with respect to each other are combined to create a vortex 52 to
promote mixing of the portions 42, 44 to create a combustible
mixture 54. The downstream end 50 of the vortex generator 38 may
open directly into the portion 74 of an annular combustion chamber
35 to provide the combustible mixture 54 therein. The combustible
mixture 54 may then be combusted in the portion 74 of the
combustion chamber 75 to generate a respective burner portion 23 of
the hot combustion gas 22 provided to the downstream turbine 26. A
pilot burner 56, supplied by a pilot portion 49 of the burner
portion 37 may be located in the central region 40 for igniting the
combustible mixture 54.
[0017] In an aspect of the invention that may be more readily
viewed in FIG. 3, the annular vortex generator 38 may include a
lobe mixer. FIG. 3 shows an end view of the combustor burner 34 of
FIG. 2 as seen along line 3-3, wherein the annular vortex generator
38 is a lobe mixer. The lobe mixer includes a plurality of
circumferentially spaced apart radially extending lobes 58 defining
a plurality of external flow directing channels 60 between the
spaced apart lobes 58 conducting, for example, the second portion
44 along external surfaces 62 of each lobe 58. The lobes 58 also
define a plurality of internal flow directing channels 64
conducting the first portion 42 along internal surfaces 66 of each
lobe 58. The lobes 58 may be arranged so that the first portion 42
entering at the upstream end 48 of the vortex generator 38 and
flowing along the internal surface 66 is given a radially outward
directed flow component, while the second portion 44 flowing along
the exterior surface 62 is given a radially inward directed
component so that when the portions 42, 44 exit the vortex
generator 38, the portions 42, 44 are directed to flow at different
angles with respect to each other, thereby producing a vortex 52
downstream of the downstream end 50 of the vortex generator 38.
Advantageously, the vortex 52 promotes mixing of the portions 42,
44 to produce the combustible mixture 54 as well as promoting
suction of a pilot flame 43 burning in a pilot zone 41 into the
vortex 52. A swirling flow of the vortex 52 is "coated" by the
pilot flame 43 and then burns from an exterior portion of the
vortex radially inward. In an aspect of the invention, the lobes 58
may comprise different geometries to generate different respective
vortex flow patterns to achieve different burn patterns. For
example, lobe 59 may have a wider, shorter cross sectional profile
at the downstream end 50 than another lobe 58, thereby creating a
different vortex flow patterns among the differently shaped lobes
58, 59 as the portions 42, 44 exit the vortex generator 38.
[0018] In another aspect of the invention shown in FIGS. 2 and 3,
the fuel outlet 46 may comprise a plurality of radially extending
fuel pegs 66 disposed to discharge the fuel outlet portion 47 of
the burner portion 37 into one or both of the portions 42, 44
flowing through the respective flow directing channels 60, 64. The
fuel pegs 66 may be radially aligned with the lobes 58 to inject
the fuel outlet portion 47 of the combustible fuel 20 into the
respective directing channels 60, 64. For example, each fuel peg 46
may include opposed fuel orifices 68 spaced apart along a radial
length of the peg 46 for directing respective jets 69 of the fuel
outlet portion 47 of the combustible fuel 20 at an oblique angle to
an axial flow direction of the burner portion 36 of the compressed
air 16 to provide improved mixing of the fuel outlet portion 47 of
the fuel 20 into the portions 42, 44 than if the fuel 20 was
injected coaxially to the flow direction. The number, size and
orientation of the fuel orifices 68 may be configured to achieve a
desired fuel/oxidizer ratio in the resulting combustible mixture
54.
[0019] The fuel outlet 46 may be disposed upstream of the vortex
generator 38 as shown in FIG. 2, or the outlet 46 may be disposed
between the upstream end 48 and the downstream end 50 of the vortex
generator 38. The fuel outlet 46 may be configured to inject the
fuel outlet portion 47 of the combustible fuel 20 into one or both
of the portions 42, 44 flowing through the through the respective
flow directing channels 60, 64. In an aspect of the invention shown
in FIG. 2, the fuel outlet portion 47 of the combustible fuel 20
may be delivered to the vortex generator 38 and directed to exit
from an orifice 70 in a surface of the vortex generator 38 into an
oxidizer flow flowing along the surface of the vortex generator 38.
For example, the fuel orifice 70, in fluid communication with the
fuel source 24, may be provided in the internal 66 and/or the
external surface 62 of the vortex generator 38 to inject fuel into
the respective portions 42, 44 of the compressed air 16 flowing
over the surfaces 66, 62.
[0020] FIG. 4 illustrates a section taken perpendicular to the
direction of flow through an exemplary annular embodiment of the
combustor 18 of FIG. 1. The annular embodiment may include a
plurality of combustor burners 34, such as the burner depicted in
FIG. 2, spaced apart in a ring around a central region 72 of the
combustor 18. A cylindrical liner 76 surrounds the plurality of
combustor burners 34. Each burner 34 may include an annular vortex
generator 38, such as a lobe mixer, disposed around a central
region 40 of the burner 34, and a fuel outlet 46 (such as shown in
FIG. 2) disposed proximate the vortex generator 38. Each burner 34
may provide a fuel/air mixture to a respective portion of the
annular combustion chamber 74 as shown in FIG. 2.
[0021] In another aspect of the invention shown in FIG. 5, the
burner 34, incorporating the innovative features of the vortex
generator 38 and the corresponding fuel outlet 46 such as depicted
in FIG. 2, may be configured for use in a can annular embodiment of
the combustor 18, wherein the burner 34 is in fluid communication
with a combustion zone 41 defined by a can liner 78. A plurality of
burners 34 maybe spaced apart around the central region 72 such as
shown in FIG. 2. Each burner 34 may feed hot combustion gas 23,
such as via a known transition piece, into respective individual
portions of an arc of a turbine inlet. Advantageously, the burner
34 may be configured to be interchangeably used in can annular type
combustors and annular type combustors with limited or no
modifications necessary to adapt the burner 34 to either type. For
example, only a mounting arrangement at the downstream end 50 of
the burner 34 may need to be modified for accommodating respective
attachment configurations in a can annular or annular embodiment of
the combustor 18.
[0022] In yet another aspect of the invention depicted in FIG. 6,
the vortex generator 38 may include a plurality of annularly
arranged flow directing elements 80, 81 projecting into the burner
portion of compressed air 36 to cause different portions 42, 44 to
be directed to flow at different angles with respect to each other,
thereby producing a vortex 52 downstream of the downstream end 50
of the vortex generator 38. For example, the flow directing
elements 80, 81 may be pyramid-shaped bluff bodies annularly spaced
apart around an inside circumference 82 of the outer annulus 39. In
an embodiment, the elements 80, 81 may be configured to have
different geometries to generate different respective vortexes 52,
53 to achieve desired flow field patterns downstream of the
downstream end 50 of the vortex generator 38. For example, the
elements 80,81 may extend radially inwards from the inside
circumference 82 different distances, or the elements may be shaped
differently to generate different respective vortexes 52, 53.
[0023] While various embodiments of the present invention have been
shown and described herein, it will be obvious that such
embodiments are provided by way of example only. Numerous
variations, changes and substitutions may be made without departing
from the invention herein. Accordingly, it is intended that the
invention be limited only by the spirit and scope of the appended
claims.
* * * * *