U.S. patent application number 13/294272 was filed with the patent office on 2013-05-16 for combustor and method for supplying fuel to a combustor.
This patent application is currently assigned to GENERAL ELECTRIC COMPANY. The applicant listed for this patent is Patrick Benedict Melton, Lucas John Stoia. Invention is credited to Patrick Benedict Melton, Lucas John Stoia.
Application Number | 20130122436 13/294272 |
Document ID | / |
Family ID | 47226017 |
Filed Date | 2013-05-16 |
United States Patent
Application |
20130122436 |
Kind Code |
A1 |
Stoia; Lucas John ; et
al. |
May 16, 2013 |
COMBUSTOR AND METHOD FOR SUPPLYING FUEL TO A COMBUSTOR
Abstract
A combustor includes a casing that encloses at least a portion
of the combustor. A fuel conduit extends downstream from the casing
and includes a tortuous path for fuel flow inside the fuel conduit.
A method for supplying fuel to a combustor includes flowing a
working fluid through tubes that extend axially through an end cap.
The method further includes supplying a fuel through a fuel conduit
into the end cap, supplying a diluent through a diluent conduit
that extends axially inside the fuel conduit, and swirling the fuel
flowing through the fuel conduit around the diluent flowing through
the diluent conduit.
Inventors: |
Stoia; Lucas John; (Taylors,
SC) ; Melton; Patrick Benedict; (Horse Shoe,
NC) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Stoia; Lucas John
Melton; Patrick Benedict |
Taylors
Horse Shoe |
SC
NC |
US
US |
|
|
Assignee: |
GENERAL ELECTRIC COMPANY
Schenectady
NY
|
Family ID: |
47226017 |
Appl. No.: |
13/294272 |
Filed: |
November 11, 2011 |
Current U.S.
Class: |
431/12 ; 431/144;
431/354 |
Current CPC
Class: |
F23R 3/286 20130101;
F23R 3/283 20130101 |
Class at
Publication: |
431/12 ; 431/354;
431/144 |
International
Class: |
F23N 1/02 20060101
F23N001/02; F23Q 25/00 20060101 F23Q025/00; F23D 14/62 20060101
F23D014/62 |
Claims
1. A combustor, comprising: a. a casing that encloses at least a
portion of the combustor; b. a fuel conduit that extends downstream
from the casing; and c. a tortuous path for fuel flow inside the
fuel conduit.
2. The combustor as in claim 1, wherein the tortuous path for fuel
flow comprises a spiral path for fuel flow inside the fuel
conduit.
3. The combustor as in claim 1, further comprising a plurality of
baffles arranged on an inside surface of the fuel conduit.
4. The combustor as in claim 1, further comprising a plurality of
turbulators arranged on an outside surface of the fuel conduit.
5. The combustor as in claim 1, further comprising a diluent
conduit that extends axially inside the fuel conduit.
6. The combustor as in claim 5, further comprising a diluent plenum
downstream from the fuel conduit, wherein the diluent conduit
provides fluid communication to the diluent plenum.
7. The combustor as in claim 1, further comprising a plurality of
tubes radially arranged across the combustor and in fluid
communication with the fuel conduit.
8. The combustor as in claim 7, further comprising a divider that
extends downstream from the fuel conduit to separate the plurality
of tubes into tube bundles.
9. The combustor as in claim 1, further comprising a fuel plenum
downstream from the fuel conduit, wherein the fuel conduit provides
fluid communication to the fuel plenum.
10. A combustor, comprising: a. an end cover; b. an end cap axially
separated from the end cover and configured to extend radially
across at least a portion of the combustor, wherein the end cap
comprises an upstream surface axially separated from a downstream
surface; c. a fuel conduit that extends from the end cover to the
end cap to provide fluid communication to the end cap; and d. a
tortuous path for fuel flow inside the fuel conduit.
11. The combustor as in claim 10, wherein the tortuous path for
fuel flow comprises a spiral path for fuel flow inside the fuel
conduit.
12. The combustor as in claim 10, further comprising a plurality of
baffles arranged on an inside surface of the fuel conduit.
13. The combustor as in claim 10, further comprising a plurality of
turbulators arranged on an outside surface of the fuel conduit.
14. The combustor as in claim 10, further comprising a diluent
conduit that extends axially inside the fuel conduit to the end
cap.
15. The combustor as in claim 10, further comprising a plurality of
tubes radially arranged in the end cap and in fluid communication
with the fuel conduit.
16. The combustor as in claim 15, further comprising a divider that
extends axially inside the end cap to separate the plurality of
tubes into a plurality of tube bundles.
17. The combustor as in claim 10, further comprising a fuel nozzle
that extends axially through the end cap.
18. A method for supplying fuel to a combustor, comprising: a.
flowing a working fluid through a plurality of tubes that extends
axially through an end cap; b. supplying a fuel through a fuel
conduit into the end cap; c. supplying a diluent through a diluent
conduit that extends axially inside the fuel conduit; and d.
swirling the fuel flowing through the fuel conduit around the
diluent flowing through the diluent conduit.
19. The method as in claim 18, further comprising disrupting a
fluid flow across an outside surface of the fuel conduit.
20. The method as in claim 18, further comprising separating the
fuel from the diluent inside the end cap.
Description
FIELD OF THE INVENTION
[0001] The present invention generally involves a combustor and a
method for supplying fuel to the combustor.
BACKGROUND OF THE INVENTION
[0002] Combustors are commonly used in industrial and power
generation operations to ignite fuel to produce combustion gases
having a high temperature and pressure. Various competing
considerations influence the design and operation of combustors.
For example, higher combustion gas temperatures generally improve
the thermodynamic efficiency of the combustor. However, higher
combustion gas temperatures also promote flashback or flame holding
conditions in which the combustion flame migrates towards the fuel
being supplied by nozzles, possibly causing severe damage to the
nozzles in a relatively short amount of time. In addition, higher
combustion gas temperatures generally increase the disassociation
rate of diatomic nitrogen, increasing the production of nitrogen
oxides (NO.sub.X). Conversely, lower combustion gas temperatures
associated with reduced fuel flow and/or part load operation
(turndown) generally reduce the chemical reaction rates of the
combustion gases, increasing the production of carbon monoxide and
unburned hydrocarbons.
[0003] In a particular combustor design, a plurality of tubes may
be radially arranged in an end cap to provide fluid communication
for a working fluid to flow through the end cap and into a
combustion chamber. A fuel may be supplied to a plenum inside the
end cap to flow over the outside of the tubes to provide convective
cooling to the tubes before flowing into the tubes to mix with the
working fluid. The enhanced mixing between the fuel and working
fluid in the tubes allows leaner combustion at higher operating
temperatures while protecting against flashback or flame holding
and controlling undesirable emissions. However, the convective
cooling provided by the fuel before entering the tubes may result
in uneven heating of the fuel. As a result, temperature and density
variations in the fuel flowing through the tubes may produce
thermal stress in the tubes and/or uneven fuel-working fluid ratios
that adversely affect flame stability, combustor performance,
and/or undesirable emissions. Therefore, an improved combustor and
method for supplying fuel to the combustor that reduces thermal
stress in the tubes and/or temperature and density variations in
the fuel flowing through the tubes would be useful.
BRIEF DESCRIPTION OF THE INVENTION
[0004] 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.
[0005] One embodiment of the present invention is a combustor that
includes a casing that encloses at least a portion of the
combustor. A fuel conduit extends downstream from the casing and
includes a tortuous path for fuel flow inside the fuel conduit.
[0006] Another embodiment of the present invention is a combustor
that includes an end cover and an end cap axially separated from
the end cover and configured to extend radially across at least a
portion of the combustor, wherein the end cap comprises an upstream
surface axially separated from a downstream surface. A fuel conduit
extends from the end cover to the end cap to provide fluid
communication to the end cap and includes tortuous path for fuel
flow inside the fuel conduit.
[0007] Embodiments of the present invention may also include a
method for supplying fuel to a combustor that includes flowing a
working fluid through a plurality of tubes that extends axially
through an end cap. The method further includes supplying a fuel
through a fuel conduit into the end cap, supplying a diluent
through a diluent conduit that extends axially inside the fuel
conduit, and swirling the fuel flowing through the fuel conduit
around the diluent flowing through the diluent conduit.
[0008] 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
[0009] 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:
[0010] FIG. 1 is a simplified cross-section view of an exemplary
combustor according to one embodiment of the present invention;
[0011] FIG. 2 is an upstream axial view of the combustor shown in
FIG. 1 according to an embodiment of the present invention; and
[0012] FIG. 3 is an enlarged cross-section view of the conduit
shown in FIG. 1 according to one embodiment of the present
invention.
DETAILED DESCRIPTION OF THE INVENTION
[0013] Reference will now be made in detail to present embodiments
of the invention, one or more examples of which are illustrated in
the accompanying drawings. The detailed description uses numerical
and letter designations to refer to features in the drawings. Like
or similar designations in the drawings and description have been
used to refer to like or similar parts of the invention. As used
herein, the terms "first", "second", and "third" may be used
interchangeably to distinguish one component from another and are
not intended to signify location or importance of the individual
components. In addition, the terms "upstream" and "downstream"
refer to the relative location of components in a fluid pathway.
For example, component A is upstream from component B if a fluid
flows from component A to component B. Conversely, component B is
downstream from component A if component B receives a fluid flow
from component A.
[0014] 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.
[0015] Various embodiments of the present invention include a
combustor and method for supplying fuel to the combustor. The
combustor generally includes a casing that encloses a working fluid
flowing through the combustor. A plurality of tubes radially
arranged in an end cap enhances mixing between the working fluid
and fuel prior to combustion. In particular embodiments, a fuel
conduit may extend between the casing and the end cap to supply
fuel to the end cap. The fuel may flow through a tortuous path
inside the fuel conduit adjacent to a diluent conduit that extends
axially inside the fuel conduit to evenly heat the fuel before the
fuel flows into the end cap. The improved heating of the fuel
reduces the thermal stress across the tubes and/or the temperature
and density variations in the fuel flowing through the tubes to
enhance flame stability, combustor performance, and/or undesirable
emissions. Although exemplary embodiments of the present invention
will be described generally in the context of a combustor
incorporated into a gas turbine for purposes of illustration, one
of ordinary skill in the art will readily appreciate that
embodiments of the present invention may be applied to any
combustor and are not limited to a gas turbine combustor unless
specifically recited in the claims.
[0016] FIG. 1 provides a simplified cross-section view of an
exemplary combustor 10 according to one embodiment of the present
invention, and FIG. 2 provides an upstream axial view of the
combustor 10 shown in FIG. 1. As shown, a casing 12 generally
encloses at least a portion of the combustor 10 to contain a
working fluid 14 flowing to the combustor 10. The casing 12 may
include an end cover 16 at one end that provides an interface for
supplying fuel, diluent, and/or other additives to the combustor
10. Possible diluents may include, for example, water, steam,
working fluid, air, fuel additives, various inert gases such as
nitrogen, and/or various non-flammable gases such as carbon dioxide
or combustion exhaust gases supplied to the combustor 10. One or
more fluid conduits 18 may extend axially from the end cover 16 to
an end cap 20 to provide fluid communication for fuel, diluents,
and/or other additives to the end cap 20. The end cap 20 is
configured to extend radially across at least a portion of the
combustor 10, and the end cap 20 and a liner 22 generally define a
combustion chamber 24 downstream from the end cap 20. The casing 12
circumferentially surrounds the end cap 20 and/or the liner 22 to
define an annular passage 26 that surrounds the end cap 20 and
liner 22. In this manner, the working fluid 14 may flow through the
annular passage 26 along the outside of the liner 22 to provide
convective cooling to the liner 22. When the working fluid 14
reaches the end cover 16, the working fluid 14 may reverse
direction to flow through the end cap 20 and into the combustion
chamber 24.
[0017] The end cap 20 generally includes an upstream surface 28
axially separated from a downstream surface 30, and one or more
nozzles 32 and/or tubes 34 may extend from the upstream surface 28
through the downstream surface 30 to provide fluid communication
through the end cap 20 to the combustion chamber 24. The particular
shape, size, number, and arrangement of the nozzles 32 and tubes 34
may vary according to particular embodiments. For example, the
nozzles 32 and tubes 34 are generally illustrated as having a
cylindrical shape; however, alternate embodiments within the scope
of the present invention may include nozzles and tubes having
virtually any geometric cross-section.
[0018] The nozzle 32 may extend axially from the end cover 16
through the end cap 20. A shroud 36 may circumferentially surround
the nozzle 32 to define an annular passage 38 around the nozzle 32
and provide fluid communication through the end cap 20. The working
fluid 14 may thus flow through the annular passage 38 and into the
combustion chamber 24. In addition, the nozzle 32 may supply fuel,
diluents, and/or other additives to the annular passage 38 to mix
with the working fluid 14 before entering the combustion chamber
24. One or more vanes 40 may extend radially between the nozzle 32
and the shroud 36 to impart swirl to the fluids flowing through the
annular passage 38 to enhance mixing of the fluids before reaching
the combustion chamber 24.
[0019] The tubes 34 may be radially arranged across the end cap 20
in one or more tube bundles 42 of various shapes and sizes, with
each tube bundle 42 in fluid communication with one or more fluid
conduits 18. For example, as shown in FIG. 2, one or more dividers
44 may extend downstream from the fluid conduits 18 axially inside
the end cap 20 between the upstream and downstream surfaces 28, 30
to separate or group the tubes 34 into pie-shaped tube bundles 42
radially arranged around the nozzle 32. One or more fluid conduits
18 may provide one or more fuels, diluents, and/or other additives
to each tube bundle 42, and the type, fuel content, and reactivity
of the fuel and/or diluent may vary for each fluid conduit 18 or
tube bundle 42. In this manner, different types, flow rates, and/or
additives may be supplied to one or more tube bundles 42 to allow
staged fueling of the tubes 34 over a wide range of operating
conditions.
[0020] A cap shield 46 may circumferentially surround at least a
portion of the upstream and downstream surfaces 28, 30 to at least
partially define one or more plenums inside the end cap 20 between
the upstream and downstream surfaces 28, 30. For example, as shown
most clearly in FIG. 1, a barrier 48 may extend radially inside the
end cap 20 between the upstream and downstream surfaces 28, 30 to
at least partially define a fuel plenum 50 and a diluent plenum 52
inside the end cap 20. Specifically, the upstream surface 28, cap
shield 46, and barrier 48 may define the fuel plenum 50, and the
downstream surface 30, cap shield 46, and barrier 48 may define the
diluent plenum 52. One or more of the tubes 34 may include one or
more fuel ports 54 that provide fluid communication from the fuel
plenum 50 into the tubes 34. The fuel ports 54 may be angled
radially, axially, and/or azimuthally to project and/or impart
swirl to the fuel flowing through the fuel ports 54 and into the
tubes 34. The fuel may then mix with the working fluid 14 flowing
through the tubes 34 before entering the combustion chamber 24.
[0021] FIG. 3 provides an enlarged cross-section view of the fluid
conduit 18 shown in FIG. 1 according to one embodiment of the
present invention. As shown, the fluid conduit 18 may include a
fuel conduit 60 that surrounds a diluent conduit 62. The fuel
conduit 60 may extend downstream from the casing 12 or end cover 16
to the end cap 20 to provide fluid communication to the fuel plenum
50 inside the end cap 20. The fuel conduit 60 may include a
tortuous path for fuel flow inside the fuel conduit 60 to increase
the distance that the fuel travels, and thus the heat transferred
to the fuel from the surrounding working fluid 14 and/or other
diluent, before the fuel reaches the fuel plenum 50 inside the end
cap 20. For example, the fuel conduit 60 may include a plurality of
baffles 64 or other flow guides arranged on an inside surface of
the fuel conduit 60 that direct and/or disrupt the fuel flow inside
the fuel conduit 60 to enhance the heat exchange from the working
fluid 14 or other diluent to the fuel. In the particular embodiment
shown in FIG. 3, the baffles 64 may be attached to or machined into
the inside surface of the fuel conduit 60 to create a spiral path
for fuel flow around the diluent conduit 62.
[0022] The diluent conduit 62 may extend generally axially inside
the fuel conduit 60 between the end cover 16 and the end cap 20 to
provide fluid communication to the diluent plenum 52. Possible
diluents supplied through the diluent conduit 62 may include, for
example, water, steam, working fluid, fuel additives, various inert
gases such as nitrogen, and/or various non-flammable gases such as
carbon dioxide or combustion exhaust gases supplied to the
combustor 10. The diluent may be supplied to the diluent conduit 62
through the end cover 16 from an external source. Alternately, or
in addition, a bypass passage 66 in the end cover 16 may provide
fluid communication for a portion of the working fluid 14 to flow
into the diluent conduit 62 to heat the fuel flowing around the
diluent conduit 62. After reaching the end cap 20, the working
fluid 14 or other diluent may flow into the diluent plenum 52 and
around the tubes 34 to convectively cool to tubes 34. The working
fluid 14 or other diluent may then flow through one or more diluent
passages 68 in the downstream surface 30 and into the combustion
chamber 24.
[0023] A plurality of turbulators of various shapes and sizes may
be arranged on or around the fuel and/or diluent conduits 60, 62 to
disrupt the laminar flow of the working fluid 14 or other diluent
across these surfaces. For example, as shown in FIG. 3, turbulators
70 may be radially arranged around the outside surface of the fuel
conduit 60 and/or the inside surface of the diluent conduit 62 to
reduce the laminar layer formed on these surfaces and thereby
enhance the heat transfer to the fuel flowing through the fuel
conduit 60.
[0024] The temperature of the fuel and working fluid 14 flowing
around and through the combustor 10 may vary considerably during
operations, causing the casing 12, fluid conduits 18, and/or tubes
34 to expand or contract at different rates and by different
amounts. As a result, a flexible coupling 72 may be included in one
or more fuel and/or diluent conduits 60, 62 between the end cover
16 and the end cap 20. The flexible coupling 72 may include one or
more expansion joints or bellows that accommodate axial
displacement by the casing 12, fluid conduits 18, and/or tubes 34
caused by thermal expansion or contraction. One of ordinary skill
in the art will readily appreciate that alternate locations and/or
combinations of flexible couplings 72 are within the scope of
various embodiments of the present invention, and the specific
location or number of flexible couplings 72 is not a limitation of
the present invention unless specifically recited in the
claims.
[0025] The various embodiments shown and described with respect to
FIGS. 1-3 may also provide a method for supplying fuel to the
combustor 10. The method may include, for example, flowing the
working fluid 14 through the tubes 34 that extend axially through
the end cap 20 and supplying fuel through the fuel conduit 60 into
the end cap 20. The method may further include supplying the
working fluid 14 or other diluent through the diluent conduit 62
that extends axially inside the fuel conduit 60 and swirling the
fuel flowing through the fuel conduit 60 around the working fluid
14 or other diluent flowing through the diluent conduit 62. In
particular embodiments, the method may further include disrupting
the fluid flow across the outside surface of the fuel conduit 60
and/or the inside surface of the diluent conduit 62 and/or
separating the fuel from the working fluid 14 or other diluent
inside the end cap 20.
[0026] The various embodiments shown and described with respect to
FIGS. 1-3 provide one or more commercial and/or technical
advantages over previous combustors. For example, the tortuous path
for the fuel flow through the fuel conduit 60 enables the working
fluid 14 or other diluent flowing inside the diluent conduit 62 or
outside of the fuel conduit 60 to evenly heat the fuel before the
fuel reaches the fuel plenum 50. The improved heating of the fuel
reduces thermal stresses in the tubes 34 and/or temperature and
density variations in the fuel flowing through the tubes 34 to
enhance flame stability, combustor performance, and/or undesirable
emissions.
[0027] This written description uses examples to disclose the
invention, including the best mode, and also to enable any person
skilled in the art to practice the invention, including making and
using any devices or systems and performing any incorporated
methods. The patentable scope of the invention is defined by the
claims, and may include other examples that occur to those skilled
in the art. Such other examples are intended to be within the scope
of the claims if they include structural elements that do not
differ from the literal language of the claims, or if they include
equivalent structural elements with insubstantial differences from
the literal languages of the claims.
* * * * *