U.S. patent application number 13/939727 was filed with the patent office on 2015-01-15 for gas turbine shroud cooling.
The applicant listed for this patent is General Electric Company. Invention is credited to Gregory Thomas Foster, Christopher Donald Porter, Michelle J. Rogers, Aaron Ezekiel Smith, David Wayne Weber.
Application Number | 20150013345 13/939727 |
Document ID | / |
Family ID | 52107479 |
Filed Date | 2015-01-15 |
United States Patent
Application |
20150013345 |
Kind Code |
A1 |
Porter; Christopher Donald ;
et al. |
January 15, 2015 |
GAS TURBINE SHROUD COOLING
Abstract
A shroud segment for a casing of gas turbine includes a body
configured for attachment to the casing proximate a localized
critical process location within the casing. The body has a leading
edge, a trailing edge, and two side edges. The critical process
location is located between the leading edge and the trailing edge
when the body is attached to the casing. A cooling passage is
defined in the body along one of the side edges with one of an
inlet or an outlet proximate the critical process location. The
cooling passage is configured large enough to cool the one side
edge adjacent the cooling passage to a desired level during
operation of the gas turbine. The critical process locations may be
related to temperatures, pressures or other measurable features of
the gas turbine environment when in use.
Inventors: |
Porter; Christopher Donald;
(Mauldin, SC) ; Foster; Gregory Thomas; (Greer,
SC) ; Smith; Aaron Ezekiel; (Simpsonville, SC)
; Weber; David Wayne; (Simpsonville, SC) ; Rogers;
Michelle J.; (Simpsonville, SC) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
General Electric Company |
Schenectady |
NY |
US |
|
|
Family ID: |
52107479 |
Appl. No.: |
13/939727 |
Filed: |
July 11, 2013 |
Current U.S.
Class: |
60/806 ;
415/116 |
Current CPC
Class: |
Y02T 50/60 20130101;
F01D 25/12 20130101; F01D 11/24 20130101; F05D 2240/11 20130101;
Y02T 50/676 20130101; F05D 2260/201 20130101; F05D 2260/202
20130101 |
Class at
Publication: |
60/806 ;
415/116 |
International
Class: |
F01D 25/12 20060101
F01D025/12 |
Claims
1. A shroud segment for a casing of gas turbine comprising: a body
configured for attachment to the casing proximate a localized
critical process location within the casing, the body having a
leading edge, a trailing edge, and two side edges, the body having
a first surface for facing the casing and a second surface opposite
the first surface for facing a hot gas path, the critical process
location being located between the leading edge and the trailing
edge when the body is attached to the casing; and at least two
cooling passages defined in the body related to one of the side
edges, a first of the cooling passages having an inlet and
extending to an outlet, one of the inlet or the outlet being
adjacent the critical process location, a second of the cooling
passages having an inlet and extending to an outlet, one of the
inlet or the outlet being adjacent the critical process location,
the first and second cooling passages being configured large enough
to cool the one side edge to a desired level during operation of
the gas turbine.
2. The shroud segment of claim 1, wherein the first cooling passage
has a first portion along the leading edge and a second portion
along the one side edge.
3. The shroud segment of claim 2, wherein the second cooling
passage has a first portion along the one side edge and a second
portion along the trailing edge.
4. The shroud segment of claim 1, further including at least two
additional cooling passages along the other of the side edges, the
two additional cooling passages being substantially symmetrical to
the at least two cooling passages with reference to a central plane
of the body extending between the leading edge and the trailing
edge.
5. The shroud segment of claim 1, wherein the first cooling passage
has a second outlet adjacent the critical process location along
the other side edge.
6. The shroud segment of claim 5, wherein the first cooling passage
includes a first portion along the leading edge and a second
portion along the one side edge, a third portion along the leading
edge, and a fourth portion along the other side edge.
7. The shroud segment of claim 1, wherein the second cooling
passage has a second inlet adjacent the critical process location
along the other side edge.
8. The shroud segment of claim 1, wherein the second cooling
passage includes a first portion along the one side edge and a
second portion along the trailing edge, a third portion along the
other side edge, and a fourth portion along the trailing edge.
9. The shroud segment of claim 1, wherein the second cooling
passage includes multiple outlets.
10. The shroud segment of claim 1, wherein the body and first and
second cooling passages are configured of a cast metal.
11. A gas turbine comprising: a compressor section; a combustion
section downstream from the compressor section; and a turbine
section downstream from the combustion section, wherein the turbine
section includes a casing defining a localized critical process
location and a plurality of shroud segments circumferentially
attached to the casing, each shroud segment including: a body
configured for attachment to the casing, at least one of the bodies
having a leading edge, a trailing edge, and two side edges, the
body having a first surface facing the casing and a second surface
opposite the first surface facing a hot gas path, the critical
process location being located between the leading edge and the
trailing edge when the body is attached to the casing; and at least
two cooling passages defined in the body related to one of the side
edges, a first of the cooling passages have an inlet and extending
to an outlet, one of the inlet or the outlet being adjacent the
critical process location, a second of the cooling passages having
an inlet and extending to an outlet, one of the inlet or the outlet
being adjacent the critical process location, the first and second
cooling passages being configured large enough to cool the one side
edge to a desired level during operation of the gas turbine.
12. The gas turbine of claim 11, wherein the first cooling passage
has a first portion along the leading edge and a second portion
along the one side edge.
13. The gas turbine of claim 12, wherein the second cooling passage
has a first portion along the one side edge and a second portion
along the trailing edge.
14. The gas turbine of claim 11, further including at least two
additional cooling passages along the other of the side edges, the
two additional cooling passages being substantially symmetrical to
the at least two cooling passages with reference to a central plane
of the body extending between the leading edge and the trailing
edge.
15. The gas turbine of claim 11, wherein the first cooling passage
has a second outlet adjacent the critical process location along
the other side edge.
16. The gas turbine of claim 15, wherein the first cooling passage
includes a first portion along the leading edge and a second
portion along the one side edge, a third portion along the leading
edge, and a fourth portion along the other side edge.
17. The gas turbine of claim 11, wherein the second cooling passage
has a second inlet adjacent the critical process location along the
other side edge.
18. The gas turbine of claim 11, wherein the second cooling passage
includes a first portion along the one side edge and a second
portion along the trailing edge, a third portion along the other
side edge, and a fourth portion along the trailing edge.
19. The gas turbine of claim 11, wherein the second cooling passage
includes multiple outlets.
20. The gas turbine of claim 11, wherein the body and first and
second cooling passages are configured of a cast metal.
Description
FIELD OF THE INVENTION
[0001] The present invention generally involves cooling a turbine
shroud element that may be located in a hot gas path of the
turbine.
BACKGROUND OF THE INVENTION
[0002] Turbines are widely used in a variety of aviation,
industrial, and power generation applications to perform work. Each
turbine generally includes alternating stages of peripherally
mounted stator vanes and rotating blades. The stator vanes may be
attached to a stationary component such as a casing that surrounds
the turbine, and the rotating blades may be attached to a rotor
located along an axial centerline of the turbine. A compressed
working fluid, such as steam, combustion gases, or air, flows along
a gas path through the turbine to produce work. The stator vanes
accelerate and direct the compressed working fluid onto the
subsequent stage of rotating blades to impart motion to the
rotating blades, thus turning the rotor and performing work. If any
compressed working fluid moves radially outside of the desired flow
path, the efficiency of the turbine may be reduces. As a result,
the casing surrounding the turbine often includes a radially inner
shell of shrouds, often formed in segments. The shrouds surround
and define the outer perimeter of the hot gas path and may be
located around both stator vanes and rotating blades.
[0003] The turbine shrouds are typically cooled in some fashion to
remove heat transferred by the hot gas path. U.S. Pat. No.
7,284,954 describes a turbine shroud segment that includes many
small cooling fluid passages machined throughout the turbine
shroud. A fluid such as compressed air from an upstream compressor
may be supplied through the fluid passages to cool the turbine
shroud. Other shroud segments utilize a single larger "core" flow
path cast in place rather than multiple small machined passages as
above. The core extends along an entire side of the shroud segment
from an axially upstream end to an axially downstream end.
[0004] While both types of shroud segment cooling passages work
well, continued improvements in systems to cool turbine shrouds
would be welcome, particularly systems that improve the amount of
cooling provided by a given flow and/or that allow selective
targeting of cooling at desired locations axially along the shroud
segments.
BRIEF DESCRIPTION OF THE INVENTION
[0005] 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.
[0006] According to certain aspects of the present disclosure, a
shroud segment for a casing of gas turbine may include a body
configured for attachment to the casing proximate a localized
critical process location within the casing. The body has a leading
edge, a trailing edge, and two side edges, as well as a first
surface for facing the casing and a second surface opposite the
first surface for facing a hot gas path. The critical process
location is located between the leading edge and the trailing edge
when the body is attached to the casing. At least two cooling
passages are defined in the body along one of the side edges. A
first of the cooling passages has an inlet and extends to an
outlet, one of the inlet or outlet being adjacent the critical
process location. A second of the cooling passages has an inlet and
extends to an outlet, one of the inlet or the outlet being adjacent
the critical process location. The first and second cooling
passages are configured large enough to cool the one side edge to a
desired level during operation of the gas turbine. Various options
and modifications are possible.
[0007] According to certain other aspects of the present
disclosure, a gas turbine may include a compressor section, a
combustion section downstream from the compressor section, and a
turbine section downstream from the combustion section. The turbine
section includes a casing defining a localized critical process
location and a plurality of shroud segments circumferentially
attached to the casing. Each shroud segment includes a body
configured for attachment to the casing. At least one of the bodies
has a leading edge, a trailing edge, and two side edges, as well as
a first surface facing the casing and a second surface opposite the
first surface facing a hot gas path. The critical process location
is located between the leading edge and the trailing edge when the
body is attached to the casing. At least two cooling passages are
defined in the body along one of the side edges. A first of the
cooling passages has an inlet and extends to an outlet, one of the
inlet or outlet being adjacent the critical process location. A
second of the cooling passages has an inlet and extends to an
outlet, one of the inlet or the outlet being adjacent the critical
process location. The first and second cooling passages are
configured large enough to cool the one side edge to a desired
level during operation of the gas turbine. As above, various
options and modifications are possible.
[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 schematic view of an exemplary gas turbine
incorporating aspects of the present disclosure;
[0011] FIG. 2 is a simplified cross-section view of a portion of
the gas turbine of FIG. 1 showing a shroud segment;
[0012] FIG. 3 is a top view of a shroud segment as in FIG. 2;
[0013] FIG. 4 is a side view of the shroud segment of FIG. 3;
[0014] FIG. 5 is a sectional view of the shroud segment taken along
line 5-5 in FIG. 3;
[0015] FIG. 6 is an isometric view of the shroud segment of FIG.
3;
[0016] FIG. 7 is a top view of a first alternate shroud
segment;
[0017] FIG. 8 is a top view of a second alternate shroud segment;
and
[0018] FIG. 9 is a top view of a third alternate shroud
segment.
DETAILED DESCRIPTION OF THE INVENTION
[0019] 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.
[0020] 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.
[0021] FIG. 1 is a schematic view of an exemplary gas turbine that
can incorporate a shroud element according to the present
disclosure. As illustrated, gas turbine 110 includes an inlet
section 111, a compressor section 112, a combustion section 114, a
turbine section 116, and an exhaust section 117. A shaft (rotor)
122 may be common to compressor section 112 and turbine section
116, and may further connect to a generator 105 for generating
electricity.
[0022] The compressor section 112 may include an axial flow
compressor in which a working fluid 100, such as ambient air,
enters the compressor from the inlet section 111 and passes through
alternating stages 113 of stationary vanes and rotating blades
(shown schematically in FIG. 1). Compressor casing 118 contains the
working fluid 100 as the stationary vanes and rotating blades
accelerate and redirect the working fluid to produce a continuous
flow of compressed working fluid. The majority of the compressed
working fluid flows downstream through the combustion section 114
and then the turbine section 116.
[0023] The combustion section 114 may include any type of combustor
known in the art. A combustor casing 115 may circumferentially
surround some or all of the combustion section 114 to direct the
compressed working fluid 100 from the compressor section 112 to a
combustion chamber 119. Fuel 101 is also supplied to the combustion
chamber 119. Possible fuels include, for example, one or more of
blast furnace gas, coke oven gas, natural gas, vaporized liquefied
natural gas (LNG), hydrogen, and propane. The compressed working
fluid 100 mixes with fuel 101 in the combustion chamber 119 where
it ignites to generate combustion gases having a high temperature
and pressure. The combustion gases then enter the turbine section
116.
[0024] As shown in FIGS. 1 and 2, within turbine section 116,
alternating stages of rotating blades (buckets) 124 and stationary
blades (nozzles) 126 are attached to rotor 122 and turbine casing
120, respectively. Working fluid 100, such as steam, combustion
gases, or air, flows along a hot gas path through gas turbine 110
from left to right as shown in FIG. 2. The first stage of
stationary nozzles 126 accelerates and directs the working fluid
100 onto the first stage of rotating blades 124, causing the first
stage of rotating blades 124 and rotor 122 to rotate. Working fluid
100 then flows across the second stage of stationary nozzles 126
which accelerates and redirects the working fluid to the next stage
of rotating blades (see FIG. 1), and the process repeats for each
subsequent stage.
[0025] As shown schematically in FIG. 1, the radially inward
portion of turbine casing 120 may include a series of shrouds 128.
Shrouds 128 in FIG. 1 are formed around blades 124. FIG. 2 shows
shrouds 128 formed around both blades 124 and nozzles 126. Shrouds
128 may be formed in segments, such as segment 130 of FIGS. 2-6. It
should be understood that, although an example of a shroud segment
related to a blade 124 is shown, the present disclosure
incorporates shroud segments formed around nozzles 124 as well.
Therefore, no limitation as to location of shrouds within casing
120 should be made.
[0026] As shown in FIG. 3, each shroud segment 130 may generally
comprise a body having a plurality of sides. Specifically, each
segment 130 has a leading edge 132, a trailing edge 134, and two
side edges 136 and 138. A first surface 140 faces (radially
outwardly) toward casing 120 and a second surface 142 opposite the
first surface faces (radially inwardly) toward the hot gas path
where the working fluid 100 flows.
[0027] A critical process location (defined below) 144 is located
between leading edge 132 and the trailing edge 134, generally in
alignment with rotating blades 124. The critical process location
144 could be, for example, a maximum or other critical temperature
location along the segment during gas turbine use, a maximum or
other critical pressure location along the segment during gas
turbine use, a maximum or other critical gas side heat transfer
coefficient location, or a maximum or other critical stress
location. The critical process location 144 could be a location
where cooling gases can enter or exit the segment after travelling
through a passageway allowing for sufficient cooling of the
segment, while still respecting back flow margin limitations.
[0028] Also, the critical process location need not be an absolute
maximum, it could be any desired value that can be used to
determine optimal flow and heat transfer characteristics within the
gas turbine or within the segment itself. Much depends on the
desired characteristics of the gas turbine, flow at the location of
segment 130, etc. The critical process location along segment 130
could vary at different stages within a gas turbine. Further, two
or more of such critical process locations could exist along a
single segment 130.
[0029] At least two cooling passages 146,148 are defined in segment
130 along one of side edges 136. First cooling passage 146 has an
inlet 150 that may be (as shown) on first surface 140 near leading
edge 132. First cooling passage 146 also has an outlet 152 adjacent
critical process location 144. Second cooling passage 148 has an
inlet 154 that may be (as shown) on first surface 140 adjacent
critical process location 144. Second cooling passage 148 has at
least one outlet 156 that may be (as shown) near trailing edge
134.
[0030] It should be understood that flow through either or both of
passages 146,148 could be reverse of that which is shown. For
example, flow in first passage 146 could be counter (directed
upstream) to that through second passage 148. In other words, flow
could run from opening 152 to opening 150 (reversing inlet/outlet
functions), if desired. Flow through second passage 148 could also
be similarly reversed.
[0031] First and second cooling passages 146,148 may be formed by
casting rather than machining. For example, as is known a mold may
be used in which a fill substance is provided matching the path of
first and second cooling passages 146,148, the fill substance being
burned off and/or chemically removed afterward leaving the
passages. Such manufacture using casting of at least some portion
of the passages may be more cost effective than machining the
passages or multiple smaller passages. Even if the passages are
formed substantially by casting, inlets and outlets to the passages
or other features may be machined as part of the manufacture.
[0032] First and second cooling passages 146,148 may be configured
large enough to cool side edge 136 and/or a related area to a
desired level during operation of the gas turbine. The passage
sizes are configured to allow sufficient flow that back flow
margins are respected, and heat transfer is sufficient to cool
segment 130 to a desired temperature. If desired, in one example of
a gas turbine, a segment 130 with a length of about 6.5 inch, a
width of about 3.0 inch, and general thickness of about 0.25 inch,
passages 146, 148 may be of a cross-section of about 0.025 square
inch. Accordingly, numerous small passages spread along the
locations of cooling passages 146,148 are not required to cool
segment 130.
[0033] As shown, an additional set of cooling passages 158,160 can
be provided on other side edge 138. Passages 158,160 may if desired
but not necessarily be substantially symmetrical to passages
146,148 along a central axis running between leading edge 132 and
trailing edge 134. As above first cooling passage 158 has an inlet
162 which may be (as shown) on first surface 140 near leading edge
132. First cooling passage 158 also has an outlet 164 adjacent
critical process location 144. Second cooling passage 160 has an
inlet 166 which may be (as shown) on first surface 140 adjacent
critical process location 144. Second cooling passage 160 has at
least one outlet 168 which may be (as shown) near trailing edge
134. As shown, inlet 150 and inlet 162 are a common, single inlet.
However, as discussed below, the inlets 150,162 may be
separate.
[0034] Various options and modifications are possible. For example,
as shown in FIG. 3, both second passages 148,160 may have multiple
outlets 156,168, which may be along trailing edge 134. Such
multiple exits may be machined or cast, and may be employed to cool
trailing edge 134 if spaced sufficiently from second passages
148,160 to require additional cooling. Some or all of such multiple
outlets could instead or also exit segment 130 at locations other
than trailing edge 134 if desired.
[0035] Alternatively, as shown in FIG. 7, modified segment 130' has
first passages 146',158' each with their own individual inlets
150,162 with first portions 170,172 and second portions 174,176
leading to outlets 152,164. As shown in FIG. 3, first portions
170,172 are in communication with each other; as shown. If desired,
some or all of the inlets in segment 130 or 130' could also be
located elsewhere other than first surface 140.
[0036] As another alternative, as shown in FIG. 8, modified segment
130'' has second passages 148',160' each with individual inlets
154,166 leading to first portions 178,180 and second portions
182,184 and then outlet(s) 156,168, as above. However, second
portions 182,184 in FIG. 8 are in communication with each other.
Therefore, instead of the construction shown in FIG. 3, having one
first passage upstream of location 144 and two second passages
downstream of location 144, a shroud segment could be made as shown
in FIG. 8 with one upstream passage and one downstream passage
split along the side edges 136,138 at location 144.
[0037] Alternatively, as shown in FIG. 9, splits could be provided
at two or more critical process locations along the shroud segment.
Along one side of segment 130''', a first passageway 146 extends
from inlet 150 to outlet 152, a second passageway 148' extends from
inlet 154 to outlet 153 and a third passageway 179 extends from
inlet 155 to outlets 156. Similarly, along the other side, a first
passageway 158 extends from inlet 162 to outlet 164, a second
passageway 160' extends from inlet 166 to outlet 165 and a third
passageway 181 extends from inlet 167 to outlets 168. Accordingly,
FIG. 9 illustrates that more than one split can be made between
leading edge 132 and trailing edge 134 at critical process
locations, as desired. It should also be understood that splits
need not be symmetrical or even along a given side of the segments
or between sides of the segments.
[0038] The segments above can be mounted to turbine casings in
various known ways, via hooks, impingement plates, clips, etc. The
present invention is not limited to any such mounting arrangement,
cooling mode, or any particular fluid used to cool the shroud
segment. For example, such mounting may or may not provide that the
cooling fluid first impacts the segments to provide impingement
cooling to the bulk of the segment before some fluid flows through
the disclosed passageways. Also, the segments may include mounting
structures, cooling passage openings, etc., for receiving,
contacting or cooling nozzles 126 if the segments are located along
a row of nozzles as opposed to a row of blades 124.
[0039] It is anticipated that the various embodiments of the shroud
segments shown above may be manufactured at lower costs than
previous designs. Specifically, the segments may be cast or forged,
with reduced machining required for inlets and outlets and the
larger passages being formed by casting. In this manner, the shroud
may be readily manufactured to include the desired fluid passages
that provide cooling to the sides of the segments. By splitting the
passages at critical process location(s) 144 where maximum
temperature, pressure or other measurable parameters (maximums or
not), cooling can be beneficially located at a desired point while
providing a more efficient flow, with less leakage. The segments
can thus be tuned in various ways to improve thermal and flow
performance.
[0040] 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.
* * * * *