U.S. patent application number 13/485295 was filed with the patent office on 2013-12-05 for methods and apparatus for cooling rotary components within a steam turbine.
The applicant listed for this patent is Mark Kevin Bowen, Michael Earl Montgomery, Stephen Roger Swan. Invention is credited to Mark Kevin Bowen, Michael Earl Montgomery, Stephen Roger Swan.
Application Number | 20130323009 13/485295 |
Document ID | / |
Family ID | 49670459 |
Filed Date | 2013-12-05 |
United States Patent
Application |
20130323009 |
Kind Code |
A1 |
Bowen; Mark Kevin ; et
al. |
December 5, 2013 |
METHODS AND APPARATUS FOR COOLING ROTARY COMPONENTS WITHIN A STEAM
TURBINE
Abstract
A stationary component includes an outer ring including a first
plenum, a first passageway, and a second plenum defined therein.
The first passageway extends between the first plenum and the
second plenum. An airfoil is disposed radially inward of the outer
ring. The airfoil includes a second passageway defined therein. The
second passageway is coupled in flow communication with the second
plenum.
Inventors: |
Bowen; Mark Kevin;
(Niskayuna, NY) ; Swan; Stephen Roger; (Clifton
Park, NY) ; Montgomery; Michael Earl; (Niskayuna,
NY) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Bowen; Mark Kevin
Swan; Stephen Roger
Montgomery; Michael Earl |
Niskayuna
Clifton Park
Niskayuna |
NY
NY
NY |
US
US
US |
|
|
Family ID: |
49670459 |
Appl. No.: |
13/485295 |
Filed: |
May 31, 2012 |
Current U.S.
Class: |
415/1 ;
415/177 |
Current CPC
Class: |
F01K 13/006
20130101 |
Class at
Publication: |
415/1 ;
415/177 |
International
Class: |
F04D 29/58 20060101
F04D029/58 |
Claims
1. A method for cooling a rotating component within a turbine, said
method comprising: channeling a cooling fluid through an outer ring
including a first plenum, a first passageway, and a second plenum
defined therein, wherein the first passageway extends between the
first plenum and the second plenum; channeling the cooling fluid
through an airfoil disposed radially inward of the outer ring, the
airfoil including a second passageway defined therein, the second
passageway coupled in flow communication with the second plenum;
and discharging the cooling fluid from the airfoil to facilitate
cooling an adjacent rotating component.
2. A method in accordance with claim 1 wherein channeling a cooling
fluid through the outer ring further comprises channeling the
cooling fluid substantially radially through the outer ring between
the first plenum and the second plenum.
3. A method in accordance with claim 1 wherein channeling a cooling
fluid through the outer ring further comprises channeling the
cooling fluid through a plurality of first passageways extending
substantially radially between the first plenum and the second
plenum, the first passageway included in the plurality for first
passageways.
4. A method in accordance with claim 1 wherein channeling the
cooling fluid through the airfoil further comprises channeling the
cooling fluid substantially radially through the airfoil.
5. A method in accordance with claim 1 wherein channeling the
cooling fluid through the airfoil further comprises channeling the
cooling fluid through a plurality of second passageways extending
substantially radially and coupled in flow communication with the
second plenum, the second passageway included in the plurality of
second passageways.
6. A method in accordance with claim 1 wherein discharging the
cooling fluid further comprises discharging the cooling fluid
through an outlet of the second passageway and into a
wheelspace.
7. A method in accordance with claim 1 further comprising sealing
the first plenum from a main steam path.
8. A stationary component for use with a turbine, said stationary
component comprising: an outer ring comprising a first plenum, a
first passageway, and a second plenum defined therein, said first
passageway extending between said first plenum and said second
plenum; and an airfoil disposed radially inward of said outer ring,
said airfoil comprising a second passageway defined therein, said
second passageway coupled in flow communication with said second
plenum.
9. A stationary component in accordance with claim 8 wherein said
first plenum is defined in a radially outer surface of said outer
ring, and said second plenum is defined in a radially inner surface
of said outer ring.
10. A stationary component in accordance with claim 8 wherein said
first passageway extends substantially radially through said outer
ring.
11. A stationary component in accordance with claim 8 wherein said
outer ring comprises a plurality of first passageways extending
substantially radially between said first plenum and said second
plenum, said first passageway included in said plurality for first
passageways.
12. A stationary component in accordance with claim 8 wherein said
second passageway extends substantially radially through said
airfoil.
13. A stationary component in accordance with claim 8 wherein said
airfoil comprises a plurality of second passageways extending
substantially radially and coupled in flow communication with said
second plenum, said second passageway included in said plurality of
second passageways.
14. A stationary component in accordance with claim 8 wherein said
second passageway has an outlet oriented to discharge a cooling
fluid into a wheelspace.
15. A steam turbine comprising: a rotor shaft comprising a
plurality of buckets coupled thereto; a steam turbine casing; and a
stationary component coupled to said steam turbine casing, said
stationary component disposed upstream from said plurality of
buckets such that a wheelspace is defined between said plurality of
buckets and said stationary component, said stationary component
comprising an outer ring and an airfoil disposed radially inward of
said outer ring, such that a cooling fluid flowpath is defined
through at least said outer ring and said airfoil, said cooling
fluid flowpath configured to channel a cooling fluid towards said
wheelspace.
16. A steam turbine in accordance with claim 15 wherein said outer
ring comprises a first plenum, a first passageway, and a second
plenum defined therein, said first passageway extending between
said first plenum and said second plenum, said first plenum, said
first passageway, and said second plenum included in said cooling
fluid flowpath.
17. A steam turbine in accordance with claim 16 wherein said outer
ring comprises a seal coupled between said first plenum and a main
steam flowpath, wherein said main steam flowpath is defined through
said plurality of buckets and said stationary component.
18. A steam turbine in accordance with claim 16 wherein said first
plenum is defined in a radially outer surface of said outer ring,
and said second plenum is defined in a radially inner surface of
said outer ring.
19. A steam turbine in accordance with claim 15 wherein said
airfoil comprises a second passageway defined therein, said second
passageway coupled in flow communication with said second plenum,
said second passageway included in said cooling fluid flowpath.
20. A steam turbine in accordance with claim 19 wherein said second
passageway has an outlet oriented to discharge the cooling fluid
into said wheelspace.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application claims the benefit of U.S. application Ser.
No. 12/031,049, filed Feb. 14, 2008, which is incorporated herein
by reference in its entirety.
BACKGROUND OF THE INVENTION
[0002] This invention relates generally to cooling a rotary
component, and more specifically, to cooling a wheelspace in a
stage of a steam turbine.
[0003] At least some known stationary and rotating components found
in steam turbine engines are subjected to temperature, pressure,
and centrifugal loadings during normal operations. The design of
the high-pressure (HP) and/or intermediate-pressure (IP) sections
of known steam turbine engines may be complex because of the high
temperatures and pressures of the steam supplied to the steam
turbine and because of the creep experienced by such components.
Known temperatures and pressures that satisfy the aerodynamic and
thermodynamic design requirements for at least some known turbines
require a corresponding acceptable mechanical design solution.
Known design solutions focus on bucket and rotor materials and/or
geometries, steam turbine operating temperatures and/or pressures,
and/or piping solutions external to the steam flowpath.
[0004] To achieve an acceptable mechanical design for some known
steam turbine components, some known designs require that such
components be exposed to steam temperatures that are at lower
temperatures than similar components would typically be exposed to
during normal operations of known turbine sections. However,
limiting operating temperatures and pressures within the turbine
limits the thermodynamic design space and may result in decreased
turbine performance.
[0005] One known design solution involves changing the rotor
geometry and materials to make a rotor that is acceptable for
long-term operations, without providing external cooling. However,
such geometries are generally more costly, reduce stage efficiency,
and/or require costly, higher capability materials than designs
that use an adequate cooling scheme. One known cooling scheme uses
pipes routed through a steam flowpath to supply a cooling steam
flow. For example, such pipes may be positioned within
first-reheat, double-flow tub stages. Such pipes however create an
obstruction within the main steam flow and add complexity to the
system.
BRIEF DESCRIPTION OF THE INVENTION
[0006] In one aspect, a method is provided for cooling a rotating
component within a turbine. The method includes channeling a
cooling fluid through an outer ring including a first plenum, a
first passageway, and a second plenum defined therein. The first
passageway extends between the first plenum and the second plenum.
The cooling fluid is channeled through an airfoil disposed radially
inward of the outer ring. The airfoil includes a second passageway
defined therein. The second passageway is coupled in flow
communication with the second plenum. The cooling fluid is
discharged from the airfoil to facilitate cooling an adjacent
rotating component.
[0007] In another aspect, a stationary component is provided for
use with a turbine. The stationary component includes an outer ring
including a first plenum, a first passageway, and a second plenum
defined therein. The first passageway extends between the first
plenum and the second plenum. An airfoil is disposed radially
inward of the outer ring. The airfoil includes a second passageway
defined therein. The second passageway is coupled in flow
communication with the second plenum.
[0008] In still another aspect, a steam turbine is provided. The
steam engine includes a rotor shaft including a plurality of
buckets coupled thereto, a steam turbine casing, and a stationary
component coupled to the steam turbine casing. The stationary
component is disposed upstream from the plurality of buckets such
that a wheelspace is defined between the plurality of buckets and
the stationary component. The stationary component includes an
outer ring and an airfoil disposed radially inward of the outer
ring, such that a cooling fluid flowpath is defined through at
least the outer ring and the airfoil. The cooling fluid flowpath is
configured to channel a cooling fluid towards the wheelspace.
BRIEF DESCRIPTION OF THE DRAWINGS
[0009] FIG. 1 is a schematic view of an exemplary steam turbine
engine.
[0010] FIG. 2 is a cross-sectional view of an exemplary first
turbine stage that may be used with the steam turbine shown in FIG.
1.
[0011] FIG. 3 is a perspective view of an exemplary stationary
component that may be used with the turbine stage shown in FIG.
2.
[0012] FIG. 4 is a cross-sectional view of another exemplary first
turbine stage that may be used with the steam turbine shown in FIG.
1.
[0013] FIG. 5 is a perspective view of an exemplary stationary
component that may be used with the turbine stage shown in FIG.
4.
DETAILED DESCRIPTION OF THE INVENTION
[0014] FIG. 1 is a schematic illustration of an exemplary
opposed-flow steam turbine engine 100 including a high-pressure
(HP) section 102 and an intermediate-pressure (IP) section 104. An
HP shell, or casing, 106 is divided axially into upper and lower
half sections 108 and 110, respectively. Similarly, an IP shell 112
is divided axially into upper and lower half sections 114 and 116,
respectively. In the exemplary embodiment, shells 106 and 112 are
inner casings. Alternatively, shells 106 and 112 are outer casings.
In the exemplary embodiment, shells 106 and 112 are sealed such
that ambient air is not admitted into engine 100. A central section
118 positioned between HP section 102 and IP section 104 includes a
high-pressure steam inlet 120 and an intermediate-pressure steam
inlet 122.
[0015] An annular section divider 134 extends radially inwardly
from central section 118 towards a rotor shaft 140 that extends
between HP section 102 and IP section 104. More specifically,
divider 134 extends circumferentially around a portion of rotor
shaft 140 between a first HP section inlet nozzle 136 and a first
IP section inlet nozzle 138. Divider 134 is received in a channel
142.
[0016] During operation, high-pressure steam inlet 120 receives
high-pressure/high-temperature steam 144 from a steam source, for
example, a power boiler (not shown). Steam 144 is routed through HP
section 102 from inlet nozzle 136 wherein work is extracted from
the steam 144 to rotate rotor shaft 140 via a plurality of turbine
blades, or buckets 202 (shown in FIGS. 2 and 3) that are coupled to
shaft 140. Each set of buckets 202 includes a corresponding
diaphragm 204 (shown in FIGS. 2 and 3) that facilitates routing of
steam 144 to associated buckets 202. The steam 144 exits HP section
102 and is returned to the boiler wherein it is reheated. Reheated
steam 146 is then routed to intermediate-pressure steam inlet 122
and returned to IP section 104 via inlet nozzle 138 at a reduced
pressure than steam 144 entering HP section 102, but at a
temperature that is approximately equal to the temperature of steam
144 entering HP section 102. Work is extracted from the steam 146
in IP section 104 in a manner substantially similar to that used
for HP section 102 via a system of rotating and stationary
components. Accordingly, an operating pressure within HP section
102 is higher than an operating pressure within IP section 104,
such that steam 144 within HP section 102 tends to flow towards IP
section 104 through leakage paths that may develop between HP
section 102 and IP section 104.
[0017] In the exemplary embodiment, steam turbine engine 100 is an
opposed-flow high-pressure and intermediate-pressure steam turbine
combination. Alternatively, steam turbine engine 100 may be used
with any individual turbine including, but not being limited to
low-pressure turbines. In addition, the present invention is not
limited to being used with opposed-flow steam turbines, but rather
may be used with steam turbine configurations that include, but are
not limited to, single-flow and double-flow turbine steam
turbines.
[0018] FIG. 2 is a cross-sectional view of an exemplary first
turbine stage 200 that may be used with steam turbine engine 100.
FIG. 3 is a perspective view of a diaphragm 204 that may be used
with turbine stage 200. In the exemplary embodiment, diaphragm 204
is fabricated from alloy steels, such as, for example, 12% Chromium
(Cr), or better, forgings, or bar stock. Furthermore, in the
exemplary embodiment, the external geometry of diaphragm 204 is any
known external geometry for a stationary component within a steam
turbine.
[0019] In the exemplary embodiment, turbine stage 200 includes
first high-pressure section inlet nozzle 136. Although turbine
stage 200 is described herein as a first turbine stage for use in a
high-pressure steam turbine, the embodiments described herein are
not limited to only being used with a first stage, but rather may
be used with any turbine stage and/or any steam turbine having a
cooling fluid flow applied thereto. In the exemplary embodiment,
stage 200 includes a rotor wheel 206 and diaphragm 204. Rotor wheel
206 includes a row 208 of buckets 202, and diaphragm 204 includes a
row 210 of airfoils 212. A main flowpath 214 is defined through
high-pressure section 102 (shown in FIG. 1) such that steam 144
(shown in FIG. 1) flows through airfoils 212 and buckets 202 during
turbine operation. More specifically, each airfoil 212 directs
steam 144 downstream through axially-adjacent buckets 202. Further,
a wheelspace 216 is defined between an upstream surface 218 of
wheel 206 and a downstream surface 220 of diaphragm 204. In the
exemplary embodiment, wheel 206 is coupled to rotor shaft 140
(shown in FIG. 1), and each bucket 202 rotates wheel 206 and rotor
shaft 140 when steam 144 contacts bucket 202. In the exemplary
embodiment, each bucket 202 includes a seal 222 that is coupled to
a bucket tip 224.
[0020] In the exemplary embodiment, diaphragm 204 includes a
stationary inner ring 226 and a stationary outer ring 228. An inner
end 232 of airfoil 212 is coupled to inner ring 226 and an outer
end 230 of airfoil 212 is coupled to outer ring 228. In the
exemplary embodiment, inner ring 226 includes a rotor seal 234 that
is positioned adjacent to rotor shaft 140 to facilitate preventing
steam 144 and/or cooling fluid 236 from flowing between inner ring
226 and rotor shaft 140. In the exemplary embodiment, cooling fluid
236 is a cooling steam. Alternatively, cooling fluid 236 is any
suitable fluid for cooling stage 200 and that enables steam turbine
engine 100 to function as described herein.
[0021] Furthermore, in the exemplary embodiment, inner ring 226
also includes a wheel seal 238 that is positioned adjacent to an
upstream wheel projection 240 to facilitate preventing steam 144
from flowing from main flowpath 214 into wheelspace 216. Inner ring
226 also includes a cooling fluid inner plenum 242 and a plurality
of cooling fluid outlets 244. In the exemplary embodiment, inner
plenum 242 is an annular slot 246 defined within an outer surface
248 of inner ring 226. Moreover, in the exemplary embodiment, inner
plenum 242 and each outlet 244 is formed integrally within inner
ring 226. In one embodiment, inner ring 226 is a single piece. In
an alternative embodiment, inner ring 226 is formed from a
plurality of segments (not shown). Further, in the exemplary
embodiment, each cooling fluid outlet 244 extends from inner plenum
242 through diaphragm downstream surface 220. In the exemplary
embodiment, a centerline 250 of outlet 244 is oriented
substantially perpendicularly to a turbine radius R (shown in FIG.
1). In another embodiment, outlet centerline 250 is oriented
obliquely with respect to turbine radius R.
[0022] In the exemplary embodiment, outer ring 228 includes a steam
seal 252 that is positioned adjacent to high-pressure steam inlet
120 (shown in FIG. 1) to facilitate preventing steam 144 from
flowing between outer ring 228 and shell 106 (shown in FIG. 1).
Steam seal 252 may be either internal to diaphragm 204 or at an
interface 254 defined between diaphragm 204 and shell 106. In the
exemplary embodiment, outer ring 228 also includes a wheel seal 256
that is positioned on a downstream surface 258 and a bucket seal
260 coupled to an inner surface. Seals 256 and 260 facilitate
preventing steam 144 from flowing from main flowpath 214 into shell
106. More specifically, in the exemplary embodiment, bucket seal
260 is configured to engage with bucket tip seal 222.
[0023] Outer ring 228 also includes a cooling fluid outer plenum
262 and a plurality of cooling fluid passages 264. In the exemplary
embodiment, outer plenum 262 is an annular slot 266 that is defined
within an outer surface 268 of outer ring 228. Furthermore, in the
exemplary embodiment, outer plenum 262 is only defined in a first
portion 270 of outer ring 228. A channel 272 is defined within a
second portion 274 of outer ring 228, wherein second portion 274 is
the portion of outer ring 228 not included in first portion
270.
[0024] In the exemplary embodiment, outer plenum 262 and each
passage 264 is formed integrally with outer ring 228. In one
embodiment, outer ring 228 is a single piece. In an alternative
embodiment, outer ring 228 includes a plurality of segments (not
shown). Further, in the exemplary embodiment, each cooling fluid
passage 264 extends from outer plenum 262 through outer ring 228
and outer ring inner surface 276. In the exemplary embodiment, a
centerline 278 of passage 264 is oriented substantially parallel to
turbine radius R. In another embodiment, passage centerline 278 is
oriented obliquely with respect to turbine radius R. Furthermore,
in the exemplary embodiment, each passage 264 has the same diameter
D.sub.O. Alternatively, each passage 264 may have any shape, size,
and/or orientation that enables engine 100 to function as described
herein.
[0025] Each airfoil 212, in the exemplary embodiment, includes an
airfoil passageway 280. A centerline 282 of each airfoil passageway
280 is oriented substantially parallel to turbine radius R.
Alternatively, passageway centerline 282 is oriented obliquely with
respect to turbine radius R. In the exemplary embodiment,
passageway 280 is defined through a widest portion 284 of each
airfoil 212 such that the external geometry of airfoil 212 is not
altered by passageway 280. Alternatively, passageway 280 may be
defined within airfoil 212 at any suitable location that enables
engine 100 to function as described herein and/or that ensures an
external geometry of airfoil 212 is not dependent upon passageway
280.
[0026] Furthermore, in the exemplary embodiment, each passageway
280 has the same diameter D.sub.A. Alternatively, each passageway
280 may have any shape, size, and/or orientation that enables
engine 100 to function as described herein.
[0027] Diameter D.sub.A is smaller than diameter D.sub.O in the
exemplary embodiment. In other embodiments, diameter D.sub.A may be
larger than, or approximately equal to, diameter D.sub.O. Moreover,
in the exemplary embodiment, an inlet 286 of airfoil passageway 280
is substantially aligned with an outlet 288 of outer ring passage
264, and an outlet 290 of airfoil passageway 280 is in flow
communication with inner plenum 242. More specifically, in the
exemplary embodiment, airfoil passageway centerline 282 is
substantially coaxial with outer ring passage centerline 278.
Alternatively, centerline 282 may be offset and/or oriented
obliquely with respect to centerline 278.
[0028] In the exemplary embodiment, the number of outer ring
outlets 288 is equal to the number of airfoils 212 coupled within
outer ring first portion 270. Similarly, the number of outlets 244
is equal to the number of airfoils 212 coupled within outer ring
first portion 270. In an alternative embodiment, the number of
outer ring outlets 288 is greater than, or less than, the number of
airfoils 212 coupled within outer ring first portion 270, and/or
the number of outlets 244 is greater than, or less than, the number
of airfoils 212 coupled within outer ring first portion 270. In
another embodiment, the number of outer ring outlets 288 is equal
to the number of airfoils 212 coupled within outer ring first
portion 270, and/or the number of outlets 244 is equal to the
number of airfoils 212 coupled within diaphragm 204. In yet another
embodiment, the number of outer ring outlets 288 and/or the number
of outlets 244 is not dependent upon the number of airfoils 212.
Alternatively, the number and/or sizing of plenum 242 and/or 262,
passageway 280, passage 264, outlet 244 and/or airfoils 212 that
include passageway 280 therethrough may be selected to control an
amount of cooling fluid 236 supplied to stage 200 and/or a velocity
of fluid 236 in passageways 280, passages 264, and/or outlets
244.
[0029] During operation of engine 100, steam 144 is channeled to
high-pressure section 102 through high-pressure steam inlet 120 and
along main flowpath 214, and cooling fluid 236, such as cooling
steam, is channeled to stage 200 via one or more pipes or
passageways (not shown) that penetrate shell 106 near outer ring
228. Steam seal 252 facilitates preventing steam 144 from entering
outer plenum 262 and/or fluid 236 from discharging from outer
plenum 262 into main flowpath 214. Steam 144 is channeled between
airfoils 212 to buckets 202 to rotate rotor shaft 140. Seals 222,
260, and/or 238 facilitate ensuring that steam 144 travels along
main flowpath 214 and also facilitate preventing leaks within
high-pressure section 102.
[0030] Cooling fluid 236 may be channeled from any suitable cooling
fluid source, such as, for example, a cooling steam source outside
of shell 106 and/or 112, a downstream stage (not shown), and/or a
leakage flow within engine 100. In the exemplary embodiment,
cooling fluid 236 enters outer plenum 262 and/or channel 272 and is
discharged from outer ring 228 through passages 264. Cooling fluid
236 discharged from passages 264 enters airfoil passageways 280,
and is then channeled through airfoil passageways 280 prior to
being discharged from outlets 290. Cooling fluid 236 enters inner
plenum 242 from passageways 280. Cooling fluid 236 is then
channeled though outlets 244 into wheelspace 216 to facilitate
cooling wheel 206 and/or wheelspace 216. In the exemplary
embodiment, cooling fluid 236 is discharged from wheelspace 216
along any suitable leakage flow path that enables cooling fluid 236
to enter main flowpath 214, through rotor seal 234, seal 238,
and/or balance holes (not shown), and/or along any other suitable
path that enables engine 100 to function as described herein.
[0031] FIG. 4 is a cross-sectional view of another exemplary first
turbine stage 400 that may be used with steam turbine engine 100.
FIG. 5 is a perspective view of a diaphragm 404 that may be used
with turbine stage 400. In the exemplary embodiment, diaphragm 404
is fabricated from alloy steels, such as, for example, 12% Chromium
(Cr), or better, forgings, or bar stock. Furthermore, in the
exemplary embodiment, the external geometry of diaphragm 404 is any
known external geometry for a stationary component within a steam
turbine.
[0032] In the exemplary embodiment, turbine stage 400 includes
first high-pressure section inlet nozzle 136. Although turbine
stage 400 is described herein as a first turbine stage for use in a
high-pressure steam turbine, the embodiments described herein are
not limited to only being used with a first stage, but rather may
be used with any turbine stage and/or any steam turbine having a
cooling fluid flow applied thereto. In the exemplary embodiment,
stage 400 includes a rotor wheel 406 and diaphragm 404. Rotor wheel
406 includes a row 408 of buckets 402, and diaphragm 404 includes a
row 410 of airfoils 412. A main flowpath 414 is defined through
high-pressure section 102 (shown in FIG. 1) such that steam 144
flows through airfoils 412 and buckets 402 during turbine
operation. More specifically, each airfoil 412 directs steam 144
downstream through axially-adjacent buckets 402. Further, a
wheelspace 416 is defined by an upstream surface 418 of wheel 406.
In the exemplary embodiment, wheel 406 is coupled to rotor shaft
140, and each bucket 402 rotates wheel 406 and rotor shaft 140 when
steam 144 contacts bucket 402. In the exemplary embodiment, each
bucket 402 includes a seal 422 that is coupled to a bucket tip
424.
[0033] In the exemplary embodiment, diaphragm 404 includes a
stationary inner ring 426 and a stationary outer ring 428. An inner
end 432 of airfoil 412 is coupled to inner ring 426 and an outer
end 430 of airfoil 412 is coupled to outer ring 428. In at least
some embodiments, inner ring 426 may be integrally formed with
airfoils 412. In the exemplary embodiment, inner ring 426 includes
a wheel seal 438 that is positioned adjacent to an upstream wheel
projection 440 to facilitate preventing steam 144 from flowing from
main flowpath 414 into wheelspace 416. In one embodiment, inner
ring 426 is a single piece. In an alternative embodiment, inner
ring 426 is formed from a plurality of segments (not shown).
[0034] In the exemplary embodiment, outer ring 428 includes a wheel
seal 456 that is positioned on a downstream surface 458 and a
bucket seal 460 coupled to an inner surface. Seals 456 and 460
facilitate preventing steam 144 from flowing from main flowpath 414
into shell 106. More specifically, in the exemplary embodiment,
bucket seal 460 is configured to engage with bucket tip seal
422.
[0035] Outer ring 428 also includes a cooling fluid outer plenum
462, a cooling fluid inner plenum 463, and a plurality of cooling
fluid passages 464 extending therebetween. In the exemplary
embodiment, outer plenum 462 is an annular slot that is defined
within an outer surface 468 of outer ring 428. In the exemplary
embodiment, inner plenum 463 is an annular slot that is defined
within an inner surface 476 of outer ring 428.
[0036] In the exemplary embodiment, outer plenum 462, inner plenum
463, and each passage 464 is formed integrally with outer ring 428.
In one embodiment, outer ring 428 is a single piece. In an
alternative embodiment, outer ring 428 includes a plurality of
segments (not shown). Further, in the exemplary embodiment, each
cooling fluid passage 464 extends substantially radially through
outer ring 428 between outer plenum 462 and inner plenum 463. In
the exemplary embodiment, a centerline 478 of passage 464 is
oriented substantially parallel to turbine radius R. In another
embodiment, passage centerline 478 is oriented obliquely with
respect to turbine radius R. Furthermore, in the exemplary
embodiment, each passage 464 has the same diameter D.sub.O.
Alternatively, each passage 464 may have any shape, size, and/or
orientation that enables engine 100 to function as described
herein.
[0037] Each airfoil 412, in the exemplary embodiment, includes an
airfoil passageway 480. A centerline 482 of each airfoil passageway
480 is oriented substantially parallel to turbine radius R.
Alternatively, passageway centerline 482 is oriented obliquely with
respect to turbine radius R. Moreover, in the exemplary embodiment,
airfoil passageway centerline 482 may be offset and/or oriented
obliquely with respect to outer ring passage centerline 478.
Alternatively, airfoil passageway centerline 482 is substantially
coaxial with outer ring passage centerline 478. In the exemplary
embodiment, passageway 480 is defined through a widest portion of
each airfoil 412 such that the external geometry of airfoil 412 is
not altered by passageway 480. Alternatively, passageway 480 may be
defined within airfoil 412 at any suitable location that enables
engine 100 to function as described herein and/or that ensures an
external geometry of airfoil 412 is not dependent upon passageway
480.
[0038] Furthermore, in the exemplary embodiment, each passageway
480 has the same diameter D.sub.A. Alternatively, each passageway
480 may have any shape, size, and/or orientation that enables
engine 100 to function as described herein. Diameter D.sub.A is
smaller than diameter D.sub.O in the exemplary embodiment. In other
embodiments, diameter D.sub.A may be larger than, or approximately
equal to, diameter D.sub.O. In the exemplary embodiment, the number
of outer ring passages 464 is equal to the number of passageways
480. In an alternative embodiment, the number of outer ring
passages 464 is greater than, or less than, the number of
passageways 480.
[0039] During operation of engine 100, steam 144 is channeled to
high-pressure section 102 through high-pressure steam inlet 120 and
along main flowpath 414, and a cooling fluid 436, such as cooling
steam, is channeled to stage 400 via one or more pipes or
passageways (not shown) that penetrate shell 106 near outer ring
428. Cooling fluid 436 may be any suitable fluid for cooling stage
400 and that enables steam turbine engine 100 to function as
described herein. Steam 144 is channeled between airfoils 412 to
buckets 402 to rotate rotor shaft 140. Seals 422, 460, and/or 438
facilitate ensuring that steam 144 travels along main flowpath 414
and also facilitate preventing leaks within high-pressure section
102.
[0040] Cooling fluid 436 may be channeled from any suitable cooling
fluid source, such as, for example, a cooling steam source outside
of shell 106, a downstream stage (not shown), and/or a leakage flow
within engine 100. In the exemplary embodiment, cooling fluid 436
enters outer plenum 462 and is discharged from outer ring 428
through passages 464. Cooling fluid 436 discharged from passages
464 enters airfoil passageways 480, and is then channeled through
airfoil passageways 480 prior to being discharged from outlets 490
into wheelspace 416 to facilitate cooling wheel 406 and/or
wheelspace 416. In the exemplary embodiment, cooling fluid 436 is
discharged from wheelspace 416 along any suitable leakage flow path
that enables cooling fluid 436 to enter main flowpath 414, through
seal 438 and/or balance holes (not shown), and/or along any other
suitable path that enables engine 100 to function as described
herein.
[0041] The above-described methods and apparatus facilitate cooling
a rotary component within a steam turbine without modifying
component external geometries, component materials, and/or steam
temperature and/or pressure. More specifically, the above-described
diaphragm has limited, or no, impact on the flowpath physical
geometry while providing the necessary cooling steam to enable
reliable long-term operation of a bucketed steam turbine rotor.
[0042] Furthermore, the above-described airfoils include
passageways through which a cooling fluid may flow radially
inwards, although airfoils used in HP and IP sections of steam
turbines have historically been solid sections. As such, the
above-described airfoils facilitate cooling rotary components
without requiring piping within the flowpath that disturbs the
steam flow. Moreover, the passageways internal to the airfoils do
not affect an external contour of the airfoils. Additionally, the
plenum, passageway, passage, and/or outlet sizing and/or the number
of airfoils that include a passageway therethrough may be selected
to control the amount of cooling fluid supplied and/or the velocity
of the fluid in the passageways, passages, and/or outlets.
[0043] Moreover, the above-described diaphragm facilitates cooling
a fluid within a wheelspace adjacent to a rotary component by lower
a temperature within the wheelspace. Such wheelspace temperature
reduction reduces a bulk temperature of the adjacent rotary
component. Furthermore, by channeling the cooling fluid radially
inward from a radially outer surface of the diaphragm through an
outer ring, an airfoil, and an inner ring, the temperature of the
outer ring, airfoil, and/or inner ring is facilitated to be reduced
as compared to diaphragms that do not include a cooling fluid
flowpath therethrough. The above-described cooling fluid flowpath
supplies a cooling steam flow through a unmodified, known stage
geometry to cool a rotor wheel.
[0044] The above-described method, which brings cooling steam from
outside the sealed outer and/or inner shells to the wheelspace
across the flowpath, facilitates minimizing an adverse effect on
turbine performance by minimizing the geometric impact on the
steampath, as compared to designs that include pipes positioned
within the steampath.
[0045] Exemplary embodiments of a method and apparatus for cooling
a rotary component within a steam turbine are described above in
detail. The method and apparatus are not limited to the specific
embodiments described herein, but rather, components of the method
and apparatus may be utilized independently and separately from
other components described herein. For example, the diaphragm may
also be used in combination with other steam turbine systems and
methods, and is not limited to practice with only the high-pressure
steam turbine section as described herein. Rather, the present
invention can be implemented and utilized in connection with many
other steam turbine cooling applications.
[0046] While the invention has been described in terms of various
specific embodiments, those skilled in the art will recognize that
the invention can be practiced with modification within the spirit
and scope of the claims.
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