U.S. patent application number 12/893276 was filed with the patent office on 2011-03-10 for blade for a gas turbine.
This patent application is currently assigned to ALSTOM TECHNOLOGY LTD. Invention is credited to Roland Duckershoff, Beat VON ARX, Brian Kenneth WARDLE.
Application Number | 20110058957 12/893276 |
Document ID | / |
Family ID | 39592112 |
Filed Date | 2011-03-10 |
United States Patent
Application |
20110058957 |
Kind Code |
A1 |
VON ARX; Beat ; et
al. |
March 10, 2011 |
BLADE FOR A GAS TURBINE
Abstract
A blade is provided for a gas turbine, especially for the
low-pressure turbine of a gas turbine with sequential combustion,
and is produced in accordance with a casting process and has a
blade airfoil which extends in the radial direction between an
inner platform and an outer platform, and in the interior of which
extends a cooling passage, bypassing the platforms, and through
which flows a cooling medium, especially cooling air, for cooling
the blade. In the outer and/or inner platform there are core outlet
openings which arise from the use of a casting core and which
connect the cooling passage to the outside space and are sealed off
by means of a sealing element. Optimum cooling is ensured by the
sealing elements being formed and inserted into the core outlet
openings so that they align with the wall surface of the cooling
passage in a flush manner.
Inventors: |
VON ARX; Beat; (Trimbach,
CH) ; Duckershoff; Roland; (Hohr-Grenzhausen, DE)
; WARDLE; Brian Kenneth; (Brugg-Lauffohr, CH) |
Assignee: |
ALSTOM TECHNOLOGY LTD
Baden
CH
|
Family ID: |
39592112 |
Appl. No.: |
12/893276 |
Filed: |
September 29, 2010 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
PCT/EP2009/053116 |
Mar 17, 2009 |
|
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12893276 |
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Current U.S.
Class: |
416/96R |
Current CPC
Class: |
F01D 9/041 20130101;
F05D 2230/21 20130101; F05D 2230/60 20130101; F01D 5/147 20130101;
B22D 31/002 20130101 |
Class at
Publication: |
416/96.R |
International
Class: |
F01D 5/18 20060101
F01D005/18 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 31, 2008 |
CH |
00470/08 |
Claims
1. A blade (20) for a gas turbine (10), said blade (20) being
produced in accordance with a casting process and comprises a blade
airfoil (22) which extends in a radial direction between a blade
tip (23) and a shroud (21) and in an interior of which extends a
cooling passage (39), which bypasses the shroud and blade tip (21,
23), and through which flows a cooling medium for cooling the blade
(20), wherein in end-face ends (21 or 23) of the blade (20) there
are core outlet openings (40 or 41) which arise from the use of a
casting core and which connect the cooling passage (39) to an
outside space and are sealed off by a sealing element (32 or 36),
the sealing element (32, 36) is formed and inserted into the core
outlet openings (40, 41) so that it aligns with a wall surface of
the cooling passage (39) in a flush manner.
2. The blade as claimed in claim 1, wherein the sealing elements
are formed as prefabricated sealing plugs (32, 36).
3. The blade as claimed in claim 1, wherein the sealing elements
(32, 36) are hard-soldered into the core outlet openings (40,
41).
4. The blade as claimed in claim 3, wherein abutment surfaces (33,
37), upon which lie the sealing elements (32, 36), are formed in
the core outlet openings (40, 41).
5. The blade as claimed in claim 1, wherein the sealing elements
(32, 36) are inserted into the core outlet openings (40, 41) so
that they align with outer surfaces of the shroud and blade tip
(21, 23) in a flush manner.
6. The blade as claimed in claim 2, wherein the sealing plugs (32,
36) are hard-soldered into the core outlet openings (40, 41).
7. The blade as claimed in claim 6, wherein abutment surfaces (33,
37), upon which lie the sealing plugs (32, 36), are formed in the
core outlet openings (40, 41).
8. The blade as claimed in claim 2, wherein the sealing plugs (32,
36) are inserted into the core outlet openings (40, 41) so that
they align with outer surfaces of the shroud and blade tip (21, 23)
in a flush manner.
9. A gas turbine comprising a blade (20), said blade (20) being
produced in accordance with a casting process and has a blade
airfoil (22) which extends in a radial direction between a blade
tip (23) and a shroud (21) and in an interior of which extends a
cooling passage (39), which bypasses the shroud and blade tip (21,
23), and through which flows a cooling medium for cooling the blade
(20), wherein in end-face ends (21 or 23) of the blade (20) there
are core outlet openings (40 or 41) which arise from the use of a
casting core and which connect the cooling passage (39) to an
outside space and are sealed off by a sealing element (32 or 36),
the sealing element (32, 36) is formed and inserted into the core
outlet openings (40, 41) so that they align with a wall surface of
the cooling passage (39) in a flush manner, wherein the blade (20)
is arranged in a turbine (15, 18) of the gas turbine (10).
10. The gas turbine as claimed in claim 9, wherein the gas turbine
(10) is a gas turbine with sequential combustion, having a first
combustion chamber (14) with a downstream high-pressure turbine
(15), and a second combustion chamber (17) with a downstream
low-pressure turbine (18), and the blade (20) is a stator blade
which is arranged in the low-pressure turbine (18).
11. The gas turbine as claimed in claim 10, wherein the
low-pressure turbine has a plurality of rows of stator blades
arranged in series in the flow direction, and the stator blade (20)
is arranged in a middle stator blade row.
12. The gas turbine as claimed in claim 9, wherein the blade (20)
is a rotor blade.
Description
CROSS REFERENCE TO RELATED APPLICATION
[0001] This application is a continuation of International
Application No. PCT/EP2009/053116 filed Mar. 17, 2009, which claims
priority to Swiss Patent Application No. 00470/08, filed Mar. 31,
2008, the entire contents of all of which are incorporated by
reference as if fully set forth.
FIELD OF INVENTION
[0002] The present invention relates to the field of gas turbine
technology, in particular to a blade for a gas turbine.
BACKGROUND
[0003] Gas turbines with sequential combustion are known and have
been proved to be successful in industrial operation.
[0004] Such a gas turbine, which has been known among experts as
GT24/26, is disclosed for example in an article by Joos, F. et al.,
"Field Experience of the Sequential Combustion System for the ABB
GT24/GT26 Gas Turbine Family", IGTI/ASME 98-GT-220, 1998 Stockholm.
FIG. 1 there shows the basic construction of such a gas turbine,
wherein FIG. 1 there is reproduced in the present application as
FIG. 1. Furthermore, such a gas turbine is disclosed in EP-B1-0 620
362.
[0005] FIG. 1 shows a gas turbine 10 with sequential combustion, in
which a compressor 11, a first combustion chamber 14, a
high-pressure turbine (HPT) 15, a second combustion chamber 17 and
a low-pressure turbine (LPT) 18 are arranged along an axis 19. The
compressor 11 and the two turbines 15, 18 are part of a rotor which
rotates around the axis 19. The compressor 11 draws in air and
compresses it. The compressed air flows into a plenum and from
there into premix burners where this air is mixed with at least one
fuel, at least with fuel which is introduced via the fuel feed line
12. Such premix burners are disclosed in principle in EP-A1-0 321
809 or EP-A2-0 704 657.
[0006] The compressed air flows into the premix burners, where the
mixing with at least one fuel takes place, as explained above. This
fuel/air mixture then flows into the first combustion chamber 14,
into which this mixture is combusted, forming a stable flame front.
The hot gas which is thus made available is partially expanded in
the adjoining high-pressure turbine 15, performing work, and then
flows into the second combustion chamber 17 where a further feed 16
of fuel takes place. As a result of the high temperatures which the
hot gas, which is partially expanded in the high-pressure turbine
15, always has, a combustion, which is based on self-ignition,
takes place in the second combustion chamber 17. The hot gas which
is reheated in the second combustion chamber 17 is then expanded in
a multistage low-pressure turbine 18.
[0007] The low-pressure turbine 18 comprises a plurality of rows,
arranged in series in the flow direction, of rotor blades and
stator blades, which are arranged in alternating sequence. For
example, the stator blades of the third stator blade row in the
flow direction are provided with the designation 20' in FIG. 1.
[0008] The stator blades in their interior are provided with a
cooling passage which is guided back and forth mostly in a
serpentine manner between the ends of the blade airfoil and through
which flows a cooling medium, mostly cooling air. This also applies
to all the thermally highly loaded rotor blades.
[0009] For producing such a blade, a casting process, in which a
casting core is used for forming the cooling passage, is
predominantly used. For production engineering reasons, the casting
core projects from the blade at one or both ends and after
completion of the casting process correspondingly leaves behind one
or more core outlet openings which later have to be sealed off. A
method for sealing off such openings is described for example in
printed publication U.S. Pat. No. 6,837,417B2. With this method,
the opening in the blade is sealed off by a sintered cap which
neither on the inner side nor on the outer side aligns with the
respective wall surface in a flush manner. This leads to uneven,
stepped surfaces which impede the flow of the medium which is used
for cooling and so impair the effectiveness of the cooling, even
partially cancelling it out.
SUMMARY
[0010] The present disclosure is directed to a blade for a gas
turbine. The blade is produced in accordance with a casting process
and includes a blade airfoil which extends in a radial direction
between a blade tip and a shroud and in an interior of which
extends a cooling passage, which bypasses the shroud and blade tip.
A cooling medium flows through the cooling passage for cooling the
blade. In end-face ends of the blade there are core outlet openings
which arise from the use of a casting core and which connect the
cooling passage to an outside space and are sealed off by a sealing
element. The sealing element is formed and inserted into the core
outlet openings so that it aligns with a wall surface of the
cooling passage in a flush manner.
[0011] The present disclosure is also directed to a gas turbine
including a blade which is produced in accordance with a casting
process and includes a blade airfoil which extends in a radial
direction between a blade tip and a shroud and in an interior of
which extends a cooling passage, which bypasses the shroud and
blade tip. A cooling medium flows through the cooling passage for
cooling the blade. In end-face ends of the blade there are core
outlet openings which arise from the use of a casting core and
which connect the cooling passage to an outside space and are
sealed off by a sealing element. The sealing element is formed and
inserted into the core outlet openings so that it aligns with a
wall surface of the cooling passage in a flush manner, with the
blade being arranged in a turbine of the gas turbine.
BRIEF DESCRIPTION OF THE DRAWINGS
[0012] The invention shall subsequently be explained in more detail
based on exemplary embodiments in conjunction with the drawing. All
elements which are not essential for the direct understanding of
the invention have been omitted. Like elements are provided with
the same designations in the different figures. The flow direction
of the media is indicated by arrows. In the drawings:
[0013] FIG. 1 shows the principle construction of a gas turbine
with sequential combustion according to the prior art,
[0014] FIG. 2 shows a stator blade in a perspective side view,
[0015] FIG. 3 shows the shroud, with a first core outlet opening,
in plan view from the top,
[0016] FIG. 4 shows the section through the sealed-off core outlet
opening in the plane IV-IV of FIG. 3 according to an exemplary
embodiment of the invention,
[0017] FIG. 5 shows the inner platform, with a second core outlet
opening, in plan view from the bottom, and
[0018] FIG. 6 shows the section through the sealed-off core outlet
opening in the plane VI-VI of FIG. 5 according to another exemplary
embodiment of the invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Introduction to the Embodiments
[0019] It is an object of the invention to create a blade of the
type referred to in the introduction which avoids the disadvantages
of known blades and which provides an optimized, undisturbed flow
of the cooling medium in the blade.
[0020] The object is achieved by the entirety of the features of
the invention. In the invention, the sealing elements are formed
and inserted into the core outlet openings so that they align with
the wall surface of the cooling passage in a flush manner. As a
result of this, negative influencing of the flow of the cooling
medium by means of the sealing elements is reliably avoided.
[0021] In one development, the sealing elements are formed as
prefabricated sealing plugs. These can be inserted into the core
outlet openings in a simple manner and fixed quickly and reliably
there. This takes place preferably by the sealing elements, or
sealing plugs, being hard-soldered into the core outlet
openings.
[0022] The sealing element or the sealing plug can be positioned
especially simply if abutting surfaces, upon which lie the sealing
elements or sealing plugs, are formed in the core outlet
openings.
[0023] According to another development, the sealing elements or
sealing plugs are inserted into the core outlet openings so that
they align with the outer surfaces of the platforms in a flush
manner. As a result of this, fluidic advantages also ensue in the
outside space of the blade.
[0024] The blade according to the invention is advantageously used
in a gas turbine.
[0025] The gas turbine in this case can be a gas turbine with
sequential combustion, having a first combustion chamber with a
downstream high-pressure turbine, and a second combustion chamber
with a downstream low-pressure turbine, wherein the blades are
arranged both in the low-pressure turbine and in the high-pressure
turbine. In particular, the low-pressure turbine in such a gas
turbine has a plurality of rows of stator blades and rotor blades
in series in the flow direction.
DETAILED DESCRIPTION
[0026] In FIG. 2, in a perspective side view, is a stator blade
which can be used for example in the low-pressure turbine of a gas
turbine with sequential combustion according to FIG. 1, and which
is suitable for realization of the invention. The use of the
subject according to the invention, however, is limited neither to
said gas turbine type nor to a special stator blade or rotor blade
nor to a specific blade row. The stator blade 20 which is taken as
a basis here comprises a blade airfoil 22 which is curved in space
and extends in the longitudinal direction (in the radial direction
of the gas turbine) between a blade tip 23 and a shroud 21, and in
the direction of the hot gas flow 30 extends from a leading edge 27
to a trailing edge 28. Between the two edges 27 and 28, the blade
airfoil 22 is delimited on the outside by a pressure side 31
(facing the viewer in FIG. 2) and an (opposite) suction side.
[0027] The stator blade 20 is fastened on the turbine casing by
hook-like fastening elements 24 and 25 which are formed on the
upper side of the shroud 21, while blade tip 23 butts against the
rotor with sealing effect.
[0028] In the interior of the blade airfoil 22, provision is made
for a cooling passage (39 in FIGS. 4, 6), which extends back and
forth in a serpentine manner between the platforms 21, 23, for
cooling the blade 20, as is shown for example in printed
publication WO-A1-2006029983. For producing such a cooling passage
by a casting technique there is a requirement for a core which in
the present example leaves behind in the platforms 21 and 23 the
core outlet openings 40 in the shroud (FIG. 3, 4) or 41 in the
blade tip (FIGS. 5, 6).
[0029] The core outlet openings 40, 41 are formed and sealed off by
corresponding sealing plugs 32 or 36 according to FIG. 4 and FIG. 6
so that the outer surfaces of the sealing plugs 32, 26 align with
the wall surfaces of the surroundings in a flush manner at least
where the wall surfaces are impinged upon by the flowing cooling
medium. This is particularly the case in the cooling passage 39
through which the cooling medium is guided in the interior of the
blade.
[0030] In the case of the round core outlet opening 40, which is
provided in the shroud 21, an annular abutment surface 33 is
created in the core outlet opening by a diameter step, the sealing
plug 32 being seated on this by a corresponding shoulder (FIG. 4).
The sealing plug 32 in this case is dimensioned and formed so that
after its insertion into the core outlet opening 40 both the outer
surface of the shroud 21 and the surface 35 of the inner wall of
the cooling passage 39 are continuous. The sealing plug 32 is fixed
in the core outlet opening 40 preferably by means of a
hard-soldered connection 34.
[0031] A similar procedure is applied in the case of the four-sided
core outlet opening 41 in the blade tip 23. In the core outlet
opening 41, provision is made on opposite sides, at a specified
depth, for abutting surfaces 37 on which is seated the sealing plug
36 which is inserted into the core outlet opening 41 and adapted in
the edge contour (FIG. 6). Also in this case, the sealing plug 36
is fixed in the core outlet opening 41 by means of hard-soldered
connections 38 and aligns with the surrounding surface in a flush
manner.
[0032] By means of the invention, which in principle can be used in
all cooled blades of turbines, the disturbing influence of the
sealing elements upon the flow of the cooling medium is minimized.
As a result, the walls of the blade are optimally cooled, which
leads to an extension of the blade service life. A preferred use of
the blade according to the invention is to be encountered in large
stationary gas turbines, for example in gas turbines with
sequential combustion, which have been known among experts under
the designation GT24/26. In the case of the last-named gas
turbines, the preferred use of such a blade can be in the
low-pressure turbine. Such a blade can also be used in other gas
turbine types.
LIST OF DESIGNATIONS
[0033] 10 Gas turbine [0034] 11 Compressor [0035] 12, 16 Fuel feed
line [0036] 13 EV burner [0037] 14, 17 Combustion chamber [0038] 15
High-pressure turbine [0039] 18 Low-pressure turbine [0040] 19 Axis
[0041] 20, 20' Blade [0042] 21 Shroud [0043] 22 Blade airfoil
[0044] 23 Blade tip [0045] 24, 25 Fastening element (hook-like)
[0046] 27 Leading edge [0047] 28 Trailing edge [0048] 29 Throttling
element [0049] 30 Hot gas flow [0050] 31 Pressure side [0051] 32,
36 Sealing plug [0052] 33, 37 Abutment surface [0053] 34, 38
Hard-soldered connection [0054] 35 Surface (cooling passage) [0055]
39 Cooling passage [0056] 40, 41 Core outlet opening
* * * * *