U.S. patent application number 14/067257 was filed with the patent office on 2014-05-01 for hot gas segment arrangement.
This patent application is currently assigned to ALSTOM Technology Ltd. The applicant listed for this patent is ALSTOM Technology Ltd. Invention is credited to Christoph Appel, Urs BENZ, Oliver Konradt, Ivan Lenuzzi, Alen Markovic.
Application Number | 20140116059 14/067257 |
Document ID | / |
Family ID | 47215399 |
Filed Date | 2014-05-01 |
United States Patent
Application |
20140116059 |
Kind Code |
A1 |
BENZ; Urs ; et al. |
May 1, 2014 |
HOT GAS SEGMENT ARRANGEMENT
Abstract
A hot gas segment arrangement, especially for a combustion
chamber of a gas turbine, that includes at least one hot gas
segment, which is removably mounted on a carrier, and is subjected
at its outside to hot gas and impingement-cooled at its inside,
whereby an impingement plate with a plurality of distributed
impingement holes is arranged in a distance at the inside of the
impingement plate. A cooling air supply means is provided for
loading the impingement plate with pressurized cooling air in order
to generate through the impingement holes jets of cooling air,
which impinge on the inside of the hot gas segment. The cooling
efficiency and lifetime are increased by the impingement plate
being part of a closed receptacle, which is supplied with the
pressurized cooling air, and by the receptacle with the impingement
plate being mounted on the carrier independently of the hot gas
segment.
Inventors: |
BENZ; Urs; (Gipf-Oberfrick,
CH) ; Appel; Christoph; (Umiken, CH) ;
Konradt; Oliver; (Endingen, CH) ; Lenuzzi; Ivan;
(Karlovac, HR) ; Markovic; Alen; (Karlovac,
HR) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
ALSTOM Technology Ltd |
Baden |
|
CH |
|
|
Assignee: |
ALSTOM Technology Ltd
Baden
CH
|
Family ID: |
47215399 |
Appl. No.: |
14/067257 |
Filed: |
October 30, 2013 |
Current U.S.
Class: |
60/754 |
Current CPC
Class: |
F23R 2900/00012
20130101; F23R 2900/03044 20130101; F23M 5/085 20130101; F23R 3/06
20130101; F23R 3/005 20130101; F23R 3/002 20130101 |
Class at
Publication: |
60/754 |
International
Class: |
F23R 3/00 20060101
F23R003/00 |
Foreign Application Data
Date |
Code |
Application Number |
Oct 31, 2012 |
EP |
12190808.1 |
Claims
1. A hot gas segment arrangement, especially for a combustion
chamber of a gas turbine, comprising at least one hot gas segment,
which is removably mounted on a carrier, is subjected at its
outside to hot gas, and is impingement-cooled at its inside,
whereby an impingement plate with a plurality of distributed
impingement holes is arranged in a distance at the inside of said
impingement plate, and a cooling air supply means is provided for
loading said impingement plate with pressurized cooling air in
order to generate through said impingement holes jets of cooling
air, which impinge on the inside of said hot gas segment, wherein
said impingement plate is part of a closed receptacle, which is
supplied with said pressurized cooling air, and that said
receptacle with said impingement plate is mounted on said carrier
independently of said hot gas segment.
2. The hot gas segment arrangement according to claim 1, wherein
said receptacle is composed of said impingement plate and a back
plate.
3. The hot gas segment arrangement according to claim 1, wherein
said receptacle is mounted on said carrier by means of a hollow
stub, and that said pressurized cooling air is introduced into said
receptacle through said stub.
4. The hot gas segment arrangement according to claim 3, wherein
said receptacle is removably mounted on said carrier.
5. The hot gas segment arrangement according to claim 3, wherein
said stub is disposed centrally with respect to said hot gas
segment.
6. The hot gas segment arrangement according to claim 1, wherein
said hot gas segment encloses said receptacle, that sealing means
are provided between said hot gas segment and said carrier in a
respective groove, and that said impingement plate or receptacle,
respectively, is used to define a sidewall for said sealing means
at a low pressure side thereof.
7. The hot gas segment arrangement according to claim 6, wherein
said sealing means comprises a rope seal.
8. The hot gas segment arrangement according to claim 1, wherein a
plurality of separate hot gas segments are arranged side by side on
a carrier, whereby said hot gas segments adjoin each other with
parallel sidewalls, that a plurality of grooves is provided on the
outside of adjoining sidewalls, whereby the grooves of both
sidewalls start within the sidewall area and open into the hot
region outside said hot gas segments, and whereby the grooves of
both sidewalls pair-wise match with each other, and that each pair
of grooves is connected to the interior of one the adjoining hot
gas segments by means of a cooling hole.
9. The hot gas segment arrangement according to claim 8, wherein
the cooling holes are arranged at the start of the grooves.
10. The hot gas segment arrangement according to claim 8, wherein
the cooling holes are arranged alternating on the one and the other
of the adjoining hot gas segments.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims priority to European application
12190808.1 filed Oct. 31, 2012, the contents of which are hereby
incorporated in its entirety.
TECHNICAL FIELD
[0002] The present invention relates to impingement-cooled hot gas
parts, especially in a combustion chamber of a stationary gas
turbine. It refers to a hot gas segment arrangement according to
the preamble of claim 1.
BACKGROUND
[0003] Combustion chambers of stationary gas turbines must be
effectively cooled to achieve the requested lifetime. On the other
hand, the performance of the machine as well as certain emission
goals have to be considered.
[0004] To achieve a good efficiency of the gas turbine cycle, the
cooling within the combustion chamber has to be efficient. The
cooling is done, dependent on the requirements, by means of
convective cooling, effusion cooling, film cooling, impingement
cooling, or a combination of these different cooling methods. The
last method, impingement cooling, is used, when an intensive
cooling is required without interfering with the hot gas flow of
the machine.
[0005] Hot gas parts (HGP), which are cooled with impingement
cooling, comprise at present an impingement plate and a hot gas
segment, both being connected directly or indirectly by means of
brazing or welding. These hot gas segments are preferably mounted
in circumferential direction of the split line of the machine and
are fixed in circumferential direction.
[0006] FIG. 1 shows an example of an impingement-cooled hot gas
segment according to the prior art. The hot gas segment arrangement
10 according to FIG. 1 comprises a plate-like carrier 11, which is
provided on its hot gas side (lower side in FIG. 1) with hooks 19
for mounting therein a hot gas segment 12. A sealing 17 in form of
a rope seal seals the interior of the hot gas segment 12 against
hot gas on the outside of the hot gas segment 12. Hot gas segment
12 is further fixed in circumferential direction by means of
circumferential fixations 18. The interior of hot gas segment 12 is
accessible for cooling air supplied from the backside of the
carrier 11 through a wide opening 11a in carrier 11.
[0007] The outer wall (bottom in FIG. 1) of hot gas segment 12 is
cooled from the inside by means of impingement cooling. Therefore,
an impingement plate 13 is arranged at a distance from the outer
wall in the interior of hot gas segment 12. The distance is
determined by a plurality of distributed spacers 14. The
impingement plate 13 in this case is essentially flat with its
border being bent up to be brazed or welded to hot gas segment 12
as a fixation 16.
[0008] This technology has disadvantages, as the impingement plate
13 and the hot gas segment 12 are connected by brazing or welding:
[0009] The connection of both parts requires additional technical,
time and cost effort during manufacturing; [0010] The connection of
both parts generates thermal stress due to the different thermal
expansion of impingement plate and hot gas segment during operation
of the machine; the consequence is: [0011] A reduced lifetime; and
[0012] the necessity of relief slots, which reduce the cooling
efficiency. [0013] The connection of both parts requires additional
technical, time and cost effort during reconditioning, i.e.
separation of impingement plate and hot gas segment at the
beginning, and brazing or welding at the end of reconditioning;
[0014] Compared to other cooling schemes a very high leakage occurs
through the hot gas part into the combustion chamber, as a high
pressure drop is necessary for impingement cooling. Inversely, this
means that at a given pressure drop along the hot gas part the
cooling efficiency is reduced; [0015] As the hot gas segment is
mounted in circumferential direction of the parting plane, [0016]
the mounting cross section of the hot gas part may not be affected
by the carrier; and [0017] the removal of the hot gas parts at
disassembly may require an additional time effort, when the hot gas
parts are contorted thermally.
[0018] There is existing a number of prior art publications
concerning the design of impingement-cooled hot gas parts:
[0019] Document EP 1 178 182 A1 discloses a gas turbine segmental
ring, which has an increased rigidity to suppress a thermal
deformation and enables less cooling air leakage by a less number
of connecting portions of segment structures. Cooling air from a
compressor flows through cooling holes of an impingement plate to
enter a cavity and to impinge on a segmental ring for cooling
thereof. The cooling air further flows into cooling passages from
openings of the cavity for cooling an interior of the segmental
ring and is discharged into a gas path from openings of a rear end
of the segmental ring. Waffle pattern of ribs arranged in a lattice
shape is formed on an upper surface of the segmental ring to
thereby increase the rigidity. A plurality of slits are formed in
flanges extending in the turbine circumferential direction to
thereby absorb the deformation and thermal deformation of the
segmental ring is suppressed. It is disadvantageous to have the
impingement plate and the segment mounted on the same heat
insulating ring.
[0020] Document U.S. Pat. No. 7,665,962 B1 discloses a blade outer
air seal in a gas turbine engine, including a plurality of ring
segments secured to a blade ring carrier. An impingement ring forms
a pressure vessel within the blade ring carrier and includes a
first group of impingement holes positioned over the middle of the
blade tip. The ring segments each include a plurality of stiffener
ribs forming a plurality of leading edge pockets, trailing edge
pocket and middle pockets each with pin fins to enhance the heat
transfer effect. A metering plate is secured over the stiffener
ribs to form closed pockets over the edge pockets while leaving the
middle pockets open. A second group of impingement holes are formed
in the metering plate over the edge pockets. Pressurized cooling
air supplied to the pressure vessel first passes through the first
group of impingement holes and is discharged directly over the
middle pockets. The cooling air then flows through the second group
of impingement holes and into the closed edge pockets, and then
leaves through discharge holes, arranged along the leading and
trailing edges of the ring segment. The individual pockets can have
the impingement holes of varying sizes in order to regulate the
amount of cooling air that flows into the specific pocket.
[0021] It is disadvantageous to mount the impingement plate in the
direct neighborhood of the segment.
SUMMARY
[0022] It is an object of the present invention to improve the
cooling efficiency, lifetime and assembly and disassembly of an
impingement-cooled hot gas segment arrangement.
[0023] This and other objects are obtained by a hot gas segment
arrangement according to claim 1.
[0024] The hot gas segment arrangement according to the invention,
which is especially provided for a combustion chamber of a gas
turbine, comprises at least one hot gas segment, which is removably
mounted on a carrier, is subjected at its outside to hot gas, and
is impingement-cooled at its inside, whereby an impingement plate
with a plurality of distributed impingement holes is arranged in a
distance at the inside of said impingement plate, and a cooling air
supply means is provided for loading said impingement plate with
pressurized cooling air in order to generate through said
impingement holes jets of cooling air, which impinge on the inside
of said hot gas segment. It is characterized in that said
impingement plate is part of a closed receptacle, which is supplied
with said pressurized cooling air, and that said receptacle with
said impingement plate is mounted on said carrier independently of
said hot gas segment.
[0025] According to an embodiment of the invention said receptacle
is composed of said impingement plate and a back plate.
[0026] According to another embodiment of the invention said
receptacle is mounted on said carrier by means of a hollow stub,
and that said pressurized cooling air is introduced into said
receptacle through said stub.
[0027] Specifically, said receptacle is removably mounted on said
carrier.
[0028] Specifically, said stub is disposed centrally with respect
to said hot gas segment.
[0029] According to a further embodiment of the invention said hot
gas segment encloses said receptacle, that sealing means are
provided between said hot gas segment and said carrier in a
respective groove, and that said impingement plate or receptacle,
respectively, is used to define a sidewall for said sealing means
at a low pressure side thereof.
[0030] Specifically, said sealing means comprises a rope seal.
[0031] According to another embodiment of the invention a plurality
of separate hot gas segments are arranged side by side on a
carrier, whereby said hot gas segments adjoin each other with
parallel sidewalls, that a plurality of grooves are provided on the
outside of adjoining sidewalls, whereby the grooves of both
sidewalls start within the sidewall area and open into the hot
region outside said hot gas segments, and whereby the grooves of
both sidewalls pair-wise match with each other, and that each pair
of grooves is connected to the interior of one of the adjoining hot
gas segments by means of a cooling hole.
[0032] Specifically, the cooling holes are arranged at the start of
the grooves.
[0033] According to just another embodiment of the invention the
cooling holes are arranged alternating on the one and the other of
the adjoining hot gas segments.
BRIEF DESCRIPTION OF THE DRAWINGS
[0034] The present invention is now to be explained more closely by
means of different embodiments and with reference to the attached
drawings.
[0035] FIG. 1 shows a cross section through a hot gas segment
arrangement according to the state of the art;
[0036] FIG. 2 shows a cross section through a hot gas segment
arrangement according to an embodiment of the invention;
[0037] FIG. 3 shows an embodiment of the inventive cooling design
applied to a combustion chamber transition region as disclosed in
document EP 2 428 647 A1;
[0038] FIG. 4 shows a sidewall design of a hot gas segment
arrangement with adjoining hot gas segments according to another
embodiment of the invention; and
[0039] FIG. 5 shows two adjoining hot gas segments with a sidewall
design according to FIG. 4.
DETAILED DESCRIPTION
[0040] FIG. 2 shows (for a comparison with FIG. 1) a cross section
through a hot gas segment arrangement according to a first
embodiment of the invention. The hot gas segment arrangement 20 of
this embodiment comprises a carrier 21, which carries a hot gas
segment 22 by means of respective hooks 29. The hot gas segment 22
is sealed against the carrier 21 by means of sealings 27 in form of
rope seals. The hot gas segment 22 encloses an impingement plate 23
with a plurality of impingement holes 25. The impingement plate 23
is part of a closed receptacle 24, which receives pressurized
cooling air through a hollow stub 26. The hollow stub is not only
used for cooling air supply but also for fixing the receptacle 24
at the carrier 21. Preferably, the fixation comprises a removable
fastener 28 so that the receptacle 24 can be demounted for
maintenance or reconditioning purposes. The fixation 26, 28 is
centered with respect to the hot gas segment 22.
[0041] FIG. 3 shows a second embodiment of the inventive cooling
design applied to a combustion chamber transition region as
disclosed in document EP 2 428 647 A1. The hot gas segment
arrangement 30 of FIG. 3 comprises a (curved) hot gas segment 32,
which is carried by a carrier 31 by means of hooks 39. The hot gas
segment 32 encloses a closed receptacle 34, which is composed of an
impingement plate 33 with respective impingement holes 35 and a
back plate 40, both plates being connected at a common rim. Again,
a hollow stub 36 with a fastener 38 is used for fixation and
supplying pressurized cooling air to the receptacle 34. The
fixation 36, 38 is centered with respect to the hot gas segment 32.
The hot gas segment 32 is sealed against the carrier 31 by means of
a sealing (rope seal) 37. The rim of the receptacle 34 or
impingement plate 33, respectively, is used as a sidewall 41 for a
groove that receives the sealing 37.
[0042] Thus, according to the invention (see FIGS. 2 and 3) the
impingement plate 23, 33 is part of a closed receptacle 24, 34,
which is directly mounted on the carrier 21, 31. Due to the nearly
identical metal temperatures of impingement plate 23, 33 and
carrier 21, 31, an additional sealing is not necessary with regard
to the mounting of the impingement plate 23, 33 on the carrier 21,
31. However, the sealing at the mounting may be optimized by means
of a sealing edge (i.e. through Hertzian stress).
[0043] Due to the closed impingement plate receptacle 24, 34 only
the pressure downstream of the impingement plate 23, 33 is
determining the leakage over the whole hot gas segment (HGS) 22,
32. The on this way reduced leakage mass flows improve the cooling
efficiency of the machine (gas turbine).
[0044] The individual and separate mounting of the impingement
plate 23, 33 on the carrier 21, 31 results in a decoupling of
impingement plate 23, 33 and hot gas segment (HGS) 22, 32. Thus,
impingement plate 23, 33 and hot gas segment 22, 32 are able to
thermally expand independent from each other. This prolongs the
lifetime of impingement plate 23, 33 and hot gas segment 22, 32 and
supersedes the provision of relief slots at the impingement plate
23, 33.
[0045] Moreover, the impingement plate 33 (FIG. 3) may act as a
sidewall 41 for sealing means 37 between carrier 31 and hot gas
segment 32. As the impingement plate 33 defines the sidewall 41 at
the low-pressure side, the rope seal 37 is prevented from slipping
out of the groove.
[0046] When the core of the hot gas flow through the machine shall
not be affected by impingement cooling air, the impingement cooling
air may leak from between the slots of adjoining hot gas segments
32a-c (FIG. 4) or 32a, 32 b (FIG. 5) by means of effusion or film
cooling. To guarantee a defined cooling mass flow even in the case
of closed slots, a mutually staggered design with additional
grooves 43, 43a, 44a, 44b may be used (see FIGS. 4 and 5).
[0047] As can be seen in FIGS. 4 and 5, a plurality of separate hot
gas segments 32a-c with internal impingement plates 33a, 33b and
sealings 37a, 37b are arranged side by side on a carrier 31,
whereby said hot gas segments 32a-c adjoin each other with parallel
sidewalls 42 or 42a,b, respectively. A plurality of grooves 43a,
44a, 44b are provided on the outside of adjoining sidewalls 42,
42a,b. The (linear and slanted) grooves 43a, 44a, 44b of both
sidewalls 42, 42a,b start within the sidewall area and open into
the hot region outside said hot gas segments 32a-c. The grooves
43a, 44a, 44b of both sidewalls 42a,b match pair-wise with each
other (see FIG. 5), and each pair of grooves 43a, 44b is connected
to the interior of one the adjoining hot gas segments 32a-c by
means of a cooling hole 45. In FIG. 4, every second groove 44a is
provided with a cooling hole 45, while the remaining grooves 43a
are without connection to the respective hot gas segment interior.
In the sidewall of the adjoining hot gas segment the distribution
of the cooling holes 45 is inverse, i.e. the cooling holes 45 are
arranged alternating on the one and the other of the adjoining hot
gas segments 32a-c for a series of groove pairs 43a, 43b (not
shown) and 44a, 44b.
[0048] Preferably, the cooling holes 45 are arranged at the start
of the grooves 44a,b.
[0049] As has been said already, the inventive cooling design
(embodiment of FIG. 3-5) may especially be applied in the
transition region of a combustion chamber of a gas turbine
according to document EP 2 428 647 A1.
[0050] The advantages of the present invention are: [0051] A total
decoupling of impingement plate and hot gas segment (HGS). This
enables [0052] a simplified inspection of impingement plate and hot
gas segment; [0053] a simple reconditioning of the hot gas part
(HGP) (it is not necessary to remove the impingement plate); this
reduces the technical effort and the reconditioning is less costly;
[0054] a longer lifetime of the impingement plate, as there is no
direct contact with the hot gas segment; thus, the impingement
plate can be re-used without reconditioning; [0055] the leakage
along the hot gas part to be substantially lower, as only a part
(e.g. 1/3) of the whole (combustion chamber) pressure drop incurs
at the respective sealing; [0056] the omission of relief slots, as
the thermal behaviour of the impingement plate is independent of
the thermal behaviour of the hot gas segment; in addition, the
necessary cooling air mass flow can be kept low due to the omitted
relief slots; [0057] the time for mounting and demounting can be
reduced, as the impingement plate does not have to be mounted to or
demounted from the carrier. [0058] A mounting/demounting in axial
direction is possible (within a range of 5 mm to 8 mm). [0059] The
re-design of the impingement plate allows a homogeneous or
optimized cooling in all directions, as the cooling efficiency can
be radially (through the sidewalls), axially and in circumferential
direction adjusted in a cost-effective way by drilling respective
impingement cooling holes. [0060] In addition, the impingement air
may be used--if desirable--in a further cooling stage (effusion
cooling, film cooling, impingement cooling, preventing hot gas
inflow). As an example, two impingement cooling stages may be used
in series, provided the necessary pressure is available. In this
way, the expensive cooling air can be used more efficiently. [0061]
The re-design of the impingement plate allows the impingement plate
to be used to define a sidewall for a rope seal at the low pressure
side (see FIGS. 3 and 5). [0062] The impingement plate can be
mounted with a central fixation with respect to the hot gas
segment. This allows minimized relative movements between carrier
and impingement plate fixation during transient operating
conditions of the machine like start-up or loading of the gas
turbine.
* * * * *