U.S. patent application number 13/712258 was filed with the patent office on 2013-06-13 for steam turbine, blade, and method.
This patent application is currently assigned to NUOVO PIGNONE S.P.A. The applicant listed for this patent is NUOVO PIGNONE S.P.A. Invention is credited to Enrico Giusti, Marco Grilli, Enzo Imparato.
Application Number | 20130149106 13/712258 |
Document ID | / |
Family ID | 45571626 |
Filed Date | 2013-06-13 |
United States Patent
Application |
20130149106 |
Kind Code |
A1 |
Giusti; Enrico ; et
al. |
June 13, 2013 |
STEAM TURBINE, BLADE, AND METHOD
Abstract
A stator blade ring comprising a plurality of stator blade
modules defining an annular chamber is provided. The plurality of
stator blade modules comprises an elongated blade portion
comprising a first and a second blade shell portion, a longitudinal
passageway, and at least one opening extending through at least one
of the first and the second blade shell portion to the longitudinal
passageway, an inner portion brazed to a first longitudinal end of
the elongated blade portion, wherein the inner portion comprises a
through hole forming a portion of the annular chamber, and an inner
passageway extending from the through hole to the longitudinal
passageway, and an outer portion brazed to a second longitudinal
end of the elongated blade portion and engaged to a steam turbine,
the outer portion comprising an outer passageway open to a surface
of the steam turbine and the longitudinal passageway.
Inventors: |
Giusti; Enrico; (Pistoia,
IT) ; Grilli; Marco; (Pisa, IT) ; Imparato;
Enzo; (Sesto Fiorentino, IT) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
NUOVO PIGNONE S.P.A; |
Florence |
|
IT |
|
|
Assignee: |
NUOVO PIGNONE S.P.A
Florence
IT
|
Family ID: |
45571626 |
Appl. No.: |
13/712258 |
Filed: |
December 12, 2012 |
Current U.S.
Class: |
415/115 ;
29/889.22 |
Current CPC
Class: |
F01D 25/32 20130101;
F05D 2220/31 20130101; F01D 9/044 20130101; F01D 9/041 20130101;
F05D 2230/237 20130101; Y10T 29/49323 20150115 |
Class at
Publication: |
415/115 ;
29/889.22 |
International
Class: |
F01D 25/32 20060101
F01D025/32; F01D 9/04 20060101 F01D009/04 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 12, 2011 |
IT |
CO2011A000060 |
Claims
1. A stator blade ring for a steam turbine, the stator blade ring
comprising: a plurality of stator blade modules defining an annular
chamber, wherein each of the plurality of stator blade modules
comprises: an elongated blade portion comprising a first blade
shell portion, a second blade shell portion brazed to the first
blade shell portion, a longitudinal passageway; and at least one
opening extending through at least one of the first blade shell
portion and the second blade shell portion to the longitudinal
passageway; an inner portion brazed to a first longitudinal end of
the elongated blade portion, wherein the inner portion comprises a
through hole forming a portion of the annular chamber, and an inner
passageway extending from the through hole to the longitudinal
passageway; and an outer portion brazed to a second longitudinal
end of the elongated blade portion and engaged to the steam
turbine, wherein the outer portion comprises an outer passageway
open to a surface of the steam turbine and the longitudinal
passageway.
2. The stator blade ring of claim 1, wherein the outer portion
further comprises: a first groove configured to engage a first
ridge in the surface of the steam turbine; and a second groove
configured to engage a second ridge in the surface of the steam
turbine.
3. The stator blade ring of claim 2, wherein the first groove and
the second groove are offset relative to the inner portion.
4. The stator blade ring of claim 3, wherein a groove in the inner
portion forms a circumferential groove in the stator blade ring,
wherein the circumferential groove is engaged by a metal ring
configured to lock the plurality of stator blade modules
together.
5. The stator blade ring of claim 4, wherein the circumferential
groove faces inwardly towards a center of the stator blade
ring.
6. A multi-stage steam turbine, comprising: a rotor assembly
comprising at least one impeller; a bearing connected to the rotor
assembly, wherein the bearing is configured to rotatably support
the rotor assembly; and a stator blade ring for the last stage of
the steam turbine, wherein the stator blade ring comprises a
plurality of stator blade modules defining an annular chamber,
wherein each of the plurality of stator blade modules comprises: at
least one elongated blade portion comprising a first blade shell
portion and a second blade shell portion brazed to the first blade
shell portion; an inner portion brazed to a first longitudinal end
of the at least one elongated blade portion, wherein the inner
portion comprises a through hole forming a portion of the annular
chamber; and an outer portion brazed to a second longitudinal end
of the at least one elongated blade portion and engaged to a
surface of the steam turbine, wherein the at least one elongated
blade portion of at least one of the plurality of stator blade
modules further comprises a first longitudinal passageway and an
opening for steam condensate to enter the first longitudinal
passageway, wherein the inner portion of the at least one of the
plurality of stator blade modules comprises a first inner
passageway extending from the through hole to the first
longitudinal passageway for the steam condensate to flow between
the annular chamber and the first longitudinal passageway; wherein
the at least one elongated blade portion of another of the
plurality of stator blade modules comprises a second longitudinal
passageway, the inner portion of the another of the plurality of
stator blade modules comprising a second inner passageway extending
from the through hole to the second longitudinal passageway for
allowing the steam condensate to flow between the annular chamber
and the second longitudinal passageway, and wherein the outer
portion of the another of the plurality of stator blade modules
comprises an outer passageway extending from the second
longitudinal passageway and opening to the surface of the steam
turbine for allowing the steam condensate to flow out of the stator
blade ring.
7. The steam turbine of claim 6, wherein a first groove in the
outer portion of each of the plurality of stator blade modules is
engaged by a first ridge on the surface of the steam turbine.
8. The steam turbine of claim 7, wherein a second groove in the
outer portion of each of the plurality of stator blade modules is
engaged by a second ridge on the surface of the steam turbine.
9. The steam turbine of claim 8, wherein the first groove faces
upstream and the second groove faces downstream of a flow of
working fluid within the steam turbine.
10. A method of making a blade module for a stator blade ring in
the last stage of a steam turbine, wherein the blade module
comprises an elongated blade portion, an inner portion, and an
outer portion, the method comprising: brazing a first edge and a
second edge of a first blade shell portion to a first edge and a
second edge of a second blade shell portion to form a longitudinal
passageway in the elongated blade portion; forming a through hole
in the inner portion; forming an inner passageway in the inner
portion extending from a surface of the inner portion to the
through hole; brazing a first longitudinal end of the elongated
blade portion to the surface of the inner portion such that the
longitudinal passageway is open to the inner passageway; forming an
outer passageway in the outer portion extending from a first
surface of the outer portion to a second surface of the outer
portion; and brazing a second longitudinal end of the elongated
blade portion to the first surface of the outer portion such that
the longitudinal passageway is open to the outer passageway.
Description
BACKGROUND OF THE INVENTION
[0001] Embodiments of the present invention relate generally to
steam turbines and, more specifically, to a stator blade ring for a
steam turbine and a method of making a stator blade ring.
[0002] A steam turbine is a turbo machine which converts thermal
and pressure energy of steam into rotary motion which may be used
to perform work. Steam turbines may be used, for example, to drive
electrical generators or compressors.
[0003] To enhance steam turbine efficiency, steam is often expanded
through a number of stages. Each stage typically includes a stator
blade diaphragm and a bearing mounted rotor assembly including at
least one impeller.
[0004] As steam progresses through the latter stages of the steam
turbine, sufficient energy may be absorbed from the steam to cause
portions of the steam to condense, and thus, to become so called,
wet steam. In addition to having a potential corrosive effect, when
wet steam impinges against the stator blade diaphragm, the
condensate tends to violently impact the stator blades and other
parts of the diaphragm. As a result, the stator blades and other
portions of each stator blade diaphragm in the latter stages of the
steam turbine may be damaged, for example, during prolonged
exposure to wet steam having a high proportion of condensate.
[0005] In modern steam turbines, the manufacture of stator blade
diaphragms represents a significant cost, particularly in multi
stage steam turbines having three or more stages each of which may
include one or more separate stator blade diaphragms.
[0006] If a stator blade diaphragm is damaged, the steam turbine
may need to be shut down and the damaged stator diaphragm removed
for servicing. If on site repair is not possible, the entire
diaphragm may need to be sent for repair or, alternatively, an
entire new stator diaphragm must be installed. Worse yet, if a
replacement is available, a new stator blade diaphragm must be
fabricated. Thus, in addition to the cost of the stator diaphragm,
costs associated with the extended downtime of the steam turbine
are also incurred.
[0007] Accordingly, what is needed is a replacement for the
conventional stator blade diaphragm, which is easily serviced
and/or replaced, which is capable of successful operation in the
presence of wet steam, and which provides a simple design which is
easier manufactured.
BRIEF SUMMARY OF THE INVENTION
[0008] According to an embodiment of the present invention, there
is provided a stator blade ring for a steam turbine. The stator
blade ring comprises a plurality of stator blade modules defining
an annular chamber. Each of the plurality of stator blade modules
comprises an elongated blade portion comprising a first blade shell
portion, a second blade shell portion brazed to the first blade
shell portion, a longitudinal passageway, and at least one opening
extending through at least one of the first blade shell portion and
the second blade shell portion to the longitudinal passageway. Each
of the plurality of stator blade modules further comprises an inner
portion brazed to a first longitudinal end of the elongated blade
portion, wherein the inner portion comprises a through hole forming
a portion of the annular chamber, and an inner passageway extending
from the through hole to the longitudinal passageway, and an outer
portion brazed to a second longitudinal end of the elongated blade
portion and engaged to the steam turbine, wherein the outer portion
comprises an outer passageway open to a surface of the steam
turbine and the longitudinal passageway.
[0009] According to an embodiment of the present invention, there
is provided a multi-stage steam turbine. The multi-stage steam
turbine comprises a rotor assembly comprising at least one
impeller, a bearing connected to the rotor assembly, wherein the
bearing is configured to rotatably support the rotor assembly, and
a stator blade ring for the last stage of the steam turbine,
wherein the stator blade ring comprises a plurality of stator blade
modules defining an annular chamber. Each of the plurality of
stator blade modules comprises at least one elongated blade portion
comprising a first blade shell portion and a second blade shell
portion brazed to the first blade shell portion, an inner portion
brazed to a first longitudinal end of the at least one elongated
blade portion, wherein the inner portion comprises a through hole
forming a portion of the annular chamber, and an outer portion
brazed to a second longitudinal end of the at least one elongated
blade portion and engaged to a surface of the steam turbine. The at
least one elongated blade portion of at least one of the plurality
of stator blade modules further comprises a first longitudinal
passageway and an opening for steam condensate to enter the first
longitudinal passageway. The inner portion of the at least one of
the plurality of stator blade modules comprises a first inner
passageway extending from the through hole to the first
longitudinal passageway for the steam condensate to flow between
the annular chamber and the first longitudinal passageway. The at
least one elongated blade portion of another of the plurality of
stator blade modules comprises a second longitudinal passageway,
the inner portion of the another of the plurality of stator blade
modules comprising a second inner passageway extending from the
through hole to the second longitudinal passageway for allowing the
steam condensate to flow between the annular chamber and the second
longitudinal passageway. The outer portion of the another of the
plurality of stator blade modules comprises an outer passageway
extending from the second longitudinal passageway and opening to
the surface of the steam turbine for allowing the steam condensate
to flow out of the stator blade ring.
[0010] According to an embodiment of the present invention, there
is provided a method of making a blade module for a stator blade
ring in the last stage of a steam turbine, wherein the blade module
comprises an elongated blade portion, an inner portion, and an
outer portion. The method comprises brazing a first edge and a
second edge of a first blade shell portion to a first edge and a
second edge of a second blade shell portion to form a longitudinal
passageway in the elongated blade portion, forming a through hole
in the inner portion, forming an inner passageway in the inner
portion extending from a surface of the inner portion to the
through hole, brazing a first longitudinal end of the elongated
blade portion to the surface of the inner portion such that the
longitudinal passageway is open to the inner passageway, forming an
outer passageway in the outer portion extending from a first
surface of the outer portion to a second surface of the outer
portion, and brazing a second longitudinal end of the elongated
blade portion to the first surface of the outer portion such that
the longitudinal passageway is open to the outer passageway.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] The accompanying drawings, which are incorporated in and
constitute a part of the specification, illustrate one or more
embodiments and, together with the description, explain these
embodiments. In the drawings:
[0012] FIG. 1 depicts a steam turbine according to an exemplary
embodiment;
[0013] FIG. 2 shows a perspective view of an exemplary
embodiment;
[0014] FIG. 3 shows a side view of the exemplary embodiment of FIG.
2;
[0015] FIG. 4 shows a cross-sectional view of the exemplary
embodiment shown in FIG. 2;
[0016] FIGS. 5 to 7 show an inner portion of the exemplary
embodiment shown in FIG. 2;
[0017] FIGS. 8 to 10 show an outer portion of the exemplary
embodiment shown in FIG. 2; and
[0018] FIG. 11 is a flowchart illustrating a method of making a
blade module for a stator blade ring according to an exemplary
embodiment.
DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS OF THE INVENTION
[0019] The following description of the exemplary embodiments
refers to the accompanying drawings. The same reference numbers in
different drawings identify the same or similar elements. The
following detailed description does not limit the invention.
Instead, the scope of the invention is defined by the appended
claims. The following embodiments are discussed, for simplicity,
with regard to the terminology and structure of a turbo machine
that has a stator and a rotor. However, the embodiments to be
discussed next are not limited to these exemplary systems, but may
be applied to other systems.
[0020] Reference throughout the specification to "one embodiment"
or "an embodiment" means that a particular feature, structure, or
characteristic described in connection with an embodiment is
included in at least one embodiment of the subject matter
disclosed. Thus, the appearance of the phrases "in one embodiment"
or "in an embodiment" in various places throughout the
specification is not necessarily referring to the same embodiment.
Further, the particular features, structures or characteristics may
be combined in any suitable manner in one or more embodiments.
[0021] To provide some context for the subsequent discussion
relating to stator blades according to these exemplary embodiments,
FIG. 1 schematically illustrates a turbo machine in the form of a
multistage steam turbine 400. Therein, the steam turbine 400
includes a housing (stator) 420 within which a number of stator
blade diaphragms 430 are disposed along with a rotor shaft 450
provided with a plurality of impeller rotors 440. The shaft 450 is
supported radially and axially through bearings 480.
[0022] During operation, the steam turbine takes a steam input from
an inlet 460 through various stages of expansion, to an outlet 470
leading to a condenser. At each turbine stage, steam is directed by
a stator diaphragm 430 onto an impeller rotor 440 thereby
converting the temperature and pressure energy of the steam into
rotating energy available for work at the rotor shaft 450.
[0023] FIG. 2 shows a portion of a stator blade ring 12 according
to an exemplary embodiment of the present invention. Stator blade
ring 12 includes a plurality of individual stator blade modules 14
extending around rotor 28 (FIG. 3) in steam turbine 10. FIG. 2
shows two such blade modules 14a and 14b.
[0024] Each stator blade module 14a, 14b includes an elongated
blade portion 16, as shown in FIGS. 2 and 3. FIG. 4 shows a
cross-sectional view of an elongated blade portion 16 having a
longitudinal reinforcing rib 24 and longitudinal passageways 26. As
is further shown in FIG. 4, a blade portion 116 may also be
provided without reinforcing rib 24 and may thus have a single
longitudinal passageway 26. As will be discussed in further detail
below, each blade portion 16 is made by brazing a first blade shell
portion 18 to a second blade shell portion 22 along the upstream
edge 32 and the downstream edge 34 thereof.
[0025] As further shown in FIGS. 2 to 4, each blade portion 16
includes a plurality of openings 36 in at least one of blade shell
portion 22 and blade shell portion 24. In the embodiment of FIGS. 2
to 4, each opening 36 is a slot formed by electric discharge
machining. Alternatively, openings 36 may be formed by other
machining processes such as drilling or milling, or, openings 36
may be formed during the initial manufacture of blade shell portion
22 and blade shell portion 24, for example, by a mold insert.
[0026] Each blade module 14 includes an inner portion 38 connected
to a first longitudinal end of at least one blade portion 16, as
shown in FIG. 2. In the embodiment shown in FIGS. 2 to 4, inner
portion 38 is brazed to blade portion 16, as will be discussed
further below. Each inner portion 38 includes a through hole 42
extending transversely to the longitudinal axis 46 (FIG. 3) of
blade portion 16. Through hole 42 forms a part of an annular
chamber 20 in stator blade ring 12 when each of the blade modules
are installed into the steam turbine 10. In order to enhance the
seal between through holes 42 in adjacent blade modules 14, at
least one end of each through hole 42 may be provided with a groove
48 configured to receive a sealing gasket. In the embodiment of
FIGS. 2 to 4, groove 48 is configured to receive an O-ring.
[0027] Each inner portion 38 also includes at least one inner
passageway 44, as shown in FIG. 3, extending from through hole 42
to each longitudinal passageway 26. Alternatively, if reinforcement
rib 24 is terminated prior to the longitudinal end of blade portion
16, then a single inner passageway 44 may be open to both
longitudinal passageways 26.
[0028] Each stator blade module 14 also includes an outer portion
52 connected to a second longitudinal end of at least one blade
portion 16, as shown in FIGS. 2 and 3. Each outer portion 52
includes at least one outer passageway 54 which is open to each
longitudinal passageway 26 and to an interior surface of steam
turbine 10, as shown in FIGS. 2, 9 and 10. Further, in the
embodiment of FIGS. 2 to 4 and 8 to 10, each outer portion may
include a groove 74 on at least one side thereof. Groove 74 may be
configured to receive a gasket for sealing adjacent outer portions
52 to each other and/or for providing a dampening effect to stator
blade ring 12. Stator blade ring 12 may be used in one of the
latter stages of the steam turbine 10, as shown in FIG. 2. During
operation, condensate from the wet steam impinging against each
blade portion 14 may enter the longitudinal passageway 26 of a
blade portion 16 through one of the openings 36. Multiple paths are
available for the condensate to travel within the blade modules 14
before exiting outside stator blade ring 12 at a location where the
condensate may be less likely to cause damage to the components of
steam turbine 10. In one path, which may include stator blade
modules 14 above the rotor shaft, the condensate may travel
downwardly through each longitudinal passageway 26 and inner
passageway 44 into through hole 42. The open through holes 42 in
adjacent blade modules 14 that form the annular chamber 20
extending around stator blade ring 12 allow the condensate to
continue flowing downwardly with gravity. The condensate may exit
the annular chamber 20 and continue on a downward path through an
inner passageway 44 of a blade module 14 below the rotor shaft of
steam turbine 10. Finally, the condensate may flow through an outer
passageway 54 to a surface of steam turbine outside of blade ring
12.
[0029] In another path, condensate may enter a longitudinal
passageway 26 of a blade portion 16 below the rotor shaft of steam
turbine 10 and flow out through outer passageway 54 without first
travelling through the annular chamber 20 formed by through holes
42.
[0030] The removal of condensate from the wet steam progressing
through the latter stages of steam turbine 10 may prevent damage to
the stator blade ring 12 as well as to the turbine blades 16 and
other downstream components of steam turbine 10. Moreover, stator
blade ring 12 allows for the collection of condensate which may
include residual heat for use in other processes.
[0031] Some blade modules, for example, blade modules above the
rotor shaft of steam turbine 10, may be provided without an outer
passageway 54, for example, to reduce manufacturing costs, since
the downward flow of condensate may obviate the need for outer
passageways 54 in blade modules 14 above the rotor shaft. Further,
some blade modules 14 may be provided with blade portions 16
without slots, for example, to further reduce manufacturing costs.
Alternatively, and as shown in the embodiment of FIGS. 2-3 and
5-10, each of the blade modules 14 may be identical to one another.
This feature provides a number of benefits. For example, the
manufacturing process is rendered more uniform. Also, servicing of
steam turbine 10 is also more convenient in that, during repair or
replacement of a single blade module 14 which is made possible by
the exemplary embodiment, only a single part number is necessary
since all blade modules 14 are identical within the stator blade
ring 12.
[0032] In addition to providing cost savings over stator blade
diaphragms which may need to be serviced or replaced as a unit,
blade modules 14 provide a simple one piece design which is easier
to install and/or replace than conventional stator blade diaphragm
rings. As shown in FIGS. 2, 3 and 8 to 10, the outer portion 52 of
each stator blade module 14 is engaged directly to steam turbine
10. Specifically, each outer portion 52 includes an upstream groove
56 and a downstream groove 58. Steam turbine 10 includes an
upstream ridge 62 engaging groove 56 and a downstream ridge 64
engaging groove 58. Groove 56 is offset closer to inner portion 38
than groove 58. The offset between grooves 56 and 58 may allow each
stator blade module to better conform to the desired flow path of
the steam through steam turbine 10, and may also prevent a
technician from inadvertently installing a blade module 14 in an
improper orientation during construction or servicing of stator
blade ring 12.
[0033] As shown in FIGS. 2 and 3, outer passageway 54 opens to a
surface of steam turbine 10 between ridge 62 and ridge 64. Note
that a chamber 76 is formed between the outer surface of blade ring
12 and the surface of steam turbine 10. Chamber 76 may facilitate
convenient collection of condensate which flows out of outer
passageways 54.
[0034] A groove 66 in each inner portion 38 forms a continuous
circumferential groove facing a center of stator blade ring 12, as
shown in FIGS. 2, 3, and 5-7. As shown in FIG. 3, each groove 66 is
engaged by a metal ring 68 which locks the stator blade modules 14
together.
[0035] As further shown in FIGS. 2, 3 and 5 to 7, the inner portion
38 of each stator blade module 14 defines an inner brazing platform
72 surrounding the first longitudinal end of each blade portion 16.
Also, as shown in FIGS. 2, 3 and 8 to 10, the outer portion 52 of
each stator blade module defines an outer brazing platform 74
surrounding the second longitudinal end of each blade portion
16.
[0036] Brazing platform 72 and brazing platform 74 provide a
convenient surface for brazing the longitudinal ends of each blade
portion 16 as well as defining a portion of a stage and/or steam
flow path within steam turbine 10. Note from FIGS. 2 and 3 that the
brazing platform 74 of each outer portion 52 transitions evenly to
the surrounding surfaces of steam turbine 10.
[0037] In the embodiment of FIGS. 2 to 4, blade shell portion 18
may be vacuum brazed to blade shell portion 22. The first and
second longitudinal ends of the resulting blade portion 16 may then
be vacuum brazed to the inner portion 38 and outer portion 52 of
each stator blade module 14. The vacuum brazing equipment used to
perform the vacuum brazing of diaphragm 14 can be standard vacuum
brazing equipment as, for example, disclosed in U.S. Pat. Nos.
4,874,918 and 4,401,254, the disclosures of which are incorporated
here by reference.
[0038] Thus, according to an exemplary embodiment shown in FIG. 11,
there is provided a method 1000 of making a blade module for a
stator blade ring, the blade module including an elongated blade
portion, an inner portion, and an outer portion, wherein the method
1000 comprises brazing 1002 first and second edges of a first blade
shell portion to first and second edges of a second blade shell
portion to form a longitudinal passageway in the elongated blade
portion, forming 1004 a through hole in the inner portion, forming
1006 an inner passageway in the inner portion extending from a
surface of the inner portion to the through hole, brazing 1008 a
first longitudinal end of the blade portion to the surface of the
inner portion such that the longitudinal passageway is open to the
inner passageway, forming 1010 an outer passageway in the outer
portion extending from a first surface to a second surface of the
outer portion, and brazing 1012 a second longitudinal end of the
blade portion to the first surface of the outer portion such that
the longitudinal passageway is open to the outer passageway.
[0039] The above-described exemplary embodiments are intended to be
illustrative in all respects, rather than restrictive, of the
present invention. Thus the present invention is capable of many
variations in detailed implementation that can be derived from the
description contained herein by a person skilled in the art. All
such variations and modifications are considered to be within the
scope and spirit of the present invention as defined by the
following claims. No element, act, or instruction used in the
description of the present application should be construed as
critical or essential to the invention unless explicitly described
as such. Also, as used herein, the article "a" is intended to
include one or more items.
* * * * *