(19)
(11)EP 3 260 663 B1

(12)EUROPEAN PATENT SPECIFICATION

(45)Mention of the grant of the patent:
29.07.2020 Bulletin 2020/31

(21)Application number: 16290110.2

(22)Date of filing:  21.06.2016
(51)International Patent Classification (IPC): 
F01D 9/04(2006.01)
B23P 15/04(2006.01)

(54)

AXIAL FLOW TURBINE DIAPHRAGM CONSTRUCTION

AXIALTURBINENLEITKRANZKONSTRUKTION

STRUCTURE DE DIAPHRAGME DE TURBINE AXIALE


(84)Designated Contracting States:
AL AT BE BG CH CY CZ DE DK EE ES FI FR GB GR HR HU IE IS IT LI LT LU LV MC MK MT NL NO PL PT RO RS SE SI SK SM TR

(43)Date of publication of application:
27.12.2017 Bulletin 2017/52

(73)Proprietor: General Electric Technology GmbH
5400 Baden (CH)

(72)Inventors:
  • Lemaire, Julien
    Levallois-Perret 92300 (FR)
  • Buguin, Arnaud
    Boulogne Billancourt 92100 (FR)

(74)Representative: BRP Renaud & Partner mbB Rechtsanwälte Patentanwälte Steuerberater 
Königstraße 28
70173 Stuttgart
70173 Stuttgart (DE)


(56)References cited: : 
EP-A1- 0 018 806
US-A- 5 474 419
EP-A2- 1 847 689
US-A1- 2007 224 043
  
      
    Note: Within nine months from the publication of the mention of the grant of the European patent, any person may give notice to the European Patent Office of opposition to the European patent granted. Notice of opposition shall be filed in a written reasoned statement. It shall not be deemed to have been filed until the opposition fee has been paid. (Art. 99(1) European Patent Convention).


    Description

    TECHNICAL FIELD



    [0001] The present invention relates to the construction of rings of static blades for axial flow turbines, and in particular, steam turbines.

    [0002] In particular, the present invention relates to turbine diaphragms.

    BACKGROUND ART



    [0003] A steam turbine is a rotating machine intended to convert the thermal of the steam into mechanical energy for driving an alternator, a pump or any other rotary mechanical receiver. Generally, steam turbines comprise a high-pressure module, a medium-pressure module and a low-pressure module.

    [0004] A steam turbine generally comprises symmetrical or non-symmetrical single or double flow inner body enclosing a rotor equipped with mobile blades and supporting fixed or stationary blades forming a diaphragm suspended in said inner body. The diaphragms are adapted to guide the flow of steam in a specific direction towards the mobile blades of the rotor, thereby accelerating the steam flow.

    [0005] The present invention is related to known types of construction diaphragms called "spacer band diaphragms" and "platform diaphragms", as exemplary described in EP 1 847 689 A2, related to an apparatus and a method of diaphragm assembly, EP 0 018 806 A1, related to an assembly including an airfoil extending between shroud sections and method of making the same, US 5,474,419 A related to a flowpath assembly for a turbine diaphragm and methods of manufacture, and US 2007/224043 related to a turbine blade and diaphragm construction.

    [0006] In the so called "spacer band diaphragm" type of construction 10, shown in Figure 1a, the blade aerofoils 11 are fixed radially to an inner ring 12 and to an outer ring 13 by means of inner and outer annular bands 14, 15, which are folded from flat strip. Through-holes 16 are cut in said bands 14, 15, for example by means of laser, to match the cross-section of the aerofoil shape. The ends of the aerofoils 11 are then inserted in said through-holes 16 and fillet welded into place. The inner band 14 is in turn welded to the inner ring 12 and the outer band 15 is in turn welded to the outer ring 13. Such type of construction involves a relatively small amount of machining of the blades compared to other types of construction used in steam turbines.

    [0007] For example, in the so called "platform diaphragms" type of construction 20, shown in Figure 1b, the blade aerofoils 21 has a section substantially in the shape of a vane having its two opposite ends integral with radially inner and outer platforms 22, 23. The blade aerofoils and the platforms are machined from solid bars or by forgings. A complete annulus of static blades is built up by assembling successive combined aerofoil-platforms components between an inner and an outer ring (not shown) and by welding the platforms to said rings. Thanks to the platforms, such diaphragm has better mechanical strength compared to the spacer band type, but has much higher manufacturing costs.

    [0008] The object of the present invention is to remedy the above drawbacks.

    DISCLOSURE OF THE INVENTION



    [0009] It is a particular object of the present invention to provide a type of diaphragm construction which has good performance characteristics as well as being economical to manufacture.

    [0010] In one embodiment, an axial flow turbine diaphragm construction according to claim 1 is provided.

    [0011] Thanks to the reinforcement portion, the mechanical strength of the spacer band diaphragm is increased without increasing the manufacturing costs. The section of the reinforcement portion preferably has a rounded and enlarged shape corresponding to the leading edge surrounding the leading edge of the aerofoil portion and a thinner part corresponding to the trailing edge surrounding the trailing edge of the aerofoil portion.

    [0012] The static blade may be made of an alloy steel material, for example, comprising 12% of chrome.

    [0013] In an embodiment, each reinforcement portions are welded to the corresponding spacer band by welds.

    [0014] The welds are, for example, located at each leading and trailing edges of each reinforcement portions.

    [0015] In an embodiment, the inner spacer band is welded to the inner ring and the outer spacer band is welded to the outer ring.

    DESCRIPTION OF THE FIGURES



    [0016] The present invention will be better understood from studying the detailed description of a number of embodiments considered by way of entirely non-limiting examples and illustrated by the attached drawings in which:
    • Figure 1a illustrates the known spacer band turbine diaphragm type of construction;
    • Figure 1b illustrates a fixed blade with integral platforms for use in the known platform turbine diaphragm type of construction;
    • Figure 2 is a three-dimensional perspective view of a part of a steam turbine diaphragm according to an embodiment of the invention;
    • Figure 3 is a three-dimensional perspective view of a static blade for use in the diaphragm construction of Figure 2;
    • Figure 4 is an upper view of the static blade of Figure 3; and
    • Figure 5 is a radial cross-section of a static blade of Figure 3, welded onto spacer bands of the steam turbine diaphragm of Figure 2.

    DETAILED DESCRIPTION



    [0017] The following detailed description of the embodiments refers to the accompanying drawings. The same reference numbers in different drawings identify the same or similar elements. Additionally, the drawings are not necessarily drawn to scale. As illustrated on Figure 2, a part of a steam turbine diaphragm 30 of a turbine comprises a nozzle unit having a plurality of identical static blade aerofoils 32 fixed radially to an inner ring 34 and to an outer ring 36 by means of inner and outer annular spacer bands 38, 40, which are folded from flat strip.

    [0018] The inner and outer rings 34, 36, as well as the inner and outer spacer bands 38, 40 are concentric.

    [0019] The inner and the outer spacer bands 38, 40 are each provided with through-holes 38a, 40a. As illustrated, the through-holes are open at both ends to receive the static blades. The through-holes 38a, 40a may be, for example, cut in said spacer bands 38, 40, for example by means of laser, to match the cross-section of the aerofoil shape. The ends of the aerofoils 32 are then inserted in said though-holes and fillet welded into place. The inner spacer band 38 is in turn welded to the inner ring 34 and the outer band 40 is in turn welded to the outer ring 36.

    [0020] As illustrated on Figures 3 and 4, each static blade 32 has an aerofoil portion 44 having an elongated body having an inner end 32a brought into contact with the inner spacer band 38 and an outer end 32b, opposite to said inner end 32a, brought into contact with the outer spacer band 40.

    [0021] The inner and outer ends 32a, 32b are connected respectively to the inner and outer spacer bands 38, 40 by welding by way of a weld bead arranged between said ends and said spacer bands. In this way each static blade is welded both to the inner spacer band and to the outer spacer band.

    [0022] Each static blade 32 has, for example, a section substantially in the shape of a vane, as shown on Figure 4, having a rounded and enlarged shape corresponding to the leading edge 44a and a thinner part corresponding to the trailing edge 44b.

    [0023] As illustrated on Figure 3 and 4, the inner and outer ends 32a, 32b of the each static blade 32 are provided respectively with an inner and outer reinforcement portion 46, 48. Each reinforcement portion 46, 48 has a section slightly bigger than the section of the aerofoil portion 44, as shown on Figure 4, having a rounded and enlarged shape corresponding to the leading edge 46a, 48a and a thinner part corresponding to the trailing edge 46b, 48b.

    [0024] Each reinforcement portion 46, 48 surrounds the periphery of the whole section of the corresponding end so as to have a section substantially bigger than the section of the aerofoil portion 44. The shape of the reinforcement portions 46, 48 thus approximates the shape of the section of the aerofoil portion 44 in its whole, i.e at and near the leading and trailing edges 44a, 44b, as well as the suction side and the pressure side of the aerofoil portion 44.

    [0025] The first and second reinforcement portions 46, 48 are slid into their matching through-holes 38a, 40a of the spacer bands 38, 40 as shown on Figure 5. Once all the static blades 32 have been assembled into the spacer bands 38, 40, they must be securely welded into position. Each leading and trailing edges of each reinforcement portions are welded to the corresponding spacer band by welds 50a, 50b and 52a, 52b. The welds 50a, 50b and 52a, 52b are shown in hatched lines on Figure 4.

    [0026] The static blades 32 are made of an alloy steel material, having for example, 12% of chrome.

    [0027] Thanks to the reinforcement portions provided at each end of the aerofoil portions, the static blade is strengthen.

    [0028] Thanks to the invention, the diaphragm construction has good mechanical strength, while being economical and easy to manufacture.


    Claims

    1. An axial flow turbine diaphragm construction comprising:

    a) an annulus of a plurality of identical static blades (32), each blade comprising:

    i) an aerofoil portion (44) having a leading edge (44a), a trailing edge (44b), a pressure side and a suction side,

    ii) inner and outer ends (32a, 32b) of each static blade are provided respectively with an inner and outer reinforcement portion (46, 48) integral with said aerofoil portion (44),

    characterized in that

    (1) a shape of the reinforcement portions (46, 48) approximates a shape of a section of the aerofoil portion (44) in its whole, i.e. at and near the leading and trailing edges (44a, 44b) as well as the suction side and the pressure side of the aerofoil portion (44), and wherein

    (2) each reinforcement portion (46, 48) surrounds the periphery of the whole section of the corresponding end so as to have a section bigger than the section of the aerofoil portion (44);

    b) an inner and outer spacer bands (38, 40) having through-holes (38a, 40a) therein shaped to receive the inner and outer reinforcement portions (46, 48) of each static blade (32); and

    c) a radially inner and outer diaphragm rings (34, 36) surrounding the annular spacer bands (38, 40).


     
    2. Axial flow turbine diaphragm construction according to claim 1, wherein each reinforcement portions are welded to the corresponding spacer band (38, 40) by welds (50a, 50b; 52a, 52b).
     
    3. Axial flow turbine diaphragm construction according to any preceding claim, wherein the welds (50a, 50b; 52a, 52b) are located at each leading and trailing edge (48a, 48b; 46a, 46b) of each reinforcement portion (46, 48).
     
    4. Axial flow turbine diaphragm construction according to any preceding claim, wherein the inner spacer band (38) is welded to the inner ring (34) and the outer spacer band (40) is welded to the outer ring (36).
     
    5. Axial flow turbine diaphragm construction according to any preceding claim, wherein each reinforcement portion (46, 48) has a section substantially bigger than the section of the aerofoil portion (44), having a rounded and enlarged shape corresponding to the leading edge (46a, 48a) surrounding the leading edge (44a) of the aerofoil portion (44) and a thinner part corresponding to the trailing edge (46b, 48b) surrounding the trailing edge (44b) of the aerofoil portion (44).
     
    6. Axial flow turbine diaphragm construction according to any preceding claim, wherein each static blade is made of an alloy steel material.
     
    7. Axial flow turbine diaphragm construction according to the preceding claim, wherein the alloy steel material comprises 12% of chrome.
     


    Ansprüche

    1. Axialturbinentrennwandkonstruktion, umfassend:

    a) einen Ring aus einer Vielzahl identischer statischer Schaufeln (32), wobei jede Schaufel umfasst:

    i) einen Flügelabschnitt (44), der eine Vorderkante (44a), eine Hinterkante (44b), eine Druckseite und eine Saugseite aufweist,

    ii) innere und äußere Enden (32a, 32b) jeder statischen Schaufel sind jeweils mit einem inneren und äußeren Verstärkungsabschnitt (46, 48) bereitgestellt, die in den Flügelabschnitt (44) integriert sind,

    dadurch gekennzeichnet, dass

    (1) eine Form der Verstärkungsabschnitte (46, 48) in etwa einer Form eines Querschnitts des Flügelabschnitts (44) in seiner Gesamtheit entspricht, d. h. an und nahe der Vorder- und Hinterkante (44a, 44b) sowie der Saugseite und der Druckseite des Flügelabschnitts (44), und wobei

    (2) jeder Verstärkungsabschnitt (46, 48) den Umfang des gesamten Querschnitts des entsprechenden Endes umgibt, um einen größeren Querschnitt als den Querschnitt des Flügelabschnitts (44) aufzuweisen;

    b) ein inneres und äußeres Abstandshalterband (38, 40), das Durchgangsbohrungen (38a, 40a) darin aufweist, die ausgebildet sind, um die inneren und äußeren Verstärkungsabschnitte (46, 48) jeder statischen Schaufel (32) aufzunehmen; und

    c) einen radial inneren und äußeren Trennwandring (34, 36), die die ringförmigen Abstandshalterbänder (38, 40) umgeben.


     
    2. Axialturbinentrennwandkonstruktion nach Anspruch 1, wobei jeder Verstärkungsabschnitt durch Schweißnähte (50a, 50b; 52a, 52b) an das entsprechende Abstandshalterband (38, 40) geschweißt ist.
     
    3. Axialturbinentrennwandkonstruktion nach einem vorstehenden Anspruch, wobei die Schweißnähte (50a, 50b; 52a, 52b) an jeder Vorder- und Hinterkante (48a, 48b; 46a, 46b) jedes Verstärkungsabschnitts (46, 48) angeordnet sind.
     
    4. Axialturbinentrennwandkonstruktion nach einem vorstehenden Anspruch, wobei das innere Abstandshalterband (38) an den inneren Ring (34) und das äußere Abstandshalterband (40) an den äußeren Ring (36) geschweißt ist.
     
    5. Axialturbinentrennwandkonstruktion nach einem vorstehenden Anspruch, wobei jeder Verstärkungsabschnitt (46, 48) einen Querschnitt aufweist, der im Wesentlichen größer als der Querschnitt des Flügelabschnitts (44) ist, eine der Vorderkante (46a, 48a) entsprechende abgerundete und vergrößerte Form aufweist, die die Vorderkante (44a) des Flügelabschnitts (44) umgibt, und einen der Hinterkante (46b, 48b) entsprechenden dünneren Teil, der die Hinterkante (44b) des Flügelabschnitts (44) umgibt.
     
    6. Axialturbinentrennwandkonstruktion nach einem vorstehenden Anspruch, wobei jede statische Schaufel aus einem Stahllegierungsmaterial hergestellt ist.
     
    7. Axialturbinentrennwandkonstruktion nach dem vorstehenden Anspruch, wobei das Stahllegierungsmaterial zu 12 % Chrom umfasst.
     


    Revendications

    1. Construction de membrane de turbine à écoulement axial comprenant :

    a) un anneau d'une pluralité de lames (32) statiques identiques, chaque lame comprenant :

    i) une partie aérodynamique (44) ayant un bord d'attaque (44a), un bord de fuite (44b), un côté de pression et un côté d'aspiration,

    ii) des extrémités intérieure et extérieure (32a, 32b) de chaque lame statique sont pourvues respectivement d'une partie de renforcement intérieure et extérieure (46, 48) solidaire avec ladite partie aérodynamique (44),

    caractérisé en ce que

    (1) une forme des parties de renforcement (46, 48) ressemble à une forme d'une section de la partie aérodynamique (44) dans son ensemble, c'est-à-dire au niveau et à proximité des bords d'attaque et de fuite (44a, 44b) ainsi que du côté d'aspiration et du côté de pression de la partie aérodynamique (44), et dans laquelle

    (2) chaque partie de renforcement (46, 48) entoure la périphérie de toute la section de l'extrémité correspondante de manière à avoir une section plus grande que la section de la partie aérodynamique (44) ;

    b) des bandes d'espacement intérieure et extérieure (38, 40) ayant des trous de passage (38a, 40a) en leurs seins formés pour recevoir les parties de renforcement intérieure et extérieure (46, 48) de chaque lame statique (32) ; et

    c) des anneaux de membrane radialement intérieur et extérieur (34, 36) entourant les bandes d'espacement annulaires (38, 40).


     
    2. Construction de membrane de turbine à écoulement axial selon la revendication 1, dans laquelle chaque partie de renforcement est soudée à la bande d'espacement correspondante (38, 40) par des soudures (50a, 50b ; 52a, 52b).
     
    3. Construction de membrane de turbine à écoulement axial selon l'une quelconque des revendications précédentes, dans laquelle les soudures (50a, 50b ; 52a, 52b) sont situées au niveau de chaque bord d'attaque et de fuite (48a, 48b ; 46a, 46b) de chaque partie de renforcement (46, 48).
     
    4. Construction de membrane de turbine à écoulement axial selon l'une quelconque des revendications précédentes, dans laquelle la bande d'espacement intérieure (38) est soudée à l'anneau intérieur (34) et la bande d'espacement extérieure (40) est soudée à l'anneau extérieur (36).
     
    5. Construction de membrane de turbine à écoulement axial selon l'une quelconque des revendications précédentes, dans laquelle chaque partie de renforcement (46, 48) a une section sensiblement plus grande que la section de la partie aérodynamique (44), ayant une forme arrondie et élargie correspondant au bord d'attaque (46a, 48a) entourant le bord de fuite (44a) de la partie aérodynamique (44) et une partie plus fine correspondant au bord de fuite (46b, 48b) entourant le bord de fuite (44b) de la partie aérodynamique (44).
     
    6. Construction de membrane de turbine à écoulement axial selon l'une quelconque des revendications précédentes, dans laquelle chaque lame statique est fabriquée à partir d'un matériau d'alliage d'acier.
     
    7. Construction de membrane de turbine à écoulement axial selon la revendication précédente, dans laquelle le matériau d'alliage d'acier comprend 12 % de chrome.
     




    Drawing














    Cited references

    REFERENCES CITED IN THE DESCRIPTION



    This list of references cited by the applicant is for the reader's convenience only. It does not form part of the European patent document. Even though great care has been taken in compiling the references, errors or omissions cannot be excluded and the EPO disclaims all liability in this regard.

    Patent documents cited in the description