EP0566478A1 - High pressure steam turbine casing - Google Patents

Abstract

HP turbine module with rotor wheel with intake of steam with very high characteristics including zones of different designs adapated to the pressure and temperature levels. - Zone A located on the steam intake side includes an assembly consisting of rotor (1), diaphragms (8), internal spool (18), and intake packing carriers (14) which are perfectly isotropic, without a break in the horizontal seal. - The zone P located on the exhaust side where the internal spool (19), produced in two parts, is coupled to the internal spool (18) of the zone A. The internal spool (19) of the zone P may be isotropic and shrunk-on or nonisotropic or bolted. In the zone A the fins (3) are mounted either in axial grooves (31) or in circumferental grooves, while in the zone P, for simplification, the grooves (16) are chosen to be circumferential. Advantage: transverse decrease in the module owing: - to the rotor wheel (1), - to the isotropic front internal spool (18), - to the elimination of the third casing on the intake side. <IMAGE>

Description

The present invention relates to improvements to the high pressure turbine modules comprising an inlet for very high characteristics steam, a steam exhaust, a rotor supporting moving wheels constituted by movable fins and stator parts comprising an external body and a internal body supporting fixed stages arranged between the movable wheels, the internal body being provided on the intake side with a gasket holder ensuring the tightness of the intake steam.

The high pressure stator parts of the steam turbines comprise, in addition to the two envelopes formed by the internal body and the external body, a third envelope at the inlet when the pressures and temperatures are very high.

Thanks to this multiplicity of envelopes it is possible to reduce the pressure and temperature difference between them.

In addition, the internal and external bodies are in two parts and are provided with flanges in the horizontal joint plane to allow bolting.

• - à une augmentation des dimensions transversales des enveloppes du stator
• - à une non isotropie de ces mêmes enveloppes.

The multiplication of envelopes, the presence of a flange at the horizontal joint for bolting the bodies lead to:

• - an increase in the transverse dimensions of the stator casings
• - non-isotropy of these same envelopes.

This causes an increase in forces and affects the mechanical and thermal behavior of the envelopes and the bolts.

This problem is critical in the intake area where the pressure and temperature are very high.

Furthermore, in the case of steam turbines with action, the rotor is provided with discs supporting the movable fins, which results in a significant increase in the transverse dimensions of the finned rotor and consequently in the stator parts.

The turbine module according to the invention of simplified design and whose dimensions have been reduced while ensuring good mechanical and thermal behavior is characterized in that the internal body comprises two bodies coupled together, an anterior body arranged on the side of the intake and a rear body disposed on the exhaust side, the front body being in one piece and surrounding a rotor part which is a drum rotor provided with grooves in which the feet of the fins are fixed.

By separating the internal body into two anterior and posterior parts, each of the parts can be adapted to the characteristics of the vapor.

The front part in which the temperature and the pressure of the vapor are very high has an internal casing and a gasket holder for the isotropic intake therefore without bolting.

This arrangement also has the effect of reducing the radial and transverse dimensions since it eliminates the thickness of the flange necessary for bolting.

On the other hand the use of a drum rotor (therefore without discs) inside the anterior internal body makes it possible to reduce the radial dimension of the vein and correlatively that of the envelopes. In addition, this reduction in the radial dimension of the vein is favorable to efficiency, in particular for action turbines.

Finally, the body has only two envelopes on admission, an external body and an internal body.

This makes it possible to further reduce the transverse dimensions.

Note that the third casing, which may sometimes be necessary for partial injection operating questions, is not necessary in the case of supercritical turbines (250 bars, 565 ° C) or with even higher characteristics (350 bars, 580 ° C) which operate with full sliding pressure injection.

According to a preferred embodiment of the invention, the grooves of the drum rotor located in the region of the anterior internal body are longitudinal and the movable wheels are separated by spacers of the same shape as the feet of the fins slid in the longitudinal grooves and facing the stages. fixed which consist of monoblock diaphragms.

As regards the part of the rotor situated in the zone of the posterior internal body, this can be of conventional construction with discs for the turbines with action for carrying the movable fins which has the advantage of having a number of 'floors limited.

This rotor part can also be drum rotor with circumferential grooves which brings the indicated advantages of the drum rotor.

A drum rotor HP module is described in French patent application No. FR-9104855 in the name of the applicant.

The posterior internal body for reasons of simplification is in two parts which can be either bolted or shrunk.

• La figure 1 représente une demi-coupe longitudinale d'un module HP de turbine à action classique.
• La figure 2 représente en demi-coupe radiale le module de la figure 1.
• La figure 3 représente en demi-coupe longitudinale une première réalisation du module de turbine selon l'invention.
• La figure 4 représente une coupe longitudinale d'une variante de la figure 3.
• La figure 5 représente une coupe radiale de la figure 4.
• La figure 6 représente une seconde réalisation du module de turbine selon l'invention.
• La figure 7 représente une coupe d'une roue mobile du module de la figure 6.
• La figure 8 représente une coupe d'un diaphragme du module de la figure 6.
• La figure 9 représente le montage circonférentiel des ailettes.
• Les figures 10, 12, 14 représentent les trois étapes du montage du module de la figure 3.
• Les figures 11, 13, 15 représentent les trois étapes du montage du module de la figure 6.
• La figure 16 représente une troisième réalisation du module de turbine selon l'invention.
• La figure 17 est une vue détaillée de la partie antérieure de la figure 3.
• La figure 18 est une vue détaillée de la partie antérieure de la figure 6.
• La figure 19 est une variante de la partie postérieure du rotor des figures 3 et 6.
• La figure 20 représente la climatisation des modules des figures 3 et 6.

The invention will now be described in more detail with reference to particular embodiments cited by way of example and represented in FIGS. 3 to 20.

• FIG. 1 represents a longitudinal half-section of a HP module of a conventional action turbine.
• FIG. 2 represents in radial half-section the module of FIG. 1.
• Figure 3 shows in longitudinal half-section a first embodiment of the turbine module according to the invention.
• FIG. 4 represents a longitudinal section of a variant of FIG. 3.
• Figure 5 shows a radial section of the fi gure 4.
• FIG. 6 represents a second embodiment of the turbine module according to the invention.
• FIG. 7 represents a section of a movable wheel of the module of FIG. 6.
• FIG. 8 represents a section of a diaphragm of the module of FIG. 6.
• Figure 9 shows the circumferential mounting of the fins.
• Figures 10, 12, 14 show the three stages of mounting the module in Figure 3.
• Figures 11, 13, 15 represent the three stages of mounting the module of Figure 6.
• FIG. 16 represents a third embodiment of the turbine module according to the invention.
• FIG. 17 is a detailed view of the front part of FIG. 3.
• FIG. 18 is a detailed view of the front part of FIG. 6.
• FIG. 19 is a variant of the rear part of the rotor of FIGS. 3 and 6.
• FIG. 20 represents the air conditioning of the modules of FIGS. 3 and 6.

The conventional action turbine HP module (FIG. 1) comprises a rotor 1 provided with discs 2 supporting movable fins 3 constituting movable wheels 4 and stator parts 5. The stator parts 5 comprise an external body 6 in two parts bolted in the horizontal joint plane and an internal body 7 supported by the external body 6 which is also in two parts bolted in the joint plane. In the internal body 7 are mounted diaphragms 8 also in two parts comprising fixed guide vanes 9 of the vein 10. Each diaphragm 8 constitutes the fixed part of a stage 40 with the movable wheel 4 which follows it.

The diaphragms 8 produced in two parts to allow their mounting are the seat of different stresses and deformations depending on the azimuth considered. They must be axially oversized, especially for the first floors, so as to take this cut at the horizontal joint into account.

The module comprises intake pipes 11 opening into an internal envelope 12 inside the internal body serving for the distribution of the vapor in the stream 10 which ends in the exhaust 13.

This envelope 12 can be produced in different ways. It can be produced in two parts plugged at the joint and assembled by bolting or it can consist of several nozzle holders for injecting the steam fixed to the internal body 7.

On the internal body 7 around the rotor 1 on the intake side is mounted at free expansion, a packing holder 14 made in two parts and bolted. It is provided with seals 15 ensuring the seal between the internal body 7 and the rotor 1 on the intake side.

A first embodiment of the action turbine module is shown in FIG. 3.

The rotor 1 of the module is a drum rotor, that is to say without discs. It is provided with circumferential grooves 16 in which the feet 17 of the moving fins 3 are housed. Such a rotor is described in application FR-A-9104855 in the name of the applicant.

The external body 6 of the stator parts 5 of the module is of conventional construction and has two bolted parts.

The internal body 7 of the stator parts is separated into two coupled bodies, an anterior body 18 on the intake side arranged in the anterior zone (zone A) and a posterior body 19 on the side of the exhaust 13 in the posterior zone (zone P).

The front body 18 is in one piece, that is to say without radial cut, therefore perfectly isotropic. It comprises two half-rings 20 provided with grooves 21 in which guide vanes 9 are slipped individually, each set of guide vanes 9 with the movable wheel 4 which follows it constitutes a stage 40.

The front body 18 surrounds a gasket holder 14 mounted at free expansion which comprises a monobloc external tube 22 ', that is to say without radial cut therefore perfectly isotropic which comes to hoop two half-crowns 22 in which retractable gaskets are mounted 15 each making a half-circumference. There can of course be several seals 15 in series. These linings 15 seal the rotor shaft 1.

If one does not wish to use retractable linings 15, the lining carrier 14 with free expansion no longer has half-crowns and is completely in one piece.

The posterior body 19 is made in two parts and coupled to the anterior body 18. It is isotropic and hooped by hoops 39. In this design the hooping is total and easy to perform since the posterior internal body is entirely cylindrical and does not include the steam admissions.

As the posterior body 19 is isotropic, the fixed parts of the vein 10 are guide vanes 9 mounted full hole in the unit at the cut of the horizontal joint in the grooves 23 of the internal body.

This rear body 19 has a front face 24 located at the border between the zones A and P against which all of the half-crowns 20 of the zone A comes to bear.

The front face 24 is extended by a circular rim 25, which is received in a groove 26 formed in the periphery of the front body 18, thus coupling the two bodies 18, 19 together.

The half-rings 20 (FIG. 17) comprise for each stage 40 a sealing segment 41 to prevent or slow down the flow of vapor in the annular space between the ring 20 and the anterior body. This possible leak is immediately recovered on the next floor by holes 42 so as to be sure to have the temperature of the last stage of zone A on the front face 24.

If zone A has too large a number of stages 40 (see FIGS. 4 and 5), provision is made to introduce an intermediate support 27 produced by a ring 28 comprising several sectors which are pushed from outside the front body 18 towards the inside of the latter, the sectors then being astride a circumferential groove 29 formed inside the front body 18 and on a groove 30 formed on the outside of the half-rings 20.

According to a variant of the invention (see fig. 6) zone A comprises a drum rotor 1 whose grooves 31 are longitudinal.

In this design, as in action turbines, as single parts of stages 40, diaphragms 8 are used in one piece without cutting at the horizontal joint, therefore perfectly isotropic and of reduced axial dimensions.

The fins 3 are mounted axially on the rotor 1 in the grooves 31; spacers 32 carrying the seals with respect to the diaphragms fill the groove between the movable wheels 4. This allows the assembly of the monobloc diaphragms 8 following each movable wheel 4 and spacer 32.

A spacer 33 at the end situated under the intake lining holder 14 blocks the fin-spacer assembly in the axial direction by means of a crown 34 screwed onto the rotor.

In Figure 7 there is shown a section aa of a movable wheel 4 of the area A.

The feet 17 of the fins 3 have at the base a development and are exactly complementary to the longitudinal grooves 31.

The feet 17 of the fins 3 of the same movable wheel 4 are joined above the grooves 31 and the caps 35 of the same wheel 4 are mounted in contact with each other.

Between two movable wheels 4 of fins 3 the spacers 32 have been slid, which have the same shape as the feet 17 of the fins 3 in each groove (see FIG. 8).

The spacers 32 can be separated or joined in packs of three, four or five. These spacers 32 or packets of spacers are in contact with each other above the grooves 31.

The spacers 32 carry the seals 36 opposite the hubs 37 of the diaphragms 8.

Each diaphragm 8 of zone A (see fig. 18) has for each stage 40 a sealing segment 41 to prevent or slow down the flow of vapor in the annular space between the diaphragm 8 and the anterior body 18. This possible leak is immediately retrieved on the next floor by grooves 43 so as to be sure of having the temperature of the last stage of zone A on the front face 24 (see fig. 18).

An action turbine with drum rotor having longitudinal grooves is described in application FR-A-9200948 filed on January 29, 1992 in the name of the applicant.

The posterior body 19 is constituted like that of FIG. 3 except that instead of being shrunk it is bolted therefore not isotropic.

The diaphragms 8 constituting the fixed parts of the vein 10 are produced in two parts and mounted at free expansion. This arrangement makes it possible to better conserve the radial rotor / stator clearances when the latter is not isotropic.

We will now describe the assemblies of zones A and P for the modules of Figures 3 and 6.

1 - Assembly of fins and fixed parts of the stages ZONE A

Two cases arise depending on whether the grooves of the drum rotor are circumferential or axial.

A - Case of circumferential mounting of the fins (Figure 3)

The movable fins 3 have a foot 17 in the shape of an inverted T. The foot 17 of the fin 3 is introduced into the circumferential groove 16 in the form of an inverted T then pivots. When all the fins 3 are in place shims 38 are introduced having the same section as the foot 17 of the fins 3 but much thinner (see FIG. 9). The last wedges 38 are cut in two in the height direction to be able to be introduced and the last in three.

In the general case there remains a play between the hats. Then the fixed vanes 9 are mounted in the half-rings 20 and then these half-rings 20 are mounted around the finned rotor 1 and while temporarily holding them by screws before mounting in the front body 18. (see FIG. 10).

B - Case of the axial mounting of the fins (figure 6)

Each movable wheel 4 is assembled in its entirety with its own clamping on the rotor 1 by sliding it axially, there is mounted between each movable wheel 4 the spacers 32 in the longitudinal grooves 31 and the monoblock diaphragms 8 (see FIGS. 7 and 8).

We end with the end spacer 33 and the crown 34 screwed onto the rotor 1 (see Figure 11).

ZONE P - see figures 3 and 6)

In zone P, a circumferential mounting of the fins 3 has been chosen, the grooves 16 of the drum rotor 1 in this zone are therefore circumferential.

An axial mounting of the fins in this area would have been possible but in fact more complex.

The assembly takes place as indicated above (see figure 9).

In zone P, two embodiments can be provided as described for the fixed parts of the stream 10, depending on whether the rear body 19 is bolted or shrunk and the mounting of the fixed stages will be different as indicated below for the mounting of the stators.

One can provide for the last movable wheel 4 of the rotor 1 (therefore on the exhaust side) an axial mounting in grooves 31 '(see fig. 19) which improves the vibration problems.

2 - Assembly of the stators ZONE A - (see figures 12, 13)

In zone A, the mounting of the internal body 18 and of the packing holder 14 are identical whatever the principle of fitting the fin (axial or circumferential).

It was said that these two parts were isotropic and without radial cut.

The fins 4 and the diaphragms 8 or guide vanes 9 of the zone A are mounted on the rotor 1 as seen previously.

The lining holder 22 ′ which has an outer tube fringing two half-rings 22 carrying the retractable linings 15 is threaded and centered on the internal body 18 by keys external to the internal body 18.

This assembly is then threaded onto the rotor 1 on the intake side.

The diaphragms 8 (fig.13) or the crown 20 carrying the guidelines 9 (fig.12) are then centered on the outside of the anterior body 18 by pins and are thus mounted at free expansion.

This type of mounting is necessary for the construction but taking into account the anterior isotropic body 18 is not necessary from the point of view of the design.

Note that if the lining holder 14 does not have retractable linings 15 it is entirely in one piece (fig.16).

ZONE P (Figures 3, 10, 12, 14) and (Figures 6, 11, 13, 15).

The lower anterior half-body 18 comprising its half-diaphragms 8 (fig. 6) or the guide lines 9 (fig. 3) is in place in the lower external half-body 6.

• - rotor 1 en appui sur ses coussinets
• - corps antérieur 18 en appui dans le corps externe 6 côté admission et attelé au demi-corps postérieur 9.

The rotor assembly 1 front body 18 of zone A is mounted in the lower external body 6, taking the following precautions:

• - rotor 1 resting on its bearings
• - front body 18 resting in the external body 6 on the intake side and coupled to the rear half-body 9.

We then cap this assembly by the upper posterior half-body which includes its half-diaphragms 8 (fig.6) or its directors 9 (fig.3).

We bolt (fig.15) or hoop (fig.14) the upper posterior half-body 2 according to the chosen design.

The upper external half-body is then mounted and bolted.

As a variant for action steam turbines, it is possible for zone P to take a rotor 1 with discs 2 which is entirely conventional.

This arrangement makes it possible to reduce the number of stages 4, 8 of zone P.

On the other hand, of course, the rotor of zone A is a drum rotor with axial or circumferential mounting; in Figure 16 the fins 3 are shown in axial mounting.

On the other hand, the rear body 19 of zone P can be, as for zone P of the modules already described, either bolted or shrunk.

It is possible to provide (see FIG. 20) for a sweep by cold vapor of the interstatoric space 44. To this end, samples are taken from one of the last stages 40 of the zone P by slots 45.

The leaks of hot steam having passed through the linings 25 are taken from the front of the lining holder 14 by slots 46 formed in this lining holder.

The slots 46 are continued by slots 47 passing through the one-piece anterior body 18 and by conduits 48 crossing the interstatoric space and supplying slots 49 to a stage in zone P, thus preventing the escape of hot steam from the front part of the anterior body and in addition we work the hot steam that escapes. It is possible to adjust by means 50, a leak of cold vapor outside the interstatoric space 44, which makes it possible to regulate the temperature of this space and possibly cool the rotor of another module (MP for example) .

Claims (13)

1 / High pressure turbine module comprising an inlet (11) for steam with very high characteristics, an exhaust (13) of steam, a rotor (1) supporting movable wheels (4) consisting of movable fins (3) and stator parts (5) comprising an external body (6) and an internal body (7, 18, 19) supporting fixed parts (8, 9) constituting with the movable wheels (4) stages (40), the body internal (7, 18, 19) being provided on the intake side (11) with a seal carrier (14) surrounding the rotor (1) and independent of the internal body (7, 18, 19), characterized in that the body internal (18,19) has two bodies coupled together, an anterior body (18) dis placed on the intake side (11) and a rear body (19) disposed on the exhaust side (13), the front body (18) being in one piece and surrounding a rotor part (1) which is a drum rotor provided with grooves (16, 31) in which the feet (17) of the fins (3) are fixed. 2 / high pressure turbine module according to claim 1, characterized in that the packing holder (14) is in one piece. 3 / high pressure turbine module according to claim 1, characterized in that the lining holder (14) comprises an external tube (22 ') in one piece enclosing two half-rings (22) each carrying one or more retractable linings (15 ). 4 / high pressure turbine module according to one of the preceding claims characterized in that the turbine is active, in that the grooves (31) of the drum rotor (1) located in the area of the front internal body (18) are longitudinal and in that the movable wheels (4) are separated by spacers (32) of the same shape as the feet (17) of the fins (3) slid in the longitudinal grooves (31) and facing the fixed stages which are formed monoblock diaphragms (8). 5 / high pressure action turbine module according to claim 4, characterized in that each diaphragm (8) of a stage (40) is provided with a sealing segment (41) ensuring the sealing between said diaphragm ( 8) and the front body (18) and in that said diaphragm (8) is provided with a groove (43) ensuring the sending of steam which could leak into the next stage (40). 6 / high pressure turbine module according to one of claims 1 to 3, characterized in that the grooves (16) of the drum rotor surrounded by the front internal body (18) are circumferential and in that the front internal body (18 ) encloses one or two pairs of half-rings (20) in which are mounted independent guide vanes (9) constituting the fixed parts of the stages (40). 7 / high pressure turbine module according to claim 6, characterized in that the half-rings (20) for each stage (40) are provided with sealing segments (41) ensuring the sealing between said half-rings (20 ) and the front body (18) and in that said half-rings (20) are provided with holes (42) ensuring the sending of steam which could leak into the next stage (40). 8 / high pressure turbine module according to one of the preceding claims characterized in that the part of the rotor (1) surrounded by the rear internal body (19) is a drum rotor provided with circumferential grooves (16) in which are housed the feet (17) of the movable fins (3) constituting the movable wheels (4). 9 / high pressure turbine module according to claim 6, characterized in that the last movable wheel (4) of the part of the rotor (1) surrounded by the rear internal body (19) which is a drum rotor is mounted in grooves longitudinal (31 ') formed in said rotor (1). 10 / high pressure turbine module according to one of claims 1 to 7, characterized in that the turbine is acting and in that the part of the rotor located in the region of the posterior internal body (19) is provided with discs ( 2) on which are mounted the movable fins (3) constituting the movable wheels (4). 11 / high pressure turbine module according to one of claims 8 to 10, characterized in that the rear internal body (19) consists of two parts bolted in the joint plane in which are mounted freely expanding diaphragms (8 ) made in two parts constituting the fixed floors. 12 / high pressure turbine module according to one of claims 8 to 10, characterized in that the rear internal body (9) consists of two hooped parts in which are fixed vanes (9) constituting the fixed stages. 13 / High pressure turbine module according to one of the preceding claims, characterized in that it comprises means (46, 47) for sampling hot steam leaks escaping from the packing holder (14) and means for injection (48,49) of this hot vapor inside the posterior body (19) and means (44) for drawing relatively cold vapor inside the posterior body (19) to inject it into the interstatoric space (44) located between internal body (18) and rear (19) on the one hand and external body (6), said cold vapor can be used to cool the rotor of another module.

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