WO2019097058A1

WO2019097058A1 - Steam turbine

Info

Publication number: WO2019097058A1
Application number: PCT/EP2018/081803
Authority: WO
Inventors: Alexey Fishkin; Uwe Pfeifer; Mikhail Roshchin; Lucian-Mircea SASU; Josep Soler Garrido
Original assignee: Siemens Aktiengesellschaft
Priority date: 2017-11-20
Filing date: 2018-11-19
Publication date: 2019-05-23

Abstract

The invention relates to a steam turbine (100, 200), comprising: an inflow housing (109); nozzles (115) fixed in the inflow housing; a rotor (121) having a wheel disk (119) and wheel blades (117), a wheel intermediate space (143) lying between the inflow housing (109) and the wheel disk (119); a gap seal (147) arranged in the wheel intermediate space (143); through-holes in the wheel disk (153).

Description

description

STEAM TURBINE

The present invention relates to a steam turbine, in particular special a steam turbine with a nozzle group control.

In a steam turbine, the thermal energy of the steam is converted into mechanical work. For this purpose, the steam turbine has at least one high-pressure-side steam inlet and at least one low-pressure-side steam outlet. On the way between the steam inlet and the steam outlet, the energy of the steam decreases, with a decrease of the steam

Steam temperature and the vapor pressure is accompanied.

In order to achieve a high efficiency, the greatest possible enthalpy gradient between the supplied steam and the steam at the outlet of the steam turbine should be aimed at. For this purpose, the highest possible temperature of the supplied steam is not agile.

Through the turbine extends a turbine shaft, which is driven by means of turbine blades. The coupling of the turbine shaft with an electric generator or a working machine enables the generation of electrical energy or mechanical drive power.

For driving the turbine shaft running and vanes are provided, the blades are fastened to the turbine shaft be and rotate with it. The vanes are fixedly arranged on a turbine housing or a vane carrier.

In steam turbines with nozzle group control, the first steam flowed through by the supplied stage is usually carried out in constant pressure construction. The vanes or nozzles of this control stage are fixed in an inflow housing. The blade row of the control stage is mounted on a wheel disc consolidates and is referred to as A-wheel. The Axialspalt formed by Einströmgehäu- se and wheel disc is referred to as Radzwischen space and lying between the wheel disc and the following lying through streaming drum stages space as a wheelspace. This embodiment of the control stage is known inter alia from the patent DE 1 219 497.

The inflow housing can be designed with (inner housing) or without (nozzle housing) integrated vane carrier.

According to the prior art, a portion of the steam exiting from the nozzle steam flows as a leakage in the Radzwi's space and from there into the annular gap between a strömgehäuse and shaft.

Due to the high temperature of the leakage steam and the centrifugal forces acting on the turbine shaft, the rotor is exposed to particularly high thermal and mechanical stresses in the area of the wheel space and the annular gap. Ro tor and inflow housing must be sized in this area so that they withstand the structural load at the required operating temperature over the entire service life, which may require the use of high-strength and therefore cost-intensive materials.

Furthermore, the amount of leakage steam is no longer available for energy conversion in the A-wheel and possibly further stages. To reduce steam leakage, therefore, a non-contact shaft seal (e.g., labyrinth seal) is usually inserted into the annular gap. The effectiveness of such shaft seals is u.a. limited by the steam temperature, as in the design of the column u.a. thermally induced plasti cal deformations of the shaft (so-called Kriechdehnungen) vorhal th must be.

Thus, according to the prior art, there is a problem in terms of strength and life of the rotor in the area of the shaft seal and the steam leakage which are no longer available for energy conversion in subsequent stages.

An object of the present invention is thus to propose a steam turbine which reduces the temperature of the rotor in the region of the wheel disc and the adjacent shaft seal, thus in particular to increase the life of the rotor, and which also has a higher efficiency of the shaft seal, in particular lower leakage losses , prepared.

The object is achieved by a steam turbine according to the indei gene claim. The dependent claims specify advantageous embodiments of the present invention.

A Einrich device for cooling a steam turbine is known from German Utility Model 1 883 030, wherein cooling steam is removed from the wheel chamber and fed via a pipeline of the shaft seal. This design has in addition to the complex construction method the disadvantage that the wheel disc and the adjacent shaft portion are not cooled in the region of the annular gap.

According to one embodiment of the present invention, there is provided a steam turbine, comprising: an inlet housing; nozzles fixed in the inflow housing; a wheel disc with A-wheel Schaufein, wherein a wheel space between the Einströmgehäuseabschnitt and the wheel disc is GE forms; a gap disposed in the wheel gap gap, which is attached to the inflow housing and / or on the rotor.

High temperature steam may be introduced into a space which is in front of a nozzle inlet. In particular, control valves may be arranged in front of the nozzles, which allow adjustment of a volume flow of steam through the nozzles. In the nozzles, the steam is accelerated and in order to convert the kinetic energy into rotational energy suitable for downstream A-wheel Schaufei gelei tet. For this purpose, the nozzles as well as the paddles FITS trained profiles.

According to this embodiment of the present invention, a gap seal is arranged in the wheel space, which prevents the flow of steam exiting from the nozzle in the following shaft seal. The gap seal may take various configurations, such as a labyrinth seal, a brush seal, etc. The gap seal is made of a material which resists such a vapor temperature.

In particular, between the inflow housing and the wheel disc radially or axially arranged brush seals can be set. The sealing elements can be arranged on a remote wheel disc.

To connect the steam chambers in front of the shaft seal and the wheel space, the wheel disc can be provided with axial bores or a channel can be installed in the inlet housing.

Leakage losses of steam, which can reach the wheel space and annular gap downstream of the nozzle vanes in conventional steam turbines, can be reduced by the gap seal. Furthermore, the steam temperature in the region of the shaft seal can be reduced to approximately the temperature of the steam after the control stage and thus be lower than in conventional steam turbines. As a result, the thermal load of the rotor and the stator can be significantly reduced, which can allow an increase in Druckdif differences and the speed.

According to an embodiment of the present invention, the gap seal partially closes the gap in the portion of passage of vapor coming from an area downstream of the nozzle vanes and upstream of the vanes. This can reduce leakage losses the, whereby the effectiveness of the steam turbine can be increased.

According to a particularly advantageous embodiment of the vorlie invention, the gap seal is designed as a bauraumspa-saving brush seal.

According to one embodiment of the present invention, the brush seal has radially and / or axially aligned brushes which are in contact with a surface of the wheel disc opposite the socket of the brush seal.

Depending on the position of the brush seal within the gap and depending on the geometry of the gap, the brushes may be aligned either axially, radially or in a direction that is between axial and radial.

According to one embodiment of the present invention, the steam turbine further comprises at least one (in particular a plurality of circumferentially spaced) substantially axially ver current passage opening in the wheel disc, which is arranged ra dial between the shaft seal and the gap seal is. The through-hole may allow for supply of lower temperature steam to a shaft seal, as described in detail below.

According to an embodiment of the present invention, the through hole is arranged to allow vapor flow from the wheel chamber into the gap.

In the wheel chamber, the temperature of the steam is usually lower than the temperature of the steam downstream of the Dü se. Steam from the wheel chamber can thus be used advantageously for cooling certain components of the steam turbine, in particular for cooling a rotor section, between the rotor and can be arranged the Einströmgehäuseabschnitt. According to one embodiment of the present invention, the passage opening is designed as an axially extending bore through the wheel disc. Thus, the passage opening can be realized in a simple manner. The passage opening can be designed as an axially extending opening, in particular bore, through the wheel disc or as an opening or an opening ge inclined at an angle to the axial direction through the wheel disc or as an eroded opening through the wheel disc.

According to an embodiment of the present invention, the steam turbine further comprises a first drum having a plurality of stages.

According to an embodiment of the present invention, the steam turbine further comprises: at least one second drum having a plurality of stages; a shaft seal comprising, in particular, an axially extending labyrinth seal and is arranged between the rotor and the inflow housing, the second drum being fed by steam emerging from the first drum and via a

Steam guide is fed back into a steam inlet space to the second drum, wherein the second drum of the steam in, as compared to the direction in which the first drum is traversed by the steam, in the reverse direction is flowed through, wherein the steam inlet space to the second drum via the shaft seal of is separated from the gap.

The labyrinth seal may be partially attached to the rotor and partially attached to the inflow housing. In the vapor inlet space to the second drum similar or even equal pressure conditions and temperature conditions could vorlie conditions as at an exit region downstream of the first drum of the steam turbine.

According to one embodiment of the present invention, the gap seal between the wheel disc and the inlet housing radially further from the rotor axis than the shaft seal, and is particularly adapted to scoop a stream of steam from the space area downstream of the nozzle and to reduce upstream of the vanes through the gap and toward the shaft seal.

Furthermore, an exit region of the passage opening in the wheel disc into the gap can be closer to an axis of rotation than the gap seal. Thus, steam from the wheel space through the through-hole can be passed to the Wellendich device for cooling the shaft seal. In the section from the gap between a space area downstream of the nozzle paddles to the gap seal, the loss of vapor stream entering the gap downstream of the nozzle paddles may result in further advancement to the shaft seal (through another portion of the gap) due to the gap seal be prevented.

According to an embodiment of the present invention, the steam turbine further includes a control system for controlling a quantity of steam flowing into the steam turbine.

Embodiments of the present invention will now be explained with reference to the accompanying drawings. The invention is not limited to the illustrated or described embodiments. In particular, the drum of the inflow housing can be flowed through in the same direction as the subsequent drum.

FIG. 1 illustrates, in a schematic longitudinal section, a steam turbine according to an embodiment of the present invention;

FIG. 2 illustrates in a schematic longitudinal section view a steam turbine according to another embodiment of the present invention. The in Figure 1 in a schematic longitudinal section il

Lustrierte part of a steam turbine 100 includes a Außenge housing 101 with an inflow channel 103, in the hot steam

105 (live steam) into the interior of the steam turbine 100 can be introduced. The interior of the steam turbine 100 includes various portions 107, 109 and 111 of one or more assemblies (111 is referred to as a vane carrier), wel che are fixed to the outer housing 101 by not illustrated fastening transmission elements. The sections 107 and 109 are referred to in the context of this application as Einströmgehäuse Trom melbeschaufelung.

The introduction channel 103 carries the live steam 105 in a nozzle located in the Einströmgehäuse Vorraum 113, from which the steam 105 is passed through the nozzles 115 to impinge downstream on vanes 117 which are attached to a wheel disc 119, which in turn with a rotor 121 of the steam turbine 100 is connected.

After driving the wheel disc 119 by flow around the wheel paddles 117 passes the steam 106 in a room downstream of the vanes 117, which is also known as wheel space 122 be. The rotor 121 rotates during operation of the steam turbine 100 about an axis of rotation 123. After the steam 106 has passed through the wheel chamber 122, it passes to ei ne first stage 125 of a first drum 127. The first Trom mel 127 includes in addition to the first stage 125 a A plurality of further stages 129. In this case, each stage 125, 129 by means attached to the portion 107 of the inflow housing Leitschau blades 131 and attached to the rotor 121 blades 133 is formed. The respective upstream vanes of each run 133 arranged vanes 131 direct the steam

106 suitably to the downstream blades 133 in order to effect a transfer of the energy of the steam 106 in Rota ion energy of the rotor 121.

After flowing through the first drum 127 of the steam turbine 100 leaves the now further cooled and in his pressure decreased steam 108, the first drum 127 in a downstream of the first drum 127 in the flow path of the steam 108 located portion 135 of the interior. In this inner space, the steam 108 has a pressure p_nTrl and a temperature T_nTrl. This pressure and also this temperature are less than a temperature T_nD and a pressure p_nD immediacy bar downstream of the nozzle vanes 115th

In the space portion 135 of the interior of the cooled steam 105 is guided in a direction opposite to a flow direction through the first drum 127 and passed to another portion 137 of the interior of the steam turbine 100. This portion 137 of the interior is in communication with a steam inlet space 139 in a second drum 141, which may be built up similar to the first drum 127, but is formed of steam in an opposite direction compared with the direction in which the first drum 127 is flowed through, to be flowed through. Also, the second drum 141 is formed of a plurality of stages 125, 129, wherein each stage guide vanes 131 and relatively arranged downstream therefrom blades 133, wherein the blades 133 are fixed to the rotor 121, while the guide vanes 131 at a section 111 from a Leitschaufelträgers are attached.

The steam turbine 100 has in particular the inflow housing section 109 of the inflow housing, on which the nozzle vanes 115 are mounted. The relative to the Einströmge- housing portion 109 rotatable together with the rotor 121 wheel disc 119 has attached the paddles 117 thereto. In this case, the nozzle vanes 115 are formed and arranged relative to the vanes 117 in order to direct introduced steam 105 onto the vanes 117. Further, a gap 143 between tween the Einströmgehäuseabschnitt 109 and the wheel disc 119 is formed so as to allow free rotation of the wheel disc 119 GE compared to the fixed Einströmgehäuseabschnitt 109 to it possible. In this gap 143 penetrates a part 145 of the paddles 115 passing through the nozzle or passing through or deflected steam 105, which thus and unfavorably not paddling over the wheel 117 is passed. This proportion 145 of the steam 105 represents a leakage current in conventional steam turbines.

In order to limit and reduce this leakage current 145, the steam turbine 100 according to this embodiment of the present invention includes a gap seal 147 disposed in a portion of the gap 143, which is attached to the inflow housing section 109 or the wheel disc 119.

The gap seal 147 at least partially occludes the gap 143 in the portion where the gap seal 147 is disposed against passage of vapor 145 resulting from a space portion 149 downstream of the nozzle vanes 115 and upstream of the vanes 117.

The gap seal 147 is circumferentially completely circumferential to the gap 143, which has a ring shape, against

Passage of steam 145 (at least partially) Shen to Shen. The gap seal 147 may in particular be designed as a Bürs tendichtung with brushes and a socket, wherein the socket can be pressed into a groove in the Einströmgehäuseabschnitt 109.

The steam turbine 100 further has in the wheel disc 119 a substantially axially (ie parallel to the rotation axis 123) extending through hole 151 which is radially (the ra diale direction is perpendicular to the rotation axis 123) between the rotor axis 123 and the gap seal 127 is arranged ,

The passage opening 151 allows a partial flow 153 of the steam 106 to be guided out of the wheel space 122 through the wheel disc 119 to a shaft seal 154, which is arranged between the rotor 121 and the inflow housing section 109 of the inflow housing. The partial flow 153 of the steam has a pressure p_RR and a temperature T_RR, which are smaller than the pressure p_nD or the temperature T_nD after passing through the nozzle vanes 115 but before passing through the vanes 117, since the steam in the wheel chamber 122 has already transferred egg nen part of its energy on the paddle 117. The partial flow 153 is thus suitable to cool the region of the shaft seal 154, which may be formed in particular as a labyrinth seal, when flowing from one gap end to the steam inlet space 139 to the second drum 141 out. The partial flow 153 then merges with the flow 108 exiting the first drum 127 at the end of the first drum to enter the second drum 141.

The vapor stream after passing through the nozzle vanes 115 and the vanes 117 is designated by reference numeral 106.

As shown in FIG. 1, the steam inlet space 139 to the second drum 141 is separated from the gap 143 via the shaft seal 154. The passage opening 151 allows a vapor communication between a closer than the gap seal on the rotation axis 123 located portion of the gap and the wheel space 122, i. a space downstream of the vanes 117.

In the embodiment illustrated in Figure 1, the gap 143 is closed by the gap seal 147 in the axial direction, i. E. the gap seal 147 extends in the axial direction. Depending on the geometry of the gap 143 and also depending on the geometry of the Einströmgehäuseabschnitte 109 and the Radschei be 119, the gap seal 147 in other rich lines, approximately radially extend, as in another Ausfüh tion form of the present invention in Figure 2 is illustrated.

Structures and elements which are similar or the same in function and / or structure are denoted by reference numerals in FIGS. 1 and 2, which differ only in the first position. Relative to the orientation of the steam turbine in FIG. 1, FIG. 2 illustrates a part of a steam turbine 200, the drums of which are all flowed through in the same direction.

Steam 205 is supplied through the inflow pipe 203 to the nozzle vanes 215, which steer the steam to the vanes 217 to rotate the wheel vanes 219 fixed to the vanes 217, which is coupled to the rotor 221, in rotation. The wheel disc 219 includes a substantially axially (parallel to the axis of rotation 223) extending through-opening 251 which directs a partial flow 253 of the vapor stream 206 through the passage opening 251 to the shaft seal 254 to cool this area.

The gap 243 formed between the wheel disc 219 and the inflow housing portion 209 is at least partially closed by the brush seal 247 to limit the leakage flow 245 of steam undesirably branching from the space portion 249 downstream of the nozzle vanes 215 and upstream of the vanes 217 , The unwanted partial flow 245 is thus at least partially prevented from penetrating to the shaft seal 254. Thus, a heating in the area of the shaft seal 254 and all subsequent Be rich by the still very hot steam partial stream 245 vermin be changed. The partial flow 245 has a temperature T_nD and a pressure p_nD. This temperature and pressure are greater than the pressure p_RR and the temperature T_RR in the wheel chamber 222, from which the partial flow 253 comes from. Thus, the partial stream 253 of the steam is suitable for cooling in the region of the Wel lendichtung 254.

Stream 206 enters a non-illustrated first drum in FIG. 2 farther to the right and is NOT deflected 180 ° after passing through the first drum and returned to enter a second drum to the left of shaft seal 254 in FIG. The brush seal 247 has a socket 257 and brushes 259.

As can be seen from Figure 2, the brushes 259 extend in a radial direction and are in contact with a GE opposite surface portion 263 of the wheel disc 219th This surface portion 263 may according to an embodiment form a groove to guide the ends of the Bürs th 259th to effect.

It should be noted that the embodiments described herein represent only a limited selection of mögli chen embodiments of the invention. Thus, it is possible to combine the features of individual embodiments in a suitable manner with one another, so that for the person skilled in the art with the embodiments that are explicit here, a large number of different embodiments are to be regarded as obviously disclosed.

Claims

claims

1. Steam turbine (100, 200), comprising:

an inflow housing section (107, 109) of a flow housing;

Nozzle vanes (115) attached to the inflow housing section;

a relative to the Einströmgehäuseabschnitt (109) together with a rotor (1121) rotatable wheel disc (119) egg nes control wheel with vanes (117), wherein the nozzle show blades (115) formed and arranged relative to the vanes (117) introduced Steering steam (105) on the Radschau blades (117), wherein a gap (143) between the Ein strömgehäuseabschnitt (109) and the wheel disc (119) is formed; and

a in a portion of the gap (143) arranged gap seal (147), which is brought to the Einströmgehäuseabschnitt (109) on.

A steam turbine according to claim 1, wherein the gap seal (147) is the gap (143) in the vapor passage portion (145) originating from a space portion (149) downstream of the nozzle vanes (115) and upstream of the vanes (117) , partially occlusive,

wherein the gap seal is formed in particular circumferentially circumferentially.

3. Steam turbine according to claim 1 or 2, wherein the gap Dich device (147) as a brush seal (247) is formed, wherein the brush seal brushes (259) and a socket (257), in which the brushes are pressed,

wherein the socket of the brush seal in particular in a recess (161) in the Einströmgehäuseabschnitt (109) is pressed.

4. Steam turbine according to the preceding claim,

wherein the brush seal (147) radially and / or axially aligned brushes (259), which with one of the socket the brush seal opposite surface (263) of the wheel disc (219) are in contact.

5. Steam turbine according to one of the preceding claims, fer ner comprising:

a substantially axially extending through hole (151) in the wheel disc, which is arranged radially between a rotor axis (123) and the gap seal (147).

6. Steam turbine according to the preceding claim,

wherein the passage opening (151) is arranged to provide vapor communication between another portion of the gap (143) that is beyond the gap seal (147) from the nozzle vanes (115) and a space (122) downstream of the vanes (117).

7. Steam turbine according to one of the 2 preceding claims, wherein the passage opening (151)

as an axially extending opening, in particular bore, through the wheel disc (119) or

as an opening or breakthrough inclined at an angle to the axial direction through the wheel disc or

as an eroded opening through the wheel disc

is executed.

8. Steam turbine according to one of the preceding claims, fer ner comprising:

a first drum (127) having a plurality of steps (125, 129), each step having vanes (131) attached to a stator part and rotor blades (133) attached to the rotor;

wherein the first drum is located downstream of the space downstream of the paddle vanes.

A steam turbine according to the preceding claim, further comprising:

at least one second drum (141) having a plurality of steps (125, 129), each step being connected to the stator part. having vanes and rotor blades mounted on the rotor;

a shaft seal (154) which in particular comprises a labyrinth seal extending in the axial direction and between the rotor (121) and the inflow housing section (109) of the inflow housing is arranged between

wherein the second drum (141) is fed by steam emerging from the first drum (127) and via a

Steam guide is fed back into a steam inlet space to the second drum, wherein the second drum is traversed by the steam in the reverse direction, compared with the direction in which the first drum is traversed by the steam,

wherein the steam entry space (139) to the second drum (141) is separated from the gap via the shaft seal (154).

A steam turbine as claimed in any one of the preceding claims, wherein the gap seal (147) is located radially further from the rotor axis (123) than the shaft seal (154) and is adapted to direct a flow of steam from the space area (149) downstream of Nozzle vanes (115) and upstream of the vanes (117) through the gap (143) and toward the shaft seal to decrease.

11. Steam turbine according to one of the preceding claims, further comprising:

Control elements, which are arranged upstream of the nozzle blades and allow to set a steam flow rate through the nozzle blades in the interior,

wherein the steam turbine in particular further comprises an outer housing which surrounds the inflow housing.