EP3155226A1

EP3155226A1 - Steam turbine, and method for operating a steam turbine

Info

Publication number: EP3155226A1
Application number: EP15750771.6A
Authority: EP
Inventors: Jan Walkenhorst; Uwe Zander; Armin De Lazzer
Original assignee: Siemens AG
Current assignee: Siemens AG
Priority date: 2014-08-20
Filing date: 2015-08-19
Publication date: 2017-04-19
Anticipated expiration: 2035-08-19
Also published as: JP2017525887A; RU2655068C1; KR101949058B1; EP3155226B1; KR20170043590A; US20170234131A1; CN106574502A; EP2987952A1; CN106574502B; US10436030B2; WO2016026880A1; PL3155226T3; JP6416382B2; BR112017002944A2

Abstract

The invention relates to a steam turbine (1) having a cooling option, in which steam is taken from the flow channel, said steam cooling the thrust-compensating intermediate floor (16), being mixed with a small amount of live steam and being returned to the flow channel.

Description

description

Steam turbine and method for operating a steam turbine

The invention relates to a steam turbine comprising an inner ^¬ housing and an outer housing and a rotor which is rotatably mounted within the inner housing, wherein the outer housing is arranged around the inner housing, wherein the rotor arranged along a first flow direction high-pressure area and along a Having second medium-pressure region arranged second flow direction.

The invention further relates to a method for cooling a steam turbine, wherein the steam turbine has a high-pressure region and a medium-pressure region, wherein a rotor is arranged between the high-pressure region and the medium-pressure region and has a thrust balance intermediate bottom.

For the purposes of the present application, a steam turbine means any turbine or sub-turbine through which a working medium in the form of steam flows. In contrast, gas turbines, gas and / or air flow through as the working medium, however, completely different tempera ^¬ ture and pressure conditions than the steam in a steam turbine. In contrast to gas turbines has steam turbines z. As the one part turbine incoming working fluid with the highest temperature at the same time the highest pressure. An open cooling system, which is open to the flow channel is in gas turbines without Teilturbinen-external Zu ^{¬ management} of cooling medium feasible. For a steam turbine, an external supply for cooling medium should be provided. For this reason, the state of the art regarding gas turbines can not be used for the assessment of the present application subject. A steam turbine typically comprises a rotor-mounted rotatably mounted rotor disposed within a housing. When flowing through the interior of the flow channel formed by the housing jacket with heated and pressurized steam, the rotor is rotated by the steam via the blade. The blades of the rotor are also referred to as blades. In addition, usually stationary guide vanes are suspended on the inner housing, which along an axial extension of the body in the interstices of the

Rotor blades grip. A vane is typically held at a first location along an interior of the steam turbine casing. In this case, it is usually part of a stator blade row, which comprises a number of guide vanes which are arranged along an inner circumference on an inner side of the steam turbine housing. Each vane has its blade radially inward. A row of vanes at said first location along the axial extent is also referred to as a vane grille or crown. Usually, a number of Leit ^¬ blade rows are connected in series. Accordingly, at a second location along the axial extent behind the first location, a further second blade is held along the inside of the steam turbine housing. A pair of a vane row and a blade row is also referred to as a vane stage.

The housing jacket of such a steam turbine can be formed from a number of housing segments. Under the housing shell of the steam turbine is in particular the statio ^¬ nary housing component of a steam turbine or a turbine part to understand that along the longitudinal direction of the steam turbine has an interior space in the form of a flow channel, which is provided for flow through the working medium in the form of vapor. This can, depending on the steam turbine, a

Inner housing and / or a guide vane carrier. However, it may also be provided a turbine housing, which has no inner housing or no guide vane. For efficiency reasons, the interpretation of such a steam turbine for so-called "high steam parameters", therefore, be desirable to ^¬ special high vapor pressures and / or high steam temperatures. However, a tempera ^¬ turerhöhung of material technology in particular is not unlimited possible. In order safe operation of the to allow steam turbine even at particularly high temperatures, therefore, cooling of individual components or components may be desirable. Without efficient cooling would ^¬ rise at the temperatures significantly more expensive materials (for example, nickel-based alloys) is necessary.

In the cooling methods known hitherto, in particular for a steam turbine body in the form of a steam turbine housing or a rotor, a distinction must be made between active cooling and passive cooling. In the case of active cooling, cooling is effected separately by a cooling medium supplied to the steam turbine body, that is to say in addition to the working medium. In contrast, a passive cooling occurs single ^¬ Lich by a suitable guide or use of the working medium. So far, steam turbine bodies have preferably been passively cooled.

All previously known cooling methods for a steam turbine housing thus see, if it is at all active cooling ^¬ process, at best, a targeted flow against a separate and to be cooled turbine part and are on the inflow of the working fluid, at best, with Einbe ^¬ drawing the first vane ring , limited. This can result in a load of conventional steam turbines with higher steam parameters to an acting on the entire turbine, increased thermal load, which could be inadequately ver ^¬ reduced by a conventional cooling of the housing described above.

Embodiments of steam turbines are known which, in addition to a first flow channel, have a second flow Have channel, wherein both the first flow channel and the second flow channel are arranged ^¬ within a housing ^¬ . Such designs are also referred to as compact turbines. Embodiments are known in which the first flow channel is designed for high-pressure blading and the second flow channel is designed for medium-pressure blading. The flow directions of the first Strö ^¬ flow channel and the second flow channel in this case show in the opposite direction to thereby minimize the thrust balance. Essentially, such types include a formed with a high-pressure region and a medium pressure rotor rotatably mounted within a Innenge ^¬ häuses is arranged, around the inner housing a Außenge ^¬ housing is arranged. The high pressure area is designed for live steam temperatures. After flowing through the live steam through the high-pressure area, the steam flows to a reheater and is brought there to a higher temperature and then flows through the medium-pressure region of the steam turbine.

The application limits of such rotors are defined by areas subject to high thermal stress. As temperatures increase, the relevant strength characteristic ^value decreases proportionally. This results in maximum allowable Wel ^¬ lendurchmesser which lead in particular at 60 Hertz applications to limitations as regards the rotor dynamic slenderness ratio of the rotor. Therefore, when reaching application limits usually in a Monoblockrotor changed to the next better material that can withstand the thermal requirements or there is a rotor welded out ^¬ out, with two materials are each designed for the thermal stresses.

It would be desirable to have an effective cooling at a vapor ^¬ turbine component, in particular for a high-temperature-excessive steam turbine. At this point, the invention begins, whose object is to provide a steam turbine and a method for their production, in which the steam turbine is cooled particularly effectively even in the high temperature ^¬ tur range.

The object is achieved by a steam turbine according to claim 1 and by a method according to claim 9.

An essential idea of the invention is to form a passive cooling. The invention is geared to a steam turbine in the aforementioned compact design. This means that the steam turbine within a common outer housing has a high-pressure area and a medium-pressure area. The high pressure area is designed for live steam temperatures. The live steam temperatures are between 530 ° C and 720 ° C at a pressure of 80-350 bar. The medium pressure range is designed for temperatures in the input range of 530-750 ° C at a pressure of 30-120 bar.

In a steam power plant, a distinction is made between high-pressure and medium-pressure blading as follows: A live steam initially flows through a partial turbine designed for live steam. After flowing through the live steam through the high-pressure area, this flows to a reheater where it is heated to the medium-pressure inlet temperatures and then flows through the medium-pressure area. After flowing through the medium-pressure region of the steam flows to a low pressure region and there has lower steam parameters.

An essential idea of the invention is now to design the steam turbine in such a way that a thrust balance intermediate floor can be passively cooled. For this purpose, a branched off from the high-pressure flow channel at a suitable location from the flow channel, which is guided to a point for thrust balance intermediate floor. This steam can then in the area between thrust balance intermediate floor and the Inner case spread out. Another essential idea of the invention is that the aforementioned steam can mix with a portion of the live steam, which then returns to the first via a cross-return duct

Flow channel can be performed.

Advantageous developments are specified in the subclaims.

In a first advantageous development, the first high-pressure blade stage is arranged in front of the second high-pressure blade stage as seen along the first flow direction.

This means that the vapor taken from the first high-pressure vane stage has higher vapor parameters than the vapor taken from the second high-pressure vane stage. Thus, a targeted suitable vapor may be withdrawn from the high pressure blading area.

In a further advantageous embodiment, the first thrust balance piston intermediate floor space along the first flow direction is seen before the second Schubausgleichszwi rule floor space. Since the thermal load of the thrust balance intermediate floor is different, the invention provides that a better cooling possibility is possible when the first thrust balance intermediate floor space along the first flow direction is arranged in front of the second thrust balance intermediate floor space.

In a further advantageous development, a first brush seal along the second flow direction before the second thrust balance intermediate floor space and a second brush seal along the second flow direction behind the first thrust balance intermediate floor space angeord ^¬ net between the inner housing and the thrust balance intermediate bottom. In a particular advantageous development of the first cross recirculation channel is formed with return tubes. Since ^¬ by the thermal balance can be optimized. In a further advantageous embodiment, the connection is formed with connecting tubes, this also leads to an advantageous temperature compensation.

In a particular advantageous embodiment, the

Steam turbine with a second cross-return passage ^¬ forms, which is arranged as a communicating tube between a third thrust balance intermediate bottom space formed between the thrust balance intermediate bottom and the inner housing and after a third high-pressure blade stage.

As a result, a further vapor in the space between the intermediate bottom and the inner housing can be used for cooling possibilities and for working relaxation.

Advantageously, as seen in the first flow direction, the third high-pressure blade stage is arranged behind the second high-pressure blade stage.

Thus, with the invention, the thrust balance intermediate floor can be optimally cooled.

As a result, an extension of the mechanical application limits of the rotor by lowering the temperature inside the shaft is possible. In addition, it is possible to ensure sufficient cooling of the thrust balance intermediate floor with potential use of brush seals. In addition, the thermally critically loaded region of the components is cooled by a passive system by the inventive arrangement.

The above-described characteristics, features and advantages of this invention, as well as the manner in which these are achieved, become clearer and more clearly understandable in the context of the invention. In conjunction with the following description of the embodiments, which are explained in more detail in conjunction with the drawings. Embodiments of the invention are described below with reference to the drawing. This is not intended to represent the Ausführungsbei ^¬ games relevant, but the drawing, including explanations useful, in a schematic

and / or slightly distorted shape. With regard to additions to the teachings directly recognizable in the drawing reference is made to the relevant prior art.

1 shows a schematic cross-sectional view of a

Steam turbine

FIG. 2 shows a detail of that shown in FIG

Steam turbine with the arrangement according to the invention.

1 shows a steam turbine 1 comprising an inner housing 2 and an outer housing 3 and a rotor 4. The rotor 4 is rotatably mounted within the inner housing 2. The storage is not shown in detail. The outer housing 3 is arranged around the inner housing 2. The rotor 4 is formed in Wesent ^¬ union rotationally symmetrical about the axis of rotation. 5 Along a first flow direction 6, which runs essentially parallel to the axis of rotation 5, the rotor 4 has a high-pressure region 7. Arranged opposite to the first flow direction 6, the rotor 4 has a medium-pressure region 9 which is arranged along the second flow direction 8. The inner housing 2 has in the high pressure region 7 a plurality of high ^¬ pressure guide vanes (not shown), which are arranged on the circumference about the axis of rotation 5. The Hochdruckleitschau ^¬ blades are arranged such that along the first Strö- tion direction 6, a high-pressure flow channel 10 having a plurality of high-pressure blade stages (not shown), each having a series of high-pressure blades and a series of high-pressure vanes is formed.

Via a first high-pressure inflow steam 11 flows into the steam turbine 1 and then flows through the high-pressure flow passage 10. In the high-pressure Strö ^¬ flow duct 10, the steam expands, whereby the temperature drops. The thermal energy of the steam is converted into rotational energy of the rotor ^¬. 4 After the steam has passed through the high pressure flow passage 10, it flows from a high pressure discharge area 12 from the steam turbine 1 to a reheater (not shown). In the intermediate superheater, the cooled vapor is brought back to a high temperature, which is comparable to the live steam temperature in the high-pressure inflow region. However, the pressure in the inflow region 11 is significantly lower. The inner housing 2 has in the central pressure region 9 a plurality of ^¬ teldruck vanes (not shown), which are arranged such that along the second flow direction 8, a medium-pressure flow channel 13 with a plurality of medium-pressure blade stages (not shown), each having a series medium pressure Blades and a number medium-pressure Leit ^¬ blades have, is formed.

The steam after the reheater flows through the medium-pressure inflow region 14 through the medium-pressure flow channel 13. The thermal energy of the steam is converted into Rotationsener ^¬ gie of the rotor 4. After the medium-pressure flow ^¬ channel 13, the steam flows through an outlet 15 from the

Steam turbine 1 out. The steam is then forwarded to a low pressure turbine part (not shown) or a process steam process. The rotor 4 has between the high-pressure flow channel 10 and the medium-pressure flow channel 13 to a thrust balance intermediate bottom 16. This thrust balance intermediate bottom 16 has a larger diameter than the rotor 4th

The live steam temperature is 530 ° C - 720 ° C at a pressure of 80bar - 350bar. The mean pressure temperature is 530 ° C - 750 ° C at a pressure of 30bar - 120bar.

FIG. 2 shows a detail of the steam turbine 1 from FIG. 1, wherein further features according to the invention are shown in FIG. The inner housing 2 has a connection 17 which is arranged as a communicating tube between the high-pressure flow channel 10 after a first high-pressure blade stage 18 and a first thrust balance intermediate bottom space 19, wherein the thrust balance intermediate bottom space 19 between the thrust balance intermediate bottom 16 and the inner housing 2 is arranged , The inner housing 2 has a plurality of segments 20 in the region of the thrust balance intermediate floor 16. The segments 20 each have a labyrinth seal (not constitute provided ^¬) on.

The inner housing 2 further comprises a first cross-return passage 21, which is arranged as a communicating pipe Zvi ^¬ rule a second thrust balance between bottom space 19 (between the thrust balance intermediate base 16 and is disposed the inner casing 2) and after a second high pressure stage of blades 22nd

The first high-pressure vane stage 18 is arranged in front of the second high-pressure vane stage 23 as seen along the first flow direction 6.

The first thrust balance intermediate floor space 19 is arranged in front of the second thrust balance intermediate floor space 22 as seen along the first flow direction 6.

Between the inner housing 2 and the thrust balance intermediate floor 16 is a first brush seal 24 along the second flow direction 8 before the second thrust compensation zwi rule floor space 22 is arranged. A second brush seal 25 is arranged along the second flow direction 8 behind the first thrust balance intermediate floor space 16. The first cross recirculation passage 21 may be formed in alternative ^embodiments with tubes (not shown). In the embodiment shown in Figure 2, the cross return passage 21 in the inner housing 2 angeord ^¬ net.

The connection 17 is formed in the embodiment selected in Figure 2 in the inner housing 2 and in alternati ^¬ ven embodiments, the connection 17 may be formed with connecting tubes.

The steam turbine 1 has a second cross-return passage 26, which as a communicating pipe between a third thrust balance between bottom space 27, the balance between ground 16 is arranged and the inner casing 2, between the thrust and according to a third high-pressure blade stage 28 is ^¬ arranged high-pressure inflow space in the high-pressure Flow channel 10 is formed.

The third high-pressure blade stage 28 is arranged behind the second high-pressure blade stage 23 as seen in the first flow direction 6. The cross-return passage 26 may be formed in the inner housing 20. In alternative embodiments, the third cross return passage 26 may be formed as a tube.

Although the invention in detail by the preferred embodiment has been illustrated and described in detail, the invention is not limited ^¬ by the disclosed examples and other variations can be derived therefrom by the skilled artisan without departing from the scope of the invention.

Claims

claims

1. Steam turbine (1) comprising

an inner housing (2) and an outer housing (3) and a rotor (4) which is rotatably mounted within the inner housing (2),

wherein the outer housing (3) around the inner housing (2) is angeord ^¬ net,

wherein the rotor (4) has a high-pressure area (7) arranged along a first flow direction (6) and a medium-pressure area (9) arranged along a second flow direction (8),

wherein the Inngengehäuse (2) in the high-pressure region (7) has a plurality of high pressure guide vanes,

which are arranged in such a way

a high-pressure flow channel (10) having a plurality of high-pressure blade ^stages , each having a row of high-pressure rotor blades and a row of high-pressure stator blades, is formed along the first flow direction (6), the inner housing (2) being in the medium pressure Area (9) has a plurality of medium-pressure vanes,

which are arranged such that along the second Strö ^¬ flow direction (8), a medium-pressure flow passage with several ^¬ ren medium-pressure blade stages which have medium pressure Leit shovel ^¬ each comprise a series intermediate-pressure rotor blades and a row is formed,

wherein the rotor (4) has a thrust balance intermediate floor (16) between the high-pressure area (7) and the medium-pressure area (9),

wherein the inner housing (2) has a connection (17) as a communicating pipe between the high pressure Strö ^¬ flow duct (10) after a first high-pressure stage of blades (18) and a first thrust balance between bottom space (19) is formed,

wherein the inner housing (2) having a first cross-return ^¬ channel (21) formed as a communicating pipe between a second thrust balance between bottom space (22) disposed between the thrust balance intermediate floor (16) and the inner housing (2),

and after a second high-pressure blade stage (23) ange ^¬ arranged high-pressure inflow space in the high-pressure flow channel (10) is formed.

2. Steam turbine (1) according to claim 1,

wherein the first high-pressure blade stage (18) is arranged upstream of the second high-pressure blade stage (23) along the first flow direction (6).

3. Steam turbine (1) according to claim 1 or 2,

wherein the first thrust balance intermediate floor space (19) is arranged in front of the second thrust balance intermediate floor space (22) as seen along the first flow direction (6).

4. Steam turbine (1) according to one of the preceding claims,

wherein between the inner housing (2) and the thrust balance intermediate bottom (16) a first brush seal (24) along the second flow direction (8) in front of the second thrust equal intermediate bottom space (22) and a second brush seal (25) along the second flow direction (8) behind the first thrust balance intermediate floor space (19) is arranged.

5. Steam turbine (1) according to one of the preceding claims,

wherein the first cross-return passage (21) is formed with tubes.

6. Steam turbine (1) according to one of the preceding claims,

wherein the connection (17) is formed with connecting tubes.

7. Steam turbine (1) according to one of the preceding claims,

with a second cross-return passage (26) is provided as a communicating pipe between a third Schubaus- equal between the bottom space (27) equal to between ground between the Schubaus- (16) and the inner housing (2) angeord ^¬ net,

and is formed after a third high-pressure blade stage (28) at ^¬ ordered high-pressure inflow space in the high-pressure flow channel (10).

8. Steam turbine (1) according to one of the preceding claims,

wherein the third high-pressure blade stage (28), viewed in the first flow direction (6), lies behind the second high-pressure

Blade stage (23) is arranged.

9. A method for cooling a steam turbine (1),

wherein the steam turbine (1) has a high-pressure area (7) and a medium-pressure area (9), wherein a rotor (2) between the high-pressure area (7) and the medium-pressure area (9) has a thrust balance intermediate floor (16). wherein steam is taken from the high-pressure area (7) and is supplied to a space between thrust balance intermediate floor (16) and Inngengehäuse (2), wherein steam from the

Space between the thrust balance intermediate floor (16) and the inner housing (2) via a first cross-return passage (21) is supplied to the high pressure area (7).

10. The method according to claim 9,

wherein a further steam between the thrust balance intermediate floor (16) and inner housing (2) via a second cross-return passage (26) in the high-pressure area (7) is supplied ^¬ leads.