EP1505254B1 - Gas turbine and associated cooling method - Google Patents

Description

Technical area

The present invention relates to a gas turbine, in particular in a power plant. The invention also relates to an associated method for cooling the gas turbine.

State of the art

Much of the electricity needed is generated in power plants using steam and / or gas turbines. The efficiency of these systems is determined by the inlet temperature of the working medium (gas or steam). If higher efficiencies are to be realized, then one has to go to higher temperatures. By these temperature increases, however, the limit of the material stress is reached very quickly. Therefore, to increase the efficiency of an increased cooling of the steam and / or gas turbine is required. The usual cooling medium of the hot gas-carrying components in a gas turbine is air, taken from the final or intermediate stage of the compressor. Critical locations are the combustion chamber lining, the first guide blade row, the first blade row, the turbine rotor and the rear compressor section.

In general, however, a cooling of steam or gas turbines by means of steam is known ( DE 3003347 ). Due to its higher heat capacity and lower viscosity, steam is in principle a better cooling medium than air. steam In addition to cooling air, the specific compressor power is reduced by eliminating the pressure losses of the cooling air and reduces the NOX emissions by a lower combustion chamber temperature at the same turbine inlet temperature.

US 4,413,477 describes the general ability to cool combustor components with steam, with no specific embodiments being disclosed.

From the prior art ( EP 0 955 449 A1 . EP 0 911 489 A1 . EP 0 911 489 and US 4,571,935 ) Gas turbines are known, the vanes are partially cooled with steam and partly with air. The steam cooling is done as a closed system to improve the efficiency of the gas turbine plant. Out EP 392,664 It has become known to blow off a portion of the steam used to cool a blade at the trailing edge of the blade, while another part of the steam is returned in a closed system.

The steam cooling can be carried out as an open or closed system. In an open system (for example, film cooling of the blades), the steam, after it has fulfilled its cooling task, admixed with the working gas and thereby increases performance and efficiency on the gas turbine.

Presentation of the invention

The present invention, as characterized in the claims, deals with the problem of providing a gas turbine of the kind mentioned an improved embodiment, with which in particular a higher performance and a longer life of the critical components can be achieved.

According to the invention, this problem is solved by the subject matters of the independent claims. Advantageous embodiments are the subject of the dependent claims.

The invention is based on the general idea, in a gas turbine, which is formed with a conventional air cooling device for cooling parts of the gas turbine by means of air, in addition to provide a steam cooling device which is designed for cooling parts of the gas turbine by means of steam.

For example, the cooling of a rotor and a stator of the gas turbine is conventionally carried out with air, while in addition a small amount of steam, e.g. From the inlet to the turbine to the exit from the turbine along a rotor shell parallel to the hot gas flow flows. Due to its higher heat capacity and lower viscosity, steam is in principle a better cooling medium than air. Steam instead of cooling air also reduces the required amount of cooling medium by approx. 50%.

The essential advantage of the invention is that the power of the additionally steam-cooled gas turbine increases compared to the conventional air-cooled gas turbine by about 2 to 5%. This results from the higher turbine inlet temperature which results in higher power. It is also noteworthy that only a comparatively small amount of steam applied in a targeted manner is needed in order to achieve intensive cooling of the gas turbine together with the air cooling.

According to a preferred embodiment of the solution according to the invention, provision may be made for the steam cooling device to be designed at least for cooling the inner inner lining and / or the inner outer lining of the combustion chamber and / or the guide vanes and / or hub-side covering elements of the vanes, and / or for a steam guide to do so is formed, that from the row of vanes along a rotor shell, a vapor film is formed.
This steam film protects the rotor from contact with the hot gas flow and thus leads to an extended life of the critical components of the gas turbine.

According to a preferred embodiment of the invention, the steam cooling device for cooling an upstream region of the Guide vanes and the air cooling device may be formed for cooling a downstream region of the guide vanes. This offers the advantage that the guide vanes are intensively cooled with steam in the thermally more heavily loaded inflow region. The invention uses the knowledge that the air cooling is sufficient to cool the thermally less heavily loaded discharge area, whereby a sufficient blade cooling is achieved with relatively little energy. If the injected for cooling steam exits through outlet openings back into the hot gas stream, it creates on the outer skin of the respective vane a fine vapor layer, which lays over the vanes and this protects similar to the rotor shell in the manner described above from direct contact with the hot gas stream and thus contributes to the robustness of the gas turbine.

The steam required for the steam cooling device can advantageously be taken from a waste heat boiler of a steam turbine, which is coupled to the gas turbine. The steam cooling thus requires no additional steam generator.

Other important features and advantages of the present invention will become apparent from the dependent claims, from the drawings and from the associated figure description with reference to the drawings.

Brief description of the drawings

Preferred embodiments of the invention are illustrated in the drawings and will be explained in more detail in the following description, wherein like reference numerals refer to the same or similar or functionally identical features.

Fig. 1

einen Längsschnitt durch eine erfindungsgemäße Gasturbine,

Fig. 2

eine Darstellung wie in Fig. 1, jedoch bei einer anderen Ausführungsform,

Fig. 3

einen Längsschnitt durch einen Hochdruckverdichter.

It show, each schematically

Fig. 1

a longitudinal section through a gas turbine according to the invention,

Fig. 2

a representation like in Fig. 1 but in another embodiment,

Fig. 3

a longitudinal section through a high pressure compressor.

Ways to carry out the invention

Corresponding Fig. 1 a gas turbine 1 according to the invention comprises a combustion chamber 2 (burner not shown), a stator 5, a rotor 8 and an air cooling device 31 only partially shown and also shown only partially steam cooling device 32. The combustion chamber 2 is of an inner lining 3 and an inner outer lining 4 surrounded. In the direction of flow after the combustion chamber 2, a hot gas stream 28 heated in the combustion chamber 2 strikes at least one row of guide vanes 6 with a plurality of guide vanes 7, which each have an inflow-side region 14 and an outflow-side region 15. This is followed by a blade row 9 with a plurality of blades 10, which form part of the rotor 8.
According to Fig. 1 For example, the steam cooling device 32 comprises a first cooling channel 24, which is arranged in the inner outer lining and is traversed by steam D during operation of the steam cooling device 32. The first cooling channel 24 communicates at the end via an outer cover plate 29 with a third cooling channel 25, which is integrated in the guide blade 7. The third cooling channel 25 is arranged in the inflow-side region 14 of the guide blade 7 and has Outlet openings 27, which communicate with the hot gas stream 28 on an outer side of the respective vane 7. The third cooling channel 27 communicates at the end with hub-side cover elements 11, so that the remaining, not exited through the outlet openings 27 steam D flows into the hub-side cover 11 and this also cools. Similar to the outlet openings 27 on the inflow-side region 14 of the guide vane 7, outlet openings 27 'are provided on the hub-side covering elements 11, from which the vapor D exits into the gas turbine 1 in the region of an inlet 21. The goal here is that most of the vapor D exits through the outlet openings 27 '.

Furthermore, a second cooling channel 23, which runs essentially parallel to the hot gas stream 28 in the direction of the guide vanes 7, is arranged in the inner inner lining 3. The second cooling channel 23 communicates at the end via outlet openings 27 ", which are arranged in the region of the hub-side cover elements 11, with the hot gas stream 28 at the inlet of the gas turbine 1.

The steam D required for the steam cooling device 32 can advantageously be taken from steam generators, not shown, in particular from a waste heat boiler, a startup steam generator or a steam turbine, which is coupled to the gas turbine. An additional steam generator for steam cooling is therefore not needed.

According to Fig. 1 the air cooling device 31 comprises a fourth cooling channel 26 which is integrated into the guide vanes 7 in the downstream region 15. The cooling channel 26 is on the input side with a cooling air source, not shown., An end or intermediate stage of a compressor, connected and output side via outlet openings 27 '' with the hot gas stream 28 and an interior of the Gas turbine 1 communicate. In contrast to the first, second and third cooling channel 24, 23, 25 and the hub-side cover elements 11, the fourth cooling channel 26 is traversed by air L and cooled by it.

Downstream of the guide vane row 6, the blade row 9 is arranged with a plurality of blades 10. The blades 10 are cooled as in conventional gas turbines 1 with air L, which flows in the illustrated embodiment, the rotor side in the blades 10.

The air cooling device 31 is formed according to the illustrated embodiment, both for cooling the blades 10 and arranged downstream of the vanes 7 heat accumulators 19. The cooling of the heat accumulation elements 19 takes place by cooling the side facing away from the hot gas flow 28 side of the heat accumulation elements 19. Additionally or alternatively, according to Fig. 1 Air L are injected directly downstream of the blades 10 in the gas turbine 1 and thus cause and / or enhance a cooling of the heat accumulation elements 19 on the side facing the hot gas flow 28 and the rotor shell 12.

• Das übliche Kühlmedium heißgasführender Bauteile in einer Gasturbine 1 ist Luft L, welche aus einer End- oder Zwischenstufe eines nicht dargestellten Verdichters entnommen wird. Kritische Stellen sind dabei die innenliegende Innenverkleidung 3 und die innenliegende Aussenverkleidung 4 der Brennkammer 2, die erste Leitschaufelreihe 6, die erste Laufschaufelreihe 9 sowie der Turbinenrotor 8.

In the following, the mode of operation of the combined air / steam cooling of the gas turbine 1 according to the invention will be explained briefly:

• The usual cooling medium of hot gas components in a gas turbine 1 is air L, which is taken from an end or intermediate stage of a compressor, not shown. Critical places are the inner lining 3 and the inner outer lining 4 of the combustion chamber 2, the first row of vanes 6, the first row of blades 9 and the turbine rotor 8.

In order to increase turbine performance and extend the life of the gas turbine 1, the invention proposes combined cooling by means of steam D and air L.

The preferably slightly superheated steam D of the steam cooling device 32 flows into designated cooling channels 23 of the inner lining 3 (inner liner) and cooling channels 24 of the inner outer lining 4 (outer liner) from the burner side.

The inflowing steam D emerges from the end of the second cooling channel 24 and is then forwarded via a guide blade outer cover plate 29 into an adjoining third cooling channel 25. After cooling the outer cover plate 29 and the flown portion 14 of the guide vane 7, the steam D flows into the hub-side cover plate 11 of the guide vane 7 and through outlet openings 27 'in the gas turbine 1. At the same time the steam D flows through outlet openings 27 in the upstream region 14 of the vanes 7 in the gas turbine 1. The goal here is that the majority of the steam D exits at the hub.

Another vapor stream D is fed to the inner liner 3 on the burner side and flows through cooling channels 23 of the inner liner 3 parallel to the hot gas flow 28 to the outlet opening 27 "in the region of the hub side cover 11. The two vapor streams D of the inner liner 3 and the hub side cover plate 11 form Due to the higher density of the steam D compared to the hot gas stream 28 during the expansion along the turbine 1 downstream of the guide vanes 7 a steam curtain or film 13 of a certain current thickness along the rotor shell 12 or edge of the hot gas stream 28. This steam film 13 protects the rotor eighth before contact with the hot gas stream 28 and leads thereby to an extended life of the critical components of the gas turbine. 1

The inner lining 3 and the inner outer lining 4 are cooled with steam D. The amount of steam required for this is about 50% of the amount of cooling air. The need for cooling slightly superheated steam D is preferably taken from a waste heat boiler, not shown. It can be provided that both the first cooling channel 24 and the second cooling channel 23 from a common or from a separate waste heat boiler (s) can be fed.

The power of the gas turbine 1 operated with the combined air or steam cooling increases by about 2 to 5 percent compared with the conventional air-cooled gas turbine, which can be explained as follows in a combined gas turbine steam turbine plant: The steam turbine power decreases as a result of the removal slightly overheated steam D from the waste heat boiler slightly, whereas the heat output of the waste heat boiler increases as a result of the larger amount from the gas turbine. Almost the largest part of this power is therefore recovered as a result of the relaxation of the steam after cooling the inner lining 3,4 and the guide vanes 7 at a much higher temperature and up to 1 bar in the gas turbine 1. The saved amount of cooling air of the guide vanes 7 flows through the combustion chamber 2 and participates in the combustion process, whereby an additional power of the gas turbine 1 is achieved.

Corresponding Fig. 2 the gas turbine 1 is shown in another embodiment, which is designed to carry out a sequential combustion. For this purpose, in addition, a high-pressure combustion chamber 2 'and a Hochdruckleitschaufelreihe 22 with several high-pressure guide vanes 16 and at least one high-pressure blade row 17 is provided with a plurality of high-pressure blades 18, which are followed downstream of a low-pressure combustion chamber, not shown, and a low-pressure turbine.
Here, the high pressure blades 18 and the high pressure vanes 16 are cooled at least in their Anströmbereich with steam D, while the trailing edges of the high pressure vanes 16 can be cooled either also with steam or conventional with air. The design of the various cooling channels is designed so that a certain amount of steam flows through the high-pressure guide vanes 16 into the hub-side cover elements 11. A large part of the steam D then flows similar to in Fig. 1 via outlet openings 27 'in the gas turbine 1 a. The other part of the steam D flows into a gap 30, which is arranged below the rotor shell 12 and between the high pressure vanes 16 and the high pressure blades 18, to be sucked from there by the high pressure blades 18 for cooling. At the same time, a portion of the steam D blocks the described gap 30 between Hochdruckleit- and high-pressure blades 16,18 with a certain amount of blown steam D. The remaining components are air-cooled.

Also at the in Fig. 2 illustrated gas turbine 1 with sequential combustion generated by the outlet openings 27 'vapor D produced a vapor film 13 which surrounds the rotor shell 12 and protects it from direct contact with the hot gas stream 28.

According to Fig. 3 an embodiment variant for cooling a high-pressure compressor 20 is shown. Here, suitable heat accumulation elements 19 are arranged between the high-pressure guide vanes 16 and the high-pressure blades 18 on the rotor shell 12 and with slightly superheated steam D, which at Fed to the end of the high pressure compressor 20 and after a certain distance at the end of the high pressure compressor 20 is returned, cooled.

• Die Erfindung sieht vor, bei einer Gasturbine 1, welche mit einer herkömmlichen Luftkühleinrichtung 31 zur Kühlung von Teilen der Gasturbine 1 mittels Luft ausgebildet ist, zusätzlich eine Dampfkühleinrichtung 32 vorzusehen, welche zur Kühlung von Teilen der Gasturbine 1 mittels Dampf ausgebildet ist.

In summary, the essential features of the solution according to the invention can be characterized as follows:

• The invention provides, in a gas turbine 1, which is formed with a conventional air cooling device 31 for cooling parts of the gas turbine 1 by means of air, in addition to provide a steam cooling device 32, which is designed to cool parts of the gas turbine 1 by means of steam.

The cooling of the rotor 8 and the stator 5 is carried out conventionally with air L. In addition, now flows a small amount of steam from the inlet 21 into the gas turbine 1 to the exit from the gas turbine 1 along the rotor shell 12 parallel to the hot gas stream 28. Due to the higher density of the vapor D compared to the hot gas stream 28 thereby remains a vapor film 13 on the rotor shell 12 and protects it from direct contact with the hot gas stream 28.

The advantages of the invention are that the power of the additionally cooled with steam D gas turbine 1 compared to the conventional air-cooled gas turbine 1, for example by about 2 to 5%, increases and at the same time due to the vapor film 13 a longer life of the critical components can be achieved ,

LIST OF REFERENCE NUMBERS

1

gas turbine

2

combustion chamber

3

inside lining

4

internal outer panel

5

stator

6

vane row

7

vane

8th

rotor

9

Blade row

10

blade

11

hub-side cover elements

12

rotor shell

13

vapor film

14

on the upstream side

15

downstream area

16

Hochdruckleitschaufel

17

High pressure blade row

18

High pressure blade

19

Heat storage elements

20

High-pressure compressors

21

entry

22

Hochdruckleitschaufelreihe

23

second cooling channel

24

first cooling channel

25

third cooling channel

26

fourth cooling channel

27

outlet opening

28

Hot gas stream

29

Outer cover plate

30

gap

31

Air cooling device

32

Steam cooling device

D

steam

L

air

Claims (14)

1. Gas turbine (1), in particular in a power plant,

   - with at least one combustion chamber (2) and with an inner cladding (3) lying on the inside and surrounding the combustion chamber (2), and with an outer cladding (4) lying on the inside,

   - with a stator (5) which has at least one guide vane row (6) with a plurality of guide vanes (7),

   - with a rotor (8) which has at least one rotor vane row (9) with a plurality of rotor vanes (10),

   - with an air cooling device (31) which is configured for cooling parts of the gas turbine (1) using air (L),

   - wherein additionally, a steam cooling device (32) is provided which is configured for cooling the guide vanes (7) and/or hub-side cover elements (11) of the guide vanes (7) using steam (D),
   characterised in that

   - the steam cooling device (32) is configured for cooling the inner cladding (3) lying on the inside and/or the outer cladding (4) lying on the inside, and

   - a steam guide is configured such that a steam film (13) is produced from the guide vane row (6) along a rotor shell (12).
2. Gas turbine according to claim 1, characterised in that a second cooling channel (24) is formed in the outer cladding (4) lying on the inside, and that a guide vane outer cover plate (29) conducts the steam emerging from the second cooling channel (24) into a third cooling channel (25).
3. Gas turbine according to claim 1 or 2, characterised in that a first cooling channel (23) is formed in the outer cladding (3) lying on the inside, and that an outlet opening (27") of the first cooling channel (23) is arranged in the region of the hub-side cover elements (12) of the guide vanes (7).
4. Gas turbine according to any of the preceding claims, characterised in that the guide vanes (7) comprise outlet openings, and that the outlet openings conduct the in-blown steam into the hot gas flow.
5. Gas turbine according to any of the preceding claims, characterised in that the air cooling device (31) is configured at least for cooling the rotor vanes (10) and/or heat build-up elements (19) arranged downstream of the guide vane row (6).
6. Gas turbine according to any of the preceding claims, characterised in that the steam cooling device (32) is configured for cooling the guide vanes (7) in an inflow-side region (14), and the air cooling device (31) is configured for cooling the guide vanes (7) in an outflow-side region (15).
7. Gas turbine according to any of the preceding claims, characterised in that

   - the gas turbine (1) is configured for performing a sequential combustion,

   - in addition, a high-pressure combustion chamber (2') is provided which is provided with an inner cladding (3) lying on the inside and surrounding this, and with an outer cladding (4) lying on the inside,

   - at least one high-pressure guide vane row (22) is provided with a plurality of high-pressure guide vanes (16),

   - at least one high-pressure rotor vane row (17) is provided with a plurality of high-pressure rotor vanes (18).
8. Gas turbine according to claim 7, characterised in that

   - the steam cooling device (32) is configured at least for cooling the high-pressure guide vanes (16) and/or hub-side cover elements (11) of the high-pressure guide vanes (16) and/or the high-pressure rotor vanes (18), and/or

   - a steam guide is configured so that a steam film (13) is produced from the high-pressure guide vane row (22) along a rotor shell (12).
9. Gas turbine according to claim 7 or 8, characterised in that the air cooling device (31) is configured at least for cooling the inner cladding (3) lying on the inside of the high-pressure combustion chamber (2') and/or the outer cladding (4) lying on the inside of the high-pressure combustion chamber (2') and/or the rear edge of the high-pressure guide vanes (16) and/or heat build-up elements (19) arranged downstream of the high-pressure guide vane row (22).
10. Gas turbine according to one of claims 7 to 9, characterised in that the steam cooling device (32) is configured for at least partially cooling a high-pressure compressor (20).
11. Gas turbine according to any of claims 7 to 10, characterised in that the steam cooling device (32) is connected, for extraction of steam (D), to a waste heat boiler of the steam turbine which is coupled to the gas turbine (1).
12. Method for cooling a gas turbine (1), in particular in a power plant, comprising

    - a combustion chamber (2) with an inner cladding (3) lying on the inside and surrounding the combustion chamber (2), and with an outer cladding (4) lying on the inside,

    - a stator (6) which has at least one guide vane row (6) with a plurality of guide vanes (7),

    - a rotor (8) which has at least one rotor vane row (9) with a plurality of rotor vanes (10),

    - in which parts of the gas turbine (1) are cooled by an air cooling device (31) using air (L), while the guide vanes (7) and/or the hub-side cover elements (11) of the guide vanes (7) are cooled by a steam cooling device (32) using steam (D),

    characterised in that via a steam guide, a steam film is produced from the guide vane row (6) along a rotor shell (12), and the steam cooling device (32) cools the inner cladding (3) lying on the inside and/or the outer cladding (4) lying on the inside.
13. Method according to claim 12, characterised by the characteristic features of at least one of claims 2 to 9.
14. Method according to claim 12 or 13, characterised in that the steam blown in for cooling the guide vanes (7) emerges via outlet openings into the hot gas flow and produces a steam film on the outer skin of the respective guide vane (7).

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