EP2229507B1 - Gas turbine - Google Patents

Description

Technical area

The present invention relates to the field of gas turbine technology. It relates to a gas turbine according to the preamble of claim 1, which in US 4733538 A is disclosed.

State of the art

Gas turbines have long been firmly established in power generation in their stationary form. These are high performance machines whose efficiency is constantly improving. An example of the achieved level of development is the Applicant's type GT24 / GT26 gas turbines, which are equipped with a 2-stage, sequential combustion, and which are described, for example, in the article F. Joos et al., "Field experience with the sequential combustion system of the GT24 / GT26 gas turbine family", ABB review 5, p.12-20 (1998 ) are described. Sucked air is compressed in a compressor and fed to a first burner assembly where it is used to combust a injected fuel. This first burner arrangement consists of premix burners, which have also become known in professional circles as EV-AEV burners. Such burners go out, for example EP-0321809 A1 respectively. EP-0704657 A1 These publications as well as other publications related to this technology form an integral part of this application. The hot gas produced by this combustion is first partially expanded in a high-pressure turbine and then introduced into a second burner arrangement (known to those skilled in the art as the SEV burner), where the proportion of unused air is used for a second combustion. The hot gas from the SEV burners is then relaxed in a low pressure turbine. The exhaust gases are then finally used for example to generate steam in a heat recovery steam generator.

On the output side of the SEV burner, the hot gas flow hits the first row of the vanes of the low-pressure turbine. This configuration is eg in the US B1-6,751,962 or the EP-A2-1 505 254 described and is in Fig. 1 This description reproduced in sections, wherein the cited documents are an integral part of the present description. In the gas turbine 10 of Fig. 1 The hot gas 12 flowing out of the combustion chamber outlet 11 impinges on the leading edge of the vanes 15 of the first vane ring, which is arranged at the input of the turbine. The combustion chamber outlet 11 is bounded laterally by a limiting element 19. Between the end of the limiting element 19 and the first row of guide vanes (15) there is a gap 16, which is sealed to the outside by an annular seal 17. By flushing openings 18 in the seal 17 and leaks purge air enters the gap 16 and prevents ingress of hot gas. Cooling air is also injected through cooling holes 20, 21 in the limiting element, as in the above-mentioned US B1-6,751,962 is described.

The rapidly flowing hot gas produces various effects at the transition to the turbine. On the one hand, at the leading edge of the guide vanes 15, a rearward bow wave 13 is created which faces the pressure gradient upstream of the suction side 24a, 24b, 24c, 24d towards the pressure side 25a, 25b, 25c. 25d is superimposed. On the other hand, a characteristic pressure distribution is generated by the complicated flow conditions in the burners or combustion chambers with swirling elements which are usually present at the combustion chamber outlet 11, which can be referred to as burner shaft 14.

The unequal distribution of the pressure at the combustion chamber outlet 11 may in practice be of the same order of magnitude as the pressure changes resulting from the bow wave 13 at the guide vanes 15. The overlay of both Effects (bow wave 13 and burner shaft 14) can thus lead to a situation in which the amplitude of the bow wave is effectively doubled, thus escaping hot gas from the hot gas channel. These flow conditions occur both in gas turbines with a combustion chamber and in gas turbines with a sequential combustion, so over 2 combustion chamber (EV respectively AEV and SEV), respectively at the transition from the burners to the turbine.

In US-A-4,733,538 , which is the preamble of independent claim 1, a gas turbine assembly is described with a plurality of individual burners, which are arranged concentrically to the axis of rotation. The first vane row is preceded in the circumferential direction by a likewise arranged around the axis of rotation ring plate with a plurality of each with equal intervals to each other arranged cooling air openings from which cooling air occurs exclusively for purposes of cooling the first row of vane. Thus, the cooling air openings only contribute to the most uniform possible temperature distribution immediately after the combustion chamber outlet and upstream to the first row of guide blades.

The publication EP-A-0 902 164 is concerned with a platform cooling system for gas turbines, in which segment cooling holes and platform cooling holes open into the intermediate gap between a downstream combustion chamber segment and a first row of guide blades. The cooling measures are solely for the cooling of the thermally heavily loaded spaces within said intermediate gap.

Presentation of the invention

It is an object of the invention to design the gas turbine so that the unfavorable effects of the bow wave and the burner shaft are avoided at the transition between the combustion chamber and the turbine inlet.

The object is solved by the entirety of the features of claim 1. Essential for the solution found is that the cooling holes in the first Split the cooling groups and second cooling hole groups, that the arrangement of the first cooling hole groups in their periodicity of the arrangement of the guide vanes corresponds in their periodicity, and that the arrangement of the second cooling hole groups in their periodicity of the regular arrangement of the burners in their periodicity.

• Die Strömungen am Brennkammerauslass sind wegen der Konfiguration der Brenner mit ihren Strömungswirbeln, lokalen Effekten der Wandkühlung und Leckageluft ungleichförmig.
• Daraus resultiert eine ungleichförmige Verteilung der Spül- und Leckageluft im Spalt zwischen Brennkammerauslass und Turbineneingang.
• Wenn die Kühlöffnungen an den Stellen angeordnet werden, wo der höchste Druck in der Strömung auftritt, können diese Effekte ausgeglichen werden.

This solution is based on the following considerations:

• The flows at the combustor outlet are non-uniform because of the configuration of the combustors with their fluid flows, local wall cooling effects, and leakage air.
• This results in a non-uniform distribution of the rinsing and leakage air in the gap between the combustion chamber outlet and the turbine inlet.
• If the cooling holes are located at the places where the highest pressure in the flow occurs, these effects can be compensated.

The invention relates to the interface of burner and turbine in gas turbines with 1 or 2 burner assemblies resp. Combustion chambers.

The number of burners used, in particular, in the abovementioned combustion chambers is often not equal to the number of guide vanes, in particular smaller than the number of vanes.

According to another embodiment of the invention, the burners are arranged in the second stage of a gas turbine with two-stage or sequential combustion.

A further embodiment is characterized in that the cooling openings of the first cooling opening groups have an undefined position with respect to the leading edges of the guide vanes, typically slightly upstream from the leading edge, and the cooling openings of the second cooling opening groups are aligned transversely to the hot gas flow.

A particularly preferred embodiment of the invention is characterized in that between the Brennkammerauslässen and the first row of guide vanes of the turbine, a circumferential gap is provided, which is flushed by circumferentially spaced flushing holes flushed with purging air, and that the flushing holes are divided into groups whose arrangement the arrangement of the vanes and / or the regular arrangement of the burner corresponds.

Advantageous and expedient developments of the inventive task solution are characterized in the dependent claims.

Brief explanation of the figures

Fig. 1

in einem Ausschnitt einen Übergang zwischen den Brennkammerauslässen und der ersten Leitschaufelreihe einer Gasturbine, wie er zur Verwirklichung der Erfindung geeignet ist; und

Fig. 2

in einer schematischen Darstellung die unterschiedliche Periodizität von Leitschaufeln und Brennern, nach welcher sich gemäss der Erfindung die Anordnung der Kühlöffnungsgruppen richtet.

The invention will be explained in more detail with reference to embodiments in conjunction with the drawings. All elements not required for the immediate understanding of the invention are omitted. The direction of flow of the various media are indicated by arrows. In the various figures, the same elements are provided with the same reference numerals. Show it

Fig. 1

in a section, a transition between the Brennkammerauslässen and the first row of guide vanes of a gas turbine, as it is suitable for implementing the invention; and

Fig. 2

in a schematic representation of the different periodicity of vanes and burners, according to which the arrangement of the cooling port groups according to the invention.

Ways to carry out the invention

In Fig. 2 is a schematic representation of the different periodicity of vanes 15a, b, c, d and burners 22a, b, c reproduced, according to which the arrangement of the cooling holes 18, 20 and 21 is directed according to the invention.

The cooling holes 20 according to Fig. 1 , which are directed to the vanes 15, are to, as out Fig. 2 divided into cooling port groups 20a, b, c, and d, which form distributed over the circumference of a cooling opening row A. How to further in Fig. 2 2, each vane 15a, b, c, d is associated with a cooling port group 20a, b, c, d, the periodicity of the cooling port groups 20a, b, c, d being equal to the periodicity of the vanes 15a, b, c, d. Specifically, the cooling port groups 20a, b, c, d are associated with the leading edges of the vanes 15a, b, c, d at which the bow shaft 13 is formed as shown in FIG Fig. 1 is shown. The cooling holes are typically arranged somewhat on the pressure side of the front edges in order to even out the pressure difference from the pressure side to the suction side.

The cooling openings 21, which inject cooling air transversely into the combustion chamber outlet 11, are likewise combined into cooling-opening groups, of which FIG Fig. 2 only the one cooling opening group 21 'is shown and a cooling opening row B indicates. The periodicity of the cooling port groups 21 'is equal to the periodicity of the burners 22a, b, c. In the example of Fig. 2 For example, the cooling opening groups 21 'are arranged directly in the middle of the combustion chamber outlets and thus aligned with the burner lances 23 a, b located in the middle. Other arrangements of the same periodicity are conceivable and depend on the specific flow conditions at the combustion chamber outlet.

By aligning the two cooling opening groups 20a, b, c, d and 21 'in the rows of cooling holes A and B on the vanes 15a, b, c, d and the burners 22a, b, c, the amplifying, undesirable effects of Bug waves 13 and burner waves 14 are easily attenuated or made harmless.

An additional possibility of influencing results if, for the rinsing openings 18 associated with the gap 16, comparable periodicities of opening groups are introduced, which are optionally aligned with the periodicity of the guide vanes 15a, b, c, d or the burners 22a, b, c or both can. As a result, unequal distributions in the gap region, which result from the superposition of bow waves 13 and burner waves 14, can be directly compensated.

Finally, an embodiment not shown in the figures described is briefly commented. Related to the Fig. 1 are possible within the hot gas flow channel embodiments in which not only an inner circumferential gap 16 is present in the circumferential direction, but also on the outer circumferential side of this hot gas flow channel also an outer circumferential gap is present, which largely fulfills the same attributes. In such a case, first and / or second cooling opening groups (20, 21) are also provided in the region of this outer circumferential gap, which fulfill the same final purpose as in the region of the gap 16 shown.

LIST OF REFERENCE NUMBERS

10

gas turbine

11

combustor

12

hot gas

13

Bow wave (vane)

14

Brenner wave

15; 15a, b, c, d

vane

16

Gap (circulating)

17

Seal (ring-shaped)

18

flushing opening

19

limiting element

20;

cooling vent

20a, b, c, d

Cooling opening group

21

cooling vent

21 '

Cooling opening group

22a, b, c

burner

23a, b

burnerlance

24 a, b, c, d

Suction side of the vane

25a, b, c, d

Pressure side of the vane

Claims (9)

1. Gas turbine (10) in which a first plurality of burners (22a, b, c) arranged regularly and concentrically relative to a rotation axis each conduct hot gas (12) through an associated combustion chamber outlet (11) into a turbine, at the inlet of which a second plurality of guide vanes (15; 15a, b, c, d) is arranged evenly spaced in a ring around the rotation axis, and wherein cooling ports (20; 21) are provided distributed around the periphery, through which cooling air can be injected into the hot gas flow at the combustion chamber outlet (11), characterised in that the cooling ports (20; 21) are arranged in the region of an inner peripheral and/or outer peripheral gap (16) relative to the channel formed by the hot gas flow (12), and are subdivided into first groups of cooling ports (20a, b, c, d) and second groups of cooling ports (21'), that the arrangement of the first groups of cooling ports (20a, b, c, d) corresponds in its periodicity to the periodicity of the arrangement of the guide vanes (15; 15a, b, c, d), and the arrangement of the second groups of cooling ports (21') corresponds in its periodicity to the periodicity of the regular arrangement of the burners (22a, b, c).
2. Gas turbine according to claim 1, characterised in that the inner peripheral and/or outer peripheral gap lies in the region of or upstream of the guide vanes.
3. Gas turbine according to claim 1, characterised in that the burners (22a, b, c) are evenly spaced from each other.
4. Gas turbine according to any of claims 1 to 3, characterised in that the number of burners (22a, b, c) is not equal to the number of guide vanes (15; 15a, b, c, d), in particular is smaller than the number of guide vanes (15; 15a, b, c, d).
5. Gas turbine according to any of claims 1 to 4, characterised in that the burners (22a, b, c) are arranged in the second stage of a gas turbine (10) with two-stage or sequential combustion.
6. Gas turbine according to any of claims 1 to 5, characterised in that the cooling ports (20) of the first group of cooling ports (20a, b, v, d) are oriented towards the leading edges of the guide vanes (15; 15a, b, c, d), and the cooling ports (21) of the second group of cooling ports (21') are oriented transversely to the hot gas flow (12).
7. Gas turbine according to any of claims 1 to 6, characterised in that a peripheral gap (16) is provided between the burner chamber outlets (11) and the first row of guide vanes (15; 15a, b, c, d) of the turbine, which gap is flushed with flushing air through flushing openings (18) distributed around the periphery, and that the flushing openings (18) are divided into groups, the arrangement of which corresponds to the arrangement of the guide vanes (15; 15a, b, c, d) and/or the regular arrangement of the burners (22a, b, c).
8. Method for operating a gas turbine (10) according to any of claims 1 - 7, wherein the gas turbine has a first plurality of burners (22a, b, c) arranged regularly and concentrically relative to a rotation axis, these burners have an associated combustion chamber outlet (11) through which hot gas (12) is injected for loading a turbine, wherein at the turbine inlet a second plurality of guide vanes (15; 15a, b, c, d) is operated which are arranged evenly spaced in a ring around the rotation axis, and wherein cooling ports (20; 21) distributed around the periphery act, through which cooling air can be injected into the hot gas flow (12), characterized in that at least one inner peripheral gap (16) is present in the region of or upstream of the guide vanes, that to prevent the intrusion of hot gas (13, 14) through this gap (16), outer peripheral cooling ports (20; 21) oriented towards the hot gas flow (16) act which are subdivided into first groups of cooling ports (20a, b, c, d) and second groups of cooling ports (21'), and that the arrangement of the first groups of cooling ports (20a, b, c, d) corresponds in its periodicity to the periodicity of the arrangement of the guide vanes (15; 15a, b, c, d), and the arrangement of the second groups of cooling ports (21') corresponds in its periodicity to the periodicity of the regular arrangement of the burners (22a, b, c).
9. Method according to claim 8, characterised in that at least one outer peripheral gap is present in the region of or upstream of the guide vanes, and to prevent the intrusion of hot gas through this gap, outer peripheral cooling ports oriented towards the hot gas flow (12) act which are subdivided into first groups of cooling ports and second groups of cooling ports, that the arrangement of the first groups of cooling ports in its periodicity corresponds to the periodicity of the arrangement of the guide vanes (15; 15a, b, c, d) and that the arrangement of the second groups of cooling ports (21') corresponds in its periodicity to the periodicity of the regular arrangement of the burners.

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