EP2417394B1 - Combustion chamber having a helmholtz damper - Google Patents

Description

Technical area

The present invention relates to a combustion chamber according to the preamble of claim 1.

State of the art

The solution to the problem of thermoacoustic oscillations in modern low NOx combustion chambers of gas turbines is becoming increasingly important. It has therefore been variously proposed in the prior art to arrange on the combustion chamber of a gas turbine so-called Helmholtz damper, which due to their configuration in which a damping volume communicates via a thin connecting channel with the combustion chamber, are capable of certain vibration frequencies in the combustion chamber effectively dampen.

Since the occurring in a combustion chamber thermoacoustic oscillations in frequency and amplitude are influenced by a variety of geometric and operating parameters of the combustion chamber, the expected vibrations can be predicted very difficult and incomplete in a new combustion chamber. It may therefore be that the Helmholtz damper used on the combustion chamber are not optimally adapted to the vibrations actually occurring in the combustion chamber, especially if this combustion chamber have to cover wide operating behavior.

It is therefore, for example, in EP-A1-0 597 138 , Has been proposed to form the Helmholtz damper completely or partially interchangeable to make subsequent changes in the spectrum of resonant frequencies occurring can. For this purpose, a so-called manhole has been proposed in the turbine housing as a measure, by which the replacement of the Helmholtz damper can be done.

The disadvantage here is that on the one hand, the vote on a resonant frequency can be done only in stages, that the replacement of damper parts or whole dampers is very expensive, and that for the exchange regularly a significant design effort on the turbine housing and the combustion chamber itself must be driven.

Furthermore, the document is from the prior art EP 02 782 607.2 became known, which shows how a Helmholtz damper is installed in a combustion chamber. The final purpose here is to form the Helmholtz damper such that its damping frequency is adjustable, and in particular is designed to be continuously adjustable. As a result, the damping can be easily adapted to the thermoacoustic behavior of the combustion chamber and optimized accordingly. An exchange of parts or entire dampers is not required, so that can be dispensed with corresponding large-sized access options. At the same time eliminated by the adjustability of the Helmholtz damper the need for different resonant frequencies differently configured damper or damper parts manufacture and ready.

The installation of these Helmholtz dampers is related to a combustion chamber of a gas turbine, which is operated with Vormischbrennern the newer generation. These Helmholtz damper are provided on the inlet side of the combustion chamber, which is formed for example with two rings of premix burners and arranged therebetween, adjustable Helmholtz damper. The gas turbine itself is enclosed by a gas turbine housing within which is a plenum filled with compressed air. The plenum surrounds the combustion chamber, which is separated from the plenum by a combustion chamber housing. The arrangement of the combustion chamber within the gas turbine is substantially the same as in the aforementioned document EP-A1-0 597 138 described. Within of the combustion chamber housing, the combustion chamber is bounded on the inlet side by a front cover. The combustion chamber is further annular and equipped with said Vormischbrennern, as for example in the base protection rights EP-0 321 809 A1 or EP-0 704 657 A1 , and in the following developments, all of which here constitute an integral part of this application.

The premix burners are arranged in corresponding openings in the front cover and open into the combustion chamber. To dampen the excited in the combustion chamber during the combustion process thermoacoustic oscillations Helmholtz dampers are provided between the burners. These Helmholtz damper each have a damping volume, which is composed of a fixed cylindrical and a variable cylindrical damping volume. The damping volume is connected to the combustion chamber via a comparatively narrow connection channel. The arrangement of connecting channel and damping volume forms a damping resonator whose resonant frequency is determined inter alia by the size of the damping volume.

Such a configuration clearly demonstrates that such incorporation of the Helmholtz dampers between the premix burners takes up relatively much space within the annular combustor, which can inevitably entail some constriction in the design and placement of the premix burners. Also, it must not be ignored that both installation and removal of such Helmholtz damper is interdependent to those of Vormischbrenner, whereby the originally proposed arrangement between premix burners and Helmholtz damper can not be changed later without further notice. This results in restrictions that are individually opposed to the particular needs of the operation of the combustion chamber with respect to the rapid and targeted action taken by measures against the advent of thermoacoustic vibrations or this does not meet to a sufficient extent.

DE 10 2005 062 284 A1 discloses a combustor for a gas turbine having multiple burners and at least one Helmholtz resonator for suppressing thermoacoustic oscillations. From this document it follows that the positions for the burner and possibly the arrangement of the Helmholtz resonators are interchangeable, so even an arrangement of a Helmholtz resonator instead of a burner can be mounted.

DE 100 58 688 A1 discloses a gas turbine having a plurality of burners and damping elements. The positions of the burners and the damping elements are interchangeable, that the openings in the turbine housing for the burner or for the damping elements are identical. In addition, this publication discloses that the burners and / or the damping elements can be arranged both adjacent to each other and radially adjacent to each other. DE 100 58 688 A1 discloses a combustion chamber according to the preamble of claim 1. EP 1 605 209 A discloses a Helmholtz resonator integrated into a combustion chamber element to be cooled with an opening open toward the combustion chamber. The combustion chamber element to be cooled has a screw provided with a through bore which serves for fastening a heat shield and protrudes with a height H into the resonator chamber. The protruding into the resonator cavity part of this screw is considered as a tuning tube. Although the person skilled in the art could derive a tuning tube in the front part of the resonance volume from this situation, further findings can not be derived therefrom.

WO 03/060381 A1 describes a arranged on a combustor for gas turbines Helmholtz damper whose damping volume communicates via a connecting channel with the combustion chamber. The Helmholtz damper is designed such that its damping frequency is adjustable. For this purpose, the damping volume is divided into a fixed and a variable part. A change in the damping volume is achieved by a change of the variable part, in that the variable damping volume is limited for example on one side by a displaceable piston.

Presentation of the invention

The invention aims to remedy this situation. The invention as characterized in the claims, the object is to design the execution of a Helmholtz damper of the type mentioned so that it can be used without fundamental modifications to the combustion chamber as needed, place and number manifold, and on the respective damping to be achieved provides a simple adjustment.

The main advantages of the invention are to be seen in that the Helmholtz damper can be used instead of a wegem removed premix burner of the known type. In particular, it should be pointed out that due to the progress in premix combustion in the annular combustion chamber, premix burners can now be used whose number for the same power is less than the number of premix burners originally provided, so that some burner positions are no longer needed in such repowering of the annular combustion chamber and therefore the vacant position is also available.

Thus, this results in an unforeseen possibility that for the installation of Helmholtz damper the free resp. Burner positions that have been freed up can be used without any disadvantages arising with regard to the combustion chamber operating concept.

Another advantage of the invention lies in the fact that the exact arrangement of the Helmholtz damper can be optimized by means of a previously carried out thermoacoustic simulation, bearing in mind that now sufficient Einstellvariationen are available, so that in the installation of such a Helmholtz damper not in any form is limited, neither in terms of the number, nor the position to be assigned within a composite of Vormischbrennern. Accordingly, these Helmholtz damper can be easily installed in the places where they also maximized Give damping effect, because if incorrectly positioning only a single Helmholtz damper, it may easily happen that overall no satisfactory effect is achieved.

Another advantage of the invention is the fact that the given space can be optimally utilized by a maximum damping volume by the Helmholtz damper proposes not to provide the tuning tube upstream, as is usually the case, but to protrude deep into the damping volume, which has a positive effect on the space available for installation.

Another advantage of the invention is the fact that measures against the thermal load acting there is remedied on the exposed positioning of the Helmholtz damper. These measures consist of initially providing efficient impingement cooling, which cools the front surface of the Helmholtz damper. For this purpose, the Helmholtz damper is equipped with a special transition piece with radial air supply holes through which the cooling medium is supplied.

Another significant advantage of the invention is the fact that the Helmholtz damper for adjusting the frequency directly from the outside, without removal or removal of any covers, is fully accessible.

A further advantage of the invention is that the Helmholtz damper is designed to not only have axial flexibility within the combustion chamber in relation to the other various components, but also to provide lateral compliance so as to have a space constraint is not given during installation, and otherwise behaves compliant during operation.

Further advantages of the invention will become apparent from the dependent claims.

Brief explanation of the figures

Fig. 1

eine Konfiguration von Vormischbrenner mit dem Einbau eines Helmholtzdämpfer nach dem Stand der Technik;

Fig. 2

der Einbau eines Helmholtzdämpfers an Stelle eines Vormischbrenners;

Fig. 3

der Einbau eines Helmholtzdämpfers zwischen zwei Vormischbrennern;

Fig. 4

der vordere Teil des Helmholtzdämpfers mit gekühlter Frontfläche und Abstimmrohr und

Fig. 5

einen Schnitt durch den hinteren Teil eines Helmholtzdämpfers.

The invention will be explained in more detail with reference to an embodiment in conjunction with the drawings. All elements not required for the immediate understanding of the invention have been omitted. The same elements are provided in the various figures with the same reference numerals. Show it:

Fig. 1

a configuration of Vormischbrenner with the installation of a Helmholtz damper according to the prior art;

Fig. 2

the installation of a Helmholtz damper in place of a premix burner;

Fig. 3

the installation of a Helmholtz damper between two premix burners;

Fig. 4

the front part of the Helmholtz damper with a cooled front surface and tuning tube and

Fig. 5

a section through the rear of a Helmholtz damper.

Ways to carry out the invention

In Fig. 1 is in a section in cross-section the inlet side of the combustion chamber of a gas turbine with, as already mentioned above, two rings of double-cone burners and an interposed, adjustable Helmholtz damper according to a belonging to the prior art design. The gas turbine 10 is enclosed by a gas turbine housing 11 within which a filled with compressed air plenum 12 is located. The plenum 12 surrounds the combustion chamber 16, which is separated from the plenum 12 by a combustion chamber housing 13. The arrangement of the combustion chamber 16 within the gas turbine 10 is substantially the same as in the aforementioned document EP-A1-0 597 138 described. Within the combustion chamber housing 13, the combustion chamber 16 is bounded on the inlet side by a front cover 26. The combustion chamber 16 is annular and is equipped with so-called premix burners 14, 15, which are known by the applicant as EV burners or AEV burners, and are well known in the art, and are arranged in rings around the axis of the gas turbine, such as this in the EP-A1-0 597 138 or in EP 0 976 982 B1 , especially Fig. 2 , is disclosed.

The premix burners 14, 15 are arranged in corresponding openings in the front cover 20 and open into the combustion chamber 16. To dampen the excited in the combustion chamber 16 during the combustion process thermoacoustic oscillations between the rings with the burners 14, 15 Helmholtz damper 17 are provided. These Helmholtz damper 17 have a damping volume that is composed of a fixed cylindrical and a variable cylindrical damping volume. The damping volume is connected to the combustion chamber 16 via a comparatively narrow connection channel 18. The arrangement of connecting channel 18 and damping volume forms a damping resonator, the resonant frequency of which is determined inter alia by the size of the damping volume, this connecting channel 18 communicating directly with the combustion chamber. The installation of such a Helmholtz damper requires a previous specific installation structure, which leads to a fixed positioning of the Helmholtz damper.

Fig. 2 shows a same output configuration of the combustion chamber 16 as in FIG Fig. 1 ,

The original premix burner 15 off Fig. 1 is replaced by a Helmholtz damper 30. This Helmholtz damper 30 is designed so that it can therefore be replaced with a premix burner. As far as this implementation is concerned, the Helmholtz damper 30 and in the front plate already existing there can be radially guided and axially freely installed, so that such an installation does not require any special mounting structure. On the special Design of this Helmholtz damper 30 is described in the description of Fig. 4 and 5 discussed in more detail.

Another way of installing such a Helmholtz damper 30 is under Fig. 3 explained in more detail. Here, the Helmholtz damper 30, thanks to its slender held embodiment, even within the annular combustion chamber between two Vormischbrennern 14, 15 install, so wherever a previously made thermoacoustic simulation provides appropriate information. Such a configuration thus allows maximum flexibility in the positioning of the Helmholtz damper 30 within a composite of premix burners, the same also applies if diffusion burners should be provided instead of premix burners.

The insertion of the Helmholtz damper and its frequency setting can then be made readily from the outside, if a corresponding opening is provided in the gas turbine housing 11, as shown in the Fig. 3 is indicated. In addition, an individual regulation of the Helmholtz damper 30 can be accomplished from the outside. Within the combustion chamber housing 13, the anchoring for the Helmholtz damper 30 can be achieved, for example, by utilizing the already existing suspension structure of the premix burner.

Fig. 4 shows the front part 30a of the built-Helmholtz damper 30, wherein it can be seen that a tuning tube 31 is disposed inside. Thus, the length of such a tuning tube 31, which is so important for the effect, can be designed to be very flexible, since the available space within the tube length 30a is large, so that the tuning tube 31 does not have to be stored as usual, but rather deep inside Damping volume 35 can protrude. In such an embodiment, it is also possible to operate with a front surface 32, which is operated by cooling, so that the subsequent tuning tube 31 and the surrounding damping volume 35 are optimally protected against the thermal loads from the combustion chamber space. The cooling medium 33 itself flows via a transition piece 34 and through there radial or quasi-radial openings 33 a in the interior of the damping volume 35 direction Front surface 32 of the Helmholtz damper 30, wherein the front surface 32 is preferably cooled by an efficient impingement cooling. The thermally consumed cooling medium then flows from the front side of the front surface 32, as can be seen from the illustrations in FIGS Fig. 2 and 3 is apparent. Basically, the damping volume 35 is selected so that the damping frequency that can be achieved in the vicinity of the frequency of one of the expected in the combustion chamber thermoacoustic oscillations. The envisaged by the construction described in detail implementation of a tuning tube 31 is achieved that is possible by the design of this tuning tube 31, both in terms of its diameter, its wall thickness, as well as its length, in a newly put into operation gas turbine Helmholtz damper 30th to tune exactly to the occurring vibration frequencies and thus obtain the lowest possible means optimal damping. In addition, the optimal installation position can be determined by a previously performed thermoacoustic simulation. This option is only possible if the installation specifications regarding a Helmholtz damper 30 in accordance with Fig. 2 and 3 are also to be fulfilled.

On the one hand, therefore, the optimal installation position is determined by the thermoacoustic simulation, on the other hand, a finer tuning against thermoacoustic vibrations can be achieved by the proposed construction. These adjustments, which can be implemented individually or in combinations with one another, make it possible to cover a wide variety of oscillation frequencies by a single embodiment of a Helmholtz damper 30, thereby avoiding the need to use differently dimensioned Helmholtz dampers for damping different oscillation frequencies.

Fig. 5 shows the rear portion 30b of the Helmholtz damper 30, thus pointing out two other advantages of the system. On the one hand, a possible adjustment of the damping volume 35 is additionally provided here, in that this adjustment is configured in particular in such a way that it can be carried out in the installed state of the Helmholtz damper 30, as shown in FIGS Fig. 2 and 3 is shown. For this purpose, the end-side damping volume 35 is provided with a Abschlussbüchse 36, which the end-side storage and management of a

Piston rod 37 is used. In the damping volume 35, this piston rod 37 is connected to an adjusting piston 38 which detects the clear width of the damping volume 35. The displaceability of the adjusting piston 38, which causes a change in volume of the active damping volume 35, is achieved by the displacement of said piston rod 37 in operative connection with an adjustable compression fitting 39 or by other means. Thus, an additional component is provided which on the one hand can be applied to the turbine housing without extensive provisions, and on the other hand allows an immediate fine adjustment of the active damping volume as needed, especially when it comes to the damping behavior in transient load areas of the gas turbine, in which a damping correction against unforeseen thermoacoustic vibrations in the combustion chamber is necessary.

On the other hand, the Helmholtz damper 30 has a lateral adjustment, which proves to be extremely advantageous during installation or operation. For this purpose, a in the Fig. 2 and 3 apparent flange 40 is provided, which ensures that a fixed point recording 41 of the Helmholtz damper 30 is given. This intermediate flange 40 is in direct operative connection with an outer shell 42 of the Helmholtz damper 30. About this outer shell 42, the inclusion of lateral strains in operative connection with an approximately placed in the longitudinal center of the Helmholtz damper 30 adjusting piston 43 is ensured. Preferably, the intermediate flange 40 is disposed in the region of the front part of the combustion chamber housing 13 and anchored there, which is known from the Fig. 2 and 3 arises analogously.

After all, it is possible in this way, with minimized expenses, the damping behavior of the Helmholtz damper 17 used to optimally adapt to the actually occurring during operation in the combustion chamber 16 thermoacoustic oscillations, if an additional need should arise, and this without a cover of the gas turbine housing 11 to fall back.

LIST OF REFERENCE NUMBERS

10

gas turbine

11

turbine housing

12

plenum

13

combustion chamber housing

14

Burner, premix burner

15

Burner, premix burner

16

combustion chamber

17

Helmholtz damper according to the prior art

18

connecting channel

19

access opening

20

front cover

30

Helmholtz damper

30a

Front part of the Helmholtz damper

30b

Rear part of the Helmholtz damper

31

tuning tube

32

Front surface, cooled

33

cooling medium

33a

Openings for the inflow of the cooling medium

34

Transition piece

35

damping volume

36

completion box

37

piston rod

38

adjusting piston

39

Compression fittings

40

flange

41

fixed mounting

42

outer shell

43

adjusting piston

Claims (10)

1. Combustion chamber (16) for a gas turbine (10), with at least one Helmholtz damper (30) arranged on the combustion chamber (16), wherein the combustion chamber is equipped with a number of burners or a combination of burners (14, 15), and wherein the Helmholtz damper (30) is arranged within the disposed burners (14, 15) or in place of a free, available space within the combination of burners according to a respectively determined or established damping requirement to counter the thermoacoustic oscillation frequencies occurring in the combustion chamber, wherein the Helmholtz damper (30) has a damping volume (35), and an adjustment device (36, 37, 38) acting on the size of the damping volume (35) is arranged in a rear part (30b) of the damping volume (35), said adjustment device having a piston rod (37) and an adjustment piston (38), wherein the piston rod (37) is connected to the adjustment piston (38) in the damping volume (35) and the change in volume of the active damping volume (35) is achieved by displacing and securing the piston rod (37), characterized in that
   the adjustment device (36, 37, 38) has a termination sleeve (36), arranged at an end side of the damping volume (35), for mounting and guiding the piston rod (37) and in that an interior tuning rod (32) is arranged in a front part (30a) of the damping volume (35).
2. Combustion chamber according to Claim 1, characterized in that the burners are premix burners.
3. Combustion chamber according to Claim 1, characterized in that the Helmholtz damper (30) has means (41, 42, 43) that allow lateral adjustment and/or elongation with respect to the original longitudinal axis.
4. Combustion chamber according to Claim 1, characterized in that the combustion chamber is an annular combustion chamber, and in that the burners are arranged over one or more rows on the front cover (20).
5. Combustion chamber according to Claims 1 and/or 4, characterized in that the Helmholtz damper (30) is inserted in place of a burner (14, 15).
6. Combustion chamber according to Claims 1 and/or 4, characterized in that the Helmholtz damper (30) is inserted between two existing burners (14, 15).
7. Combustion chamber according to one of Claims 1-6, characterized in that the damping volume (35) of the Helmholtz damper (30) can be adjusted continuously from the outside.
8. Combustion chamber according to one of Claims 1-7, characterized in that a front surface (32) to the combustion chamber (16) is cooled, which front surface belongs to the Helmholtz damper (30).
9. Combustion chamber according to Claim 8, characterized in that cooling is brought about by impingement cooling.
10. Combustion chamber according to one of Claims 1-9, characterized in that the site for installing the Helmholtz damper (30) and/or determining the damping volume (35) to be provided and/or the geometric design of the tuning pipe (31) are determined by a thermoacoustic simulation that was carried out in advance.

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