EP0611434A1

EP0611434A1 - Arrangement for suppressing combustion-caused vibrations in the combustion chamber of a gas turbine system

Info

Publication number: EP0611434A1
Application number: EP92922654A
Authority: EP
Inventors: Bernhard Schetter
Original assignee: Siemens AG
Current assignee: Siemens AG
Priority date: 1991-11-15
Filing date: 1992-11-06
Publication date: 1994-08-24
Also published as: JPH07501137A; WO1993010401A1; CZ114994A3

Abstract

L'invention concerne un dispositif permettant de supprimer les vibrations dues à la combustion dans une chambre de combustion (1), pouvant être l'objet de vibrations acoustiques, d'une installation à turbine à gaz. Ladite chambre de combustion (1) est pourvue d'un brûleur (2) assurant la combustion d'un fluide comportant un combustible, fluide qui est conduit jusqu'au brûleur (2) par une conduite d'alimentation (3) pouvant être l'objet de vibrations acoustiques et couplée acoustiquement à la chambre de combustion (1). Selon un premier mode de réalisation de l'invention, le dispositif présente un élément (4, 5; 6; 7; 19) ayant une action acoustique et couplé à la conduite d'alimentation (3), par lequel la conduite d'alimentation (3) est accordée acoustiquement de telle manière qu'une combustion instationnaire en raison des vibrations acoustiques dans la conduite d'alimentation (3) soit pratiquement exclue. Selon un deuxième mode de réalisation de l'invention, une réaction de vibrations acoustiques dans la conduite d'alimentation (3) à des vibrations acoustiques dans la chambre de combustion (1), réaction induite par une combustion instationnaire en raison des vibrations acoustiques dans la conduite d'alimentation (3) est réglée, par l'élément (4, 5; 6; 7; 19) ayant une action acoustique, de telle manière qu'elle s'oppose à la production de vibrations dues à la combustion. L'application de l'invention est possible et avantageuse dans les installations fixes à turbine à gaz d'une puissance électrique nominale atteignant 100 MW et plus.The invention relates to a device for suppressing vibrations due to combustion in a combustion chamber (1), which can be subjected to acoustic vibrations, of a gas turbine installation. Said combustion chamber (1) is provided with a burner (2) ensuring the combustion of a fluid comprising a fuel, which fluid is led to the burner (2) by a supply line (3) which can be subject to acoustic vibrations and acoustically coupled to the combustion chamber (1). According to a first embodiment of the invention, the device has an element (4, 5; 6; 7; 19) having an acoustic action and coupled to the supply line (3), through which the supply line (3) is acoustically tuned such that unsteady combustion due to acoustic vibrations in the supply line (3) is practically excluded. According to a second embodiment of the invention, a reaction of acoustic vibrations in the supply line (3) to acoustic vibrations in the combustion chamber (1), reaction induced by unsteady combustion due to the acoustic vibrations in the supply line (3) is adjusted by the element (4, 5; 6; 7; 19) having an acoustic action, in such a way that it opposes the production of vibrations due to combustion. The application of the invention is possible and advantageous in fixed gas turbine installations with a nominal electrical power reaching 100 MW and more.

Description

Device for suppressing combustion vibrations in a combustion chamber of a gas turbine plant

The invention relates to a device for suppressing combustion vibrations in a too acoustic

Vibration-capable combustion chamber of a gas turbine plant, which combustion chamber has a burner for the combustion of a fluid carrying a fuel, which fluid can be fed to the burner through a feed line capable of acoustic vibrations and acoustically coupled to the combustion chamber.

Combustion chambers of gas turbine plants, especially combustion chambers which are equipped with premix burners, tend to self-excited combustion oscillations, depending on the operating state. Such combustion vibrations have frequencies which correspond to the resonance frequencies of the combustion chamber or of another structure capable of vibration, including the combustion chamber; depending on the size of the vibratory structure, these frequencies are between a few Hz and several kHz, typically less than 1 kHz in gas turbine systems. Pressure fluctuations of considerable magnitude are often associated with such combustion vibrations, in particular with amplitudes of the pressure up to the level of the steady pressure losses of the combustion chamber. Such pressure fluctuations can u. U. cause mechanical damage to the combustion chambers and other components of the gas turbine systems.

A combustion chamber for a gas turbine system with a burner arranged therein can be found in EP 0 193 838 B1. The burner described there is a so-called "hybrid burner", a combination of diffusion burner and pre-burner. If the premix burner is operated, u. It may be necessary to support the combustion by means of an additional "pilot flame" from the diffusion burner. Information on the design of a combustion chamber for a gas turbine system can be found in DE 25 23 449 C3. The combustion chamber described there consists of a flame tube which is arranged in a housing, the air for combustion being fed through an annular gap between the flame tube and the housing to the burners arranged at one end of the flame tube. The combustion air flows through the burners into the flame tube, fuel being added to it; The combustion takes place in the flame tube. The exhaust gases from the combustion are fed to the gas turbine, if necessary after admixing air.

Gas turbine plants which are operated with gaseous fuels are receiving increased attention in connection with coal gasification devices in which gaseous fuel is produced from coal. Gas turbine plants in combination with coal gasification plants and steam power plants for waste heat recovery were dealt with in detail in a lecture by S. Joyce entitled "The Development of Integrated Coal-Gasification Combined-Cycle (ICG-GUD) Power Plants", presented on April 26th. 90 on the occasion of a seminar "Coal Gasification for Generation of Electricity" held in Arnhem (Netherlands); a transcript of the lecture was distributed during the seminar.

Further details on pre-burners and hybrid burners for use in the combustion chambers of gas turbine systems can be found in EP 0 108 361 Bl, EP 0 276 696 Bl and WO 89/08803 AI. The latter document relates to the upgrading of a combustion chamber for the supply of additives for binding certain scraps in the fuel used.

The causes of self-excited combustion vibrations have long been known in principle. With combustion vibrations conditions are acoustic vibrations, i.e. vibrations of the type of sound, which are ignited by transient combustion processes. The frequency of a combustion oscillation is mainly determined by the geometry of the combustion chamber; the frequency of the combustion oscillation corresponds to a resonance frequency, which is defined by standing acoustic waves in the oscillatory structure to which the combustion chamber belongs.

Combustion vibrations often result from the fact that acoustic vibrations in a combustion chamber capable of acoustic vibrations cause acoustic vibrations in a feed line which is also capable of acoustic vibrations for the delivery of the fuel to the burner; the acoustic vibrations in the feed line, in turn, due to the pressure surges connected to them, cause an unsteady fuel flow to the burner and thus bring about an unsteady combustion, which in turn influences the acoustic vibrations in the combustion chamber. Depending on the phase relationship between the transient combustion and the acoustic vibrations in the combustion chamber, a thermodynamic process can result on the burner, which releases mechanical energy from the combustion, which then flows into the acoustic vibrations in the combustion chamber. In this way, self-excitation arises in the overall system capable of vibration, which comprises the combustion chamber and the feed line, the closed feedback circuit required for self-excitation, which supplies the energy for the combustion vibrations, being formed by the acoustic transmission of vibrations from the combustion chamber into the feed line in connection with the thermodynamic transmission of vibrations from the feed line into the combustion chamber. It should be noted that the described "acoustic coupling" between the combustion chamber and the feed line does not necessarily have to be a direct coupling between the gas columns in the combustion chamber and the feed line; this coupling can also be realized in that the wall of the combustion chamber is connected to the wall of the feed line, which allows the transmission of acoustic vibrations. In general, it can be assumed that the acoustic coupling between the feed line and the combustion chamber is very complex and possibly implemented over several different transmission paths. In any case, however, the acoustic coupling is a coupling that is also present in the absence of combustion and can therefore be determined, for example, by measurements on a combustion chamber arrangement through which no combustion flows. The thermodynamic coupling between the feed line and the combustion chamber can also be measured, for example by filling the combustion chamber with acoustic insulation material, whereupon acoustic vibrations are measured in the combustion chamber, which are caused by the combustion by acoustic vibrations excited in the feed line. Due to the complexity of conventional combustion chambers, which, moreover, are generally not acoustically closed structures, but are only components of larger, vibration-capable structures which, in addition to the combustion chamber, also include hot gas channels and the like, is a reliable prediction of the occurrence and the frequencies of acoustic resonances, which can lead to combustion vibrations, are hardly possible in practice.

Combustion vibrations in industrial combustion devices are dealt with in the book "C-Bustion-Driven Oscillations in Industry" by AA Putnam, American Elsevier Publishing Company, Inc., New York (1971). Chapters 1 and 2 contain information on Cause and origin of combustion vibrations, special combustion devices are dealt with in the following chapters, and chapter 9 concerns the suppression of combustion vibrations. There are no references to the special problems of combustion devices in which combustion takes place under high pressure and which are used in particular in gas turbine plants.

In gas turbine plants, "combustion vibrations" are understood to mean, above all, acoustic vibrations, the pressure amplitudes of which reach the order of magnitude of the pressure losses occurring in stationary operation above the combustion chambers, in particular exceeding sizes of about 10% of the respective pressure losses. Usual pressure losses are approximately 200 kPa for aircraft engine gas turbines and approximately 50 kPa for power plant gas turbines. Tolerable acoustic vibrations should therefore not significantly exceed values of around 10 kPa. It should be noted that the absence of combustion vibrations can hardly ever mean absolutely noiseless combustion - in combustion chambers of gas turbines there is generally always a very loud, characteristic noise, the effects of which are taken into account in the design of the combustion chambers and that is why lower limit for the operational acoustic stress of the combustion chamber is determined.

So far, attempts have been made to counter combustion vibrations in the combustion chambers of gas turbine plants by means of geometric changes to the burner or other components of the combustion chamber, by redistribution of the air introduced into the combustion chamber or by inserting throttle points at the outlets of the supply lines in the burners; the latter was done to prevent acoustic vibrations in the combustion chamber from to meet guide lines. Those with the previously known

Measures achieved success have always been limited: The first-mentioned measures were particularly unsuitable because, due to the lack of sufficient predictability of their effects, they could not be carried out in a targeted manner. The last-mentioned measure was only of little practical importance because a sufficiently effective throttle point in the supply line results in a considerable pressure loss and therefore requires impractically high pressures in the fuel supply system.

In view of the problem described, the invention is based on the object of providing a device for suppressing combustion vibrations in a combustion chamber capable of acoustic vibrations

Specify gas turbine system that is reliable, does not significantly impair the other facilities required for the operation of the gas turbine system and, moreover, can be easily integrated into an existing gas turbine system if required.

In a first embodiment, the device according to the invention for suppressing combustion vibrations in a combustion chamber of a gas turbine system capable of acoustic vibrations, which combustion chamber has a burner for the combustion of a fluid carrying a fuel, which fluid is acoustically responsive to the burner by means of acoustic vibrations the supply line coupled to the combustion chamber can be supplied, characterized by an acoustically active element coupled to the supply line, by means of which the supply line is acoustically tuned in such a way that unsteady combustion due to acoustic vibrations in the supply line is essentially ruled out.

The invention is based on this embodiment. that acoustic vibrations in the feed line can mainly be understood as standing waves; this means that zones with vibrations of high amplitude and zones with vibrations of low or practically vanishing amplitude alternate in the feed line in accordance with the frequencies of the acoustic vibrations. According to the invention, the arrangement of the standing waves in the feed line is influenced in such a way that a zone with a small, preferably essentially vanishing, amplitude comes to lie on the burner, which is an end of the feed line. Since the pressure conditions at the location of the burner directly determine the combustion, the guarantee of a sufficiently low pressure fluctuation in the supply line at the location of the burner leads to a sufficiently uniform, non-stationary combustion. Accordingly, the closed feedback circuit, in which self-excitation could build up, has broken down; The occurrence of combustion vibrations can thus be prevented efficiently.

In the context of a second embodiment, the device according to the invention for suppressing combustion vibrations in a combustion chamber of a gas turbine system capable of acoustic vibrations, which combustion chamber has a burner for the combustion of a fluid carrying a fuel, which fluid provides the burner with an acoustic signal A feed line capable of vibrations and acoustically coupled to the combustion chamber can be fed, characterized by an acoustically active element coupled to the feed line, by means of which the feed line is acoustically tuned such that a reaction of acoustic vibrations in the feed line to acoustic vibrations in the combustion chamber, which reaction is caused by transient combustion due to the acoustic vibrations in the feed line device, counteracts the occurrence of combustion vibrations.

In the context of the second embodiment, the invention is based on the fact that by adjusting the acoustic properties of the feed line, the phase position of the thermodynamically induced reaction can be influenced relative to the phase position of the acoustic coupling between the combustion chamber and the feed line; According to the invention, the feed line is tuned by inserting a corresponding acoustically active element, so that the phase position of the thermodynamic reaction relative to the acoustic coupling does not correspond to a positive feedback required for self-excitation, but rather to a negative feedback. The negative feedback precludes self-excitation and also results in "active acoustic damping" of the vibratory system, which includes the combustion chamber and the feed line. "Active" because the thermodynamic reaction taking place via the combustion actually draws energy from the system capable of oscillation; According to the first embodiment of the invention, energy can only be withdrawn from the oscillatory system by means of the remaining damping present in the system due to friction or the like.

The device of any design can be used in connection with any burner; it is particularly suitable for use in connection with a pre-burner which is part of a hybrid burner, for example. Reliable suppression of combustion vibrations in gas turbine plants in power plants with electrical power ratings up to 100 MW and above is possible.

The fuel can be a gas, for example natural gas or one obtained from a coal gasification process

Product, the fluid carrying the fuel possibly being the gas itself. The fuel can also be a solid or liquid substance, for example coal dust or oil, which is dispersed in a gas which is itself possibly combustible. Finally, a liquid fuel, e.g. B. oil, conceivable; oil-water emulsions and the like are also suitable.

The described measures for suppressing combustion vibrations also allow targeted upgrading of an already existing gas turbine system.

It goes without saying that the design of the acoustically active element with regard to its acoustic parameters must be adapted to the properties of the predetermined combustion chamber and the location in the supply line to which it is to be coupled or connected. For this purpose, the combustion vibrations occurring in the combustion chamber may have to be measured; in particular, acoustic waves in the feed line may also have to be examined. The evaluation of such measurement data then leads to specific requirements for the acoustically active element to be coupled to the feed line. To suppress combustion vibrations in the combustion chamber of a gas turbine plant, as mentioned, u. a. the acoustic phenomena in the feed line of the burner are evaluated. Due to the usually simple design of such a feed line, the acoustic phenomena that occur are relatively easy to measure and theoretically detectable even if they vary from case to case. In any case, it is possible to derive a reliable statement as to how the combustion vibrations can be counteracted.

As an acoustically effective element, there is a Helmholtz resonance nator in question; this consists of an essentially closed cavity or pot into which a piece of pipe or neck leads. The mode of operation of the Helmhol tz resonator is known per se and therefore requires no detailed discussion at this point. However, it should be noted that the Helmholtz resonator, which is itself a structure capable of oscillation and has certain resonance frequencies, is not necessarily operated at such a resonance frequency in the present context. On the other hand, use is made of the fact that a Helmholtz resonator exhibits a well-defined behavior when exposed to any acoustic wave, ie also a wave whose frequency does not correspond to any of its resonance frequencies.

A Helmholtz resonator can be designed in a particularly space-saving manner as a cavity coaxially surrounding the supply line in the manner of a muffler in the exhaust system of an internal combustion engine.

A further possibility for realizing the acoustically active element is the connection of a closed pipe section, that is to say a resonance pipe, to the feed line. Such resonance tubes are known as "quarter-wave tubes". As already noted for the Helmholtz resonator, the resonance tube is not necessarily operated at one of its resonance frequencies.

It is particularly advantageous to use an acoustically effective element that is adjustable to change its acoustic properties. Such an adjustable acoustically active element can be a Helmholtz resonator with a neck that is adjustable in length or a pot with variable volume; a resonance tube is also possible, which is closed with an adjustable slide and thus an adaptation of its acoustic properties to the requirements of the respective individual case allowed. In particular with regard to retrofitting existing combustion chambers, the use of adjustable acoustically active elements is to be preferred, since such elements allow adaptation to predetermined systems. It may also be appropriate to adjust the acoustically active element as a function of the operating state of the gas turbine system, since experience has shown that the occurrence of combustion vibrations depends relatively strongly on the respective load on the gas turbine system. "

A further possibility for realizing the acoustically active element is to insert a cavity into the feed line, the cavity being an “open end” of the feed line in terms of acoustics. With the aid of such a cavity, the resonance behavior of the part of the supply line directly connected to the burner can be influenced in a targeted manner, so that combustion vibrations are effectively avoided. In this context, the "acoustic effectiveness" of the cavity is not a specific "response behavior" to an acoustic wave that enters the cavity through the feed line, but simply the fact that an acoustic wave in a well-defined manner and practically completely at the mouth of the feed line in the cavity is reflected. The part of the feed line between the burner and the cavity is thus acoustically decoupled from the other parts of the feed line; in terms of its acoustic properties, it is therefore easy to grasp theoretically and can be adapted to the respective requirements.

It should be pointed out that an acoustic termination in the manner of a "closed end" in a supply line would hardly be possible in a gas turbine system by means of a critically flowed orifice, which could be part of a throttle device, for example. As is known, a critical flow acts as a reflector for Acoustic waves, since by definition sound waves flow through them and therefore wave propagation against the flowing flow is not possible. Ensuring such a "critical flow", however, requires a considerable pressure drop across the orifice, which in connection with pressure-loaded combustion chambers would only be achievable with pressures at an impractical level in the feed lines. It should therefore be noted that in the context of the prior art in a gas turbine system, the formation of an acoustic termination in a fuel supply line was not practical.

An acoustically active element in the present sense can also be an acoustic transmitter coupled to the feed line, e.g. B. a speaker, a vibrating piston or a vibrating membrane. Such an element is acted upon by an acoustic signal which is removed from the combustion chamber and which is characteristic of the acoustic conditions there. Such an acoustic signal can, for example, by means of a transducer acoustically coupled to the combustion chamber, preferably directly to the flame tube, e.g. B. a microphone can be obtained. The signal can be sent from the microphone to an amplifier via a signal line and from there to the acoustic transmitter via a further signal line. The transmitter enables "active" suppression of combustion vibrations in addition to or instead of the "passive" suppression previously explained, the supply line being acted upon from the outside, to a certain extent forcibly, by an acoustic signal which counteracts the combustion vibrations. In this way, suppression of the combustion vibrations can also be achieved, in particular when vibrations from the combustion chamber are coupled into the feed line only very little become; this is particularly so because, in addition to the coupling from the combustion chamber, an additional possibility for coupling vibrations into the feed line is used. As already mentioned, the suppression of combustion vibrations may be linked to the guarantee of certain phase relationships between acoustic vibrations in the combustion chamber and acoustic vibrations in the feed line. Accordingly, care must be taken to ensure that the supply line is acted upon by the transmitter with such a phase relationship. Corresponding input elements may have to be provided for this, for example as electronic phase shifters in the signal lines leading to the transmitter. In principle, an amplifier can also be used to supply the transmitter, which itself offers such a possibility for setting the phase. A transmitter acted upon by an acoustic pickup is preferably used in connection with liquid fuel.

How the suppression of combustion vibrations in a combustion chamber with several burners is fundamentally a matter of individual case, since it depends, among other things, on the extent to which vibrations in the feed lines leading to the burners influence one another. In particular when the combustion oscillations take place with relatively low resonance frequencies of the combustion chamber, it can be assumed that the acoustic coupling of the feed line of a first burner to the feed line of a second burner is relatively small. In such circumstances, the acoustic effects of the feed lines are largely independent of one another, from which it follows that a separate acoustically active element for suppressing the combustion vibrations is required in each feed line. In other cases, if there are significant repercussions from supply line to supply line, it may be possible and sufficient, only to provide some of the supply lines with acoustically active elements.

A particularly advantageous development of the device is characterized in that at least two acoustically active elements are provided in the feed line. It is particularly advantageous if an acoustically active element is a cavity, which represents an acoustically open end of the supply line, and a further acoustically active element is inserted between the cavity and the burner. In the context of this configuration, the cavity is used to acoustically close off a section of the feed line adjoining the burner and to decouple it from the rest of the feed line; the further acoustically active element can be used to tune the piece of the feed line thus obtained to suppress combustion vibrations. In any case, the insertion of several acoustically active elements in a feed line means that several parameters are available for tuning the feed line, which can considerably simplify the suppression of combustion vibrations.

The suppression of combustion vibrations in a combustion chamber of a gas turbine system can be realized on the one hand with the aid of the acoustically active element coupled to the feed line in such a way that acoustic vibrations in the feed line, which can lead to in-stationary combustion, are largely suppressed. Under certain circumstances this amounts to avoiding resonance frequencies in the feed line which correspond approximately to the resonance frequencies of the combustion chamber.

The suppression of combustion vibrations in the combustion chamber can also be carried out by explicitly accepting vibrations in the feed line are set in that the acoustic properties of the feed line are set by the acoustically active element in such a way that a vibration excited in the feed line counteracts the combustion vibration in the combustion chamber. This measure assumes that an oscillation in the feed line which is stimulated by an oscillation in the combustion chamber must also have a certain phase relationship to the combustion oscillation. Thus, the mutual coupling of the vibrations mentioned can be influenced in such a way that the vibrations do not support each other, but counteract each other. This adjustment of the phase relationship between the vibrations must take into account the dynamics of the combustion process. It should be noted in particular that the combustion of a fuel emerging from a burner occurs only after a certain time delay and, moreover, takes up a certain period of time. The phase relationship between combustion oscillation and oscillation in the feed line must be dimensioned taking this delay into account.

The further explanation of the invention is based on the exemplary embodiments shown in the drawing. To clarify special features, the drawing is schematic and is not drawn to scale. In detail show:

1 shows a combustion chamber with feed lines for fuel, supplemented by a device for suppressing combustion vibrations;

2 and 3 show exemplary embodiments of an acoustically effective element in a feed line;

Fig. 4 and Fig. 5 embodiments of an adjustable or controllable acoustically active element in one Supply line.

1 shows a combustion chamber 1, which can optionally be used as one of several in a (not shown) gas turbine system, with two burners 2, each of which can be supplied with a gas carrying a fuel through a feed line 3. It is assumed that the combustion chamber 1 and the feed lines 3 are capable of acoustic vibrations, as is generally the case with components of gas turbine systems. Important for this is in particular the fact that supply lines 3 and combustion chambers 1 of gas turbine systems are usually not manufactured or filled with acoustically insulating substances, since such substances increase the pressure losses caused in the combustion chambers 1 or supply lines 3, which is always very disadvantageous for the efficiency of the gas turbine system is. The combustion chamber 1 is formed from a flame tube 8 with a bottom 9 into which the burners 2 are let in; the flame tube 8 is — essentially concentrically — surrounded by an outer tube 10. Combustion air can flow between the flame tube 8 and the outer tube 10 from a compressor of the gas turbine system to the burners 2. The combustion air is mixed with fuel in the burners 2; the combustion essentially takes place in the flame tube 8, from which the combustion gases subsequently flow to a gas turbine of the gas turbine system.

The burners 2 are so-called premix burners. The gas carrying the fuel is supplied to the combustion air through main nozzles 11, mixed intensively with it in a blading 12 and ignited only when it enters the flame tube 8.

To stabilize each burner 2, this is also provided with an auxiliary nozzle 13, which has a certain proportion of fuel is introduced directly into the flame tube 8, where it burns in a diffusion flame and thus provides a "pilot flame" for stabilizing the premix combustion.

The lower feed line 3 has a laterally connected Helmholtz resonator 4 as an acoustically active element. A Helmholtz resonator 5 arranged coaxially around it is provided on the upper feed line 3. Essential elements of each Helmholtz resonator 4, 5 are a neck 14, i. H. a narrow piece of pipe, and a pot 15, d. H. a relatively large cavity that connects to the neck 14. The mode of operation of the Helmholtz resonator 4, 5 has already been explained.

A control valve 16 is inserted into each feed line 3; Both control valves 16 can be controlled via a branching control line 17 and thus allow, if necessary in conjunction with further measures, an adjustment of the thermal power generated in the combustion chamber 1 and a power control of the gas turbine system. Under certain circumstances, the control valves 16 (or similar components) can represent acoustic closings of the feed lines 3; this is the case if there is a noticeable amount of pressure loss. However, the insertion of throttling points in supply lines 3 is common and advantageous if these supply lines 3 are supplied with fuel by a common delivery device. As a rule, throttling points in the feed lines 3 serve to even out the distribution of the fuel on these feed lines 3.

2 and 3 relate to other possibilities with regard to the design of the acoustically active element. 2, a resonance tube 6 is coupled to the feed line 3. One end of the resonance tube 6 opens into the feed line 3; the other end facing away from the feed line 3 is closed. An acoustic vibration excited in the feed line 3 is coupled into the resonance tube 6; the acoustic behavior of the resonance tube 6 influences the acoustic properties of the feed line 3. The resonance tube 6 can be used in particular to set the resonance frequency for the structure of the feed line 3 and the resonance tube 6.

3, a large-volume cavity 7 is inserted into the feed line 3. This cavity 7 represents an acoustically open end of the feed line 3; it uncouples the piece of the feed line 3 between itself and the burner 2 (not shown) from the piece of the feed line 3 leading from it to the conveying device. By suitably positioning the cavity 7, the acoustic properties of the feed line 3 between the burner 2 and the cavity 7 matched so that the combustion vibrations are suppressed.

FIG. 4 shows, similar to FIG. 2, a resonance tube 6 coupled to the feed line 3 as an acoustically active element. 4, the resonance tube 6 is closed at the end by means of a movable slide 18 which allows the acoustic properties of the resonance tube 6 to be adjusted (for example its resonance frequencies). By adjusting the slide 18, the resonance tube 6 can be adapted to different operating states of the combustion chamber 1 to which the feed line 3 is connected. This is in particular against the endeavor to be able to operate a gas turbine plant safely over the largest possible power range.

Fig. 5 shows a possibility of realizing the acoustically active element by means of an acoustic transmitter, namely a loudspeaker 19, which in one Housing 20 is coupled or attached to the feed line 3 and is acted upon by an acoustic signal removed from the flame tube 8. This signal is taken from the flame tube 8 by means of a microphone 21 and fed to the amplifier 23 via a signal line 22, and to the loudspeaker 19 via a further signal line 24. The phase of the acoustic in the feed line 3 caused by the loudspeaker 19 is adjusted Vibration may include amplifier 23, for example, a setting element 25, shown as a capacitor with variable capacitance, for adjusting the phase of its output signal. Possibly. the correct phase relationship can be achieved by appropriate selection of the position of the microphone 21 on the flame tube 8. In addition, there is of course the possibility of providing a plurality of such microphones 21 instead of a single microphone 21, which may possibly be advantageous with regard to the processing of the signal supplied to the loudspeaker 19. Of course, several, z. B. two, acoustically effective elements 7, 19 may be provided. The combination of a large cavity 7, as shown in FIG. 5, with another acoustically active element 19 is particularly preferred. The cavity 7 serves the piece of the feed line 3 between the

To acoustically decouple cavity 7 and the burner 2 from the rest of the feed line 3. The loudspeaker 19 is connected between the burner 2 and the cavity 7.

The mode of operation of the acoustically active elements 4, 5, 6, 7, 19 shown in the drawing can be used in accordance with each embodiment of the invention, since both versions can be implemented essentially using the same structural measures. In individual cases, the mode of operation of the acoustically active element 4, 5, 6, 7, 19 depends on its design and coordination, under certain circumstances, not only the position of a single resonance frequency, but also the arrangement of a plurality or a plurality of resonance frequencies and any other acoustic properties. Finally, it should be noted that in addition to the resonance indications of an acoustically active element 4, 5, 6, 7, 19 its damping properties can also be important, which can be particularly important and advantageous if the acoustically active element does not directly flow through the feed line 3

Fuel flows through. Then its damping, which is favorably adjustable, can also be used to advantage.

The invention enables the suppression of combustion vibrations in a combustion chamber of a gas turbine system in a simple and safe manner. The device according to the invention is easily adaptable to the requirements of the individual case and enables safe and reliable operation of the gas turbine system.

Claims

1. Device for suppressing combustion vibrations in a combustion chamber (1) of a gas turbine system capable of acoustic vibrations, which combustion chamber (1) has a burner (2) for the combustion of a fluid carrying a fuel, which fluid supplies the burner (2) can be supplied by a supply line (3) capable of acoustic vibrations and acoustically coupled to the combustion chamber (1), characterized by an acoustically active element (4, 5; 6; 7; 19) coupled to the supply line (3) that the feed line (3) is acoustically matched in such a way that non-stationary combustion due to the acoustic vibrations in the feed line (3) is essentially excluded.

2. Device for suppressing combustion vibrations in a combustion chamber (1) of a gas turbine system capable of acoustic vibrations, which combustion chamber (1) has a burner (2) for the combustion of a fluid carrying a fuel, which fluid supplies the burner (2) can be supplied by a feed line (3) capable of acoustic vibrations and acoustically coupled to the combustion chamber (1), characterized by an acoustically active element (4, 5; 6; 7; 19) coupled to the feed line (3) that the feed line (3) is acoustically matched so that a

Reaction of acoustic vibrations in the feed line (3) to acoustic vibrations in the combustion chamber (1), which reaction is caused by an instational combustion due to the acoustic vibrations in the feed line (3) to counteract the occurrence of combustion vibrations .

3. Device according to claim 1 or 2, wherein the acoustically active element (4,5; 6; 7; 19) is a Helmholtz resonator (4,5).

4. Device according to claim 3, wherein the Helmholtz resonator (5) coaxially surrounds the feed line (3).

5. Device according to claim 1 or 2, wherein the acoustically active element (4,5; 6; 7; 19) is a closed resonance tube (6).

6. Device according to one of the preceding claims, wherein the acoustically active element (4, 5; 6; 7; 19) is adjustable to change its acoustic properties.

7. Device according to claim 1 or 2, wherein the acoustically active element (4,5; 6; 7; 19) is a cavity (7) integrated in the feed line (3), which has an acoustically open end of the feed line (3) represents.

8. Device according to claim 1 or 2, wherein the acoustically active element (4, 5; 6; 7; 19) is an acoustical transmitter, in particular a loudspeaker (19), which is removed from the combustion chamber (1) acoustic signal is operable.

9. The device according to claim 8, wherein the acoustic transmitter is a loudspeaker (19), which via signal lines (22, 24) and an amplifier (23) with one to the combustion chamber (1), preferably to the flame tube (8 ), acoustically coupled acoustic transducer (21) is connected.

10. Device according to one of the preceding claims, which at least two acoustically active elements (4, 5;

6; 7; 19).

11. The device according to claim 10, which has a cavity (7) which is an acoustically open end of the feed line (3), wherein between the cavity (7) and the burner (2) a further acoustically active element (4, 5; 6; 19) is inserted into the feed line (3).