JPH07190364A - Method and equipment for damping thermal acoustic vibration - Google Patents

Abstract

PURPOSE: To reduce an acoustic vibration within a combustion chamber without having any relation with the type of fuel (liquid-like or gaseous fuel) by a method wherein a location showing a thermal discharging variation in respect to combustion is controlled for controlling combustion. CONSTITUTION: A pressure sensor 15 is arranged at a location showing a powerful pressure variation, for example, within a combustion chamber 3 to measure a pressure variation related to a thermal acoustic vibration, accepts the pressure variation and transmits a generated signal to a measured value processing preparation device 16. The measured signal released from hindrance by the measured value processing preparation device 16, and amplified to a required level is transmitted to a measured value processing device 17. A signal properly processed with a required phase shift being performed within a control loop comprising a pressure sensor 15, a control device 2 and a control valve 14 and the like at the measured value processing device reaches the control device 18. The control device 18 may generate a required amount of operation for controlling the control valve 14. With such an arrangement as above, it is possible to perform an effective attenuation of thermal acoustic vibration within the combustion chamber 3 without having any relation with the type of fuel (liquid or gaseous fuel).

Description

Detailed Description of the Invention

[0001]

This invention relates to the field of fuel technology. That is, the present invention is a method for attenuating thermoacoustic vibrations that occur during combustion of inflowing fuel in a combustion chamber, particularly in a combustion chamber of a gas turbine, and measures pressure fluctuations in the combustion chamber. And controlling combustion correctly in accordance with the measured pressure fluctuations to affect combustion so that pressure fluctuations are reduced.

Such a method is known, for example, from DE 40 40 745 A1.

The invention further relates to a device for carrying out the method described above.

[0004]

2. Description of the Related Art When burning fuel in a combustion chamber of a stationary gas turbine, an aircraft engine or the like,
Due to the combustion process, instabilities or pressure fluctuations that excite (thermoacoustic) vibrations occur at appropriate rates. Such thermoacoustic vibration is felt outward as hum, noise, or rattle. These sounds are not only an inconvenient sound source, but also increase harmful substances due to uneven combustion, unacceptably high mechanical load, and extinguish flame in extreme cases. There is a risk of being punished.

In order to be able to effectively suppress this type of thermoacoustic vibration, various proposals have already been made in the past for effective damping (in the specification mentioned at the beginning or in Germany). See Japanese Patent No. 3439903). The method proposed in the specification mentioned at the beginning is
It is based on supplying fuel aperiodically. Its functional principle is the so-called Rayleigh-Kri standard.
terium). According to this criterion, the cross-correlation function

[0006]

[Equation 1]

When takes a positive value, acoustic vibration occurs in the combustion chamber.

According to the above-mentioned prior art, an adjusting member has been proposed in order to be able to control the variation in heat release so that the cross-correlation function is minimized through the supply of fuel. There is. Regulators of this kind exist for liquid fuels. However, there are no control elements available for gaseous fuels. The problem with regulating members for gaseous fuels is that there is a parasitic variation in the gas supply conduit with respect to combustion, which has a further adverse effect on combustion.

[0009]

SUMMARY OF THE INVENTION The object of the present invention is therefore to improve the method described at the outset in such a way that, in a simple manner, the thermoacoustic oscillations in the combustion chamber are independent of the fuel type (liquid or gaseous). The object is to provide an apparatus suitable for carrying out the method, as well as enabling effective damping.

[0010]

SUMMARY OF THE INVENTION The present invention solves the above problems in a method of the type described at the outset by controlling the location of the heat release variation associated with combustion for combustion control. I was able to. This control is not performed via the fuel supply itself, but the method of the present invention can be used consistently with both liquid and gaseous fuels.

In other words, the idea of the present invention is not to affect the heat release fluctuation depending on the size thereof, but to try to affect the place where the heat release fluctuation is performed. Cross-correlation functions are likewise minimized by such means. Basically, the heat-emission variation point can be changed, for example by changing the contour of the combustion chamber or the contour of the flame. However, such contour changes would result in the emergence of costly machinery that would unnecessarily complicate the structure of the combustion chamber.

Therefore, in an advantageous embodiment according to the present invention, the control of the heat release fluctuation point is performed by controlling the ignition timing. By changing the ignition timing or the ignition delay, the ignition position is changed and the heat release fluctuation portion is automatically changed based on the fuel flow.

In a further advantageous embodiment of the method according to the invention, the ignition timing can be influenced particularly simply and effectively if the ignition timing is controlled by blowing additional medium into the combustion chamber. . At that time, it is self-evident that, in order to achieve the desired attenuation result, it is necessary to perform the blowing in the correct phase.

In the case of the first alternative embodiment, additional medium is blown in to increase the ignition delay. Water is then preferably used as additional medium.

In the case of the second alternative embodiment, an additional medium is injected to reduce the ignition delay. Hydrogen or CO is preferably used here as additional medium.

The device for carrying out the method according to the invention is characterized by a first means for measuring pressure fluctuations and a second means for controlling the heat release point, said second means. Cooperates with the first means to make an operative connection via the control device and form a control loop.

In a further advantageous development of the device according to the invention, the first means have at least one pressure sensor arranged in and / or behind the combustion chamber, and the second means. The means has at least one injection nozzle arranged in the combustion chamber, which injection nozzle is loadable by an additional medium for controlling the ignition delay via a supply conduit provided with a control valve. It has the characteristics of

Other exemplary configurations are mentioned in the other appended claims.

[0019]

The invention will now be described in more detail on the basis of an embodiment in connection with the accompanying drawings.

FIG. 1 of the accompanying drawings shows a schematic of a (stationary) gas turbine similar to that used for generating current in large capacity thermal power plants. The gas turbine 1 has a compressor section 5, a combustion chamber with a trailing turbine inlet 7, and a turbine section 4. Annular bodies of fixed blades and moving blades are alternately arranged in both the compressor portion 5 and the turbine portion 4. The rotating blades are fixed to one common turbine shaft 6. The combustion air is sucked in at the compressor inlet on the right side, compressed in the compressor part 5 and introduced under high pressure into the (chamber-shaped in this example) combustion chamber 3. In this position the air mixes with the fuel which is blown into the combustion chamber 3 via the fuel supply conduit 10, the fuel ring conduit 9 and the multiple fuel injection nozzles 8. This air-fuel mixture is ignited to form a flame and burn. The generated high-temperature combustion gas passes through the turbine inlet 7 at a high speed and flows into the turbine portion 4, where the combustion gas rotates its kinetic energy at least partially through the rotor blades. 6.

The thermoacoustic oscillations that occur in the combustion chamber 3 during combustion are such that the position of the heat release fluctuations, ie the state and / or shape of the flame, changes and is controlled on the basis of unfavorable pressure fluctuation criteria. Is affected by the attenuation.
To this end, a control loop is formed which has at least one pressure sensor 15, a control device 2 and a control valve 14 for controlling and blowing additional medium into the combustion chamber 3.

The pressure sensor 15 has a strong pressure fluctuation location,
It is arranged, for example, in the combustion chamber 3 itself or-as shown in Figure 1-at the turbine inlet 7. The pressure sensor 15 measures and accepts pressure fluctuations associated with thermoacoustic vibrations and transmits the generated signal to a measurement value preparation device 16 arranged behind it. The measurement value preparation device 16 has, for example, suitable filter circuits and preamplifiers, which release the measurement signal from interference and amplify it to the level required for further processing. The measurement signal thus processed is then transmitted to the subsequent measurement value processing device 17, which is arranged to be able to perform the required phase shift in the control loop. This work is done by analog means or by digital means by the use of a microprocessor.

The appropriately processed signal is the measured value processing device 1.
7 to reach the inlet of the control device 18, and the control device 18 generates the manipulated variable necessary for controlling the control valve 14.
The type of manipulated variable is adjusted depending on whether the control valve 14 operates electrically, liquidly or pneumatically. Control valve 1
4 is arranged in the supply conduit 13 for the additional medium and controls the supply of the medium to the corresponding jet nozzle 12, said jet nozzle 12 being connected to the ring conduit 11 Are blown into the combustion chamber 3. The injection nozzle 12 is preferably directed towards the flame in the combustion chamber 3,
It is oriented laterally or parallel to the flame direction. The nozzle itself is formed as a ring or as an individual nozzle. Importantly, the additional medium is empirically accurate,
The effect is to allow injection into certain zones where the effect of ignition delay is particularly pronounced, depending on the type of combustion of the flame.

If a liquid, in particular water, is used as additional medium, the control device shown can be constructed in a particularly simple manner. The advantage of this configuration is that there is a suitable regulating member for the liquid medium, namely the control valve 14. By blowing water, the ignition delay time can be increased in a known manner. When the injection with proper phase shift is performed, the cross-correlation function described at the beginning is minimized.

However, if a corresponding control element is present, it is also conceivable to blow in a gaseous additional medium instead of water in order to increase the ignition delay time. It is likewise conceivable to use a medium (liquid or gaseous) with a shorter ignition delay time instead of a medium with a longer ignition delay time. Hydrogen and carbon monoxide (CO) can be mentioned here as examples of gaseous media operating in this way.

The use of the present invention is, of course, illustrated in the embodiments,
It is not limited to the ring-shaped main combustion chamber of the stationary gas turbine. Similar results are obtained when used in geometrically different shaped combustion chambers, after-combustion chambers, aviation engines or the like.

As a whole, according to the invention, a method and a device for operating a combustion chamber in which the thermoacoustic oscillations occurring during the combustion process can be damped or completely suppressed independent of the type of fuel Can be achieved.

[Brief description of drawings]

FIG. 1 shows thermoacoustic vibrations in a combustion chamber of a gas turbine,
FIG. 5 is a diagram of an advantageous embodiment of a control device according to the invention, which can be effectively damped by the controlled blowing of additional medium into the combustion chamber.

[Explanation of symbols]

 1 Gas Turbine 2 Control Device 3 Combustion Chamber (Ring) 4 Turbine Part 5 Compressor Part 6 Turbine Shaft 7 Turbine Inlet 8 Fuel Injection Nozzle 9 Fuel Ring Conduit 10 Fuel Supply Conduit 11 Ring Conduit (Additional Medium) 12 Injection Nozzle ( Additional medium) 13 Supply conduit (of additional medium) 14 Control valve 15 Pressure sensor 16 Measured value processing preparation device 17 Measured value processing device 18 Control device

Claims (13)

[Claims] 1. A method for attenuating thermoacoustic vibrations which occur during combustion of inflowing fuel in a combustion chamber (3), in particular in a combustion chamber of a gas turbine (1), In the type in which the pressure fluctuation in the combustion chamber (3) is measured, and the combustion is controlled in phase according to the measured pressure fluctuation to affect the combustion so that the pressure fluctuation is reduced, , A method for damping thermo-acoustic oscillations, characterized in that it controls the location of the heat release fluctuations associated with combustion. 2. The method according to claim 1, characterized in that the control of the heat release fluctuation point is performed by controlling the ignition timing. 3. Method according to claim 2, characterized in that the control of the ignition timing is carried out by blowing additional medium into the combustion chamber. 4. Method according to claim 3, characterized in that an additional medium is blown to increase the ignition delay. 5. Method according to claim 3, characterized in that additional medium is blown in to reduce the ignition delay. 6. The method according to claim 3, wherein the additional medium is a liquid medium. 7. A method according to claim 6, characterized in that water is blown in as an additional medium in order to increase the ignition delay. 8. A method according to any one of claims 3 to 5, characterized in that the additional medium is a gaseous medium. 9. Method according to claim 8, characterized in that hydrogen or CO is blown in as additional medium in order to reduce the ignition delay. 10. A first means for measuring the pressure fluctuations and a second means for controlling the heat release point are provided, the second means via the control device (2). Device for carrying out the method according to any one of claims 1 to 9, characterized in that it is operatively coupled to and forms a control loop. 11. The first means has at least one pressure sensor (15) arranged in and / or behind the combustion chamber (3), and the second means comprises the combustion chamber (3). Having at least one injection nozzle (12) disposed therein,
The injection nozzle (12) is characterized in that it can be loaded by an additional medium for controlling the ignition delay via a supply conduit (13) provided with a control valve (14),
The device according to claim 10. 12. The control device (2) comprises a measurement value processing preparation device (16), a measurement value processing device (17) and a control drive device (18) in a series circuit, and the measurement value processing preparation device (16).
The inlet of the pressure sensor (15) and also the control drive (1
12. Device according to claim 11, characterized in that the outlets of 8) are each operatively connected to a control valve (14). 13. Arrangement according to claim 12, characterized in that a measurement value preparation device (16) is provided in the control loop, in particular for the correct phase adjustment.