EP1483536B1 - Gas turbine - Google Patents

Description

The invention relates to a gas turbine with a burner, which opens into a combustion chamber. In particular, the combustion chamber is designed as an annular combustion chamber.

In combustion systems such as gas turbines, aircraft engines, rocket engines and heating systems, thermoacoustically induced combustion oscillations can occur. These arise through an interaction of the combustion flame and the associated heat release with acoustic pressure fluctuations. By means of an acoustic excitation, the position of the flame, the flame front surface or the mixture composition can fluctuate, which in turn leads to fluctuations of the heat release. With a constructive phase position, positive feedback and amplification can occur. Such an increased combustion vibration can lead to considerable noise and vibration damage.

These thermoacoustically induced instabilities are significantly influenced by the acoustic properties of the combustion chamber and the boundary conditions present at the combustion chamber inlet and the combustion chamber outlet as well as at the combustion chamber walls. The acoustic properties can be changed by installing Helmholtz resonators.

The WO 93/10401 A1 shows a device for suppressing combustion oscillations in a combustion chamber of a gas turbine plant. A Helmholtz resonator is fluidly connected to a fuel supply line. The acoustic properties of the supply line or the overall acoustic system are thereby changed so that combustion oscillations are suppressed. However, it has been shown that this measure is not sufficient in all operating conditions, as it is also at a suppression of vibrations In the fuel line to combustion vibrations can come.

The US-A-6 058 709 proposes to avoid combustion oscillations to introduce fuel at axially different positions in the combustion channel of a burner. As a result, with regard to the formation of combustion vibrations, constructive phase positions in the mixture composition are superimposed by destructive, so that overall there are lower fluctuations and thus a reduced tendency to form combustion oscillations. However, this measure is comparatively expensive in comparison to the purely passive measure of the use of Helmholtz resonators.

In the EP 0 597 138 A1 a gas turbine combustor is described which has air-purged Helmholtz resonators in the burner. The resonators are arranged alternately on the end face of the combustion chamber between the burners. By these resonators, vibration energy is absorbed by combustion vibrations occurring in the combustion chamber and the combustion vibrations are thereby damped.

Another measure for damping combustion oscillations is in the EP 1 004 823 A2 shown. Here a Helmholtz resonator is directly connected to the mixing area of the burner. The resonator is to be installed upstream of the fuel supply, since combustion oscillations occurring in the burner and also caused by the supply lines are to be absorbed by the resonator.

In the US 5,644,918 a combustion chamber is disclosed with a resonator formed in the form of a cylindrical double sleeve, which is arranged concentrically between a combustion chamber housing and a combustion chamber liner. The double sleeve is formed inter alia by an annular flange and the inner surface of the combustion chamber housing.

The object of the invention is to specify a gas turbine with a particularly low tendency to form combustion oscillations, wherein structural measures should be avoided on a combustion chamber wall.

This object is achieved by specifying a gas turbine having a combustion chamber and a burner opening into the combustion chamber at a burner mouth, wherein the burner mouth is annularly surrounded by a Helmholtz resonator and according to the invention the characterizing features of claim 1 are provided.

The Helmholtz resonator is placed around the mouth of a burner. The attenuation of combustion oscillations by a resonator can lead to local temperature differences if the resonator acts unevenly on the combustion area. This is avoided by the symmetrical, annular arrangement around the burner flame. The consequent temperature uniformity increases the damping effect and at the same time leads to a reduction of the formation of nitrogen oxides. In addition, by the arrangement of the resonator immediately around the flame around can be acted intensively directly on the place of the highest heat release. Also, this improved contact with the main source of combustion vibrations increases the effect of the resonator.

Um tiefe Frequenzen zu bekämpfen, benötigt man dementsprechend ein sehr großes Volumen. Das ist in der Praxis aufgrund des geringen zur Verfügung stehenden Platzangebotes allerdings mit großen Schwierigkeiten verbunden. In der hier beschriebenen Vorrichtung wird nun die Länge der Bohrungen wesentlich vergrößert. Dies wird erreicht, indem die Bohrungen als Röhrchen ausgeführt werden, die in das Volumen hineinragen. Das innere Volumen des Resonators wird dabei kaum geändert. Die äußeren Abmessungen des Resonators können somit klein gehalten werden. Die Röhrchen können dabei verwunden ausgeführt werden, um genügend Abstand zu den Wänden zu haben. Durch Veränderung der Länge der Röhrchen kann die Dämpfungsvorrichtung auf jede beliebige Frequenz, die im Verbrennungssystem auftritt, eingestellt werden. Dabei müssen die äußeren Abmessungen des Resonators und damit des Brennereinsatzes sowie die offene Gesamtquerschnittsfläche nicht geändert werden. Der Hauptvorteil: um tiefe Frequenzen zu dämpfen, kann mit Hilfe der hineinragenden Röhrchen auf eine Volumenvergrößerung des Resonators verzichtet werden.The Helmholtz resonator preferably has a resonator volume and opens at a resonator opening into the combustion chamber, the resonator mouth having a small tube continuing into the resonator volume. More preferably, the resonator mouth is formed by a plurality of openings which are each continued via a tube into the resonator volume. The tubes thus protrude into the resonator volume. By this embodiment, it is possible to keep the size of the resonator small. Usually, a resonator consists of a volume V and holes of a certain length I and cross section A. This geometry together with the speed of sound c determines the resonance frequency according to the simplified formula $f_{\mathit{res}}=\left(c/\left(2\pi \right)\right)*\sqrt{\left[A/\left(V*1\right)\right]}\mathrm{,}$

In order to fight low frequencies, one needs accordingly a very large volume. This is in practice due to the limited space available but associated with great difficulties. In the here described device, the length of the holes is now substantially increased. This is achieved by making the holes as tubes that protrude into the volume. The inner volume of the resonator is hardly changed. The outer dimensions of the resonator can thus be kept small. The tubes can be carried out wounded to have enough distance to the walls. By changing the length of the tubes, the damping device can be adjusted to any frequency that occurs in the combustion system. In this case, the outer dimensions of the resonator and thus the burner insert and the open total cross-sectional area need not be changed. The main advantage: to dampen low frequencies, can be dispensed with the help of the protruding tubes on an increase in volume of the resonator.

Preferably, the tube or tubes are curved or twisted so that the tube length is increased without falling below a minimum distance to the resonator wall.

Preferably, the resonator volume is adjustable, for example by a piston-like displacement of a resonator wall. As a result, the acoustic properties, in particular the impedance, can be adjusted and adjusted.

In a preferred embodiment, the combustion chamber is designed as an annular combustion chamber. Especially in annular combustion chambers combustion oscillations can lead to very disturbing and damaging combustion oscillations by a comparatively large combustion chamber volume and burners coupled together. In addition, the acoustic properties of such a combustion chamber are difficult to calculate.

According to the invention, the Helmholtz resonator is integrated in a burner insert, wherein the burner is connected to the burner via the burner insert. The burner insert can be a separate component, which is bolted to the combustion chamber wall, for example, and in the then the actual burner is used. But it can also be connected to the burner, so that, for example, the burner insert forms a flange on the burner, with which the burner is connected to the combustion chamber wall. The integration of the resonator in the burner insert no structural measures on the combustion chamber wall are required and the resonator can be expanded if necessary in a simple manner.

Preferred dimensions of the Helmholtz resonator is formed through air. As a result, the impedance of the resonator can be changed and adjusted in a simple manner. In addition, a cooling of the resonator and in the case of integration of the resonator in the burner insert, a cooling of the entire burner insert is achieved.

• Figur 1: eine Gasturbine
• Figur 2: einen an einer Brennkammerwand angeordneten Brenner

The invention will be explained by way of example and in part schematically with reference to the drawing. Show it:

• FIG. 1 : a gas turbine
• FIG. 2 a burner arranged on a combustion chamber wall

Like reference numerals have the same meaning in the various figures.

In FIG. 1 a gas turbine 51 is shown. The gas turbine 51 has a compressor 53, an annular combustion chamber 55 and a turbine part 57. Air 58 from the environment is fed to the compressor 53 where it is compressed to combustion air 9 high. Subsequently, the combustion air 9 of the annular combustion chamber 55 is supplied. About gas turbine burner 1 is burned there with fuel 11 to a hot gas 59. The hot gas 59 drives the turbine part 57.

In the annular combustion chamber 55 may, for reasons described above, for the formation of combustion vibrations come that can significantly affect the operation of the gas turbine 51. Helmholtz resonators may be used to dampen such combustion oscillations, with a particularly effective design being described below:

In FIG. 2 a gas turbine combustor 1 is shown, which is connected via a burner insert 2 with a combustion chamber wall 56 of a combustion chamber 55 and opens at a burner port 4 into the combustion chamber 55. A burner channel 3 of the gas turbine burner 1 surrounds a central channel 41 as an annular channel 30. The annular channel 30 is designed as a premixing channel in which fuel 11 and combustion air 9 are intensively mixed prior to combustion. This is called pre-mixed combustion. The fuel 11 is introduced via hollow swirl blades 13 in the annular channel 30. The central channel 41 opens into the combustion zone 27 together with a central fuel lance 45, the fuel, in particular oil, via a swirl nozzle 47 supplies. In this case, fuel 11 and combustion air 9 are first mixed in the combustion zone 27 and it is called a diffusion combustion. However, fuel 11, in particular natural gas, can also be added via a fuel inlet 43 into the central channel 41 upstream of the combustion zone 27.

A Helmholtz resonator 19, which has a resonator volume 23 and opens into the combustion chamber 55 via a resonator opening 21 consisting of bores, is integrated in the burner insert 2. At each of the holes in the resonator volume 23 into a tube 61 connects that is wound wound. The Helmholtz resonator 19 surrounds the burner mouth 4 annular.

The annular enclosure of the burner opening 4 through the resonator 19 leads to a uniform action on the combustion zone 27. This does not lead to temperature irregularities through the resonator 19. In addition, the Resonator 19 is very effective immediately on the zone of maximum heat release.

The tubes 61 allow a comparatively small size for the resonator 19 so that it can be integrated into the burner insert 2. Air is introduced into the resonator 19 via air inlets 63, so that this can be adapted on the one hand in terms of its impedance, and on the other hand can also be cooled.

Claims (9)

1. Gas turbine (51) having a combustion chamber (55) and a combustor (1) which leads into the combustion chamber (55) at a combustor port (4), in which the combustor port (4) is surrounded annularly by a Helmholtz resonator (19),
   characterized in that
   the Helmholtz resonator (19) is integrated in a combustor insert (2), wherein the combustor (1) is connected to the combustion chamber (55) via the combustor insert (2).
2. Gas turbine according to claim 1, in which the Helmholtz resonator (19) has a resonator volume (23) and leads into the combustion chamber (55) at a resonator port (21), wherein the resonator port (21) extends into the resonator volume (23) by means of a small tube (61).
3. The gas turbine (51) according to claim 2, in which the small tube (61) is curved or twisted in form.
4. The gas turbine (51) according to claim 2 or 3, in which the resonator volume (23) is adjustable.
5. The gas turbine (51) according to one of the preceding claims, in which the combustion chamber (55) is designed as an annular combustion chamber.
6. The gas turbine (51) according to one of the claims 1 to 5, in which the combustor insert (2) is a separate component in which the combustor (1) is installed.
7. The gas turbine (51) according to claim 6, in which the combustor insert (2) is screwed onto a combustion chamber wall (56).
8. The gas turbine (51) according to claims 1 to 5, in which the combustor insert (2) forms a flange at the combustor (1).
9. The gas turbine (51) according to one of the preceding claims, in which the Helmholtz resonator (19) is designed to allow direct airflow.

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