WO2005093326A2

WO2005093326A2 - Gas turbine combustion chamber and corresponding operating method

Info

Publication number: WO2005093326A2
Application number: PCT/EP2005/051192
Authority: WO
Inventors: Peter Flohr; Alexander Ni; Rajeshriben Patel; Majed Toqan
Original assignee: Alstom Technology Ltd
Priority date: 2004-03-29
Filing date: 2005-03-16
Publication date: 2005-10-06
Also published as: WO2005093326A3; DE102004015186A1

Abstract

The invention relates to a combustion chamber (1) for a gas turbine, comprising an annular combustion chamber (2) and at least one annular burner arrangement (4). The burner arrangement has several burners (5), which are arranged in a distributed manner in peripheral direction at the entrance (3) of the combustion chamber (2). In order to reduce pressure pulsations in the combustion chamber (2), the combustion chamber (1) comprises an actuation system (6) that is configured to individually actuate each burner (5) of the burner arrangement (4), in addition to a control system (8) that individually monitors each burner (5) of the burner arrangement (4) by means of an appropriate sensor system (9) and controls each individual burner by means of the actuation system (6) with the aim of reducing pressure pulsations.

Description

Gas turbine combustor and associated operating procedure

Technical field

The present invention relates to a combustion chamber for a gas turbine with the features of the preamble of claim 1. The present invention also relates to a method for reducing pressure pulsations in such a combustion chamber with the features of the preamble of claim 7.

State of the art

In modern gas turbine combustors, a lean premix combustion is generally carried out in order to burn a gaseous or liquid fuel with air with low pollutants. The combustion air and fuel are premixed as evenly as possible and only then fed to the flame. This takes place with a high excess of air, so that relatively low flame temperatures arise, which reduces the formation of nitrogen oxides. Combustion chambers of this type are susceptible to thermo-acoustic vibrations or pressure pulsations. On the one hand, such pressure pulsations lead to undesirable noise pollution in the vicinity of the combustion chamber. On the other hand, these pressure pulsations can

Adversely affect the operating behavior of the combustion chamber. For example can increase the pollutant emissions of the combustion chamber due to the pressure pulsations. In extreme cases, the combustion reaction can be severely impaired or even extinguished by the influence of the pressure pulsations.

A combustion chamber of the type mentioned at the outset is known from EP 0597 138 B1, which has an annular combustion chamber and a plurality of burners which are arranged in a circumferential direction at an inlet of the combustion chamber. To reduce the pressure pulsations, several Helmholtz dampers are provided in the known combustion chamber, which communicate with the combustion chamber. As a result, the pressure pulsations can be damped in the area of the combustion chamber. In order to be able to accommodate such Helmholtz resonators in the combustion chamber, a relatively large installation space is required, which, however, is not available in every application and, in particular, cannot be easily retrofitted.

Presentation of the invention

The invention seeks to remedy this. The invention as in the

Is concerned with the problem of showing an improved way for reducing pressure pulsations for a combustion chamber of the type mentioned, which in particular requires little space.

According to the invention, this problem is solved by the subject matter of the independent claims. Advantageous embodiments are the subject of the dependent claims. The invention is based on the general idea that, in the case of a burner arrangement consisting of a plurality of torches arranged in a ring, each burner should be monitored for pressure pulsation and, in the event of inadmissible local pressure pulsations, act in a targeted manner on the respective burner to reduce the pressure pulsations. The global pulsation problem of the entire burner arrangement is thus divided into several local pulsation problems for the individual burners in the invention. This procedure is based on the knowledge that the pressure pulsation in the combustion chamber and thus the instability of the combustion reaction arise as a function of pressure pulsations that occur locally on the individual burners. The more burners show local pressure pulsations, the greater the pressure pulsations in the combustion chamber and the more unstable the combustion reaction there. By means of the procedure according to the invention, disadvantageous effects of pressure pulsations on the stability and on the functioning of the combustion reaction can thus be recognized comparatively early and prevented or prevented by appropriate countermeasures. The measures according to the invention therefore generally take effect before a critical operating state occurs in the combustion chamber. Another important advantage of the procedure according to the invention can also be seen in the fact that through the targeted

Influencing individual critical burners, the entire combustion behavior within the combustion chamber is changed only slightly, so that the individual measures for stabilizing individual burners have little or no effect on pollutant emissions and on the efficiency of the combustion chamber.

The pressure pulsations occurring at the individual burners are preferably assessed on the basis of the amplitudes of the pressure pulsations occurring. For this purpose, each individual burner is preferably one separate pressure sensor assigned, which enables the monitoring of the amplitudes.

According to a particularly advantageous embodiment, in the present invention, a separate control circuit can be set up for each burner of the burner arrangement, which makes it possible to operate the respective burner in such a way that the amplitudes of any pulsations that occur locally remain below a predetermined or predeterminable threshold value. It is particularly important here that the control loops can work independently and therefore independently of the other control loops.

Further important features and advantages of the present invention result from the subclaims, from the drawings and from the associated description of the figures with reference to the drawings.

Brief description of the drawings

Preferred exemplary embodiments of the invention are illustrated in the drawings and are explained in more detail in the following description, the same reference numerals referring to the same or similar or functionally identical components. Each shows schematically

1 is a very simplified schematic diagram of a combustion chamber according to the invention,

2 is a view as in Fig. 1, but in another embodiment, Fig. 3 is a diagram in which the amplitudes of the pressure pulsations occurring for the burners of the combustion chamber is plotted.

Ways of Carrying Out the Invention

1 shows, in a highly simplified form, a combustion chamber 1 for a gas turbine, which is otherwise not shown. The combustion chamber 1 has an annular combustion chamber 2, of which an inlet 3 is visible in FIG. 1. The combustion chamber 1 also comprises at least one ring-shaped burner arrangement 4, which consists of several burners 5. These burners 5 are arranged at the inlet 3 distributed in the circumferential direction. In the exemplary embodiment shown here, the burner arrangement 4 has twelve burners 5. It is clear that in another embodiment, more or fewer burners 5 can also be provided.

When the combustion chamber 1 is in operation, the burners 5 receive an oxidizer, in particular combustion air, and a liquid or gaseous fuel, e.g. Natural gas. A premixing of the fuel / combustion air mixture is then carried out in the burners 5. This fuel / combustion air mixture is then burned in the combustion chamber 2.

The combustion chamber 1 also includes an actuation system 6, which is designed such that it can actuate each burner 5 of the burner arrangement 4 individually. This is indicated in FIG. 1 by control lines 7, which each lead from the actuation system 6 to one of the burners 5. It is clear that another type of signal transmission can also be provided, for example by means of a bus system. The actuation system 6 can set individually determined operating parameters for the respective burner 5 on each individual burner 5. For example, the actuation system 6 on each burner 5 adjust the air supply and / or fuel supply and / or burner inlet temperature.

The combustion chamber 1 is further equipped with a control system 8 and with a sensor system 9. The sensor system 9 comprises several

Pressure sensors 10, namely a pressure sensor 10 for each burner 5 of the burner arrangement 4. These pressure sensors 10 are expediently designed such that an amplitude of pressure pulsations that occur in the area of the respectively assigned burner 5 can be detected. The detected amplitudes or the measurement signals correlating therewith are made available to the control system 8 by the sensor system 9. For this purpose, the control system 8 communicates with the sensor system 9. In the present case, the individual pressure sensors 10 are connected via signal lines 11 to a central unit 12 of the sensor system 9 and this communicates with the control system 8 via a connecting line 13. In principle, other interconnections are also possible here , For example, each pressure sensor 10 can be connected directly to the control system 8. A variant with a bus system is also conceivable, in which the individual pressure sensors 10 and the control system 8 are connected to a corresponding data bus.

The control system 8 is also connected to the actuation system 6 and configured in such a way that it can actuate the actuation system 6 for the targeted control of all or individual burners 5.

The variant according to FIG. 2 differs from the embodiment according to FIG. 1 primarily in that two annular burner arrangements 4 and 4 ′ are provided, which are arranged concentrically to one another. Each burner arrangement 4, 4 'here comprises the same number of burners 5 and 5', each burner 5 of the inner burner arrangement 4 having one burner 5 ' is assigned to the outer burner arrangement 4 ', the mutually assigned burners 5 and 5' also being spaced apart from one another in the radial direction. In such an embodiment, it may be expedient to assign a common pressure sensor 10 to each pair of radially arranged burners 5, 5 ′. In a corresponding manner, the actuation system 6 is then designed in such a way that it controls the burners 5, 5 ′ assigned to one another in pairs. Through this group formation or pair formation, the regulation effort or control effort can be reduced. Such pair or group formation is fundamentally also possible in the circumferential direction, in particular with a large number of burners. In principle, however, an embodiment is also possible in which each individual burner 5 and 5 'is assigned its own pressure sensor 10 and in which the actuation system 6 can actuate each individual burner 5 and 5' individually.

FIG. 3 shows a situation that can typically occur during operation of the combustion chamber 1. The diagram shows the amplitudes A determined with the aid of the pressure sensors 10, specifically for each individual burner 5. The individual burners 5 are numbered from 1 to 12 in the diagram. In the arrangement according to FIG. 1, this numbering of the burners 5 corresponds, for example, to a numbering of

Burner 5 clockwise corresponding to a clock, that is, burner 5 ₂ is at the top, i.e. at the 12 o'clock position.

In the diagram according to FIG. 3, a threshold value As for the amplitude A of the pressure pulsations is also entered in the form of a broken line.

Pressure amplitudes A which are below the threshold value As represent "normal" pulsations in which there is no need for action. The amplitudes A which are above the threshold value As are "critical", so that there is a need for action in the associated burner 5. In the exemplary case shown here, the second burner 5 ₂₎ is thus the fifth Burner 5s, the eighth burner 5β and the ninth burner 5g are critical, which is indicated in FIG. 1 by full circles, while the other burners 5 are not critical, that is to say operate normally and are indicated by circular lines or by empty circles.

The present invention works as follows:

During operation of the combustion chamber 1, the sensor system 9 monitors the amplitudes A of the pressure pulsations in the area of each individual burner 5 by means of the pressure sensors 10. The measured values are transmitted to the control system 8, which checks whether the determined amplitudes A are below the threshold value As or not.

3, the control system 8 detects one for the four critical burners 5 ₂ , 5s, 5s and 5g

Need for action to the effect that the pressure pulsations on the critical burners 5 ₂₎ 5s, 5 ₈ and 5 ₉ must be reduced with regard to their amplitudes A. Consequently, the control system 8 actuates the actuation system 6 in a suitable manner such that the actuation system 6 the critical burners 5 ₂ . 55, 5β and 5g with regard to a reduction or suppression of the pressure pulsations or with a view to a weakening of the amplitudes A. It is essential here that the control system 8 uses the actuation system 6 exclusively the critical burners 5 ₂ . 5s, 5s and 5g controls to reduce the vibration amplitudes A, while all other, normally working burners 5 continue to be operated unchanged. On the one hand, this procedure has the advantage that the measures for reducing the pressure pulsations, which are described below, have only a minor influence on the overall operating behavior of the burner chamber 1, since only the critical burners 5 and not all burners 5 are influenced. On the other hand, the respective measures on the respective critical burner 5 can be selected very drastically and thus work effectively without critical operating states for the combustion chamber 1 occurring. In addition, the pressure pulsations which build up are combated in this way at a very early point in time at which they have as a rule not yet adversely affected the operation of the combustion chamber 1, that is to say the combustion reaction in the combustion chamber 2.

In order to individually reduce the amplitudes A of the pressure pulsations at the individual critical burners 5 ₂ , 5s, 5 ₈ and 5g, the actuation system 6 can reduce the air supply and / or the fuel supply and / or the fuel inlet temperature, for example, on the respective burner 5. For example, throttling the fuel supply by, for example, 50% leads to an effective reduction in the pulsation amplitudes A. If the fuel supply is reduced by 50% for all four critical burners 5 ₂ , 5s, 5 ₈ and 5 g, this means one for the entire burner arrangement 4 Reduction of the fuel supply by only about 16.7%. Due to the drastic measures, the pulsation at the critical burners 5 can be combated very effectively, so that normal operation for the respective burner 5 can be achieved within a short time.

In the embodiment shown here, the burners 5 are controlled as a function of the amplitude A of the pressure pulsations occurring at the respective burner 5 in order to reduce the amplitudes A at the respective critical burner 5 from critical values above the threshold value As to non-critical or normal values below the threshold value As. In principle, however, other reference variables for the control or regulation of the burners 5 are also conceivable, which correlate with the pressure pulsations on the individual burners 5. Since in the combustion chamber 1 according to the invention each burner 5 is assigned its own pressure sensor 10 and since the control system 8 also enables the individual burners 5 to be actuated individually via the actuation system 6, the burner arrangement 4 in the combustion chamber 1 according to the invention can have its own for each burner 5 closed loop are formed. It is important that each individual control loop controls or controls the associated burner 5 independently of the other control loops with a view to reducing the pressure pulsations or with a view to reducing the amplitude A. The control goal is not necessarily a specific value for the amplitude A, but rather that

Lowering the locally occurring amplitude A below the respective threshold value As. These control loops are therefore essentially only activated and operated only as long as the amplitude of the respective critical burner 5 is above the respective threshold value As.

The threshold value As can be a static absolute value, which is determined empirically, for example. Alternatively, the threshold value As can also be a dynamic relative value, which results from an overall view of all current amplitudes A at the burners 5. For example, the relative threshold value As draws a limit for outliers that are no longer permissible with regard to an average of all amplitudes A or are regarded as critical. A combination of a static absolute value and a dynamic relative value is also possible in order to also be able to take into account the rare case in which all the burners show 5 critical amplitudes.

LIST OF REFERENCE NUMBERS

combustion chamber

Entry from 2nd

burner arrangement

burner

actuating system

control line

control system

sensors

pressure sensor

signal line

Central unit from 9

connecting line

Claims

claims

1. Combustion chamber for a gas turbine, - with an annular combustion chamber (2) and

- With at least one annular burner arrangement (4) with a plurality of burners (5), which are arranged at an inlet (3) of the combustion chamber (2) in the circumferential direction, so that an actuation system (6) is provided, which is designed for the individual actuation of each burner (5) of the burner arrangement (4),

- That a control system (8) is provided which individually monitors each burner (5) of the burner arrangement (5) by means of a suitable sensor system (9) and controls them individually via the actuation system (6) with a view to suppressing and / or reducing pressure pulsations ,

2. Combustion chamber according to claim 1, characterized by the fact that the sensor system (9) for each burner (5) of the burner arrangement (4) has a pressure sensor (10) with which the amplitudes (A) of each Burner (5) occurring pressure pulsations are detectable.

3. Combustion chamber according to claim 1 or 2, dad u rch ge ken nzeich net that the actuation system (6) is designed so that it in the respective burner (5) to suppress and / or reduce the pressure pulsations Air supply and / or fuel supply and / or burner inlet temperature reduced.

4. Combustion chamber according to one of claims 1 to 3, characterized in that the control system (8) is equipped so that it the respective burner (5) depending on the amplitude (A) of the pressure pulsations occurring on the burner (5) via the actuation system (6) controlled to suppress and / or reduce the pressure pulsations.

5. Combustion chamber according to one of claims 1 to 4, characterized in that via the control system (8), the sensors (9) and the actuation system (6) for each burner (5) of the burner arrangement (4) has its own closed control loop is formed, which actuates the respective burner (5) such that the amplitudes (A) of the pressure pulsations occurring at the respective burner (5) do not exceed a predetermined or predeterminable threshold value (As).

6. Combustion chamber according to claim 5, characterized in

- that the threshold value (As) is an absolute value, or

- That the threshold value (As) is a relative value which results from a comparison of the amplitudes (A) of the pressure pulsations on all burners (5) of the burner arrangement (4).

7. combustion chamber according to one of claims 1 to 6, dadu rch indicates,

- that at least two radially and / or in the circumferential direction immediately adjacent burners (5) are combined to form a burner group, - That the actuation system (6) is designed for the individual actuation of each burner group,

- That the burner groups are individually monitored with regard to pressure pulsations.

8. A method for reducing pressure pulsations in a gas turbine combustion chamber (1), which has an annular combustion chamber (2) and at least one burner arrangement (4) with a plurality of burners (5) arranged in a circumferential direction at an inlet (3) of the combustion chamber (2) ), so that each burner (5) of the burner arrangement (4) is individually monitored with regard to pressure pulsations and controlled to suppress and / or reduce the pressure pulsation.

9. The method according to claim 8, characterized by the fact that in each burner (5) of the burner arrangement (4) the amplitudes (A) of the pressure pulsations occurring on the respective burner (5) are monitored.

10. The method according to claim 8 or 9, characterized by the fact that each burner (5) of the burner arrangement (4) as a function of the amplitude (A) of the pressure pulsations occurring on the respective burner (5) for suppression and / or reduction the pressure pulsations are controlled.

11. The method according to any one of claims 8 to 10, so that the air supply and / or the fuel supply and / or the burner inlet temperature is reduced in order to suppress and / or reduce the pressure pulsations in the respective burner (5).

12. The method according to any one of claims 8 to 11, characterized in that each burner (5) of the burner arrangement (4) is controlled with its own closed control loop, such that the amplitudes (A) of those occurring on the respective burner (5) Pressure pulsations do not exceed a predetermined or predeterminable threshold value (As).

13. The method according to claim 12, characterized in that

- that the threshold value (As) is an absolute value, or

14. The method according to any one of claims 8 to 13, characterized in that at least two radially and / or in the circumferential direction immediately adjacent burners (5) are combined to form a burner group, each burner group being monitored individually with regard to pressure pulsations and for suppression and / or Reduction of the pressure pulsations is controlled.