EP2179222B2 - Burner for a combustion chamber of a turbo group - Google Patents

Description

Technical area

The present invention relates to a burner for a combustion chamber of a turbo group, in particular in a power plant, according to the preamble of claim 1.

State of the art

the DE 103 45 137 A1 shows an injection device intended for gas turbines, which is designed in the manner of a lance and protrudes in a self-supporting manner into a burner. Axial discharge openings for fuel and air are provided at the free end of the lance in such a way that a fuel jet encased by a flow of shielding air is generated. To control the quantitative ratio between fuel and shielding air, it is provided that the temperature changes occurring at the injection device are used. In this way, an automatic adaptation to different operating states is to be achieved in such a way that optimal operation is continuously maintained. In addition, this publication indicates that it is known to provide aerodynamic methods for flame stabilization, reference being made to swirl currents. It is emphasized that the entire flow in swirl-stabilized burners reacts extremely sensitively to changes in the flow field.

With regard to the arrangement of the lance in the burner, no more precise information is given. In addition, no more detailed explanations are given with regard to the design of the burner.

From the EP 1 526 333 A1 a fuel injector for gas turbines is known. The injector has a rod-like end piece which is arranged on the head of a vortex chamber essentially coaxially to the longitudinal axis of this chamber. On the outlet side, this vortex chamber opens into a combustion chamber.

The aforementioned end piece of the injector has, on the one hand, axial outlet openings through which fuel can be ejected as a liquid jet, and, on the other hand, discharge openings are provided through which the fuel can be ejected as an evaporating liquid jet.

the EP 0 704 657 A2 relates to a burner for gas turbines or the like. On the inflow side, this burner consists of a swirl generator and an axially adjoining mixing section, with a special transition geometry being provided at the beginning of a mixing tube such that a swirling flow passes through the mixing tube. On the downstream side of the transition geometry, film-laying bores are arranged in the wall of the mixing section, which bring about an increase in the flow velocity along the pipe wall. On the outlet side, the mixing section opens into a combustion chamber, in which a return flow zone is formed in the area of a jump in cross section between the mixing section and the combustion chamber, which is intended to act as a flame holder. A central fuel nozzle for injecting an in particular liquid fuel into the swirl generator is arranged in a cylindrical initial part upstream of the swirl generator.

the DE 10 2005 015 152 A1 relates to a premix burner for a gas turbine combustor. This burner comprises an oxidizer supply device for supplying a gaseous oxidizer into a mixing space, to which gaseous fuel is supplied by means of a gas fuel supply device and liquid fuel is supplied by means of a liquid fuel supply device. To improve the burner operation, the liquid fuel supply device has a plurality of injection holes communicating with a main supply line, which are designed so that the spray jet generated has a component radial to a main outflow direction of the burner.

In the DE 103 34 228 A1 a method for operating a premix burner is described. This has different groups of injection openings for premix fuel as well as a central fuel injection with several injection openings. In this case, different groups of the injection openings are acted upon with gaseous fuel independently of one another in order to form a premix stage on the one hand and a diffusion stage of the premix burner on the other hand. The result is an extended operating range of the premix burner with low pollutant emissions.

Despite the diverse state of the art, burners of the type specified at the beginning have the problem of flashback from the combustion chamber into the interior of the burner.

Such flashbacks are due to instabilities in the combustion process.

Presentation of the invention

This is where the present invention comes into play. The invention, as it is characterized in the claims, deals with the problem, for a burner of the in EP 704657 mentioned type to provide an improved embodiment, which is characterized in particular by an increased stability of the combustion process in the combustion chamber.

According to the invention, this problem is solved by the subject matter of the independent claim. Advantageous embodiments are the subject of the dependent claims.

The invention is based on the general idea of making the lance significantly longer so that it can protrude deeper into the interior of the burner in the direction of the outlet opening. Here, the knowledge is used that a velocity profile develops in the mixer for the mixture flow, that in the center has significantly higher speeds than in the edge area. By lengthening the lance in the direction of the outlet opening into the mixer, the speed in the center can be reduced, while at the same time the flow speed increases in the edge areas. However, the increased flow velocity in the edge area effectively counteracts a flashback. As a result of the targeted positioning of the lance shifted in the direction of the outlet opening, it can also be achieved that a flame front, which occurs during operation of the combustion chamber as a result of the combustion reaction, at least partially extends into the interior of the burner. This is due to the reduced flow velocity in the center of the velocity profile in the mixer. Through the targeted positioning or lengthening of the lance, the stationary flame front can run partially inside the burner. This is beneficial in several ways. On the one hand, the targeted introduction of fuel into the flame front can be improved with the aid of the lance, since the distance between the free-standing lance end and the flame front is reduced. On the other hand, the interaction between several burners of the combustion chamber via the combustion chamber is reduced, since the part of the flame front protruding into the respective burner interior is comparatively independent of the other burners and therefore stable with respect to the respective burner. The proposed construction thus makes it possible in particular to transfer results from test bench systems that only work with one burner to industrial systems in which the combustion chamber has several burners.

According to the invention, the lance has a plurality of concentrically arranged tubes on a central inner tube which contains a central channel for liquid fuel and has at least one axial outlet opening at the end of the lance. In addition, a hollow-walled outer tube is provided which encloses the inner tube with the formation of an inner annular channel and contains at least one outer channel for gaseous fuel in its hollow wall. The inner ring channel ends axially open at the end of the lance and is used to guide air. Due to the proposed construction with concentric tubes, on the one hand liquid fuel and on the other hand gaseous fuel can be fed alternately or simultaneously via the lance. At the same time, the air flow through the ring channel enables the lance to be cooled. Furthermore, the air flow through the inner ring channel makes flushing of the central channel or the at least one outer channel unnecessary if only gaseous or only liquid fuel is supplied via the lance. In addition, with the air supplied via the inner ring channel inside the burner, a media separation between liquid fuel and gaseous fuel can be achieved at least up to the flame front. This can be advantageous for realizing a stable combustion reaction.

Further important features and advantages of the burner according to the invention emerge from the subclaims, from the drawings and from the associated description of the figures with the aid of the drawings.

Brief description of the drawings

Fig. 1

einen stark vereinfachten Längsschnitt durch einen Brenner,

Fig. 2

eine Ansicht wie in Fig. 1, jedoch bei einer anderen Ausführungsform,

Fig. 3

eine Ansicht wie in den Fig. 1 und 2, jedoch bei ausgefahrener Lanze,

Fig. 4

eine Ansicht wie in den Fig. 1 und 2, jedoch mit einer detaillierteren Darstellung der Lanze,

Fig. 5

eine Darstellung wie in Fig. 4, jedoch bei einer anderen Ausführungsform der Lanze.

Preferred exemplary embodiments of the invention are shown in the drawings and are explained in more detail in the following description, with the same reference symbols referring to the same or similar or functionally identical components. They show, each schematically,

Fig. 1

a greatly simplified longitudinal section through a burner,

Fig. 2

a view like in Fig. 1 , but in a different embodiment,

Fig. 3

a view like in the Fig. 1 and 2 , but with the lance extended,

Fig. 4

a view like in the Fig. 1 and 2 , but with a more detailed representation of the lance,

Fig. 5

a representation as in Fig. 4 , but in a different embodiment of the lance.

Ways of Carrying Out the Invention

According to the Figs. 1 to 5 a burner 1 comprises a swirl generator 2, a mixer 3 and a lance 4. In the assembled state, the burner 1 forms part of a combustion chamber, otherwise not shown here, of a turbo group, which is in particular arranged in a power plant.

The swirl generator 2 encloses an inlet-side section of a burner interior 5 and has at least one air inlet 6 which extends tangentially with respect to a longitudinal center axis 7 of the burner 1. In the examples shown, the swirl generator 2 is designed to be conical. The respective air inlet 6 forms a longitudinal slot along the cone jacket. A plurality of such air inlets 6 are preferably arranged distributed in the circumferential direction. As a result, the air can penetrate tangentially into the burner interior 5, as a result of which it is subjected to a swirl. In the examples shown, the swirl generator 2 also has a fuel inlet 8, via which gaseous fuel can be introduced into the burner interior 5. For example, this fuel inlet 8 consists of several rows of individual inlet openings running along the surface line of the conical swirl generator 2, through which the fuel gas can enter the burner interior 5. The Fuel inlet 8 be aligned tangentially in order to increase the swirl effect. The fuel inlet 8 can also generate a certain radial component in order to improve the mixing with the air.

The mixer 3 encloses an outlet-side section of the burner interior 5 and has an outlet opening 9 which is open to a combustion chamber 10 of the combustion chamber. The mixer 3 comprises, for example, a tubular body 11 which is connected to the swirl generator 2 via a tubular transition piece 12 and which has an outlet flange 13 with the outlet opening 9. The burner 1 can be connected to the combustion chamber via the outlet flange 13. The mixer 3 is expediently cylindrical in shape.

The lance 4 is used to introduce pilot fuel into the combustion chamber 10. For this purpose, the lance 4 is arranged coaxially to the longitudinal center axis 7. Furthermore, the lance 4 extends, at least in a pilot mode of the burner 1, from a burner head 14, which essentially forms the tip of the conical swirl generator 2, into the burner interior 5. The lance 4 thus starts from the burner head 14 and ends with a lance end 15 free-standing in a section of the burner interior 5 enclosed by the mixer 3 at a distance 17 from the outlet opening 9 which is greater than 25% and less than 50% of the distance 18, which has an outlet-side end 19 of the swirl generator 2 from the outlet opening 9.

At the in Fig. 1 The embodiment shown also shows part of a flame front 16 which is formed during operation of the combustion chamber as a result of the combustion reaction taking place in the combustion chamber 10. It can be seen that part of this flame front 16 protrudes into the interior of the burner 5, specifically into an end section of the interior of the burner 5, which is enclosed by an end region of the mixer 3 on the outlet side. In the example shown, the flame front 16 remains within the section of the burner interior 5 that is enclosed by the outlet flange 13. or arrangement of the lance 4 is achieved. In the pilot operation of the burner 1, the lance 4 extends with its free-standing end 15 comparatively far into the burner interior 5, namely to the extent that part of the flame front 16 extends into the burner interior 5. So that the lance 4 can protrude so deep into the burner interior 5 in the direction of the outlet opening 9, the lance 4 must be designed accordingly so that it has the axial length required for this. In the Fig. 1 , 2 , 4th and 5 In the embodiments shown, the lance 4 is positioned in the burner 1 in such a way that its free-standing end 15 is located in a section of the burner interior 5 enclosed by the mixer 3. In other words, the lance 4 extends into the mixer 3. The lance 4 extends with its free-standing end 15 in the axial direction up to about half of the mixer 3 or even beyond it into the mixer 3. In Fig. 2 the registered distance 17 that the free-standing lance end 15 has from the outlet opening 9 is greater than 25% and smaller than 50% of the distance 18 that the outlet-side end 19 of the swirl generator 2 has from the outlet opening 9.

According to Fig. 2 For example, an inlet pipe 20, which extends coaxially to the lance 4, can be arranged on the burner head 14. This inlet pipe 20 protrudes in the axial direction into a section of the burner interior 5 enclosed by the swirl generator 2. This inlet pipe 20 can form an annular inlet channel 21 for liquid fuel. The inlet channel 21 has at least one axially oriented outlet opening 22. Through this at least one axial outlet opening 22, the liquid fuel can enter the burner interior 5 in accordance with arrows 48, essentially in the axial direction. The burner 1 can thus be operated with fuel gas and / or with liquid fuel. A plurality of such axial outlet openings 22 are preferably arranged at the end of the inlet pipe 20 which ends in the burner interior 5.

According to a preferred embodiment, the lance 4 can be arranged on the burner head 14 so as to be adjustable in the axial direction. The axial position of the free-standing lance end 15 within the burner interior 5 can thus be adjusted. In particular, the position of the part of the flame front 16 protruding into the burner interior 5 can thereby be adjusted. With the aid of the longitudinally adjustable lance 4, the burner 1 can be adapted to the operating parameters of the combustion chamber, which enables the combustion process to be stabilized. The lance 4 can thus be moved more or less deeply into the burner interior 5 or extended more or less far out of the burner interior 5, depending on requirements. Fig. 3 shows a situation in which the lance 4 is largely extended out of the burner interior 5. The lance end 15 then expediently ends on the inside of the burner head 14 facing the burner interior 5 Fig. 3 the lance 4 is fully extended to simplify the illustration. It can be moved back into the burner interior 5 according to an arrow 23. At the in Fig. 3 In the configuration shown, the flame front 16 is arranged completely outside the burner interior 5 and is located downstream of the outlet opening 9 with respect to the flow direction of the burner 1.

In Fig. 3 a speed profile 24 is shown in simplified form, which represents the distribution of the flow speed along the cross section of the burner 1 within the mixer 3. It can be seen that if there is no lance 4 in the center, the flow has a significant maximum. By moving the lance 4 into the described area within the mixer 3, the flow velocity in the center of the cross section of the mixer 3 is inevitably reduced. At the same time, the speed is thereby outside the lance 4, that is to say in the edge region of the cross section increased accordingly to ensure a constant volume flow. The reduction in the central flow velocity enables the flame front 16 to migrate upstream. With the appropriate positioning and configuration of the lance 4, the flame front 16 partially protrudes into the burner interior 5, as shown in FIG Fig. 1 is shown.

In the Fig. 4 and 5 the lance 4 is also shown in section. The following detailed description of the lance 4 also applies in particular to the embodiments of FIG Figs. 1 to 3 .

According to the Fig. 4 and 5 the lance 4 has several tubes arranged concentrically to one another, namely a central inner tube 25 and an outer tube 26. The inner tube 25 contains a central channel 27 and has axially oriented outlet opening 28 arranged at least on the free-standing lance end 15. The central channel 27 serves to supply liquid fuel to the at least one outlet opening 28. In the example, the inner tube 25 is equipped with a nozzle-shaped cross-sectional constriction 29 in the area of the outlet opening 28, which enables the formation of an intense liquid jet. This jet of liquid fuel is in the Fig. 4 and 5 indicated by an arrow 32. The outer tube 26 is dimensioned such that it encloses the inner tube 25 while forming an inner annular channel 30. This inner ring channel 30 is axially open at the lance end 15 and thus opens into the burner interior 5. The inner ring channel 30 is used to guide air, which can exit from the inner ring channel 30 in the axial direction according to an arrow 31.

The outer tube 26 is designed with a hollow wall, that is, the outer tube 26 has a hollow wall 33 with an inner wall 34 and an outer wall 35 radially spaced therefrom. In the hollow wall 33, the outer tube 26 contains at least one outer channel 36 ( Fig. 4 ) or 37 ( Fig. 5 ).

This at least one outer channel 36, 37 serves to supply gaseous fuel. The outer channel 36, 37 can be designed as an annular channel which is simply formed between the two walls 34, 35 of the wall 33. This outer ring channel 36 or 37 can according to Fig. 4 have at least one axially oriented outlet opening 38 at the lance end 15, whereby a substantially axially oriented injection of fuel gas according to an arrow 39 can be achieved. Additionally or alternatively, an in Fig. 5 Lance end section 40, which is marked with a curly bracket and which has the free-standing lance end 15, an arrangement of several radial outlet openings 41 can be provided. These radial outlet openings 41 are preferably formed in the outer wall 35 of the hollow wall 33 of the outer tube 26. In this way, a substantially radially oriented injection of the fuel gas into the burner interior 5 can be realized. The gaseous fuel injected radially in this way is deflected into the axial direction according to arrows 42 due to the prevailing axial flow inside the burner.

In order to be able to selectively implement the axial injection 39 and the radial injection 42 in an outer annular channel 36 or 37, a corresponding control can be provided which works, for example, with a sleeve-shaped control element that is located in a first position in front of the radial outlet openings 41, while in a second position it blocks the at least one axial outlet opening 38. A plurality of axial outlet openings 38 distributed in the circumferential direction are preferably arranged at the axial end of the outer tube 26.

As an alternative to this, at least one first outer channel 36 can be formed in the hollow wall 33, which leads at the lance end 15 to the at least one axial outlet opening 38. In addition to this, at least one second outer channel 37 can be formed in the hollow wall 33, which leads to at least one of the radial outlet openings 41 formed in the lance end section 40. Fig. 4 shows, for example, a section through the first outer channels 36, while Fig. 5 shows a section through the second outer channels 37. The first and second outer channels 36, 37 can be connected on the input side to different, independently operable supply devices or control devices. This makes it possible to introduce the gaseous fuel either through the at least one axial outlet opening 38 or only through the at least one radial outlet opening 41 or both through the at least one axial outlet opening 38 and through the at least one radial outlet opening 41.

In the Fig. 4 and 5 In the embodiments shown, the inner tube 25 protrudes axially beyond the outer tube 26. In this way, a certain media separation can be achieved during operation of the lance 4 for injecting the liquid fuel and for injecting the fuel gas. This media separation can also be supported by the air 31 that is blown in.

In the embodiments shown here, the inlet pipe 20 arranged on the burner head 14 is also designed with a hollow wall, so that it has a hollow wall 43 with an inner wall 44 and an outer wall 45. The hollow-walled inlet pipe 20 is also dimensioned here in such a way that it encloses the lance 4 or the outer pipe 26 while forming an axially open annular channel 46. Air can be blown into the interior of the burner through this annular channel 46 in accordance with an arrow 47. In this way, effective cooling of the lance in the area of the burner head 14 can be achieved. The inlet channel 21, which is used to introduce the liquid fuel according to arrows 48, is formed in the hollow wall 43 and can in particular also be configured in an annular manner.

the Fig. 4 and 5 show another specialty. In these embodiments, a wall 49 of the mixer 3 is equipped with a film cooling 50. Such a film cooling 50 is implemented, for example, by means of several cooling bores 51, which penetrate the corresponding wall 49 and can be flowed through by coolant, which is applied to the side of the wall 49 facing the burner interior 5 and thereby generates a cooling film protecting the wall 49. Air is usually used as the coolant. As shown here, the cooling bores 51 can be made in the main flow direction of the burner 1 in order to improve the formation of a cooling film.

List of reference symbols

1

burner

2

Swirl generator

3

mixer

4th

lance

5

Burner interior

6th

Air inlet

7th

Longitudinal central axis

8th

Fuel gas inlet

9

Outlet opening

10

Combustion chamber

11

Tubular body

12th

Transition piece

13th

Outlet flange

14th

Burner head

15th

free-standing lance end

16

Flame front

17th

Distance between 9 and 4

18th

Distance between 9 and 19

19th

downstream end of 2

20th

Inlet pipe

21

Inlet port

22nd

Inlet opening

23

Entry movement from 4

24

Speed profile

25th

Inner tube

26th

Outer tube

27

central channel

28

Outlet opening

29

jet

30th

inner ring channel

31

Air flow

32

Liquid fuel flow

33

hollow wall

34

Inner wall

35

Outer wall

36

(first) outer channel

37

(second) outer channel

38

axial outlet

39

Fuel gas flow

40

Lance end section

41

radial outlet opening

42

Fuel gas flow

43

hollow wall

44

Inner wall

45

Outer wall

46

Ring channel

47

Air flow

48

Liquid fuel flow

49

Wall of 3

50

Film cooling

51

Cooling bore

Claims (8)

1. Burner for a combustion chamber of a turbo group, at least comprising a swirl generator (2), a mixer (3), and a fuel injection device in the form of a lance (4) which introduces air and fuel into a burner interior (5) for a combustion reaction taking place in a combustion chamber (10), wherein the swirl generator (2) which surrounds the burner interior (5) on the inlet side has at least one air inlet (6) which is tangential with respect to a longitudinal centre axis (7), and the mixer (3) which surrounds the burner interior (5) on the outlet side has an outlet opening which is open towards the combustion chamber (10), and the lance (4) arranged coaxially to the longitudinal centre axis (7) for introduction of pilot fuel in a pilot operation of the burner (1) extends starting from a burner head (14) into the burner interior (5),

   characterised in that at least in pilot operation of the burner (1), the lance (4) extends so far into the burner interior (5) that a flame front (16) of the combustion reaction taking place in the combustion chamber (10) extends at least partially into an end portion of the burner interior (5) surrounded by an outlet-side end region of the mixer (3), in that at least in pilot operation of the burner (5), the lance (4) is arranged with its outlet-side end (15) in a portion of the burner interior (5) which is surrounded by the mixer (3), and a distance (17) of the lance end (15) from the outlet opening (9) is greater than 25% and less than 50% of the distance (18) of an outlet-side end (19) of the swirl generator (2) from the outlet opening (9);

   and that the lance (4) comprises several concentrically arranged tubes (25, 26);

   that a central inner tube (25) contains a central channel (27) for the liquid fuel and has at least one axial outlet opening (28) at the lance end (15);

   that a hollow-walled outer tube (26) surrounds the inner tube (25), forming an inner ring channel (30), and contains at least one outer channel (36, 37) for gaseous fuel in its hollow wall (33);

   and that the inner ring channel (30) is axially open at the lance end (15) and serves to guide air.
2. Burner according to claim 1, characterised in that the lance (4) is arranged length-adjustably on the burner head (14) so that depending on need, it can be introduced more or less deeply into and withdrawn more or less further from the burner interior (5).
3. Burner according to claim 1 or 2, characterised in that an inlet tube (20) is arranged on the burner head (14), and protrudes coaxially to the lance (4) into the portion of the burner interior (5) surrounded by the swirl generator (2), and forms an annular inlet channel (21) for liquid fuel which has at least one axial outlet opening (22).
4. Burner according to claim 3, characterised in that the inlet tube (20) has hollow walls, that the inlet tube (20) surrounds the lance (4), forming an axially open ring channel (46) for air, and that the inlet channel (21) is formed in the hollow wall (43) of the inlet tube (20).
5. Burner according to claim 1, characterised in that the outer channel (36, 37) is formed in the hollow wall (33) of the outer tube (26) as a ring channel which has at least one axial outlet opening (28) at the lance end (15), and/or the lance end portion (40) comprising the lance end (15) has several radial outlet openings (41).
6. Burner according to claim 1, characterised in that at least one (first) outer channel (36) is formed in the hollow wall (33) of the outer tube (26) and has at least one axial outlet opening (28) at the lance end (15), and/or at least one (second) outer channel (37) is formed in the hollow wall (33) of the outer tube (26) and has several radial outlet openings (41) in a lance end portion (40) comprising the lance end (15).
7. Burner according to one of claims 1 or 5 to 6, characterised in that the inner tube (25) protrudes axially over the outer tube (26).
8. Burner according to any of claims 1 to 7, characterised in that a wall (49) of the mixer (3) is equipped with film cooling (50).

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