EP2179222B1 - 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 intended for gas turbines injection device, which is designed in the manner of a lance and cantilevered into a burner. At the free end of the lance axial discharge openings for fuel and air are provided, such that a sheathed by a Abschirmluftstrom fuel jet is generated. To control the quantity ratio between fuel and shielding air is provided to exploit the temperature changes occurring at the injector. In this way, an automatic adaptation to different operating states is to be achieved in such a way that an optimal operation is maintained all the time. Incidentally, this document can be taken from the reference that it is known to provide aerodynamic methods for flame stabilization, reference being made to swirl flows. It is emphasized that the entire flow in spin-stabilized burners is extremely sensitive to changes in the flow field.

With regard to the arrangement of the lance in the burner no more detailed instructions are given. In addition, no more detailed statements are made with respect to the design of the burner.

From the EP 1 526 333 A1 For example, a gas turbine fuel injector is known. The injector has a rod-like end piece, which is arranged at the head of a vortex chamber substantially coaxially to the longitudinal axis of this chamber. This vortex chamber opens on the output side into a combustion chamber.

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

The EP 0 704 657 A2 relates to a burner for gas turbines or the like. This burner consists upstream of a swirl generator and an axially subsequent mixing section, wherein at the beginning of a mixing tube, a special transition geometry is provided, such that the mixing tube is penetrated by a swirl flow. On the outflow side of the transition geometry are placed in the wall of the mixing section filing holes, which cause an increase in the flow velocity along the pipe wall. On the output side, the mixing section opens into a combustion chamber in which a backflow zone is formed in the region of a cross-sectional jump between the mixing section and the combustion chamber, which zone is intended to act as a flame holder. In a cylindrical initial part upstream of the swirl generator, a central fuel nozzle for injecting a particular liquid fuel is arranged in 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 feed device for feeding a gaseous oxidizer into a mixing space to which gaseous fuel is fed by means of a gas fuel feed device and liquid fuel is fed by means of a liquid fuel feed 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 configured so that the spray jet generated has a component radially to a main outflow direction of the burner.

In the DE 103 34 228 A1 For example, a method of operating a premix burner will be described. This has several groups of injection ports for premix fuel and a central fuel injection with multiple injection ports. In this case, different groups of the injection openings are acted upon independently of each other with gaseous fuel, on the one hand to form a premixing stage and on the other hand, a diffusion stage of the premix burner. As a result, an extended operating range of the premix burner is to be realized with low pollutant emissions.

Despite the diverse state of the art in burners of the type described above, the problem of a flashback from the combustion chamber into the burner inside.

Such flashbacks are due to instabilities in the combustion process.

Presentation of the invention

This is where the present invention begins. The invention, as characterized in the claims deals with the problem for a burner of 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.

This problem is solved according to the invention 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 to design the lance much longer, so that it can protrude deeper in the direction of the outlet opening into the burner interior. Here, the knowledge is used that a velocity profile is formed in the mixer for the mixture flow, which has significantly higher velocities in the center than in the edge region. By extending 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 velocity in the edge regions increases. However, the increased flow velocity in the edge region effectively counteracts flashback. The targeted, in the direction of the outlet opening displaced positioning of the lance can also be achieved that a flame front, which arises during operation of the combustion chamber by the combustion reaction, at least partially into the burner interior protrudes. This is due to the reduced flow rate at the center of the velocity profile in the mixer. Due to the targeted positioning or extension of the lance thus the stationary flame front can partially extend within the burner interior. This is advantageous in several ways. On the one hand, the targeted introduction of fuel into the flame front can be improved with the help 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 a plurality of burners of the combustion chamber is reduced via the combustion chamber, since the part of the flame front projecting into the respective burner interior is comparatively independent of the other burners with respect to the respective burner and thus stable. The proposed construction thus makes it possible, in particular, to transfer results from test bench installations which only work with one burner to industrial installations in which the combustion chamber has a plurality of burners.

In an advantageous embodiment it can be provided that the lance has a plurality of concentrically arranged tubes, for example a central inner tube, which contains a central channel for liquid fuel and at least one axial outlet opening at the end of the lance. In addition, a hollow-walled outer tube may be provided, which encloses the inner tube to form an inner annular channel and contains in its hollow wall at least one outer channel for gaseous fuel. The inner ring channel ends axially open at the end of the lance and serves to guide air. Due to the proposed construction with concentric pipes, on the one hand, liquid fuel and, on the other hand, gaseous fuel can be supplied alternately or simultaneously via the lance. At the same time allows the air flow through the annular channel cooling the lance. Furthermore, the air duct through the inner annular channel rinses the central channel or the at least one outer channel dispensable if only gaseous or only liquid fuel is supplied via the lance. In addition, with the supplied via the inner ring channel air inside the burner media separation between liquid fuel and gaseous fuel can be achieved at least to the flame front. This can be advantageous for realizing a stable combustion reaction.

Other important features and advantages of the burner according to the invention will become apparent from the subclaims, from the drawings and from the associated description of the figures with reference to 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 embodiments of the invention are illustrated in the drawings and will be described in more detail in the following description, wherein like reference numerals refer to the same or similar or functionally identical components. Show, in each case schematically,

Fig. 1

a greatly simplified longitudinal section through a burner,

Fig. 2

a view like in Fig. 1 but in another 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 depiction of the lance,

Fig. 5

a representation like in Fig. 4 but in another embodiment of the lance.

Ways to carry out the invention

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

The swirl generator 2 encloses an input-side section of a burner interior 5 and has at least one air inlet 6, which extends tangentially with respect to a longitudinal central axis 7 of the burner 1. In the examples shown, the swirl generator 2 is configured conical. The respective air inlet 6 forms a longitudinal slot along the cone sheath. Preferably, a plurality of such air inlets 6 are arranged distributed in the circumferential direction. As a result, the air can penetrate tangentially into the burner interior 5, whereby it is acted upon by a twist. 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, along the generatrix of the conical swirl generator 2 extending rows of individual inlet openings through which the fuel gas can enter the burner interior 5. In this case, the fuel inlet 8 may be aligned tangentially to increase the swirl effect. Likewise, the fuel inlet 8 may generate some radial component to enhance mixing with the air.

The mixer 3 encloses an output-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 via a tubular transition piece 12 to the swirl generator 2 and which carries an outlet flange 13 with the outlet opening 9. About the outlet 13, the burner 1 can be connected to the combustion chamber. Suitably, the mixer 3 is cylindrically shaped.

The lance 4 is used for introducing pilot fuel into the combustion chamber 10. For this purpose, the lance 4 is arranged coaxially to the longitudinal central axis 7. Furthermore, at least in a pilot operation of the burner 1, the lance 4 extends into the burner interior 5 from a burner head 14, which essentially forms the tip of the conical swirl generator 2. The lance 4 thus starts from the burner head 14 and ends with a lance end 15 freestanding in a portion 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, has an outlet-side end 19 of the swirl generator 2 from the outlet opening 9.

At the in Fig. 1 In addition, a portion of a flame front 16 is shown, which forms during operation of the combustion chamber through the running in the combustion chamber 10 combustion reaction. As can be seen, part of this flame front 16 projects into the burner interior 5, specifically into an end section of the burner interior 5, which is enclosed by an outlet-side end region of the mixer 3. In the example shown, the flame front 16 remains within the section of the burner interior 5 enclosed by the outlet flange 13. Such a course of the flame front 16, in which a part of the flame front 16 passes through the outlet opening 9 into the interior Burner interior 5 projects, is achieved by a special configuration and / or arrangement of the lance 4. 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 a part of the flame front 16 extends into the burner interior 5 inside. Thus, 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 necessary axial length for this purpose. In the in the Fig. 1 . 2 . 4 and 5 In the embodiment shown, the lance 4 is positioned in the burner 1 so 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. In this case, the lance 4 extends with its free-standing end 15 in the axial direction to about half of the mixer 3 or even beyond in the mixer 3 into it. In Fig. 2 is the registered distance 17, which has the free-standing lance end 15 of the outlet opening 9, greater than 25% and less than 50% of the distance 18, the outlet-side end 19 of the swirl generator 2 from the outlet opening 9 has.

According to Fig. 2 can be arranged on the burner head 14, an inlet tube 20 which extends coaxially with the lance 4. This inlet tube 20 protrudes in the axial direction into a section of the burner interior 5 enclosed by the swirl generator 2. This inlet pipe 20 may form an annular inlet channel 21 for liquid fuel. The inlet channel 21 has at least one axially oriented outlet opening 22. By virtue of these at least one axial outlet opening 22, the liquid fuel can enter the burner interior 5 substantially in the axial direction, as indicated by arrows 48. The burner 1 can thus be operated with fuel gas and / or with liquid fuel. Preferably, a plurality of such axial outlet openings 22 are arranged at the end of the inlet tube 20 ending in the burner interior 5.

According to a preferred embodiment, the lance 4 may be arranged in the axial direction adjustable on the burner head 14. Thus, the axial position of the free-standing lance end 15 within the burner interior 5 is adjustable. In particular, this allows the position of the part of the flame front 16 projecting into the burner interior 5 to be adjusted. With the help of the longitudinally adjustable lance 4, the burner 1 can be adapted to operating parameters of the combustion chamber, which allows stabilization of the combustion process. The lance 4 can thus be retracted more or less deep into the burner interior 5, depending on demand, or extend more or less far out of the burner interior 5. Fig. 3 shows a situation in which the lance 4 is largely extended from the burner interior 5. The lance end 15 expediently ends at the inside of the burner head 14 facing the burner interior 5 Fig. 3 For simplicity, the lance 4 is fully extended. It can be retracted according to an arrow 23 back into the burner interior 5. 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 In a simplified manner, a velocity profile 24 is shown, which represents the distribution of the flow velocity along the cross section of the burner 1 within the mixer 3. Visible, the flow has a significant maximum in the absence of lance 4 in the center. By retracting 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 correspondingly increased outside the lance 4, ie in the edge region of the cross section, in order to ensure a constant volume flow. The reduction of central flow velocity allows the flame front 16 to travel upstream. With appropriate positioning and design of the lance 4, the flame front 16 protrudes partially into the burner interior 5, as in Fig. 1 is shown.

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

According to the Fig. 4 and 5 The lance 4 has a plurality of concentrically arranged tubes, namely a central inner tube 25 and an outer tube 26. The inner tube 25 includes a central channel 27 and has at least the free-standing lance end 15 arranged axially oriented outlet opening 28. The central channel 27 is used to supply liquid fuel to at least one outlet opening 28. In the example, the inner tube 25 is provided in the region of the outlet opening 28 with a nozzle-shaped cross-sectional constriction 29, which allows the formation of an intense liquid jet. This liquid fuel jet is in the Fig. 4 and 5 indicated by an arrow 32. The outer tube 26 is sized so that it surrounds the inner tube 25 to form an inner annular channel 30. This inner annular channel 30 is axially open at the end of the lance 15 and thus opens into the burner interior 5. The inner annular channel 30 serves to guide air, which can emerge from the inner annular channel 30 in the axial direction according to an arrow 31.

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

This at least one outer channel 36, 37 serves to supply gaseous fuel. The outer channel 36, 37 may be configured as an annular channel, which is simply formed between the two walls 34, 35 of the wall 33. This outer annular 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, in an in Fig. 5 a lance end portion 40, having a brace, having the free-standing lance end 15, may be an array of a plurality of radial exit openings 41. These radial outlet openings 41 are preferably formed in the outer wall 35 of the hollow wall 33 of the outer tube 26. As a result, a substantially radially oriented injection of the fuel gas into the burner interior 5 can be realized. The thus radially injected gaseous fuel is thereby deflected according to arrows 42 due to the prevailing axial flow in the burner interior in the axial direction.

In order to be able to selectively realize the axial injection 39 and the radial injection 42 in the case of an outer annular channel 36 or 37, a corresponding control may be provided which, for example, operates with a sleeve-shaped control element which lies in a first position in front of the radial outlet openings 41. while it locks in a second position, the at least one axial outlet opening 38. Preferably, a plurality of circumferentially distributed axial outlet openings 38 are arranged at the axial end of the outer tube 26.

Alternatively, in the hollow wall 33 at least a first outer channel 36 may be formed, which at the lance end 15 to the at least one axial outlet opening 38 leads. In addition, at least one second outer channel 37 may 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 a section through the second outer channels 37 shows. The first and second outer channels 36, 37 may be connected on the input side to various, independently operable supply devices or control devices. This makes it possible to selectively introduce the introduction of the gaseous fuel only 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 in the Fig. 4 and 5 shown embodiments, the inner tube 25 projects axially beyond the outer tube 26. In this way, a certain separation of media during operation of the lance 4 for injecting the liquid fuel and for injecting the fuel gas can be achieved. This media separation can also be assisted by the injected air 31.

In the embodiments shown here, moreover, the inlet pipe 20 arranged at the burner head 14 is hollow-walled, so that it has a hollow wall 43 with an inner wall 44 and an outer wall 45. The hollow-walled inlet tube 20 is here also dimensioned so that it encloses the lance 4 and the outer tube 26 to form an axially open annular channel 46. Through this annular channel 46 47 air can be injected into the burner interior according to an arrow. In this way, an effective cooling of the lance in the region of the burner head 14 can be achieved. The inlet channel 21 corresponding to the introduction of the liquid fuel Arrows 48 is used, is formed in the hollow wall 43 and may also be configured in particular ring-shaped.

The Fig. 4 and 5 show another special feature. In these embodiments, a wall 49 of the mixer 3 is provided with a film cooling 50. Such a film cooling 50 is realized for example by means of a plurality of cooling holes 51 which pass through the corresponding wall 49 and can be flowed through by coolant, which applies to the side of the wall 49 facing the burner interior 5 and thereby generates a cooling film protecting the wall 49. As a coolant is usually air. The cooling holes 51 may be set in the main flow direction of the burner 1 as shown here to enhance the formation of a cooling film.

LIST OF REFERENCE NUMBERS

1

burner

2

swirl generator

3

mixer

4

lance

5

Brenner Affairs

6

air intake

7

Longitudinal central axis

8th

Fuel gas inlet

9

outlet

10

combustion chamber

11

pipe body

12

Transition piece

13

outlet flange

14

burner head

15

freestanding lance end

16

flame front

17

Distance between 9 and 4

18

Distance between 9 and 19

19

downstream end of 2

20

inlet pipe

21

inlet channel

22

inlet port

23

Entry movement of 4

24

velocity profile

25

inner tube

26

outer tube

27

central channel

28

outlet opening

29

jet

30

inner ring channel

31

airflow

32

Liquid fuel flow

33

hollow wall

34

inner wall

35

outer wall

36

(first) outer channel

37

(second) outer channel

38

axial outlet opening

39

Fuel gas flow

40

Lanzenendabschnitt

41

radial outlet opening

42

Fuel gas flow

43

hollow wall

44

inner wall

45

outer wall

46

annular channel

47

airflow

48

Liquid fuel flow

49

Wall of 3

50

film cooling

51

cooling hole

Claims (9)

1. Burner for a combustion chamber of a turbogroup, at least comprising a swirl generator (2), a mixer (3) and a fuel injection device in the form of a lance (4) which introduces, into a burner interior (5), air and fuels for a combustion reaction taking place in a combustion space (10), wherein the swirl generator (2), which encloses the burner interior (5) on the inlet side, has at least one air inlet (6) tangential to a longitudinal centre axis (7), and the mixer (3), which encloses the burner interior (5) on the outlet side, has an outlet opening which is open towards the combustion space (10), and the lance (4), arranged coaxially to the longitudinal centre axis (7), for introducing pilot fuel, in a pilot mode of the burner (1), extends from a burner head (14) into the burner interior (5), characterized in that the lance (4), at least in the pilot mode of the burner (1), extends far enough into the burner interior (5) for a flame front (16) of the combustion reaction, which takes place in the combustion space (10), to extend at least partially into an end section of the burner interior (5) which is enclosed by an outlet-side end region of the mixer (3), by virtue of the fact that the lance (4), at least in the pilot mode of the burner (1), is arranged with its outlet-side end (15) in a section of the burner interior (5) which is enclosed 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) which an outlet-side end (19) of the swirl generator (2) has from the outlet opening (9).
2. Burner according to Claim 1, characterized in that the lance (4) is arranged on the burner head (14) in a longitudinally-adjustable manner so that, depending upon requirement, it can be extended to a greater or lesser depth into the burner interior (5) and can be retracted from it by a greater or lesser distance.
3. Burner according to Claim 1 or 2, characterized in that an inlet pipe (20), which projects coaxially to the lance (4) into the section of the burner interior (5) which is enclosed by the swirl generator (2) and forms an annular inlet passage (21) for liquid fuel which has at least one axial outlet opening (22), is arranged on the burner head (14).
4. Burner according to Claim 3, characterized in that the inlet pipe (20) is of a hollow-walled design, in that the inlet pipe (20) encloses the lance (4), forming an axially open annular passage (46) for air, and in that the inlet passage (21) is formed in the hollow wall (43) of the inlet pipe (20).
5. Burner according to one of Claims 1 to 4, characterized in that the lance (4) has a plurality of concentrically arranged pipes (25, 26), in that a central inner pipe (25) includes a central passage (27) for liquid fuel and has at least one axial outlet opening (28) at the lance end (15), in that a hollow-walled outer pipe (26) encloses the inner pipe (25), forming an inner annular passage (30) and in its hollow wall (33) includes at least one outer passage (36, 37) for gaseous fuel, and in that the inner annular passage (30) terminates axially open at the lance end (15) and serves for the guiding of air.
6. Burner according to Claim 5, characterized in that the outer passage (36, 37) in the hollow wall (33) of the outer pipe (26) is designed as an annular passage which has at least one axial outlet opening (28) at the lance end (15) and/or which has a plurality of radial outlet openings (41) in a lance end section (40) which has the lance end (15).
7. Burner according to Claim 5, characterized in that at least one (first) outer passage (36), which has at least one axial outlet opening (28) at the lance end (15), is formed in the hollow wall (33) of the outer pipe (26), and/or in that at least one (second) outer passage (37), which has a plurality of radial outlet openings (41) in a lance end section (40) which has the lance end (15), is formed in the hollow wall (33) of the outer pipe (26).
8. Burner according to one of Claims 5 to 7, characterized in that the inner pipe (25) projects axially beyond the outer pipe (26).
9. Burner according to one of Claims 1 to 8, characterized in that a wall (49) of the mixer (3) is equipped with film cooling (50).

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