BURNER FOR A TURBINE

Abstract

A burner for a turbine has a flame tube, a casing enclosing the flame tube forming an oxidant collection chamber, a burner bottom which bounds the oxidant collection chamber and the combustion space, and a swirler which has a plurality of guide vanes arranged so that the distances between the guide vanes form a plurality of radial inlet passages to the combustion space. A fuel supply pipe is provided in the inlet flow region of at least some of the inlet passages, which fuel supply pipe extends lengthwise through the respective inlet passage in an axial direction of the burner and traverse to an oxidant flow direction, and wherein each fuel supply pipe has in its wall at least one radial fuel output opening by which fuel can be mixed into the respective inlet passage with a directional component extending transverse to the oxidant flow direction.

Description

The present invention is directed to a burner for a turbine and particularly to a burner which is provided with a device for premixing oxidant and fuel for a turbine.

BACKGROUND OF THE INVENTION

Premix burners, as they are called, are used in turbines, e.g., gas turbines in order to achieve lower emissions. Through the use of premix technology, the process of mixing fuel and oxidant such as air is decoupled from, i.e., made antecedent to, the actual combustion process. Peak temperatures during combustion can be reduced in this way. At the same time, the retention time of the fuel-oxidant mixture (e.g., fuel-air mixture) in the reaction zone is shortened. In particular, this reduces the formation of NOx (particularly thermal NOx). Different “premix burners” are used in atmospheric combustion and in combustion under pressure. Also, different burners are used in the field of gas turbines. In an optimal burner, combustion should proceed within a large operating range stably, in a controlled manner, with low emissions, and as completely as possible. In this regard, the quality of the fuel-oxidant mixture is always the focus of concern. Mixing is crucial for the local combustion temperature and accordingly for the reaction products, i.e., emissions. Therefore, the location and aerodynamics of the fuel injection arrangement must be carefully selected.

DE 10 2008 019 117 A1 describes a burner for a turbine, which burner is provided with a device for premixing air and fuel. According to this document, the burner has a cylindrical combustion chamber for gaseous or liquid fuel and a main injector. The combustion chamber is bounded in an axial direction of the burner on one side by a burner bottom and radially by a flame tube. The main injector serves to inject a premixed fuel-air mixture. Injection is carried out radial to a longitudinal axis of the burner via main nozzles which open into a radial swirler. The radial swirler is arranged between the burner bottom and the flame tube and causes a swirl momentum to be imparted to the fuel-air mixture which then swirls into the combustion chamber.

Other burners provided with a device for premixing oxidant and fuel are described in DE 198 59 210 A1 and DE 38 19 898 A1.

It is an object of the invention to provide a burner for a turbine in which an extremely homogeneous premixing of a fuel-oxidant mixture, e.g., a fuel-air mixture, to be introduced into a combustion chamber of the burner is achieved in a simple and economical way.

SUMMARY OF THE INVENTION

According to the present invention, a burner for a turbine has a flame tube in which a combustion space is formed, a casing enclosing the flame tube from radially outward at a predetermined distance therefrom so that an oxidant collection chamber is formed between the flame tube and casing, a burner bottom which bounds the oxidant collection chamber and the combustion space at an axial end of the burner, and a swirler which is arranged axially between the flame tube and burner bottom axially adjoining the burner bottom and radially adjoining the oxidant collection chamber for supplying a fuel-oxidant mixture into the combustion space, wherein the swirler has a plurality of guide vanes arranged at a circumferential distance from one another along a circumferential direction of the burner so that the respective distances between the guide vanes form a plurality of radial inlet passages to the combustion space, each of which has a tangential component along its path, and a fuel supply pipe is provided in a respective inlet flow region of at least some of the plurality of inlet passages, which fuel supply pipe extends lengthwise through the respective inlet passage in an axial direction of the burner and traverse to an oxidant flow direction, and each fuel supply pipe has in its wall at least one fuel output opening radial to the fuel supply pipe by which fuel can be mixed into the respective inlet passage with a directional component extending transverse to the oxidant flow direction.

Air which is fed into the oxidant collection chamber at atmospheric pressure or at increased pressure is preferably provided as oxidant.

Due to the fact that the injection of fuel into the burner according to the invention is carried out inside the inlet passages or air channels of the swirler through individual fuel supply pipes with a directional component extending transverse to the oxidant flow direction, an extremely homogeneous premixing of the fuel-oxidant mixture, e.g., a fuel-air mixture, to be introduced into the combustion chamber of the burner is achieved in a simple and economical manner.

Through the possibility of optionally configuring the fuel output opening(s) which is/are preferably constructed as a bore hole and the optionally selectable positioning of the fuel supply pipes and fuel output opening(s) inside the respective inlet flow regions and at the respective fuel supply pipes, respectively, an optimal premixing of fuel (e.g., combustible gas) and oxidant (e.g., air) can be achieved. Insofar as the fuel composition changes, the fuel output openings can be adapted in size and shape.

According to an embodiment of the present invention, all of the inlet passages are provided with a fuel supply pipe.

This advantageously promotes a particularly homogeneous mixing of fuel and oxidant before introducing into the combustion chamber.

According to another embodiment of the invention, at least one of the fuel supply pipes is arranged in the respective inlet passage.

This embodiment of the invention presents an advantageous variant for the arrangement of one or more or all of the fuel supply pipes, wherein the respective position in the inlet passage is optionally selectable and, therefore, the mixing length of fuel and oxidant is optionally changeable.

According to yet another embodiment of the invention, at least one of the fuel supply pipes is arranged directly in front of the respective inlet passage in the oxidant flow direction, i.e., at the start of the inlet flow region.

This embodiment of the invention presents another advantageous variant for the arrangement of one or more or all of the fuel supply pipes, wherein the mixing length or mixing distance of fuel and oxidant is extended to the maximum degree.

According to another embodiment of the invention, at least one of the fuel supply pipes is arranged off-center in the respective inlet passage with respect to a center longitudinal axis of the respective inlet passage.

This embodiment of the invention presents another advantageous variant for the arrangement of one or more or all of the fuel supply pipes, wherein the respective off-center position in the inlet passage transverse to the center longitudinal axis thereof is optionally selectable and the swirl intensity of the fuel is therefore optionally variable. According to an embodiment of the invention, at least one of the fuel supply pipes or a plurality or all of the fuel supply pipes are arranged centrally in the respective inlet passage with respect to the center longitudinal axis of the respective inlet passage.

According to another embodiment of the invention, at least one of the fuel supply pipes has a plurality of fuel output openings which are arranged at a distance from one another along the length of the fuel supply pipe.

With this embodiment of the invention, the homogeneous mixing of fuel and oxidant can be improved even further. Therefore, a plurality of or all of the fuel supply pipes are each preferably provided with a plurality of fuel output openings arranged at a distance from one another along the length of the fuel supply pipes.

According to yet another embodiment of the invention, at least one of the fuel supply pipes has two fuel output openings which are arranged at the same position with respect to the length of the fuel supply pipe so that fuel can be delivered from the fuel supply pipe via these two fuel output openings with two directional components opposed to one another.

According to this embodiment of the invention, by means of the output of fuel into the inlet passage in opposite directions, the oxidant flow on both sides of the fuel supply pipe is used to swirl the fuel and the homogeneous mixing of fuel and oxidant is therefore further improved.

A plurality of or all of the fuel supply pipes preferably each have two fuel output openings which are arranged at the same position with respect to the length of the fuel supply pipe so that fuel can be delivered from the fuel supply pipe via these two fuel output openings with two directional components opposed to one another.

Still more preferably, each fuel output opening of a respective fuel supply pipe has a fuel output opening of this kind arranged at the same position with respect to the length of the fuel supply pipe which outputs the fuel thereof with an opposed directional component.

Naturally, in addition to optimal “standard positions”, optimization with respect to emissions and flashback behavior can also be carried out individually depending on fuel.

According to further embodiments of the invention, viewed with respect to the cross section of the respective fuel supply pipe, the two fuel output openings are located diametrically opposite one another or respective center longitudinal axes of the two fuel output openings enclose an obtuse angle with one another.

Also, with this embodiment of the invention, the intensity of the swirling and entrainment of the fuel in the oxidant can be influenced in a simple, efficient manner and can accordingly be optimized for the respective application.

According to further embodiments of the invention, the fuel supply pipes each have a cylindrical cross section or an airfoil-shaped cross section or other cross sections suitable for optimal swirling. According to the invention, all of the fuel supply pipes can have the same cross-sectional shape. Embodiments in which groups of fuel supply pipes are formed, wherein all fuel supply pipes within a group have the same cross-sectional shape, but the groups have different cross-sectional shapes, are likewise possible.

For example, the airfoil shape can prove advantageous for reducing a direct mixing in the downstream piping, which may be necessary particularly in the case of reactive fuels (e.g., hydrogen).

According to another embodiment of the invention, the fuel supply pipes are each detachably mounted so that each fuel supply pipe which is formed in accordance with a predetermined fuel mixing configuration can be individually exchanged if necessary for a fuel supply pipe based on another predetermined fuel mixing configuration.

Owing to the simple exchangeability of the fuel supply pipes, the burner can be adapted simply and quickly when changing fuel. Typically, the burner according to the invention is suitable for use of combustible gas as fuel. But the burner according to the invention can also be operated with liquid fuel, in which case special nozzles should be inserted in the fuel output openings, as the case may be.

Through the use of the central fuel supply pipes in the inlet passages of the swirler, optimal mixtures of fuel (e.g., combustible gas) and oxidant (e.g., air) are possible. Low emissions can be achieved in this way. At the same time, the individual configuration of fuel output openings and/or positioning of the fuel supply pipes makes it possible to respond to locally different oxidant distributions, e.g., locally different air distributions. The solution according to the invention is very economical due to the central exchangeable fuel supply pipes.

BRIEF DESCRIPTION OF THE DRAWING

The invention will be described more fully in the following with reference to preferred embodiments and the accompanying drawings in which:

FIG. 1 is a schematic longitudinal sectional view through the construction of a burner of a gas turbine according to an embodiment of the present invention;

FIG. 2 is a schematic cross-sectional view of a portion of the burner from FIG. 1 viewed along a line A-A in FIG. 1;

FIGS. 3 a)-c) are enlarged partial views of an inlet passage of the burner from FIG. 2 showing three possible configurations of a fuel supply pipe;

FIGS. 4 a) and b) shows two possible configurations of a fuel supply pipe in an inlet passage of the burner according to the invention viewed along a line B-B in FIG. 2.

DETAILED DESCRIPTION OF THE PRESENTLY PREFERRED EMBODIMENTS

FIG. 1 shows the construction of a burner 1 of a gas turbine (not shown in its entirety) according to an embodiment of the present invention.

The burner 1 has a flame tube 10 in which a combustion space 11 is formed and a tubular casing 20 which encloses the flame tube 10 from radially outward at a predetermined distance therefrom so that an oxidant collection chamber 21 is formed between the flame tube 10 and casing 20.

Combustible gas is provided as fuel for the burner 1, and atmospheric air is provided as oxidant for the combustible gas. This atmospheric air is compressed by a compressor (not shown) and then fed to the oxidant collection chamber 21.

Further, the burner 1 has a burner bottom 30 which bounds the oxidant collection chamber 21 and combustion space 11 at an axial end of the burner 1 and a swirler 40 which is arranged axially between the flame tube 10 and burner bottom 30 axially adjoining the burner bottom 30 and radially adjoining the oxidant collection chamber 21 for supplying a fuel-oxidant mixture BOG into the combustion space 11.

Referring additionally to FIG. 2 which shows a sectional view of a portion of the burner from FIG. 1 viewed along a line A-A in FIG. 1, the swirler 40 has a plurality of (in this case, eight) guide vanes 41 arranged at a circumferential distance from one another along a circumferential direction UR of the burner 1.

The guide vanes 41 are each shaped and arranged in such a way that the respective distances between the guide vanes 41 form a plurality of (in this case, eight) radial inlet passages 42 toward the combustion space 11, each of which has a tangential component along its path.

A fuel supply pipe 43a, 43b, 43c, 43d which extends with respect to its length through the respective inlet passage 42 in an axial direction AR (see FIG. 1) of the burner 1 and traverse to an oxidant flow direction OR is provided in a respective inlet flow region of at least some of the plurality of inlet passages 42.

Although FIG. 2 shows a fuel supply pipe 43a, 43b, 43c, 43d in only four of the eight inlet passages 42, fuel supply pipes 43a, 43b, 43c, 43d can also be provided in more or in fewer or in all inlet passages 42 according to embodiment forms of the invention which are not shown.

As is shown in FIGS. 3 and 4, each fuel supply pipe 43a, 43b, 43c, 43d has in its wall at least one fuel output opening 44, 45 radial to the fuel supply pipe 43a, 43b, 43c, 43d by which fuel BS can be mixed into the respective inlet passage 42 with a directional component extending transverse to the oxidant flow direction OS. Each fuel output opening 44, 45 is preferably formed as a bore hole or as a nozzle insert.

As can be seen from FIG. 2, one or more or all of the fuel supply pipes 43a, 43b, 43d can be arranged directly in the respective inlet passages 42. As can also be seen from FIG. 2, the fuel supply pipes 43a, 43b, 43d can be arranged in the respective inlet passages 42 at different positions along the length of the respective inlet passages 42.

On the other hand, one or more or all of the fuel supply pipes 43c can be arranged directly in front of the respective inlet passages 42 in the oxidant flow direction OS (i.e., at the input of the respective inlet passages 42 partially or entirely in the oxidant collection chamber 21).

As can also be seen from FIG. 2, one or more or all of the fuel supply pipes 43a, 43b, 43c can be arranged centrally in the respective inlet passages 42 with respect to center longitudinal axes L of the respective inlet passages 42. On the other hand, one or more or all of the fuel supply pipes 43d can also be arranged off-center in the respective inlet passages 42 with respect to center longitudinal axes L thereof.

As can be seen from FIG. 4, one or more or all of the fuel supply pipes 43a, 43b, 43c, 43d can have a plurality of fuel output openings 44, 45 which are arranged at a distance from one another along the respective length of the fuel supply pipes 43a, 43b, 43c, 43d [variant a) in FIG. 4]. On the other hand, one or more or all of the fuel supply pipes 43a, 43b, 43c, 43d can also have only one individual fuel output opening 44, 45 with respect to the respective length of the fuel supply pipes 43a, 43b, 43c, 43d [variant b) in FIG. 4].

As can be seen from FIG. 3, one or more or all central fuel supply pipes 43a, 43b, 43c (designated 43a-c in FIG. 3) and also one or more or all off-center fuel supply pipes 43d (not shown in FIG. 3) can have two fuel output openings 44, 45 which are arranged at the same position with respect to the length of the fuel supply pipe so that fuel BS can be delivered from the respective fuel supply pipe 43a, 43b, 43c, 43d via these two fuel output openings 44, 45 with two directional components opposed to one another (as is indicated by the oppositely directed exit arrows for fuel BS).

As can also be seen from FIG. 3, the two fuel output openings 44, 45, viewed with respect to the cross section of the respective fuel supply pipe 43a, 43b, 43c, 43d, can be located diametrically opposite one another [variant a) in FIG. 3], or respective center longitudinal axes L1, L2 of the two fuel output openings 44, 45 can enclose an obtuse angle α (45°<α<180°) with one another [variants b) and c) in FIG. 3].

Naturally, it would also be possible within the framework of the invention to let the respective fuel output openings 44, 45 located diametrically opposite one another or at an obtuse angle α relative to one another alternate over the length of the fuel supply pipe 43a, 43b, 43c, 43d so that only one individual fuel output opening 44, 45 is arranged at each length position of the fuel supply pipe 43a, 43b, 43c, 43d.

As can be seen from FIGS. 2 to 4, the fuel supply pipes 43a, 43b, 43c, 43d each have a cylindrical cross section. However, according to embodiment forms of the invention which are not shown in the drawings, the fuel supply pipes 43a, 43b, 43c, 43d can also have an airfoil-shaped cross section or other cross- sectional shapes suitable for a homogeneous mixing of oxidant and fuel. An airfoil shape is shown with respect to guide vanes, for example, in DE 38 19 898 A1, FIG. 2, the content of which is incorporated herein by reference in its entirety.

Although not shown in detail in FIGS. 1 to 4, the fuel supply pipes 43a, 43b, 43c, 43d are each detachably mounted in the burner 1 in such a way that each fuel supply pipe 43a, 43b, 43c, 43d which is formed in accordance with a predetermined fuel mixing configuration (position of the fuel supply pipe in the inlet passage, quantity and arrangement of the fuel output openings, cross-sectional shape of the fuel supply pipe) can be individually exchanged if necessary for a fuel supply pipe 43a, 43b, 43c, 43d based on another predetermined fuel mixing configuration.

To this end, the fuel supply pipes 43a, 43b, 43c, 43d (designated by 43a-d in FIG. 4) are removably inserted into corresponding apertures in the burner bottom 30 as is shown in FIG. 4; each fuel supply pipe 43a, 43b, 43c, 43d has at a longitudinal end thereof a flange portion or head portion 46, 47 which contacts the burner bottom 30 on the side thereof remote of the swirler 40 and, e.g., is screwed to the burner bottom 30 by means of screws (not shown).

Finally, it should be noted that each fuel supply pipe 43a, 43b, 43c, 43d is, of course, fluidically connected to a fuel source (not shown) such as, e.g., a combustible-gas tank, via lines and control valves (neither of which is shown).

Thus, while there have shown and described and pointed out fundamental novel features of the invention as applied to a preferred embodiment thereof, it will be understood that various omissions and substitutions and changes in the form and details of the devices illustrated, and in their operation, may be made by those skilled in the art without departing from the spirit of the invention. For example, it is expressly intended that all combinations of those elements and/or method steps which perform substantially the same function in substantially the same way to achieve the same results are within the scope of the invention. Moreover, it should be recognized that structures and/or elements and/or method steps shown and/or described in connection with any disclosed form or embodiment of the invention may be incorporated in any other disclosed or described or suggested form or embodiment as a general matter of design choice. It is the intention, therefore, to be limited only as indicated by the scope of the claims appended hereto.

Claims

1-7. (canceled)

11. A burner for a turbine comprising: a flame tube (10) defining a combustion space (11);a casing (20) enclosing said flame tube (10) from radially outward at a predetermined distance from said flame tube (10) and forming an oxidant collection chamber (21) between said flame tube (10) and said casing (20);a burner bottom (30) bounding said oxidant collection chamber (21) and said combustion space (11) at an axial end of said burner;a swirler (40) arranged axially between said flame tube (10) and said burner bottom (30) axially adjoining said burner bottom (30) and radially adjoining said oxidant collection chamber (21) for supplying a fuel-oxidant mixture into said combustion space (11), said swirler (40) comprising a plurality of guide vanes (41) arranged at a circumferential distance from one another along a circumferential direction (UR) of said burner so that the respective distances between said guide vanes (41) form a plurality of radial inlet passages (42) to said combustion space (11), said radial inlet passages having a tangential component along its path;a fuel supply pipe (43a, 43b, 43c, 43d) provided in a respective inlet flow region of at least some of said inlet passages (42), said fuel supply pipe (43a, 43b, 43c, 43d) having a length and extending lengthwise through said respective inlet passage (42) in an axial direction (AR) of said burner and traverse to an oxidant flow direction (OR), and wherein each fuel supply pipe (43a, 43b, 43c, 43d) comprises a wall having at least one fuel output opening (44, 45) radial to said fuel supply pipe (43a, 43b, 43c, 43d) for mixing fuel (BS) into said respective inlet passage (42) with a directional component extending transverse to the oxidant flow direction (OR).

12. The burner according to claim 11, wherein at least one of said fuel supply pipes (43a, 43b, 43d) is arranged in said respective inlet passage (42).

13. The burner according to claim 11, wherein at least one of said fuel supply pipes (43c) is arranged directly in front of said respective inlet passage (42) in the oxidant flow direction (OR).

14. The burner according to claim 11, wherein at least one of said fuel supply pipes (43a, 43b, 43c) is arranged centrally in said respective inlet passage (42) with respect to a center longitudinal axis (L) of said respective inlet passage (42).

15. The burner according to claim 11, wherein at least one of said fuel supply pipes (43d) is arranged off-center in said respective inlet passage (42) with respect to a center longitudinal axis (L) of said respective inlet passage (42).

16. The burner according to claim 11, wherein at least one of said fuel supply pipes (43a, 43b, 43c, 43d) comprises a plurality of fuel output openings (44, 45) arranged at a distance from one another along said length of said fuel supply pipe (43a, 43b, 43c, 43d).

17. The burner according to claim 11, wherein at least one of said fuel supply pipes (43a, 43b, 43c, 43d) comprises two fuel output openings (44, 45) arranged at the same position with respect to said length of said fuel supply pipe (43a, 43b, 43c, 43d) for delivering fuel (BS) from said fuel supply pipe (43a, 43b, 43c, 43d) via said two fuel output openings (44, 45) with two directional components opposed to one another.

18. The burner according to claim 17, wherein said at least one fuel supply pipe (43a, 43b, 43c, 43d) comprises a cross section and wherein, with respect to said cross section of said fuel supply pipe, said two fuel output openings (44, 45) are located diametrically opposite one another.

19. The burner according to claim 17, wherein said at least one fuel supply pipe (43a, 43b, 43c, 43d) comprises a cross section and said two fuel output openings each having a center longitudinal axis and wherein, with respect to said cross section of said fuel supply pipe, said respective center longitudinal axes (L1, L2) of said two fuel output openings (44, 45) enclose an obtuse angle (α) with one another.

20. The burner according to claim 11, wherein said fuel supply pipes (43a, 43b, 43c, 43d) each have one of a cylindrical cross section and an airfoil-shaped cross section.

21. The burner according to claim 11, wherein said fuel supply pipes (43a, 43b, 43c, 43d) are each detachably mounted so that each fuel supply pipe (43a, 43b, 43c, 43d) formed in accordance with a first predetermined fuel mixing configuration can be individually exchanged for a fuel supply pipe (43a, 43b, 43c, 43d) based on another predetermined fuel mixing configuration.

22. The burner according to claim 12, wherein at least one of said fuel supply pipes (43a, 43b, 43c) is arranged centrally in said respective inlet passage (42) with respect to a center longitudinal axis (L) of said respective inlet passage (42).

23. The burner according to claim 13, wherein at least one of said fuel supply pipes (43a, 43b, 43c) is arranged centrally in said respective inlet passage (42) with respect to a center longitudinal axis (L) of said respective inlet passage (42).

24. The burner according to claim 12, wherein at least one of said fuel supply pipes (43a, 43b, 43c, 43d) comprises a plurality of fuel output openings (44, 45) arranged at a distance from one another along said length of said fuel supply pipe (43a, 43b, 43c, 43d).

25. The burner according to claim 13, wherein at least one of said fuel supply pipes (43a, 43b, 43c, 43d) comprises a plurality of fuel output openings (44, 45) arranged at a distance from one another along said length of said fuel supply pipe (43a, 43b, 43c, 43d).

26. The burner according to claim 14, wherein at least one of said fuel supply pipes (43a, 43b, 43c, 43d) comprises a plurality of fuel output openings (44, 45) arranged at a distance from one another along said length of said fuel supply pipe (43a, 43b, 43c, 43d).

27. The burner according to claim 12, wherein at least one of said fuel supply pipes (43d) is arranged off-center in said respective inlet passage (42) with respect to a center longitudinal axis (L) of said respective inlet passage (42).

28. The burner according to claim 13, wherein at least one of said fuel supply pipes (43d) is arranged off-center in said respective inlet passage (42) with respect to a center longitudinal axis (L) of said respective inlet passage (42).

29. The burner according to claim 12, wherein at least one of said fuel supply pipes (43a, 43b, 43c, 43d) comprises two fuel output openings (44, 45) arranged at the same position with respect to said length of said fuel supply pipe (43a, 43b, 43c, 43d) for delivering fuel (BS) from said fuel supply pipe (43a, 43b, 43c, 43d) via said two fuel output openings (44, 45) with two directional components opposed to one another.

30. The burner according to claim 13, wherein at least one of said fuel supply pipes (43a, 43b, 43c, 43d) comprises two fuel output openings (44, 45) arranged at the same position with respect to said length of said fuel supply pipe (43a, 43b, 43c, 43d) for delivering fuel (BS) from said fuel supply pipe (43a, 43b, 43c, 43d) via said two fuel output openings (44, 45) with two directional components opposed to one another.