SWIRLER FOR A BURNER OF A GAS TURBINE ENGINE
A fuel injection structure for a swirler of a burner of a gas turbine engine, wherein the swirler includes a plurality of vanes and a plurality of mixing channels between the vanes to channel air from a radially outer end of the mixing channel to a radially inner end of the mixing channel, of the fuel injection structure which includes at least two injection ports to inject fuel into the channeled air. A swirler for a burner of a gas turbine engine, and a burner of a gas turbine engine and a gas turbine engine includes the fuel injection structure.
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This application is the US National Stage of International Application No. PCT/EP2015/051612 filed Jan. 27, 2015, and claims the benefit thereof. The International Application claims the benefit of European Application No. EP14154756 filed Feb. 11, 2014. All of the applications are incorporated by reference herein in their entirety.
FIELD OF INVENTIONThe present invention is related to a fuel injection means for a swirler of a burner of a gas turbine engine, the swirler comprising a plurality of vanes and a plurality of mixing channels between the vanes to channel air from a radially outer end of the mixing channel to a radially inner end of the mixing channel, the fuel injection means comprising at least two injection ports to inject fuel into the channelled air. Further, the invention is related to a swirler for a burner of a gas turbine engine, comprising fuel injection means, a plurality of vanes and plurality of mixing channels between the vanes to channel air from a radially outer end of the mixing channel to a radially inner end of the mixing channel, the fuel injection means comprising at least two injection ports to inject fuel into the channelled air, further to a burner of a gas turbine engine, comprising a swirler and a combustion chamber and further to a gas turbine engine, comprising at least one burner.
BACKGROUND OF INVENTIONModern gas turbine engines are commonly used in industrial applications. Such gas turbine engines can comprise a pilot burner with a pilot burner fuel delivery arrangement described in U.S. 2003/106320 A1. To achieve the goal of an environmental-friendly operation of the gas turbine engine, the gas turbine engine is operated in a DLE-combustion mode (DLE: Dry Low Emission) producing low emissions, especially low NOx-emissions. To achieve this goal, a good and uniform mixing of air and fuel in a burner of the gas turbine engine has to be achieved. In modern gas turbine engines swirlers are used for this task. Such a swirler arrangement is for instance described in U.S. Pat. No. 5,983,642 A1.
In operation of the gas turbine engine 10, air 24, which is taken in through the air inlet 12, is compressed by the compressor section 14 and delivered to the combustion or burner section 16. The burner section 16 comprises an array of combustors each having a combustor axis 17 and arranged thereabout a burner plenum 26, one or more combustion chambers 28, defined by a double wall can 27 and at least one burner 30 fixed to each combustion chamber 28. The combustion chambers 28 and the burners 30 are located inside the burner plenum 26. The compressed air 24 passing through the compressor 14 and the diffuser 32 is discharged from the diffuser 32 into the burner plenum 26 from where a portion of the air enters the burner 30 and is mixed with a gaseous or liquid fuel. The air/fuel-mixture is then burned and the combustion gas 34 or working gas from the combustion is channelled via a transition duct 35 to the turbine section 18.
The turbine section 18 comprises a number of blade-carrying discs 36 attached to the shaft 22. In the present example, two discs 36 each carry an annular array of turbine blades 38. However, the number of blade-carrying discs 36 could be different, i.e. only one disc or more than two discs. In addition, guiding vanes 40 which are fixed to a stator 42 of the gas turbine engine 10, are disposed between the turbine blades 38. Between the exit of the combustion chamber 28 and the leading turbine blades 38 inlet guiding vanes 44 are provided.
The combustion gas 34 from the combustion chamber 28 enters the turbine section 18 and drives the turbine blades 38 which in turn rotate the shaft 22. The guiding vanes 40, 44 serve to optimize the angle of the combustion or working gas on the turbine blades 38. The compressor section 14 comprises an actual series of guide vane stages 46 and rotor blade stages 48.
As mentioned above, variations in air/fuel distributions in the burner have a negative influence on the temperature distributions and the uniformity of the flame in this specific burner. Gas turbine engines in general are normally optimized for full load operation. Especially the mixing of fuel and air in a swirler of a burner of the gas turbine engine is crucial to achieve a high efficiency during the operation of the gas turbine engine. Therefore the parts, especially the fuel injection means, are designed such to achieve an optimum mixing of fuel and air for a full load operation of the gas turbine engine.
Therefore, during part load operations of the gas turbine engine, poor mixing of fuel and air can occur. The reliability of the gas turbine engine may be affected by such poor mixing of fuel and air. In addition, due to poor mixing, a good portion of liquid fuel cannot atomize and therefore liquid ligaments often attach and/or are deposited to the internal surface of the components and form a carbon buildup. When running the gas turbine engine at a part load or at a low load, the engine may suffer from disadvantages such as obstruction of fuel injection ports by carbon build-up, poor ignition caused by obstructed igniter ports and/or pre-chamber covering with carbon build-up which may result in long-term damage of the gas turbine engine.
It is known to enhance the reliability of gas turbine engines operated at part loads by bleeding compressed air from the engine and thus increasing the flame temperature. This leads to a burn-off of a portion of the carbon build-up. However, this method is highly inefficient and is especially non-applicable for very low loads. To address such low loads, for instance loads smaller than 40% of the maximum load, it is known to change the fuel injection means of the gas turbine engine. This procedure is both expensive and increases the downtime of the gas turbine engine.
SUMMARY OF INVENTIONIt is an object of the present invention to solve the aforesaid problems and drawbacks at least partly. In particular, it is an object of the present invention to provide fuel injection means, a swirler, a burner and a gas turbine engine, which allow an operation of the gas turbine engine at different load levels and improve the efficiency, especially at low loads, in an easy and cost efficient way.
The aforesaid problems are solved by fuel injection means for a swirler of a burner of a gas turbine engine, by a swirler for a burner of a gas turbine engine, by a burner of a gas turbine engine and a gas turbine engine according to the claims. Further features and details of the present invention result from the subclaims, the description and the drawings. Features and details discussed with respect to the fuel injection means can also be applied to the swirler, the burner and the gas turbine engine and vice versa, if of technical sense.
According to a first aspect of the invention the aforesaid object is achieved by a fuel injection means for a swirler of a burner of a gas turbine engine, the swirler comprising a plurality of vanes and a plurality of mixing channels between the vanes to channel air from a radially outer end of the mixing channel to a radially inner end of the mixing channel, the fuel injection means comprising at least two injection ports to inject fuel into the channelled air. The fuel injection means according to the invention is characterized in that the fuel injection means is enabled to change the number of injection ports used for the fuel injection. The swirler described in the preamble is used in a burner of a gas turbine engine to produce an air/fuel mixture. This air/fuel mixture is afterwards burned in a combustion chamber of the burner. The fuel injection means used to inject fuel into the channelled air in the mixing channel comprises at least two injection ports. These injections ports are distributed along the fuel injection means and may differ in size. By providing more than one injection port it is possible to achieve a more uniform distribution of the air/fuel mixture. According to the invention the fuel injection means is enabled to change the number of injection ports used for the fuel injection. Therefore it is possible, to use many, especially all, injection ports for an operation of the gas turbine engine at full load. For an operation of the gas turbine engine at a part load only a few, even down to one, injection ports can be used. This feature allows to provide fuel by a fuel injection means at such a high pressure that a good atomization of the fuel into the air can always be secured. By changing the number of injection ports used for the fuel injection according to the load level of the operation of the gas turbine engine for each of these load levels a good atomization of the fuel into the air and therefore a good fuel air mixing can be achieved. A highly efficient operation of the gas turbine engines independent of the current load level can be achieved. Due to the good air/fuel mixing, an efficient burning of the fuel in the burner of the gas turbine engine can be secured and therefore a carbon build-up in the swirler, especially at the fuel injection ports or at an igniter can be prohibited. It is possible to use an electric motor or a hydraulic system to achieve the change of the number of used injection ports.
Further, fuel injection means according to the invention can be characterized in that the fuel injection means comprises a spring loaded mechanism to change the number of injection ports used for the fuel injection. Such a spring loaded mechanism is especially a mechanical easy way to change the number of used injection ports. Preferably no other driving means are necessary and/or used to change the number of used injection ports. Especially no external engine such as an electric motor or a hydraulic system is necessary to achieve the change of the number of used injection ports.
In a further advanced arrangement of a fuel injection means according to the invention, the spring loaded mechanism is enabled to be driven by the pressure of the fuel to be injected. Especially, the force of the spring loaded mechanism can be directed against the pressure of the fuel. During the operation of the gas turbine engine, if the load level should be increased, more fuel is needed to achieve this high load operation of the gas turbine engine. This leads to an enlargement of the pressure in the fuel system of the gas turbine engine. Therefore, this higher pressure in the fuel system can be used to drive the spring loaded mechanism. A higher pressure of the fuel in the fuel system of the gas turbine engine results in a higher force of the fuel against a spring of the spring loaded mechanism.
Therefore, a spring loaded mechanism enabled to be driven by the pressure of the fuel to be injected is a very easy way to control such a spring loaded mechanism.
In addition, a fuel injection means according to the invention can be characterized in that at least two injection ports share a common feeding pipe wherein a spring loaded mechanism comprises a piston arranged in the common feeding pipe. Such a feeding pipe can be used to feed the fuel to the several injection ports. In particular the injection ports are arranged at the feeding pipe, especially in a linear way. The piston is arranged inside the feeding pipe and separates the fuel in the feeding pipe from a spring of the spring loaded mechanism. For an operation at higher load more fuel is needed to be burned in the burner of the gas turbine engine. Therefore, in the fuel system of the gas turbine engine higher pressure is present. Through the force of the fuel at this higher pressure the piston is driven back inside the feeding pipe and consequently more injection ports are opened for injecting fuel into the air. By doing so, the number of used injection ports is automatically adapted to the load level of the operation of the gas turbine engine.
Further, fuel injection means according to the invention can be characterized in that the fuel injection means are enabled to be arranged at a trailing edge of one of the vanes of the swirler. The trailing edges of the vanes of the swirler are positioned at the end of the respective mixing channel.
Therefore, the injection of the fuel into the channelled air is carried out at the end of the mixing channels and at the beginning of the burner plenum. A very good mixture can be achieved and especially the positioning of fuel at the boundaries of the mixing channel can be prohibited.
According to another development of the invention a fuel injection means can be characterized in that the fuel injection means are constructed as a fuel injection lance. Such a fuel injection lance can be positioned inside the mixing channel. The positioning of the fuel injection lance inside the mixing channel can be done at the radially outer end of the mixing channel, at the radially inner end of the mixing channel or in between. Therefore it is possible, to choose the position of the fuel injection lance inside the mixing channel to meet the demands of the gas turbine engine to be used in.
Further, fuel injection means according to the invention can be characterized in that the injection ports are arranged in a counter-flow or a co-flow or a vertical spiral direction in respect to a direction of the channelled air. These different arrangements of the injection ports at the fuel injection means also allows an adaptation to specification and demands of the gas turbine engines to be used in. An especially highly efficient operation of the gas turbine engine can therefore be achieved.
According to a second aspect of the invention, the object is solved by a swirler for a burner of a gas turbine engine, comprising fuel injection means, a plurality of vanes and a plurality of mixing channels between the vanes to channel air from a radially outer end of the mixing channel to a radially inner end of the mixing channel, the fuel injection means comprising at least two injection ports to inject fuel into the channelled air. A swirler according to the invention is characterized in that the fuel injection means is constructed according to the first aspect of the invention. The use of such a fuel injection means provides the same advantages, which have been discussed in detail according to the fuel injection means according to the first aspect of the invention.
Further, according to a third aspect of the invention, the object is solved by a burner of a gas turbine engine, comprising a swirler and a combustion chamber. A burner according to the invention is characterized in that the swirler is constructed according to the second aspect of the invention. The use of such a swirler provides the same advantages which have been discussed in detail according to a swirler according to the second aspect of the invention.
In addition, according to a forth aspect of the invention, the object is solved by a gas turbine engine, comprising at least one burner. A gas turbine engine according to the invention is characterized in that the burner is constructed according to the third aspect of the invention. The use of such a burner provides the same advantages, which have been discussed in detail according to a burner according to the third aspect of the invention.
The present invention is described with respect to the accompanied figures. The figures show schematically:
Elements having the same functions and mode of action are provided in
In
Therefore, an obstruction of the fuel injection port 62 by carbon build-up cannot be prohibited. Other disadvantages such as poor ignition caused by obstructed igniter ports and/or prechamber covering with carbon build-up which can result in long-term damage of the gas turbine engine can also occur.
In
In summary the
The fuel injection means 50 can vary the height above a base 57 of the mixing channel 56 or the axial extent 59 of the fuel injection 64 from the fuel injection ports 62. In
In the above exemplary embodiment the spring loaded mechanism 68 has a generally linear bias such that the fuel pressure and position of the piston 72 in the common feeding pipe 70 have a linear relationship. In an adaptation of the swirler, the spring loaded mechanism 68 has a non-linear bias and an increase in fuel pressure has an increasing bias the further the spring loaded mechanism 68 is compressed or forced away from the base 57. At part load operation a relatively small change in fuel pressure causes a relatively large movement of the piston at part load operation. This is particularly advantageous at part load operation where small variations in pressure usually occur and the effect of fuel mixing is important on combustion performance of the system. For example and referring to
The non-linear bias or stiffness of the spring mechanism 68 may be achieved in a number of ways. One way is to have a spring with a helix having a variable tightness. Another way is to have a spring with a varying thickness and therefore stiffness of the wire the helix is formed from. Another way is to have a second spring or further springs extending part of the length of the main spring 68. Although a helical spring is shown in the figures, other spring or resilient means may be utilised which could be mechanical or field derived. The term spring mechanism is not intended to be restricted to helical wire springs.
As can be seen in
Referring to
In the exemplary embodiment described above, the injection ports 62A-C have similar outlet areas and therefore issue approximately the same amount of fuel when they are all fully exposed. However, in other examples the outlet areas may be different such that different quantities of fuel are issue from one or all the injection ports 62A-C. This can be beneficial to tailor the delivery of fuel into the different areas 64 of heights above the base 57 for different load demands while assuring good fuel atomisation. For example, the first injection port 62A may have a smaller area than second and third injection ports 62B, 62C. Thus at low load where approximately 10%-20% power is demanded good fuel atomisation occurs and the injection port 62A is sized for the respective fuel pressure to deliver an optimised fuel/air mixture. At medium loads between about 20%-60% power the fuel pressure is sufficient to urge the piston 72 to expose the second injection port 62B where its larger outlet area gives the combination of the first and second outlet areas a wider range of operability. At higher loads between 60%-100% power the fuel pressure is sufficient to urge the piston 72 to expose the third injection port 62C where its outlet area, larger that the first injection port 62A, gives the combination of the first, second and third outlets a wider range of operability.
It should be appreciated that the common feeding pipe 70 and the spring loaded mechanism 68 could be arranged the opposite way to that shown in
It should also be appreciated that any of the embodiments described above can be combined with any of the other embodiments in order to tailor the variable fuel injection to optimise any one or more of the advantages described.
Claims
1. A swirler for a burner of a gas turbine engine, comprising:
- a fuel injector,
- a plurality of vanes, and
- a plurality of mixing channels between the vanes to channel air from a radially outer end of the mixing channel to a radially inner end of the mixing channel,
- the fuel injector comprising at least two injection ports to inject fuel into the channelled air,
- wherein the fuel injector is enabled to change the number of injection ports used for the fuel injection.
2. The swirler according to claim 1,
- wherein the fuel injector comprises a spring loaded mechanism to change the number of injection ports used for the fuel injection.
3. The swirler according to claim 2,
- wherein the spring loaded mechanism is enabled to be driven by the pressure of the fuel to be injected.
4. The swirler according to claim 2,
- wherein the at least two injection ports share a common feeding pipe and wherein spring loaded mechanism comprises a piston arranged in the common feeding pipe.
5. The swirler according to claim 2,
- wherein the spring loaded mechanism has a non-linear bias.
6. The swirler according claim 1,
- wherein the fuel injector are enabled to be arranged at a trailing edge of one of the vanes of the swirler.
7. The swirler according to claim 1,
- wherein the fuel injector are constructed as a fuel injection lance.
8. The swirler according to claim 1,
- wherein the injection ports are arranged in a counter-flow or a co-flow or a vertical spiral direction in respect to a direction of the channelled air.
9. The swirler as claimed in claim 1,
- wherein the fuel injector varies an axial extent over which fuel can be injected into the channelled air.
10. The swirler as claimed in claim 1,
- wherein the fuel injector comprises the at least two injection ports located at axially spaced apart locations.
11. The swirler as claimed in claim 10,
- wherein the at least two injection ports are located along an axial line.
12. The swirler ) as claimed in claim 1,
- wherein there are at least three injection ports and the injection ports are unequally spaced.
13. The swirler as claimed in claim 1,
- wherein the at least two injection ports have different outlet areas.
14. The swirler as claimed in claim 11,
- wherein the mixing channel has a base and the injection port further away from the base has a greater outlet area.
15. A burner of a gas turbine engine, comprising
- a swirler and a combustion chamber,
- wherein the swirler is constructed according to claim 1.
16. A gas turbine engine, comprising
- at least one burner,
- wherein the burner is constructed according to claim 14.
Type: Application
Filed: Jan 27, 2015
Publication Date: Dec 1, 2016
Applicant: Siemens Aktiengesellschaft (Munich)
Inventor: Ghenadie Bulat (Lincoln)
Application Number: 15/116,590