Patent Application
20170219210
The invention relates to a burner for a gas turbine, having at least one burner lance and/or burner hub, and at least one burner passage that at least portionally surrounds the burner lance and/or burner hub. The burner also comprises a fuel supply arrangement, having at least one fuel nozzle and at least one fuel channel.
The burner serves to introduce fuel into a combustion chamber of the gas turbine. The fuel may be introduced into the combustion chamber directly in the outlet region of the burner, in order to generate a diffusion flame, for example in that the fuel is introduced into the combustion chamber or injected into the air stream adjacently to an air stream flowing out of a burner passage of the burner. Alternatively or additionally, the burner may introduce premixed fuel into the combustion chamber, in that the fuel is injected into a burner passage realized as a premix passage (by means of fuel nozzles that lead into the premix passage), and mixed in the premix passage with an air stream flowing through the premix passage. After emerging from the burner, the fuel/air mixture emerging from the premix passage is burned in the combustion chamber, rendering possible combustion that is particularly low in pollutants. Such premix flames, however, have a tendency toward combustion instabilities, for which reason such burners comprise, for example, pilot burners or further fuel passages for the purpose of stabilization.
For the purpose of supplying the burner with a type of fuel, or generally a plurality of fuel types, the burner comprises a fuel supply system. The fuel supply system comprises a fuel supply arrangement, having at least one fuel channel, via which the fuel nozzles of the burner are supplied with fuel. The fuel nozzle may be, for example, a pressure-swirl nozzle. However, it may also be, for example, a burner passage outlet.
The burner of the generic type comprises at least one burner lance and/or one burner hub.
The burner lance may be, for example, a central lance of a pilot burner or cone burner having nozzles for diffusion operation. The burner lance may also be disposed centrally in a premix passage, or project into the latter from upstream. The burner lance may serve to guide the flow, or additionally comprise fuel nozzles that inject fuel into the premix passage. The nozzles of the burner lance may be supplied with fuel via at least one fuel channel of the fuel supply arrangement that extends in the burner lance. A fuel injector—for example in the form of a swirl generator comprising swirl blades—that is disposed around the lance may be disposed on the burner lance, which fuel injector likewise comprises fuel nozzles that lead into the premix passage. In this case, the fuel supply arrangement may extend along the burner lance, as far as the nozzles of the fuel injector.
The burner hub denotes a component that radially inwardly delimits a burner passage, and in which there extends/extend at least one fuel channel of the fuel supply arrangement that supplies fuel to fuel nozzles disposed on the hub, and/or supply channels, which extend as far as fuel nozzles disposed in the burner passage. The burner hub may be disposed between the burner passage and a fuel supply unit that is disposed radially further inward, such that the burner hub at least portionally surrounds the supply unit that is disposed radially further inward. In order to reduce pollutant emissions during operation of the burner, it is sought to mix the injected fuel as finely and homogeneously as possible with the air flowing past. For example, pressure-swirl nozzles are used for this purpose in the prior art.
The invention is based on the object of specifying a burner, of the type stated at the outset, and a gas turbine having at least one such burner, by means of which it is made possible to reduce emissions of pollutants, and by which improved operating reliability is additionally ensured.
The object is achieved, according to the invention, in the case of a burner of the type stated at the outset, in that the fuel supply arrangement comprises at least one fluidic oscillator that has an interaction chamber, wherein the interaction chamber has at least one inlet for the intake of fuel and, located opposite, an outlet region, having at least one outlet channel for the outlet of fuel, wherein one end of at least one feedback line leads into the interaction chamber, in the region of the inlet, and the other end thereof leads into the outlet region or into an outlet channel, wherein the two ends of the feedback line are each sealed off from the interaction chamber by a flexible membrane.
It is thus proposed, according to the invention, to integrate at least one fluidic oscillator into the fuel supply arrangement. In other words, at least one fuel nozzle is fluidically connected to an outlet channel of the fluidic oscillator, the inlet of the fluidic oscillator being fluidically connected to a fuel channel of the fuel supply arrangement. A fluctuation of the fuel supply of the fuel nozzle connected to the fluidic oscillator is thus effected, as a result of which stronger turbulences occur, between fuel emerging from the fuel nozzle and combustion air flowing past. This promotes better mixing. Emissions of pollutants are thereby reduced.
Fluidic oscillators have long been known as fluidic control elements that do not require expensive valves. For example, they are used to supply air into the boundary layer of airfoils, in order to avoid separation of the boundary layer.
Differing types of fluidic oscillator are known, which differ in their structure. Common to all of these types is that they have an interaction chamber that is entered, through an inlet, by a pressurized jet of fluid. The jet is applied periodically to differing side walls, or side-wall regions, of the interaction chamber, such that one may refer to an interaction of the jet with the side walls of the chamber, an oscillation of the jet being stimulated, such that the jet flows through the chamber periodically on differing paths and consequently, in the outlet region, leaves the interaction chamber periodically by differing outlets, or leaves a central outlet of the interaction chamber periodically in differing directions. The jet is thus periodically applied to, and comes away from, at least two opposing side-wall regions, this being caused by delaying of the flow.
The periodic application of the jet to the side walls/side-wall regions may additionally be stabilized, in that the pressure of the outlet respectively receiving the jet is fed back to the inlet region by means of comparatively thin feedback lines, such that the jet obtains an impulse that presses it away from the side wall/side-wall region to which it is just then being applied. However, the feedback is not absolutely necessary for the oscillation of the jet.
The functioning of fluidic oscillators is of the prior art, such that the fluidic oscillators are explained only briefly here.
In the case of the present invention, it is proposed, according to the invention, to integrate at least one fluidic oscillator into a fuel supply arrangement of a burner for a gas turbine, such that, during operation, the at least one fuel nozzle outputs a pulsed jet of fuel, as a result of the outlet channel receiving fuel in a periodic manner. If the fluidic oscillator comprises a plurality of outlet channels (to which at least one fuel nozzle is connected downstream), the output of the fuel of the at least two fuel nozzles is effected with a time offset relative to each other. The frequency may be set by the geometry of the fluidic oscillator, in particular by the size of the chamber.
The fuel nozzle connected to the outlet channel may be realized by the outlet channel itself, for example in that the outlet channel is realized as a full-jet nozzle.
The fluidic oscillator according to the invention is particularly suited to receiving fuel. For this purpose, the two ends of the at least one feedback line are each sealed off against the interaction chamber by a flexible membrane.
As already described further above, the feedback line serves to stabilize the oscillation, and functions by feeding a pressure in the outlet region back to the inlet region. In the prior art, these feedback lines are open toward the interaction chamber, such that a portion of the fluid flowing through the chamber fills the feedback line and is moved back and forth in the latter. The flexible membranes serve to transfer the pressure, without the fuel being able to enter the feedback line. According to the invention, the function of transferring the pressure is assumed by the air enclosed, between the membranes, in the feedback line, or by a specially filled fluid or gel.
As a result, there is no region that forms in the feedback line in which fuel remains over a prolonged period and, in the case of oil as a fuel, becomes carbonized, which would cause choking of the feedback lines. This increases the operational reliability of the burner realized according to the invention.
The flexible membrane is composed of a material that is resistant to the fuel. The membrane may be fastened in the end region of the feedback line, in the latter. However, it could also be fastened, for example, in the region of the mouth of the feedback line, on the inside of the interaction chamber, and in this case cover the mouth of the feedback line. Insofar as the feedback line leads into the outlet channel, the membrane could be fastened, analogously, to the inside of the outlet channel, and in this case cover the mouth of the feedback line.
Advantageous designs of the invention are specified in the following description and the dependent claims, the features of which may be applied individually and in any combination with one another.
It may be provided, advantageously, that the membrane is composed of a temperature-resistant high-grade steel or of a nickel-based material.
This material is flexible, withstands the temperatures in the region of the fuel lines of gas turbine burners, and is corrosion-resistant with respect to fuel. The nickel-based material may also be referred to as a material based on nickel.
Advantageously, it may further be provided that the feedback line is filled with a fluid or gel for the purpose of transmitting a pressure.
The fluid may be an inert gas that, in the case of a failure of the membrane, behaves in a non-problematic manner when in contact with fuel. The gel may be, for example, an aerogel that is particularly resistant to heat.
It may also be considered to be advantageous that at least one outlet channel of the interaction chamber is realized as a fuel nozzle in the form of a full-jet nozzle.
This design has a simple structure and reduces the production costs.
Advantageously, for the purpose of stimulating the oscillation, the interaction chamber comprises at least two oppositely disposed side-wall regions, which diverge from each other in the manner of a diffusor, at least in the inlet region of the interaction chamber, in the direction of the outlet region.
The design of the invention relates to a fluidic oscillator that, owing to the wall regions diverging in the direction of the outlet, at least in the inlet region, stimulates an incoming jet to oscillates. Within the scope of this application, the term side-wall region may also be referred to as a side wall.
In the case of the walls diverging in the manner of a diffusor in the inlet region, the jet entering under pressure is automatically applied periodically to differing side walls, and comes back away from the latter. The opening angle of the walls is suitably selected in this case. It may be selected, for example, so as to be greater than 7.5 degrees. Suitable opening angles are known from the prior art.
The chamber may be realized, for example, in the form of a cone, having the outlets in the base area. The side walls/side-wall regions may extend, for example, in a curved course from the inlet region to the opposite outlet region, and the chamber may be round in cross-section. In this case, it is essential only that, owing to the side walls in the inlet region diverging in the direction of the outlet, the jet is stimulated to effect an oscillation in which it exits the chamber in a periodically alternating manner through differing outlets.
An advantageous design of the invention may provide that the two side-wall regions diverge in such a manner that at least an angle of 7.5 degrees is realized between an inflow direction and the side-wall region.
It may also be considered as advantageous that the two opposing side-wall regions extend in a curved shape from the inlet region to the outlet region.
Further, it may be provided, advantageously, that the interaction chamber is realized so as to be substantially rotationally symmetrical, and the rotation axis goes through the inlet and the opposite outlet region, wherein the interaction chamber widens in the manner of a diffusor, at least in the inlet region, in the direction of the outlet.
The inlet in this case is disposed on one side of the chamber, and the outlet region on the opposite side of the interaction chamber.
It is a further object of the invention to specify a combustion chamber having at least one burner, and a gas turbine having at least one such combustion chamber, by means of which it is made possible to reduce emissions of pollutants during operation, and by which improved operating reliability is additionally ensured.
For this purpose, the combustion chamber comprises at least one burner realized as claimed, and the gas turbine comprises at least one combustion chamber as claimed.
The combustion chamber may be, for example, an annular combustion chamber, disposed at the top end of which there are one or more full-perimeter rows of burners. At least one of the burners may be realized as claimed. The combustion chamber may also be realized, for example, as a pipe combustion chamber or silo combustion chamber. At its top end, the combustion chamber may comprise a burner arrangement that has main burners disposed in the form of a circle. There may be one or more circles of disposed main burners. There may be a central pilot burner disposed in the middle. Each burner, or only one burner, or individual burners may be realized as claimed.
The gas turbine may be a turbomachine having a plurality of combustion chambers—for example annular combustion chambers—the combustion chambers being disposed in succession in the direction of flow. The gas turbine may also comprise a circular arrangement of combustion chambers—for example pipe combustion chambers—the outlets of which are disposed in a ring-segment form on a common annular turbine inlet.
The invention also relates to a fluidic oscillator having an interaction chamber, wherein the interaction chamber has at least one inlet for the intake of a fluid and, located opposite, an outlet region, having at least one outlet channel for the outlet of the fluid, wherein, for the purpose of stabilizing an oscillation of the fluid jet that can be stimulated by the interaction chamber, one end of at least one feedback line leads into the interaction chamber, in the region of the inlet, and the other end thereof leads into the outlet region or into an outlet channel.
It is a further object of the invention to specify a fluidic oscillator of the above-mentioned type that is particularly suitable for operation with fuel.
For this purpose, the ends of the feedback line are each sealed off from the interaction chamber by a flexible membrane.
In the prior art, these feedback lines are open toward the interaction chamber, such that a portion of the fluid flowing through the chamber fills the feedback line and is moved back and forth in the latter.
The flexible membranes serve to transfer the pressure, without the fuel being able to enter the feedback line. According to the invention, the function of transferring the pressure is assumed by the air enclosed, between the membranes, in the feedback line, or by a specially filled fluid or gel.
As a result, there is no regions that form in the feedback line in which fuel remains over a prolonged period and, in the case of oil as a fuel, becomes carbonized, which would cause choking of the feedback lines. Consequently, the fluidic oscillator according to the invention is suitable for integration into a fuel supply arrangement, whereby it increases the operational reliability of the burner.
The flexible membrane is composed of a material that is resistant to fuel. The membrane may be fastened in the end region of the feedback line, in the latter. However, it could also be fastened, for example, in the region of the mouth of the feedback line, on the inside of the interaction chamber, and in this case cover the mouth of the feedback line. Insofar as the feedback line leads into the outlet channel, the membrane could be fastened, analogously, to the inside of the outlet channel, and in this case cover the mouth of the feedback line.
It may also be provided advantageously, that the membrane is composed of a temperature-resistant high-grade steel or of a nickel-based material.
It may also be considered as advantageous that the feedback line is filled with a fluid or gel for the purpose of transmitting a pressure.
An advantageous design of the invention may provide that, for the purpose of stimulating the oscillation, the interaction chamber comprises at least two oppositely disposed side-wall regions, which diverge from each other in the manner of a diffusor, at least in the inlet region of the interaction chamber, in the direction of the outlet region.
At least one outlet channel of the fluidic oscillator may be realized as a fuel nozzle in the form of a full-jet nozzle.
Further expedient designs and advantages are provided by the description of exemplary embodiments of the invention, with reference to the figure of the drawing, wherein components that have the same function are denoted by the same references.
There are shown in
The combustion system 9 represented in
During operation of the gas turbine, air is sucked in through the intake housing 6 and compressed by the compressor 8. The compressor air L″ provided at the turbine-side end of the compressor 8 is guided along a burner plenum 7 to the combustion system 9 where, in the region of the burner arrangement, it is routed into the burners 11 and in the latter is mixed with fuel and/or enriched with fuel in the outlet region of the burner 11. Fuel supply systems in this case supply the burners with fuel. The mixture, or the compressor air and the fuel, is/are discharged from the burners 11 into the combustion chamber 11 and combusts/combust, forming a hot stream of working gas in a combustion zone within the combustion chamber housing 12 of the combustion chamber. From there, the stream of working gas flows along the hot-gas channel, past the guide blades 17 and the rotor blades 18. At the rotor blades 18, the stream of working gas expands in an impulse-transmitting manner, such that the rotor blades 18 drive the rotor 3, and the latter drives the generator (not represented) coupled thereto.
The oscillator 24a comprises an interaction chamber 26, having precisely one inlet 28 that has an inlet region 30, and having an oppositely disposed outlet region 32 that has a first outlet channel 34 and a second outlet channel 36. Disposed for each outlet channel there is a relatively thin feedback line 38 that connects the inlet region to the outlet region, one end of the feedback line leading into the outlet channel in the example represented. The side-wall regions 40 diverge in the direction of the outlet region 32, such that the interaction chamber 26 is triangular in longitudinal section. The oscillator 24a is not of a rotationally symmetrical structure, but is of a constant longitudinal section perpendicularly in relation to the plane of the drawing.
Shown schematically in
Shown schematically in
Shown schematically in
Shown schematically in
A jet of fuel under pressure entering the interaction chamber 26 in the inflow direction 29 advantageously is applied to the side walls 27, an oscillation of the jet being stimulated because of the divergence of the side-wall regions 27 in the inlet region 30, such that the jet is periodically applied to differing side-wall regions and periodically applies fuel to the two outlet channels 34 and 36. The feedback lines 38a, 38b feed a pressure in the outlet region 32 back to the inlet region 30, and thereby stabilize the oscillation. In order that no fuel gets into the feedback lines, the feedback lines are sealed at their ends by the flexible membranes 37, which transmit a pressure to a fluid 35 or gel, which may be, for example, air or an inert gas, enclosed in each feedback line. When, during the oscillation, fuel is applied to the outlet channel 34, the membrane 37 of the feedback channel 38a that is disposed in the outlet region is pressed into the line 38a, as represented, such that the membrane 37 at the other end of the feedback line 38a, in the inlet region 30, is pressed out. At this time, substantially no pressure is applied to the two membranes 37 that seal off the opposite feedback line 38b. Owing to the membrane 37, the fluidic oscillator 25 is suitable for having a through-flow of fuel and for stimulating oscillation of the fuel jet, a safety risk, from standing fuel in the feedback lines, being reliably avoided.
A burner 84 according to the invention, according to a second exemplary embodiment of the invention, is shown schematically in
The pressure prevailing at the end of the outlet channel is fed back to the inlet region 30 of the interaction chamber by the feedback lines 38a, 38b. The membranes 37 seal off the feedback lines against the fuel, a pressure loading the membranes being transmitted from one end to the other end of the feedback line by means of a fluid or gel enclosed in the feedback line.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10 2014 218 285.9 | Sep 2014 | DE | national |
This application is the US National Stage of International Application No. PCT/EP2015/070463 filed Sep. 8, 2015, and claims the benefit thereof. The International Application claims the benefit of German Application No. DE 102014218285.9 filed Sep. 12, 2014. All of the applications are incorporated by reference herein in their entirety.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/EP2015/070463 | 9/8/2015 | WO | 00 |
