WO2008155373A1

WO2008155373A1 - Non-rotational stabilization of the flame of a premixing burner

Info

Publication number: WO2008155373A1
Application number: PCT/EP2008/057757
Authority: WO
Inventors: Mariano Cano Wolff; Patrick Ronald Flohr; Matthias Hase; Martin Lenze; Jürgen MEISL; Paul Pixner; Uwe Remlinger; Kai-Uwe Schildmacher; Thomas Alexis Schneider; Jaap Van Kampen
Original assignee: Siemens Aktiengesellschaft
Priority date: 2007-06-21
Filing date: 2008-06-19
Publication date: 2008-12-24
Also published as: EP2156095A1; EP2006606A1; US20100192583A1; EP2156095B1

Abstract

The invention relates to a method for stabilizing the flame of a premixing burner (1), comprising a reaction chamber (5) containing a fluid. The method is characterized in that an air-fuel mixture is injected into the reaction chamber (5) at a speed that is different from that of the fluid present in the reaction chamber (5), the speed being adjusted such that vortices (10) form at the boundary (11) forming between the air-fuel mixture and the surrounding fluid. The invention further relates to a premixing burner (1) comprising a reaction chamber (5) and at least one premixing spray nozzle (6) opening into the reaction chamber (5). The premixing burner (1) is characterized in that an air-fuel mixture can be injected into the reaction chamber (1) at a speed that is different from that of the surrounding fluid, the speed being adjusted such that vortices (10) form at the boundary (11) between the air-fuel mixture and the surrounding fluid.

Description

description

Spin-free stabilization of the flame of a premix burner

The present invention relates to a method for stabilizing the flame of a premix burner.

Combustion of fuel or an air-fuel mixture in combustors of gas turbines can cause combustion oscillations. These are characterized by greatly increased pressure amplitudes at different frequencies. Combustion vibrations can occur in the combustion chamber itself, but also in the adjacent components of the gas turbine and can be measured there. In general, combustion oscillations are undesirable because they adversely affect the combustion and can damage the entire combustion system. Combustion vibrations occur primarily in premix combustion systems, that is, in systems where the fuel is mixed with air prior to ignition. They occur preferably when the flame is limited to a relatively small location, so the reaction density is very high. Such a compact flame with a small local extent are associated with so-called delay times. If the delay times are within a certain narrow range, interactions with the acoustics of the combustion chamber may occur. This combustion oscillations can occur.

A system or method whereby combustion oscillations are completely avoided is not yet known. However, there are a variety of premix combustion systems in which an air-fuel mixture is twisted and the flame is stabilized by recirculation zones. In these systems, fuel is injected into an air stream and both are twisted, for example with the help of so-called swirl blades. After a certain distance traveled by this mixture, it burns downstream of the burner in a flame front, which is spatially stabilized by the flow field. However, all of these systems are characterized by the fact that there is a distinct and spatially limited flame. Therefore, combustion oscillations or flame instabilities inevitably occur at certain operating points. These can lead to extreme mechanical loads on the combustion chamber structure and should therefore be avoided or at least reduced.

An additional, common way to stabilize the flame is the use of pilot flames. This is particularly important in a partial load operation of a gas turbine.

It is the object of the present invention to provide an advantageous method for stabilizing the flame of a premix burner. Another object of the present invention is to provide an advantageous premix burner.

These objects are achieved by a method for stabilizing the flame of a premix burner according to claim 1 and a premix burner according to claim 9. The dependent claims contain further, advantageous embodiments of the invention.

The method according to the invention for stabilizing the flame of a premix burner comprising a reaction space containing a fluid, such as the combustion gases, is characterized in that an air-fuel mixture is injected into the reaction space at a rate different from that in the reaction space differs located fluid. The velocity is set such that vortices form at the forming interface between the fuel or air-fuel mixture and the fluid surrounding it. The eddies that form can be characterized in particular in that the axes of the vertebrae are perpendicular to the propagation direction of the air-fuel mixture. This distinguishes them from the vortexes that arise in the premix combustion systems already mentioned, in which an air-fuel mixture is twisted. The axes of the vortex, which primarily arise as a result of the twisting of the air-fuel mixture, lie parallel to the propagation direction of the air-fuel mixture. In addition, as a result of the twisting, recirculation vortices also form whose axes are perpendicular to the propagation direction of the air-fuel mixture. However, the vortices arising in connection with the present invention are characterized, in contrast to the eddies resulting from a twist, in that no vortices with axes parallel to the propagation direction of the air-fuel mixture occur.

An advantage of the present invention is that a complex twisting of the air-fuel mixture is not required, but nevertheless a mixing of air and fuel by turbulence is achieved. The recirculation also causes mixing of the air-fuel mixture with the hot combustion gas produced during combustion. This stabilizes the burner since it achieves continuous ignition.

It can be injected for flame stabilization fuel or an air-fuel mixture as a pilot fuel in the reaction space. The pilot fuel can be injected parallel or anti-parallel offset to the air-fuel mixture in the reaction space. When the pilot fuel is injected into the reaction space in anti-parallel offset from the air-fuel mixture, the hot gases of the pilot flame are thus made available to the premix jets for the hot gas intake. This reliably stabilizes the combustion reaction of the jets. In addition, since the exit of the hot gases from the combustion chamber against the Vorischstrahlrichtung takes place, is virtually all the hot gas for the ignition and the stabilization of Vormischstrahlen available.

The air-fuel mixture may preferably be formed by, in a premix jet nozzle, injecting the fuel into an oxidant at a rate higher than that of the oxidant. In particular, the fuel can be parallel to

Flow direction of the oxidant are injected into this. As the oxidizing agent, in particular air, i. the atmospheric oxygen, serve.

Furthermore, the side of the reaction space at which the pilot burner is located can be cooled with an oxidizing agent, which is then fed to the pilot fuel when injected into the reaction space. The oxidizing agent may be, for example, air.

For such a cooling of the heavily heat-stressed points on the combustion chamber side, where the pilot burner is located, a high pressure difference is available due to the large pressure loss in the premix jet nozzles. This allows the use of various cooling technologies, such as impingement jet cooling, impingement jet cooling with surface enlargement or ribbed cooling. For impact jet cooling with surface enlargement, for example, dimples, longitudinal and transverse ribs are considered. In this way, an open combustion chamber cooling is not required.

The inventive method, in particular the just described principle of anti-parallel injection of

Pilot fuel and air-fuel mixture, is applicable to both tube combustion systems and annular combustion chamber systems. It may be in the used Pilot burner to a swirl-stabilized burner or act a jet burner.

The antiparallel injection is particularly advantageous when annularly arranged jet burners are used as the main burner. In a stabilization of a plurality of annularly arranged jet flames through a centrally arranged pilot flame with parallel to the jet flame flow direction causes the main flow direction of the pilot flame of a recirculation flow to the

Radiation flames is directed opposite, which can lead to disadvantages when igniting. The reason for this is that not the entire pilot flame is available for igniting and stabilizing the jet flames. The stronger the recirculation, the worse the pilot flame can ignite and stabilize. However, a strong recirculation of the hot combustion gases is absolutely necessary for stable operation of the jet flames in order to allow hot gas to be drawn into the jets. The hot gas intake into the jets ignites the jet flames and ensures continuous combustion.

Preferably, the exit velocity of the air-fuel mixture from the Vormischstrahldüse in the reaction chamber or the combustion chamber is greater than that

Flame speed. The laminar flame velocity is the rate at which the fresh gas flows into the flame front under laminar flow conditions during flame reactions. In laminar flames on burners, the flame front is stationary, in turbulent, as occurs in most technical combustion processes, the flame front fluctuates around a central location. The flame speed of the turbulent flame is a multiple of the speed of the laminar flame.

The premix burner according to the invention comprises inter alia a reaction space and at least one premix jet nozzle which opens into the reaction space. He is characterized by in that the premix jet nozzle is designed in such a way that an air-fuel mixture can be injected into the reaction space at a speed which differs from that of the surrounding fluid. The speed is adjusted so that at the forming

Form the interface between the air-fuel mixture and the surrounding fluid vortex. The premix burner according to the invention essentially offers the advantages already described in relation to the method according to the invention.

It is an untwisted premix burner. The air-fuel mixture is injected in the form of an untwisted jet into a reaction space. The jet entry speed may preferably be above the flame speed. Furthermore, the jet entrance velocity may preferably be higher than the velocity of the fluid surrounding the steel. The free jet of each nozzle penetrates into the reaction space and thereby absorbs entrained fluid, primarily already combusted air-fuel mixture. This backflow stabilizes the flame. The speed and extent of the free jet determine the flame length, ensuring that all the fuel burns within the reaction space.

The premix jet nozzle of the premix burner according to the invention may preferably comprise a fuel nozzle. In this case, the premix jet nozzle can be configured such that the fuel through the fuel nozzle parallel to the flow direction of an oxidant present in the premix jet nozzle, for example

Compressor air is injected into this. Alternatively, the premix jet nozzle can be configured such that the fuel nozzle has at least one injection opening which allows the fuel to be injected at an angle between 0 ° and 90 ° to the flow direction of an oxidant present in the premix jet nozzle. In principle, the inlet opening of the premix jet nozzle opening into the reaction chamber and / or the opening of the fuel nozzle opening into the premix jet nozzle can have a round, oval, rectangular or square shape or be designed as a slot.

The premix jet nozzle may also comprise an element which allows adjustment of the oxidant entrance velocity. In this element for setting the

Oxidant inlet velocity may be, for example, a valve or a perforated plate.

The premix burner according to the invention may comprise at least one pilot burner. The pilot burner may be a spin-stabilized burner or a jet burner. In addition, several premix jet nozzles can be arranged to form one ring or several concentric rings around a respective pilot burner. In the case where a plurality of premix jet nozzles are arranged to form a plurality of concentric rings around a pilot burner, it is advantageous if the premix jet nozzles of the various rings are arranged offset from one another. The pilot burner can in particular also be arranged so that the

Flow direction of the pilot flame runs antiparallel to the beam direction of the jet flame.

As an alternative to an arrangement in rings, several premix jet nozzles can also be arranged in one or more rows. Again, it is advantageous to arrange the premix jet nozzles of different rows offset from each other. In any case, it is additionally possible for the directions of irradiation of the premix jet nozzles to have an angle between 0 ° and 90 ° relative to each other.

Overall, it has proven to be advantageous if in each case between two Vormischstrahldüsen a pilot burner is arranged. Preferably, the premix jet nozzles or the premix jet nozzle can be arranged opposite to the pilot burner and offset therefrom.

For cooling, in particular the pilot burner side rear wall of the reaction space, the premix burner may be surrounded by a fluid channel which is connected to a cooling fluid supply. The cooling fluid supply may in particular be an air supply.

The advantage of the present invention lies in the non-injured injection of an air-fuel mixture via nozzles into the reaction space, wherein an optimal distribution of the heat release in the entire reaction space is achieved by a targeted design of the air inlets and the gas mixture within the mixing channels. The resulting better distribution of heat release through individual penetration depths allows a higher combustion stability compared to conventional systems. As a result, combustion oscillations are avoided.

Further features, properties and advantages of the present invention will be described below by means of embodiments with reference to the accompanying figures.

1 shows schematically as the first embodiment

Cross section through a part of the rear wall of a premix burner according to the invention.

FIG 2 shows schematically the propagation direction of the air-fuel mixture and a thereby resulting

Whirl . FIG. 3 shows schematically vortices caused by twisting.

4 schematically shows the arrangement of the inlet openings around the pilot burner on the rear wall of a premix burner according to the invention. FIG 5 shows a second embodiment schematically the

As a third exemplary embodiment, FIG. 6 schematically shows the arrangement of inlet openings and pilot burners on the

Rear wall of a premix burner according to the invention. 7 shows as a fourth embodiment schematically the

Cross section through an inventive

Premix burner in the longitudinal direction. 8 shows a schematic illustration of the fifth exemplary embodiment

Cross section through an inventive

Premix burner in the longitudinal direction. 9 shows schematically a section through a premix burner according to the invention along the sectional plane IX-IX shown in FIG.

The first embodiment of the present invention will be described below with reference to FIGS. 1 to 4.

1 shows schematically the cross section through part of the rear wall of a substantially rotationally symmetrical premix burner 1. The center line 2 denotes the symmetry axis of the premix burner 1. The premix burner 1 comprises a housing 3, a pilot burner 4, a reaction space 5 and a premix jet nozzle 6

Premix jet nozzle 6 has an inlet opening 13, which opens into the reaction space 5. The pilot burner 4, which in the present embodiment is a spin-stabilized burner, is located in the middle of the rear wall of the premix burner 1. It is surrounded concentrically by a plurality of premix jet nozzles 6, which are likewise located on the rear wall of the premix burner 1.

The premix jet nozzle 6 includes a fuel nozzle 8 surrounded by an air intake passage 37. Of the

Air inlet channel 37 and the pilot burner 4 open into the reaction chamber 5. Inside the air inlet channel 37 is a perforated plate 14. The perforated plate 14 is used for regulation the velocity of the incoming oxidant, which in the present embodiment is compressor air. The flow direction of the air flowing through the air inlet passage 37 is indicated by arrows 7.

Through the fuel nozzle 8, fuel is passed into the front, that is to say the part of the premix jet nozzle 6 facing the reaction space 5. The direction of flow of the fuel is indicated by an arrow 9.

In the front part of the premix jet nozzle 6, the incoming air mixes with the fuel flowing in through the fuel nozzle 8. Through the inlet opening 13 of this mixture is injected into the reaction chamber 5. By injecting this mixture at high speed in the

Reaction space 5 forms an interface 11 between the located in the reaction chamber 5 gas, in the present embodiment, at least partially combusted air-fuel mixture, and the injected air-fuel mixture. At this interface 11 arise due to the difference in velocity between the mixture located in the reaction chamber 5 and the injected air-fuel mixture vortices 10. These vortices cause mixing of the injected air-fuel mixture with the gas mixture in the reaction chamber, which contains in particular hot combustion gases, which contribute to the stabilization of the flame.

Preferably, the air is injected through the air inlet passage 37 at a lower velocity into the front part of the premix jet nozzle 6 than the velocity of the fuel injected through the fuel nozzle 8 into the front part of the premix jet nozzle 6. As a result, the air is entrained by the fuel, which promotes the mixing of air and fuel due to the so-called Entrainments. For this purpose, the air can in particular be injected parallel to the fuel in the reaction chamber 5. In Figure 2, a resulting from the inventive method vortex 10 is schematically outlined. FIG. 2 shows the direction of propagation 31, which is equivalent to the main flow direction, of the air-fuel mixture in the reaction space 5 and, by way of example, a vortex 10 formed in this case. Furthermore, the axis 32 of the vortex 10 is outlined. The vortex axis 32 of the resulting vortex 10 in this case runs perpendicular to the propagation direction 31 of the air-fuel mixture. This distinguishes the vortices arising in the context of the method according to the invention from the vortices, which are primarily caused by twisting.

In FIG. 3, for comparison, vortices 33 and 44 are outlined, which were caused by twisting. The axis of the vortex 33 generated primarily by the twisting is distinguished by the fact that it is largely parallel to the direction of propagation 31 of the twisted air-fuel mixture, which is also sketched in FIG. The twisting additionally causes the formation of recirculation vortices 44 whose axes are perpendicular to the propagation direction 31 of the air-fuel mixture, as shown schematically in FIG.

The arrangement of the inlet openings 13 about the pilot burner 4 is outlined in FIG. FIG 4 shows schematically the upper

Half-plane of a section along the IV-IV sectional plane through the rear wall of the premix burner 1 shown in FIG.

The marked in Figure 4 by the reference numeral 26

Center line is perpendicular to the axis of symmetry indicated in Figure 1 by reference numeral 2. One sees in FIG 4 the

Pilot burner 4 and numerous with the reference numerals 13 and

15 designated first inlet openings and second

Inlets of premix jet nozzles.

The first inlet openings 13 are arranged on a concentric circle around the pilot burner 4. The second inlet openings 15 are also on a circle lying concentrically around the pilot burner 4 arranged, wherein the second inlet openings 15 are located at a greater distance from the pilot burner 4 than the first inlet openings 13. The second inlet openings 15 are also arranged offset from the first inlet openings 13. Alternatively, any number of inlet openings may also be arranged on only one circle around the pilot burner 4. Additionally or alternatively, pilot burners may be arranged on a circle whose radius is different from the radius of the circles on which the first and second inlet openings 13 and 15 are arranged. Likewise, the first inlet openings 13, the second inlet openings 15 and / or the pilot burners can be arranged axially offset from one another. Hereinafter, a second embodiment of the present invention will be described in detail with reference to FIG. Elements which correspond to the elements described in the first embodiment are given the same reference numerals and will not be described again.

The special features of the second exemplary embodiment of the premix burner are shown in FIG. 5 shows schematically the cross section through part of the rear wall of a largely rotationally symmetrical premix burner. 5 shows the axis of symmetry 2 running through the center of the premix burner. In the middle of the rear wall is a pilot burner 4 which, as in the first exemplary embodiment, is designed as a spin-stabilized premix burner and is surrounded concentrically by premix jet nozzles 6. In the premix jet nozzles 6 are fuel nozzles 8. The fuel nozzles 8 are of

Surrounded air intake ducts 37. With the aid of the inlet openings 13 and 15, fuel and air 16 is injected into the reaction space 5. For this purpose, fuel is first sprayed through the fuel nozzle 8 into the front part of the premix jet nozzles 6 where it is mixed with air 16 from the air inlet channels 37, and then passed on or injected into the reaction space 5. In the present exemplary embodiment, the fuel nozzles 8 are characterized in that they have openings 34 on their sides facing the reaction space 5, which allow the fuel to exit obliquely to the flow direction of the air flowing in through the air inlet ducts 37. The direction of flow of the fuel is indicated by arrows 9 in FIG. 5; the direction of flow of the air flowing through the air inlet channels 37 is indicated by arrows 7. It can be seen in the FIG 5, that the flow direction of the fuel 9 at the exit through the openings 34 at an angle to the flow direction of the air 7, which flows through the air inlet channels 37 comprises. These angles can be adjusted arbitrarily by a corresponding design of the openings 34. In this case, in particular an angle between the flow direction of the exiting fuel 9 and the flow direction of the incoming air 7 between 0 ° and 45 ° makes sense. Preferably, the fuel is injected into the air intake passages 37 at a higher rate than air. This favors a

Penetration of the fuel into the air flow and thus the mixing of fuel and air.

The air-fuel mixture is injected in the present embodiment through first inlet openings 13 parallel to the center line 2 in the reaction chamber 5. In contrast, the injection of the air-fuel mixture in the reaction chamber 5 by second inlet openings 15 takes place at an angle to the center line 2. At the interfaces 11 between the injected air-fuel mixture and in the

Reaction space 5 air again turn vortex 10. These vortices 10 have the properties described in the previous embodiment.

Hereinafter, a third embodiment of the present invention will be described in detail with reference to FIG. Elements corresponding to the elements described in the first two embodiments are are given the same reference numerals and will not be described again.

The premix burner of the third embodiment is characterized by a different arrangement of inlet openings and pilot burners in comparison to the first two embodiments. FIG. 6 schematically shows an arrangement, which is alternative to FIG. 4, of inlet openings and pilot burners. FIG. 6 shows a top view 17 on the rear side of the reaction space 5 viewed from the reaction space. Both the pilot burner 4 and the inlet openings 18 are arranged concentrically around the center of the rear wall of the reaction space 5. The pilot burner 4 and the inlet openings 18 have the same distance from the center. The four pilot burners shown and the eight intake ports 18 shown in FIG. 6 are arranged such that the intake ports 18 are each adjacent to a pilot burner 4. The inlet openings 18 are further distinguished by the fact that they are not round in contrast to the previously described embodiments, but are designed as rectangular slots with rounded corners. Of course, instead of four pilot burners 4 and eight intake ports 18, any number of pilot burners and intake ports may be used.

The arrangement described has the advantage that the ignition paths are smaller by the arrangement of a plurality of pilot burners than in the previously described embodiments with a central pilot burner. Another advantage is that the plurality of pilot burners allows flexible control of the burnup of the air-fuel mixture. In addition, the individual flames can be specifically stabilized with the help of the various pilot burners.

Hereinafter, a fourth embodiment of the present invention will be described in more detail with reference to FIG. Elements that in the first three Embodiments described correspond elements are provided with the same reference numerals and will not be described again.

7 shows schematically the cross section through a

Premix burner in the longitudinal direction. The premix burner shown in FIG. 7 contains in its interior a reaction space 5 which has an outlet 35 directed toward the turbine for the combustion gases. The reaction space 5 is surrounded by a circumferential channel 19. At the end of the reaction space 5 facing away from the output 35 is a pilot burner 4. The output 35 of the reaction chamber 5 is annularly surrounded by inlet openings 13 of Vormischstrahldüsen 6. The inlet openings 13 are the pilot burner 4 opposite lying and arranged offset radially to this.

The pilot burner 4, which in the present exemplary embodiment is designed as a spin-stabilized burner, is supplied with pilot fuel by a pilot fuel supply 36. The flow direction of the pilot fuel is indicated by an arrow 20. The pilot fuel is injected via the pilot burner 4 in the reaction chamber 5 and burned there. The pilot burner is also supplied with air from the circulating channel 19. A portion of this air is passed from there to the pilot burner 4, another part of the air passes through the circumferential channel 19 to the inlet openings 13. The direction of flow of the air coming from the compressor is through the arrows 24 marked. The air flowing on to the pilot burner 4 is indicated by the arrows 23. The air entering the premix jet nozzles 6 is indicated by the arrows 25.

The air flowing to the pilot burner 4 simultaneously cools the rear side 21 of the reaction space 5. The back 21 is due to the opposite inlet openings 13 through which an air-fuel mixture with high Speed is injected into the reaction chamber 5, exposed to higher thermal loads compared to conventional burners. A corresponding cooling is therefore advantageous.

Each premix jet nozzle 6 in FIG. 7 comprises a fuel nozzle 8. The fuel nozzle 8 opens into the front part of the premix jet nozzle 6, which in turn opens into the reaction space 5 via an inlet opening 13. In the fuel nozzle 8 fuel is passed. The

Flow direction of the fuel is indicated by arrows 27. The fuel is injected via the fuel nozzle 8 in the front part of the Vormischstrahldüse 6. There, the fuel is added to the fuel. The direction of flow of the air is indicated by arrows 25. The air used passes from the compressor via the circumferential channel 19 in the Vormischstrahldüse. 6

The flow direction of the injected via the inlet opening 13 into the reaction chamber 5 air-fuel mixture is indicated by arrows 29. Due to the high velocity of the injected air-fuel mixture, vortices form at the interface between the injected air-fuel mixture and the surrounding gas. The direction of flow of the vortices is indicated by arrows 30. The vortices cause mixing of the injected air-fuel mixture with the gas located in the reaction space 5. This gas is air and hot gas resulting from the combustion of the pilot flame. It supports the from

Pilot burner in the direction of turbine flowing hot gas the formation of this vortex. At the same time, the entire pilot flame located in the reaction space 5 is available for igniting and stabilizing the jet flames. This is achieved in that the pilot burner 4 and the

Inlet openings 13 are arranged antiparallel to each other and offset radially. The main flow direction of the fuel or hot gas of the pilot flame is indicated by arrows 22. This main flow direction 22 of the hot gas of the pilot flame promotes the recirculation around the premixed jets. The achieved in this way high degree of mixing in the reaction chamber 5 promotes stable combustion in the reaction chamber, thus preventing unwanted combustion oscillations.

In the following, further possible variants of the present invention will be described in more detail with reference to FIGS. 8 and 9 as a fifth exemplary embodiment. Elements that correspond to the elements described in the first four embodiments are given the same reference numerals and will not be described again.

FIG. 8 shows, as a fifth exemplary embodiment, the cross section through a premix burner according to the invention in the longitudinal direction. It can be seen in FIG 8, inter alia, the symmetry axis 2, the housing 3 of the premix burner, a Vormischstrahldüse 6 and a centrally located pilot burner 4, which is intended to ensure ignition of the air-fuel mixture. The pilot burner 4 is reset via a cone 43 in the axial direction. Several premix jet nozzles 6 are rotationally symmetric about the symmetry axis 2, i. also around the pilot burner 4, arranged.

The premix burner comprises a reaction space 5 with an outlet 35 leading to a turbine, and a plenum 42 facing the exit 35 and from which

Reaction space is spatially separated by a top plate 41. In plenum 42 is compressor air, which is injected through the premixing dies 6 in the reaction chamber 5. The flow direction of the air is indicated by arrows 7.

Furthermore, in plenum 42, a fuel distributor 12 is arranged, which is connected to a stub 39. In 8, the fuel distributor 12 is arranged starting from the symmetry axis 2 at a larger radius than the stub 39. Of course, the stub 39 can be arranged at a larger radius than the fuel distributor 12. With the help of

Sting line 39, the fuel is injected into the premix jet 6. About the Vormischstrahldüse 6 mixed with the compressor air fuel is injected into the reaction chamber 5 and burned there. The free jet of the resulting flame is indicated by the reference numeral 40.

FIG. 9 schematically shows a section through the premix burner shown in FIG. 8 along the sectional plane IX-IX indicated there. You can see in FIG 9 again the

Reaction space 5, which is separated from the plenum 42 by the top plate 41. In the top plate 41, a premix jet nozzle 6 is introduced, via which an air-fuel mixture is injected into the reaction space 5. In plenum 42 is a stub 39, with which

Fuel can be injected into the premix jet 6. The flow direction of the fuel is indicated by arrows 9. The reaction chamber 5 of the fifth embodiment consists essentially of a cylinder, which are supplied on one side via the top plate 41 air and fuel. In addition to the fuel distributor 12, flow channels may be provided in the plenum 42, which allow guidance and alignment of the air or fuel flow. Also, several pilot burners may be present instead of just one pilot burner. One or more pilot flames should guarantee burnup or ignition of the mixture. Furthermore, it is possible to burn the fuel only via the or the pilot burner 4 at low firing rates.

The air-fuel mixture can via radial slots, as described in connection with FIG 6, in the reaction chamber. 5 enter. On the slots flow channels are attached, with which the flow is directed and in which fuel and air are mixed. In this case, various arrangements of the premix jet nozzles 6 and the pilot burner 4 in the top plate 41 are possible.

In a first variant, the premix jet nozzles 6 can be mounted around a centrally located pilot burner 4, as described in connection with FIG. These extend in the radial direction only over part of the annular surface, and form two groups, which are offset in the circumferential and in the radial direction. The pilot burner 4 may be reset as in FIG 8 via a cone 43 in the axial direction. A flush design can also be realized. Both the inner and the outer ring of the Vormischstrahldüsen 6 have their own fuel supply, so that a gradation of the fuel can take place.

As a second variant, the premix jet nozzles 6 may be mounted in a single ring around a central pilot burner 4, as shown in FIG. This variant is structurally simpler than the first variant.

A third variant has three (alternatively four or any other number greater than one) pilot burners 4 and six (alternatively eight or any other number greater than one) premix jet nozzles 6. The premix jet nozzles 6 as well as the pilot burners 4 are mounted on the same circumference, as described in connection with FIG. The achsenahe range of the burner is unencumbered in this variant and can thus serve for recirculation or to the backflow of already reacted gas. The fuel injection takes place in principle analogous to the variants already mentioned. A staging of the fuel supply can be done by means of two fuel manifolds, each supplying each second inlet port. The proposed arrangements can be made with simple structural methods, an injection of the fuel into the air. This has advantages over variants in which a large number of circular premix jet nozzles 6 are used. The first variant has the advantage that it is possible to tune the air flow and the fuel quantities through the two rows of premix jet nozzles 6. Furthermore, a radial grading or displacement of the amount of fuel can simply take place, so that optionally the radial fuel distribution can be manipulated. The third variant has the advantage that the arrangement of three (or four or any other number, which is greater than one) pilot burners 4, the ignition paths are smaller than in the first two variants with a central burner.

In summary, in the context of the present invention, the reaction is spatially distributed by suitable flow guidance. As a result, combustion-induced instabilities can be largely avoided. The air-fuel mixture is injected at high speed into the reaction space. The resulting high turbulence and high shear of the flow prevents the oxidation of the mixture via a flame. The reaction or oxidation is thus over the

Reaction space distributed. The production of nitrogen oxides is minimal due to the high degree of premixing.

Claims

claims

A method of stabilizing the flame of a premix burner (1) comprising a fluid-containing reaction space (5), characterized in that an air-fuel mixture is injected into the reaction space (5) at a rate different from that of the fluid in the reaction space (5) differs, wherein the air-fuel mixture is injected in the form of an untwisted jet in the reaction space (5), wherein the

Speed is set so that form at the forming interface (11) between the air-fuel mixture and the surrounding fluid vortex (10), wherein the fuel or an air-fuel mixture as a pilot fuel via a pilot burner (4) in the reaction space (5) is injected and wherein the pilot fuel is injected parallel or anti-parallel offset to the air-fuel mixture in the reaction space (5).

2. The method according to claim 1, characterized in that the axes (32) of the forming vortex (10) are perpendicular to the propagation direction (31) of the air-fuel mixture.

3. The method according to claim 1 or 2, characterized in that the air-fuel mixture is formed by that in a premixing jet (6) of the fuel is injected into an oxidizing agent at a rate which is higher than that of the oxidizing agent.

4. The method according to claim 3, characterized in that the fuel is injected parallel to the flow direction of the oxidizing agent in this.

5. The method according to any one of the preceding claims, characterized in that the side of the reaction space (5) at which the pilot burner (4) is cooled with an oxidizing agent, which is then fed to the pilot fuel when injected into the reaction space (5).

6. The method according to any one of claims 3 to 5, characterized in that it is the oxidizing agent is air.

7. premix burner (1) which comprises a reaction space (5) and at least one premix jet nozzle (6) which opens into the reaction space (5), the premix jet nozzle

(6) is designed such that an air-fuel mixture can be injected at a speed in the reaction space (5), which differs from that of the surrounding fluid, wherein the speed is adjusted so that at the forming interface (11 ) between the air-fuel mixture and the surrounding fluid vortex (10).

8. premix burner (1) according to claim 7, characterized in that the Vormischstrahldüse (6) comprises a fuel nozzle (8).

9. premix burner (1) according to claim 8, characterized in that the Vormischstrahldüse (6) is designed so that the fuel through the fuel nozzle (8) parallel to the flow direction (7) of an in the Vormischstrahldüse (6) located oxidant injected into this becomes.

10. premix burner (1) according to claim 8, characterized in that the Vormischstrahldüse (6) is designed so that the fuel nozzle (8) has at least one injection opening (34), which injecting the fuel at an angle between 0 ° and 90 ° to Flow direction (7) of the present in the Vormischstrahldüse (6) oxidant allowed.

11. premix burner (1) according to one of claims 7 to 10, characterized in that in the reaction space (5) opening into the inlet opening (13, 15, 18) of the Vormischstrahldüse (6) and / or in the Vormischstrahldüse (6) opening Opening of the fuel nozzle (8) has a round, oval, rectangular or square shape or is designed as a slot.

12. premix burner (1) according to one of claims 7 to 11, characterized in that the premix jet nozzle (6) has an element for adjusting the oxidant inlet velocity.

13. premix burner (1) according to claim 12, characterized in that it is the element for adjusting the oxidant inlet velocity to a valve or a perforated plate (14).

14. premix burner (1) according to one of claims 7 to 13, characterized in that the premix burner (1) comprises at least one pilot burner (4).

15. premix burner (1) according to claim 14, characterized in that it is the pilot burner (4) is a spin-stabilized burner or a jet burner.

16. premix burner (1) according to any one of claims 14 or 15, characterized in that a plurality of premix jet nozzles (6) are arranged to form a ring or a plurality of concentric rings around a pilot burner (4).

17. premix burner (1) according to claim 16, characterized in that a plurality of premix jet nozzles (6) to form a plurality of concentric rings around a pilot burner (4) are arranged, wherein the premix jet nozzles (6) of the various rings are arranged offset from one another.

18. premix burner (1) according to one of claims 7 to 15, characterized in that a plurality of premix jet nozzles (6) are arranged in one or more rows.

19. premix burner (1) according to one of claims 7 to 18, characterized in that the directions of irradiation of the premix jet nozzles (6) in the reaction space (5) to each other at an angle between 0 ° and 90 °.

20. premix burner (1) according to one of claims 7 to 19 and claim 14, characterized in that that in each case between two premix jet nozzles (6), a pilot burner (4) is arranged.

21. Premix burner (1) according to one of claims 7 to 20 and claim 14, characterized in that the premix jet nozzle (6) is arranged opposite the pilot burner (4) and radially offset therefrom.

22. premix burner (1) according to one of claims 7 to 21, characterized in that the premix burner (1) by a fluid channel (19) is surrounded, which is connected to a cooling fluid supply.

23. premix burner (1) according to claim 22, characterized in that it is the cooling fluid supply to an air supply.