Burner for Powdered and/or Particulate Fuels with Adjustable Swirl

Abstract

A burner for powdered and/or particulate fuels having a flow channel for transporting at least one gas stream into a combustion chamber, wherein the flow channel has an annular cross section and a swirl device imparting a swirl to the gas stream in a circumferential direction. The swirl device has at least a first and a second group of deflection means to generate the swirl, that at least the second group of deflection means is attached in a fixed manner to supporting structure that is axially displaceable along the flow channel and/or can be rotated about the longitudinal axis of the flow channel in order to alter the swirl.

Description

The invention relates to a burner for powdered and/or particulate fuels having a flow channel for transporting at least one gas stream into a combustion chamber wherein the flow channel has an annular cross section and a swirl device imparting a swirl to the gas stream in a circumferential direction.

In order to burn solid fuels with greater efficiency whilst creating fewer toxic substances, burners of the aforementioned type are typically used wherein the burners are assigned to corresponding combustion chambers. The burners are also referred to as pulverised-fuel burners and are used particularly in industrial combustion plants. The fuel must be available in the form of fine particles so that it can be burned using respective burner. Particularly when burning coal, the fuel is ground so finely that it is referred to as coal dust. It is not feasible, however, to grind all fuels so finely.

The fuels are so fine that they can be blown systematically into the combustion chamber via the burner with the help of a gas stream. The gas stream ultimately serves for pneumatic conveyance of the fuel and also generally provides oxygen for the combustion process. In simple scenarios, the gas stream is therefore air.

Oxygen-enriched air or another gas mixture containing oxygen can also be used. The gas stream, which transports the fuel to the combustion chamber, is described as primary air regardless of its composition.

Most burners of the type indicated have additional flow channels through which other gas streams are blown into the combustion chamber. Unlike primary air, said gas streams do not transport any fuel and this is why said gas streams are also referred to as secondary air. In most cases, the primary stream is fed to the combustion chamber close to the centre of the burner cross section. To this end the burner has an annular flow channel for the primary air. Further flow channels can be provided concentrically to said flow channel through which secondary air flows. Secondary air can also be air or another gas mixture containing oxygen, which, where required, consists substantially of oxygen (technical oxygen).

A swirl is imparted in a circumferential direction to the stream of primary air and the stream of secondary air in the burner by means of separate swirl devices. In other words, the stream lines of the primary air and/or the secondary air develop the form of a spiral in the respective flow channel. The swirl device has deflection means to impart the swirl where said means divert the gas stream to one side in a circumferential direction relative to the longitudinal direction of the flow channel. The swirl is required in order to achieve favourable fuel combustion and the formation of only small quantities of nitrogen oxides (NOx).

The optimum swirl of the primary air and/or the secondary air is dependent to a large extent on the fuel used. Particle size, net calorific value and the proportion of volatile components, for example, play a particular role here. Therefore, in order to operate dust firing systems using a wide range of different fuels, the burners used must be adjustable in terms of the swirl generated. To achieve this, the deflection means are distributed mostly over the circumference of the respective annular gap. The pitch angle of the deflection means relative to the longitudinal axis of the annular gap can be varied in the burners known from the prior art, for example DE 10 2005 032 109 A1, by means of various adjustment mechanisms. Disadvantageous in the known adjustment mechanisms, however, is that these are time-consuming and costly to produce, susceptible to faults and difficult to use.

The problem to be solved by the present invention is therefore to refine and further develop the burners known from the prior art in order to minimise the disadvantages known from said prior art.

This problem is solved in a burner according to the features of the preamble of claim 1 in that the swirl device has at least a first and a second group of deflection means distributed over the circumference of the flow channel to generate the swirl, that at least the second group of deflection means is attached in a fixed manner to a supporting structure and that the supporting structure is axially displaceable along the flow channel and/or can be rotated about the longitudinal axis of the flow channel in order to alter the swirl that has been imparted.

The invention has identified that it is extremely easy to vary the swirl imparted to a gas stream in a flow channel if the deflection means are divided into at least two groups of deflection means which can then be adjusted in their position relative to each other. A group of deflection means is attached in a fixed manner relative to each other to a supporting structure which itself can be adjusted in at least one spatial direction. This allows the position of the second group of deflection means relative to the first group of deflection means to be changed. It is therefore basically not necessary for the first group of deflection means to also be configured so as to be moveable in relation to its position in the burner. However, in order to increase the degree of freedom in terms of varying the swirl, the deflection means in the first group of deflection means can also be mounted in a fixed manner relative to each other on a further supporting structure which can be adjusted relative to the flow channel.

A third group of deflection means can be provided to increase the degree of freedom to vary the swirl. Additional groups of deflection means are also conceivable although this would further increase cost and effort in terms of the burner design. Each of these groups of deflection means can be provided in a fixed manner or moveable relative to the respective flow channel. Moreover, with regard to the first two groups of deflection means, the deflection means do not have to be arranged in a completely fixed manner relative to one each other. This is possible, however, because adjustment of the supporting structure is basically sufficient in order to adjust the deflection means as required. If this is required and justifies the additional time and effort, individual or all deflection means from the second group of deflection devices can also be adjustably arranged separately in relation to the other deflection means and/or in relation to the supporting structure.

In the process, particularly the inclination of the deflection means relative to the longitudinal axis of the respective flow channel can be adjustable. It is particularly preferable, however, if the supporting structure can be adjusted relative to the flow channel without simultaneous adjustment of the alignment of the deflection means in the second group of the deflection means relative to each other. This enables not only a defined adjustment of the second group of deflection means in relation to the first group of deflection means, but also achieves a simple burner design.

In order to be able to move one group of deflection means relative to another group of deflection means, the supporting structure can be displaced axially in relation to the flow channel. Alternatively or additionally, the supporting structure can be rotated about the longitudinal axis of the flow channel. In this manner, the swirl in the gas stream can ultimately be adjusted through a simple adjustment of the burner by means of a simply designed and also extremely reliable adjustment mechanism. Complex adjustment mechanisms, which are known from the prior art and also are difficult to operate, are dispensable thanks to the invention.

Corresponding swirl devices can be provided in just one flow channel or in several flow channels to assist adaptation of the burner to various fuels. In particular, the swirl device can be provided in the flow channel of the primary air transporting the fuel, since varying the swirl is particularly important here.

It is also essentially preferred if at least one flow channel and preferably two concentric flow channels for secondary air is/are provided concentric to one flow channel for the primary air. In particular, the flow channels for secondary air are arranged around the flow channel for primary air.

In a first preferred embodiment of the burner, the deflection means have guiding surfaces inclined towards the longitudinal direction of the flow channel. Said guiding surfaces, along which the gas stream flows, divert said gas stream in a circumferential direction. This ultimately leads to a swirl being imparted to the gas stream in the circumferential direction of the flow channel.

Alternatively or additionally it is particularly preferred if the deflection means are configured as guide vanes and/or guide plates. Guide vanes are understood in this context to be deflection means with a curved guiding surface. Such curved guiding surfaces can reduce the loss of pressure caused by the swirl device, where appropriate. A guide plate, on the other hand, is understood to be a deflection means comprising only a thin plate. Guide plates enable considerable savings in terms of material with regard to the swirl device.

Irrespective of this the flow channel can be configured in the form of a hollow cylinder. Said axial region is, for example, at least twice as long as the external diameter of the hollow cylinder shaped flow channel. Corresponding burners enable a stream with a consistent swirl to be conveyed to the combustion chamber where said stream continues further into the combustion chamber.

It has proven particularly advantageous in terms of the simple and compact design of the burner if the flow channel is delimited by an inner tube and an outer tube. It is further preferred for reasons of symmetry if both tubes are configured concentrically to one another. Depending whether the gas stream involves primary air and/or secondary air, the inner tube can be a core tube, a primary tube or a secondary tube. In the case of a core tube, the outer tube will be formed by a primary tube. This embodiment of the burner is particularly preferred because the variation of the swirl, particularly in the primary air, is especially important for fuel combustion. Alternatively or additionally, the inner tube can also be formed by a primary tube or a secondary tube, wherein the outer tube is a secondary tube or a tertiary tube accordingly. In said cases, the gas stream is formed preferably by secondary air not containing fuel.

Essentially it is preferred if the burner has a fuel supply for conveying powdered and/or particulate fuel into the flow channel. The fuel can then be fed specifically to the burner and mixed with primary air in the burner. Prior mixing with the risk of subsequent partial separation and accumulation of fuel in the pipe system can thus be avoided.

At least the second group of deflection means can preferably be adjusted such that the deflection means in the second group of deflection means and the first group of deflection means are aligned flush with one another. Depending on the number of groups of deflection means used, the adjacent deflection means from a plurality of groups of deflection means can also be aligned flush with one another. At least the second group of deflection means can however, in contrast to this, also be adjusted such that the adjacent deflection means at least in the first and the second group of deflection means are arranged offset relative to one another. Preferably the deflection means in the adjacent groups of deflection means are then arranged behind one another, wherein the deflection means partially or fully overlap in the longitudinal direction of the flow channel. Offset and flush positions are not necessarily required to be absolutely offset or flush. A more flush or more offset position of the deflection means in the various groups of deflection means may be involved. Ultimately this may result in the deflection of one group of deflection means being more or less continued by the other group of deflection means. The more offset a plurality of groups of deflection means are arranged relative to one another, the less the deflection of the gas stream will be added to by the individual groups.

Alternatively or additionally, provision can be made for the deflection means in the second group of deflection means to continue in the same position in the deflection means in the first group of deflection means and/or vice versa. In other words, the deflection means in the various groups of deflection means merge into each. The deflection means in the individual groups of deflection means can therefore forma serious of joint deflection means, although the deflection means in the various groups of deflection means are not directly connected to one another. Such an effect can be achieved in the corresponding position of at least the second group of deflection means as with significantly longer deflection means, which here are made up of the individual deflection means in a position of the second group of deflection means.

In order to be able to vary the swirl in the gas stream by adjusting at least the second group of deflection means, in a first position of the second group of deflection means a larger free flow section can be provided in the longitudinal direction of the flow channel between the deflection means in the first and second group of deflection means in a further position of the second group of deflection means, a smaller free flow section for the gas stream can be provided in a longitudinal direction of the flow channel between the deflection means in the first and second group of deflection means. The smaller the free flow section for the gas stream in the longitudinal direction of the flow channel, the less unrestricted the gas stream is in its passage through the deflection means and the more strongly the gas stream is deflected in the longitudinal direction. In other words, the greater the swirl, the smaller the free flow section between the groups of deflection means.

Alternatively or additionally, provision can be made that in one position of at least the second group of deflection means, the deflection means in the first group of deflection means and the second group of deflection means form joint deflection channels inclined towards the longitudinal direction of the flow channel. The deflection means in the at least two groups of deflection means can therefore be brought into a complementary position. In doing so, the deflection means in one group of deflection means together form flow channels which preferably continue unchanged through the deflection means in the other group of deflection means. The groups of deflection means can then jointly deflect the gas stream more strongly. If at least the second group of deflection means is adjusted such that the flow channels of one group of deflection means are not continuations of the flow channels of the other group of deflection means, but are separate channels, significantly less deflection will be achieved and consequently significantly less swirl.

The swirl device can have at least a third group of deflection means distributed over the circumference of the flow channel to generate the swirl. In said case, the degree of swirl imparted to the gas stream will be regulated over a larger area. However, the trade off is frequently higher cost in terms of design for the burner.

In the case of a third group of deflection devices, said group can be provided with deflection means that are arranged in a fixed manner relative to each other and are attached to another supporting structure. The supporting structure can then be provided so as to be axially displaceable along the flow channel and/or rotatable about the longitudinal axis of the flow channel to alter the swirl that has been imparted. Thus, in order to vary the swirl, both the second and the third group of deflection means can be adjusted. This achieves greater freedom in terms of adjusting the swirl. It is, however, simpler in terms of design if only the second group of deflection means is provided so as to be moveable. This is offered in particular if the second group of deflection means is provided between the first and third group of deflection means.

In order to minimise technical costs, it is essentially preferred if the first group of deflection means is provided in a fixed manner in the flow channel.

A burner with a simpler design can be provided if the supporting structure is configured as annular. The supporting structure can then easily follow the outer circumference of the inner tube delimiting the flow channel. The supporting structure can also be configured as a concentric dual ring structure wherein the deflection means are each fixed between the rings of the dual ring structure. In order to minimise disruption of the gas stream as far as possible, the inner ring of the dual ring structure can follow the outer circumference of the inner tube delimiting the flow channel whereas the outer ring of the dual ring structure follows the inner circumference of the outer tube delimiting the outer flow channel.

The invention is explained in more detail below using a drawings showing only example embodiments. The drawings show

FIG. 1 is a longitudinal section of a first embodiment of a burner according to the invention,

FIG. 2A is a detailed view of a swirl device of the burner of FIG. 1 showing the deflection means spaced apart from one another,

FIG. 2B is a detailed view of a swirl device of the burner of FIG. 1 showing the deflection means adjacent to one another,

FIG. 3A is a schematic view of a swirl device of a second embodiment of a burner according to the invention showing flow when the movable deflection means is spaced apart from the stationary deflection means,

FIG. 3B is a schematic view of a swirl device of a second embodiment of a burner according to the invention showing flow when the movable deflection means is adjacent to the stationary deflection means,

FIG. 4A is a schematic view of a swirl device of a third embodiment of a burner according to the invention showing the flow when the rotatable deflection means is not aligned with the stationary deflection means, and

FIG. 4B is a schematic view of a swirl device of a third embodiment of a burner according to the invention showing the flow when the rotatable deflection means is aligned with the stationary deflection means.

FIG. 1 shows a longitudinal section of a burner 1 which is arranged in the wall W of a combustion chamber B. The burner 1 has a series of tube sections arranged concentrically in relation to each other. A core tube 3 is provided centrally and concentrically to the central axis 2 of burner 1. A burner lance or other means shown purely schematically here can be provided in the core tube 3.

A primary tube 4 is provided concentrically to the core tube 3, where said primary tube 4 encloses with the core tube 3 a flow channel 5 with an annular cross section. The core tube 3 and the primary tube 4 create a flow channel 5 in the form of a hollow cylinder. In said flow channel 5, the primary air is transported in the direction of the combustion chamber. Prior to this a particulate fuel is introduced into the primary air via a feed device that is not shown. The particles in the fuel are not shown in FIG. 1 for reasons of clarity. The primary tube 4 ends adjacent to the combustion chamber B in a primary throat 6 with a conically extended cross section. A flame holder 7 is attached to the primary throat 6. The flame holder 7 has a toothed edge 8 that protrudes radially into the primary air which assists the generation of swirl in the primary air in the combustion chamber B.

A first secondary tube 9 and a second secondary tube 10 are provided concentrically to the primary tube 4. The respective external tube 9,10 also forms annular flow channels 11,12 for secondary air with the respective internal tube 4,9; no fuel particles are added to said air. A secondary throat 13 with a conically extended cross section is provided at the outlet end of the internal secondary tube 9. A muffle 14 in the form of a conical extension is provided at the outlet end of the second secondary tube 10. The angle of inclination of the muffle 14 is greater than the angle of inclination of the secondary throat 13, the angle of inclination of which is greater than the angle of inclination of the primary throat 6. Cooling ducts 15 are assigned to the muffle 14 for cooling purposes, some of said ducts are positioned between the muffle 14 and the wall W of the combustion chamber B and some on the inner side of the wall W of the combustion chamber B. The concentric arrangement of core tube 3, primary tube 4 and the secondary tubes 9,10 as well as the assignment of the device for supplying particulate fuel, i.e. the concentric arrangement of the annular flow channels 5,11,12, means that a further two secondary air streams are guided into the combustion chamber B around the primary air stream conducting the fuel. Further secondary tubes and flow channels can be provided for further secondary air where required. It is possible to dispense with the second secondary tube 10, however, but this is generally required in fewer cases.

A swirl in the circumferential direction is imparted to the primary air stream, which flows through the annular gap between the core tube 3 and the primary tube 4, with the help of swirl device 16. The primary air stream is offset in rotation from the central axis 2 in the shape of a spiral. In the burner 1 shown and preferred in this respect, the swirl device 16 is composed of three groups of deflection means 17, 18, 19 distributed over the circumference of the flow channel to deflect the primary air stream in a circumferential direction.

Further swirl devices 20, 21 are provided in the other flow channels 11, 12 for the secondary air streams; said swirl devices impart a swirl to the secondary air streams in the circumferential direction of the flow channels 11, 12. In the burner 1 shown and preferred in this respect, the swirl devices 20, 21 in the flow channels 11, 12 for the secondary air each have only one group of deflection means distributed over the circumference of the flow channels 11, 12. A plurality of groups of deflection means could however be provided behind one another, where required in addition to or as a replacement for the swirl device 16 with a plurality of groups of deflection means 17,18,19 in the flow channel 5 delimited by the core tube 3 and the primary tube 4.

The core tube 3 of the burner 1 and the swirl device 16 are shown as a detail of the burner 1 in FIGS. 2a and 2b. In the burner 1 shown and preferred in this respect, the swirl device 16 has three groups of deflection means 17, 18, 19 which are configured here in the form of deflection plate. The deflection means 17, 18, 19 in each group of deflection means 17, 18, 19 are arranged over the circumference of the flow channel 5 for the primary air. The deflection means 17 in the first group of deflection means 17 are permanently fixed onto the core tube 3 whereas the deflection means 18, 19 in the other groups of deflection means 18,19 are attached in a fixed manner relative to each other on annular shaped supporting structures 22,23. The supporting structures 22, 23 are provided so as to be displaceable in the longitudinal direction of the flow channel 5 in the burner 1 shown and preferred in this respect. Therefore the deflection means 17, 18, 19 can assume the positions shown in FIGS. 2a and 2b.

In FIG. 2a the groups of deflection means 17, 18, 19 are clearly spaced apart from each another. The spacing between the groups of deflection means 17, 18, 19 corresponds in the burner 1, shown and preferred in this respect, to at least the width of the groups of deflection means 17, 18, 19 in a longitudinal direction of the flow channel 5. Consequently, the primary air stream is deflected by each of the groups of deflection means 17, 18, 19 in a circumferential direction which generates a swirl. However, the primary air stream is not deflected between the groups of deflection means 17, 18, 19 and consequently the swirl imparted previously may be partially eliminated again. If the supporting structures 22, 23 on which the second group of deflection means 18 and the third group of deflective means 19 are mounted, are displaced in a longitudinal direction of the flow channel 5, the gaps between the deflection means 17, 18, 19 in the groups of deflection means 17, 18, 19 will close more or less completely. This will create continuous flow channels 24 which strongly deflect the primary gas stream in a circumferential direction thus imparting a bigger swirl to the primary gas stream.

The principle of adjusting the swirl is described again in FIGS. 3a and 3b using a swirl device having a first group of deflection means 31 and a second group of deflection means 32. Here FIGS. 3a and 3b show, for the purposes of greater clarity, an arrangement of the core tube 33 with the deflection means 31, 32 provided thereon. The first group of deflection means 31 is fixed so as to be stationary on the core tube 33. The second group of deflection means 32 is however only attached in a fixed manner relative to each other on a supporting structure 34 which itself can be displaced in the longitudinal direction of the flow channel. The flow lines S show that in the spaced position of the groups of deflection means 31, 32 shown in FIG. 3a, when passing through each group of deflection means 31,32, the primary air stream is deflected partly in a circumferential direction and passes through to some extent virtually unhindered in the longitudinal direction. If the second group of deflection means 32 is pushed towards to the first group of deflection means 31, then the deflection means 32 in the second group of deflection close the free flow sections in the first group of deflection means 31 and vice versa. The free flow sections are characterised in FIG. 3a by the circumferential segments Q, through which parts of the primary gas stream can pass in a straight line in a longitudinal direction of the flow channel between the deflection means 31, 32. In the burner 35 shown in the position as per FIG. 3b, the entire primary gas stream is substantially deflected in a circumferential direction of the flow channel whereby the swirl imparted to the primary gas stream is significantly increased. To deflect the primary gas stream, the deflection means 31, 32 have guide surfaces 36 which protrude into the primary gas stream.

Also in the burner 40, which is shown schematically in FIGS. 4a and 4b, the first group of deflection means 41 is fixed so as to be stationary on the core tube 42, of which an arrangement is shown in FIGS. 4a and 4b. The second group of deflection means 43 is however attached in a fixed manner relative to each other on a supporting structure 44. The supporting structure 44 can be rotated about the central axis of the burner 40. In this way the overlap of the deflection means 41, 43 in both groups of deflection means 41,43 can be altered and consequently the swirl in the primary gas stream can be varied. In the position of the second group of deflection means 43 as per FIG. 4a, the deflection means 41,43 leave a free flow section open, through which some of the primary air stream can pass in a straight line in a longitudinal direction of the flow channel. The open section is again characterised by the circumferential segments Q. This is not the case in the position of the second group of deflection means 43 as per FIG. 4b. The free cross sections are closed and the entire primary air stream is deflected and thus ultimately the swirl imparted to the primary air stream is increased.

By displacing at least the second group of deflection means with the supporting structure 22,23,34 alongside the core tube 3,33 or by rotating at least the second group of deflection means 43 together with the supporting structure 44, the groups of deflection means 17,18,19,31,32,41,43 can be brought into a position as per FIG. 2b, 3b or 4b. The deflection means 17, 31, 41 in the first group of deflection means 17, 31, 41 and the deflection means 18, 19, 32, 43 in the second group of deflection means 18, 19, 32, 43 are then aligned flush with each other wherein the deflection means 18, 19, 32, 43 in the second group of deflection means 18, 19, 32, 43 continue into the deflection means 17, 31, 41 in the first group of deflection means 17, 31, 41. In other words, the deflection means 17, 31, 41 in the first group of deflection means 17, 31, 41 and the second group of deflection means 18, 19, 32, 43 form joint deflection channels inclined towards the longitudinal direction of the flow channel.

In order to impart less swirl to the primary air stream, at least the second group of deflection means 18, 19, 32, 43 can be brought into a position as per FIG. 2a, 3a or 4a. In said position, deflection means 17, 18, 19, 31, 32, 41, 43 in the first group of deflection means 17, 31, 41 and the second group of deflection means 18, 19, 32, 43 are arranged offset relative to one another. Flush with a deflection means 17, 18, 19, 31, 32, 41, 43 in one group of deflection means 17, 18, 19, 31, 32, 41, 43 is a space between two deflection means 17, 18, 19, 31, 32, 41, 43 in another group of deflection means 17, 18, 19, 31, 32, 41, 43. Both groups of deflection means 17, 18, 19, 31, 32, 41, 43 each therefore form separate deflection channels between the deflection means 17, 18, 19, 31, 32, 41, 43 which are inclined towards the longitudinal direction of the flow channel, but are nevertheless provided as overlapping each other in the longitudinal direction.

Claims

1. A burner for powdered and/or particulate fuels, comprising:

a flow channel for transporting at least one gas stream into a combustion chamber,

wherein the flow channel has an annular cross section and a swirl device imparting a swirl to the gas stream in a circumferential direction, wherein

the swirl device has at least one first and one second group of deflection means distributed over the circumference of the flow channel to generate the swirl,

at least the second group of deflection means is attached in a fixed manner relative to each other on a supporting structure, and

the supporting structure is axially displaceable along the flow channel and/or is provided so as to be rotatable about the longitudinal axis of the flow channel in order to alter the swirl imparted.

2. The burner according to claim 1,

wherein, in order to impart the swirl in the circumferential direction, the deflection means have guide surfaces inclined towards the longitudinal direction of the flow channel.

3. The burner according to claim 1,

wherein the deflection means are configured as guide vanes and/or guide plates.

4. The burner according to claim 1, wherein the flow channel is configured in the shape of a hollow cylinder.

5. The burner according to claim 1, wherein the flow channel is delimited by an inner tube, preferably core tube, and an outer, in particular concentric, tube, preferably primary tube.

6. The burner according to claim 1, wherein a fuel supply is provided for feeding powdered or particulate fuel into the flow channel.

7. The burner according to claim 1, wherein in a first position of at least the second group of deflection means, adjacent deflection means in the first and second group of deflection means are aligned flush with one another and that in a second position of at least the second group of deflection means the adjacent deflection means in the first and second group of deflection means are arranged offset relative to one another.

8. The burner according to claim 1, wherein the deflection means in the second group of deflection means continue into the deflection means in the first group of deflection means and/or vice versa.

9. The burner according to claim 1, wherein, in a first position of at least the second group of deflection means, adjacent deflection means of at least the first group of deflection means and the second group of deflection means have a larger free flow section for the gas stream in a longitudinal direction of the flow channel than in a second position of the at least second group of deflection means.

10. The burner according to claim 1, wherein in a position of at least the second group of deflection means, the deflection means in the first group of deflection means and the second group of deflection means form joint deflection channels and/or flow channels inclined towards the longitudinal direction of the flow channel.

11. The burner according to claim 1, wherein, in a position of at least the second group of deflection means, the deflection means in the first group of deflection means and the second group of deflection means form separate deflection channels and/or flow channels inclined towards the longitudinal direction of the flow channel.

12. The burner according to claim 1, wherein the swirl device has at least a third group of deflection means distributed over the circumference of the flow channel to generate the swirl.

13. The burner according to claim 12, wherein

the third group of deflection means is attached in a fixed manner relative to each other on a further supporting structure, and

the supporting structure for altering the imparted swirl is axially displaceable along the flow channel and/or is provided so as to be rotatable about the longitudinal axis of the flow channel.

14. The burner according to claim 1, wherein the first group of deflection means is provided in a fixed manner in the flow channel.

15. The burner according to claim 1, wherein the supporting structure is configured as annular.