EP0797051B1 - Burner for a heat generator - Google Patents

Description

Technical field

The present invention relates to a burner according to the preamble of claim 1, as known from EP 0 670 456 A1.

State of the art

a) Luftbypass in der Brennkammer;

b) Herunterfahren der Brennstoffmenge bei einem Teil der operierenden Brenner;

c) Umschalten auf eine Diffusionsstufe, wie dies üblicherweise als Standardmethode bewerkstelligt wird.

Die ersten zwei Methoden gemäss a) und b) bedingen komplexe Brennkammerkonstruktionen oder Brennstoffverteilsysteme. Die dritte Methode gemäss c) führt zu einem sprunghaften Anstieg der NOx-Emissionen, dergestalt, dass diese in den höheren Lastbereichen über die vom Gesetzgeber maximal festgelegten Werte fallen.All burners that are operated as pure premix burners deliver the lowest NOx emissions at operating points that are very close to the lean extinguishing limit. For this reason, the air distribution during the operation of gas turbines with premixing combustion chambers is designed in such a way that an operating point which is as lean as possible but can still be operated reliably results. If the load is reduced below the maximum output by reducing the amount of fuel, flame extinguishing results without control intervention in the compressor, since the lean extinguishing limit is exceeded. If the amount of compressor air can be modulated in this context, as is the case with modern gas turbines, flame extinguishing can in principle be prevented by reducing the amount of air, in the sense that the adiabatic flame temperature is kept approximately constant. In general, however, the temperature in the low-pressure part of the turbine rises inadmissibly as a result of the turbine pressure ratio becoming smaller. Common methods to work around this problem are:

a) air bypass in the combustion chamber;

b) shutting down the amount of fuel in some of the operating burners;

c) Switching to a diffusion level, as is usually done as a standard method.

The first two methods according to a) and b) require complex combustion chamber designs or fuel distribution systems. The third method according to c) leads to a sudden increase in NOx emissions in such a way that in the higher load ranges they fall above the maximum values specified by law.

EP-B1-0 321 809 describes a shell made of several shells conical burner, so-called double cone burner, for Generation of a closed swirl flow in the cone head has become known, which due to the increasing swirl along the cone axis becomes unstable and into an annular swirl flow with reverse flow in the core. Fuels such as gaseous fuels are produced along the the individual adjacent shells formed channels, too Called air inlet slots, injected and homogeneous with the Air mixes before combustion by ignition at the stagnation point the backflow zone or backflow bubble, which acts as a flame holder is used. Liquid fuels will be preferably injected via a central nozzle on the burner head and then evaporate in the cone cavity. Among those typical of gas turbines The ignition of these liquid fuels takes place under conditions early in the vicinity of the fuel nozzle, with what What cannot be avoided is that the NOx values are precisely due to this lack of premix increase sharply, for example it is necessary to inject water. About that It also had to be found that the attempt to contain hydrogen Burning gases similar to natural gas leads to pre-ignition problems at the gas wells with subsequent Have caused the burner to overheat. You have against this Remedy sought by using a special injection method at the burner outlet introduced for such gaseous fuels the results of which have not been entirely satisfactory were able.

Presentation of the invention

The invention seeks to remedy this. The invention how it is characterized in the claims, the task lies based on precautions for a burner of the type mentioned propose by which a perfect premix of fuels of various types and achieved which are reliable and optimal flame positioning is reached at the desired location.

On the one hand, the proposed burner includes precautions, which is on the head side and upstream of a downstream mixing section has a swirl generator, preferably in this regard can be interpreted that the basic aerodynamic principles the so-called double-cone burner according to EP-A1-0 321 809 can be used. In principle, however, is the use an axial or radial swirl generator possible. The Mixing section itself preferably consists of a tubular one Mixing element, hereinafter called mixing tube, which is a significantly improved premixing of different fuels Kind allowed.

The flow from the swirl generator is seamless into the mixing tube initiated: This is done by a transition geometry, which consists of transition channels, which in the initial phase this mixing tube are excluded, and which the flow in the subsequent effective flow cross-section transfer the mixing tube. This low loss Flow introduction between swirl generator and mixing tube initially prevents the immediate formation of a backflow zone at the exit of the swirl generator.

First, the swirl strength in the swirl generator is above its Geometry chosen so that the vertebra does not burst in the mixing tube, but further downstream at the combustion chamber inlet takes place, the length of this mixing tube dimensioned so is that there is sufficient mix quality for everyone Fuel types results. For example, is the one used Swirl generator according to the basic principles of the double-cone burner built up, the twist strength results from the design the corresponding cone angle, the air inlet slots and their number.

The axial speed profile has a pronounced profile in the mixing tube Maximum on the axis and thereby prevents backfire in this area. The axial speed drops down to the wall. To reignite this area too prevent various measures are provided: For example, on the one hand, the entire speed level by using a mixing tube with a sufficient Lift small diameter. Another possibility consists of only the outside speed of the Increase mixing tube by a small part of the combustion air over an annular gap or through filming holes flows into the mixing tube downstream of the transition channels.

As for the mentioned transition channels to initiate the flow affects from the swirl generator in the mixing tube, so to say that the course of these transition channels is spiral can be constricting or expanding accordingly the effective subsequent flow cross-section of the mixing tube.

Part of the pressure loss that may be generated can be caused by Attachment of a diffuser at the end of the mixing tube compensated become. In this area or upstream one can also Venturi range can be provided.

The combustion chamber closes at the end of the mixing tube a cross-sectional leap. A central one is formed here Backflow zone, the properties of which are those of a flame holder are. The creation of a stable backflow zone requires one sufficiently high swirl number in the mixing tube. But it is one Initially undesirable, stable backflow zones can occur the supply of small, strongly swirled air volumes, 5-20% of the Total air volume generated at the end of the pipe.

a) Stabile Flammenposition;

b) Tiefere Schadstoff-Emissionen (Co, UHC, NOx);

c) Minimierung der Pulsationen;

d) Vollständiger Ausbrand;

e) Grosse Betriebsbereich-Abdeckung;

f) Gute Querzündung zwischen den verschiedenen Brennern, insbesondere bei gestufter Lasterstellung, bei welcher die Brenner untereinander interdependent betrieben werden;

g) Die Flamme kann der entsprechenden Brennkammergeometrie angepasst werden;

h) Kompakte Bauweise;

i) Verbesserte Mischung der Strömungsmedien;

j) Verbesserter "Patternfaktor" der Temperaturverteilung in der Brennkammer (= ausgeglichenes Temperaturprofil der Brennkammerströmung).

In connection with the mentioned cross-sectional jump, the end of the mixing tube is formed with a tear-off edge, which gives the backflow zone a high spatial stability. In general, the measures mentioned can achieve the following advantages:

a) Stable flame position;

b) Lower pollutant emissions (Co, UHC, NOx);

c) minimization of pulsations;

d) complete burnout;

e) Large operating area coverage;

f) Good cross-ignition between the different burners, especially with a stepped load position, in which the burners are operated interdependently with one another;

g) The flame can be adapted to the corresponding combustion chamber geometry;

h) compact design;

i) Improved mixing of the flow media;

j) Improved "pattern factor" of the temperature distribution in the combustion chamber (= balanced temperature profile of the combustion chamber flow).

On the other hand, this burner can be expanded in such a way that in the area of the cross-sectional jump, concentric to Mixing tube, a number of individual, self-contained mixing elements are arranged, each mixing element having the properties of a pilot burner shows as long as the air ratio is chosen accordingly. A small part of the combustion air is branched off from the main air flow and flows into said Mixing elements, here 2 to 10% combustion air are sufficient. Each mixing element has at least one a fuel nozzle, the mixture formed therein via Injection openings in the front wall injected into the combustion chamber becomes. In the event of an overload in the area of the combustion air supply the mixing element practically only conveys fuel, as is the case with a normal diffusion level is. This is of particular importance because it is the requirement profile of the burner, namely minimal NOx emissions and high stability range of the flame when idling and load shedding, can be met without the need for separate fuel supplies to the machine are necessary. Such an extension the burner according to EP-B1-0 is also capable of mixing elements 321 809 to increase quality.

Advantageous and expedient developments of the inventive Task solutions are characterized in the other claims.

Exemplary embodiments are described below with reference to the drawings the invention explained in more detail. All for the immediate Understand the invention are non-essential features been left out. The same elements are in the different Figures with the same reference numerals. The The direction of flow of the media is indicated by arrows.

Brief description of the drawings

Fig. 1

einen Brenner mit anschliessender Brennkammer,

Fig. 2

einen Drallerzeuger in perspektivischer Darstellung, entsprechend aufgeschnitten,

Fig. 3

einen Schnitt durch den 2-Schalen-Drallerzeuger, nach Fig. 2,

Fig. 4

einen Schnitt durch einen 4-Schalen-Drallerzeuger,

Fig. 5

einen Schitt durch einen Drallerzeuger, dessen Schalen schaufelförmig profiliert sind,

Fig. 6

eine Darstellung der Form der Uebergangsgeometrie zwischen Drallerzeuger und Mischrohr und

Fig. 7

eine Abrisskante zur räumlichen Stabilisierung der Rückströmzone.

It shows:

Fig. 1

a burner with subsequent combustion chamber,

Fig. 2

a swirl generator in a perspective view, cut open accordingly,

Fig. 3

3 shows a section through the 2-shell swirl generator, according to FIG. 2,

Fig. 4

a section through a 4-shell swirl generator,

Fig. 5

a step through a swirl generator, the shells of which are profiled in a shovel shape

Fig. 6

a representation of the shape of the transition geometry between swirl generator and mixing tube and

Fig. 7

a tear-off edge for spatial stabilization of the backflow zone.

Ways of carrying out the invention, commercial usability

Fig. 1 shows the overall structure of a burner. Is initially a swirl generator 100 effective, the design of which in the following Fig. 2-5 shown and described in more detail becomes. This swirl generator 100 is a conical one Formations that are tangential multiple times from a tangential inflowing combustion air flow 115 is applied becomes. The flow that forms here is based on a transition geometry provided downstream of the swirl generator 100 transitioned seamlessly into a transition piece 200, in such a way that no separation areas can occur there. The configuration of this transition geometry is under Fig. 6 described in more detail. This transition piece 200 is on the outflow side the transition geometry through a tube 20 extended, both parts of the actual mixing tube 220, also called mixing section, form the burner. Of course the mixing tube 220 may consist of a single piece, i.e. then that the transition piece 200 and pipe 20 merged into a single coherent structure are, preserving the characteristics of each part stay. Become transition piece 200 and tube 20 from two parts created, they are connected by a socket ring 10, the same bushing ring 10 on the head side as the anchoring surface serves for the swirl generator 100. Such a Bushing ring 10 also has the advantage that different Mixing tubes can be used. outflow side of the tube 20 is the actual combustion chamber 30, which only symbolizes here through the flame tube is. The mixing tube 220 meets the condition that downstream of the swirl generator 100 provided a defined mixing section in which a perfect premix of fuels of different types is achieved. This mixing section, so the mixing tube 220, furthermore enables a loss-free Flow guidance, so that it is also in operative connection do not initially form a backflow zone with the transition geometry can, which over the length of the mixing tube 220 to the Mix quality for all types of fuel influence can be exercised can. This mixing tube 220 has yet another property, which is that in the mixing tube 220 itself the axial speed profile has a pronounced maximum owns the axis so that the flame reignites the combustion chamber is not possible. However, it is correct that with such a configuration this axial speed falls to the wall. To reignite in this area too to prevent the mixing tube 220 in flow and Circumferential direction with a number of regular or irregular distributed holes 21 of different cross-sections and directions opposite the burner axis 60, through which an amount of air into the interior of the mixing tube 220 streams, and along the wall like a film induce an increase in speed. A there is another possibility to achieve the same effect in that the flow cross section of the mixing tube 220 on the outflow side of the transition channels 201, which the already form the transition geometry mentioned, undergoes a narrowing, whereby the overall speed level within the Mixing tube 220 is raised. These run in the figure Bores 21 at an acute angle with respect to the burner axis 60. The outlet of the transition channels also falls 201 with the narrowest flow cross section of the Mixing tube 220 together. The aforementioned transition channels 201 bridge the respective cross-sectional difference, without negatively influencing the flow formed. If the chosen precaution when guiding the pipe flow 40 along the mixing tube 220 an intolerable If pressure loss triggers, this can be remedied be by not at the end of the mixing tube in the figure shown diffuser is provided. At the end of the mixing tube 220 is followed by a combustion chamber 30, with between the two flow cross sections one through a front wall 80 formed cross-sectional jump 70 is present. Only here A central backflow zone 50 is formed, which has the properties of a flame holder. Forms within this cross-sectional jump 70 during operation one flow-like edge zone, in which by the predominant there Vacuum vortex detachments arise, this leads to an increased ring stabilization of the backflow zone 50. The creation of a stable backflow zone 50 requires one sufficiently high number of twists in the pipe in question. Is a initially undesirable, stable backflow zones can be created by supplying small, highly swirled air currents on the Pipe end generated, for example by tangential openings become. It is assumed here that this required air volume is approximately 5-20% of the total air volume.

As for the design of the tear-off edge at the end of the mixing tube 220, reference is made to the description under FIG. 7.

Vertical or quasi-perpendicular to the front wall 80 become concentric arranged a number of mixing elements 300 to the mixing tube 20, which consist of a tubular flow channel, with a part 115a flowing through combustion air are usually available, 2-10% of the total standing combustion air 115. The mixing element has at a suitable point at least one feeder 301 for insertion a fuel 303. With appropriate training both of the mixing element 300, its air inlet geometry as well as the fuel injection can both liquid as well as gaseous fuels. The Dimensions of the air inlet geometry and the fuel injection are designed so that the full combustion air resp. Amount of fuel required for supported operation the entire load range are necessary in the mixing element 300 can be introduced. The fuel quantities are at full load between main level (100) and pilot level (300) chosen approximately proportional to the air distribution. The combustion chamber side Output of the mixture formed in the mixing element 300 304 is taken over by a nozzle 31, which in the Front wall 80 is integrated. The number of wreathed around the mixing tube 20 arranged mixing elements 300 is the respective one Configuration of the burner and its operating parameters customized.

It has been shown in connection with the mixing elements 300 that you can pre-mix the air ratio range of the here operable burner in the direction of lean mixtures a piece can expand far without having to buy increased CO emissions must be taken if in the immediate vicinity of the Burner is a strong ignition source. Such kind forms a flame front, which is reflected in the mixture propagates. Preferably, therefore, with falling load only reduced the amount of fuel in the main stage, being moderate Increasing the amount of fuel in the pilot stage, within whose limit with regard to NOx emissions is permissible, such that with this configuration an increase in Ignition effect is given.

Over a certain combustion air number, i.e. under a limit load the combustion chamber 30, the flame front no longer spreads quickly enough so that unburned fuel emits becomes. This is remedied by the Fuel 303 more and more only that which can be operated as a pilot stage Mixing element 300 is supplied. Because the air ratio here very quickly takes on very small values (<< 1), and the Air flow through the flow channels due to the large The amount of fuel that is partially blocked differs this mode of operation of the pilot stages is not significantly different from that an ordinary diffusion combustion stage.

Basically, the mixing element 300 exhibits the same properties a pilot burner, as long as the air ratio is appropriate is selected. In case of overload with regard to the amount of combustion air promotes the mixing element 300 practically only Fuel, like this a normal diffusion burner does. This is of particular importance since it means the requirement profiles with regard to minimized NOx emissions Support flame in the high load range of the combustion chamber and the extremely high stability range of the support flame when idling and load shedding can be met without having to separate Fuel supplies to the combustion chamber 30 are necessary.

The mixing elements 300 described are not provided limited to the burner shown here. In a similar way these elements can also be used in a burner according to EP-0 321 809 B1 in the area of those described and shown there Front wall can be provided. This publication forms accordingly integral part of this description.

In order to better understand the structure of the swirl generator 100 it is advantageous if at the same time as FIG. 2, at least FIG. 3 is used. Furthermore, this Fig. 2 is not unnecessary to be confusing, they are those according to the Figure 3 schematically shown guide plates 121a, 121b only hinted been recorded. In the following, the Description of Fig. 2 as required on the figures mentioned pointed.

The first part of the burner according to FIG. 1 forms the one according to FIG. 2 shown swirl generator 100. This consists of two hollow conical partial bodies 101, 102 which are offset from one another are nested. The number of conical Partial body can of course be larger than two, such as Figures 4 and 5 show; this depends on how each further will come closer to the explanation below, of the type of debt collection of the whole burner. It is with certain operating constellations not excluded one from one single spiral existing swirl generator. The Offset of the respective central axis or longitudinal symmetry axes 101b, 102b of the tapered partial bodies 101, 102 to one another creates in the neighboring wall, in mirror image Arrangement, each a tangential channel, i.e. an air inlet slot 119, 120 (Fig. 3) through which the combustion air 115 in the interior of the swirl generator 100, i.e. in flows through the cone cavity 114 thereof. The cone shape of the one shown Partial body 101, 102 has a flow direction certain fixed angle. Of course, depending on the operational use, can the partial body 101, 102 in the flow direction have an increasing or decreasing taper similar to a trumpet or Tulip. The latter two Shapes are not included in the drawing as they are for the expert can be easily understood. The two tapered partial bodies 101, 102 each have a cylindrical Initial part 101a, 102a, which also, analogous to the tapered Partial bodies 101, 102 run offset from one another, so that the tangential air inlet slots 119, 120 over the entire length of the swirl generator 100 are present. In the area of the cylindrical initial part, a nozzle 103 is preferred for a liquid fuel 112 housed, its injection 104 with the narrowest cross section of the through conical partial body 101, 102 formed conical cavity 114 coincides. The injection capacity and the type of this Nozzle 103 depends on the specified parameters of the respective burner. Of course, the swirl generator can 100 purely conical, i.e. without cylindrical starting parts 101a, 102a. The tapered body 101, 102 also each have a fuel line 108, 109 on which along the tangential air inlet slots 119, 120 arranged and provided with injection openings 117 are, through which preferably a gaseous fuel 113 injected into the combustion air 115 flowing through there is how the arrows 116 symbolize this. This Fuel lines 108, 109 are preferably no later than End of tangential inflow, before entering the cone cavity 114, placed, this for an optimal Obtain air / fuel mixture. At that through the nozzle 103 fuel introduced 112, as mentioned, normally a liquid fuel, whereby a mixture formation with another medium without any problems is possible. This fuel 112 will tip under one Angle injected into the cone cavity 114. From the nozzle 103 A conical fuel spray 105 is thus formed, which by the rotating combustion air 115 flowing in tangentially is enclosed. In the axial direction, the concentration of the injected fuel 112 continuously through the inflowing combustion air 115 to mix with evaporation quality reduced. Becomes a gaseous fuel 113 introduced via the opening nozzles 117, the happens Formation of the fuel / air mixture directly at the end of the Air inlet slots 119, 120. Is the combustion air 115 additionally preheated, or for example with a recirculated This enriches flue gas or exhaust gas sustainable evaporation of liquid fuel 112, before this mixture flows into the downstream stage. The The same considerations also apply when using the lines 108, 109 liquid fuels should be supplied. at the design of the tapered partial body 101, 102 with respect the cone angle and the width of the tangential air inlet slots 119, 120 are strict limits to be observed, so that the desired flow field of the combustion air Set 115 at the output of swirl generator 100 can. Generally speaking, a downsizing of the tangential air inlet slots 119, 120 the faster Formation of a backflow zone already in the area of the swirl generator favored. The axial speed within the Swirl generator 100 cannot be replaced by a corresponding one change the supply of an axial combustion air flow shown. Appropriate swirl generation prevents formation of flow separation within the swirl generator 100 downstream mixing tube. The construction of the swirl generator 100 is also excellent, the size to change the tangential air inlet slots 119, 120, with which without changing the overall length of the swirl generator 100 a relatively large range of operations can be covered can. Of course, the partial bodies 101, 102 are also in slidable to another level, which even an overlap of the same can be provided. It is further possible, the partial body 101, 102 by an opposite to interleave rotating movement in a spiral. So it is possible to change the shape, size and the configuration of the tangential air inlet slots 119, 120 to vary arbitrarily, with which the swirl generator 100 without Changing its overall length is universally applicable.

The geometric configuration of FIG Baffles 121a, 121b. They have a flow initiation function which, according to their length, the respective End of the tapered body 101, 102 in the direction of flow extend towards the combustion air 115. The Channeling the combustion air 115 into the cone cavity 114 can by opening or closing the guide plates 121a, 121b by one in the area of the entry of this channel into the Cone cavity 114 placed pivot point 123 can be optimized, this is particularly necessary if the original gap size of the tangential air inlet slots 119, 120 dynamic should be changed. Of course you can dynamic arrangements can also be provided statically by required guide plates with a fixed component form the tapered partial bodies 101, 102. The can also Swirl generator 100 can also be operated without baffles, or other aids can be provided for this.

4 shows that the swirl generator 100 now made up of four partial bodies 130, 131, 132, 133 is. The associated longitudinal symmetry axes for each partial body are marked with the letter a. About this configuration can be said that due to the generated lower twist strength and in cooperation with one suitably suitably enlarged slot width, the bursting of the vortex flow on the downstream side of the To prevent swirl generator in the mixing tube, making the mixing tube can best fulfill the role intended for him.

Fig. 5 differs from Fig. 4 insofar as here the partial bodies 140, 141, 142, 143 have a blade profile shape, which is intended to provide a certain flow becomes. Otherwise, the mode of operation of the swirl generator stayed the same. The admixture of fuel 116 in the combustion air flow 115 happens from the inside the blade profiles, i.e. the fuel line 108 is now integrated in the individual blades. Also here are the longitudinal axes of symmetry to the individual partial bodies marked with the letter a.

6 shows the transition piece 200 in a three-dimensional view. The transition geometry is for a swirl generator 100 with four partial bodies, corresponding to FIG. 4 or 5, built up. Accordingly, the transition geometry points as natural extension of the upstream parts four transition channels 201, creating the conical quarter area the partial body mentioned is extended until it hits the wall of the tube 20 respectively. of the mixing tube 220 cuts. The same Considerations also apply when the swirl generator is off another principle than that described under Fig. 2, is constructed. The one running downward in the direction of flow The surface of the individual transition channels 201 has an in Flow direction spiral shape, which describes a crescent shape, corresponding to the The fact that the flow cross section of the Transition piece 200 flared in the direction of flow. The swirl angle of the transition channels 201 in the flow direction is selected so that the pipe flow then up to Cross-sectional jump 70 at the entrance to the combustion chamber is still sufficient large distance remains to make a perfect premix with the injected fuel. Further increases the axial speed due to the above-mentioned measures on the mixing tube wall downstream of the swirl generator. The transition geometry and the measures in the area of the mixing tube cause a significant increase in the axial speed profile towards the center of the mixing tube, so that the danger of early ignition is decisively counteracted becomes.

Fig. 7 shows the tear-off edge already mentioned, which on Burner outlet is formed. The flow cross section of the Tube 20 is given a transition radius R in this area, whose size basically depends on the flow within the Tube 20 depends. This radius R is chosen so that the flow applies to the wall and so the swirl number strong can rise. The size of the radius can be quantified Define R so that it is> 10% of the inner diameter d of the tube is 20. Opposite a flow without a radius Now the backflow bladder 50 increases enormously. This Radius R extends to the exit plane of the tube 20, wherein the angle β between the beginning and end of the curvature is <90 °. The runs along one leg of the angle β Tear-off edge A into the interior of the tube 20 and thus forms one Tear-off level S opposite the front point of the tear-off edge A, whose depth is> 3 mm. Of course, here Edge running parallel to the exit plane of the tube 20 a curved course again at the exit level to be brought. The angle β 'that is between tangent the trailing edge A and perpendicular to the exit plane of the Tube 20 spreads, is the same size as angle β. On the Advantages of this training is already under the chapter "Representation of the invention" discussed in more detail.

LIST OF REFERENCE NUMBERS

10

Buchenring

20

Mixing tube, mixing section

21

Holes, openings

30

combustion chamber

31

mixture nozzle

40

Flow, pipe flow in the mixing pipe

50

Backflow zone, backflow bubble

60

Brenner

70

Jump in cross section

80

front wall

100

swirl generator

101

102 partial body

101a, 102b

Cylindrical starting parts

101b, 102b

Longitudinal axes of symmetry

103

fuel nozzle

104

fuel injection

105

Fuel spray (fuel injection profile)

108

109 fuel lines

112

Liquid fuel

113

Gaseous fuel

114

conical cavity

115

Combustion air (combustion air flow)

115a

Part of combustion air

116

Fuel injection from lines 108, 109

117

fuel nozzles

119

120 Tangential air inlet slots

121a,

121b baffles

123

Pivot point of the guide plates

130

131, 132, 133 partial body

131a,

131a, 132a, 133a longitudinal axes of symmetry

140

141, 142, 143 vane-shaped partial body

140a,

141a, 142a, 143a axes of longitudinal symmetry

200

Transition piece

201

Transition passages

220

mixing tube

300

Mixing element, pilot stage

301

fuel line

303

fuel

304

Mixture of 115a and 303

d

Inner diameter of the tube 20

R

Transition radius

T

Tangent line of the tear-off edge

A

tear-off edge

S

breakaway step

β

Transition angle from R

β '

Angle between T and A

Claims (14)

1. Burner for a heat generator, consisting essentially

   of a swirl generator (100) for combustion air (115),

   of means (170) for injecting at least one fuel (116) into the combustion air (115),

   of a mixing section (220), which is in effective connection to the swirl generator (100) and are [sic] arranged upstream of a combustion chamber (30), and

   a number of mixing elements (300) are arranged in the region of the transition characterized by a cross-sectional step (70) between swirl generator and mixing section (100, 220) and combustion chamber (30) concentric or quasi-concentric to the mixing section, in which mixing elements (300), a mixture formation takes place between a proportion of combustion air (115a) and a fuel (303), and that [sic] the mixing elements are in effective connection with the mixing section pilot stages of the combustion chamber [sic] and

   the mixing section (220) is arranged downstream of the swirl generator (100) as a mixing tube (20),

   characterized in that the mixing tube (20) is provided with a separation edge (A) in the region of the outlet into the combustion chamber (30) to stabilize and increase a reverse flow zone (50) forming downstream.
2. Burner according to Claim 1, characterized in that the separation edge (A) consists of a transition radius (R) in the region of the outlet from the mixing tube (20) and a separation step (S) set back from the outlet from the mixing tube.
3. Burner according to Claim 2, characterized in that the transition radius (R) is greater than 10% of the internal diameter of the mixing tube (20), and in that the separation step (S) has a depth greater than 3 mm.
4. Burner according to one of Claims 1 to 3, characterized in that the mixing tube (20) has transition ducts (201), which extend in the flow direction within a first section part (200), for transferring a flow (40) formed in the swirl generator (100).
5. Burner according to Claim 4, characterized in that the number of transition ducts (201) in the mixing section (220) corresponds to the number of the partial flows formed by the swirl generator (100).
6. Burner according to Claim 4, characterized in that the mixing tube (20) connected downstream of the transition ducts (201) is provided, in the flow direction and peripheral direction, with openings (21) for injecting an air flow to within the mixing tube (20).
7. Burner according to Claim 6, characterized in that the openings (21) extend at an acute angle relative to the burner centre line (60) of the mixing tube (20).
8. Burner according to Claim 4, characterized in that the flow cross section of the mixing tube (20), downstream of the transition ducts (201), is smaller, of the same size, or larger than the cross section of the flow (40) formed in the swirl generator (100).
9. Burner according to Claim 1, characterized in that a diffuser and/or a venturi section is provided upstream of the cross-sectional step (70).
10. Burner according to Claim 1, characterized in that the swirl generator (100) consists of at least two hollow, conical partial bodies (101, 102; 130, 131, 132, 133; 140, 141, 142, 143) nestled into one another in the flow direction, in that the respective axes of longitudinal symmetry (101b, 102b; 130a, 131a, 132a, 133a; 140a, 141a, 142a, 143a) of these partial bodies extend offset relative to one another in such a way that the adjacent walls of the partial bodies form, in their longitudinal extent, tangential ducts (119, 120) for a combustion air flow (115), and in that at least one fuel nozzle (103) is arranged in the conical hollow space (114) formed by the partial bodies.
11. Burner according to Claim 10, characterized in that further fuel nozzles (117) are arranged in the region of the tangential ducts (119, 120) in their longitudinal extent.
12. Burner according to Claim 10, characterized in that the partial bodies (140, 141, 142, 143) have a vane-shaped profiling in cross section.
13. Burner according to Claim 10, characterized in that the partial bodies have a fixed conical angle in the flow direction, or an increasing conical inclination, or a decreasing conical inclination.
14. Burner according to Claim 10, characterized in that the partial bodies are nestled into one another in spiral shape.

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