EP0783089B1 - Cone-shaped burner - Google Patents

Description

Technical field

The invention relates to a cone burner for gaseous and / or liquid fuels, according to the preamble of the claim 1.

State of the art

EP-B1-0321809 discloses a gas for combustion and / or liquid fuels suitable double cone burners known. This burner consists of two hollow, one into one Partial conical bodies which are tangential Have air inlet slots. At the radial end of each air inlet slot is a line for gaseous fuel arranged. Mixing the gaseous fuel into the combustion air flowing in tangentially therefore takes place within the air inlet slots, and that in the entire interior of the burner. When using liquid fuel this via a centrally arranged nozzle into the interior of the burner injected.

At the burner end of such a double-cone burner, Formation of a central return flow zone of the fuel mixture. In this area there is already a homogeneous one over time Fuel profile reached across the burner cross section. The ignition of the fuel mixture takes place at the top of the Backflow zone, so that there is a stable flame front. Due to the sudden expansion of the area to the combustion chamber an outer recirculation area also forms, which also contributes to flame stabilization.

When using liquid fuel, the fuel concentration through the tangentially introduced combustion air degraded in the axial direction so that a well premixed Firing mixture is created. However, it becomes more gaseous Used fuel, the distance is at least from the Mixing points arranged in the downstream area of the burner of the fuel to the flame only very little. That is why the present there still leads in terms of time and location not completely homogenized fuel mixture to an increased Production of nitrogen oxides and carbon monoxide.

Presentation of the invention

The invention tries to avoid all of these disadvantages. It is based on the task of a cone burner for gaseous and / or to create liquid fuels, the one has reduced NOx and CO emissions.

According to the invention, this is achieved in that Device according to the preamble of claim 1, the partial cone body a common one at its downstream end Have outlet diffuser. The partial cone bodies have one Transition area to the outlet diffuser, in which the size of the air inlet slots continuously in the direction of flow decreases. The outlet diffuser is circular and has no air inlet slots educated.

Due to this design of the cone burner is suitable Choice of the slot width, the vortex bursting and thus the ignition of the fuel mixture further downstream, in the vicinity of the outlet diffuser end. This will be the end of the burner available mixing distance and mixing time essential extended. This creates a better homogenized Fuel mixture, which leads to a significant reduction in NOx and CO emissions. This affects both Use of liquid as well as gaseous fuel, the advantage of the latter being significantly greater. With the continuous reduction in the size of the air inlet slots there are sudden cross-sectional jumps in the transition area from the cone burner geometry to the circular one Outlet diffuser prevented. In this way, transfer areas can be the flow of the fresh fuel mixture and thus avoid undesired flame control there. The cone burner now has a circular exit cross-section to the combustion chamber, which is compared to the known double-cone burners the cooling air requirement for those used there Sickles are eliminated. The outlet diffuser provides an additional advantage a stronger shielding of the reaction zone the neighboring burners, resulting in increased flame stability is achieved.

It is particularly useful if the Partial cone body to the outlet diffuser the diameter of the Fuel supply decreases in the direction of flow. In order to is the gas perforation in the transition area according to the local slot width adjusted and an even distribution of the gaseous fuel in the combustion air.

It is also advantageous if the outlet diffuser has a length from about 10 to 25 percent of the total length of the cone burner has and has an exit surface which is not greater than 1.3 times one at the beginning of the transition area formed cross-sectional area of the partial cone bodies formed double cone part. Such, relative short diffuser results in a small boundary layer thickness, preventing the flame from kicking back in the boundary layer becomes.

In a second embodiment, the outlet diffuser has an opening angle that increases continuously in the direction of flow, which is initially equal to the cone angle of the burner and downstream continuously larger than this is. This stabilizes the wall boundary layer and thus minimizing the risk of flow separation.

Brief description of the drawing

In the drawing are two embodiments of the invention using a double-cone burner connected to a combustion chamber shown.

Fig. 1

einen Doppelkegelbrenner des Standes der Technik, perspektivisch und entsprechend aufgeschnitten dargestellt;

Fig. 2

einen Schnitt II-II durch den in Fig. 1 gezeigten Brenner, schematisch vereinfacht dargestellt;

Fig. 3

eine schematische Darstellung eines erfindungsgemässen Doppelkegelbrenners in Seitenansicht;

Fig. 4

einen Ausschnitt von Fig. 3 mit vergrösserter Darstellung des Übergangsbereiches zum Auslassdiffusor;

Fig. 5 bis Fig. 7

Teilquerschnitte des Übergangsbereiches, entlang der Linien V-V, VI-VI, VII-VII in Fig. 4;

Fig. 8

eine Darstellung entsprechend Fig. 3, jedoch in einer anderen Ausführungsform.

Show it:

Fig. 1

a double-cone burner of the prior art, shown in perspective and cut accordingly;

Fig. 2

a section II-II through the burner shown in Figure 1, shown schematically simplified.

Fig. 3

a schematic representation of a double-cone burner according to the invention in side view;

Fig. 4

a detail of Figure 3 with an enlarged view of the transition area to the outlet diffuser.

5 to 7

Partial cross sections of the transition area, along the lines VV, VI-VI, VII-VII in Fig. 4;

Fig. 8

a representation corresponding to FIG. 3, but in another embodiment.

It is only essential for understanding the invention Elements shown. The flow direction of the work equipment is marked with arrows.

Way of carrying out the invention

FIG. 1 shows one known from the prior art Double cone burner shown. It consists of two halves, hollow partial cone bodies 1, 2 which are laterally offset from one another, lie on top of each other and complement each other to form a body. Therefore, the partial cone bodies 1, 2 have in the flow direction 3 offset central axes 4, 5 (Fig. 2). The double-cone burner points in the direction of flow 3 conical burner interior 6. Between the partial cone bodies 1, 2 are tangential air inlet slots 7, 8 formed.

On both partial cone bodies 1, 2 and there at the outer end of the Air inlet slots 7, 8 are each a fuel line 9, 10 arranged for gaseous fuel 11 (Fig. 1). The Fuel lines 9, 10 are with several, in the entire area of the air inlet slots 7, 8 evenly distributed and fuel feeds formed as openings 12 are provided. Both partial cone bodies 1, 2 each have a cylindrical one Initial part 13, 14, which are also offset from one another are arranged. Thus the tangential air inlet slots 7, 8 upstream over the entire length of the double cone burner. At the upstream end the double cone burner, i.e. in its cylindrical beginning 13, 14, is an opening into the burner interior 6, central liquid fuel nozzle 15 arranged. Both Partial cone bodies 1, 2 have a flat, in the range of 10 ° up to 30 ° trained cone angle 16. Combustion chamber side 17 is a collar-shaped on the double-cone burner, as anchoring for the partial cone body 1, 2 serving end plate 18th arranged. In the end plate 18 is a number of Bores 19 formed through which cooling air 20 for the Immediately upstream of the end plate 18, crescent-shaped Ends of the partial cone bodies 1, 2 to the combustion chamber 17 is derived.

When liquid fuel 21 is used, its injection takes place at an acute angle, at the narrowest cross section of the burner interior 6. This forms a conical fuel profile 22, which is surrounded by rotating combustion air 23 flowing in via the tangential air inlet slots 7, 8. In the axial direction, the concentration of the liquid fuel 21 is continuously reduced by the mixed-in combustion air 23. At the downstream end of the double-cone burner, a central backflow zone 24 of the fuel mixture is formed, which causes the conical fuel profile 22 to burst (vortex breakdown). As a result, a good fuel concentration over the burner cross section is achieved in this area. The combustion mixture is ignited at the top of the reverse flow zone 24. Only at this point can a stable flame front 25 arise.
If gaseous fuel 11 is burned, it passes through the openings 12 into the burner interior 6, where it is mixed with the combustion air 23. A conical fuel profile 22 is also formed in the burner interior 6.

3 shows a schematic representation of a device according to the invention Double cone burner. For the sake of clarity are only the essential components or the opposite the prior art shown in FIGS. 1 and 2 changed Components shown.

The two half, hollow partial cone bodies 1, 2 of the burner complement each other to form a body designed as a double cone part 26, which downstream in a common, circular Outlet diffuser 27 merges. Immediately upstream of the outlet diffuser 27 is a transition region 28 from the double cone part 26 to the outlet diffuser 27. In this transition area 28 takes the size of the air inlet slots 7, 8 continuously in the direction of flow 3. However, it will the burner cross section is continuously expanded, making the Area through which the fuel mixture flows also in the transition area 28 becomes larger or at least remains constant.

The outlet diffuser 27 has a length 29 of approximately 15 percent the total length 30 of the double-burner. Its exit surface 31 corresponds to approximately 1.3 times the cross-sectional area 32 at the beginning of the transition area 28. He owns an opening angle 33 which is initially equal to the cone angle 16 of the burner and in the flow direction 3 continuously increases.

The transition region 28 to the outlet diffuser 27 is shown in FIG shown enlarged, whereby the arrangement and design of the ending at the downstream end of the transition region 28 Fuel line 9 become clear.

Figures 5 to 7 show three partial cross sections of the double cone part 26 in its transition region 28. In Fig. 5 is the beginning, in Fig. 6 the middle part and in Fig. 7 the end of the transition area 28 shown. In the transition area 28 becomes the diameter of the fuel line 9 and the openings 12 reduced in the direction of flow 3. Already at the end of the transition area 28 are the air inlet slots 7, 8 and the openings 12 are completely closed. At downstream adjoining circular outlet diffuser 27 neither air inlet slots 7, 8 nor fuel lines 9, 10 arranged (Fig. 3).

In contrast to the function of a known double cone burner is by the arrangement of the Outlet diffuser 27 additional time and space for the interference also in the downstream area of the double cone part 26 imported gaseous fuel 11 won. In this way, an optimal fuel concentration reached over the burner cross section. When burned of such a homogenized fuel mixture, the NOx and significantly reduced CO emissions. Even when used of liquid fuel 21 will reduce emissions achieved, but the advantage is not in this case so big.

The flow of the fuel mixture is in the outlet diffuser 27 slightly delayed and therefore unstable at its center. Thereby it only comes close to the downstream end of the outlet diffuser 27 to form the central backflow zone 24 of the fuel mixture and thus to burst the conical Fuel profile 22. Because the outlet diffuser 27 is trumpet-shaped is formed, there is a constant surface course from transition area 28 to the entry of the fuel mixture reached in the combustion chamber 17. As a result, the boundary layer resolves does not decrease in its interior, so that is advantageous a stable flame front only downstream of the double-cone burner 25 can train. By changing the length of the double cone part 26, the slot width, the opening angle 33 or the number of air inlet slots 7, 8 can be the location the vortex burst according to the specific conditions to be influenced.

Because of the transition region 28 from the double cone part 26 to Outlet diffuser 27 continuously reduced in size Air inlet slots 7, 8 become a fluid transition from the double-cone burner geometry to the circular one Outlet diffuser 27 reached. This makes sudden cross-sectional jumps avoided. The adjustment of the gas perforation the local size of the air inlet slots 7, 8 takes place through the corresponding reduction in the opening diameter. Naturally the distance between the openings 12 can also be increased become. An additional advantage of the trumpet-shaped trained outlet diffuser 27 is the stabilizing one Effect of its convex curved wall.

In a second embodiment, the outlet diffuser has 27 an opening angle 34, which is equal to the cone angle 16 of the burner is formed (Fig. 8). Because of the simple, Straight shape of the outlet diffuser 27 can this double cone burner manufactured much lighter and cheaper become. In addition, a cooling air baffle is outside the combustion chamber wall 35 36 arranged, which is upstream to the outlet diffuser 27 is sufficient and at the downstream end of the air inlet slots 7, 8 ends. The outlet diffuser 27 is with in the space between combustion chamber wall 35 and cooling air baffle 36 back-flowing cooling air cooled from the outside, the latter finally in a plenum formed upstream of the burner 37 opens. Because of this convective cooling of the outlet diffuser 27, the operational security compared to first embodiment further improved.

Reference list

1

Partial cone body

2nd

Partial cone body

3rd

Flow direction

4th

Central axis

5

Central axis

6

Burner interior

7

Air inlet slot

8th

Air inlet slot

9

Fuel line

10th

Fuel line

11

gaseous fuel

12th

Fuel supply, opening

13

Initial part

14

Initial part

15

Liquid fuel nozzle

16

Cone angle

17th

Combustion chamber

18th

End plate

19th

drilling

20th

Cooling air

21

liquid fuel

22

tapered fuel profile

23

Combustion air

24th

Backflow zone

25th

Flame front

26

Body, double cone part

27

Outlet diffuser

28

Transition area

29

Length of 27

30th

Total length of 26 and 27

31

Exit area of 27

32

Cross sectional area

33

Opening angle of 27

34

Opening angle of 27

35

Combustion chamber wall

36

Cooling air baffle

37

plenum

Claims (5)

1. Cone burner for gaseous and/or liquid fuels (11, 21), consisting of

   a) at least two hollow sectional cone bodies (1, 2) which complement one another to form one body (26) and whose centre axes (4, 5) are arranged offset from one another in the direction (3) of flow,

   b) tangential air-inlet slots (7, 8) arranged between the sectional cone bodies (1, 2),

   c) a plurality of fuel feeds (12), uniformly distributed in the entire region of the air-inlet slots (7, 8), for gaseous fuel (11),

   d) a burner interior space (6) widening conically in the direction (3) of flow,

   e) a central liquid-fuel nozzle (15) arranged at the upstream end of the cone burner and leading into the burner interior space (6),

   characterized in that

   f) the sectional cone bodies (1, 2) have a common outlet diffuser (27) at their downstream end,

   g) the sectional cone bodies (1, 2) have a transition region (28) to the outlet diffuser (27), in which the size of the air-inlet slots (7, 8) decreases continuously in the direction (3) of flow,

   h) the outlet diffuser (27) is designed to be circular and without air-inlet slots (7, 8).
2. Cone burner according to Claim 1, characterized in that the diameter of the fuel feeds (12) decreases in the direction (3) of flow in the transition region (28) of the sectional cone bodies (1, 2).
3. Cone burner according to Claim 2, characterized in that the outlet diffuser (27) has a length (29) of about 10 to 25 per cent of the overall length (30) of the cone burner and has an outlet area (31) which is not greater than 1.3 times a cross-sectional area (32), formed at the start of the transition region (28), of the body (26).
4. Cone burner according to Claim 3, characterized in that the outlet diffuser (27) has an opening angle (34) which is equal to the cone angle (16) of the burner.
5. Cone burner according to Claim 3, characterized in that the outlet diffuser (27) has an opening angle (33) which is initially equal to the cone angle (16) of the burner and increases continuously in the direction (3) of flow.

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