EP2423599B1 - Method for operating a burner arrangement and burner arrangement for implementing the method - Google Patents

Description

TECHNICAL AREA

The present invention relates to the field of burner technology, in particular gas turbines. It relates to methods for operating a burner assembly according to the preamble of claim 1. It further relates to a burner assembly for carrying out the method.

STATE OF THE ART

For some time gas turbines with so-called sequential combustion are known in the art, in which the combustion gases from a first combustion chamber to work performance in a first turbine to a second combustion chamber to be led, where using the in the combustion gases contained combustion air, a second combustion takes place, and the reheated gases are fed to a second turbine.

For this second combustion so-called SEV burners are used in the applicant, which are described, for example, in the article " Field experience with the sequential combustion system of the GT24 / GT26 gas turbine family ", ABB Review 5, 1998, pp. 12-20 , or in the publication EP 2 169 314 A2 (see the local there Fig. 1 ) to be discribed.

Such a SEV burner is schematically in the Fig. 1 shown: The SEV burner 10 of Fig. 1 includes a mixing space 12 extending in a flow direction (see the elongated arrows). Upstream of the mixing chamber 12 is an inlet 11, can enter through the combustion gases 18 from the first (not shown) combustion chamber to relax in the first (not shown) turbine in the mixing chamber 12. Downstream of the mixing chamber 12 is followed by a combustion chamber 13, in which a burner flame with a corresponding flame boundary 17 is formed during operation. The mixing space 12 is bounded outwardly by a burner wall 15 having a plurality of effusion holes 16. Into the mixing chamber 12 projects an angled fuel lance 14, from which a fuel 19 is injected into the mixing chamber 12.

Contrary to the direction of flow of the combustion gases 18 in the mixing chamber 12 outside cooling air 20 is supplied, which enters through the effusion holes 16 in the burner wall 15 into the mixing chamber 12 and effusion cooling causes (see Fig. 2 ). By supplying the cooling air along the burner wall 15, this is convectively cooled. As already mentioned in the publication EP 2 169 314 A2 has been carried out, there is a desire in such SEV burners to improve the cooling and suppress the flashback even more so that the sequential burner can be operated at even higher hot gas temperatures and with highly reactive fuels.

In conventional burners of gas turbines has been proposed (see the document US 7,493,767 B2 ; 8 and 9), in the impingement cooling of transition pieces, to alter and influence the distribution of cooling air across the impingement cooling plate by providing certain holes in the sheet with so-called "flow trapping elements" or "scoops" to locally higher mass flows To provide cooling air. Since, in this case, because of the lack of effusion cooling, the cooling air does not enter the mixing chamber directly through the burner wall but is guided along the outside of the burner wall, no consideration has to be given to the interaction of the flow in the mixing chamber with cooling air flowing in through the burner wall.

In the case of a SEV burner, however, there is a close relationship between the distribution of the incoming diffusion cooling air and the flow conditions in the mixing chamber or in the combustion chamber following behind.

From the EP 0 918 190 A1 and the EP 2 169 314 A2 burner assemblies are known with effusion cooled burner walls. The EP 0 918 190 A1 further discloses an annular space which guides the cooling air outside the burner along the burner wall.

The JP 58 072822 A shows an effusion cooled burner wall in which each effusion hole has a cylindrical extension.

From the US 2006/059916 A1 Furthermore, an effusion cooling is known in which a perforated plate is connected upstream of the combustion chamber wall.

PRESENTATION OF THE INVENTION

It is an object of the invention to improve the aforementioned method for operating a burner assembly so that higher combustion temperatures are achieved or highly reactive fuels can be used, and to provide a burner assembly for performing the method.

The object is achieved by the method of claim 1 and by the burner assembly of claim 9. Essential for the invention is that the cooling air is deflected targeted on the outside of the burner wall in its flow direction by distributed deflecting elements. As a result, effusion cooling can, so to speak, be "tailored" to enhance its effect in the most critical areas of the burner. The use of the deflection allows a greatly improved adjustment of the direction of injected effusion cooling air. As a result, the flow conditions are optimized within the mixing chamber, which - especially with regard to the stability of combustion in particularly reactive fuels - the reliability benefits.

The deflection allow in their area a more concentrated effusion cooling of the burner. Preferably, the deflecting elements are mounted directly on the outer surface of the burner wall. In particular, they have the shape of a halved ball half shell and resemble an orchestra shell. The height and width of the semicircular opening of the deflecting elements can be varied as a function of the diameter and spacing of the effusion holes covered therewith. The number and placement of the deflectors depend on the shape of the burner. The orientation of the baffles (that is, the orientation of their openings) can be chosen so that the maximum cooling air flow is directed into the effusion holes. The deflecting elements can either be manufactured and fastened individually or together in the form of a correspondingly punched and / or embossed sheet metal. The deflecting elements may be welded or cast on the burner wall. However, the number and diameter of the effusion holes can also be adapted to the positions of the deflection elements.

An embodiment of the method according to the invention is characterized in that the cooling air is deflected by a deflection in each case in one of the effusion holes.

Another embodiment of the method according to the invention is characterized in that the cooling air is deflected by a deflecting element in each case in several effusion holes.

Another embodiment of the method according to the invention is characterized in that the effusion holes are inclined with their axes relative to the burner wall, and that the cooling air is deflected by the deflecting elements such that it flows on entry into the effusion holes substantially parallel to the axes of the effusion holes.

A further embodiment of the method according to the invention is characterized in that the effusion holes are inclined with their axes relative to the burner wall, and that the cooling air is deflected by the deflecting elements such that it flows substantially perpendicular to the burner wall when entering the effusion holes.

Another embodiment of the method according to the invention is characterized in that a perforated plate with holes is arranged on the outside of the burner wall and at a distance from the burner wall, and that the cooling air is introduced on the side facing away from the burner wall of the perforated plate and by the deflection into the holes of the perforated plate is deflected and flows to the burner wall.

Yet another embodiment of the method according to the invention is characterized in that spoon-like shells are used as deflecting elements which shield the associated effusion holes from one side and are open in the direction of the approaching cooling air.

An embodiment of the burner assembly according to the invention is characterized in that in each case a deflecting element is associated with one of the effusion holes.

Another embodiment of the burner assembly according to the invention is characterized in that a deflecting element is assigned in each case to a plurality of effusion holes.

Another embodiment of the burner assembly according to the invention is characterized in that the effusion holes are inclined with their axes relative to the burner wall, and that the deflection elements are designed such that the cooling air flows in the entry into the effusion holes substantially parallel to the axes of the effusion holes.

Another embodiment of the burner assembly according to the invention is characterized in that the effusion holes are inclined with their axes relative to the burner wall, and that the deflection elements are formed such that the cooling air flows when entering the effusion holes substantially perpendicular to the burner wall.

A further embodiment of the burner arrangement according to the invention is characterized in that a perforated plate with holes is arranged on the outside of the burner wall and at a distance from the burner wall, and that the deflecting elements are arranged on the side facing away from the burner wall of the perforated plate such that cooling air through the deflecting elements in the holes of the perforated plate is deflected and flows to the burner wall.

Yet another embodiment of the burner assembly according to the invention is characterized in that the deflecting elements are designed as spoon-like shells which shield the associated effusion holes from one side and are open in the direction of the approaching cooling air.

Yet another embodiment of the burner assembly according to the invention is characterized in that the deflecting elements are applied to the outer surface of the burner wall or the perforated plate.

BRIEF EXPLANATION OF THE FIGURES

Fig. 1

in einer vereinfachten Darstellung den Aufbau eines SEV-Brenners, wie er zur Ausführung der Erfindung geeignet ist;

Fig. 2

den Schnitt durch die Brennerwand eines SEV-Brenners mit Effusionskühlung gemäß Fig. 1, wobei die Effusionslöcher gegen die Brennerwand geneigt sind;

Fig. 3

in perspektivischer Darstellung einen Ausschnitt aus einer Brennerwand, die gemäß einem Ausführungsbeispiel der Erfindung mit einem Umlenkelement ausgestattet ist, welches die Kühlluft in mehrere Effusionslöcher gleichzeitig umgelenkt;

Fig. 4

in perspektivischer Darstellung einen Ausschnitt aus einer Brennerwand, die gemäß einem anderen Ausführungsbeispiel der Erfindung mit einem Umlenkelement ausgestattet ist, welches die Kühlluft in nur ein Effusionsloch umgelenkt;

Fig. 5

eine zu Fig. 2 vergleichbare Brennerwand, die gemäß einem anderen Ausführungsbeispiel der Erfindung mit Umlenkelementen einer ersten Art ausgestattet ist;

Fig. 6

eine zu Fig. 2 vergleichbare Brennerwand, die gemäß einem anderen Ausführungsbeispiel der Erfindung mit Umlenkelementen einer zweiten Art ausgestattet ist; und

Fig. 7

eine zu Fig. 2 vergleichbare Brennerwand, die gemäß einem weiteren Ausführungsbeispiel der Erfindung von einem Lochblech mit Umlenkelementen im Abstand umgeben ist.

The invention will be explained in more detail with reference to embodiments in conjunction with the drawings. Show it

Fig. 1

in a simplified representation of the structure of a SEV burner, as it is suitable for carrying out the invention;

Fig. 2

the section through the burner wall of a SEV burner with effusion cooling according to Fig. 1 wherein the effusion holes are inclined against the burner wall;

Fig. 3

in a perspective view a section of a burner wall, according to an embodiment of the Invention is equipped with a deflecting element which deflects the cooling air into several effusion holes simultaneously;

Fig. 4

in perspective view a section of a burner wall, which is equipped according to another embodiment of the invention with a deflecting element, which deflects the cooling air into only one effusion hole;

Fig. 5

one too Fig. 2 comparable burner wall, which is equipped according to another embodiment of the invention with deflection of a first type;

Fig. 6

one too Fig. 2 comparable burner wall, which is equipped according to another embodiment of the invention with deflection of a second type; and

Fig. 7

one too Fig. 2 Comparable burner wall, which is surrounded according to a further embodiment of the invention by a perforated plate with deflecting elements in the distance.

WAYS FOR CARRYING OUT THE INVENTION

The invention gives the possibility of the effusion cooling of the burner Fig. 1 "tailor" or optimize in order to increase their impact in the most critical areas of the burner (the particularly hot areas). This happens because aerodynamically shaped deflecting elements (21 in FIG. 3 and FIG. 4 ) are arranged on the cold or outer side of the burner wall 15. The presence of this spoon-like, designed in the manner of a half-spherical half-deflection elements 21 makes it possible to adjust the direction of the injected effusion cooling air according to the particular needs.

Further, in regions where the flow velocity of the cooling air on the outer side of the burner wall 15 and the static pressure due to the high flow velocity are reduced, the diverting elements 21 allow the flow to accumulate and convert at least part of the dynamic pressure into static pressure. The deflecting elements 21 thus allow the feed pressure for the effusion cooling to be raised and adjusted.

Fig. 3 shows a small section of the burner wall 15 with a plurality of distributed therein effusion holes 16, by the according Fig. 1 Cooling air flows into the mixing chamber 12. Fig. 3 further shows a single deflecting element 21, which, representative of other deflecting elements, not shown, several of the effusion holes 16 so covered that in the direction of the arrow on the burner wall 15 along the cooling air flow 20 captured and deflected in the direction of the effusion holes 16. Over the entire burner wall 15, many such deflecting elements 21 may be arranged in different density and orientation, in order to deflect the cooling air 20 in an optimum manner.

Of course, in the context of the invention, the size of the deflection elements 21 can be changed relative to the diameters of the effusion holes 16. Fig. 4 shows a single arrangement of a deflecting element 21, which is associated with only a single effusion hole 16. As a result, the distribution of the deflected cooling air in the area can be divided even finer.

By choosing the size of the deflecting elements 21 relative to the diameters of the effusion holes 16, the function can be set as a deflecting element or as a stowage element for recovering the dynamic pressure.

In principle, the effusion holes 16 can be oriented with their hole axes perpendicular to the plane of the burner wall 10. In most cases, however, as in Fig. 2 shows the axes of the effusion holes 16 with respect to the plane of the Burner wall 15 inclined so that the inflowing through the effusion holes 16 cooling air has a velocity component parallel to the main flow in the mixing chamber 12 and increases the axial length and thus the cooling effect. The angle α, which includes the axis with the wall plane, may be in a range between 10 ° and 80 °, in particular between 20 ° and 50 °, preferably between 30 ° and 40 °. A particularly suitable value has been found to be an angle of 35 °.

In such inclined effusion holes 16, the deflecting elements 21, as in Fig. 5 shown, be shaped so that the deflected cooling air largely perpendicular to the burner wall 15 and thus meets the hole entrances. However, it can be more favorable in terms of flow technology, according to Fig. 6 adjust the curvature of the deflection elements 22 so that the deflected cooling air enters the effusion holes 16 practically in the direction of the hole axes.

Finally, it is also possible within the scope of the invention, according to Fig. 7 at a distance from the burner wall 15 outside a perforated plate 23 to be arranged, which is provided with corresponding holes 25, is deflected in the cooling air through the arranged on the perforated plate 23 deflecting 21, and then to traverse the gap 24 between the perforated plate 23 and burner wall 15 and in enter the effusion holes 16. By this arrangement, on the one hand, an additional impact cooling effect is achieved on the burner wall 15. On the other hand, the assignment of the diverted cooling air to the effusion holes is opposite to the configuration Fig. 5 and Fig. 6 indirect.

The effusion cooling described is not limited to the mixing chamber 12, but may also extend to the liner of the combustion chamber 13. In addition to the actual cooling, the effusion cooling in the liner has the task of avoiding the self-ignition of the air-fuel mixture. In addition to the cooling, the effusion cooling in the mixing chamber 12 or premixer has the task of avoiding the stagnation of combustion gases on the burner wall 15 by forming a boundary layer.

• Erhöhung des Kühlluftmassenstroms durch die kleinen Löcher (Umwandlung des dynamischen Drucks in statischen Druck)
• Verhinderung eines Flashbacks
• Auf der kalten Seite der Brennerwand 15 ausserdem die Funktion eines Wirbelgenerators (Turbulator).

The deflection elements 21, 22 thus fulfill the following tasks:

• Increasing the mass flow of cooling air through the small holes (conversion of the dynamic pressure into static pressure)
• Prevention of a flashback
• On the cold side of the burner wall 15 also the function of a vortex generator (turbulator).

In particular, the function of the vortex formation of the cooling air by the deflecting elements 21, 22 can be reinforced by the fact that the deflecting elements 21, 20 are mounted in a specific overall arrangement (graduation) in order to influence them in terms of flow. Thus, the convective cooling on the outside of the burner wall 15 is increased. For example, rows of deflection elements 21, 22 are arranged at right angles to the flow direction of the cooling air 22, wherein the deflection elements 21, 22 of two successive rows are each arranged offset from one another.

The deflection elements 21, 22 locally enhance the effusion cooling of the burner. If according to Fig. 7 a perforated plate 23 is used as an impingement cooling plate with deflecting elements, the heat transfer coefficient increases on the cold side of the burner wall 15. The deflecting elements 21, 22 are preferably arranged in the areas where the cooling air has a particularly high speed to more cooling air into the effusion holes 16th redirect.

Some areas of the effusion cooling are disadvantaged in that the speed of the cooling air is high there and only a low static pressure prevails. Some areas of effusion cooling need to be reinforced because the heat load on the hot gas side (because of a high heat transfer coefficient or a high flame temperature) is particularly high there. The deflection elements according to the invention catch cooling air through a combination of damming and diverting, which otherwise would have flowed past the effusion holes. In this way, the cooling can be local be reinforced without increasing the number of effusion holes or the diameter of the effusion holes increases the risk of cracking.

• die Form ist die einer halben Kugelhalbschale, wobei Höhe und Breite als Funktion von Durchmesser und Abstand der Effusionslöcher verändert werden können;
• die Anzahl und Platzierung der Umlenkelemente hängt von der Form des Brenners ab;
• die Ausrichtung der Umlenkelemente kann so gewählt werden, dass ein maximaler Kühlluftstrom in die Effusionslöcher eingebracht wird;
• Umlenkelemente überdecken entweder ein einzelnes Effusionsloch oder gleichzeitig mehrere Effusionslöcher;
• die Umlenkelemente können entweder einzeln hergestellt und angebracht werden, oder gleichzeitig in Form eines geprägten und/oder gestanzten Bleches;
• die Umlenkelemente können am Brenner angeschweisst oder angegossen sein;
• die Anzahl und der Durchmesser der Effusionslöcher kann in Abhängigkeit von der Platzierung der Umlenkelemente variiert werden.

The deflecting elements have the following overall characteristics:

• the shape is that of a half sphere half shell, wherein height and width can be changed as a function of diameter and distance of the effusion holes;
• the number and placement of the baffles depends on the shape of the burner;
• the orientation of the deflecting elements can be selected so that a maximum cooling air flow is introduced into the effusion holes;
• Deflection elements cover either a single effusion hole or simultaneously several effusion holes;
• the deflecting elements can either be manufactured and installed individually or at the same time in the form of an embossed and / or stamped sheet;
• the deflecting elements can be welded or cast on the burner;
• the number and the diameter of the effusion holes can be varied depending on the placement of the deflecting elements.

LIST OF REFERENCE NUMBERS

10

SEV burner (burner arrangement)

11

inlet

12

mixing room

13

combustion chamber

14

fuel lance

15

burner wall

16

effusion

17

flames border

18

combustion gas

19

fuel

20

cooling air

21.22

deflecting

23

perforated sheet

24

gap

25

hole

α

angle

Claims (15)

1. Method for operating a burner arrangement (10), in which burner arrangement a hot combustion gas (18) containing combustion air flows substantially parallel to a burner wall (15) through a mixing chamber (12) delimited by this burner wall (15) into a combustion chamber (13), and in the mixing chamber (12) is mixed with an injected fuel (19), wherein for effusion cooling, cooling air (20) flows from the outside of the burner wall (15) through effusion holes (16) in the burner wall (15) into the interior of the mixing chamber (12),
   characterised in that
   the cooling air (20) on the outside of the burner wall (15) is deflected in its flow direction by deflector elements (21, 22) in the direction towards the burner wall (15), that the cooling air (20) on the outside of the burner wall (15) has a speed component parallel to the burner wall (15), and
   that the static pressure of the cooling air (20) upstream of the deflector elements (21, 22) is increased in order to raise the supply pressure for the effusion cooling.
2. Method according to claim 1, characterised in that the cooling air (20) on the outside of the burner wall (15) has a speed component parallel to the burner wall (15), and that the cooling air (20) is deflected in the direction towards the burner wall (15).
3. Method according to claim 2, characterised in that the cooling air (20) is deflected by a deflector element (21, 22) into one of the effusion holes (16).
4. Method according to claim 2, characterised in that the cooling air (20) is deflected by a deflector element (21, 22) into a plurality of effusion holes (16).
5. Method according to claim 3 or 4, characterised in that the axes of the effusion holes (16) are tilted relative to the burner wall (15), and that the cooling air (20) is deflected by the deflector elements (22) such that on entry into the effusion holes (16), it flows substantially parallel to the axes of the effusion holes (16).
6. Method according to claim 3 or 4, characterised in that the axes of the effusion holes (16) are tilted relative to the burner wall (15), and that the cooling air (20) is deflected by the deflector elements (21) such that on entry into the effusion holes (16), it flows substantially perpendicular to the burner wall (15).
7. Method according to one of claims 1 or 2, characterised in that a perforated plate (23) with holes (25) is arranged on the outside of the burner wall (15) and spaced from the burner wall (15), and that the cooling air is guided onto the side of the perforated plate (23) facing away from the burner wall (15) and deflected by the deflector elements (21, 22) into the holes (25) of the perforated plate (23) and flows towards the burner wall (15).
8. Method according to one of claims 1 to 6, characterised in that as deflector elements (21, 22), spoon-shaped dishes are used which screen the associated effusion holes (16) on one side and are open in the direction of the inflowing cooling air (20).
9. Burner arrangement (10) for performance of the method according to any of claims 1 to 8, which burner arrangement (10) comprises a mixing chamber (12) which extends in a flow direction, is delimited on the outside by a burner wall (15) and which comprises upstream an inlet (11) for a hot combustion gas (18) containing combustion air, and adjoining which downstream is a combustion chamber (13), wherein a fuel lance (14) for injecting a fuel (19) protrudes into the mixing chamber (12) and the burner wall (15) is provided with effusion holes (16), through which the cooling air (20) guided onto the outside of the burner wall (15) can flow into the mixing chamber (12), characterised in that on the outside of the burner wall (15), deflector elements (21, 22) are arranged which deflect the inflowing cooling air (20) in the direction towards the burner wall (15) in order to raise the supply pressure for the effusion cooling.
10. Burner arrangement according to claim 9, characterised in that each deflector element (21, 22) is assigned to one effusion hole (16).
11. Burner arrangement according to claim 9, characterised in that each deflector element (21, 22) is assigned to a plurality of effusion holes (16).
12. Burner arrangement according to claim 10 or 11, characterised in that the axes of the effusion holes (16) are tilted relative to the burner wall (15), and that the deflector elements (22) are configured such that on entry into the effusion holes (16), the cooling air (20) flows substantially parallel to the axes of the effusion holes (16).
13. Burner arrangement according to claim 10 or 11, characterised in that the axes of the effusion holes (16) are tilted relative to the burner wall (15), and that the deflector elements (21) are configured such that on entry into the effusion holes (16), the cooling air (20) flows substantially perpendicular to the burner wall (15).
14. Burner arrangement according to claim 10 or 11, characterised in that a perforated plate (23) with holes (25) is arranged on the outside of the burner wall (15), and that the deflector elements (21) are arranged on the side of the perforated plate (23) facing away from the burner wall (15) such that cooling air (20) is deflected by the deflector elements (21) into the holes (25) of the perforated plate (23) and flows towards the burner wall (15).
15. Burner arrangement according to any of claims 9 to 13, characterised in that the deflector elements (21, 22) are configured as spoon-shaped dishes which screen the associated effusion holes (16) on one side and are open in the direction of the inflowing cooling air (20).

Images