EP2463583B1 - Gas turbine and method for reconditioning such a gas turbine - Google Patents

Description

TECHNICAL AREA

The present invention relates to the field of gas turbines. It relates to a gas turbine according to the preamble of claim 1. It further relates to a method for reconditioning such a gas turbine.

STATE OF THE ART

Fig. 13 shows in a highly simplified representation of a stationary gas turbine with sequential combustion, as known from the prior art. The illustrated gas turbine 10 includes a compressor 11 for compressing aspirated air, a first annular combustor 14 into which is mixed fuel injected with pre-mix type burners 13 supplied via a fuel supply 12. The resulting hot gas drives a first Turbine 15, and is then reheated by injecting a fuel from a second fuel supply 16 into a second combustion chamber 17, to then drive a second turbine 18.

Modern stationary gas turbines are usually designed with an annular combustion chamber, as in Fig. 1 is reproduced. In the local gas turbine 20 with annular combustion chamber 24 of the combustion chamber is limited by an outer side wall 25 and by an inner side wall 26. Also, the hot gas path 27 is divided in the combustion chamber 24 by an inlet and an exit plane. The entry level is characterized by a plurality of burners 21, 22 and one or more front segments 23. The burners 21, 22 are positioned in the front segments and sealed in the flow direction. The attachment of the front segments themselves as well as their sealing must meet the requirements of the combustion. The combustion chamber 24 is operated for a long time, with or without interruptions (start and stop cycles). Examples of arrangements of front panels and front segments are from the US5285632 , of the WO 96/04510 A1 or the DE 44 32 558 A1 known.

• Strapazierfähigkeit
• Dauerschwingfestigkeit
• Alterungsbeständigkeit
• Dauerhaftigkeit
• Rekonditionierbarkeit
• Einfache Montierbarkeit
• De- und Neumontagemöglichkeit bei geschlossener Brennkammer
• Geringe Kosten im Life-Cycle (Erst- und Rekonditionierungskosten)

The construction of the front segments is characterized by:

• durability
• Fatigue strength
• aging resistance
• durability
• Rekonditionierbarkeit
• Easy to assemble
• Dismantling and new installation option with closed combustion chamber
• Low costs in the life cycle (initial and reconditioning costs)

• Sie bestehen jeweils aus den Hauptkomponenten Frontblech und Kühlblech;
• Abdichten der komprimierten Brennerluft gegenüber dem Brennraum;
• gegenseitiges Abdichten zum anliegenden Frontsegment in Umfangsrichtung durch äussere Dichtungsstreifen;
• rotationssymmetrische Ausführung;
• kein Strukturteil, d.h. nicht selbsttragend; es wird auf der Frontplatte fixiert;
• weist versetzte Kühlluftlöcher im Kühlblech gegenüber dem Frontblech auf, d.h. die Kühlung des Bauteils basiert auf Prallkühlung; die Kühlluftlöcher sind geometrisch vorgegeben, sodass der Luftmassenstrom kontrolliert bleibt;
• weist Kühlluftlöcher in der Seitenwand des Frontblechs auf, um das Einströmen von Heissgas zu den äusseren Dichtungsstreifen zu vermeiden; dies ist ein sogenanntes "Sidewall-Purging";
• weist einen Bewegungsspielraum in axialer sowie radialer Richtung auf, um durch die thermischen Ausdehnungen der Brennkammer, Spannungen zu minimieren;
• muss temperaturresistent sein und somit eine gewisse Zeit- bzw. Dauerfestigkeit aufweisen;
• muss möglichst einfach und kostengünstig herstellbar sein.

The front segments have the following features and functions:

• They consist of the main components front plate and cooling plate;
• Sealing the compressed burner air from the combustion chamber;
• mutual sealing to the adjacent front segment in the circumferential direction by outer sealing strips;
• rotationally symmetrical design;
• no structural part, ie not self-supporting; it is fixed on the front panel;
• has staggered cooling air holes in the heatsink with respect to the front panel, ie the cooling of the component is based on impingement cooling; the cooling air holes are geometrically predetermined so that the air mass flow remains controlled;
• has cooling air holes in the side wall of the front panel to prevent the inflow of hot gas to the outer sealing strip; this is a so-called sidewall purging;
• has a range of motion in the axial and radial directions in order to minimize stresses due to the thermal expansion of the combustion chamber;
• must be temperature resistant and thus have a certain time or fatigue strength;
• must be as simple and inexpensive to produce.

The front segments should be mounted in advance on the front panel. This module is then delivered as a "front panel complete" to the installation site.

When reconditioning the front segments, the outer sealing strips are replaced. In the previous design, these seals are installed between the heat sink and the front panel. That is, to replace the seals, you must first cut away all fasteners of the cooling plate, bend all hooks and upper and lower edges and remove the cooling plate. Only then can the new seal be installed.

These gaskets are also already installed before they reach the coating supplier for the TBC coating on the front panel. This has the negative effect that the seals are exposed to the sandblasting and then have to be covered extra for coating.

In addition, resulting from the pinching of the outer sealing strips in operation large plastic deformation of these sealing strips.

PRESENTATION OF THE INVENTION

It is therefore an object of the invention to design a gas turbine of the type mentioned in terms of the front segments so that the disadvantages of the known solutions are avoided and in particular the outer sealing strips installed after coating and can be replaced without opening the front segments, as well to specify a method for their reconditioning.

It is also an object of the invention to avoid a deformation of the seals, even if a larger extension of the front plate takes place with respect to the cooling plate.

The objects are achieved by the claims 1 and 11.

The gas turbine according to the invention, which is in particular a stationary gas turbine, comprises an annular combustion chamber which is bounded in the radial direction by an inner side wall and an outer side wall and in the axial direction by an annular front plate through which front plate burners communicate with the combustion chamber wherein the front plate is covered to the combustion chamber towards protection against heat by a plurality of circular ring forming, flat front segments, each comprising a front plate forming the front and a parallel to and spaced behind the front plate cooling plate.

It is characterized in that the front segments are releasably hooked to the front panel, that for sealing the front segments in Circumferentially one another between adjacent front segments each extending in the radial direction seal is arranged, and that the seal by two parallel running, in the middle between the adjacent front segments abutting outer sealing strip is formed, each of which on the outside at the edge of the cooling plate the associated front segment is attached.

An embodiment of the gas turbine according to the invention is characterized in that the front segments have on their back a plurality of hooks, and that on the front of the front plate fixing bolts are arranged, each having a hook receptacle, and in which the front segments are hooked with their hooks ,

It is particularly advantageous if the hooks are arranged distributed on the edges of the front segments running in the radial direction, and if the hooks and the hook receivers are oriented such that the front segments are largely fixed perpendicular to the segment surface, while they have sufficient freedom of movement parallel to the segment surface Compensation of thermally induced strains.

According to another embodiment of the invention, the fastening bolts are screwed to the front panel, means being provided for securing the fastening bolts against rotation.

A further embodiment is characterized in that the cooling plate has holes distributed over the surface through which cooling air can flow into the intermediate space between the front plate and the cooling plate for impingement cooling of the front plate.

Another embodiment of the invention is characterized in that in the front segments in each case the cooling plate is held by distributed in the area arranged spacer bolts at a distance from the front plate, and that the Fuse plate is fixed to the standoff bolt by means of the back of the standoff pins and fixed to the standoffs by a weld firmly connected washers.

It is particularly favorable for the reconditioning, it is when the lock washers are each composed of a lower ring and an upper ring, and when the lock washers are firmly connected only in the region of the upper ring with the associated standoff bolt through the weld.

A further embodiment is characterized in that the outer sealing strips consist of a precipitation-hardened, high-temperature-resistant nickel-based alloy, that the outer sealing strips are biased to one another in the cold state of the gas turbine, that the outer sealing strips extend with their sealing lips against the flow direction, and that the outer sealing lips To reduce the mutual wear at their free ends are provided with a radius.

Another embodiment of the invention is characterized in that for securing the outer sealing strips distributed along the edge of the cooling plate arranged fixing clips are provided, that the outer sealing strips are slidably held between the fixing clips and the respective heat sink, and that the fixing Clips are each outside the range of the outer sealing strip firmly connected by a weld with the heat sink

In particular, the displacement of the outer sealing strip between the fixing clips and the associated cooling plate is limited in each case by a knob formed on the fixing clip, which penetrates through a larger cutout in the outer sealing strip into a pocket arranged underneath in the cooling plate.

The inventive method for reconditioning a gas turbine according to the invention is characterized in that for removing the cooling plate, the welded with the standoffs upper rings are separated, that the remaining lower rings are deducted from the standoffs, and that for re-fixing the cooling plate on the standoffs The remaining lower rings are put back on the distance bolts and firmly connected to the distance bolts by welding.

BRIEF EXPLANATION OF THE FIGURES

Fig. 1

in einem Ausschnitt den Längsschnitt durch eine Gasturbine, wie sie zur Realisierung der Erfindung geeignet ist;

Fig. 2

in einer Ansicht schräg von vorne ein Frontsegment gemäss einem Ausführungsbeispiel der Erfindung;

Fig. 3

das Frontsegment aus Fig. 2 in einer Ansicht schräg von hinten;

Fig. 4

in einem Ausschnitt schräg von hinten gesehen den Anschlussbereich zwischen zwei benachbarten Frontsegmenten gemäss einem Ausführungsbeispiel der Erfindung;

Fig. 5

in einer Schnittdarstellung die Befestigung des Frontsegmentes an der Frontplatte gemäss einem Ausführungsbeispiel der Erfindung;

Fig. 6-8

verschiedene Schritte beim Rekonditionieren gemäss einem Ausführungsbeispiel der Erfindung;

Fig. 9

in einer Schnittdarstellung den Übergangsbereich zwischen zwei benachbarten Frontsegmenten gemäss einem Ausführungsbeispiel der Erfindung;

Fig. 10

in einer Explosionsdarstellung die Befestigung eines äusseren Dichtungsstreifens am Frontsegment gemäss einem Ausführungsbeispiel der Erfindung;

Fig. 11

den Schnitt durch die Befestigungsanordnung gemäss Fig. 10;

Fig. 12

die Befestigungsanordnung gemäss Fig. 10 in der Draufsicht von oben; und

Fig. 13

eine schematisierte Darstellung einer stationären Gasturbine mit sequenzieller Verbrennung aus dem Stand der Technik.

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

Fig. 1

in a section of the longitudinal section through a gas turbine, as is suitable for implementing the invention;

Fig. 2

in a view obliquely from the front, a front segment according to an embodiment of the invention;

Fig. 3

the front segment off Fig. 2 in a view obliquely from behind;

Fig. 4

seen in a section obliquely from behind the connection area between two adjacent front segments according to an embodiment of the invention;

Fig. 5

in a sectional view of the attachment of the front segment on the front panel according to an embodiment of the invention;

Fig. 6-8

various steps in reconditioning according to an embodiment of the invention;

Fig. 9

in a sectional view, the transition region between two adjacent front segments according to an embodiment of the invention;

Fig. 10

in an exploded view, the attachment of an outer weather strip on the front segment according to an embodiment of the invention;

Fig. 11

the section through the mounting arrangement according to Fig. 10 ;

Fig. 12

the fastening arrangement according to Fig. 10 in the top view from above; and

Fig. 13

a schematic representation of a stationary gas turbine with sequential combustion of the prior art.

WAYS FOR CARRYING OUT THE INVENTION

FIGS. 2 and 3 show in a view obliquely from the front or from behind a front segment 23 according to an embodiment of the invention. The front segment 23 has on the front side (towards the combustion chamber) a front plate 28 provided with distributed first holes 33. On the back of a cooling plate 29 is arranged parallel to the front plate 28, which is equipped with second holes 34. On the front panel 28, an upper edge 36 and a lower edge 37 are integrally formed at the top and bottom to the rear protruding. Also formed on the front plate 28 to the rear protruding are on the sides a plurality of along the side edges distributed hooks 35, the attachment of the front segment 23 on the front panel (45 in Fig. 5 ) serve. in the Front segment 23 are furthermore circular openings 31 and 32 for the burners 21 and 22 (FIG. Fig. 1 ) intended.

The attachment of the front segments 23 on the front plate 45 is carried out according to 4 and 5 respectively. Fig. 9 by means of fastening bolts 39. The fastening bolts 39 have two mounting features: on the one hand, a securing pin 43, which is inserted into a securing bore 42 in the fastening bolt and in the front plate 45 in order to prevent the fastening bolt 39 from rotating ( Fig. 5 ). On the other hand, an Allen screw 44, which guided through the front panel 45 via a threaded hole 41, the fastening bolts 39 attached. This Allen screw 44 is finally protected against sweat.

The fastening principle of the front segment 23 by means of the fastening bolts 39 is based on clamping, i. the hook receptacle 40 of the fastening bolt 39 clamps on the bearing surface of the hook 35 of the front segment 23 in the axial direction (perpendicular to the segment surface) the front segment 23 fixed. This principle still allows a shift of the front segment in the radial and in the circumferential direction (in the plane of the segment surface) even with a large force. This mobility is necessary to compensate for the different thermal expansions of different components.

The attachment of the cooling plate 29 on the front panel 28 by means of fasteners 38, according to Fig. 6-8 on the one hand spacers 46 include to maintain the desired distance to each other, and on the other hand have lock washers 47, which are welded to the standoffs 46 (weld 48) and thus the so-called sandwich construction of front panel 28 and heat sink 29 together. The standoffs 46 are connected to the front panel 28 by spot welding. The spacer bolts 46 can absorb forces in the radial and in the circumferential direction. These forces can arise due to the greater thermal expansion of the front plate relative to the heat sink.

The lock washers 47, however, absorb all the axial forces, which are caused by pulsations of the combustion chamber 24 and thermal deformation of the front segment. Of course, axial forces also arise purely by the weight of the cooling plate 29. The lock washers 47 are designed in two stages (47a, 47b in Fig. 7 ) so that they can be reused a second time during reconditioning. The idea is to cut open only the upper first welded ring 47b of the lock washer 47. The lower second ring 47a can then be used again with the spacer bolt 46 or welded (welding 49 in Fig. 8 ).

At the front segment 23 according to FIGS. 2 and 3 are arranged at the radially extending side edges outer sealing strip 30, which serve to seal the front segments with each other in the circumferential direction. By designing the design, the seals, which are preferably made of a precipitation-hardened, high-temperature-resistant nickel-base alloy, eg Waspaloy®, are already pre-stressed to each other when cold. This principle provides optimal sealing in all operating conditions.

The sealing lips of the outer sealing strips 30 are according to Fig. 9 designed opposite to the flow direction 52. By this principle, the sealing is improved by taking advantage of the pressure difference in the flow direction to press the outer sealing strips 30 against each other. The outer sealing strips 30 have at the ends of the sealing lips 59 radii R ( Fig. 11 ), so that the mutual wear in the arrangement according to Fig. 9 is minimized. Tilting of the outer weather strip 30 during installation and operation is thus avoided.

The outer sealing strips 30 are fastened by six fixing clips 53 per seal (FIG. 10, 11 ). These fixing clips 53 have a knob 54, which is guided in a cut-out pocket 57 on the cooling plate 29. This knob 54 absorbs forces in the radial and in the circumferential direction and thus prevents the falling out of the outer weather strip 30. A cutout on the fixing clip 53, which is designed to be greater than the thickness of the outer sealing strip 30, allows free movement of the outer sealing strip 30. This prevents stresses in the outer sealing strip 30, which are caused by different thermal expansions of the front plate 28 and heat sink 29. The fixing clips 53 are fastened by welding to the cooling plate 29 (FIG. Fig. 11 ). The welding 56 takes place between two feet 58 on the fixing clip 53 (FIG. Fig. 12 ). These feet 58 cause that the fixing clips 53 do not lift by the action of heat of the welding process and thus are no longer parallel to the cooling plate 29. A controlled mobility of the outer weather strip 30 would not be guaranteed in such a case.

A comparison of the proposed new design with the old design reveals in particular the following: In the previous design, the seal was between the front panel and the cooling plate; therefore, all spacers always had to be cut open, the hooks bent and the spacers removed, because the heat sink had to be dismantled.

With the new design, the seal is located above the cooling plate, on the cold side, therefore the cooling plate does not need to be removed. The standoffs no longer have to be cut open and hooks and spacers are no longer bent open or removed. Only the fixing clips must be dismantled. Seen from the other side, this also has the advantage that the seals can be mounted after coating.

However, the reconditioning of a front segment does not necessarily involve only replacement of the weather strips; Further repairs may be necessary, removing the cooling plate. In such a case, spacer bolts / hooks / spacers would still be cut / bent / removed anyway. Here would then be a second use of the lock washer according to Fig. 6-8 come to the course.

LIST OF REFERENCE NUMBERS

10.20

gas turbine

11

compressor

12.16

fuel supply

13,21,22

burner

14,17,24

combustion chamber

15.18

turbine

19

machine axis

23

front segment

25

outer side wall

26

inner sidewall

27

Hot gas path

28

Frontblech

29

heatsink

30

outer weather strip

31.32

opening

33.34

hole

35

hook

36

upper edge

37

lower edge

38

attachment

39

mounting bolts

40

Euro hook

41

threaded hole

42

lock hole

43

safety pin

44

Allen screw

45

front panel

46

Standoffs

47

lock washer

47a

lower ring

47b

upper ring

48,49,56

welding

50

Seal (two sealing strips 30)

51

gap

52

flow direction

53

Fixing clip

54

knob

55

neckline

57

bag

58

Foot

59

sealing lip

R

radius

Claims (11)

1. Gas turbine (20), especially a stationary gas turbine, comprising an annular combustion chamber (24), which in the radial direction is delimited by an inner sidewall (26) and an outer sidewall (25), and in the axial direction is delimited by a circular ring-like front plate (45), through which front plate (45) burners (21, 22) are in communication with the combustion chamber (24), wherein the front plate (45) is covered towards the combustion chamber (24) for protection against heat effect by means of a multiplicity of flat front segments (23) which form a circular ring, which front segments comprise in each case a front panel (28), which forms the front side, and a cooling panel (29), which is arranged parallel to and at a distance behind the front panel (28), characterized in that the front segments (23) are detachably mounted on the front plate (45) in a hooked-in manner, in that for sealing the front segments (23) in the circumferential direction in relation to each other a radially extending seal (50) is arranged between adjacent front segments (23) in each case, and in that the seal (50) is formed by two parallel extending outer sealing strips (30) which abut in the middle between the adjacent front segments (23), of which each is fastened in each case on the outer side on the edge of the cooling panel (29) of the associated front segment (23).
2. Gas turbine according to Claim 1, characterized in that the front segments (23) have a multiplicity of hooks (35) on their rear side, and in that fastening bolts (39) are arranged on the front side of the front plate (45), which have in each case a hook socket (40), and into which the front segments (23) are hooked by their hooks (35).
3. Gas turbine according to Claim 2, characterized in that the hooks (35) are located in a distributed arrangement on the radially extending edges of the front segments (23), and in that the hooks (35) and the hook sockets (40) are oriented in such a way that the front segments (23) are largely fixed perpendicularly to the segment surface, whereas they have adequate movement clearance parallel to the segment surface for compensating thermally induced expansions.
4. Gas turbine according to Claim 2 or 3, characterized in that the fastening bolts (39) are fastened on the front plate (45) by screws, and in that means (42, 43) are provided for locking the fastening bolts (39) against rotation.
5. Gas turbine according to one of Claims 1 - 4, characterized in that the cooling panel (29) has holes (34) distributed over the surface, through which cooling air can flow into the interspace (51) between front panel (28) and cooling panel (29) for impingement cooling of the front panel (28).
6. Gas turbine according to Claim 5, characterized in that in the front segments (23) the cooling panel (29) is kept at a distance in each case from the front panel (28) by means of spacer bolts (46) which are located in a distributed arrangement in the surface, and in that the cooling panel (29) is fixed on the spacer bolts (46) by means of locking plates (47) which are seated from the rear side upon the spacer bolts (46) and fixedly connected to said spacer bolts (46) by means of a weld (48).
7. Gas turbine according to Claim 6, characterized in that the locking plates (47) are assembled in each case from a lower ring (47a) and an upper ring (47b), and in that the locking plates (47) are fixedly connected by means of the weld (48) to the associated spacer bolt (40) only in the region of the upper ring (47b).
8. Gas turbine according to one of Claims 1 -7, characterized in that the outer sealing strips (30) consist of a precipitation-hardened, high temperature-resistant nickel-based alloy, in that the outer sealing strips (30) are pretensioned to each other in the cold state of the gas turbine (20), in that the outer sealing strips (30) extend by their sealing lips (59) counter to the flow direction, and in that the outer sealing lips (59) are provided with a radius (R) on their free ends for reducing the mutual wear.
9. Gas turbine according to one of Claims 1 -8, characterized in that for fastening of the outer sealing strips (30) provision is made for fixing clips (53) which are located in a distributed arrangement along the edge of the cooling panel (29), in that the outer sealing strips (30) are retained in a movable manner between the fixing clips (53) and the respective cooling panel (29), and in that the fixing clips (53) are fixedly connected in each case to the cooling panel (29) by means of a weld (56) outside the region of the outer sealing strip (30).
10. Gas turbine according to Claim 9, characterized in that the displacement of the outer sealing strip (30) between the fixing clips (53) and the associated cooling panel (29) is limited in each case by means of a knob (54) which is formed on the fixing clip (53) and which penetrates through a larger constructed cutout (55) in the outer sealing strip (30) into a pocket (57), arranged beneath it, in the cooling panel (29).
11. Method for reconditioning a gas turbine according to Claim 7, characterized in that for removing the cooling panel (29) the upper rings (47b) which are welded to the spacer bolts (40) are detached, in that the remaining lower rings (47a) are withdrawn from the spacer bolts (40), and in that for refixing of the cooling panel (29) on the spacer bolts (40) the remaining lower rings (47a) are reseated upon the spacer bolts (40) and fixedly connected to said spacer bolts (40) by means of a weld (49).

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