DE102010007724A1 - Screwless intermediate stage seal of a gas turbine - Google Patents

Abstract

The invention relates to an intermediate stage seal arrangement of a gas turbine with a radially outer ring (1), which is connected to guide vanes, and with a radially inner ring (3), which is mounted on the outer ring (1), the inner ring being by means of a plurality of removable holding elements (7, 8, 9) is fixed in the axial direction relative to the outer ring (1).

Description

The invention relates to an interstage seal arrangement of a gas turbine, and more particularly to a gas turbine having a screwless interstage seal construction.

In turbine stages of gas turbines, it is known to screw the rotor disks together. This takes place during assembly so that the arranged between adjacent rotor disks intermediate stage seal are already pre-assembled. These are to be designed so that the accessibility to the disc flanges of the rotor discs ensures their screwing and on the other hand, the sealing function is met.

The prior art shows constructions in which the interstage seal assembly consists of two rings which are either individually secured to the vanes independently of each other or which are bolted together. Another known embodiment is the division into two half-rings, which must be mounted after screwing the rotor disks.

In the known embodiments with screwed rings, it proves to be disadvantageous that the screw connection of the interstage seal parts is exposed to high temperatures. In case of failure of the screw (breakage of individual screws) results in damage to the rotor discs. Furthermore, the screwing involves the risk that other components may be damaged during the assembly process, for example, a Christmas tree toothing on the disc. Furthermore, the screw creates a turbulence of the air flows between the rotor and stator and thus generates an air resistance, which counteracts the rotation. The turbulence also leads to an increase in the air temperature, which has a negative effect on the disk temperature and the cooling air temperature for the subsequent blade. Another major disadvantage is that the choice of material for the rings of the interstage seal arrangement is limited because the relative radial displacement due to differential thermal expansion must be reduced to a minimum in order to prevent slippage of the flange and the associated bending load of the screws.

In the known from the prior art solutions with two separate interstage seal rings is a statically indeterminate system, which can occur by component tolerances constraining forces between the front ring and the rear ring (seen in the direction of flow of the gas turbine). In one of the rings is usually the pressure difference of the surrounding air so low that no or only small axial forces act. This can lead to vibrations and increased wear. The very cost-intensive manufacturing in the vane thus requires an increased processing costs. Furthermore, additional sealing strips or sealing elements are required between the vane segments. The ring carrying the interstage seal is also exposed to a high radial temperature gradient in this design.

In split interstage seal rings an increased amount of processing is required. In particular, elaborate milling work is necessary. Such an assembly is matched with respect to their elements, so that individual elements (for example, half-rings) can not be replaced individually. Furthermore, such a system-inherently non-rotationally symmetrical construction is exposed during operation to asymmetrical thermal expansions, so that such components can deform from a circular shape into an oval shape. As a result, an increased cold gap may be required and thus result in increased leakage.

The invention has for its object to provide a Zwischenstufendichtungsanordnung a gas turbine of the type mentioned, which avoids the disadvantages of the prior art with a simple structure and simple, cost-effective manufacturability and in particular has good structural properties.

According to the invention the object is achieved by the combination of features of claim 1, the dependent claims show further advantageous embodiments of the invention.

According to the invention, it is thus provided that the interstage seal arrangement comprises a (radially) outer ring, which is both held axially by guide vanes, and centered and thus stored, and a (radially) inner ring, which is mounted on the outer ring comprises. The terms (radially) outer and (radial) inner refer to the axis of rotation or machine axis. With the terms front and rear reference is made to the direction of flow of the gas turbine, front thus means closer to the inlet region, while rear means closer to the outlet.

According to the invention, each of the rings, namely the outer ring and the inner ring, is provided with at least one sealing area to perform the function of an interstage seal arrangement.

Furthermore, the invention provides that the inner ring is centered on the outer ring by at least three radial tongue and groove joints and secured against rotation in the circumferential direction. The planes of symmetry of all tongue and groove joints must all contain the main axis of rotation of the components involved to prevent deformation or damage. This principle corresponds to the state of the art and is used inter alia for the centering of the outer ring by the guide vanes. It allows different thermal expansions of the components involved while ensuring coaxiality.

With respect to the axial fixation of the outer ring by engaging in the radial groove strips of the vanes may be made to the prior art. The inner ring, however, is secured axially to the rear by an annular projection of the outer ring. The engagement of the inner ring on the outer ring is ensured in operation by the pressure differential between the front, first stage and located behind the interstage seal assembly second stage. At a standstill, the inner ring could move forward. However, this is prevented according to the invention by means of a plurality of holding elements. According to the invention, these holding elements can be disassembled even from the outside in order to enable a displacement of the inner ring to the front or of the outer ring to the rear for screwing the rotor disks. According to the invention, the holding elements are themselves secured against falling out by the strips of the guide vanes.

The radial groove in the outer ring can preferably be designed for inserting retaining elements. As a result, the radial groove is provided either over the entire peripheral region or over part of its circumference with a larger axial width, which makes it possible to introduce in addition to the strip of the guide blade in addition holding elements. At the periphery, for example, three such holding elements are provided which are sufficient to secure the inner ring against axial slipping when the engine is at a standstill. In an alternative embodiment of the invention, it is also possible to provide inwardly facing retaining elements, which are formed on the strip of the vane itself, either as pins which are introduced into radial bores of the strip, or as extensions of portions of the strip in the radial direction ,

To increase the sealing effect between the outer ring and the inner ring, it may be advantageous if the outer ring and / or the inner ring is provided at the respective contact area with a ring bead-shaped sealing projection.

According to the invention it is thus possible in a particularly favorable manner, to manufacture the outer ring and the inner ring of different materials, so that the outer ring and the inner ring can be optimized in terms of their thermal stresses.

In the following the invention will be described by means of embodiments in conjunction with the drawing. Showing:

1 FIG. 2 is a partial axial sectional view of an interstage seal assembly according to a first embodiment of the present invention; FIG.

2 a simplified partial view along the section line AA-AA according to 1 .

3 a view of a modified embodiment, analog 1 , and

4 a view, analog 1 , another embodiment.

In the embodiments, the same parts are each provided with the same reference numerals. For clarity, the representation of the centering tongue and groove connection is omitted in all figures.

The 1 shows a first embodiment in which an outer interstage seal ring 1 and an inner interstage seal ring 3 are provided, which respectively corresponding sealing areas 4 . 5 . 6 include. With regard to the dimensioning of the construction of the sealing areas 4 . 5 . 6 can be made to the prior art.

The outer ring 1 includes a radially extending, radially outwardly open radial groove 12 , in which a radially inwardly facing bar 11 a foot of a vane 2 is plugged in. The vanes 2 are formed according to the prior art and segmented in the circumferential direction, wherein in each case also a plurality of guide vanes 2 a common foot 16 can have.

The 1 to 3 continue to show a disc 17 a stage 1 a turbine with rotor blades 19 , as well as a disc 18 a stage 2 , which is located downstream of the intermediate stage seal assembly according to the invention, with rotor blades 20 , Regarding the discs 17 . 18 and the rotor blades 19 . 20 can be made to the prior art.

At the in 1 embodiment shown, the outer ring comprises 1 a circumferentially extending radially outwardly open radial groove 12 (see above), which in the axial direction with an additional, widening groove 15 is provided in a recess 14 goes over, which opens radially inward. In the groove 15 is (see also 2 ) a holding element 7 inserted, which (see 2 ) Is T-shaped and its foot 21 through the recess 14 passes. The holding element 7 gets through the bar 11 held after its assembly and thus extends with his foot radially inward.

Radially inward to the outer ring 1 is the inner ring 3 arranged. This lies against an annular approach 10 of the outer ring 1 and is thus supported in the axial direction. The annular approach 10 thus forms a plant leg and fixes the inner ring 3 where the inner ring 3 on its radially outer side with a space for thermal expansion with respect to the outer ring 1 is provided. On the ring-shaped approach 10 opposite side becomes the inner ring 3 through the retaining element 7 fixed. For example, three such holding elements are distributed over the circumference 7 intended.

The 2 shows in simplified representation a view along the line AA-AA of 1 , This shows that the retaining element 7 in the groove 15 is inserted and thus fixed radially, so that a reliable condition is ensured during operation of the gas turbine.

The construction according to the invention has the advantage that during assembly of the interstage seal arrangement or the gas turbine, the inner ring 3 on the outer ring 1 can be mounted in a simple manner. Subsequently, the holding elements 7 used and the vanes 2 plugged in.

The 3 shows a modified embodiment in which a holding element 8th as a pin-shaped extension of the bar 11 is formed, which is the recess 14 passes through and thus directly the inner ring 3 against shifting forward secures, as soon as the vane 2 is mounted.

At the in 4 embodiment shown is the respective holding element 9 formed in the form of a pin, which in a radial bore of the bar 11 is pressed.

According to the invention thus results in the advantage that a failure of glands can be excluded because no glands between the outer ring and the inner ring are provided. This also results in lower flow losses, since the surfaces of the outer ring and the inner ring can each be streamlined optimized.

A significant advantage results according to the invention in that the choice of material for the outer ring and for the inner ring can be optimized separately and thus, for example, an optimal splitting behavior for the inner ring, while the outer ring, a high temperature resistant material can be selected.

Another advantage may result in a weight saving as well as a reduction of the components and an associated reduction of the assembly costs.

LIST OF REFERENCE NUMBERS

1

Outer ring

2

vane

3

Inner ring

4

sealing area

5

sealing area

6

sealing area

7

retaining element

8th

retaining element

9

retaining element

10

Ring-shaped approach

11

strip

12

radial groove

13

sealing projection

14

recess

15

groove

16

foot

17

Slice of the stage 1

18

Slice of the stage 2

19

rotor blade

20

rotor blade

21

foot

Claims (9)

Interstage seal arrangement of a gas turbine with a radially outer ring ( 1 ), which is connected to vanes, as well as with a radially inner ring ( 3 ), which on the outer ring ( 1 ), wherein the inner ring by means of several removable holding elements ( 7 . 8th . 9 ) relative to the outer ring ( 1 ) is fixed in the axial direction, wherein the inner ring ( 3 ) in contact with an annular projection ( 10 ) of the outer ring ( 1 ). Interstage seal arrangement according to claim 1, characterized in that the annular projection ( 10 ) by means of a tongue and groove-like connection for positive retention in the circumferential direction with the inner ring ( 3 ) connected is. Interstage seal arrangement according to one of claims 1 or 2, characterized in that the guide vanes ( 2 ) each with a radially extending, annular segment-like bar ( 11 ), which in a radial groove ( 12 ) of the outer ring ( 1 ) is introduced. Interstage seal arrangement according to claim 3, characterized in that in the radial groove ( 12 ) Holding elements ( 7 ) are inserted, which in the axial direction against the inner ring ( 3 ) and fix it in the axial direction. Interstage seal arrangement according to claim 4, characterized in that on the strip ( 11 ) radially inwardly facing retaining elements ( 8th . 9 ) are arranged, which the inner ring ( 3 ) in the axial direction. Interstage seal arrangement according to claim 4 or 5, characterized in that the radial groove ( 12 ) with radially inwardly facing recesses ( 14 ) for the implementation of the holding elements ( 7 . 8th . 9 ) is trained. An interstage seal arrangement according to any one of claims 2 to 6, characterized in that on the axially annular shoulder ( 10 ) of the outer ring ( 1 ) and / or at the contact area of the inner ring ( 3 ) a ring-shaped sealing projection ( 13 ) is trained. Interstage seal arrangement according to one of claims 2 to 7, characterized in that the tongue and groove-like connection on one of the rings ( 1 ) fixed axial bolts ( 15 ) in corresponding recesses of the other ring ( 3 ) intervene. Interstage seal arrangement according to one of claims 1 to 8, characterized in that the outer ring ( 1 ) and the inner ring ( 3 ) are made of different materials.

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