US20110150640A1

US20110150640A1 - Labyrinth Seal in a Stationary Gas Turbine

Info

Publication number: US20110150640A1
Application number: US12/951,402
Authority: US
Inventors: Peter Tiemann; Christel Tiemann
Original assignee: Siemens AG
Current assignee: Siemens AG
Priority date: 2003-08-21
Filing date: 2010-11-22
Publication date: 2011-06-23

Abstract

A segmented inner ring for holding guide blades is provided. A lateral wall opposing the front side of the inner ring and pertaining to a shaft shoulder formed on the rotor shaft extends radially. Also a stationary gas turbine comprising a segmented inner ring is provided.

Description

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation-in-part of U.S. application Ser. No. 12/202,535 filed on Sep. 2, 2008, which is a continuation of U.S. National Stage application Ser. No. 10/569,144 filed on Feb. 21, 2006 claiming benefit to International Application No. PCT/EP2004/008052, filed Jul. 19, 2004. The International Application claims the benefits of European Patent application No. 03019002.9 EP filed Aug. 21, 2003. All of the applications are incorporated by reference herein in their entirety.

FIELD OF THE INVENTION

The invention relates to a stationary gas turbine having a segmented inner ring for holding guide vanes.

BACKGROUND OF THE INVENTION

DE 37 12 628 has disclosed an inner ring for holding guide vanes of a stationary gas turbine. The guide vanes which are arranged in a star shape around the rotor to form a guide vane ring are secured to the housing of the gas turbine by means of their radially outer guide vane roots. The radially extending guide vanes, on their side facing the rotor, have the guide vane head, which is connected to the stationary inner ring. This inner ring, which is U-shaped in cross section, engages coaxially around the rotor of the gas turbine and connects the guide vanes of a guide vane ring to one another in order to increase the stability of the guide vane ring and to improve the vibrational properties of the guide vanes. A gap is in this case formed between the web of the U-shaped inner ring, its flanks and the corresponding circumferential and end faces associated with the rotor. Likewise, the web of the U-shaped inner ring, on its surface facing the rotor, has one half of a labyrinth seal, which together with the second half arranged on the rotor forms the labyrinth seal.
When the gas turbine is operating, the working fluid which flows within the flow passage is only supposed to flow past the guide vanes of a guide vane ring. However, the working fluid can also flow through the gap formed by stationary and rotating components, as a leakage flow. To reduce the extent of the leakage flow, the gap between
the stationary and rotating components is sealed by means of the labyrinth seal.
Furthermore, it is known to provide a plurality of labyrinth seals in the gap between the flank of the inner ring and of the shaft shoulder, in order to achieve an improved sealing action. In this case, two labyrinth seals are arranged axially and radially offset with respect to one another, in a terraced arrangement, in the gap between the flank and shaft shoulder.

SUMMARY OF THE INVENTION

Therefore, the object of the invention is to make a stationary gas turbine with a parting gap available whose inner ring is designed in an alternative manner.
The object relating to the gas turbine is achieved by the features of the claims, and the object relating to the method is achieved by the features of the claims. Advantageous configurations are given in the subclaims.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is explained with reference to a drawing, in which:

FIG. 1 shows a segmented securing ring for guide vanes of a first turbine stage,

FIG. 2 shows the segmented inner ring for the guide vanes of a second, third and fourth turbine stage, and

FIG. 3 shows a partial longitudinal section through a gas turbine.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 3 shows a stationary gas turbine 1 in the form of a partial longitudinal section. In its interior, it has a rotor 3, which is mounted such that it can rotate about an axis of rotation 2 and is also referred to as the turbine rotor or rotor shaft. An intake housing 4, a compressor 5, a toroidal annular combustion chamber 6 with a plurality of coaxially arranged burners 7, a turbine 8 and the exhaust-gas housing 9 follow one another along the rotor 3. The annular combustion chamber 6 in this case forms a combustion space 10 which is in communication with an annular hot-gas duct 11, where four turbine stages 12 connected in series form the turbine 8. Each turbine stage 12 is formed from two blade/vane rings. As seen in the direction of flow of a working fluid 14, a guide vane ring 17 is followed in the hot-gas duct 11 by a ring 15 formed from rotor blades 18. The guide vanes 16 are secured to the stator 19, whereas the rotor blades 18 of a ring 15 are secured to the rotor 3 by means of a turbine disk 20. A generator (not shown) is coupled to the rotor 3.
The stationary gas turbine 1 has a housing 60 which with respect to a parting plane 61 running parallel to the horizontal plane can be divided into an upper housing half 62 and a lower housing half 64. In the subsequent text using the terms “upward” and “downward” or “upper half of the . . . ” and “lower half of the . . . ”, this is in each case to be understood as meaning with respect to the parting plane 61 of the gas turbine 1 for the object in question.
While the gas turbine 1 is operating, the compressor 5 sucks in air 21 through the intake housing 4 and compresses it. The air 21 provided at the turbine end of the compressor 5 is fed to the burners 7, where it is mixed with a fuel. The mixture is then burnt so as to form the working fluid 14 in the combustion space 10. From there, the working fluid 10 flows past the guide vanes 16 and the rotor blades 18 in the hot-gas duct 11. The working fluid 14 expands at the rotor blades 18, transmitting its momentum as it does so, so that the rotor 3 is driven, and with it the generator coupled to it is also driven.
On their side facing the housing 13, the guide vanes 16 have a guide vane root, by means of which they are hooked in an annular guide vane carrier. At their end facing the rotor 3, i.e. the guide vane head, they are connected to an inner ring 30.
FIG. 1 shows an excerpt from the gas turbine 1 between the guide vane 16 of the first turbine stage 12 and the rotor 3. The inner wall, located on the radially inner side, of the combustion chamber 6 delimits the hot-gas duct 11 toward the inside. As seen in the direction of flow of the working fluid 14, the guide vane 16 of the first turbine stage 12 is followed by the rotor blade 18.
On the rotor 3 is the turbine disk 20, which at its outer circumference holds the rotor blades 18. To secure the rotor blades 18 against axial displacement, at a side wall 22 of the turbine disk 20 a covering element 23 is hooked to the turbine disk 20 by means of a plurality of radially spaced hooks. The covering element 23, together with the turbine disk 20, forms a shaft shoulder 24.
A plurality of balconies 25′ 25″, 25′″, 25″″, which extend in the axial direction and are coaxially encircling, are arranged on a side wall 51, facing the combustion chamber 6, of the covering element 23.
In each case three sealing teeth 26′, 26″, 26′″, 26″″ extend coaxially on that circumferential surface of each balcony 25 which faces away from the rotor 3.
The three modules 33, 34, 35 are mounted rotationally fixedly on the stator 19, between the inner wall, located on the radially inner side, of the combustion chamber 6 and the rotor 3. The rotationally fixed inner ring 30 is provided between the modules 33, 34, 35 and the covering element 23.
On its end side 52 facing the shaft shoulder 24, the inner ring 30 has a plurality of balconies 29′, 29″, 29′″, 29″″ extending in the axial direction and coaxially encircling. Sealing surfaces 27′, 27″, 27′″, 27″″ are in each case provided on those circumferential surfaces of the balconies 29 which face the sealing teeth 26. Each sealing surface 27, together with its corresponding sealing teeth 26, forms a labyrinth seal 28.
A meandering gap 38, in which therefore four labyrinth seals 28′, 28″, 28′″, 28″″ are connected sequentially, of which the three labyrinth seals 28′, 28″, 28′″ are stacked radially on top of one another, is formed between the covering element 23 and the inner ring 30.
The labyrinth seal 28″″ is not stacked radially with respect to the next labyrinth seal 28′″ radially inward, but rather is arranged in terraced fashion, i.e. the labyrinth seal 28″″ is axially offset with respect to the labyrinth seal 28′″.
At its end side 52 facing the combustion chamber 6, the inner ring 30 has an axially extending arm 46, on the free end of which a projection 37, which extends radially inwards, is formed integrally.
On its side facing the inner ring 30, the module 34 comprises a projection 36, which forms a hooked engagement with the projection 37 of the inner ring 30.
When the gas turbine 1 is operating, a working fluid 14 flows within the hot-gas duct 11. To prevent the working fluid 14 from penetrating as a leakage flow into a gap 38 formed by stationary and rotating components, the gap 38 has a plurality of labyrinth seals 28 which are stacked radially on top of one another and act jointly, in terms of flow, as a seal 31.
The three labyrinth seals 28′, 28″, 28′″, which are stacked without any axial offset with respect to one another, allow a more compact design combined, at the same time, with an improvement in the sealing action as a result of the increase in the number of labyrinth seals 28.
FIG. 2 shows an excerpt of a gas turbine 1 located between the hot-gas duct 11 and the axis of rotation 2 of the rotor 3. The turbine disk 20″ bears the rotor blade 18″ of the second turbine stage and the turbine disk 20′″ bears the rotor blade 18′″ of the third turbine stage. On the side wall 22″ of the turbine disk 20″, the covering element 23″ secures the rotor blade 18″ against axial displacement. The covering element 23″ is hooked to the turbine disk 20″ by means of two hooked engagements that are radially spaced apart from one another. In the same way, the covering element 23′″ secures the rotor blade 18′″ against axial displacement. In this case, the covering element 23′″ and the turbine disk 20′″ are hooked together on the side wall 22′″.
The inner ring 30 with a securing ring 40 is provided in the groove-shaped recess 42 formed between the two turbine disks 20″, 20′″. The securing ring 40 is connected to the inner ring 30 on its side facing the rotor 3 by means of a hooked engagement 41 and is connected to the guide vane 16′″ on its side facing away from the rotor 3. For this purpose, the inner ring 30 is bolted to the guide vane 16′″ by means of a bolt 45, whereas the securing ring 40 is clamped to the guide vane 16′″. The securing ring 40 has a groove 43 into which extends a projection 44 arranged on the guide vane 16′″.
The side wall 51 facing away from the turbine disk 20′″, the covering element 23′″ has three balconies 25′, 25″, 25′″ which extend in the axial direction and are coaxially encircling. In each case three coaxially encircling sealing teeth 26′, 26″, 26′″ are provided on the outer circumference of the individual balconies 25′, 25″, 25′″. On its end side 52 assigned to the turbine disk 20′″, the inner ring 30 likewise has three balconies 29′, 29″, 29′″, which extend in the direction of the shaft shoulder 24 and are coaxially encircling transversely with respect thereto. Each balcony 29, on its inner circumferential surface, has a sealing surface 27 facing the balconies 25 of the covering element 23′″ located further inward in the radial direction. In this case, the sealing surface 27′ together with the sealing tooth 26′ forms a labyrinth seal 28′, the sealing surface 27″ together with the sealing tooth 26″ forms a further labyrinth seal 28″, and the sealing surface 27′″ together with the sealing tooth 26′″ forms the third labyrinth seal 28′″.
The seal 31 shown in FIG. 2 can be put together by the sequence of the following assembly steps:
At the start of assembly of the stationary gas turbine 1 having the parting plane 61, first of all the lower housing half 64 is put in place. In each case the lower halves of the guide vane rings 17 have already been completed in the lower housing half 64 by means of preassembled guide vanes 16.
Only the covering element 23″ has been mounted on the rotor 3, which has not yet been fitted; the side wall 22′″ does not yet have a covering element 23′″.
For each inner ring 30 according to the invention, the lower half of the securing ring 40, which is formed by a single-part or multi-part segment of a total size of 180°, is placed into the lower housing half 64, so that the projection 44 engages in the groove 43. Then, the lower half of the inner ring 30 is mounted in the lower housing half 64 which in each case hooks to the inner ring 30 and is partly bolted to the guide vanes 16 in order to secure them against relative movements. The lower half of the securing ring 30 is likewise formed from one or more segments totaling a size of 180°.
When the lower half of each securing ring 40 and inner ring 30 has been mounted in the lower housing half 64, the rotor 3 is placed into the lower housing half 64. At least the lower halves of the side wall 22′″ of the turbine disks 20, which subsequently face the end side 52, must not have a covering element 23′″, since otherwise the rotor 3 cannot be placed into the lower housing half 64.
A segment of the covering element 23′″ is mounted on the upper half of the side wall 22′″ of the rotor 3 which has already been placed into the lower housing half 64.
Then, the rotor 3 is rotated, so that during this rotation the segment of the covering element 23′″ which is mounted on the upper half is rotated into the lower housing half 64. In the process, the axially extending balconies 25 of the covering element 23′″ move accurately between the corresponding balconies 29 of the inner ring 30 which is already located in the lower half.
Segments of covering elements 23 continue to be mounted on the upper half of the side walls 22 and rotated into the lower housing half 64 until the lower half of the seal 31 has been completely formed.
After the upper half of the covering element 23 has then been mounted on the upper half of the rotor 3 on the side wall 22′″, the upper half of the inner ring 30 can then be moved radially inward into the recess 42 formed between the turbine disks 20″, 20′″ in order to complete the inner ring 30, in order for the balconies 29 thereof then to be moved over the balconies 25 of the covering elements 23′″ by displacement in the axial direction. The upper half of the inner ring 30 is positioned on the flanges of the lower half of the inner ring 30 or securing ring 40.
Thereafter, the upper half of the securing ring 40 is moved into the recess 42 and hooked to the inner ring 30 in order to complete the circular, segmented securing ring 40.
Then, in a manner which is already known, the guide vanes 16 of the upper half of the guide vane ring 17 can be mounted.
The assembly instructions are carried out in a similar manner for securing the guide vanes 16 of the first turbine stage 12 shown in FIG. 1.
In the lower housing half 64, the guide vanes 16 and the modules 35, 36, 37 have already been preassembled before the rotor 3 without covering element 23 is placed into it.
Then, if not already present, one or more segments of the covering element 23 are mounted on the upper half of the side wall 22 of the first turbine disk 20. Next, the rotor 3 is rotated, so that the segment(s) slide into the lower housing half 64 so as to form the lower half of the seal 31.
After the upper half of the covering element 23 has been mounted on the upper half of the rotor 3 at the side wall 22, the upper half of the inner ring 30 can then be moved radially inward into the clear space between turbine disk 20 and annular combustion chamber 6, in order for the balconies 29 thereof then to be pushed in the axial direction over the balconies 25 of the covering elements 23. The upper half of the inner ring 30 is located on the end sides of the lower half of the inner ring 30. Then, the modules 33, 34 and 36 are successively installed.
In an alternative configuration, each segment can be formed from a plurality of pieces.
During operation, it is possible for the rotor 3 to be displaced counter to the direction of flow of the working fluid 14 without a balcony 25, 29 touching or striking the end side lying opposite it.
The inner ring 30, which is rotationally fixed while the gas turbine 1 is operating, together with the rotating covering elements 23, forms a gap 38 which is sealed by means of the seal 31. The working fluid 14 is effectively prevented from leaving the hot-gas duct 11, so that it flows past the rotor blades 18 as intended. The leakage flow is effectively reduced, which leads to an increase in the efficiency of the stationary gas turbine.
Furthermore, the seals 47, 48, 49, 50 reduce the leakage flow between rotating and stationary components.

Claims

1. A stationary gas turbine engine, comprising:

a compressor arranged within the engine that provides a compressed airstream flow;

a combustion chamber located downstream of the compressor;

a turbine located downstream of the combustion chamber;

a lower housing portion and an upper housing portion defining a parting plane between the housing portions;

a rotor having a centerline located along the parting plane, the rotor having a shaft shoulder;

a guide vane ring which supports a plurality of guide vane segments at an outermost radial end of the segments, the guide vane segments arranged coaxially around the rotor at angular intervals;

a segmented inner ring which supports a radial innermost edge of the guide vanes; and

a securing ring which inhibits axial displacement of the inner ring.

2. The gas turbine engine as claimed in claim 2, wherein the guide vane segments are arranged around the rotor at equal angular intervals.

3. The gas turbine engine as claimed in claim 2, wherein the inner ring is secured to a rotationally stationary element.

4. The gas turbine engine as claimed in claim 2, wherein the inner ring is secured to the guide vanes.

5. A split u-ring for use in a turbo machine, comprising:

a rotationally stationary first ring portion arranged concentric with a rotational centerline of the turbomachine, where the first ring portion

supports a radially innermost portion of a stationary guide vane of the turbomachine, and

has a radially inward facing hook arrangement; and

a rotationally stationary second ring portion arranged downstream of and immediately adjacent to the stationary first ring portion, where the second ring portion further supports the radially innermost portion of a stationary guide vane of the turbomachine.