KR100600922B1 - Combined labyrinth and brush seals for rotary machines - Google Patents

Abstract

A combination labyrinth / brush seal is provided in the seal between the rotating element and the stationary element. The seal includes a plurality of arcuate seal ring segments 20 each having one or more labyrinth teeth 24 extending radially towards the surface of the rotating element. As original equipment or retrofit, a brush seal is provided in the labyrinth tooth in the slot 48 formed in the seal surface of the seal ring segment 20. In one form, the brush seal support and / or the front plates 38, 40 have a tongue 62 extending into the axially extending recess 60 of the seal ring segment 20, so that the brush The relative radial movement of the seal and seal ring segment 20 is prevented. End faces of the brush seal and the seal ring segment have holes 66 formed and filled with welding material to prevent circumferential relative motion. If a single radially extending slot 48 is provided in the seal ring segment 20, the brush seal may be stitch-welded to the seal ring segment along both plates 38, 40 of the brush seal.

Description

COMBINED LABYRINTH AND BRUSH SEALS FOR ROTARY MACHINES}

The present invention fixes and / or retrofits a brush seal to provide a combination brush and labyrinth seal for rotary machinery such as steam and gas turbines, and a labyrinth brush seal combination. It is about how to.

BACKGROUND Rotating mechanisms, such as steam and gas turbines used in power generation and mechanical drive applications, are large machinery that typically consist of multiple turbine stages. In a turbine, the high pressure fluid flowing through the turbine stage must pass through a series of stationary and rotating elements, and a seal between the stationary and rotating elements is used to suppress leakage. The efficiency of the turbine depends, for example, on the seal's ability to prevent leakage between the rotor and the stator. Turbines and other machinery that use relative rotating parts typically apply rigid teeth, ie labyrinth type seals, to suppress leakage. Typically, high-low or straight axial rigid labyrinth seals are used. Seals of this type are used in practically all turbine positions where leakage between the rotating element and the stationary element must be suppressed. This includes interstage axial seals, rotor end seals and blade tip seals. The labyrinth seal is proven to be reliable, but its performance deteriorates over time as a result of a transient event in which the stationary and rotating elements interfere, rubbing the labyrinth teeth in the form of a "mushroom" and opening the seal gap. . The rolling mechanism also applies a brush seal. Brush seals are generally less likely to leak than labyrinth seals. The brush seal can also accommodate relative movement between the stationary element and the rotating element, such as the rotor and the stator, because the seal bristle is bent. Brush seals can also better match surface irregularities. Combination brushes and labyrinth seals are disclosed in US Pat. No. 5,474,306. However, in order to retrofit existing turbines and incorporate combined labyrinth and brush seals into new machinery, compact seal designs are required due to physical space constraints. It is also desirable to have a brush seal, which is essentially a double safety device, due to the long time interval between turbine inspection and expensive maintenance. Therefore, it is desirable to design the original labyrinth type seals and the brush seals incorporated into the lids of existing labyrinth seals.

Summary of the Invention

According to the present invention, a combination brush seal is provided within the environment of a rotating machine such as a turbine, in which the brush seal is attached to the original or improved labyrinth tooth seal ring segment to facilitate relative circumferential and radial motion. Can be fixed. In the present invention, the brush seal can take the form of a plurality of bristles supported by the support. That is, the bristles are arranged between the pair of support plates in the form of arcuate segments and fixed between them, for example by welding the radially outermost part of the brush seal support. Preferably, each seal ring segment has an arcuate surface, from which a plurality of labyrinth teeth axially spaced protrude opposite a rotating element such as an axis. When adding a brush seal as original equipment to provide a combinatorial labyrinth brush seal or retrofitting the brush seal to the seal ring segment, grooves along the arcuate surface of the seal ring segment to accommodate the support for the array of bristles Is formed. That is, the bristles between the arcuate plates and the plates are concentric with the seal ring segments and are receivable in the groove such that the radially inner ends of the bristles project past the tips of the axially adjacent labyrinth teeth and engage against the opposing rotating elements. . To secure the support to the seal ring segment, one or more welds are provided along both sides of the support between the support and the seal ring segment surface such that the brush seal is applied to the seal ring segment for radial and circumferential motion relative to the seal ring segment. Can be fixed Preferably, one of the support plates for the array of bristles has a tapered tooth edge that forms additional labyrinth seal teeth when the brush seal is attached to the seal ring segment.

In another form of the invention, the seal ring segment has a groove having a recess extending axially outwardly of the seal ring segment surface. The brush seal support also has an axially extending leg for receiving in the recess when the support is received in the groove of the seal ring segment, thereby securing the support and the seal ring segment against radial relative motion with respect to each other. To prevent the circumferential movement of the support and the seal ring segment with respect to each other, the end faces of the brush seal support and the seal ring segment have openings extending generally tangentially or circumferentially such that the adjacent ends of the seal ring segment and the support are Expose the surface. Welding material is provided in the opening to secure the support and the seal ring segment against circumferential relative motion. Thus, the brush seal and seal ring segment can be spot welded at one end of the segment to prevent circumferential relative motion.

When retrofitting the brush seal to the seal ring segment, the sealing surface of the rotating element is preferably smoothed by machining a layer of thin material from this surface. Typically, depending on the axial thickness of the seal and the axial relative motion of the rotor foreseen, the number of existing rotor lands may be zero to one or more, but one of the lands may be removed.

In a preferred embodiment according to the invention, in a rotating mechanism having a rotatable element lying about a common axis and a stationary element for rotation, a seal is provided between these elements, the seal being supported by the stationary element An elongated arcuate seal ring segment having an arch surface opposite the rotating element, and at least one labyrinth seal tooth projecting generally radially from the seal ring segment towards the rotating element, wherein the seal ring segment surface is axial from the seal tooth. A brush seal having said labyrinth seal teeth having grooves spaced in a direction and comprising a plurality of bristles and a support for bristles disposed in the groove, wherein the bristles are fixed in the support and protrude beyond the support therefrom; A seal, a support for fixing the support in the groove, At least one weld between the seal ring segments.

In another preferred embodiment according to the invention there is provided between a rotatable element lying about a common axis and an element fixed for rotation and supported by one of the elements and projecting generally radially toward the other of the elements between the elements. In a rotating machine comprising a plurality of teeth extending generally circumferentially for sealing in a method, a method of forming a combination labyrinth and brush seal between the elements, comprising: an array of circumferentially separated bristles; The shaft from the tooth on the one element by fixing to one element such that the bristles lie in a plane substantially perpendicular to the axis and the distal end thereof protrudes toward the other element beyond the radial region of the tooth and substantially seals the other element. Retrofitting the array of bristles circumferentially spaced apart in a direction; The method comprising the step of welding to one element of the array of groups of bristles are provided.

It is therefore a primary object of the present invention to provide a novel and improved apparatus and method for forming a combination labyrinth and brush seal between a rotating and stationary element of a turbine, wherein the brush seal is the circumferential relative of the stationary element and the brush seal. It is provided as a retrofit or original equipment with welds to prevent movement.

1 is a schematic illustration of a seal ring segment between a stationary and rotating element showing a combined labyrinth and brush seal according to the invention on a seal surface;

2 is an enlarged partial end view of a brush seal showing the relationship between the tip of the bristles and a support plate having a labyrinth tooth profile;

3 is a partial cross-sectional view of a brush seal inserted into the seal ring segment in the form of a tongue and groove,

4 is a partial cross-sectional view of a brush seal in a recess of a seal ring segment in accordance with another aspect of the present invention;

FIG. 5 is a view similar to FIG. 4 showing the reversed shape of the brush seal in the groove, FIG.

6 is an enlarged end view of the brush seal of FIG. 4 in a seal ring segment showing an opening for receiving a welding material that limits circumferential movement of the brush seal;

7 is a cross-sectional view taken along line 7-7 of FIG. 3 showing a weld stitch line for securing a brush seal in a recess of the seal segment;

8 is a view similar to FIG. 7 showing the assembly of FIG. 4;

1, in particular with reference to FIG. 1, is shown a portion of a rotating mechanism, such as a steam turbine, having a turbine shaft 10 disposed in a turbine housing 12 and typically supported within the turbine housing 12. The seal ring 14 is disposed in a turbine housing, i.e., a stationary element that separates the high pressure region 16 and the low pressure region 18 on both sides of the ring in the axial direction. The seal ring 14 is formed of an annular array of a plurality of labyrinth seal teeth 24 radially spaced apart from the plurality of arcuate seal ring segments 20 having a seal surface 22. As shown, the teeth have a high-low structure to obtain a close gap with the radial protrusions or lands 26 and the grooves 28 of the shaft 10. Typically, the labyrinth seal ring segment installs a relatively large number of barriers, or teeth, for fluid flow from the high pressure region 16 on both sides of the seal to the low pressure region 18 so that each barrier pressurizes the fluid. It performs its function by following a winding path, causing a pressure drop to occur. The sum of the pressure drops over the labyrinth seal is defined as the pressure difference between the high and low pressure regions on both sides of its axial direction. This type of labyrinth toothed seal ring segment is typically springed back and freely moved radially in case of severe rotor-seal interference during operation. In certain configurations, the spring maintains the seal ring segment 20 radially outward from the rotor, for example during start up and stop, and fluid pressure is supplied between the seal ring segment and the cavity 30 in the rotor housing. The seal ring segment is displaced radially inward so that the gap with the rotor becomes smaller after the rotor reaches its maximum speed (ie, the seal is closed).

1 also shows a seal ring segment with a combination labyrinth / brush seal. As shown, the seal ring segments may each have a brush seal 32. The brush seal 32 may be provided into existing seal ring segments as original equipment or retrofit. Each brush seal includes a plurality of supports 34 for the long bristles 36. For example, the support 34 may include a pair of generally arcuate support plates 38, 40 on both axial sides of the bristles 36. Brush seal support 34 has an end face that is flush with the seal ring segment and lies along the same radial plane as the end face of the seal ring segment. The support plates are welded to each other along the radially outermost end, and the bristles are welded to each other and to the plate at the same location.

As best shown in FIG. 2, the support plate 38 located on the low pressure or downstream side of the brush seal acts as a support for the bristles 36. Preferably, the support plate 38 ends with a profile of tapered teeth 44 just before the distal end of the bristles 36. Thus, the ends of the bristles 36 are intended to press and engage the rotating element, ie the surface of the shaft 10, wherein the teeth 44 are additional labyrinth seal teeth that support the bristles 36 spaced apart from the shaft. Act as. The upstream or high pressure front plate 40 is spaced apart from the upstream side of the bristles 36. This space allows the bristles to deflect when engaged with the rotating surface.

In the formation of a brush seal, the bristles are typically placed on top of the annular ring which ultimately acts as a support plate for the bristles and the front plate is placed on top of the bristles. The annular plate with bristles interposed therebetween is then welded along the radially outermost edge and the annular support plate / bristle / front plate is divided into the same number of segments as the seal ring segments along the radial end surface. It will be appreciated that the bristles are arranged deviate from the radius of the plate at a predetermined angle between the plates. When the annular brush seal ring is cut, it is cut along a radius that removes a portion of the bristles, otherwise this portion of the bristles extends from the end face of one bristle segment to the opposite end face of the adjacent bristle segment, FIG. 7. And a triangular region of adjacent bristle segments, in which adjacent bristles do not extend, as shown at 46 in FIG. 8. However, when the brush segments are fixed to the seal ring segments, the profiled support teeth 44 act as seals in these areas without bristles.

Referring again to FIG. 1, the seal ring segment may be provided in original equipment or retrofit with grooves or slots 48 for receiving the brush seal segment. The groove 48 is shown to be in a generally central position between the axial ends of the seal ring segment, but in combination with the labyrinth seal teeth of the seal segment and also in an axial position along the other seal surface 22 as shown. One or more grooves may be provided in the seal ring segment along the axial length of the seal to provide more brush seals.

1 and 3, the grooves 48 formed in the seal ring segment have a base that defines a parallel side wall and an arcuate slot for receiving the brush segment. The brush segment is disposed in the groove 48 and the front plate 40 faces the upstream direction. To restrain the brush seal in the slot, one or more welds are provided along the joint of the brush seal segment and the surface adjacent the groove 48. The weld is indicated by reference numeral 50 in FIG. 7. That is, a stitch weld is provided along the sides of the brush segment at the junction with the surface 22 of the seal ring segment 20 to maintain the brush seal against radial and circumferential motion relative to the seal ring segment. do.

Referring to the embodiment shown in FIG. 4, the grooves 48 in the seal ring segment have recesses 60 extending axially outward from the surface 22, through which the grooves 48 are opened. do. In this form, the brush seal segment comprises a support plate 38a having a bristles 36 and a tooth profile 44a. However, the upstream plate 40a may have a protruding tongue 62 for receiving in the recess 60. By sliding the brush seal segment circumferentially in the groove 48, it will be appreciated that the tongue 62 engaged in the recess 60 prevents the radial movement of the brush segment relative to the seal ring segment. In Fig. 5, the groove 60b is formed on the opposite side in the axial direction, i.e., the downstream side, and the tongue 62b of the brush segment may be formed on the supporting plate 38b rather than the upstream plate as shown in Fig. 4. In all cases, tongue and recess alignment of the brush seal within the seal ring segment prevents radial movement of the brush seal segment and the seal ring segment.

To prevent the circumferential relative movement of the brush segment and the seal ring segment, the brush segment and the seal ring segment are welded to each other adjacent one or both of the opposing end faces. To achieve this, it will be appreciated that the end face of the brush seal comprising the support plate lies in the same plane along the radial end plane of the seal ring segment. An opening is formed in at least one end face of the seal ring segment and through one of the brush seal plates. For limited tangential distance, it is preferred that holes 66, preferably circular holes, be drilled through the support plate in at least one end face of the seal ring segment. By filling the holes at one or both ends of the seal ring segment with welding material, the brush segment and the seal ring segment are joined together to prevent circumferential relative motion.

While the present invention has been described with respect to embodiments which are presently considered to be the most practical and good, the invention is not intended to be limited to the disclosed embodiments but is intended to cover various modifications and equivalent arrangements falling within the spirit and scope of the appended claims. do.

Claims (13)

In a rotating mechanism having a rotatable element lying about a common axis and an element fixed for rotation and a seal provided between the elements, the seal is: An elongated arcuate seal ring segment supported by the securing element and having an arcuate surface opposite the rotating element; At least one labyrinth seal tooth projecting generally radially from the seal ring segment towards the rotating element, wherein the seal ring segment surface is axially spaced from the seal tooth and opened radially inward of the segment surface The labyrinth seal tooth having a groove, A brush seal disposed in the groove and comprising a plurality of bristles and a support for bristles, the bristles fixed in the support and projecting therefrom beyond the support and the segment surface to engage the rotating element, the groove and the The seal ring segment includes an arcuate recess extending in one axial direction radially outward of the surface, wherein the support is received in the recess to prevent movement of the support radially inward with respect to the seal ring segment. And the seal ring segment and the support have end faces adjacent to each other at one circumferential end of the seal ring segment, and a welding material is attached to the end face to provide grooves for the seal ring segment. To prevent the circumferential movement of the support within , Including the brush seal seal. The method of claim 1, The support comprises a pair of plates lying on both axial sides of the bristles, at least a portion of one of the plates being axially spaced from the bristles such that a portion of the bristle is spaced while engaging the rotating element. Deflected into seal. delete delete delete The method of claim 1, An opening extending generally tangentially in one end of the seal ring segment to expose a portion of the face through the one segment end, wherein the welding material is disposed in the opening. seal. delete The method of claim 1, A weld along each side of the surface and the support to secure the support to circumferential and radial motion within the groove. seal. The method of claim 8, A plurality of welds along each of the opposite ends of the support to secure the support and the surface to each other while the brush seal is in the groove. seal. The method of claim 8, The support includes a pair of plates lying on both axial sides of the bristles, at least a portion of one of the plates axially spaced from the bristles so that the space while the portion of the bristles is engaged with the rotating element. To be deflected into seal.  A rotatable element lying about a common axis and fixed against rotation, the labyrinth seal between the elements being supported by one of the elements and projecting generally radially towards the other of the elements 10. A method of forming a combined labyrinth and brush seal between said elements in a rotating mechanism comprising a plurality of teeth extending generally circumferentially for sealing between them. An array of circumferentially separated bristles so that the bristles lie in a plane generally perpendicular to the axis and the distal end thereof protrudes toward the other element past the radial region of the tooth to substantially seal the other element, By fixing to the one element, remodeling the array of bristles circumferentially separated from the teeth axially on the one element, wherein the step comprises the array of the one element and the bristles. Sliding circumferentially with respect to each other and welding the array of bristles to the one element to prevent the one element and the array of bristles from radially moving relative to each other, and the one element and the array of bristles to each other Securing to circumferential sliding; The one element (sealing segment) and the array of bristles have end faces adjacent to each other at one end of the one element (sealing segment) and within the one end of the one element (sealing segment) the end of the one element (sealing segment) Forming an opening extending generally tangentially through the array of bristles and exposing a portion of the end faces of the one element (seal segment), The welding step includes placing a welding material in the opening to prevent circumferential movement of the brush seal and the one element with respect to each other. A method of forming combination labyrinth and brush seals. delete delete

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