U.S. patent application number 09/736705 was filed with the patent office on 2002-06-20 for brush seal with positive adjustable clearance control.
This patent application is currently assigned to General Electric Company. Invention is credited to Aksit, Mahmut Faruk, Chupp, Raymond Edward, Dinc, Osman Saim, Zhou, Ming.
Application Number | 20020074729 09/736705 |
Document ID | / |
Family ID | 24960971 |
Filed Date | 2002-06-20 |
United States Patent
Application |
20020074729 |
Kind Code |
A1 |
Aksit, Mahmut Faruk ; et
al. |
June 20, 2002 |
Brush seal with positive adjustable clearance control
Abstract
The positions of brush seal segments are positively adjusted
relative to a housing carrying the brush seal segments and the
opposing sealing component by employing members formed of thermally
responsive material. The members are heated by heating elements
receiving controlled power. By increasing or decreasing the power
provided to the heating elements, the members are expanded or
contracted to move the brush seal segments toward or away from the
opposing sealing component.
Inventors: |
Aksit, Mahmut Faruk; (Troy,
NY) ; Dinc, Osman Saim; (Troy, NY) ; Chupp,
Raymond Edward; (Glenville, NY) ; Zhou, Ming;
(Schenectady, NY) |
Correspondence
Address: |
General Electric Company
CRD Patent Docket Rm 4A59
P.O. Box 8, Bldg. K-1 -Salamone
Schenectady
NY
12301
US
|
Assignee: |
General Electric Company
|
Family ID: |
24960971 |
Appl. No.: |
09/736705 |
Filed: |
December 15, 2000 |
Current U.S.
Class: |
277/355 |
Current CPC
Class: |
F16J 15/3288 20130101;
F16J 15/445 20130101 |
Class at
Publication: |
277/355 |
International
Class: |
F16J 015/44 |
Claims
What is claimed is:
1. Apparatus for minimizing fluid leakage between two components
separated by a gap, comprising: a brush seal carried by one of said
components for disposition between the two components and including
a plurality of bristles projecting from said brush seal and having
free ends terminating in bristle tips in engagement with the other
of said components so as to seal the gap between said components,
said brush seal being mounted for movement relative to said one
component and toward and away from said other component; and a
member disposed between said one component and said brush seal and
responsive to heat applied to said member so as to expand or
contract, when heat is applied or removed, respectively, thereby
displacing said brush seal relative to said one component toward or
away from said another component, respectively.
2. Apparatus according to claim 1 wherein said one component
includes a groove therein for receiving at least part of said brush
seal, said brush seal being movable in said groove toward and away
from said other component, said member being disposed in said
groove between said one component and said brush seal to expand or
contract in response to the heat applied or removed, respectively,
thereby displacing said brush seal relative to said one
component.
3. Apparatus according to claim 1 including a heating element for
applying heat to said member.
4. Apparatus according to claim 3 wherein said heating element
comprises an electrically actuated element, said apparatus further
including a circuit for controllably energizing said electrically
actuated heating element.
5. Apparatus according to claim 1 wherein said member is fixed to a
predetermined one of said components.
6. Apparatus according to claim 1 wherein said member is free of
fixation to both said components.
7. Apparatus according to claim 1 wherein said member is elongated
in the direction of displacement of said brush seal.
8. Apparatus according to claim 1 wherein said member is elongated
in a direction generally normal to the direction of displacement of
said brush seal.
9. In a rotary machine having a rotatable component and a component
fixed against rotation, said components being disposed about a
common axis, apparatus for adjustably sealing a gap between said
components, comprising: an arcuate brush seal segment carried by
one of said components, including a plurality of bristles
projecting from said one component and having free ends terminating
in bristle tips in engagement with the other of said components so
as to seal the gap between said components, said brush seal segment
being mounted for movement relative to said one component and
toward and away from said other component; and a member carried by
said one component for displacing said brush seal segment relative
to said other component and formed of a material responsive to heat
either applied to or removed from said member by expanding or
contracting, respectively, and thereby moving said brush seal
segment relative to said one component, so as to adjust clearance
between said brush seal and said other component.
10. Apparatus according to claim 9 including means for applying
heat to said member.
11. Apparatus according to claim 10 wherein said means for applying
heat comprises a heating element for heating said member and a
control for adjusting the magnitude of heat applied by said element
to said member.
12. Apparatus according to claim 9 wherein said member is fixed at
one end to said seal segment and at the other end to said one
component, said member being responsive to the heat applied thereto
or removed therefrom by expanding or contracting, respectively, to
displace said one end of the member relative to said other end to
move said brush seal segment relative to said one component.
13. Apparatus according to claim 10 wherein said heating element
comprises an electrically actuated element, and said apparatus
further including a circuit for controllably energizing said
electrically actuated heating element.
14. A method of positively controlling a brush seal position
relative to one of two components separated by a gap therebetween,
said brush seal being carried by said one of said components for
movement toward and away from the other of said components, said
brush seal having a plurality of bristles projecting therefrom and
terminating in bristle tips in engagement with said other of said
components, said method comprising the steps of: disposing a member
between said brush seal and said one component, said member being
formed of a thermally responsive material; and applying heat at
different temperatures to said thermally responsive member to
expand or contract said member and thereby move said brush seal
relative to said one component and toward or away from said other
component.
15. A method according to claim 14 including the steps of affixing
an electrically energized heating element to said member, and
controlling power provided to said heating element to heat said
member to the specified temperatures.
16. A method according to claim 15 wherein said one component
includes a groove therein for receiving the brush seal, and further
including the step of disposing said member in said groove between
said brush seal and said one component.
Description
BACKGROUND OF THE INVENTION
[0001] This invention relates generally to brush seals and more
particularly to apparatus and methods for positively adjusting
clearance between a brush seal and an opposing component against
which the brush seal bears to form the seal.
[0002] Brush seals are commonly used to minimize leakage through a
gap between parts or components which are to be sealed to one
another. For example, brush seals are commonly used in rotating
machinery such as steam and gas turbines used for power generation.
Typically, the brush seals minimize leakage between regions at
different pressures on opposite sides of the seal. As a specific
example, a steam turbine may employ a brush seal for minimizing
leakage of steam between a stationary component and a rotating
component such as a rotor.
[0003] While brush seals are discussed herein in a preferred
embodiment with respect to sealing between stationary and rotating
components, it will also be appreciated that brush seals can be
applied to seal components which are non-rotating and may be
irregularly shaped. For example, a brush seal may be used to seal
between a combustor transition piece and a sealing cap of a first
stage nozzle in a gas turbine. In a typical application of a brush
seal between stationary and rotating components, however, the brush
seal comprises a plurality of arcuate segments, each segment
conventionally including a pair of plates with a plurality of brush
bristles disposed between the plates. The plates and proximal ends
of the brush bristles between the plates are typically welded to
one another, forming a completed brush seal segment. Opposite ends
of the bristles project from between the plates, terminating in
free ends or tips engaging and forming a seal with the other
component, typically the rotating component. The arcuate brush seal
segments are typically disposed in a groove of the stationary
component and may have a spring between the component and the
segment biasing the segment for movement between the opposing
sealing components, e.g., for movement toward the rotating
member.
[0004] It has been found, however, that because of stack-up
tolerances and machine-to-machine variations, it is very difficult
to achieve accurate clearance control, even with brush bristles
biased by a spring toward the opposing sealing component. Also, it
is common that for the same machine, the sealing clearance may be
different from the bottom half to the upper half of the machine.
For example, gravity affects the brush seal segments in the
semi-circular upper and lower casings of a steam turbine tending to
engage and disengage, respectively, the bristle tips relative to
the rotor. These operating clearance variations result in
performance changes in different applications. Additionally, brush
seal leakage performance also tends to degrade with time and
progressive bristle wear.
BRIEF SUMMARY OF THE INVENTION
[0005] In accordance with a preferred embodiment of the invention,
an adjustable clearance brush seal is provided wherein the sealing
clearance between the parts or components being sealed may be
positively controlled, particularly during operation of the
associated machine, and from locations external to the machine. For
example, the brush seal may be provided in arcuate brush seal
segments disposed in a groove of a stationary component with the
bristles in opposition to, and engaging, the rotating component.
The seal clearance between the bristles and the opposing component
can be positively controlled. The seal clearance is the degree of
interference between the brush bristles and the opposing sealing
component, as well as any gap between the tips of the bristles and
the associated sealing component, e.g., where it may be desired to
maintain a gap permitting flow between opposite sides of the seal.
To accomplish the foregoing, a member or members formed of a
thermally expansible or contractible material are disposed in
controlling relation to the brush seal in the component carrying
the brush seal to control the location of the brush seal vis-a-vis
the seal component engaged by the bristle tips. For example, each
member may comprise one or more pins or sleeves carried by the
stationary component and disposed in the groove between the
stationary component and the brush seal to extend in a generally
radial direction. Upon application of heat to the thermal material
of the members, the members tend to elongate, displacing the brush
seal segment radially toward the opposing seal component.
Conversely, when the temperature of the members is lowered, any
interference between the opposing seal component and the bristles
of the brush seal tend to displace the brush seal segment in an
opposite direction toward the component in which the brush seal is
mounted. Consequently, the opposite ends of the members need not be
secured to either the component or the brush seal. Alternatively,
one or both ends of the members may be secured, for example, by
welding, to the component mounting the brush seal and to the brush
seal per se, whereby positive control of the brush seal can be
effected to move the brush seal in opposite directions responsive
to the differential heat applied to the members.
[0006] More particularly, and as noted previously, the members may
comprise pins or hollow sleeves having heating elements about the
pins or within the sleeves. The heating elements preferably
comprise electrically actuated elements which can be controlled
through suitable circuitry employing, for example, a rheostat. By
adjusting the rheostat to control the magnitude of the heat
supplied to the members, the members can be differentially expanded
or contracted. A still further alternative may comprise a
circumferentially extending member, e.g., a band, having a heating
element contained within the band or about the band for expanding
or contracting the band and, hence, displacing the brush seal
segment toward or away from its opposing seal component.
[0007] The members are formed of materials having a high thermal
coefficient of expansion and the electric heating elements may be
embedded in or about the materials. By increasing or decreasing the
power supplied to the heating elements, the pins or bands expand or
contract, respectively, moving the seal segments toward or away
from the opposing seal component, respectively. Consequently, the
user may adjust the power setting to achieve the desired clearance.
This also can be accomplished externally of the machine and while
the machine is in operation. A particular advantage of the
invention resides in elimination of a need for tight tolerances for
the seal and its mounting, thereby easing machining constraints and
reducing costs.
[0008] In a preferred embodiment of the invention, apparatus for
adjusting a seal between two components includes a brush seal
carried by one of the components for disposition between the two
components and having a plurality of bristles projecting from the
brush seal, with free ends of the bristles terminating in bristle
tips in engagement with the other of the components forming a seal
between the components. The brush seal is mounted for movement
relative to one component and toward and away from the other
component. A member disposed between the one component and the
brush seal is responsive to heat either applied thereto or removed,
by expanding or contracting, respectively, thereby displacing the
brush seal relative to the one component toward or away from the
other component, respectively.
[0009] In a further preferred embodiment, a rotary machine includes
a rotatable component and a component fixed against rotation, the
components being disposed about an axis, and a seal between the
components comprising an arcuate brush seal segment carried by one
of the components, including a plurality of bristles projecting
from the one component and having free ends terminating in bristle
tips in engagement with the other of the components, forming a seal
between the components. The brush seal segment is mounted for
movement relative to the one component and toward and away from the
other component. A member is carried by the one component for
displacing the brush seal segment relative to the other component
and is formed of a material thermally responsive to heat applied
differentially thereto by expanding or contracting and thus moving
the brush seal relative to the one component, thereby adjusting the
sealing clearance between the brush seal segment and the other
component.
[0010] In a still further preferred embodiment of the invention
there is provided in a seal between adjacent components including a
brush seal carried by one of the components for movement relative
to the one component toward and away from a second one of the
components, the brush seal having a plurality of projecting
bristles terminating in bristle tips in engagement with the second
one of the components, a method of positively controlling the brush
seal position relative to the one component comprising the steps of
disposing a member between the brush seal and the one component
which is formed of a thermally responsive material; and applying
heat at different temperatures to the member of thermally
responsive material to expand or contract the member and thereby
move the brush seal relative to the one component and toward or
away from the second component.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] FIG. 1 is a fragmentary cross-sectional view of a brush seal
between stationary and rotating components according to the prior
art;
[0012] FIG. 2 is a perspective view of the brush seal illustrated
in FIG. 1;
[0013] FIG. 3 is a fragmentary cross-sectional view illustrating a
positive adjustable clearance brush seal according to a preferred
embodiment of the invention and disposed between two components to
be sealed;
[0014] FIG. 4 is a perspective view similar to FIG. 2 illustrating
a thermally responsive material in conjunction with a brush seal
for positive clearance control according to a preferred embodiment
of the invention;
[0015] FIG. 5 is a view similar to FIG. 3 illustrating a further
preferred embodiment of the invention;
[0016] FIG. 6 is a view similar to FIG. 3 illustrating a still
further preferred embodiment of the invention; and
[0017] FIG. 7 is a view similar to FIG. 3 illustrating a further
preferred embodiment of the invention.
DETAILED DESCRIPTION OF THE INVENTION
[0018] FIG. 1 illustrates a brush seal 10, in accordance with the
prior art, for sealing between a first component, e.g., a
stationary component 12, and a second, rotatable component 14.
Brush seal 10 comprises a plurality of arcuate segments 16, each
having a pair of backing plates 18 and 20 enclosing therebetween a
plurality of bristles 22. The bristles are secured at their
proximal ends to the backing plates, for
[0019] FIG. 7 is a view similar to FIG. 3 illustrating a further
preferred embodiment of the invention.
DETAILED DESCRIPTION OF THE INVENTION
[0020] FIG. 1, illustrates a brush seal, 10, in accordance with the
prior art, for sealing between a first component, e.g., a
stationary component 12, and a second, rotatable component 14.
Brush seal 10 comprises a plurality of arcuate segments 16, each
having a pair of backing plates 18 and 20 enclosing therebetween a
plurality of bristles 22. The bristles are secured at their
proximal ends to the backing plates, for example, by welds 24. The
bristles extend from their proximal ends between backing plates 18
and 20 to project freely therefrom, terminating in bristle tips in
engagement with a surface of rotatable component 14. The bristles
generally extend radially of the rotatable component and are offset
from radii of that component generally in the direction of
rotation. The bristles are formed of metal or may be formed of
other material, such as ceramics. As shown in FIG. 2, one of the
backing plates 23 extends to a lesser radial extent than the
opposite backing plate 26. In the typical prior art brush seal
configurations illustrated in FIGS. 1 and 2, the brush seal segment
is disposed in a groove within stationary component 12 at a fixed
radial location with the bristle tips engaging the sealing surface
of rotatable component 14. Alternatively, the seal segment may be
disposed in a groove within the stationary component and displaced
under spring pressure toward or away from the rotating component.
However, in both instances, the position of the brush seal is not
achieved by positive control at the position or location of the
brush seal segment.
[0021] In a preferred embodiment of the invention illustrated in
FIGS. 3 and 4, each segment of a brush seal 30 comprises a pair of
backing plates 32 and 34, with bristles 36 disposed therebetween.
As in the prior art, the bristles are secured at their proximal
ends between the backing plates by suitable means, for example, a
weld 38. The bristles extend from the weld between the backing
plates, terminating in bristle tips 37 in engagement with the
surface to be sealed. contracts in the longitudinal direction of
the long axis of the sleeve, which axis is oriented in a radial
direction. For example, sleeve 41 may contain a heating element 44
connected in an electrical circuit including a power source 46 and
a controller for adjusting the magnitude of the power supplied to
heating element 44. The controller, for example, may comprise a
rheostat 48. Alternatively, other types of controls can be used for
controlling the power supplied to heating element 44 and hence the
magnitude of the heat applied to sleeve 41. Moreover, while the
heat applied to sleeve 41 is shown provided by an electrical
heating element, other sources of heat may be used to expand or
contract the sleeve. For example, a fluid thermal medium, such as
steam, may flow through or about the sleeve to expand the sleeve. A
lower temperature fluid medium may also be used, such as a
refrigerant, to contract the sleeve.
[0022] While the embodiment of FIG. 3 illustrates heating element
44 residing within sleeve 41, member 39 may comprise a solid
element, such as a pin 47 having heating element 44 disposed about
the pin, as illustrated in FIG. 5. Other elements of the preferred
embodiment hereof illustrated in FIG. 5 are denoted by like
reference numerals as in the preceding embodiment.
[0023] By increasing or decreasing power supplied to the heating
element, e.g. by adjusting rheostat 48, member 39 (or 47) is
expanded or contracted, respectively, moving or displacing the seal
segments in response thereto. For example, by increasing the power
supplied to heating element 44 within sleeve 41 of FIG. 3, the
sleeve is expanded in its axial direction and hence displaces the
brush seal segment in a radial direction toward rotatable component
14. If the ends of the members are not secured to stationary
component 12 or to the segments of brush seal 30, decreasing the
power supplied to heating element 44 still positively controls the
position of the brush seal segments because the engagement of
rotatable component 14 with the bristle tips tends to displace the
brush seal segments radially outwardly. Moreover, one or both ends
of the members (e.g. sleeves 41 of FIG. 3 or pins 47 of FIG. 5) can
be positively secured to the stationary component and/or the brush
seal. In either instance, positive control over the location of the
brush seal segments relative to the stationary component mounting
the brush seal segments is achieved by increasing or decreasing
power supplied to thermally expansible and contractible pins
47.
[0024] In another form of a preferred embodiment of the invention
illustrated in FIG. 6, heating elements 50 may be disposed within a
circumferentially extending member, e.g. a heating band 52, formed
of a thermally responsive material. The heating band preferably
resides in a space between brush seal segment 54 and the base of
groove 56 in the stationary component. Thus, band 52 extends
circumferentially between the brush seal segments and the base of
groove 56, and may extend the entire circumferential length of the
segments, or for only part of their length, or a plurality of band
segments, separated from one another, may be provided along the
circumference of the segments. Upon actuation of the heating
elements within band 52, the increase or decrease of power supplied
to the heating elements will respectively expand or contract band
52 in a radial direction to displace brush seal segments 54 in
groove 56, thereby positively adjusting the clearance between the
bristle tips and the surface of the rotatable component. One or
both of the radially opposite faces of the heating bands may be
secured to the stationary component and the power supplied to band
52 can be adjusted externally of the machine as in the preceding
embodiment.
[0025] In FIG. 7, a pair of bands 60, similar to band 52 shown in
FIG. 6, are located between hook portions 62 of the brush seal
segment and hooks 64 of groove 40. Heating elements 66 are disposed
within bands 60 and each band, like bands 52 of FIG. 6, may extend
in part or completely around the entire brush seal segment
circumferentially. Consequently, upon increasing or decreasing
power supplied to electrical elements 66, bands 52, formed of
thermally expansible and contractible material, will expand or
contract radially, respectively, causing the brush seal segments to
move in a radial direction. The radially opposed faces of bands 60
may be secured to hooks 64 and hook portions 62, respectively.
Alternatively, springs (not shown) may be disposed
circumferentially about groove 40 to bias the segments for movement
radially inwardly, the radial extent of bands 60 controlling the
position of the brush seal segments against the bias of the
spring.
[0026] It will be appreciated that the pins or bands need not be
secured to either the stationary component or the brush seal in
order to positively control the movement of the brush seal. For
example, when the pin of FIG. 5 or the band of FIG. 6 is expanded,
the brush seal is displaced radially inwardly. Upon decreasing the
power supplied to the heating element, the pin or band contracts in
a radial direction, providing a gap in which the interference
between the rotating component and bristles forces the brush seal
segment to move in a radially outward direction. The pins or bands,
however, can be fixed at one end or along one face, respectively,
to the stationary component or to the brush seal segment, or they
can be fixed to both the stationary component and the brush seal
segment at opposite ends or along opposite faces, respectively.
With both ends or both faces fixed, the brush seal segment follows
both the expanding and contracting movement of the pins or bands
without external assist.
[0027] While only certain preferred features of the invention have
been illustrated and described, many modifications and changes will
occur to those skilled in the art. It is, therefore, to be
understood that the appended claims are intended to cover all such
modifications and changes as fall within the true spirit of the
invention
* * * * *