Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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GAS TURBINE SEAL APPARATUS
BACKGROUND OF THE INVENTION
Field of the Invention
This invention relates to a gas turbine seal apparatus for
preventing a leakage of sealing/cooling medium with a high accuracy.
Description of the Prior Art
A conventional sealing apparatus will be described with
reference to FIGs. 6 and 7. FIG. 6 shows a schematic sectional view of
a gas turbine. In the gas turbine, a moving blade 4 mounted on a disc 3
is rotated at a high speecl by a high temperature main flow gas 1
supplied from a combustor (not shown) so as to drive a generator
connected thereto producing electric power.
In the gas turbine, a seal portion such as a buffle plate seal 5,
labyrinth seal 6 or the like is disposed in a predetermined gap so as
to prevent a high pressure air or high temperature steam used as a
sealing/ccoling medium 2 from leaking into the main flow gas 1.
FIG. 7(a) shows a portion of the discs 3 arranged adjacent to
each other and having a seal portion disposed therebetween. FIG. 7(b)
shows the buffle plate seal 5 which is a major portion of FIG. 7(a) in
enlargemen-t.
That: is, the labyrinth seal 6 and a single piece of the buffle
plate seal 5 are disposed between closely neighbouring portions of the
disc 3 adjacent to each other to prevent the sealing/cooling medium 2
supplied t,hrough an axial hole provided in the disc 3 from leaking
through a cavity 7 between the moving blade and the stationary blade
into the high temperature main flow gas 1 as shown by stream lines 8 and
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9 indica-ted by arrows. As a result, this portion is sealed.
However, because the conventional seal apparatus is so
construc-ted that only a single buffle plate seal 5 is disposed, leakage
of the sealing/cooling medium 2 of a high pressure air or high
temperature steam caused at this portion indicated by the stream line
becomes ]arge.
This leaking sealing/cooling medium 2 advances further and mixes
into the high temperature rnain flow gas 1 as indicated by the stream
line 9, so that a large loss occurs in terms of a turbine aerodynamic
performance and a gas turbine cycle thermal efficiency.
In recent years, the pressure ratio of the gas turbine has been
increasecl and a higher pressure steam (several tens atm) has been more
often used as the sealing/cooling medium 2. Thus, unless the leakage
at this portion is blocked, a target efficiency of a plant cannot be
achieved.
SUMMARY OF THE INVENTION
The present invention has been proposed to solve the problem
described above and it therefore is an object of the invention to
provide a seal apparatus capable of suppressing leakage of the
sealing/cooling medium with a simple structure so as to contribute to
improvement of the efficiency of the plant.
To achieve the above object, the present invention provides a
gas turbine seal apparatus comprising a seal portion disposed between
adjacent turbine rotor discs for a sealing/cooling medium not to leak
into a main flow gas, the seal portion being constructed in multi-stages
by dispos.ng a seal plate in each of a plurality of mounting grooves
disposed in a radius direction. Because of such a multi-stage seal
portion in which the seal plate is disposed in each of the plurality of
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the mounting grooves, a pressure ratio applied to one seal plate is
dispersecl in several fractional parts, so that a secure sealing can be
achieved.
Further, according to another aspect, the present invention
provides a gas turbine seal apparatus comprising a seal portion disposecl
between adjacent turbine rotor discs for a sealing/cooling medium not
to leak into a main flow gas, the seal portion being constructed in a
single-stage or multi-stages by disposing an annular seal pin in a
single one-side tapered groove or in each of a plurality of one-side
tapered grooves, each said ~roove having an inclined outer wall. As
a result, the seal pin is disposed in the one-side tapered groove having
the inclined outer wall, sc that the seal pin is pressed strongly to
the radius direction because of a centrifugal force and a differential
pressure. Thus, the seal pin seals each gap in the radius direction
between the adjacent discs, thereby providing a secure sealing
performance. This one-side tapered groove may be constructed in a
single-stage, but by providing it in multi-stages, the sealing
performance can be further raised.
Further, according to still another aspect, the present
invention provides a gas turbine seal apparatus, wherein the seal plate
and the mounting groove, and the seal pin and the one-side tapered
groove, respectively, are applied to by an abrasion resistant coating.
By such abrasion resistant coatings, abrasion between the seal plate
and the mounting groove therefor, or the seal pin and the one-side
tapered groove in which the seal pin is disposed, is reduced and the
surface roughness of those coating portions is improved, so that a
smooth and slippery surface is provided, thereby the sealing
performance being further improved.
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BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 shows schematically a gas turbine seal apparatus
according to a first embodiment of the present invention, wherein FIG.
l(a) shows a portion of discs in which a seal portion is disposed
between adjacent discs and FTG. l(b) is an explanatory view for showing
a buffle plate seal which is a major portion of FIG. l(a);
FIG. 2 shows schematically a gas turbine seal apparatus
according to a second embodiment of the present invention, wherein FIG.
2(a) shows a portion of discs in which a seal portion is disposed
between adjacent discs and FIG. 2(b) is an explanatory view for showing
a seal portion comprising a one-side tapered groove and an annular seal
pin which is a major portion of FIG. 2(a);
FIG. 3 is an explanatory view showing an applied example in
which a pa.rt of FIG. 2 is modified;
FIG. 4 shows schematically a gas turbine seal apparatu,
according to a third embodiment of the present invention, indicating a
portion of~ discs in which a seal portion is disposed between adjacent
discs, in enlargement;
FIG. 5 is an explanatory view showing an applied example in
which a part of FIG. 4 is modified;
FIG. 6 shows a schematic sectional view of a conventional gas
turbine; and
FIG. 7 shows schemat:ically a conventional gas turbine seal.
apparatus, wherein FIG. 7(a) shows a portion of discs in which a
sealing portion is disposed between adjacent discs and FIG. 7(b) is an
explanato:ry view for showing a buffle plate seal which is a major
portion of FIG. 7(a).
DETAILED DE~SCRIPTION OF THE PREFERRED EMBODIMENTS
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A first embodiment Gf the present invention will be described
with reference to Fig. 1. FIG. l(a) shows partially a disc portion 3, 3
arranged adjacent to each other and having a seal portion disposed
therebetween. FIG. l(b) shows a buffle plate seal 5 which is a major
portion of FIG. l(a) in enlargement. Meanwhile, the same reference
numerals are attached to the same components as mentioned before and a
description thereof is omitted.
According to this embodiment, a plurality of mounting grooves 13
are provided in a turbine axial directional projecting portion of each
of a pair of discs 3, 3 adjacent to each other in the same direction
such that the mounting grooves 13 are arranged in multi-stages in
radius direction. In each of the mounting grooves 13 disposed is a
buffle plate seal 5a, 5b, 5c, 5d. Although a four-buffle plate type in
which four pieces of the buffle plate seal are provided has been shown
here, the number of the buffle plate seal is not restricted to four as
long as it is a multi-stage structure of two pieces or more and,
needless 1o day, it may be adjusted appropriately depending on a design
condition of a concrete apparatus.
According to this embodiment, because the aforementioned four-
piece structure buffle plate seals 5a, 5b, 5c, 5d are provided, each of
the buffle plate seals 5a, 5b, 5c, 5d jointly copes with a high pressure
air or high temperature steam supplied as the sealing/cooling medium 2.
Thus, the pressure applied to the buffle plate seals is dispersed so
that a pressure applied to each thereof is alleviated. As a result,
each seal has a surplus sealing capacity so that the sealing performance
becomes improved, thereby a secure sealing being carried out.
A second embodiment of the present invention will be describecl
according to FIGs. 2 and 3. Like FIG. 1 based on the first embodiment,
FIG. 2(a) shows partially a disc portion 3, 3 arranged adjacent to each
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other and having a seal portion disposed therebetween and FIG. 2(b)
shows a seal portion in which an annular seal pin 10 is disposed in a
one-side tapered groove 11 which is a major portion of FIG. 2(a) in
enlargement. Meanwhile, the same reference numerals are attached to
the same components as the pr-ior art described previously and the first
embodiment, and a description thereof is omitted.
According to this ernbodiment, a one-side tapered groove l:L
having its outer wall inclined outwardly is provided in a turbine
axial directional projecting portion of each of a pair of discs 3, 3
arranged adjacent to each other in the same direction. An annular seal
pin 10 is disposed in this one-side tapered groove 11.
Because the present embodiment is so structured as describecl
above, the seal pin 10 is pressed to the radius direction because of a
centrifugal force applied to the seal pin during operation, a
differential pressure between the inside and the outside of the seal pin
10 in the radius direction, etc. As a result, this seal pin seals a
gap between the discs 3 and 3 in the radius direction, thereby providing
a secure s,-aling performance.
FIG. 3 shows an applied example in which the present embodiment
is partially modified. That is, a plurality of the one-side tapered
grooves lla, llb, llc, lld are provided in the radius direction and the
seal pins lOa, lOb, lOc, lOd are disposed in the respective one-side
tapered grooves lla, llb,llc, lld, so that a multi-stage seal portion is
constructed.
Because of this multi-stage seal portion, the sealing function
is dispersed so that a load applied to each stage is alleviated. Thus,
each seal portion has a surplus potential thereby total sealing
performance being raised.
A third embodiment of the present invention will be described
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with reference to FIGs. 4 and 5. Because the third embodiment is a
modificat.ion of the major parts of the first and second embodiments, the
same reference numerals are attached to the same components as the
aforement.ioned embodiments and a description thereof is omitted.
According to this embodiment, if this is described comparing to
the aforementioned first embodiment, the buffle plate seal 5 and the
mounting groove 13 contai.ning it are applied to by an abrasion
resistant coating 12a of a ceramic material or chromium species material
as shown -Ln FIG. 4.
Likewise if this embodiment is compared to the aforementioned
second enbodiment, the surfaces of the seal pin 10 and the one-side
tapered groove 11 in which the seal pin 10 is disposed are applied to by
an abrasion resistant coating 12b of a ceramic material or chromium
species material as shown in FIG. 5.
According to this embodiment, by applying such coatings 12a, 12b,
abrasion between members which repeat contact and separation like the
buffle plate seal 5 and the mounting groove 13 is prevented so that the
service life of these components can be extended.
By applying the aforementioned coating to the surfaces of the
component members of the buffle plate seal 5 and the mounting groove 13
as well as Of the seal pin 10 and the one-side tapered groove 11, the
surface roughness is improved so as to be smooth and slippery, and the
close contactability between the respective components is improved so
that the sealing performance is largely intensified.
Although the embodiments of the present invention have been
described above, the present invention is not restricted to these
embodiments but it is needless to say that its concrete structure may be
modified in various ways within the scope of the claims of the
invention.
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Acc:ording to the present invention, because the gas turbine seal
apparatus comprises a seal portion disposed between adjacent turbine
rotor discs for a sealing/cooling medium not to leak into a main flow
gas and the seal portion is constructed in multi-stages by disposing a
seal plat:e in each of a plurality of mounting grooves disposed in a
radius direction, a pressure ratio applied to one seal plate is
dispersed in several fractional parts, so that a secure sealing can be
achieved and the gas turbine performance is enhanced remarkably.
Further, according to the invention of Claim 2, because the gas
turbine <,eal apparatus comprises a seal portion disposed between
adjacent turbine rotor discs for a sealing/cooling medium not to leak
into a main flow gas and the seal portion is constructed in a single-
stage or rnulti-stages by disposing an annular seal pin in a single one-
side tapered groove or in each of a plurality of one-side tapered
grooves, each said groove having an inclined outer wall, the seal pin
is pressed strongly to the radius direction because of a centrifugal
force and a differential pressure so as to provide a secure sealing
performance in the radius directional gap between the adjacent discs.
Further, if this one-side tapered groove is constructed in multi-
stages, lhe sealing performance can be further raised so as to
contribute to improving the turbine performance.
Further, according to the invention of Claim 3, the
aforementioned seal plate and mounting groove, and the aforementioned
seal pin and one-side tapered groove, respectively, are applied to by an
abrasion resistant coating, abrasion between the seal plate and the
mounting groove therefor, or the seal pin and the one-side tapered
groove in which the seal pin is disposed, is reduced so as to elongate
the life of these components and the surface roughness thereof is
improved so that a smooth and slippery surface is provided, thereby the
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sealing performance is further improved so as to contribute to
improving the turbine performance.
