Seal for a joint or juncture – Seal between relatively movable parts – Close proximity seal
Reexamination Certificate
1998-11-05
2001-03-27
Dayoan, B. (Department: 3626)
Seal for a joint or juncture
Seal between relatively movable parts
Close proximity seal
C277S421000
Reexamination Certificate
active
06206378
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention The present invention relates to a spindle bolt seal device for a gas turbine, which is constructed such that steam is used for cooling a gas turbine high temperature portions and is then recovered.
2. Description of the Prior Art A gas turbine, operating under high temperature conditions, is being developed with a recovery type steam cooled system in which steam is used for cooling of high temperature portions and, after used for the cooling, the steam is recovered.
In the recovery type steam cooled system, the steam that has been used for cooling and then recovered, is effectively used for performing another work, and thus preventing the steam from leaking uselessly before it is recovered leads to enhancement of the cycle efficiency. Moreover, if the steam for cooling mixes into a gas path of the gas turbine, there is a fear of lowering the performance of the gas turbine itself.
On the other hand, first to fourth stage discs and end rotors of the gas turbine are fastened so as to be connected to each other by a spindle bolt and an outlined structure thereof is shown in FIG.
7
. In
FIG. 7
, numeral
01
designates a first stage disc, which carries a first stage moving blade
04
, numeral
02
designates a second stage disc, which carries a second stage moving blade
05
and numeral
03
designates a third stage disc, which carries a third stage moving blade
06
.
Numeral
1
designates a spindle bolt, which passes through the discs
01
to
03
to connect them. Cooling steam flows into the respective moving blades from each of the discs, as shown by arrows, and is collected so as to be recovered into cavities formed between the discs.
In the prior art gas turbine, as shown in
FIG. 6
, no seal is provided for the spindle bolt
1
, but rather there is a clearance
9
between a disc
8
and the spindle bolt
1
in a bolthole
2
so as to be appropriate for cooling of the spindle bolt
1
. However, in the gas turbine which employs the recovery type steam cooled system, spaces between each of the discs
8
are filled with steam, hence there is a problem in that the steam leaks toward the upstream side through the clearance
9
between the disc
8
and the spindle bolt I to mix into the gas path.
SUMMARY OF THE INVENTION
In view of the problem with the prior art gas turbine having a recovery type steam cooled system, it is an object of the present invention to provide a gas turbine spindle bolt seal device that is able to reduce steam leakage from a turbine disc spindle bolt portion.
In order to attain said object, in a gas turbine spindle bolt seal device of the present invention, a seal hole is formed in a turbine disc portion through which a spindle bolt passes and in the seal hole, there are disposed a seal piece fitted around the spindle bolt and a seal piece cover for covering the seal piece. The seal piece is made of a material having a smaller coefficient of linear expansion than the spindle bolt.
Further, there is bored in the seal piece cover a pressure hole through which a high pressure side steam pressure is introduced into an inner side of the seal piece cover so as to urge the seal piece in the seal piece cover into contact with a sheet surface of the seal hole.
According to the gas turbine spindle bolt seal device of the present invention constructed as above, the seal piece disposed in the seal hole is urged into contact with the sheet surface of the seal hole due to the steam pressure, and thereby the steam is prevented from leaking along the sheet surface.
Also, the seal piece is made of a material having a smaller coefficient of linear expansion than the spindle bolt, and thereby the clearance between the seal piece and the spindle bolt becomes smaller in operation and the steam is prevented from leaking along the spindle bolt.
Further, in order to attain said object, the present invention provides a gas turbine spindle bolt seal device constructed such that a seal hole is formed in a turbine disc portion through which a spindle bolt passes and a seal piece is fitted around the spindle bolt in the seal hole. The seal piece is constructed by a ring portion, which is perpendicular to the spindle bolt, and a cylindrical portion, which is parallel with the spindle bolt.
According to the gas turbine spindle bolt seal device constructed as mentioned above, a terminal end of the cylindrical portion of the seal piece is urged into contact with the sheet surface of the seal hole due to a differential pressure and as the terminal end of the cylindrical portion has a narrow contact area, a strong urging force is obtained and the steam can be reliably prevented from leaking along the spindle bolt.
Also, in order to attain said object, the present invention provides a gas turbine spindle bolt seal device constructed such that a seal hole is formed in a turbine disc portion through which a spindle bolt passes and a ring-like seal piece is inserted into the seal hole. The ring-like seal piece is made of a material having a smaller coefficient of linear expansion than the spindle bolt.
In the gas turbine spindle bolt seal device constructed as above, the ring-like seal piece is urged into contact with the sheet surface of the seal hole by the steam pressure, and thereby the steam is prevented from leaking along the sheet surface of the seal hole. Also, the seal piece is made of a material having a smaller coefficient of linear expansion than the spindle bolt, and thereby the clearance between the seal piece and the spindle bolt becomes smaller in operation and the steam leakage along the spindle bolt is reduced.
In addition to the construction of the above gas turbine spindle bolt seal device, if an additional ring-like seal piece is provided in the seal hole, the additional ring-like seal piece is made of a material having a larger coefficient of linear expansion than a material of the turbine disc portion, and thus this arrangement will be preferable because the additional ring-like seal piece is expanded by heat in operation so as to make the clearance between this seal piece and the turbine disc portion smaller, and thereby a gas turbine spindle bolt seal having less steam leakage is realized.
REFERENCES:
patent: 3597024 (1971-08-01), Singelmann
patent: 4194745 (1980-03-01), McDougal
patent: 5037115 (1991-08-01), Brandon
patent: 5303936 (1994-04-01), Kuroki
patent: 5433453 (1995-07-01), Dalton
patent: 5628617 (1997-05-01), Dalton et al.
patent: 5794942 (1998-08-01), Vance et al.
patent: 5951250 (1999-09-01), Suenaga et al.
patent: 6019573 (2000-02-01), Uematsu et al.
patent: 6053701 (2000-04-01), Ichiryu et al.
patent: 1 309 350 (1973-03-01), None
Patent Abstracts of Japan, 09133005, May 20, 1997.
Nakamura Takeshi
Sakata Kaoru
Beres John L.
Dayoan B.
Mitsubishi Heavy Industries Ltd.
Wenderoth , Lind & Ponack, L.L.P.
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