Rotary kinetic fluid motors or pumps – With passage in blade – vane – shaft or rotary distributor...
Reexamination Certificate
1999-02-01
2001-11-13
Ryznic, John E. (Department: 3745)
Rotary kinetic fluid motors or pumps
With passage in blade, vane, shaft or rotary distributor...
Reexamination Certificate
active
06315518
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a stationary blade of a gas turbine, in which cooling can be performed effectively by means of a simple construction.
BACKGROUND ART
A hot section of a turbine blade of a gas turbine has conventionally been cooled by the discharged air or bleed air of a compressor, but it is contrived to cool a stationary blade of a gas turbine by using steam in place of air as one means for improving the gas turbine efficiency.
In the steam cooling of the stationary blade of gas turbine, the extraction steam of a steam turbine which constitutes a combined cycle in combination with the gas turbine is used, so that the steam pressure is usually high. Also, the leakage of steam in the gas turbine must be minimized for the reason of the steam-side cycle. Therefore, in the steam cooling of the stationary blade of gas turbine, the stationary blade is required
(1) to have a pressure resisting strength that withstand the steam pressure,
(2) to have a steam passage open to the outside and to have a supply port and a recovery port,
(3) to have a low thermal stress, and
(4) to be easy in manufacturing.
In the conventional stationary blade of gas turbine, as indicated by arrows in
FIGS. 3 and 4
, cooling steam enters the stationary blade of gas turbine through a cooling steam inlet
32
of an outside shroud
31
, and after passing through an impingement plate
39
, it goes through an inward cooling passage
34
provided in a blade portion
33
, and is turned at an inside shroud
35
. After that, the cooling steam passes through an outward cooling passage
36
provided in the blade portion
33
, and is recovered at a cooling steam outlet
37
.
Besides the aforementioned stationary blade of gas turbine, a stationary blade in which only the inside shroud is air-cooled has been proposed as disclosed in Japanese Patent Application No. 8-749 filed by the applicant of this invention. In Japanese Patent Application No. 8-749, as shown in
FIG. 3
, in addition to the aforementioned configuration, cooling air is introduced into the inside shroud
35
through a cooling air inlet
40
. The cooling air is allowed to flow through the impingement plate
39
to cool the inside shroud
35
. After cooling, the air is allowed to flow into a main gas flow F through a film cooling hole
38
provided in the inside shroud
35
to perform film cooling.
The present steam-cooled stationary blade of gas turbine is in the above-described state and certainly advantageous in terms of efficiency. However, its closed, long, and bent passage is complicated in construction, so that it is difficult to manufacture. In addition to this, if the wall thickness is increased to increase the pressure resisting strength, the whole blade becomes rigid, which poses a problem of disadvantage in terms of thermal stress.
The present invention was made to solve the above problems.
DISCLOSURE OF THE INVENTION
For the stationary blade of a gas turbine in accordance with the present invention, the following means were provided:
(1) An inside shroud and an outside shroud are air-cooled.
(2) A trailing edge portion of a blade portion, which is thin in shape, is air-cooled.
(3) In the present invention described in item (2), part of air which has cooled the trailing edge portion of the blade portion is discharged from the side of an inside shroud as inside seal air for a combustion gas passage.
In the aforementioned invention (1), the inside shroud and the outside shroud of the stationary blade of gas turbine is air-cooled, so that the construction can be simplified, and the occurrence of a local uncooled portion and resultant seizure can be prevented.
In the aforementioned invention (2), the trailing edge portion of the stationary blade of gas turbine, which is thin in shape for the aerodynamic reason, is air-cooled, so that this stationary blade is advantageous in terms of strength as compared with the case where high-pressure steam is used for cooling, and pin fin cooling can be performed.
In the aforementioned invention (3), part of air which has cooled the trailing edge portion of the blade portion is discharged from the side of an inside shroud in the aforementioned invention (2), so that the inside seal air for the combustion gas passage can be secured easily without making the construction complicated.
REFERENCES:
patent: 5120192 (1992-06-01), Ohtomo et al.
patent: 5320483 (1994-06-01), Cunha et al.
patent: 5340274 (1994-08-01), Cunha
patent: 5399065 (1995-03-01), Kudo et al.
patent: 5829245 (1998-11-01), McQuiggan et al.
patent: 5954475 (1999-09-01), Matsuura et al.
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patent: 06081675 (1994-03-01), None
patent: 08165902 (1996-06-01), None
patent: 09189203 (1997-07-01), None
patent: 09280002 (1997-10-01), None
patent: 09264103 (1997-10-01), None
patent: 10-37704 (1998-02-01), None
Suenaga Kiyoshi
Uematsu Kazuo
Alston & Bird LLP
Mitsubishi Heavy Industries Ltd.
Ryznic John E.
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