Fluid reaction surfaces (i.e. – impellers) – With heating – cooling or thermal insulation means
Patent
1997-07-08
1998-08-18
Kwon, John T.
Fluid reaction surfaces (i.e., impellers)
With heating, cooling or thermal insulation means
416 96R, F04D 2958
Patent
active
057951306
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a heat recovery type gas turbine rotor that is applicable to a blade cooling of a high temperature industrial gas turbine used in a combined plant etc.
2. Description of the Prior Art
Cooling of a conventional gas turbine moving blade is done in two ways, one being an air cooling type and the other being a recovery type by way of steam cooling.
In the air cooling type, as shown in FIG. 4, there is provided a cavity 8a between each disc 12 and also provided is a cavity connecting passage 20 connecting each said cavity 8a and connecting the cavity 8a and a front portion of a first stage disc. Thus, cooling air 14 is supplied from a leading edge portion of each stage moving blade 1 to 4 and, after cooling each said moving blade, is discharged into an interior of the turbine from a trailing edge portion 15 of each blade.
In the recovery type by way of steam cooling, as shown in FIG. 3, there is provided a cooling steam supply passage 13, within a rotor 5, extending from a rear portion of a fourth stage moving blade 4 to a leading edge portion of a first stage moving blade 1 and also provided is a cavity 8a between each disc 12. Further, a return passage 11 is provided extending rearwardly from the cavity 8a of the disc of the fourth stage moving blade so as to pass through this disc.
Also, in the portion of the first stage moving blade 1 to a third stage moving blade 3, flow passages are provided in series each so as to pass through a blade cooling passage 6 and the cavity 8a, starting from a front end portion of the cooling steam supply passage 13 via the disc of the first stage moving blade 1.
By use of said structure, cooling steam is supplied from the cooling steam supply passage 13 to cool the first stage moving blade 1 to the third stage moving blade 3 sequentially and returns through the return passage 11.
In said gas turbine blade of the air cooling type, compressor discharge air is used for the cooling, and cooling medium (air), after used, is discharged into the turbine. In a large capacity industrial gas turbine, however, use of a combined cycle plant in combination with a steam turbine is now a main tendency, and it is currently required that steam derived therefrom is made use of for cooling and heat obtained by the cooling is used for a steam cycle, thereby to enhance a combined cycle plant efficiency.
Also, in the recovery type by way of steam cooling in series as one system, there is such a problem that steam temperature in the latter stages becomes too high to cool the moving blades of the latter stages.
It is therefore an object of the present invention to dissolve said problems in the prior art.
SUMMARY OF THE INVENTION
In order to attain said object, the present invention provides a heat recovery type gas turbine rotor having multi-stage moving blades, each fitted to a disc, characterized in comprising: an inner cavity and an outer cavity provided between each said disc; a blade cooling passage erecting from a root portion of each of said moving blades except a rearmost stage moving blade and making U-turn at a tip portion thereof; a cooling steam supply passage extending from a rear portion of the rearmost stage moving blade to a leading edge portion of a foremost stage moving blade in said gas turbine rotor; a bifurcation passage provided in the disc portion of the foremost stage so as to connect at its proximal end to said cooling steam supply passage and to bifurcate at its distal end so that one bifurcation thereof connects to one end of said blade cooling passage and the other bifurcation connects to said outer cavity which is adjacent thereto; a blade return passage provided in the disc portion of the foremost stage so as to connect at its proximal end to the other end of said blade cooling passage and at its distal end to said inner cavity which is adjacent thereto; a cavity connecting passage for connecting each said inner cavity; a return passage extending along said cooling steam supply pas
REFERENCES:
patent: 4830575 (1989-05-01), Bandukwalla
patent: 5318404 (1994-06-01), Carreno et al.
patent: 5558496 (1996-09-01), Woodmansee et al.
patent: 5593274 (1997-01-01), Carreno et al.
patent: 5695319 (1997-12-01), Matsumoto et al.
Kasai Yoshikuni
Suenaga Kiyoshi
Kwon John T.
Mitsubishi Jukogyo Kabushiki Kaisha
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