Rotary kinetic fluid motors or pumps – With passage in blade – vane – shaft or rotary distributor...
Reexamination Certificate
2001-11-20
2003-05-20
Look, Edward K. (Department: 3745)
Rotary kinetic fluid motors or pumps
With passage in blade, vane, shaft or rotary distributor...
C415S096000, C415S097000
Reexamination Certificate
active
06565311
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a seal structure of a steam passage between a blade ring and a stationary blade of a steam cooled type gas turbine, that is so structured that cooling steam, flowing in a cooling steam supply passage and return passage, is prevented from leaking from a steam shield connection portion of the blade ring and a fitting portion of the stationary blade.
2. Description of the Prior Art
The recent combined cycle power plant (herein simply referred to as “the plant”) is in the tendency that a gas turbine thereof is operated at a higher temperature for realizing a higher efficiency of the plant and, in order to improve the thermal efficiency, such a gas turbine as uses steam, instead of air, as cooling medium for cooling a gas turbine blade and the like is being developed.
In such a steam cooled type gas turbine, the steam for cooling the gas turbine blade and the like, flowing in a seal structure of a steam passage between a blade ring and a stationary blade (herein simply referred to as “the seal structure”), is not discharged into main flow gas as combustion gas but cooling heat of the gas turbine blade and the like is recovered into a steam turbine of the plant, thereby increasing output of the entire plant. Also, by suppressing blowing quantity of the cooling medium into the combustion gas that drives the gas turbine blade, temperature lowering of the combustion gas is prevented and the gas turbine efficiency is enhanced and thus the efficiency of the entire plant can be enhanced.
In the plant described above, the cooling steam used as the cooling medium is usually of a pressure higher than the atmospheric pressure and needs to be shielded against the atmospheric pressure to be supplied into the gas turbine interior.
Also, in order to enhance the output of the entire plant by recovering the cooling steam into the steam turbine, it is necessary to make cooling steam passages, provided in the outer and inner blade rings and the stationary blade of the gas turbine, in a closed form.
A prior art seal structure made in such a closed form will be described with reference to an example shown in FIG.
7
. While this example has been originally designed to use compressed air as cooling medium, it is modified so as to use cooling steam for cooling the steam cooled type gas turbine.
As used herein, the term “outer, or inner, circumferential side” means the outer, or inner, circumferential side in a rotor radial direction of the gas turbine or, in other words, “the upper, or lower, side” as seen in the respective figures appended herein.
As shown in
FIG. 7
, in the prior art seal structure, cooling steam is supplied from outside (not shown) into a blade ring
10
to flow through a steam shield connection portion
21
and a blade ring cooling steam supply passage
30
, that is provided in the blade ring
10
, and cools the blade ring
10
. Then, the cooling steam flows through a seal pipe
25
to enter a stationary blade
50
. The seal pipe
25
is of a hollow cylindrical shape having at one end a flange portion
26
and is provided in a cooling steam supply passage connection portion between the blade ring cooling steam supply passage
30
and a stationary blade cooling steam supply passage
39
, that is provided in the stationary blade
50
. While flowing through the stationary blade cooling steam supply passage
39
, the cooling steam cools the stationary blade
50
and, having been used for the cooling, it is recovered outside of the blade ring
10
through a cooling steam return passage (not shown), that is provided to pass through the blade ring
10
.
When the cooling steam enters the steam shield connection portion
21
, it is of a temperature of about 200 to 300° C. and when the cooling steam returns to the cooling steam return passage, it is heated to a temperature of about 500 to 600° C., that is elevated by cooling the blade ring
10
and the stationary blade
50
.
Thus, in the portions through which the cooling steam flows, there are caused thermal deformations in the rotor axial, radial and circumferential directions by the heat of the steam and it is needed to provide there such a steam passage seal structure that is able to absorb the thermal deformations. That is, the prior art seal structure, as shown in
FIG. 7
, is made such that, in a fitting portion of the stationary blade
50
to the blade ring
10
, the blade ring cooling steam supply passage
30
and the stationary blade cooling steam supply passage
39
are connected together at a shroud
42
, that is provided around a periphery of the fitting portion of the stationary blade
50
and is fastened by a bolt
41
. Thereby, a seal is effected at the flange portion
26
by a metal seal ring
70
a
′,
70
b
′ but, in this seal structure, there is still a problem that minute gaps arise in the cooling steam supply passage connection portion due to the thermal deformation to cause a steam leakage.
SUMMARY OF THE INVENTION
In order to solve the problem in the prior art to cause the steam leakage at the connection portion between the blade ring cooling steam supply passage and the stationary blade cooling steam supply passage, it is an object of the present invention to provide a seal structure of a cooling steam supply passage connection portion between a blade ring and a stationary blade of a steam cooled type gas turbine that is able to greatly enhance the sealing ability and to largely advance the realizability of a steam cooled blade ring and stationary blade. In addition to this, it is also an object of the present invention to provide a like seal structure of a cooling steam return passage provided in the blade ring and the stationary blade.
In order to achieve the mentioned objects, the present invention provides the means of the following inventions (1) to (13), wherein the inventions (2) to (13) are based on the invention (1), and functions and effects of the respective inventions (1) to (13) will be described in items (a) to (m).
(1) As a first one of the present invention, a gas turbine steam passage seal structure between a blade ring and a stationary blade, comprises: a blade ring steam passage hole provided in the blade ring so as to have its one end communicated with a steam passage chamber of the blade ring, the blade ring steam passage hole having a stepped portion formed in a middle portion thereof; a stationary blade steam passage hole provided in the stationary blade so as to oppose the other end of the blade ring steam passage hole, the stationary blade steam passage hole having a stepped portion formed in a stationary blade outer peripheral portion thereof; and a cooling steam supply passage connection portion constructed comprising a seal pipe of a hollow cylindrical shape provided between the blade ring steam passage hole and the stationary blade steam passage hole so as to communicate them with each other and a seal urging guide device provided at each of the stepped portions of the blade ring steam passage hole and the stationary blade steam passage hole so as to effect a seal of the cooling steam supply passage connection portion while fixedly supporting the seal pipe.
(a) By the above construction, even if the blade ring and the stationary blade make deformations by the heat of the steam, the steam passages in the cooling steam supply passage connection portion between the blade ring and the stationary blade have a flexibility to elongate and contract in the rotor axial, radial and circumferential directions. Thereby, the deformations due to the heat of the steam are absorbed and also steam leakage through minute gaps in the cooling steam supply passage connection portion can be prevented so that drive force of the steam turbine using the recovery steam may be increased. Also, temperature lowering of the combustion gas due to the inflow of the leaking steam is avoided so that drive force of the gas turbine may be increased and the thermal efficiency of the combined cycle power generation plant can be imp
Hirokawa Kazuharu
Kunitake Nobuhiro
Oya Takeaki
Tanioka Tadateru
Look Edward K.
McAleenan James M
Mitsubishi Heavy Industries Ltd.
Wenderoth , Lind & Ponack, L.L.P.
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