Rotary kinetic fluid motors or pumps – With passage in blade – vane – shaft or rotary distributor...
Reexamination Certificate
2002-09-09
2004-08-03
Look, Edward K. (Department: 3745)
Rotary kinetic fluid motors or pumps
With passage in blade, vane, shaft or rotary distributor...
C416S09600A
Reexamination Certificate
active
06769867
ABSTRACT:
BACKGROUND OF THE INVENTION
1) Field of the Invention
This invention relates to a gas turbine which uses a coolant such as air and steam for cooling a dynamic blade. More specifically, this invention relates to a joint structure of a coolant flow passage in the gas turbine for coupling a flow passage for supplying a coolant from a rotor disk to the dynamic blade, a tube seal and the gas turbine.
2) Description of the Related Art
In order to increase thermal efficiency in the gas turbine, a technique in which steam is used as a coolant instead of the air, to cool hot members such as a dynamic blade, a rotor disk or a stationary blade of the gas turbine is now being used. This is due to the following reasons. That is, the specific heat at constant pressure of dry steam is cp=1.86 kJ/kgK under a standard condition, which is a value almost twice as large as the specific heat at constant pressure of the air, cp=1.00 kJ/kgK. Therefore, the steam has a large heat capacity as compared with the air of the same mass, and the endothermic effect thereof increases. Further, if the wet steam is used as a coolant, latent heat of vaporization of the wet portion can be used for cooling, and hence the endothermic effect thereof further increases. Therefore, when the steam is used for the coolant, the cooling efficiency can be increased than using the air, and hence the temperature of the combustion gas at the entrance of the turbine can be set high. As a result, the thermal efficiency can be improved.
In the conventional air cooling, air from the compressor has been used as a coolant for the dynamic and stationary blades of the turbine. However, if this compressed air is used for cooling, the work that can be taken out from the turbine decreases. Here, if steam is used instead of the air, the cooling air for the dynamic and stationary blades can be saved, and hence the work that can be recovered by the turbine increases by this amount, thereby the work that can be taken out from the turbine can be increased.
FIG. 8
is a cross section which shows a steam flow passage for supplying cooling steam to the dynamic blade of the turbine. The steam supplied to the hollow main spindle
800
of the turbine is guided to a steam supply pipe
801
heading radially outwards. Thereafter, this steam flows into a steam supply pipe
804
which goes axially through the vicinity of the outer periphery of a rotor disk
803
, and is supplied to a cooling flow passage (not shown) provided inside of the dynamic blade
805
.
FIG. 9
is a cross section which shows a joint structure of the coolant passage, which has been conventionally used for supplying or recovering the cooling steam from the rotor disk side to the dynamic blade side. As shown in this figure, the end
121
of the joint section
120
is formed into a spherical shape, and fitted into a coolant passage inlet
805
a
of a dynamic blade
805
, which is also formed into a spherical shape to fit in with the end. A protruding portion
120
a
is peripherally provided at the other end of the joint section
120
. When the other end of the joint section
120
is inserted into the coolant passage outlet
803
a
on the rotor disk
803
side, the top of the protruding portion
120
a
and the coolant passage outlet
803
a
abut against each other, which becomes a seal point
125
to prevent leakage of the coolant.
In Japanese Patent Application Laid-Open No. 2000-274261, there is disclosed a joint structure of a cooling passage, wherein a flange is formed at one end of a joint section, and inserted into a groove having the same cross section as that of the flange, provided at the root of a dynamic blade, to thereby connect a coolant flow passage. A spherical spring is provided at a portion where this joint portion is inserted into a cooling flow passage outlet formed in a rotor disk, and leakage of steam is prevented by the elastic force of this spring.
The end
121
of the joint section
120
is spherical and comes into face contact with a coolant inlet
805
a
of the dynamic blade
805
formed into a spherical shape which fits in together with the end, to prevent the steam from leaking. However, it is difficult to increase the machining accuracy of the face, and steam leaks slightly from this portion. Further, during operation of the gas turbine, the temperature of the joint structure portion of the cooling flow passage increases up to about 400° C. Therefore, the joint section
120
is manufactured from a metal material, and inserted into the coolant passage outlet
803
a
of the rotor disk
803
manufactured from a metal material as well. Therefore, a gap is always formed at the seal point
125
, causing a problem in that steam leaks from this gap. Since the amount of leakage of the steam is not so large, it is not a big problem so far. However, in order to increase the use efficiency of the steam, it is necessary to minimize the steam leakage in the seal portion.
The joint structure of a cooling passage disclosed in Japanese Unexamined Patent Publication No. 2000-274761 can correspond to the radial movement of the rotor disk. However, when a movement in the direction perpendicular to this radial direction occurs, if the movement is very small, this joint structure can correspond thereto, but if the movement is large, a gap is formed between the flange and the root of the dynamic blade, and hence causing a problem in that steam leaks from this gap.
SUMMARY OF THE INVENTION
It is an object of this invention to provide a joint structure of a cooling flow passage and a tube seal in a gas turbine, and a gas turbine, wherein wastage of steam is suppressed by reducing leakage of the steam, and even if the dynamic blade and the rotor disk move relative to each other, the seal performance can be maintained.
The joint structure of a coolant passage in a gas turbine according to one aspect of the present invention comprises a rotor disk having a first coolant passage port for supplying or recovering a coolant to or from a dynamic blade, the dynamic blade being fitted to the outer periphery of the rotor disk, a second coolant passage port provided at the root of the dynamic blade, and a tube seal having a tubular barrel, the end of the barrel inserted into the second coolant passage port being formed into a spherical shape, and the side of the barrel inserted into the first coolant passage port being provided with an elastic member which deforms in the radial direction of the barrel. The internal surface of the second coolant passage port and the spherical end of the tubular barrel come in line contact with each other.
Thus, the spherical end of the tube seal and the internal surface of the coolant passage port provided at the root of the dynamic blade into line contact with each other, to thereby suppress leakage of the coolant in this portion. At the coolant passage port on the rotor disk side, leakage of steam is suppressed by the spherical elastic member such as a spring provided on the tube seal barrel. Since the coolant passage port provided in the dynamic blade and the end of the tube seal barrel are brought into line contact with each other, leakage of the coolant can be suppressed, even if the machining accuracy in this portion is not so high. Further, in the coolant passage on the rotor disk side, the seal performance is maintained by the elastic member, and vibrations can be absorbed by a damping action of this elastic member. Therefore, stable sealing effect can be maintained not only on the rotor disk side but also in the coolant passage on the dynamic blade side.
Since the end of the tube seal barrel is formed into a spherical shape, it endures large centrifugal force acting thereon due to the rotation of the rotor disk, and the seal performance of this portion can be maintained. Even when the dynamic blade and the rotor disk shift from each other and the tube seal inclines, the seal performance can be maintained by the spherically formed end of the tube seal barrel and the elastic member provided on the tube seal barrel. At this time, since the
Ohya Takeaki
Uematsu Kazuo
Kershteyn Igor
Look Edward K.
Mitsubishi Heavy Industries Ltd.
Oblon & Spivak, McClelland, Maier & Neustadt P.C.
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