JP2003262102A - Steam turbine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a steam turbine preventing steam leakage from a horizontal dividing surface of upper and lower half inner casings and an upper and lower nozzle boxes. <P>SOLUTION: This steam turbine comprises an outer casing 23 and an inner casing 24, each being halved by a horizontal dividing surface into an upper half part and a lower half part, obtaining dual configuration, and also comprises a steam chest 29 formed in the inner casing 24, having such a shape that supplied steam can be made to flow along the whole circumference. A seal strip 36 is fixed along the circumference of the steam chest formed in the inner casing 24. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a steam turbine, and more particularly to a steam turbine having an improved seal structure for a steam chamber installed on the inlet side of the first stage of the turbine.

[0002]

2. Description of the Related Art Generally, there are two methods for operating a steam turbine: a nozzle cutoff speed control operation and a throttle speed control operation.

In the former operating method, the turbine nozzles (nozzle plates) constituting the first paragraph of the turbine are divided into several groups, the steam control valves connected to the turbine nozzles of the divided groups are sequentially opened and closed, and the amount of inflowing steam is increased. Since the turbine output is adjusted while controlling the control, the turbine efficiency during the partial load operation is relatively higher than that in the throttle speed control operation.

On the other hand, the latter operating method adjusts the turbine output by changing the pressure while squeezing all the steam control valves connected to the turbine nozzle arranged annularly along the circumferential direction of the turbine rotor (turbine shaft). Therefore, the pressure loss is smaller than that in the nozzle shutoff operation, and the structure is simplified.

As shown in FIG. 15, the steam inlet portion of the steam turbine capable of the former operation is a pressure vessel having a dual structure of a turbine casing 1 having an outer casing 2 and an inner casing 3. The outer casing 2 and the inner casing 3 are each divided into two parts by a horizontal dividing plane HL, and the two divided head parts are referred to as an upper half outer casing 2a and an upper half inner casing 3a, and their bottom parts are respectively separated. Is divided into a lower half outer casing 2b and a lower half inner casing 3b.

The upper and lower half inner casings 3a, 3b are provided with steam chambers 5a, 5b, 5c, 5d formed toward the inlet side of the grouped turbine nozzles (nozzle plates) 4.

The steam chambers 5a to 5d are equipped with sleeves (expansion joint seals) 6a, 6b, 6c and 6d on the outside of the middle, and are provided in the upper and lower outer casings 2a and 2b of the steam inlet nozzles 7a and 7b. It is connected to 7c and 7d.

Further, the steam chambers 5a to 5d have a construction in which, for example, one steam chamber 5a and an adjacent steam chamber 5b are separated from each other by closing portions 8a and 8b.

On the other hand, as shown in FIG. 16, the steam inlet portion of the steam turbine capable of throttle-controlled operation is formed in the upper and lower inner casings 3a and 3b, and extends along the circumferential direction of the turbine rotor (not shown). A steam chamber 9 is provided on the inlet side of the turbine nozzle 4 in which the blades are arranged.

The steam chamber 9 is formed along the entire circumference of the turbine nozzles 4 arranged in an annular row, and a sleeve 10 is provided outside the middle of the steam chamber 9 to provide a steam inlet nozzle on the lower half outer casing 2b. It is connected to 14.

The steam turbine having the steam chamber 9 having the above-described structure has the steam inlet nozzle 14 of the lower half outer casing 2b.
Since the steam from the tank flows over the entire circumference, the structure is simplified and the pressure loss is small.

In a combined cycle power plant, which is becoming the mainstream of recent thermal power plants, more steam turbines capable of throttle-controlled operation are adopted. This point will now be described in more detail with reference to FIG. To do.
Note that, in FIG. 17, the lower half outer casing 2b and the lower half inner casing 3b are viewed from the horizontal dividing plane HL with the upper half outer casing 2a and the upper half inner casing 3a removed.
FIG.

The steam turbine has a lower half outer casing 2b.
In addition, the lower half inner casing 3b is engaged and fixed by interposing the protruding pieces 11a and 11b, and the turbine rotor (turbine shaft) 12 is provided at the central portion of the lower half inner casing 3b.
It is configured to accommodate.

Further, the steam turbine has a bolt hole 13 for connecting the upper half inner casing 3a to the lower half inner casing 3b, and a steam inlet pipe 14 shown by a chain line.
And an intermediate gland portion 15 for sealing the shaft with the turbine rotor 12.

The steam turbine faces the outlet side of the steam chamber 9 and has turbine ends (nozzle plate) 4 supported by a diaphragm outer ring 16 and a diaphragm inner ring 17 at both ends and a turbine rotor blade which is planted in a turbine rotor 12. It is provided with a turbine first paragraph 19 composed of 18 and. A turbine stage composed of turbine nozzles and turbine rotor blades has a plurality of stages along the axial direction of the turbine rotor 12, the steam energy is converted into velocity energy by the turbine nozzle 4, and the velocity energy is given to the turbine rotor blades 18. The turbine rotor 12 is rotated by a rotating shaft, and the power generated during the rotation drives a generator (not shown).

In the steam turbine, when the upper half inner casing is connected to the lower half inner casing 3b, bolts are inserted into the bolt holes 13 for airtight connection, and as shown in FIGS. 18 and 19. , Key 2 in the keyway 20
1 is installed, or as shown in FIG. 20, in addition to the outer casing 2 and the inner casing 3, the horizontal split surface HL is
A so-called triple structure pressure vessel provided with a nozzle box 22 having an upper half nozzle box 22a and a lower half nozzle box 22b to be divided is used, and steam supplied from the steam inlet pipe 14 to the turbine nozzle 4 via the steam chamber 9 is A structure that does not leak outside is also applied as necessary.

[0017]

A steam turbine provided with a pressure vessel having a dual structure of the outer casing 2 and the inner casing 3 shown in FIG. 16 and the outer casing 2, the inner casing 3 and the nozzle box 22 shown in FIG. In the steam turbine provided with the triple-structured pressure vessel of FIG. 15, there is no closed portion 8a, 8b between the one steam chamber 5a and the adjacent steam chamber 5b as shown in FIG. Since steam flows throughout, it has excellent characteristics with little pressure loss, but there are still some problems, one of which was steam leakage.

That is, in the steam turbine having the above-described structure of the steam inlet portion, as shown in FIG. 17, the turbine rotor 12 and the intermediate gland portion 15 are located on the inner diameter side of the upper and lower inner casings 3a and 3b. For some reason, the bolt holes 13 of the bolts connected to the upper half inner casing 3a are arranged mainly near the lower half outer casing 2b side. Because of this, steam turbines are the result of many years of use.
Due to the thermal influence, the airtightness-maintaining force between the upper half inner casing 3a and the lower half inner casing 3b becomes low, and the steam from the inner diameter side (turbine rotor side) of the steam chamber 9 toward the intermediate gland portion 15 via the horizontal dividing surface. As a result, steam that does not perform expansion work is generated due to steam leakage, and there was a problem that the turbine internal efficiency as designed could not be maintained.

As shown in FIGS. 18 and 20, the steam turbine is provided with a key 21 on the inner diameter side (turbine rotor side) of the steam chamber 9 to reinforce the airtightness maintaining force of the upper and lower inner casings 3a and 3b. As a result of long years of use, the airtightness maintaining ability of the upper and lower half inner casings also decreased, and steam leaked from the steam chamber 9 to the intermediate gland portion 15 via the horizontal dividing surface HL.

The present invention has been made under such circumstances, and an object of the present invention is to provide a steam turbine which prevents steam from leaking from the horizontal split surfaces of the upper and lower half inner casings and the upper and lower half nozzle boxes. .

[0021]

In order to achieve the above-mentioned object, a steam turbine according to the present invention has, as described in claim 1, a two-division of an upper half portion and a lower half portion in a horizontal dividing plane. In the steam turbine having a steam chamber formed in the inner casing and having a shape to flow the supplied steam over the entire circumference while having a double structure including an outer casing and an inner casing The seal piece is attached along the periphery of the formed steam chamber.

Further, in order to achieve the above object, the steam turbine according to the present invention has the following features.
It has a triple structure with an outer casing, an inner casing, and a nozzle box that divide the upper half portion and the lower half portion into two parts on the horizontal dividing surface, and the steam formed in the nozzle box is supplied over the entire circumference. In a steam turbine provided with a steam chamber having a shape of flowing through, a seal piece is attached along the periphery of the steam chamber formed in the nozzle box.

In order to achieve the above-mentioned object, the steam turbine according to the present invention has the following features.
The seal piece is formed in a circular shape with respect to the steam chamber.

In order to achieve the above-mentioned object, the steam turbine according to the present invention has the following features.
The seal piece is formed in a non-circular shape with respect to the steam chamber.

In order to achieve the above-mentioned object, the steam turbine according to the present invention has the following features.
The seal piece is formed in a non-circular shape having an opening for the steam chamber.

Further, in order to achieve the above object, the steam turbine according to the present invention has the following features.
The seal piece is formed by forming the seal piece into a C-shape.

In order to achieve the above-mentioned object, the steam turbine according to the present invention has the following features.
The seal piece has a W-shaped shape.

In order to achieve the above-mentioned object, the steam turbine according to the present invention has the following features.
The seal piece is formed by forming a meandering shape.

In order to achieve the above-mentioned object, the steam turbine according to the present invention has the following features.
When the seal piece is mounted in the sealing groove provided in the lower half portion of the inner casing, the opening is arranged so that the opening faces the steam chamber side.

Further, in order to achieve the above-mentioned object, the steam turbine according to the present invention has, as described in claim 10, a seal groove in which a seal piece is mounted, having an upper half portion and a lower half portion. A gap is formed on the steam chamber side of the horizontal division surface to be brought into contact.

In order to achieve the above-mentioned object, in the steam turbine according to the present invention, as described in claim 11, the sealing piece is provided in the lower half of the inner casing and the lower half of the nozzle box. It is arranged at a position that does not intersect the gap formed between either one and the turbine nozzle of the turbine stage.

Further, in order to achieve the above-mentioned object, the steam turbine according to the present invention is, as described in claim 12, in the steam turbine according to claim 1 or 2, the turbine operation constituting the first paragraph of the turbine. A passage is formed from a downstream side to an upstream side in a disk of a turbine rotor in which blades are planted.

Further, in order to achieve the above-mentioned object, the steam turbine according to the present invention has the passage provided with a steam scoop on the suction side as described in claim 13.

[0034]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of a steam turbine according to the present invention will be described below with reference to the drawings and the reference numerals attached to the drawings. The steam turbine according to the present invention is applied to a steam turbine having a shape including a steam chamber capable of so-called throttle control operation, in which supplied steam flows over the entire circumference of the steam chamber.

FIG. 1 shows a first steam turbine according to the present invention.
FIG. 3 is a schematic plan view of a lower half outer casing as seen from a horizontal dividing surface, showing an embodiment and removing the upper half outer casing from the upper and lower half outer casings.

In the steam turbine according to this embodiment, the outer casing 23 and the inner casing 24 are each divided into two by a horizontal dividing surface, and the upper half outer casing 23a, the lower half outer casing 23b and the upper half inner casing 24 are divided.
a, of the lower half inner casing 24b, the lower half outer casing 23b is projected to the lower half outer casing 23b and the lower half inner casing 24b is engaged and fixed through the pieces 25a and 25b, and the turbine rotor 26 is provided at the central portion of the lower half inner casing 24b. It is configured to accommodate.

Further, the steam turbine is provided with a bolt hole 27 for connecting the upper half inner casing 24a to the lower half inner casing 24b with a bolt, a steam chamber 29 connected to a steam inlet pipe 28 shown by a chain line, and a turbine rotor. 26 and an intermediate ground portion 15 for sealing the shaft.

The steam turbine is composed of a turbine nozzle 33 facing the outlet side of the steam chamber 29 and having both ends supported by a diaphragm outer ring 31 and a diaphragm inner ring 32 and a turbine rotor blade 34 planted in the turbine rotor 26. It is equipped with a turbine paragraph 35 for the first paragraph. A turbine stage including a turbine nozzle and turbine rotor blades is provided in a plurality of stages along the axial direction of the turbine rotor 26, the steam energy is converted into velocity energy by the turbine nozzle 33, and the velocity energy is applied to the turbine rotor blades 34. The turbine rotor 26 is rotated by an electric power generator, and the power generated during the rotation drives a generator (not shown).

In the steam turbine having such a structure, in this embodiment, a seal piece 36 made of, for example, metal and having elasticity is mounted along the periphery of the steam chamber 29. In addition, as the kind of metal used for the seal piece,
Since the steam temperature is around 500 ° C., it is desirable to manufacture it with a heat resistant material that can withstand such temperature.

The sealing piece 36, as shown in FIG.
The steam chamber 29 may be formed in a circular shape, or, as shown in FIG. 2, the steam chamber 29 may be formed in a non-circular shape such as a quadrilateral shape.

The sealing piece 36 is also applied to a steam turbine provided with a bridge 37 interposed between the steam chamber 29 and the turbine nozzle 33, as shown in FIG.

Generally, in the steam turbine, the turbine nozzle 33 is manufactured in a thin plate shape, and the bridge 37 may be installed at an appropriate position on the inlet side of the turbine nozzle 33 in order to guarantee the strength.

In this embodiment, the steam turbine having such a structure is also provided with the seal piece 36 to further improve the steam sealing property.

Further, the sealing piece 36 is, as shown in FIG. 6, a high-pressure steam turbine having a steam chamber 29 formed in an axially symmetrical shape with respect to the horizontal dividing surface HL, and as shown in FIG. The present invention is also applied to a high-pressure steam turbine including a steam chamber 29 formed in a non-symmetrical shape with respect to the split surface HL. Then, as shown in FIG. 8, the sealing piece 8 applied to these high-pressure steam turbines is formed along the circumference of the steam chamber 29 into, for example, a circular shape.

The seal piece 36 formed along the periphery of the steam chamber 29 shown in FIGS. 1, 2, 5 and 8 is provided between the lower half inner casing 24b and the turbine nozzle 33 at the first stage of the turbine. It is arranged at a position that does not intersect the formed gap.

Furthermore, the sealing piece 36 is also shown in FIG.
As shown in FIG. 0, the outer casing 23 and the inner casing 24 are provided, while the steam turbine is provided with a triple-structured pressure vessel that accommodates the nozzle box 38 that forms the steam chamber 29, and as shown in FIG. 11, a high-pressure turbine. Section and the intermediate-pressure turbine section are housed in one outer casing 23 and one inner casing 24, that is, a so-called high-intermediate-pressure integrated steam turbine, and as shown in FIG. 12, the high-pressure turbine section and the intermediate-pressure turbine section are integrated into one. The present invention is also applied to a high-intermediate-pressure integrated steam turbine including a pressure vessel having a so-called triple structure, which is housed in one outer casing 23 and one inner casing 24 and also houses a nozzle box 38 forming a steam chamber 29.

In the steam turbine shown in FIGS. 10, 11 and 12, each of the outer casing 23, the inner casing 24 and the nozzle box 38 is divided into horizontal division planes HL.
Upper half outer casing 23a, lower half outer casing 23
b, upper half inner casing 24a, lower half inner casing 2
4b, an upper half nozzle box 38a, and a lower half nozzle box 38b are divided into two parts, and bolt holes 27, 27a are used to connect each other with bolts.

Further, in the steam turbine shown in FIG. 10, the seal piece 36 is formed along the circumference of the steam chamber 29 in a non-circular closed shape.

In the steam turbine shown in FIGS. 11 and 12, the sealing piece 36 is formed in a non-circular shape having an opening along the circumference of the steam chamber 29.

Furthermore, as shown in FIGS. 8 and 10, the sealing piece 36 does not intersect with a gap formed between the lower half inner casing 24b or the lower half nozzle box 38b and the turbine nozzle 33 of the turbine stage 35. It is located in a position.

On the other hand, a seal piece 36 to be mounted in any one of the above-mentioned circular shape, non-circular shape and non-circular shape having an opening along the circumference of the steam chamber 29.
As shown in (a), (b), and (c) of FIG. 3, the shape is one of a C-shaped shape having an opening 39, a W-shaped shape, and a meandering shape. A molded product is selected.

In the steam turbine in which the seal piece 36 having such a shape, for example, a C-shape, is selected, as shown in FIG. 4A, one of the upper half inner casing 24a and the lower half inner casing 24b is selected. When mounting in the sealing groove 40 provided in the lower half inner casing 24b, or in the upper half nozzle box 38a and the lower half nozzle box 38b,
When mounted in the sealing groove 40 provided in the lower half nozzle box 38b, the opening 39 is arranged at a position facing the steam chamber 29 side. This is because when the steam leaks from the steam chamber 29 side through the horizontal dividing surface HL as a result of long-term use, the sealing piece 36 is pushed by the pressure of the steam flowing into the opening 39 of the C-shaped sealing piece 36. This is to prevent the steam from leaking to the outside through the horizontal dividing surface HL due to the bulging of the seal piece 36.

In addition, as shown in FIG. 4B, the steam turbine in which the W-shaped sealing piece 36 is selected has a lower half inner casing out of the upper half inner casing 24a and the lower half inner casing 24b. Seal groove 40 provided in 24b
When it is mounted on the steam chamber or when it is mounted on the sealing groove 40 provided in the lower half nozzle box 38b among the upper half nozzle box 38a and the lower half nozzle box 38b, the opening portion is the same as the above. If it is arranged at a position facing the 29 side, the seal piece 36 can be bulged by the pressure of the inflowing steam to prevent the steam from leaking out.

If the expansion force of the sealing piece 36 is used more effectively, as shown in FIG. 9, the steam chamber 29 of the horizontal dividing surface HL that brings the upper half portion and the lower half portion into contact with each other. It is preferable to provide a gap 41 on the side.

As described above, in this embodiment, the seal piece 36 is formed along the periphery of the steam chamber 29, and the expansion force of the formed seal piece 36 is utilized to make the upper half inner casing 24a and the lower half inner casing 24b. Since the leakage of steam from the connection surface with or the connection surface between the upper half nozzle box 38a and the lower half nozzle box 38b is prevented, the airtightness maintaining force of each connection surface is sufficiently secured due to structural or layout reasons. Even if it is not possible, it is possible to reliably prevent the steam from leaking.

FIG. 13 shows a second embodiment of the steam turbine according to the present invention, which is an upper and lower half inner casing 24.
Of the a and 24b, the upper half inner casing 24a is removed, and the lower half inner casing 24b viewed from the horizontal dividing surface HL
2 is a schematic plan view of FIG.

In the present embodiment, even if the seal piece 36 is mounted along the periphery of the steam chamber 29, the seal piece 3 may be removed for some reason.
In consideration of the case where steam leaks from No. 6, steam is discharged from the outlet side of the turbine rotor blade 34 toward the turbine nozzle 33 side to the disk 43 of the turbine rotor 26 in which the turbine rotor blade 34 of the turbine first paragraph 42 is planted. A passage 44 is provided for flowing.

The passage 44 is formed so as to be inclined from the turbine rotor blade outlet side toward the turbine nozzle 33 side, and the opening area thereof is gradually increased.

As described above, in this embodiment, the disk 43 of the turbine rotor 26 is inclined from the outlet side of the turbine rotor blade 34 of the turbine first stage 42 toward the turbine nozzle 33 side, and the opening area is gradually increased. Enlarged passage 44
Is provided and is supplied as cooling steam to the space 46a between the turbine nozzle 33 and the turbine rotor blade 34 of the turbine first paragraph 42 to cool the intermediate gland portion 30. Therefore, by any chance, from the steam chamber 29 via the seal piece 36. High-temperature, high-pressure steam is space 4
Even if the intermediate gland portion 30 leaks to 6a, it is possible to prevent the intermediate gland portion 30 from being deformed due to a high temperature, and the turbine rotor 26 can be stably operated.

In this embodiment, the turbine first paragraph 42
In the disk 43 of the turbine rotor 26 at
However, if the steam scoop 47 is provided on the suction side of the passage 44, a larger amount of steam for cooling is supplied to the space 46a.
And the intermediate ground part 30 can be cooled more effectively.

[0061]

As described above, in the steam turbine according to the present invention, the throttle chamber of the first stage of the turbine can be controlled, and the steam chamber having the shape in which the supplied steam flows over the entire circumference is divided into the horizontal division surfaces. Is divided into two parts, the upper half part and the lower half part, and a means for preventing the leakage of steam from the connecting surface between the upper half part and the lower half part, which is divided into two parts, is provided. Due to the circumstances, it is possible to prevent the steam from leaking even if there is a portion where the airtightness maintaining ability between the upper half portion and the lower half portion cannot be sufficiently secured.

Further, in the steam turbine according to the present invention, the steam chamber is divided into an upper half part and a lower half part by a horizontal dividing surface, and
Even if there is a means to prevent steam from leaking from the connecting surface between the upper and lower half parts, if steam leaks for any reason, the disk in the first paragraph of the turbine will be upstream from the downstream side. Since the means for supplying the cooling steam toward the side is provided, the turbine rotor can be stably operated without applying an excessive heat load to the intermediate gland portion.

[Brief description of drawings]

FIG. 1 is a schematic plan view showing a first embodiment of a steam turbine according to the present invention as seen from a horizontal division plane.

FIG. 2 is a schematic plan view showing a first application example of the first embodiment of the steam turbine according to the present invention as seen from a horizontal division plane.

3A and 3B are views showing the shape of a metal seal piece applied to a steam turbine according to the present invention, in which FIG. 3A is a C-shaped metal seal piece, and FIG. 3B is a W-shaped metal seal piece. , (C)
Shows a meander-shaped metal seal piece.

FIG. 4 is a view showing an application example in which the metal seal piece shown in FIG. 3 is mounted in a sealing groove of a lower half inner casing, (a) is a view of a C-shaped metal seal piece, and (b) is W. The figure of the metal seal piece of a mold shape.

FIG. 5 is a schematic plan view showing a second application example of the first embodiment of the steam turbine according to the present invention as seen from a horizontal division plane.

FIG. 6 is a schematic vertical sectional view showing a conventional steam turbine.

FIG. 7 is a schematic vertical sectional view showing a conventional steam turbine.

FIG. 8 is a schematic plan view showing a third application example of the first embodiment of the steam turbine according to the present invention as seen from a horizontal division plane.

9 is a diagram showing an application example in which the metal seal piece shown in FIG. 3 is mounted in a sealing groove of a lower half inner casing.

FIG. 10 is a schematic plan view showing a fourth application example of the first embodiment of the steam turbine according to the present invention as seen from a horizontal division plane.

FIG. 11 is a schematic plan view showing a fifth application example of the first embodiment of the steam turbine according to the present invention as seen from a horizontal division plane.

FIG. 12 is a schematic plan view showing a sixth application example in the first embodiment of the steam turbine according to the present invention as seen from a horizontal division plane.

FIG. 13 is a schematic plan view showing a second embodiment of a steam turbine according to the present invention as seen from a horizontal division plane.

FIG. 14 is a schematic plan view showing a third embodiment of the steam turbine according to the present invention as seen from a horizontal division plane.

FIG. 15 is a vertical cross-sectional view showing a steam inlet portion in a conventional steam turbine that can perform a nozzle shutoff speed control operation.

FIG. 16 is a vertical cross-sectional view showing a steam inlet portion of a conventional steam turbine capable of throttle-controlled operation.

FIG. 17 is a schematic plan view showing a lower half outer inner casing as seen from a horizontal division plane in a conventional steam turbine.

FIG. 18 is a schematic plan view showing a lower half outer inner casing as seen from a horizontal division plane in a conventional steam turbine.

19 is a partial view showing a connection surface between the upper half inner casing and the lower half inner casing in FIG.

FIG. 20 is a vertical cross-sectional view showing a steam inlet portion of another conventional steam turbine capable of throttle-controlled operation.

[Explanation of symbols]

1 turbine casing 2 External casing 2a Upper half outer casing 2b Lower half outer casing 3 Inner casing 3a Upper half inner casing 3b lower half inner casing 4 turbine nozzle 5a, 5b, 5c, 5d Steam chamber 6a, 6b, 6c, 6d sleeve 7a, 7b, 7c, 7d Steam inlet nozzle 8a, 8b closed part 9 steam room 10a, 10b sleeve 11a, 11b protruding piece 12 turbine rotor 13 bolt holes 14 Steam inlet pipe 15 Intermediate ground section 16 diaphragm outer ring 17 Diaphragm inner ring 18 turbine blades 19 turbine paragraph 20 keyway 21 key 22 nozzle box 22a Upper half nozzle box 22b Lower half nozzle box 23 External casing 23a Upper half outer casing 23b Lower half outer casing 24 Inner casing 24a Upper half inner casing 24b lower half inner casing 25a, 25b protruding piece 26 turbine rotor 27, 27a Bolt hole 28 Steam inlet pipe 29 Steam room 31 diaphragm outer ring 32 Diaphragm inner ring 33 turbine nozzle 34 turbine blades 35 turbine paragraph 36 Seal Piece 37 bridge 38 nozzle box 38a Upper half nozzle box 38b Lower half nozzle box 39 opening 40 Seal groove 41 Gap 42 turbine first paragraph 43 discs 44 passage 45 turbine paragraph 46a, 46b space 47 Steam Scoop

Claims (13)

[Claims] 1. A horizontal division plane having an upper half portion and a lower half portion.
A steam turbine having a dual structure including an outer casing and an inner casing to be divided and having a steam chamber formed in the inner casing to flow the supplied steam over the entire circumference thereof. A steam turbine in which a seal piece is attached along the periphery of a steam chamber formed in the steam turbine. 2. A horizontal division plane having an upper half portion and a lower half portion.
In a steam turbine having a steam chamber formed in the nozzle box and having a shape to flow the supplied steam over the entire circumference, in addition to a triple structure including an outer casing to be divided, an inner casing and a nozzle box, A steam turbine in which a sealing piece is attached along the periphery of a steam chamber formed in a nozzle box. 3. The steam turbine according to claim 1, wherein the sealing piece is formed in a circular shape with respect to the steam chamber. 4. The steam turbine according to claim 1, wherein the sealing piece is formed in a non-circular shape with respect to the steam chamber. 5. The steam turbine according to claim 1, wherein the sealing piece is formed in a non-circular shape having an opening for the steam chamber. 6. The steam turbine according to claim 1, wherein the sealing piece is formed into a C-shape. 7. The steam turbine according to claim 1, wherein the seal piece is formed into a W shape. 8. The steam turbine according to claim 1, wherein the sealing piece is formed into a meandering shape. 9. The steam turbine according to claim 1, wherein when the seal piece is mounted in a sealing groove provided in a lower half portion of the inner casing, the opening is arranged so as to face the steam chamber side. . 10. The steam according to claim 9, wherein the sealing groove in which the seal piece is mounted forms a gap on the steam chamber side of the horizontal dividing surface that abuts the upper half portion and the lower half portion. Turbine. 11. The seal piece is arranged at a position that does not intersect a gap formed between one of the lower half portion of the inner casing and the lower half portion of the nozzle box and the turbine nozzle of the turbine stage. The steam turbine according to claim 1, wherein the steam turbine is a steam turbine. 12. The steam turbine according to claim 1 or 2, wherein a passage is formed from a downstream side to an upstream side in a disk of a turbine rotor in which turbine moving blades constituting the first stage of the turbine are planted. And a steam turbine. 13. The steam turbine according to claim 12, wherein the passage is provided with a steam scoop on the suction side.