On-off valve and steam turbine

An on-off valve of the present invention includes a valve box which includes an inlet flow path of steam and an outlet flow path which communicates with the inlet flow path through a communication bole, a stop valve body which opens or closes the communication hole, and a stop valve support portion, in which the outlet flow path extends in a direction intersecting the opening direction of the communication hole toward a downstream side in a flow direction of the steam, and a minimum wall thickness of the valve box is smaller than a minimum wall thickness of the valve box.

TECHNICAL FIELD

The present invention relates to an on-off valve provided in a steam flow path of a steam turbine.

Priority is claimed on Japanese Patent Application No. 2017-025964, filed on Feb. 15, 2017, the content of which is incorporated herein by reference.

BACKGROUND ART

In a steam turbine, moving blades and stationary blades are alternately arranged in a casing. A plurality of moving blades are provided on an outer peripheral surface of a rotary shaft rotating around an axis at interval in a circumferential direction of the rotary shaft. In addition, the stationary blades are fixed to the casing. In addition, main steam is supplied from a boiler into the casing to rotate the rotary shaft, and thus, for example, power is generated by a generator.

In the steam turbine, for example, an on-off valve is provided in a flow path through which the main steam is supplied from the boiler. Such an on-off valve is disclosed in PTL 1. In the on-off valve disclosed in PTL 1, a support shaft of a valve body is supported by a valve box at an inlet portion of the steam.

CITATION LIST

Patent Literature

SUMMARY OF INVENTION

Technical Problem

However, in the on-off valve disclosed in PTL1, a flow path of the inlet portion and a flow path of an outlet portion of the steam are disposed to be perpendicular to each other, and the support shaft supporting the valve body is, provided to penetrate the valve box. That is, a direction of the flow path is changed in the valve box, and the support shaft is provided at a position where the direction is changed. Accordingly, a flow of the steam stagnates at this position, and thus, there is a concern that heat transfer between a wall surface of the valve box and the steam decreases at the position of the stagnation. As a result, in the valve box, a position of a portion which is heated by steam and has a high temperature and a position of a portion to which heat is not sufficiently transferred by the steam and which has a low temperature occur. In addition, at the position having a relatively low temperature, a temperature gradient of the wall surface of the valve box increases, and thus, thermal deformation of the valve box becomes uneven. As a result, the support shaft may be bent due to the uneven deformation of the valve box, and thus, there is a possibility that the valve body is not correctly opened and closed.

Therefore, the present invention provides an on-off valve and a steam turbine capable of smoothly opening and closing the valve body by suppressing the uneven thermal deformation of the valve box.

Solution to Problem

The present invention adopts the following means in order to solve the above-described problems.

According to a first aspect of the present invention, there is provided an on-off valve including: a valve box which includes an inlet flow path of steam, and an outlet flow path which communicates with the inlet flow path through a communication hole on a downstream side in a flow direction of the steam; a valve body which is configured to open or close the communication hole; and a valve support portion which penetrates the valve box such that a portion of the valve support portion is disposed in the outlet flow path, is supported by the valve box on the outlet flow path side from the communication hole, and supports the valve body so as to be capable of operating the valve body in an opening direction of the communication hole, in which the outlet flow path extends in a direction intersecting the opening direction of the communication hole toward a downstream side, and a minimum wall thickness of the valve box on a side, which is positioned on a downstream side from the communication hole and is opposite to a side to which the outlet flow path extends across the valve support portion, is smaller than a minimum wall thickness of the valve box on an upstream side from the communication hole.

According to this on-off valve, the minimum wall thickness of the valve box on the outlet flow side becoming the downstream side of the communication hole and the side opposite to the side to which the outlet flow path extends across the valve support portion is smaller than the minimum wall thickness of the valve box on the inlet flow path side positioned on the upstream side of the communication hole. As a result, the thickness of the valve box can decrease at a position at which a direction of a flow path in the outlet flow path is changed and a position at which the flow of the steam stagnates around the valve support portion. Accordingly, for example, particularly, when the steam turbine starts or the like, in a case where the temperature of the valve box is changed suddenly, a temperature gradient on the wall surface of the valve box can be promoted at the position at which the flow of the steam stagnates.

According to a second aspect of the present invention, in the on-off valve of the first aspect, in an inner surface of the valve box forming the outlet flow path, an uneven portion is provided on an inner surface around the valve support portion.

A heat transfer area at the position at which the flow of the steam stagnates is increased by the uneven portion, and thus, it is possible to disturb the flow of the steam. Therefore, the heat transfer at the position at which the uneven portion is provided can be promoted, and the temperature of the valve box at the position at which the steam stagnates around the valve support portion can be close to temperatures of other portions of the valve box. As a result, it is possible to further decrease the temperature gradient of the wall surface of the valve box at the position at which the steam stagnates.

According to a third aspect of the present invention, in the on-off valve of the first or second, aspect, the on-off valve further includes a metal member which is fixed to an outer surface of the valve box on the downstream side from the communication hole.

Heat from the wall surface of the valve box can flow into the metal member on the side, to which the outlet flow path extends, by this metal member. That is, the metal member can function as a heat storage unit. Accordingly, compared with the side (the side to which the outlet flow path extends) on which the flow of the steam stagnates in the vicinity of the valve support portion, heat dissipation can be promoted on the side to which the outlet flow path extends, and thus, thermal deformation of the valve box around the valve support portion can be uniformized.

According to a fourth aspect of the present invention, in the on-off valve of any one of the first to third aspects, the on-off valve further includes a drive unit which is fixed to the valve box on the downstream side from the communication hole and configured to drive the valve support portion, in which a gap is provided between the drive unit and the valve box on the side opposite to the side to which the outlet flow path extends across the valve support portion.

In this way, the gap is provided between the drive unit and the valve box on the side opposite to the side to which the outlet flow path extends across the valve support portion, and thus, at this position, it is possible to suppress heat dissipation caused by heat conduction from the valve box to the drive unit. In addition, the gap is not provided between the valve box and the drive unit on the side to which the outlet flow path extends, and thus, the heat dissipation from the valve box to the drive unit is easily performed. Accordingly, thermal deformation of the valve box around the valve support portion can be uniformized on both sides of the valve support portion.

In addition, according to a fifth aspect of the present invention, there is provided an on-off valve including: a valve box which includes inlet flow path of steam, and an outlet flow path which communicates with the inlet flow path through a communication hole on a downstream side in a flow direction of the steam; a valve body which is configured to open or close the communication hole; a valve support portion which penetrates the valve box such that a portion of the valve support portion is disposed in the outlet flow path, is supported by the valve box on the outlet flow path side from the communication hole, and supports the valve body so as to be capable of operating the valve body in an opening direction of the communication hole; and a metal member which is fixed to an outer surface of the valve box on a downstream side from the communication hole, in which the outlet flow path extends in a direction intersecting the opening direction of the communication hole toward a downstream side.

Heat from the wall surface of the valve box can flow into the metal member on the side, to which the outlet flow path extends, by the metal member, and thus, the metal member can function as a heat storage unit. Accordingly, compared with the side on which the flow of the steam stagnates in the vicinity of the valve support portion, heat dissipation can be promoted on the side to which the outlet flow path extends, and thus, thermal deformation of the valve box around the valve support portion can be uniformized.

In addition, according to a sixth aspect of the present invention, there is provided an on-off valve including: a valve box which includes an inlet flow path of steam, and an outlet flow path which communicates with the inlet flow path through a communication hole on a downstream side in a flow direction of the steam a valve body which is configured to open or close the communication hole; a valve support portion which penetrates the valve box such that a portion of the valve support portion is disposed in the outlet flow path, is supported by the valve box on the outlet flow path side from the communication hole, and supports the valve body so as to be capable of operating the valve body in an opening direction of the communication hole; and a drive unit which is fixed to the valve box on a downstream side from the communication hole and configured to drive the valve support portion, in which the outlet flow path extends in a direction intersecting the opening direction of the communication hole toward a downstream side, and a gap is provided between the drive unit and the valve box on a side opposite to a side to which the outlet flow path extends across the valve support portion.

In this way, the gap is provided between the drive unit and the valve box on the side opposite to the side to which the outlet flow path extends across the valve support portion, and thus, at this position, it is possible to suppress heat dissipation caused by heat conduction from the valve box to the drive unit. In addition, the gap is not provided between the valve box and the drive unit on the side to which the outlet flow path extends, and thus, the heat dissipation from the valve box to the drive unit is easily performed. Accordingly, thermal deformation of the valve box around the valve support portion can be uniformized.

In addition, according to a seventh aspect of the present invention, there is provided an on-off valve including: a valve box which includes an inlet flow path of steam, and an outlet flow path which communicates with the inlet flow path through a communication hole on a downstream side in a flow direction of the steam; a valve body which is configured to open or close the communication hole; a valve support portion which penetrates the valve box such that a portion of the valve support portion is disposed in the outlet flow path, is supported by the valve box on the outlet flow path side from the communication hole, and supports the valve body so as to be capable of operating the valve body in an opening direction of the communication hole; a metal member which is fixed to an outer surface of the valve box on a downstream side from the communication hole and on a side to which the outlet flow path extends across the valve support portion; and a drive unit which is fixed to the valve box on the downstream side from the communication hole and configured to drive the valve support portion, in which the outlet flow path extends in a direction intersecting the opening direction of the communication hole toward the downstream side, and a gap is provided between the drive unit and the valve box on a side opposite to a side to which the outlet flow path extends across the valve support portion.

Accordingly, thermal deformation of the valve box around the valve support portion can be uniformized by the metal member and the gap.

In addition, according to an eighth aspect of the present invention, there is provided a steam turbine including: a steam flow path; and the on-off valve according to any one of the first to seventh aspects provided in the steam flow path.

In the steam turbine, the on-off valve is provided, and thus, the minimum wall thickness of the valve box on the side opposite to the side to which the outlet flow path extends across the valve support portion on the outlet flow path side is smaller than the minimum wall thickness of the valve box on the inlet flow path side. As a result, the thickness of the valve box can decrease at a position at which a direction of, a steam flow path is changed and a position at which the flow of the steam stagnates around the valve support portion. Accordingly, when the steam turbine starts or the like, it is possible to decrease a temperature gradient on the wall surface of the valve box at the position at which the flow of the steam stagnates.

Advantageous Effects of Invention

According to the present invention, it is possible to smoothly open and close a valve body by suppressing uneven thermal deformation of a valve box.

DESCRIPTION OF EMBODIMENTS

First Embodiment

Hereinafter, embodiments of a steam turbine10according to the present invention will be described with reference to the accompanying drawings. However, the present invention is not limited to the embodiment.

As shown inFIG. 1, the steam turbine10of the present embodiment is an external combustion engine which extracts energy of steam S as rotational power and is used for a generator or the like in a power plant.

The steam turbine10includes a casing11, a rotary shaft20which rotates with respect to the casing11, a stationary blade ring12which is fixed to the casing11in the casing11, a moving blade ring30which is fixed to the rotary shaft20, a boiler40which generates steam S (main steam) to be supplied into the casing11, a steam flow path41which connects the boiler40and the casing11, and an on-off valve42which opens and closes the steam flow path41.

The stationary blade ring12is held by the casing11, and a plurality of stationary blade rings12are provided at intervals along a direction of a center axis O of the rotary shaft20. Each stationary blade ring12is formed to expand radially inward from an inner peripheral surface of the casing11. In each stationary blade ring12, a plurality of stationary blades12ware disposed at intervals in a circumferential direction.

The rotary shaft20extends along the center axis O to penetrate the casing11. An intermediate portion of the rotary shaft20in the direction along the center axis O is accommodated in the casing11, and both end portions of the rotary shaft20in the direction of the center axis O protrude toward an outside of the casing11from both end portions of the casing11in the direction of the center axis O. The rotary shaft20is rotatably supported with respect to the casing11around the center axis O by bearing portions13at both end portions protruding outward from a the casing11. Each bearing portion13includes journal bearings14respectively provided at both end portions of the rotary shaft20and a thrust bearing15which is provided on one end side of the rotary shaft20.

The moving blade ring30is held by the rotary shaft20and a plurality of moving blade rings30are provided at intervals along the direction of the center axis O of the rotary shaft20. The moving blade rings30and the stationary blade rings12are alternately disposed along the center axis O. Each moving blade ring30is formed to extend radially outward from an outer peripheral surface of the rotary shaft20. In each moving blade ring30, a plurality of moving blades30ware disposed at intervals in the circumferential direction.

The boiler40generates high-temperature and high-pressure steam S, and supplies the steam S to the steam turbine10via the steam flow path41.

In addition, this steam10is a so-called high-pressure turbine. In addition, although not shown, an intermediate-pressure turbine and a low-pressure turbine are connected to this high-pressure turbine, a condenser is connected to the high-pressure turbine, water is supplied from the condenser to the boiler40, and the steam S is generated by the boiler40again.

Next, the on-off valve42will be described with reference toFIG. 2.

The on-off valve42includes a valve box44, a stop valve body (valve body)46which is operated in the valve box44a stop valve supporting portion (valve support portion)47which supports the stop valve body46, an adjustable valve body48which is disposed to face the stop valve body46, and an adjustable valve support portion49which supports the adjustable valve body48. In addition, the on-off valve42further includes a first actuator70which drives the stop valve supporting portion47and a second actuator75which drives the adjustable valve support portion49.

In the valve box44, an inlet flow path51which is connected to the steam flow path41and an outlet flow path52which communicates with the inlet flow path51. In addition, the steam S flows in from the inlet flow path51and flows out from the outlet flow path52.

The inlet flow path51is connected to the steam flow path41. In addition, in the valve box44, a lid portion45which is attached and detached so as to open and close the inlet flow path51is provided.

The outlet flow path52straightly extends along an opening direction D of the communication hole53from the communication hole53which is a connection portion between the inlet flow path51and the outlet flow path52on a downstream side of the inlet flow path51in a flow of the steam S, and thereafter, the outlet flow path52is curved such that the extension direction thereof is bent by 90° and straightly extends toward a downstream side in the flow of the steam S. That is, the outlet flow path52extends in a direction (an orthogonal direction in the present embodiment) intersecting the opening direction D of the communication hole53. An annular valve seat58is provided on the communication hole53.

The stop valve body46is operated in the opening direction D of the communication hole53to open and close the communication hole53. That is, the stop valve body46is operated to approach the valve seat58so as to come into contact with the valve seat58, or is operated to be separated from the valve seat58so as to not come into contact with the valve seat58. This enables the steam S to flow between the inlet flow path51and the outlet flow path52or blocks the flow of the steam S.

The stop valve supporting portion47includes a valve rod60which supports the stop valve body46straightly extending along the opening direction D of the communication hole53, and a sheath61into which the valve rod60is inserted and which supports the valve rod60such that the valve rod60slidably moves in the opening direction D. The sheath61straightly extends in the opening direction D, penetrates the valve box44, and is supported by the valve box44. The sheath61extends to a position approaching the stop valve body46and a portion of the sheath61is disposed in the outlet flow path52.

Here, in the present embodiment, a minimum wall thickness t2of the valve box11which is positioned on the outlet flow path52side (downstream side) from the communication hole53and is positioned on a side opposite to a side to which the outlet flow path52extends across the sheath61is smaller than a minimum wall thickness t1of the valve box44on the inlet flow path51side (upstream side) from the communication hole53.

The adjustable valve body48is disposed in the inlet flow path51and faces the stop valve body46in the opening direction D. In addition, the adjustable valve body48is operated to approach the valve seat58so as to come into contact with the valve seat58and is operated to be separated so as not to come into contact with the valve seat58. When the adjustable valve body48comes into contact with the valve seat58, the adjustable valve body48comes into contact with an outer end of the stop valve body46. That is, an end portion of the adjustable valve body48on the communication hole53side is formed in a cylindrical shape.

The adjustable valve support portion49has a cylindrical sleeve66which is fixed to an inner surface of the valve box44facing the communication hole53in the opening direction D and supports the adjustable valve body48and a valve rod65which is disposed inside the sleeve66, straightly extends along the opening directions D, and supports the adjustable valve body48. The valve rod65straightly extends in the opening direction D and penetrates the valve box44.

The first actuator70includes a casing71which is fixed to the valve box44on the outlet flow path52side in the valve box11and a push rod72which supports the valve rod60and moves the valve rod60forward or rearward. The casing71is disposed on an extension line of an axis of the valve rod60supporting the stop valve body46and is fixed to an outer surface of the valve box44.

The second actuator75includes a casing76which is fixed to the valve box44on the inlet flow path51side in the valve box44and a push rod77which supports the valve rod65and moves the valve rod65forward or rearward. The casing76is disposed on an extension line of an axis of the valve rod65supporting the adjustable valve body48and is fixed to the outer surface of the valve box44.

The steam turbine10of the above-described present embodiment includes the on-off valve42having the above-described configuration.

Here, as shown in an analysis result ofFIG. 3, the flow of the steam S stagnates around the sheath61of the stop valve supporting portion47in the outlet flow path52, and thus, a heat transfer coefficient between the steam S and the valve box44X is lower than those of other portions of the valve box44X. For example, in a valve box44X shown inFIG. 3, the minimum wall thickness t1=t2.

More specifically, the flow of the steam S stagnates at a portion opposite to a side (right side on a paper surface of theFIG. 3) to which the outlet flow path52extends across the sheath61, that is, a corner portion52aat which the outlet flow path52is bent. Accordingly, the heat transfer coefficient between the steam S and the valve box44X decreases at the corner portion52a. As a result, a temperature of the valve box44X at the corner portion52ais lower than those of other portions of the valve box44X.

Accordingly, as shown inFIG. 3, compared with the side to which the outlet flow path52extends across the sheath61, an amount of thermal deformation (amount of thermal expansion) of an outer surface of the sheath61on the side opposite to the extension side of the outlet flow path52is small, and thus, the sheath61and the valve rod60are bent as a whole. As a result, it is difficult to smoothly operate the stop valve body46.

Here, in the present embodiment, the minimum wall thickness t2of the valve box44on the side opposite to the side to which the outlet flow path52extends across the sheath61on the outlet flow path52side is smaller than the minimum valve thickness t1of the valve box14on the inlet flow path51side. As a result, in the corner portion52awhich is the position at which a direction of the outlet flow path52is changed and in the position at which the flow of the steam S stagnates around the sheath61, the thickness of the valve box44can decrease.

Accordingly, for example, particularly, in a case where the temperature of the valve box44is changed suddenly at a start-up of the steam turbine10, or the like, heat conduction on the wall surface of the valve box44can be promoted at the position at which the flow of the steam S stagnates, and thus, it is possible to decrease a temperature gradient of the wall surface. Accordingly, a temperature can be uniformly increased in the valve box44by the steam S on the outlet flow path52side, and the thermal deformation of the valve box44around the sheath61can be uniformized. Accordingly, uneven thermal deformation of the valve box44is suppressed, and bending deformation of the valve rod60and the sheath61as shown inFIG. 3can be suppressed. As a result, it is possible to smoothly open or close the stop valve body45while suppressing occurrence of thermal stress of the valve rod60or the like.

Second Embodiment

Next, a second embodiment of the steam turbine10according to the present invention will be described. In addition, in the second embodiment described below, in the drawings, the same reference signs are assigned to the same configurations as those of the first embodiment, and repeated descriptions are omitted. The second embodiment is different from the first embodiment in that an uneven portion80is provided on an inner surface of a valve box44A.

As shown inFIG. 4A, the uneven portion80is provided on an inner surface of the valve box44A forming the outlet flow path52on the side opposite to the side to which the outlet flow path52. More specifically, the uneven portion80has a plurality of concave portions81which extends along the sheath61and the valve rod60, are arranged to be adjacent to each other in the circumferential direction of the valve rod60, and are recessed from the inner surface of the valve box44A, and fin-shaped convex portions82which protrude to the outlet flow path52between the concave portions81adjacent to each other in the circumferential direction. Accordingly, the uneven portion80is provided to surround the sheath61from the outer periphery. As shown inFIG. 4B, for example, a cross sectional shape, of each concave portion81when the concave portion81is viewed in the opening direction D may be a semicircular shape, and when viewed in the opening direction D, the plurality of concave portions81may form a waveform.

In addition, as shown inFIG. 5, the uneven portion80may have cylindrical fins83protruding from the inner surface of the valve box44A. Instead of the cylindrical fins83, pin fins may be used. In addition, the uneven portion80may simply be a rough surface having a rough inner surface of the valve box44A.

In a case where the valve box44A is formed by casting, the uneven portion80may be formed on the inner surface of the valve box44A by forming a shape corresponding to the uneven portion80in a mold. In addition, after the valve box44A is manufactured, the uneven portion80may be formed by machining.

According to the steam turbine10of the above-described present embodiment, a heat transfer area at the position at which the flow of the steam S stagnates is increased by the uneven portion80provided in the valve box44A, and thus, it is possible to disturb the flow of the steam S. Therefore, the heat transfer at the position at which the uneven portion80is provided can be promoted, and the temperature of the valve box44A at the position at which the steam S stagnates around the sheath61can be close to temperatures of other portions of the valve box44A. As a result, it is possible to further decrease the temperature gradient of the wall surface of the valve box44A at the position at which the steam S stagnates.

Accordingly, it is possible to decrease the temperature gradient of the wall surface of the valve box44A on the side opposite to the side to which the outlet flow path52extends. Therefore, it is possible to smoothly open and close the stop valve body45by suppressing the uneven thermal deformation of the valve box44A.

Third Embodiment

Next, a third second embodiment of the steam turbine10according to the present invention will be described. In addition, in the third embodiment described below, in the drawings, the same reference signs are assigned to the same configurations as those of the first embodiment and the second embodiment, and repeated descriptions are omitted. The third embodiment is different from the first embodiment and the second embodiment in that a metal member90fixed to the outer surface of the valve box11is further provided.

As shown inFIG. 6A, the metal member90is positioned on the outlet flow path52side from the communication hole53and is fixed to the outer surface of the valve box11only on a side to which the outlet flow path52extends across the sheath61. Moreover, the metal member90is formed of a metal material having a large heat capacity such as carbon steel or stainless steel, and, for example, as shown inFIG. 6B, is disposed coaxially with the valve rod60and has a semi-annular shape when viewed in the opening direction D.

In the present embodiment, the metal member90is provided inside the casing71of the first actuator70, the first actuator70is fixed to the valve box44, and thus, the metal member90is indirectly fixed to the valve box44.

In addition, the metal member90is not provided inside the casing71of the first actuator70, and may be directly fixed to the outer surface of the valve box44. Moreover, the metal member90may not be formed in a semi-annular shape, and may have any shape as long as it is provided only on the side to which the outlet flow path52extends across the sheath61. For example, the metal member90is divided, and thus, a plurality of metal members90may be provided.

Here, the metal members90may be provided on both sides of the side opposite to the side to which the outlet flow path52extends across the sheath61and the side to which the outlet flow path52extends. An installation position of the metal member90may be appropriately changed depending on conditions such as whether to suppress the deformation during start-up or whether to suppress the deformation during a rated operation.

According to the steam turbine10of the above-described the present embodiment, by the metal member90, heat from the wall surface of the valve box44can flow into the metal member90on the side to which the outlet flow path52extends. That is, the metal member90can function as a heat storage unit. Accordingly, compared with the side on which the flow of the steam S stagnates in the vicinity of the sheath61becoming the side opposite to the side to which the outlet flow path52extends, heat dissipation can be promoted on the side to which the outlet flow path52extends, and thus, thermal deformation of the valve box44around the sheath61can be uniformized.

Accordingly, it is possible to decrease the temperature gradient of the wall surface of the valve box44on the side opposite to the side to which the outlet flow path extends. Therefore, it is possible to smoothly open and close the valve body by suppressing the uneven thermal deformation of the valve box44.

Fourth Embodiment

Next, a fourth embodiment of the steam turbine10according to the present invention will be described. In addition, in the fourth embodiment described below, in the drawings, the same reference signs are assigned to the same configurations as those of the first embodiment to the third embodiment, and repeated descriptions are omitted. The fourth embodiment is different from the first embodiment to the third embodiment in that a gap91is provided between the first actuator70and the valve box11on the side opposite to the side to which the outlet flow path52extends across the sheath61.

That is, as shown inFIGS. 7A and 7B, a gap91which is disposed coaxially with the valve rod60and has a semi-annular shape is formed between the casing71of the first actuator70and the valve box44on the side opposite to the side to which the outlet flow path52extends across the sheath61.

In addition, the gap91may be not formed a semi-annular shape and may have any shape as long as at least it is provided on the side to which the outlet flow path52extends across the sheath61. For example, the gap91may be divided ire the circumferential direction of the valve rod60, and a plurality of gaps91may be provided.

Here, the gaps91may be provided on both sides of the side opposite to which the outlet flow path52extends across the sheath61and the side to which the outlet flow path52extends such that a size of the gap91on the side opposite to the side to which the outlet flow path52extends is larger than a size of the gap91on the side to which the outlet flow path52extends.

According to the steam turbine10of the above-described present embodiment, the gap91is provided between the casing71of the first actuator70and the valve box44on the side opposite to the side to which the outlet flow path52extends across the sheath61, and thus, at this position, it is possible to suppress heat dissipation caused by heat conduction from the valve box11to the first actuator70.

In addition, the gap91is not provided between the valve box11and the casing71on the side to which the outlet flow path52extends, that is, the valve box44and the casing71come into close contact with each other, and thus, the heat dissipation from the valve box14to the casing71is easily performed. Accordingly, thermal deformation of the valve box44around the sheath61can be uniformized on both sides of the sheath61.

Accordingly, it is possible to decrease the temperature gradient of the wall surface of the valve box44on the side opposite to the side to which the outlet flow path52extends. Therefore, it is possible to smoothly open and close the valve body by suppressing the uneven thermal deformation of the valve box14.

Hereinbefore, the embodiments of the present invention are described in detail with reference to the drawings. However, the respective configurations and the combinations thereof and the like in the respective embodiments are merely examples, and additions, omissions, replacements, and other modifications of configurations are possible within a scope which does not depart from the gist of the present invention. In addition, the present invention is not limited by the embodiments, and is limited only by claims.

For example, in the above-described embodiments, the on-off valve42including the stop valve body46and the adjustable valve body48is described. However, the on-off valve42which does not have the adjustable valve body48may be provided.

In addition, the outlet flow path52is not limited to the above-described configurations as long as it extends in the direction intersecting the opening direction D of the communication hole53and the valve rod60is provided at the position (corner portion52a) at which the extension direction is changed. That is, the outlet flow path52may straightly extend from the communication hole53, and thereafter, the outlet flow path52may be bent smoothly such that the extension direction is changed in the middle. The outlet flow path52may be bent abruptly to extend to a downstream side of the flow of the steam S.

In addition, the metal member90of the third embodiment and the gap91of the fourth embodiment may be provided together. In addition, the metal member90of the third embodiment and the gap91of the fourth embodiment may be applied to the on-off valve which has the configurations of the first embodiment and the second embodiment, or may be applied to the on-off valve which does not have the configurations of the first embodiment and the second embodiment.

INDUSTRIAL APPLICABILITY

According to the present invention, it is possible to smoothly open and close a valve body by suppressing uneven thermal deformation of a valve box.

REFERENCE SIGNS LIST

12: stationary blade ring

14: journal bearing

30: moving blade ring

30w: moving blade

41: steam flow path

44,44A,44X: valve box

47: stop valve supporting portion (valve support portion)

48: adjustable valve body

49: adjustable valve support portion

51: inlet flow path

52: outlet flow path

52a: corner portion

53: communication hole

58: valve seat

90: metal member

O: center axis

D: opening direction