JP2011226428A - Steam turbine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress an exhaust loss of a steam turbine including a steam guide or the like.SOLUTION: The steam guide of a steam turbine rotor includes an upper half steam guide and a lower half steam guide. The upper half steam guide 40 is in a semicircular-ring shape disposed outside an inner casing 21 and covering the steam turbine rotor from the outside in a radial direction, and forms a steam exhaust flow passage to exhaust working steam with an inner circumference face shaped in such a manner that a distance from the rotation center axis gradually increases toward the downstream side in the axial direction. The lower half steam guide 50 is in a semicircular-ring shape disposed to face the upper half steam guide 40 to form a circular ring together with the upper half steam guide 40 with an inner circumference face shaped in such a manner that the distance from the rotation center axis gradually increases toward the downstream side in the axial direction.

Description

  The present invention relates to a steam turbine provided with a steam guide and the like.

For example, steam turbines used in thermal power plants and the like are required to improve efficiency in order to effectively use energy resources and reduce CO ₂ emissions. In order to improve the efficiency of a steam turbine, it is necessary to effectively convert energy into mechanical work. In this case, various internal loss reductions are required.

  One of internal losses in the steam turbine is exhaust loss. This exhaust loss accounts for a large proportion of the total steam turbine loss. This exhaust loss is a loss that occurs between the final stage outlet of the nozzle and the condenser inlet, and includes a leaving loss, a hood loss, an annular area limiting loss, a turn-up loss, and the like.

  The hood loss is a pressure loss from the exhaust chamber to the condenser, and greatly depends on the shape and size of the exhaust chamber. Since the pressure loss increases with the square of the flow velocity, it is effective to reduce the flow velocity by increasing the exhaust size within an allowable range. However, increasing the size has restrictions such as the manufacturing cost and the size of the building where the steam turbine is installed. Since the exhaust chamber occupies a large capacity even in the entire steam turbine, increasing the size to reduce the loss leads to an increase in the size and cost of the entire steam turbine.

JP-A-4-334702

  Many steam guides in which the exhaust chamber is arranged are configured to be divided into a lower side and an upper side with respect to the rotation center axis of the rotor. The upper half steam guide and the lower half steam guide may be formed with a gap in the divided portion after being assembled. It is often difficult to produce the upper half and lower half steam guides so that the gap does not occur due to an increase in cost. If this gap is large, the exhaust loss described above may increase.

  The present invention has been made to solve the above-described problems, and an object thereof is to make it possible to suppress exhaust loss of a steam turbine.

  In order to achieve the above object, a steam turbine according to the present invention includes a turbine rotor having a plurality of rotor blades fixed on an outer peripheral surface, and a working steam that is a working fluid disposed outside the outer peripheral surface in the radial direction. A nozzle that forms a steam flow path that circulates in a direction; an inner casing that fixes the nozzle and rotatably accommodates the turbine rotor; an outer casing that accommodates the inner casing; and the steam passage of the inner casing And the inner peripheral surface is formed so that the distance from the rotation center axis gradually increases toward the downstream side in the axial direction, and partially covers the turbine rotor from the radially outer side. An annular first steam guide and an annular ring that can be arranged to face the first steam guide and together with the first steam guide A second steam guide that is formed in a semi-annular shape and has an inner peripheral surface that gradually increases in distance from the rotation center axis toward the downstream side in the axial direction, the first steam guide When the first steam guide and the second steam guide are combined with each other, a first engagement surface and a second engagement surface that can be engaged with each other are formed at the circumferential ends of the second steam guide and the second steam guide, respectively. Further, the first engagement surface and the second engagement surface are formed so as to incline in the same direction as either upward or downward in the radial direction and can be fixed in contact with each other. It is characterized by being comprised.

  The steam turbine according to the present invention includes a turbine rotor having a plurality of moving blades fixed to the outer peripheral surface, and a steam that is disposed radially outside the outer peripheral surface and distributes the operating steam that is a working fluid in the axial direction. A nozzle that forms a flow path, an inner casing that fixes the nozzle portion and rotatably accommodates the rotor, an outer casing that accommodates the inner casing, and an inner casing are disposed downstream of the steam passage. And a semi-annular first steam guide that is formed such that the inner peripheral surface gradually increases as the distance from the rotation center axis decreases toward the downstream side in the axial direction, and covers the turbine rotor from the radially outer side; The semicircular ring that can be arranged to face the first steam guide and forms a single ring with the first steam guide, and the inner peripheral surface A second steam guide formed such that the distance from the central axis gradually increases toward the downstream side in the axial direction, and the second steam guide is provided at a circumferential end of the first steam guide. When engaged, a first engagement plate that extends toward the second steam guide and extends along the inner peripheral surface is attached, and at the circumferential end of the second steam guide, A second engagement is formed to extend toward the second steam guide when the second steam guide is engaged and to extend along the inner peripheral surface, and to engage with the first engagement plate. When a combination plate is attached and the first engagement plate and the second engagement plate are engaged with each other, the opposing surfaces are configured to contact each other.

  The steam turbine according to the present invention includes a turbine rotor having a plurality of moving blades fixed to the outer peripheral surface, and a steam that is disposed radially outside the outer peripheral surface and distributes the operating steam that is a working fluid in the axial direction. A nozzle that forms a flow path, an inner casing that fixes the nozzle and rotatably accommodates the turbine rotor, an outer casing that accommodates the inner casing, and an inner casing are disposed downstream of the steam passage. And a semi-annular first steam guide that is formed such that the inner circumferential surface gradually increases as the distance from the rotation center axis decreases toward the downstream side in the axial direction, and covers the turbine rotor from the radially outer side, The semicircular ring that can be arranged to face the first steam guide and forms a single ring with the first steam guide, A second steam guide formed such that the distance from the rotation center axis gradually increases toward the downstream side in the axial direction, and the second steam is provided at a circumferential end of the first steam guide. At least one plate-like convex fin formed so as to extend toward the second steam guide and extend along the inner peripheral surface when the guide is engaged is attached to the second steam guide. Is formed so as to extend toward the second steam guide and to follow the inner peripheral surface when the second steam guide is engaged with the convex fin from both sides in the radial direction. At least two plate-like concave fins formed so as to be sandwiched are attached.

  According to the present invention, exhaust loss of a steam turbine can be suppressed.

It is a schematic front view which shows typically an upper half steam guide, a lower half steam guide, etc. in a part of steam turbine of a 1st embodiment concerning the present invention. It is a schematic front view of the partial cross section which shows the steam turbine of FIG. FIG. 2 is a schematic partial perspective view showing a state before being combined with a part of the upper half steam guide and the lower half steam guide of FIG. 1. FIG. 4 is a schematic partial perspective view showing a state where the upper half steam guide and the lower half steam guide of FIG. 3 are combined with each other. It is a VV arrow side cross section of FIG. It is a general | schematic fragmentary perspective view of the state divided | segmented by some upper half steam guides and lower half steam guides of the steam turbine of 2nd Embodiment which concerns on this invention. FIG. 7 is a schematic partial perspective view showing a state where the upper half steam guide and the lower half steam guide of FIG. 6 are combined with each other. It is a general | schematic fragmentary perspective view of the state divided | segmented by a part of upper half steam guide and lower half steam guide of the steam turbine of 3rd Embodiment which concerns on this invention. FIG. 9 is a schematic partial perspective view showing a state where the upper half steam guide and the lower half steam guide of FIG. 8 are combined with each other. It is a general | schematic fragmentary perspective view of the state divided | segmented by a part of upper half steam guide and lower half steam guide of the steam turbine of 4th Embodiment which concerns on this invention. FIG. 11 is a schematic partial perspective view showing a state where the upper half steam guide and the lower half steam guide in FIG. 10 are combined with each other. It is an enlarged partial side view of the XII part of FIG. It is a sectional side view which shows the modification of embodiment (1st Embodiment) of FIG.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

[First Embodiment]
A first embodiment according to the present invention will be described with reference to FIGS. FIG. 1 is a schematic front view schematically showing an upper half steam guide 40, a lower half steam guide 50, and the like in a part of the steam turbine of the present embodiment. FIG. 2 is a schematic front view of a partial cross section showing the steam turbine of FIG. FIG. 3 is a schematic partial perspective view showing a state of the upper half steam guide 40 and the lower half steam guide 50 of FIG. 1 before being combined. FIG. 4 is a schematic partial perspective view showing a state where the upper half steam guide 40 and the lower half steam guide 50 of FIG. 3 are combined with each other. FIG. 5 is a sectional side view taken along the arrow V-V in FIG. 1.

  First, the outline of the structure of the steam turbine of this embodiment is demonstrated.

  This steam turbine is an axial flow multi-stage turbine, and includes a steam turbine rotor 10 configured by attaching a plurality of moving blades 12 to the outer periphery of a cylindrical rotor body, and a casing. This casing has a double structure having an outer casing 23 and an inner casing 21.

  The inner casing 21 is configured to be divided into an upper half inner casing 21a and a lower half inner casing 21b. Similarly, the outer casing 23 is configured to be divided into an upper half outer casing 23a and a lower half outer casing 23b.

  The steam turbine rotor 10 is rotatably accommodated in the inner casing 21, and both ends of the steam turbine rotor 10 protrude on both sides in the axial direction (left-right direction in FIG. 2).

  The outer casing 23 accommodates the inner casing 21 and is attached with a bearing 25 for supporting a portion protruding from the inner casing 21 of the steam turbine rotor 10. The steam turbine rotor 10 is rotatably supported by the bearing 25.

  On the radially inner side of the inner casing 21, a nozzle 11 having an annular flow path through which working steam as a working fluid flows in the axial direction is fixed and disposed on the radially outer side of the steam turbine rotor 10.

  A final stage blade 13 is provided inside the inner casing 21 and in the vicinity of the outlet from which the steam turbine rotor 10 protrudes. A steam guide, a bearing cone 26, and the like are disposed downstream of the final stage blade 13 on the downstream side of the working steam and outside the inner casing 21, and a diffuser (expanded flow) for exhausting the working steam to the outside of the casing. Road) 14 is formed. The diffuser 14 has a function of increasing the pressure by reducing the flow velocity by gradually increasing the cross-sectional area from the inlet to the outlet of the flow path.

  These steam guides and bearing cones 26 are arranged inside the outer casing 23 with an axial gap therebetween in the axial direction (FIG. 1). At this time, the steam guide is arranged upstream of the working steam, and the bearing cone 26 is arranged downstream. Further, the steam in the axial direction becomes the diffuser 14 and the working steam flows.

  The working steam flows into the nozzle 11 as indicated by an arrow X1 in FIG. 2, flows axially on both sides of the steam turbine rotor 10 as indicated by an arrow X2, and then flows through the diffuser 14 to the outside of the outer casing 23. Exhausted.

  The steam guide has an upper half steam guide 40 and a lower half steam guide 50. When these are assembled into an integral steam guide, they are configured to be annular members. The steam guide at this time is arranged so as to cover a portion protruding from the inner casing 21 of the steam turbine rotor 10 from the outside in the radial direction. The steam guide is formed so that the inner diameter gradually increases from the upstream side to the downstream side of the working steam (from the left side to the right side in FIG. 1). The shapes of the upper half steam guide 40 and the lower half steam guide 50 will be described later.

  The bearing cone 26 is a partially conical member that covers the bearing 25 from the outside in the radial direction, and is formed so that the inner diameter gradually increases from the upstream side to the downstream side of the working steam. The upstream end of the bearing cone 26 is disposed so that the axial position overlaps the downstream end of the steam guide.

  The steam guide and the bearing cone 26 have a function as the diffuser 14 by being formed so that the inner diameter gradually increases as described above.

  The steam guide can be divided into two upper and lower parts, that is, an upper half steam guide 40 and a lower half steam guide 50 with a horizontal plane (virtual plane) 70 including the rotation center axis of the steam turbine rotor 10 as a boundary (ie, an upper half steam guide 40 and a lower half steam guide 50) 5). However, the upper half steam guide 40 and the lower half steam guide 50 are not strictly divided vertically in the horizontal plane 70. A part of the divided part of the upper half steam guide 40 is below the horizontal plane 70, and a part of the divided part of the lower half steam guide 50 is above the horizontal plane 70.

  Below, the structure of the division | segmentation part of each of these upper half steam guide 40 and lower half steam guide 50 is demonstrated.

  An upper inclined surface 41 having a predetermined angle with respect to the horizontal plane 70 is formed on the circumferential end surface of the divided portion of the upper half steam guide 40, that is, the circumferential end surface of the connection portion with the lower half steam guide 50. In this example, the upper inclined surface 41 is formed so as to fall outward in the radial direction (FIG. 5).

  A lower inclined surface 51 of a predetermined angle with respect to the horizontal plane 70 is formed on the circumferential end surface of the divided portion of the lower half steam guide 50, that is, the circumferential end surface of the connection portion with the upper half steam guide 40. The lower inclined surface 51 is formed so as to be lowered outward in the radial direction.

  That is, the upper inclined surface 41 and the lower inclined surface 51 are formed so as to have the same inclination direction when facing each other. For this reason, when the upper half steam guide 40 and the lower half steam guide 50 are combined with each other, the upper inclined surface 41 and the lower inclined surface 51 are configured to be in contact with each other.

  The upper inclined surface 41 and the lower inclined surface 51 are preferably about 45 to 60 degrees with respect to the horizontal.

  When the upper half steam guide 40 and the lower half steam guide 50 are combined with each other, the upper half steam guide 40 is elastically deformed in a direction spreading outward in the radial direction. At this time, the lower half steam guide 50 is elastically deformed radially inward.

  Here, a state where the upper half steam guide 40 is fitted into the lower half steam guide 50 will be described.

  First, after arranging the lower half outer casing 23b and the lower half inner casing 21b, the lower half steam guide 50 is attached. Although not shown in detail, the lower half steam guide 50 is fixed to the flange 16 with a bolt or the like in the axial direction. After this, the steam turbine rotor 10 is installed and the upper half inner casing 21a is installed.

  Next, the upper half steam guide 40 is fitted from above the lower half steam guide 50. At this time, the upper half steam guide 40 is attached to the lower half steam guide 50 so that the upper inclined surface 41 and the lower inclined surface 51 are in contact with each other. At this time, the upper half steam guide 40 is elastically deformed so as to spread outward in the radial direction, and the lower half steam guide 50 is elastically deformed so as to be narrowed inward in the radial direction. As a result, the upper inclined surface 41 and the lower inclined surface 51 are in close contact with each other.

  As can be seen from the above description, according to the present embodiment, the formation of a gap in the divided portion (connecting portion) of the upper half steam guide 40 and the lower half steam guide 50 is suppressed, and the steam guide or the like is formed. The working steam is prevented from leaking from the diffuser 14. Therefore, exhaust loss of the steam turbine can be suppressed.

[Second Embodiment]
A steam turbine according to a second embodiment of the present invention will be described with reference to FIGS. 6 and 7. FIG. 6 is a schematic partial perspective view of the steam turbine according to this embodiment, which is partly divided into the upper half steam guide 40 and the lower half steam guide 50. FIG. 7 is a schematic partial perspective view showing a state in which the upper half steam guide 40 and the lower half steam guide 50 of FIG. 6 are combined with each other. In addition, this embodiment is a modification of 1st Embodiment, Comprising: The same code | symbol is attached | subjected to the same part or similar part as 1st Embodiment (FIGS. 1-5), and duplication description is carried out. Omitted.

  A first engagement plate 43 and a second engagement plate 53 are attached to the connection portions of the upper half steam guide 40 and the lower half steam guide 50 of the present embodiment.

  When the upper half steam guide 40 and the lower half steam guide 40 are combined with each other, the circumferential end face (upper end face) 42 of the connection portion of the upper half steam guide 40 is formed so as to be substantially horizontal facing downward. Has been. Further, the circumferential end face (lower end face) 52 of the connecting portion of the lower half steam guide 50 is formed so as to face upward and become almost horizontal.

  The first engagement plate 43 is attached to the upper end surface 42 of the connection portion of the upper half steam guide 40 so as to extend at a predetermined angle. That is, the first engagement plate 43 is formed to extend downward from the upper end face 42 toward the lower half steam guide 50 when the upper half steam guide 40 is attached to the lower half steam guide 50. Yes. The first engagement plate 43 is formed of a spring material or the like that is more elastic and flexible than the upper half steam guide 40.

  The second engagement plate 53 is attached to the lower end surface 52 of the connecting portion of the lower half steam guide 50 so as to extend at a predetermined angle. That is, the first engagement plate 43 is formed to extend upward from the lower end surface 52 toward the lower half steam guide 50 when the upper half steam guide 40 is attached to the lower half steam guide 50. ing. Similar to the first engagement plate 43, the second engagement plate 53 is formed of a spring material having elasticity and flexibility.

  When the upper half steam guide 40 and the lower half steam guide 50 are combined with each other, the first engagement plate 43 and the second engagement plate 53 are configured such that the opposing surfaces are in close contact with each other. In other words, the radially inner side surface of the first engaging plate 43 and the radially outer side surface of the second engaging plate are configured to be in close contact with each other.

  At this time, the front end of the first engagement plate 43 is elastically deformed so that the front end of the second engagement plate 53 is warped radially inward.

  As can be seen from the above description, according to the present embodiment, it is possible to suppress the formation of a gap between the upper half steam guide 40 and the lower half steam guide 50 as in the first embodiment. Further, since the first and second engagement plates 43 and 53 are made of a member that is easily elastically deformed compared to the main bodies of the upper and lower steam guides 40 and 50, it is possible to improve the adhesion. Become.

  In addition, the upper half and lower half steam guides 40, 50 are elastically deformed so that the front end of the first engagement plate 43 is warped radially outward and the front end of the second engagement plate 53 is warped radially inward. When assembling each other, it is possible to prevent the tips of the first and second engagement plates 43 and 53 from colliding with each other and hindering assembly workability.

[Third Embodiment]
A steam turbine according to a third embodiment of the present invention will be described with reference to FIGS. FIG. 8 is a schematic partial perspective view of the steam turbine according to this embodiment, which is partly divided into the upper half steam guide 40 and the lower half steam guide 50. FIG. 9 is a schematic partial perspective view showing a state in which the upper half steam guide 40 and the lower half steam guide 50 of FIG. 8 are combined with each other. Note that this embodiment is a modification of the second embodiment, and the same or similar parts as those in the second embodiment (FIGS. 6 and 7) are denoted by the same reference numerals, and redundant description is given. Omitted.

  As in the second embodiment, the first and second engagement plates 43 and 53 are attached to the upper end surface 42 of the upper half steam guide 40 and the lower end surface 52 of the lower half steam guide 50, respectively. It has been. When the upper half steam guide 40 and the lower half steam guide 50 are combined with each other, the first and second engagement plates 43 and 53 are in close contact with each other while being elastically deformed radially outward.

  In the second embodiment, when the dimensional difference between the horizontal planes of the split surfaces of the upper half and lower half steam guides 40, 50 is relatively large, or the flow of the diffuser 14 formed by the upper half and lower half steam guides 40, 50 When the difference in the radius of curvature of the road surface is large, there is a possibility that when the upper half and lower half steam guides 40 and 50 are combined with each other, the first engagement plate 43 and the second engagement plate 53 are less likely to come into contact with each other. There is sex. On the other hand, even when the dimensional difference between the above-described portions of the upper half steam guide 40 and the lower half steam guide 50 is relatively large, they can be brought into close contact with each other.

  Thereby, formation of a gap between the upper half steam guide 40 and the lower half steam guide 50 can be suppressed.

[Fourth Embodiment]
A steam turbine according to a fourth embodiment of the present invention will be described with reference to FIGS. FIG. 10 is a schematic partial perspective view of the steam turbine according to the present embodiment, which is partly divided into the upper half steam guide 40 and the lower half steam guide 50. FIG. 11 is a schematic partial perspective view showing a state where the upper half steam guide 40 and the lower half steam guide 50 of FIG. 10 are combined with each other. 12 is an enlarged partial side view of the XII portion of FIG. In addition, this embodiment is a modification of 1st Embodiment (FIGS. 1-5), Comprising: The same code | symbol is attached | subjected to the same part or similar part as 1st Embodiment, and duplication description is carried out. Omitted.

  A convex gap adjusting fin 44 is attached to the upper end face 42 of the upper half steam guide 40 of the present embodiment. A concave clearance adjusting fin 54 is attached to the lower end surface 52 of the lower half steam guide 50.

  The convex gap adjusting fins 44 are attached so as to extend substantially perpendicularly from the radial center of the upper end face 42 of the connecting portion of the upper half steam guide 40. That is, when the upper half steam guide 40 is attached to the lower half steam guide 50, the convex gap adjusting fin 44 extends downward from the radial center of the upper end surface 42 toward the lower half steam guide 50. It is formed as follows. The tip of the convex gap adjusting fin 44 is formed in a state of being sharpened downward, that is, an acute angle.

  The concave clearance adjusting fin 54 has two fins, and each fin is attached so as to extend substantially vertically from both ends in the radial direction of the upper end surface 42 of the connecting portion of the lower half steam guide 50. That is, when the upper half steam guide 40 is attached to the lower half steam guide 50, the concave gap adjusting fins 54 extend upward from both radial sides of the lower end surface 52 toward the lower half steam guide 50. It is formed as follows. Each tip of the concave gap adjusting fin 54 is formed in a state of being sharpened upward, that is, an acute angle.

  When the upper half and lower half steam guides 40 and 50 formed with the convex and concave gap adjusting fins 44 and 54 are combined with each other, the tips of the convex gap adjusting fins 44 are formed on the lower end surface 52 with a predetermined distance. The circumferential interval is maintained (FIG. 12). Similarly, the front end of the concave clearance adjusting fin 54 is held at a predetermined circumferential distance on the upper end surface 42. That is, it becomes possible for the fins 44 and 54 to suppress the leakage of steam, similarly to the labyrinth fin.

  Moreover, in this case, as described in the first to third embodiments, it is not necessary to make them closely contact with each other, so that the combination work is easy.

[Other Embodiments]
The description of the above embodiment is an example for explaining the present invention, and does not limit the invention described in the claims. Moreover, each part structure of this invention is not restricted to the said embodiment, A various deformation | transformation is possible within the technical scope as described in a claim.

  For example, in the first embodiment, when the upper half steam guide 40 and the lower half steam guide 50 are combined, the connection portion of the lower half steam guide is radially outward and the connection portion of the upper half steam guide is radially inner. You may comprise so that it may become. That is, as shown in FIG. 13, the upper inclined surface 41 and the lower inclined surface 51 may be configured to be inclined upward toward the radially outer side.

  In the second embodiment, the first engagement plate 43 and the second engagement plate 53 are both deformed radially outward, but the opposite may be possible.

DESCRIPTION OF SYMBOLS 10 ... Steam turbine rotor, 11 ... Nozzle, 12 ... Blade, 13 ... Final stage blade, 14 ... Diffuser, 16 ... Flange, 21 ... Inner casing, 21a ... Upper half inner casing, 21b ... Lower half inner casing, 23 ... Outside Casing, 23a ... Upper half outer casing, 23b ... Lower half outer casing, 25 ... Bearing, 26 ... Bearing cone, 40 ... Upper half steam guide, 41 ... Upper inclined surface, 42 ... Upper end surface, 43 ... First engaging plate , 44 ... convex gap adjusting fins, 50 ... lower half steam guide, 51 ... lower inclined surface, 52 ... lower end face, 53 ... second engagement plate, 54 ... concave gap adjusting fins, 70 ... horizontal plane (virtual plane) )

Claims (5)

A turbine rotor having a plurality of rotor blades fixed to the outer peripheral surface;
A nozzle that is disposed radially outside the outer peripheral surface and forms a steam flow path that circulates working steam, which is a working fluid, in the axial direction;
An inner casing that fixes the nozzle and rotatably accommodates the turbine rotor;
An outer casing that houses the inner casing;
The inner casing is disposed on the downstream side of the steam flow path, and the inner peripheral surface is formed such that the distance from the rotation central axis gradually increases toward the downstream side in the axial direction, A semicircular first steam guide partially covering from the outside in the radial direction;
The semicircular ring that can be arranged to face the first steam guide and forms a single ring together with the first steam guide, and the inner peripheral surface is directed to the downstream side in the axial direction with respect to the rotation center axis. A second steam guide formed to gradually grow according to
Have
A first engagement surface and a second engagement surface that can be engaged with each other are formed at the circumferential ends of the first steam guide and the second steam guide,
When the first steam guide and the second steam guide are combined with each other, the first engagement surface and the second engagement surface are either upward or downward in the radial direction and in the same direction as each other. Formed so as to be inclined to each other, and configured to be fixed in a state of being in contact with each other,
A steam turbine characterized by   The portion where the first inclined surface and the second inclined surface are formed has heat resistance and is configured to be elastically deformable when the first inclined surface and the second inclined surface are in contact with each other. The steam turbine according to claim 1. A turbine rotor having a plurality of rotor blades fixed to the outer peripheral surface;
A nozzle that is disposed radially outside the outer peripheral surface and forms a steam flow path that circulates working steam, which is a working fluid, in the axial direction;
An inner casing that fixes the nozzle portion and rotatably accommodates the rotor;
An outer casing that houses the inner casing;
The inner casing is disposed on the downstream side of the steam passage, and the inner peripheral surface is formed such that the distance from the rotation center axis gradually increases toward the downstream side in the axial direction, and the turbine rotor is radiused. A semicircular first steam guide covering from the outside in the direction;
The semicircular ring that can be arranged to face the first steam guide and forms a single ring together with the first steam guide, and the inner peripheral surface is directed to the downstream side in the axial direction with respect to the rotation center axis. A second steam guide formed to gradually grow according to
Have
The first engagement guide is formed to extend toward the second steam guide and to extend along the inner peripheral surface when the second steam guide is engaged with the circumferential end of the first steam guide. The board is attached,
When the second steam guide is engaged with the circumferential end of the second steam guide, the second steam guide extends toward the second steam guide and extends along the inner peripheral surface. A second engagement plate that can be engaged with each other is attached to the engagement plate,
When the first engagement plate and the second engagement plate are engaged with each other, the opposing surfaces are configured to contact each other;
A steam turbine characterized by   The steam turbine according to claim 3, wherein the first engagement plate and the second engagement plate are configured to contact each other while being deformed in the same direction in the radial direction. A turbine rotor having a plurality of rotor blades fixed to the outer peripheral surface;
A nozzle that is disposed radially outside the outer peripheral surface and forms a steam flow path that circulates working steam, which is a working fluid, in the axial direction;
An inner casing that fixes the nozzle and rotatably accommodates the turbine rotor;
An outer casing that houses the inner casing;
The inner casing is disposed on the downstream side of the steam passage, and the inner peripheral surface is formed such that the distance from the rotation center axis gradually increases toward the downstream side in the axial direction, and the turbine rotor is radiused. A semicircular first steam guide covering from the outside in the direction;
The semicircular ring that can be arranged to face the first steam guide and forms a single ring together with the first steam guide, and the inner peripheral surface is directed to the downstream side in the axial direction with respect to the rotation center axis. A second steam guide formed to gradually grow according to
Have
At least one sheet formed to extend toward the second steam guide and to extend along the inner peripheral surface when the second steam guide is engaged with the circumferential end of the first steam guide. Plate-shaped convex fins are attached,
The convex fin is formed at the circumferential end of the second steam guide so as to extend toward the second steam guide when the second steam guide is engaged, and to extend along the inner peripheral surface. Are attached with at least two plate-like concave fins formed so as to be sandwiched from both sides in the radial direction,
A steam turbine characterized by

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