JP6132737B2 - Steam turbine - Google Patents

Description

  Embodiments described herein relate generally to a steam turbine including a resin material.

  In recent years, non-ferrous composite materials reinforced with a synthetic resin and carbon fiber, which are stronger and lighter than metals, are widely used mainly in the aircraft industry, where improvement in fuel consumption by reducing weight is important. The use of such materials in steam turbines for power generation is very groundbreaking and worthy of innovation for steam turbines.

  The steam flow expands to, for example, 5/100 atm or less in the steam turbine low-pressure section, and the volume flow rate is on the order of about 1000 times the inlet, so the casing outer diameter of the large steam turbine may be close to 10 m. If a resin-based material containing fiber reinforced composite material is applied to such a large structure, a lightweight steam turbine of about 1/5 can be realized even with the same dimensions, especially construction equipment and construction period shortening The economic effect of is enormous.

  On the other hand, fiber-reinforced composite materials (FRP), among other resin-based materials, have high specific strength (strength per unit weight) and are promising as structural members, but they are resistant to water droplets and foreign matter that collide at high speed. Is the biggest challenge. As a prior art of the resin material, for example, “Method of forming a composite structure having a mounting flange” disclosed in Japanese Patent Application Laid-Open No. 2008-128249 can be cited. Although this is a lightweight nozzle technology that focuses on the flange shape of the stationary structural member of a steam turbine, no proposal has been found that directly refers to avoiding water droplet erosion.

  Next, the configuration of the steam turbine and the problems when it is configured with resin-based members will be described. FIG. 13 is a view showing a stationary blade row and a moving blade blade row constituting a general axial flow steam turbine. As shown in FIG. 13, the steam turbine is rotatably provided in the casing 12 and the casing 12. A plurality of stationary blades 4 are disposed in the casing 12 between the inner ring 6 and the outer ring 7 in the circumferential direction. A plurality of rotor blades 5 are arranged in the circumferential direction on the turbine rotor 8, and the rotor blades 5 are covered with a tip cover 9. As described above, the axial-flow steam turbine has a plurality of stages including such a stationary blade row and a moving blade blade row, and these plurality of paragraphs are housed in the casing 12 covering the outermost periphery.

  In each paragraph, when the pressure on the inlet side of the steam flow 3 is P1, the pressure decreases to P2 by passing through the stationary blade 4, and expands to increase the volume, and at the same time, the steam outflow direction is changed to the turbine rotation direction. As a result, it is converted into circumferential velocity energy. The speed energy in the circumferential direction is converted into rotational torque by the reaction force caused by turning in the anti-rotation direction by the moving blade 5 and at the same time the reaction force by further expanding and increasing the outflow speed by reducing the pressure to P3. .

  FIG. 13 particularly shows the final stage of the low-pressure turbine and the first stage just before it. As shown in FIG. 13, there are a large number of water droplets of several microns to several hundred microns, particularly in the last paragraph and immediately preceding paragraph inside the low-pressure turbine. First, the water vein 13 is formed on the surface of the stationary blade 4, and further, the stationary blade Along with the coarse water droplets 14 blown off from 4, it rides on the flow of steam and collides with the passage member at the steam flow rate and rotation speed.

  As shown in FIG. 14, when the tip of the moving blade 5 is viewed in detail, the coarse water droplets 14 and the blade surface water veins 15 are concentrated and accumulated on the outer peripheral side by centrifugal force, and the outer peripheral corners and seal fins of the tip cover 9 are concentrated. 10 is discharged at high speed in the radial direction from the tip portion. In FIG. 14, the water droplets consist of a leading edge discharge water droplet 16a, a fin discharge water droplet 16b, and a trailing edge discharge water droplet 16c. Further, in the operation of the steam turbine, an uneven temperature change of the rotor and the casing is unavoidable, and a difference in thermal expansion occurs between the rotating part and the stationary part. Therefore, the axial relative movement distance δ of the moving blade 5 is equal to the opposing outer ring. On the other hand, it may reach several tens of millimeters. For example, when a part or the whole of the last stage stationary blade structure, which is the largest part constituting the passage portion, is manufactured from a resin material, it is necessary to avoid erosion. It has been found that the collision speed due to water droplets is the highest. As shown in FIG. 15, the erosion of the facing surface of the tip cover 9 of the outer ring 7 is the most severe in the existence range w of the tip cover 9.

  When the stationary blade structure is made of a metal material, the erosion is sufficiently small within a soundness confirmation interval such as a periodic inspection, but the resin-based material is more than acceptable. Therefore, in order to improve the reliability of the steam turbine to which the resin-based material is applied, not only measures for protecting the assumed erosion range but also the leading edge discharge water droplet 16a and the support discharge water droplet 16c as shown in FIG. It is necessary to assume in advance a method for dealing with unexpected erosion.

JP 2008-128249 A

  The present embodiment has been made in consideration of such points, and an object thereof is to provide a steam turbine that can prevent erosion and reduce the weight as a whole.

  The steam turbine according to the present embodiment includes a casing, a turbine rotor that is rotatably provided through the casing, a moving blade that is connected to the turbine rotor, and a stationary blade that is disposed in the casing. An outer peripheral cover having an inner wall that covers the moving blade, and the inner wall has at least the most upstream end of the tip of the moving blade from the axial position when the moving blade is positioned at the most upstream position. During the rotation of the blade, the most downstream end of the tip of the blade is harder than the members in other ranges in the blade facing portion that covers the blade blade tip existing range up to the axial position when it is located on the most downstream side. A steam turbine including a hard member.

Explanatory drawing which shows the paragraph structure in 1st Embodiment of a steam turbine. The A direction arrow directional view of FIG. Explanatory drawing which shows the attachment structure of a resin member. It is B line direction sectional drawing of FIG. 1, and is explanatory drawing which shows the attachment structure of a metal member. The C direction arrow directional view of FIG. Explanatory drawing which shows the attachment structure of the monolithic member made from a ceramic. Explanatory drawing which shows 2nd Embodiment of a steam turbine. Explanatory drawing which shows the water droplet erosion from the moving blade front-end | tip part and the flow of a water droplet in the modification of a steam turbine. Explanatory drawing similar to FIG. 8 which shows the other modification of a steam turbine. Explanatory drawing which shows 3rd Embodiment of a steam turbine. Explanatory drawing which shows the shape of the outer ring | wheel in the modification of a steam turbine. Explanatory drawing which shows the shape of the outer ring | wheel in the modification of a steam turbine. Explanatory drawing which shows a general steam turbine. The enlarged view which shows the front-end | tip part of the moving blade of FIG. The figure explaining the movement width of the front-end | tip part of a moving blade. Explanatory drawing which shows 4th Embodiment of a steam turbine.

First Embodiment Hereinafter, the present embodiment will be described with reference to the drawings.

  1 to 6 are views showing a first embodiment of a steam turbine.

  As shown in FIG. 1, the steam turbine according to the present embodiment includes a casing 12, a turbine rotor 8 that is rotatably provided through the casing 12, and a plurality of metal rotor blades 5 that are connected to the turbine rotor 8. And a metal inner ring 6 and a metal outer ring 7 are provided in the casing 12, and a plurality of metal vanes 4 are disposed between the inner ring 6 and the outer ring 7 along the circumferential direction. ing.

  A plurality of blades 5 connected to the turbine rotor 8 and arranged along the circumferential direction constitute a moving blade row, and a plurality of stationary blades 4 arranged along the circumferential direction between the inner ring 6 and the outer ring 7. Constitutes a stationary blade row, and the moving blade row and the stationary blade row constitute a stage of the steam turbine.

  A plurality of rotor blades 5 connected to the turbine rotor 8 and arranged in the circumferential direction are covered with a tip cover (tip portion) 9.

  An outer ring 7 of the stationary blade 4 surrounds the outer periphery of the moving blade 5, and an inner wall 17 </ b> A having a metal member 17 and a resin member 18 is supported on the inner peripheral surface of the outer ring 7. In this case, the outer ring 7 that supports the inner wall 17A functions as an outer peripheral cover.

  Further, the most downstream end of the tip cover 9 of the moving blade 5 is in operation from the axial position when the most upstream end of the tip cover 9 of the moving blade 5 is operating, that is, during rotation of the moving blade. That is, the range up to the axial position at the most downstream position during rotation of the moving blade is the moving blade tip portion existing range w. The metal member 17 of the inner wall 17A is disposed so as to cover at least the moving blade tip portion existence range w extending in the axial direction, and the resin member 18 of the inner wall 17A is disposed on the downstream side of the metal member 17. .

  Here, if the occupation range in the axial direction in which the moving blade 5 moves in the axial direction, that is, the moving blade tip portion existing range is w, the metal member 17 faces the moving blade tip portion 9 and extends in the axial direction. The moving blade facing range W of the metal member 17 covers the moving blade tip portion existing range w.

  Specifically, the relationship between the moving blade facing range W in the axial direction of the metal member 17 and the moving blade tip portion existing range w of the tip cover 9 is W> w, and the moving blade tip portion exists. The range W is included in the moving blade facing range W (see FIG. 1).

  The metal member 17 constituting the inner wall 17A is made of a hard member such as stainless steel, and the metal member 17 is harder than members in other ranges of the inner wall 17A, for example, the resin member 18 on the downstream side of the metal member 17. ing.

  Next, the mounting structure of the resin material 18 on the inner wall 17A will be described with reference to FIGS.

  2 and 3 are views taken along arrow A in FIG. Although the resin member 18 is attached to the inner periphery of the outer ring 7, this resin member 18 may be attached to the inner periphery of the outer ring 7 as an annular mold integrally extending in the circumferential direction, as shown in FIG. As described above, the resin member 18 may be divided into a plurality of divided portions 18 a by dividing the resin member 18 in the circumferential direction. Further, as shown in FIG. 3, the divided portion 18 a of the resin member 18 is provided with a counterbore and the outer ring 7 on the outer peripheral side is provided with a bolt through hole 7 h so that the divided portion 18 a is bolted with the bolt 19 and the nut 20. Can do.

  As shown in FIG. 3, the head portion 19 a of the bolt 19 positioned on the divided portion 18 a side of the resin member 18 does not protrude into the steam flow and does not disturb the flow.

  With such a configuration, the resin member 18 can be easily detached from the outer ring 7. Furthermore, if this example is applied to the final stage of the turbine, only the resin member 18 can be detached from the exhaust end of the turbine.

  Next, the attaching / detaching action of the metal member 17 will be described using the BB cross-sectional view of FIG. 1 shown in FIG. Since the metal member 17 is disposed on the facing surface of the rotor blade 5, there is no space for extracting the metal member 17 on the inner diameter side. Therefore, in order to attach and detach the metal member 17 without taking out the turbine rotor 8 provided with the moving blade 5, it is necessary to insert and remove in the direction of the rotation axis.

  According to the present embodiment, the outer ring 7 is provided with the fitting groove 22, and the metal member 17 having the hook 23 can be inserted and assembled in the axial direction (see FIG. 4). With this configuration, both the metal member 17 and the resin member 18 can be attached and detached without disassembling the turbine rotor. The metal member 17 and the resin member 18 may be detachably attached, for example, by bonding.

  Next, the operation of the present embodiment having such a configuration will be described. As shown in FIG. 1, during the operation of the steam turbine, the steam flow 3 flows from the stationary blade 4 to the moving blade 5 side. Coarse water droplets 14 blown off from the stationary blade row or the outer peripheral wall surface or water droplets generated in the steam flow collide with the moving blade 5 to form a moving blade surface water vein 15. Coarse water droplets 14 and blade surface water veins 15 are concentrated and accumulated on the outer peripheral side of the rotor blades 5 by centrifugal force, and the collected water droplets have a radius from the corners of the outer peripheral surface of the tip cover 9 and the tip portions of the seal fins 10. In the direction, the leading edge discharging water droplet 16a, the fin discharging water droplet 16b, and the trailing edge discharging water droplet 16c are discharged at high speed. Although the water droplets collide with the opposing inner wall 17A at a speed exceeding 100 m / s, according to the present embodiment, the portion of the inner wall 17A where the water droplet collides is made of the metal member 17.

  Theoretically, water droplets are expected to be released from the moving blade tip existing range w of the tip cover 9 of the moving blade 5 in consideration of the difference in thermal expansion between the rotating portion and the stationary portion. It has the axial length of the moving blade facing range W that covers the range w of the cover 9 (larger). Thus, the inner wall 17A has members having different hardness depending on the axial position, that is, the metal member 17 and the resin member 18. Specifically, a metal member 17 having a moving blade facing range W larger than the moving blade tip portion existing range w is provided, and a resin member 18 is provided on the downstream side of the metal member 17 to release water droplets from the tip portion of the moving blade 5. Therefore, the shell stationary blade structure can be reduced in weight.

  Next, in the inspection performed in the middle of the turbine operation, an advantage due to the fact that the metal member 17 can be attached and detached will be added. At the design stage, the metal member 17 has a wider blade facing range W that covers the blade tip portion existing range w, assuming that the erosion range, that is, the blade tip portion existing range is w. By the way, since the internal flow of steam, the number of water droplets, and the amount of water greatly change according to the plant load, unexpected erosion as shown by the leading edge discharge water droplet 16a and the support discharge water droplet 16c shown in FIG. 15 may occur. It is extremely difficult to predict all such damaged parts, and it is practically necessary to assume that unexpectedly damaged parts appear in a test run or an inspection immediately after the start of operation. According to the present embodiment, the metal member 17 facing the tip cover 9 of the moving blade 5 is detachably provided on the outer ring 7, and the hard material can be deployed in the optimum range by correcting and reinforcing the shape. As a result, the water drop resistance is dramatically improved.

  Next, a modification of the present embodiment will be described with reference to FIGS. In the modification shown in FIGS. 4 and 5, a part of the metal material 17 is replaced with a resin member 24, and a hard protective layer 21 such as a fine ceramic represented by SiC is formed on the inner surface of the resin member 24. . The fine ceramic material constituting the hard protective layer 21 has a hardness of 2 to 4 and a wear resistance of stainless steel, and is suitable for water wear resistance.

  In general, it is known that destruction of a material proceeds from a defect and stress concentration on a minute part. However, the hard protective layer 21 covering the resin member 24 is required for surface hardness and is not an application of stress. Therefore, there is no hindrance to use. As shown in FIGS. 4 and 5, the metal member 17 and the resin member 24 have a hook 23, and the outer ring 7 is provided with a fitting groove 22 in which the metal member 17 and the hook 23 of the resin member 24 are fitted.

  Since the hard protective layer 21 has a property that the probability of defects increases as the member size increases, as shown in FIG. 5, the hard protective layer 21 is used in the protective layer as a tile-shaped ceramic piece 25 in advance, so that it is unspecified by impact during operation. Therefore, it is possible to improve the reliability without breaking and breaking.

  Next, another modification of the present embodiment will be described with reference to FIG. In the modification shown in FIG. 6, a fine ceramic monolithic (single) member 26 excellent in water droplet erosion is provided instead of the metal material 17. When the monolithic member 26 made of fine ceramic is provided, stress concentration occurs at the base of the hook 23 of the monolithic member 26 as shown in FIG. For this reason, as shown in FIG. 6, the cross-sectional shape of the monolithic member 26 made of fine ceramic has a gradual change, specifically, a shape having a cross-sectional depression angle α> 90 degrees. 4 and 6, there is no possibility that a tensile force is applied to the resin member 24 or the fine ceramic monolithic member 26, and there is a high possibility that a force pressing in the outer circumferential direction by the steam force is applied. It is possible to maintain reliability.

Second Embodiment Next, a second embodiment of the steam turbine will be described with reference to FIGS.

  In the second embodiment shown in FIGS. 7 to 9, a space 28 is formed between an inner wall 17A composed of a metal member 17 and a resin member 18 and an outer ring 7 that supports the inner wall 17A.

  In the second embodiment shown in FIG. 7 to FIG. 9, the same parts as those in the first embodiment shown in FIG. 1 to FIG.

  As shown in FIG. 7, a metal member 17 and a resin member 18 constituting the inner wall 17 </ b> A are provided on the inner surface of the outer ring 7 side by side in the axial direction.

  7 to 9, the metal member 17 and the resin member 18 are arranged in the axial direction so as to cover the space 28 of the outer ring 7, and the metal member 17 and the resin member 18 are bolts that penetrate the metal member 17 and the resin member 18. 27.

  Here, the metal member 17 is good also as a member provided with the ceramic protective layer 21 in the resin member 24 (refer FIG. 4). As shown in FIG. 6, the weight of the outer ring 7 can be reduced by forming the space 28 on the inner surface of the outer ring 7.

  Next, a modification of the present embodiment will be described with reference to FIGS.

  FIG. 8 shows a case where the resin member 18 is eroded by water droplets that are not designed. When the resin member 18 is eroded, the erosion gap 29 penetrates the resin member 18, but the erosion gap 29 is formed by holding the resin member 18 and the metal member 17 forming the space 28 with the fastening bolts 27. However, the resin member 18 does not fall off. Further, a hard layer 30 such as a ceramic coating or a metal plate lining is provided to cover the ceiling and side walls of the inner surface of the space 28, and the outer ring 7 is not eroded and cut by the hard layer 30. .

  Even when the resin member 18 is eroded in this way, it becomes clear at the next open inspection opportunity, and the metal member 17 and the resin member 18 can be easily detached from the outer ring 7. For example, measures such as extending the axial dimension of the metal member 17 to the downstream side can be taken.

  Further, as shown in FIG. 8, the erosion gap 29 may be left and used as a drain passage. That is, the drain water droplets that have passed through the erosion gap 29 of the resin member 18 are stored in the space 28, but the drain water droplets are restored from the drain hole 31 by providing the drain hole 31 at or near the vertical position of the outer ring 7. It can be discharged towards a water vessel (not shown).

  In general, a drain discharge slit that performs the same function as the erosion gap 29 of the present invention is provided in the rear several stages of a turbine that is relatively non-reheat type and has a relatively high wetness. Since it cannot be specified, an unnecessarily large space is provided.

  Therefore, as shown in FIG. 9, a resin member 18 is disposed on the tip cover 9 or the seal fin 10 of the rotor blade 5 or on the outer peripheral side facing surface of the MEB groove (not shown). Thus, by using the erosion gap 29 formed by the water droplet collision on the resin member 18 as the drain discharge slit, it is possible to remove the actual water droplet with the minimum necessary width.

Third Embodiment Next, a third embodiment of the steam turbine will be described with reference to FIGS.

  The embodiment shown in FIGS. 10 to 12 differs only in the structure of the outer ring 7 of the stationary blade 4 and the inner wall 17A, and the other configurations are substantially the same as those of the first embodiment shown in FIGS. It is.

  In the third embodiment shown in FIG. 10 to FIG. 12, the same parts as those in the first embodiment shown in FIG. 1 to FIG.

  As shown in FIG. 7, the outer ring 7b of the stationary blade 4 is made of a resin material.

  Similarly to the first embodiment shown in FIGS. 1 to 6, a metal member 17 and a resin member 18 are arranged on the inner surface of the outer ring 7 b made of a resin material, and the outer ring is formed by the metal member 17 and the resin member 18. An inner wall 17A supported on the inner surface of 7b is configured.

  Next, a modification of the present embodiment will be described with reference to FIG.

  As shown in FIG. 11, the outer ring 7c is made of a resin material, and the metal member 17 is supported on the inner surface of the outer ring 7c. In this case, the metal member 17 is held on the outer ring 7c by bolts 33 and nuts 34. The portion of the outer ring 7c on the downstream side of the metal member 17 has the same function as the resin member 18 on the downstream side of the metal member 17 shown in FIGS.

  Since it is difficult to pull out the metal member 17 provided on the outer ring 7 c in the axial direction, the metal member 17 is fastened in the radial direction by the bolt 33 and the nut 34.

  Next, another modification of the present embodiment will be described with reference to FIG. As shown in FIG. 12, the stationary blade 4a and the outer ring 7c are integrally formed of a resin material, and an inner wall 17A having a metal member 17 and a resin member 18 made of a material different from the outer ring 7c is provided on the inner surface of the outer ring 7c. It has been.

  In the embodiment shown in FIGS. 10 to 12, it is possible to reduce the weight of the structure or the entire structure of the stationary blade 4 at the final stage, which is the largest component constituting the passage portion, to about 1/5. Become. Further, by molding the outer rings 7b, 7c or the stationary blade 4a from the fiber reinforced composite resin material, the structural strength is dramatically increased, and in particular, the design strength corresponding to the stress caused by the steam force applied to the structure of the stationary blade 4a is expanded. can do.

Fourth Embodiment Next, a fourth embodiment of the steam turbine will be described with reference to FIG.

  The embodiment shown in FIG. 16 is obtained by removing the tip cover 9 and the seal fin 10 that cover the plurality of moving blades 5, and other configurations are substantially the same as those of the first embodiment shown in FIGS. 1 to 6. It is.

  In the fourth embodiment shown in FIG. 16, the same parts as those in the first embodiment shown in FIGS. 1 to 6 are denoted by the same reference numerals, and detailed description thereof is omitted.

  In FIG. 16, the tip cover 9 and the seal fin 10 that cover the plurality of moving blades 5 are not provided. For this reason, the plurality of moving blades 5 themselves constitute the tip portion.

  In addition, embodiment is an illustration and the range of invention is not limited to it.

3 Steam flow, 4 Stator blade, 4a Stator blade made of resin material, 5 Rotor blade, 6 Inner ring, 7 Outer ring, 7b Outer ring made of resin material, 7c Outer ring made of resin material, 8 Turbine rotor, 9 Tip cover, 10 Seal Fin, 11 Tip gap, 12 Casing, 13 Stator blade surface water vein, 14 Coarse water droplet, 15 Rotor surface water vein, 16a Leading edge discharge water droplet, 16b Fin discharge water droplet, 16c Trailing edge discharge water droplet, 17 Metal member, 18 Resin member, 19 bolt, 20 nut, 21 hard protective layer, 22 fitting groove, 23 hook, 24 resin member, 25 ceramic piece, 26 monolithic member, 27 bolt, 28 space, 29 erosion gap, 30 drain hole, 31 drain path, 33 bolts, 34 nuts, P1 turbine stage inlet side pressure, P2 turbine stationary blade outlet side and rotor blade inlet side Pressure, P3 turbine stage outlet pressure, W rotor blade facing range, w Tip cover existing range

Claims (12)

A casing,
A turbine rotor provided rotatably through the casing;
A rotor blade connected to the turbine rotor;
A stationary blade disposed in the casing;
An outer peripheral cover having an inner wall covering the bucket,
The inner wall is located at the most downstream end of the moving blade from the axial position when the most upstream end of the moving blade is positioned at the most upstream position while the rotating blade is rotating, and the most downstream end of the moving blade is positioned at the most downstream position during the rotating blade. In the moving blade facing range that covers the moving blade tip portion existing range up to the axial position when including a hard member that is harder than other range members,
The hard member includes a metal member, steam turbines the other range of the member you comprising a resin member. A casing,
A turbine rotor provided rotatably through the casing;
A rotor blade connected to the turbine rotor;
A stationary blade disposed in the casing;
An outer peripheral cover having an inner wall covering the bucket,
The inner wall is located at the most downstream end of the moving blade from the axial position when the most upstream end of the moving blade is positioned at the most upstream position while the rotating blade is rotating, and the most downstream end of the moving blade is positioned at the most downstream position during the rotating blade. In the moving blade facing range that covers the moving blade tip portion existing range up to the axial position when including a hard member that is harder than other range members,
The inner wall comprises a member that ceramic member or a ceramic protective layer is provided, steam turbines the other range of the member you comprising a resin member. The steam turbine according to claim 2 , wherein the ceramic material or the ceramic protective layer includes a divided portion that is divided into tile-shaped pieces in advance. The steam turbine according to claim 2, wherein the resin material has a space between the outer peripheral cover and the resin material. The steam turbine according to claim 4 , wherein an inner surface of the outer peripheral cover that forms the space is covered with a metal cover. The steam turbine according to claim 4 , wherein an inner surface of the outer peripheral cover that forms the space is covered with a ceramic material or a ceramic coating. Steam turbine according to any one of claims 4 to 6, characterized in that drainage holes on the outer peripheral cover forming the space are provided. A casing,
A turbine rotor provided rotatably through the casing;
A rotor blade connected to the turbine rotor;
A stationary blade disposed in the casing;
An outer peripheral cover having an inner wall covering the bucket,
The inner wall is located at the most downstream end of the moving blade from the axial position when the most upstream end of the moving blade is positioned at the most upstream position while the rotating blade is rotating, and the most downstream end of the moving blade is positioned at the most downstream position during the rotating blade. In the moving blade facing range that covers the moving blade tip portion existing range up to the axial position when including a hard member that is harder than other range members,
The outer peripheral cover is steam turbine you, comprising the vane outer ring including a resin member. A casing,
A turbine rotor provided rotatably through the casing;
A rotor blade connected to the turbine rotor;
A stationary blade disposed in the casing;
An outer peripheral cover having an inner wall covering the bucket,
The inner wall is located at the most downstream end of the moving blade from the axial position when the most upstream end of the moving blade is positioned at the most upstream position while the rotating blade is rotating, and the most downstream end of the moving blade is positioned at the most downstream position during the rotating blade. In the moving blade facing range that covers the moving blade tip portion existing range up to the axial position when including a hard member that is harder than other range members,
The outer peripheral cover is steam turbine you characterized by being integrally molded with member of another range of the inner wall. The steam turbine according to claim 9 , wherein the outer peripheral cover and the stationary blade are formed of an integrally formed resin assembly. It said other range of member is characterized by comprising a fiber-reinforced composite resin material, the steam turbine according to any one of claims 1 to 10. The steam turbine according to any one of claims 1 to 11, wherein at least one of the hard member on the inner wall or the member in another range is detachable from the outer peripheral cover.

Images