JP2015081588A - Steam turbine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a structure capable of maintaining sealability even if a rotor rotates to make a gap between adjacent surfaces of rotor blades formed into a V-shape.SOLUTION: Provided is a steam turbine configured so that a tree-type fitting portion is formed at a rotor wheel section of a rotor and a root of each rotor blade so as to arrange a plurality of rotor blades each constituted by a wing and the root in a rotor circumferential direction. The tree-type fitting portion forms at least one hook constituted by a concave portion and a convex portion, a groove is formed in at least one of bonded surfaces of the roots of the adjacent rotor blades so as to surround the hook, and an elastic body is arranged in the groove between the rotor blade with the groove and the adjacent rotor blade in a compressed state.

Description

  The present invention relates to a steam turbine in a power plant, and more particularly to a steam turbine provided with a technique for blocking a fitting portion between a moving blade and a rotor from an external environment.

  Steam turbines in power plants are exposed to corrosive fluids such as oxidizing atmospheres and hot atmospheres. Metals used in these structures are destined to be corroded or oxidized when exposed to corrosive fluids such as oxidizing atmospheres, except for precious metals. Usually, at the time of designing, it is designed so that a predetermined strength and function are maintained over the entire lifetime in consideration of a corrosion rate and an oxidation rate under an assumed environment.

  However, the progress of corrosion may become noticeable due to changes in operation, operation method, environment, or the appearance of new phenomena that were not assumed in the design stage. The problem with steam turbines in particular is environmentally assisted cracking such as stress corrosion cracking and corrosion fatigue involving corrosion, and if this occurs, operation stop is required for inspection and repair, which hinders stable power supply. There is a possibility of causing.

  The most affected by corrosion in current steam turbines, the place where damage is a concern is where the rotor blades and rotor are fitted in a Christmas tree-like structure. This fitting portion is a place where stress is severe because there is a gap and a stress concentration portion at the root portion of the hook due to the centrifugal load from the moving blade generated during operation.

  In order to prevent the above environmentally assisted cracking, improvements are made from the viewpoints of stress, material, and environment, which are the three factors of environmentally assisted cracking. For stress, take a shape and structure that avoids stress concentration, and for materials, for example, use materials with reduced proof stress and low stress corrosion cracking susceptibility. For the environment, steam in the steam turbine does not enter the fitting part The fitting part is covered and filled, or a seal part is provided.

  Of these three factors, stress, material, and environment, the method of shutting down the environment is only necessary to shut off the steam that is the cause of environmentally assisted cracking so that it does not flow into the fitting part. In addition, the degree of freedom in selecting materials for rotor materials and rotor blade materials is high, and furthermore, since there are no causative substances, stress restrictions are relaxed, resulting in design. It has many advantages such as increased tolerance.

  For this reason, many inventions relating to environmentally assisted cracking technology from the environmental aspect have been provided. For example, in Patent Document 1, an environment-free (seal) is achieved by filling an adhesive without carbon molecules between a moving blade and a moving blade. Although the purpose and object are different, Patent Document 2 proposes an invention in which a tapered groove is provided in a moving blade, a pin is inserted into the groove, and a sealing property between the moving blade and the moving blade is maintained.

JP-A-2-248602 JP 2011-32985 A

  The above-mentioned patent document 1 is a means for preventing steam from flowing into the fitting portion and, as a result, avoiding corrosion and environmentally assisted cracking.

  However, normally, when the rotor is stopped, the adjacent surfaces of the moving blade and the moving blade are in close contact with each other, but when the rotor starts to rotate, a centrifugal force causes an opening between the contacting moving blade and the moving blade. Thus, the steam can easily reach the fitting portion through the open gap. Recently, as a phenomenon that has become clear, the gap between the open rotor blades and the rotor blades is not uniform, and the width between the rotor blades and the rotor blades increases from the central axis of the rotor toward the outer radial direction. There is a tendency to spread and open in a V shape.

  For this reason, in the case of Patent Document 2, for example, there is a concern that a phenomenon occurs in which the center axis side of the moving blades and adjacent surfaces of the moving blades can maintain the sealing performance, but the outer peripheral side has insufficient environmental barrier (sealing performance). is there. In the case of Patent Document 2, since the pins and grooves for maintaining the sealing performance provided on the adjacent surfaces of the moving blades are uniform in thickness and depth, the gap between the moving blades and the moving blades is V-shaped. In such a case, there is a concern that the sealing performance gradually decreases from the center of the rotor shaft toward the outer radial direction as in Patent Document 1.

  From the above, the present invention provides a structure that can maintain the sealing performance even when the rotor rotates and the interval between adjacent surfaces of the moving blades and the moving blades becomes V-shaped.

  From the above, in the present invention, in order to arrange a plurality of rotor blades composed of blade portions and root portions in the circumferential direction of the rotor, a tree-type fitting portion is formed at the rotor wheel portion of the rotor and the root portion of the rotor blades. The tree-type fitting portion forms at least one hook composed of a concave portion and a convex portion, and a groove is formed so as to surround the hook on at least one of the joint surfaces of the adjacent blade root portions. The groove is characterized in that an elastic body is disposed in a compressed state between the moving blade provided with the groove and the adjacent moving blade.

  In the present invention, even in the gap between a moving blade and a moving blade that may open a V-shape by the above-described function, the elastic body adheres with good followability and the sealing performance is maintained. As a result, even when the rotor is stopped or rotating, it is possible to effectively prevent steam and the like flowing into the fitting portion between the rotor and the moving blade. Therefore, it is possible to provide a steam turbine that can prevent corrosion of the fitting portion and is excellent in resistance to environment-assisted cracking such as stress corrosion cracking and corrosion fatigue.

The figure which shows the cross-sectional schematic of a low pressure steam turbine axial direction. The bird's-eye view which expanded centering on the fitting part of the rotor of a part A of FIG. 1, and a moving blade. The figure which shows the positional relationship of a moving blade at the time of rotation. BRIEF DESCRIPTION OF THE DRAWINGS Schematic which shows Example 1 of this invention. The figure for demonstrating the arrangement | positioning relationship between a single moving blade and an elastic body. The figure which shows the state which assembled the some moving blade on the rotor wheel. The figure which looked at the bird's-eye view shown in FIG. 6 from the side. Schematic which shows Example 2 of this invention. Schematic which shows Example 3 of this invention. The three-dimensional figure which described the shape of the elastic body somewhat exaggeratedly.

  Embodiments of the present invention will be described below with reference to the drawings.

  First, with reference to FIGS. 1, 2 and 3, the structure of the turbine and phenomena such as corrosion and environmentally assisted cracking occurring at the root of the rotor blade will be described. The embodiment of the present invention will be described in detail later with reference to FIGS.

  First, the structure of the steam turbine will be briefly described. For example, power generation steam turbines are classified into thermal power, nuclear power, geothermal heat, and the like according to the generation source of steam, and are configured by combining a plurality of steam turbines according to steam temperature, pressure, and flow rate. However, there is no significant difference in the structure of a single steam turbine. Therefore, unless otherwise specified, a low-pressure turbine used in a region where the steam temperature is from room temperature to around 200 ° C. will be described below. This is because phenomena such as corrosion and environmentally assisted cracking often occur mainly in the steam temperature range of 80 ° C to 150 ° C.

  FIG. 1 shows a schematic cross-sectional view in the axial direction of the low-pressure steam turbine. The steam turbine mainly includes a rotor 1 which is a rotating body, a moving blade 2 attached to the rotor 1, a stationary blade 4 which rectifies steam and efficiently supplies steam to the moving blade, and a casing 3 surrounding them. ing. A plurality of multi-stage disc-shaped rotor wheels 101 are formed on the rotor 1, and the rotor blades 2 are arranged in close contact with the outer periphery of the rotor wheel 101 in an annular shape.

  FIG. 2 is a bird's eye view of the portion A shown in FIG. 1, with the fitting portion 102 between the rotor 1 (rotor wheel 101) and the rotor blade 2 being the center. However, although only three blades 2 are shown in this figure, the blades 2 are installed over the entire circumference of the fitting portion 102 of the rotor wheel 101.

  There are several types of fitting methods for the rotor wheel 101 and the rotor blade 2. One is to feed the pin into the fork groove and fix it, and the second is to form a tree-shaped groove in the rotor wheel 101 along the axial direction of the rotor, and the rotor blade 2 is fitted here. There are various methods for combining them. Here, a tangential entry structure in which tree-shaped grooves are provided in the circumferential direction of the rotor wheel 101 will be described. This method tends to be frequently used in the paragraph where the steam temperature is about 80 ° C. or higher, and FIG. 2 is a typical example.

  As shown in FIG. 2, the outer edge portion of the rotor wheel 101 has a tree structure, and the tree-shaped portion is shown as the fitting portion 102. The fitting portion that fits with the outer edge portion of the rotor wheel 101 on the inner edge portion side of the rotor blade 2 is processed according to this tree structure shape. Thereby, it is designed to withstand the centrifugal stress and the steam flow generated when the rotor 1 rotates.

  On the other hand, changes in steam environment, operation, operation method, accumulation of impurities, etc. may cause corrosion and environmentally assisted cracking. A particularly stressful place is the root of the hook 103 of the rotor wheel 101 shown in FIG. That is, the shape of the tree-shaped fitting portion shown in FIG. 2 is such that a portion with a large lateral width (convex portion) and a portion with a narrow lateral width (concave portion) are alternately repeated from the axial center toward the rotor side, and the outer edge portion. The width is reduced as For this reason, the base of the hook 103 located at the outermost edge (the concave portion closest to the tip and having the narrowest lateral width) of the combination portion of the unevenness (hook 103) is a place where the stress is severe.

  In this part, stress may be concentrated before and after the material yield strength due to centrifugal stress. In addition to stress, another cause of these corrosion and environmentally assisted cracking is that steam enters the fitting portion 102. In particular, when impurities are contained in the vapor, it accumulates in the fitting portion 102 and further accelerates corrosion and environmentally assisted cracking. Furthermore, the application of stress cycles accompanying the start and stop of the steam turbine is also considered as an acceleration factor.

  It has become clear that the presence of steam or water is essential for the occurrence of corrosion and environmentally assisted cracking, and in order to prevent these, the entry of steam into the fitting portion 102 is prevented. Most effective. One or a plurality of hooks 103 are connected to the fitting portion 102. In particular, environmentally assisted cracking is more likely to occur on the outer peripheral side, and it is particularly effective to prevent steam from entering this portion. The reason for this is thought to be that the following factors are working in addition to stress factors.

  When the steam turbine is stopped, the moving blade 2 and the moving blade adjacent to the moving blade 2 are in close contact with each other as shown in FIG. The moving blades that are in close contact with each other are separated from each other by stress, and a gap is generated. At this time, it becomes easier for more steam to reach the fitting portion 102 through the generated gap.

  FIG. 3 shows the positional relationship of the moving blades during rotation. At this time, the gap generated between the moving blade 2 and the moving blade adjacent to the moving blade 2 is not uniform, and the outer peripheral side seems to have a wider V-shaped gap. This is shown as “opening” in FIG. For this reason, it is considered that the hook 103 on the outer peripheral side has more opportunities to come into contact with steam, and environmentally friendly cracking is likely to occur.

  Thus, since it is considered that the rotor blades 2 are unevenly opened in a V shape during operation, an effective sealing performance can be obtained only by arranging a general gasket between the adjacent rotor blades 2. difficult. Usually, when the gasket is tightened, in order to prevent the occurrence of permanent elongation, if the gasket is rubber, the compression rate is limited to about 20 to 30%.

  However, if the opening gap is uniform regardless of the location, there is no problem with a gasket having a uniform thickness, but if there is a deviation in the opening gap as shown in FIG. 3, the sealing effect cannot be obtained. For example, when the gasket thickness is determined so that a sealing effect can be obtained in accordance with the most open part, when the gap is closed, the compression rate of the most open part is 30%, which is the limit at which permanent extension does not occur. It may exceed. On the other hand, if the gasket thickness is determined in accordance with the portion that is least open, the sealability of the most open portion may be insufficient when a gap occurs.

  In consideration of the above-described problems, Embodiment 1 of the present invention will be described below. FIG. 4 is a schematic diagram showing Example 1 of the present invention. FIG. 4 shows a single structure of the moving blade 2 according to the embodiment of the present invention. The moving blade 2 includes a blade portion 2a and a root portion 2b. A tree-shaped fitting portion 102 is formed on the inner side of the root portion 2 b so as to match the fitting portion of the rotor wheel 101. However, although the fitting portions of the root portion 2b and the rotor wheel 101 are formed so as to have a male-female relationship, it is inevitable that a gap is actually generated between them.

  In the present invention, the groove 201 is formed so as to surround the fitting portion 102 at the position of the moving blade 2 and the root portion 2b where the moving blade 2 is provided. The groove 201 may be formed on one side of the moving blade 2 root 2b to be provided. In FIG. 4, a single rotor blade 2 is shown, but in reality, a groove 201 is provided at the same location of all the rotor blades 2. The groove 201 is formed in a generally U shape so as to surround the fitting portion 102, and this groove shape has a depth and width that are gradually deeper from the central axis of the rotor in the radial direction, and It has a wide structure.

  In the groove 201 formed on one surface of the rotor blade root 2b, the elastic body 5 having a shape matching the groove shape is installed. FIG. 5 is a diagram for explaining the positional relationship between the single rotor blade 2 and the elastic body 5. The curved elastic body 5 having a shape that fits the depth and width of the groove 201 is fitted into the groove 201. It is matched. The groove 201 is deeper and wider in the radial direction. Similarly, the elastic body 5 is thicker in the radial direction.

  6 is a view showing a state in which a plurality of moving blades 2 (2-1, 2-2, 2-3) are assembled on the rotor wheel 101, and the moving blade 2 in which the elastic body 5 is fitted in the groove 201. FIG. -2 shows a state in which it is combined with other adjacent rotor blades 2-3, 2-1 on the rotor wheel 101. In addition, when a groove | channel is formed in the moving blade 2-2, the groove | channel 201 and the elastic body 5 do not need to be provided in the joint surface of the other moving blade 2-3. Further, when the adjacent rotor blades 2 are brought into close contact with each other, the thickness and width are such that the compressibility of the elastic body 5 is uniform in any linear portion.

  FIG. 7 is a side view of the bird's eye view shown in FIG. When the linear elastic body 5 in the present embodiment is viewed from the side, it has a structure in which the thickness gradually increases in the radial direction as described on the right side of FIG.

  The elastic body 5 used in Example 1 is made of a material selected from ethylene propylene rubber, acrylic rubber, silicon rubber, and fluorine rubber in order to withstand the vapor temperature and various chemical substances. All the rubbers have a heat-resistant safety temperature that exceeds 90 ° C., which is a temperature at which environmentally assisted cracking of a low-pressure steam turbine easily occurs, and is 100 ° C. or higher. In particular, fluororubber has a continuous useable temperature of around 200 ° C. and is excellent in heat resistance and chemical resistance, and therefore has excellent durability.

  The linear elastic body 5 can be easily molded. A mold having a predetermined shape can be manufactured and manufactured by an injection molding method. The cross-sectional shape of the elastic body 5 can be manufactured in any of a circular shape, an oval shape, or a rectangular shape, and a sealing effect can be obtained. However, when it is desired to enhance the sealing function by a line seal, the cross-sectional shape of the elastic body 5 is preferably circular. .

  According to the first embodiment, as shown in FIG. 5, the thickness of the elastic body 5 has a structure that is thick in the radial direction. As a result, even when the gap opening width between the moving blade 2 and the adjacent moving blade 2 is increased as the position from the central axis of the rotor 1 in the radial direction is large, the amount of change of the elastic body 5 is large, so that sealing performance is ensured. can do.

  In the first embodiment, the groove 201 has a stepped shape that is deep and wide in the radial direction, but at the same time, it is not necessary to have a deep depth and a wide width. Either one may be changed in the radial direction. Since the size of the opening shown in FIG. 3 tends to be different depending on the stage of the turbine, one of the depth and the width can be changed in the radial direction with respect to the portion where the size of the opening is expected to be small. In this case, sufficient sealing performance can be secured.

  Further, in the first embodiment, the structure in which the groove 201 is provided in either one of the adjacent rotor blades 2 is illustrated. However, the present invention is not limited to this, and the sealing effect can be achieved even if the grooves 201 are formed so as to face each other. Is obtained. At this time, since the elastic body 5 can be made thicker, there is an advantage that it is possible to cope with a wider gap between the moving blades.

  Further, the elastic body 5 sandwiched between the moving blade 2 and the adjacent moving blade is exemplified as a range of 20 to 30% when the rotor 1 is not rotating, but is not necessarily limited thereto. In the range of 30% or less in which permanent extension is suppressed, the pressure is arbitrarily selected according to the pressure difference between the external steam and the pressure at the gap between the rotor blade and rotor wheel of the fitting portion shown in FIG. be able to. For example, in a general constant-pressure turbine for electric power, the steam pressure in the third stage counted from the last stage and the condenser side is substantially the same as the atmospheric pressure, and the differential pressure is small. Therefore, the compression rate of the elastic body 5 when the rotor is not rotating can be suppressed to 20% or less, and consideration can be given so as to reduce permanent elongation. Accordingly, the durability of the elastic body 5 can be maintained over a longer period.

  FIG. 10 is a three-dimensional view in which the shape of the elastic body 5 is slightly exaggerated. Therefore, the groove 201 basically has the same width relationship. As is clear from this figure, the vertical and horizontal widths of part A close to the rotor center, the vertical and horizontal widths of part C farthest from the rotor center, and the width of part B at the intermediate position are increased as the distance from the rotor center increases. ing.

  Example 2 will be described below with reference to the drawings.

  The elastic body 5 illustrated in the first embodiment has a structure in which the thickness increases in the radial direction or the central axis of the rotor 1. In this case, as described above, the compression rate is usually used in a range of 20 to 30% in order to suppress permanent elongation. On the other hand, it may be necessary to use the elastic body 5 having a smaller wall thickness, such as a stationary blade portion for inserting the moving blade 2 into the rotor wheel 101, the shape of the rotor wheel 101 or the moving blade 2, and structural restrictions. .

  In this case, as shown in FIG. 8, if the elastic body 5 has a structure similar to the hollow portion 501, the compression rate can exceed 30%. Therefore, it becomes possible to use the elastic body 5 having a smaller thickness, and it is difficult to receive structural restrictions. Even if the elastic body 5 having a hollow structure is used with a compression rate exceeding 30%, the portion where permanent stretching occurs is limited to a part with a small radius of curvature on the outer peripheral side. It becomes difficult to receive and the sealing performance can be maintained for a long time.

  The elastic body 5 having a hollow structure can be manufactured by a mold in which a core is inserted in a portion that becomes a hollow portion. Alternatively, a hollow body having a uniform thickness may be formed first by extrusion molding, and this may be formed by heating and shaping with a mold having a predetermined shape.

  Example 3 will be described below with reference to the drawings.

  According to the second embodiment, it is possible to maintain the sealing performance even when non-uniform gap openings are generated, but the sealing function may be deteriorated due to a manufacturing accuracy defect or aged deterioration. When the sealing function of the elastic body 5 is partially deteriorated, the steam passes over the elastic body 5 and reaches the fitting portion 102. The structure shown in FIG. 9 is adopted so that the sealing function can be recovered even in such a situation.

  In FIG. 9, the hydrophilic portion 501 of the hollow elastic body 5 is filled with the hydrophilic resin 503. In addition, a plurality of communication holes 502 communicating with the hollow interior are provided on the surface of the elastic body 5 on the fitting portion side of the rotor wheel 101 and the rotor blade 2.

  Specifically, the hydrophilic resin 503 is a polymer represented by polyvinyl alcohol. However, in order to avoid dissolution by water at ambient temperature, a polymer having a adjusted degree of polymerization or saponification of polyvinyl alcohol or a copolymer with a non-hydrophilic resin is used. This is filled in the hollow portion 501 in a dry state. When the sealing function of the elastic body 5 is deteriorated and the steam exceeds the elastic body 5 and enters the fitting portion 102 from the elastic body 5, a part of the steam is condensed, and the communication hole 502 facing the fitting surface direction is formed. Thus, the vapor and the droplets reach the hydrophilic resin 503 of the elastic body 5. The hydrophilic resin 503 swells by absorbing moisture. When it swells, a force that pushes and spreads the elastic body 5 from the inside of the hollow works and comes into close contact with the groove 201 of the rotor blade 2.

  Since the hydrophilic resin 503 that has absorbed moisture has high fluidity, the hydrophilic resin 503 may come off partly through the communication hole 502. In such a state, the force to push and expand the hollow interior is weakened and the sealing performance is lowered, but the leaked hydrophilic resin 503 is still present on the inner surface side of the elastic body 5, It functions as an obstacle that suppresses intrusion to the fitting part side.

  However, since there is no guarantee that the effect as an obstacle can be maintained for a long time, it is effective to have means for indicating that steam or water has entered the hollow portion. In Example 3, the hydrophilic resin 503 is filled in the hollow portion 501 of the elastic body 5, but at the same time, for example, when a fluorescent material that emits fluorescence by ultraviolet rays is added, the sealing property of the elastic body 5 is reduced and vapor enters. Then, the phosphor added to the hollow portion 501 leaks out.

  The leaked phosphor oozes out of the elastic body 5 (on the opposite side of the fitting side). When the rotation of the rotor 1 is stopped, that is, when the turbine is inspected for opening, by irradiating ultraviolet rays between the rotor blades 2 and the rotor blades 2, if fluorescence is observed, the seal of the elastic body 5 is lowered. I suggest that. If this means is used, it is possible to know whether or not the elastic body 5 is functioning. This makes it easy to plan and implement replacement of the elastic body 5.

  In Example 3, an example in which the hydrophilic resin 5 and the phosphor are simultaneously present is shown, but the simultaneous presence is not necessarily required, and only one of them can be used depending on the situation and purpose.

  As described in detail above, when the rotor rotates and the adjacent surfaces of the rotor blades and the rotor blades open to form a gap, the steam easily reaches the fitting portion through the generated gap. . At this time, since the gap width may increase toward the outer peripheral side, a seal mechanism capable of following the gap width non-uniformity is required.

  In order to solve this, in the present invention, a groove capable of holding an elastic body is formed in a linear shape on one of adjacent rotor blades so as to surround the fitting surface between the rotor and the rotor blades. The depth and width of the groove are deeper and wider from the central axis of the rotor toward the outer radius. At the same time, the elastic body that is installed in the groove to obtain a sealing property has a linear structure that increases in thickness from the central axis of the rotor toward the outer radial direction. As a result, even when the blade between the blades opens in a V shape, the uniformity of the compression ratio of the elastic body can be maintained from the side closer to the central axis to the side farther away. Sealability can be obtained.

  In addition, since the elastic body can be used with a high compression rate by using a hollow structure, the operating range in which the sealing performance of the elastic body can be maintained becomes wider, and the size of the V-shaped opening changes. Will also be excellent in followability. In the case of rubber typified by EPDM (Ethylene-Propylene diene terpolymer) as an elastic body, it is usually used so that the compression rate is around 20 to 30% in order to avoid permanent elongation during compression as much as possible. By using a hollow structure inside the body, it becomes possible to use at a compression rate exceeding 30%. As a result, the followability of the gap change is excellent.

  Furthermore, the inside of the hollow body is filled with a polymer having excellent hydrophilicity, for example, PVA (Polyvinyl Alcohol), and a hole communicating with the inside of the hollow body is provided. When the vapor enters the hollow body through the hole, the hydrophilic resin filled in the hollow body swells, and this causes a force to push the hollow body and expand the gap between the moving blade and the moving blade. Sealing performance is improved by trying to fill.

  Furthermore, when the hollow body is filled with the phosphor, when the vapor entering from the outside enters the hollow body through the hole, the phosphor moves from the gap between the moving blade and the moving blade through the vapor intrusion path. Leak out. For example, if the phosphor is a substance that emits fluorescence when irradiated with ultraviolet rays, it is possible to know the traces of vapor intrusion by irradiating the vicinity of the joint surface between the moving blades and moving blades when inspecting the steam turbine. Become. As a result, it is not necessary to extract the moving blade and confirm the seal soundness.

DESCRIPTION OF SYMBOLS 1 ... Rotor, 101 ... Rotor wheel, 102 ... Fitting part, 103 ... Hook, 2 ... Moving blade, 201 ... Groove, 3 ... Casing, 4 ... Static blade, 5 ... Elastic body, 501 ... Hollow part, 502 ... Hydrophilic Resin, 503... Hydrophilic resin

Claims (5)

In order to arrange a plurality of moving blades composed of a blade portion and a root portion in the circumferential direction of the rotor, a steam turbine that forms a tree-type fitting portion at the rotor wheel portion of the rotor and the root portion of the rotor blade,
The tree-type fitting portion forms at least one hook composed of a concave portion and a convex portion, and a groove is formed so as to surround the hook on at least one of the joint surfaces of the adjacent blade root portions. The steam turbine is characterized in that an elastic body is disposed in a compressed state between the moving blade provided with the groove and the adjacent moving blade in the groove. The steam turbine according to claim 1,
The depth and width of the groove are processed so as to be deeper and wider in the radial direction from the rotor central axis, and the elastic body is thickened in the radial direction from the rotor central axis. Steam turbine. A steam turbine according to claim 1 or claim 2, wherein
The steam turbine according to claim 1, wherein the elastic body has a hollow structure. The steam turbine according to any one of claims 1 to 3,
The elastic body is a material selected from ethylene propylene rubber, acrylic rubber, silicon rubber, and fluoro rubber, and has a hollow structure, and the hollow interior is filled with at least one of a hydrophilic resin or a phosphor. The steam turbine is characterized in that a plurality of communication holes communicating with the hollow interior are provided on the side surface of the elastic body where the rotor and rotor blade are fitted. The steam turbine according to any one of claims 1 to 3,
The steam turbine according to claim 1, wherein the elastic body is made of a metal that is a non-communication foam.

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