JP5951449B2 - Steam turbine - Google Patents

Description

  Embodiments of the present invention relate to a steam turbine.

  The work efficiency in a steam turbine used in a power plant or the like is influenced by the flow rate of steam that generates power (rotational torque) by rotating a moving blade. Therefore, if the flow rate of the steam leaking from the gap between the stationary part and the rotating part in the steam turbine increases, the work efficiency decreases. Therefore, improvement of the sealing technology between the stationary part and the rotating part in the steam turbine is required.

  FIG. 5 is a diagram schematically showing a part of a meridional section of one turbine stage in a conventional steam turbine. In FIG. 5, the flow of steam is indicated by arrows.

  Between the diaphragm inner ring 310 and the diaphragm outer ring 311, a plurality of stationary blades 312 that rectify the flow of steam are supported in the circumferential direction. These components function as a stationary structure.

  As shown in FIG. 5, a rotor disk 321 is formed on the turbine rotor 320. A plurality of rotor blades 322 are implanted in the rotor disk 321 in the circumferential direction. A shroud 323 is provided at the tip of the moving blade 322. These components function as a rotating structure.

  As shown in FIG. 5, seal fins 330 are provided on the inner peripheral surface of the diaphragm inner ring 310 to suppress the leakage of steam from between the diaphragm inner ring 310 and the turbine rotor 320. Further, seal fins 331 are provided on the outer peripheral surface of the shroud 323, and steam leakage from between the shroud 323 and the diaphragm outer ring 311 is suppressed.

  In the conventional steam turbine described above, the stationary structure and the rotating structure may come into contact with each other due to vibrations generated during operation. That is, the seal fin 330 may contact the turbine rotor 320 or the seal fin 331 may contact the diaphragm outer ring 311.

  Therefore, even when such contact occurs, in order to prevent damage to the constituent members and maintain the steam seal structure, for example, the machinability ( A technique for coating an abradable layer excellent in ease of cutting) has been studied.

JP 2007-170302 A

  As described above, by providing a free-cutting material layer such as an abradable layer, damage to the seal fins 330 and 331 can be suppressed even when the stationary portion and the rotating portion conflict with each other due to vibration during operation of the steam turbine. . However, during operation of the steam turbine, the free-cutting material layer may be eroded by foreign matter or the free-cutting material layer may be thinned over time. Therefore, it is necessary to improve the erosion resistance of the free-cutting material layer.

  The problem to be solved by the present invention is to provide a steam turbine capable of improving the erosion resistance of the free-cutting material layer and suppressing the leakage of steam in the seal portion.

  The steam turbine according to the embodiment includes a rotating structure that rotates about a rotating shaft of a turbine rotor, a stationary structure that is spaced apart from an outer periphery of the rotating structure, an outer peripheral surface of the rotating structure, or the And a sealing member installed in the circumferential direction so as to protrude from the inner peripheral surface of the stationary structure. Further, the steam turbine protrudes from the outer peripheral surface of the rotating structure facing the seal member or the inner peripheral surface of the stationary structure so as not to contact the tip of the seal member, and is installed in a circumferential direction. And a free cutting material layer provided at a portion from the outer peripheral surface of the rotating structure or the inner peripheral surface of the stationary structure projecting from the plate member to the tip of the plate member.

It is a figure showing a meridional section of a steam turbine of an embodiment. It is the figure which showed typically a part of meridional section of one turbine stage in the state which the steam turbine of embodiment is not operating. It is the figure which showed typically a part of meridional section of one turbine stage in the state which the steam turbine of embodiment is operating. It is the figure which showed typically a part of meridional section of the turbine stage in which the part of the free cutting material layer of the seal | sticker part eroded in the state which the steam turbine of embodiment is operating. It is the figure which showed typically a part of meridional section of one turbine stage in the conventional steam turbine.

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

  FIG. 1 is a diagram illustrating a meridional section of a steam turbine 10 according to an embodiment. In the following embodiments, the same components are denoted by the same reference numerals, and redundant descriptions are omitted or simplified.

  As shown in FIG. 1, the steam turbine 10 includes a double-structure casing composed of an inner casing 20 and an outer casing 21 provided outside the inner casing 20. Further, a turbine rotor 23 is provided in the inner casing 20. The turbine rotor 23 is rotatably supported by a rotor bearing 24.

  For example, a rotor disk 25 is formed in the turbine rotor 23, and a plurality of rotor blades 22 are implanted in the rotor disk 25 in the circumferential direction. A moving blade cascade having a plurality of moving blades 22 in the circumferential direction is formed in a plurality of stages in the axial direction of the turbine rotor 23.

  A diaphragm outer ring 26 is installed on the inner periphery of the inner casing 20, and a diaphragm inner ring 27 is installed inside the diaphragm outer ring 26. A plurality of stationary blades 28 are arranged in the circumferential direction between the diaphragm outer ring 26 and the diaphragm inner ring 27 to constitute a stationary blade cascade. The stationary blade cascade is provided in a plurality of stages alternately with the moving blade cascade in the axial direction of the turbine rotor 23. The turbine blade cascade and the rotor blade cascade located on the downstream side thereof constitute one turbine stage. Further, as shown in FIG. 1, a part of the diaphragm outer ring 26 on the downstream side is spaced apart from the outer periphery of the moving blade 22 and extends in the downstream direction.

  An annular steam passage 29 through which main steam flows is formed between the diaphragm outer ring 26 and the diaphragm inner ring 27. A seal portion 30 is provided between the turbine rotor 23 and the inner casing 20 and between the turbine rotor 23 and the outer casing 21 in order to prevent leakage of steam to the outside. As will be described in detail later, a seal portion 40 that prevents leakage of steam is also provided between the turbine rotor 23 and the diaphragm inner ring 27 and between the shroud 31 and the diaphragm outer ring 26 that constitute the tip of the rotor blade 22. Is provided.

  A sleeve tube 32 is provided so as to penetrate the outer casing 21 and the inner casing 20. The sleeve pipe 32 guides the steam from the main steam pipe 33 into the nozzle box 34. The nozzle box 34 is an annular passage disposed between the inner casing 20 and the turbine rotor 23. A first-stage stationary blade 28 (first-stage nozzle) is provided at the outlet of the nozzle box 34. The steam supplied to the nozzle box 34 passes through the first stage stationary blade 28 and is guided to the first stage moving blade 22.

  On the downstream side of the turbine stage of the final stage, there is provided an exhaust passage 35 for exhausting steam that has expanded in each turbine stage.

  In addition, although demonstrated here exemplifying a high pressure turbine, the structure of this Embodiment is applicable to an ultrahigh pressure turbine, an intermediate pressure turbine, a low pressure turbine etc., for example. The configuration of the present embodiment is provided in at least one turbine stage of an ultrahigh pressure turbine, a high pressure turbine, an intermediate pressure turbine, and a low pressure turbine. For example, in an ultrahigh pressure turbine, a high pressure turbine, and an intermediate pressure turbine with high steam pressure, for example, all turbine stages may be configured as in the present embodiment. In the case of a low-pressure turbine, for example, it is preferably provided in an upstream turbine stage where the steam pressure is high.

  Next, the configuration of the seal portion 40 between the turbine rotor 23 and the diaphragm inner ring 27 and between the shroud 31 and the diaphragm outer ring 26 constituting the tip of the moving blade 22 will be described in detail.

  Drawing 2 is a figure showing typically a part of meridional section of one turbine paragraph in the state where steam turbine 10 of an embodiment is not operating. Drawing 3 is a figure showing typically a part of meridional section of one turbine paragraph in the state where steam turbine 10 of an embodiment is operating.

  As shown in FIG. 2, the steam turbine 10 according to the embodiment includes a rotating structure including a turbine rotor 23 and moving blades 22 implanted in a rotor disk 25 of the turbine rotor 23. The steam turbine 10 includes a stationary structure including a stationary blade 28, a diaphragm outer ring 26 that supports the stationary blade 28 from the outer diameter side, and a diaphragm inner ring 27 that supports the stationary blade 28 from the inner diameter side. Yes.

  First, the seal part 40 formed between the turbine rotor 23 and the diaphragm inner ring 27 that is spaced apart from the outer periphery of the turbine rotor 23 will be described.

  As shown in FIG. 2, a seal member 50 protruding outward in the radial direction is formed on the outer peripheral surface 23 a of the turbine rotor 23. The seal member 50 is continuously formed over the circumferential direction of the turbine rotor 23 and has an annular shape. The seal member 50 may be formed integrally with the outer peripheral surface 23a of the turbine rotor 23, or may be formed by welding or the like.

  Here, a so-called High-Low type structure is shown in which the protruding lengths of the adjacent seal members 50 toward the outside in the radial direction are different, but the present invention is not limited to this. For example, it is good also as the protrusion length to the radial direction outer side of the adjacent seal member 50 being the same.

  The seal member 50 is configured by a plate-like member having a predetermined width M1. For example, as shown in FIG. 2, the sealing member 50 may have a fin shape in which the thickness is gradually reduced at the distal end as it goes to the distal end. The seal member 50 is made of the same material as that constituting the turbine rotor 23, for example.

  Here, an example in which the four-stage seal member 50 is provided in the axial direction of the turbine rotor 23 is shown, but the seal member 50 only needs to be formed in at least one stage in the axial direction of the turbine rotor 23.

  On the other hand, a plate-like member 60 that protrudes radially inward (toward the turbine rotor 23) is formed on the inner peripheral surface 27 a of the diaphragm inner ring 27 facing the seal member 50 so as not to contact the tip of the seal member 50. Yes. The plate-like member 60 is continuously formed over the circumferential direction of the diaphragm inner ring 27 and has an annular shape.

  The protruding length of the plate-like member 60 inward in the radial direction is set corresponding to the protruding length of the seal member 50. When the seal member 50 has, for example, a high-low type structure, as shown in FIG. 2, the inner peripheral surface 27a of the diaphragm inner ring 27 is formed to be uneven. Then, when the plate-like member 60 and the seal member 50 are arranged to face each other (when the axial position of the turbine rotor 23 is arranged so as to coincide with each other), the protruding lengths of the two do not contact each other. Is set. Specifically, when the plate member 60 and the seal member 50 are opposed to each other in a state where the steam turbine 10 is not in operation, the clearance between both ends is considered in consideration of, for example, a manufacturing intersection or a thermal elongation amount. And about 0.5 mm to 2.0 mm.

  The plate-like member 60 is fixed by, for example, fitting a part of the plate-like member 60 into a groove 27b formed on the inner peripheral surface 27a in the circumferential direction and caulking the opening of the groove 27b. Caulking is performed, for example, from at least one of the upstream side (left side of the plate-like member 60 in FIG. 2) and the downstream side (right side of the plate-like member 60 in FIG. 2). In addition, in order to strengthen fixation of the plate-shaped member 60, it is preferable that caulking is performed from both the upstream side and the downstream side, for example. In addition, the caulking portions are formed at a plurality of locations, for example, equally in the circumferential direction.

  The plate-like member 60 is configured by a plate-like member having a width M2 that is thinner than the width M1 of the seal member 50. The plate-like member 60 is made of, for example, stainless steel such as SUS304. The plate member 60 preferably has a lower hardness than the material constituting the seal member 50. Since the width M2 of the plate-like member 60 is thinner than the width M1 of the seal member 50, a material having the same degree of hardness as the material constituting the seal member 50 is used as the material constituting the plate-like member 60. You can also

  Here, in the state where the steam turbine 10 is not operating, the position of the tip of the plate member 60 in the turbine rotor axial direction is the same as the position of the tip of the seal member 50 in the turbine rotor axial direction, as shown in FIG. It is off. For example, as shown in FIG. 2, the position of the tip of the plate member 60 in the turbine rotor axial direction is shifted to the upstream side of the position of the corresponding seal member 50 in the turbine rotor axial direction.

  This deviation width is set based on the amount of thermal expansion in the axial direction of the turbine rotor 23 and the turbine rotor 23 of the diaphragm inner ring 27 in a state where the steam turbine 10 is operated. That is, in the state where the steam turbine 10 is operating, the deviation width is the position of the tip of the plate-like member 60 in the turbine rotor axial direction and the tip of the seal member 50 in the turbine rotor axial direction as shown in FIG. Is set to match. Here, the state shown in FIG. 3 is a state in which the steam turbine 10 is operated and is thermally stable, for example, during rated operation.

  Here, the plate-like member 60 is provided in four stages in the axial direction of the turbine rotor 23 corresponding to the number of the seal members 50, but is not limited thereto. For example, the plate-like member 60 shown in FIG. 2 may be composed of only the plate-like member 60 located on the most upstream side. Furthermore, for example, in the plate-like member 60 shown in FIG. 2, the plate-like member 60 may be configured by only the plate-like member 60 positioned on the most upstream side and the most downstream side. That is, as the plate-like member 60, at least the plate-like member 60 located on the most upstream side may be provided.

  A free-cutting material layer 70 formed of a free-cutting material is formed in a portion from the inner peripheral surface 27a of the diaphragm inner ring 27 from which the plate-shaped member 60 protrudes to the tip of the plate-shaped member 60. This free-cutting material layer 70 is made of, for example, an abradable material. The abradable material is not particularly limited, and a known material that is generally used can be used. As the abradable material, for example, a material excellent in machinability including a solid lubricant BN (bentonite) can be used. For example, the composition which consists of a NiCrAl alloy and BN, the composition which consists of a NiCrFeAl alloy and BN, etc. are mentioned. Moreover, as abradable material, you may apply soft metals, such as phosphor bronze and a white, for example.

  The free-cutting material layer 70 is formed, for example, by spraying the above-described material onto the inner peripheral surface 27a of the diaphragm inner ring 27 after the plate-like member 60 is fixed.

  Next, the seal part 40 formed between the moving blade 22 and the diaphragm outer ring 26 disposed on the outer periphery of the moving blade 22 will be described.

  As shown in FIG. 2, a seal member 80 protruding outward in the radial direction is formed on the outer peripheral surface 31 a of the shroud 31 constituting the tip of the moving blade 22. The seal member 80 is continuously formed in the circumferential direction of the shroud 31 and has an annular shape. The seal member 80 may be formed integrally with the outer peripheral surface 31a of the shroud 31, or may be formed by welding or the like.

  Here, a so-called High-Low type structure is shown in which the protruding lengths of the adjacent seal members 80 toward the outside in the radial direction are different, but the present invention is not limited to this. For example, the protruding lengths of the adjacent seal members 80 outward in the radial direction may be the same.

  The seal member 80 is configured by a plate-like member having a predetermined width M3. For example, as shown in FIG. 2, the sealing member 80 may have a fin shape in which the thickness of the sealing member 80 is gradually reduced at the leading end. The seal member 80 is made of, for example, the same material as that constituting the shroud 31.

  Here, an example in which the four-stage seal member 80 is provided in the axial direction of the turbine rotor 23 is shown, but the seal member 80 only needs to be formed in at least one stage in the axial direction of the turbine rotor 23.

  On the other hand, the inner peripheral surface 26 a of the diaphragm outer ring 26 that extends on the outer periphery of the moving blade 22 and faces the seal member 80 is radially inward (toward the turbine rotor 23 side) so as not to contact the tip of the seal member 80. A protruding plate-like member 90 is formed. The plate-like member 90 is continuously formed in the circumferential direction of the diaphragm outer ring 26 and has an annular shape.

  The protruding length of the plate-like member 90 inward in the radial direction is set corresponding to the protruding length of the seal member 80. When the seal member 80 has, for example, a high-low type structure, as shown in FIG. 2, the inner peripheral surface 26a of the diaphragm outer ring 26 is formed to be uneven. When the plate-like member 90 and the seal member 80 are arranged to face each other (when the axial position of the turbine rotor 23 is arranged to coincide with each other), the protruding lengths of the two do not contact each other. Is set. Specifically, when the plate member 90 and the seal member 80 are opposed to each other in a state where the steam turbine 10 is not in operation, the clearance between both ends is considered in consideration of, for example, a manufacturing intersection or a thermal elongation amount. And about 0.5 mm to 2.0 mm.

  The plate-like member 90 is fixed to the inner peripheral surface 26a of the diaphragm outer ring 26 in the same manner as the plate-like member 60 described above. The plate-like member 90 is configured by a plate-like member having a width M4 that is thinner than the width M3 of the seal member 80. The plate-like member 90 is made of, for example, a low alloy steel such as CrMoV steel. The plate member 90 preferably has a lower hardness than the material constituting the seal member 80. Since the width M4 of the plate member 90 is thinner than the width M3 of the seal member 80, a material having the same degree of hardness as the material forming the seal member 80 is used as the material forming the plate member 90. You can also.

  Here, in the state where the steam turbine 10 is not operating, the position of the tip of the plate member 90 in the turbine rotor axial direction is the same as the position of the tip of the seal member 80 in the turbine rotor axial direction, as shown in FIG. It is off. For example, as shown in FIG. 2, the position of the tip of the plate member 90 in the turbine rotor axial direction is shifted to the upstream side of the position of the corresponding seal member 80 in the turbine rotor axial direction.

  This deviation width is set based on the amount of thermal expansion in the axial direction of the turbine rotor 23 of the shroud 31 and the diaphragm outer ring 26 when the steam turbine 10 is operated. That is, in the state where the steam turbine 10 is operating, the deviation width is the position of the tip of the plate member 90 in the turbine rotor axial direction and the tip of the seal member 80 in the turbine rotor axial direction, as shown in FIG. Is set to match.

  Here, the plate-like member 90 is provided in four stages in the axial direction of the turbine rotor 23 corresponding to the number of the seal members 80, but is not limited thereto. For example, the plate-like member 90 shown in FIG. 2 may be composed of only the plate-like member 90 located on the most upstream side. Furthermore, for example, in the plate-like member 90 shown in FIG. 2, the plate-like member 90 may be configured by only the plate-like member 90 positioned on the most upstream side and the most downstream side. That is, the plate-like member 90 only needs to include at least the plate-like member 90 positioned on the most upstream side.

  A free-cutting material layer 100 formed of a free-cutting material is formed in a portion from the inner peripheral surface 26a of the diaphragm outer ring 26 from which the plate-shaped member 90 protrudes to the tip of the plate-shaped member 90. This free-cutting material layer 100 is composed of the same material and the same method as the free-cutting material layer 70 described above.

  Here, the effect | action of the above-mentioned seal part 40 in the steam turbine 10 is demonstrated. The action of the seal portion 40 formed between the turbine rotor 23 and the diaphragm inner ring 27 is the same as the action of the seal portion 40 formed between the rotor blade 22 and the diaphragm outer ring 26. Therefore, here, the operation of the seal portion 40 formed between the moving blade 22 and the diaphragm outer ring 26 will be described.

  FIG. 4 is a diagram schematically showing a part of a meridional section of a turbine stage in which a part of the free cutting material layer 100 of the seal portion 40 is eroded in a state where the steam turbine 10 of the embodiment is operating. It is. In FIG. 4, the flow of steam is indicated by arrows.

  When the operation state shown in FIG. 3 is maintained and the upstream side of the free cutting material layer 100 of the seal portion 40 is eroded, the state shown in FIG. 4 is obtained. That is, a part of the surface of the free cutting material layer 100 on the upstream side of the plate-like member 90 located on the most upstream side is eroded. Even if such erosion occurs, as shown in FIG. 4, since the plate-like member 90 located on the most upstream side exists, the free-cutting material layer 100 on the downstream side is prevented from being eroded. be able to.

  Further, when the steam turbine 10 is in operation, the tip of the plate member 90 and the tip of the seal member 80 face each other (because the axial position of the turbine rotor 23 at each tip coincides), so Even if the cutting material layer 100 is eroded, the leakage of steam can be accurately suppressed.

  In the above-described embodiment, an example is shown in which the stationary member includes the plate-like members 60 and 90 and the free cutting material layers 70 and 100, and the rotating member includes the seal members 50 and 80. It is not limited to the configuration. For example, the stationary structure may include the seal members 50 and 80, and the rotating structure may include the plate-like members 60 and 90 and the free cutting material layers 70 and 100.

  That is, the seal portion 40 formed between the turbine rotor 23 and the diaphragm inner ring 27 includes a plate-like member 60 and a free cutting material layer 70 on the outer peripheral surface 23 a of the turbine rotor 23. A sealing member 50 may be provided on the peripheral surface 27a. Further, in the seal portion 40 formed between the moving blade 22 and the diaphragm outer ring 26, the plate-like member 90 and the free cutting material layer 100 are provided on the outer peripheral surface 31 a of the shroud 31 constituting the tip of the moving blade 22. The sealing member 80 may be provided on the inner peripheral surface 26 a of the diaphragm outer ring 26 that extends to the outer periphery of the moving blade 22 and faces the sealing member 80.

  Even with such a configuration, it is possible to obtain the same effects as the effects in the above-described embodiment.

  According to the embodiment described above, it is possible to improve the erosion resistance of the free-cutting material layer and suppress the leakage of steam in the seal portion.

  Although several embodiments of the present invention have been described, these embodiments are presented by way of example and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the scope of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalents thereof.

  DESCRIPTION OF SYMBOLS 10 ... Steam turbine, 20 ... Inner casing, 21 ... Outer casing, 22 ... Rotor blade, 23 ... Turbine rotor, 23a, 31a ... Outer peripheral surface, 24 ... Rotor bearing, 25 ... Rotor disk, 26 ... Diaphragm outer ring, 26a, 27a ... inner peripheral surface, 27 ... diaphragm inner ring, 27b ... groove, 28 ... stationary blade, 29 ... steam passage, 30, 40 ... seal part, 31 ... shroud, 32 ... sleeve pipe, 33 ... main steam pipe, 34 ... nozzle box 35, exhaust passage, 50, 80 ... seal member, 60, 90 ... plate member, 70, 100 ... free cutting material layer.

Claims (5)

A rotating structure that rotates about the rotation axis of the turbine rotor;
A stationary structure spaced apart from the outer periphery of the rotating structure;
A seal member installed in the circumferential direction so as to protrude from the outer peripheral surface of the rotating structure or the inner peripheral surface of the stationary structure;
A plate-like member installed in the circumferential direction, protruding from the outer peripheral surface of the rotating structure facing the seal member or the inner peripheral surface of the stationary structure so as not to contact the tip of the seal member;
A free-cutting material layer provided on a portion extending from the outer peripheral surface of the rotating structure or the inner peripheral surface of the stationary structure from which the plate-like member protrudes to the tip of the plate-like member. Steam turbine.   The turbine rotor axial position at the tip of the seal member is shifted from the turbine rotor axial position at the tip of the plate-like member in a state where the steam turbine is not operating. The described steam turbine.   The turbine rotor axial position at the tip of the seal member coincides with the turbine rotor axial position at the tip of the plate-like member when the steam turbine is operating. The steam turbine according to 1 or 2.   The steam turbine according to claim 1, wherein a thickness of the plate-like member is thinner than a thickness of the seal member. The rotating structure is a turbine rotor, and a plurality of moving blades implanted in a circumferential direction of the turbine rotor,
The stationary structure is disposed apart from the outer periphery of the turbine rotor, supports a plurality of stationary blades, and a part of the inner ring is spaced apart from the outer periphery of the moving blade and extends in the downstream direction. The steam turbine according to any one of claims 1 to 4, wherein the outer ring is a diaphragm outer ring that supports the stationary blades.

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