Steam seal device of steam turbine and steam turbine

Abstract

The present application provides a gland seal device for a steam turbine and a steam turbine, including a stationary blade assembly. The stationary blade assembly includes stationary blades and a diaphragm located radially outside the stationary blades. Among the inlet steam side end face and the outlet steam side end face of the diaphragm, at least one is provided with a plurality of grooves arranged at intervals in the circumferential direction. This gland seal device can reduce the mixing loss caused by the leakage steam.

Description

Technical Field

[0001] The present invention relates to the technical field of steam turbines, and particularly to a gland sealing device for a steam turbine and a steam turbine. Background Art

[0002] There is a gap between the shroud at the top of the moving blade of the steam turbine and the diaphragm gland at the top of the stationary blade. During the steam flow, inevitably, a part of the steam will leak to the outlet side of the moving blade. When this part of the leaked steam flows back into the passage of the next-stage stationary blade, it must be mixed with the mainstream steam in the passage of the stationary blade. There is a large velocity difference, especially the circumferential velocity difference, when the two are mixed. Therefore, when the leaked steam mixes into the mainstream steam, it will destroy the stable flow field of the mainstream steam, resulting in a large mixing loss. Summary of the Invention

[0003] The purpose of this application is to provide a gland sealing device for a steam turbine and a steam turbine, which can reduce the mixing loss caused by the leaked steam.

[0004] This application provides a gland sealing device for a steam turbine, including a stationary blade assembly. The stationary blade assembly includes stationary blades and a diaphragm located radially outside the stationary blades. At least one of the inlet-side end face and the outlet-side end face of the diaphragm is provided with a plurality of grooves arranged at intervals in the circumferential direction.

[0005] Optionally, the outlet-side end face of the diaphragm is provided with the groove, defined as the first groove; the diaphragm has a first guiding portion on the outlet side, and the first guiding portion is an annular structure surrounding the plurality of first grooves. The first guiding portion is located inside the first groove, and the outer surface of the first guiding portion is a first guiding surface for guiding steam to flow towards the first groove.

[0006] Optionally, there is a first partition wall between adjacent first grooves, and the first guiding portion protrudes axially from the first partition wall.

[0007] Optionally, a shroud is provided radially outside the moving blade assembly of the steam turbine, and the inner diameter of the first guiding portion is smaller than the inner diameter of the shroud.

[0008] Optionally, a second guiding surface is provided on the inlet side of the shroud. Both the first guiding surface and the second guiding surface are annular conical surfaces, and the first guiding surface and the second guiding surface are arranged oppositely.

[0009] Optionally, the inlet-side end face of the diaphragm is provided with the groove, defined as the second groove; the diaphragm has a second guiding portion on the inlet side, and a part of the wall of the second groove is the outer surface of the second guiding portion; the second guiding portion includes a third guiding surface, and the third guiding surface gradually inclines outward in the direction towards the shroud of the moving blade assembly.

[0010] Optionally, a shroud is provided on the radially outer side of the moving blade assembly of the steam turbine, and the outer diameter of the second guiding portion is greater than the outer diameter of the shroud.

[0011] Optionally, a groove, defined as a first groove, is provided on the steam outlet side end face of the diaphragm; the depth of the first groove is less than the depth of the second one.

[0012] Optionally, a shroud is provided on the radially outer side of the moving blade assembly of the steam turbine, and the steam seal device further includes steam seal teeth provided on the diaphragm, and the steam seal teeth face the shroud.

[0013] This application also provides a steam turbine, including the steam seal device described in any one of the above.

[0014] The steam seal device of this application includes a groove provided on the steam inlet side end face or the steam outlet side end face of the diaphragm. When a part of the leaked steam flows into or out of the gap between the diaphragm and the moving blade assembly, due to the provision of the groove, the leaked steam will enter the groove and be blocked by the partition wall between adjacent grooves to prevent circumferential flow, so as to consume the circumferential component velocity of the steam, thereby reducing the circumferential component velocity of this part of the leaked steam, and thus reducing the circumferential creep of the leaked steam. After converging into the main steam flow, it will not generate a circumferential impact on the main steam flow, and the mixing loss of the steam can be reduced. At the same time, since the circumferential creep of this part of the leaked steam is suppressed, it also plays a role in preventing the rotor of the steam turbine from experiencing fluid-induced vibration accordingly. Description of the Drawings

[0015] Figure 1 It is a partial schematic view of the blade assembly of the steam turbine in the embodiment of this application;

[0016] Figure 2 is Figure 1 an enlarged view of the positions of the shroud, the first groove and the second groove in

[0017] Figure 3 is Figure 1 a schematic view from the A-direction perspective in

[0018] Figure 4 is Figure 1 a schematic view from the B-direction perspective in

[0019] Figure 5 is Figure 2 an enlarged view of the position of the first groove in

[0020] Figure 6 is Figure 2 an enlarged view of the position of the second groove in

[0021] Figures 1-6 The reference numerals in the drawings are explained as follows:

[0022] 11 - First - stage stationary blade assembly; 111 - First - stage diaphragm; 112 - First - stage stationary blade;

[0023] 12 - Second - stage stationary blade assembly; 121 - Second - stage diaphragm; 122 - Second - stage stationary blade;

[0024] 1a - Second groove; 1b - Second partition wall; 1c - Second diversion part; 1c1 - Third diversion surface;

[0025] 1d - First groove; 1e - First partition wall; 1f - First diversion part; 1f1 - First diversion surface;

[0026] 1g - Step side wall; 1h - Step surface;

[0027] 2 - Labyrinth teeth;

[0028] 3 - Rotating blade assembly; 31 - Shroud; 311 - Second diversion surface; 312 - Annular protrusion; 32 - Rotating blade;

[0029] a - First gap; b - Second gap; c - Third gap. Detailed implementation manners

[0030] In order to enable those skilled in the art of this technology to better understand the solution of the present invention, the present invention will be further described in detail below with reference to the drawings and specific implementation manners.

[0031] Please refer to Figure 1 、 2 , Figure 1 which is a partial schematic view of the blade assembly of the steam turbine in the embodiment of the present application, with the perspective being an axial cross - section, and only showing the first - stage stationary blade assembly 11, the second - stage stationary blade assembly 12, and the rotating blade assembly 3 located between them, and each blade assembly only shows the part on one side of the central axis of the steam turbine, so as to better illustrate the labyrinth seal device in this embodiment; Figure 2 is Figure 1 an enlarged view of the positions of the shroud 31, the first groove 1d, and the second groove 1a in

[0032] In this embodiment, for two adjacent stationary blade assemblies of the steam turbine, along the direction from steam inlet to steam outlet, that is Figure 1In the direction from right to left, the first-stage stationary blade assembly 11 and the second-stage stationary blade assembly 12 are respectively defined. The first-stage stationary blade assembly 11 is located upstream of the second-stage stationary blade assembly 12. Steam flows from the steam inlet side of the first-stage stationary blade assembly 11 to the steam outlet side of the second-stage stationary blade assembly 12. The flow direction of the main steam is axial flow, and the circumferential component velocity is relatively small. In this embodiment, "outer" and "inner" are also defined. "Outer" means the direction radially away from the central axis of the steam turbine, and "inner" means the direction radially close to the central axis of the steam turbine. At this time, each stationary blade assembly includes a plurality of stationary blades and a diaphragm located radially outside the stationary blade assembly. The diaphragm is annular, and the annular diaphragm is connected to the radial outside of the plurality of stationary blades.

[0033] Figure 1 Among them, the diaphragm of the first-stage stationary blade assembly 11 is the first-stage diaphragm 111, the diaphragm of the second-stage stationary blade assembly 12 is the second-stage diaphragm 121, the stationary blades of the first-stage stationary blade assembly 11 are the first-stage stationary blades 112, and the stationary blades of the second-stage stationary blade assembly 12 are the second-stage stationary blades 122. The axial distance between the first-stage diaphragm 111 and the second-stage diaphragm 121 is less than the axial distance between the first-stage stationary blades 112 and the second-stage stationary blades 122.

[0034] The moving blade assembly 3 includes a plurality of moving blades 32 and a shroud 31 located radially outside the moving blade assembly 3. The shroud 31 is annular, and the annular shroud 31 is connected to the radial outside of the plurality of moving blades 32. The moving blades 32 are located between the first-stage stationary blades 112 and the second-stage stationary blades 122. Specifically, as Figure 1 shown, on both axial sides of each diaphragm are respectively the steam inlet side and the steam outlet side, that is, the steam inlet side and the steam outlet side are axially distributed. The steam outlet side end face of the diaphragm includes an annular step surface 1h (shown in Figure 5 ), and the step surface 1h faces axially towards the diaphragm of the next-stage stationary blade. In this way, the shroud 31 of the moving blade 32 is located between the steam inlet side end face of the second-stage diaphragm 121 and the step surface 1h of the steam outlet side end face of the diaphragm of the first-stage stationary blade assembly 11. The annular step side wall 1g (shown in Figure 5 ) where the diaphragm is in contact with the step surface 1h is arranged towards the central axis of the steam turbine. The steam seal device includes steam seal teeth 2 provided on the step side wall 1g. A plurality of axially distributed annular protrusions 312 are also provided on the outer surface of the shroud 31. Some of the steam seal teeth 2 are located between two adjacent annular protrusions 312, and some of the steam seal teeth 2 and the annular protrusions 312 are radially opposite. The cooperation between the steam seal teeth 2 and the annular protrusions 312 plays a role in steam sealing to prevent steam from leaking between the outside of the shroud 31 and the inside of the diaphragm.

[0035] It can be further understood in combination with Figures 3-4 that Figure 3 is Figure 1 a schematic view from the A-direction perspective in Figure 1Right view; Figure 4 is Figure 1 a schematic view from the B direction in Figure 1 , that is, Figure 3 , 4 shows the entire axial end face of the steam turbine.

[0036] It should be noted that the steam seal device further includes grooves. In this embodiment, among the inlet side end face and the outlet side end face of the diaphragm of the stationary blade assembly, at least one end face is provided with a plurality of grooves arranged at intervals in the circumferential direction, that is, the inner side of the inlet side end face or the outlet side end face close to the shroud 31 is provided with grooves. The notch of the groove corresponds to the inlet direction or is the same as the inlet direction. The groove provided on the outlet side is defined as the first groove 1d, and the groove provided on the inlet side is defined as the second groove 1a. In Figure 1 , the inlet side end face and the outlet side end face of each stage of diaphragm are provided with grooves, that is, each stage of diaphragm is provided with the first groove 1d and the second groove 1a at the same time. The notch of the second groove 1a provided on the inlet side is opposite to the inlet direction, Figure 1 in Figure 1 , the notches of the second grooves 1a of the first stage diaphragm 111 and the second stage diaphragm 121 both face left, and the notches of the first grooves 1d of the two both face the same as the inlet direction,

[0037] As Figure 3 , 4 shown, a plurality of first grooves 1d are distributed in the circumferential direction, and the plurality of first grooves 1d are coaxially arranged with the stationary blade assembly. A plurality of second grooves 1a are also distributed in the circumferential direction, and the plurality of second grooves 1a are also coaxially arranged with the stationary blade assembly. Among them, there is a partition wall between two adjacent grooves in the circumferential direction. The partition wall between two adjacent first grooves 1d is defined as the first partition wall 1e, and the partition wall between two adjacent second grooves 1a is defined as the second partition wall 1b. When processing the grooves on the corresponding diaphragm, the naturally formed partition is the partition wall. The bottom of the first groove 1d and the second groove 1a can both be spherical or a flat bottom structure with a rounded corner to prevent stress concentration during use.

[0038] Reference can continue to be made to Figure 1 , 2 , and understood in combination with 5 and 6. Figure 5 is Figure 2 an enlarged view of the position of the first groove 1d in Figure 6 is Figure 2 an enlarged view of the position of the second groove 1a in

[0039] When steam enters the steam inlet side of the moving blade assembly 3 from the channel of the first-stage stationary blade assembly 11, part of the steam does not continue to flow axially, but enters the first gap a between the steam inlet side of the shroud 31 of the moving blade assembly 3 and the steam outlet side of the first-stage diaphragm 111, that is, the axial gap between the two. There is a second gap b between the radially inner side of the first-stage diaphragm 111 and the radially outer side of the shroud 31, that is, the radial gap between the two. The second gap b is also the position where the steam seal teeth 2 mentioned above are provided. A third gap c is formed between the steam outlet side of the shroud 31 and the steam inlet side of the second-stage diaphragm 121, that is, the axial gap between the shroud 31 and the second-stage diaphragm 121. The leaked steam can flow from the first gap a to the second gap b, as Figure 5 shown, and then flow from the second gap b to the third gap c, and finally flow back into the main steam again, as shown in 6. It should be noted that Figure 1 , 2 , 5, and 6 all show the flow path of the steam in the form of dotted arrows.

[0040] With such a setting, when the steam enters the first-stage stationary blade assembly 11 axially, part of the steam enters from the first gap a and continues to flow towards the second gap b. Since the first groove 1d is provided inside the end face of the steam outlet side of the first-stage diaphragm 111, after the leaked steam enters the steam seal device from the first gap a, it will first flow towards the first groove 1d. And the multiple first grooves 1d are arranged at intervals in the circumferential direction, then the first partition wall 1e between adjacent first grooves 1d will block and prevent the circumferential flow of this part of the steam to consume the circumferential component velocity of the steam, thereby reducing the circumferential component velocity of this part of the leaked steam. In this way, this part of the steam can flow from the second gap b to the third gap c with a relatively large axial velocity and a relatively small circumferential velocity. At this time, this part of the steam will flow into the second groove 1a again. Similar to the principle of the first groove 1d, the second partition wall 1b between adjacent second grooves 1a will continue to consume the circumferential component velocity of the steam, reduce the circumferential creep of the steam, and prevent the circumferential flow. Then, after the steam flowing out from the third gap c flows back into the main steam, it will not cause a circumferential impact on the main steam, thereby reducing the mixing loss of the steam. At the same time, since the circumferential creep of this part of the leaked steam is inhibited, it also plays a role in preventing the rotor of the steam turbine from experiencing fluid-induced vibration accordingly.

[0041] It should be noted that when the circumferential component velocity of the steam is reduced at the position of the first groove 1d and enters the second gap b, since the shroud 31 rotates with the moving blade 32, the steam in the second gap b may still regain the circumferential component velocity. By setting the second groove 1a to consume the circumferential component velocity, the effect of reducing the mixing loss will be more obvious. However, it can be known that setting only the first groove 1d or only the second groove 1a can consume the circumferential component velocity of the leakage steam to a certain extent. Therefore, it is also possible to set only one of the first groove 1d and the second groove 1a. Of course, setting the first groove 1d and the second groove 1a simultaneously is more conducive to reducing the mixing loss of the steam.

[0042] As Figure 1 , 5 shown, in this embodiment, the diaphragm of the stationary blade has a first guiding portion 1f located on the steam outlet side. The first guiding portion 1f is an annular structure surrounding a plurality of first grooves 1d. The first guiding portion 1f is located inside the first grooves 1d. Relative to the position of the first grooves 1d, the first guiding portion 1f is an annular tooth structure extending further in the steam inlet direction. There is a first partition wall 1e between two adjacent first grooves 1d. The first guiding portion 1f protrudes axially from the first partition wall 1e. The first guiding portion 1f includes an outer surface and an inner surface distributed radially. The outer surface of the first guiding portion 1f is the first guiding surface 1f1. The first guiding surface 1f1 is in contact with the wall of the first groove 1d. The inner surface of the first guiding portion 1f is also a part of the inner surface of the diaphragm and is flush with other parts of the inner surface of the diaphragm to ensure the smooth flow of steam in the channel of the stationary blade assembly. The first guiding surface 1f1 of the first guiding portion 1f is an annular conical surface, which is conducive to guiding the leaked steam into a plurality of first grooves 1d, reducing or preventing the steam from directly entering the second gap b without entering the first grooves 1d. In fact, the first guiding portion 1f not only plays a guiding role but also plays an axial and radial sealing role.

[0043] Furthermore, the inner diameter of the first guiding portion 1f in this embodiment can be set to be smaller than the inner diameter of the shroud 31. In this way, when the steam entering from the channel of the first-stage stationary blade assembly 11 enters the channel of the moving blade assembly 3, it will not collide with the steam inlet side end face of the shroud 31 of the moving blade assembly 3, and the leakage of steam to the first gap a can also be reduced.

[0044] In addition, as Figure 5 shown, the steam inlet side end face of the shroud 31 of the moving blade assembly 3 in this embodiment includes a second guiding surface 311. Both the first guiding surface 1f1 and the second guiding surface 311 are annular conical surfaces, and the first guiding surface 1f1 and the second guiding surface 311 are arranged oppositely and can be substantially parallel. In this way, due to the structure of conical surface against conical surface, it can be ensured that the first guiding surface 1f1 and the second guiding surface 311 have a small gap distance h (shown in Figure 2)Under such circumstances, a relatively large axial gap L is obtained. The gap distance h is the distance perpendicular to the first flow guiding surface 1f1 and the second flow guiding surface 311, and the axial gap L is the axial distance between the two flow guiding surfaces. A decrease in the gap distance h is beneficial to improving the steam seal performance, while a relatively large axial gap L is beneficial to ensuring the axial relative movement conditions between the moving blade 32 and the stationary blade. As Figure 2 shown, there is a minimum gap S along the axial direction between the shroud 31 and the diaphragm. This minimum gap S should ensure the differential expansion requirements between the moving blade assembly 3 and the stationary blade assembly. Here, L, h, and S should be combined and designed according to actual requirements to meet the usage needs.

[0045] In this embodiment, the depth of the first groove 1d is not less than 5 mm. The selection of the depth should ensure that the incoming steam can be blocked and separated circumferentially. A depth greater than 5 mm is beneficial for the entry and blocking of steam. For example, it can be set to 6 mm or more; the arc length of the first groove 1d is 45 mm to 55 mm. If the arc length of the first groove 1d is too large, the force for circumferential separation of steam will decrease. If the arc length of the first groove 1d is too small, steam is not easy to enter. 45 mm to 55 mm is a better arc length range. For example, it can be set to 50 mm. As mentioned above, there is a first partition wall 1e between adjacent first grooves 1d. The circumferential thickness of the first partition wall 1e can be 4 mm to 6 mm. For example, it can be set to 5 mm. If the first partition wall 1e is too thin, the separation effect will be poor. If the first partition wall 1e is too thick, the number of the first grooves 1d will be limited, and some steam will not enter the first groove 1d. Setting the thickness of the first partition wall 1e to 4 mm to 6 mm is relatively moderate. Of course, according to the actual size of the stationary blade assembly and the flow parameters of the steam, etc., the above data range can also be adjusted. This embodiment does not limit this.

[0046] Correspondingly, the depth of the second groove 1a can be not less than 8 mm. As mentioned above, when the shroud 31 rotates, the steam will generate a circumferential component velocity. The second groove 1a is an adjustment area before the confluence into the mainstream steam. Then the depth can be set to be greater than the depth of the first groove 1d to further ensure the consumption of the circumferential component velocity of the steam. The depth of the second groove 1a can be set to 10 mm, for example. The arc length of the second groove 1a can be 45 mm to 55 mm. For example, it can be set to 50 mm. There is a second partition wall 1b between adjacent first grooves 1d. The thickness of the second partition wall 1b can be 4 mm to 6 mm. For example, it can be set to 5 mm. Here, the selection of the circumferential thickness of the second partition wall 1b and the circumferential arc length size of the second groove 1a can be understood by referring to the above first groove 1d and will not be elaborated here.

[0047] In this embodiment, the outer diameter of the second groove 1a may be larger than the outer diameter of the shroud 31. When the outer periphery of the shroud 31 has an irregular shape, for example, when an annular protrusion 312 is provided, the outer diameter of the second groove 1a is larger than the maximum outer diameter of the shroud 31, so as to prevent the steam leaking from the second gap b from not flowing accurately into the second groove 1a and causing additional flow losses. The outer diameter of the second groove 1a may be further increased. In the axial projection, the outer diameter of the second groove 1a may be located outside the second gap b, that is, the second groove 1a is set as high as possible, so as to further prevent the steam leaking from the second gap b from blowing towards the steam inlet side end plane of the diaphragm and weakening the effect of preventing circumferential flow.

[0048] In this embodiment, the diaphragm further includes a second guiding portion 1c located on the steam inlet side, as Figure 6 shown, which shows the second guiding portion 1c on the steam inlet side of the second-stage diaphragm 121 of the second-stage stationary blade assembly 12. The second guiding portion 1c is located inside the second groove 1a. The second guiding portion 1c includes an inner surface and an outer surface distributed in the radial direction. The part of the outer surface corresponding to the second groove 1a constitutes the wall of the second groove 1a. The inner surface of the second guiding portion 1c is the third guiding surface 1c1. The third guiding surface 1c1 gradually inclines from the inside to the outside along the direction towards the shroud 31 of the moving blade 32. In this way, it is beneficial to guide the steam in the third gap c to flow relatively smoothly into the channel of the second-stage stationary blade assembly 12, mix into the main steam flow, and reduce the disturbance to the main steam flow. At the same time, the third guiding surface 1c1 can also inhibit the main steam from entering between the shroud 31 and the second-stage diaphragm 121, and make it flow smoothly along the wall surface of the steam passage. The wall surface of the steam passage includes the inner surface of the diaphragm.

[0049] Figure 6 In, the second guiding portion 1c is flush with the second partition wall 1b in the axial direction. Actually, the second guiding portion 1c can also protrude axially from the second partition wall 1b like the first guiding portion 1f. In this way, the second guiding portion 1c also has an annular tooth structure and can play an axial sealing role for the steam, that is, the second guiding portion 1c has the functions of guiding, axial and radial sealing. Of course, it can be determined whether to set the second guiding portion 1c to protrude from the second partition wall 1b according to the axial distance between the steam inlet side end face of the diaphragm and the shroud 31.

[0050] The inclination angle of the third guiding surface 1c1 of the second guiding portion 1c is designed according to the angle of steam flow to prevent the steam flowing out of the channel of the moving blade 32 from hitting the steam inlet side end face of the second-stage diaphragm 121, that is, to prevent hitting the steam inlet side end face of the downstream-stage diaphragm. The third guiding surface 1c1 of the second guiding portion 1c can be smoothly transitioned with the inner surface of the second-stage diaphragm 121 and the outer side wall surface of the second-stage stationary blade 122 to improve the flow efficiency.

[0051] In this embodiment, the positions where the first groove 1d and the partition are connected, as well as the positions where the second groove 1a and the partition are connected, can be set with rounded transitions to reduce stress. The other parts of the steam seal device can retain the sharp edges after processing to consume the kinetic energy of the leaked steam.

[0052] This embodiment also provides a steam turbine, including the steam seal device described in any one of the above, which has the same technical effects as those in the above embodiments and will not be repeated here.

[0053] In this article, specific examples are used to illustrate the principle and implementation manner of the present application. The description of the above embodiments is only used to help understand the method and its core idea of the present application. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present application, several improvements and modifications can be made to the present application, and these improvements and modifications also fall within the protection scope of the claims of the present application.

Claims

1. Steam seal device of steam turbine, characterized in that, It includes a stator vane assembly, and the stator vane assembly includes stator vanes and diaphragms located radially outside the stator vanes; a plurality of first grooves are provided on the steam outlet side end face of the diaphragm at circumferentially spaced intervals; the diaphragm has a first flow guiding portion on the steam outlet side, and the first flow guiding portion is an annular structure surrounding the plurality of first grooves, the first flow guiding portion is located inside the first grooves, and the outer surface of the first flow guiding portion is a first flow guiding surface for guiding steam to flow towards the first grooves; there is a first partition wall between adjacent first grooves, and the first flow guiding portion protrudes axially from the first partition wall; A shroud is provided radially outside the moving blade assembly of the steam turbine, and the inner diameter of the first flow guiding portion is smaller than the inner diameter of the shroud; a second flow guiding surface is provided on the steam inlet side of the shroud, and both the first flow guiding surface and the second flow guiding surface are annular conical surfaces, and the first flow guiding surface and the second flow guiding surface are arranged oppositely; a plurality of second grooves are provided on the steam inlet side end face of the diaphragm at circumferentially spaced intervals; the diaphragm has a second flow guiding portion on the steam inlet side, and a part of the wall of the second groove is the outer surface of the second flow guiding portion; the second flow guiding portion includes a third flow guiding surface, and the third flow guiding surface gradually inclines outwards towards the direction of the shroud of the moving blade assembly.

2. The steam seal device of a steam turbine according to claim 1, characterized in that, The outer diameter of the second flow guiding portion is larger than the outer diameter of the shroud.

3. The steam seal device of a steam turbine according to claim 1, characterized in that, The depth of the first groove is smaller than the depth of the second groove.

4. The gland seal device of the steam turbine according to any one of claims 1-3, characterized in that The steam seal device further includes steam seal teeth provided on the diaphragm, and the steam seal teeth face the shroud.

5. Steam turbine, characterized in that, It includes the steam seal device according to any one of claims 1-4.

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