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, which are conducive to the smooth start-up of the steam turbine and ensure sealing and leakage prevention. The gland seal device is installed on the gland body of the steam turbine. The gland seal device includes a plurality of gland seal segments distributed circumferentially. Gland teeth are arranged on the radially inner side of the gland seal segments; the gland seal device further includes a first elastic member, and the first elastic member is arranged radially between the gland body and the gland seal segments to press the gland seal segments in the radially inward direction; the gland seal segments are provided with a first limiting surface for inward radial stop cooperation with the second limiting surface of the gland body; the gland seal device further includes a limiting device, and the limiting device includes a second elastic member and a connecting member. At least part of the connecting member is located on the radially outer side of the gland seal segments, and the connecting member is connected to the gland seal segments. The second elastic member is arranged radially between the connecting member and the gland body to press the connecting member in the radially outward direction.

Description

Technical Field

[0001] This application relates to the technical field of steam power generation, and particularly relates to a gland seal device for a steam turbine and a steam turbine. Background Art

[0002] A steam turbine is provided with a gland seal device to prevent steam inside the steam turbine from leaking axially. The gland seal device is provided with a plurality of gland teeth distributed axially. There is a small gap between the gland teeth and the outer surface of the rotor to achieve the purpose of sealing and preventing leakage.

[0003] During the startup of the rotor of the steam turbine, the speed of the rotor gradually increases from zero and passes through the critical speed. The frequency corresponding to the critical speed corresponds to the natural frequency of the rotor. When the critical speed is reached, based on the resonance principle, the rotor will generate a large vibration amplitude, which will cause the outer surface of the rotor to contact the above-mentioned gland teeth and generate friction. This friction not only causes wear of the gland teeth and enlargement of the gland gap, but also causes the rotor to vibrate more violently, seriously affecting the safe operation of the steam turbine. Summary of the Invention

[0004] The purpose of this application is to provide a gland seal device for a steam turbine and a steam turbine, which is beneficial to the smooth startup of the steam turbine and ensures sealing and preventing leakage.

[0005] To solve the above technical problems, this application provides a gland seal device for a steam turbine. The gland seal device is installed on the gland body of the steam turbine. The gland seal device includes a plurality of gland arc segments distributed circumferentially. Gland teeth are arranged on the radially inner side of the gland arc segments. The gland seal device further includes a first elastic member, and the first elastic member is arranged radially between the gland body and the gland arc segments to press the gland arc segments in the radially inward direction. The gland arc segments are provided with a first limiting surface for axially inward stop cooperation with the second limiting surface of the gland body in the radial direction.

[0006] The gland seal device further includes a limiting device. The limiting device includes a second elastic member and a connecting member. At least part of the connecting member is located on the radially outer side of the gland arc segments, and the connecting member is connected to the gland arc segments. The second elastic member is arranged radially between the connecting member and the gland body to press the connecting member in the radially outward direction.

[0007] In one mode, the limiting device further includes a limiting member. The limiting member has a third limiting surface, and the gland arc segments have a fourth limiting surface. The fourth limiting surface can axially outward stop cooperate with the third limiting surface in the radial direction. When the fourth limiting surface and the third limiting surface stop cooperate, there is a distance between the first limiting surface and the second limiting surface in the radial direction.

[0008] In one way, the second elastic member presses radially between the limiting member and the connecting member, so that the third limiting surface of the limiting member presses against the second limiting surface of the gland body;

[0009] A second groove is provided on the radially outer side of the gland arc section, and the bottom wall of the second groove is the fourth limiting surface, and the fourth limiting surface is closer to the central axis of the gland arc section than the first limiting surface.

[0010] In one way, the gland arc section includes an adjacent installation part and a gland part, the gland part is located radially inside the installation part, gland teeth are arranged on the radially inner side of the gland part, the installation part is used for inserting into the installation groove of the gland body, and a first shoulder is axially extended at one end of the installation part away from the central axis, and one side end face of the first shoulder facing the central axis of the gland arc section is the first limiting surface.

[0011] In one way, there is a first chamber between the radially outer side of the installation part and the gland body, the steam turbine has a second chamber on the steam inlet side of the gland part, and a steam vent groove is arranged on the steam inlet side part of the installation part, and the steam vent groove communicates the first chamber and the second chamber.

[0012] In one way, the steam vent grooves are arranged at both circumferential ends of the installation part, and the steam vent grooves penetrate the end face of the gland arc section facing the circumferential direction.

[0013] In one way, the first limiting surface and the second limiting surface are arc surfaces that can be in surface contact with each other, the third limiting surface is an arc surface that can be in surface contact with the second limiting surface, and the fourth limiting surface is a flat surface.

[0014] In one way, the connecting member is a screw, a screw hole is provided on the radially outer side of the gland arc section, the connecting member is inserted into the screw hole to threadedly connect the connecting member and the gland arc section, and the second elastic member is arranged between the nut of the screw and the gland body.

[0015] In one way, the connecting member is a screw, a screw hole is provided on the radially outer side of the gland arc section, the connecting member is inserted into the screw hole to threadedly connect the connecting member and the gland arc section, and the second elastic member is arranged between the nut of the screw and the gland body; the limiting member is an annular structure, and both the limiting member and the second elastic member are sleeved on the connecting member.

[0016] In one way, the gland teeth include long gland teeth and short gland teeth. The height of the long gland teeth in the radial direction is greater than that of the short gland teeth in the radial direction. Both the long gland teeth and the short gland teeth extend along the circumferential direction of the gland arc section, and the two are arranged alternately in the axial direction of the gland arc section;

[0017] The gland teeth further include inclined gland teeth. The inclined gland teeth are located between adjacent long gland teeth and short gland teeth, and / or the inclined gland teeth are the gland teeth located on the outermost side in the axial direction of the gland part; the height of the inclined gland teeth in the radial direction is not greater than the height of the short gland teeth; on the steam inlet side part of the inclined gland teeth, the steam inlet side part and the circumferential direction of the gland arc section have an included angle, and the included angle is an acute angle.

[0018] In one way, a third elastic member is further included. The third elastic member is arranged axially between the gland body and the steam inlet side part of the gland arc section.

[0019] In one way, in the installation state, there is a first gap in the circumferential direction between adjacent two gland arc sections, and the diameter of the gland ring composed of a plurality of gland arc sections is D1; in the working state, there is a second gap in the circumferential direction between adjacent two gland arc sections, and the diameter of the composed gland ring is D2, and D1 is greater than D2;

[0020] The minimum value of the gap between adjacent two gland arc sections in the circumferential direction is (D1 - D2)·π / N, where N is the number of gland arc sections.

[0021] The present application further provides a steam turbine, including a rotor and a gland body located radially outside the rotor. The gland body is installed with the gland device of the steam turbine described in any one of the above items. The gland body is provided with an installation groove. The installation groove has a notch facing the rotor. One end of the wall part of the installation groove close to the notch extends axially to form a second shoulder, and the end face on the side of the second shoulder away from the central axis of the rotor is the second limiting surface.

[0022] The steam seal device in this application is provided with a first elastic member and a limiting device. The limiting device includes a second elastic member. The first elastic member presses the steam seal arc section inward in the radial direction, and the second elastic member presses the steam seal arc section outward in the radial direction. The elastic force of the first elastic member can be set to be insufficient to overcome the elastic force of the second elastic member during startup, so that the steam seal arc section can be lifted outward in the radial direction to increase the radial clearance between the steam seal teeth and the rotor; in the working state, the elastic force of the first elastic member combined with the steam pressure can overcome the elastic force of the second elastic member and promote the steam seal arc section to approach the rotor, thereby reducing the clearance. It can be seen that the steam seal device in this application can automatically adjust the clearance as needed to balance smooth startup and sealing against leakage, thereby improving the economy and safety of the unit. The steam turbine provided in this application includes a steam seal device and has the same technical effects as the steam seal device. Brief Description of the Drawings

[0023] Figure 1 It is a schematic structural diagram of the steam turbine in the embodiment of this application;

[0024] Figure 2 is Figure 1 an enlarged view of part C in

[0025] Figure 3 is Figure 2 an enlarged view of part D in

[0026] Figure 4 is Figure 2 a sectional view taken along the A-A direction in

[0027] Figure 5 is Figure 4 a schematic diagram of the steam seal device in the installed state in

[0028] Figure 6 is Figure 2 a sectional view taken along the B-B direction in

[0029] Figure 7 is Figure 4 a schematic diagram of the steam seal arc section unfolded in

[0030] The descriptions of the reference numerals in the drawings are as follows:

[0031] 100 - steam seal body; 100a - installation groove; 101 - second shoulder; 1011 - second limiting surface; 1012 - second sealing surface;

[0032] 200 - Steam seal device; 201 - Steam seal ring; 21 - Steam seal arc segment; 211 - Installation part; 2111 - First shoulder; 21111 - First limiting surface; 2112 - Throat neck; 21121 - First sealing surface; 211a - Second groove; 211a1 - Fourth limiting surface; 211b - First groove; 211c - Steam passage groove; 211d - Third groove; 212 - Steam seal part; 212 - Steam seal part; 2131 - Long steam seal teeth; 2132 - Short steam seal teeth; 2133 - Inclined steam seal teeth; 22 - First elastic member; 23 - Limiting device; 231 - Second elastic member; 232 - Connecting member; 2321 - Nut; 233 - Limiting member; 2331 - Third limiting surface; 24 - Third elastic member;

[0033] 300 - Rotor; 301 - Boss; 300a - Rotor groove;

[0034] a - First chamber; b - Second chamber; c - Third chamber. Detailed implementation mode

[0035] In order to enable those skilled in the art to better understand the technical solutions of the present application, the present application will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0036] In the embodiments of the present application, the terms "first", "second", "third", and "fourth" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, the features defined with "first", "second", "third", and "fourth" may explicitly or implicitly include one or more of such features.

[0037] Please refer to Figures 1-3 , Figure 1 is a schematic structural diagram of a steam turbine in the embodiments of the present application, showing the upper half of the steam turbine, and is a view of a radial cross-section of the steam turbine at the steam seal device 200; Figure 2 is Figure 1 an enlarged view of part C in Figure 3 is Figure 2 an enlarged view of part D in

[0038] The steam turbine in this embodiment includes a cylinder block (not shown in the figure) and a rotor 300 located inside the cylinder block. Moving blades are provided on the rotor 300, and stationary blades are fixed on the cylinder block. The space between the cylinder block and the rotor 300 forms a flow path. The stationary blades and the moving blades are located in the flow path. Steam enters the flow path, flows through the stationary blades and the moving blades, and the moving blades rotate under the action of the steam flow, thereby driving the rotor 300 to rotate. To reduce or avoid axial leakage of steam, the steam turbine is also provided with a gland device 200 and a gland body 100. The gland device 200 is installed on the gland body 100. The gland body 100 is an integral or split annular structure. The gland body 100 can be independently provided and fixed to the cylinder block, or the gland body 100 is a part of the cylinder block.

[0039] As Figure 1 shown, the gland device 200 in this embodiment includes a plurality of gland segments 21 distributed circumferentially. Figure 1 Three gland segments 21 in the upper half are shown in the figure. The plurality of gland segments 21 are assembled circumferentially into an annular gland ring 201. Of course, there is a Figure 1 , 2 gap S as shown. The gland ring 201 is not a complete ring. In addition, the circumferential, radial, and axial directions described in this application are all the circumferential, radial, and axial directions of the steam turbine. The gland body 100 is also an annular structure extending circumferentially along the steam turbine. The gland body 100 is located radially inside the cylinder block and radially outside the rotor 300. The central axes corresponding to the gland body 100 and the gland segments 21 are also the central axis of the steam turbine, that is, the gland body 100 and the gland segments 21 are coaxially arranged. Among them, in this application, the direction away from the central axis is defined as outwards, and the direction close to the central axis is defined as inwards.

[0040] As Figure 4 , 5 shown, Figure 4 is Figure 2 the A-A sectional view in the figure. At this time, the gland device 200 is in the working state; Figure 5 is Figure 4 the schematic diagram of the gland device 200 in the installed state in the figure. It is defined that the gland device 200 has an installed state and a working state. The working state is the normal operation state of the gland device 200 after the steam turbine starts, and the installed state is the non-working state.

[0041] Gland teeth are provided on the radially inner side of each gland segment 21, specifically including Figure 4The long gland teeth 2131, short gland teeth 2132, and inclined gland teeth 2133 shown. A plurality of bosses 301 distributed axially are provided on the radially outer side of the rotor 300. The bosses 301 can be arranged around the rotor 300. The gland teeth and the bosses 301 are combined to form a labyrinth structure to prevent steam from flowing axially, so as to achieve the purpose of preventing or reducing steam leakage.

[0042] As Figure 2 shown, the gland device 200 in this embodiment further includes a first elastic member 22. The first elastic member is specifically a spring. The first elastic member 22 is arranged radially between the gland body 100 and the gland arc segment 21 to press the gland arc segment 21 in the radially inward direction, so that the gland arc segment 21 approaches the rotor 300, so as to ensure that the gap between the gland teeth of the gland arc segment 21 and the rotor 300 will not be too large, thereby meeting the requirement of preventing steam leakage. Moreover, the gland arc segment 21 is provided with a first limiting surface 21111. As Figure 4 shown, the first limiting surface 21111 is used for inward axial stop cooperation with the second limiting surface 1011 of the gland body 100 of the steam turbine to limit the first limiting surface 21111 from approaching the rotor 300 further, thereby defining the distance between the gland arc segment 21 and the rotor 300. That is, the first elastic member 22 presses the gland arc segment 21 to approach the rotor 300 to ensure the sealing effect, but the gap between the gland arc segment 21 and the rotor 300 cannot be too small to avoid collision between the gland teeth and the rotor 300. That is to say, the stop cooperation between the first limiting surface 21111 and the second limiting surface 1011 defines the minimum distance between the gland teeth (including short gland teeth 2132, inclined gland teeth 2133, long gland teeth 2131) of the rotor 300 and the gland arc segment 21, Figure 4 and the height of the gap is shown as T1 in

[0043] As Figure 4 shown, the gland arc segment 21 includes an adjacent mounting portion 211 and a gland portion 212. The gland portion 212 is located radially inside the gland body 100. The above-mentioned various gland teeth are arranged on the radially inner side of the gland portion 212. The mounting portion 211 is used to be inserted into the mounting groove 100a of the gland body 100. The mounting portion 211 has an end away from the central axis, that is, the outer end. The outer end of the mounting portion 211 extends axially to form a first shoulder 2111. The two axial sides of the outer end of the mounting portion 211 can extend axially respectively to form two first shoulders 2111 distributed axially, Figure 4Among them, on the axial two sides of the outer end of the installation part 211 are the steam inlet side part and the steam outlet side part respectively. The steam inlet side part extends axially towards the steam inlet side, and the steam outlet side part extends axially towards the steam outlet side. At this time, the axial cross-section of the installation part 211 is similar to a "T" shape, and the axial cross-section of the steam seal arc section 21 is correspondingly similar to an "I" shape. The part of the installation part 211 below the first shoulder 2111 is the throat neck 2112 of the steam seal arc section 21. One end face of the first shoulder 2111 of the installation part 211 facing the central axis of the steam seal arc section 21 is the first limiting surface 21111, that is, the surface on the radially inward side of the first shoulder 2111 is the first limiting surface 21111. In addition, the installation part 211 can be provided with a first groove 211b for installing the above-mentioned first elastic member 22. As Figure 2 shown, one end of the first elastic member 22 is inserted into the first groove 211b, and the other end abuts against the wall of the installation groove 100b of the steam seal body 100 radially.

[0044] Please continue to refer to Figure 4 , the steam seal body 100 is provided with an installation groove 100a. The installation groove 100a extends circumferentially and is annular. The installation groove 100a has a notch facing the rotor 300. One end of the wall of the installation groove 100a close to the notch extends axially to form a second shoulder 101. One end face of the second shoulder 101 away from the central axis of the rotor 300 is the second limiting surface 1011. Similarly, the two axial sides of the end close to the notch can extend axially respectively to form two second shoulders 101 distributed axially to correspond to the first shoulder 2111. In theory, setting one side shoulder is also possible, but having shoulders on both axial sides makes the cooperation more stable. The installation groove 100a and the structure of the above-mentioned installation part 211 are cooperatively arranged. The axial cross-section of the installation groove 100a is also "T" shaped. After assembly, the first shoulder 2111 of the steam seal arc section 21 is located in the "T" shaped horizontal part space of the installation groove 100a, and the throat neck 2112 of the installation part 211 is located in the "T" shaped vertical part of the installation groove 100a, that is, between the second shoulders 101 on the axial two sides. The first shoulder 2111 is located radially outside the second shoulder 101, and the first shoulder 2111 can abut against the second shoulder 101 radially. Both the first shoulder 2111 and the second shoulder 101 are arc-shaped structures, and they can form a stop fit in the radial direction. The second shoulder 101 is arranged on the steam seal body 100 and is a relatively stationary part, and the first shoulder 2111 is a part of the steam seal arc section 21 and is a radially movable part relative to the second shoulder 101.

[0045] It should be noted that the steam seal device 200 in this embodiment further includes a limiting device 23. The limiting device 23 includes a second elastic member 231 and a connecting member 232. At least part of the connecting member 232 is located radially outside the steam seal arc section 21, and the connecting member 232 is connected to the steam seal arc section 21. As Figure 4As described above, the connecting member 232 is specifically a screw. A screw hole 211b is provided at the radially outer end of the mounting portion 211. A part of the screw is inserted into the screw hole 211b to threadedly connect the gland arc segment 21 and the connecting member 232, and the other part of the screw is located radially outside the mounting portion 211. The second elastic member 231 is specifically a spring in this embodiment. The second elastic member 231 is arranged radially between the connecting member 232 and the gland body 100. The second elastic member 231 can be sleeved on a part of the connecting member 232 to serve as a limiting and guiding member for the connecting member 232, and the second elastic member 231 can press against the radially outer end of the connecting member 232 in the radially outward direction. When the connecting member 232 is a screw, the screw has a nut 2321, and the nut 2321 is the radially outer end of the connecting member 232. The second elastic member 231 can abut against the nut 2321. It can be seen that the connecting member 232 can also be a structure other than a screw, such as a pin. A boss is provided on the outer periphery of the pin to abut against the second elastic member 231, which is also acceptable. No specific limitation is made here. The main purpose is to provide a radially outward elastic force by setting the cooperation between the connecting member 232 and the second elastic member 231, so as to indirectly apply a radially outward elastic force away from the rotor 300 to the gland arc segment 21.

[0046] Combined with Figure 1 Understand that the central axis of the steam turbine generally extends horizontally. At this time, the arc openings of some gland arc segments 21 face downward, and the arc openings of some gland arc segments 21 face upward. When the number of gland arc segments 21 is more than two, the arc openings of some gland arc segments 21 will be inclined upward or downward. Taking Figure 1 the gland arc segment 21 with the arc opening facing downward as an example, the forces acting on the gland arc segment 21 include the radially inward force F1 exerted by the first elastic member 22, the radially outward force F2 exerted by the second elastic member 231, and the self-weight G of the gland arc segment 21. Both the gravity G and the elastic force F1 urge the gland arc segment 21 to approach the rotor 300, and the elastic force F2 urges the gland arc segment 21 to move away from the rotor 300.

[0047] In the working state, steam can enter the installation groove 100a of the gland body 100. There is a pressure difference between the radially inner and outer sides of the gland arc segment 21, so that in addition to the gravity G, the elastic force F1, and the elastic force F2, the gland arc segment 21 will also be subjected to the steam pressure F3. The steam pressure F3 also urges the gland arc segment 21 to approach the rotor 300. Under the combined action of these forces, in the working state of the gland arc segment 21, the first limiting surface 21111 of the gland arc segment 21 abuts against the second limiting surface 1011 of the gland body 100, as Figure 4As shown, the steam seal teeth and the rotor 300 have a minimum gap T1, which meets the requirements of sealing and preventing steam leakage. In this embodiment, in the installed state, the elastic force F1 of the first elastic member 22 is set to be insufficient to abut the first limit surface 21111 and the second limit surface 1011 of the steam seal arc segment 21, that is, considering the gravity G factor, F1 and F2 are configured so that in the installed state, there is a spacing h between the first limit surface 21111 and the second limit surface 1011, as shown in FIG. Figure 5 As shown, the first limiting surface 21111 is relatively higher, and the steam seal arc segment 21 is relatively Figure 4 In the working state, the height h is raised in the direction away from the rotor 300, so that the gap between the steam seal teeth and the rotor 300 is expanded from T1 to T2.

[0048] In this way, during the startup phase of the steam turbine, since the steam pressure F3 is relatively small, it is still unable to overcome the elastic force F2 of the second elastic member 231, and the first limit surface 21111 and the second limit surface 1011 still cannot contact each other, so that the distance between the steam seal tooth and the rotor 300 remains expanded. During the startup process, when the rotor 300 passes the critical speed and generates a large amplitude, since the distance between the steam seal arc segment 21 and the rotor 300 is greater than the distance under normal working conditions, the friction caused by the contact between the surface of the rotor 300 and the steam seal tooth can be reduced or avoided, thereby reducing the wear of the steam seal tooth, and also reducing or avoiding more violent vibrations of the rotor 300, which is conducive to the smooth startup of the steam turbine. After the steam turbine is started, as the steam pressure F3 increases, under the action of the steam pressure F3 and the elastic force F1 of the first elastic member 22, the elastic force F2 of the second elastic member 231 can be overcome, and the first limiting surface 21111 of the steam seal arc segment 21 can be abutted against the second limiting surface 1011, eliminating the lifting height h, so as to reduce the gap between the steam seal teeth and the rotor 300 to the minimum gap T1, thereby ensuring the sealing effect and preventing steam leakage.

[0049] As described in the background technology, if the steam seal gap is increased in order to reduce the friction level during startup, more steam leakage will be caused during operation, which will have an adverse effect on the economy of the steam turbine. The steam seal device 200 in this embodiment can automatically adjust the gap as needed to take into account both smooth startup and sealing and leakage prevention, thereby improving the economy and safety of the unit.

[0050] It can be understood that, as described above, the plurality of steam seal arc segments 21 are distributed along the circumferential direction, and the orientations of the steam seal arc segments 21 and the rotor 300 are not the same, some are located above the rotor 300, some are located below the rotor 300, or some of the steam seal arc segments 21 are located above the rotor 300, and some are located on the side of the rotor 300, etc., so that the gravity G of the steam seal arc segment 21 may cause the steam seal arc segment 21 to approach the rotor 300, or may cause the steam seal arc segment 21 to move away from the rotor 300. Figure 1For example, when the arc opening of the steam seal arc segment 21 faces downward, the gravity G forces the steam seal arc segment 21 to move radially inward toward the rotor 300. On the contrary, when the arc opening of the steam seal arc segment 21 faces upward, the gravity G forces the steam seal arc segment 21 to move radially outward away from the rotor 300. When designing F1 and F2, the circumferential position of the corresponding steam seal arc segment 21 needs to be considered to determine the direction of the gravity G. In this way, the elastic force settings of the first elastic member 22 and the second elastic member 231 will be different according to the position of the steam seal arc segment 21.

[0051] For example, if the elastic force F1 of multiple first elastic members 22 is set to be basically the same, when the arc mouth of the steam seal arc segment 21 is facing downward, the gravity G and the elastic force F1 of the first elastic member 22 have the same effect, both of which urge the steam seal arc segment 21 to approach the rotor 300, and the elastic force F2 of the second elastic member 231 can be set to be relatively large. When the arc mouth of the steam seal arc segment 21 is facing upward, the gravity G and the elastic force F1 of the first elastic member 22 have opposite effects, and the gravity G urges the steam seal arc segment 21 to move away from the rotor 300, which is the same as the effect of the second elastic member 231, and the elastic force F2 of the second elastic member 231 can be set to be relatively small.

[0052] In order to facilitate the adjustment of the elastic force of the second elastic member 231, the connecting member 232 in this embodiment is a screw. By adjusting the depth of the screw screwed into the steam seal arc segment 21, the length m of the second elastic member 231 above the screw hole 211b can be adjusted, and the degree of pre-compression of the second elastic member 231 can be adjusted to achieve the purpose of adjusting the elastic force, so that the elastic force of multiple second elastic members 231 distributed along the circumferential direction can be set differently according to their positions. When adjusting the length m, it is necessary to ensure that there is a certain gap between the radial outer end face of the screw and the radial outer wall of the mounting groove 100a of the steam seal body 100. The height n of the gap in the radial direction can be set to be above 3mm to ensure that the steam seal arc segment 21 has sufficient retreat space.

[0053] It can be seen that the connecting member 232 is not limited to being a screw, and the elastic force adjustment can also be adopted in other ways, for example, the second elastic member 231 selects springs with different stiffnesses according to different arrangement positions, or the connecting member 232 is a telescopic adjustable structure, etc. In fact, the second elastic member 231 can also be set to have the same elastic force, and the first elastic member 22 can be set to be adjustable.

[0054] Each steam seal arc segment 21 may be provided with one or more first elastic members 22 and second elastic members 231. The number of first elastic members 22 and second elastic members 231 may be configured according to the length of the steam seal arc segment 21, for example, 2 to 3 first elastic members 22 and second elastic members 231 may be configured so that each elastic member can be evenly loaded. Figure 2As shown, two first elastic members 22 and two second elastic members 231 are provided on a gland segment 21. The two first elastic members 22 are located between the two second elastic members 231. The two first elastic members 22 and the two second elastic members 231 are symmetrically arranged along the radial center line of the gland segment 21. Specifically, in this embodiment, six uniformly arranged gland segments 21 are included. The central angle a4 corresponding to each gland segment 21 is 60°. The included angle a3 between the two first elastic members 22 can be 20°. The included angle a2 between each second elastic member 231 and the radial center of the gland segment 21 is also 20°. That is, the four elastic members provided on each gland segment 21 are evenly distributed in the circumferential direction, achieving the purpose of better uniform load bearing.

[0055] It can be seen that in this embodiment, the second elastic member 231 is provided to apply a radially outward force to the gland segment 21 to lift the gland segment 21. On this premise, the first elastic member 22 can be set to have a smaller stiffness. As long as in the working state, the provided pressing elastic force F1 and the steam pressure F3 together cause the first limiting surface 21111 and the second limiting surface 1011 to abut. It can be seen that for this purpose, the first elastic member 22 does not need to be set to have a large stiffness. In this way, even when the surface of the rotor 300 rubs against the gland teeth, the gland segment 21 can retreat in time to reduce the friction.

[0056] As a more detailed solution, as Figure 4 、 5 shown, the limiting device 23 in this embodiment further includes a limiting member 233. The limiting member 233 is a limiting block in this embodiment. The relative position of the limiting member 233 and the gland body 100 in the radial direction remains unchanged. The limiting member 233 has a third limiting surface 2331. Specifically, the surface of the limiting member 233 facing the rotor 300 is the third limiting surface 2331. The gland segment 21 has a fourth limiting surface 211a1. The fourth limiting surface 211a1 can cooperate with the third limiting surface 2331 to stop outward in the radial direction. When the fourth limiting surface 211a1 and the third limiting surface 2331 are in stop cooperation, there is a distance h between the first limiting surface 21111 and the second limiting surface 1011 in the radial direction, as Figure 4 shown. That is, the fourth limiting surface 211a1 and the third limiting surface 2331 are used to limit the lifting amplitude of the gland segment 21 by the second elastic member 231. When the fourth limiting surface 211a1 of the gland segment 21 abuts against the third limiting surface 2331 of the limiting member 233, the gland segment 21 cannot continue to move radially outward. That is, the abutting cooperation between the fourth limiting surface 211a1 and the third limiting surface 2331 is used to limit the maximum distance T2 between the gland teeth of the gland segment 21 and the rotor 300.

[0057] It is not difficult to understand that the lifting of the gland arc segment 21 depends on the second elastic member 231. By providing the limiting member 233 to limit the gland arc segment 21, the consistency of the distances of multiple gland arc segments 21 relative to the rotor 300 after lifting can be ensured. In this way, when changing from the installation state to the working state, multiple gland arc segments 21 can approach the rotor 300 synchronously. Thus, the operation rhythm of the entire gland device 200 is consistent, which is beneficial to the stable operation of the steam turbine and ensures the reliability of leakage prevention.

[0058] Specifically, the second elastic member 231 is pressed between the limiting member 233 and the connecting member 232. Exemplarily, it is pressed between the limiting member 233 and the nut 2321 of the connecting member 232. In this way, the third limiting surface 2331 of the limiting member 233 can be pressed against the second limiting surface 1011 of the second shoulder 101. With such an arrangement, the second elastic member 231 can abut the limiting member 233 against the gland body 100, so that the limiting member 233 remains stationary relative to the gland body 100 in the radial direction, thereby enabling the limiting member 233 to play a role in radially outwardly stopping the gland arc segment 21. It can be seen that the limiting member 233 can also be kept stationary with the gland body 100 in other ways. For example, it can be integrally formed with the gland body 100 or be limit-connected to the gland body 100. Here, by directly abutting the second elastic member 231 against the gland body 100 and providing support for the second elastic member 231, the structure of the gland body 100 does not need to be modified, nor does it need to set up a connection structure to connect the limiting member 233 and the gland body 100, and the setting is relatively simple.

[0059] In addition, since the third limiting surface 2331 is always pressed against the second limiting surface 1011 of the second shoulder 101 under the action of the second elastic member 231, and in the lifted state, the third limiting surface 2331 and the fourth limiting surface 211a1 also abut. At this time, the fourth limiting surface 211a1 and the second limiting surface 1011 will be in a flush state, as Figure 5 shown. And in the lifted state, it is required that there is a distance between the first limiting surface 21111 and the second limiting surface 1011 in the radial direction, and the first limiting surface 21111 is located radially outside the second limiting surface 1011. Therefore, the first limiting surface 21111 is also located radially outside the fourth limiting surface 211a1. Taking Figure 5 this as a reference, the first limiting surface 21111 needs to be higher than the fourth limiting surface 211a1 by a height difference of h.

[0060] For this reason, as Figure 2As shown, a second groove 211a is provided on the radially outer side of the gland segment 21 in this embodiment. The second groove 211a is specifically provided at the outer end of the mounting portion 211. The second groove 211a can axially penetrate through the mounting portion 211 of the gland segment 21. The bottom wall of the second groove 211a is the fourth limiting surface 211a1. In this way, the fourth limiting surface 211a1 is closer to the central axis of the gland segment 21 than the first limiting surface 21111, that is, lower than the first limiting surface 21111. In Figure 5 In the shown installation state, a part of the limiting member 233 can be embedded into the second groove 211a so that its third limiting surface 2331 abuts against the fourth limiting surface 211a1. It can be seen that in the installation state of the gland segment 21, a part of the third limiting surface 2331 of the limiting member 233 abuts against the second limiting surface 1011, and a part abuts against the fourth limiting surface 211a1. Moreover, after being arranged in this way, a part of the limiting member 23 can be embedded in the second groove 211a, and the position of the limiting member 23 is limited, which is more reliable during operation or assembly. Of course, it is not limited to this way to limit the limiting member 23. For example, the limiting member 23 can also be connected to the second elastic member 231; the limiting member 23 in this embodiment can also be an annular structure, and the limiting member 23 can be sleeved on the connecting member 231.

[0061] It is easy to understand that the height difference h in the radial direction between the first limiting surface 21111 and the fourth limiting surface 211a1 of the gland segment 21, that is, the distance h by which the gland segment 21 is lifted. For example, if this height difference is set to 1 mm, then relative to the working state, the gland segment 21 in the installation state can be lifted 1 mm radially outward. Of course, this height difference can also be other values and can be set according to specific requirements.

[0062] The working process of the gland device 200 in this embodiment is as follows: As the steam parameters increase and the power of the steam turbine increases, the steam pressure difference between the steam inlet side and the steam outlet side of each gland ring 201 gradually becomes larger. Under the combined action of the steam pressure difference (generating steam pressure F3) and the first elastic member 22 of the gland ring 201, the gland ring 201 overcomes the elastic force of the second elastic member 231 (some gland segments 21 also need to overcome the gravity of the gland segment 21, and some gland segments 21 provide assistance), and presses the first limiting surface 21111 of the first shoulder 2111 against the second limiting surface 1011 of the second shoulder 101 of the gland body 100. At this time, the minimum clearance T1 is formed between the gland teeth and the rotor 300, which is approximately 1 mm smaller than the maximum clearance T2 between the gland teeth and the rotor 300 at the start-up stage, reaching the designed minimum value, and steam leakage can be reduced.

[0063] In this embodiment, the first limiting surface 21111 of the gland arc segment 21 and the second limiting surface 1011 of the gland body 100 are arc surfaces capable of abutting against each other in a face-to-face manner. Correspondingly, the third limiting surface 2331 is also an arc surface capable of abutting against the second limiting surface 1011 in a face-to-face manner, so that the second elastic member 231 reliably abuts the limiting member 233 against the second shoulder 101 of the gland body 100. The central axes corresponding to the arc surfaces are all the central axis of the steam turbine. The fourth limiting surface 211a1 can be a flat surface. The fourth limiting surface 211a1 is the bottom wall of the groove structure provided on the mounting portion 211 of the gland arc segment 21. Processing it into a flat surface is beneficial to the processing of the second groove 211a. At this time, the abutment between the third limiting surface 2331 and the fourth limiting surface 211a1 will be a line contact.

[0064] Looking again Figure 6 , Figure 6 is Figure 2 the sectional view taken along line B-B in

[0065] In this embodiment, there is a first chamber a between the radial outer side of the mounting portion 211 of the gland arc segment 21 and the gland body 100, which is equivalent to the back pressure chamber of the gland arc segment 21. The steam turbine has a second chamber b on the steam inlet side of the gland portion 212 and a third chamber c on the steam outlet side of the gland portion 212. Figure 6 In , for the steam to pass through the gland device 200, it needs to enter from the left side of the gland portion 212. Then, the second chamber b is located on the left side of the gland portion 212, and the right side of the gland portion 212 is the third chamber c. A steam passage groove 211c is provided on the steam inlet side portion of the mounting portion 211. The steam inlet side portion is the side portion of the mounting portion 211 close to the steam inlet side. The steam passage groove 211c communicates the first chamber a and the second chamber b, so that the steam can be better introduced into the first chamber a. The steam passage groove 211c is provided on the mounting portion 211, which is also easy to process. Figure 6 shows that part of the steam passage groove 211c is located in the throat 2112 and part is located on the first shoulder 2111. The maximum depth of the steam passage groove 211c is, for example, 3 - 4 mm. Combining with Figure 2 it can be understood that steam passage grooves 211c are provided at both circumferential ends of each gland arc segment 21, and the steam passage grooves 211c penetrate the end faces of the gland arc segment 21 facing the circumferential direction. In this way, the two mutually adjacent steam passage grooves 211c of two adjacent gland arc segments 21 combined together can be more conducive to the steam entering the mounting groove 100a of the gland body 100.

[0066] The pressure of the second chamber b can be defined as P1. Since the first chamber a communicates with the second chamber b, the pressure of the second chamber b is also P1. P1 is the inlet steam pressure, and the steam pressure between the gland teeth and the rotor 300 is P2. Due to the blocking of the gland teeth, when the steam flows along the gap between the gland teeth and the rotor 300, the pressure P2 will gradually decrease. The steam pressure in the third chamber c on the outlet side is P3, and the value of P3 is the lowest. In this way, there is a large pressure difference between the steam pressure P1 in the first chamber a and the steam pressure P2 radially inside the gland arc segment 21, so that the steam pressure F3 generated under the action of the pressure difference can apply a pressure to the gland arc segment 21 to approach the rotor 300, prompting the first limiting surface 21111 of the gland arc segment 21 to abut against the second limiting surface 1011 of the gland body 100.

[0067] Reference can be further made to Figure 4 and in combination with Figure 7 for understanding. Figure 7 is Figure 4 a schematic diagram of the gland arc segment 21 unfolded in [reference document]. The gland arc segment 21 is arc-shaped. Figure 7 It shows the unfolded plane, which can also be understood as Figure 7 the projection plane of the gland arc segment 21 projected along the radial center line direction.

[0068] As described above, the gland teeth in this embodiment include long gland teeth 2131 and short gland teeth 2132 that are alternately arranged in the axial direction of the gland arc segment 21. In the axial section of the gland arc segment 21, multiple gland teeth are in a comb shape. Both the long gland teeth 2131 and the short gland teeth 2132 extend along the circumferential direction of the gland arc segment 21, that is, both the long gland teeth 2131 and the short gland teeth 2132 are arc-shaped tooth structures. The radial height of the long gland teeth 2131 of the gland arc segment 21 is greater than the radial height of the short gland teeth 2132. As shown in Figures 4-6 , in the radial direction, the long gland teeth 2131 correspond to the positions between two adjacent bosses 301 on the surface of the rotor 300. The long gland teeth 2131 extend into the rotor groove 300a formed between the two bosses 301 and have a first spacing from the bottom wall of the rotor groove 300a. In this embodiment, the variation range of this first spacing is T1~T2. The short gland teeth 2132 correspond to one boss 301 and have a second spacing from the corresponding boss 301. The first spacing and the second spacing are equal, and the second spacing also varies between T1~T2. By setting the spacing, it can avoid contact and friction between the gland teeth and the rotor 300 and can form a labyrinth-type leakage prevention structure. The axial spacing d between the long gland teeth 2131 and the short gland teeth 2132 can be determined according to the axial expansion difference between the gland teeth and the rotor 300 to avoid interference between the long gland teeth 2131 and the bosses 301 after expansion.

[0069] It should be noted that the gland teeth in this embodiment further include inclined gland teeth 2133. The inclined gland teeth 2133 are located between adjacent long gland teeth 2131 and short gland teeth 2132. Both ends of the inclined gland teeth 2133 are connected to the long gland teeth 2131 and the short gland teeth 2132. A slot can be provided on the radially inner surface of the gland portion 212 of the gland arc segment 21. The long gland teeth 2131, the inclined gland teeth 2133, and the short gland teeth 2132 can all be inserted into the corresponding slots for inlay fixation. Of course, when the process permits, they can also be integrally machined on the gland portion 212. The height of the inclined gland teeth 2133 in the radial direction is not greater than the height of the short gland teeth 2132, so as to avoid interference with the boss 301 of the rotor 300, and thus will not affect the axial expansion between the gland teeth and the rotor 300.

[0070] In addition, in addition to being arranged between the long gland teeth 2131 and the short gland teeth 2132, the inclined gland teeth 2133 are also arranged on the radially inner side of the gland portion 212 near the steam inlet side and the steam outlet side. It is defined that there are edge gland teeth on both axial edges of the radially inner side of the gland portion 212. Figure 7 The leftmost long gland tooth or short gland tooth is the edge gland tooth, and the rightmost long gland tooth or short gland tooth is the edge gland tooth. The inclined gland teeth 2133 are located between the edge of the radially inner side of the gland portion 212 and the edge gland teeth, that is, the outermost gland teeth arranged along the axial direction of the gland portion 212 are the inclined gland teeth 2313.

[0071] In addition, the inclined gland teeth 2133 have an inlet side portion, that is, the side portion near the steam inlet side. The inclined gland teeth 2133 are located between a pair of long gland teeth 2131 and short gland teeth 2132. The long gland teeth 2131 are located on the steam inlet side of the inclined gland teeth 2133, or the short gland teeth 2132 are located on the steam inlet side of the inclined gland teeth 2133. At this time, the included angle a1 between the inlet side portion of the inclined gland teeth 2133 and the long gland teeth 2131 or short gland teeth 2132 located on the steam inlet side of the inclined gland teeth 2133 is an acute angle. For the outermost inclined gland teeth 2313, the included angle a1 between the inlet side portion of the inclined gland teeth 2313 and the edge of the gland portion 212 is an acute angle. The edge of the gland portion 212 and the long gland teeth 2311 or short gland teeth 2312 all extend circumferentially, so the above-mentioned included angle is also the included angle a1 between the inclined gland teeth 2313 and the circumferential direction.

[0072] In this way, the gland teeth of the gland arc segment 21 in this embodiment include three types of teeth. The gland teeth are distributed in a net shape on the radially outer side of the surface of the rotor 300, which can prevent the steam between the long gland teeth 2131 and the short gland teeth 2132 from flowing circumferentially under the action of the circumferential uneven pressure difference, and at the same time, can also limit the circumferential flow of the steam driven by the surface of the high-speed rotating rotor 300, thereby suppressing the self-excited vibration of the rotor 300.

[0073] The inclination direction of the inclined steam seal teeth 2133 is related to the rotation direction of the rotor 300 and the steam flow direction. Based on the principle that it is not conducive to the steam flowing through, the inlet side of the above-defined inclined steam seal teeth 2133 and the long steam seal teeth 2131 or short steam seal teeth 2132 or the edge of the steam seal part 212 on the inlet side are arranged at an acute angle. Then, the inclined steam seal teeth 2133 are arranged facing the steam. The inlet side of the inclined steam seal teeth 2133 can guide the leaked steam to the inlet side, further reducing the steam leakage. Arranging the inclined steam seal teeth 2313 on the outermost side of the steam seal part 212 along the axial direction can also better utilize the flow resistance and drainage functions of the inclined steam seal teeth 2133.

[0074] As Figure 7 shown, the inclined steam seal teeth 2133 are evenly embedded in the radial inner side of the steam seal arc section 21. The included angle a1 between the inclined steam seal teeth 2133 and the edge of the long steam seal teeth 2131 or short steam seal teeth 2132 or the steam seal part 212 is related to the spacing d between the long steam seal teeth 2131 and the short steam seal teeth 2132. The larger the spacing d, the larger the variation range of the included angle a1, and the value of a1 can vary within the range of 15° to 45°; the smaller the spacing d, the smaller the variation range of the included angle a1, and the value of a1 is about 15° to 20°. It can be understood that at the same spacing d, the smaller the included angle a1, the longer the length of the inclined steam seal teeth 2133. This angle range can, on the one hand, ensure the obstruction of the circumferential flow of the leaked steam and the guidance to the inlet side, and on the other hand, this angle design is beneficial to increasing the embedding length of the inclined steam seal teeth 2133 between two adjacent and parallel long steam seal teeth 2131 and short steam seal teeth 2132 and the steam seal arc section 21, which is beneficial to preventing the inclined steam seal teeth 2133 from falling off. The inclined steam seal teeth 2133 are parallel to each other, and the distance t between them can be set between 10 mm and 20 mm.

[0075] Figure 7 In, multiple inclined steam seal teeth 2313 are arranged along the same extension line to form a group of inclined teeth. Figure 7 shows multiple groups of inclined teeth distributed along the axial direction. Each group of inclined teeth is equivalent to being divided by the long steam seal teeth 2131 and the short steam seal teeth 2132. Arranging the inclined steam seal teeth 2313 in this way has a better drainage effect on the incoming steam to the inlet side.

[0076] As Figure 2 、 6 shown, the steam seal device 200 in this embodiment further includes a third elastic member 24. Specifically, the third elastic member 24 can also be Figure 6For the spring shown in , each elastic member in the present application may also be an elastic structure other than a spring, such as an elastic tube. The third elastic member 24 is axially disposed between the steam seal body 100 and the steam inlet side of the steam seal arc section 21 to push the steam seal arc section 21 towards the steam outlet side. One or two third elastic members 24 may be provided for each steam seal arc section 21, or there may be multiple ones. More than one third elastic member 24 may be circumferentially evenly distributed. A third groove 211d may be machined on the steam inlet side of the steam seal arc section 21. One end of the third elastic member 24 may be inserted into the third groove 211d, and the other end of the third elastic member 24 may abut against the wall of the mounting groove 100a of the steam seal body 100.

[0077] As Figure 6 shown, the part of the mounting portion 211 of the steam seal arc section 21 below the first shoulder 2111 is the throat 2112 of the mounting portion 211. A first sealing surface 21121 is provided on the steam outlet side of the throat 2112. Under the action of the third elastic member 24, the first sealing surface 21121 of the steam seal arc section 21 presses against the second sealing surface 1012 of the steam seal body 100. The second sealing surface 1012 of the steam seal body 100 is part of the wall of its mounting groove 100a. In this way, it is beneficial to prevent the steam flowing into the first chamber a from flowing towards the steam outlet side and leaking under any operating conditions. As described above, the steam seal arc section 21 is provided with a steam passage groove 211c on its steam inlet side, and in order to form the first sealing surface 21121 on its steam outlet side, the steam passage groove 211c is not machined.

[0078] The limiting device 23, the first elastic member 22, the third elastic member 24 and the steam seal arc section 21 in this embodiment are assembled, and then can be slid into the steam seal body 200 circumferentially. After sliding in, the second elastic member 231 is compressed and abuts the limiting member 23 against the second limiting surface 1011, and the third limiting surface 2331 and the fourth limiting surface 211a1 abut. The second elastic member 22 and the third elastic member 24 are compressed and correspondingly abut against the steam seal body 100.

[0079] In the present embodiment, the multiple steam seal arc sections 21 of the steam seal device 200 are radially lifted outwards in the installed state, and correspondingly, the diameter of the formed steam seal ring 201 is larger. In the working state, the multiple steam seal arc sections 21 radially contract inwards, and correspondingly, the diameter of the formed steam seal ring 201 is smaller. In order to enable the multiple steam seal arc sections 21 to radially contract inwards in the working state, a first gap needs to be reserved circumferentially between adjacent two steam seal arc sections 21 in the installed state. At this time, the diameter of the steam seal ring 201 is D1. In the working state, there is a second gap circumferentially between adjacent two steam seal arc sections 21. The second gap is greater than or equal to zero, and the first gap is greater than the second gap. At this time, the diameter of the steam seal ring 201 is D2. Obviously, D1 is greater than D2.

[0080] On this basis, the minimum value of the first gap between two adjacent gland arc segments 21 in the circumferential direction is set to (D1 - D2)·π / N, where N is the number of gland arc segments 21. (D1 - D2)·π is the change in the circumference of the gland ring 201 in two states, that is, the total change in the gap S during the contraction of the gland ring 201. Since the number of gland arc segments 21 is N, the number of gaps between the gland arc segments 21 is also N, and thus the minimum value of the gap S can be obtained. As long as it is not less than this minimum value, the radial inward contraction of the gland arc segments 21 can be satisfied.

[0081] As Figure 2 shown,

[0082] The above is only the preferred embodiment of the present application. It should be noted that for those of ordinary skill in the art of this technology, without departing from the principle of the present application, several improvements and refinements can be made, and these improvements and refinements should also be regarded as the protection scope of the present application.

Claims

1. A steam seal device for a steam turbine, installed on a steam seal body of a steam turbine, characterized in that: The steam seal device comprises a plurality of steam seal arc segments distributed along the circumferential direction, and steam seal teeth are arranged on the radial inner side of the steam seal arc segments; the steam seal device further comprises a first elastic member, which is arranged radially between the steam seal body and the steam seal arc segment to press the steam seal arc segment in the radial inward direction; the steam seal arc segment is provided with a first limiting surface, which is used to cooperate with the second limiting surface of the steam seal body in the radial inward direction; The steam seal device also includes a limiting device, the limiting device includes a second elastic member and a connecting member, at least a portion of the connecting member is located radially outside the steam seal arc segment, and the connecting member is connected to the steam seal arc segment, and the second elastic member is radially arranged between the connecting member and the steam seal body to press the connecting member in a radially outward direction; The steam seal arc segment comprises a mounting portion and a steam seal portion connected to each other, the steam seal portion is located radially inwardly of the mounting portion, the steam seal teeth are arranged radially inwardly of the steam seal portion, the mounting portion is used to be inserted into the mounting groove of the steam seal body, one end of the mounting portion away from the central axis of the steam seal arc segment extends axially to form a first boss, and the end surface of the first boss facing the central axis of the steam seal arc segment is the first limiting surface; the portion of the mounting portion below the first boss is a throat; A first chamber is provided between the radial outer side of the mounting portion and the steam seal body, the steam turbine has a second chamber located on the steam inlet side of the steam seal portion, a steam passage groove is provided on the steam inlet side of the mounting portion, the steam passage groove connects the first chamber and the second chamber; part of the steam passage groove is located on the throat of the mounting portion, and part of the steam passage groove is located on the first boss; The steam grooves are arranged at both ends of the mounting portion along the circumferential direction, and the steam grooves penetrate the end surface of the steam seal arc segment facing the circumferential direction. The two steam grooves close to each other of two adjacent steam seal arc segments are combined together to facilitate steam to enter the mounting groove of the steam seal body.

2. The steam seal device of the steam turbine according to claim 1, characterized in that: The limiting device also includes a limiting member, the limiting member has a third limiting surface, the steam seal arc segment has a fourth limiting surface, the fourth limiting surface can cooperate with the third limiting surface to stop radially outward, when the fourth limiting surface and the third limiting surface stop cooperate, the first limiting surface and the second limiting surface have a radial spacing.

3. The steam seal device of the steam turbine according to claim 2, characterized in that: The second elastic member is pressed radially between the limiting member and the connecting member, so that the third limiting surface of the limiting member is pressed against the second limiting surface of the steam seal body; A second groove is arranged on the radial outer side of the steam seal arc segment, and the bottom wall of the second groove is the fourth limiting surface. The fourth limiting surface is closer to the central axis of the steam seal arc segment than the first limiting surface.

4. The steam seal device of the steam turbine according to claim 2, characterized in that: The first limiting surface and the second limiting surface are arcuate surfaces that can abut against each other, the third limiting surface is an arcuate surface that can abut against the second limiting surface, and the fourth limiting surface is a straight surface.

5. The steam seal device of a steam turbine according to any one of claims 1 to 4, characterized in that: The connecting member is a screw, and a screw hole is arranged on the radial outer side of the steam seal arc segment. The connecting member is inserted into the screw hole to threadably connect the connecting member and the steam seal arc segment. The second elastic member is arranged between the nut of the screw and the steam seal body.

6. The steam seal device of a steam turbine according to any one of claims 2 to 4, characterized in that: The connecting member is a screw, and a screw hole is provided on the radial outer side of the steam seal arc segment. The connecting member is inserted into the screw hole to threadably connect the connecting member and the steam seal arc segment. The second elastic member is provided between the nut of the screw and the steam seal body. The limiting member is an annular structure, and the limiting member and the second elastic member are both covered with the connecting member.

7. The steam seal device of a steam turbine according to any one of claims 1 to 4, characterized in that: The steam seal teeth include long steam seal teeth and short steam seal teeth, the height of the long steam seal teeth in the radial direction is greater than the height of the short steam seal teeth in the radial direction, the long steam seal teeth and the short steam seal teeth both extend along the circumference of the steam seal arc segment, and the two are alternately arranged in the axial direction of the steam seal arc segment; The steam seal teeth also include oblique steam seal teeth, which are located between the adjacent long steam seal teeth and the short steam seal teeth, and / or the oblique steam seal teeth are the steam seal teeth located at the outermost side of the steam seal part in the axial direction; the radial height of the oblique steam seal teeth is not greater than the height of the short steam seal teeth; the steam inlet side of the oblique steam seal teeth and the circumference of the steam seal arc segment have an angle, and the angle is an acute angle.

8. The steam seal device of a steam turbine according to any one of claims 1 to 4, characterized in that: It also includes a third elastic member, which is axially arranged between the steam seal body and the steam inlet side of the steam seal arc segment.

9. The steam seal device of a steam turbine according to any one of claims 1 to 4, characterized in that: In the installed state, there is a first gap between two adjacent steam seal arc segments in the circumferential direction, and the diameter of the steam seal ring composed of the plurality of steam seal arc segments is D1; ​​in the working state, there is a second gap between two adjacent steam seal arc segments in the circumferential direction, and the diameter of the steam seal ring composed is D2, and D1 is greater than D2; The minimum value of the gap between two adjacent steam seal arc segments in the circumferential direction is (D1-D2)·π / N, wherein N is the number of the steam seal arc segments.

10. A steam turbine, characterized in that: It includes a rotor and a steam seal body located radially outside the rotor, the steam seal body is installed with the steam seal device of the steam turbine according to any one of claims 1 to 9, the steam seal body is provided with a mounting groove, the mounting groove has a notch facing the rotor, the wall of the mounting groove extends axially at one end close to the notch to form a second boss, and the end surface of the second boss on the side away from the central axis of the rotor is the second limiting surface.

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