A compact main steam valve for steam turbine

Abstract

The compact main steam valve of a steam turbine described in the present invention belongs to the technical field of steam turbines, and includes a valve body and a valve seat, a valve sleeve and a valve stem arranged in the valve body. The valve sleeve and the valve seat are arranged in sequence in the valve body from the outside to the inside and enclose a structure with a compression inner cavity. A valve cover is provided at the outer port of the valve body. The valve stem penetrates the valve cover and the valve sleeve and slides back and forth in the compression inner cavity. The valve cover is sleeved on the outside of the valve sleeve, and the opposite surfaces of the valve cover and the valve sleeve are concave and combined to form a sealed chamber; a pressure ring is filled between the inner end surface of the valve cover and the outer end surface of the valve sleeve. After the valve sleeve is subjected to the reverse extrusion force of steam, the sealed chamber can cooperate with the valve cover fixed on the valve body to offset a part of the force, so as to fix the valve sleeve in the valve body; under the action of the pressure ring, the sealing of the sealed chamber can be effectively guaranteed, and the sealing surface structure between the valve cover and the valve sleeve can be simplified, thereby improving the convenience of subsequent maintenance and disassembly.

Description

Technical Field

[0001] The invention belongs to the technical field of steam turbines, in particular to a compact main steam valve for a steam turbine. Background Art

[0002] The main steam valve of the steam turbine is the first valve of the steam turbine and is an on / off valve. Its actuator is connected to the protection system of the steam turbine. In the case of a turbine trip, the pressure of the hydraulic system drops and the main steam valve is closed. Before starting, the main steam valve is opened by the turbine protection system. The supply and cut-off of steam to the steam turbine are achieved by opening and closing the main steam valve. Therefore, the main steam valve operates in a high-temperature and high-pressure steam environment for a long time, and the main steam valve is required to have good sealing performance to prevent the leakage of high-temperature and high-pressure steam, resulting in heat loss and even safety accidents.

[0003] In order to ensure the freedom of movement of the valve stem, a certain gap must be maintained between the valve stem and the sleeve. A large gap will cause serious steam leakage for small and medium-sized steam turbines.

[0004] Most of the existing technologies adopt a mode of arranging the valve and the cylinder separately through the steam inlet pipe and the flange, which increases the pipeline loss and the steam leakage point, is not conducive to rapid assembly and disassembly, and increases the operation and maintenance costs.

[0005] As the valve is continuously opened and closed, the sealing surface of the valve stem will suffer from wear, pitting, surface corrosion and other defects, making it impossible to ensure the sealing effect. As a result, the sliding surface is affected by the high-temperature steam and a large amount of oxide scale is produced, causing the valve stem to become stuck and unable to close normally. In severe cases, an accident may occur and the machine cannot be shut down.

[0006] The valve cover seal generally adopts a flange structure or a gate rod seal with a labyrinth structure. In the flange seal structure, the valve cover and flange are generally thick and heavy, with large consumables, poor flange sealing effect, and large air leakage. The sealing gasket is generally a disposable toothed gasket. The bolts are generally heat-tightened bolts, which requires a matching bolt heating device, which is costly. The damage rate of heat-tightened bolts is also high during overhaul, and the bolts are difficult to disassemble. A certain proportion of bolts need to be replaced each time they are overhauled.

[0007] The gate rod seal of the secret palace structure has two levels of steam leakage, the first level leaks to the deaerator, and the second level leaks to the steam seal cooler. The leaking steam needs to be connected to the deaerator and steam seal cooler with pipes, which makes the system complex and costly, affecting the economic efficiency of the steam turbine. Summary of the invention

[0008] In order to solve the problem that the main steam valve, especially the sealing surface between the valve cover and the valve sleeve, has a complex structure or is inconvenient to maintain, the present invention provides a compact main steam valve for a steam turbine.

[0009] The present invention is achieved through the following technical solutions:

[0010] A compact main steam valve for a steam turbine comprises a valve body and a valve seat, a valve sleeve and a valve stem arranged in the valve body. The valve sleeve and the valve seat are arranged in sequence in the valve body from the outside to the inside and enclose a structure with a compression inner cavity. A valve cover is provided at the outer port of the valve body. The valve stem penetrates the valve cover and the valve sleeve and slides back and forth in the compression inner cavity. The valve cover is sleeved on the outside of the valve sleeve, and the opposing surfaces of the valve cover and the valve sleeve are concave and combined to form a sealed chamber; a pressure ring is filled between the inner end surface of the valve cover and the outer end surface of the valve sleeve.

[0011] After the valve sleeve is subjected to the reverse extrusion force of steam, the sealing chamber can cooperate with the valve cover fixed on the valve body to offset part of the force, thereby fixing the valve sleeve in the valve body; under the action of the pressure ring, the sealing performance of the sealing chamber can be effectively guaranteed, and the sealing surface structure between the valve cover and the valve sleeve can be simplified, thereby improving the convenience of subsequent maintenance and disassembly.

[0012] A further improvement of the present invention is that a shaft shoulder is provided on the outer wall of the valve sleeve, and the valve cover is arranged outside the shaft shoulder of the valve sleeve; the outer wall of the pressure ring fits the inner wall of the valve body, and a sealing ring is provided between the pressure ring and the valve sleeve to fit the inner wall of the valve body, and the cross section of the sealing ring is triangular. The shaft shoulder serves as the inner bottom surface of the sealing chamber, which can increase the effective area of ​​the sealing chamber acting on the valve sleeve; the sealing ring with a triangular cross section cooperates with the valve sleeve, the valve cover and the inner wall of the valve body respectively, and improves the sealing effect by means of the stable structure of the triangle.

[0013] A further improvement of the present invention is that the outer wall of the valve cover near one end of the valve sleeve is provided with a four-segment ring embedded in the inner wall of the valve body, and the inner end face of the four-segment ring fits the outer end face of the pressure ring. When subjected to outward pressure, a large reaction force is generated on the valve sleeve, which seals the valve body; a pre-tightening force is formed on the valve sleeve through the valve cover to cooperate with the use of the four-segment ring to increase the sealing effect on the valve body; the effective area of ​​the four-segment ring acting on the valve sleeve is increased by the pressure ring.

[0014] A further improvement of the present invention is that the inner wall of the passage through which the valve sleeve allows the valve stem to pass is provided with a first guide sleeve and a second guide sleeve that match the valve stem in sequence from the outside to the inside. The first guide sleeve and the second guide sleeve are respectively provided at both ends of the passage through which the valve sleeve allows the valve stem to pass, and the first guide sleeve and the second guide sleeve ensure the safety of the movement stroke of the valve stem in the passage.

[0015] A further improvement of the present invention is that a sealing element matching the valve stem is provided on the valve sleeve between the first guide sleeve and the second guide sleeve, which is used to seal the steam passage along the valve stem and to receive the pressure transmitted inward from the valve sleeve to form a compression seal on the valve stem.

[0016] A further improvement of the present invention is that a gap of 0.21 mm is left between the side wall of the valve stem and the passage of the valve sleeve through which the valve stem is allowed to pass, thereby reducing the amount of air leakage between the valve stem and the valve sleeve.

[0017] A further improvement of the present invention is that the inner end of the valve stem is provided with a valve disc made integrally with the valve stem; the outer end surface of the valve disc is provided with a boss extending toward one side of the valve stem and leaving a gap; a plug-in arranged around the valve stem is provided between the boss and the valve stem. The valve stem and the valve disc are made integrally, which effectively improves the structural strength; the plug-in forms a force strength on the connection between the valve stem and the valve disc.

[0018] A further improvement of the present invention is that a buffer groove is provided at the outer end of the inner wall of the plug-in unit, which can form a steam buffer space when the boss contacts the valve sleeve when the valve stem is withdrawn from the compression cavity, thereby avoiding severe wear caused by direct contact.

[0019] A further improvement of the present invention is that a heat insulation cover matching with the valve cover is provided on the outer end surface of the valve cover, so as to effectively prevent the steam inside the valve body from leaking out through the valve cover.

[0020] It can be seen from the above technical scheme that the beneficial effects of the present invention are: after the valve sleeve is subjected to the reverse extrusion force of steam, the sealing chamber can cooperate with the valve cover fixed on the valve body to offset part of the force, thereby fixing the valve sleeve in the valve body; under the action of the pressure ring, the sealing performance of the sealing chamber can be effectively guaranteed, and the sealing surface structure between the valve cover and the valve sleeve can be simplified, thereby improving the convenience of subsequent maintenance and disassembly. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the technical solution of the present invention, the accompanying drawings required for use in the description will be briefly introduced below. Obviously, the accompanying drawings in the following description are only some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying creative work.

[0022] Figure 1 It is a structural schematic diagram of a specific implementation mode of the present invention.

[0023] In the accompanying drawings: 1. valve body, 2. valve seat, 3. valve sleeve, 4. valve stem, 5. valve disc, 6. valve cover, 7. four-section ring, 8. pressure ring, 9. first guide sleeve, 10. plug-in, 11. heat insulation cover, 12. sealing element, 13. sealing ring, 14. second guide sleeve. DETAILED DESCRIPTION

[0024] In order to make the purpose, features and advantages of the present invention more obvious and easy to understand, the technical solution of the present invention will be clearly and completely described below in conjunction with the drawings in this specific embodiment. Obviously, the embodiments described below are only part of the embodiments of the present invention, not all of them. Based on the embodiments in this patent, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this patent.

[0025] As attached Figure 1 As shown, a compact main steam valve for a steam turbine comprises a valve body 1 and a valve seat 2, a valve sleeve 3 and a valve stem 4 arranged in the valve body 1. The valve sleeve 3 and the valve seat 2 are arranged in sequence in the valve body 1 from the outside to the inside and enclose a structure with a compression inner cavity. The valve cover 6 is arranged at the outer port of the valve body 1. The valve cover 6 is provided at the outer port of the valve body 1 and is sealed and fixed on the valve cover 6 by fastening bolts.

[0026] The outer wall of the valve sleeve 3 is provided with a shaft shoulder, and the valve cover 6 is arranged outside the shaft shoulder of the valve sleeve 3; the valve cover 6 is sleeved on the outside of the valve sleeve 3, and the opposite surfaces of the valve cover 6 and the valve sleeve 3 are concave and combined to form a sealed chamber; a pressing ring 8 is filled between the inner end surface of the valve cover 6 and the outer end surface of the valve sleeve 3. Under the action of the pressing ring 8, the sealing of the sealed chamber can be effectively guaranteed, and the sealing surface structure between the valve cover 6 and the valve sleeve 3 can be simplified, thereby improving the convenience of subsequent maintenance and disassembly. After the valve sleeve 3 is subjected to the reverse extrusion force of steam, the sealed chamber can cooperate with the valve cover 6 fixed on the valve body 1 to offset part of the force, thereby achieving the fixation of the valve sleeve 3 in the valve body 1.

[0027] The outer wall of the pressing ring 8 fits with the inner wall of the valve body 1, and a sealing ring 13 is provided between the pressing ring 8 and the valve sleeve 3 to fit with the inner wall of the valve body 1, and the cross section of the sealing ring 13 is triangular. The shoulder serves as the inner bottom surface of the sealing chamber, which can increase the effective area of ​​the sealing chamber on the valve sleeve 3; the sealing ring 13 with a triangular cross section cooperates with the valve sleeve 3, the valve cover 6 and the inner wall of the valve body 1 respectively, and improves the sealing effect with the help of the stable structure of the triangle. In other words, both the valve sleeve 3 and the valve cover 6 are provided with a space to accommodate the sealing ring 13.

[0028] The outer wall of the valve cover 6 near the end of the valve sleeve 3 is provided with a four-segment ring 7 embedded in the inner wall of the valve body 1, and the inner end surface of the four-segment ring 7 is in contact with the outer end surface of the pressure ring 8. When subjected to outward pressure, a large reaction force is generated to act on the valve sleeve 3, which plays a sealing role on the valve body 1; a pre-tightening force is formed on the valve sleeve 3 through the valve cover 6 to cooperate with the use of the four-segment ring 7 to increase the sealing effect on the valve body 1; the pressure ring 8 increases the effective area of ​​the four-segment ring 7 acting on the valve sleeve 3.

[0029] The four-section ring 7 plays a positioning role. The four sections are specifically a four-in-one ring, which consists of four parts and is designed with a segmented structure, which greatly facilitates the assembly of the valve cover 6 on the valve body 1; when the sealing ring 13 encounters a sealing failure, the steam leaking into the space inside the assembly hole of the valve cover 6 (that is, the hole through which the bolt passes through the valve cover 6) is introduced into the steam seal heater, further reducing the steam pressure borne by the valve cover 6, ensuring the fixing strength of the valve cover 6 on the valve body 1, and improving the safety of the operation of the main steam valve.

[0030] The valve stem 4 penetrates the valve cover 6 and the valve sleeve 3 and reciprocates in the compression inner cavity. The inner end of the valve stem 4 is provided with a valve disc 5 made integrally with the valve stem 4; the outer end surface of the valve disc 5 is provided with a boss extending to one side of the valve stem 4 and leaving a gap; a plug-in 10 arranged around the valve stem 4 is provided between the boss and the valve stem 4. The valve stem 4 and the valve disc 5 are made integrally, which effectively improves the structural strength; the plug-in 10 forms the force strength of the connection between the valve stem 4 and the valve disc 5. The plug-in 10 is a buffer structure with energy absorption.

[0031] The outer end of the inner wall of the plug 10 is provided with a buffer groove, which can form a steam buffer space when the boss contacts the valve sleeve 3 when the valve stem 4 is withdrawn from the compression cavity, thereby avoiding severe wear caused by direct contact.

[0032] The inner wall of the passage through which the valve stem 4 is allowed to pass through the valve sleeve 3 is provided with a first guide sleeve 9 and a second guide sleeve 14 which are matched with the valve stem 4 in sequence from the outside to the inside. The first guide sleeve 9 and the second guide sleeve 14 are respectively arranged at both ends of the passage through which the valve stem 4 is allowed to pass through the valve sleeve 3, and the first guide sleeve 9 and the second guide sleeve 14 ensure the safety of the movement stroke of the valve stem 4 in the passage.

[0033] The valve sleeve 3 between the first guide sleeve 9 and the second guide sleeve 14 is provided with a sealing element 12 matched with the valve stem 4, which is used to seal the steam passage along the valve stem 4 and to bear the pressure transmitted inward by the valve sleeve 3 to form a compression seal on the valve stem 4.

[0034] The first guide sleeve 9 and the second guide sleeve 14 are respectively arranged at the two ends of the passage of the valve sleeve 3 that allows the valve stem 4 to pass through, and the inner side of the passage is provided with a shaft shoulder for accommodating the sealing element 12. The sealing element 12 is arranged on the outer side of the valve stem 4 and close to the inner shoulder of the valve sleeve 3, and is used to seal the steam passage along the valve stem 4 and to bear the pressure transmitted inward from the valve sleeve 3 to form a compression seal on the valve stem 4.

[0035] A gap of 0.21 mm is left between the side wall of the valve stem 4 and the passage of the valve sleeve 3 through which the valve stem 4 passes, thereby reducing the amount of air leakage between the valve stem 4 and the valve sleeve 3.

[0036] The contact surfaces of the valve stem 4, valve disc 5, first guide sleeve 9, sealing element 12, second guide sleeve 14 and plug-in 10 are all provided with hardened surfaces of Stellite alloy to improve wear resistance and tightness and avoid steam leakage caused by sticking, oxidation and corrosion.

[0037] The outer end surface of the valve cover 6 is provided with a heat insulation cover 11 matched with the valve cover 6. The heat insulation cover 11 effectively prevents the steam inside the valve body 1 from leaking out through the valve cover 6.

[0038] The compact main steam valve of a steam turbine described in the present invention can have a sealing chamber that can cooperate with a valve cover fixed on the valve body to offset a part of the force after the valve sleeve is subjected to the reverse extrusion force of steam, thereby fixing the valve sleeve in the valve body; the sealing performance of the sealing chamber can be effectively guaranteed under the action of the pressure ring, and the sealing surface structure between the valve cover and the valve sleeve can be simplified, thereby improving the convenience of subsequent maintenance and disassembly. The sealing ring is compressed by the pressure of steam, and the greater the pressure, the better the sealing effect; the structure of the four-section ring and the valve cover is compact, the sealing effect is good, and the valve cover is easy to fix, and no matching bolt heating device is required, which saves consumables and reduces the occurrence rate of failures.

[0039] The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same and similar parts between the various embodiments can be referenced to each other.

[0040] The terms "upper", "lower", "outer side", "inner side", etc. in the specification and claims of the present invention and the above-mentioned drawings are used to distinguish the relative relationship in position if they exist, and do not need to be qualitative. It should be understood that the numbers used in this way can be interchanged where appropriate, so that the embodiments of the present invention described here can be implemented in an order other than those illustrated or described here. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions.

[0041] The above description of the disclosed embodiments enables one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A compact main steam valve for a steam turbine, comprising a valve body (1), a valve seat (2), a valve sleeve (3) and a valve stem (4) arranged in the valve body (1), wherein the valve sleeve (3) and the valve seat (2) are arranged in sequence in the valve body (1) from the outside to the inside and enclose a structure with a compression inner cavity, a valve cover (6) is provided at the outer end of the valve body (1), and the valve stem (4) penetrates the valve cover (6) and the valve sleeve (3) and reciprocates in the compression inner cavity, characterized in that: The valve cover (6) is sleeved on the outside of the valve sleeve (3), and the opposing surfaces of the valve cover (6) and the valve sleeve (3) are concave and combined to form a sealed chamber; a pressure ring (8) is filled between the inner end surface of the valve cover (6) and the outer end surface of the valve sleeve (3); a shaft shoulder is provided on the outer side wall of the valve sleeve (3), and the valve cover (6) is arranged on the outer side of the shaft shoulder of the valve sleeve (3); the outer side wall of the pressure ring (8) is in contact with the inner wall of the valve body (1), and a sealing ring (13) is provided between the pressure ring (8) and the valve sleeve (3) and is in contact with the inner wall of the valve body (1), and the cross section of the sealing ring (13) is triangular; the outer wall of the valve cover (6) close to one end of the valve sleeve (3) is provided with a four-section ring (7) embedded in the inner wall of the valve body (1), and the inner end surface of the four-section ring (7) is in contact with the outer end surface of the pressure ring (8).

2. A compact main steam valve for steam turbine according to claim 1, characterized in that: A first guide sleeve (9) and a second guide sleeve (14) matching the valve stem (4) are provided in sequence from outside to inside on the inner wall of the passage through which the valve sleeve (3) allows the valve stem (4) to pass.

3. A compact main steam valve for steam turbine according to claim 2, characterized in that: A sealing element (12) matching with the valve stem (4) is provided on the valve sleeve (3) between the first guide sleeve (9) and the second guide sleeve (14).

4. A compact main steam valve for steam turbine according to claim 3, characterized in that: A gap of 0.21 mm is left between the side wall of the valve stem (4) and the passage of the valve sleeve (3) through which the valve stem (4) is allowed to pass.

5. A compact main steam valve for steam turbine according to claim 1, characterized in that: The inner end of the valve stem (4) is provided with a valve disc (5) integrally formed with the valve stem (4); the outer end surface of the valve disc (5) is provided with a boss extending toward one side of the valve stem (4) and leaving a gap; and a plug-in unit (10) arranged around the valve stem (4) is provided between the boss and the valve stem (4).

6. A compact main steam valve for steam turbine according to claim 5, characterized in that: A buffer groove is provided at the outer end of the inner wall of the plug-in unit (10).

7. A compact main steam valve for steam turbine according to claim 1, characterized in that: The outer end surface of the valve cover (6) is provided with a heat insulation cover (11) which matches the valve cover (6).

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