Quick-closing valve for steam turbine

Abstract

The utility model provides a steam turbine quick-closing valve which comprises a valve casing and a valve cover assembly which are sequentially connected, a valve seat is arranged in the valve casing, the valve seat is in clearance fit with the valve casing, the valve seat is fixed on the valve casing through a clamping ring, a valve disc is arranged in the valve cover assembly, the valve disc is matched and connected with the valve seat in an abutting mode, and the valve cover assembly is fixed on the valve casing. Wear-resistant layers are arranged on two contact surfaces of the valve disc and the valve seat. The defects that in the prior art, a valve seat is in interference fit with a valve shell, the valve seat is fixed through spot welding after being installed on the valve shell, and disassembly and assembly are inconvenient can be overcome. And the contact surface of the valve disc and the valve seat is easy to wear, so that the contact of the sealing surface is not uniform, and the valve cannot be completely closed.

Description

Technical Field

[0001] The utility model relates to the technical field of steam turbines, in particular to a quick-closing valve for steam turbines. Background Art

[0002] Steam turbines are the main equipment of petrochemical, metallurgical enterprises, and thermal power plants. The steam intake and exhaust of steam turbines are realized through the coordinated actions of various valves, and the speed of steam turbines is controlled. The quick-closing valve is also called the main steam valve. It is the main closing mechanism between the main steam pipeline and the steam turbine. In an emergency, it can immediately cut off the steam intake of the steam turbine and quickly shut down the unit. The existing quick-closing valve mainly includes a valve housing, a valve seat, a butterfly valve, a valve cover, a seat frame, an oil cylinder, a sealing assembly, a piston assembly, and a valve stem. The valve housing, the valve cover, and the oil cylinder are connected in sequence. The valve seat is installed in the valve housing, and the piston assembly is installed in the oil cylinder. The valve stem passes through the valve cover. One end of the valve stem is connected to the butterfly valve, and the other end of the valve stem is connected to the piston assembly. The valve stem is driven to move left and right by the oil cylinder to control the opening and closing of the quick-closing valve. The valve seat and the valve housing are interference fit. After the valve seat is installed in the valve housing, it is fixed by spot welding, which has the disadvantage of inconvenient disassembly and assembly. In addition, the contact surface between the valve disc and the valve seat is easy to wear, resulting in uneven contact of the sealing surface, and the valve cannot be completely closed. Utility Model Content

[0003] Therefore, the utility model provides a quick-closing valve for a steam turbine, which can overcome the defects of the prior art that the valve seat and the valve housing are in interference fit, the valve seat is fixed to the valve housing by spot welding, and it is inconvenient to disassemble and assemble. In addition, the contact surface between the valve disc and the valve seat is easily worn, resulting in uneven contact of the sealing surface and the valve cannot be completely closed.

[0004] In order to solve the above problems, the utility model provides a quick-closing valve for a steam turbine, comprising a valve housing and a valve cover assembly connected in sequence, wherein a valve seat is provided in the valve housing, the valve seat and the valve housing are clearance-fitted, and the valve seat is fixed to the valve housing by a retaining ring, a valve disc is provided in the valve cover assembly, the valve disc is fitted and abutted against the valve seat, and two contact surfaces of the valve disc and the valve seat are provided with a wear-resistant layer.

[0005] In some embodiments, the quick-closing valve for a steam turbine further includes a pre-start valve seat, the pre-start valve seat is interference fit with the valve disc, and the pre-start valve seat and the outer end surface of the valve disc are fastened by a saddle screw.

[0006] In some embodiments, the two contact surfaces between the pre-start valve seat and the valve stem head are provided with the wear-resistant layer, and the material of the wear-resistant layer is Stellite.

[0007] In some embodiments, the quick-closing valve for a steam turbine further comprises a valve stem, and a steam groove is provided at the bottom of the piston boss of the valve stem head, and the steam groove can introduce the steam between the valve disc and the valve cover assembly into the steam chamber of the steam turbine.

[0008] In some embodiments, the valve stem includes a first valve stem and a second valve stem, one end of the first valve stem is connected to the valve disc, the other end of the first valve stem is connected to one end of the second valve stem via a coupling assembly, and the other end of the second valve stem extends into the cylinder and is connected to the cylinder piston assembly.

[0009] In some embodiments, the valve cover assembly includes a valve cover, a sealing body and a bracket, the sealing body and the valve cover are interference fit, the valve cover is fixed to the valve housing by a bolt connector, and the bracket is fixedly connected to the valve cover.

[0010] In some embodiments, the sealing body has a plurality of steam holes around its circumference, and the steam holes can introduce the steam in the cavity between the rear end of the valve disc and the sealing body into the steam chamber of the steam turbine.

[0011] In some embodiments, the quick-closing valve for a steam turbine further includes a spring assembly, the spring assembly including a spring and a spring seat, the spring seat is fixedly connected to the valve stem of the quick-closing valve for a steam turbine, the spring is sleeved on the valve stem and connected to the spring seat.

[0012] In some embodiments, a sealing ring is fixedly provided inside the valve disc, the sealing ring has a sealing ring stop, a four-way ring is sleeved on the sealing ring stop, and the outer peripheral wall of the four-way ring is interference fit with the inner ring of the valve disc.

[0013] In some embodiments, the circumferential side wall of the clamping ring has relatively arranged bosses, the bosses and the clamping ring have a smooth transition, and the inner wall of the valve housing has a clamping ring installation groove adapted to the bosses.

[0014] The utility model provides a quick-closing valve for a steam turbine, in which the valve seat and the valve housing are matched with each other in clearance, and the valve seat is fixed by a clamping ring, which is convenient for disassembly and assembly. The valve housing and the clamping ring are cleverly designed with a boss structure, which is convenient for disassembly and assembly; the contact circular surfaces of the valve seat, valve disc, valve stem, etc. are made of surfacing-welded Stellite cobalt-chromium-tungsten alloy, which achieves the effects of high temperature resistance, corrosion resistance, wear resistance, etc., and prolongs the service life. The valve stem is provided with a steam groove, and the sealing body of the valve cover assembly is provided with a steam hole, which can reduce the problem of steam leakage from the valve stem; the valve stem is divided into two sections, which reduces the thermal deformation of the valve stem, improves the rigidity, and prevents steam leakage from the valve stem; the spring assembly and the oil cylinder piston assembly are designed separately, and the structure is simple and not easy to cause jamming. The valve cover and the bracket are welded structures, and the bracket is made of steel pipe, which saves costs. The steam turbine quick-closing valve of the present application is simple to install, safe and reliable to use, and can effectively ensure the safety of the steam turbine during use. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 This is a schematic structural diagram of a quick closing valve for a steam turbine according to an embodiment of the utility model;

[0016] Figure 2 A quick closing valve for a steam turbine according to an embodiment of the utility model Figure 1 The local enlarged view of point I in the middle;

[0017] Figure 3 It is a structural schematic diagram of the oil cylinder piston assembly of the quick closing valve for steam turbine according to the embodiment of the utility model;

[0018] Figure 4 This is a schematic structural diagram of a valve cover assembly of a quick-closing valve for a steam turbine according to an embodiment of the utility model;

[0019] Figure 5 This is a schematic diagram of the sealing assembly structure of a quick-closing valve for a steam turbine according to an embodiment of the utility model;

[0020] Figure 6 This is a schematic diagram of the structure of a spring assembly of a quick-closing valve for a steam turbine according to an embodiment of the utility model;

[0021] Figure 7 This is a schematic structural diagram of a coupling assembly of a quick-closing valve for a steam turbine according to an embodiment of the utility model;

[0022] Figure 8 A schematic diagram of the valve stem head structure of a quick-closing valve for a steam turbine according to an embodiment of the utility model;

[0023] Fig. 9 A quick closing valve for a steam turbine according to an embodiment of the utility model Figure 8 Sectional view;

[0024] Fig.10 The utility model is a schematic diagram of the four-ring structure of the quick-closing valve for steam turbine according to the embodiment of the present utility model.

[0025] The reference numerals are as follows:

[0026] 100, steam outlet; 101, valve housing; 102, first valve stem; 103, spring assembly; 104, coupling assembly; 105, second valve stem; 106, oil cylinder piston assembly; 107, valve cover assembly; 108, sealing assembly; 109, steam inlet; 110, valve seat; 111, filter screen; 112, valve disc; 113, four-in-one ring; 114, sealing ring; 115, wear-resistant layer; 116, snap ring; 117, set screw 1; 118, pre-start valve seat; 119, set screw 2; 200, sealing body; 201, valve cover; 202, Bolted connector; 203, bracket; 204, connecting flange; 205, centering plate; 206, first bolted connector; 207, steam vent; 300, sealing sleeve; 301, armored graphite sealing ring; 302, flange cover; 303, second bolted connector; 304, graphite sealing ring; 400, spring seat; 401, spring; 500, flange one; 501, coupling; 502, housing; 503, flange two; 504, guide sleeve; 505, third bolted connector; 506, fourth bolted connector; 601, steam vent. DETAILED DESCRIPTION

[0027] See also Figures 1 to 10 As shown, according to an embodiment of the utility model, a quick-closing valve for a steam turbine is provided, comprising a valve housing 101 and a valve cover assembly 107 connected in sequence, wherein a valve seat 110 is provided in the valve housing 101, the valve seat 110 is clearance-fitted with the valve housing 101, and the valve seat 110 is fixed to the valve housing 101 by a retaining ring 116, and a valve disc 112 is provided in the valve cover assembly 107, the valve disc 112 is in abutment with the valve seat 110, and a wear-resistant layer 115 is provided on the two contact surfaces of the valve disc 112 and the valve seat 110. In the prior art, the valve seat 110 is usually interference-fitted with the valve housing 101, and after the valve seat 110 is installed in the valve housing 101, it is fixed by spot welding, which has the disadvantage of being inconvenient to disassemble and assemble. In the present application, the valve seat 110 is clearance-fitted with the valve housing 101, and the valve seat 110 is fixed by a retaining ring 116, which is convenient for disassembly and assembly. The valve housing 101 and the clamping ring 116 are cleverly designed with a boss structure, which is easy to disassemble and assemble. In the prior art, the contact surface between the valve disc 112 and the valve seat 110 is easily worn, resulting in uneven contact of the sealing surface and the valve cannot be completely closed. The present application provides a wear-resistant layer 115 on the contact circular surface of the valve seat 110 and the valve disc 112 to achieve high temperature resistance, corrosion resistance, wear resistance and other effects, thereby extending the service life.

[0028] In a specific embodiment, the quick-closing valve for a steam turbine also includes a pre-start valve seat 118, and the pre-start valve seat 118 is interference fit with the valve disc 112, and the pre-start valve seat 118 and the outer end surface of the valve disc 112 are fastened by a saddle screw. Usually, the pre-start valve seat 118 and the valve disc 112 are designed as an integrated whole. In order to ensure the sealing of the valve stem head and the pre-start valve seat 118, grinding operation is required to ensure uniform contact. If the pre-start valve seat 118 and the valve disc 112 are designed as an integrated whole, the grinding operation will be difficult, and there will be steam leakage caused by uneven contact. The present application adopts an independent design of the pre-start valve seat 118 and the valve disc 112, which can be easily ground.

[0029] In a specific embodiment, the two contact surfaces of the pre-start valve seat 118 and the valve stem head are provided with the wear-resistant layer 115, and the material of the wear-resistant layer 115 is Stellite. The wear-resistant layer 115 is provided on the contact surface of the pre-start valve seat 118 and the valve stem head, and the Stellite cobalt-chromium-tungsten alloy is welded to achieve high temperature resistance, corrosion resistance, wear resistance and other effects, and prolong the service life.

[0030] Specifically, the valve seat 110 and the contact surface (spherical surface) between the valve seat 110 and the valve disc 112 are designed with 3 mm deep Stellite as the contact surface. Stellite is a cobalt-chromium-tungsten alloy that is resistant to wear, corrosion and high-temperature oxidation, which increases the service life and can ensure the closure of the valve.

[0031] Specifically, the contact surface (spherical surface) between the valve disc 112 and the valve seat 110 is welded with 4mm-deep Stellite during design to increase the service life and ensure the closure of the valve.

[0032] Specifically, the pre-start valve seat 118 is an independent structure with the valve disc 112, with interference fit, and is locked on the outside by a set screw 117 distributed at 180 degrees. The contact surface of the pre-start valve seat 118 (the contact surface with the valve stem, which is a spherical surface) is welded with 3mm deep Stellite to improve the service life and ensure a good sealing effect.

[0033] Specifically, the first valve stem 102, the contact surface of the valve stem head (the contact surface with the pre-start valve seat, which is a spherical surface), is welded with 3mm deep Stellite to increase the service life and ensure a good sealing effect.

[0034] In a specific embodiment, the quick-closing valve for a steam turbine also includes a valve stem, and a steam-passing groove 601 is provided at the bottom of the piston boss of the valve stem head, and the steam-passing groove 601 can introduce the steam between the valve disc 112 and the valve cover assembly 107 into the steam chamber of the steam turbine. In the prior art, there is a phenomenon of steam leakage from the valve stem sealing assembly. In order to solve the problem of valve stem steam leakage, the currently used quick-closing valves mostly adopt the method of lengthening the valve stem sealing section, using a combination of a steel sealing sleeve and a graphite sealing sleeve, and adding a steam leakage port to recover the leaked steam, which increases the production cost and the spare parts cost of the wearing parts seal, and causes waste of steam. The steam-passing groove on the valve stem head can reduce the problem of valve stem steam leakage and reduce the development cost at the same time.

[0035] In a specific embodiment, the valve stem includes a first valve stem 102 and a second valve stem 105, one end of the first valve stem 102 is connected to the valve disc 112, the other end of the first valve stem 102 is connected to one end of the second valve stem 105 through a coupling assembly 104, and the other end of the second valve stem 105 extends into the oil cylinder and is connected to the oil cylinder piston assembly 106. Usually, the valve stem is a one-piece type with a large axial length. When it is subjected to high temperature expansion, it deforms, which will cause the disadvantage of reduced sealing. In this application, the valve stem is divided into two sections to reduce the thermal deformation of the valve stem, improve the rigidity, and prevent the valve stem from leaking steam.

[0036] Specifically, one end of the first valve stem 102 is connected to the valve disc 112, the valve disc 112 is located in the valve housing 101 and the valve cover assembly 107 and cooperates with the valve seat 110, the other end of the first valve stem 102 is connected to one end of the second valve stem 105 through the coupling assembly 104, the other end of the second valve stem 105 extends into the oil cylinder and is connected to the oil cylinder piston assembly 106; the valve housing 101 has a steam inlet 109 and a steam outlet 100, a flange connection surface is provided at the end face of the steam outlet 100, and a filter 111 is installed at the steam inlet 109.

[0037] Specifically, the coupling assembly 104 includes a coupling 501, a flange 1 500, a guide sleeve 504, a flange 2 503 and a housing 502. The flange 1 500, the flange 2 503 and the housing 502 are welded together, and the flange 2 503 is fixedly connected by a fourth bolt connector 506. The flange 1 500 of the coupling assembly 104 is connected to the connecting flange 204 of the valve cover assembly 107 by a third bolt connector 505. The first valve stem 102 passes through the guide sleeve 504 and is threadedly connected to the coupling 501. The second valve stem 105 is connected to the coupling 501.

[0038] In a specific embodiment, the valve cover assembly 107 includes a valve cover 201, a sealing body 200 and a bracket 203, wherein the sealing body 200 and the valve cover 201 are interference fit, the valve cover 201 is fixed to the valve housing 101 by a bolt connector 202, and the bracket 203 is fixedly connected to the valve cover 201. In the prior art, the valve cover 201 and the bracket 203 are cast integrated structures, which have high production costs. The valve cover 201 of the present application is a separate casting, and the bracket 203 is made of a steel pipe and is welded to the valve cover 201 and the connecting flange 204 inside and outside, and this structure can save manufacturing costs.

[0039] Specifically, a sealing assembly 108 is installed in the sealing body 200 of the valve cover assembly 107, and its end is fixed by a second bolt connector 303 and a flange cover 302. The sealing assembly 108 includes a steel sealing sleeve 300, an armored graphite sealing ring 301, and a graphite sealing ring 304. The maximum diameter gap between the sealing assembly 108 and the first valve stem 102 is 0.03 mm. When in use, the steel sealing sleeve 300 is installed first, then the armored graphite sealing ring 301, and then the graphite sealing ring 304.

[0040] In a specific embodiment, the sealing body 200 has a plurality of steam holes 207 around it, and the steam holes 207 can introduce the steam in the cavity between the rear end of the valve disc 112 and the sealing body 200 into the steam chamber of the steam turbine. The sealing body 200 has four steam holes 207 of Φ10 around it, so that the steam between the rear end of the valve disc 112 and the sealing body 200 (cavity) can enter the steam chamber of the steam turbine through the steam holes 207 and the valve seat 110, which can reduce or even avoid the steam leakage of the first valve stem 102 and the sealing assembly 108.

[0041] In a specific embodiment, the quick-closing valve for a steam turbine further includes a spring assembly 103, the spring assembly 103 includes a spring 401 and a spring seat 400, the spring seat 400 is fixedly connected to the valve stem of the quick-closing valve for a steam turbine, and the spring 401 is sleeved on the valve stem and connected to the spring seat 400. The spring assembly 103 and the oil cylinder are designed separately, and the oil cylinder is purchased externally, so that the structure is simpler.

[0042] Specifically, the spring seat 400 is connected to the first valve stem 102 by threads. After the spring 401 is adjusted to a suitable installation length, the spring seat 400 is locked by bolts to fix the position. The spring 401 passes through the first valve stem 102 and is installed between the spring seat 400 and the centering plate 205. The centering plate 205 is connected to the coupling flange 205 by a first bolt connector 206.

[0043] In a specific embodiment, a sealing ring 114 is fixedly provided inside the valve disc 112. The sealing ring 114 has a sealing ring stop. A four-way ring 113 is sleeved on the sealing ring stop. The outer peripheral wall of the four-way ring 113 is interference fit with the inner ring of the valve disc 112. From the perspective of assembly, the four-way ring is designed to be four and a half. If it is a full circle, it will not be able to be installed normally. The sealing ring 114 and the valve disc 112 are fixed with a set screw 119, because when the valve stem moves to the right, it is required to drive the valve disc 112 and the sealing ring 114 to move to the right together. The set screw 119 alone cannot meet the requirements. A four-in-one ring 113 is added to make the outer circle of the four-in-one ring 113 match the tolerance of the valve disc 112, and the inner circle of the four-in-one ring 113 is stuck on the stop of the sealing ring. When the valve stem moves to the right, the right end face of the valve stem head contacts the left end faces of the four-in-one ring 113 and the sealing ring 114, thereby driving the valve disc 112 and the sealing ring 114 to move to the right.

[0044] Specifically, the four-ring 113 is composed of four ring bodies, and the circumferential gap between the ring bodies is 1-2 mm, which can ensure the reasonable installation of the four-ring 113 and have enough thermal expansion gap when heated at high temperature.

[0045] In a specific embodiment, the circumferential side wall of the clamp ring 116 has a boss arranged opposite to each other, the boss and the clamp ring 116 have a smooth transition, and the inner wall of the valve housing 101 has a clamp ring installation groove adapted to the boss. After the clamp ring 116 is installed in the clamp ring installation groove and rotated at a certain angle, the axial position of the clamp ring can be limited, thereby fixing the valve seat 110 in the valve housing 101.

[0046] Specifically, the rationality of installation is taken into consideration in the structural design of the valve housing 101 and the clamping ring 116. The clamping ring 116 is designed with bosses in the range of 80° above and below, and the clamping ring installation groove in the valve housing 101 is designed to be elliptical, which ensures that the clamping ring 116 can be easily installed and can maintain an unchanged axial position in the valve housing 101. To prevent the clamping ring 116 from circumferential movement, the clamping ring 116 and the valve housing 101 can be riveted at three points during installation. During installation, the boss is placed in the clamping ring installation groove, and then the clamping ring 116 is rotated, and the boss slides out of the clamping ring installation groove and is clamped on the valve housing 101 to achieve axial positioning.

[0047] The above is only a preferred embodiment of the utility model, and is not intended to limit the utility model. Any modifications, equivalent replacements and improvements made within the spirit and principles of the utility model should be included in the protection scope of the utility model. The above is only a preferred implementation of the utility model. It should be pointed out that for ordinary technicians in this technical field, several improvements and variations can be made without departing from the technical principles of the utility model, and these improvements and variations should also be regarded as the protection scope of the utility model.

Claims

1. A quick-closing valve for a steam turbine, comprising a valve housing (101) and a valve cover assembly (107) connected in sequence, characterized in that: The valve housing (101) has a valve seat (110) therein, the valve seat (110) and the valve housing (101) are clearance-fitted, and the valve seat (110) is fixed to the valve housing (101) via a retaining ring (116); a valve disc (112) is provided in the valve cover assembly (107), the valve disc (112) and the valve seat (110) are in abutment with each other, and two contact surfaces of the valve disc (112) and the valve seat (110) are provided with a wear-resistant layer (115).

2. The quick closing valve for steam turbine according to claim 1, characterized in that: It also comprises a pre-start valve seat (118), wherein the pre-start valve seat (118) is interference fit with the valve disc (112), and the pre-start valve seat (118) and the outer end surface of the valve disc (112) are fastened by a saddle screw.

3. The quick closing valve for steam turbine according to claim 2, characterized in that: The two contact surfaces between the pre-start valve seat (118) and the valve stem head are provided with the wear-resistant layer (115), and the material of the wear-resistant layer (115) is Stellite.

4. The quick closing valve for a steam turbine according to claim 1 or 3, characterized in that: It also comprises a valve stem, wherein the bottom of the piston boss of the valve stem head is provided with a steam passage groove (601), and the steam passage groove (601) can introduce the steam between the valve disc (112) and the valve cover assembly (107) into the steam chamber of the steam turbine.

5. The quick closing valve for steam turbine according to claim 4, characterized in that: The valve stem comprises a first valve stem (102) and a second valve stem (105), one end of the first valve stem (102) is connected to the valve disc (112), the other end of the first valve stem (102) is connected to one end of the second valve stem (105) via a coupling assembly (104), and the other end of the second valve stem (105) extends into the oil cylinder and is connected to the oil cylinder piston assembly (106).

6. The quick closing valve for steam turbine according to claim 1, characterized in that: The valve cover assembly (107) comprises a valve cover (201), a sealing body (200) and a bracket (203); the sealing body (200) and the valve cover (201) are in interference fit; the valve cover (201) is fixed to the valve housing (101) via a bolt connector (202); and the bracket (203) is fixedly connected to the valve cover (201).

7. The quick closing valve for steam turbine according to claim 6, characterized in that: The sealing body (200) has a plurality of steam holes (207) in the circumferential direction, and the steam holes (207) are capable of introducing steam in the cavity between the rear end of the valve disc (112) and the sealing body (200) into the steam chamber of the steam turbine.

8. The quick closing valve for steam turbine according to claim 1, characterized in that: It also comprises a spring assembly (103), the spring assembly (103) comprising a spring (401) and a spring seat (400), the spring seat (400) being fixedly connected to the valve stem of the quick-closing valve for the steam turbine, the spring (401) being sleeved on the valve stem and connected to the spring seat (400).

9. The quick closing valve for steam turbine according to claim 1, characterized in that: A sealing ring (114) is fixedly arranged inside the valve disc (112), the sealing ring (114) having a sealing ring stop, a four-way ring (113) sleeved on the sealing ring stop, and an outer peripheral wall of the four-way ring (113) is interference-fitted with an inner ring of the valve disc (112).

10. The quick closing valve for steam turbine according to claim 1, characterized in that: The circumferential side wall of the clamping ring (116) has bosses arranged opposite to each other, the bosses transition smoothly with the clamping ring (116), and the inner wall of the valve housing (101) has a clamping ring mounting groove adapted to the bosses.

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