Low-pressure main steam valve and feedwater pump turbine

Abstract

This invention provides a low-pressure main steam valve and a feedwater pump turbine, belonging to the field of thermal power generation technology, to solve the problems of large weight and volume, and high manufacturing cost of the low-pressure main steam valve for feedwater pump turbines. The low-pressure main steam valve of this invention includes a valve body and a valve core. The valve body includes a valve seat cavity, a main cavity, an outlet flange, a valve cover assembly, an inlet flange, and a flow divider. The valve seat cavity and the main cavity are interconnected and coaxial. The outlet flange is connected to the free end of the valve seat cavity. The valve cover assembly is connected to the free end of the main cavity. The inlet flange is connected to the side wall of the main cavity. The flow divider is disposed on the inner wall of the main cavity and located opposite the inlet flange. The valve core is disposed within the valve body. This invention can reduce the volume and weight of the low-pressure main steam valve, shorten the production cycle and manufacturing cost, and improve the internal steam flow performance of the low-pressure main steam valve.

Description

Technical Field

[0001] This utility model belongs to the field of thermal power generation technology, specifically relating to a low-pressure main steam valve and a feedwater pump turbine. Background Technology

[0002] The feedwater pump turbine is a key auxiliary equipment in thermal power plants, playing a decisive role in ensuring the stable operation of the boiler feedwater system, improving unit efficiency, and ensuring the overall safe and economical operation of the power plant. The feedwater pump turbine is typically driven by low-pressure steam (pressure range 0.8–1.5 MPa, temperature 300–350℃) extracted from the main turbine. This steam passes sequentially through the low-pressure main steam valve and the low-pressure regulating valve of the feedwater pump turbine before entering the flow path to perform work. Currently, the low-pressure main steam valve of the feedwater pump turbine generally adopts an integrated casting structure. Due to the characteristics of the casting process and the relatively low allowable high-temperature stress of the blank, the design wall thickness of the cast valve shell is significantly increased (usually more than 1.2 times that of the forged valve shell) to meet the same operating conditions, increasing the product's volume and weight. Furthermore, due to the wall thickness limitation, the cavity space of the low-pressure main steam valve is relatively small, leading to turbulent flow of low-pressure steam within it. This can easily cause valve stem vibration and large valve pressure loss, affecting the safe operation of the unit. Furthermore, the casting process is lengthy and technically challenging, making it difficult to guarantee casting quality. This can leave inherent quality defects in complex areas that cannot be covered by non-destructive testing, posing safety hazards during operation. For the production of small-batch feedwater pump turbines, there are also issues such as high manufacturing costs for low-pressure main steam valve molds, long production cycles, and the susceptibility of castings to defects like shrinkage cavities and porosity. Utility Model Content

[0003] Therefore, the technical problem to be solved by this utility model is to provide a low-pressure main steam valve and a feedwater pump turbine, which can reduce the volume and weight of the low-pressure main steam valve, reduce the production cycle and manufacturing cost of the low-pressure main steam valve, and improve the internal steam flow performance of the low-pressure main steam valve.

[0004] To address the aforementioned problems, this utility model provides a low-pressure main steam valve, comprising a valve body and a valve core. The valve body includes a valve seat cavity, a main cavity, an outlet flange, a valve cover assembly, an inlet flange, and a flow divider. The valve seat cavity and the main cavity are interconnected and coaxial. The outlet flange is connected to the free end of the valve seat cavity. The valve cover assembly is connected to the free end of the main cavity. The inlet flange is connected to the side wall of the main cavity. The flow divider is disposed on the inner wall of the main cavity and located opposite the inlet flange. The valve core is disposed within the valve body.

[0005] The valve seat cavity and the main cavity are made of seamless steel pipes.

[0006] The valve seat cavity is welded to the main cavity. The outlet flange is welded to the valve seat cavity. The inlet flange is welded to the side wall of the main cavity. The flow divider is welded to the inner wall of the main cavity.

[0007] The flow divider is V-shaped, consisting of an open end and a closed end. The open end is connected to the inner wall of the main cavity. The closed end faces the inlet flange.

[0008] The manifold has a manifold groove in the middle. The manifold groove runs through the manifold along its thickness.

[0009] The valve cover assembly includes: a valve cover body, fasteners, a gasket, and a valve stem leakage guide. The valve cover body is fixed to the end of the main cavity by fasteners. The gasket is disposed between the end of the main cavity and the valve cover body. The valve cover body has a valve stem mounting hole. The valve stem leakage guide connects to the side wall of the valve stem mounting hole.

[0010] The valve core includes: a valve seat, a valve disc, a filter screen, a main steam valve stem, and an actuator valve stem. The valve seat is located within the valve seat cavity. The end of the valve seat facing the valve cover assembly has a throat. The valve disc is located on the side of the throat near the valve cover assembly. The valve disc and the inner wall of the throat contact each other to form a sealing surface. The filter screen is cylindrical, located within the main cavity, and coaxial with the main cavity. Both ends of the filter screen are sealed to the valve seat and the valve cover assembly, respectively. A flow divider is located radially outside the filter screen. One end of the main steam valve stem is connected to the valve disc. The free end of the main steam valve stem extends beyond the main cavity through the valve cover assembly. The actuator valve stem is connected to the free end of the main steam valve stem via a valve position indicator.

[0011] The valve core component also includes a packing ring, a valve stem sleeve, and a threaded sleeve. The packing ring is positioned between the outer wall of the main steam valve stem and the valve cover assembly. The valve stem sleeve and threaded sleeve are fitted onto the main steam valve stem and seal both ends of the packing ring.

[0012] The low-pressure main steam valve also includes a pre-opening valve structure. The pre-opening valve structure includes: a valve disc inner bore, a steam inlet, a sealing rod, and a gland. The valve disc inner bore is located on the valve disc. The valve disc inner bore includes a small-diameter section and a large-diameter section that are interconnected. The small-diameter section communicates with the valve seat cavity. The large-diameter section communicates with the main cavity. The steam inlet is located on the valve disc. The steam inlet communicates between the main cavity and the side wall of the large-diameter section. The sealing rod is connected to the end of the main steam valve stem and is coaxial with the main steam valve stem. The diameter of the sealing rod is larger than the diameter of the main steam valve stem. The diameter of the sealing rod is larger than the diameter of the small-diameter section. The sealing rod is located in the large-diameter section. The free end of the sealing rod abuts against the connection between the large-diameter section and the small-diameter section to form the pre-opening valve sealing surface. The gland is fitted onto the main steam valve stem. The gland is sealed between the inner wall of the large-diameter section and the outer wall of the main steam valve stem. The gland is fixed to the valve disc by a locating pin.

[0013] This utility model also provides a feedwater pump turbine, which includes the aforementioned low-pressure main steam valve.

[0014] Beneficial effects:

[0015] The low-pressure main steam valve provided by this utility model includes a valve body and a valve core. The valve body includes a valve seat cavity, a main cavity, an outlet flange, a valve cover assembly, an inlet flange, and a flow divider. The valve core is disposed within the valve body. The valve body of this utility model has a split structure, consisting of a valve seat cavity, a main cavity, an outlet flange, a valve cover assembly, and an inlet flange, which reduces the difficulty of manufacturing and testing, avoids quality defects in complex parts, and improves product quality. At the same time, this utility model can significantly reduce the thickness of the valve body, ensuring internal space while reducing volume and weight, allowing steam to flow more smoothly within the valve cavity, resulting in faster valve warm-up and rapid start-up and shutdown of the unit. The low-pressure main steam valve provided by this utility model does not require the use of casting molds, reducing production cycle and manufacturing costs. In addition, the flow divider in the main cavity of this utility model can make the steam flow within the main cavity more uniform, reduce valve pressure loss, and prevent main steam valve stem vibration. Attached Figure Description

[0016] Figure 1 A cross-sectional view of a low-pressure main steam valve according to an embodiment of this utility model;

[0017] Figure 2 A cross-sectional view of a valve housing according to an embodiment of this utility model;

[0018] Figure 3 A cross-sectional schematic diagram of a flow divider according to an embodiment of this utility model;

[0019] Figure 4 A cross-sectional view of the valve seat and valve disc according to one embodiment of the present utility model;

[0020] Figure 5 This is a schematic diagram of a pre-start valve structure according to an embodiment of the present invention.

[0021] The reference numerals in the attached figures are as follows:

[0022] 1. Valve housing; 2. Valve core; 3. Pre-opening valve structure;

[0023] 11. Valve seat cavity; 12. Main cavity; 13. Outlet flange; 14. Valve cover assembly; 15. Inlet flange; 16. Flow divider;

[0024] 141. Valve cover body; 142. Fastener; 143. Gasket; 144. Valve stem leakage guide; 145. Valve stem mounting hole;

[0025] 161. Diverter plate groove;

[0026] 21. Valve seat; 22. Valve butterfly; 23. Filter screen; 24. Main steam valve stem; 25. Actuator valve stem; 26. Throat; 27. Sealing surface; 28. Valve position indicator; 29. ​​Packing ring; 210. Valve stem sleeve; 211. Threaded sleeve;

[0027] 31. Valve disc inner hole; 32. Steam inlet hole; 33. Sealing rod; 34. Gland; 35. Locating pin; 36. Pre-opening valve sealing surface. Detailed Implementation

[0028] In the description of this utility model, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", etc., indicating the orientation or positional relationship are based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this utility model and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this utility model.

[0029] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this utility model, "a plurality of" means two or more, unless otherwise explicitly specified.

[0030] In this utility model, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model according to the specific circumstances.

[0031] The preferred embodiments of the present invention will be described below with reference to the accompanying drawings. It should be understood that the preferred embodiments described herein are for illustration and explanation only and are not intended to limit the present invention.

[0032] This embodiment provides a low-pressure main steam valve. Figure 1 This is a cross-sectional view of a low-pressure main steam valve provided in this embodiment. Figure 2 This is a cross-sectional view of the valve housing in this embodiment.

[0033] like Figure 1 and Figure 2 As shown, the low-pressure main steam valve in this embodiment includes a valve body 1 and a valve core 2. The valve body 1 includes a valve seat cavity 11, a main cavity 12, an outlet flange 13, a valve cover assembly 14, an inlet flange 15, and a flow divider 16. The valve seat cavity 11 and the main cavity 12 are interconnected and coaxial. The outlet flange 13 is connected to the free end of the valve seat cavity 11. The valve cover assembly 14 is connected to the free end of the main cavity 12. The inlet flange 15 is connected to the side wall of the main cavity 12. The flow divider 16 is disposed on the inner wall of the main cavity 12 and located opposite the inlet flange 15. The valve core 2 is disposed within the valve body 1.

[0034] The outlet flange 13 and inlet flange 15 of this implementation use standard specification flanges, which are easy to purchase, require no processing, and reduce production costs.

[0035] In this embodiment, the valve housing 1 is a split structure, consisting of a valve seat cavity 11, a main cavity 12, an outlet flange 13, a valve cover assembly 14, and an inlet flange 15. This reduces manufacturing and testing difficulties, avoids quality defects in complex parts, and improves product quality. Simultaneously, this embodiment significantly reduces the thickness of the valve housing 1, ensuring sufficient internal space while reducing volume and weight. This allows for smoother steam flow within the valve cavity, faster valve warm-up, and rapid unit start-up and shutdown. The low-pressure main steam valve provided in this embodiment does not require casting molds, reducing production cycle and manufacturing costs. Furthermore, this embodiment incorporates a flow divider 16 in the main cavity 12, which promotes more uniform steam flow within the main cavity 12, reduces valve pressure loss, and prevents vibration of the main steam valve stem 24.

[0036] Among them, such as Figure 2 As shown, the valve seat cavity 11 and the main cavity 12 are made of seamless steel pipes.

[0037] In this embodiment, the valve seat cavity 11 and the main cavity 12 are connected after being machined from seamless steel pipes. This reduces the wall thickness of the low-pressure main steam valve shell 1, lowers the manufacturing cost, and can reduce the valve warm-up time, shorten the warm-up start-up time, and enable the feedwater pump turbine to start up quickly.

[0038] Among them, such as Figure 2 As shown, the valve seat cavity 11 and the main cavity 12 are connected by welding. The outlet flange 13 is connected to the valve seat cavity 11 by welding. The inlet flange 15 is connected to the side wall of the main cavity 12 by welding. The diverter plate 16 is welded to the inner wall of the main cavity 12.

[0039] In this embodiment, the outlet flange 13, valve seat cavity 11, main cavity 12 and inlet flange 15 are connected together by welding and heat treatment after the mating interfaces are machined. The diversion plate 16 is welded to the inner wall of the main cavity 12 opposite to the inlet flange 15, which reduces the manufacturing difficulty and structural complexity of the valve body 1 and avoids internal quality defects.

[0040] Figure 3 This is a cross-sectional schematic diagram of a flow divider 16 provided in this embodiment. Wherein, as... Figure 3 As shown, the flow divider 16 is V-shaped, including an open end and a closed end. The open end is connected to the inner wall of the main cavity 12. The closed end faces the inlet flange 15.

[0041] The diversion plate 16 in this embodiment is designed in a V-shape with inclined surfaces on both sides. This design can ensure structural strength and provide better diversion and guidance, reducing steam flow turbulence after steam enters the main cavity 12 from the inlet flange 15, reducing valve pressure loss, and preventing vibration of the main steam valve stem 24.

[0042] Among them, such as Figure 1 and Figure 2 As shown, a flow divider groove 161 is provided in the middle of the flow divider 16. The flow divider groove 161 penetrates the flow divider 16 along the thickness direction of the flow divider 16.

[0043] In this embodiment, a flow divider groove 161 is provided in the middle of the flow divider 16, which can make the steam pressure in the main cavity 12 more balanced, so that the steam can pass through the filter screen 23 more evenly, and further achieve the purpose of reducing valve pressure loss and preventing the main steam valve stem 24 from vibrating.

[0044] Among them, such as Figure 2 As shown, the valve cover assembly 14 includes: a valve cover body 141, a fastener 142, a gasket 143, and a valve stem leakage conduit 144. The valve cover body 141 is fixed to the end of the main cavity 12 by the fastener 142. The gasket 143 is disposed between the end of the main cavity 12 and the valve cover body 141. The valve cover body 141 is provided with a valve stem mounting hole 145. The valve stem leakage conduit 144 communicates with the side wall of the valve stem mounting hole 145.

[0045] The fasteners 142 in this embodiment are bolts and nuts. The valve cover body 141 is fixed to the main cavity 12 using the bolts and nuts. A gasket 143 is placed between the end of the main cavity 12 and the valve cover body 141, serving a sealing function. A valve stem leakage conduit 144 is provided to guide the leaked steam from the valve stem mounting hole 145 to the shaft seal cooler for steam heat and water recovery.

[0046] Figure 4 This is a cross-sectional view of a valve seat 21 and a valve disc 22 provided for this embodiment. Figure 1and Figure 4 As shown, the valve core 2 includes: a valve seat 21, a valve disc 22, a filter screen 23, a main steam valve stem 24, and an actuator valve stem 25. The valve seat 21 is disposed in the valve seat cavity 11. The end of the valve seat 21 facing the valve cover assembly 14 has a throat 26. The valve disc 22 is disposed on the side of the throat 26 near the valve cover assembly 14. The valve disc 22 contacts the inner wall of the throat 26, forming a sealing surface 27. The filter screen 23 is cylindrical, disposed in the main cavity 12, and coaxial with the main cavity 12. Both ends of the filter screen 23 are sealed to the valve seat 21 and the valve cover assembly 14, respectively. A flow divider 16 is located radially outside the filter screen 23. One end of the main steam valve stem 24 is connected to the valve disc 22. The free end of the main steam valve stem 24 extends through the valve cover assembly 14 and beyond the main cavity 12. The actuator valve stem 25 is connected to the free end of the main steam valve stem 24 via the valve position indicator device 28.

[0047] In this embodiment, the valve seat 11 has a throat 26 at one end facing the valve cover assembly 14, and the valve disc 22 is disposed on the side of the throat 26 near the valve cover assembly 14. This helps to increase the contact area between the valve seat 21 and the valve disc 22, thereby increasing the annular area of ​​the sealing surface 27 to accommodate steam flow with a larger specific volume.

[0048] The filter screen 23 in this embodiment is cylindrical and can surround the inlet of the valve core 2, ensuring that the steam entering the main cavity 12 from the inlet flange 15 can only pass through the valve core 2 and enter the valve seat cavity 11 after being filtered by the filter screen 23.

[0049] In this embodiment, the main steam valve stem 24 and the actuator stem 25 are connected as a single unit via a threaded connection using the valve position indicator 28. An actuator bracket is mounted on the valve cover assembly 14, and the low-pressure main steam valve actuator and spring are mounted on the actuator bracket. When the low-pressure main steam valve actuator operates, it overcomes the spring force by pulling the main steam valve stem 24 through the actuator stem 25, which in turn pulls the valve disc 22, thus opening the valve. When the low-pressure main steam valve actuator does not operate, the spring quickly presses the main steam valve stem 24 to the closed position, causing the valve disc 22 to contact the inner wall of the throat 26, forming a sealing surface 27, thereby achieving rapid closure of the low-pressure main steam valve and preventing overspeed of the feedwater pump turbine.

[0050] Among them, such as Figure 1 As shown, the valve core component 2 also includes: a packing ring 29, a valve stem sleeve 210, and a threaded sleeve 211. The packing ring 29 is disposed between the outer wall of the main steam valve stem 24 and the valve cover assembly 14. The valve stem sleeve 210 and the threaded sleeve 211 are sleeved on the main steam valve stem 24, and the valve stem sleeve 210 and the threaded sleeve 211 seal both ends of the packing ring 29.

[0051] In this embodiment, the packing ring 29 is made of flexible graphite.

[0052] In this embodiment, the main steam valve stem 24 extends out of the main cavity 12 through the valve stem mounting hole 154 on the valve cover body 141 and connects to the actuator valve stem 25. The packing ring 29 is sealed between the outer periphery of the main steam valve stem 24 and the inner wall of the valve stem mounting hole 145 by the valve stem sleeve 210 and the threaded sleeve 211, which prevents steam leakage. The valve stem sleeve 210 and the threaded sleeve 211 are fixed to the valve cover body 141 by threads and are riveted to prevent loosening.

[0053] Figure 5 This is a schematic diagram of a pre-opening valve structure 3 provided in this embodiment. Wherein, as... Figure 1 , 4 As shown in Figure 5, the low-pressure main steam valve also includes a pre-opening valve structure 3. The pre-opening valve structure 3 includes: a valve disc inner bore 31, a steam inlet 32, a sealing rod 33, and a gland 34. The valve disc inner bore 31 is located on the valve disc 22. The valve disc inner bore 31 includes a small-diameter section and a large-diameter section connected to each other. The small-diameter section communicates with the valve seat cavity 11. The large-diameter section communicates with the main cavity 12. The steam inlet 32 ​​is located on the valve disc 22. The steam inlet 32 ​​communicates between the main cavity 12 and the side wall of the large-diameter section of the valve disc inner bore 31. The sealing rod 33 is connected to the end of the main steam valve stem 24 and is coaxial with the main steam valve stem 24. The diameter of the sealing rod 33 is larger than the diameter of the main steam valve stem 24. The diameter of the sealing rod 33 is larger than the diameter of the small-diameter section of the valve disc inner bore 31. The sealing rod 33 is located in the large-diameter section. The free end of the sealing rod 33 abuts against the junction of the large-diameter section and the small-diameter section to form the pre-opening valve sealing surface 36. The gland 34 is fitted onto the main steam valve stem 24. The gland 34 is sealingly connected between the inner wall of the large-diameter section and the outer wall of the main steam valve stem 24. The gland 34 is fixed to the valve disc 22 by a locating pin 35.

[0054] In this embodiment, the free end of the sealing rod 33 abuts against the connection between the large-diameter section and the small-diameter section to form the pre-opening valve sealing surface 36; the gland 34 and the valve butterfly 22 are fixed by threads and then positioned and prevented from loosening by the positioning pin 35.

[0055] In this embodiment, the sealing rod 33 is located in the receiving space enclosed by the large-diameter section and the gland 34, and when the main steam valve stem 24 is actuated, the sealing rod 33 can move relative to this receiving space to form a pre-opening valve stroke L.

[0056] When the low-pressure main steam valve is closed, the valve disc 22 and the inner wall of the throat 26 of the valve seat 21 come into contact with each other to form a sealing surface 27; the free end of the sealing rod 33 abuts against the connection between the large-diameter section and the small-diameter section to form a pre-opening valve sealing surface 36 (i.e., the pre-opening valve structure is in the closed state). At this time, the steam in the main cavity 12 cannot enter the valve seat cavity 11 through the valve core 2;

[0057] When the low-pressure main steam valve actuator operates, it overcomes the spring force by pulling the main steam valve stem 24 through the actuator valve stem 25, which in turn pulls the sealing rod 33, causing the sealing rod 33 to move towards the gland 34, thereby causing the pre-opening valve sealing surface 36 to fail. At this time, a small amount of steam in the main chamber 12 can enter the large-diameter section of the valve disc inner hole 31 through the steam inlet hole 32, and then enter the valve seat cavity 11 through the small-diameter section, so as to reduce the pressure difference before and after the valve disc 22 (i.e., the pressure difference between the main chamber 12 and the valve seat cavity 11), so that the low-pressure main steam valve actuator can achieve the function of opening the valve disc 22 with a smaller force;

[0058] When the sealing rod 33 abuts against the gland 34, the opening stroke of the pre-opening valve structure is completed. The actuator valve stem 25 continues to pull the main steam valve stem 24, which can pull the valve disc 22, causing the sealing surface 27 between the valve seat 21 and the valve disc 22 to fail, thus opening the valve.

[0059] When the low-pressure main steam valve actuator does not operate, the spring quickly presses the main steam valve stem 24 to the closed position. At this time, the valve disc 22 and the inner wall of the throat 26 come into contact, forming a sealing surface 27; the free end of the sealing rod 33 abuts against the connection between the large-diameter section and the small-diameter section, forming a pre-opening valve sealing surface 36. This achieves rapid closure of the low-pressure main steam valve and prevents the feedwater pump turbine from overspeeding.

[0060] The low-pressure main steam valve in this embodiment also includes a pre-opening valve structure 3. When the low-pressure main steam valve is pulled open by the low-pressure main steam valve actuator, the pre-opening valve stroke L is opened first, so that a small amount of steam in the main chamber 12 enters the valve seat chamber 12 through the steam inlet 32. This can reduce the pressure difference between the front and rear sides of the valve butterfly 22, thereby reducing the pulling force required to open the valve butterfly 22.

[0061] This embodiment also provides a feedwater pump turbine, which includes the aforementioned low-pressure main steam valve.

[0062] In this embodiment, the valve body 1 of the low-pressure main steam valve is made of forged components such as seamless steel pipes, end caps, and flanges, which are mature products on the market. The valve body is assembled by machining, welding, and heat treatment. At the same time, a flow divider 16 is provided in the valve body 1, which can solve the problem of large vibration of the main steam valve stem 24 caused by the turbulent flow of steam in the main cavity 12 after the steam enters from the inlet flange 15. It can also reduce valve pressure loss and improve steam utilization efficiency.

[0063] The feedwater pump turbine provided in this embodiment has the low-pressure main steam valve of the above embodiment, and therefore has all the above-mentioned beneficial effects, which will not be repeated here.

[0064] It will be readily understood by those skilled in the art that the aforementioned advantageous methods can be freely combined and superimposed without conflict.

[0065] The above are merely preferred embodiments of this utility model and are not intended to limit the scope of this utility model. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this utility model should be included within the protection scope of this utility model. The above are only preferred embodiments of this utility model. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of this utility model, and these improvements and modifications should also be considered within the protection scope of this utility model.

Claims

1. A low-pressure main steam valve, characterized in that, Including valve housing and valve core; The valve body includes a valve seat cavity, a main cavity, an outlet flange, a valve cover assembly, an inlet flange, and a flow divider; the valve seat cavity and the main cavity are interconnected and coaxial; the outlet flange is connected to the free end of the valve seat cavity; the valve cover assembly is connected to the free end of the main cavity; the inlet flange is connected to the side wall of the main cavity; the flow divider is disposed on the inner wall of the main cavity and located on the opposite side of the inlet flange; The valve core is disposed in the valve body.

2. The low-pressure main steam valve according to claim 1, characterized in that, The valve seat cavity and the main cavity are made of seamless steel pipe.

3. The low-pressure main steam valve according to claim 1 or 2, characterized in that, The valve seat cavity is connected to the main cavity by welding; the outlet flange is connected to the valve seat cavity by welding; the inlet flange is connected to the side wall of the main cavity by welding; and the diverter plate is welded to the inner wall of the main cavity.

4. The low-pressure main steam valve according to claim 1, characterized in that, The diverter plate is V-shaped, including an open end and a closed end; the open end is connected to the inner wall of the main cavity; the closed end faces the inlet flange.

5. The low-pressure main steam valve according to claim 1 or 4, characterized in that, The flow divider plate has a flow divider plate groove in the middle; the flow divider plate groove penetrates the flow divider plate along the thickness direction of the flow divider plate.

6. The low-pressure main steam valve according to claim 1, characterized in that, The valve cover assembly includes: a valve cover body, fasteners, gaskets, and a valve stem leakage conduit; The valve cover body is fixed to the end of the main cavity by the fastener; The gasket is disposed between the end of the main cavity and the valve cover body; The valve cover body is provided with a valve stem mounting hole; the valve stem leakage conduit is connected to the side wall of the valve stem mounting hole.

7. The low-pressure main steam valve according to claim 1, characterized in that, The valve core component includes: valve seat, valve disc, filter screen, main steam valve stem, and actuator valve stem; The valve seat is disposed in the valve seat cavity; the end of the valve seat facing the valve cover assembly has a throat; The valve disc is disposed on the side of the throat near the valve cover assembly; the valve disc and the inner wall of the throat contact each other to form a sealing surface; The filter screen is cylindrical, disposed in the main cavity and coaxial with the main cavity; both ends of the filter screen are respectively sealed to the valve seat and the valve cover assembly; the flow divider is located radially outside the filter screen; One end of the main steam valve stem is connected to the valve disc; the free end of the main steam valve stem extends through the valve cover assembly to the outside of the main cavity; The actuator stem is connected to the free end of the main steam valve stem via a valve position indicator device.

8. The low-pressure main steam valve according to claim 7, characterized in that, The valve core component also includes: a packing ring, a valve stem sleeve, and a threaded sleeve; The packing ring is disposed between the outer wall of the main steam valve stem and the valve cover assembly; The valve stem sleeve and the threaded sleeve are fitted onto the valve stem of the main steam valve, and the valve stem sleeve and the threaded sleeve seal both ends of the packing ring.

9. The low-pressure main steam valve according to claim 7, characterized in that, It also includes a pre-start valve structure; the pre-start valve structure includes: a valve disc inner hole, a steam inlet hole, a sealing rod, and a pressure cap; The valve disc has an inner hole; the valve disc inner hole includes a small diameter section and a large diameter section that are connected to each other; the small diameter section communicates with the valve seat cavity; the large diameter section communicates with the main cavity; The steam inlet is located on the valve disc; the steam inlet connects the main cavity and the side wall of the large-diameter section. The sealing rod is connected to the end of the main steam valve stem and is coaxial with the main steam valve stem; the diameter of the sealing rod is larger than the diameter of the main steam valve stem; the diameter of the sealing rod is larger than the diameter of the small diameter section; the sealing rod is located in the large diameter section; the free end of the sealing rod abuts against the connection between the large diameter section and the small diameter section to form a pre-opening valve sealing surface; The gland is fitted onto the main steam valve stem; the gland is sealed between the inner wall of the large-diameter section and the outer wall of the main steam valve stem; the gland is fixed to the valve disc by a locating pin.

10. A feedwater pump turbine, characterized in that, The feedwater pump turbine includes a low-pressure main steam valve as described in any one of claims 1 to 9.

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