Throttling device with capillary tube for nuclear power station

Abstract

The invention relates to a throttling device with a capillary tube for a nuclear power station, and relates to the technical field of pipeline throttling, the throttling device comprises a spiral capillary tube body, a pore plate main body and a lifting handle fixedly arranged on the periphery of the pore plate main body, and flange plates are fixedly arranged on the two opposite side faces of the pore plate main body; a limiting hole is formed in the pore plate main body in the axis direction of the pore plate main body, a mounting sinking groove for placing a capillary tube body is formed in the edge of an opening in one side of the limiting hole, and one end of the capillary tube body is fixedly connected with the inner wall of the limiting hole; a limiting ring groove is formed in the inner edge of an opening of the mounting sinking groove, a filter screen clamped into the limiting ring groove is arranged on one side of the pore plate body, and a pressing ring abutting against the side, away from the capillary tube body, of the filter screen is fixedly embedded in the inner wall of the limiting ring groove. The limiting ring groove is formed in the inner edge of the opening of the mounting sinking groove, the filter screen is abutted and fixed through the pressing ring, integration of filtering and throttling devices is achieved, additional purchasing of filter elements is not needed, and the equipment purchasing and subsequent maintenance cost is greatly reduced.

Description

Technical Field

[0001] This application relates to the technical field of pipeline throttling, and in particular to a throttling device with a capillary tube for use in nuclear power plants. Background Technology

[0002] In the oil delivery system of a nuclear power plant, precise control of the medium flow rate within the pipeline is one of the key aspects of ensuring stable equipment operation. Because strict regulation of the oil flow rate is required under certain operating conditions, flow-limiting orifice plates become an indispensable core component of this system. Their main function is to adjust the flow cross-section within the pipeline through a specific structure, utilizing the principle of local resistance loss to regulate the flow rate. This ensures that the oil delivery meets the operating parameter requirements of the nuclear power plant equipment, thereby maintaining the normal operating conditions of critical units such as the reactor cooling system and lubrication system. Therefore, the performance stability of the flow-limiting orifice plate has a significant impact on the overall safe operation of the nuclear power plant.

[0003] Currently, mainstream flow-limiting orifice plates used in nuclear power plants typically consist of three parts: the orifice plate body, a lifting handle, and a spiral capillary tube. The lifting handle is fixed to the outer periphery of the orifice plate body for easy installation and maintenance; flanges are integrally formed on opposite sides for connection to the pipeline system. A through-hole is formed along the axis of the orifice plate body, and an installation groove is machined at the edge of one opening of the limiting hole to accommodate the capillary tube. The capillary tube employs a spiral structure design to enhance the throttling effect, and one end is welded to the inner wall of the limiting hole using silver-based welding wire. In practical applications, oil in the upstream pipeline is injected from the side of the limiting hole away from the installation groove, flows through the spiral capillary tube to achieve flow restriction, and finally drains into the installation groove before flowing into the downstream pipeline.

[0004] Under nuclear power plant operating conditions, when the oil flows into the settling tank after being throttled by the spiral capillary tube, it easily carries away contaminants such as metal debris and impurities remaining in the upstream pipeline. If not filtered in time, this can lead to increased wear and tear on downstream equipment and a higher risk of failure. Currently, the solution is to install additional filter elements on the inner wall of the downstream pipeline. However, this solution increases equipment procurement and maintenance costs, and the installation and replacement of filter elements is cumbersome, affecting system operating efficiency and indicating room for improvement. Summary of the Invention

[0005] The purpose of this application is to provide a throttling device with a capillary tube for nuclear power plants, which solves the problems of low efficiency and high cost when additional filter elements are installed in the downstream pipeline in the above-mentioned related technologies.

[0006] The throttling device with a capillary tube for nuclear power plants provided in this application adopts the following technical solution: A throttling device with a capillary tube for nuclear power plants includes a spiral capillary body, an orifice plate body, and a lifting handle fixed to the outer periphery of the orifice plate body. Flanges are fixed on opposite sides of the orifice plate body. A limiting hole is formed on the orifice plate body along its own axis. An installation groove for inserting the capillary body is formed on one side opening edge of the limiting hole. One end of the capillary body is fixedly connected to the inner wall of the limiting hole. A limiting annular groove is formed at the inner edge of the opening of the installation groove. A filter screen is provided on one side of the orifice plate body and is inserted into the limiting annular groove. A pressure ring is fixedly embedded on the inner wall of the limiting annular groove and abuts against the side of the filter screen away from the capillary body.

[0007] By adopting the above technical solution, a limiting annular groove is set along the opening of the installation tank, and the filter screen is pressed and fixed with a pressure ring, realizing the integration of filtration and throttling device. There is no need to purchase additional filter elements, which significantly reduces equipment procurement and subsequent maintenance costs. It eliminates the cumbersome process of installing downstream pipelines and replacing filter elements, avoids interference with system operation during maintenance operations, and effectively improves operating efficiency. The filter screen is precisely set at the key node after the oil is throttled by the capillary body, which can intercept metal debris and impurity particles in time, reduce wear on downstream equipment from the source, and reduce the risk of failure. At the same time, the filter screen is installed firmly, and subsequent maintenance and replacement are convenient. The overall design meets the high requirements of nuclear power plant equipment for performance stability, and takes into account both practicality and reliability.

[0008] Optionally, a positioning plate is provided above the main body of the perforated plate, and a positioning through hole is provided on the positioning plate for the lifting handle to pass through; a locking component is provided on the outside of the main body of the perforated plate, and a flexible protective curtain is fixed on both sides of the positioning plate near the two flanges; the side of the flexible protective curtain away from the positioning plate is detachably connected to the lower part of the flange through the locking component, and the flexible protective curtain at this time protects both sides of the limiting hole.

[0009] By adopting the above technical solution, the protective curtain can effectively shield both sides of the limiting hole during transportation or when idle, preventing dust and impurities from entering or external collisions from damaging the internal structure and protecting the core components of the throttling device; the detachable design takes into account both protection and ease of use, and the protective curtain can be quickly removed when installation or maintenance is required without affecting normal operation.

[0010] Optionally, the locking element includes locking rods located on both sides of the lifting handle and locking blocks fixed to the outer periphery of both ends of the locking rods; the side of the flexible protective curtain away from the positioning plate is fixedly connected to the side of the locking rod away from the locking blocks; the lower part of the flange has two fixing slots opposite to the locking blocks; the two locking blocks on the locking rod are inserted into the two fixing slots on the same side respectively during the packaging and transportation of the throttling device; the locking blocks are provided with elastic snap-fit ​​elements, and the inner wall of the fixing slots is provided with a first groove for the elastic snap-fit ​​elements to snap into.

[0011] By adopting the above technical solution, the combination design of the locking rod and the locking block, together with the fixed slot at the bottom of the flange, can accurately realize the detachable connection between the flexible protective curtain and the flange, ensuring that the protective curtain stably covers both sides of the limiting hole during transportation; the engaging structure of the elastic snap-fit ​​component and the first groove can automatically lock the locking block, preventing the lock from falling off due to transportation bumps, thus enhancing the stability of protection. At the same time, disassembly and assembly can be completed without additional tools, reducing the complexity of operation.

[0012] Optionally, the elastic snap-fit ​​component includes a compression spring and an arc-shaped protrusion. The locking block has a placement groove for the compression spring and the arc-shaped protrusion to be inserted. The compression spring presses one side of the arc-shaped protrusion, causing a part of the arc-shaped protrusion to protrude from the opening of the placement groove. The outer surface of the protruding part of the arc-shaped protrusion is an arc surface, and the arc length corresponding to this arc surface is a minor arc.

[0013] By adopting the above technical solution, the compression spring continuously squeezes to make the arc-shaped protrusion protrude stably, and can automatically lock when it engages with the first groove, ensuring reliable locking; the arc surface of the protrusion is set as a minor arc, and can be smoothly guided in and out through the arc surface during disassembly and assembly without the need for additional tools, making operation convenient; the placement groove provides a stable installation space for the component, the overall structure is compact, adapts to the space requirements of the locking plug, and takes into account both locking effect and ease of disassembly and assembly.

[0014] Optionally, the positioning plate has a positioning groove on its side facing the orifice plate body for the outer edge of the flange and the outer edge of the flange on the external pipe to be engaged together; the two opposite sides of the lifting handle have locking notches, which are located above the positioning plate when the outer edge of the flange is engaged in the positioning groove; the inner edges of the two locking blocks on the two locking rods can be inserted into the locking notches respectively when the outer edge of the flange is engaged in the positioning groove, the bottom surface of the locking rod abuts against the top surface of the positioning plate, and the sides of the locking blocks on the two locking rods abut against each other, and the flexible protective curtain protects the top surface of the positioning plate.

[0015] By adopting the above technical solution, the positioning trough can simultaneously engage the flange and the outer edge of the external pipe flange, accurately positioning the connection position and improving installation stability; the locking rod is inserted into the locking notch and abuts against each other, combined with the bottom surface abutting against the positioning plate, further fixing the positioning plate and the main body of the orifice plate, strengthening the overall structural stability; at the same time, the flexible protective curtain turns to protect the top surface of the positioning plate, preventing dust and impurities from entering after installation; the overall design makes the installation positioning more accurate, the structure more stable, and the protection more comprehensive, and the operation does not require complicated tools, adapting to the installation and protection needs of nuclear power plant equipment.

[0016] Optionally, an elastic pad is fixed on the inner wall of the positioning trough.

[0017] By adopting the above technical solution, the elastic gasket can fill the gap between the flange and the outer edge of the external pipe flange, reduce the loosening between components after installation, and improve the connection sealing and stability; it can buffer vibration and impact, reduce wear and noise during equipment operation; it can also avoid scratch damage caused by direct contact between metal parts, extend the service life of the device, and has a simple structure, does not increase the installation difficulty, and is suitable for the reliability requirements of nuclear power plant equipment.

[0018] Optionally, a second groove is provided on the inner wall of the locking notch for the elastic snap-fit ​​to engage.

[0019] By adopting the above technical solution, a second groove is provided on the inner wall of the locking notch, which can precisely engage with the elastic snap-fit ​​of the locking block to form a double fixing effect. This prevents the locking rod from loosening or shifting during device operation or vibration, and strengthens the connection stability between the positioning plate and the main body of the orifice plate. No additional fixing tools are required; locking can be completed simply by elastic snap-fit, making the operation convenient and efficient. At the same time, the structural design of the elastic snap-fit ​​ensures reliable locking, further improving the structural safety of the device in operation and meeting the stability requirements of nuclear power plant equipment.

[0020] Optionally, the lifting handle is provided with a fixing hole, which is located above the positioning plate when the outer edge of the flange is engaged with the positioning groove; the two locking rods can be installed vertically when the throttling device needs to be moved, the locking blocks at the lower ends of the two locking rods can be inserted into the openings on both sides of the fixing hole, and the locking blocks at the upper ends of the two locking rods abut against each other and are located above the lifting handle.

[0021] By adopting the above technical solution, a fixing hole is provided in the lifting handle, allowing the locking rod to be installed vertically: the lower locking block is inserted into the fixing hole, and the upper end abuts to form a "grip," making it convenient for workers to apply force to move the equipment and solving the problem that the lifting handle may be inconvenient to hold; no additional handling tools are required, and the function can be converted using existing locking components, making operation simple; and the vertical installation is stable, preventing the locking rod from loosening during handling, thus combining practicality and convenience and adapting to the needs of equipment handling.

[0022] Optionally, a third groove is provided on the inner wall of the fixing hole for the elastic snap-fit ​​component to be inserted.

[0023] By adopting the above technical solution, a third groove is provided on the inner wall of the fixing hole, which can precisely engage with the elastic snap-fit ​​of the locking block, firmly fixing the vertically installed locking rod and preventing the locking rod from loosening due to vibration during transportation, thus ensuring the stability of the "grip" structure. Locking and unlocking can be completed without additional tools, making operation convenient. Fixing is achieved by using existing elastic snap-fit, without the need for additional parts, simplifying the structure while improving transportation safety, and meeting the stability requirements of nuclear power plant equipment during transportation.

[0024] Optionally, guide slopes are provided at both sides of the opening of the fixing hole.

[0025] By adopting the above technical solution, a guide slope is provided at the edge of the fixing hole opening, which can provide guidance for the locking block at the lower end of the locking rod: no precise alignment is required when inserting, the slope can guide the block to slide smoothly into the fixing hole, reduce the difficulty of operation, and improve the installation efficiency of the locking rod before transportation.

[0026] In summary, this application includes the following beneficial technical effects: This application features a limiting annular groove along the inside of the installation trough opening, which secures the filter screen with a pressure ring, integrating the filtration and throttling device. This eliminates the need for additional filter elements, significantly reducing equipment procurement and subsequent maintenance costs. It also eliminates the cumbersome process of installing back-end pipelines and replacing filter elements, avoiding interference with system operation and effectively improving operational efficiency. Attached Figure Description Figure 1 This is a schematic diagram of the overall structure of Embodiment 1 of this application; Figure 2 This is a cross-sectional structural diagram illustrating the installation and cooperation of the filter screen and the pressure ring in Embodiment 1 of this application; Figure 3 This is a schematic diagram of the overall structure of Embodiment 2 of this application; Figure 4 This is an exploded structural diagram illustrating the installation distribution of the positioning plate and the flexible protective curtain in Embodiment 2 of this application; Figure 5 This is a cross-sectional structural diagram illustrating the installation and mating of the locking component in Embodiment 2 of this application; Figure 6 yes Figure 5 An enlarged schematic diagram of part A in the middle; Figure 7 This is a cross-sectional view of Embodiment 2 of this application illustrating the installation and fit of the elastic pad; Figure 8 yes Figure 7 Enlarged schematic diagram of part B in the middle; Figure 9 This is a cross-sectional structural diagram illustrating the installation and coordination of the flexible protective curtain in Embodiment 2 of this application; Figure 10 This is a partial cross-sectional view of Embodiment 2 of this application illustrating the installation and fit of the locking rod; Figure 11 This is a partial structural diagram illustrating the distribution of locking gaps in an embodiment of this application.

[0027] In the diagram, 1. Orifice plate body; 11. Flange; 111. Fixing slot; 112. First groove; 12. Limiting hole; 13. Installation groove; 14. Limiting ring groove; 2. Capillary body; 3. Lifting handle; 31. Locking notch; 311. Second groove; 32. Fixing hole; 321. Third groove; 322. Guide slope; 4. Filter screen; 5. Pressure ring; 6. Positioning plate; 61. Positioning through hole; 62. Positioning groove; 63. Elastic pad; 7. Locking component; 71. Locking rod; 72. Locking insert; 721. Placement groove; 73. Elastic snap-fit ​​component; 731. Compression spring; 732. Arc-shaped protrusion; 8. Flexible protective curtain. Detailed Implementation

[0028] The present application will be further described in detail below with reference to all the accompanying drawings.

[0029] Example 1: Reference Figure 1 and Figure 2 A throttling device with a capillary tube for nuclear power plants includes a spiral capillary body 2, an orifice plate body 1 and a lifting handle 3 fixed on the outer periphery of the orifice plate body 1. Flanges 11 are integrally formed on opposite sides of the orifice plate body 1, and several through holes are evenly opened on the flanges 11. A limiting hole 12 is provided on the main body 1 of the orifice plate along its own axis. A mounting groove 13 for inserting a capillary body 2 is provided on one side of the opening edge of the limiting hole 12. One end of the capillary body 2 is fixedly connected to the inner wall of the limiting hole 12. A limiting ring groove 14 is provided at the inner edge of the opening of the mounting groove 13. A filter screen 4 is provided on one side of the main body 1 of the orifice plate, which is inserted into the limiting ring groove 14. A pressure ring 5 is fixedly embedded on the inner wall of the limiting ring groove 14 and abuts against the side of the filter screen 4 away from the capillary body 2.

[0030] The implementation principle of this application embodiment is as follows: In the non-working assembly state: First, fix one end of the spiral capillary body 2 to the inner wall of the limiting hole 12 of the orifice plate body 1, embed it into the installation groove 13, then insert the filter screen 4 into the limiting ring groove 14, and use the pressure ring 5 in the ring groove to press the filter screen 4 to complete the assembly; finally, fix the flange 11 to the flange on the external pipeline with bolts.

[0031] Normal operating condition: The medium is initially filtered by the filter screen (intercepting impurities such as metal shavings to avoid wear on downstream equipment), enters the limiting hole 12, and flows through the spiral capillary body 2 for throttling, controlling the flow rate and pressure to adapt to the working conditions. The flange 11 ensures a stable connection, eliminating the need for additional filtration steps and improving system operating efficiency.

[0032] Example 2: Reference Figure 3 , Figure 4 and Figure 5The difference between this embodiment and Embodiment 1 is that a positioning plate 6 is provided above the perforated plate body 1, wherein a positioning through hole 61 for the lifting handle 3 to pass through is provided on the positioning plate 6; a locking member 7 is provided on the outside of the perforated plate body 1, and a flexible protective curtain 8 is fixed on the two sides of the positioning plate 6 near the two flanges 11. When the throttling device needs to be packaged for shipment, the side of the flexible protective curtain 8 away from the positioning plate 6 is detachably connected to the lower part of the flange 11 through the locking piece 7. At this time, the flexible protective curtain 8 protects both sides of the limiting hole 12, while keeping the bottom surface of the positioning plate 6 and the outer peripheral surface of the orifice plate body 1 in a tight abutment state.

[0033] Reference Figure 4 , Figure 5 and Figure 6 The locking component 7 includes locking rods 71 ​​located on both sides of the lifting handle 3 and locking inserts 72 fixed on the outer periphery of both ends of the locking rods 71. The side of the flexible protective curtain 8 away from the positioning plate 6 is fixedly connected to the side of the locking rod 71 away from the locking inserts 72. The lower part of the flange 11 has two fixing slots 111 opposite to the locking inserts 72. The locking plug 72 is provided with an elastic snap-fit ​​73, and the inner wall of the fixing slot 111 is provided with a first groove 112. When the throttling device is packaged and transported, the two locking plugs 72 on the locking rod 71 are respectively inserted into the two fixing slots 111 on the same side, and at this time the elastic snap-fit ​​73 is snapped into the corresponding first groove 112.

[0034] Reference Figure 5 and Figure 6 The elastic snap-fit ​​component 73 includes a compression spring 731 and an arc-shaped protrusion 732. The locking insert 72 has a placement groove 721 for the compression spring 731 and the arc-shaped protrusion 732 to be inserted. The compression spring 731 presses one side of the arc-shaped protrusion 732 so that a part of the arc-shaped protrusion 732 protrudes from the opening of the placement groove 721. The outer surface of the protruding part of the arc-shaped protrusion 732 is an arc surface, and the arc length corresponding to the arc surface is a minor arc.

[0035] Reference Figure 7 and Figure 8 The positioning plate 6 has a positioning groove 62 on the side facing the orifice plate body 1, which is used to insert the outer edge of the flange 11 and the outer edge of the flange on the external pipe. The inner wall of the positioning groove 62 is fixed with an elastic pad 63 made of rubber. The lifting handle 3 has a fixing hole 32. When the outer edge of the flange 11 is inserted into the positioning groove 62, the fixing hole 32 is located above the positioning plate 6. The two sides of the opening of the fixing hole 32 are provided with guide slopes 322. The inner wall of the fixing hole 32 has a third groove 321. When the throttling device needs to be moved, the two locking rods 71 ​​can be installed vertically, so that the locking blocks 72 at the lower end of the two locking rods 71 ​​are inserted into the openings on both sides of the fixing hole 32 along the guide slope 322. At this time, the elastic snap-fit ​​73 at the lower end is snapped into the corresponding third groove 321, and the locking blocks 72 at the upper end of the two locking rods 71 ​​abut against each other and are located above the lifting handle 3. At this time, the upper ends of the two locking rods 71 ​​can work together as a "handle" to facilitate the staff to apply force to move it.

[0036] Reference Figure 9 , Figure 10 and Figure 11 Locking notches 31 are provided on the opposite sides of the lifting handle 3. When the outer edge of the flange 11 is engaged with the positioning groove 62, the locking notches 31 are located above the positioning plate 6. A second groove 311 is provided on the inner wall of the locking notches 31. When the throttling device is connected to the external pipeline, the locking plug 72 is first removed from the fixed slot 111, and then the inner edges of the two locking plugs 72 on the two locking rods 71 ​​are respectively inserted into the locking notch 31. At this time, the elastic snap fastener 73 is snapped into the corresponding second groove 311. The outer edge of the flange 11 and the outer edge of the flange on the external pipeline are snapped into the positioning groove 62. At this time, the bottom surface of the locking rod 71 abuts against the top surface of the positioning plate 6, and the sides of the locking plugs 72 on the two locking rods 71 ​​that are close to each other abut against each other. The flexible protective curtain 8 can also protect the top surface of the positioning plate 6 at this time.

[0037] The implementation principle of this application embodiment is as follows: The packaging condition for shipment is as follows: the locking block 72 of the locking rod 71 is inserted into the fixing slot 111 at the bottom of the flange 11, the elastic snap fastener 73 is snapped into the first groove 112, the flexible protective curtain 8 is connected to the bottom of the flange 11, and the protective limit hole 12 is on both sides; the bottom surface of the positioning plate 6 is pressed against the outer periphery of the perforated plate body 1, thus completing the packaging protection.

[0038] Handling status: The locking rod 71 is installed vertically, and the locking insert 72 at the lower end of the locking rod 71 is inserted into the fixing hole 32 along the guide slope 322. At this time, the elastic snap fastener 73 is snapped into the third groove 321; the upper locking insert 72 abuts against the top of the lifting handle 3 to form a "grip" for easy handling by the staff.

[0039] When connected to an external pipeline: Pull out the locking plug 72, adjust the locking rod 71 to a horizontal position, insert the two locking plugs 72 into the locking notch 31 on the lifting handle 3, at which time the elastic snap-fit ​​73 snaps into the second groove 311; the flange 11 and the outer edge of the external pipeline flange snap into the positioning groove 62 (elastic pad 63 assists in fixing), the bottom surface of the locking rod 71 abuts against the top surface of the positioning plate 6 and they abut against each other, and the flexible protective curtain 8 protects the top surface of the positioning plate 6.

[0040] The embodiments described in this specific implementation are preferred embodiments of this application and are not intended to limit the scope of protection of this application. Identical components are represented by the same reference numerals. Therefore, all equivalent changes made to the structure, shape, and principle of this application should be covered within the scope of protection of this application.

Claims

1. A throttling device with a capillary tube for nuclear power plants, comprising a spiral capillary body (2), an orifice plate body (1), and a lifting handle (3) fixed on the outer periphery of the orifice plate body (1). Flanges (11) are fixed on opposite sides of the orifice plate body (1). A limiting hole (12) is provided on the orifice plate body (1) along its own axis. An installation groove (13) for inserting the capillary body (2) is provided on one side opening edge of the limiting hole (12). One end of the capillary body (2) is fixedly connected to the inner wall of the limiting hole (12). Its features are, A limiting annular groove (14) is provided at the inner edge of the opening of the installation sink (13). A filter screen (4) is provided on one side of the perforated plate body (1) and is inserted into the limiting annular groove (14). A pressure ring (5) is fixedly embedded on the inner wall of the limiting annular groove (14) and abuts against the side of the filter screen (4) away from the capillary body (2).

2. A throttling device with a capillary tube for a nuclear power plant according to claim 1, characterized in that, A positioning plate (6) is provided above the main body (1) of the perforated plate, and a positioning through hole (61) for the lifting handle (3) to pass through is provided on the positioning plate (6); The main body (1) of the perforated plate is provided with a locking member (7) on the outside. The positioning plate (6) is fixed with a flexible protective curtain (8) on both sides near the two flanges (11). The side of the flexible protective curtain (8) away from the positioning plate (6) is detachably connected to the lower part of the flange (11) through the locking member (7). The flexible protective curtain (8) protects both sides of the limiting hole (12) at this time.

3. A throttling device with a capillary tube for a nuclear power plant according to claim 2, characterized in that, The locking component (7) includes a locking rod (71) located on both sides of the lifting handle (3) and a locking insert (72) fixed on the outer periphery of both ends of the locking rod (71); the flexible protective curtain (8) is fixedly connected to the side of the locking rod (71) away from the positioning plate (6) and away from the locking insert (72); The lower part of the flange (11) has two fixed slots (111) opposite to the locking blocks (72); the two locking blocks (72) on the locking rod (71) are respectively inserted into the two fixed slots (111) on the same side during the packaging and transportation of the throttling device; the locking blocks (72) are provided with elastic snap-fit ​​members (73), and the inner wall of the fixed slots (111) is provided with a first groove (112) for the elastic snap-fit ​​members (73) to be snapped into.

4. A throttling device with a capillary tube for a nuclear power plant according to claim 3, characterized in that, The elastic snap-fit ​​component (73) includes a compression spring (731) and an arc-shaped protrusion (732). The locking insert (72) has a placement groove (721) for inserting the compression spring (731) and the arc-shaped protrusion (732). The compression spring (731) presses one side of the arc-shaped protrusion (732) so that a part of the arc-shaped protrusion (732) protrudes from the opening of the placement groove (721). The outer surface of the protruding part of the arc-shaped protrusion (732) is an arc surface, and the arc length corresponding to the arc surface is a minor arc.

5. A throttling device with a capillary tube for a nuclear power plant according to claim 3, characterized in that, The positioning plate (6) has a positioning groove (62) on the side facing the orifice plate body (1) for the outer edge of the flange (11) and the outer edge of the flange on the external pipe to be inserted together; the lifting handle (3) has a locking notch (31) on the two opposite sides, and the locking notch (31) is located above the positioning plate (6) when the outer edge of the flange (11) is inserted into the positioning groove (62); When the inner edges of the two locking blocks (72) on the two locking rods (71) are engaged in the positioning groove (62) on the outer edge of the flange (11), they can be inserted into the locking notch (31) respectively. At this time, the bottom surface of the locking rod (71) abuts against the top surface of the positioning plate (6), and the sides of the locking blocks (72) on the two locking rods (71) abut against each other. At this time, the flexible protective curtain (8) protects the top surface of the positioning plate (6).

6. A throttling device with a capillary tube for a nuclear power plant according to claim 5, characterized in that, An elastic pad (63) is fixed on the inner wall of the positioning groove (62).

7. A throttling device with a capillary tube for a nuclear power plant according to claim 5, characterized in that, The inner wall of the locking notch (31) is provided with a second groove (311) for the elastic snap-fit ​​(73) to be snapped into.

8. A throttling device with a capillary tube for a nuclear power plant according to claim 3, characterized in that, The lifting handle (3) is provided with a fixing hole (32), which is located above the positioning plate (6) when the outer edge of the flange (11) is engaged with the positioning groove (62). The two locking rods (71) can be installed vertically when the throttling device needs to be moved. The locking blocks (72) at the lower end of the two locking rods (71) can be inserted into the openings on both sides of the fixing hole (32) facing each other. The locking blocks (72) at the upper end of the two locking rods (71) abut against each other and are located above the lifting handle (3).

9. A throttling device with a capillary tube for a nuclear power plant according to claim 8, characterized in that, The inner wall of the fixing hole (32) is provided with a third groove (321) for the elastic snap-fit ​​member (73) to be snapped into.

10. A throttling device with a capillary tube for a nuclear power plant according to claim 8, characterized in that, The fixing hole (32) has guide slopes (322) on both sides of the opening.

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