A steam-driven auxiliary feed water pump governing valve positioner pilot valve

Abstract

This application provides a pilot valve for a steam-driven auxiliary feedwater pump regulating valve positioner. The pilot valve includes a valve sleeve, a valve core, a ejector pin, a spring, and a valve cover. The valve sleeve connects to the positioner and acts as an internal cylinder for air intake and exhaust. The valve core is installed in the valve sleeve, with its flat end contacting the plug end of the valve sleeve via a spring. The ejector pin is installed below the valve core, with its rounded end contacting the grooved end of the valve core. The valve cover is connected to the side of the valve sleeve opposite to the plug end, away from the valve core. During operation, the ejector pin actuates the pilot valve core, with both ends of the core receiving forces from the ejector pin and the spring, controlling the displacement between the valve core and the valve sleeve. This application addresses the problem of poor speed stability in existing steam-driven auxiliary feedwater pumps by modifying the contact surface between the ejector pin and the valve core from a pointed end to a rounded end, based on the original pilot valve design.

Description

Technical Field

[0001] This application belongs to the field of positioner pilot valve technology, specifically relating to a positioner pilot valve for a steam-driven auxiliary feedwater pump regulating valve. Background Technology

[0002] In nuclear power plants, the auxiliary feedwater system serves as a backup to the normal feedwater system, supplying water to the secondary side of the steam generator in the event of a loss of the main feedwater system. The steam-driven auxiliary feedwater pump, or simply steam auxiliary pump, is one of the important dedicated safety facilities of the Hualong One unit and a crucial nuclear safety barrier ensuring the safe and stable operation of the nuclear power unit.

[0003] However, existing steam-driven auxiliary feedwater pumps, such as the Shanghai Apollo steam-driven auxiliary feedwater pump, have the problem of large speed fluctuations, resulting in poor speed stability of the steam-driven auxiliary feedwater pump. This can even cause the main line plan and testing of the nuclear power unit to be hindered, which will have a great impact on the project progress. Summary of the Invention

[0004] In view of this, the embodiments of this application are committed to providing a pilot valve for a steam-driven auxiliary feedwater pump regulating valve positioner. By modifying the plane in contact between the pin and the valve core from a pointed end to a rounded end on the basis of the original pilot valve, the problem of poor speed stability of the existing steam-driven auxiliary feedwater pump is solved.

[0005] This application provides a pilot valve for a steam-driven auxiliary feedwater pump regulating valve positioner. The pilot valve includes a valve sleeve, a valve core, a ejector pin, a spring, and a valve cover. The valve sleeve connects to the positioner and acts as an internal cylinder for air intake and exhaust. The valve core is installed in the valve sleeve, with its flat end contacting the plug end of the valve sleeve via a spring. The ejector pin is installed below the valve core, with its rounded end contacting the grooved end of the valve core. The valve cover is connected to the side of the valve sleeve opposite to the plug end, away from the valve core. During operation, the ejector pin actuates the pilot valve core, with both ends of the valve core receiving forces from the ejector pin and the spring, controlling the displacement between the valve core and the valve sleeve.

[0006] In one specific embodiment of this application, the surface of the valve core is plated with hard chrome.

[0007] In one specific embodiment of this application, the valve core has various sizes to be adapted to different pneumatic auxiliary feedwater pumps.

[0008] In one specific embodiment of this application, a stepped platform is provided at the lowest position inside the valve sleeve, and the stepped platform is used to place the ejector pin.

[0009] In one specific embodiment of this application, the ejector pin is connected to the lowest groove of the valve core in a metal-to-metal manner. The lowest part of the ejector pin is used to place directly on the positioner diaphragm. The position of the diaphragm changes due to the change in the positioner feedback spring, which in turn indirectly drives the position of the ejector pin to change.

[0010] In one specific embodiment of this application, the valve core, as an important control component of the internal slide valve, is moved by the change of the position of the ejector pin, thereby changing the intake and exhaust volume of the internal cylinder to achieve overall control of the regulating air circuit.

[0011] In one specific embodiment of this application, the spring is placed directly on the uppermost plane of the valve core. When the valve core moves, the spring adjusts and buffers the position of the valve core by changing the amount of compression.

[0012] In one specific embodiment of this application, the valve cover is connected to the valve sleeve, and the exhaust gas discharged from the internal cylinder due to insufficient sealing is discharged through the round hole above the valve cover.

[0013] In one specific embodiment of this application, the valve sleeve is fixedly connected to the positioner via external threads. The valve cover is connected to the valve sleeve via external threads.

[0014] In one specific embodiment of this application, the valve sleeve fixes the rubber sealing ring through three sealing ring grooves.

[0015] The beneficial effects of this technical solution are as follows: By optimizing the contact plane between the ejector pin and the valve core, and changing the ejector pin's tip from a pointed end to a rounded end, and the bottom of the ejector pin from an inverted cone shape to a hemispherical shape, the problem of ejector pin tilting and jamming during operation is reduced, thus improving the stability of the pilot valve of the steam-driven auxiliary feedwater pump regulating valve positioner. Furthermore, by adjusting the outer diameter of the valve core, the gap between the valve core and the inner wall of the valve sleeve is reduced, improving the smoothness of the pilot valve's operation and thus reducing speed fluctuations, thereby improving the speed stability of the steam-driven auxiliary feedwater pump. This invention is based on domestically produced pneumatic control equipment for steam-driven auxiliary pumps, and creatively optimizes the original pilot valve structure. It has been applied in the field, and the speed fluctuation of domestically produced steam-driven auxiliary pumps has been significantly reduced. The embodiments of this application greatly reduce the time for hot testing of steam auxiliary pumps during major overhauls, saving overhaul man-hours. Taking the Hualong One unit as an example, after using the steam-driven auxiliary feedwater pump regulating valve positioner and pilot valve provided in the embodiments of this application, from 2020 to the present, during the hot testing of Unit 6, and during the daily and major overhauls of Units 5 and 6, all related tests of the steam auxiliary pump were successful on the first attempt, and the speed error was small, reaching the leading level in the industry. Attached Figure Description

[0016] Figure 1 The figure shown is a cross-sectional schematic diagram of a pilot valve for a steam-driven auxiliary feedwater pump regulating valve positioner provided in an embodiment of this application.

[0017] Figure 2 As shown Figure 1 The diagram shows a three-dimensional structural schematic of the valve sleeve in the pilot valve of a steam-driven auxiliary feedwater pump regulating valve positioner.

[0018] Figure 3 As shown Figure 2 The diagram shows the front view of the valve sleeve.

[0019] Figure 4 As shown Figure 2 The diagram shows a cross-sectional view of the valve sleeve.

[0020] Figure 5 As shown Figure 2 The diagram shows a rear view of the valve sleeve.

[0021] Figure 6 As shown Figure 1 The diagram shows a three-dimensional structural schematic of the valve core in the pilot valve of a steam-driven auxiliary feedwater pump regulating valve positioner.

[0022] Figure 7 As shown Figure 6 The diagram shows a front view of the valve core.

[0023] Figure 8 As shown Figure 6 The diagram shows a cross-sectional view of the valve core.

[0024] Figure 9 As shown Figure 6 The diagram shows a side view of the valve core.

[0025] Figure 10 As shown Figure 1 The diagram shows a three-dimensional structure of the ejector pin in the pilot valve of a steam-driven auxiliary feedwater pump regulating valve positioner.

[0026] Figure 11 As shown Figure 10 The diagram shows the front view of the thimble. Detailed Implementation

[0027] From February 18 to March 1, 2020, Unit 5 of the Fuqing Nuclear Power Plant was in the hot-state testing phase. During the commissioning phase, operational tests were conducted on the Shanghai Apollo steam-driven auxiliary feedwater pumps 5TFA003PO and 5TFA004PO. The pump speed fluctuations exceeded the acceptance criteria, leading to test failure and disrupting the unit's main schedule and testing, significantly impacting the project's progress. This defect was identified as one of the company's "Top Ten Defects" of concern.

[0028] Through continuous testing and discussion, it was found that the H-6200 model positioner pilot valve in the pneumatic control system has problems such as poor manufacturing process, low machining accuracy, and defects in functional principle. As a result, the positioner pilot valve of the steam auxiliary pump regulating valve does not meet the requirements for stable operation, thus causing the above-mentioned defects.

[0029] To address at least one of the aforementioned problems, embodiments of this application provide a pilot valve for a steam-driven auxiliary feedwater pump regulating valve positioner. The technical solutions in these embodiments will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of this application.

[0030] At least one embodiment of this application provides a pilot valve for a steam-driven auxiliary feedwater pump regulating valve positioner. (See reference...) Figures 1 to 11 The pilot valve of the steam-driven auxiliary feedwater pump regulating valve positioner includes a valve sleeve 1, a valve core 2, a ejector pin 3, a spring 4, and a valve cover 5. The valve sleeve 1 connects to the positioner and acts as an internal cylinder for air intake and exhaust. The valve core 2 is installed in the valve sleeve 1, with its flat end contacting the plug end of the valve sleeve 1 via the spring 4. The ejector pin 3 is installed below the valve core 2, with its rounded end contacting the grooved end of the valve core 2. The valve cover 5 is connected to the side of the valve sleeve 1 opposite to the plug end and the valve core 2. During operation, the ejector pin 3 actuates, driving the pilot valve core 2. The valve core 2 receives forces from the ejector pin 3 and the spring 4 at both ends, controlling the displacement between the valve core 2 and the valve sleeve 1.

[0031] It should be noted that the pilot valve of the positioner for the steam-driven auxiliary feedwater pump is installed inside the positioner and is used to control the air supply entering the valve diaphragm. The positioner can be the H-6200 model positioner from Shanghai Automation Instrumentation Factory No. 7. The steam-driven auxiliary feedwater pump can be simply referred to as the steam-assisted pump.

[0032] The specific implementation method is as follows: The feedback cam below the positioner receives the control air pressure output by the electrical converter. The feedback cam moves according to the control air pressure, and drives the ejector pin 3 to move through the spring device below the positioner. The movement of the ejector pin 3 drives the valve core 2 of the pilot valve to move. The two ends of the valve core 2 receive the force of the ejector pin 3 and the spring 4 respectively, controlling the displacement between the valve core 2 and the valve sleeve 1, thereby controlling the air source entering the valve diaphragm and completing the process of controlling the opening of the valve by electrical signal.

[0033] According to the technical solution provided in this application, by optimizing the contact plane between the ejector pin 3 and the valve core 2, the ejector pin 3 is changed from a pointed end to a rounded end, and the bottom of the ejector pin 3 is changed from an inverted cone shape to a hemispherical shape, based on the original pilot valve. This reduces the problem of ejector pin tilting and jamming during the operation of the valve core 2 and ejector pin 3, and improves the stability of the pilot valve of the steam-driven auxiliary feedwater pump regulating valve positioner. By adjusting the outer diameter of the valve core 2, the gap between the valve core 2 and the inner wall of the valve sleeve is reduced, improving the smoothness of the pilot valve operation of the steam-driven auxiliary feedwater pump regulating valve positioner, thereby improving the response accuracy of the control system, reducing the speed fluctuation amplitude, and improving the speed stability of the steam-driven auxiliary feedwater pump. This application is based on the development of domestically produced pneumatic control equipment for steam-driven auxiliary pumps. It creatively optimizes the original pilot valve structure and has been applied in the field, significantly reducing the speed fluctuation of domestically produced steam-driven auxiliary pumps. The embodiments of this application greatly reduce the time for hot testing of steam auxiliary pumps during major overhauls, saving overhaul man-hours. Taking the Hualong One unit as an example, after using the steam-driven auxiliary feedwater pump regulating valve positioner and pilot valve provided in the embodiments of this application, the relevant tests of the steam auxiliary pump were all successful on the first attempt during the hot test of Unit 6, the 501 major overhaul, the 601 major overhaul, and the 502 major overhaul, and the speed error was small, which has entered the leading level in the same industry.

[0034] In at least one embodiment of this application, the surface of the valve core 2 is plated with hard chrome. This improves the wear resistance of the valve core and reduces wear when the auxiliary pump regulating valve is activated.

[0035] The existing pilot valve's control accuracy and sensitivity for the regulating valve are far from meeting the requirements for stable operation of the steam-driven auxiliary feedwater pump. The pilot valve of the steam-driven auxiliary feedwater pump regulating valve positioner provided in this application improves the accuracy and sensitivity of the pilot valve's control over the regulating valve through improvements such as optimizing the tip 3 from a pointed to a rounded shape, optimizing the bottom of the tip 3 from an inverted cone to a hemispherical shape, and hard chrome plating on the valve core 2 and adjusting the outer diameter. This steam-driven auxiliary feedwater pump regulating valve positioner pilot valve has been used in four units of this power plant and three nuclear power plants in the same industry, and is perfectly compatible with domestic steam-driven auxiliary pump control systems. In on-site testing of the steam-driven auxiliary pump using this new pilot valve at the nuclear power plant, the speed error was consistently much smaller than the required ±80 rpm.

[0036] In at least one embodiment of this application, the valve core 2 has multiple sizes to adapt to different steam-driven auxiliary feedwater pumps. Thus, the outer diameter of the corresponding valve core 2 can be adjusted according to the characteristics of each auxiliary pump to perfectly adapt to the stable operation requirements of different auxiliary pumps.

[0037] For example, based on the characteristics of the Hualong One auxiliary pump, adaptive optimization can be carried out to perfectly match the operational requirements of the Fuqing Hualong One auxiliary pump.

[0038] In at least one embodiment of this application, a stepped platform is provided at the lowest position inside the valve sleeve 1, and the stepped platform is used to place the ejector pin 3.

[0039] In at least one embodiment of this application, the ejector pin 3 is connected to the lowermost groove of the valve core 2 in a metal-to-metal manner. The lowermost part of the ejector pin 3 is used to be placed directly on the positioner diaphragm. The position of the diaphragm is changed by the change in the positioner feedback spring, which indirectly drives the position of the ejector pin 3 to change.

[0040] In at least one embodiment of this application, the valve core 2, as an important control component of the internal slide valve, is pushed by the change of the position of the ejector pin 3 to change the intake and exhaust volume of the internal cylinder, thereby achieving overall control of the regulating air path.

[0041] In at least one embodiment of this application, the spring 4 is placed directly on the uppermost plane of the valve core 2. When the valve core 2 moves, the spring 4 adjusts and buffers the position of the valve core 2 by changing the amount of compression.

[0042] In at least one embodiment of this application, the valve cover 5 is connected to the valve sleeve 1, and the exhaust gas discharged from the internal cylinder due to insufficient sealing is discharged through the round hole above the valve cover 5.

[0043] In at least one embodiment of this application, the valve sleeve 1 is fixedly connected to the positioner via an external thread. The valve cover 5 is connected to the valve sleeve 1 via an external thread.

[0044] In at least one embodiment of this application, the valve sleeve 1 secures the rubber sealing ring via three sealing ring grooves. This improves the sealing performance of the internal slide valve cylinder.

[0045] In at least one embodiment of this application, the plug end of the valve sleeve 1 is a hexagonal fastening plug end.

[0046] It should be noted that the combination of the technical features in the embodiments of this application is not limited to the combination methods described in the embodiments of this application or the combination methods described in specific embodiments. All technical features described in this application can be freely combined or combined in any way, unless they contradict each other.

[0047] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Any modifications or equivalent substitutions made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A pilot valve for a steam-driven auxiliary feedwater pump regulating valve positioner, characterized in that, Includes valve sleeve, valve core, ejector pin, spring, and valve cover. The valve sleeve connects to the positioner and acts as an internal cylinder for air intake and exhaust. The valve core is installed in the valve sleeve, with its flat end contacting the end cap of the valve sleeve via a spring. The ejector pin is installed below the valve core, with its rounded end contacting the grooved end of the valve core. The valve cover is connected to the side of the valve sleeve opposite to the end cap, away from the valve core. A stepped platform is located at the bottom of the valve sleeve to hold the ejector pin. The ejector pin connects to the bottom groove of the valve core with its metal surface facing the metal surface. The bottom of the ejector pin rests directly on the positioner diaphragm. Changes in the positioner's feedback spring cause changes in the diaphragm's position, indirectly changing the position of the ejector pin. During operation, the movement of the ejector pin drives the movement of the pilot valve core. The two ends of the valve core receive the forces of the ejector pin and the spring respectively, controlling the displacement between the valve core and the valve sleeve.

2. The pilot valve of the steam-driven auxiliary feedwater pump regulating valve positioner according to claim 1, characterized in that, The valve core is plated with hard chrome.

3. The pilot valve of the steam-driven auxiliary feedwater pump regulating valve positioner according to claim 1, characterized in that, The valve core is available in various sizes to be compatible with different pneumatic auxiliary feedwater pumps.

4. The pilot valve of the steam-driven auxiliary feedwater pump regulating valve positioner according to claim 1, characterized in that, As an important control component of the internal slide valve, the valve core moves by changing the position of the ejector pin, thereby changing the intake and exhaust volume of the internal cylinder to achieve overall control of the air circuit.

5. The pilot valve of the steam-driven auxiliary feedwater pump regulating valve positioner according to claim 1, characterized in that, The spring is placed directly on the uppermost plane of the valve core. When the valve core moves, the spring adjusts and buffers the position of the valve core by changing its compression.

6. The pilot valve of the steam-driven auxiliary feedwater pump regulating valve positioner according to claim 1, characterized in that, The valve cover is connected to the valve sleeve, and the exhaust gas discharged from the internal cylinder due to insufficient sealing is discharged through the round hole on the top of the valve cover.

7. The pilot valve of the steam-driven auxiliary feedwater pump regulating valve positioner according to claim 1, characterized in that, The valve sleeve is fixedly connected to the positioner via external threads, and the valve cover is connected to the valve sleeve via external threads.

8. The pilot valve of the steam-driven auxiliary feedwater pump regulating valve positioner according to any one of claims 1 to 7, characterized in that, The valve sleeve secures the rubber sealing ring through three sealing ring grooves.

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