Three-way valve sleeve structure for accurate flow ratio of boron water replenishment of nuclear reactor

Abstract

The invention belongs to the technical field of nuclear reactor boron water flow ratio control, provides a three-way valve sleeve structure for accurate flow ratio of nuclear reactor boron water replenishment and a use method thereof, and realizes accurate flow ratio of nuclear reactor boron water replenishment of a third-generation nuclear power plant. The three-way valve sleeve structure comprises a valve body, a lower sleeve is installed in the valve body, an upper sleeve is installed on the lower sleeve, and the lower sleeve is provided with a lower sleeve window; the valve element penetrates through the lower sleeve and the upper sleeve to be arranged and slides up and down in the valve body, and a window of the lower sleeve is divided into two throttling windows according to the proportion. The guide device has the advantages of being good in guide performance, vibration resistance and abrasion resistance, high in fluid pressure and flow fluctuation resistance and high in fluid pressure and flow fluctuation resistance.

Description

Technical Field

[0001] The present application belongs to the technical field of boron water flow ratio control for nuclear reactors, and in particular to a three-way valve sleeve structure for accurate flow ratio of boron water supply for nuclear reactors. Background Art

[0002] The boric acid proportioning loop is an important part of the chemical and volume control system of a nuclear power plant, which directly affects the core reactivity control and the pressurizer liquid level control. The main function of this loop is to mix desalted water and boric acid (2.5%) to produce a boric acid solution with a target concentration of 0ppm to 4375mm according to the setting, which is used to add boron-containing water to the primary loop, core water supply tank, injection tank and spent pool. Compared with the second-generation improved unit (M310), the boric acid proportioning system of the third-generation unit (AP1000) is simple in structure, mainly consisting of a water supply pump, a pneumatic three-way valve, a desalted water pressure reducing valve, a boric acid storage tank and other equipment.

[0003] Since the commissioning of the boric acid proportioning circuit of the third-generation nuclear electrochemical and volumetric control system began in 2016, in manual mixing mode and automatic water replenishment mode, the boric acid solution concentration often deviates too much from the target value, triggering the boron deviation alarm, and even causing the water replenishment operation to terminate. The main control room has issued status reports many times, reporting that the boric acid proportioning circuit is prone to triggering the boron deviation alarm. The third-generation nuclear power unit has included this problem in the list of top ten problems, organized personnel to analyze and test it many times, and optimized the instrumentation logic and parameter settings, but the problem has not been completely solved. Summary of the invention

[0004] The purpose of the present application is to overcome the defects of the prior art, thereby providing a three-way valve sleeve structure with precise flow ratio of boron water replenishment for a nuclear reactor, so as to achieve precise flow ratio of boron water replenishment for a nuclear reactor of a third-generation nuclear power plant.

[0005] In order to achieve the above objectives, this application provides the following technical solutions:

[0006] In the first aspect, the present application provides a three-way valve sleeve structure for precise flow ratio matching of boron water supply to a nuclear reactor, comprising a valve body, a lower sleeve installed in the valve body, an upper sleeve installed on the lower sleeve, and the lower sleeve having a lower sleeve window; a valve core is arranged through the lower sleeve and the upper sleeve and slides up and down in the valve body, dividing the lower sleeve window into two throttling windows in proportion.

[0007] In some embodiments, the lower sleeve window is a star-shaped structure.

[0008] In some embodiments, the upper sleeve has an upper sleeve window.

[0009] In some embodiments, the upper sleeve window includes a plurality of symmetrically arranged windows.

[0010] In some embodiments, a groove is provided on the outer wall of the upper sleeve, and an O-ring is provided in the groove.

[0011] In some embodiments, the lower sleeve and the upper sleeve both adopt a sleeve and valve seat integrated structure.

[0012] In some embodiments, the sealing surfaces cooperating with the valve core are respectively arranged on the inner sides of the lower ends of the upper sleeve and the lower sleeve.

[0013] In some embodiments, the valve core is a plunger valve core.

[0014] In some embodiments, a sealing ring capable of axial sliding and bidirectional sealing is provided between the lower sleeve and the valve body.

[0015] In a second aspect, the present application provides a method for using a three-way valve sleeve structure for accurately matching the flow rate of boron water supply to a nuclear reactor, comprising:

[0016] The valve core moves up and down between the upper sleeve and the inner ring of the lower sleeve, dividing the lower sleeve window into two throttling windows with different flow resistance coefficients;

[0017] In the initial state, the valve core contacts the sealing surface inside the lower sleeve. When the valve is in the closed state, the fluid medium at the second inlet is cut off, and the fluid medium enters the lower flow channel from the first inlet through the upper throttling window of the lower sleeve. At this time, the upper throttling window of the lower sleeve has a flow throttling window with a minimum flow resistance coefficient area;

[0018] The valve core moves upward, dividing the window of the lower sleeve into two proportional throttling windows with different flow resistance coefficients, and controlling two media at the same time. At this time, the flow resistance coefficient of the lower throttling window of the lower sleeve decreases, and the flow resistance coefficient of the upper throttling window increases;

[0019] When the valve is in the fully open state, the valve core contacts the sealing surface inside the upper sleeve, the fluid medium at the inlet is cut off, and the fluid medium enters the lower flow channel from the inlet through the lower throttling window of the lower sleeve. At this time, the lower throttling window of the lower sleeve has a flow throttling window with a minimum flow resistance coefficient area, realizing the function of flow ratio.

[0020] Compared with the prior art, the three-way valve sleeve structure with precise flow ratio for boron water replenishment in nuclear reactor provided by the present application has the following beneficial effects:

[0021] 1. It has the advantages of good guiding performance, vibration resistance and wear resistance;

[0022] 2. Strong ability to resist fluid pressure and flow fluctuations;

[0023] 3. It realizes the ratio adjustment of wide range concentration with high adjustment accuracy, especially the precise control performance at ultra-low flow rate. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the technical solution of the present application, the following is a brief introduction to the drawings required for the technical description.

[0025] Figure 1 A schematic diagram of a three-way valve sleeve structure for accurate flow ratio matching of boron water supply to a nuclear reactor provided in this application;

[0026] Figure 2 for Figure 1 Enlarged view of point A in the middle.

[0027] Description of reference numerals:

[0028] 1. Valve body; 2. Lower sleeve; 3. Valve core; 4. O-ring; 5. Upper sleeve. DETAILED DESCRIPTION

[0029] The following is further explained in detail through specific implementation methods.

[0030] By conducting simulation tests on various factors that affect concentration deviation and testing the mixing conditions among the water-making pressure reducing valve, pneumatic three-way valve and concentrated boric acid solution, it was found that the fundamental cause of the deviation in boric acid concentration ratio is the valve seat, valve core and valve cage structure in the traditional three-way regulating valve technology, which can only achieve the function of mixing two-way media but cannot achieve the function of accurate ratio of medium flow. The previous inferred reasons include poor performance of the pressure reducing valve and low instrument accuracy. Through simulation calculation analysis, several factors that may have a greater impact were inferred, and then these influencing factors were verified by building a test bench.

[0031] Therefore, the present application provides a three-way valve sleeve structure for precise flow ratio matching of boron water supply to a nuclear reactor (hereinafter referred to as the three-way valve sleeve structure). On the basis of a traditional three-way valve, the internal structure of the valve body is modified, the valve seat and the cylindrical thin-walled valve core are removed, and an upper sleeve 5, a lower sleeve 2 and a plunger valve core (valve core 3) are added.

[0032] It should be noted that the precise flow ratio referred to in this application is: the flow range of boric acid and desalted water is 0-40m 3 / h, when the concentration of concentrated boric acid solution is 4000ppm, after the system sets the boric acid flow value and concentration value, the structure can automatically adjust the actual boric acid concentration of the system to a deviation of less than 87.5ppm from the set boric acid concentration within 2 minutes, and adjust the flow rate to near the set value, especially when the set boric acid flow rate is less than 5m 3 When the flow rate is small and the boric acid concentration is lower than 300ppm, the actual boric acid concentration can still be accurately adjusted to the above deviation range.

[0033] like Figure 1 and Figure 2 As shown, the three-way valve sleeve structure includes a valve body 1, a lower sleeve 2, a valve core 3, an O-ring 4 and an upper sleeve 5. The upper sleeve 5 and the lower sleeve 2 are installed in the valve body 1, and the upper sleeve 5 is sleeved on the lower sleeve 2. The outer wall of the upper sleeve 5 is provided with a groove for accommodating the O-ring 4. The upper sleeve 5 and the lower sleeve 2 both adopt a valve seat sleeve integrated structure and are provided with a window. The sleeve and the valve seat are set as a whole, which reduces the number of parts and components, reduces the risk of leakage and failure caused by loose connection or misalignment of components, and helps to achieve more accurate flow control. The valve core 3 passes through the upper sleeve 5 and the lower sleeve 2.

[0034] like Figure 1 As shown, a ring-shaped groove is provided on the outer wall of the upper sleeve 5, and the groove accommodates the O-ring 4. The outer side of the O-ring 4 is in close contact with the inner wall of the valve body 1 to form a static sealing structure. The static sealing structure of the O-ring 4 replaces the function of the original valve seat sealing gasket. The O-ring 4 prevents the fluid medium from flowing into the lower flow channel through the matching surface of the valve body 1 and the upper sleeve 5.

[0035] The upper sleeve window includes a plurality of symmetrically arranged windows (hollow structures), a total of 4 windows, for the entry and exit of two-way media. The upper sleeve window is similar to 4 rectangular symmetrical windows.

[0036] The window shape of the lower sleeve window is, for example, a star-shaped structure (hollow shape). The star-shaped structure is designed to achieve the purpose of regulating the flow rate by changing the size of the sleeve window hole area. This structural design can greatly reduce the impact of changes in fluid flow on the flow regulation function of the valve. This can solve the problem that the boric acid concentration cannot be automatically proportioned within the specified time under low flow and low concentration conditions.

[0037] The upper sleeve 5 and the lower sleeve 2 both adopt an integrated sleeve and valve seat structure, and the sleeve and the valve seat are set as a whole, which reduces the number of parts and reduces the risk of leakage and failure caused by loose connection or misalignment of parts, which helps to achieve more accurate flow control. The sealing surface that cooperates with the valve core 3 is set on the inner side of the lower end of the upper sleeve 5 and the lower sleeve 2 respectively.

[0038] The valve core 3 passes through the upper sleeve 5 and the lower sleeve 2, and moves vertically up and down, dividing the lower sleeve window into two throttling windows in proportion.

[0039] The specific ratio is calculated according to the actual working conditions. For different boric acid concentrations, the flow rates of desalted water and boric acid solution will have a corresponding ratio. Combined with some typical and commonly used working conditions, the corresponding flow ratio is calculated to form the flow characteristic curve of the three-way valve. Different positions on the profile of the two throttling windows correspond to different flow ratios. The up and down movement of the plunger in the lower sleeve causes the flow window to change, thereby achieving precise adjustment of the boric acid ratio concentration.

[0040] By vertically moving the valve core 3 up and down, the lower sleeve window is divided into two throttling windows with different flow resistance coefficients, and the flow sizes of the two media are controlled at the same time, which can solve the problem that the three-way valve in the prior art cannot realize the flow ratio function.

[0041] Preferably, the valve core 3 is a plunger valve core, and the advantages of using a plunger valve core include:

[0042] 1. The plunger and valve seat are tightly matched to achieve precise flow regulation;

[0043] 2. The movement trajectory of the plunger is relatively stable, without shaking or offset, thus ensuring the accuracy and repeatability of the adjustment;

[0044] 3. The metal-to-metal seal between the plunger and the valve seat can effectively prevent fluid leakage;

[0045] 4. The sealing surface is processed with high precision to ensure long-term sealing effect;

[0046] 5. The plunger is made of high-strength metal material with high hardness and wear resistance. It can maintain a long service life under frequent switching operations and fluid flushing;

[0047] 6. For fluids with particulate impurities, the plunger structure can better resist wear and reduce leakage caused by wear;

[0048] 7. The application range is wide, from fine adjustment of small diameter to high flow control of large diameter, this structure can be used.

[0049] The specific usage process of this application is:

[0050] The valve core 3 moves vertically up and down between the upper sleeve 5 and the inner ring of the lower sleeve 2, dividing the lower sleeve window into two throttling windows with different flow resistance coefficients; in the initial state, the valve core 3 contacts the inner sealing surface of the lower sleeve 2, and when the valve is in a closed state, the fluid medium at the second inlet is cut off, and the fluid medium enters the lower flow channel from the first inlet through the upper throttling window of the lower sleeve 2, and at this time, the upper throttling window of the lower sleeve 2 has a flow throttling window with a minimum flow resistance coefficient area; when the valve core 3 moves upward, the window of the lower sleeve 2 is divided into two proportional throttling windows with different flow resistance coefficients, and the two media are controlled at the same time, and at this time, the flow resistance coefficient of the lower throttling window of the lower sleeve 2 is reduced, and the flow resistance coefficient of the upper throttling window is increased; when the valve is in a fully open state, the valve core 3 contacts the inner sealing surface of the upper sleeve 5, the fluid medium at the first inlet is cut off, and the fluid medium enters the lower flow channel from the first inlet through the lower throttling window of the lower sleeve 2, and at this time, the lower throttling window of the lower sleeve 2 has a flow throttling window with a minimum flow resistance coefficient area; the function of flow ratio is realized.

[0051] The above description is only a specific implementation manner of the present application, but the protection scope of the present application is not limited thereto. Any changes or substitutions that can be easily conceived by any technician familiar with the technical field within the technical scope disclosed in the present application should be covered within the protection scope of the present application.

Claims

1. A three-way valve sleeve structure for accurate flow ratio matching of boron water supply to a nuclear reactor, comprising a valve body (1), characterized in that: A lower sleeve (2) is installed in the valve body (1), an upper sleeve (5) is installed on the lower sleeve (2), and the lower sleeve (2) has a lower sleeve window; a valve core (3) is arranged through the lower sleeve (2) and the upper sleeve (5) and slides up and down in the valve body (1), dividing the lower sleeve window into two throttling windows in proportion.

2. The three-way valve sleeve structure for accurate flow ratio matching of boron water supply to a nuclear reactor according to claim 1 is characterized in that: The lower sleeve window is a star-shaped structure.

3. The three-way valve sleeve structure for accurate flow ratio matching of boron water supply to a nuclear reactor according to claim 1 is characterized in that: The upper sleeve (5) has an upper sleeve window.

4. The three-way valve sleeve structure for accurate flow ratio matching of boron water supply to a nuclear reactor according to claim 3 is characterized in that: The upper sleeve window includes a plurality of symmetrically arranged windows.

5. The three-way valve sleeve structure for accurate flow ratio matching of boron water supply to a nuclear reactor according to claim 1, characterized in that: A groove is provided on the outer wall of the upper sleeve (5), and an O-ring (4) is provided in the groove.

6. The three-way valve sleeve structure for accurate flow ratio matching of boron water supply to a nuclear reactor according to claim 1, characterized in that: The lower sleeve (2) and the upper sleeve (5) both adopt a sleeve and valve seat integrated structure.

7. The three-way valve sleeve structure for accurate flow ratio matching of boron water supply to a nuclear reactor according to claim 1 or 6, characterized in that: The sealing surfaces cooperating with the valve core (3) are respectively arranged on the inner sides of the lower ends of the upper sleeve (5) and the lower sleeve (2).

8. The three-way valve sleeve structure for accurate flow ratio matching of boron water supply to a nuclear reactor according to claim 1, characterized in that: The valve core (3) is a plunger type valve core.

9. The three-way valve sleeve structure for accurate flow ratio matching of boron water supply to a nuclear reactor according to claim 1, characterized in that: A sealing ring capable of axial sliding and bidirectional sealing is provided between the lower sleeve (2) and the valve body (1).

10. A method for using a three-way valve sleeve structure for accurate flow ratio matching of boron water supply to a nuclear reactor, characterized in that: include: The valve core (3) moves up and down between the upper sleeve (5) and the inner ring of the lower sleeve (2), dividing the lower sleeve window into two throttling windows with different flow resistance coefficients; In the initial state, the valve core (3) contacts the inner sealing surface of the lower sleeve (2). When the valve is in the closed state, the fluid medium at the second inlet is cut off, and the fluid medium enters the lower flow channel from the first inlet through the upper throttling window of the lower sleeve (2). At this time, the upper throttling window of the lower sleeve (2) has a flow throttling window with a minimum flow resistance coefficient area; The valve core (3) moves upward, dividing the window of the lower sleeve (2) into two proportional throttling windows with different flow resistance coefficients, and controlling two mediums at the same time. At this time, the flow resistance coefficient of the lower throttling window of the lower sleeve (2) decreases, and the flow resistance coefficient of the upper throttling window increases; When the valve is in the fully open state, the valve core (3) contacts the inner sealing surface of the upper sleeve (5), the fluid medium at the inlet is cut off, and the fluid medium enters the lower flow channel from the inlet through the lower throttling window of the lower sleeve (2). At this time, the lower throttling window of the lower sleeve (2) has a flow throttling window with a minimum flow resistance coefficient area, thereby realizing the function of flow ratio matching.

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