A special stop valve for lead-based reactors

Abstract

The application provides a special stop valve for lead-based reactor, which comprises a valve body, an inlet cavity and an outlet cavity in the valve body, and a vertical section extending downward from the intersection of the inlet cavity and the outlet cavity; an inlet pipe and an outlet pipe extending downward from the valve body, and the upper ends of the pipes correspond to the inlet cavity and the outlet cavity; a metal bellows arranged in the vertical section, and the outer periphery of the bellows and the inner wall of the valve body form a bellows outer cavity; a drain pipe connecting the bottom of the bellows outer cavity and the inlet pipe; and a valve core arranged at the intersection of the inlet cavity and the outlet cavity. In the open state, the split working medium enters the bottom through the drain pipe, flows into the main stream through the bellows outer cavity, and washes the bellows, so that the light impurity particles are prevented from gathering in the bellows outer cavity. In the stop state, the high pressure at the bottom of the valve core and the low pressure at the top of the valve core form a pressure difference, so that self-tight sealing is realized. In the emptying state, the working medium in the valve body is gravity-drained through the drain pipe, so that residual working medium is prevented. The application solves the problems of impurity gathering and working medium residue, and is suitable for lead-based reactor coolant control.

Description

Technical Field

[0001] This invention relates to the field of coolant fluid control technology in lead-based reactor loops, and more particularly to a shut-off valve specifically designed for lead-based reactors. Background Technology

[0002] Lead-based reactors are one of the main types of advanced nuclear reactors. Low-melting-point lead-based working fluids (lead or lead-bismuth alloys) are typically used as coolants in the loop and are characterized by high temperature, high density, high boiling point, low volatility, easy oxidation, strong corrosion, and strong radiation. The valves that control the lead-based working fluid coolant function have a direct impact on the safe operation of the nuclear reactor.

[0003] Currently, the basic structure of lead-based working fluid gate valves refers to the typical structure of JB / T 11150-2025 "Bellbell-Sealed Steel Gate Valves", with the addition of a working fluid leakage detection interface. After long-term use and verification on a lead-bismuth working fluid experimental device, this type of valve has the following shortcomings:

[0004] Firstly, the service life is relatively short. After hundreds of opening and closing cycles on the lead-bismuth working fluid experimental circuit device, a large number of valves exhibited varying degrees of jamming, and some valves experienced bellows seal failure, leading to leakage of lead-bismuth working fluid coolant. The main reason for the short service life is the accumulation of a large number of large-particle, high-hardness impurities in the troughs of the sealing bellows, causing damage to the bellows during valve opening and closing.

[0005] Secondly, the lead-bismuth working fluid within the valve body cannot be vented, leading to its long-term retention. Due to its extremely low volatility and high boiling point, the retained lead-based working fluid cannot be removed through natural volatilization or evaporation. This long-term retention causes the following problems: First, the retained lead-based working fluid oxidizes into particulate oxides with high hardness, which can damage the valve body's sealing surfaces, leading to internal leakage. Second, the lead-based working fluid has a dissolving and corrosive effect on the valve body material; long-term retention will corrode the valve body's sealing surfaces, affecting the sealing performance. Third, the lead-based coolant used in the reactor has a high level of radiation; the retained lead-based working fluid will significantly increase the valve's radiation level, making it a radiation hotspot and increasing the difficulty of maintenance.

[0006] Therefore, in order to solve the above problems, this invention proposes a shut-off valve specifically for lead-based reactors. Summary of the Invention

[0007] To address the problems of short valve life and long-term retention of lead-based working fluid in the valve body in the existing technology, the present invention provides a shut-off valve specifically for lead-based reactors.

[0008] According to one objective of the present invention, a shut-off valve for lead-based reactors is provided, comprising:

[0009] The valve body has an inlet chamber and an outlet chamber inside, as well as a vertical section extending downward from the junction of the two.

[0010] The inlet pipe and the outlet pipe extend downward from the valve body, and their upper ends are respectively connected to the inlet chamber and the outlet chamber.

[0011] A metal bellows is installed in the vertical section of the valve body, and its outer periphery and the inner wall of the valve body form a bellows outer cavity.

[0012] The drain pipe connects the bottom of the outer cavity of the corrugated pipe to the inlet pipe;

[0013] The valve core is located at the junction of the inlet chamber and the outlet chamber, and has a valve core bottom facing the outer cavity of the bellows and a valve core top facing the outlet chamber.

[0014] In the closed state, the high pressure in the inlet pipe is transmitted through the working fluid and acts on the bottom of the valve core, so that the bottom of the valve core is under high pressure, while the top of the valve core is under low pressure. The pressure difference between the two forms a pressure self-tightening seal for the valve.

[0015] Preferably, the valve core has a hemispherical structure, and all surface edges of the valve core are chamfered.

[0016] Preferably, the valve also includes a main valve stem and a secondary valve stem. The main valve stem is connected to the valve core and extends into the outer cavity of the bellows. The secondary valve stem is located at the upper part of the valve body. The main valve stem and the secondary valve stem are linked together by a gantry.

[0017] Preferably, the drain pipe is inclined, with one end connected to the inlet pipe being lower than the end connected to the outer cavity of the corrugated pipe.

[0018] Preferably, the inlet pipe is connected to the end of the inlet chamber that is away from the outlet chamber, and the outlet pipe is connected to the end of the outlet chamber that is away from the inlet chamber.

[0019] Both the inlet and outlet chambers are inclined, with the connection end between the inlet chamber and the inlet pipe higher than the junction of the inlet chamber and the outlet chamber, and the connection end between the outlet chamber and the outlet pipe lower than the junction of the outlet chamber and the inlet chamber.

[0020] The inclination angles of both the inlet and outlet chambers are not less than 20°.

[0021] Preferably, the base material of the valve body and valve core is 316L stainless steel, and the sealing surface of the valve core is welded or sprayed with Stellite alloy coating.

[0022] The metal corrugated pipe is a multi-layered corrugated pipe made of 316L stainless steel.

[0023] Compared with the prior art, the beneficial effects of the present invention are:

[0024] The metal bellows is installed in the vertical section of the valve body through a T-shaped channel layout, and a drain pipe connected to the inlet pipe is set at the bottom of the outer cavity of the bellows. With the inclined design of the inlet and outlet chambers and the inclined setting of the drain pipe, when the valve needs to be emptied, the lead-based working fluid can be completely emptied from each chamber through the drain pipe and outlet pipe by gravity. This reduces the corrosion of the valve body and sealing surfaces caused by the long-term retention of the lead-based working fluid, and also reduces the radiation generated by the valve due to the retention of the lead-based working fluid.

[0025] The T-shaped channel layout facilitates the passage of impurity particles (mostly iron-based or lead-based oxides, with a density lower than that of the lead-based working fluid) floating on the lead-based working fluid through the valve body, thereby preventing a large number of impurity particles from entering the bellows outer cavity and accumulating. At the same time, a small amount of diverted lead-based working fluid enters the bellows outer cavity through the drain pipe, which flushes and cleans the bellows outer cavity. These multiple aspects work together to prevent impurities from accumulating in the bellows troughs and causing damage to the bellows, thus extending the valve's service life.

[0026] The design utilizes the connection between the inlet pipe, outlet pipe, and the outer cavity of the bellows. In the closed state, the high pressure on the inlet side is transmitted through the lead-based working fluid to the bottom of the valve core, creating a pressure difference with the low pressure on the outlet side, thus achieving a pressure self-tightening seal. This design uses the system's own lead-based working fluid pressure to drive the valve core tightly against the sealing surface. The sealing force automatically increases with increasing system pressure, effectively compensating for wear on the sealing surface and improving sealing reliability.

[0027] The valve core adopts a hemispherical structure and all surface edges are chamfered, which makes the valve core contact with the sealing pair smoothly during the opening and closing process, reduces local stress concentration, eliminates sharp edges, avoids lead-based working fluid from being retained at the edges, thereby reducing the problem of long-term corrosion of the sealing pair by lead-based working fluid, and reduces the probability of impurity particles adhering, improving the cleanliness of the sealing surface.

[0028] The valve body and valve core base material are made of 316L stainless steel. The valve core sealing surface is fused or sprayed with Stellite alloy coating, giving the sealing pair both good resistance to lead-based working fluid corrosion and high-temperature wear resistance, which can significantly extend the service life of the sealing pair under the erosion of high-temperature lead-based working fluids. The metal bellows uses multi-layer 316L stainless steel bellows, which improves the pressure bearing capacity and fatigue life, and has good compatibility with lead-based working fluids, avoiding seal failure due to material corrosion.

[0029] The present invention will be further described below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0030] Figure 1 This is a cross-sectional schematic diagram from one perspective of a lead-based reactor-specific shut-off valve described in this invention.

[0031] Figure 2This is a schematic diagram from another perspective of the lead-based reactor-specific shut-off valve described in this invention. Detailed Implementation

[0032] The following description is intended to provide a detailed account of the invention so that those skilled in the art can implement it. The preferred embodiments described below are merely examples, and other obvious variations will occur to those skilled in the art. The basic principles of the invention defined in the following description can be applied to other embodiments, modifications, improvements, equivalents, and other technical solutions that do not depart from the spirit and scope of the invention.

[0033] Please see Figure 1-2 This invention provides a dedicated shut-off valve for lead-based reactors, aiming to solve problems such as short service life, radiation hotspots caused by lead-based working fluid retention, and corrosion of sealing surfaces in existing lead-based working fluid shut-off valves. Its overall structure includes: a valve body 1, which has an inlet chamber 9 and an outlet chamber 10 inside, and a vertical section extending downward from the junction of the two; an inlet pipe 11 and an outlet pipe 12, extending downward from the valve body 1 respectively, with their upper ends correspondingly connected to the inlet chamber 9 and the outlet chamber 10; a metal bellows 4, disposed within the vertical section of the valve body 1, its outer periphery forming a bellows outer cavity 5 with the inner wall of the valve body 1; a drain pipe 6, connecting the bottom of the bellows outer cavity 5 and the inlet pipe 11; and a valve core 2, disposed at the junction of the inlet chamber 9 and the outlet chamber 10, having a valve core bottom 13 facing the bellows outer cavity 5 and a valve core top 14 facing the outlet chamber 10. The T-shaped channel layout allows the liquid lead-based working fluid to be discharged by gravity from the inlet chamber, outlet chamber, and outer cavity of the bellows when necessary, through the inlet and outlet pipes. This ensures complete emptying of the lead-based working fluid from the valve body, reducing corrosion caused by long-term retention of the working fluid on the valve body and sealing surfaces. Simultaneously, this T-shaped structure prevents impurities (usually iron-based or lead-based oxides) floating on the surface of the liquid lead-based working fluid from accumulating in the outer cavity of the bellows. The bellows is positioned vertically, away from the high-temperature scouring areas of the inlet and outlet chambers, and the drain pipe connects the bottom of the outer cavity to the inlet pipe. This achieves both external cavity emptying and allows a small amount of lead-based working fluid to flow through the outer cavity to flush and clean the bellows when the valve is open, preventing impurities from accumulating in the bellows troughs.

[0034] The improvement of this invention also lies in achieving a pressure self-tightening sealing function for the valve. In the closed state, the working fluid pressure in the inlet pipe 11 is transmitted to the outer cavity 5 of the bellows via the outlet pipe 6 and acts on the bottom 13 of the valve core, causing the bottom 13 of the valve core to bear high pressure, while the top 14 of the valve core is at low pressure or normal pressure. The pressure difference between the two forms a pressure self-tightening seal for the valve. This design utilizes the system's own liquid lead-based working fluid pressure to drive the valve core to tightly adhere to the sealing pair. The sealing force automatically increases with the increase of system pressure, effectively compensating for wear on the sealing surface and improving sealing reliability. It is particularly suitable for high-temperature and high-pressure conditions in lead-based reactor circuits.

[0035] Based on this, valve core 2 has a hemispherical structure, and all edges of the valve core 2 surface are chamfered. The hemispherical shape ensures smooth contact between the valve core and the sealing pair during opening and closing, reducing local stress concentration; the chamfering eliminates sharp edges, preventing liquid lead-based working fluid from accumulating at the edges, thus solving the problem of long-term corrosion of the sealing pair by lead-based working fluid, while also reducing the probability of impurity particles adhering and improving the cleanliness of the sealing surface.

[0036] The shut-off valve is also equipped with a dual-stem linkage structure, including a main stem 3 and a secondary stem 7. The main stem 3 is connected to the valve core 2, and the secondary stem 7 is located on the upper part of the valve body 1. The main stem 3 and the secondary stem 7 are synchronously linked through a gantry 8. This dual-stem linkage design facilitates manual opening and closing of the valve or connection to an external power mechanism.

[0037] The drain pipe 6 is inclined, with one end connected to the inlet pipe 11 lower than the end connected to the outer cavity 5 of the bellows. When necessary, this arrangement ensures that the liquid lead-based working fluid in the outer cavity of the bellows flows completely to the inlet pipe under the action of gravity, achieving complete emptying and avoiding corrosion or thermal stress damage to the bellows caused by residual lead-based working fluid.

[0038] Regarding the layout of the inlet and outlet chambers, the inlet pipe 11 connects to the end of the inlet chamber 9 furthest from the outlet chamber 10, and the outlet pipe 12 connects to the end of the outlet chamber 10 furthest from the inlet chamber 9. Both the inlet chamber 9 and the outlet chamber 10 are inclined, with the connection end of the inlet chamber 9 to the inlet pipe 11 higher than its intersection with the outlet chamber 10, and the connection end of the outlet chamber 10 to the outlet pipe 12 lower than its intersection with the inlet chamber 9. Preferably, the inclination angle of both the inlet chamber 9 and the outlet chamber 10 is not less than 20°. The inclined design allows the lead-based working medium in the outlet chamber to be automatically discharged through the outlet pipe when emptying is required, while the lead-based working medium in the inlet chamber flows to the outer cavity of the corrugated pipe and is discharged together with the lead-based working medium in the outer cavity of the corrugated pipe through the drain pipe. The inclination angle of not less than 20° ensures thorough emptying and prevents the lead-based working medium from remaining in the chamber.

[0039] In terms of material selection, the base material of valve body 1 and valve core 2 is 316L stainless steel, and the sealing surface of valve core 2 is welded or sprayed with Stellite alloy coating. 316L stainless steel has good resistance to lead-based working fluid corrosion and good machinability; Stellite alloy has excellent high-temperature hardness, wear resistance, and resistance to solvent corrosion, which can significantly extend the service life of the sealing pair under the erosion of high-temperature lead-based working fluid. In addition, the metal bellows 4 is a multi-layer bellows made of 316L stainless steel. The multi-layer structure improves the pressure-bearing capacity and fatigue life of the bellows. The 316L stainless steel material has good compatibility with lead-based working fluid, avoiding sealing failure due to material corrosion.

[0040] In use, this shut-off valve is installed on the coolant charging and discharging pipeline of the lead-based reactor loop. When the lead-based coolant working fluid needs to be charged into or discharged from the reactor, the valve is in the open state. High-pressure liquid lead-based working fluid enters the inlet chamber from the inlet pipe, flows through the flow channel between the valve core and the valve body to the outlet chamber, and then flows out of the valve body through the outlet pipe. A small amount of high-pressure liquid lead-based working fluid enters the outer cavity of the bellows through the drain pipe, flushes the bellows, and then merges into the main channel at the junction of the inlet and outlet chambers. When it is necessary to cut off the fluid, the auxiliary valve stem is driven upward by the operating mechanism, which drives the main valve stem and valve core upward via the gantry until the valve core is tightly fitted with the sealing pair. At this time, the inlet pipe side is filled with high-pressure liquid lead-based working fluid, and the pressure is transmitted through the drain pipe to the outer cavity of the bellows and acts on the bottom of the valve core, forming a pressure difference with the low pressure or normal pressure on the outlet chamber side, thus achieving a self-tightening seal. When the valve body needs to be emptied, both the inlet and outlet pipes are under normal pressure. The lead-based working fluid in the outlet chamber is automatically emptied by gravity through the outlet pipe, and the lead-based working fluid in the inlet chamber and the outer cavity of the bellows is automatically emptied by gravity through the outlet pipe and inlet pipe, thus avoiding long-term retention.

[0041] In summary, this lead-based reactor-specific shut-off valve, through its T-shaped channel layout to prevent impurity accumulation, pressure self-tightening seal, inclined venting design, hemispherical chamfered valve core, dual valve stem linkage, and combination of corrosion-resistant and wear-resistant materials, effectively solves the problems of short lifespan, radiation hotspots caused by lead-based working fluid retention, and corrosion of sealing surfaces in existing lead-based working fluid shut-off valves. It significantly improves the reliability and safety of the valve under harsh operating conditions of lead-based reactor coolants.

[0042] The embodiments described above are only used to illustrate the technical ideas and features of the present invention. Their purpose is to enable those skilled in the art to understand the content of the present invention and implement it accordingly. The scope of patent application of the present invention should not be limited by these embodiments. That is, any equivalent changes or modifications made in accordance with the spirit disclosed in the present invention still fall within the patent scope of the present invention.

Claims

1. A shut-off valve specifically for lead-based reactors, characterized in that, include: The valve body (1) has an inlet chamber (9) and an outlet chamber (10) inside, as well as a vertical section extending downward from the junction of the two; The inlet pipe (11) and the outlet pipe (12) extend downward from the valve body (1), and their upper ends are respectively connected to the inlet chamber (9) and the outlet chamber (10). A metal bellows (4) is disposed in the vertical section of the valve body (1), and its outer periphery and the inner wall of the valve body (1) form a bellows outer cavity (5). The drain pipe (6) connects the bottom of the outer cavity (5) of the corrugated pipe and the inlet pipe (11). The valve core (2) is located at the junction of the inlet chamber (9) and the outlet chamber (10), and has a valve core bottom (13) facing the side of the bellows outer cavity (5) and a valve core top (14) facing the side of the outlet chamber (10). In the closed state, the high pressure in the inlet pipe (11) is transmitted through the lead-based working medium and acts on the bottom of the valve core (13), so that the bottom of the valve core (13) is under high pressure, while the top of the valve core (14) is under low pressure. The pressure difference between the two forms a pressure self-tightening seal for the valve.

2. The lead-based reactor-specific shut-off valve according to claim 1, characterized in that, The valve core (2) has a hemispherical structure, and all the edges of the valve core (2) are chamfered.

3. The lead-based reactor-specific shut-off valve according to claim 1, characterized in that, It also includes a main valve stem (3) and a secondary valve stem (7). The main valve stem (3) is connected to the valve core (2) and extends into the outer cavity (5) of the bellows. The secondary valve stem (7) is located on the upper part of the valve body (1). The main valve stem (3) and the secondary valve stem (7) are linked together by a gantry (8).

4. The lead-based reactor-specific shut-off valve according to claim 1, characterized in that, The drain pipe (6) is inclined, with one end of it connected to the inlet pipe (11) being lower than the end of it connected to the outer cavity (5) of the corrugated pipe.

5. The lead-based reactor-specific shut-off valve according to claim 1, characterized in that, The inlet pipe (11) is connected to the end of the inlet chamber (9) away from the outlet chamber (10), and the outlet pipe (12) is connected to the end of the outlet chamber (10) away from the inlet chamber (9); Both the inlet chamber (9) and the outlet chamber (10) are inclined, and the connection end of the inlet chamber (9) and the inlet pipe (11) is higher than the junction end of the inlet chamber (9) and the outlet chamber (10), while the connection end of the outlet chamber (10) and the outlet pipe (12) is lower than the junction end of the outlet chamber (9).

6. The lead-based reactor-specific shut-off valve according to claim 5, characterized in that, The inclination angles of the inlet chamber (9) and the outlet chamber (10) are both not less than 20°.

7. The lead-based reactor-specific shut-off valve according to claim 1, characterized in that, The base material of the valve body (1) and the valve core (2) is 316L stainless steel, and the sealing surface of the valve core (2) is welded or sprayed with Stellite alloy coating.

8. The lead-based reactor-specific shut-off valve according to claim 1, characterized in that, The metal corrugated pipe (4) is a multi-layer corrugated pipe made of 316L stainless steel.

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