Corrosion product centrifugal separation device and method for spent fuel pool

Abstract

The invention provides a corrosion product centrifugal separation device and method for a spent fuel pool, and belongs to the technical field of spent fuel pool purification systems.The corrosion product centrifugal separation device comprises a solid collecting tank and a Venturi tube, a pore plate is installed in a cylindrical section of the upper portion of the solid collecting tank, and the bottom of the solid collecting tank is connected with an inlet pipe; a cyclone impeller is mounted in the inlet pipe, a separation section is arranged at the top of the inlet pipe, a cylindrical guide plate is externally connected to the separation section, the separation section is connected with a connecting pipe, a recovery impeller is mounted in the connecting pipe, the connecting pipe is connected with a Venturi pipe, and the Venturi pipe is connected with an outlet. Based on the obvious density difference of the solid phase and the liquid phase, a rotational flow field can be generated by pool water through the rotational flow impeller, solid-liquid separation is conducted on substances with different specific gravities, corrosion products are efficiently removed through gravity settling, the purpose of purifying the spent fuel pool is achieved, and compatibility with an existing circulating system of the spent fuel pool is high.

Description

Technical Field

[0001] This invention belongs to the technical field of spent fuel water tank purification systems, specifically relating to a centrifugal separation device and method for corrosion products in spent fuel water tanks. Background Technology

[0002] Currently, the ferritic-martensitic stainless steel cladding material in the spent fuel pool of fast reactor units is severely corroded. However, the existing pool water purification system has insufficient treatment capacity, resulting in a large amount of corrosion products in the pool water, which may lead to seriously excessive levels of radioactivity in the pool.

[0003] Existing spent fuel water purification systems typically employ mechanical filters. These filters work by using micropores in the filter element to trap solid particles in the water, achieving purification and separation. However, filters have several drawbacks: firstly, they are prone to forming a filter cake layer, causing filter element blockage, which leads to increased pressure drop and poor purification efficiency; secondly, the core components have a limited lifespan, requiring frequent filter element replacements. This increases the time workers spend in high-radiation environments, raising operational risks and increasing the burden of radioactive waste disposal, thus increasing economic costs.

[0004] Ferritic-martensitic stainless steel, the cladding material, corrodes severely in spent fuel pools, producing a large amount of corrosion products. The pool water needs to be purified. However, current purification methods rely on filters, which are prone to filter cake formation and filter clogging. Furthermore, their core components require frequent replacement and have a limited lifespan, increasing the burden of radioactive waste disposal and raising maintenance risks and economic costs. Summary of the Invention

[0005] The purpose of this invention is to provide a centrifugal separation device and method for corrosion products in spent fuel water tanks. By using a swirl impeller to generate a swirling flow field in the water, substances with different specific gravities are separated into solid and liquid components. The corrosion products are then efficiently removed by gravity sedimentation, thereby achieving the purpose of purifying the spent fuel water tank.

[0006] The objective of this invention is achieved through the following technical solution:

[0007] A centrifugal separation device for corrosion products in spent fuel water tanks includes: a solid collection tank and a venturi tube. An orifice plate is installed in the upper cylindrical section of the solid collection tank. The bottom of the solid collection tank is connected to an inlet pipe. A swirl impeller is installed inside the inlet pipe. The top of the inlet pipe has a separation section. A cylindrical guide plate is connected to the separation section. The separation section is connected to a connecting pipe. A recovery impeller is installed inside the connecting pipe. The connecting pipe is connected to the venturi tube, and the venturi tube is connected to an outlet.

[0008] Furthermore, the venturi tube includes a contraction section, a reflux section, and an expansion section connected in sequence. The contraction section is connected to the connecting pipe, and the reflux section has multiple reflux holes evenly distributed circumferentially.

[0009] Furthermore, the solid collection tank is a tank structure with a cylindrical upper part, a frustum-shaped middle part, and an inverted cone-shaped lower part, and the upper, middle, and lower parts of the solid collection tank are arranged coaxially.

[0010] Furthermore, the bottom of the solid collection tank has a solid discharge port.

[0011] Furthermore, the swirl impeller includes 4-8 arc-shaped blades, which are evenly arranged circumferentially, and the outlet angle of the arc-shaped blades is 45°-60°.

[0012] Furthermore, the separation section includes a circumferentially funnel-shaped separation opening, which is inwardly contracting.

[0013] Furthermore, the diameter of the separation port of the separation section is 0.8D-0.9D, where D is the diameter of the inlet pipe, the length of the separation section is 0.5D-1D, and the distance from the swirl impeller is 1D-2D.

[0014] Furthermore, the solid discharge port adopts an annular opening, a valve is installed on the solid discharge port, and the diameter of the solid discharge port opening is 0.2D-0.4D.

[0015] Furthermore, the length of the venturi tube varies within the range of 3D-4D, the cross-sectional diameter of the contraction section gradually decreases to 0.5D, the width of the return section is 0.5D, and the cross-sectional diameter of the expansion section gradually increases from 0.5D to the original pipe inner diameter.

[0016] The present invention may also include:

[0017] A method for centrifugal separation of corrosion products in spent fuel water pools, using the aforementioned apparatus, includes the following steps:

[0018] Water containing corrosion products flows into the pool through the inlet pipe. First, under the action of the swirling impeller, the solid and liquid phases acquire stable tangential velocities, transforming from linear motion to high-speed rotation, forming a swirling flow field. The liquid water and solid corrosion products move towards the center and periphery of the swirling flow field, respectively. Through the funnel-shaped separation port at the end of the separation section, the corrosion products fully enter the solid collection tank. After entering the solid collection tank, the corrosion products and some pool water are forced to flow by the cylindrical guide plate. The shape of the guide plate forces the solid and liquid phases to flow along a specific trajectory. The pool water containing corrosion products will change direction, and the corrosion products will accelerate towards the bottom of the solid collection tank. The denser corrosion products move to the bottom of the collection tank, while the less dense pool water moves in the opposite direction. Simultaneously, under the action of gravity, the corrosion products will further settle to the bottom and accumulate at the solid discharge outlet. In addition, the settling corrosion products also inhibit the backflow of solid particles into the pool water.

[0019] The separated pool water in the solid collection tank will continue to flow upward and reach the perforated plate. The perforated plate acts as a barrier to further prevent the backflow of particles and to filter the pool water, thereby reducing the solid particles carried by the pool water and further improving the separation efficiency.

[0020] The pool water in the original pipeline flows into the connecting pipe after passing through the separation section. Under the action of the recovery impeller, the pool water changes from spiral flow to axial flow, reducing the flow resistance of the pool water in the subsequent pipeline, increasing the axial flow velocity, and finally flowing into the Venturi tube. Based on Bernoulli's principle, when the pool water flow rate in the pipeline is constant, the pool water velocity will increase and the pressure will decrease due to the gradually narrowing cross section of the Venturi tube, forming a low-pressure zone after the outlet of the narrowing section. Due to the pressure difference between the inside and outside of the pipeline, the pool water in the solid collection tank will be drawn back into the pipeline through the return hole of the return section.

[0021] After the two streams of water merge, they continue to flow upward together. When they reach the expansion section, the resulting slow expansion structure will gradually reduce the flow rate of the water and restore the pressure to normal.

[0022] Finally, the pool water will flow back from the outlet into the spent fuel water pool circulation system pipeline.

[0023] The beneficial effects of this invention are as follows:

[0024] This invention does not rely on filter cartridges. Based on the significant density difference between the solid and liquid phases, a swirling impeller can be used to generate a swirling flow field in the pool water, enabling solid-liquid separation of substances with different specific gravities. Gravity sedimentation is then used to achieve efficient removal of corrosion products, thus purifying the spent fuel pool.

[0025] This invention uses a cylindrical guide plate to guide the pool water containing corrosion products to change its flow direction, extend the flow path, and increase the time for the corrosion products to settle naturally in the solid collection tank, allowing the solid particles to settle more fully. In addition, the cylindrical guide plate will guide the pool water to change direction, thereby generating an acceleration of the corrosion products toward the bottom of the solid collection tank, forcing the solid particles to move to the bottom, further improving the separation efficiency.

[0026] The present invention arranges a recovery impeller to restore the fluid from helical flow to axial flow, which can reduce the fluid flow resistance, increase the axial flow velocity, reduce fluid wear on the pipeline, and is more suitable for connection with subsequent equipment.

[0027] The present invention features a circumferential funnel-shaped separation port, which is opened along the axial direction and is consistent with the flow direction of the main fluid. Solid particles flow smoothly along the axial direction to the separation port, allowing solid particles to flow more fully into the collection tank, reducing particle escape and energy loss. Under the same processing capacity, it can reduce the energy consumption of power equipment, and is especially suitable for high-flow solid-liquid separation scenarios.

[0028] This invention uses a Venturi tube, which allows the water entering the solid collection tank to be drawn back into the original pipeline, thereby reducing the loss rate of liquid phase water, reducing the water content of solid waste, and reducing the burden of radioactive wastewater treatment.

[0029] This invention utilizes a cyclone device to guide pool water to form a cyclone field, achieves solid-liquid separation through centrifugal force, and collects corrosion products by gravity sedimentation, thus realizing online separation of solid and liquid phases. This can overcome the shortcomings of poor separation effect and long separation time of single gravity sedimentation.

[0030] This invention eliminates the reliance on filters in centrifugal separation, eliminates the need for traditional filter cartridges, avoids the risk of filter cake clogging, avoids significant pressure drop changes, and eliminates the need for frequent component replacements in radioactive environments. This reduces maintenance risks and decreases the burden and economic costs of radioactive waste disposal.

[0031] The perforated plate of this invention serves as a barrier and filter, effectively preventing particles from flowing back through the perforated plate, reducing the amount of solid particles carried by the pool water, and further improving the separation efficiency.

[0032] The invention has a simple structure, a small footprint, continuous operation, and strong compatibility with the existing circulation system of spent fuel water tanks. It does not require large-scale modification of the water tank structure and can be directly installed in pipelines. Attached Figure Description

[0033] Appendix Figure 1 This is a schematic diagram of the structure of the present invention.

[0034] In the attached diagram: 1. Inlet pipe, 2. Swirl impeller, 3. Separation section, 4. Cylindrical guide plate, 5. Solid collection tank, 6. Solid discharge outlet, 7. Connecting pipe, 8. Recovery impeller, 9. Venturi tube, 10. Orifice plate, 11. Recirculation section, 12. Expansion section, 13. Outlet. Detailed Implementation

[0035] The present invention will now be further described with reference to the accompanying drawings.

[0036] This invention provides a centrifugal separation device for corrosion products in spent fuel water tanks, as shown in the attached figure. Figure 1 As shown, it includes: a solid collection tank 5 and a venturi tube 9. An orifice plate 10 is installed in the upper cylindrical section of the solid collection tank 5. The bottom of the solid collection tank 5 is connected to an inlet pipe 1. A swirl impeller 2 is installed inside the inlet pipe 1. The top of the inlet pipe 1 has a separation section 3. A cylindrical guide plate 4 is connected to the outside of the separation section 3. The separation section 3 is connected to a connecting pipe 7. A recovery impeller 8 is installed inside the connecting pipe 7. The connecting pipe 7 is connected to the venturi tube 9. The venturi tube 9 is connected to an outlet 13.

[0037] Specifically, the bottom of the solid collection tank 5 is in close contact with the outer wall of the inlet pipe 1.

[0038] In this embodiment, a swirl impeller 2 is arranged in the inlet pipe 1. The swirl impeller 2 is composed of 4-8 arc-shaped blades. The root line of the blades conforms to the equation of an ellipse. The blades are evenly arranged circumferentially, and the outlet angle of the blades is 45°-60°.

[0039] The swirl impeller 2 is followed by the separation section 3. The length of the separation section 3 is between 0.5D and 1D, and the distance from the swirl impeller 2 is between 1D and 2D. The separation section 3 is composed of a circumferential trumpet-shaped separation port, and the separation port is in an inwardly contracting shape. The diameter of the separation port varies in the range of 0.8D to 0.9D.

[0040] Where D is the diameter of inlet pipe 1.

[0041] The separation section 3 is connected to a cylindrical guide plate 4, which is in close contact with the upper part of the separation section 3, with the plate wall between 0.5D and 1D from the pipe wall.

[0042] Furthermore, a solid collection trough 5 is provided outside the cylindrical guide plate 4. The solid collection trough 5 is a trough structure with a cylindrical upper part, a frustum-shaped middle part, and an inverted cone shape at the bottom. The three parts are arranged coaxially and a smooth transition is adopted at the connection.

[0043] A solid discharge port 6 is opened at the bottom of the solid collection tank 5. The solid discharge port 6 adopts an annular opening design and a suitable valve setting. The diameter of the opening is in the range of 0.2D-0.4D.

[0044] A perforated plate 10 is installed in the upper cylindrical section of the solid collection tank 5. The perforated plate 10 adopts a square array opening layout, and the diameter of the holes is adjusted according to the water flow rate and the diameter of the solid particles.

[0045] Furthermore, the separation section 3 is followed by a connecting pipe 7, the length of which is 2D-3D.

[0046] In this embodiment, a recovery impeller 8 is arranged inside the connecting pipe 7. The recovery impeller 8 consists of 4-8 arc-shaped blades. The root line of the blades conforms to the equation of an ellipse. The blades are evenly arranged circumferentially, and the outlet angle of the blades is 45°-60° to ensure that the fluid restores axial flow.

[0047] Connecting pipe 7 is followed by venturi pipe 9. Venturi pipe 9 consists of a contraction section, a return section 11, and an expansion section 12, with smooth transitions between sections. The length of this device varies in the range of 3-4D. The cross-sectional diameter of the contraction section gradually decreases to 0.5D, the width of the return section 11 is 0.5D, and the cross-sectional diameter of the expansion section 12 gradually increases from 0.5D to the original pipe inner diameter.

[0048] On the wall of the reflux section 11, an appropriate number of reflux holes are evenly opened along the circumference, with the hole area being 5%-10% of the side surface area of ​​the pipe.

[0049] Connect outlet 13 after venturi tube 9.

[0050] This embodiment also provides a separation method for corrosion products in a centrifugal separation device for spent fuel water pools, comprising the following steps:

[0051] The pool water containing corrosion products flows in from the inlet pipe 1. Under the action of the swirl impeller 2, the solid and liquid phases can obtain a stable tangential velocity, changing from the original linear motion to high-speed rotational motion, forming a swirling flow field. Due to the significant density difference between the solid and liquid phases, the liquid phase water and the solid corrosion products will move towards the center and periphery of the swirling flow field, respectively. The funnel-shaped separation port at the end of the separation section 3 is opened axially, consistent with the main flow direction of the pool water in the pipeline, allowing the corrosion products to enter the solid collection tank 5 more fully. After the corrosion products and some pool water enter the solid collection tank 5, they will be forced to flow by the cylindrical guide plate 4. The shape of the guide plate forces the solid and liquid phases to flow along a specific trajectory. The pool water containing corrosion products will change direction, and the corrosion products will generate acceleration towards the bottom of the solid collection tank 5. The denser corrosion products move to the bottom of the collection tank, while the less dense pool water moves in the opposite direction. At the same time, under the action of gravity, the corrosion products will further settle to the bottom and accumulate at the solid discharge outlet 6. In addition, the settling corrosion products will also inhibit the solid particles from flowing back into the pool water. When the corrosion products accumulate to a certain extent, the valve of the solid discharge outlet 6 can be opened to discharge the corrosion products.

[0052] The cylindrical guide plate 4 also extends the flow path of the pool water containing corrosion products, increases the time for the corrosion products to settle naturally in the collection tank, allows the corrosion products to settle more fully, and improves the separation efficiency.

[0053] The separated pool water in the solid collection tank 5 will continue to flow upward and reach the perforated plate 10. The perforated plate 10 plays a certain blocking role, which can further prevent the backflow of particles, filter the pool water, reduce the solid particles carried by the pool water, and further improve the separation efficiency.

[0054] The pool water in the original pipeline flows into the connecting pipe 7 after passing through the separation section 3. Under the action of the recovery impeller 8, the pool water changes from spiral flow to axial flow, which can reduce the flow resistance of the pool water in the subsequent pipeline and increase the axial flow velocity. Finally, it flows into the Venturi tube 9. Based on Bernoulli's principle, when the pool water flow rate in the pipeline is constant, the pool water velocity will increase and the pressure will decrease due to the gradual reduction of the cross-section of the contraction section of the Venturi tube 9, forming a low-pressure zone behind the outlet of the contraction section. Due to the pressure difference between the inside and outside of the pipeline, the pool water in the solid collection tank 5 will be drawn back into the pipeline through the return hole of the return section 11.

[0055] After the two streams of water merge, they continue to flow upward together and reach the expansion section 12. Because the cone angle of the cone tube in the expansion section 12 is small, the resulting slow expansion structure will make the water flow rate of the pool slow down and the pressure will return to normal.

[0056] Finally, the pool water will flow back from outlet 13 into the spent fuel pool circulation system pipeline.

[0057] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A centrifugal separation device for corrosion products in spent fuel water tanks, characterized in that, include: Solid collection tank (5), Venturi tube (9), the upper cylindrical section of the solid collection tank (5) is equipped with an orifice plate (10), the bottom of the solid collection tank (5) is connected to the inlet pipe (1), the inlet pipe (1) is equipped with a swirl impeller (2), the top of the inlet pipe (1) has a separation section (3), the separation section (3) is connected to a cylindrical guide plate (4), the separation section (3) is connected to a connecting pipe (7), the connecting pipe (7) is equipped with a recovery impeller (8), the connecting pipe (7) is connected to the Venturi tube (9), and the Venturi tube (9) is connected to the outlet (13).

2. The centrifugal separation device for corrosion products in spent fuel water tanks according to claim 1, characterized in that, The Venturi tube (9) includes a contraction section, a return section (11), and an expansion section (12) connected in sequence. The contraction section is connected to the connecting pipe (7), and the return section (11) has a plurality of return holes evenly distributed along the circumference.

3. The centrifugal separation device for corrosion products in spent fuel water tanks according to claim 2, characterized in that, The solid collection tank (5) is a tank structure with a cylindrical upper part, a frustum-shaped middle part, and an inverted cone shape at the bottom. The upper, middle, and lower parts of the solid collection tank (5) are arranged coaxially.

4. The centrifugal separation device for corrosion products in spent fuel water tanks according to claim 3, characterized in that, The solid collection tank (5) has a solid discharge port (6) at the bottom.

5. The centrifugal separation device for corrosion products in spent fuel water tanks according to claim 4, characterized in that, The swirl impeller (2) includes 4-8 arc-shaped blades, which are evenly arranged circumferentially, and the outlet angle of the arc-shaped blades is 45°-60°.

6. The centrifugal separation device for corrosion products in spent fuel water tanks according to claim 5, characterized in that, The separation section (3) includes a circumferentially funnel-shaped separation port, which is in an inwardly contracting form.

7. The centrifugal separation device for corrosion products in spent fuel water tanks according to claim 6, characterized in that, The The diameter of the separation port of the separation section (3) is 0.8D-0.9D, where D is the diameter of the inlet pipe (1), the length of the separation section (3) is 0.5D-1D, and the distance from the swirl impeller (2) is 1D-2D.

8. The centrifugal separation device for corrosion products in spent fuel water tanks according to claim 7, characterized in that, The solid discharge port (6) has an annular opening, and a valve is installed on the solid discharge port (6). The diameter of the opening of the solid discharge port (6) is 0.2D-0.4D.

9. The centrifugal separation device for corrosion products in spent fuel water tanks according to claim 8, characterized in that, The length of the Venturi tube (9) varies in the range of 3D-4D. The cross-sectional diameter of the contraction section gradually decreases to 0.5D. The width of the return section (11) is 0.5D. The cross-sectional diameter of the expansion section (12) gradually increases from 0.5D to the original inner diameter of the pipe.

10. A method for centrifugal separation of corrosion products in spent fuel water tanks, characterized in that, The method using the apparatus according to any one of claims 1-9 comprises the following steps: The pool water containing corrosion products flows in from the inlet pipe (1). First, under the action of the swirling impeller (2), the solid and liquid phases obtain a stable tangential velocity, changing from the original linear motion to high-speed rotational motion, forming a swirling flow field. The liquid phase pool water and the solid phase corrosion products will move towards the center and the periphery of the swirling flow field, respectively. Through the funnel-shaped separation port at the end of the separation section (3), the corrosion products fully enter the solid collection tank (5). After the corrosion products and some pool water enter the solid collection tank (5), they will be forced to flow by the cylindrical guide plate (4). The shape of the guide plate forces the solid and liquid phases to flow along a specific trajectory. The pool water containing corrosion products will turn, and then the corrosion products will generate acceleration towards the bottom of the solid collection tank (5). The corrosion products with higher density move towards the bottom of the collection tank, while the pool water with lower density moves in the opposite direction. At the same time, under the action of gravity, the corrosion products will further settle to the bottom and accumulate at the solid discharge port (6). In addition, the corrosion products in the settling will also inhibit the solid particles from flowing back into the pool water. The separated pool water in the solid collection tank (5) will continue to flow upward and reach the perforated plate (10). The perforated plate (10) acts as a barrier to further prevent the backflow of particles, and filters the pool water to reduce the solid particles carried by the pool water and further improve the separation efficiency. The pool water in the original pipeline will flow into the connecting pipe (7) after passing through the separation section (3). Under the action of the recovery impeller (8), the pool water will change from spiral flow to axial flow, reducing the flow resistance of the pool water in the subsequent pipeline, increasing the axial flow velocity, and finally flowing into the Venturi tube (9). Based on Bernoulli's principle, when the pool water flow rate in the pipeline is constant, the pool water flow velocity will increase and the pressure will decrease due to the gradual reduction of the cross section of the contraction section of the Venturi tube (9), forming a low-pressure zone behind the outlet of the contraction section. Due to the pressure difference between the inside and outside of the pipeline, the pool water in the solid collection tank (5) will be drawn back into the pipeline through the return hole of the return section (11). After the two streams of water merge, they continue to flow upward together and reach the expansion section (12). The resulting slow expansion structure will make the water flow rate of the pool slow down and the pressure will return to normal. Finally, the pool water will flow from the outlet (13) back into the spent fuel pool circulation system pipeline.

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