Vertical seawater lift pump for nuclear power station

Abstract

The invention relates to the technical field of lift pumps, and discloses a vertical seawater lift pump for a nuclear power plant, which comprises a pump pipe, a motor arranged at the bottom of the pump pipe, a water inlet connector and a water outlet connector respectively and correspondingly arranged at the bottom and the top of the pump pipe, and a plurality of booster impellers arranged in the pump pipe, the self-adaptive flow speed reducing component is arranged in the pump pipe; the flow speed self-adaption reducing component comprises a one-way valve assembly arranged in the pump pipe and an expansion assembly arranged at the bottom of the one-way valve assembly. Through the arranged flow speed self-adaptive reducing part, the flow speed of the one-way valve area located in the high-pressure area can be reduced in a self-adaptive mode, then the impact force of the flow speed on the one-way valve is reduced, the probability of cavitation is reduced, and the service life of the lift pump is prolonged.

Description

Technical Field

[0001] The invention relates to the technical field of lift pumps, and in particular to a vertical seawater lift pump for a nuclear power plant. Background Art

[0002] In nuclear power plants, vertical seawater lifting pumps are the core equipment to ensure the safe operation of the nuclear island cooling system. They continuously transport seawater to key parts such as the condenser and waste heat removal system through a vertical multi-stage centrifugal structure. The pump adopts a vertical shaft design. The drive motor drives the series impeller to rotate at high speed. The seawater is pressurized step by step under the action of centrifugal force to achieve large flow and medium and high head requirements. The vertical structure not only saves space, but also optimizes the axial force through balancing holes and symmetrical impeller layout, reducing the risk of bearing wear and vibration. Since nuclear power plants have strict requirements on equipment reliability and leakage prevention, the pump body needs to deal with problems such as high salinity corrosion, sediment wear and biological adhesion in seawater. Therefore, corrosion-resistant materials such as duplex stainless steel impellers, titanium alloy sleeves or concrete volutes are used, and are equipped with shaft seal-free magnetic drive technology to completely eliminate the risk of sealing failure.

[0003] In order to prevent the backflow of seawater from damaging the impeller and the motor, the existing vertical lift pump often adds a one-way valve inside so that the seawater will not flow back when the lift pump stops working. When the installation height of the seawater lift pump exceeds its maximum allowable water suction height, the pressure at the pump inlet will decrease. When the pressure drops to the saturated vapor pressure, the seawater will vaporize to produce bubbles, causing cavitation. Since the flow cross-sectional area of ​​the one-way valve area is often small, the seawater in this area will have a higher flow rate and greater impact force after being pressurized layer by layer. Excessive water flow impact force will cause the flow state of the flow channel in the pump to become disordered, resulting in local low-pressure areas. The pressure in these low-pressure areas may be lower than the saturated vapor pressure, so that the water vaporizes in these areas to form bubbles, which in turn causes cavitation, causing corrosion and damage to the parts and materials in the one-way valve area, and then corroding and damaging the lift pump, reducing its service life. Therefore, there is an urgent need for a vertical lift pump that can adaptively reduce its flow rate according to the size of the seawater impact force in the one-way valve area, so as to reduce the probability of cavitation. Summary of the invention

[0004] In view of the problem of the prior art that the impact force of seawater in the one-way valve area is too large, which is prone to cavitation, causing corrosion and damage to the pump and parts and materials in the one-way valve area, a vertical seawater lifting pump for nuclear power plants is proposed.

[0005] The purpose is: by setting up a flow rate adaptive reduction component, the flow rate in the one-way valve area located in the high-pressure area can be adaptively reduced, thereby reducing the impact force on the one-way valve, reducing the probability of cavitation, and increasing the service life of the lift pump.

[0006] The technical solution of the present invention is a vertical seawater lifting pump for a nuclear power plant, comprising a pump pipe, a motor arranged at the bottom of the pump pipe, a water inlet connection port and a water outlet connection port arranged at the bottom and the top of the pump pipe respectively, and a plurality of booster impellers arranged inside the pump pipe, and also comprising a flow rate adaptive reduction component arranged inside the pump pipe; The flow rate adaptive reduction component includes a one-way valve component arranged inside the pump tube, and an expansion component arranged at the bottom of the one-way valve component; The one-way valve assembly is used to prevent seawater from flowing back and causing damage to the booster impeller and the motor; the one-way valve assembly includes a baffle plate arranged inside the pump pipe, and the expansion assembly includes an expansion groove opened on the inner wall of the pump pipe, a plurality of expansion plates arranged in the expansion groove, a connecting rod arranged on one side of the expansion plate, and an expansion rod arranged on one side of the connecting rod, and the top of the expansion rod passes through the baffle plate and is fixedly connected to the one-way valve assembly.

[0007] With the above technical solution, when the seawater lifting pump is working, the water inlet connection port and the water outlet connection port are connected through pipes respectively. When the water inlet connection port is placed in seawater, the motor is started, and the motor drives the internal multi-layer boost impellers that are evenly distributed vertically to rotate. After the layers of boosting, the seawater pushes the one-way valve assembly open, so that the seawater flows out from the water outlet connection port after being pressurized, thereby achieving the lifting of seawater. When the pump speed is too high, it will affect the water flow state and pressure distribution in the pump, which may lead to cavitation, and the excessive impact force of the water flow will cause the flow state of the flow channel in the pump to become disordered, resulting in local low-pressure areas. The pressure in these low-pressure areas may be lower than the saturated vapor pressure, so that the water vaporizes in these areas to form bubbles, thereby causing cavitation. In addition, excessive water flow impact force may also cause the components in the pump to vibrate, further destroying the stability of the water flow, increasing the possibility of cavitation, and causing corrosion to the parts in the one-way valve area inside the pump, as well as damage to the surface of the material. Therefore, by setting the flow rate adaptive reduction component, the flow rate in the one-way valve area located in the high-pressure area can be adaptively reduced, thereby reducing its impact force on the one-way valve, reducing the probability of cavitation, and increasing the service life of the lift pump. When the water flow rate is too large, the greater the impact force, the greater the impact on the one-way valve assembly, making the one-way valve assembly open more. At this time, the one-way valve assembly will simultaneously drive the expansion assembly to expand during the opening process, so that the expansion plate and the connecting rod are synchronously expanded under the driving action of the expansion rod, thereby increasing the average cross-sectional area of ​​the water flow in the bottom area of ​​the baffle, thereby reducing the water flow velocity in this area, reducing the impact force on the one-way valve assembly, and thus reducing the probability of cavitation.

[0008] Furthermore, the expansion assembly also includes a vertical hole opened at the top of the expansion rod, an oblique hole opened on one side of the vertical hole, a sliding hole opened in the middle of the expansion plate, and the connecting rod slides in the vertical and oblique holes through cylindrical limiters symmetrically arranged on both sides, a hinge seat arranged at the bottom of two adjacent expansion plates, and the hinge seat is fixedly connected to the expansion groove, a rotating groove opened at the bottom of the baffle, and a movable groove opened on one side of the expansion groove.

[0009] By adopting the above technical solution, when the one-way valve assembly is pushed open by the water flow, it will simultaneously drive the expansion rod to move upward, so that the connecting rod slides in the vertical hole through the cylinder. At this time, several expansion plates do not rotate. When the impact force of the water flow reaches the threshold, the one-way valve assembly is continuously pushed up, so that after the connecting rod moves to the inclined hole, under the guiding action of the inclined hole, the expansion plate is driven to rotate and open, so that the water flow cross-sectional area in the bottom area of ​​the baffle gradually increases and its flow rate is reduced. The setting of the rotating groove is used to facilitate the rotation of the expansion plate, and the setting of the movable groove facilitates the up and down movement of the expansion rod.

[0010] Furthermore, in the initial state, the plurality of expansion plates form a truncated cone shape with a narrow top and a wide bottom.

[0011] By adopting the above technical solution, the truncated cone-shaped expansion plate can guide the water flow, so that the water can quickly flow out from the middle of the one-way valve assembly.

[0012] Furthermore, an oblique groove having the same inclination direction as the oblique hole is provided on the baffle.

[0013] By adopting the above technical solution, when the expansion rod continues to move upward, the greater the impact force of the water flow, the greater the expansion range of the expansion plates, and the better the effect of reducing the speed of the water flow in the opposite direction. When the connecting rod reaches the end of the expansion rod, the bottom side of the expansion rod is in contact with the inclined groove, and the expansion range of the expansion plates is also the largest, so that the expansion plates are in a vertical state. At this time, the average cross-sectional area through which the water flows is the largest, and the effect of reducing the speed of the water flow is also the largest.

[0014] Furthermore, the bottom of the expansion rod moves in the movable groove, and the end of the expansion rod is located on one side of the hinged rotation point of the bottom of the expansion plate in the vertical direction.

[0015] By adopting the above technical solution, the expansion rod moves in the movable groove so that the end of the expansion rod is located on the left side of the bottom of the expansion plate in the vertical direction. This makes it convenient for the expansion plate to be in a vertical state when the connecting rod moves to the end of the expansion rod, thereby forming the maximum cross-sectional area for water flow and improving the deceleration effect on the water flow.

[0016] Furthermore, the one-way valve assembly includes a valve plate arranged on the top of the baffle, a valve column arranged on the top of the valve plate, a spring sleeved on the valve column, and an abutment column arranged on the top of the spring, and the valve column slides in the abutment column in a limited position, and the bottom of the valve plate is fixedly connected to a plurality of expansion rods evenly distributed and penetrating the baffle.

[0017] By adopting the above technical solution, when the valve plate is lifted up, water flows out from between the valve plate and the baffle, and the spring is compressed, causing the valve column to slide upward in the ground connection column. When the lift pump stops running, under the resetting action of the spring, the valve plate blocks the baffle to prevent water backflow impact and damage to the boost impeller and motor.

[0018] Furthermore, a curved groove is provided on the top of the rotating groove, and spikes are evenly and annularly distributed on the curved groove.

[0019] By adopting the above technical solution, when the expansion plate is unfolded, the arc surface groove is exposed. At this time, part of the water flow will flow out from the middle, and the other part will enter the arc surface groove. The part of the water flow entering the arc surface groove will reflux along the inclined surface of the arc surface groove under the action of the impact force. After entering the arc surface groove, the bubbles generated in the high-pressure area are punctured, further reducing the probability of cavitation.

[0020] Furthermore, the spike is inclined in the same direction as the arc surface groove.

[0021] By adopting the above technical solution, since the water flows back and forth along the arc surface groove, the sharp thorns can better puncture the bubbles, thereby enhancing the bubble removal effect.

[0022] Compared with the prior art, the present invention has the following beneficial effects: 1. By setting the flow rate adaptive reduction component, the flow rate in the one-way valve area located in the high-pressure area can be adaptively reduced, thereby reducing the impact force on the one-way valve, reducing the probability of cavitation, and increasing the service life of the lift pump.

[0023] 2. When the valve plate is lifted up, water flows out from between the valve plate and the baffle, and the spring is compressed, causing the valve column to slide upward in the ground connection column. When the lift pump stops running, the valve plate blocks the baffle under the reset action of the spring to prevent water backflow impact and damage to the boost impeller and motor.

[0024] 3. When the expansion plate is unfolded, the arc groove is exposed. At this time, part of the water flow will flow out from the middle, and the other part will enter the arc groove. The part of the water flow entering the arc groove will reflux along the inclined surface of the arc groove under the action of the impact force. After entering the arc groove, the bubbles generated in the high-pressure area will be punctured, further reducing the probability of cavitation. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a schematic diagram of the overall three-dimensional structure of the seawater lifting pump of the present invention; Figure 2 It is a schematic diagram of the three-dimensional structure inside the end of the seawater lifting pump of the present invention; Figure 3 It is a schematic diagram of the exploded structure of the internal structure of the end pump body of the lift pump of the present invention; Figure 4 It is a schematic diagram of the overall front cross-sectional structure of the pump body of the present invention; Figure 5 For the present invention Figure 4 The enlarged view of point A in the middle and the schematic diagram of the water flow direction structure; Figure 6 It is a schematic diagram of the exploded structure of the one-way valve assembly and the expansion assembly of the present invention; Figure 7 It is a schematic diagram of the coordinated three-dimensional structure of the expansion rod, the expansion plate and the connecting rod of the present invention in the initial state; Figure 8 It is an enlarged diagram of the baffle of the present invention and a schematic diagram of the structure of the seawater return circulation direction.

[0026] In the figure: 1. pump pipe; 2. motor; 3. water inlet connection port; 4. water outlet connection port; 5. one-way valve assembly; 51. baffle; 52. valve plate; 53. valve column; 54. spring; 55. abutment column; 6. expansion assembly; 61. expansion groove; 62. expansion plate; 63. connecting rod; 64. expansion rod; 65. vertical hole; 66. oblique hole; 67. sliding hole; 68. hinge seat; 69. rotating groove; 70. moving groove; 71. oblique groove; 8. arc groove; 9. spike. DETAILED DESCRIPTION

[0027] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are described in detail below in conjunction with the accompanying drawings.

[0028] Example 1, reference Figure 1-Figure 8, which is the first embodiment of the present invention, provides a vertical seawater lifting pump for a nuclear power plant, including a pump pipe 1, a motor 2 installed at the bottom of the pump pipe 1, a water inlet connection port 3 and a water outlet connection port 4 installed at the bottom and the top of the pump pipe 1 respectively, and a plurality of boosting impellers installed inside the pump pipe 1, and also includes a flow rate adaptive reduction component installed inside the pump pipe 1; the flow rate adaptive reduction component includes a one-way valve assembly 5 installed inside the pump pipe 1, and an expansion assembly 6 installed at the bottom of the one-way valve assembly 5; the one-way valve assembly 5 is used to prevent seawater from backflowing and causing damage to the boosting impeller and the motor 2; the one-way valve assembly 5 includes a baffle 51 fixedly connected to the inside of the pump pipe 1, the expansion assembly 6 includes an expansion groove 61 opened on the inner wall of the pump pipe 1, a plurality of expansion plates 62 rotatably connected in the expansion groove 61, a connecting rod 63 fixedly connected to one side of the expansion plate 62, and an expansion rod 64 slidably connected to one side of the connecting rod 63, and the top of the expansion rod 64 passes through the baffle 51 and is fixedly connected to the one-way valve assembly 5.

[0029] Specifically, when the seawater lifting pump is working, the water inlet connection port 3 and the water outlet connection port 4 are connected through a pipeline respectively, and then the pipeline is placed in the seawater, and the motor 2 is started. The motor 2 drives the rotation of several vertically evenly distributed multi-layer boosting impellers inside (this is the existing technology and will not be described in detail). After the layers of boosting, the seawater pushes the one-way valve assembly 5 open, so that the seawater flows out from the water outlet connection port 4 after being pressurized, thereby achieving the lifting of the seawater. When the pump speed is too high, it will affect the water flow state and pressure distribution in the pump, which may lead to cavitation, and the excessive impact force of the water flow will cause the flow state of the flow channel in the pump to become disordered, resulting in local low-pressure areas. The pressure in these low-pressure areas may be lower than the saturated vapor pressure, so that the water vaporizes in these areas to form bubbles, thereby causing cavitation. In addition, the excessive impact force of the water flow may also cause the components in the pump to vibrate, further destroy the stability of the water flow, increase the possibility of cavitation, and cause corrosion to the parts in the one-way valve area inside the pump, as well as damage to the surface of the material. Therefore, by setting the flow rate adaptive reduction component, the flow rate in the one-way valve area located in the high-pressure area can be adaptively reduced, thereby reducing its impact force on the one-way valve, reducing the probability of cavitation, and increasing the service life of the lift pump. When the water flow rate is too large, the greater the impact force, the greater the impact on the one-way valve assembly 5, making the one-way valve assembly 5 open more. At this time, the one-way valve assembly 5 will synchronously drive the expansion assembly 6 to expand during the opening process, so that the expansion plate 62 and the connecting rod 63 are synchronously expanded under the driving action of the expansion rod 64, thereby increasing the average cross-sectional area of ​​the water flow in the bottom area of ​​the baffle 51, thereby reducing the water flow velocity in this area, reducing the impact force on the one-way valve assembly 5, and thus reducing the probability of cavitation.

[0030] Reference Figure 2-Figure 7The expansion assembly 6 also includes a vertical hole 65 opened at the top of the expansion rod 64, an oblique hole 66 opened on one side of the vertical hole 65, and a sliding hole 67 opened in the middle of the expansion plate 62, and the connecting rod 63 slides in the vertical and oblique holes 66 through cylindrical limiters symmetrically arranged on both sides, and is rotatably connected to a hinge seat 68 at the bottom of two adjacent expansion plates 62, and the hinge seat 68 is fixedly connected to the expansion groove 61, a rotating groove 69 opened at the bottom of the baffle 51, and a movable groove 70 opened on one side of the expansion groove 61.

[0031] Specifically, when the one-way valve assembly 5 is pushed open by the water flow, it will simultaneously drive the expansion rod 64 to move upward, so that the connecting rod 63 slides in the vertical hole 65 through the cylinder. At this time, some expansion plates 62 do not rotate. When the impact force of the water flow reaches the threshold, the one-way valve assembly 5 is continuously pushed up, so that the connecting rod 63 moves to the inclined hole 66. Under the guidance of the inclined hole 66, the expansion plate 62 is driven to rotate and open, so that the water flow cross-sectional area in the bottom area of ​​the baffle 51 gradually increases, reducing its flow rate. The setting of the rotating groove 69 is used to facilitate the rotation of the expansion plate 62, and the setting of the moving groove 70 facilitates the up and down movement of the expansion rod 64.

[0032] Reference Figure 6-Figure 7 In the initial state, a plurality of expansion plates 62 form a truncated cone with a narrow top and a wide bottom.

[0033] Specifically, the frustoconical expansion plate 62 can guide the water flow, so that the water can quickly flow out from the middle of the one-way valve assembly 5 .

[0034] Reference Figure 5 The baffle plate 51 is also provided with an oblique groove 71 having the same oblique direction as the oblique hole 66 .

[0035] Specifically, when the expansion rod 64 is in the process of continuously moving upward, the greater the impact force of the water flow, the greater the expansion range of the expansion plates 62, and the better the effect of reducing the speed of the water flow in the opposite direction. When the connecting rod 63 reaches the end of the expansion rod 64, the bottom side of the expansion rod 64 is in contact with the inclined groove 71, and the expansion range of the expansion plates 62 is also the largest, so that the expansion plates 62 are in a vertical state. At this time, the average cross-sectional area of ​​the water flow is the largest, and the effect of reducing the speed of the water flow is also the largest.

[0036] Reference Figure 5 The bottom of the expansion rod 64 moves in the moving groove 70, and the end of the expansion rod 64 is located on one side of the hinged rotation point at the bottom of the expansion plate 62 in the vertical direction.

[0037] Specifically, the expansion rod 64 moves in the movable groove 70 so that the end of the expansion rod 64 is located on the left side of the bottom of the expansion plate 62 in the vertical direction, so that when the connecting rod 63 moves to the end of the expansion rod 64, the expansion plate 62 can be in a vertical state, thereby forming the maximum cross-sectional area for water flow to pass through, thereby improving the deceleration effect on the water flow.

[0038] Example 2, reference Figure 4-Figure 7 , is the second embodiment of the present invention, which is different from the first embodiment in that: the one-way valve assembly 5 includes a valve plate 52 abutting against the top of the baffle 51, a valve column 53 fixedly connected to the top of the valve plate 52, a spring 54 sleeved on the valve column 53, and an abutting column 55 fixedly connected to the top of the spring 54, and the valve column 53 slides in the abutting column 55, and the bottom of the valve plate 52 is fixedly connected to a plurality of expansion rods 64 evenly distributed and penetrating the baffle 51.

[0039] Specifically, when the valve plate 52 is lifted up, water flows out from between the valve plate 52 and the baffle 51, and the spring 54 is compressed, so that the valve column 53 slides upward in the ground connection column. When the lift pump stops running, under the reset action of the spring 54, the valve plate 52 blocks the baffle 51 to prevent the backflow of water from damaging the booster impeller and the motor 2. The rest of the structure is the same as that of Example 1.

[0040] Example 3, reference Figure 8 , which is the third embodiment of the present invention. This embodiment is different from the second embodiment in that an arc groove 8 is provided on the top of the rotating groove 69, and spikes 9 are evenly and annularly distributed on the arc groove 8.

[0041] Specifically, when the expansion plate 62 is unfolded, the arc groove 8 is exposed. At this time, part of the water flow will flow out from the middle, and the other part will enter the arc groove 8. The part of the water flow that enters the arc groove 8 will reflux along the inclined surface of the arc groove 8 under the action of the impact force. After entering the arc groove 8, the bubbles generated in the high-pressure area will be punctured, further reducing the probability of cavitation.

[0042] Reference Figure 8 The spike 9 is inclined in the same direction as the arc surface groove 8.

[0043] Specifically, since the water flows back and forth along the arc groove 8, the spikes 9 can better puncture the bubbles, thereby enhancing the bubble removal effect. The rest of the structure is the same as that of the second embodiment.

[0044] Comprehensive examples 1-3, the working principle of the present invention: when the seawater lifting pump is working, the water inlet connection port 3 and the water outlet connection port 4 are connected through pipelines respectively, and the water inlet connection port 3 is placed in the seawater, and the motor 2 is started, and the motor 2 drives the internal multiple vertically evenly distributed multi-layer boosting impellers to rotate. After the layers of boosting, the seawater pushes the one-way valve assembly 5 open, so that the seawater flows out from the water outlet connection port 4 after being pressurized, and the seawater is lifted. When the pump speed is too high, it will affect the water flow state and pressure distribution in the pump, which may lead to cavitation, and the excessive impact force of the water flow will cause the flow state of the flow channel in the pump to become disordered, resulting in local low-pressure areas. The pressure in these low-pressure areas may be lower than the saturated vapor pressure, so that the water vaporizes in these areas to form bubbles, thereby causing cavitation. In addition, the excessive impact force of the water flow may also cause the components in the pump to vibrate, further destroy the stability of the water flow, increase the possibility of cavitation, and cause corrosion to the parts in the one-way valve area inside the pump, as well as damage to the surface of the material. Therefore, by setting the flow rate adaptive reduction component, the flow rate in the one-way valve area located in the high-pressure area can be adaptively reduced, thereby reducing its impact force on the one-way valve, reducing the probability of cavitation, and increasing the service life of the lift pump. When the water flow rate is too large, the greater the impact force, the greater the impact on the one-way valve assembly 5, making the one-way valve assembly 5 open more. At this time, the one-way valve assembly 5 will synchronously drive the expansion assembly 6 to expand during the opening process, so that the expansion plate 62 and the connecting rod 63 are synchronously expanded under the driving action of the expansion rod 64, thereby increasing the average cross-sectional area of ​​the water flow in the bottom area of ​​the baffle 51, thereby reducing the water flow velocity in this area, reducing the impact force on the one-way valve assembly 5, and thus reducing the probability of cavitation.

[0045] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present invention, which should all be included in the scope of the claims of the present invention.

Claims

1. A vertical seawater lifting pump for a nuclear power plant, comprising a pump pipe, a motor arranged at the bottom of the pump pipe, a water inlet connection port and a water outlet connection port arranged at the bottom and the top of the pump pipe respectively, and a plurality of booster impellers arranged inside the pump pipe, characterized in that: Also included is a flow rate adaptive reduction component disposed inside the pump tube; The flow rate adaptive reduction component includes a one-way valve component arranged inside the pump tube, and an expansion component arranged at the bottom of the one-way valve component; The one-way valve assembly is used to prevent seawater from flowing back and causing damage to the booster impeller and the motor; the one-way valve assembly includes a baffle plate arranged inside the pump pipe, and the expansion assembly includes an expansion groove opened on the inner wall of the pump pipe, a plurality of expansion plates arranged in the expansion groove, a connecting rod arranged on one side of the expansion plate, and an expansion rod arranged on one side of the connecting rod, and the top of the expansion rod passes through the baffle plate and is fixedly connected to the one-way valve assembly.

2. The vertical seawater lifting pump for a nuclear power plant according to claim 1, characterized in that: The expansion assembly also includes a vertical hole opened at the top of the expansion rod, an oblique hole opened on one side of the vertical hole, a sliding hole opened in the middle of the expansion plate, and the connecting rod slides in the vertical and oblique holes through cylindrical limiters symmetrically arranged on both sides, a hinge seat arranged at the bottom of two adjacent expansion plates, and the hinge seat is fixedly connected to the expansion groove, a rotating groove opened at the bottom of the baffle, and a movable groove opened on one side of the expansion groove.

3. The vertical seawater lifting pump for a nuclear power plant according to claim 2, characterized in that: In the initial state, a plurality of the expansion plates form a truncated cone with a narrow top and a wide bottom.

4. The vertical seawater lifting pump for a nuclear power plant according to claim 1, characterized in that: An oblique groove having the same inclination direction as the oblique hole is also provided on the baffle.

5. The vertical seawater lifting pump for a nuclear power plant according to claim 1, characterized in that: The bottom of the expansion rod moves in the moving groove, and the end of the expansion rod is located at one side of the hinged rotation point of the bottom of the expansion plate in the vertical direction.

6. The vertical seawater lifting pump for a nuclear power plant according to claim 1, characterized in that: The one-way valve assembly includes a valve plate arranged on the top of the baffle, a valve column arranged on the top of the valve plate, a spring sleeved on the valve column, and an abutment column arranged on the top of the spring, and the valve column slides within the abutment column in a limited manner, and the bottom of the valve plate is fixedly connected to a plurality of expansion rods evenly distributed and penetrating the baffle.

7. The vertical seawater lifting pump for a nuclear power plant according to claim 2, characterized in that: The top of the rotating groove is provided with an arc surface groove, and spikes are evenly and annularly distributed on the arc surface groove.

8. The vertical seawater lifting pump for a nuclear power plant according to claim 7, characterized in that: The spike is inclined in the same direction as the arc surface groove.

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