Variable frequency speed regulation type starting feed pump for nuclear power station

Abstract

The invention relates to the technical field of nuclear power feed pumps, and discloses a variable-frequency and variable-speed starting feed pump for a nuclear power plant, which comprises a pump body, a driving shaft arranged in the pump body, a variable-speed motor arranged at one end of the driving shaft, an auxiliary water delivery assembly arranged on one side of the pump body, and a multi-stage impeller mechanism and an adjusting assembly arranged in the pump body, a main water inlet and a main water outlet are formed in the top of the pump body, water flow enters the front cavity from the main water inlet through the arranged auxiliary water conveying assembly and the multi-stage impeller mechanism, the speed adjusting motor runs at a low speed and drives the front impeller body and the rear impellers to rotate in the pump body through the driving shaft, and when the front impeller body rotates, the rear impellers rotate in the pump body. Water flow can be divided into two parts to be conveyed in two directions through the inner row of blades and the outer row of blades, so that the water flow and pressure are more stable, impact on key equipment is reduced, different working condition requirements are better met, and the effect of improving the stability and reliability of a system is achieved.

Description

Technical Field

[0001] The invention relates to the technical field of nuclear power feed water pumps, in particular to a variable frequency speed regulation type starting feed water pump for a nuclear power station. Background Art

[0002] The startup feedwater pump in a nuclear power plant is an important auxiliary equipment, used to provide deoxygenated water to the steam generator during unit startup, shutdown and low-load operation to ensure a stable water supply for the primary coolant. The application of variable frequency speed regulation technology enables the startup feedwater pump to flexibly adjust the speed according to the actual working conditions, which not only improves the working efficiency of the pump, but also significantly reduces energy consumption and prolongs the service life of the equipment, which plays an important role in improving the overall operational reliability and economy of the nuclear power plant.

[0003] The patent publication number CN102606485A discloses a start-up feedwater pump for a nuclear power plant, including a stator component, a rotor component, two sets of mechanical seals, a mechanical seal flushing pipe and a bearing component. The stator component includes a pump body and a balance water pipe, and the rotor component includes a pump shaft, an impeller, an intermediate sealing sleeve, a rear sealing sleeve and a sleeve nut. The bearing component includes a front bearing, a rear bearing, an intermediate throttling bushing and a rear throttling bushing. The pump body is an axially split structure and is divided into a lower pump body at the bottom and an upper pump cover at the top through a horizontal center plane. The lower pump body and the upper pump cover are connected as a whole by a plurality of clamping bolts; the inner cavity of the pump body is provided with the first to fifth pressure water chambers in the low-pressure zone and the sixth to ninth pressure water chambers in the high-pressure zone. The balance water pipe is connected between the inlet and outlet located at the front and rear parts of the pump body; the impeller is composed of a nine-stage impeller, and the two sets of mechanical seals are respectively installed at the front and rear ends of the pump body; the mechanical seal flushing pipe is led out from the outlet of the first-stage pressure water chamber and connected to the two sets of mechanical seals respectively.

[0004] The prior art has the following defects: Unable to smoothly convert efficiency between low speed and high speed: The internal fluid dynamic characteristics and mechanical structure of the existing starting water pump perform differently at different speeds. The impeller and guide vane cannot effectively guide the water flow at low speed, resulting in reduced efficiency. When the speed changes, the efficiency curve of the pump will change suddenly or decrease, resulting in unstable water flow and affecting the normal operation of the system. This uneven change in efficiency will also increase energy consumption, increase equipment wear, and reduce safety and reliability. Therefore, it is necessary to set up a structure that can convert efficiency between low speed and high speed. At low speed, water is delivered by a single-stage water pump. During the process of increasing the speed, it is gradually converted to a multi-stage water pump to deliver water, so that the water flow and pressure are more stable, reducing the impact on key equipment, and better adapting to different working conditions. Requirements, to achieve the effect of improving system stability and reliability.

[0005] Insufficient water delivery capacity when used as a backup pump: When the existing starting water supply pump is used as a backup pump, its water flow and pressure are lower than the design values, which cannot meet the needs of the nuclear reactor cooling system. When the main pump fails or is under maintenance, it cannot timely or completely replace the function of the main pump, affecting the safe operation of the system, and then affecting the efficiency and stability of the generator, resulting in shutdown or load reduction operation, affecting the power generation capacity of the nuclear power plant. Therefore, it is necessary to add a reflux structure to increase the water delivery capacity of the starting water supply pump when it is used as a backup pump. When the main pump fails or is under maintenance, it can take over the task quickly and smoothly, reducing the system response time, improving safety, and achieving the effect of improving water delivery efficiency and stability. Summary of the invention

[0006] In view of the problems in the prior art such as the inability to smoothly convert the efficiency between low speed and high speed and the insufficient water delivery capacity when used as a backup pump, a variable frequency speed regulation starting feed water pump for nuclear power plants is proposed.

[0007] The present application provides a variable frequency speed regulating starting water supply pump for a nuclear power plant, the purpose of which is: through the provision of an auxiliary water supply component and a multi-stage impeller mechanism, water is supplied by a single-stage water pump at low speed, and in the process of increasing the speed, it is gradually converted into a multi-stage water pump for water supply, so that the water flow and pressure are more stable, thereby achieving the effect of improving the stability and reliability of the system; through the provision of the auxiliary water supply component and the regulating component, when the main pump fails or is under maintenance, the task can be taken over quickly and smoothly, thereby achieving the effect of improving the water supply efficiency and stability.

[0008] The technical solution of the present invention is: a variable frequency speed regulating starting water supply pump for a nuclear power plant, comprising a pump body, a driving shaft arranged inside the pump body, a speed regulating motor arranged at one end of the driving shaft, an auxiliary water delivery component arranged at one side of the pump body, and a multi-stage impeller mechanism and an adjusting component arranged inside the pump body, the top of the pump body is provided with a main water inlet and a main drain, the adjusting component is used to adjust the flow direction of water, the multi-stage impeller mechanism comprises a front impeller assembly and a plurality of rear impellers arranged between the pump body and the driving shaft, a plurality of sealing rings are fixedly installed inside the pump body, and a cavity assembly is arranged between the front impeller assembly, the plurality of rear impellers and the pump body; The pre-impeller assembly includes a pre-sealing block fixedly mounted on the inner wall of the pump body, and a pre-impeller body fixedly mounted on the outer wall of the drive shaft, the inner wall of the pre-sealing block is rotatably connected to the outer wall of the drive shaft, the outer wall of the pre-impeller body is rotatably connected to the inner wall of the pump body, and a plurality of support columns are fixedly connected to the outer walls of one side of the pre-impeller body close to the pre-sealing block, and the outer walls of the plurality of support columns are fixedly connected to inner row blades and outer row blades.

[0009] By adopting the above scheme, through the setting of the front impeller assembly, when the speed regulating motor runs at a low speed to drive the front impeller body to rotate, the inner row blades and the outer row blades can be used to divide the water flow into two parts and transport them in two directions. One part of the water flow is transported by the outer row blades to the auxiliary water delivery assembly, and the other part of the water flow is transported by the inner row blades to the cavity where the rear impeller is located, thereby converting the efficiency between low speed and high speed. At low speed, water is transported by a single-stage water pump. During the process of increasing the speed, it is gradually converted to multi-stage water pump water delivery, so that the water flow and pressure are more stable, the impact on key equipment is reduced, and the requirements of different working conditions are better adapted to achieve the effect of improving the stability and reliability of the system.

[0010] Furthermore, the cavity assembly includes a front cavity, an intermediate cavity and a rear cavity opened inside the pump body, the front cavity is arranged between the front sealing block and the front impeller body, the intermediate cavity is arranged between the front impeller body and multiple rear impellers, and the rear cavity is arranged between the rear impeller and the adjustment assembly.

[0011] Furthermore, the inner row blades and the outer row blades are both arranged inside the front cavity. When the multiple inner row blades rotate, the water flow in the front cavity can be transported to the middle cavity. When the multiple outer row blades rotate, the water flow in the front cavity can be transported to the auxiliary water delivery component.

[0012] By adopting the above scheme, the water flow in the front cavity is divided into two parts through the cavity assembly. One part of the water flow is transported to the auxiliary water delivery assembly, and the other part of the water flow is transported to the middle cavity. The water flow is transported to the auxiliary water delivery assembly to form a single-stage water pump and then transported to the rear cavity. The water flow is transported to the middle cavity to form a multi-stage water pump. When the speed of the speed regulating motor becomes faster, the middle cavity is connected to the rear cavity by adjusting the assembly, which is suitable for the needs of medium and high-pressure water supply in nuclear power plants.

[0013] Furthermore, the auxiliary water delivery assembly includes an auxiliary water inlet connecting pipe connected to the front cavity, and an auxiliary drainage connecting pipe connected to the rear cavity, and an auxiliary water delivery pipe is connected between the auxiliary water inlet connecting pipe and the auxiliary drainage connecting pipe.

[0014] Furthermore, the inner wall of the auxiliary water delivery pipe is rotatably connected to a water delivery auger, and one end of the water delivery auger is fixedly connected to an auxiliary driving motor.

[0015] By adopting the above scheme, through the auxiliary water delivery component, the water flow in the front cavity enters the auxiliary water delivery pipe through the auxiliary water inlet connecting pipe. At this time, the auxiliary drive motor is running in the forward direction, and the water delivery auger is driven by the output power of the auxiliary drive motor to rotate, thereby driving the water flow in the auxiliary water delivery pipe to the auxiliary drainage connecting pipe, and enters the rear cavity, and is finally discharged from the main drainage port, thereby forming a single-stage water pump. The single-stage water pump has a higher efficiency when started at a low speed and can quickly reach a stable operating state.

[0016] Furthermore, the adjustment assembly includes a rear sealing block fixedly mounted on the inner wall of the pump body, the outer wall of the rear sealing block is fixedly connected with a plurality of evenly distributed shrinkage tubes, the interior of the shrinkage tube is slidably connected with a push rod, and a shrinkage spring is fixedly connected between the push rod and the shrinkage tube.

[0017] Furthermore, the adjustment assembly also includes a plurality of evenly distributed second gaskets fixedly mounted on the inner wall of the pump body, the end of the push rod away from the shrinkage tube is fixedly connected to the first gasket, a hollow sealing block is arranged between the plurality of second gaskets and the plurality of first gaskets, and the hollow sealing block is rotatably sleeved on the outer wall of the drive shaft.

[0018] Furthermore, the inner wall of the hollow sealing block is fixedly connected to a plurality of inclined sliding cylinders, and the inner walls of the plurality of inclined sliding cylinders are rollingly connected to gravity balls. When the hollow sealing block rotates with the drive shaft, the gravity balls will move from one end of the inclined sliding cylinder close to the drive shaft to the end away from the drive shaft under the action of centrifugal force.

[0019] By adopting the above scheme, through the setting of the adjustment component, when the speed of the speed regulating motor is slow, the hollow sealing block is resisted by the push rod and the contraction spring in the contraction cylinder, thereby closing the middle cavity and the rear cavity; when the speed of the speed regulating motor becomes faster, the gravity ball inside the hollow sealing block moves from the end of the inclined sliding cylinder close to the drive shaft to the end away from the drive shaft under the action of centrifugal force, and squeezes the hollow sealing block under the impact of the water flow, so that the hollow sealing block approaches the contraction cylinder, thereby connecting the middle cavity and the rear cavity, thereby regulating the direction of the water flow.

[0020] Beneficial effects of the present invention: Through the auxiliary water delivery component and the multi-stage impeller mechanism, water flows from the main water inlet into the front cavity. The speed regulating motor runs at a low speed and drives the front impeller body and multiple rear impellers to rotate inside the pump body through the driving shaft. When the front impeller body rotates, the inner row blades and outer row blades can be used to divide the water flow into two parts and transport them in two directions. A part of the water flow is blocked by the outer row blades at the outer ring of the front cavity, close to the auxiliary water inlet connecting pipe, and is transported to the rear cavity by the auxiliary water delivery component, and finally discharged from the main drain port, thereby forming a single-stage water pump. The single-stage water pump has a higher efficiency when starting at a low speed and can quickly reach a stable operating state. Another part of the water flow is transported to the inner ring of the front cavity by the inner row blades and enters the middle cavity. Under the regulation of the regulating component, the middle cavity is connected with the rear cavity and finally discharged from the main drain port, thereby forming a multi-stage water pump, which makes the water flow and pressure more stable, reduces the impact on key equipment, better adapts to different working conditions, and achieves the effect of improving system stability and reliability.

[0021] Through the multi-stage impeller mechanism and adjustment components, when the speed of the speed regulating motor becomes faster, the gravity ball inside the hollow sealing block moves from the end of the inclined slide tube close to the drive shaft to the end away from the drive shaft under the action of centrifugal force, and squeezes the hollow sealing block under the impact of the water flow, so that the hollow sealing block approaches the contraction tube, thereby the middle cavity is connected with the rear cavity, and the water flow in the middle cavity flows into the rear cavity. At this time, the auxiliary drive motor is turned off, and the water flow in the auxiliary water pipe stops flowing. The water flow can only flow from the middle cavity and is finally discharged from the main drain port, thereby forming a multi-stage water pump. The multi-stage water pump can achieve a higher head and is suitable for the needs of medium and high pressure water supply in nuclear power plants.

[0022] By setting up auxiliary water supply components and regulating components, when used as a backup pump, the multi-stage water pump at this time cannot meet the needs of the nuclear reactor cooling system. The auxiliary drive motor can be run in reverse to return part of the water in the rear cavity to the front cavity through the auxiliary water supply pipe. The reflux can increase the inlet pressure of the water feed pump, reduce the risk of cavitation, and improve the reliability of the entire system. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a schematic diagram of the overall structure of the water supply pump of the present invention; Figure 2 A top view of the overall structure of the water supply pump of the present invention; Figure 3 It is a structural schematic diagram of the main water inlet and the main drain outlet of the present invention; Figure 4 It is a front view of the structure of the multi-stage impeller mechanism of the present invention; Figure 5 It is a structural schematic diagram of the front impeller assembly of the present invention; Figure 6 It is a structural schematic diagram of the rear impeller of the present invention; Figure 7 It is a structural schematic diagram of the cavity assembly of the present invention; Figure 8 It is a structural schematic diagram of the auxiliary water delivery component of the present invention; Fig. 9 It is a front view of the structure of the rear cavity of the present invention; Fig.10 For the present invention Fig. 9 The structural diagram of the enlarged part at A in the middle; Fig.11 It is a structural schematic diagram of the hollow sealing block of the present invention.

[0024] In the figure: 1. Pump body; 2. Drive shaft; 3. Speed ​​regulating motor; 4. Auxiliary water delivery assembly; 41. Auxiliary water inlet connecting pipe; 42. Auxiliary water delivery pipe; 43. Water delivery auger; 44. Auxiliary drainage connecting pipe; 45. Auxiliary drive motor; 5. Main water inlet; 6. Main drainage outlet; 7. Multi-stage impeller mechanism; 71. Pre-impeller assembly; 711. Pre-sealing block; 712. Pre-impeller body; 713. Support column; 714 , inner row blades; 715, outer row blades; 72, rear impeller; 73, sealing ring; 74, cavity assembly; 741, front cavity; 742, middle cavity; 743, rear cavity; 8, adjustment assembly; 81, rear sealing block; 82, contraction cylinder; 83, contraction spring; 84, push rod; 85, first gasket; 86, second gasket; 87, hollow sealing block; 88, inclined slide cylinder; 89, gravity ball. DETAILED DESCRIPTION

[0025] 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.

[0026] Reference Figure 1 - Fig.11 , provides a variable frequency speed regulating starting water supply pump for a nuclear power plant, comprising a pump body 1, a driving shaft 2 arranged inside the pump body 1, a speed regulating motor 3 arranged at one end of the driving shaft 2, an auxiliary water delivery component 4 arranged at one side of the pump body 1, and a multi-stage impeller mechanism 7 and an adjusting component 8 arranged inside the pump body 1, a main water inlet 5 and a main outlet 6 are opened on the top of the pump body 1, the adjusting component 8 is used to adjust the flow direction of water, the multi-stage impeller mechanism 7 comprises a front impeller assembly 71 and a plurality of rear impellers 72 arranged between the pump body 1 and the driving shaft 2, a plurality of sealing rings 73 are fixedly installed inside the pump body 1, and a cavity assembly 74 is arranged between the front impeller assembly 71, the plurality of rear impellers 72 and the pump body 1.

[0027] Reference Figure 4 - Figure 7 The pre-impeller assembly 71 includes a pre-sealing block 711 fixedly mounted on the inner wall of the pump body 1, and a pre-impeller body 712 fixedly mounted on the outer wall of the drive shaft 2. The inner wall of the pre-sealing block 711 is rotatably connected to the outer wall of the drive shaft 2, and the outer wall of the pre-impeller body 712 is rotatably connected to the inner wall of the pump body 1. A plurality of support columns 713 are fixedly connected to the outer wall of the pre-impeller body 712 close to the pre-sealing block 711, and the outer walls of the plurality of support columns 713 are all fixedly connected to inner row blades 714 and outer row blades 715.

[0028] Specifically, the rear impeller 72 can be set to multiple, and the sealing ring 73 is arranged inside the pump body 1 to seal the connection between the front impeller body 712 and the multiple rear impellers 72. The multiple inner row blades 714 and the outer row blades 715 are evenly distributed on the front impeller body 712 and connected through the support column 713. The function of the front sealing block 711 is to seal one end of the pump body 1 and form a water transfer cavity between it and the front impeller body 712.

[0029] Through the provision of the front impeller assembly 71, when the speed regulating motor 3 runs at a low speed to drive the front impeller body 712 to rotate, the inner row of blades 714 and the outer row of blades 715 can be used to divide the water flow into two parts and transport them in two directions. One part of the water flow is transported to the auxiliary water delivery assembly 4 by the outer row of blades 715, and the other part of the water flow is transported to the cavity where the rear impeller 72 is located by the inner row of blades 714, thereby converting the efficiency between low speed and high speed. At low speed, water is transported by a single-stage water pump, and in the process of increasing the speed, it is gradually converted into multi-stage water pump water delivery, so that the water flow and pressure are more stable, the impact on key equipment is reduced, and the requirements of different working conditions are better adapted to achieve the effect of improving the stability and reliability of the system.

[0030] Reference Figure 7 - Figure 8 The cavity assembly 74 includes a front cavity 741, an intermediate cavity 742 and a rear cavity 743 which are opened inside the pump body 1. The front cavity 741 is arranged between the front sealing block 711 and the front impeller body 712, the intermediate cavity 742 is arranged between the front impeller body 712 and the plurality of rear impellers 72, the rear cavity 743 is arranged between the rear impeller 72 and the adjusting assembly 8, the inner row blades 714 and the outer row blades 715 are both arranged inside the front cavity 741, and when the plurality of inner row blades 714 rotate, the water flow in the front cavity 741 can be transported to the intermediate cavity 742, and when the plurality of outer row blades 715 rotate, the water flow in the front cavity 741 can be transported to the auxiliary water delivery assembly 4.

[0031] Through the cavity assembly 74, the water flow in the front cavity 741 is divided into two parts. One part of the water flow is transported to the auxiliary water delivery assembly 4, and the other part of the water flow is transported to the middle cavity 742. The water flow is transported to the auxiliary water delivery assembly 4 to form a single-stage water pump and then transported to the rear cavity 743. The water flow is transported to the middle cavity 742 to form a multi-stage water pump. When the speed of the speed regulating motor 3 becomes faster, the middle cavity 742 is connected to the rear cavity 743 through the adjustment assembly 8, which is suitable for the needs of high-pressure water supply in nuclear power plants.

[0032] Reference Figure 8The auxiliary water delivery component 4 includes an auxiliary water inlet connecting pipe 41 connected to the front cavity 741, and an auxiliary drainage connecting pipe 44 connected to the rear cavity 743. An auxiliary water delivery pipe 42 is connected between the auxiliary water inlet connecting pipe 41 and the auxiliary drainage connecting pipe 44. The inner wall of the auxiliary water delivery pipe 42 is rotatably connected to a water delivery auger 43, and one end of the water delivery auger 43 is fixedly connected to an auxiliary driving motor 45.

[0033] Through the auxiliary water delivery component 4, the water flow in the front cavity 741 enters the auxiliary water delivery pipe 42 through the auxiliary water inlet connecting pipe 41. At this time, the auxiliary driving motor 45 is running in the forward direction, and the power output by the auxiliary driving motor 45 drives the water delivery auger 43 to rotate, driving the water flow in the auxiliary water delivery pipe 42 to the auxiliary drainage connecting pipe 44, and enters the rear cavity 743, and finally discharged from the main drainage port 6, thereby forming a single-stage water pump. The single-stage water pump has a higher efficiency when started at a low speed and can quickly reach a stable operating state.

[0034] Reference Fig. 9 - Fig.11 The adjusting assembly 8 includes a rear sealing block 81 fixedly mounted on the inner wall of the pump body 1, a plurality of uniformly distributed shrinkage cylinders 82 are fixedly connected to the outer wall of the rear sealing block 81, a push rod 84 is slidably connected inside the shrinkage cylinder 82, a shrinkage spring 83 is fixedly connected between the push rod 84 and the shrinkage cylinder 82, the adjusting assembly 8 also includes a plurality of uniformly distributed second gaskets 86 fixedly mounted on the inner wall of the pump body 1, a first gasket 85 is fixedly connected to one end of the push rod 84 away from the shrinkage cylinder 82, a hollow sealing block 87 is arranged between the plurality of second gaskets 86 and the plurality of first gaskets 85, the hollow sealing block 87 is rotatably sleeved on the outer wall of the drive shaft 2, a plurality of inclined slide cylinders 88 are fixedly connected to the inner wall of the hollow sealing block 87, a plurality of inclined slide cylinders 88 are rollingly connected to the inner walls of the plurality of inclined slide cylinders 88, and gravity balls 89 are rollingly connected to each other. When the hollow sealing block 87 rotates with the drive shaft 2, the gravity balls 89 will move from one end of the inclined slide cylinder 88 close to the drive shaft 2 to the other end away from the drive shaft 2 under the action of centrifugal force.

[0035] Specifically, the hollow sealing block 87 is sleeved on the outer wall of the driving shaft 2 and rotates with the driving shaft 2. At the same time, the hollow sealing block 87 can slide on the driving shaft 2 under the action of centrifugal force and water pressure. A first gasket 85 and a second gasket 86 are arranged on both sides of the hollow sealing block 87. The function of the gasket is to prevent the hollow sealing block 87 from being stuck and unable to move, and to reduce the friction between the hollow sealing block 87 and the inside of the pump body 1 or the push rod 84.

[0036] By setting the adjustment component 8, when the speed of the speed regulating motor 3 is slow, the hollow sealing block 87 is resisted by the push rod 84 and the contraction spring 83 in the contraction tube 82, thereby closing the intermediate cavity 742 and the rear cavity 743. When the speed of the speed regulating motor 3 becomes faster, the gravity ball 89 inside the hollow sealing block 87 moves from the end of the inclined slide tube 88 close to the drive shaft 2 to the end away from the drive shaft 2 under the action of centrifugal force, and squeezes the hollow sealing block 87 under the impact of the water flow, so that the hollow sealing block 87 approaches the contraction tube 82, thereby connecting the intermediate cavity 742 with the rear cavity 743, thereby regulating the direction of the water flow.

[0037] During use, water flows into the front cavity 741 from the main water inlet 5, and the speed regulating motor 3 runs at a low speed and drives the front impeller body 712 and multiple rear impellers 72 to rotate inside the pump body 1 through the driving shaft 2. When the front impeller body 712 rotates, the inner row blades 714 and the outer row blades 715 can be used to divide the water flow into two parts and transport them in two directions. A part of the water flow is blocked by the outer row blades 715 at the outer circle of the front cavity 741, close to the auxiliary water inlet connecting pipe 41, and is transported to the rear cavity 743 by the auxiliary water delivery component 4, and finally discharged from the main drain port 6, thereby forming a single-stage water pump. The single-stage water pump has a higher efficiency when starting at a low speed and can quickly reach a stable operating state; the other Part of the water flow is transported by the inner row of blades 714 to the inner circle of the front cavity 741 and enters the intermediate cavity 742. Under the regulation of the regulating assembly 8, the intermediate cavity 742 is connected with the rear cavity 743 and finally discharged from the main drain port 6, thereby forming a multi-stage water pump. The multi-stage water pump can achieve a higher head and is suitable for the needs of high-pressure water supply in nuclear power plants. When used as a backup pump, the multi-stage water pump at this time cannot meet the needs of the nuclear reactor cooling system, and the auxiliary drive motor 45 can be reversed to return part of the water in the rear cavity 743 to the front cavity 741 through the auxiliary water pipe 42. The reflux can increase the inlet pressure of the water supply pump, reduce the risk of cavitation, and improve the reliability of the entire system.

[0038] Working principle of the present invention: When the water pump is started, water flows into the front chamber 741 from the main water inlet 5, and the speed regulating motor 3 runs at a low speed to drive the front impeller body 712 and multiple rear impellers 72 to rotate inside the pump body 1 through the drive shaft 2.

[0039] When the front impeller body 712 rotates, the inner row blades 714 and the outer row blades 715 are arranged to divide the water flow into two parts and transport them in two directions. A part of the water flow is blocked by the outer row blades 715 at the outer ring of the front cavity 741, close to the auxiliary water inlet connecting pipe 41, and enters the auxiliary water delivery pipe 42 from the auxiliary water inlet connecting pipe 41. At this time, the auxiliary driving motor 45 is running in the forward direction, and the power output by the auxiliary driving motor 45 drives the water delivery auger 43 to rotate, driving the water flow in the auxiliary water delivery pipe 42 to the auxiliary drainage connecting pipe 44, and enters the rear cavity 743, and finally discharged from the main drainage port 6, thereby forming a single-stage water pump. The single-stage water pump has a higher efficiency when starting at a low speed and can quickly reach a stable operating state.

[0040] Another part of the water flow is transported by the inner row of blades 714 to the inner circle of the front cavity 741, and enters the intermediate cavity 742. After being transported by multiple rear impellers 72, it flows in the intermediate cavity 742 and finally reaches the side of the hollow sealing block 87 close to the rear impeller 72. When the speed of the speed regulating motor 3 is slow, the hollow sealing block 87 is resisted by the push rod 84 and the contraction spring 83 in the contraction tube 82, thereby closing the intermediate cavity 742 and the rear cavity 743.

[0041] When the speed of the speed regulating motor 3 becomes faster, the gravity ball 89 inside the hollow sealing block 87 moves from the end of the inclined slide tube 88 close to the drive shaft 2 to the end away from the drive shaft 2 under the action of centrifugal force, and squeezes the hollow sealing block 87 under the impact of the water flow, so that the hollow sealing block 87 approaches the contraction tube 82, thereby the intermediate cavity 742 is connected with the rear cavity 743, and the water flow in the intermediate cavity 742 flows into the rear cavity 743. At this time, the auxiliary drive motor 45 is turned off, and the water flow in the auxiliary water pipe 42 stops flowing. The water flow can only flow from the intermediate cavity 742 and is finally discharged from the main drain port 6, thereby forming a multi-stage water pump. The multi-stage water pump can achieve a higher head and is suitable for the needs of high-pressure water supply in nuclear power plants.

[0042] When used as a backup pump, the multi-stage water pump at this time cannot meet the needs of the nuclear reactor cooling system. The auxiliary drive motor 45 can be operated in reverse to return part of the water in the rear cavity 743 to the front cavity 741 through the auxiliary water pipe 42. The reflux can increase the inlet pressure of the water pump, reduce the risk of cavitation, and improve the reliability of the entire system.

[0043] 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 variable frequency speed regulating starting water supply pump for a nuclear power plant, comprising a pump body (1), a drive shaft (2) arranged inside the pump body (1), a speed regulating motor (3) arranged at one end of the drive shaft (2), an auxiliary water delivery component (4) arranged at one side of the pump body (1), and a multi-stage impeller mechanism (7) and an adjusting component (8) arranged inside the pump body (1), wherein a main water inlet (5) and a main water outlet (6) are provided at the top of the pump body (1), and the adjusting component (8) is used to adjust the flow direction of water, and is characterized in that: The multi-stage impeller mechanism (7) comprises a front impeller assembly (71) and a plurality of rear impellers (72) arranged between a pump body (1) and a drive shaft (2); a plurality of sealing rings (73) are fixedly mounted inside the pump body (1); and a cavity assembly (74) is arranged between the front impeller assembly (71), the plurality of rear impellers (72) and the pump body (1); The front impeller assembly (71) comprises a front sealing block (711) fixedly mounted on the inner wall of a pump body (1), and a front impeller body (712) fixedly mounted on the outer wall of a drive shaft (2); the inner wall of the front sealing block (711) is rotatably connected to the outer wall of the drive shaft (2); the outer wall of the front impeller body (712) is rotatably connected to the inner wall of the pump body (1); a plurality of support columns (713) are fixedly connected to an outer wall of the front impeller body (712) close to the front sealing block (711); and the outer walls of the plurality of support columns (713) are all fixedly connected to inner row blades (714) and outer row blades (715).

2. The variable frequency speed regulating starting water supply pump for a nuclear power plant according to claim 1, characterized in that: The cavity assembly (74) comprises a front cavity (741), an intermediate cavity (742) and a rear cavity (743) which are opened inside the pump body (1); the front cavity (741) is arranged between the front sealing block (711) and the front impeller body (712); the intermediate cavity (742) is arranged between the front impeller body (712) and the plurality of rear impellers (72); and the rear cavity (743) is arranged between the rear impeller (72) and the adjustment assembly (8).

3. The variable frequency speed regulating starting water supply pump for a nuclear power plant according to claim 2, characterized in that: The inner row blades (714) and the outer row blades (715) are both arranged inside the front cavity (741); when the plurality of inner row blades (714) rotate, the water flow in the front cavity (741) can be transported to the middle cavity (742); and when the plurality of outer row blades (715) rotate, the water flow in the front cavity (741) can be transported to the auxiliary water delivery assembly (4).

4. The variable frequency speed regulating starting water pump for a nuclear power plant according to claim 3, characterized in that: The auxiliary water delivery assembly (4) comprises an auxiliary water inlet connecting pipe (41) in communication with the front cavity (741), and an auxiliary drainage connecting pipe (44) in communication with the rear cavity (743); an auxiliary water delivery pipe (42) is in communication between the auxiliary water inlet connecting pipe (41) and the auxiliary drainage connecting pipe (44).

5. The variable frequency speed regulating starting water pump for a nuclear power plant according to claim 4, characterized in that: The inner wall of the auxiliary water delivery pipe (42) is rotatably connected to a water delivery auger (43), and one end of the water delivery auger (43) is fixedly connected to an auxiliary drive motor (45).

6. The variable frequency speed regulating starting water pump for a nuclear power plant according to claim 1, characterized in that: The regulating assembly (8) comprises a rear sealing block (81) fixedly mounted on the inner wall of the pump body (1); a plurality of evenly distributed shrinking cylinders (82) are fixedly connected to the outer wall of the rear sealing block (81); a push rod (84) is slidably connected to the interior of the shrinking cylinder (82); and a shrinking spring (83) is fixedly connected between the push rod (84) and the shrinking cylinder (82).

7. The variable frequency speed regulating starting water supply pump for a nuclear power plant according to claim 6, characterized in that: The adjustment assembly (8) further comprises a plurality of evenly distributed second gaskets (86) fixedly mounted on the inner wall of the pump body (1); an end of the push rod (84) away from the shrinking tube (82) is fixedly connected to a first gasket (85); a hollow sealing block (87) is provided between the plurality of second gaskets (86) and the plurality of first gaskets (85); the hollow sealing block (87) is rotatably sleeved on the outer wall of the drive shaft (2).

8. The variable frequency speed regulating starting water supply pump for a nuclear power plant according to claim 7, characterized in that: The inner wall of the hollow sealing block (87) is fixedly connected to a plurality of inclined slide cylinders (88), and the inner walls of the plurality of inclined slide cylinders (88) are all rollingly connected to gravity balls (89). When the hollow sealing block (87) rotates with the drive shaft (2), the gravity balls (89) move from one end of the inclined slide cylinder (88) close to the drive shaft (2) to the other end away from the drive shaft (2) under the action of centrifugal force.

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