Pumps for nuclear power plants

Abstract

The present invention relates to the technical field of nuclear power plant pumps, and discloses a nuclear power plant pump used in important plant water intake structures of AP1000 and CAP1400 nuclear power plants. The pump comprises a motor, a motor base, a pump support, an upper shaft, a middle shaft, a lower shaft, a shaft sleeve, a guide bearing, an upper protective pipe, a middle protective pipe, a lower protective pipe, an upper water pipe, a middle water pipe, a lower water pipe, a water outlet horn, a guide vane, an impeller, a pump cover and a filter screen. The pump support is an integrated structure, the upper end of the upper water pipe is connected to the bottom plate of the pump support through a flange, and a reinforcement ring is provided at the connection, which is connected to the lower end surface of the bottom plate after being matched with the outer circle and the lower end surface of the flange. The technical defects of the existing pump, that is, the upper water pipe and the upper shaft are easily broken, and the connection between the upper water pipe and the pump support is easily broken, are solved, the operational safety and reliability of the nuclear power plant pump are improved, the service life of the pump is extended, the operation, maintenance and repair costs of the pump are reduced, and the safe operation of the nuclear power plant is guaranteed.

Description

Technical Field

[0001] The present invention relates to the technical field of nuclear power plant pumps, and in particular to a nuclear power plant pump used in important plant water intake structures of AP1000 and CAP1400 nuclear power plants. Background Art

[0002] In AP1000 and CAP1400 nuclear power plants, the cooling method for nuclear power plant units is to use water pumps to pump seawater to cool the equipment to ensure the safe and stable operation of the nuclear power units. The seawater contains sediment and marine biological media, and the submerged length of the pump is ≥6 meters. The current pump technology used in nuclear power plants has some defects:

[0003] The weight and axial force of the pump's rotor are borne by the motor, causing high operating temperatures and bearing damage. The motor and upper shaft are connected via a rigid coupling to transmit torque, making installation of the motor and pump difficult and ensuring concentricity difficult. Improper installation can cause vibration in the pump and motor. If the pump itself vibrates, the rigid coupling can transmit vibration to the motor, damaging the motor. Seawater pumped by the pump can splash everywhere, polluting the environment and corroding other equipment. The elbow on the pump support is separate from the baseplate and the outer wall of the support, reducing the overall strength of the pump support. The water thrust generated during operation can cause alternating fatigue in the elbow and baseplate. The upper water pipe is unreinforced and connected to the elbow. The water thrust, combined with the rising and falling seawater vortices and lateral thrust of the water flow, can cause multiple alternating fatigue between the elbow and the upper water pipe, the water pipe, the bearing housing, and the joints of the water pipe. This can cause oscillation at the joints of the upper, middle, and lower water pipes, and eccentric vibration of the center shaft, which can wear the guide bearings and the center shaft. Because nuclear power plant pumps are suspended vertically, all water thrust and vibration forces generated on the upper baseplate of the pump support, as well as water thrust, seawater vortex forces, lateral thrust from seawater flow, and vibration forces generated on the lower baseplate, are concentrated at the bend in the pump support, causing multi-source fatigue fractures in the pump's upstream pipe and upper shaft. During operation, sediment from seawater can easily enter the intermediate coupling between the shafts, causing wear on the keys or threads on the coupling and shaft, resulting in damage to the intermediate coupling and shaft. The impeller is mounted on the lower shaft via a sleeve assembly and secured with an impeller nut. The impeller's weight and water thrust are borne entirely by the nut, which can easily damage it. When the pump is shut down, the backflow of seawater pumped by the pump, causing the impeller to reverse direction, can easily loosen and fall off, leading to accidents. The pump lacks or is insufficiently equipped with various detection probes, making it impossible to monitor the pump's operation in real time and identify any problems. This results in low pump safety and reliability, impacting the safe and stable operation of the nuclear power unit. Summary of the Invention

[0004] The purpose of the present invention is: the present invention provides a pump for a nuclear power plant to solve the technical problems that the upper water pipe and the upper shaft of the existing nuclear power plant pump are prone to multi-source fatigue fracture due to water thrust, and the connection between the upper water pipe and the pump support is prone to fracture.

[0005] In order to achieve the above-mentioned purpose, the present invention provides a pump for a nuclear power plant, comprising an electric motor, a motor base, a pump support, an upper shaft, a middle shaft, a lower shaft, a shaft sleeve, a guide bearing, an upper protective pipe, a middle protective pipe, a lower protective pipe, an upper water pipe, a middle water pipe, a lower water pipe, a water outlet horn, a guide vane, an impeller, a pump cover and a filter screen; the electric motor is arranged on the motor base and connected to the upper shaft, and the motor base is arranged on the pump support; the upper shaft, the middle shaft and the lower shaft are connected and fixed by an intermediate coupling assembly, and a bearing seat is provided below the intermediate coupling assembly; the shaft sleeve is sleeved on the upper shaft, The middle shaft or the lower shaft cooperates with the guide bearing; the upper protective tube, the middle protective tube, and the lower protective tube are correspondingly sleeved on the outer sides of the upper shaft, the middle shaft, and the lower shaft; the upper water pipe, the middle water pipe, and the lower water pipe are correspondingly sleeved on the outer sides of the upper protective tube, the middle protective tube, and the lower protective tube; the upper end of the upper water pipe is connected to the pump support, the lower end of the lower water pipe is connected to one end of the water outlet horn, and the other end of the water outlet horn is connected to the upper end of the guide vane; the impeller is connected to the lower shaft and cooperates with the guide vane; the lower end of the guide vane is connected to the pump cover, and the filter is connected to the guide vane or the pump cover;

[0006] in:

[0007] The pump support is an integrated structure, the upper end of the upper water pipe is connected to the bottom plate of the pump support through a flange, and a reinforcement ring is provided at the connection. The reinforcement ring cooperates with the outer circle and lower end face of the flange and is connected to the lower end face of the bottom plate.

[0008] In some embodiments of the present application, the upper water pipe includes an integrally manufactured pipe body, reinforcing ribs and flanges; the flanges are respectively provided at both ends of the pipe body, and the outer diameter of the flange provided at the upper end of the pipe body is larger than the flange provided at the lower end; the outer wall of the pipe body is axially provided with the reinforcing ribs.

[0009] In some embodiments of the present application, the intermediate coupling assembly includes two half couplings, a joint pin, a sealing strip, an end sealing ring, a bottom sealing ring, a side sealing ring, and a locking pin;

[0010] The two half-couplings are engaged at the connection between the upper shaft and the middle shaft, and the joint nail passes through both sides of the two half-couplings to complete the connection; a half groove is provided on the cross-section of the half-coupling at a position away from the joint nail, and the two opposite half grooves together form an axial groove, and the sealing strip is provided in the axial groove;

[0011] The end sealing rings are respectively installed on the two end surfaces of the half coupling through the locking pins. The end sealing ring is close to the surface of the end surface of the half coupling and is provided with a bottom ring groove at a position away from the locking pin, and the bottom sealing ring is arranged in the bottom ring groove; the end sealing ring is close to the side surface of the upper shaft or the middle shaft and is provided with a side ring groove, and the side sealing ring is arranged in the side ring groove.

[0012] In some embodiments of the present application, the bearing seat includes a base, a radial positioning ring and a radial pin;

[0013] The base is sleeved on the central axis, the central axis is provided with the shaft sleeve, and the guide bearing matched with the shaft sleeve is provided on the inner side of the base; the lower end of the upper protective tube is matched with the upper end surface of the base, and the upper end of the middle protective tube is matched with the lower end surface of the base; both ends of the upper water pipe and the middle water pipe are provided with flanges, the flange at the lower end of the upper water pipe is connected to the upper end surface of the base, and the flange at the upper end of the middle water pipe is connected to the lower end surface of the base;

[0014] The radial positioning ring is sleeved on the base, and the upper end face of the radial positioning ring is provided with an upper circular ring, and the lower end face is provided with a lower circular ring; the upper circular ring fits with the outer circular surface and the lower end face of the flange at the lower end of the upper water pipe, and the radial nail is used to pass through the upper circular ring to connect with the upper water pipe; the lower circular ring fits with the outer circular surface and the upper end face of the flange at the upper end of the middle water pipe, and the radial nail is used to pass through the lower circular ring to connect with the middle water pipe.

[0015] Some embodiments of the present application further include a thrust bearing assembly, wherein the thrust bearing assembly includes a thrust seat, a bearing support, a thrust bearing, a rolling bearing, a thrust sleeve, and a bearing gland;

[0016] The thrust seat sleeve is arranged on the upper shaft and connected to the pump support. The bearing support is arranged in the thrust seat and forms an inner cavity and an outer cavity with the inner inner wall and outer inner wall of the thrust seat respectively. The thrust bearing is arranged in the inner cavity; the thrust sleeve is arranged in the bearing support and cooperates with the thrust bearing, and the rolling bearing is arranged on the thrust sleeve; the bearing gland is installed on the bearing support after passing through the thrust sleeve and cooperating with the rolling bearing.

[0017] In some embodiments of the present application, the pump support includes an integrally manufactured support body, a base plate, a bent pipe, a first reinforcing rib, a second reinforcing rib, and a third reinforcing rib;

[0018] The bent pipe is arranged in the support body, the first reinforcing rib connects one side of the bent pipe with the inner wall of the support body, and the second reinforcing rib connects the other side of the bent pipe with the inner wall of the support body;

[0019] The bottom plate is arranged at the bottom of the support body, and the third reinforcing rib is arranged on the outer side surface of the support body and connected to the bottom plate.

[0020] In some embodiments of the present application, a sealing assembly is further provided on the pump support;

[0021] The sealing assembly includes a sealing seat, a shaft seal, a shaft seal cover and a transparent sealing cover;

[0022] The sealing seat is connected to the support body and the upper protective tube, the upper shaft sleeve is provided with the shaft sleeve, the guide bearing is arranged in the sealing seat, the shaft seal is arranged in the gap between the sealing seat and the upper shaft, and the shaft seal cover is arranged above the shaft seal; the transparent sealing cover is arranged above the shaft seal cover and connected to the shaft seal cover and the sealing seat to form a liquid collecting chamber.

[0023] In some embodiments of the present application, a cooling component is further provided on the pump support;

[0024] The cooling assembly includes a cooling coil, a drain pipe, a cooling pipe, a short pipe and a return pipe;

[0025] The cooling coil is arranged in the outer cavity, and the drain pipe is arranged in the pump support; one end of the cooling pipe is connected to the cooling coil, and the other end is connected to the liquid collecting cavity; one end of the short tube is connected to the liquid collecting cavity, and the other end is connected to the drain pipe; one end of the return pipe is connected to the cooling coil, and the other end is connected to the drain pipe.

[0026] In some embodiments of the present application, the pump support is further provided with an adjustment component;

[0027] The adjustment assembly includes an adjustment seat and an adjustment nut; the adjustment seat is provided on the upper shaft and is located above the thrust sleeve, and the adjustment nut passes through the adjustment seat and is connected to the thrust sleeve.

[0028] In some embodiments of the present application, the guide vane inner wall is provided with a mouth ring at the upper and lower parts, a throttle sleeve is provided at a predetermined position, and the guide bearing is provided below the throttle sleeve;

[0029] The lower shaft is provided with the shaft sleeve, and the lower shaft is inserted into the guide vane so that the shaft sleeve cooperates with the guide bearing and the throttle sleeve;

[0030] A first sand throwing ring is sleeved on the bottom of the shaft sleeve on the lower shaft, and a second sand throwing ring is sleeved on the upper part of the throttle sleeve on the lower shaft;

[0031] The impeller is located at the bottom of the first sand throwing ring, and a half-ring positioning block is sleeved on the bottom of the impeller on the lower shaft to fix the impeller on the lower shaft and make the impeller cooperate with the mouth ring;

[0032] The first sand throwing ring includes an annular disc portion provided on its upper end surface and an annular cover portion provided on its lower end surface; the annular disc portion includes, from the inside to the outside, a downwardly inclined section, a vertical section, a flat bottom section, and an upwardly inclined section, thereby forming a downwardly inclined groove shape on both sides; the annular cover portion includes, from the inside to the outside, an arc section and a downwardly inclined section, thereby forming an upwardly inclined convex groove shape on the outside;

[0033] The second sand throwing ring includes a lower cover portion provided on the lower end surface thereof, and the shape of the lower cover portion is the same as that of the ring cover portion.

[0034] Compared with the prior art, the pump for a nuclear power plant according to the embodiment of the present invention has the following beneficial effects:

[0035] The nuclear power plant pump provided by the present invention is primarily used in critical water intake structures of AP1000 and CAP1400 nuclear power plants. The pump's submerged length is ≥6 meters. This pump overcomes the technical drawbacks of existing pumps, such as the fragility of the upstream water pipe and upper shaft, as well as the fragility of the connection between the upstream water pipe and the pump support. This improves the operational safety and reliability of nuclear power plant pumps, extends the pump's service life, reduces pump operation, maintenance, and repair costs, and ensures the safe operation of the nuclear power plant. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0037] Figure 1 This is a schematic cross-sectional view of a pump for a nuclear power plant according to an embodiment of the present invention;

[0038] Figure 2 yes Figure 1 Enlarged view of point A in the middle;

[0039] Figure 3 yes Figure 1 Enlarged view of point B in the middle;

[0040] Figure 4 yes Figure 1 Enlarged view of point C in the middle;

[0041] Figure 5 yes Figure 2 A1 in the middle is an enlarged view;

[0042] Figure 6 This is a schematic diagram of the front view of the intermediate coupling assembly;

[0043] Figure 7 is a schematic diagram of the cross-sectional structure of the intermediate coupling assembly;

[0044] Figure 8 yes Figure 4 Enlarged view of C1 in the middle;

[0045] Figure 9 yes Figure 1 Enlarged view of point D in the middle;

[0046] Figure 10 This is a schematic diagram of the structure of the first sand throwing table;

[0047] In the figure, 1, electric motor; 2, motor base; 3, thrust bearing assembly; 31, thrust seat; 32, bearing support; 33, thrust bearing; 34, rolling bearing; 35, thrust sleeve; 36, bearing gland; 4, pump support; 5, pump shaft assembly; 51, pump shaft; 511, upper shaft; 512, middle shaft; 513, lower shaft; 52, bushing; 53, guide bearing; 54, protective tube; 541, upper protective tube; 542, middle protective tube; 543, lower protective tube; 55, water pipe; 551, upper Water pipe; 5510, reinforced ribs; 552, middle water pipe; 553, lower water pipe; 6, water outlet horn; 7, guide vane; 71, mouth ring; 72, throttle sleeve; 8, impeller; 9, guide cone; 10, pump cover; 11, filter screen; 12, sealing assembly; 121, sealing seat; 122, shaft seal; 123, shaft seal cover; 124, transparent sealing cover; 13, cooling assembly; 131, cooling coil; 132, drain pipe; 133, cooling pipe; 134, short pipe; 135, return pipe Flow tube; 14. Adjustment assembly; 141. Adjustment seat; 142. Adjustment nut; 15. First sand throwing ring; 151. Ring disk; 152. Ring cover; 16. Second sand throwing ring; 17. Half ring positioning block; 18. Bolt; 100. Elastic coupling; 110. Elastic motor coupling; 120. Elastic water pump coupling; 200. Intermediate coupling assembly; 201. Half coupling; 202. Joint nail; 203. Sealing strip; 204. End sealing ring; 205. Bottom sealing ring ; 206, side sealing ring; 207, locking pin; 300, bearing seat; 301, base; 302, radial locating ring; 303, radial pin; 304, upper ring; 305, lower ring; 400, vibration probe; 500, pressure probe; 600, temperature probe; 700, oil level gauge; 701, oil-blocking sleeve; 702, exhaust valve; 800, solenoid valve; 801, regulating valve; 802, external interface; 900, flange; 901, reinforcement ring; 902, connecting screws. DETAILED DESCRIPTION

[0048] The following embodiments of the present invention are described in further detail with reference to the accompanying drawings and examples. The following examples are used to illustrate the present invention but are not intended to limit the scope of the present invention.

[0049] In the description of the present invention, it should be understood that the terms "up", "down", "left", "right", "top", "bottom", etc., indicating directions or positional relationships, are based on the directions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore cannot be understood as a limitation on the present invention.

[0050] It should be understood that the terms "length", "width", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operate in a specific orientation, and therefore cannot be understood as limiting the present invention.

[0051] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of the technical features being referred to. Thus, a feature identified as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, "plurality" means two or more, unless otherwise specifically defined.

[0052] See also Figure 1 , is a nuclear power plant pump according to a preferred embodiment of the present invention, comprising a motor 1, a motor base 2, a thrust bearing assembly 3, a pump support 4, a pump shaft assembly 5, a water outlet horn 6, guide vanes 7, an impeller 8, a guide cone 9, a pump cover 10 and a filter screen 11.

[0053] The electric motor 1 is arranged on a motor base 2 , and the motor base 2 is connected to a pump support 3 .

[0054] The pump shaft assembly 5 includes a pump shaft 51, a shaft sleeve 52, a guide bearing 53, a protective tube 54, and a water supply pipe 55. The pump shaft 51 comprises an upper shaft 511, a middle shaft 512, and a lower shaft 513. The protective tube 54 comprises an upper protective tube 541, a middle protective tube 542, and a lower protective tube 543. The water supply pipe 55 comprises an upper water supply pipe 551, a middle water supply pipe 552, and a lower water supply pipe 553. The number of middle shafts 512 is ≥ 1, and the number of middle protective tubes 542 and middle water supply pipes 552 corresponds to the number of middle shafts 512. Multiple shaft sleeves 52 are mounted on the outer wall of the shaft. The number of guide bearings 53 corresponds to the number of shaft sleeves 52. Their specific installation positions are described in detail below.

[0055] See also Figure 2The output shaft of motor 1 is connected to upper shaft 511 via an elastic coupling 100. Specifically, elastic coupling 100 includes an elastic motor coupling 110 mounted on the output shaft of motor 1 and an elastic water pump coupling 120 mounted on upper shaft 511. Motor 1 is mounted and fixed to motor base 2 so that elastic motor coupling 110 and elastic water pump coupling 120 are matingly connected. Vibration probes 400 are installed axially and radially on motor base 2. Temperature probes 600 are installed at the top and bottom of motor 1. A pressure probe 500 is installed on pump support 5.

[0056] See also Figure 2 The pump support 4 includes an integrally manufactured support body 41, a base plate 42, a bend 43, a first reinforcing rib 44, a second reinforcing rib 45 and a third reinforcing rib 46. Specifically, the bend 43 is arranged in the support body 41, the first reinforcing rib 44 connects one side of the bend 43 to the inner wall of the support body 41, and the second reinforcing rib 45 connects the other side of the bend 43 to the inner wall of the support body 41. The base plate 42 is arranged at the bottom of the support body 41, and the third reinforcing rib 46 is arranged on the outer side surface of the support body 41 and connected to the base plate 42. The integrated manufacturing of the above components, that is, welding or casting the whole body together, forms an integral structure of the pump support 4, effectively improves the overall strength of the pump support 4, eliminates the hidden danger of alternating fatigue of the bend 43 and the base plate 42 caused by the water thrust generated during the operation of the pump, and ensures the safe operation of the pump.

[0057] See also Figure 2 and Figure 5 The thrust bearing assembly 3 includes a thrust seat 31, a bearing support 32, a thrust bearing 33, a rolling bearing 34, a thrust sleeve 35, and a bearing cover 36. The thrust seat 31 is sleeved on the upper shaft 511 and connected to the pump support 4. The bearing support 32 is disposed within the thrust seat 3 and forms an inner cavity and an outer cavity with the inner and outer walls of the thrust seat 31, respectively. The thrust bearing 33 is disposed within the inner cavity. The thrust sleeve 35 is disposed within the bearing support 32 and engages with the thrust bearing 33. The rolling bearing 34 is mounted on the thrust sleeve 35. The bearing cover 36 is mounted on the bearing support 32 after being passed through the thrust sleeve 35 and engaged with the rolling bearing 34.

[0058] See also Figure 2 The pump support 4 is also equipped with an oil level gauge 700, an oil blocking sleeve 701, an exhaust valve 702, and a temperature probe 600. The oil level gauge 700 is connected to the thrust seat 31. The oil blocking sleeve 701 is inserted into the thrust sleeve 62 and then fixed to the thrust seat 31. The exhaust valve 702 is installed on the bearing gland 36. The temperature probe 600 passes through the bearing gland 36 and is installed on the bearing support 32.

[0059] See also Figure 2 and Figure 5The upper shaft 511 is provided with a sealing assembly 12 connected to the pump support 4. The sealing assembly 12 includes a sealing seat 121, a shaft seal 122, a shaft seal cover 123 and a transparent sealing cover 124. The sealing seat 121 is inserted through the upper shaft 511 and connected to the support body 41 and the upper protective tube 541. The upper shaft 511 is provided with a shaft sleeve 52. The guide bearing 53 is provided in the sealing seat 121, and the shaft sleeve 52 cooperates with the guide bearing 53. The shaft seal 122 is inserted through the upper shaft 511 and is provided in the gap between the sealing seat 121 and the upper shaft 511 and cooperates with the shaft sleeve 53. The shaft seal cover 123 is provided above the shaft seal 122. The transparent sealing cover 124 is provided above the shaft seal cover and connected to the shaft seal cover 123 and the sealing seat 121, forming a liquid collecting chamber to prevent the seawater pumped by the pump from splashing around and to allow the leakage of the shaft seal 122 to be observed at any time. Two temperature probes 600 are also provided on the seal seat 121, one of which contacts the shaft seal 122, and the other contacts the guide bearing 53. The prior art seal assembly has insufficient sealing performance and lacks a sealing cover. As a result, seawater pumped by the pump splashes everywhere, causing environmental pollution and corrosion of other equipment. The seal assembly 12 of the present application overcomes these problems.

[0060] See also Figure 2 and Figure 5 The pump support 4 also incorporates a cooling assembly 13. This assembly includes a cooling coil 131, a drain pipe 132, a cooling tube 133, a short tube 134, and a return pipe 135. The cooling coil 131 is located in the outer cavity formed between the bearing support 32 of the thrust bearing assembly 3 and the outer and inner walls of the thrust seat 3. The drain pipe 132 is located within the pump support 4. The cooling tube 133 passes through the motor base 2 and is then mounted on the thrust seat 31. Its ends are connected to the cooling coil 131 and the liquid collection chamber, respectively. The cooling tube 133 is equipped with a solenoid valve 800, a regulating valve 801, a pressure probe 500, and an external port 802. One end of the short tube 134 is connected to the liquid collection chamber, and the other end is connected to the drain pipe 132. The return pipe 135 passes through the motor base 2 and is then mounted on the thrust seat 31. Its ends are connected to the cooling coil 131 and the drain pipe 132, respectively. The return pipe 135 is equipped with a temperature probe 600.

[0061] See also Figure 2 and Figure 5 The pump support 4 also incorporates an adjustment assembly 14, comprising an adjustment seat 141 and an adjustment nut 142. The adjustment seat 141 is sleeved onto the upper shaft 511 and positioned above the thrust sleeve 35. The adjustment nut 142 passes through the adjustment seat 141 and is connected to the thrust sleeve 35. Rotating the adjustment nut 142 allows the upper shaft 511 to move up and down relative to the pump support 4, thereby adjusting the axial position of the impeller 8 and ensuring proper fit between the impeller 8 and the guide vanes 7. Once the impeller 8 is positioned correctly, the adjustment nut 142 is screwed onto the thrust sleeve 35.

[0062] See also Figure 1 The upper shaft 511 and the middle shaft 512, the middle shaft 512 and the middle shaft 512, and the middle shaft 512 and the lower shaft 513 are all connected and fixed via the intermediate coupling assembly 200, and the bearing seat 300 is sleeved below the intermediate coupling assembly 200. The ends of the upper water pipe 551 are respectively connected to the sealing seat 121 and the bearing seat 300 in the pump support 4, the ends of the middle water pipe 552 are respectively connected to the bearing seat 300, and the ends of the lower water pipe 553 are respectively connected to the bearing seat 300 and the water outlet speaker 6.

[0063] See also Figure 6 and Figure 7 The intermediate coupling assembly 200 includes two half-couplings 201, a coupling pin 202, a sealing strip 203, an end sealing ring 204, a bottom sealing ring 205, a side sealing ring 206 and a locking pin 207. The structure and assembly method of the intermediate coupling assembly 200 are described below using the connection between the upper shaft 511 and the middle shaft 512 as an example. The two half-couplings 201 are engaged at the connection between the upper shaft 511 and the middle shaft 512, and the coupling pin 202 passes across both sides of the two half-couplings 201 to complete the connection. A half groove 208 is provided on the cross-section of the half-coupling 201 at a position away from the coupling pin 202. The two opposite half grooves 208 together form an axial groove, and the sealing strip 203 is provided in the axial groove. During actual installation, first place one half-coupling 201 onto the shaft, then insert the sealing strip 203 into the half-groove 208. Then, align the other half-coupling 201 and secure the two half-couplings 201 using the coupling pins 202 (screws). The end sealing rings 204 are attached to the two end faces of the half-coupling 201 using the locking pins 207 (screws). A bottom ring groove is defined on the surface of the end sealing ring 204, which is located close to the end face of the half-coupling 201, away from the locking pins 207. The bottom sealing ring 205 is located within the bottom ring groove. Side ring grooves are defined on the side of the end sealing ring 204, which is close to the upper shaft 511 or the middle shaft 512. Side sealing rings 206 are located within the side ring grooves. Both the coupling pins 202 and the locking pins 207 are coated with sealant. The existing intermediate coupling lacks a sealing structure, allowing mud and sand from seawater to easily enter the intermediate coupling, causing wear on the keys or threads on the coupling and shaft, leading to damage to the intermediate coupling and shaft. The above-described technical solution ensures that mud and sand and other impurities cannot enter the keyway of the intermediate coupling, protecting the keys from wear. Furthermore, the end seal ring 204 helps radially reinforce the intermediate coupling.

[0064] See also Figure 1 and Figure 3A bearing seat 300 is provided below the intermediate coupling assembly 200. Taking the bearing seat 300 located below the intermediate coupling assembly 200 connecting the upper shaft 511 and the middle shaft 512 as an example, the bearing seat 300 comprises a base 301, a radial locating ring 302, and radial pins 303. The base 301 is sleeved onto the middle shaft 512. A shaft sleeve 52 is provided on the outside of the middle shaft 512. A guide bearing 53, which mates with the sleeve 52, is provided on the inside of the base 301. The lower end of the upper protective tube 541 mates with the upper end surface of the base 301, while the upper end of the middle protective tube 542 mates with the lower end surface of the base 301. Both the upper and middle water pipes 551 and 552 are provided with flanges 900. The lower end of the upper water pipe 551 is connected to the upper end surface of the base 301, while the upper end of the middle water pipe 552 is connected to the upper end surface of the base 301. The radial locating ring 302 is sleeved onto the base 301. An upper ring 304 is provided on the upper end surface of the radial locating ring 302, and a lower ring 305 is provided on the lower end surface. The upper ring 304 mates with the outer circumference and lower end surface of the flange 900 at the lower end of the upper water supply pipe 551, and is connected to the upper water supply pipe 551 via radial nails 303 passing through the upper ring 304. The lower ring 505 mates with the outer circumference and upper end surface of the flange 900 at the upper end of the middle water supply pipe 552, and is connected to the middle water supply pipe 552 via radial nails 303 passing through the lower ring 305. This effectively enhances the radial positioning of the upper and middle water supply pipes 551, improving their overall strength and concentricity, and ensuring safe operation of the pump. Furthermore, a temperature probe 600 and a vibration probe 400 are provided radially on the radial locating ring 302, respectively. The temperature probe 600 contacts the guide bearing 53, and a vibration probe 400 is provided axially on the radial locating ring 302.

[0065] See also Figure 1 and Figure 3 The upper water pipe 551 comprises an integrally manufactured pipe body, reinforcing ribs 5510, and flanges 900 at each end. The outer wall of the pipe body is provided with reinforcing ribs 5510 along the axial direction. The outer diameter of the flange 900 at the upper end of the pipe body is larger than that of the flange 900 at the lower end of the pipe body. The flange 900 at the upper end of the pipe body is connected to the base plate 42, and a reinforcing ring 901 is provided at the connection. The reinforcing ring 901 mates with the outer circumference and lower end surface of the flange 900 and is mounted to the lower end surface of the base plate using connecting bolts 902. This integrated manufacturing refers to the integral connection through welding or casting. During actual installation, the pump support 4 is put over the upper shaft 511 and the upper protective tube 541, so that the bottom plate 42 and the upper water pipe 551 are matched and then fixed with bolts. The reinforcement ring 901 is pushed up so that it is matched with the lower end face of the bottom plate 42, the outer circle and the lower end face of the flange 900 at the same time, and is connected and fixed to the lower end face of the bottom plate 42 with connecting bolts 902, so that the flange 900, the bottom plate 42 and the reinforcement ring 901 form a whole, and the upper water pipe 551 is fixed axially and radially to improve the overall strength and ensure the safe operation of the pump.

[0066] See also Figure 1 、 Figure 4 and Figure 8 The impeller 8 is connected to the lower outer wall of the lower shaft 513, and the guide vane 7 is matingly connected to the impeller 8. Specifically, a ring 71 is provided at the upper and lower portions of the inner wall of the guide vane 7, a throttle sleeve 72 is provided at a predetermined position, and a guide bearing 53 is provided below the throttle sleeve 72. The lower shaft 513 is provided with a sleeve 52, which is inserted into the guide vane 7 so that the sleeve 52 mates with the guide bearing 53 and the throttle sleeve 72. A temperature probe 600 is provided to contact the guide bearing 53. A first sand throwing ring 15 is mounted on the bottom of the sleeve 52 on the lower shaft 513, and a second sand throwing ring 16 is mounted on the lower shaft 513 above the throttle sleeve 72. Impeller 8 is located at the bottom of first sand slinging ring 15. A semi-ring locating block 17 is sleeved on lower shaft 513 at the bottom of impeller 8. Semi-ring locating block 17 is snapped onto lower shaft 513, inserted into the axial hole of impeller 8, and then bolted to impeller 8. This independently secures impeller 8, first sand slinging ring 15, and shaft sleeve 52 to lower shaft 513. Specifically, the keyway of impeller 8 is axially sealed by semi-ring locating block 17 and first sand slinging ring 15, ensuring that impeller 8 engages with mouth ring 71. Multiple impellers 8 and guide vanes 7 can be provided, arranged in a row, with adjacent guide vanes 7 connected by bolts 18.

[0067] In the prior art, the impeller and the impeller are mounted on the lower shaft via a sleeve assembly and then locked with an impeller nut. All the impeller weight and water thrust are borne entirely by the impeller nut, which can easily cause damage to the impeller nut. When the pump is shut down, the seawater pumped backflows and the impeller reverses, which can easily cause the impeller nut to loosen and fall off, causing an accident. The above-mentioned solution of the present application can overcome this problem.

[0068] See also Figure 9 The guide cone 9 is mounted on the bottom of the lower shaft 513 and secured to the lower shaft 513 with screws after engaging the half-ring positioning block 17. The pump cover 10 is placed over the impeller 8, ensuring that the mouth ring 71 engages with the impeller 8. The pump cover 10 is then connected and secured to the guide vane 7. A vibration probe 400 is installed at the connection. The filter screen 11 is then mounted and secured to the guide vane 7 or the pump cover 10.

[0069] For details, see Figure 10 The first sand throwing ring 15 includes a ring disk portion 151 provided on its upper end surface and a ring cover portion 152 provided on its lower end surface. The ring disk portion 151 includes a downwardly inclined section, a vertical section, a flat bottom section, and an upwardly inclined section from the inside to the outside, thereby forming a downwardly inclined groove shape on both sides. The ring cover portion 152 includes an arc section and a downwardly inclined section from the inside to the outside, thereby forming an upwardly inclined convex groove shape on the outside. Figure 8The second sand slinging ring 16 includes a lower cover portion located on its lower end surface. The lower cover portion has the same shape as the annular cover portion 152. Specifically, the annular cover portion 152 is oriented toward the impeller 8, the annular disc portion 151 is oriented toward the guide bearing 53, and the lower cover portion of the second sand slinging ring 16 is oriented toward the guide bearing 53. When the pump is operating, the first and second sand slinging rings 15 and 16 rotate together with the impeller 8 and the lower shaft 513. The annular cover portion 152 generates centrifugal force to rotate the seawater, preventing silt and other impurities in the seawater from flowing upward into the guide bearing 53. The lower cover portion prevents silt and other impurities in the seawater from flowing downward into the throttle sleeve 77, thereby ensuring the normal operation of the guide bearing 53, the shaft sleeve 52, and the throttle sleeve 72. For a period of time after the pump stops running, the seawater in the cavity on the impeller 8 and inside the guide vane 7 will rotate slightly. The annular disc portion 151 prevents the mud and sand in the slightly rotating seawater from entering the guide bearing 53. After the seawater stops rotating, a very small amount of mud and sand and other impurities in the seawater are collected by the annular disc portion 151. When the pump starts running again, the annular disc portion 151 generates centrifugal force to rotate the seawater and throw the very small amount of mud and sand and other impurities in the annular disc portion 151 out of the annular disc portion 151, preventing impurities from entering the cavity on the impeller 8 and inside the guide vane 7, thereby ensuring the normal use of the guide bearing 53, the shaft sleeve 52 and the throttle sleeve 72.

[0070] The above-mentioned probes (vibration probe 400, pressure probe 500 and temperature probe 600) and valves are connected to the computer in the central control room of the power plant through wires. They can monitor the operation of the pump in real time, determine the problem of the pump, ensure the safe operation of the pump, and ensure the safe operation of the nuclear power plant.

[0071] In summary, the present invention proposes a nuclear power plant pump, which is mainly used in important water intake structures of AP1000 and CAP1400 nuclear power plants. The pump has a submerged length of ≥6 meters. Compared with the existing technology, its beneficial effects are:

[0072] 1. The motor and the upper shaft are connected to transmit torque through an elastic coupling, which effectively ensures the concentricity of the motor output shaft and the pump shaft. A thrust bearing assembly is also provided to prevent the motor of the nuclear power plant pump from bearing the axial force of the pump.

[0073] 2. The upper shaft, middle shaft and lower shaft are connected by an intermediate coupling assembly with good sealing performance, which can ensure that no impurities such as mud and sand will enter the keyway in the intermediate coupling, ensure that the flat key will not wear, and help to radially reinforce the intermediate coupling.

[0074] Third, the pump support is manufactured in an integrated manner, forming a monolithic structure that effectively improves the overall strength of the pump support and eliminates the potential risk of alternating fatigue between the elbow and the baseplate caused by the hydraulic thrust generated during pump operation. The upward water pipe is also manufactured in an integrated manner, and a reinforcement ring is installed at the connection with the pump support to axially and radially secure the upward water pipe, improving the overall strength and ensuring safe operation of the pump. This solves the technical defects of existing pumps, such as the upward water pipe and upper shaft being easily broken, and the connection between the upward water pipe and the pump support being easily broken.

[0075] 4. The sealing assembly on the pump support is equipped with a transparent sealing cover to form a liquid collecting chamber to prevent the seawater pumped by the pump from splashing everywhere and the leakage of the shaft seal can be observed at any time.

[0076] 5. The pump support is also integrated with a cooling component to ensure good cooling effect.

[0077] 6. The pump support is also integrated with an adjustment component, which can adjust the axial position of the impeller to ensure good cooperation between the impeller and the guide vane.

[0078] 7. A radial positioning ring is provided on the bearing seat to effectively enhance the radial positioning of the water pump connection, improve its overall strength and concentricity, and ensure the safe operation of the pump.

[0079] 8. The throttle sleeves of the impeller and guide vane are equipped with sand throwing rings, and semi-ring positioning blocks. The impeller, sand throwing ring and shaft sleeve are independently fixed on the lower shaft, which helps to axially seal the impeller. The sand throwing ring effectively prevents impurities such as mud and sand in seawater from entering the throttle sleeve and guide bearing, thereby ensuring the normal operation of the equipment.

[0080] 9. The pump is equipped with vibration probes, pressure probes and temperature probes in multiple locations, which can monitor the operation of the pump in real time and determine where the problem lies.

[0081] In summary, the motor of the nuclear power plant pump provided by the present invention does not bear the axial force of the pump, and the motor and the upper shaft are connected by an elastic coupling to transmit torque; the probes and valves configured on the pump are connected to the computer in the power plant's central control room, which can monitor the operation of the pump in real time and determine the problem of the pump. The nuclear power plant pump provided by the present invention solves the technical defects of existing pumps such as high vibration and noise during operation, easy wear of the motor bearings, easy splashing and leakage of the pumped medium, serious wear of the intermediate coupling, guide bearings and upper, middle and lower shafts, swinging of the connection between the upper, middle and lower water pipes, easy loosening of the elbow and bottom plate on the pump support, and easy breakage of the upper water pipe and upper shaft; it improves the operational safety and reliability of the nuclear power plant pump, extends the service life of the pump, reduces the operation, maintenance and repair costs of the pump, and ensures the safe operation of the nuclear power plant.

[0082] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and substitutions can be made without departing from the technical principles of the present invention. These improvements and substitutions should also be regarded as the scope of protection of the present invention.

Claims

1. Pumps for nuclear power plants, including electric motors, motor bases, pump supports, upper shafts, middle shafts, lower shafts, bushings, guide bearings, upper protective pipes, middle protective pipes, lower protective pipes, upper water pipes, middle water pipes, lower water pipes, water outlet horns, guide vanes, impellers, pump covers, and strainers; The motor is arranged on the motor seat and connected to the upper shaft, and the motor seat is arranged on the pump support; the upper shaft, the middle shaft and the lower shaft are connected and fixed by an intermediate coupling assembly, and a bearing seat is provided below the intermediate coupling assembly; the shaft sleeve is sleeved on the upper shaft, the middle shaft or the lower shaft and cooperates with the guide bearing; the upper protective pipe, the middle protective pipe and the lower protective pipe are correspondingly sleeved on the outer side of the upper shaft, the middle shaft and the lower shaft; the upper water pipe, the middle water pipe and the lower water pipe are correspondingly sleeved on the outer side of the upper protective pipe, the middle protective pipe and the lower protective pipe; The upper end of the upper water pipe is connected to the pump support, the lower end of the lower water pipe is connected to one end of the water outlet horn, and the other end of the water outlet horn is connected to the upper end of the guide vane; the impeller is connected to the lower shaft and cooperates with the guide vane; the lower end of the guide vane is connected to the pump cover, and the filter is connected to the guide vane or the pump cover; Its characteristics are: The pump support is an integrated structure, the upper end of the upper water pipe is connected to the bottom plate of the pump support through a flange, and a reinforcement ring is provided at the connection, and the reinforcement ring is matched with the outer circle and lower end surface of the flange and then connected to the lower end surface of the bottom plate; The output shaft of the motor is connected to the upper shaft via an elastic coupling, wherein the elastic coupling includes an elastic motor coupling mounted on the output shaft of the motor and an elastic water pump coupling mounted on the upper shaft, and the motor is mounted and fixed on the motor base so that the elastic motor coupling and the elastic water pump coupling are cooperatively connected; The upper and lower parts of the inner wall of the guide vane are respectively provided with mouth rings, a throttling sleeve is provided at a predetermined position, and the guide bearing is provided below the throttling sleeve; The lower shaft is provided with the shaft sleeve, and the lower shaft is inserted into the guide vane so that the shaft sleeve cooperates with the guide bearing and the throttle sleeve; A first sand throwing ring is sleeved on the bottom of the shaft sleeve on the lower shaft, and a second sand throwing ring is sleeved on the upper part of the throttle sleeve on the lower shaft; The impeller is located at the bottom of the first sand throwing ring, and a half-ring positioning block is sleeved on the bottom of the impeller on the lower shaft to fix the impeller on the lower shaft and make the impeller cooperate with the mouth ring; The first sand throwing ring includes an annular disc portion provided on its upper end surface and an annular cover portion provided on its lower end surface; the annular disc portion includes, from the inside to the outside, a downwardly inclined section, a vertical section, a flat bottom section, and an upwardly inclined section, thereby forming a downwardly inclined groove shape on both sides; the annular cover portion includes, from the inside to the outside, an arc section and a downwardly inclined section, thereby forming an upwardly inclined convex groove shape on the outside; The second sand throwing ring includes a lower cover portion provided on the lower end surface thereof, and the shape of the lower cover portion is the same as that of the ring cover portion.

2. The nuclear power plant pump according to claim 1, characterized in that: The upper water pipe includes an integrally manufactured pipe body, reinforcing ribs and flanges; the flanges are respectively provided at both ends of the pipe body, and the outer diameter of the flange provided at the upper end of the pipe body is larger than the flange provided at the lower end; the outer wall of the pipe body is axially provided with the reinforcing ribs.

3. The nuclear power plant pump according to claim 1, characterized in that: The intermediate coupling assembly includes two half couplings, a joint pin, a sealing strip, an end sealing ring, a bottom sealing ring, a side sealing ring and a locking pin; The two half-couplings are engaged at the connection between the upper shaft and the middle shaft, and the joint nail passes through both sides of the two half-couplings to complete the connection; a half groove is provided on the cross-section of the half-coupling at a position away from the joint nail, and the two opposite half grooves together form an axial groove, and the sealing strip is provided in the axial groove; The end sealing rings are respectively installed on the two end surfaces of the half coupling through the locking pins. The end sealing ring is close to the surface of the end surface of the half coupling and is provided with a bottom ring groove at a position away from the locking pin, and the bottom sealing ring is arranged in the bottom ring groove; the end sealing ring is close to the side surface of the upper shaft or the middle shaft and is provided with a side ring groove, and the side sealing ring is arranged in the side ring groove.

4. The nuclear power plant pump according to claim 1, characterized in that: The bearing seat includes a base, a radial positioning ring and radial nails; The base is sleeved on the central axis, the central axis is provided with the shaft sleeve, and the guide bearing matched with the shaft sleeve is provided on the inner side of the base; the lower end of the upper protective tube is matched with the upper end surface of the base, and the upper end of the middle protective tube is matched with the lower end surface of the base; both ends of the upper water pipe and the middle water pipe are provided with flanges, the flange at the lower end of the upper water pipe is connected to the upper end surface of the base, and the flange at the upper end of the middle water pipe is connected to the lower end surface of the base; The radial positioning ring is sleeved on the base, and the upper end face of the radial positioning ring is provided with an upper circular ring, and the lower end face is provided with a lower circular ring; the upper circular ring fits with the outer circular surface and the lower end face of the flange at the lower end of the upper water pipe, and the radial nail is used to pass through the upper circular ring to connect with the upper water pipe; the lower circular ring fits with the outer circular surface and the upper end face of the flange at the upper end of the middle water pipe, and the radial nail is used to pass through the lower circular ring to connect with the middle water pipe.

5. The nuclear power plant pump according to claim 1, characterized in that: Also included is a thrust bearing assembly, which includes a thrust seat, a bearing support, a thrust bearing, a rolling bearing, a thrust sleeve and a bearing gland; The thrust seat sleeve is arranged on the upper shaft and connected to the pump support. The bearing support is arranged in the thrust seat and forms an inner cavity and an outer cavity with the inner inner wall and outer inner wall of the thrust seat respectively. The thrust bearing is arranged in the inner cavity; the thrust sleeve is arranged in the bearing support and cooperates with the thrust bearing, and the rolling bearing is arranged on the thrust sleeve; the bearing gland is installed on the bearing support after passing through the thrust sleeve and cooperating with the rolling bearing.

6. The nuclear power plant pump according to claim 5, characterized in that: The pump support comprises an integrally manufactured support body, a base plate, a bent pipe, a first reinforcing rib, a second reinforcing rib and a third reinforcing rib; The bent pipe is arranged in the support body, the first reinforcing rib connects one side of the bent pipe with the inner wall of the support body, and the second reinforcing rib connects the other side of the bent pipe with the inner wall of the support body; The bottom plate is arranged at the bottom of the support body, and the third reinforcing rib is arranged on the outer side surface of the support body and connected to the bottom plate.

7. The nuclear power plant pump according to claim 6, characterized in that: The pump support is also provided with a sealing assembly; The sealing assembly includes a sealing seat, a shaft seal, a shaft seal cover and a transparent sealing cover; The sealing seat is connected to the support body and the upper protective tube, the upper shaft sleeve is provided with the shaft sleeve, the guide bearing is arranged in the sealing seat, the shaft seal is arranged in the gap between the sealing seat and the upper shaft, and the shaft seal cover is arranged above the shaft seal; the transparent sealing cover is arranged above the shaft seal cover and connected to the shaft seal cover and the sealing seat to form a liquid collecting chamber.

8. The nuclear power plant pump according to claim 7, characterized in that: The pump support is also provided with a cooling assembly; The cooling assembly includes a cooling coil, a drain pipe, a cooling pipe, a short pipe and a return pipe; The cooling coil is arranged in the outer cavity, and the drain pipe is arranged in the pump support; one end of the cooling pipe is connected to the cooling coil, and the other end is connected to the liquid collecting cavity; one end of the short tube is connected to the liquid collecting cavity, and the other end is connected to the drain pipe; one end of the return pipe is connected to the cooling coil, and the other end is connected to the drain pipe.

9. The nuclear power plant pump according to claim 6, characterized in that: The pump support is also provided with an adjustment component; The adjustment assembly includes an adjustment seat and an adjustment nut; the adjustment seat is provided on the upper shaft and is located above the thrust sleeve, and the adjustment nut passes through the adjustment seat and is connected to the thrust sleeve.

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