Emergency suction system for cold source blocking net of nuclear power station

Abstract

The invention relates to the technical field of nuclear power cold source water intake trash holding, in particular to a nuclear power station cold source blocking net emergency suction system. A plurality of floating net bags are arranged on the sea surface to form an effective blocking net wall, floating objects on a drifting path can be rapidly collected and intercepted, the floating objects are prevented from entering a cold source area of the nuclear power station, and safe operation of the nuclear power station is ensured. Each net bag is connected with the suction pipe through the branch pipe, and the gate valve is arranged on the branch pipe, so that the suction operation of each net bag can be flexibly controlled, and the flexibility and the reliability of the system are improved. And the large-channel suction centrifugal pump and the solid-liquid separator are combined for use, so that intercepted floating objects can be effectively sucked and treated, and a cold source area is kept clean and smooth.

Description

Technical Field

[0001] The invention relates to the technical field of pollution interception at a nuclear power cold source water intake, in particular to an emergency suction system for a cold source interception net of a nuclear power plant. Background Art

[0002] In recent years, the nuclear power plant's cooling water intake has repeatedly experienced seasonal marine organism outbreaks and blockages caused by floating marine debris, triggering operational alarms.

[0003] At present, nuclear power plants often use the method of "net bag interception + manual offshore fishing boat barge cleaning" to deal with it. This method is inefficient. During the period of superimposed marine organism outbreaks, manual barge cleaning by fishing boats cannot effectively guarantee the safe operation of nuclear power plants. In the existing public technology, there are also submersible pumps connected to the tail of the interception net for sewage discharge. However, each net bag needs to correspond to a sewage pump. The number of equipment is large and the pump is easily affected by the attachment of marine organisms and seawater corrosion due to long-term immersion in seawater. The failure rate is high, maintenance requires divers to operate, and there are great safety hazards. There are also land pumps for suction, but the design theory of non-clogging and high suction pumps is immature. At low tide, the pump will cavitate, causing the equipment to fail to operate normally. At the same time, the pipelines of the existing cleaning system are relatively complex, prone to blockage, and do not have a mechanized unblocking function. In emergency situations, the system may not be able to operate continuously and stably, so it is urgent to solve it. Summary of the invention

[0004] In order to avoid and overcome the technical problems existing in the prior art, the present invention provides an emergency suction system for a cold source barrier of a nuclear power plant, which can effectively improve the cleaning stability and efficiency of marine garbage.

[0005] To achieve the above object, the present invention provides the following technical solutions:

[0006] A nuclear power plant cold source interception net emergency suction system comprises a plurality of net bags floating on the sea surface and used for collecting floating objects on the drifting path of the floating objects, the net openings of the net bags are arranged in a row on the sea surface to cooperate to form a blocking net wall, the outlets of the net bags are connected to the suction pipes through branch pipes, and each branch pipe is equipped with a gate valve; the suction pipe is connected to the inlet end of a large channel suction centrifugal pump floating on the sea surface, and the outlet end of the large channel suction centrifugal pump is connected to a solid-liquid separator installed thereon.

[0007] As a further solution of the present invention: a caisson half-sunken into the sea is arranged between adjacent net bags, one side of the rectangular net opening adjacent to the caisson is fitted and fixed to the outer wall of the caisson, and the lower half of the rectangular net opening is immersed in the sea.

[0008] As a further solution of the present invention: the net bags located at both ends of the barrier net wall are respectively connected to the protection blocks at the cold source entrance of the nuclear power plant.

[0009] As a further solution of the present invention: the suction pipe is installed on the floating row, and a plurality of buoys are installed side by side on the lower surface of the floating row, and the length direction of each buoy is parallel to the length direction of the floating row.

[0010] As a further solution of the present invention: the branch pipe includes a straight pipe and an elbow connecting adjacent straight pipes, and the gate valve is installed on the straight pipe.

[0011] As a further solution of the present invention: the large channel suction centrifugal pump is installed in a floating pump station floating on the sea surface.

[0012] As a further solution of the present invention: a backup pump is also installed in the floating pump station, and the backup pump, the large channel suction centrifugal pump and the suction pipe are connected to each other through a three-way ball valve.

[0013] As a further solution of the present invention: the outlet end of the standby pump is communicated with the solid-liquid separator.

[0014] As a further solution of the present invention: the total head loss of the marine biological suction pipeline is H1:

[0015] H1=h1+h2+h3;

[0016] h1=I·L;

[0017]

[0018] Wherein, h1 represents the total resistance loss along the suction pipe; h2 represents the resistance loss caused by all elbows used in the system; h3 represents the resistance loss caused by all gate valves used in the system; I represents the hydraulic gradient of the suction pipe; K represents the length of the suction pipe; k represents the number of net bags; ξ2 represents the local resistance loss coefficient of the elbow; v2 represents the flow velocity of water when flowing through the elbow; g represents the acceleration of gravity; v3 represents the flow velocity of water when flowing through the gate valve; ω3 represents the local resistance loss coefficient of the gate valve; Q represents the flow rate through the suction pipe; and d represents the diameter of the suction pipe.

[0019] As a further solution of the present invention: the head of the large channel suction centrifugal pump is H:

[0020] H=H1+H2;

[0021] Where H2 represents the height difference between the elevation of the large channel suction centrifugal pump and the highest point of the suction system.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] 1. The present invention forms an effective barrier wall by setting up multiple floating net bags on the sea surface, which can quickly collect and intercept floating objects on the drifting path, prevent them from entering the cold source area of ​​the nuclear power plant, and ensure the safe operation of the nuclear power plant. Each net bag is connected to the suction pipe through a branch pipe, and a gate valve is installed on the branch pipe to facilitate flexible control of the suction operation of each net bag, thereby improving the flexibility and reliability of the system. The combined use of a large-channel suction centrifugal pump and a solid-liquid separator can effectively suck and process the intercepted floating objects, keeping the cold source area clean and unobstructed.

[0024] 2. The caissons are arranged between adjacent net bags, which not only enhances the stability of the barrier net wall, but also effectively prevents seawater and floating objects from passing through the gaps between the net bags, further improving the interception effect. The caisson is fitted and fixed to one side of the rectangular net opening, so that the lower half of the net bag can be stably immersed in the sea, enhancing the interception capability.

[0025] 3. The net bags at both ends of the barrier net wall are connected to the protection blocks at the cold source entrance of the nuclear power plant to form a complete protection system, which effectively prevents floating objects from bypassing the barrier net wall from both sides and entering the cold source area, thereby improving the strictness and reliability of the protection.

[0026] 4. The suction pipe is installed on the floating row and supported by multiple buoys, so that the entire suction system can float stably on the sea surface without being affected by waves and tides. At the same time, the design of the floating row and buoys also facilitates the installation, commissioning and maintenance of the system.

[0027] 5. The branch pipe adopts a combination of straight pipe and elbow, making the system structure more compact and flexible. The gate valve is installed on the straight pipe, which is convenient for operation and control, and also convenient for system inspection and maintenance.

[0028] 6. Installing the large channel suction centrifugal pump in a floating pump station floating on the sea surface allows the pump body to float with the ups and downs of the sea surface, avoiding stress concentration and damage risks caused by fixed installation. At the same time, the design of the floating pump station also facilitates the inspection and maintenance of the large channel suction centrifugal pump.

[0029] 7. Install a backup pump in the floating pump station and connect it to the large channel suction centrifugal pump and suction pipe through a three-way ball valve, which improves the reliability and emergency response capability of the system. When the large channel suction centrifugal pump fails, it can be quickly switched to the backup pump to ensure the continuous operation of the system.

[0030] 8. The outlet of the standby pump is connected to the solid-liquid separator, so that the standby pump can effectively handle the intercepted floating objects when it is activated, keeping the cold source area clean and unobstructed.

[0031] 9. The formula for calculating the total head loss of the system provides a scientific basis for the design and optimization of the system. Through calculation and analysis, the resistance loss and performance of the system can be accurately evaluated, providing strong support for the improvement and optimization of the system.

[0032] 10. The proposed formula for calculating the head of a large channel suction centrifugal pump provides an important reference for the selection and configuration of a large channel suction centrifugal pump. Through calculation and analysis, the head requirements of a large channel suction centrifugal pump can be accurately determined to ensure that the pump body can meet the operating requirements of the system and improve the overall performance and reliability of the system. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 It is a schematic diagram of the overall structure of the present invention.

[0034] Figure 2 It is a schematic diagram of the structure of the floating pump station in the present invention.

[0035] Figure 3 This is a schematic diagram of the double pump structure of "one for backup and one for use, backwashing each other" in the present invention.

[0036] Figure 4 It is a schematic structural diagram of the large-channel suction centrifugal pump in the present invention.

[0037] In the figure: 1. control cabinet; 2. communication pipe; 3. large channel suction centrifugal pump; 4. floating pump station; 5. suction pipe; 6. branch pipe; 61. straight pipe; 62. elbow; 63. gate valve; 7. floating row; 8. solid-liquid separator; 9. net bag; 10. caisson; 11. buoy; 12. three-way ball valve; 13. pump body; 14. impeller; 15. wear-resistant ring; 16. rear pump cover; 17. vacuum regulating valve; 18. degassing pipe; 19. separation plate; 20. suction impeller; 21. shaft seal; 22. bearing bracket; 23. shaft; 24. deep groove ball bearing; 25. bracket; 26. spare pump. DETAILED DESCRIPTION

[0038] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0039] See also Figure 1-2In an embodiment of the present invention, a nuclear power plant cold source blocking emergency suction system includes a plurality of net bags 9, and a caisson 10 half-sunken in the sea is installed between each net bag 9. The net opening of the net bag 9 is rectangular, half of the net opening is below the sea surface, and half is above the sea surface. One side of the rectangular net opening adjacent to the caisson 10 is fitted and fixed to the outer wall of the caisson 10. With this connection method, each net opening is connected to each other to form a blocking net wall. At the same time, in order to improve the stability of the blocking net wall, the two ends of the blocking net wall are respectively connected to the protective blocks at the entrance of the cold source of the nuclear power plant.

[0040] The outlet of the square cone net bag 9 is connected to the suction pipe 5 through the branch pipe 6. The branch pipe 6 includes a straight pipe 61 and an elbow 62 connecting adjacent straight pipes 61, and a gate valve 63 is installed on the straight pipe 61. The suction pipe 5 is connected to the inlet end of the large channel suction centrifugal pump 3 floating on the sea surface, and the outlet end of the large channel suction centrifugal pump 3 is connected to the solid-liquid separator 8 through the connecting pipe 2. The suction pipe 5 is installed on the floating row 7, and a plurality of buoys 11 are installed side by side on the lower surface of the floating row 7, and the length direction of each buoy 11 is parallel to the length direction of the floating row 7.

[0041] The large channel suction centrifugal pump 3 is installed in a floating pump station 4 floating on the sea surface, and a standby pump 26 is also installed in the floating pump station 4. The standby pump 26, the large channel suction centrifugal pump 3 and the suction pipe 5 are connected to each other through a three-way ball valve 12. The switching use of the large channel suction centrifugal pump 3 and the standby pump 26 is controlled by the control cabinet 1.

[0042] When the present invention is in use, the control cabinet 1 controls the standby pump 26 or the large channel suction centrifugal pump 3 to start, and the three-way ball valve 12 is adjusted so that the running standby pump 26 or the large channel suction centrifugal pump 3 is connected to the suction pipe 5, and the suction work starts. At the same time, the gate valves 63 at the net bags 9 that need to be sucked are opened in sequence, and the net bags 9 are sucked one by one. After the suction is completed, the standby pump 26 or the large channel suction centrifugal pump 3 is turned off, and the solids in the solid-liquid separator 8 are taken out.

[0043] like Figure 3As shown, the floating pump station 4 adopts the pipeline design concept of "one standby and one in use, backwashing each other", and the specific operation is: when the large channel suction centrifugal pump 3 is working normally, open valve ③ and valve ④, close valve ①, valve ② and valve ⑤, and normal operation can be achieved; when the working pump pipeline fails, first rotate the handwheel of the three-way ball valve 12 clockwise by 120°, close valve ①, valve ③ and valve ⑤, open valve ② and valve ④, and the standby pump 26 can be quickly replaced. This design allows one pump to work normally while the other is on standby at any time, so as to quickly replace it in case of failure or maintenance, avoiding work interruption due to equipment problems, thereby improving the reliability of the system. In addition, when the large-channel suction centrifugal pump 3 is working normally, open valve ③ and valve ④, and close valve ①, valve ② and valve ⑤ to achieve normal operation; when the working pump is blocked, first rotate the handwheel of the three-way ball valve 12 clockwise by 120°, close valve ④ and valve ⑤, open valve ①, valve ② and valve ③, and backwash the working pump; when the standby pump 26 is blocked, close valve ① and valve ④, open valve ③, valve ② and valve ⑤, and backwash the standby pump 26. This design can ensure its long-term and efficient operation, reduce the frequency of manual maintenance, and significantly reduce the risk of unexpected downtime due to equipment blockage.

[0044] The large-channel suction centrifugal pump 3 used in the present invention integrates a water ring vacuum pump and a centrifugal pump structure, that is, the impeller part of the water ring vacuum pump is arranged between the impeller 14 and the driving end of the centrifugal pump, thereby forming a complete large-channel suction centrifugal pump 3.

[0045] like Figure 4As shown, the large channel suction centrifugal pump 3 includes a pump body 13, an impeller 14, a wear ring 15, a rear pump cover 16, a vacuum regulating valve 17, a degassing pipe 18, a separation disc 19, a suction impeller 20, a shaft seal 21, a bearing bracket 22, a shaft 23, a deep groove ball bearing 24 and a bracket 25. The wear ring 15 is located between the impeller 14 and the pump body 13, and the separation disc 19 is located between the suction impeller 20 and the impeller 14, and together with the shaft seal 21, a sealed cavity is formed. The vacuum regulating valve 17 is located at the rear end of the suction impeller 20 and is used to adjust the pressure in the sealed cavity. The separation disc 19 and the suction impeller 20 are the core of the water ring vacuum pump. They generate power through high-speed rotation, drive the medium in the sealed cavity to form a water ring, and thus realize the function of vacuum extraction. The wear ring 15 is an important wear-resistant component. It is located between the impeller 14 and the pump body 13, and plays a role in reducing friction, protecting the pump body 13 and the impeller 14, and effectively extending the service life of the equipment. The rear pump cover 16 is connected to the pump body 13, and together they form the rear sealing structure of the large channel suction centrifugal pump 3. The vacuum regulating valve 17 is located at the rear end of the suction impeller 20. Its main function is to adjust the pressure in the sealed chamber to ensure that the equipment operates in the best state. The degassing pipe 18 is used to remove the gas in the sealed chamber to maintain the vacuum state in the sealed chamber. The separation disc 19 is located between the suction impeller 20 and the impeller 14. Its function is to help separate gas and water to ensure the normal operation of the equipment. The suction impeller 20 is the core component of the entire equipment. It makes the water in the sealed chamber form a water ring to generate a strong vacuum suction. The shaft seal 21 and the separation disc 19 form a sealed chamber together to effectively prevent gas leakage and ensure the sealing performance of the equipment. The bearing bracket 22 is used to support and fix the shaft 23 to ensure the stability and reliability of the shaft during rotation. The deep groove ball bearing 24 is a commonly used rolling bearing. It is located on the shaft and plays a supporting and rotating role, further enhancing the stability and durability of the equipment. The bracket 25 is the supporting structure of the whole device, which connects and fixes all the main components, ensuring the overall stability and reliability of the device. In summary, the various components in the large channel suction centrifugal pump 3 cooperate with each other and work closely together to achieve an efficient vacuum extraction function.

[0046] When the large channel suction centrifugal pump 3 is in use, the motor is first started to drive the shaft 23 to rotate. The shaft 23 rotates and drives the suction impeller 20 and the impeller 14 to rotate synchronously. Then the suction impeller 20 begins to extract the gas inside the pump body 13 through the air inlet hole on the separation disk 19. At the same time, the gas in the suction pipe 5 gradually flows into the pump body 13 under the suction action of the impeller 14 and the separation impeller 20, and enters the sealed cavity through the air inlet hole on the separation disk 19. Finally, the gas flows through the air outlet hole on the separation disk 19 and is discharged from the degassing pipe 18. In this way, the gas in the suction pipe 5 is gradually discharged by reciprocating suction and exhaust, achieving the purpose of suction and allowing floating objects and marine garbage to be sucked into the suction pipe 5, and then sent to the solid-liquid separator 8 under the action of the impeller 14 to complete solid-liquid separation.

[0047] like Figure 2 and Figure 3 As shown, valve ① is opened to allow seawater to enter the flow channel of the large channel suction centrifugal pump 3. After startup, the seawater in the sealed cavity forms an annular water film under the action of centrifugal force, and together with the suction impeller 20, the volume of the air chamber in the sealed cavity is changed to achieve gas suction, compression and discharge. In the suction stage, the gas enters the larger air chamber; in the compression stage, the volume of the air chamber is reduced and the gas is compressed; in the exhaust stage, the gas is discharged through the degassing pipe 18.

[0048] It is known that the total length of the suction pipe 5 in the emergency suction system of a nuclear power cold source marine biological invasion barrier is L 150m, the total number of net bags 9 is 1, the total number of elbows 62 is 7, and the total number of gate valves 63 is 6; the suction pipe 5 adopts DN280 DR11 grade HDPE pipe with a wall thickness of about 29.44mm, and the suction operation flow Q is 400m 3 / h, the average flow velocity in the suction pipe 5 is about 2.27m / s, the diameter d of the suction pipe 5 is 0.25m, and the pipeline resistance along the way I = 0.0139. The total resistance loss along the way h1 of the system is 2.085. The total local resistance loss of the elbow 62 is:

[0049]

[0050] In the calculation of the local resistance of the gate valve 63 and the elbow 62, the total local resistance loss of the gate valve 63 is:

[0051]

[0052] The total head loss of the marine biological suction pipeline is:

[0053] H1=3.548m

[0054] The height difference H2 between the large channel suction centrifugal pump 3 and the highest point of the system is 8m, so the required head of the large channel suction centrifugal pump 3 is:

[0055] H=11.548m

[0056] Considering the safety factor and cavitation performance, the selection parameters of large channel suction centrifugal pump 3 are flow rate 400m 3 / h, the lift is 14m.

[0057] The impeller 14 of the large channel suction centrifugal pump 3 adopts a double blade structure. In order to meet the suction stroke design of 600r / min, the flow rate Q of the reference pump is obtained by increasing the speed C And lift H C Calculate hydraulic geometry parameters and perform CWhen used, the reference pump can finally achieve non-blocking operation. Set the speed n of the large channel suction centrifugal pump 3 to 1000r / min. According to the flow similarity relationship: Q / Q C =(n / n C ) / (D / D C ) 3 , Q and Q C are the flow rates of large channel suction centrifugal pump 3 and the reference pump, D and D C are the impeller diameters of large channel suction centrifugal pump 3 and the reference pump, n and n C The impeller speed and head similarity relationship of large channel suction centrifugal pump 3 and reference pump are H / (H C -h')=(n / n C ) 2 (D / D C ) 2 , H C The head of the reference pump, h' is the head conversion margin, which is 4m. After calculation, the flow rate Q of the reference pump C 667m 3 / h, head H C By design, the inlet diameter of the large channel suction centrifugal pump 3 is 216.6 mm, the outer diameter of the impeller 14 is 487.4 m, and the blade outlet width is 140.8 m, which can meet the needs of non-clogging suction.

[0058] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A nuclear power plant cold source barrier emergency suction system, characterized in that: The invention comprises a plurality of net bags (9) floating on the sea surface and used for collecting floating objects on the drifting path of the floating objects, the net openings of the net bags (9) are arranged in a row on the sea surface to cooperate to form a blocking net wall, the outlets of the net bags (9) are connected to the suction pipe (5) through the branch pipe (6), and each branch pipe (6) is equipped with a gate valve (63); the suction pipe (5) is connected to the inlet end of a large channel suction centrifugal pump (3) floating on the sea surface, and the outlet end of the large channel suction centrifugal pump (3) is connected to a solid-liquid separator (8) installed thereon.

2. A nuclear power plant cold source barrier emergency suction system according to claim 1, characterized in that: A caisson (10) half-sunken in the sea is arranged between adjacent net bags (9), one side of a rectangular net opening adjacent to the caisson (10) is fitted and fixed to the outer wall of the caisson (10), and the lower half of the rectangular net opening is immersed in the sea.

3. A nuclear power plant cold source screen emergency suction system according to claim 2, characterized in that: The net bags (9) located at both ends of the barrier net wall are respectively connected to the protection blocks at the cold source entrance of the nuclear power plant.

4. A nuclear power plant cold source barrier emergency suction system according to any one of claims 1 to 3, characterized in that: The suction pipe (5) is installed on the floating row (7), and a plurality of buoys (11) are installed side by side on the lower surface of the floating row (7), and the length direction of each buoy (11) is parallel to the length direction of the floating row (7).

5. A nuclear power plant cold source barrier emergency suction system according to claim 4, characterized in that: The branch pipe (6) comprises a straight pipe (61) and an elbow (62) connecting adjacent straight pipes (61), and a gate valve (63) is installed on the straight pipe (61).

6. A nuclear power plant cold source barrier emergency suction system according to claim 5, characterized in that: The total head loss of the marine biological suction pipeline is H1: H1=h1+h2+h3; h1=I·L; In the formula, h1 represents the total resistance loss along the suction pipe (5); h2 represents the resistance loss caused by all elbows (62) used in the system; h3 represents the resistance loss caused by all gate valves (63) used in the system; I represents the hydraulic gradient of the suction pipe (5); L represents the length of the suction pipe (5); k represents the number of net bags (9); ξ2 represents the local resistance loss coefficient of the elbow (62); v2 represents the flow velocity of water when flowing through the elbow (62); g represents the acceleration of gravity; v3 represents the flow velocity of water when flowing through the gate valve (63); ξ3 represents the local resistance loss coefficient of the gate valve (63); Q represents the flow rate flowing through the suction pipe (5); and d represents the diameter of the suction pipe (5).

7. A nuclear power plant cold source screen emergency suction system according to claim 6, characterized in that: Large channel suction centrifugal pump (3) head is H: H=H1+H2; Wherein, H2 represents the height difference between the elevation of the large channel suction centrifugal pump (3) and the highest point of the suction system.

8. A nuclear power plant cold source screen emergency suction system according to claim 7, characterized in that: A large channel suction centrifugal pump (3) is installed in a floating pump station (4) floating on the sea surface.

9. A nuclear power plant cold source screen emergency suction system according to claim 8, characterized in that: A standby pump (26) is also installed in the floating pump station (4), and the standby pump (26), the large channel suction centrifugal pump (3) and the suction pipe (5) are connected to each other via a three-way ball valve (12).

10. A nuclear power plant cold source barrier emergency suction system according to claim 9, characterized in that: The outlet end of the standby pump (26) is in communication with the solid-liquid separator (8).

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