A device for secondary side maintenance of horizontal steam generators used in nuclear power plants.

Abstract

This application belongs to the field of nuclear power plant engineering, specifically relating to a device for secondary side maintenance of a horizontal steam generator used in a nuclear power plant. The device includes: an air supply duct, an air supply fan, an exhaust duct, and an exhaust fan. One end of the air supply duct enters the steam generator through a manhole and extends to the bottom of the heat transfer tubes of the steam generator; the other end of the air supply duct is connected and fixed to the outlet of the air supply fan. One end of the exhaust duct is placed on an underwater steam distribution plate inside the steam generator, and the other end passes through the manhole and is connected and fixed to the inlet of the exhaust fan. No special placement platform is required; any location on site can be used as a placement location. Internal maintenance can be achieved simply by opening one manhole, improving maintenance efficiency.

Description

Technical Field

[0001] This application belongs to the field of nuclear power plant engineering, and specifically relates to a device for secondary side maintenance of a horizontal steam generator for nuclear power plants. Background Technology

[0002] In a certain nuclear reactor facility, there are 8 horizontal steam generators. During the overhaul, the internal secondary side of the steam generators needs to be maintained. There are two maintenance methods: silica gel maintenance and dry air maintenance.

[0003] Silica gel maintenance involves placing silica gel on an underwater steam distribution plate inside the secondary side of the steam generator. However, since silica gel can only be placed and retrieved manually, this maintenance method is labor-intensive, requiring a large number of personnel and time. Furthermore, because the steam generator is a core component of the nuclear island and has a high radiation dose, personnel entering to place silica gel for maintenance will increase their radiation exposure and the risk of foreign objects entering the equipment.

[0004] Dry air maintenance involves setting up a work platform at the manhole on the side of the steam generator, with a blower mounted on it. The blower is directly connected to the manhole, and the maintenance is achieved by blowing air into the secondary side of the steam generator. Because the blower is directly connected to the manhole, the blowing air can only clean a portion of the secondary side of the steam generator, making the maintenance efficiency slightly lower than silica gel maintenance. Furthermore, since air enters through one manhole, the other manhole must be opened for exhaust to ensure the blower operates normally and is not damaged. According to the steam generator manhole maintenance cycle (4C) requirements, not every major overhaul requires both manholes to be fully opened, but to ensure the blower operates normally and is not damaged, both manholes must be opened. Therefore, this maintenance method directly increases the workload significantly, and the required personnel and time also increase dramatically. Summary of the Invention

[0005] The purpose of this application is to provide a device for secondary side maintenance of horizontal steam generators used in nuclear power plants, which solves the problem that dry air maintenance directly increases the workload and the required personnel and time.

[0006] The technical solution to achieve the purpose of this application is as follows:

[0007] This application provides an embodiment of a device for secondary side maintenance of a horizontal steam generator for nuclear power plants. The device includes: an air supply duct, an air supply fan, an exhaust duct, and an exhaust fan.

[0008] One end of the air supply duct enters the steam generator through a manhole on one side and extends to the bottom of the heat transfer tube of the steam generator. The other end of the air supply duct is connected and fixed to the air outlet of the air supply fan.

[0009] One end of the exhaust duct is placed on the underwater steam distribution plate inside the steam generator, and the other end passes through the manhole and is connected and fixed to the air inlet of the exhaust fan.

[0010] Optionally, the device further includes: a side manhole guard plate to prevent foreign objects from entering;

[0011] A foreign object prevention mesh plate is installed on the manhole, and two through holes are provided for the air supply duct and the exhaust duct to pass through respectively.

[0012] Optionally, the device further includes: a foreign object prevention device at the outlet of the air supply fan and a foreign object prevention device at the inlet of the air supply fan;

[0013] The anti-foreign object device at the outlet of the air supply fan is connected and fixed to the air supply fan by bolts and nuts, and the anti-foreign object device at the inlet of the air supply fan is connected by bolts and nuts.

[0014] Optional,

[0015] The other end of the air supply duct is connected to the throat of the anti-foreign object device at the outlet of the air supply fan by a steel cable tie.

[0016] Optionally, the device further includes: a foreign object prevention device for the exhaust fan inlet;

[0017] The foreign object prevention device at the inlet of the exhaust fan is connected and fixed to the air inlet of the exhaust fan by bolts and nuts.

[0018] Optionally, the other end of the exhaust duct is connected to the throat of the anti-foreign object device at the inlet of the exhaust fan via a steel cable tie.

[0019] Optionally, the air inlet opening of the exhaust duct is arranged facing upwards.

[0020] Optionally, the exhaust duct has three air inlets.

[0021] The beneficial technical effects of this application are as follows:

[0022] (1) The present application provides a device for secondary side maintenance of a horizontal steam generator for nuclear power plants. The device uses air supply duct and exhaust duct so that the blower does not need to be directly connected to the side manhole and no special placement platform is required. Any site on site can be used as the placement site. Internal maintenance can be achieved by simply opening one side manhole. During maintenance, the airflow direction of the purging air is from left to right and from bottom to top, and then discharged through the exhaust duct. Compared with the unidirectional flow direction from left to right, it expands the purging area inside the secondary side of the steam generator and improves the maintenance efficiency.

[0023] (2) The present application provides a device for secondary side maintenance of a horizontal steam generator for nuclear power plants. It uses inlet and outlet anti-foreign object mesh plates and side manhole anti-foreign object mesh plates to reduce the risk of foreign objects, avoid radiation dose caused by personnel entering, and reduce industrial safety risks. Attached Figure Description

[0024] Figure 1 A schematic diagram of a device for secondary side maintenance of a horizontal steam generator for nuclear power plants, provided in an embodiment of this application;

[0025] Figure 2 A schematic diagram of the structure of the air supply fan and air supply duct in an apparatus for secondary side maintenance of a horizontal steam generator for nuclear power plants, provided in an embodiment of this application;

[0026] Figure 3 A schematic diagram of the exhaust fan and exhaust duct in an apparatus for secondary side maintenance of a horizontal steam generator for nuclear power plants, provided in an embodiment of this application;

[0027] Figure 4 A schematic diagram of the structure of a foreign object prevention mesh plate for the manhole in a device for secondary side maintenance of a horizontal steam generator for nuclear power plants, provided in an embodiment of this application;

[0028] Figure 5 A schematic diagram of the structure of the foreign object prevention device at the inlet of the blower in an apparatus for secondary side maintenance of a horizontal steam generator for nuclear power plants, provided in an embodiment of this application;

[0029] Figure 6a and Figure 6b A schematic diagram of the structure of the foreign object prevention device at the outlet of the blower in an apparatus for secondary side maintenance of a horizontal steam generator for nuclear power plants, provided in an embodiment of this application;

[0030] Figure 7a and 7b This is a schematic diagram of the structure of the foreign object prevention device at the inlet of the exhaust fan in an apparatus for secondary side maintenance of a horizontal steam generator for nuclear power plants, provided in an embodiment of this application.

[0031] In the picture:

[0032] 1-Exhaust fan, 2-Exhaust fan inlet anti-foreign object device, 3-Exhaust duct, 4-Side manhole anti-foreign object mesh plate, 5-Underwater steam distribution plate, 6-Heat transfer tube, 7-Dedicated air supply duct, 8-Air supply fan outlet anti-foreign object device, 9-Air supply fan, 10-Air supply fan inlet anti-foreign object device, 11-Steam generator. Detailed Implementation

[0033] To enable those skilled in the art to better understand this application, the technical solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the embodiments described below are only a part of the embodiments of this application, and not all of them. Based on the embodiments described in this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0034] Dry air maintenance involves setting up a work platform at the manhole on the side of the steam generator, with a blower mounted on it. The blower is directly connected to the manhole, and maintenance is achieved by blowing air into the secondary side of the steam generator. Because the blower is directly connected to the manhole, the blowing air can only clean a portion of the secondary side of the steam generator, resulting in slightly lower maintenance efficiency compared to silica gel maintenance. Furthermore, there are no foreign object prevention measures at the blower inlet and outlet, allowing foreign objects from outside and inside the blower to easily enter the steam generator with the maintenance air, causing contamination. Additionally, since air enters through one manhole, the other manhole must be opened for exhaust to ensure the blower operates normally and is not burned out. According to the steam generator manhole maintenance cycle (4C) requirements, not every major overhaul requires opening both manholes completely, but opening both manholes is necessary to ensure the blower operates normally and is not burned out. Therefore, this maintenance method directly increases the workload significantly, and the required personnel and time increase dramatically. In addition, since the fan is directly connected to the side manhole, the placement of the fan also has strict requirements for the platform erection. The height of the platform must be such that the fan and the side manhole are horizontally aligned. However, since the disassembly and installation of the steam generator side manhole also require the use of this platform, and the required height is different, the scaffolding work platform needs to be switched and modified between the disassembly and installation of the manhole and the maintenance work. This also increases a lot of working time and workload.

[0035] Therefore, this application provides a device for secondary side maintenance of a horizontal steam generator used in nuclear power plants, which can efficiently complete the internal maintenance of the secondary side of the steam generator without preventing foreign objects from entering the steam generator with the maintenance air, without setting up a working platform, opening one end of the manhole, and avoiding personnel from entering and being exposed to radiation dose. This method can reduce the labor intensity of personnel, reduce maintenance time, and improve work efficiency.

[0036] Based on the above, in order to clearly and in detail illustrate the advantages of this application, the specific embodiments of this application will be described below in conjunction with the accompanying drawings.

[0037] See Figure 1 The figure is a schematic diagram of a device for secondary side maintenance of a horizontal steam generator for nuclear power plants, provided in an embodiment of this application.

[0038] This application provides an embodiment of a device for secondary side maintenance of a horizontal steam generator for nuclear power plants, comprising: an air supply duct 7, an air supply fan 9, an exhaust duct 3, and an exhaust fan 1;

[0039] One end of the air supply duct 7 enters the steam generator 11 through a manhole on one side and extends to the bottom of the heat transfer tube 6 of the steam generator 11. The other end of the air supply duct 7 is connected and fixed to the air outlet of the air supply fan 9.

[0040] One end of the exhaust duct 3 is placed on the underwater steam distribution plate 5 inside the steam generator 11, and the other end passes through the manhole and is connected and fixed to the air inlet of the exhaust fan 1, such as... Figure 2 and Figure 3 As shown.

[0041] In some possible implementations of the embodiments of this application, such as Figure 4 As shown, the device also includes: a side manhole anti-foreign object mesh plate 4;

[0042] The side manhole anti-foreign object mesh plate 4 is installed on the manhole and has two through holes for the air supply duct 7 and the exhaust duct 3 to pass through respectively.

[0043] In some possible implementations of the embodiments of this application, such as Figure 5 , Figure 6a and Figure 6b As shown, the device also includes: a foreign object prevention device 8 at the outlet of the air supply fan and a foreign object prevention device 10 at the inlet of the air supply fan;

[0044] The air supply fan outlet anti-foreign object device 8 is connected and fixed to the air supply fan 9 by bolts and nuts, and the air supply fan inlet anti-foreign object device 10 is connected to the air supply fan inlet 9 by bolts and nuts.

[0045] As an example, the foreign object prevention device 10 at the inlet of the air blower can be in the form of two flanges with a stainless steel wire mesh sandwiched between them, and the wire mesh is fixed by spot welding. The foreign object prevention device 8 at the outlet of the air blower can also be in the form of two flanges with a stainless steel wire mesh sandwiched between them, and the wire mesh is fixed by spot welding.

[0046] In one example, the other end of the air supply duct 7 is connected to the throat of the air supply fan outlet anti-foreign object device 8 by a steel cable tie.

[0047] In some possible implementations of the embodiments of this application, Figure 7a and 7b As shown, the device also includes: a foreign object prevention device 2 for the exhaust fan inlet;

[0048] The foreign object prevention device 2 at the inlet of the exhaust fan is connected and fixed to the air inlet of the exhaust fan 1 by bolts and nuts.

[0049] As an example, the foreign object prevention device 2 at the inlet of the exhaust fan can be in the form of two flanges with a stainless steel wire mesh sandwiched between them, and the wire mesh is fixed by spot welding.

[0050] In one example, the other end of the exhaust duct 3 is connected to the throat of the exhaust fan inlet anti-foreign object device 2 by a steel cable tie.

[0051] In some possible implementations of the embodiments of this application, the air inlet opening of the exhaust duct 3 is arranged facing upwards. As an example, the exhaust duct 3 has three air inlets.

[0052] Understandably, the new maintenance air supply fan 9 and exhaust fan 1 can be placed on the steel grating of the manhole equipment opened at either end of the steam generator 11 without the need to set up a work platform. Both the inlet and outlet of the air supply fan 9 are equipped with flanges that can be connected to the anti-foreign object device. The air inlet is connected to the air supply fan inlet anti-foreign object device 10 via the flange and bolts and nuts, and the air outlet is connected to the air supply fan outlet anti-foreign object device 8. The air supply fan outlet anti-foreign object device 8 has a throat section, which can be connected to the air supply duct 7 via stainless steel cable ties. The air supply duct 7 passes through the anti-foreign object mesh plate 4 of the manhole on the side of the steam generator 11 and enters the interior of the secondary side of the steam generator 11. After entering the interior, the air outlet of the duct extends vertically downward to the bottom of the heat transfer tube 6 of the steam generator 11. The exhaust fan 1 has a flange at its air inlet, which can be connected to the exhaust fan inlet anti-foreign object device 2 via bolts and nuts. The exhaust fan inlet anti-foreign object device 2 has a throat section, which can be connected to the exhaust duct 3 via stainless steel cable ties. The exhaust duct 3 passes through the anti-foreign object mesh plate 4 of the manhole on the side of the steam generator 11 and enters the secondary side of the steam generator 11. After entering the interior, it is placed directly on the underwater steam distribution plate 5 of the steam generator 11. There are three exhaust ports at the end of the exhaust duct 3, with the three exhaust ports facing upwards. The anti-foreign object mesh plate 4 of the manhole on the side can be fixed to the manhole by bolts and nuts on the body of the steam generator 11. At the same time, the supply fan 9 and the exhaust fan 1 are turned on to maintain the secondary side of the steam generator 11. During maintenance, the airflow direction of the purging air is from left to right and from bottom to top, and then it is discharged through the exhaust duct 3. Compared with the unidirectional flow from left to right, this expands the purging area inside the secondary side of the steam generator and improves the maintenance efficiency.

[0053] The specific steps are as follows:

[0054] 1. Ensure that the steam generator 11 is in an isolated state and that the manhole on one end is open;

[0055] 2. Ensure the temperature inside the container is below 45℃;

[0056] 3. Place the exhaust fan 1 and the supply fan 9 on any site outside the manhole on the opening side of the steam generator 11 that will not affect the operation;

[0057] 4. Briefly start the exhaust fan 1 and the supply fan 9, and reconfirm the airflow direction at the inlet and outlet of the fans. After confirming that there is no abnormality, disconnect the power.

[0058] 5. Connect the foreign object prevention device 2 at the inlet of the exhaust fan to the inlet flange of the exhaust fan 1 using bolts and nuts;

[0059] 6. Connect and fix the outlet anti-foreign object device 8 and the inlet anti-foreign object device 10 of the air blower to the inlet and outlet flanges of the new air blower 9 respectively using bolts and nuts;

[0060] 5. Insert one end of the air supply duct 7 into the steam generator 11. After entering the interior, the air outlet of the duct extends vertically downward to the bottom of the heat transfer tube 6 of the steam generator 11.

[0061] 6. The other end of the air supply duct 7 passes through the lower opening of the side manhole anti-foreign object mesh plate 4;

[0062] 7. The other end of the air supply duct 7 passes through the lower opening of the side manhole anti-foreign object mesh plate 4 and is connected to the throat of the air supply fan outlet anti-foreign object device 8 by a steel binding strap.

[0063] 8. Place one end of the exhaust duct 3 on the underwater steam distribution plate 5, with the air inlet opening facing upwards;

[0064] 9. Pass the other end of the exhaust duct 3 through the upper opening of the side manhole anti-foreign object mesh plate 4;

[0065] 10. The other end of the exhaust duct 3 passes through the opening on the side manhole anti-foreign object mesh plate 4 and is connected to the throat of the exhaust fan inlet anti-foreign object device 2 by a steel cable tie.

[0066] 11. Check and confirm whether the exhaust duct 3 and the supply duct 7 are bent, flattened, or otherwise damaged;

[0067] 12. Secure the side manhole anti-foreign object mesh plate 4 to the opening side manhole using the steam generator body bolts;

[0068] 13. First turn on the power to start the supply fan 9, then turn on the power to start the exhaust fan 1;

[0069] 14. Double-check and confirm whether the exhaust duct 3 and the supply duct 7 are bent, flattened, or otherwise damaged.

[0070] 15. Check for air leaks at all connections between the exhaust duct 3 and the supply duct 7;

[0071] 16. After confirming that there are no problems, the maintenance of steam generator 11 begins;

[0072] 17. Subsequently, turn off the supply fan 9 and exhaust fan 1 every 8 hours, and repeat steps 13-16 after waiting for 1 hour.

[0073] 18. After receiving the maintenance stop instruction, stop the supply fan 9 and exhaust fan 1, remove all maintenance equipment, reinstall the steam generator side manhole, and the maintenance is complete.

[0074] The present application has been described in detail above with reference to the accompanying drawings and embodiments. However, the present application is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of the present application. All content not described in detail in this application can be derived from existing technology.

Claims

1. An apparatus for secondary side maintenance of a horizontal steam generator for nuclear power plants, characterized in that, The device comprises a supply air duct (7), a supply air fan (9), an exhaust air duct (3) and an exhaust air fan (1); One end of the supply air duct (7) enters the inside of the steam generator (11) through a side manhole and extends to the bottom of the heat transfer pipe (6) of the steam generator (11), and the other end of the supply air duct (7) is connected and fixed with the air outlet of the supply air fan (9); One end of the exhaust air duct (3) is placed on the underwater uniform steam plate (5) inside the steam generator (11), and the other end passes through the manhole and is connected and fixed with the air inlet of the exhaust air fan (1); The device further comprises a supply air fan outlet foreign matter prevention device (8) and a supply air fan inlet foreign matter prevention device (10); The supply air fan outlet foreign matter prevention device (8) is connected and fixed with the supply air fan (9) through bolts and nuts, and the supply air fan inlet foreign matter prevention device (10) is connected with the inlet of the supply air fan (9) through bolts and nuts; The supply air fan inlet foreign matter prevention device (10) is in the form of two flanges sandwiching a stainless steel wire mesh, and the wire mesh is fixed by spot welding; The supply air fan outlet foreign matter prevention device (8) is in the form of two flanges sandwiching a stainless steel wire mesh, and the wire mesh is fixed by spot welding.

2. The apparatus for secondary side maintenance of a horizontal steam generator for nuclear power plants according to claim 1, characterized in that, The device further comprises a side manhole foreign matter prevention mesh plate (4); The side manhole foreign matter prevention mesh plate (4) is installed on the manhole and has two through holes for passing through the supply air duct (7) and the exhaust air duct (3), respectively.

3. The apparatus for secondary side maintenance of a horizontal steam generator for nuclear power plants according to claim 1, characterized in that, The other end of the supply air duct (7) is connected with the throat of the supply air fan outlet foreign matter prevention device (8) through a steel binding belt.

4. The apparatus for secondary side maintenance of a horizontal steam generator for nuclear power plants according to claim 1, characterized in that, The device further comprises an exhaust air fan inlet foreign matter prevention device (2); The exhaust air fan inlet foreign matter prevention device (2) is connected and fixed with the air inlet of the exhaust air fan (1) through bolts and nuts.

5. The apparatus for secondary side maintenance of a horizontal steam generator for nuclear power plants according to claim 4, characterized in that, The other end of the exhaust air duct (3) is connected with the throat of the exhaust air fan inlet foreign matter prevention device (2) through a steel binding belt.

6. The device for secondary side maintenance of a horizontal steam generator for nuclear power plants according to any one of claims 1-5, characterized in that, The air inlet opening part of the exhaust air duct (3) is arranged upward.

7. The apparatus for secondary side maintenance of a horizontal steam generator for nuclear power plants according to claim 6, characterized in that, The air inlet of the exhaust air duct (3) has three.

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