Steam generator primary side inlet and outlet connecting pipe sealing structure

Abstract

The invention belongs to the technical field of nuclear power equipment maintenance, and particularly relates to a steam generator primary side inlet and outlet connecting pipe sealing structure. The sealing device comprises a sealing ring seat with an outer side clamping groove, an inflatable sealing device and a bolt, the inflatable sealing device is arranged above the sealing ring seat, and the inflatable sealing device is fixedly connected with the sealing ring seat through the bolt. The sealing performance is improved by adopting the design of the bolt and the clamping groove on the outer side of the ring seat in combination with an inflatable sealing mode, the assembly and disassembly time is shortened, the influence of the sealing structure on the flowing characteristic of a coolant is reduced, and different maintenance conditions can be coped with.

Description

Technical Field

[0001] The invention belongs to the technical field of nuclear power equipment maintenance, and in particular relates to a sealing structure for an inlet and outlet pipe of a primary side of a steam generator. Background Art

[0002] When overhauling the steam generator (SG) lower head, it is necessary to seal the steam generator lower head to isolate the steam generator lower head inner cavity and the refueling pool. The steam generator lower head primary side inlet and outlet pipe sealing device is an important maintenance tool required for nuclear power plants.

[0003] When maintenance activities are carried out during low water levels, the primary side inlet and outlet pipe seals only need to have the function of preventing foreign matter; when the water level is high, the primary side inlet and outlet pipe seals need to have the functions of preventing foreign matter and sealing pressure.

[0004] The traditional sealing method for the primary inlet and outlet pipes of the lower head of the steam generator in a nuclear power plant is a plugging plate plus a sealing gasket structure. The plugging plate and the sealing gasket are fixed to the sealing ring seat of the primary inlet and outlet pipes, and the sealing gasket is pre-tightened by bolt connection to achieve sealing. The traditional sealing structure requires tightening multiple bolts, which is complicated to assemble and disassemble, takes a long time to install, and has poor sealing effect.

[0005] The bolt-free pneumatic sealing device can shorten the assembly and disassembly time and reduce the risk of loose foreign matter. The inner side of the sealing ring seat of the primary side pipe on the steam generator body forms a groove structure for engaging and fixing the plug. The structure and size of this sealing method may affect the primary side coolant flow characteristics because: (1) the groove is formed on the inner side of the ring seat, and the groove contacts and affects the fluid flow at the nozzle; (2) because the sealing surface that contacts the capsule needs to be reserved, the height of the sealing ring seat will increase accordingly.

[0006] The existing sealing structure has the disadvantages of insufficient sealing, long time consumption for assembly and disassembly, and large structural changes that affect fluid properties. Summary of the invention

[0007] The technical problem to be solved by the present invention is to provide a sealing structure for the inlet and outlet pipes on the primary side of a steam generator, which improves the sealing performance, shortens the assembly and disassembly time, reduces the influence of the sealing structure on the flow characteristics of the coolant, and can cope with different maintenance situations by adopting a bolt + outer groove design of a ring seat combined with an air expansion seal.

[0008] The technical solution adopted by the present invention is:

[0009] A steam generator primary side inlet and outlet pipe sealing structure comprises a sealing ring seat with an outer groove, an inflatable sealing device and bolts. The inflatable sealing device is placed above the sealing ring seat, and the inflatable sealing device is fixedly connected to the sealing ring seat by bolts.

[0010] The annular upper surface of the sealing ring seat is provided with 6 to 20 threaded holes and a clamping groove is provided on the outer side. The outer clamping groove structure is formed by surfacing welding or integrally processed with the ring seat.

[0011] The sealing ring seat is fixed to the connection between the nozzle of the primary side inlet pipe and the inner wall of the lower head by welding, and the height extending toward the inner side of the lower head is less than 150mm.

[0012] The inflatable sealing device includes a capsule, a support plate and a control system. The support plate includes a side plate and a middle support plate. The side plate is divided into left and right parts. The middle support plate is installed between the two side plates. The outer sides of the side plates and the middle support plate are downward groove structures. The groove cooperates with the sealing ring seat. The capsule is located between the side plate and the sealing ring seat. The control system is connected to the capsule.

[0013] After the side plates and the middle support plate are installed on the sealing ring seat, they are connected through slots evenly distributed along the circumference. For each slot, the slot bite depth is 6mm to 18mm, the bite width is 30mm to 240mm, the minimum matching area is 320mm2, and the bite surface is a truncated cone side surface that is 30° to 90° with the circumferential surface, excluding 90° or 90° annular surfaces.

[0014] The bowl-shaped capsule is tightly attached to the bottom of the left and right side panels, and the capsule and the left and right side panels are fastened by bolts to form a combination that can be folded in the middle; the middle support plate is independently separated through the manhole and installed in the middle of the left and right side panels to form a hollow cylindrical structure; the capsule is located between the support plate and the sealing ring seat, and the control system is connected to the capsule.

[0015] The pressure of the control system is set in advance, and the capsule is evacuated through the air pipe before installation and removal; after installation, the capsule is inflated through the air pipe to press the inner side of the sealing ring seat to achieve sealing.

[0016] A positioning baffle is provided at the end of each slot of the pneumatic sealing device. The pneumatic sealing device and the slot of the ring seat are engaged by rotating at a certain angle. After rotation, the positioning baffle reaches the positioning baffle to ensure accurate installation, thereby limiting the radial and axial movement of the device. The axial movement of the device is then limited by installing a stop screw.

[0017] The side plates and the middle support plate are made of low-density materials, and are made of aluminum alloy plates that have undergone surface anodizing treatment or titanium alloys that do not require surface treatment, including 2024-T351 aluminum alloy, 7075-T6 aluminum alloy and TC4 titanium alloy.

[0018] The capsule has two air bags located on the radial outer sides of the side plates and the middle support plate, and has a small space flat and approximately elliptical structure to improve the pressure bearing capacity; the material is a material with strong weather resistance, heat aging resistance, radiation resistance and hydrophobicity, as well as high tear resistance and toughness, including butadiene styrene, EPDM and modified EPDM rubber.

[0019] Compared with the prior art, the embodiments of the present invention have the following beneficial effects:

[0020] (1) The present invention provides a steam generator primary side inlet and outlet pipe sealing structure. Since the airbag is inflated and presses the inner wall of the sealing ring seat to deform, the sealing strength is large and the sealing effect is better. The bolt connection method is complicated and time-consuming to assemble and disassemble, and the outer slot method can shorten the working time. In addition, the number of parts is reduced, reducing the possibility of foreign matter entering the reactor coolant system.

[0021] (2) The present invention provides a sealing structure for the inlet and outlet pipes on the primary side of a steam generator, which can significantly reduce the resistance during disassembly and assembly and improve the efficiency of disassembly and assembly. Firstly, the capsule is evacuated in advance before maintenance to ensure the installation gap. Secondly, the ring seat of the outer groove structure makes the inner side flat, which can significantly reduce the friction between the capsule and the wall during disassembly and assembly.

[0022] (3) The present invention provides a steam generator primary side inlet and outlet pipe sealing structure, wherein the groove structure is located on the outer side of the sealing ring seat, so that the inner side is flat, thereby reducing the impact on the fluid at the primary side pipe, and the height of the ring seat is reduced, thereby reducing the impact on the fluid characteristics.

[0023] (4) The present invention provides a steam generator primary side inlet and outlet pipe sealing structure, which can realize different connection modes to cope with maintenance situations with different sealing requirements, and can achieve fast operation.

[0024] (5) The present invention provides a steam generator primary side inlet and outlet pipe sealing structure, the structure of the sealing ring seat retains the function of cooperating with the traditional plugging plate. The sealing structure proposed by the present invention can be implemented for both existing nuclear power plant equipment and new nuclear power plant equipment. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] 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 description of the embodiments. 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 creative work.

[0026] Figure 1 A schematic diagram of a steam generator primary side inlet and outlet pipe sealing structure proposed by the present invention;

[0027] Figure 2 A schematic diagram of a sealing ring seat structure according to the present invention;

[0028] Figure 3 The inflatable sealing structure (a) and its enlarged view (b) according to the present invention;

[0029] Figure 4 This is a schematic diagram of the installation to realize the anti-foreign matter function in Example 2 of this application;

[0030] Figure 5 This is a schematic diagram of the installation to achieve the functions of preventing foreign matter and sealing pressure in Example 3 of this application;

[0031] In the figure: 1-primary side inlet pipe; 2-sealing ring seat; 3-inflatable sealing device; 4-bolt; 5-manhole; 201-threaded hole; 202-slot structure; 301-capsule; 302-slot; 303-control system; 304-positioning baffle; 305-stop screw; 306-side plate; 307-middle support plate. DETAILED DESCRIPTION

[0032] 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.

[0033] In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the 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 orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", and "third" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance.

[0034] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0035] like Figure 1 and Figure 2 As shown, the present invention provides a steam generator primary side inlet and outlet pipe sealing structure, including a sealing ring seat 2 with an outer groove, an inflatable sealing device 3 and a bolt 4, wherein the inflatable sealing device 3 is placed above the sealing ring seat 2, and the inflatable sealing device 3 is fixedly connected to the sealing ring seat 2 by the bolt 4.

[0036] The annular upper surface of the sealing ring seat 2 has 6 to 20 threaded holes and a slot on the outside. The slot structure on the outside is formed by surfacing or integrally processed with the ring seat. The sealing ring seat 2 is fixed to the connection between the nozzle of the primary side inlet pipe 1 and the inner wall of the lower head by welding, and the height extending toward the inner side of the lower head is less than 150 mm.

[0037] like Figure 3 As shown, the inflatable sealing device 3 includes a capsule 301, a support plate and a control system 303. The support plate includes a side plate 306 and a middle support plate 307.

[0038] The side plate 306 is divided into two parts, the middle support plate 307 is installed between the two side plates 306, the outer sides of the side plates 306 and the middle support plate 307 are downward groove structures, and the grooves cooperate with the sealing ring seat 2. After the side plates 306 and the middle support plate 307 are installed on the sealing ring seat 2, they are connected through the card grooves 302 evenly distributed along the circumference. For each card groove 302, the card groove bite depth is 6mm~18mm, the bite width is 30mm~240mm, and the minimum matching area is: 320mm 2 The occlusal surface is a truncated cone side surface or a 90° annular surface that is 30° to 90° (excluding 90°) with the circumferential surface;

[0039] The bowl-shaped capsule 301 is tightly attached to the bottom of the left and right side plates 306. The capsule 301 and the left and right side plates 306 are fastened by bolts to form a combination that can be folded in the middle. The middle support plate 307 is separated and passed through the manhole 5, and installed in the middle of the left and right side plates 306 to form a hollow cylindrical structure; the capsule 301 is located between the support plate and the sealing ring seat 2, and the control system 303 is connected to the capsule 301. The pressure of the control system 303 is set in advance, and the capsule 301 is vacuumed through the air pipe before installation and removal; after installation, the capsule 301 is inflated through the air pipe to press the inner side of the sealing ring seat 2 to achieve sealing; each card slot 302 of the inflatable sealing device 3 has a positioning baffle 304 at the end, which is rotated at a certain angle to make the inflatable sealing device 3 and the card slot of the ring seat 2 fit together, and after rotation, it reaches the positioning baffle 304 to ensure accurate installation, thereby limiting the radial and axial movement of the device, and then the axial movement of the device is limited by installing the stop screw 305;

[0040] The side plates 306 and the middle support plate 307 are made of low-density materials, and are made of aluminum alloy plates with surface anodization treatment or titanium alloys that do not require surface treatment, including 2024-T351 aluminum alloy, 7075-T6 aluminum alloy, and TC4 titanium alloy.

[0041] The capsule 301 has two air bags located on the radial outer side of the side plate 306 and the middle support plate 307, and a small space flat approximate elliptical structure (a straight line segment plus two semicircles) is selected to improve the pressure bearing capacity. Materials with strong weather resistance, heat aging resistance, radiation resistance and hydrophobicity, as well as high tear resistance and toughness are used, including styrene-butadiene, EPDM and modified EPDM rubber.

[0042] Furthermore, two bolts 4 or all the bolts may be installed at symmetrical positions, and the bolts are installed in threaded holes distributed in an annular manner.

[0043] Example 1

[0044] The inflatable sealing device includes a capsule, a support plate and a control system. The flat portion of the bowl-shaped capsule is tightly attached to the bottom of the left and right side plates and fastened by bolts to form a combination that can be folded in the middle. The middle support plate 307 is independently separated through the manhole 5 and installed in the middle of the side plates to form a hollow cylindrical structure.

[0045] The support plate is made of 2024-T351 aluminum alloy with surface anodizing treatment.

[0046] The seal (capsule) of the inflatable sealing device has two air bags located on the radial outer side of the support plate. A small space flat approximate elliptical structure (a straight line segment plus two semicircles) is selected to improve the pressure bearing capacity. The material is EPDM rubber.

[0047] The support plate and the sealing ring seat are in contact through the slot. For each slot, the slot bite depth is 17mm, the bite width is 207mm, and the matching area is 3513mm 2 The occlusal surface is the side of a truncated cone that is 45 degrees to the circumferential surface.

[0048] There is a positioning baffle at the end of each slot of the inflatable sealing device. Rotating 22.5° allows the boss to embed into the groove. After rotation, it reaches the positioning baffle to ensure accurate installation, thereby limiting the radial and axial movement of the device, and then limiting the axial movement of the device by installing a stop screw.

[0049] Install all bolts in the circularly distributed threaded holes.

[0050] Example 2

[0051] When carrying out maintenance activities during low water level, the primary side inlet and outlet pipe sealing structure proposed by the present invention is adopted, such as Figure 4 shown.

[0052] The annular upper surface of the sealing ring seat has 8 threaded holes and a slot on the outside. The slot structure on the outside is integrally processed with the ring seat. The sealing ring seat is welded and fixed to the connection between the nozzle of the primary inlet pipe and the inner wall of the lower head. The height extending toward the inner side of the lower head is 103mm.

[0053] The left and right side support plates and the capsule assembly are folded in the middle and sent into the steam generator through the Φ406mm manhole to the working position. The middle support plate is separated and passed through the Φ406mm manhole and installed in the middle of the side plate to form a hollow cylindrical structure.

[0054] The support plate is made of 7075-T6 aluminum alloy with anodized surface.

[0055] The seal (capsule) of the inflatable sealing device has two air bags located on the radial outer side of the support plate. A small space flat approximate elliptical structure (a straight line segment plus two semicircles) is selected to improve the pressure bearing capacity. The material is EPDM rubber.

[0056] Then install two symmetrically positioned bolts without tightening them. The bolts are installed in the circularly distributed threaded holes.

[0057] Only one staff member is required to carry and operate it, thus realizing the function of preventing foreign objects.

[0058] Example 3

[0059] When the water level is high, the primary side inlet and outlet pipe sealing structure proposed by the present invention is adopted, such as Figure 5 shown.

[0060] The water inlet nozzle of the steam generator with an inner diameter of Φ787.4mm is sealed.

[0061] The annular upper surface of the sealing ring seat has 8 threaded holes and a slot on the outside. The slot structure on the outside is integrally processed with the ring seat. The sealing ring seat is welded and fixed to the connection between the nozzle of the primary inlet pipe and the inner wall of the lower head. The height extending toward the inner side of the lower head is 103mm, and the width of the ring seat is 44.5mm.

[0062] The assembly of the left and right side support plates and the capsule is folded in the middle and sent into the steam generator through the Φ406mm manhole to the working position. The middle support plate is separated and passed through the Φ406mm manhole and installed in the middle of the side plate 306 to form a hollow cylindrical structure.

[0063] The support plate is made of TC4 titanium alloy and does not require surface treatment.

[0064] The seal (capsule) of the inflatable seal device has two air bags, which are located on the radial outer side of the support plate, and a small space flat approximate elliptical structure (a straight line segment plus two semicircles) is selected to improve the pressure bearing capacity. The material is peroxide-cured EPDM.

[0065] The support plate and the sealing ring seat are in contact through 8 slots evenly distributed in the circumferential direction. For each slot, the slot bite depth is 12mm, the bite width is 207mm, the matching area is about 2480mm2, and the bite surface is a circular surface at 90° to the circumferential surface.

[0066] There is a positioning baffle at the end of each slot of the inflatable sealing device 3. Rotating about 22.5° allows the boss of the ring seat to be embedded in the slot. After rotation, it reaches the positioning baffle to ensure accurate installation, thereby limiting the radial and axial movement of the device, and then limiting the axial movement of the device by installing a stop screw.

[0067] Set the pressure of the control system in advance, and evacuate the airbags through the air pipe before installation and removal; after installation, provide 0.4MPa pressure to the two airbags and 0.1MPa pressure to the ring surface through the air pipe. The airbags are inflated and press the inner side of the sealing ring seat to achieve sealing.

[0068] Only one staff member is required to carry and operate it, realizing the functions of preventing foreign objects and sealing pressure.

[0069] It will be apparent to those skilled in the art that the invention is not limited to the details of the exemplary embodiments described above and that the invention can be implemented in other specific forms without departing from the spirit or essential features of the invention. Therefore, the embodiments should be considered exemplary and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description, and it is intended that all variations falling within the meaning and scope of the equivalent elements of the claims be included in the invention. Any reference numeral in a claim should not be considered as limiting the claim to which it relates.

[0070] In addition, it should be understood that although the present specification is described according to implementation modes, not every implementation mode contains only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment may also be appropriately combined to form other implementation modes that can be understood by those skilled in the art.

Claims

1. A steam generator primary side inlet and outlet pipe sealing structure, characterized in that: The invention comprises a sealing ring seat (2) with an outer groove, an air-expanding sealing device (3) and a bolt (4); the air-expanding sealing device (3) is placed above the sealing ring seat (2); and the air-expanding sealing device (3) is fixedly connected to the sealing ring seat (2) via the bolt (4).

2. The steam generator primary side inlet and outlet pipe sealing structure according to claim 1, characterized in that: The annular upper surface of the sealing ring seat (2) is provided with 6 to 20 threaded holes and has a clamping groove on the outer side. The outer clamping groove structure is formed by surfacing welding or integrally processed with the ring seat.

3. The steam generator primary side inlet and outlet pipe sealing structure according to claim 1, characterized in that: The sealing ring seat (2) is fixed to the connection between the nozzle of the primary side inlet pipe (1) and the inner wall of the lower head by welding, and the height extending toward the inside of the lower head is less than 150 mm.

4. The steam generator primary side inlet and outlet pipe sealing structure according to claim 1, characterized in that: The inflatable sealing device (3) comprises a capsule (301), a support plate and a control system (303); the support plate comprises a side plate (306) and an intermediate support plate (307); the side plate (306) is divided into two parts, a left part and a right part; the intermediate support plate (307) is installed between the two side plates (306); the outer sides of the side plates (306) and the intermediate support plate (307) are downward groove structures; the grooves cooperate with the sealing ring seat (2); the capsule (301) is located between the side plates (306) and the sealing ring seat (2); and the control system (303) is connected to the capsule (301).

5. The steam generator primary side inlet and outlet pipe sealing structure according to claim 4, characterized in that: After the side plates (306) and the middle support plate (307) are mounted on the sealing ring seat (2), they are connected via the slots (302) evenly distributed along the circumference. For each slot (302), the slot engagement depth is 6 mm to 18 mm, the engagement width is 30 mm to 240 mm, and the minimum mating area is 320 mm. 2 The occlusal surface is the side of a truncated cone that is 30° to 90° with the circumferential surface, and does not include a 90° or 90° annular surface.

6. The steam generator primary side inlet and outlet pipe sealing structure according to claim 4, characterized in that: The bowl-shaped capsule (301) is tightly attached to the bottom of the left and right side plates (306), and the capsule (301) and the left and right side plates (306) are fastened by bolts to form a combination that can be folded in the middle; the middle support plate (307) is independently separated and passed through the manhole (5), and is installed in the middle of the left and right side plates (306) to form a hollow cylindrical structure; the capsule (301) is located between the support plate and the sealing ring seat (2), and the control system (303) is connected to the capsule (301).

7. The steam generator primary side inlet and outlet pipe sealing structure according to claim 4, characterized in that: The pressure of the control system (303) is set in advance, and the capsule (301) is evacuated through the air pipe before installation and removal; after installation, the capsule (301) is inflated through the air pipe to press the inner side of the sealing ring seat (2) to achieve sealing.

8. The steam generator primary side inlet and outlet pipe sealing structure according to claim 4, characterized in that: A positioning baffle (304) is provided at the end of each slot (302) of the pneumatic sealing device (3). The pneumatic sealing device (3) and the slot of the ring seat (2) are engaged by rotating at a certain angle. After the rotation, the positioning baffle (304) is reached to ensure accurate installation, thereby limiting the radial and axial movement of the device. The axial movement of the device is then limited by installing a stop screw (305).

9. The steam generator primary side inlet and outlet pipe sealing structure according to claim 4, characterized in that: The side plates (306) and the middle support plate (307) are low-density materials, and are made of aluminum alloy plates that have undergone surface anodizing treatment or titanium alloys that do not require surface treatment, including 2024-T351 aluminum alloy, 7075-T6 aluminum alloy, and TC4 titanium alloy.

10. The steam generator primary side inlet and outlet pipe sealing structure according to claim 4, characterized in that: The capsule (301) has two air bags located on the radial outer sides of the side plates (306) and the middle support plate (307), and has a small space flat and approximately elliptical structure to improve the pressure bearing capacity; the material is a material with strong weather resistance, heat aging resistance, radiation resistance and hydrophobicity, as well as high tear resistance and toughness, including styrene-butadiene rubber, EPDM and modified EPDM rubber.

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