A method and device for isolating, maintaining pressure and overhauling a helium compressor in a high-temperature gas-cooled reactor

Abstract

The present invention relates to a method and device for isolating and maintaining pressure during the overhaul of a helium compressor in a high-temperature gas-cooled reactor, belonging to the technical fields of reactor equipment sealing and overhaul. During the normal operation of the reactor, the screw-lift overhaul device in the overhaul device is placed in the helium atmosphere above the pressure vessel. When maintenance is required, the overhaul device lowers the helium compressor to the lower limit position, closes the pressure-maintaining overhaul isolation valve, rebuilds the primary circuit pressure boundary, isolates the component to be repaired, and performs the overhaul; after the overhaul is completed, the overhauled helium compressor is lifted by the screw-lift overhaul device and tightened against the upper sealing surface to achieve the pre-tightening force for sealing; the screw-lift overhaul device is driven by a motor and a reducer and lifts along the guide rails with self-locking function evenly arranged on the inner wall; the jacket cooling system exchanges heat with the metal wall surface of the equipment, cools the internal environment of the equipment and maintains a local low-temperature helium environment to prevent the insulation of the stator winding of the helium compressor from overheating and failing and the reduction motor from failing.

Description

Technical Field

[0001] The present invention relates to a method and device for isolating and maintaining pressure during the overhaul of a helium compressor in a high-temperature gas-cooled reactor, belonging to the technical fields of reactor equipment sealing and overhaul. Background Art

[0002] A high-temperature gas-cooled reactor is a type of gas-cooled reactor that uses helium as a coolant. The outlet temperature of the reactor core is close to 750 - 1000 °C. The high-temperature gas-cooled reactor nuclear power plant uses a helium compressor to drive the helium coolant to circulate. During reactor startup, power operation, shutdown and other conditions, it provides a sufficient flow of helium to pass through the primary loop system to take away the heat generated by the reactor core, ensuring core cooling. The helium compressor in the demonstration project is located above the steam generator. The helium compressor is at the hot end of the helium cycle and cools the helium in the motor cavity through a nuclear secondary cooler, enabling the motor and the electromagnetic drive device to operate at an appropriate temperature. If a problem occurs during the operation of the helium compressor, the reactor needs to be completely shut down, the top cover needs to be completely opened, and the helium compressor is lifted out by a ring crane into an atmosphere isolation device (filled with helium). The atmosphere isolation device connects the overhaul environment with the primary loop and isolates it from the outside world, forming a slightly positive pressure helium environment to prevent air from entering the primary loop when the main helium blower is disassembled, lifted and reinstalled, affecting the performance of the reactor working medium. However, the preparation work for the overhaul conditions takes about several weeks, and the shutdown time is relatively long, resulting in relatively large economic losses.

[0003] Chinese Patent Application No. 201910985914 discloses a rolling screw jack, the structure of which is as Figure 1 shown. The device mainly consists of a - small bevel gear, b - large bevel gear, c - arc thread nut, d - thrust bearing, e - pin, f - ball nut, g - ball screw, h - ejector rod, i - support, j - anti-rotation screw. When lifting a heavy object, it replaces the sliding screw with a large friction in the current mechanical jack with a rolling screw with extremely small friction. When pausing midway and lowering the load, it still uses the sliding screw with self-locking ability to achieve reliable hovering and steady descent. Summary of the Invention

[0004] The object of the present invention is to propose a method and device for isolating and maintaining pressure during the overhaul of a helium compressor in a high-temperature gas-cooled reactor, using the existing up-and-down lifting device in a high-temperature gas-cooled reactor to perform primary loop pressure-maintaining core extraction maintenance on the helium compressor placed under the steam generator in the reactor, reducing the shutdown time caused by the overhaul of the helium compressor, or enabling overhaul under non-shutdown conditions.

[0005] The helium compressor isolation and pressure-maintaining maintenance device proposed by the present invention includes a screw lifting main body, a jacket cylinder body 2, a pressure vessel cylinder body 3, an upper support plate 6, a lower support plate 1, an upper maintenance isolation valve 13 and a lower maintenance isolation valve 10. The jacket cylinder body 2 is sleeved outside the pressure vessel cylinder body 3. The jacket cylinder body 2 is provided with a cooling water inlet 22 and a cooling water outlet 16. The pressure vessel cylinder body 3 is provided with a vacuum pumping port 18. A guide rail 8 is machined on the inner wall of the upper part of the pressure vessel cylinder body 3. The helium compressor 7 is placed on the upper support plate 6 inside the pressure vessel cylinder body 3. The upper maintenance isolation valve 13 and the lower maintenance isolation valve 10 are installed above the helium compressor 7 through a connecting flange 15. The screw lifting main body is fixed on the lower support plate 1 inside the pressure vessel cylinder body 3. The upper support plate 6 moves up and down in the pressure vessel cylinder body 3 through the guide rail 8. The screw shaft 24 of the screw lifting main body is interlocked with the upper support plate 6.

[0006] The screw lifting main body in the above-mentioned maintenance device is composed of a screw lifting main body 5, a screw shaft 24, a hollow sleeve 25, a threaded sleeve 26, a first bearing 19, a coupling 20 and a reduction motor 4. The hollow sleeve 25, the first bearing 19, the coupling 20 and the reduction motor 4 are coaxially installed in the screw lifting main body 5 from top to bottom. The reduction motor 4 is fixed on the lower support plate 1. The screw shaft 24 is placed inside the hollow sleeve 25. The top end of the inner wall of the shell of the screw lifting main body 5 is connected to a sleeve limit key 35 by a rivet. A key groove 38 matching with the sleeve limit key 35 is left outside the hollow sleeve 25. The direction of the key groove 38 is parallel to the axis direction. The threaded sleeve 26 is in interference fit connection with the hollow sleeve 25 and is positioned by a positioning pin 37 between the two to prevent circumferential rotation of the threaded sleeve 26. The male thread on the inner surface of the threaded sleeve 26 meshes with the female thread on the outer surface of the screw shaft 24. The lower end of the screw shaft 24 is connected to the output shaft of the reduction motor 4 through the first bearing 19 and the coupling 20.

[0007] In the above-mentioned screw lifting main body, the lower end of the screw shaft 24 drives the driven shaft helical gear 32 to rotate through the drive shaft helical gear 33. The driven shaft helical gear 32 meshes with the screw shaft 24 to transmit power to the screw shaft 24, realizing the rising and falling process of the maintenance device.

[0008] In the above-mentioned screw lifting main body, the reduction motor 4 and the magnetic drive device are placed outside the pressure vessel cylinder body 3. The lower end of the screw shaft 24 extends out of the pressure vessel cylinder body 3 and is connected to the output shaft of the reduction motor 4 through the magnetic drive device.

[0009] In the above-mentioned maintenance device, a concave sleeve 34 is provided at the lower end of the pressure vessel cylinder body 3. The concave sleeve 34 is welded to the lower end of the pressure vessel cylinder body 3. The upper end of the concave sleeve 34 is welded to the isolation sleeve 29 to form a closed boundary. The reduction motor 4 and the magnetic drive device are placed in the internal space of the concave sleeve 34. The lower end of the spiral shaft 24 extends out of the pressure vessel cylinder body 3 and then extends into the concave sleeve 34, and is connected to the output shaft of the reduction motor 4 through the magnetic drive device.

[0010] The isolation and pressure-maintaining maintenance method for the helium compressor of the high-temperature gas-cooled reactor proposed by the present invention includes the following steps:

[0011] (1) Build a high-temperature gas-cooled reactor helium compressor isolation and pressure-maintaining maintenance device as described above;

[0012] (2) When the reactor is operating normally, the high-temperature gas-cooled reactor helium compressor 7 is placed on the limit base 23 of the upper support plate 6 inside the pressure vessel cylinder body 3 of the maintenance device. The upper part of the pressure vessel cylinder body 3 is in a helium atmosphere, and the helium compressor 7 is interconnected with the primary circuit 12 of the reactor;

[0013] (3) When the helium compressor 7 needs to be repaired, start the reduction motor 4. The reduction motor 4 transmits the torque to the spiral shaft 24. The spiral shaft 24 meshes with the threaded sleeve 26, and the threaded sleeve 26 drives the hollow sleeve 25 to move downward along the axis. The helium compressor 7 descends to the lowest position along with the upper support plate 6 of the spiral lifting body 5;

[0014] (4) By operating the handwheel 9, close the upper maintenance isolation valve 13 and the lower maintenance isolation valve 10 successively. Start the vacuum pumping system to pump out the hot helium in the pressure vessel cylinder body 3 from the vacuum pumping port 18. Remove the helium compressor 7 to be repaired through the bolts on the connecting flange 15, realizing the isolation and pressure-maintaining maintenance of the high-temperature gas-cooled reactor helium compressor.

[0015] The isolation and pressure-maintaining maintenance method and device for the helium compressor of the high-temperature gas-cooled reactor proposed by the present invention have the following characteristics and advantages:

[0016] 1. The isolation and pressure-maintaining maintenance device for the helium compressor of the high-temperature gas-cooled reactor of the present invention can realize the atmosphere isolation between the primary circuit pressure boundary and the pressure vessel, and complete the maintenance of the core-pulling part of the helium compressor; this maintenance device realizes the closure of the primary circuit during the maintenance process through a double isolation valve group, ensuring that the radioactivity of the primary circuit does not leak. After the maintenance is completed, the vacuum pumping pipeline evacuates the hot helium in the equipment, opens the double isolation valves, and jacks up the helium compressor through the maintenance device until the top sealing surface enters the rabbet, and the jacking height reaches the set jacking distance. This maintenance device is convenient for maintenance, reduces the reactor shutdown time caused by maintenance, and even enables maintenance under the condition of non-reactor shutdown.

[0017] 2. The reduction motor in the maintenance device of the present invention drives the mechanical maintenance device to realize the rising and falling process. The mechanical spiral lifting maintenance device has a simple structure and is safe and reliable. During the operation of the helium compressor, the spiral lifting device can provide sufficient pressure to ensure the sealing between the helium compressor and the primary circuit of the upper reactor.

[0018] 3. In the spiral lifting body of the maintenance device of the present invention, the spiral shaft 24, the threaded sleeve 26, the first bearing 19, etc. are all oil-free and self-lubricating, which ensures the reliability and life of the device and greatly reduces the failure and maintenance caused by lubrication failure of the spiral shaft 24, the threaded sleeve 26, the first bearing 19, etc. of the lifting device.

[0019] 4. The maintenance device of the present invention cools the maintenance device through an external jacket to maintain the required low temperature environment in the equipment at all times. The cooling system replaces the nuclear secondary cooler that originally comes with the helium compressor body. Since the cooling system is outside the pressure boundary (outside the pressure vessel), the risk of the cooler breaking can be avoided. The helium compressor part can be used in one use and one standby. During the maintenance process, after the helium compressor to be repaired is removed, the standby helium compressor can be directly installed to continue normal operation, reducing the downtime caused by maintenance, and even maintenance can be carried out without stopping the reactor. The maintenance device of the present invention can be used in the operation or shutdown of high-temperature gas-cooled reactors to achieve the lifting and lowering of helium compressors, isolation of the pressure boundary of a circuit, pressure maintenance, rapid maintenance, or similar application fields such as petrochemicals and electricity. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a structural schematic diagram of an existing rolling screw jack.

[0021] Figure 2 It is a structural schematic diagram of the high temperature gas-cooled reactor helium compressor isolation and pressure maintenance device of the present invention.

[0022] Figure 3 This is a schematic diagram of the maintenance device structure when the helium compressor is in working condition.

[0023] Figure 4 for Figure 2 The shown part is an enlarged view of the top limit base of the maintenance device.

[0024] Figure 5 for Figure 2 The shown figure is a partial enlarged view of the transmission and bearing parts of the maintenance device.

[0025] Figure 6 for Figure 2 A partial enlarged view of the threaded sleeve and the hollow sleeve shown.

[0026] Figure 7 for Figure 2An embodiment of the maintenance device shown.

[0027] Figure 8 Another structural schematic diagram of the maintenance device of the present invention.

[0028] Figure 9 is Figure 8 A partial enlarged view of the maintenance device shown.

[0029] Figure 10 Another structural schematic diagram of the maintenance device of the present invention.

[0030] Figures 1 - 10 In it, 1 is the lower support plate, 2 is the clamping sleeve body, 3 is the pressure vessel body, 4 is the reduction motor, 5 is the screw lifting main body, 6 is the upper support plate, 7 is the helium compressor, 8 is the guide rail, 9 is the operation handwheel, 10 is the lower maintenance isolation valve, 11 is the gate plate, 12 is the primary circuit of the reactor, 13 is the upper maintenance isolation valve, 14 is the intermediate buffer zone, 15 is the connecting flange, 16 is the cooling water outlet, 17 is the maintenance support, 18 is the vacuum extraction port, 19 is the first bearing, 20 is the coupling, 21 is the electrical penetration, 22 is the cooling water inlet, 23 is the limit base, 24 is the screw shaft, 25 is the hollow sleeve, 26 is the threaded sleeve, 27 is the connecting key, 28 is the inner magnetic rotor, 29 is the isolation sleeve, 30 is the outer magnetic rotor, 31 is the second bearing, 32 is the driven shaft helical gear, 33 is the drive shaft helical gear, 34 is the concave sleeve, 35 is the sleeve limit key, 37 is the positioning pin, 38 is the keyway. Detailed implementation manners

[0031] The high-temperature gas-cooled reactor helium compressor isolation and pressure-maintaining maintenance device proposed by the present invention has a structure as shown in Figure 2 and Figure 3 shown, and includes a screw lifting main body, a clamping sleeve body 2, a pressure vessel body 3, an upper support plate 6, a lower support plate 1, an upper maintenance isolation valve 13 and a lower maintenance isolation valve 10. The clamping sleeve body 2 is sleeved outside the pressure vessel body 3. The clamping sleeve body 2 is provided with a cooling water inlet 22 and a cooling water outlet 16. The pressure vessel body 3 is provided with a vacuum extraction port 18. A guide rail 8 is machined on the inner wall of the upper part of the pressure vessel body 3. The helium compressor 7 is placed on the upper support plate 6 inside the pressure vessel body 3. The upper maintenance isolation valve 13 and the lower maintenance isolation valve 10 are installed above the helium compressor 7 through a connecting flange 15. The screw lifting main body is fixed on the lower support plate 1 inside the pressure vessel body 3. The upper support plate 6 moves up and down in the pressure vessel body 3 through the guide rail 8. The screw shaft 24 of the screw lifting main body is interlocked with the upper support plate 6.

[0032] The above-mentioned screw lifting main body has a structure as shown in Figure 4 and Figure 5As shown in the figure, it consists of a spiral lifting main body 5, a spiral shaft 24, a hollow sleeve 25, a threaded sleeve 26, a first bearing 19, a coupling 20, and a reduction motor 4. The hollow sleeve 25, the first bearing 19, the coupling 20, and the reduction motor 4 are coaxially installed in the spiral lifting main body 5 from top to bottom, and the reduction motor 4 is fixed on the lower support plate 1. The spiral shaft 24 is placed inside the hollow sleeve 25. The top end of the inner wall of the shell of the spiral lifting main body 5 is connected to a sleeve limit key 35 by a rivet. There is a keyway 38 on the outside of the hollow sleeve 25 that matches the sleeve limit key 35. The direction of the keyway 38 is parallel to the axis direction. The fit between the sleeve limit key 35 and the keyway 38 ensures that the hollow sleeve 25 can only move along the axial direction, as Figure 4 shown. The threaded sleeve 26 is connected to the hollow sleeve 25 by interference fit. The end of the counterbore can limit the axial position of the threaded sleeve 26, and they are positioned by a positioning pin 37 to prevent the circumferential rotation of the threaded sleeve 26, as Figure 6 shown. The male thread on the inner surface of the threaded sleeve 26 meshes with the female thread on the outer surface of the spiral shaft 24. The lower end of the spiral shaft 24 is connected to the output shaft of the reduction motor 4 through the first bearing 19 and the coupling 20 that can bear a large axial force, as Figure 5 shown. The spiral shaft 24, the threaded sleeve 26, the first bearing 19, etc. all adopt oil-free self-lubrication, which ensures the reliability and service life of the device and greatly reduces the failures and repairs caused by the lubrication failure of the spiral shaft 24, the threaded sleeve 26, the first bearing 19, etc. of the lifting device.

[0033] The above Figure 2 and Figure 3 shown maintenance device, in which the lower end of the spiral shaft 24 drives the driven shaft helical gear 32 to rotate through the drive shaft helical gear 33. The driven shaft helical gear 32 meshes with the spiral shaft 24 to transmit power to the spiral shaft 24, realizing the rising and falling process of the maintenance device. As Figure 7 shown.

[0034] The above Figure 2 and Figure 3 shown maintenance device, in which the reduction motor 4 and the magnetic drive device are placed outside the pressure vessel cylinder body 3. The pressure vessel cylinder body 3 remains intact. The lower end of the spiral shaft 24 extends out of the pressure vessel cylinder body 3 and is connected to the output shaft of the reduction motor 4 through the magnetic drive device. As Figure 8 and Figure 9 shown. The reduction motor 4 transmits the torque to the outer magnetic rotor 30 of the magnetic drive device, and the outer magnetic rotor 30 transmits the torque to the inner magnetic rotor 28 of the magnetic drive device through magnetic force, as Figure 9As shown in the figure. The inner magnetic rotor 28 is connected to the screw shaft 24 in a matching manner, so as to realize the rising and falling process of the upper support plate 6 of the above-mentioned maintenance device. In the magnetic drive device, the inner magnetic rotor 28 and the outer magnetic rotor 30 are separated by the isolation sleeve 29, and the isolation sleeve 29 is welded to the pressure vessel head as a whole, so as to ensure the sealing and integrity of the structure. Since the motor is placed outside the pressure vessel cylinder body 3 in this structure, the influence of internal space heat dissipation on the reduction motor 4 does not need to be considered.

[0035] The above-mentioned Figure 2 and Figure 3 The maintenance device shown, wherein the lower end of the pressure vessel cylinder body 3 is provided with an inner concave sleeve 34, the inner concave sleeve 34 is welded to the lower end of the pressure vessel cylinder body 3, the upper end of the inner concave sleeve 34 is welded to the isolation sleeve 29 to form a closed boundary, the reduction motor 4 and the magnetic drive device are placed in the internal space of the inner concave sleeve 34, the reduction motor 4 and the magnetic drive device are located in the atmospheric environment, and the lower end of the screw shaft 24 extends out of the pressure vessel cylinder body 3 and then extends into the inner concave sleeve 34 and is connected to the output shaft of the reduction motor 4 through the magnetic drive device. As Figure 10 shown in the figure.

[0036] The isolation and pressure maintenance method for the helium compressor of the high-temperature gas-cooled reactor proposed by the present invention includes the following steps:

[0037] (1) Build a high-temperature gas-cooled reactor helium compressor isolation and pressure maintenance device as Figure 2 shown in the figure;

[0038] (2) When the reactor is operating normally, the high-temperature gas-cooled reactor helium compressor 7 is placed on the limit base 23 of the upper support plate 6 in the pressure vessel cylinder body 3 of the screw lifting main body. The upper part of the pressure vessel cylinder body 3 is in a helium atmosphere, and the helium compressor 7 is interconnected with the primary loop 12 of the reactor;

[0039] (3) When the helium compressor 7 needs to be repaired, start the reduction motor 4. The reduction motor 4 transmits the torque to the screw shaft 24. The screw shaft 24 meshes with the threaded sleeve 26. The threaded sleeve 26 is in interference fit with the hollow sleeve 25 and is positioned by the positioning pin 37. The threaded sleeve 26 cannot rotate circumferentially, and at the same time, the threaded sleeve can withstand the end of the counterbore, so that the threaded sleeve 26 drives the hollow sleeve 25 to move axially. The hollow sleeve 25 moves downward axially, the pressing force between the fan cover of the helium compressor 7 and the fan diffuser gradually decreases, and at the same time, under the gravity of the helium compressor 7, the upper support plate 6, the helium compressor 7 descends with the upper support plate 6 of the screw lifting main body 5, and the helium compressor 7 is lowered to the lowest position by the maintenance device;

[0040] (4) By operating the handwheel 9, first close the upper maintenance isolation valve 13 and then close the lower maintenance isolation valve 10. After the lower maintenance isolation valve 10 is shut off and meets the technical requirements, a new primary circuit pressure boundary is constructed, and the helium compressor 7 is isolated outside. Start the vacuum pumping system, and extract the hot helium gas in the pressure vessel cylinder body 3 from the vacuum pumping port 18. Remove the helium compressor 7 to be repaired through the bolts on the connecting flange 15. Since the pressure in the primary circuit remains constant throughout the maintenance process, the isolation and pressure maintenance repair of the helium compressor of the high-temperature gas-cooled reactor can be achieved.

[0041] The working principle of the isolation and pressure maintenance repair device for the helium compressor of the high-temperature gas-cooled reactor proposed by the present invention is as follows:

[0042] The screw lifting main body in the maintenance device of the present invention is placed in the helium atmosphere of the pressure vessel. The nuclear safety class I pressure maintenance repair isolation double-valve group device is installed between the reduced-diameter section of the bottom head of the steam generator and the nuclear safety-class pressure-bearing cylinder. Under the maintenance condition of the helium compressor, the pressure maintenance repair isolation valve can achieve the atmosphere isolation between the primary circuit pressure boundary and the pressure vessel. The core-pulling part of the helium compressor is lowered to the lowest position at the lower part of the pressure vessel through the maintenance device. After the pressure maintenance repair isolation valve is closed, a new primary circuit pressure boundary is constructed, and the maintenance component and the pressure vessel are isolated outside the primary circuit pressure boundary for maintenance. After the maintenance is completed, the core-pulling part of the repaired helium compressor is lifted through the maintenance device and pressed tightly against the top sealing surface to achieve a certain pre-tightening force for sealing. The maintenance device is lifted and lowered along three guide rails evenly arranged along the inner wall of the cylinder, and has a self-locking and anti-detaching function. Throughout the lifting process, it is driven by an external electric motor. When the motor driver controls the reduction motor to rotate forward, the screw drives the maintenance device to rise. When the motor driver controls the reduction motor to rotate backward, the screw drives the maintenance device to descend. The purpose of the double-valve group is double insurance for in-depth defense. The leakage rate of any single valve meeting the technical requirements can ensure the isolation effect. There is a jacket outside the pressure vessel, and the jacket exchanges heat with the metal wall surface of the equipment, which can cool the internal environment of the pressure vessel, maintain a local low-temperature helium environment inside the equipment, and prevent the insulation of the stator winding of the helium compressor from overheating and failing.

[0043] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0044] The reduction motor 4 in the maintenance device of the present invention is built into the cavity at the lower part of the maintenance device. Through holes are opened on the outer shell at the cavity of the screw-lifting maintenance device to ensure that the internal cavity space of the maintenance device can communicate with the internal space of the pressure vessel cylinder 3, and the heat generated by the internal reduction motor 4 can be dissipated into the space of the pressure vessel cylinder 3 through the through holes on the outer shell. The base of the reduction motor 4 is bolted and fixed to the bottom cover plate of the maintenance device. The main shaft of the reduction motor 4 is connected to one end of the coupling 20 through the connecting key 27. The first bearing 19 is connected with an interference fit to the inner flange of the outer shell of the maintenance device. The smooth end of the screw shaft 24 passes through the inner ring of the paired first bearings 19 and has an interference fit with the inner ring of the first bearing 19. The smooth end of the screw shaft 24 passing through the first bearing 19 is connected to the other end of the coupling 20 through the connecting key 27, thereby realizing the rotational drive of the screw shaft 24. The first bearing 19 has a solid lubrication function and can bear a large axial force. There is a hollow sleeve 25 outside the screw shaft 24. The lower end of the hollow sleeve 25 is connected to the screw shaft 24 through a solid-lubricated threaded sleeve 26 with internal threads. A counterbore matching the outer diameter of the length of the threaded sleeve 26 is left inside the hollow sleeve 25. The threaded sleeve 26 is connected to the hollow sleeve 25 with an interference fit, and the end of the counterbore can limit the axial position of the threaded sleeve, and the two are positioned through the positioning pin 37 to prevent the circumferential rotation of the threaded sleeve 26, as Figure 6As shown in the figure. A thick-walled bottom support ring cylinder is welded to the pressure vessel head. The upper part of the bottom support ring cylinder is welded with a lower support plate 1. A rabbet is set on the lower support plate 1 to fix the maintenance device. At the same time, holes are opened on the outer shell of the maintenance device for connecting thermocouples. An upper support plate 6 is installed on the upper part of the maintenance device. The upper support plate 6 is connected to three guide rails 8 that are evenly fixed on the side wall of the pressure vessel through bolts. The guide rails are welded or bolted to the pressure vessel cylinder body 3, which can ensure the stable operation of the upper support plate 6 during the lifting and lowering process without tipping over. On the upper support plate 6, a limit base 23 is set, and the helium compressor 7 can be located within the limit base 23 to prevent the helium compressor 7 from tipping over. An electrical penetration 21 is provided on the bottom head at the lowest part of the pressure vessel, which is convenient for ensuring the internal seal and pressure stability when the cable is led out. The upper part of the pressure vessel is a butt-welded connecting flange 15. The connecting flange 15 is bolted in the order of the upper maintenance isolation valve 13 and the lower maintenance isolation valve 10. The lower maintenance isolation valve 10 and the upper maintenance isolation valve 13 are arranged alternately, one on the left and one on the right, one on the upper and one on the lower. The upper maintenance isolation valve 13 is connected to the reactor primary loop 12, and the lower maintenance isolation valve 10 is bolted to the connecting flange. The two isolation valves are bolted to each other. The purpose of the double-valve group is double insurance for in-depth defense. The leakage rate of any single valve meeting the technical requirements can ensure the isolation function. A jacket cylinder 2 is provided on the outer wall of the pressure vessel cylinder body 3. The jacket cylinder 2 exchanges heat with the metal wall surface of the pressure vessel cylinder body 3 to maintain a low-temperature environment inside the pressure vessel. A cooling inlet 22 and a cooling water outlet 16 are provided on the jacket, and the cooling water enters from the bottom and exits from the top for countercurrent heat exchange.

[0045] In the maintenance device of the present invention, the flange bolts of the lower maintenance isolation valve 10 are welded to the upper maintenance isolation valve 13 with a thick-walled pipe. In the normal working state, the maintenance device is in a compressed state with the base of the upper helium compressor 7. The weight of the helium compressor 7 is about 8 tons, and the lifting force provided by the device of the present invention is about 20t. The maintenance device is lifted and lowered along three guide rails 8 evenly arranged along the inner wall. The guide rails are welded or bolted to the pressure vessel cylinder body 3 and have a self-locking and anti-disconnection function. The stroke of the screw lifting main body 5 is determined by the axial dimension chain of the upper maintenance isolation valve 13 and the lower maintenance isolation valve 10, about 1000mm. Limit switches and load indicators are provided at the upper ends of the guide rails 8 to prevent overload damage to the helium compressor volute. When the motor driver controls the reverse rotation of the reduction motor 4, through the drive of the reduction motor 4 (motor and planetary reducer), the torque is transmitted to the screw shaft 24 with threads. The screw shaft 24 meshes with the threaded sleeve 26 with solid lubrication function. The threaded sleeve 26 cannot rotate circumferentially but moves linearly downward along the axis. Therefore, the threaded sleeve 26 drives the hollow sleeve 25 to move downward along the axis. When the hollow sleeve 25 moves downward along the axis, the pressing force between the fan cover and the fan diffuser section gradually decreases. At the same time, under the action of the gravity of the helium compressor 7, the helium compressor 7 slowly descends with the upper support plate 6 of the screw lifting main body 5. The helium compressor 7 is lowered to the lowest position by the screw lifting main body 5. After the upper maintenance isolation valve 13 and the lower maintenance isolation valve 10 are closed and the leakage rate is detected to meet the technical requirements, the upper maintenance isolation valve 13 and the lower maintenance isolation valve 10 construct a new primary circuit pressure-bearing boundary, and the helium compressor 7 is isolated outside. After the pressure of the pressure vessel is relieved, the startup maintenance work can be unloaded.

[0046] Figure 3 The figure shows the state of the helium compressor during normal operation. When the motor driver controls the forward rotation of the reduction motor 4, the transmission process is the same as the above process. The reduction motor 4 drives the screw shaft 24 to rotate in the reverse direction. The screw shaft 24 drives the threaded sleeve 26 meshing with it to move axially upward along the axis, driving the hollow sleeve 25 to move linearly upward along the axis, thereby driving the helium compressor 7 on the upper support plate 6 to continuously rise until the load indicator reaches the set limit value. At the top, the upper support plate 6 rises to the upper limit of the guide rail 8, as Figure 3 shown, which can well ensure the seal between the helium compressor 7 and the primary circuit.

[0047] The maintenance device of the present invention has an overall structure of a double-layer shell pressure vessel or an external cooling jacket structure for a pressure vessel. It is suspended and installed below the upper maintenance isolation valve 13 and the lower maintenance isolation valve 10. The upper end face of the upper maintenance isolation valve 13 is connected to the primary circuit 12 of the reactor, and the lower end face of the lower maintenance isolation valve 10 is connected to the connection flange 15 of the pressure vessel. Heat insulation measures are taken at the connection to prevent excessive heat carried by helium from entering the pressure vessel cylinder 3. Cooling water flows through the middle of the jacket cylinder 2 to create a local low-temperature helium environment inside, preventing the insulation of the stator winding of the helium compressor from overheating and failing.

[0048] The electrical penetration 21 provided on the outer shell of the maintenance device supplies power to the reduction motor 4. During the maintenance of the helium compressor 7, the above-mentioned equipment can all be replaced and maintained.

[0049] Figure 8 and Figure 9 Another structural schematic diagram of the maintenance device of the present invention is shown. The reduction motor 4 is external, and its structure is generally the same as that shown in Figure 2 The difference is that the reduction motor 4 is placed outside the pressure vessel cylinder 3, and the pressure vessel cylinder 3 remains intact. The torque is transmitted to the outer magnetic rotor 30 through the reduction motor 4, and the outer magnetic rotor 30 transmits the torque to the inner magnetic rotor 28 through magnetic force, as shown in Figure 8 shown. The inner magnetic rotor 28 is connected and matched with the spiral shaft 24, so as to realize the rising and falling process of the upper support plate 6 of the above-mentioned spiral lifting main body. In the magnetic force-driven maintenance device, the inner magnetic rotor 28 and the outer magnetic rotor 30 are separated by the isolation sleeve 29, and the isolation sleeve 29 is welded to the pressure vessel head as a whole, so as to ensure the sealing and integrity of the structure. Since the motor is placed outside the pressure vessel cylinder 3 in this structure, the influence of internal space heat dissipation on the reduction motor 4 does not need to be considered.

[0050] Figure 10 Another structural schematic diagram of the maintenance device of the present invention is shown. For the magnetic force-driven device, refer to Figure 9 Most of the structure of the maintenance device is the same as that in Embodiment 1. The difference is that the reduction motor 4 and the magnetic force-driven device are located in the atmospheric environment. An opening is made on the pressure vessel cylinder 3 and welded to the concave sleeve 34. The other end of the concave sleeve 34 is welded / bolted to the isolation sleeve 29 to form a closed boundary. The reduction motor 4 and the magnetic force-driven device are externally embedded in the internal space of the concave sleeve 34. Since the reduction motor 4 and the magnetic force-driven device are in the atmospheric environment, the influence of space heat dissipation on the reduction motor 4 does not need to be considered. At the same time, it does not occupy too much external space, making the structure of the whole maintenance device more compact and facilitating disassembly, maintenance and transportation.

[0051] The above is only used to illustrate the present invention and is not a limitation of the present invention. According to the technical principle of the present invention, those of ordinary skill in the art can have various modified designs for a design scheme of the present invention. The scope of patent protection of the present invention shall be defined by the claims.

Claims

1. A helium compressor isolation and pressure maintenance overhaul device for a high-temperature gas-cooled reactor, characterized in that, The maintenance device includes a screw lifting main body (5), a jacket cylinder body (2), a pressure vessel cylinder body (3), an upper support plate (6), a lower support plate (1), an upper maintenance isolation valve (13) and a lower maintenance isolation valve (10). The jacket cylinder body (2) is sleeved outside the pressure vessel cylinder body (3). A cooling water inlet (22) and a cooling water outlet (16) are provided on the jacket cylinder body (2). A vacuum extraction port (18) is provided on the pressure vessel cylinder body (3). A guide rail (8) is machined on the inner wall of the upper part of the pressure vessel cylinder body (3). The helium compressor (7) is placed on the upper support plate (6) inside the pressure vessel cylinder body (3). The upper maintenance isolation valve (13) and the lower maintenance isolation valve (10) are installed above the helium compressor (7) through a connecting flange (15). The screw lifting main body is fixed on the lower support plate (1) inside the pressure vessel cylinder body (3). The upper support plate (6) moves up and down in the pressure vessel cylinder body (3) through the guide rail (8). The screw shaft (24) of the maintenance device is interlocked with the upper support plate (6). The screw lifting main body consists of a screw lifting main body (5), a screw shaft (24), a hollow sleeve (25), a threaded sleeve (26), a first bearing (19), a coupling (20) and a reduction motor (4). The hollow sleeve (25), the first bearing (19), the coupling (20) and the reduction motor (4) are coaxially installed in the screw lifting main body (5) from top to bottom. The reduction motor (4) is fixed on the lower support plate (1). The screw shaft (24) is placed inside the hollow sleeve (25). The top end of the inner wall of the shell of the screw lifting main body (5) is connected to a sleeve limit key (35) by rivets. A keyway 38 matching with the sleeve limit key (35) is left outside the hollow sleeve (25). The direction of the keyway (38) is parallel to the axis direction. The threaded sleeve (26) is connected with the hollow sleeve (25) by interference fit. The male thread on the inner surface of the threaded sleeve (26) meshes with the female thread on the outer surface of the screw shaft (24). The lower end of the screw shaft (24) is connected to the output shaft of the reduction motor (4) through the first bearing (19) and the coupling (20). An inner concave sleeve (34) is provided at the lower end of the pressure vessel cylinder body (3). The inner concave sleeve (34) is welded to the lower end of the pressure vessel cylinder body (3). The upper end of the inner concave sleeve (34) is welded to an isolation sleeve (29) to form a closed boundary. The reduction motor (4) and the magnetic drive device are placed in the inner space of the inner concave sleeve (34). The lower end of the screw shaft (24) extends out of the pressure vessel cylinder body (3) and then extends into the inner concave sleeve (34) and is connected to the output shaft of the reduction motor (4) through the magnetic drive device.

2. The overhaul device according to claim 1, characterized in that, The lower end of the screw shaft (24) drives the driven shaft helical gear (32) to rotate through the drive shaft helical gear (33). The driven shaft helical gear (32) meshes with the screw shaft (24) to transmit power to the screw shaft (24), realizing the rising and falling process of the maintenance device.

3. The overhaul device according to claim 1, characterized in that, The speed reducer motor (4) and the magnetic drive device are placed outside the pressure vessel cylinder body (3). The lower end of the spiral shaft (24) extends out of the pressure vessel cylinder body (3) and is connected to the output shaft of the speed reducer motor (4) through the magnetic drive device.

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