A dehumidification device and method for a generator rotor center hole

Abstract

The application discloses a kind of dehumidification device and method for generator rotor center hole, the dehumidification device includes: heating unit, the heating unit includes radiant heater and heat preservation component;Radiant heater is arranged on the outer surface of the rotor shaft, for the outer surface of the rotor shaft is heated to from outside the rotor center hole is heated, the heat preservation component is arranged on the outside of the heater and surrounds the periphery of the rotor shaft;Ventilation unit, the ventilation unit includes air source and air heater;Air heater obtains instrument air from air source, forms hot dry air after instrument air is heated, and is passed into rotor center hole from plug screw hole, from inside the rotor center hole is heated, and the water vapor generated in the rotor center hole is discharged from the conductive screw hole.The dehumidification device of the application can dry and insulate the inside of the rotor center hole without removing the conductive rod of the rotor center hole.

Description

Technical Field

[0001] This invention belongs to the field of generator technology, and particularly relates to a dehumidification device and method for the central hole of a generator rotor. Background Technology

[0002] As one of the main pieces of equipment in power generation companies, the 660MW salient-pole generator is susceptible to damage when the insulation inside the rotor center hole becomes damp. This can lead to a decrease in the local insulation of the generator rotor, and further deterioration of the insulation can cause grounding and inter-turn short circuits in the rotor windings, resulting in unit shutdown and seriously affecting the safe and stable operation of the power system. Furthermore, the manufacturing process of the rotor center hole is extremely complex, making it difficult for on-site maintenance personnel to thoroughly address the issue.

[0003] Figure 1 This is a schematic diagram of the structure of an existing generator rotor, such as... Figure 1 As shown, the rotor winding of the 660MW salient-pole generator is formed by connecting the rotor leads, conductive rod 9, and slip ring 12 with conductive screws 3 to create a complete rotor winding circuit. The conductive rod 9 consists of two semicircles, which are then insulated and bound to form a cylinder. This cylinder is then placed inside the generator rotor center hole 10 and secured by conductive screws 3 on both sides of the slip ring 12 and rotor retaining ring 13. The rotor center hole 10 is then sealed using a cold-fitting technique with a body sealing plate 14. The body sealing plate 14 has a sealing screw hole 15 in its center, containing a tapered screw for sealing tests of the generator rotor center hole 10. Currently, when dealing with moisture in the rotor center hole of the 660MW salient-pole generator, all conductive screws on both sides of the slip ring 12 and rotor retaining ring 13 must be removed. Then, the rotor center hole sealing plate 14 and the conductive rod 9 inside the center hole must be removed, and the moisture-affected area must be insulated. Because the rotor endplate uses cold-fitting technology, on-site maintenance is not feasible. Essentially, the existing endplate is destroyed and replaced with a new one, causing an imbalance in the generator rotor shaft system. If necessary, the generator must be returned to the factory for rotor dynamic balancing (overspeed) testing. This results in long maintenance cycles and high costs. Summary of the Invention

[0004] In view of the shortcomings of the existing technology, the present invention provides a dehumidification device and method for the central hole of a generator rotor, so as to solve the problem of how to dehumidify the central hole of a generator rotor that has become damp.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] This invention first provides a dehumidification device for the central hole of a generator rotor. The generator rotor includes a rotor shaft and a central hole. A body blocking plate is provided at the first end of the rotor shaft, and a rotor retaining ring is provided at the second end of the rotor shaft. The body blocking plate is provided with blocking screw holes, and the rotor retaining ring is provided with conductive screw holes. The dehumidification device includes:

[0007] A heating unit, comprising a radiant heater and a heat insulation component; the radiant heater is disposed on the outer surface of the rotor shaft and is used to heat the outer surface of the rotor shaft to heat the rotor center hole from the outside; the heat insulation component is disposed outside the heater and surrounds the periphery of the rotor shaft.

[0008] The ventilation unit includes an air source and an air heater. The air heater obtains instrument air from the air source, heats the instrument air to form hot dry air, and then introduces it into the rotor center hole through the plug screw hole to heat the rotor center hole from the inside. The water vapor generated in the rotor center hole by heating is discharged from the conductive screw hole.

[0009] Preferably, the ventilation unit further includes a first air pipe, a second air pipe, and a pressure sensor. The first air pipe is connected between the air source and the air heater, the second air pipe is connected between the air heater and the plugging screw hole, and the pressure sensor is disposed on the first air pipe.

[0010] Preferably, a flange is connected to the body plug plate, and the second air pipe is connected to the plug screw hole through the flange.

[0011] Preferably, the power supply of the radiant heater is AC220V, the output power of the radiant heater reaches 30kW or more, and the temperature of the radiant heater is adjustable from 0℃ to 100℃.

[0012] Preferably, the dehumidification device further includes a temperature monitoring unit, which includes a first temperature sensor, a second temperature sensor, and a third temperature sensor; the first temperature sensor is disposed on the outer surface of the rotor shaft and is used to detect the heating temperature of the outer surface of the rotor shaft; the second temperature sensor is disposed at the inlet of the plugging screw hole and is used to detect the temperature of the hot dry air introduced into the rotor center hole; the third temperature sensor is disposed at the outlet of the conductive screw hole and is used to detect the temperature of the gas discharged from the conductive screw hole.

[0013] This invention first provides a method for dehumidifying the center hole of a generator rotor, using the dehumidification device described above, the dehumidification method comprising:

[0014] S10. Remove the generator rotor from the generator stator and place it on the support bracket. Remove the plugging screws on the main body block plate to expose the plugging screw holes. Remove the upward-facing conductive screw holes of the rotor retaining ring to expose the conductive screw holes.

[0015] S20. Control the heating unit to heat the outer surface of the rotor shaft to heat the rotor center hole from the outside;

[0016] S30. Control the ventilation unit to introduce hot dry air from the plugging screw hole into the rotor center hole, heat the rotor center hole from the inside, and discharge the water vapor generated in the rotor center hole through the conductive screw hole.

[0017] Preferably, the temperature of the heating unit heating the outer surface of the rotor shaft is controlled to be no more than 90°C, the temperature of the hot dry air introduced into the center hole of the rotor is controlled to be no more than 75°C, and the temperature of the gas discharged from the conductive screw hole is controlled to be no less than 45°C.

[0018] Preferably, the temperature at which the heating unit heats the outer surface of the rotor shaft is controlled to be 85°C to 90°C.

[0019] Preferably, the humidity of the hot, dry air introduced into the central hole of the rotor is not higher than 20% RH and the pressure is in the range of 0 MPa to 0.6 MPa.

[0020] Preferably, the rotor shaft is heated to a predetermined time and then rotated 180° so that the exposed conductive screw holes face upwards.

[0021] This invention provides a dehumidification device and method for the central hole of a generator rotor. By using a heating unit to heat the outer surface of the rotor shaft, the central hole is heated from the outside, causing moisture to evaporate and form water vapor. Then, a ventilation unit introduces hot, dry air into the central hole, further heating the central hole from the inside to continue evaporation, and simultaneously expelling the water vapor generated during heating through the conductive screw holes. This achieves dehumidification of the central hole. Therefore, when the central hole of a generator rotor is damp, the dehumidification device and method provided in this invention can dry and insulate the interior of the central hole without removing the conductive rod, avoiding the problems of long maintenance cycles and high costs associated with generator rotor equipment. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the structure of an existing generator rotor;

[0023] Figure 2 This is a schematic diagram of the dehumidification device provided in an embodiment of the present invention;

[0024] Figure 3 This is a schematic diagram of the air inlet end of the dehumidification device provided in an embodiment of the present invention;

[0025] Figure 4 This is a schematic diagram of the exhaust end of the dehumidification device provided in an embodiment of the present invention. Detailed Implementation

[0026] To make the objectives, technical solutions, and advantages of the present invention clearer, specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. Examples of these preferred embodiments are illustrated in the drawings. The embodiments of the present invention shown in and described with reference to the drawings are merely exemplary, and the present invention is not limited to these embodiments.

[0027] It should also be noted that, in order to avoid obscuring the invention with unnecessary details, only the structures and / or processing steps closely related to the solution according to the invention are shown in the accompanying drawings, while other details that are not closely related to the invention are omitted.

[0028] This embodiment first provides a dehumidification device for the center hole of a generator rotor. Figure 2 This is a schematic diagram of the dehumidification device provided in an embodiment of the present invention, as shown below. Figure 1 and Figure 2 As shown, the dehumidification device includes a heating unit 4, which includes a radiant heater 41 and a heat insulation component 42. The radiant heater 41 is disposed on the outer surface of the rotor shaft 2 and is used to heat the outer surface of the rotor shaft 2 to heat the rotor center hole 10 from the outside. The heat insulation component 42 is disposed outside the heater 41 and surrounds the periphery of the rotor shaft 2.

[0029] Because the rotor shaft 2 is very thick, when dealing with moisture insulation inside the rotor center hole 10, it is necessary to heat the surface of the rotor shaft 2 corresponding to the outside of the rotor center hole 10 to assist in the treatment. A radiant heater 41 is used to heat the rotor shaft 2 from the outside, thus providing continuous heating to the surface of the rotor shaft 2 corresponding to the outside of the rotor center hole 10. Simultaneously, an insulation component 42 is added around the heating area to ensure uniform heating of the shaft surface during the heating process. Considering the need for the insulation component 42 to have high reflectivity, small weight, good sealing, high cost-effectiveness, and simple operation, tin foil and aluminum foil are preferred. The aluminum foil and tin foil should be approximately 1 meter long, 0.5 meters wide, and 20 micrometers thick. The radiant heater 41 is surrounded by aluminum foil and tin foil, and the insulation coverage area should not interfere with the periodic rotation of the rotor. By heating the rotor shaft 2 with the heater 41, the moisture inside the rotor center hole 10 evaporates, forming water vapor.

[0030] In another preferred embodiment, the insulation component 42 may also be made of insulation materials such as asbestos cloth, rock wool, or glass fiber.

[0031] Specifically, the power supply of the radiant heater 41 is AC220V, the output power of the radiant heater 41 reaches more than 30kW, and the temperature of the radiant heater 41 is adjustable from 0℃ to 100℃.

[0032] like Figure 1 and Figure 2 As shown, the dehumidification device includes a ventilation unit 5, which includes an air source 51 and an air heater 52. The air heater 52 obtains instrument air from the air source 51, heats the instrument air to form hot dry air, and then introduces it into the rotor center hole 10 through the plugging screw hole 15. This heats the rotor center hole 10 from the inside, and the water vapor generated in the rotor center hole 10 is discharged through the conductive screw hole 11. After heating the rotor shaft 2, hot dry air is then introduced into the rotor center hole 10, which is a secondary heating treatment of the rotor center hole 10. The hot dry air and the water vapor in the rotor center hole 10 mix and are discharged through the conductive screw hole 11 on the rotor. After the two heating processes, the inside of the rotor center hole 10 is dried and insulated.

[0033] In a preferred embodiment, the air heater 52 may be a duct-type heater.

[0034] In the preferred solution, such as Figure 2 As shown, the ventilation unit 5 further includes a first air pipe 53, a second air pipe 54, and a pressure sensor 55. The first air pipe 53 is connected between the air source 51 and the air heater 52, and the second air pipe 54 is connected between the air heater 52 and the plugging screw hole 15. The pressure sensor 55 is mounted on the first air pipe 53. Specifically, a flange is connected to the body plug plate 14, and the second air pipe 54 is connected to the plugging screw hole 15 through the flange. The flange prevents the leakage of hot dry air. The instrument air from the air source 51 is delivered to the air heater 52 through the first air pipe 53. After being heated by the air heater 52 to form hot dry air, it passes through the flange on the second air pipe 54 and is discharged into the rotor center hole 10 through the plugging screw hole 15.

[0035] Specifically, the air is filtered and dried by an air compressor and a refrigerated dryer to obtain instrument air. The instrument air has a humidity of less than 20% RH and a pressure of 0-0.6 MPa, which can be adjusted. The air source 51 uses instrument air, and the air heater 52 is a duct-type heater. The clean instrument air is heated by the duct-type heater and then passed through the second air pipe 54 into the rotor center hole 10 to remove the moisture inside the generator rotor center hole 10, so as to achieve the purpose of drying and insulation treatment.

[0036] Specifically, Figure 3 This is a schematic diagram of the air inlet end of the dehumidification device provided in an embodiment of the present invention, as shown below. Figure 3 As shown, clean instrument air is heated by a duct-type heater to form hot dry air 100, which then enters the rotor center hole 10 through the plug screw hole 15. The hot dry air 100 passes through the gap between the conductive rod 9 and the rotor center hole 10, heating the rotor center hole 10 from the inside to evaporate the moisture. The water vapor generated by heating in the rotor center hole 10 is discharged from the conductive screw hole 11. Figure 4 This is a schematic diagram of the exhaust end of the dehumidification device provided in an embodiment of the present invention, as shown below. Figure 4 As shown, Figure 4 200 indicates the air discharged from the rotor center hole 10.

[0037] In the preferred solution, such as Figure 2 As shown, the dehumidification device further includes a temperature monitoring unit 6, which includes a first temperature sensor 61, a second temperature sensor 62, and a third temperature sensor 63. The first temperature sensor 61 is disposed on the outer surface of the rotor shaft 2 and is used to detect the heating temperature of the outer surface of the rotor shaft 2. The second temperature sensor 62 is disposed at the inlet of the plugging screw hole 15 and is used to detect the temperature of the hot dry air introduced into the rotor center hole 10. The third temperature sensor 63 is disposed at the outlet of the conductive screw hole 11 and is used to detect the temperature of the gas discharged from the conductive screw hole 11.

[0038] Specifically, the temperature monitoring unit 6 also includes a controller. The temperature sensor 61 is connected to the controller via a sensor line. The controller is connected to the air heater 52 and the radiant heater 41 respectively. When the temperature of the rotor shaft 2 surface, the temperature of the dry hot air entering the rotor center hole 10, and the temperature of the air discharged from the conductive screw hole 11 exceed the required temperature, the temperature sensor 61 sends a sensing signal to the controller. The controller controls the air heater 52 and the radiant heater 41 to stop operating to prevent the rotor shaft 2 from overheating during the heating process, which could lead to deformation and insulation aging of the generator rotor shaft 2.

[0039] The present invention also provides a method for dehumidifying the center hole of a generator rotor, using the dehumidification device described above, the dehumidification method comprising:

[0040] S10. Remove the generator rotor 1 from the generator stator and place it on the support bracket. Remove the plugging screws on the main body plug plate 14 to expose the plugging screw holes 15. Remove the upward-facing conductive screw holes 3 of the rotor retaining ring 13 to expose the conductive screw holes 11.

[0041] S20. Control the heating unit 4 to heat the outer surface of the rotor shaft 2 to heat the rotor center hole 10 from the outside.

[0042] In a preferred embodiment, the temperature at which the heating unit 4 heats the outer surface of the rotor shaft 2 is controlled to not exceed 90°C. In a more preferred embodiment, the temperature at which the heating unit 4 heats the outer surface of the rotor shaft 2 is controlled to be between 85°C and 90°C.

[0043] S30. Control the ventilation unit 5 to introduce hot dry air from the plugging screw hole 15 into the rotor center hole 10, heat the rotor center hole 10 from the inside, and discharge the water vapor generated by heating in the rotor center hole 10 from the conductive screw hole 11.

[0044] In a preferred embodiment, the humidity of the hot dry air introduced into the rotor center hole 10 is not higher than 20%RH and the pressure is in the range of 0MPa to 0.6MPa. The temperature of the hot dry air introduced into the rotor center hole 10 is controlled to not exceed 75°C, and the temperature of the gas discharged from the conductive screw hole 11 is controlled to not be lower than 45°C.

[0045] In a preferred embodiment, after the rotor shaft 2 is heated to a predetermined time, it is rotated 180°, and different conductive screw holes 3 are removed to keep the exposed conductive screw holes 11 facing upwards. The two conductive screws on the rotor retaining ring side are arranged diagonally at 180°. Considering the existence of dead zones inside the rotor center hole, in order to completely remove moisture from the rotor center hole, after the rotor shaft 2 is heated, the rotor shaft is rotated 180° every 12 hours, and the upward-facing conductive screws are removed alternately to keep the air outlet facing upwards. During this period, the external radiant heater continues to work, and the ventilation unit continuously introduces hot dry air into the rotor center hole. Repeating the above steps for about 48 hours can complete the dehumidification of the rotor center hole.

[0046] Based on the above dehumidification method, the present invention can dehumidify the inside of the generator rotor center hole, and can dry and insulate the inside of the generator rotor center hole.

[0047] Example 1

[0048] This embodiment provides a method for dehumidifying the center hole of a generator rotor, the method being as follows:

[0049] (1) First, confirm that the unit is shut down and all primary equipment of the generator set has been switched to maintenance status. Pull the generator rotor out of the barrel and place it on a special bracket. The direction of the rotor can be adjusted according to the maintenance needs on the special bracket, and the rotor can be prevented from bending the shaft due to long-term placement.

[0050] (2) Confirm that the insulation inside the generator rotor center hole is damp.

[0051] Remove the positive and negative leads from the rotor retaining ring side of the generator and measure the insulation resistance of the windings at various parts of the rotor. The measurement results are as follows: rotor lead insulation to ground 4800 megohms, inner slip ring insulation to ground 50 megohms, outer slip ring insulation to ground 0.3 megohms, and insulation between the inner and outer slip rings 50 megohms. Based on the measurement results, it is confirmed that the insulation inside the generator rotor center hole is damp.

[0052] (3) Remove one conductive screw on the side of the positive (negative) lead wire near the retaining ring. Special tools must be used when removing the conductive screw. The sealing and insulating parts for the conductive screw must be prepared in advance. Use the hole after removing the conductive screw as an exhaust port. Remove the plugging screw in the center of the rotor body plug plate used for sealing test, leaving the plugging screw hole empty. Connect the sealing test flange to the outside of the center hole at the end of the generator rotor. The flange has a reserved interface for air intake.

[0053] (4) Air is filtered and dried by an air compressor and a refrigerated dryer to form instrument air (generally, power plants have their own air compressor stations). The clean instrument air is directly connected to the duct-type heater, electrically heated to 75°C, and then introduced into the rotor center hole through the external flange interface of the rotor end center hole. The gas flows through the gap between the conductive rod and the inside of the rotor center hole to the conductive screw on the retaining ring side. The gas after heat exchange treatment is discharged through the conductive screw hole after the retaining ring side is removed. According to the principle that water vapor rises, the generator rotor should be adjusted by a special bracket to make the air outlet on the retaining ring side face upward, while stabilizing the outlet temperature at 45°C. If necessary, the intake air flow rate should be adjusted.

[0054] (5) Use a radiant heater to continuously heat the rotor shaft surface corresponding to the center hole of the rotor. Simultaneously, add tin foil around the heated area, ensuring the tin foil coverage does not interfere with the periodic rotation of the rotor. The power of the radiant heater is determined based on the ambient temperature, controlling the rotor shaft surface temperature between 85℃ and 90℃.

[0055] (6) Since the two conductive screws on the retaining ring side are arranged diagonally at 180°, considering the dead zone inside the central hole, in order to completely remove the moisture inside the central hole, in practical applications, the rotor shaft is rotated 180° every 12 hours, and the upward-facing conductive screws are removed alternately to keep the air outlet facing upward. During this period, the external primary heating system and the internal hot air intake system need to work continuously. After repeating the above steps for about 48 hours of drying treatment, the insulation resistance of the rotor winding is measured again. The measurement results are as follows: rotor lead insulation to ground 4800 megohms, inner slip ring insulation to ground 4200 megohms, outer slip ring insulation to ground 4200 megohms, insulation between inner and outer slip rings 5000 megohms. Comparing the measurement results on the front and back sides, it is found that the insulation inside the rotor central hole has been significantly improved.

[0056] (7) To prevent moisture from being drawn in during the cooling and shrinking process after heat treatment, which could cause the insulation inside the central hole to become damp again, the air inlet temperature of the central hole was slowly reduced to maintain a slight positive pressure. When the outlet temperature approached the ambient temperature, the insulation and sealing materials of the removed conductive screws were replaced, and the conductive screws were reinstalled as a whole. After passing the airtightness test of the generator rotor central hole, the insulation resistance of each part was measured again and found to be consistent with that after treatment. At the same time, in accordance with the requirements of the preventive testing procedures for power equipment, DC resistance, AC withstand voltage, single voltage, RSO test, and rotor static and dynamic AC impedance tests were carried out on the generator rotor. All test data met the specifications.

[0057] In summary, the dehumidification device and method for the central hole of a generator rotor provided by this invention uses a heating unit to heat the outer surface of the rotor shaft, thereby heating the central hole from the outside and causing moisture in the central hole to evaporate into water vapor. Then, a ventilation unit introduces hot, dry air into the central hole, which, on the one hand, heats the central hole from the inside to continue evaporating moisture, and on the other hand, discharges the water vapor generated in the central hole through the conductive screw hole, thus achieving dehumidification of the central hole. Therefore, when the central hole of a generator rotor is damp, the dehumidification device and method provided by this invention can dry and insulate the interior of the central hole of the generator rotor without removing the conductive rod, avoiding the problems of long maintenance cycles and high costs associated with generator rotor equipment.

[0058] The above description is only a specific embodiment of this application. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of this application, and these improvements and modifications should also be considered within the scope of protection of this application.

Claims

1. A kind of dehumidification device for the center hole of generator rotor, the generator rotor (1) includes rotor shaft (2) and rotor center hole (10), the first end of the rotor shaft (2) is provided with body blanking plate (14), the second end of the rotor shaft (2) is provided with rotor guard ring (13), blanking screw hole (15) is provided on the body blanking plate (14), and the rotor guard ring (13) is provided with conductive screw hole (11);It is characterized by, The dehumidification device comprises: a heating unit (4) comprising a radiant heater (41) and a heat preservation assembly (42); the radiant heater (41) is arranged on the outer surface of the rotor shaft (2) and used for heating the outer surface of the rotor shaft (2) to heat the rotor center hole (10) from the outside, and the heat preservation assembly (42) is arranged outside the heater (41) and surrounds the periphery of the rotor shaft (2); an air supply unit (5) comprising an air source (51) and an air heater (52); the air heater (52) obtains instrument air from the air source (51), heats the instrument air to form hot dry air, and then supplies the hot dry air into the rotor center hole (10) from the plug screw hole (15) to heat the rotor center hole (10) from the inside, and discharges water vapor generated in the rotor center hole (10) from the conductive screw hole (11).

2. The dehumidifying device according to claim 1, wherein The air supply unit (5) further comprises a first air pipe (53), a second air pipe (54) and an air pressure sensor (55); the first air pipe (53) is connected between the air source (51) and the air heater (52), the second air pipe (54) is connected between the air heater (52) and the plug screw hole (15), and the air pressure sensor (55) is arranged on the first air pipe (53).

3. The dehumidification apparatus according to claim 2, wherein A flange is connected to the body plug plate (14), and the second air pipe (54) is connected to the plug screw hole (15) through the flange.

4. The dehumidifying device according to claim 1, wherein The power supply of the radiant heater (41) is AC220V, the output power of the radiant heater (41) is more than 30kW, and the temperature of the radiant heater (41) is adjustable between 0°C and 100°C.

5. The dehumidification device according to any one of claims 1 to 4, characterized in that, The dehumidification device further comprises a temperature monitoring unit (6) comprising a first temperature sensor (61), a second temperature sensor (62) and a third temperature sensor (63); the first temperature sensor (61) is arranged on the outer surface of the rotor shaft (2) and used for detecting the heating temperature of the outer surface of the rotor shaft (2); the second temperature sensor (62) is arranged at the inlet of the plug screw hole (15) and used for detecting the temperature of the hot dry air supplied into the rotor center hole (10); and the third temperature sensor (63) is arranged at the outlet of the conductive screw hole (11) and used for detecting the temperature of the gas discharged from the conductive screw hole (11).

6. A method of removing moisture from the center bore of a generator rotor, comprising: The dehumidification method comprises: S10, taking out the generator rotor (1) from the generator stator and placing it on a support bracket, disassembling the plug screw on the body plug plate (14) to expose the plug screw hole (15), and disassembling the conductive screw hole (11) of the rotor retainer ring (13) facing upwards to expose the conductive screw hole (11); S20, control the heating unit (4) to heat the outer surface of the rotor shaft (2) to heat the rotor center hole (10) from the outside; S30, control the ventilation unit (5) to introduce hot dry air from the plug screw hole (15) into the rotor center hole (10), heat the rotor center hole (10) from the inside, and discharge the water vapor generated by heating in the rotor center hole (10) from the conductive screw hole (11).

7. The method of removing moisture according to claim 6, wherein The temperature control of the heating unit (4) heating the outer surface of the rotor shaft (2) is not more than 90°C, the temperature control of the hot dry air introduced into the rotor center hole (10) is not more than 75°C, and the temperature control of the gas discharged from the conductive screw hole (11) is not less than 45°C.

8. The method of removing moisture according to claim 7, wherein The temperature control of the heating unit (4) heating the outer surface of the rotor shaft (2) is 85°C~90°C.

9. The method of removing moisture according to claim 7, wherein The humidity of the hot dry air introduced into the rotor center hole (10) is not higher than 20%RH, and the pressure is in the range of 0MPa~0.6MPa.

10. The method of dehumidification according to any one of claims 6-9, wherein, The rotor shaft (2) is turned over 180° after heating for a predetermined time, and the exposed conductive screw hole (11) is kept facing up by disassembling different conductive screw holes (11).

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