Full-stage automatic switching type central forced air supplement device for Francis turbine

Abstract

The application discloses a full-stage automatic switching type central forced air supplement device of a Francis turbine, which is characterized in that: a valve cover with a bearing set is connected to a supporting seat through a valve shaft and a spring, a valve port ring and a supporting pipe are fixed to an air supplement cavity; an air supplement volute with a square ring, a floating sealing ring, a vacuum degree sensor, a natural air supplement port, an air supplement port and a proximity switch is fixed to an air supplement chamber, the air supplement volute is communicated with a wind volume adjusting pipe and a fan volute through a wall pipe; the wind volume adjusting pipe is provided with a wind distribution plate, an arc plate, a vertical plate, a guide block and a guide column, the vertical plate is connected to an expansion rod, and a push-pull rod is arranged on a cover plate of the air supplement chamber; the fan volute is provided with a motor, a fan air inlet, an impeller and a fan support; a hydraulic cylinder is provided with a downward electromagnetic valve and an upward electromagnetic valve and is fixed to the cover plate, a piston rod is provided with a sealing cover, and the vacuum degree sensor, the proximity switch, the downward electromagnetic valve, the upward electromagnetic valve, the push-pull rod and the motor are connected to a control unit through a control cable and a signal power cable. The application can be widely applied to the air supplement field of Francis turbines.

Description

Technical fields:

[0001] This invention is an air replenishment device for automatically switching between natural and forced air replenishment at the center of a mixed-flow turbine. Background technology:

[0002] With the rapid development of wind and solar power, coupled with the decreasing water volume in various river basins, hydro-generator units sometimes fail to reach full load or operate at more than 50% load. Since hydro-generator units are generally designed to operate at a minimum load of 35-45% of their rated load, especially mixed-flow turbines which differ from propeller turbines (where the blade angle can be adjusted for lower loads), while mixed-flow turbines have fixed blades, and are designed to operate at more than 50% of their rated load, inherent vibrations arise in the design, manufacturing processes, and installation of the hydro-generator units. These inherent vibrations are consistent with the operating standards of hydro-generators. When the hydro-generator unit operates below 35-45% load, Karman vortex streets and hydraulic pulsations create a huge vacuum zone. This huge vacuum zone causes severe vibrations in the hydro-generator unit, resulting in significant damage, reduced service life, and increased maintenance frequency and workload. Current technology addresses the issue of the Karman vortex street and hydraulic pulsations that create a large vacuum zone at the center of the mixed-flow runner during ultra-low load hydro-generator units by injecting large amounts of compressed air into the top cover and tailrace cross. This method is not only energy-intensive, but neither of these forced methods can eliminate the severe vibrations generated by the hydro-generator unit during ultra-low load operation. If the problem of severe vibrations during ultra-low load operation is not completely eliminated, large and medium-sized hydro-generator units will be unable to meet the grid's ultra-low load power generation requirements, causing economic losses to hydropower plants. The grid will then allocate these power generation quotas to smaller hydro-generator units, whose ultra-low load power generation quotas are well within the normal load range for large and medium-sized units, and which do not experience severe vibrations. The power generation targets required by the power grid directly impact the economic benefits of hydropower plants. If large and medium-sized hydro-turbine generator units attempt to meet ultra-low load power generation targets without affecting the plant's economic returns, this ultra-low load power generation occurs within the generator units' severe vibration zones, causing significant damage, increased maintenance costs, reduced service life, and safety hazards. Conversely, avoiding ultra-low load operation to ensure safe operation and extend service life significantly reduces the hydropower plant's economic benefits. To eliminate the severe vibration caused by the large vacuum zone during ultra-low load operation, forced air injection at the center is the most effective method. However, because a natural air injection valve is installed on the turbine's central air injection chamber, current technology cannot solve the technical challenge of forcibly injecting a large amount of air into the large vacuum zone through the central air injection pipe. Furthermore, using compressed air for injection results in an extremely heavy workload for large air compressors, which are unsuitable for prolonged operation.When a hydro-generator unit operates at over 50% load, natural air replenishment is sufficient to supply air to the turbine via a natural air supply valve. However, when operating at extremely low loads, natural air replenishment is far from adequate to meet the large air requirements of the resulting vacuum zone. Therefore, a switch from natural air replenishment to forced air replenishment is necessary. Forced air replenishment injects a large amount of air into the vacuum zone to eliminate the severe vibrations generated by the turbine. Currently, the structure and installation method of the natural air supply valve used in hydro-generators cannot meet the requirements of forced air replenishment at the turbine's center. Furthermore, forced air replenishment must also maintain the turbine's operating efficiency; it cannot be used to reduce turbine efficiency. Large and medium-sized mixed-flow hydro-turbine generator units urgently need to solve the problem of severe vibrations during ultra-low load power generation. That is, to prevent severe vibrations from damaging the structure of the hydro-turbine generator unit due to meeting the grid requirements for ultra-low load power generation, and to eliminate the vacuum zone by forcibly replenishing air at the center of the turbine, so that the hydro-turbine generator unit can operate and generate electricity smoothly during ultra-low load power generation, thus ensuring the economic benefits of the hydropower plant. Summary of the Invention:

[0003] The technical solution provided by this invention fully meets the technical requirements of center natural air supply and forced air supply for mixed-flow turbines in the field, enabling the turbine generator set to operate and generate electricity smoothly under ultra-low load. It can not only meet the grid's requirements for the ultra-low load operation and power generation of large and medium-sized turbine generator sets, but also prevent the turbine generator set from generating severe vibrations, thus providing a technical guarantee for improving the economic benefits and social benefits of hydropower plants.This technical solution includes a gas supply chamber with a cover plate and a natural gas supply pipe, a mixing wheel fixed at the lower end of the gas supply chamber, and a central gas supply pipe directly connecting to the vacuum zone within the gas supply chamber. Its main technical features are: a gas supply chamber with a cover plate and a natural gas supply pipe, a mixing wheel fixed at the lower end of the gas supply chamber, a central gas supply pipe directly connecting to the vacuum zone within the gas supply chamber, a support pipe placed on the flange above the gas supply chamber via a flange with evenly distributed flange holes and flange bolt holes at its upper end, a support seat fixed to the center position of the lower end of the support pipe by four stiffeners (i.e., the support pipe is inside the gas supply chamber), a valve cover fixed to the upper end of the valve shaft via bolt holes and a bolt, a bearing seat mounted at the center position on the valve cover, and a thrust bearing, a top shaft with a shaft platform, and a deep groove bearing installed in the bearing seat. A bearing is fixed to the upper end of the bearing seat. After the cover and spring are fitted onto the valve shaft, the valve shaft passes through the guide hole on the support seat. A valve port ring with a valve port is fixed on the valve cover. The valve port ring and the flange at the upper end of the support pipe are fixed to the upper end of the air supply chamber with bolts through the flange hole and flange bolt hole. A rectangular ring with a rectangular groove is installed concentrically with the air supply port under the air supply volute. A floating sealing ring is installed in the rectangular groove. A vacuum sensor is fixed inside the air supply volute through the base, bracket and horizontal plate. The vacuum sensor is connected to the control unit through the control cable. The vacuum sensor monitoring threshold is set in the range of 0.001 to 0.01 MPa. The air supply volute with the air supply port at the bottom and the natural air supply port at the top is fixed concentrically with the valve port in the air supply chamber by 2 to 4 fixing arms. A proximity switch is fixed to the top with brackets and bolts. The proximity switch is connected to the control unit via a control cable. The air inlet of the air supply volute is connected to the wall-mounted pipe. The other end of the wall-mounted pipe is connected to the effective air supply outlet on the air volume regulating pipe with a splitter. The upper end of the vertical plate in the air volume regulating pipe is connected to the end of the telescopic rod of the push-pull rod via a connecting seat and a fixing pin. The lower end of the back of the vertical plate is slidably connected to two guide blocks and two guide posts. The two guide posts are fixed inside the air volume regulating pipe. An air distribution plate and an arc plate are fixed to the front of the vertical plate. The push-pull rod is fixed to the air supply chamber with brackets and bolts. The push-pull rod is connected to the control unit via a control cable. The air distribution plate moves up and down in the radial H direction of the impeller, that is, the air distribution plate adjusts the air volume radially with the impeller. The motor... The control cable connects to the control unit. An impeller is located inside the fan casing. Below the fan casing are the fan inlet and fan support. The other end of the airflow regulating pipe connects to the fan outlet. The piston rod passes through the center hole of a cover plate with a flange hole, fixing the hydraulic cylinder to the cover plate. The downward solenoid valve connects to the hydraulic cylinder via an oil pipe and is connected to the control unit via a control cable. The upward solenoid valve connects to the hydraulic cylinder via an oil pipe and is connected to the control unit via a control cable. A sealing cover with a fixing sleeve is fixed to the piston rod using a fixing pin. The distance from the end of the piston rod to the sealing cover is L+A, which is the distance from the sealing cover to the natural air supply port. The cover plate is bolted to the air supply chamber through the flange hole. A signal power cable is connected to the control unit.

[0004] The threshold of the vacuum sensor monitoring the vacuum level at the air inlet is set within the range of 0.001 to 0.01 MPa. Under the condition of ensuring a reasonable vacuum level for the mixed-flow turbine, a large amount of air Q2 is forcibly injected into the mixed-flow runner through the air inlet casing, air inlet chamber, and central air inlet pipe to form a huge vacuum zone. Q2 is the effective forced air injection volume. This air injection volume Q2 meets the monitoring threshold of the vacuum sensor at the air inlet and the working efficiency of the turbine. If Q2 does not meet the monitoring threshold of the vacuum sensor, the control unit adjusts the air volume of Q2 through push-pull rods and vertical plates, arc plates, air distribution plates, and air distribution ports. The excess air volume Q1 is discharged from the air distribution port to ensure that the working efficiency of the mixed-flow turbine is not reduced due to forced air injection. The air supply chamber and its sleeves are fixed, while the air supply cavity and its sleeves are rotating. To prevent the piston rod from rotating with the valve cover during its downward movement to open the valve cover to its maximum stroke, an anti-rotation sleeve consisting of a bearing housing, a thrust bearing, a top shaft with a shaft platform, a deep groove bearing, and a bearing cover with a through hole is installed at the center of the valve cover. The floating sealing ring can float up and down in the rectangular groove of the rectangular ring for sealing. The valve shaft can slide in the guide hole of the support seat. A proximity switch monitors whether the sealing cover is covering the natural air supply port. After the sealing cover is covering the natural air supply port, the control unit starts the motor, which drives the impeller to inject Q2 air volume into the huge vacuum area through the fan casing. The air distribution plate and the arc plate adjust the air volume Q2 radially to ensure that the air velocity remains constant regardless of changes in the Q2 air volume, further meeting the technical requirements of rapid air supply for mixed-flow turbines under ultra-low load conditions. The air-injection volute introduces horizontally supplied air (Q2) into a large vacuum zone through a turbulent flow, passing vertically through the valve port, air-injection chamber, and central air-injection pipe. This efficiently changes the flow direction of the high-speed air intake from horizontal to vertical. When the mixed-flow turbine generator is not in the ultra-low load power generation stage, the piston rod moves upward with the sealing cover, switching to the natural air-injection stage. Atmospheric air is drawn in by the turbine's vacuum-generated stroke, which opens the valve cover, and the generator stops working.

[0005] The technical effect achieved by the technical solution provided by this invention is as follows: When the mixed-flow turbine generator set is operating at 50-100% load, it is in the natural air replenishment stage. At this time, the air supplied by the natural air replenishment pipe replenishes the vacuum zone through the natural air replenishment port, air replenishment port, valve port, air replenishment chamber, and central air replenishment pipe on the air replenishment volute. Under the action of the vacuum degree in the vacuum zone, the valve cover compression spring moves downward, and the air is replenished from the ring formed by the valve port and the valve cover into the mixed-flow runner to form a smaller vacuum zone, reducing turbine vibration and cavitation. The vacuum degree at which the valve cover is sucked open during the natural air replenishment stage is designed and manufactured within the range of 0.001-0.01 MPa. The maximum stroke L of the valve cover is calculated and determined according to technical requirements. The valve cover opening stroke is determined by the vacuum degree of the vacuum zone and the spring parameters. This stage is the natural air replenishment stage of the mixed-flow turbine generator set. When the mixed-flow turbine generator set operates at a load 35-45% below its rated load, it is considered to be operating at ultra-low load. During ultra-low load operation, the unit will experience severe vibrations due to a large vacuum zone. This severe vibration is mainly caused by the large vacuum zone generated by the mixed-flow runner. Natural air replenishment alone is insufficient to eliminate this vacuum zone; a large amount of air must be forcibly injected into the vacuum zone through the central air replenishment pipe to effectively eliminate the severe vibration. This stage is called the forced air replenishment stage. When the mixed-flow turbine generator set enters ultra-low load operation, the control unit opens the downward and upward solenoid valves, injecting high-pressure oil into the hydraulic cylinder through the downward solenoid valve. The piston rod, carrying the sealing cover, moves downward. When the front end of the piston rod presses against the upper end of the top shaft, the top shaft does not rotate, while the deep groove bearing outer sleeve and the thrust bearing lower sleeve rotate, and the top shaft and piston rod remain relatively stationary. At this point, the piston rod continues to move downwards, opening the valve cover to its maximum stroke L. The sealing cover seals the natural air supply port. The proximity switch detects that the sealing cover is in place and sends a signal to the control unit. The control unit closes the downward and upward solenoid valves, and the natural air supply port is sealed. The control unit then starts the motor with the impeller, supplying effective air volume Q2 into the huge vacuum zone through the fan casing and the air volume adjustment pipe. The effective air volume Q2 is supplied into the huge vacuum zone through the air supply port, valve port, air supply chamber, and central pipe. The impeller draws air Q into the fan inlet, and the air distribution plate, arc plate, and air distribution port in the air volume adjustment pipe divide Q into two parts, Q1 and Q2. Q2 is the effective air volume supplied to the vacuum zone. Air volume Q1 is discharged through the air distribution port, and air volume Q2 is controlled by the push-pull rod through the vertical plate, air distribution plate, and arc plate. In this way, the effective air volume can be adjusted while the wind speed remains constant, allowing the supplied air volume to quickly reach the huge vacuum zone. The Q2 air volume is adjusted according to the monitoring threshold set by the vacuum sensor to ensure the working efficiency of the mixed flow turbine. The monitoring threshold set by the vacuum sensor is in the range of 0.001 to 0.01 MPa. The vacuum sensor is connected to the control unit through a control cable. The control unit controls the Q2 air volume by controlling the push-pull rod, which is a servo push-pull rod.If the current vacuum level is lower than the monitoring threshold set by the vacuum sensor, the control unit controls the push-pull rod to move downwards, reducing the airflow of Q2 until the current vacuum level equals the monitoring threshold. Conversely, if the current vacuum level is higher than the monitoring threshold set by the vacuum sensor, the control unit controls the push-pull rod to lift the air distribution plate, increasing the airflow of Q2 until the current vacuum level equals the monitoring threshold. When the unit resumes operating at 50-100% load, the control unit opens the upward and downward solenoid valves, and high-pressure oil is injected into the hydraulic cylinder through the upward solenoid valve. At this time, the piston rod, along with the sealing cover, rises to its original position. Simultaneously, the control unit stops the motor, thus stopping the forced air replenishment stage, and the unit returns to the natural air replenishment stage. The rectangular ring and floating sealing ring improve the sealing performance at the dynamic and static seals, ensuring that the effective airflow Q2 is fully replenished into the vacuum zone. The air replenishment volute effectively changes the horizontally high-speed air replenishment into a vertical direction, replenishing the large vacuum zone. The signal power cable provides the control unit with command signals and power. This technical solution fundamentally solves the technical problem of strong vibration generated by mixed-flow turbine generator sets during ultra-low load power generation.

[0006] The technical solution provided by this invention has an ingenious and concise structure, perfectly solving the problem of automatic switching center forced air replenishment technology in mixed-flow turbine generator sets throughout all stages. It completely eliminates the problem of vibration caused by low loads, reduces unit maintenance costs and workload, and significantly improves the economic and social benefits of hydropower plants. Compared with existing technologies, this technical solution is novel, inventive, and practical, and will be widely used in the field of hydropower generation. Attached image description:

[0007] Figure 1 Main view of the automatic switching center forced air supply device for the mixed-flow turbine.

[0008] Figure 2 AA view of the fully automatic switching center forced air supply device for mixed-flow turbine.

[0009] Figure 3 BB view of the fully automatic switching center forced air supply device for mixed-flow turbine.

[0010] Figure 4 CC view of the fully automatic switching center forced air supply device for the mixed-flow turbine.

[0011] Figure 5 Enlarged view of the fully automatic switching center forced air supply device for the mixed-flow turbine.

[0012] Figure 6 Enlarged view of the automatic switching center forced air supply device II for the mixed-flow turbine.

[0013] in:

[0014] 1. Hydraulic cylinder; 2. Oil pipe; 3. Downward solenoid valve

[0015] 4. Control cable 5. Upward solenoid valve 6. Control unit

[0016] 7. Bracket 8. Push-pull rod 9. Signal power cable

[0017] 10. Telescopic pole; 11. Fixing pin; 12. Connecting seat

[0018] 13. Vertical panel; 14. Curved panel; 15. Air vent.

[0019] 16. Air distribution plate; 17. Motor; 18. Fan casing

[0020] 19. Impeller; 20. Fan bracket; 21. Fan inlet

[0021] 22. Air outlet flange; 23. Air volume regulating pipe; 24. Guide column

[0022] 25. Guide block; 26. Air inlet; 27. Rectangular ring

[0023] 28. Rectangular annular groove; 29. ​​Flange hole; 30. Valve port ring.

[0024] 31. Bearing housing; 32. Air supply chamber; 33. Support tube

[0025] 34. Rib plate; 35. Support seat; 36. Valve shaft

[0026] 37. Central air supply pipe; 38. Mixed flow impeller; 39. Vacuum zone

[0027] 40. Guide hole; 41. Spring; 42. Screw

[0028] 43. Screw hole; 44. Valve cover; 45. Top shaft

[0029] 46. ​​Valve port; 47. Flange bolt hole; 48. Flange

[0030] 49. Floating sealing ring; 50. Bearing cover; 51. Vacuum sensor

[0031] 52. Horizontal plate 53. Bracket 54. Base

[0032] 55. Air supply chamber 56. Natural air supply pipe 57. Bolt

[0033] 58. Cover plate; 59. Sealing cover; 60. Hydraulic cylinder flange

[0034] 61. Through hole; 62. Fixing sleeve; 63. Cotter pin

[0035] 64. Piston rod; 65. Through-wall tube; 66. Proximity switch

[0036] 67. Natural air inlet 68. Air inlet housing 69. Fixing base

[0037] 70. Fixed arm; 71. Volute air inlet; 72. Effective make-up air outlet.

[0038] 73. Fan outlet 74. Air volume adjustment inlet 75. Deep groove bearing

[0039] 76. Thrust bearing 77. Shaft base Detailed implementation method:

[0040] The upper end of the support tube 33 has a flange 48 with staggered and evenly distributed flange holes 29 and flange bolt holes 47. The lower end of the support tube 33 is fixed with a support seat 35 with guide holes 40 at the center position by four stiffeners 34. The valve cover 44 is fixed to the upper end of the valve shaft 36 by bolt holes 43 and screws 42. The bearing seat 31 with flange 48 at the upper end is fixed to the center position of the valve cover 44 by bolts 57 through flange 48 and flange holes 29. The thrust bearing 76, the top shaft 45 with shaft platform 76 and the deep groove bearing 75 are installed in the bearing seat 31 in sequence. The bearing cover 50 with through hole 61 is fixed to the upper end of the bearing seat 31 by bolts 57 through flange holes 29. The upper end of the top shaft 45 is 5-10 mm higher than the upper surface of the bearing cover 50. The valve shaft 36 is inserted through the spring 41 into the guide hole 40 on the support seat 35. After the valve port ring 30 with the valve port 46 is put on the valve cover 44, the valve port ring 30 is first fixed to the flange 48 of the support tube 33 with bolts 57 through the flange bolt hole 47. Then, the valve port ring 30 and the support tube 33 are fixed to the gas supply chamber 32 with bolts 57 through the flange hole 29. The gas supply chamber 32 has a central gas supply pipe 37. The lower end of the gas supply chamber 32 is fixed with a mixing wheel 38. Below the mixing wheel 38 is the vacuum zone 39.

[0041] The gas replenishment chamber 55 has a natural gas replenishment pipe 56, a wall-passing pipe 65, and a cover plate 58. A vacuum sensor 51 is fixed in the gas replenishment volute 68 via a base 54, a bracket 53, and a horizontal plate 52. The vacuum sensor 51 is connected to the control unit 6 via a control cable 4. A rectangular ring 27 with a rectangular annular groove 28 is fixed around the gas replenishment port 26 of the gas replenishment volute 68, and a floating sealing ring 49 is installed in the rectangular annular groove 28. The gas replenishment volute 68, with a natural gas replenishment port 67 on top and a gas replenishment port 26 on the bottom, is fixed inside the gas replenishment chamber 55 using bolts 57 via 3-4 sets of bases 54, fixing arms 70, and fixing seats 69, ensuring that the gas replenishment port 26 is concentric with the valve port 46. A proximity switch 66 is fixed to the gas replenishment volute 68 near the natural gas replenishment port 67 via a bracket 7. The proximity switch 66 is connected to the control unit 6 via a control cable 4. The inlet 71 of the air intake volute 68 is connected to one end of the wall-mounted pipe 65 via the air outlet flange 22 and bolts 57. The other end of the wall-mounted pipe 65 is connected to the airflow adjustment pipe 23 with the air distribution port 15. Two guide blocks 25 are respectively fitted onto two guide posts 24 with screw holes 43 at the ends through guide holes 40. The two guide blocks 25 are fixed to the back of the vertical plate 13. The two guide posts 24 are fixed to the upper and lower surfaces inside the airflow adjustment pipe 23 with bolts 59 through the screw holes 43 at both ends. An air distribution plate 16 is fixed below the vertical plate 13. An arc plate 14 is fixed between the vertical plate 13 and the air distribution plate 16. The vertical plate 13 is fixed to the front end of the telescopic rod 10 of the push-pull rod 8 via the connecting seat 12, fixing pin 11 and cotter pin 63 fixed at the upper end. The push-pull rod 8 is fixed to the air intake chamber 55 via the bracket 7 and bolts 57. The push-pull rod 8 is connected to the control unit 6 via the control cable 4. The other end of the air volume regulating pipe 23 is connected to the fan outlet 73 of the fan casing 18. The fan casing 18, which includes the fan inlet 21, motor 17, and impeller 19, is fixed to the fan bracket 20. After the piston rod 64 passes through the through hole 61 on the cover plate 58, the hydraulic cylinder 1 is fixed to the cover plate 58 with bolts 57 through the hydraulic cylinder flange 60. The downward solenoid valve 3 is connected to the hydraulic cylinder 1 through the oil pipe 2, and the upward solenoid valve 5 is connected to the hydraulic cylinder 1 through the oil pipe 2. The downward solenoid valve 3 and the upward solenoid valve 5 are connected to the control unit 6 through the control cable 4. The control unit 6 is connected to the signal power cable 9. A sealing cap 59 with a fixing sleeve 62 is fitted onto the piston rod 64 through a guide hole 40. The distance between the sealing cap 59 and the top shaft 45 is L+A. A fixing pin 11 is used to fix the sealing cap 59 to the piston rod through the fixing sleeve 62 and the guide hole 40 on the piston rod 64. Cotter pins 63 are installed at both ends of the fixing pin 11. A bolt 57 is used to fix the cover plate 58 to the air supply chamber 55 through the flange hole 29. The process is complete.

Claims

1. A fully automatic switching center-forced air supply device for a mixed-flow turbine, comprising an air supply chamber with a cover plate and a natural air supply pipe, a mixed-flow impeller fixed at the lower end of the air supply chamber, and a center air supply pipe connected directly to a vacuum zone within the air supply chamber, characterized in that... The supporting pipe is placed on the flange on the upper surface of the air supplementing cavity through the flange with uniformly distributed flange holes and flange screw holes, the supporting seat is fixed on the center position of the lower end of the supporting pipe through four rib plates, that is, the supporting pipe is inside the air supplementing cavity, the valve shaft is fixed with a valve cover through a screw hole and a screw rod on the upper end, a bearing seat is installed on the center position of the upper surface of the valve cover, a thrust bearing, a top shaft with a shaft table and a deep groove bearing are installed in the bearing seat, a bearing cover is fixed on the upper end of the bearing seat, the spring is sleeved on the valve shaft, then the valve shaft passes through the guide hole on the supporting seat, a valve port ring with a valve port is fixed on the upper surface of the valve cover, the valve port ring and the flange on the upper end of the supporting pipe are fixed on the upper end of the air supplementing cavity through the flange holes and the flange screw holes and bolts; a rectangular ring with a rectangular ring groove is installed on the lower surface of the air supplementing volute at the concentric position with the air supplementing port, a floating sealing ring is installed in the rectangular ring groove, a vacuum degree sensor is fixed inside the air supplementing volute through a base, a support and a horizontal plate, the vacuum degree sensor is communicated with a control unit through a control cable, the monitoring threshold of the vacuum degree sensor is set in the range of 0.001-0.01 Mpa, the air supplementing volute with the air supplementing port on the lower surface and the natural air supplementing port on the upper surface is fixed in the air supplementing chamber concentrically with the valve port through 2-4 fixing arms, a proximity switch is fixed on the upper surface of the air supplementing volute through a support and bolts, the proximity switch is communicated with the control unit through a control cable, the air inlet of the air supplementing volute is communicated with the through-wall pipe, the other end of the through-wall pipe is communicated with the effective air supplementing outlet of the air volume adjusting pipe with a branch port, the upper end of the vertical plate in the air volume adjusting pipe is connected with the telescopic rod end of the push-pull rod through a connecting seat and a fixing pin, the back lower end of the vertical plate is slidably connected with two guide columns through two guide blocks, the two guide columns are fixed inside the air volume adjusting pipe, the front of the vertical plate is fixed with a branch plate and an arc plate, the push-pull rod is fixed on the upper surface of the air supplementing chamber through a support and bolts, the push-pull rod and the control unit are communicated through a control cable, the branch plate moves up and down in the axial direction of the impeller, the motor is communicated with the control unit through a control cable, the fan volute has an impeller, the lower surface of the fan volute has a fan air inlet and a fan support, the other end of the air volume adjusting pipe is communicated with the fan air outlet; the hydraulic cylinder is fixed on the cover plate through the center through hole of the cover plate with a flange hole, the downward electromagnetic valve is communicated with the hydraulic cylinder through an oil pipe, the downward electromagnetic valve is connected with the control unit through a control cable, the upward electromagnetic valve is communicated with the hydraulic cylinder through an oil pipe, the upward electromagnetic valve is connected with the control unit through a control cable, the sealing cover with a fixing sleeve is fixed on the piston rod through a fixing pin, the distance between the end of the piston rod and the sealing cover is L+A, that is, the distance between the sealing cover and the natural air supplementing port is L+A, the cover plate is fixed on the upper surface of the air supplementing chamber through a flange hole and bolts, the control unit is connected with a signal power cable.

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