Center air supply device for automatically adjusting stroke of conical valve disc by magnetic push type main and standby electric cylinders

Abstract

The utility model discloses a magnetic push type center air supply device for automatically adjusting the stroke of a conical valve disc through a main electric cylinder and a standby electric cylinder, the main electric cylinder is fixed on a guide cylinder bottom plate through a guide piston, a telescopic rod and the standby electric cylinder, and then the guide cylinder bottom plate and a guide cylinder are fixed below an air supply cover plate; a push magnet is arranged at the end of a telescopic rod of the main electric cylinder, the conical valve disc is provided with a valve disc magnet, and the push magnet and the N pole of the valve disc magnet are opposite and cannot make contact. Guide sleeves with guide holes are respectively welded on three rib plates at the lower end of the valve cylinder; three guide valve shafts are fixed below the conical valve disc, springs are sleeved on the guide valve shafts respectively and then penetrate through guide holes, and the conical valve disc is installed at the upper end of the rotary air supply pipe through a flange on a valve cylinder and a valve seat with a conical valve port. The main electric cylinder is connected with the control server through a control cable with a cable spiral joint, the standby electric cylinder is connected with the control server through a control cable, and the air supplementing cover plate is fixed to the air supplementing cover. The technical scheme can be widely applied to the field of mixed-flow water turbine center air supply.

Description

Technical fields:

[0001] This invention is a central air supply device for automatically adjusting the stroke of the conical valve disc within the full load range of a mixed-flow turbine. Background technology:

[0002] With the continuous grid connection of new energy power generation equipment, the power grid requires mixed-flow turbine generator sets to operate within an increasingly wider load range. These generator sets frequently operate from full load to 50% of full load, and sometimes even below 40% of full load. The lower the generator load of a large mixed-flow turbine, the larger and higher the harmful vacuum zone at the center of the turbine. This harmful vacuum zone causes abnormal vibrations in the turbine, resonating with the inherent vibrations of the turbine-generator set. This can lead to severe cracks at the runner's outlet and exacerbate blade cavitation, even damaging the moving parts and the overall structure of the generator set. If a mixed-flow turbine-generator set cannot operate at full load or must operate at low load, the best technical measure to eliminate the harmful vacuum zone is to introduce air into the vacuum zone through an air supply pipe that rotates synchronously with the shaft. This reduces the harmful vacuum zone and significantly improves the turbine's operating environment. Mixed-flow turbine generator sets require different air supply vacuum levels depending on the load. This is because the lower the operating load of the mixed-flow turbine generator set, the greater the amount of air required for air supply; the load, air supply volume, and vacuum level are negatively correlated. However, current technical solutions have the following drawbacks:

[0003] 1. The vacuum created by the turbine opens the valve disc of the air supply device. During the opening process, the valve disc must overcome the spring force. This type of air supply device does not effectively prevent air from entering the vacuum zone of the turbine. The larger the working stroke of the air supply valve disc, the larger the vacuum zone formed in the center of the turbine and the higher the vacuum degree. It is a passive working method that relies on the vacuum degree to open the valve disc. It cannot automatically adjust the stroke of the air supply device to smoothly supply and eliminate the air in the turbine vacuum zone when the mixed-flow turbine is running.

[0004] 2. Some existing technologies use springs to control the vacuum level. This type of air supply device will cause pulsation in the air supply to the turbine, making the turbine's working state unstable. This type of spring-controlled air supply device not only exerts a great impact force on the entire air supply device when the valve disc is closed, often causing damage to the buffer, but the spring is also very easy to break. In both cases, the valve disc often cannot close properly, which increases the risk of flooding the unit.

[0005] With the increasing range of power generation loads for mixed-flow turbine generator units and the more frequent occurrence of low-load operation, existing technologies cannot perfectly meet the technical requirements for eliminating vacuum zones under low-load conditions. Power plants with giant mixed-flow turbine generator units urgently need a creative solution to better meet the needs of central air injection during low-load operation of mixed-flow turbines, eliminate resonance caused by harmful vacuum zones under low loads, and reduce turbine runner cracks and cavitation. Summary of the Invention:

[0006] This invention proposes a technical solution to address the technical problems in this field. The system includes an air supply cover and air supply pipes on the air supply hood, a rotating air supply pipe with a flange, and is characterized by: a spare electric cylinder fixed below the bottom plate of the guide cylinder; a guide piston fixed to the end of a 2L-length telescopic rod on the spare electric cylinder; the main electric cylinder fixed inside the guide piston via a fixing plate; the travel of the telescopic rod on the spare electric cylinder being greater than or equal to 2L; the travel of the telescopic rod on the main electric cylinder being L, where the value of a is not zero; a magnet fixing plate fixed to the lower end of the telescopic rod of the main electric cylinder; and a thrust magnet fixed below the magnet fixing plate using a magnet guard. A control cable with a cable spiral joint is used to connect the main electric cylinder to the control server through the cable holes on the guide piston, guide cylinder, and air supply hood; and a control cable is used to connect the spare electric cylinder to the control server through the cable holes on the guide cylinder and air supply hood. Together; fix the guide tube base plate and guide tube to the center position under the air supply cover plate; fix the valve disc magnet to the center position on the conical valve disc through the magnetic cover; align the N pole of the pushing magnet with the N pole of the valve disc magnet to generate a repulsive force; fix three guide valve shafts at 120 degrees under the conical valve disc, with the axis of the three guide valve shafts having the same diameter as the center of the conical valve disc; weld the front ends of the equally long stiffeners together at 120 degrees, and weld the rear ends of the stiffeners to the inner wall of the valve cylinder; weld a guide sleeve to the side of each stiffener, with the guide hole on each guide sleeve concentric with the guide valve shaft; fit three springs onto the three guide valve shafts under the conical valve disc, and then pass the three guide valve shafts through the guide holes so that the conical valve disc is located at the upper end of the valve cylinder; fix the conical valve disc to the flange of the rotating air supply pipe through the valve seat with the conical valve port and the valve cylinder; the conical valve disc is concentric with the pushing magnet; fix the air supply cover plate to the air supply cover. The telescopic rod, thrust magnet, and valve disc magnet are parallel to each other and concentric. The driving magnet, main electric cylinder, standby electric cylinder, guide piston, guide cylinder, and air supply cover are all stationary; while the valve cylinder, valve seat, and conical valve disc rotate together with the rotating air supply pipe. Therefore, the concentricity of the valve disc magnet and the driving magnet should be well maintained, and according to the principle of like poles repelling each other, the driving magnet on the telescopic rod of the main electric cylinder will generate sufficient repulsive force when driving the valve disc magnet to drive the conical valve disc to work. During the working stroke L of the conical valve disc, the distance between the valve disc magnet and the driving magnet always maintains a certain distance 'a', which decreases as the working stroke L increases, but always remains in a non-contact state. The guide piston can slide freely in the guide cylinder without gaps. Decomposing one spring into three springs in the existing technology has the following technical effects: when one spring breaks, two springs still close the valve disc, eliminating the risk of flooding the unit; when the cable spiral joint moves up and down on the telescopic rod of the standby electric cylinder, it can provide the control cable extension length for the main electric cylinder to move up and down with the guide piston, preventing the main electric cylinder control cable from being pulled off and stuck on the guide piston.The control server controls the operating status of the main electric cylinder and the standby electric cylinder based on the signals from the input signal cable. The control server constantly checks for malfunctions in the main electric cylinder and determines the position of the telescopic rod on the main electric cylinder in case of a malfunction, so as to adjust the operating position of the telescopic rod on the standby electric cylinder accordingly. The telescopic rod on the standby electric cylinder extends by a stroke L at its initial operating position. The working stroke, opening and closing speed of the conical valve disc are all controlled by the telescopic rods on the main and standby electric cylinders, and are controlled by the control server. When the telescopic rod retracts, the closing force of the conical valve disc is provided by three springs beneath it.

[0007] The technical effect achieved by the technical solution provided by this invention is as follows: When the backup electric cylinder receives a working signal from the control server, the backup electric cylinder extends its telescopic rod by half of its total stroke, L. The stroke of the telescopic rod of the backup electric cylinder is greater than or equal to 2L; the stroke of the telescopic rod on the main electric cylinder is L. The telescopic rod on the backup electric cylinder stops after extending half of its total stroke, L. The telescopic rod of the backup electric cylinder pushes the guide piston with the main electric cylinder downwards by a stroke L. The telescopic rod on the main electric cylinder with stroke L is in a fully retracted state. At this time, the distance 'a' between the pushing magnet and the valve disc magnet is at its maximum, and the conical valve disc is in a closed state. The stroke L takes into account the change in the value of 'a'. The longer the stroke L, the greater the repulsive force generated between the pushing magnet and the valve disc magnet, and the smaller the value of 'a'. The pushing magnet and the valve disc magnet generate a certain repulsive force. This repulsive force exerts a certain pressure on the three springs. This pressure is insufficient to overcome the elastic force of the three springs to move the valve disc, i.e., the device is in a closed state. When the control server receives a signal indicating a harmful vacuum zone in the turbine, it activates the main electric cylinder. The main electric cylinder drives the telescopic rod outwards, with a maximum extension stroke of L. During this outward extension, the distance 'a' between the pushing magnet and the valve disc magnet continuously decreases, increasing the repulsive force between them and pushing the conical valve disc downwards. When the repulsive force balances the elastic force of the three springs beneath the conical disc, the valve disc comes to a standstill, and the telescopic rod stops working. At this point, the conical valve disc's stroke satisfies the turbine's air supply stroke, preventing resonance and efficiency loss. Even when the main electric cylinder's telescopic rod reaches stroke L, the value 'a' will not be zero, meaning the pushing magnet and the valve disc magnet will not come into contact. This is because the pushing magnet is fixed, while the valve disc magnet rotates; the valve disc's stroke is determined by the control server's instructions. By employing the repulsive feature of two magnets with the same poles, the technical problem of using fixed main and backup electric cylinders to push open the rotating conical valve disc is solved. This allows a large amount of air to enter the harmful vacuum zone of the turbine through the flow ring formed by the stroke between the conical valve disc and the conical valve orifice, and the rotating air supply pipe. This eliminates the harmful vacuum zone, improves the turbine's operating environment, and prevents resonance that could lead to cracks. Using the main electric cylinder to open the conical valve disc via a telescopic rod is an active opening method. Active opening provides very stable air supply without fluctuations, unlike existing technologies that require the turbine to increase its vacuum level to open the valve disc, which is a passive opening method. Passive opening leads to unstable air supply with significant fluctuations. When the control server receives a signal that air supply is not needed, it controls the main electric cylinder to retract the telescopic rod. This pushes the magnet upwards with the telescopic rod, increasing the distance between the magnet and the valve disc magnet, reducing the repulsive force. The conical valve disc, under the elastic force of three springs, also moves upwards until it closes, thus completing one air supply cycle.

[0008] When the control server detects a malfunction in the main electric cylinder, it activates the backup electric cylinder. The backup electric cylinder operates as follows:

[0009] 1. When the main electric cylinder malfunctions while the telescopic rod is fully retracted, the standby electric cylinder will operate using the portion of the telescopic rod that is not extended. The stroke of the unextended portion of the telescopic rod of the standby electric cylinder is equal to L, which fully meets the control requirements for the opening and replenishment stroke of the conical valve disc.

[0010] 2. If the main electric cylinder malfunctions while its telescopic rod is fully extended (i.e., when the telescopic rod is extended by L), the backup electric cylinder must retract the extended portion of the telescopic rod L completely into the backup electric cylinder. This allows the conical valve disc to return to the closed position. Then, the telescopic rod on the backup electric cylinder controls the distance between the pushing magnet and the valve disc magnet by moving the guide piston and the main electric cylinder up and down. This ensures that even if a malfunction occurs after the main electric cylinder's telescopic rod is fully extended, the control server can control the conical valve disc's air replenishment stroke via the telescopic rod stroke on the backup electric cylinder. The backup electric cylinder fully meets the control requirements for both the opening and closing of the conical valve disc's air replenishment stroke.

[0011] 3. When the main electric cylinder malfunctions while the telescopic rod is extended to a certain length L1, the backup electric cylinder must retract the extended telescopic rod to the backup electric cylinder length L1 so that the conical valve disc can return to the closed state. The control server then controls the telescopic rod on the backup electric cylinder to control the up and down movement of the guide piston and the main electric cylinder, thereby controlling the distance between the push magnet and the valve disc magnet. This fulfills the requirement that the backup electric cylinder controls the stroke of the conical valve disc's air replenishment operation when the main electric cylinder malfunctions.

[0012] The use of main and backup electric cylinders ensures the safe operation of this device. The structure employs a push magnet and valve disc magnet, ensuring that even if the valve disc is not concentric with the main and backup electric cylinders, it will not affect their service life. This device has excellent anti-lifting performance. The push magnet and valve disc magnet are made of neodymium iron boron material, the conical valve disc, valve seat, and guide cylinder are made of 304 stainless steel, the guide piston is made of tin bronze, and the magnet protective cover is made of magnetically conductive material. The input signal cable provides the control server with generator set efficiency signals, resonance vibration signals, and vacuum level signals in the vacuum zone. This specification only discloses one technical solution of the invention. Other technical solutions obtained by those skilled in the art without inventive effort based on the disclosure of this invention are all within the scope of protection of this invention.

[0013] The technical solution disclosed in this invention perfectly solves the technical problem that the existing central air supply device for mixed-flow turbines cannot meet the operating requirements of the hydroelectric generator. Existing solutions suffer from problems such as easily broken springs, easily damaged dampers, and large airflow fluctuations during air supply, including unstable air in the vacuum zone. The solution of this invention is compact, ingenious, reliable, and stable, and compared with existing technologies, it possesses novelty, inventiveness, and practicality. The technical solution disclosed in this invention will be widely applied in the field of central air supply for mixed-flow turbines. Attached image description:

[0014] Figure 1 Main view of the magnetic push-type main and backup electric cylinder automatic adjustment conical valve disc stroke center air replenishment device.

[0015] Figure 2 Magnetic push-type main and backup electric cylinder automatic adjustment conical valve disc stroke center air replenishment device AA view

[0016] in:

[0017] 1. Guide valve shaft 2. Guide sleeve 3. Spring

[0018] 4. Valve cylinder; 5. Screw hole; 6. Flange

[0019] 7. Fixing hole; 8. Bolt; 9. Valve seat

[0020] 10. Conical valve disc; 11. Valve disc magnet; 12. Push magnet

[0021] 13. Countersunk bolts 14. Main electric cylinder 15. Guide piston

[0022] 16. Fixed plate; 17. Telescopic pole; 18. Air supply cover

[0023] 19. Air inlet cover plate; 20. Guide cylinder bottom plate; 21. Spare electric cylinder

[0024] 22. Electric cylinder seat; 23. Countersunk hole; 24. Cable guide hole

[0025] 25. Control cable 26. Control server 27. Input signal cable

[0026] 28. Power cord 29. Guide cylinder 30. Cable spiral joint

[0027] 31. Air supply pipe; 32. Magnetic fixing plate; 33. Magnetic protective cover.

[0028] 34. Conical valve port; 35. Shaft seat; 36. Rib plate

[0029] 37. Rotary air supply pipe; 38. Guide hole Detailed implementation method:

[0030] Using countersunk bolts 13, through the countersunk hole 23 on the guide cylinder base plate 20 and the electric cylinder seat 22, fix the spare electric cylinder 21 with the telescopic rod 17 to the bottom of the guide cylinder base plate 20. Using countersunk bolts 13, fix the guide piston 15 to the end of the telescopic rod 17 on the spare electric cylinder 21 through the countersunk hole 23. Using countersunk bolts 13, fix the main electric cylinder 14 with the telescopic rod 17 to the bottom of the fixing plate 16 with the fixing hole 7. Use bolts 8 to fix the fixing plate 16 inside the guide piston 15 through the fixing hole 7. Use countersunk bolts 13 to fix the magnet fixing plate 32 with the fixing hole 7 to the end of the telescopic rod 17 on the main electric cylinder 14. Place the push magnet 12 into the magnet cover 33, and then use bolts 8 to fix the push magnet 12 to the bottom of the magnet fixing plate 32 through the flange 6 and the fixing hole 7 on the magnet cover 33. One end of the control cable 25 of the cable spiral joint 30 passes through the wire hole 24 on the guide piston 15 and connects to the main electric cylinder 14. The other end of the control cable 25 of the cable spiral joint 30 connects to the control server 26, which has an input signal cable 27 and a power line 28, through the wire hole 24 on the guide cylinder 29 and the air supply cover 18. One end of the control cable 25 passes through the wire hole 24 on the guide cylinder 29 and connects to the spare main electric cylinder 21, and the other end passes through the wire hole 24 on the air supply cover 18 and connects to the control server 26. The guide cylinder base plate 20 and the guide cylinder 29 are fixed to the center position under the air supply cover 19 with bolts 8. The valve disc magnet 11 is placed in the magnet cover 33, and then the valve disc magnet 11 is fixed to the center position on the conical valve disc 10 through the flange 6, the fixing hole 7 on the magnet cover 33 and the screw hole 5 on the conical valve disc 10 with bolts 8. Three guide valve shafts 1 are divided into 120-degree sections by the shaft seat 35 on the guide valve shaft 1 and fixed to the bottom of the conical valve disc 10 with bolts 8. The guide valve shafts 1 are at the same distance from the center of the conical valve disc 10. Three ribs 36 of equal length and distributed at 120-degree intervals are welded together at their front ends and welded to the lower inner side of the valve cylinder 4 at their rear ends. Guide sleeves 2 are welded onto the three ribs 36 respectively, and the three guide sleeves 2 are concentric with the three guide valve shafts 1. After the three springs 3 are fitted onto the guide valve shafts 1, the three guide valve shafts 1 are inserted into the guide sleeves 2. The valve cylinder 4 is placed on the flange 6 of the rotary air supply pipe 37, and then the valve seat 9 with the conical valve port 34 is placed on the flange 6 of the valve cylinder 4. The valve seat 9 and the valve cylinder 4 are fixed to the upper flange 6 of the rotary air supply pipe 37 with bolts 8 through the fixing holes 7 and screw holes 5. The conical valve disc 10 is closed by the conical valve port 34 on the valve seat 9 under the action of the three springs 3. Secure the air supply cover 19 to the air supply hood 18 with the air supply pipe 31. The process is complete.

Claims

1. A magnetic push-type automatic adjustment conical valve disc stroke center air replenishment device for a main and backup electric cylinder, comprising an air replenishment cover and an air replenishment pipe on the air replenishment hood, a rotary air replenishment pipe, and a flange on the rotary air replenishment pipe, characterized in that... A spare electric cylinder is fixed below the bottom plate of the guide cylinder. A guide piston is fixed to the end of the 2L-length telescopic rod on the spare electric cylinder. The main electric cylinder is fixed inside the guide piston via a fixing plate. The travel of the telescopic rod on the spare electric cylinder is greater than or equal to 2L, and the travel of the telescopic rod on the main electric cylinder is L. The value of a in travel L is not zero. A magnet fixing plate is fixed to the lower end of the telescopic rod of the main electric cylinder. A magnet cover is used to fix the thrust magnet below the magnet fixing plate. A control cable with a cable spiral joint is used to connect the main electric cylinder to the control server through the cable holes on the guide piston, guide cylinder, and air supply cover. A control cable is also used to connect the spare electric cylinder to the control server through the cable holes on the guide cylinder and air supply cover. The bottom plate of the guide cylinder and the guide cylinder are both fixed at the center position below the air supply cover. The valve disc magnet is fixed to the center of the conical valve disc using a magnetic shield, aligning the N pole of the pushing magnet with the N pole of the valve disc magnet. Three guide valve shafts are fixed at 120-degree angles below the conical valve disc, with their centers having the same diameter as the center of the conical valve disc. Equal-length stiffeners are welded together at 120-degree angles, and their rear ends are welded to the inner wall of the valve cylinder. A guide sleeve is welded to the side of each stiffener, with the guide hole on each sleeve concentric with the guide valve shaft. Three springs are respectively fitted onto the three guide valve shafts below the conical valve disc, and the three guide valve shafts are then passed through the guide holes to position the conical valve disc at the top of the valve cylinder. The conical valve disc is fixed to the flange of the rotary air supply pipe via a valve seat with a conical valve port and the valve cylinder. The conical valve disc is concentric with the pushing magnet. The air supply cover is then fixed to the air supply cover.

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