Constant-vacuum-adjustable annular valve disc mixed flow hydraulic turbine center operation air supplement device

Abstract

The application discloses a constant-vacuum adjustable annular valve disc mixed flow hydraulic turbine center operation air supplement device, an outer cylinder with a fixed flange is fixed on the upper end of an air supplement pipe through a lower bottom ring with an air supplement hole, the upper end is provided with a fixed flange, an upper air inlet, an air inlet pipe with an inner valve seat and an outer diameter and four to eight circumferential air inlets in the lower part is welded on the bottom cover through a welding ring pipe; four guide sleeves are fixed in the inner cylinder through four fixed plates, the inner cylinder with an outer valve seat is fixed on the bottom cover, the inner and outer valve seats are respectively provided with an inner conical valve port and an outer conical valve port, inner and outer conical valve ports are formed on the inner and outer valve discs of the annular valve disc; an adjusting ring is fixed in a ladder-shaped ring groove, four guide shafts concentric with guide holes are fixed below the annular valve disc, the guide shafts pass through the guide holes, and the annular valve disc is arranged in the inner and outer conical valve ports on the inner and outer valve seats; the air inlet pipe is fixed at a central position below an upper ring cover with an air inlet hole, and the upper ring cover is fixed on the outer cylinder. The scheme is applied to the field of air supplement of hydraulic turbines.

Description

Technical fields:

[0001] This invention is a device for maintaining constant vacuum and adjustable center air supply during the full-load operation range of large and medium-sized mixed-flow turbines. Background technology:

[0002] Currently, green energy sources such as wind and solar power are increasingly being integrated into the power grid, putting hydropower plants under peak-shaving and frequency-regulating conditions. Especially when giant mixed-flow turbine generator units are operating under peak-shaving and frequency-regulating conditions, the mixed-flow turbine deviates from its rated operating conditions, creating a huge vacuum zone below the turbine's exhaust cone. The smaller the load on the mixed-flow turbine, the greater the vacuum level in this zone. This vacuum not only causes abnormal vibrations in the mixed-flow turbine but also exacerbates blade cavitation and cracks at the blade exit edges, posing serious safety hazards to the generator unit structure. Existing linear air-injection devices using springs are no longer sufficient to improve the operating conditions of mixed-flow turbines during peak shaving and frequency regulation. Air-injection valves without springs are not only extremely heavy but also have poor dynamic balance; the valve disc alone weighs half a ton, causing frequent damage to the valve shaft and buffer devices. Lifting the half-ton valve disc requires the mixed-flow turbine to generate a vacuum of 0.02–0.03 MPa or higher, which leads to severe abnormal vibrations, significantly shortening the turbine's service life and increasing maintenance workload. The valve disc structure cannot adjust its weight to meet the minimum air-injection vacuum required for the mixed-flow turbine. Therefore, adopting a reasonable, smooth, and stable air-injection device is a crucial technical measure to improve the operation of mixed-flow turbines during peak shaving and frequency regulation, eliminating abnormal vibrations, suppressing cavitation, and reducing cracking. Therefore, many large hydropower plants urgently need a gas supply device that can effectively improve the operating conditions of mixed-flow turbines during peak shaving and frequency regulation. This new type of gas supply device should have the functions of constant vacuum degree, adjustable gas supply vacuum degree, reliable structure, long service life, stable performance and good sealing performance, and substantial technological progress. Summary of the Invention:

[0003] The technical solution provided by this invention fully meets the full-load operating air supply requirements of giant mixed-flow turbines in large hydropower plants. The basic working principle and technical features of this air supply device are as follows: An outer cylinder with a fixed flange at the upper end is bolted to the fixed flange at the end of the air supply pipe via a bottom ring with air supply holes and a connecting hole; an air inlet pipe with a fixed flange at the upper end, an upper air inlet, an inner valve seat fixed in the middle of the outer surface, and 4-8 circumferential air inlets machined on the lower end is welded to the center of the bottom cover via a welded ring pipe; four guide sleeves with guide holes are welded to the inner side of the inner cylinder at 90 degrees and equal height using four fixed plates, with the center of the guide hole distribution circle concentric with the annular valve disc, and the axial direction of the guide holes perpendicular to the bottom cover; the upper end with... It has an outer valve seat and an inner cylinder with a fixed flange at the lower end. It is bolted to the bottom cover via the engagement holes on the bottom cover and the threaded holes on the fixed flange. The outer valve seat has an external tapered valve port, and the inner valve seat has an internal tapered valve port. The a value is ≥5~40mm. An external tapered valve port is machined on the outer valve disc of the annular valve disc, and an internal tapered valve port is machined on the inner valve disc. The adjusting ring is placed into the trapezoidal annular groove on the annular valve disc. Through four sets of engagement holes evenly distributed on the adjusting ring and the flange seat, the adjusting ring is fixed to the trapezoidal annular groove on the annular valve disc using four sets of bolts. Four guide shafts are fixed below the annular valve disc. Furthermore, it is concentric with the guide holes on the four guide sleeves, allowing the four guide shafts to slide through the guide holes. The annular valve disc with the four guide shafts is placed in the inner conical valve port on the inner valve seat and the outer conical valve port on the outer valve seat. The inner conical valve port of the inner valve disc and the outer conical valve port of the outer valve disc respectively seal against the conical surfaces of the corresponding inner conical valve port and outer conical valve port of the inner and outer valve seats. L is the maximum stroke of the annular valve disc, and the length of the guide shaft is 1.5L. Multiple adjusting rings of different weights are selected by calculation to adjust the overall weight of the annular valve disc. The weight is equal to the mass m multiplied by the gravitational acceleration g, i.e., the weight equals m... g, to ensure that the constant vacuum level can be maintained within a reasonable range of 0.001 to 0.015 MPa; the air inlet pipe is fixed to the center position below the upper ring cover by bolts through the threaded hole of the fixing flange at the upper air inlet position and the mating hole at the air inlet position; the upper ring cover is fixed to the upper end of the outer cylinder by bolts through the mating hole and the threaded hole on the fixing flange at the upper end of the outer cylinder; the air inlet pipe, annular valve disc, inner cylinder and bottom cover together with the upper ring cover, outer cylinder, lower bottom ring, air inlet hole, air inlet and air inlet pipe form a vacuum annular cavity that communicates with the vacuum zone, and the air inlet pipe, annular valve disc, inner cylinder and bottom cover form a positive pressure annular cavity that communicates with the atmosphere.The inner conical valve port on the inner valve seat and the outer conical valve port on the outer valve seat have good sealing performance with the inner and outer conical surfaces of the annular valve disc; the flow ring area formed by the air inlet, the upper air inlet, the 4 to 8 circumferential air outlets, and the inner and outer conical valve ports all meet the flow area requirements of the air supply port and air supply hole; the flow area of ​​the vacuum annular cavity also meets the technical requirements for air supply; the inner cylinder and the bottom cover, the air inlet pipe and the upper annular cover, the outer cylinder and the upper annular cover, and the lower bottom ring and the air supply pipe are all fixed by a sealed connection; the 4 guide shafts and 4 guide sleeves fit well without jamming; because the annular valve disc is lightweight, it descends into the wind during the air supply process, thus having good slow descent performance; because this technical solution adopts a central air supply method, the overall dynamic balance performance is excellent.

[0004] The technical effect achieved by the technical solution provided by this invention is as follows: Based on the optimal vacuum value P determined during the peak-shaving and frequency-regulating processes of the mixed-flow turbine, and based on the effective area S of the annular valve disc, the overall mass m of the annular valve disc can be calculated using the formula P×S=F, where F is the suction force generated by the vacuum lifting the entire weight of the annular valve disc. The overall mass m of the annular valve disc is the mass of the annular valve disc itself plus the mass of the adjusting ring and the four guide shafts. Using P×S=F=mg, where m is the overall mass of the annular valve disc and g is the acceleration due to gravity; m=P×S / g, after unifying the units, the overall mass m of the annular valve disc under the optimal constant vacuum gas supply condition can be calculated. The frictional force between the guide shaft and the guide hole can be ignored. During the entire gas supply process of the mixed-flow turbine during peak-shaving and frequency-regulating power generation, the overall mass m of the annular valve disc is constant, and the overall weight of the annular valve disc is also constant; only the stroke L of the annular valve disc varies according to the gas supply amount. The annular valve disc mass, weight, and gravity used in this specification are only for ease of description and calculation and have no essential difference. The change in the stroke L of the annular valve disc only causes a change in the amount of air supplied, and does not cause a change in the vacuum value P. When the vacuum level in the vacuum zone generated during the operation of the mixed-flow turbine reaches the optimal air supply threshold P, the annular valve disc is sucked up and rises. Atmospheric air enters the vacuum annular cavity through the air inlet, upper air inlet, air inlet pipe, and 4-8 circumferential air inlets, passing through the annular flow ring formed by the inner and outer conical valve ports. Air then flows into the vacuum zone generated by the mixed-flow turbine through the vacuum annular cavity, air supply holes, air supply ports, and air supply pipes. When the a value is ≥5-40mm, the annular valve disc floats under the action of the upward airflow generated by the inner and outer conical valve ports. At this time, the weight of the annular valve disc and the wind force generated by the upward airflow reach a temporary balance, and the annular valve disc stabilizes at a certain stroke position. When the vacuum level in the vacuum zone stabilizes at the optimal P value, the mixed-flow turbine has the highest efficiency, the most stable operating conditions, no abnormal vibration, and effectively suppresses cavitation and crack formation. When the vacuum level in the vacuum zone increases, the annular valve disc moves upward, increasing its stroke and flow area, thus increasing the amount of air supplied to the vacuum zone and restoring the vacuum level to the P value. When the vacuum level in the vacuum zone decreases, the annular valve disc moves downward, decreasing its stroke and flow area, thereby reducing the amount of air supplied to the vacuum zone and restoring the vacuum level to the P value. When the vacuum zone disappears, the annular valve disc slowly falls back to its original sealing position. Regardless of how the vacuum level changes during peak shaving and frequency regulation of the mixed-flow turbine, the annular valve disc, with a fixed total weight, moves up and down to increase or decrease its stroke, thereby increasing or decreasing the amount of air supplied, stabilizing the vacuum level in the vacuum zone at the P value, thus achieving the technical effect of constant vacuum air supply. Depending on the parameters of different mixed-flow turbines, the total weight of the annular valve disc can be adjusted by increasing or decreasing the weight of the adjusting ring to achieve the optimal air supply vacuum value P value within a reasonable range of 0.001–0.015 MPa.The annular valve disc is made of aluminum alloy. The four guide shafts are used to ensure that the annular valve disc is in a sealed state when it falls back. All other structures are made of stainless steel.

[0005] The specification only discloses one of the technical solutions of the present invention. Other technical solutions obtained by those skilled in the art without creative effort based on the disclosure of the present invention are all within the protection scope of the present invention.

[0006] The technical solution disclosed in this invention solves the technical challenge of constant vacuum air replenishment for large mixed-flow turbines during peak shaving and frequency regulation. It provides a technical guarantee for improving the operating environment of large mixed-flow turbines under peak shaving and frequency regulation conditions, ensuring safe operation, avoiding abnormal vibration, reducing maintenance workload, and improving economic efficiency. This technical solution is novel, inventive, and practical compared to existing solutions. Its ingenious design, reasonable structure, and strong practicality, along with the advantage of long-term maintenance-free operation, will be widely applied in the field of central air replenishment for mixed-flow turbines. Attached image description:

[0007] Figure 1 A front view of a constant vacuum adjustable annular valve disc mixed-flow turbine center operation air supply device.

[0008] Figure 2 A constant vacuum adjustable annular valve disc mixed-flow turbine center operation air supply device (AA view)

[0009] Figure 3 A constant vacuum adjustable annular valve disc mixed-flow turbine center operation air supply device (BB view)

[0010] Figure 4 A CC view of a constant vacuum adjustable annular valve disc mixed-flow turbine center operation air supply device.

[0011] in:

[0012] 1. Air supply tube 2. Air supply port 3. Air supply hole

[0013] 4. Threaded hole; 5. Bolt; 6. Bottom cover

[0014] 7. Bottom ring; 8. Outer cylinder; 9. Fixed flange

[0015] 10. Inner cylinder; 11. Vacuum annular cavity; 12. Guide shaft

[0016] 13. Guide sleeve; 14. Fixing plate; 15. Outer valve seat

[0017] 16. Outer valve disc; 17. Upper ring cover; 18. Adjusting ring

[0018] 19. Inner valve disc; 20. Inner valve seat; 21. Air inlet.

[0019] 22. Top air inlet 23. Circumferential air inlet 24. Air inlet duct

[0020] 25. Internal conical valve port; 26. Trapezoidal annular groove; 27. Annular valve disc.

[0021] 28. Fitting hole; 29. ​​External conical valve port; 30. Flange seat

[0022] 31. Guide hole; 32. Positive pressure ring cavity; 33. Welded ring tube Detailed implementation method:

[0023] The outer cylinder 8, with a fixed flange 9 at the upper end, is fixed to the upper fixed flange 9 of the air supply pipe 1 by bolts 5 and threaded holes 4 through a bottom ring 7 with a central air supply hole 3 and a mating hole 28. The air inlet pipe 24, with a fixed flange 9 at the upper end, an upper air inlet 22, an inner valve seat 20 in the middle of the outer side, and 4 to 8 circumferential air outlets 23 at the bottom, is welded to the center of the bottom cover 6 by welding ring pipe 33. The guide sleeves 13 with guide holes 31 are fixed at 90 degrees to the inner surface of the inner cylinder 10 by four fixing plates 14, with the center of the guide holes 31 all located on the annular valve disc 2. On the center circle 7, the guide hole 31 is perpendicular to the annular valve disc 27; through the mating hole 28 on the bottom cover 6 and the threaded hole 4 on the fixing flange 9 at the lower end of the inner cylinder 10, the inner cylinder 10 with the outer valve seat 15 at the upper end is fixed to the bottom cover 6 in a sealing manner with bolts 5. An outer conical valve port 29 is machined on the outer valve seat 15, and an inner conical valve port 25 is machined on the inner valve seat 20. An outer conical valve port 29 is machined on the outer valve disc 16 on the annular valve disc 27, and an inner conical valve port 25 is machined on the inner valve disc 19 on the annular valve disc 27; the adjusting ring 18 is placed on the outer valve disc 16 with the inner conical valve port 25 and the inner valve seat 19 on the annular valve disc 27. In the trapezoidal annular groove 26 on the annular valve disc 27, through four sets of mutually 90-degree mating holes 28 and flange seats 30, the adjusting ring 18 is fixed in the trapezoidal annular groove 26 with bolts 5. Four guide shafts 12 are fixed below the annular valve disc 27, with the centers of the four guide shafts 12 aligned with the four guide holes 31. The four guide shafts 12 pass through the four guide holes 31, allowing them to slide freely up and down without gaps within the four guide holes 31, so that the annular valve disc 27 falls between the inner conical valve port 25 and the outer conical valve port 29 in a sealing manner. The air inlet pipe 24 passes through the upper end... The threaded hole 4 and engagement hole 28 on the fixed flange 9 are fixed to the center position below the upper ring cover 17 with air inlet hole 21 using bolts 5, so that the air inlet pipe 24 is concentric with the air inlet hole 21; the upper ring cover 17 is fixed to the upper end of the outer cylinder 8 through the engagement hole 28 and the threaded hole 4 on the fixed flange 9 using bolts 5; the upper ring cover 17, outer cylinder 8, lower bottom ring 7, air inlet hole 3, air inlet port 2 and air inlet pipe 1 form a vacuum annular cavity 11 that communicates with the vacuum zone; the air inlet pipe 24, annular valve disc 27, outer valve seat 15, inner valve seat 20 and bottom cover 6 form a positive pressure annular cavity 32 that communicates with the atmosphere. All engagement positions are sealed. Implementation complete.

Claims

1. A constant vacuum adjustable annular valve disc mixed-flow turbine center-run air supply device, characterized in that, The outer cylinder, with a fixed flange at the top, is bolted to the fixed flange at the end of the air supply pipe via a bottom ring with air supply holes and a fitting hole. An air inlet pipe, with a fixed flange at the top, an upper air inlet, an inner valve seat fixed in the middle of its outer surface, and 4-8 circumferential air outlets machined on the bottom, is welded to the center of the bottom cover via a welding ring pipe. Four guide sleeves with guide holes are welded to the inner cylinder at 90-degree angles and equal height using four fixing plates. The center of the guide hole distribution circle is aligned with the annular valve disc. The core, with the guide hole axially perpendicular to the bottom cover; the inner cylinder with an outer valve seat at the upper end and a fixed flange at the lower end, is bolted to the bottom cover through the mating hole on the bottom cover and the threaded hole on the fixed flange; the outer valve seat is machined with an outer conical valve port, and the inner valve seat is machined with an inner conical valve port; the a value is ≥5~40mm. An outer conical valve port is machined on the outer valve disc of the annular valve disc, and an inner conical valve port is machined on the inner valve disc of the annular valve disc. The adjusting ring is placed into the trapezoidal annular groove on the annular valve disc, and then... (The sentence is incomplete and requires further context to translate accurately.) Four sets of engagement holes and flange seats are distributed on the adjusting ring. The adjusting ring is fixed to the trapezoidal annular groove on the annular valve disc using four sets of bolts. Four guide shafts are fixed below the annular valve disc and concentric with the guide holes on the four guide sleeves, allowing the four guide shafts to slide through the guide holes. The annular valve disc with the four guide shafts is placed in the inner conical valve port on the inner valve seat and the outer conical valve port on the outer valve seat. The inner conical valve port of the inner valve disc and the outer conical valve port of the outer valve disc respectively... The inner conical valve port of the inner valve seat and the outer conical valve port of the outer valve seat are in conical sealing contact; L is the maximum stroke of the annular valve disc, and the length of the guide shaft is 1.5L; fix the air inlet pipe at the center position below the upper ring cover; fix the upper ring cover to the upper end of the outer cylinder; the air inlet pipe, annular valve disc, inner cylinder and bottom cover together with the upper ring cover, outer cylinder, lower bottom ring, air inlet hole, air inlet port and air inlet pipe form a vacuum annular cavity that communicates with the vacuum zone, and the air inlet pipe, annular valve disc, inner cylinder and bottom cover form a positive pressure annular cavity that communicates with the atmosphere.

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