Right-angle isosceles air cavity type buffer double-inclined-plane seal constant-pressure air supplement device

Abstract

The application discloses a right-angled isosceles air chamber type buffer double-inclined-plane sealed constant-pressure air supplement device, four rib plates concentrically fix an outer cover with a mounting flange and a center air inlet pipe with a bottom ring together. An outer sealing ring with an outer sealing ring groove is fixed on the rib plate of the inner surface of the outer cover, an inner sealing ring with an inner sealing ring groove is fixed on the rib plate of the center air inlet pipe, and the inner and outer sealing ring grooves are provided with inner and outer right-angled isosceles rings. The sealing vertical ring and the bottom of the inner and outer sealing ring grooves form an air buffer chamber. Two anti-rotation shafts fixed on a cross beam pass through two anti-rotation holes on an anti-rotation beam, and the anti-rotation beam is fixed on the upper end of the center air inlet pipe. The cross beam is fixed on the upper surface of a ring-shaped valve disc with inner and outer right-angled isosceles grooves, and the inner and outer right-angled isosceles grooves are concentric with the inner and outer right-angled isosceles rings. An upper cover is fixed on the outer cover, and the center air inlet pipe is fixed on the upper end of an air supplement pipeline through the bottom ring. The technical scheme disclosed by the application can be widely applied to the wide-load air supplement field of mixed-flow water turbines and reversible mixed-flow water turbines.

Description

Technical fields:

[0001] This invention is an air supply device for mixed-flow turbines and reversible mixed-flow turbines during low-load operation. Background technology:

[0002] Currently, conventional mixed-flow turbines and pumped-storage reversible mixed-flow turbines, under low-load operating conditions, exhibit eccentric vortex bands, Karman vortex streets, and high-speed, low-flow operation, resulting in a large and harmful vacuum zone at the turbine center. This vacuum zone causes abnormal vibration, structural fatigue, and poses a serious threat to the safe operation of the unit. To eliminate this harmful vacuum zone at low loads in mixed-flow turbines, those skilled in the art utilize existing air-injection devices to introduce air into the harmful vacuum zone, thereby eliminating it, reducing unit vibration, extending service life, and reducing maintenance workload. However, existing air replenishment devices generally use springs to control the valve disc stroke. The suction force generated by the vacuum on the valve disc compresses the spring through the valve shaft, causing the valve disc to open. The larger the working stroke of the valve disc, the greater the amount of air replenished, and the greater the vacuum generated by the mixed-flow turbine. The working stroke of the valve disc is positively correlated with the vacuum level; that is, the larger the working stroke of the valve disc, the greater the vacuum level in the harmful vacuum zone of the mixed-flow turbine. When the vacuum level exceeds the reasonably designed vacuum level threshold, due to the lag in air replenishment, even if air is replenished, it will cause the unit to experience instantaneous and violent vibrations. Therefore, the existing linear air replenishment devices are not suitable for applying air replenishment to mixed-flow turbines under low-load conditions in principle. Furthermore, the existing air replenishment devices have complex structures, with extremely complex conical valve disc sealing structures, air buffers, and oil buffers. The buffer medium oil is also prone to leakage, leading to buffer failure, and their manufacturing cost is very high. The springs are also prone to fatigue fracture or deformation due to long-term use, causing the air replenishment vacuum level to become uncontrollable. There is an urgent need in this field for conventional mixed-flow turbines and reversible mixed-flow turbines in pumped storage power stations to develop a simple, reliable, and effective air replenishment device with a valve disc working stroke that is not positively correlated with the vacuum level. That is, during the air replenishment process of the mixed-flow turbine in a wide load operating range, the vacuum level of the turbine in the vacuum zone can be kept stable within a reasonable range of the design threshold through smooth and reasonable air replenishment. This device is called a constant pressure air replenishment device. Summary of the Invention:

[0003] The technical solution involved in this invention is proposed to meet the technical requirements for air replenishment under low-load operation conditions of mixed-flow turbines and reversible mixed-flow turbines. Its main technical features are: Four connecting and fixing ribs between an outer cover with a mounting flange at the upper end and a central air inlet pipe with a bottom ring at the lower end are fixed with an outer sealing ring and an inner sealing ring. The outer sealing ring is fixed to the inner surface of the outer cover in a sealing manner, and the inner sealing ring is fixed to the upper end of the central air inlet pipe in a sealing manner. The inner surface of the outer cover and the outer surface of the central air inlet pipe form an air inlet ring, and the inner surface of the outer sealing ring and the outer surface of the inner sealing ring form an air replenishment ring. An outer right-angled isosceles ring with two sealing vertical rings below is installed in the outer sealing ring groove on the outer sealing ring in a sealing manner. The annular valve disc has two vertical sealing rings and the bottom surface of the outer sealing ring groove forming a buffer air chamber. An inner right-angled isosceles ring with two vertical sealing rings underneath is installed in the inner sealing ring groove on the inner sealing ring in a sealing manner. The two vertical sealing rings and the bottom surface of the inner sealing ring groove form a buffer air chamber. An outer right-angled isosceles groove and an inner right-angled isosceles groove are machined on the underside of the annular valve disc, and are concentric with the outer and inner right-angled isosceles rings respectively. The right-angled surface of the outer right-angled isosceles groove is in sealing contact with the right-angled surface of the outer right-angled isosceles ring, and the right-angled surface of the inner right-angled isosceles groove is in sealing contact with the right-angled surface of the inner right-angled isosceles ring. Through the through holes on the anti-rotation beam and the threaded blind holes on the fixing flange, two anti-rotation shafts are symmetrically fixed to the bottom of the crossbeam with bolts. The two anti-rotation shafts pass through the anti-rotation holes on the anti-rotation beam. The anti-rotation beam is fixed at the center of the central intake pipe. The anti-rotation shafts can slide freely up and down in the anti-rotation holes. Both ends of the crossbeam are fixed to the center of the annular valve disc. The upper cover is fixed to the upper mounting flange of the outer cover in a sealing manner. The stroke L is the maximum distance the annular valve disc is lifted. The maximum stroke L of the annular valve disc is 50-100 mm away from the upper cover. An outer right-angled isosceles groove is present. The lower surface and the lower surface of the inner right-angled isosceles groove maintain a buffer distance of 5-20 mm from the upper surfaces of the outer and inner sealing rings, respectively. The total weight W of the annular valve disc, crossbeam, two anti-rotation shafts, and fixing bolts must be balanced with the suction force generated by the designed reasonable vacuum threshold aMPa. W = S × aMPa, where S is the area of ​​the gas replenishment ring, i.e., aMPa = W / S. The central air inlet pipe is bolted to the fixing flange at the end of the gas replenishment pipe through the flange hole and threaded blind hole on the bottom ring. The air inlet chamber is connected to the vacuum zone of the gas replenishment pipe. The total weight W of the annular valve disc, crossbeam, and two anti-rotation shafts must be balanced with the suction force generated by the designed reasonable vacuum threshold aMPa. W = S × aMPa, where W is the weight in kilograms; S is the area of ​​the gas replenishment ring in square centimeters; the vacuum design threshold aMPa is converted to akg / cm². 2A smaller vacuum design threshold (aMPa) results in a lighter total weight (W); a larger vacuum design threshold (aMPa) results in a heavier total weight (W). The surfaces of the outer and inner right-angled isosceles grooves fit tightly against the surfaces of the rubber-made outer and inner right-angled isosceles rings. This sealing structure has two right-angled sealing surfaces, providing a better sealing effect than conical seals. When the annular valve disc falls rapidly, the inner and outer right-angled isosceles rings and the buffer chamber provide excellent buffering. The inner and outer right-angled isosceles rings and the buffer chamber absorb all the kinetic energy of the falling annular valve disc, thus achieving a buffering effect. The structure is simple and can completely replace the complex air and oil buffering devices in existing technologies. The lower surfaces of the outer and inner right-angled isosceles grooves maintain a buffer distance of 5–20 mm from the upper surfaces of the outer and inner sealing rings, respectively. This device is fixed to the air supply pipe and rotates at the same speed as the turbine. Two anti-rotation shafts can move freely up and down within the anti-rotation holes. The torque generated by these shafts keeps the annular valve disc relatively stationary with respect to the inner and outer right-angled isosceles rings, ensuring concentricity and improving sealing performance. The stroke L is the maximum distance the annular valve disc is lifted. The upper cover is 50-100 mm higher than the stroke L to prevent the annular valve disc from colliding with the upper cover during rapid ascent, thus converting its kinetic energy into potential energy. The flow area of ​​the air supply ring fully meets the flow area of ​​the central air inlet pipe, and the flow area of ​​the air inlet ring opening also meets the flow area of ​​the air supply ring. The outer cover is concentrically fixed to the outside of the central air inlet pipe by welding with four stiffeners, and the air inlet ring opening maximizes the air supply volume.

[0004] The technical effect achieved by the disclosed technical solution of this invention is as follows: First, the vacuum threshold aMPa for air replenishment is calculated and determined based on the main technical parameters of the mixed-flow turbine. This threshold aMPa represents the optimal vacuum level for the mixed-flow turbine in low-load conditions, ensuring both maximum turbine efficiency and minimum vibration amplitude and frequency, thus meeting operational requirements. Based on the determined vacuum threshold aMPa, the total weight W of the moving parts of the annular valve disc, crossbeam, and two anti-rotation shafts is calculated, using a consistent unit of measurement. The weight of each component of the annular valve disc, crossbeam, and two anti-rotation shafts is designed based on the total weight W of the moving parts. The total weight W must include the weight of the fixed standard parts, and the unit is kilograms. A reasonable clearance is maintained between the anti-rotation shafts and the anti-rotation holes, and lubricant is applied; friction is negligible. When a mixed-flow turbine generates a large vacuum zone under low load, and the vacuum level reaches the design vacuum threshold a MPa, the vacuum level will draw open the annular valve disc through the air supply pipe and the central air intake pipe. Air from the atmosphere enters the vacuum zone of the mixed-flow turbine through the air intake ring, air supply ring, air intake chamber, and air supply pipe. The amount of air supplied is controlled by the stroke of the annular valve disc being lifted. The larger the vacuum zone formed by the mixed-flow turbine, the greater the stroke of the annular valve disc being lifted, and the more air is supplied. However, the vacuum threshold a MPa of the vacuum zone remains constant. This is because the vacuum threshold a MPa is controlled by the total weight W of the moving parts and the area S of the air supply ring, i.e., a MPa = W / S. The total weight W of the moving parts and the area S of the air supply ring remain constant during the air supply process. When the vacuum zone created by the mixed-flow turbine is small, the stroke of the annular valve disc being lifted is shorter, and the amount of air introduced is less; conversely, when the vacuum zone created by the mixed-flow turbine is large, the stroke of the annular valve disc being lifted is longer, and the amount of air introduced is more. Throughout this process, the vacuum threshold aMPa remains constant. Therefore, the technical solution disclosed in this invention maintains a constant vacuum threshold aMPa regardless of changes in the volume of the vacuum zone created by the mixed-flow turbine. Only changes in the stroke of the annular valve disc, and the amount of air introduced, ensure that the designed vacuum threshold aMPa remains constant throughout the air supply process of the mixed-flow turbine generating the vacuum zone across the entire wide-load operating zone. Even if the vacuum level in the vacuum zone of the mixed-flow turbine rises rapidly due to abnormal phenomena caused by Karman vortex street and hydraulics, the stroke of the annular valve disc will also increase rapidly. At this time, the annular valve disc must not hit the top cover. At the same time, a large amount of air is introduced to quickly bring the abnormally high vacuum level in the vacuum zone back to the set reasonable aMPa vacuum level threshold. This effectively and reasonably maintains constant pressure and prevents the mixed-flow turbine from generating severe vibrations.This technical solution perfectly solves the defect in the prior art where the valve disc gas replenishment stroke of the linear gas replenishment device is positively correlated with the vacuum degree of the vacuum zone; it replaces the complex buffer device in the prior art with inner and outer right-angle isosceles rings and buffer gas chambers with simple structure and excellent buffer performance; more importantly, it eliminates the spring in the prior art that is easy to break and deform and does not meet the requirements of gas replenishment.

[0005] The specification only discloses one of the technical solutions of the present invention. Based on the content disclosed in the present invention, other technical solutions obtained by those skilled in the art without creative effort are all within the protection scope of the present invention.

[0006] The technical solution disclosed in this invention solves the technical defect that the linear gas replenishment device in the prior art is positively correlated with the vacuum degree. It omits the easily broken and deformable spring, and adopts a double-sided sealing structure with inner and outer right-angle isosceles rings made of rubber to improve the sealing performance of this device, which is superior to the conical seal in the prior art. At the same time, it also absorbs the kinetic energy of the annular valve disc falling, achieving a good buffering effect.

[0007] The technical solution disclosed in this invention has an ingenious and simple structure with high reliability. By utilizing the constant total weight W of the moving parts and the area S of the air-injection ring, the optimal vacuum threshold aMPa is controlled to remain constant, thus achieving the technical objective and effect of efficient and stable operation of the mixed-flow turbine in a wide load range. Compared with existing technical solutions, the technical solution disclosed in this invention is novel, inventive, and practical, and will be widely used in the field of wide-load constant-pressure air injection for conventional mixed-flow turbines and reversible mixed-flow turbines in pumped-storage power stations. Attached image description:

[0008] Figure 1 Main view of the right-angled isosceles air chamber type buffer double inclined surface sealing constant pressure air replenishment device

[0009] Figure 2 Right-angled isosceles air chamber type buffer double inclined surface sealing constant pressure air replenishment device (AA view)

[0010] Figure 3 Right-angled isosceles air chamber type buffer double inclined surface sealing constant pressure air replenishment device BB view

[0011] Figure 4 Enlarged view of a right-angled isosceles air chamber type buffer double-sloping-face sealed constant pressure air supply device

[0012] in:

[0013] 1. Gas supply pipe 2. Mounting flange 3. Threaded blind hole

[0014] 4. Bolts 5. Flange holes 6. Bottom ring

[0015] 7. Central air intake pipe; 8. Air intake ring; 9. Outer cover.

[0016] 10. Rib plate; 11. Outer sealing ring; 12. Buffer air chamber

[0017] 13. Outer sealing ring groove; 14. Sealing vertical ring; 15. Outer right-angle isosceles groove.

[0018] 16. Annular valve disc; 17. Top cover; 18. Outer right-angle isosceles ring.

[0019] 19. Crossbeam; 20. Air inlet ring; 21. Inner right-angle isosceles ring.

[0020] 22. Inner sealing ring; 23. Anti-rotation shaft; 24. Fixed flange

[0021] 25. Anti-rotation hole; 26. Through hole; 27. Air intake chamber

[0022] 28. Anti-rotation beam; 29. ​​Inner right-angle isosceles groove; 30. Inner sealing ring groove. Detailed implementation method:

[0023] An outer cover 9 with a mounting flange 2 at the upper end is concentrically fixed to a central air intake pipe 7 with a bottom ring 6 at the lower end via four stiffening plates 10. The inner surface of the outer cover 9 and the outer surface of the central air intake pipe 7 form an air intake ring 8. An outer sealing ring 11 is welded in a sealing manner to the inner surface of the outer cover 9 at the upper end of the stiffening plate 10. An inner sealing ring 22 is welded in a sealing manner to the end of the central air intake pipe 7 and the top of the stiffening plate 10. The inner diameter of the outer sealing ring 11 and the outer diameter of the inner sealing ring 22 form a replenishing air ring 20. An outer sealing ring groove 13 is machined on the upper part of the 1st sealing ring, and an inner sealing ring groove 30 is machined on the inner sealing ring 22. An outer right-angled isosceles ring 18 and an inner right-angled isosceles ring 21 with two sealing vertical rings 14 at their lower ends are respectively installed into the outer sealing ring groove 13 and the inner sealing ring groove 30 in a sealing manner. The two sets of sealing vertical rings 14 and the bottom surfaces of the outer sealing ring groove 13 and the inner sealing ring groove 30 respectively form two buffer air chambers 12. An anti-rotation beam 28 with two anti-rotation holes 25 is fixed at the upper center position inside the central air intake pipe 7. Two anti-rotation shafts 23 are symmetrically fixed to the underside of the crossbeam 19 using bolts 4 through the through holes 26 on the anti-rotation beam 28 and the threaded blind holes 3 on the fixing flange 24, allowing the two anti-rotation shafts 23 to freely pass through the two anti-rotation holes 25 on the anti-rotation beam 28; the two ends of the crossbeam 19 are fixed to the annular valve disc 16 using bolts 4 through the through holes 26 at both ends of the crossbeam 19 and the threaded blind holes 3 on the annular valve disc 16; the outer right-angled isosceles groove 15 and the inner right-angled isosceles groove 29 on the annular valve disc 16... The outer right-angled isosceles ring 18 and the inner right-angled isosceles ring 21 are concentric. The maximum stroke of the annular valve disc 16 is L. The upper cover 17 is fixed to the mounting flange 2 at the upper end of the outer cover 9 in a sealed manner through the flange hole 5 and the threaded blind hole 3 with bolts 4. The distance between the upper cover 17 and the maximum stroke L is 50-100 mm. The central air inlet pipe 7 is fixed to the mounting flange 2 at the end of the air supply pipe 1 through the flange hole 5 and the threaded blind hole 3 on the bottom ring 6 with bolts 4. The air inlet chamber 27 is connected to the vacuum zone of the air supply pipe 1. The implementation is complete.

Claims

1. A right-angled isosceles air chamber type buffer double-inclined surface sealing constant pressure air supply device, characterized in that, in Four connecting and fixing ribs are used between the upper cover with a mounting flange and the lower central air intake pipe with a bottom ring. An outer sealing ring and an inner sealing ring are fixed on these ribs. The outer sealing ring is fixed to the inner surface of the outer cover in a sealing manner, and the inner sealing ring is fixed to the upper end of the central air intake pipe in a sealing manner. The inner surface of the outer cover and the outer surface of the central air intake pipe form an air intake ring, and the inner surface of the outer sealing ring and the outer surface of the inner sealing ring form a replenishing air ring. A right-angled isosceles ring with two sealing vertical rings below is inserted into the outer sealing ring groove on the outer sealing ring in a sealing manner. The bottom surface of the outer sealing ring groove and the inner sealing ring ring form a buffer air chamber; an inner right-angled isosceles ring with two sealing vertical rings below is installed in the inner sealing ring groove on the inner sealing ring in a sealing manner, and the two sealing vertical rings and the bottom surface of the inner sealing ring groove form a buffer air chamber; an outer right-angled isosceles groove and an inner right-angled isosceles groove are machined under the annular valve disc, and are concentric with the outer right-angled isosceles ring and the inner right-angled isosceles ring respectively. The right-angled surface of the outer right-angled isosceles groove is in sealing contact with the right-angled surface of the outer right-angled isosceles ring, and the right-angled surface of the inner right-angled isosceles groove is in sealing contact with the right-angled surface of the inner right-angled isosceles ring; through the anti-rotation beam The through holes and threaded blind holes on the fixing flange are used to bolt two anti-rotation shafts symmetrically fixed to the bottom of the crossbeam. The two anti-rotation shafts pass through the anti-rotation holes on the anti-rotation beam. The anti-rotation beam is fixed at the center of the central intake pipe. The anti-rotation shafts can slide freely up and down in the anti-rotation holes. The two ends of the crossbeam are fixed at the center of the annular valve disc. The top cover is fixed to the mounting flange on the upper end of the outer cover in a sealing manner. The stroke L is the maximum distance the annular valve disc is lifted. The maximum stroke L of the annular valve disc is 50-100 mm away from the top cover. The outer right-angle isosceles groove is shown in the table below. The lower surfaces of the inner right-angled isosceles groove and the outer and inner sealing rings respectively maintain a buffer distance of 5-20 mm. The total weight W of the annular valve disc, crossbeam, two anti-rotation shafts and fixing bolts must be balanced with the suction force generated by the reasonably designed vacuum threshold aMPa. W = S × aMPa, where S is the area of ​​the air replenishment ring, i.e., aMPa = W / S. The central air inlet pipe is fixed to the fixed flange at the end of the air replenishment pipe with bolts through the flange hole and threaded blind hole on the bottom ring. The air inlet chamber is connected to the vacuum zone of the air replenishment pipe.

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