Radial self-compensation main shaft working sealing structure of through-flow turbine with elastic rubber inlaid with carbon graphite material

Abstract

The invention discloses a radial self-compensation main shaft working sealing structure of a tubular turbine with elastic rubber inlaid with a carbon graphite material, which comprises a metal sealing seat provided with an active pressure water through hole, a composite water sealing gland matched with the metal sealing seat to form a rectangular-section ring groove, and a sealing ring accommodated in the rectangular-section ring groove, the sealing ring comprises an elastic rubber base body and a plurality of carbon graphite self-lubricating columns embedded in the sealing working ring face of the elastic rubber base body. The sealing working ring surface and a stainless steel anti-wear rotating ring assembled on the main shaft of the water turbine form a dynamic sealing pair; the sealing ring achieves the radial self-compensation sealing function under the action of active pressure water and rubber elastic force. According to the invention, the principle and good effect of active cleaning pressure water film sealing similar to water turbine main shaft piston type rubber end (flat) surface sealing can be realized, the effect similar to traditional multi-layer radial blocking combined carbon sealing pressure water active sealing can be realized, and the radial self-compensation pressure water film sealing device has the advantages of radial self-compensation capability, long wear resistance, long service life and the like.

Description

Technical Field

[0001] This invention pertains to turbine sealing technology, specifically a radial self-compensating main shaft working seal structure for a flow-through turbine with elastic rubber inlaid with carbon graphite material. Background Technology

[0002] For a long time, packing radial seals have been widely used as the main shaft working seals in axial flow turbines.

[0003] Packing seals are characterized by their simple structure and convenient adjustment and maintenance. For example... Figure 1 As shown, the traditional packing seal device 11 mainly includes a packing seal ring 4, a water-dividing I-beam ring 5 that cooperates with the packing seal ring 4, a metal sealing seat 6, a water-sealed metal gland 2, a leak-proof sealing ring 3 for the gland, and a pressure adjustment device 1. The water-sealed metal gland 2 is connected to the metal sealing seat 6 via the pressure adjustment device 1 (i.e., bolts). The metal sealing seat 6 and the water-sealed metal gland 2 together form a rectangular cross-section annular groove 12 for installing the packing seal ring 4 and the water-dividing I-beam ring 5. The metal sealing seat 6 is provided with an active pressure water supply hole 14 for introducing active pressure water 9. The water-sealed metal gland 2 is provided with a pressure-pressurizing cylindrical structure 2.1. The pressure-pressurizing cylindrical structure 2.1 has an annular plane 2.2 that cooperates with the packing seal ring 4. This sealing method has the characteristics of simple structure, low operating cost, and convenient on-site adjustment and maintenance. However, for bulb turbines operating on rivers with high sediment loads, especially those with large sediment loads during the annual flood season, the packing seal of the turbine's main shaft 8 has micro-gaps due to the fibrous nature of the packing strips (strips) used in the packing seal ring 4. This structure allows water containing fine sediment to easily penetrate, making the traditional packing seal ring 4 prone to wear during operation. It also causes severe wear damage to its mating component—the stainless steel anti-wear rotating ring 7. The accumulation of this damage affects the sealing effect, safety, and reliability.

[0004] Therefore, traditional packing seal devices 11 often require adjustment and compensation of the sealing tightness and capacity lost due to wear during operation through the clamping force adjustment device 1, and the packing seal needs to be replaced when necessary.

[0005] It is obvious that traditional packing seals have the disadvantages of requiring on-site maintenance personnel, consuming manpower, and having relatively low reliability.

[0006] Traditional packing seals are not conducive to the long-term, safe, and stable operation of bulb turbine units under minimal or no-person maintenance conditions, and hinder the advancement of unmanned remote management technology for power plants. Furthermore, the occasional need to be vigilant about potential drawbacks that could affect the long-term, stable, and safe operation of the turbine contradicts the goal of maximizing the economic benefits of power plants. Summary of the Invention

[0007] The purpose of this invention is to address the shortcomings of existing technologies by providing a radially self-compensating main shaft working seal structure for a axial-flow turbine with elastic rubber inlaid with carbon graphite material, which has radial self-compensation capability, long wear resistance and service life, and significantly improved operational reliability.

[0008] The technical objective of this invention is achieved through the following technical solution: A radial self-compensating main shaft working seal structure for a axial-flow turbine with elastic rubber inlaid with carbon graphite material is characterized by comprising a metal sealing seat with an active pressure water passage hole, a composite water seal cover that cooperates with the metal sealing seat to form a rectangular cross-section annular groove, and a sealing ring housed in the rectangular cross-section annular groove. The sealing ring comprises an elastic rubber matrix and multiple carbon graphite self-lubricating pillars inlaid on the sealing working ring surface of the elastic rubber matrix. The sealing working ring surface of the sealing ring forms a dynamic sealing pair with a stainless steel anti-wear rotating ring assembled on the turbine main shaft. The sealing ring achieves a radial self-compensating sealing function under the action of active pressure water and rubber elastic force.

[0009] Preferably, the elastic rubber matrix of the sealing ring is primarily made of HNBR hydrogenated nitrile butadiene rubber or NBR / PVC composite rubber. In practical applications, other types of rubber can also be selected as the material for the elastic rubber matrix of the sealing ring.

[0010] Preferably, the inner side of the sealing ring is provided with an annular water storage tank, and the outer side is provided with a pressurized water inlet annular groove. The annular water storage tank and the pressurized water inlet annular groove are connected by a water conveying hole, which is used to transport active pressurized water from the pressurized water inlet annular groove to the annular water storage tank.

[0011] Preferably, the cylindrical structure of the composite water seal cap has a friction-enhancing damping ring on its end ring plane.

[0012] Preferably, the friction-enhancing damping ring is an aluminum alloy ring with a high-damping material layer firmly bonded to the ring plane.

[0013] Compared with the prior art, the beneficial effects of the present invention are: 1. This invention can achieve the principle and good effect of active cleaning pressure water film sealing, which is similar to the piston-type rubber end (flat) surface seal of the turbine main shaft, and achieve the effect of active pressure water sealing, which is similar to the traditional multi-layer radial block combination carbon seal.

[0014] 2. This invention not only achieves automatic radial compensation of the sealing ring after wear on the sealing working surface, maintaining a good sealing state, but also significantly reduces the wear of the sealing element and its mating parts. It is particularly suitable for harsh water quality conditions such as high sediment content, greatly extending the service life of the sealing system. At the same time, this invention also effectively improves the sealing effect and reliability of the sealing structure, which is conducive to achieving less-manned, unmanned maintenance or remote management. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the axial cross-section of a traditional packing seal device; Figure 2 This is a schematic diagram of the mechanical structure of a traditional packing sealing device without the packing seal ring and the water distribution ring. Figure 3 This is a schematic cross-sectional view of the axial section of the present invention; Figure 4 yes Figure 3 Axial schematic diagram of the middle sealing ring; Figure 5 yes Figure 4 FF axial view; Figure 6 yes Figure 4 Q-direction view; Figure 7 yes Figure 4 E-direction view; Figure 8 This is a schematic diagram of a specific design example of the sealing ring of the present invention; Figure 9 This is a schematic diagram of the composite water seal cap of the present invention; Figure label: 1—Pressure force adjustment device; 2—Water-sealed metal cap; 2.1—Pressurized cylindrical structure; 2.2—Annular plane; 3—Leak-proof sealing ring; 4—Packing ring; 5—Water-dividing I-shaped ring; 6—Metal sealing seat; 7—Stainless steel wear-resistant swivel ring; 8—Water turbine main shaft; 9—Active pressurized water; 10—Water leakage in the turbine working chamber; 11—Traditional packing seal device; 12—Rectangular cross-section annular groove; 13—Sealing ring; 13.1—First sealing ring; 13.2—Second sealing ring; 13.3—Sealing working ring surface; 13.4—Annular water storage tank; 13.5—Water inlet hole; 13.6—Pressurized water inlet ring groove; 13.7—Carbon graphite self-lubricating column; 14—Active pressure water supply port; 16—The main shaft working sealing structure of this invention; 17—Sealed Operating System 19—Open-type butt joint; 20—Composite water seal gland; 20.1—Cylindrical structure; 20.2—End ring plane; 20.3—Friction-enhancing damping ring.

[0016] L—Axial height; S—Radial width. Detailed Implementation

[0017] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0018] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0019] It should be noted that similar reference numerals and letters in the following figures indicate similar items; therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures. Furthermore, the terms "first," "second," etc., are used only to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0020] like Figures 1-9As shown, a radial self-compensating main shaft working seal structure for a through-flow turbine, featuring elastic rubber inlaid with carbon graphite material, includes a metal sealing seat 6 with an active pressure water passage 14, a composite water seal cover 20 that mates with the metal sealing seat 6 to form a rectangular cross-section annular groove 12, and a sealing ring 13 housed within the rectangular cross-section annular groove 12. The sealing ring 13 includes an elastic rubber matrix and multiple carbon graphite self-lubricating pillars 13.7 embedded in the sealing working ring surface 13.3 of the elastic rubber matrix. The sealing working ring surface 13.3 of the sealing ring 13 forms a dynamic sealing pair with a stainless steel anti-wear rotating ring 7 mounted on the turbine main shaft 8. The sealing ring 13 achieves radial self-compensating sealing under the action of active pressure water 9 and the elastic force of the rubber. By utilizing the water pressure of the active pressure water 9 and the elasticity of the rubber material of the sealing ring 13, a dual guarantee of sealing power is achieved. When the sealing working surface 13.3 wears, the system can automatically and continuously push the sealing ring radially to compensate for the wear gap, ensuring that the sealing surface is always in close contact with the stainless steel anti-wear rotating ring 7. This completely changes the traditional packing seal model that relies on manual periodic tightening and adjustment, achieving automatic maintenance of the sealing effect and significantly improving the reliability and durability of the seal.

[0021] The sealing ring 13 has multiple carbon graphite self-lubricating pillars 13.7 embedded in its working ring surface. Carbon graphite material possesses excellent self-lubricating properties and wear resistance, forming a lubricating film on the friction pair surface, effectively reducing the coefficient of friction. This not only significantly reduces the wear of the sealing ring itself but also effectively protects the mating stainless steel anti-wear rotating ring 7 from damage. Its integral rubber structure fundamentally eliminates the drawbacks of fiber-woven packing that easily allows silt to seep in, making it particularly suitable for harsh working conditions in silty rivers, significantly extending its service life. Combining the advantages of self-compensation, wear resistance, and low maintenance, this sealing structure ensures long-term, trouble-free, and stable operation of the turbine main shaft, reducing unplanned downtime caused by seal failure.

[0022] In practical implementation, the metal sealing seat 6 and the composite water seal gland 20 are detachably connected via a clamping force adjusting device 1. The composite water seal gland 20 and the metal sealing seat 6, when combined, form a rectangular cross-section annular groove 12. A sealing ring 13 is housed within the rectangular cross-section annular groove 12. The radially outer annular surface of the sealing ring 13 fits against the groove wall of the rectangular cross-section annular groove 12; the radially inner annular surface of the sealing ring 13 forms a sealing working annular surface 13.3 that mates with the stainless steel anti-wear rotating ring 7.

[0023] In actual use, the sealing ring 13 in this invention is a sealing ring that only moves slightly intermittently along the annular groove 12 in the rectangular cross-section and can move radially self-compensatingly, without special mechanical positioning.

[0024] During operation, the sealing ring 13 is stably pushed towards the stainless steel anti-wear rotating ring 7 under the combined action of the elastic force of its own rubber material and the active pressure water 9, thereby forming a continuous and stable radial clamping force on its sealing working ring surface 13.3, realizing a reliable spindle dynamic sealing function, and achieving full sealing and radial running-in self-compensation.

[0025] like Figure 8 As shown, the sealing ring 13 is formed by splicing two parts along the axial direction. In this embodiment, the sealing ring 13 consists of two sealing rings arranged along the axial direction and having a mating joint 19.

[0026] Specifically, the sealing ring 13 includes a first sealing ring 13.1 and a second sealing ring 13.2; each of the first sealing ring 13.1 and the second sealing ring 13.2 has multiple carbon graphite self-lubricating pillars 13.7 evenly distributed along the circumference on its respective sealing working ring surface. The carbon graphite (pillar) rods distributed and embedded on the sealing working ring surfaces of the two sealing rings not only function as solid self-lubricating materials, playing a role in lubricating and protecting the stainless steel rotating ring 7 by distributing graphite molecules on its own working surface, but also, due to their solid structure, can form a combined seal with elastic rubber in a heterogeneous material form, thus leveraging their respective advantages.

[0027] like Figure 8 As shown, the long side (i.e., the axial height) L1 of the rectangular cross-section sealing ring 13 is designed to be 54mm, based on successful cases of current hydraulic turbines, whether it is a piston-type hydraulic rubber end-face seal structure or a balanced end-face seal structure; the radial width S of the sealing ring 13 is designed to be 25mm; the sealing working ring surface 13.3 of the first sealing ring 13.1, the sealing working ring surface 13.3 of the second sealing ring 13.2, and the annular water storage groove 13.4 are evenly distributed among each other, and the axial height L of the entire sealing ring 13 is 18mm wide. (18:18:18).

[0028] The first sealing ring 13.1 and the second sealing ring 13.2 each have a carbon graphite solid lubricated graphite column with a diameter of 7 mm embedded on their respective ring surfaces at 30 mm intervals.

[0029] like Figure 9 As shown, the composite friction-enhancing damping ring 20.3 is on the end ring plane 20.2 of the cylindrical structure 20.1 of the composite water seal gland 20.

[0030] In practical implementation, the friction-enhancing damping ring 20.3 is an aluminum alloy ring with a high-damping material layer firmly bonded to its ring plane. This technique ensures that when the sealing ring 13 is pressed against the friction-enhancing damping ring 20.3 on the composite water seal cover 20 under water pressure during operation, it generates high frictional resistance, thus preventing the sealing ring 13 from rotating synchronously with the stainless steel anti-wear rotating ring 7 and thus avoiding damage to the sealing ring 13.

[0031] The sealing ring 13, relative to the mating stainless steel sealing ring 7, is theoretically capable of rotating under sufficiently large external forces because there is no mechanical limit to its rotation direction in the design. In practice, referring to some turbine piston-type rubber end face seals without rotation positioning mechanical structures, due to the pressure of the leaking water 10 in the turbine working chamber and the action of the active sealing pressure water 14, the rubber of the sealing ring 13 deforms and adheres tightly to the annular plane of the friction resistance strengthening damping ring 20.3 on the composite water seal metal pressure cover 20 structure. Due to the high friction coefficient of the rubber and the anti-slip high friction resistance characteristics of the friction resistance strengthening damping ring, the sealing ring 13 can be guaranteed not to rotate with the stainless steel anti-wear ring 7 during operation.

[0032] like Figures 2-9 As shown, the inner side of the sealing ring 13 is provided with an annular water storage tank 13.4, and the outer side is provided with a pressurized water inlet annular groove 13.6. The annular water storage tank 13.4 and the pressurized water inlet annular groove 13.6 are connected by a water supply hole 13.5, which is used to transport the active pressurized water 9 from the pressurized water inlet annular groove 13.6 to the annular water storage tank 13.4.

[0033] In specific implementation, the sealing ring 13 also has an annular water storage tank 13.4 for conveying active pressure water 9 to the sealing working ring surface 13.3, a water supply hole structure 13.5 for conveying active pressure water 9 to the annular water storage tank 13.4, and an annular groove structure 13.6 for storing active pressure water 9 supplied by the active pressure water supply hole 14 on the metal sealing seat 6 structure.

[0034] The elastic rubber matrix of the sealing ring 13 is mainly made of HNBR hydrogenated nitrile butadiene rubber or NBR / PVC composite rubber. In practical applications, other types of rubber can also be selected as the material for the elastic rubber matrix of the sealing ring 13.

[0035] The elastic rubber matrix is ​​made of NBR / PVC (nitrile butadiene rubber / polyvinyl chloride) rubber-plastic composite material or HNBR hydrogenated nitrile butadiene rubber, which has been practically proven to be a specially formulated material. In actual operation, both HNBR hydrogenated nitrile butadiene rubber and NBR / PVC composite rubber exhibit good tensile and retraction elasticity and strength, low wear characteristics, and the ability to not damage the stainless steel anti-wear ring. They also exhibit low frictional heat generation under occasional contact conditions, thus preventing seal burn-out.

[0036] The sealing system 17 consists of a composite structure elastic self-compensating sealing ring 13, a metal sealing seat 6, and a composite water seal gland 20. The sealing system 17 cooperates with the stainless steel anti-wear rotating ring 7 mounted on the turbine main shaft 8 to jointly achieve the radial dynamic sealing function of the main shaft. This technology provides radial self-compensation capability, long wear-resistant life, and effectively improves the sealing effect and reliability, facilitating minimal or no-person maintenance or remote management.

[0037] With its outstanding advantages of self-compensation, wear resistance, and low maintenance, this invention can ensure the long-term, stable, and trouble-free operation of the turbine main shaft, significantly reducing unplanned downtime caused by seal failure. This not only directly improves the power generation efficiency and availability of the unit, but also promotes the modernization and intelligent management of hydropower stations, especially bulb turbine units, from "manned operation" to "less manned or even unmanned operation," resulting in significant economic benefits and technological advancements.

[0038] The technical solutions provided by the embodiments of the present invention have been described in detail above. Specific examples have been used to illustrate the principles and implementation methods of the embodiments of the present invention. The descriptions of the embodiments above are only for helping to understand the principles of the embodiments of the present invention. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the embodiments of the present invention. Therefore, the content of this specification should not be construed as a limitation of the present invention.

Claims

1. A radial self-compensating main shaft working seal structure of a through-flow water turbine with an elastic rubber inlaid carbon graphite material, characterized in that, The metal sealing seat (6) is provided with a main pressure water through hole (14), a composite water seal cover (20) is matched with the metal sealing seat (6) to form a rectangular cross-section ring groove (12), a sealing ring (13) is accommodated in the rectangular cross-section ring groove (12), The sealing ring (13) comprises an elastic rubber base and a plurality of carbon graphite self-lubricating columns (13.7) inlaid on a sealing working ring surface (13.3) of the elastic rubber base; the sealing working ring surface (13.3) of the sealing ring (13) forms a dynamic sealing pair with a stainless steel wear-resistant rotating ring (7) assembled on a water turbine main shaft (8). The sealing ring (13) realizes radial self-compensation sealing function under the action of the active pressure water (9) and the rubber elastic force.

2. The radial self-compensating main shaft working seal structure of the tubular turbine according to claim 1, characterized in that: The material of the elastic rubber base of the sealing ring (13) is mainly HNBR hydrogenated nitrile rubber or NBR / PVC composite material rubber.

3. The radial self-compensating main shaft working seal structure of tubular turbine according to claim 1, characterized in that: The inner side of the sealing ring (13) is provided with an annular water storage groove (13.4), and the outer side is provided with a pressure water inlet ring groove (13.6); the annular water storage groove (13.4) and the pressure water inlet ring groove (13.6) are communicated through a water delivery hole (13.5), which is used for conveying the active pressure water (9) from the pressure water inlet ring groove (13.6) to the annular water storage groove (13.4).

4. The radial self-compensating main shaft working seal structure of tubular turbine according to claim 1, characterized in that: The end ring plane (20.2) of the cylindrical structure (20.1) of the composite water seal cover (20) is compounded with a friction force enhancing damping ring (20.3).

5. The radial self-compensating main shaft working seal structure of tubular turbine according to claim 4, characterized in that: The friction force enhancing damping ring (20.3) is an aluminum alloy ring with a high damping material layer firmly compounded on the ring plane.

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