Combined steam seal at shaft end of steam turbine

Abstract

The invention discloses a steam turbine shaft end combined steam seal which comprises an air cylinder body and a rotor shaft, the rotor shaft is rotationally installed in the air cylinder body, the steam turbine shaft end steam seal further comprises threaded teeth, the threaded teeth are arranged on the rotor shaft, the two sections of threaded teeth are arranged on the rotor shaft, and the pumping effect is formed by disturbing airflow through the threaded teeth; the comb teeth are arranged on the rotor shaft, the comb teeth are located between the two sections of threaded teeth, and a throttling effect is formed through small gaps between the comb teeth and the rotor shaft; the first centrifugal disc and the second centrifugal disc are fixedly mounted on the rotor shaft, and centrifugal disc grooves are formed in the first centrifugal disc and the second centrifugal disc; by adopting the synergistic effect of multiple seals and combining centrifugal interception, threaded pumping, comb throttling and friction sealing, the steam leakage amount of the shaft end is remarkably reduced, the efficiency of the steam turbine is improved, meanwhile, the degradation risk of lubricating oil is reduced, and the operation safety of a unit is enhanced.

Description

Technical Field

[0001] The invention relates to the technical field of steam turbine shaft end seals, in particular to a steam turbine shaft end combined steam seal. Background Art

[0002] my country's power industry, the foundation of the national economy, remains primarily based on thermal power generation, with a total installed capacity of 1.36 billion kilowatts. Steam turbines, the core equipment of thermal power units, have a direct impact on the economics of coal combustion. Seal leakage is a key factor limiting efficiency improvements, causing not only a 3% to 4% loss in efficiency but also lubricant degradation and component corrosion, threatening unit safety. Therefore, the development of high-efficiency seal technology is crucial.

[0003] Existing steam seals have obvious limitations: the traditional labyrinth type requires a long shaft seal section and has redundant structure; the brush wires of the brush seal are severely worn after long-term operation and need to be replaced frequently; the improved honeycomb or composite steam seals are complex to process and costly, and need to be replaced as a whole after wear, which is unbearable for small and medium-sized units. These defects make it difficult to strike a balance between sealing effect and economy. A new structure is urgently needed to solve the contradiction between steam leakage loss and maintenance cost. For this purpose, a combined steam seal at the shaft end of the turbine is proposed. Summary of the Invention

[0004] To address the problems of traditional labyrinth seals requiring long shaft seal sections, brush seals rapidly wearing out and requiring frequent replacement, and complex composite seals with high processing costs and the need for complete replacement after wear, the present invention provides a combined turbine shaft-end seal. This seal utilizes multiple seal synergies and a buffer-compensating design to improve sealing efficiency while maintaining a compact structure and economical maintenance, adapting to the needs of various units.

[0005] In order to achieve the above-mentioned purpose, the present invention specifically adopts the following technical solutions: The turbine shaft end combined steam seal comprises a cylinder body and a rotor shaft, wherein the rotor shaft is rotatably mounted in the cylinder body, and is characterized in that the turbine shaft end steam seal further comprises: Threaded teeth are provided on the rotor shaft, and the threaded teeth are provided in two sections on the rotor shaft, and the threaded teeth disturb the airflow to form a pumping effect; The comb teeth are provided on the rotor shaft and are located between two sections of thread teeth. The throttling effect is formed by the small gap between the comb teeth and the rotor shaft. The first centrifugal disc and the second centrifugal disc are fixedly mounted on the rotor shaft. The first centrifugal disc and the second centrifugal disc are both provided with centrifugal disc grooves. When the rotor shaft rotates, a strong centrifugal force is generated through the centrifugal disc grooves to throw out the steam in the cylinder. Graphite ring, which is fixedly mounted on the rubber sleeve and frictionally contacts the back of the second centrifugal disc to form a contact seal; The rubber sleeve is fixedly installed in the cylinder body. A spring is fixedly installed on the rubber sleeve. The rubber sleeve uses its own elasticity to clamp and buffer the graphite ring.

[0006] Preferably, the thread teeth and comb teeth are arranged between the first centrifugal disk and the second centrifugal disk.

[0007] Preferably, a spring base is fixedly mounted on the rubber sleeve, and one end of the spring is fixedly mounted on the spring base.

[0008] Preferably, the graphite ring is tightly embedded in the end of the rubber sleeve away from the spring base, and the end of the spring away from the spring base is against the graphite ring through the rubber sleeve.

[0009] Preferably, the rotor shaft, the first centrifugal disc, the second centrifugal disc, the threaded teeth and the comb teeth are coaxially arranged, and the rotor shaft, the first centrifugal disc, the threaded teeth and the comb teeth are integrally assembled in a sealed cavity formed in the cylinder body.

[0010] Preferably, the cross section of the centrifugal disc grooves is arc-shaped, and the centrifugal disc grooves are circumferentially distributed on the first centrifugal disc and the second centrifugal disc.

[0011] Preferably, the thread rotation direction of the thread teeth is the same as the rotation direction of the rotor shaft during operation.

[0012] Preferably, the rubber sleeve body is in the shape of a bellows that can be stretched and compressed, and the rubber sleeve can be expanded and contracted along the axis direction of the rotor shaft through the bellows body structure.

[0013] The beneficial effects of the present invention are as follows: By adopting the synergistic effect of multiple seals, through the combination of centrifugal interception, thread pumping, comb throttling and friction seals, the steam leakage at the shaft end is significantly reduced, the efficiency of the turbine is improved, the risk of lubricating oil deterioration is reduced, and the operating safety of the unit is enhanced.

[0014] The rubber sleeve bellows structure and the spring form a buffer compensation mechanism, which can adapt to rotor vibration and component wear, extend the service life of the seal, reduce maintenance frequency, and adapt to complex working conditions for long-term stable operation.

[0015] The structural design takes into account both adaptability and economy. Through modular integration of centrifugal discs, threaded teeth and other components, it can adapt to turbines with different parameters without large-scale modification of the unit. The processing technology is simple, reducing manufacturing and installation costs. It is especially suitable for the upgrade and modification of small and medium-sized units or low-parameter steam turbines. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a schematic diagram of the cross-sectional structure of the present invention; Figure 2It is a structural schematic diagram of the rotor shaft and the first centrifugal disk and other structures of the present invention; Figure 3 This is a schematic diagram of the structure of the rotor shaft and thread teeth of the present invention; Figure 4 It is a structural schematic diagram of the rubber sleeve and spring structures of the present invention; Figure 5 It is a structural schematic diagram of the first centrifugal disk and centrifugal disk slots of the present invention.

[0017] Figure numerals: 1. first centrifugal disc; 2. rotor shaft; 3. threaded teeth; 4. comb teeth; 5. second centrifugal disc; 6. cylinder body; 7. graphite ring; 8. spring; 9. rubber sleeve; 10. spring base; 11. centrifugal disc groove. DETAILED DESCRIPTION

[0018] To make the objectives, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings herein can be arranged and designed in various different configurations.

[0019] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention as claimed, but rather merely represents selected embodiments of the present invention. All other embodiments derived by persons of ordinary skill in the art based on the embodiments of the present invention without creative effort shall fall within the scope of protection of the present invention.

[0020] It should be noted that similar reference numerals and letters represent similar items in the following drawings. Therefore, once an item is defined in one drawing, it does not need to be further defined or explained in subsequent drawings. In addition, the terms "first," "second," etc. are used only to distinguish the descriptions and are not to be understood as indicating or implying relative importance.

[0021] The electrical components mentioned in this article are all connected to an external main controller and 220V AC power, and the main controller can be a conventional known device that performs control such as a computer.

[0022] In the description of the embodiments of the present invention, it should be noted that the terms "inside", "outside", "upper", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, or are the orientations or positional relationships in which the inventive product is usually placed when in use. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, they cannot be understood as limitations on the present invention.

[0023] Example: Refer to Figures 1 to 5 The turbine shaft end combined steam seal includes a cylinder body 6 and a rotor shaft 2. The rotor shaft 2 is rotatably mounted in the cylinder body 6, forming an annular gap between the two. Steam is easily leaked from this gap. To prevent leakage, the turbine shaft end steam seal also includes: Thread teeth 3 are provided on the rotor shaft 2, and the thread teeth 3 are provided in two sections on the rotor shaft 2. The thread teeth 3 disturb the airflow to form a pumping effect; Comb teeth 4 are provided on the rotor shaft 2 and are located between two sections of thread teeth 3. A throttling effect is formed by a small gap between the comb teeth 4 and the rotor shaft 2. The first centrifugal disc 1 and the second centrifugal disc 5 are fixedly mounted on the rotor shaft 2. The first centrifugal disc 1 and the second centrifugal disc 5 are each provided with a centrifugal disc groove 11. The centrifugal disc groove 11 can generate a strong centrifugal force when the rotor shaft 2 rotates, thereby throwing out the steam in the cylinder. Graphite ring 7, which is fixedly mounted on the rubber sleeve 9, and frictionally contacts the back of the second centrifugal disc 5 to form a contact seal; The rubber sleeve 9 is fixedly installed in the cylinder body 6. A spring 8 is fixedly installed on the rubber sleeve 9. The rubber sleeve 9 uses its own elasticity to clamp and buffer the graphite ring 7.

[0024] To ensure a good steam seal, the thread teeth 3 and comb teeth 4 are positioned between the first centrifugal disc 1 and the second centrifugal disc 5. A spring base 10 is fixedly mounted on the rubber sleeve 9, with one end of the spring 8 fixedly mounted on the spring base 10. A graphite ring 7 is tightly fitted into the end of the rubber sleeve 9 away from the spring base 10, with the end of the spring 8 abutting against the graphite ring 7 via the rubber sleeve 9. The rotor shaft 2, the first centrifugal disc 1, the second centrifugal disc 5, the thread teeth 3, and the comb teeth 4 are coaxially arranged and integrally assembled within the sealed cavity formed within the cylinder body 6. The centrifugal disc grooves 11 have an arcuate cross-section and are distributed circumferentially around the first and second centrifugal discs 1 and 5. The thread rotation of the thread teeth 3 is the same as the rotation direction of the rotor shaft 2 during operation. The rubber sleeve 9 is constructed in an expandable and compressible bellows-like structure, allowing the rubber sleeve 9 to expand and contract along the axis of the rotor shaft 2.

[0025] Two centrifugal discs are welded or interlocked to the rotor shaft 2 and rotate at high speed with it. When the turbine starts, the first centrifugal disc 1 takes over. The centrifugal disc grooves 11 on its surface generate strong centrifugal force during high-speed rotation, radially ejecting steam from the cylinder inner wall 6. This significantly reduces the amount of steam that might otherwise enter subsequent sealing gaps, forming the first highly effective interception barrier.

[0026] After passing through the first interception, the residual steam continues to flow outward. At this time, two sections of threaded teeth 3 directly machined onto the rotor shaft 2 begin to intervene. The threaded teeth 3 are designed to be left-handed or right-handed according to the rotation direction of the rotor shaft 2. When the shaft rotates at high speed, its spiral structure forms a "pump" effect, which not only actively pumps the steam entering the gap out of the sealing area along the axial direction to reduce steam accumulation, but also strongly disturbs the steam flow through high-speed rotation, destroying its orderly flow state, increasing flow resistance, and forming a second sealing line of defense.

[0027] After the action of the threaded teeth 3, a section of comb teeth 4 structure further enhances the sealing effect: the tiny gap between the comb teeth 4 and the rotor shaft 2 forms a throttling effect. When residual steam tries to pass through, a pressure difference will be generated before and after the comb teeth 4. When the steam flows through the gap, throttling and pressure reduction occur, and the pressure and flow rate change significantly. The leakage amount per unit time is further reduced, which acts as an intermediate link to continuously weaken the leakage power of steam.

[0028] After passing through the first three seals, a small amount of steam continues to diffuse outward. This is when the second centrifugal disc 5 comes into play: the centrifugal force generated by its high-speed rotation again throws the remaining steam out radially along the groove. At the same time, its backside provides the critical contact surface for the final seal. The graphite ring 7, embedded in the rubber sleeve 9, fits tightly against the back friction surface of the centrifugal disc 5 under the elastic force of spring 8. Due to the excellent lubricity and wear resistance of the graphite ring 7, the two form a close dynamic friction contact when the centrifugal disc 5 rotates at high speed, completely blocking the steam leakage path and forming the final sealing guarantee.

[0029] It is worth noting that the rubber sleeve 9 uses its own elasticity to clamp and buffer the graphite ring 7, and one end of the spring 8 abuts against the spring base 10, continuously providing pressure to the graphite ring 7; when the rotor shaft 2 vibrates due to operation or the graphite ring 7 is worn, the elastic force of the spring 8 and the elastic deformation of the rubber sleeve 9 can compensate for the gap change in time, always maintaining the sealing pressure between the graphite ring 7 and the centrifugal disk 5, ensuring that the entire sealing system remains stable and efficient during long-term operation, which not only significantly reduces steam leakage losses but also extends the service life of components.

[0030] Working Principle: Two centrifugal discs are welded or interlocked to the rotor shaft 2 and rotate at high speed with it. When the turbine starts, the first centrifugal disc 1 takes over. The centrifugal disc grooves 11 on its surface generate strong centrifugal force during high-speed rotation, radially ejecting steam from the cylinder inner wall 6. This significantly reduces the amount of steam that might otherwise enter the subsequent sealing gaps, forming the first highly effective interception barrier.

[0031] After passing through the first interception, the residual steam continues to flow outward. At this time, two sections of threaded teeth 3 directly machined onto the rotor shaft 2 begin to intervene. The threaded teeth 3 are designed to be left-handed or right-handed according to the rotation direction of the rotor shaft 2. When the shaft rotates at high speed, its spiral structure forms a "pump" effect, which not only actively pumps the steam entering the gap out of the sealing area along the axial direction to reduce steam accumulation, but also strongly disturbs the steam flow through high-speed rotation, destroying its orderly flow state, increasing flow resistance, and forming a second sealing line of defense.

[0032] After the action of the threaded teeth 3, a section of comb teeth 4 structure further enhances the sealing effect: the tiny gap between the comb teeth 4 and the rotor shaft 2 forms a throttling effect. When residual steam tries to pass through, a pressure difference will be generated before and after the comb teeth 4. When the steam flows through the gap, throttling and pressure reduction occur, and the pressure and flow rate change significantly. The leakage amount per unit time is further reduced, which acts as an intermediate link to continuously weaken the leakage power of steam.

[0033] After passing through the first three seals, a small amount of steam continues to diffuse outward. This is when the second centrifugal disc 5 comes into play: the centrifugal force generated by its high-speed rotation again throws the remaining steam out radially along the groove. At the same time, its backside provides the critical contact surface for the final seal. The graphite ring 7, embedded in the rubber sleeve 9, fits tightly against the back friction surface of the centrifugal disc 5 under the elastic force of spring 8. Due to the excellent lubricity and wear resistance of the graphite ring 7, the two form a close dynamic friction contact when the centrifugal disc 5 rotates at high speed, completely blocking the steam leakage path and forming the final sealing guarantee.

[0034] It is worth noting that the rubber sleeve 9 uses its own elasticity to clamp and buffer the graphite ring 7, and one end of the spring 8 abuts against the spring base 10, continuously providing pressure to the graphite ring 7; when the rotor shaft 2 vibrates due to operation or the graphite ring 7 is worn, the elastic force of the spring 8 and the elastic deformation of the rubber sleeve 9 can compensate for the gap change in time, always maintaining the sealing pressure between the graphite ring 7 and the centrifugal disk 5, ensuring that the entire sealing system remains stable and efficient during long-term operation, which not only significantly reduces steam leakage losses but also extends the service life of components.

[0035] The above shows and describes the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The above embodiments and descriptions merely illustrate the principles of the present invention. Various changes and modifications may be made to the present invention without departing from the spirit and scope of the present invention. Such changes and modifications are intended to fall within the scope of the present invention. The scope of protection claimed by the present invention is defined by the appended claims and their equivalents.

Claims

1. A steam turbine shaft end combined steam seal, comprising a cylinder body (6) and a rotor shaft (2), wherein the rotor shaft (2) is rotatably mounted in the cylinder body (6), and is characterized in that: The turbine shaft end steam seal further comprises: Threaded teeth (3), the threaded teeth (3) are provided on the rotor shaft (2), and the threaded teeth (3) are provided with two sections on the rotor shaft (2), and the threaded teeth (3) disturb the airflow to form a pumping effect; Comb teeth (4), the comb teeth (4) are provided on the rotor shaft (2), and the comb teeth (4) are located between two sections of thread teeth (3), and a throttling effect is formed through a small gap between the comb teeth (4) and the rotor shaft (2); A first centrifugal disc (1) and a second centrifugal disc (5), both of which are fixedly mounted on the rotor shaft (2), and each of which is provided with a centrifugal disc groove (11). The centrifugal disc groove (11) can generate a strong centrifugal force when the rotor shaft (2) rotates, thereby throwing out the steam in the cylinder; A graphite ring (7), the graphite ring (7) is fixedly mounted on the rubber sleeve (9), and the graphite ring (7) is in frictional contact with the back surface of the second centrifugal disc (5) to form a contact seal; A rubber sleeve (9) is fixedly mounted in the cylinder body (6). A spring (8) is fixedly mounted on the rubber sleeve (9). The rubber sleeve (9) utilizes its own elasticity to clamp and buffer the graphite ring (7).

2. The turbine shaft end combined steam seal according to claim 1, characterized in that: The thread teeth (3) and the comb teeth (4) are arranged between the first centrifugal disc (1) and the second centrifugal disc (5).

3. The turbine shaft end combined steam seal according to claim 1, characterized in that: A spring base (10) is fixedly mounted on the rubber sleeve (9), and one end of the spring (8) is fixedly mounted on the spring base (10).

4. The turbine shaft end combined steam seal according to claim 3, characterized in that: The graphite ring (7) is tightly embedded in the end of the rubber sleeve (9) away from the spring base (10), and the end of the spring (8) away from the spring base (10) is against the graphite ring (7) through the rubber sleeve (9).

5. The turbine shaft end combined steam seal according to claim 1, characterized in that: The rotor shaft (2), the first centrifugal disc (1), the second centrifugal disc (5), the threaded teeth (3) and the comb teeth (4) are coaxially arranged, and the rotor shaft (2), the first centrifugal disc (1), the threaded teeth (3) and the comb teeth (4) are integrally assembled in a sealed cavity formed in the cylinder body (6).

6. The turbine shaft end combined steam seal according to claim 1, characterized in that: The cross section of the centrifugal disc grooves (11) is arc-shaped, and the centrifugal disc grooves (11) are circumferentially distributed on the first centrifugal disc (1) and the second centrifugal disc (5).

7. The turbine shaft end combined steam seal according to claim 1, characterized in that: The thread rotation direction of the thread teeth (3) is the same as the rotation direction of the rotor shaft (2) during operation.

8. The turbine shaft end combined steam seal according to claim 1, characterized in that: The rubber sleeve (9) has a bellows-like body that is expandable and compressible, and the rubber sleeve (9) can expand and contract along the axis direction of the rotor shaft (2) through the bellows-like body structure.

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