A combined main shaft seal structure for bulb-type cross-flow turbine units

Abstract

This utility model discloses a combined main shaft sealing structure for a bulb-type axial flow turbine unit, including a guide cone, a rotating ring, and a water seal cover. The guide cone is fixed to the fixed end of the unit, and the water seal cover is fitted onto the outside of the guide cone. A labyrinth sealing ring and a rubber sealing plate are sequentially arranged between the guide cone and the rotating ring. The labyrinth sealing ring is connected to the guide cone, and a pressure ring is provided on the guide cone. This utility model achieves contactless sealing through the setting of the labyrinth sealing ring, air shroud, etc., and is not affected by the axial movement of the unit, reducing seal wear. The adjustment of the ring ceramic coating process and the coordination of the self-lubricating water film greatly enhances the wear resistance of the rubber sealing plate, significantly reducing the replacement frequency. The use of a self-lubricating water flow channel eliminates the need for external main shaft sealing water, reducing water leakage. Furthermore, when the rubber sealing plate needs to be replaced, the air shroud allows for replacement without draining the unit, significantly reducing maintenance costs and repair workload.

Description

Technical Field

[0001] This utility model relates to the field of water conservancy and hydropower equipment technology, specifically a combined main shaft sealing structure for a bulb-type turbine generator set. Background Technology

[0002] Bulb-type axial-flow turbine generator sets are widely used in low-head water conservancy and hydropower projects due to their compact structure and strong flow capacity. The main shaft seal is the core component that ensures the safe operation of the unit. The existing main shaft seal structure adopts a combination of air-sealed maintenance seal and packing seal as the working seal. The working seal consists of a rotating ring, guide cone, radial packing seal, I-ring, sealing gland, water tank, etc. The radial packing seal material is four 19X19 PTFE braided packings. A gasket I-ring is placed in the middle of the four packings to ensure smooth flow of lubricating water. Water stoppage is achieved by compressing the braided packings to form a sealing surface.

[0003] The above-mentioned prior art has the following problems:

[0004] (1) The seal is prone to failure: the interface of the PTFE braided packing is prone to cracking, which leads to the packing becoming loose and misaligned, and the leakage gradually increases. The misaligned packing will wear down the swivel ring. The severely worn swivel ring will further shear and twist the packing, causing the packing to break and fail, resulting in a high frequency of replacement.

[0005] (2) Difficult to maintain: The seal cannot be used normally during maintenance. Replacing the packing requires stopping the machine and closing the inlet and tailwater gates. The water in the flow channel must be drained before the maintenance can be carried out, resulting in a long maintenance period.

[0006] (3) High economic losses: Frequent shutdowns for maintenance not only increase spare parts and labor costs, but also cause unnecessary power loss, affecting the economic benefits of the power plant.

[0007] Therefore, it is necessary to propose a combined spindle sealing structure for bulb-type turbine units to solve or at least alleviate the above-mentioned defects. Utility Model Content

[0008] The purpose of this utility model is to provide a combined main shaft sealing structure for a bulb-type cross-flow unit to solve the problems mentioned in the background art.

[0009] To achieve the above objectives, this utility model provides the following technical solution: a combined main shaft sealing structure for a bulb-type flow-through unit, comprising a guide cone, a rotating ring, and a water seal cover. The guide cone is fixed to the fixed end of the unit, and the water seal cover is fitted onto the outside of the guide cone. A labyrinth sealing ring and a rubber sealing plate are sequentially provided between the guide cone and the rotating ring. The labyrinth sealing ring is connected to the guide cone, and a pressure ring is provided on the guide cone. The rubber sealing plate is positioned by the pressure ring, and an adjusting ring is attached to the rubber sealing plate. The adjusting ring is connected to the rotating ring and rotates synchronously. An air shroud is provided between the labyrinth sealing ring and the rubber sealing plate. The water seal cover is connected to a water collection well for collecting leaked water and lubricating water after sealing.

[0010] Furthermore, the labyrinth sealing ring is provided with a set of sequentially arranged annular sealing teeth, an expansion cavity is formed between adjacent annular sealing teeth, and a throttling gap is formed between the annular sealing teeth and the inner wall of the rotating ring.

[0011] Furthermore, the mating surface of the adjusting ring is treated with a ceramic coating process, and a self-lubricating water film is formed between the rubber sealing plate and the mating surface of the adjusting ring.

[0012] Furthermore, the pressure ring is threaded onto the guide cone, and the fitting gap between the rubber sealing plate and the adjusting ring is adjusted by rotating the pressure ring.

[0013] Compared with the prior art, the beneficial effects of this utility model are:

[0014] (1) This utility model achieves contactless sealing by setting up labyrinth sealing rings, air shrouds, etc., and is not affected by the axial movement of the unit, reducing seal wear. By adjusting the ring ceramic plating process and the self-lubricating water film, the wear resistance of the rubber sealing plate is greatly enhanced, and the replacement frequency is greatly reduced. The flow channel water self-lubrication method is adopted, which does not require external supply of main shaft sealing water, reducing water leakage. Moreover, when the rubber sealing plate needs to be replaced, the air shroud can be used to replace it without draining the unit, which greatly reduces maintenance costs and maintenance workload. Attached Figure Description

[0015] Figure 1 Assembly of this utility model Figure 1 Schematic diagram of the side section structure;

[0016] Figure 2 This is a schematic diagram of the cross-sectional structure on the other side of the assembly drawing of this utility model.

[0017] The purpose, features, and advantages of this utility model will be further explained in conjunction with the embodiments and with reference to the accompanying drawings.

[0018] Explanation of icon numbers:

[0019] 1. Flow guide cone; 2. Water seal cover; 3. Adjusting ring; 4. Rubber sealing plate; 5. Labyrinth sealing ring; 6. Rotating ring; 7. Pressure ring; 8. Air shroud. Detailed Implementation

[0020] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0021] Example 1: Please refer to Figure 1-2 This utility model provides a technical solution: a combined main shaft sealing structure for a bulb-type flow-through unit, including a guide cone 1, a rotating ring 6, and a water seal cover 2. The guide cone 1 is fixed to the fixed end of the unit, and the water seal cover 2 is fitted onto the outside of the guide cone 1. A labyrinth sealing ring 5 and a rubber sealing plate 4 are sequentially arranged between the guide cone 1 and the rotating ring 6. The labyrinth sealing ring 5 is connected to the guide cone 1, and a pressure ring 7 is provided on the guide cone 1. The rubber sealing plate 4 is positioned by the pressure ring 7, and an adjusting ring 3 is attached to the rubber sealing plate 4. The adjusting ring 3 is connected to the rotating ring 6 and rotates synchronously. An air shroud 8 is provided between the labyrinth sealing ring 5 and the rubber sealing plate 4. The water seal cover 2 is connected to a water collection well for collecting leaked water and lubricating water after sealing.

[0022] After the unit starts, the water in the flow channel enters the gap between the labyrinth sealing ring 5 and the rotating ring 6. When the water flows through the throttling gap and expansion cavity formed by the four sets of annular sealing teeth, a throttling effect is generated, resulting in hydraulic loss. The water pressure in the flow channel drops from 0.1-0.2 MPa to below 0.1 MPa. The water leakage in the flow channel after pressure reduction acts on the rubber sealing plate 4, making the rubber sealing plate 4 tightly fit the ceramic-coated surface of the adjusting ring 3. At the same time, the leakage water forms a self-lubricating water film on the friction surface, reducing the friction and wear between the rubber sealing plate 4 and the adjusting ring 3. The residual leakage water and the self-lubricating water film after being sealed by the rubber sealing plate 4 flow into the interior of the water seal cover 2 and are introduced into the collection water through the drain port of the water seal cover 2. To prevent water from entering the water guide bearing, if the leakage increases during operation, the sealing effect can be restored by adjusting the pressure ring 7 to change the gap between the rubber sealing plate 4 and the adjusting ring 3. When the rubber sealing plate 4 needs to be replaced, there is no need to close the inlet and outlet gates or empty the drain channel. The leakage channel between the labyrinth sealing ring 5 and the rubber sealing plate 4 is blocked by the air enclosure 8. After removing the pressure ring 7, the failed rubber sealing plate 4 is removed, a new rubber sealing plate 4 is replaced, the pressure ring 7 is reinstalled, the gap between the rubber sealing plate 4 and the adjusting ring 3 is adjusted to ensure a tight fit, the air enclosure 8 is closed, the maintenance is completed, and the unit can resume operation, which greatly shortens the maintenance period.

[0023] Reference Figures 1-2 In this utility model, the labyrinth sealing ring 5 is provided with 4 sets of sequentially arranged annular sealing teeth, an expansion cavity is formed between adjacent annular sealing teeth, and a throttling gap is formed between the annular sealing teeth and the inner wall of the rotating ring 6.

[0024] When the water flows into the labyrinth sealing ring 5 and the rotating ring 6, it will generate throttling resistance when passing through the throttling gap, and when it reaches the expansion cavity, the water flow expands and the pressure decreases. Through this process, hydraulic loss is formed, so that the water flow pressure drops from the initial 0.1-0.2MPa to within 0.1MPa, thereby achieving pressure reduction and sealing, and providing conditions for the main seal of the subsequent rubber sealing plate 4.

[0025] Reference Figures 1-2 In this utility model, the mating surface of the adjusting ring 3 is treated with a ceramic coating process, and the mating surface of the rubber sealing plate 4 and the adjusting ring 3 forms a self-lubricating water film.

[0026] The mating surface of the adjusting ring 3 is treated with a ceramic coating process, which improves the smoothness and wear resistance of the contact surface and reduces the frictional loss when the rubber sealing plate 4 and the adjusting ring 3 rotate relative to each other. The self-lubricating water film formed on the mating surface of the rubber sealing plate 4 and the adjusting ring 3 is caused by the pressure of the water leakage in the flow channel, which makes the rubber plate stick tightly to the adjusting ring. The water film can further reduce friction. Together with the ceramic coating process, it extends the service life of the sealing structure and ensures the reliability of the seal.

[0027] Reference Figures 1-2 In this utility model, the pressure ring 7 is threaded onto the guide cone 1, and the fitting gap between the rubber sealing plate 4 and the adjusting ring 3 is adjusted by rotating the pressure ring 7.

[0028] The pressure ring 7 is connected to the guide cone 1 via a thread. This connection allows the pressure ring 7 to move axially along the thread. When the pressure ring 7 is rotated, it moves closer to or further away from the rubber sealing plate 4, thereby changing the clamping force on the rubber sealing plate 4. Ultimately, this adjusts the fit gap between the rubber sealing plate 4 and the adjusting ring 3, ensuring both sealing performance and ease of maintenance.

[0029] The working principle is as follows: After the unit starts, the water in the flow channel enters the gap between the labyrinth sealing ring 5 and the rotating ring 6. When the water flows through the throttling gap and expansion cavity formed by the four sets of annular sealing teeth, a throttling effect is generated, resulting in hydraulic loss. The water pressure in the flow channel drops from 0.1-0.2 MPa to below 0.1 MPa. The water leakage after pressure reduction acts on the rubber sealing plate 4, making the rubber sealing plate 4 tightly fit the ceramic-coated surface of the adjusting ring 3. At the same time, the leakage forms a self-lubricating water film on the friction surface, reducing the friction and wear between the rubber sealing plate 4 and the adjusting ring 3. The residual leakage and the self-lubricating water film after being sealed by the rubber sealing plate 4 flow into the interior of the water seal cover 2 and are led out through the drain port of the water seal cover 2. The water collection well is used to prevent water leakage into the water guide bearing. If the leakage increases during operation, the sealing effect can be restored by adjusting the pressure ring 7 to change the gap between the rubber sealing plate 4 and the adjusting ring 3. When the rubber sealing plate 4 needs to be replaced, there is no need to close the inlet and outlet gates or empty the drain channel. The leakage channel between the labyrinth sealing ring 5 and the rubber sealing plate 4 is blocked by the air enclosure 8. After removing the pressure ring 7, the failed rubber sealing plate 4 is removed, a new rubber sealing plate 4 is replaced, the pressure ring 7 is reinstalled, the gap between the rubber sealing plate 4 and the adjusting ring 3 is adjusted to ensure a tight fit, the air enclosure 8 is closed, the maintenance is completed, and the unit can resume operation, which greatly shortens the maintenance period.

[0030] The above are merely preferred embodiments of this utility model and do not limit the patent scope of this utility model. Any equivalent structural or procedural transformations made based on the description and drawings of this utility model, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of this utility model.

Claims

1. A combined main shaft sealing structure for a bulb-type axial-flow turbine unit, characterized in that, The system includes a guide cone (1), a rotating ring (6), and a water seal cover (2). The guide cone (1) is fixed to the fixed end of the unit. The water seal cover (2) is fitted on the outside of the guide cone (1). A labyrinth sealing ring (5) and a rubber sealing plate (4) are arranged between the guide cone (1) and the rotating ring (6). The labyrinth sealing ring (5) is connected to the guide cone (1). A pressure ring (7) is provided on the guide cone (1). The rubber sealing plate (4) is positioned by the pressure ring (7). An adjusting ring (3) is attached to the rubber sealing plate (4). The adjusting ring (3) is connected to the rotating ring (6) and rotates synchronously. An air shroud (8) is provided between the labyrinth sealing ring (5) and the rubber sealing plate (4). The water seal cover (2) is connected to the water collection well and is used to collect leaked water and lubricating water after sealing.

2. A combined main shaft seal for a bulb tubular turbine unit according to claim 1, characterized in that: The labyrinth sealing ring (5) is provided with 4 sets of sequentially arranged annular sealing teeth, an expansion cavity is formed between adjacent annular sealing teeth, and a throttling gap is formed between the annular sealing teeth and the inner wall of the rotating ring (6).

3. A combined main shaft seal for a bulb tubular turbine unit according to claim 2, characterized in that: The mating surface of the adjusting ring (3) is treated with a ceramic coating process, and the mating surface of the rubber sealing plate (4) and the adjusting ring (3) forms a self-lubricating water film.

4. A combined main shaft seal for a bulb tubular turbine unit according to claim 3, characterized in that: The pressure ring (7) is threaded onto the guide cone (1), and the fitting gap between the rubber sealing plate (4) and the adjusting ring (3) is adjusted by rotating the pressure ring (7).

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