Water turbine main shaft sealing device and water turbine

Abstract

The utility model discloses a water turbine main shaft sealing device and a water turbine. The sealing device comprises a main shaft and a sealing seat, a sealing block and a partition plate are arranged between the main shaft and the sealing seat, and the sealing block is annular, arranged outside the main shaft in a sleeving mode and moves along with the main shaft. The partition plate is located in the sealing seat and comprises a radial partition plate for isolating two adjacent sealing blocks, isolating the sealing blocks from the end face of the sealing seat and an axial partition plate for isolating the sealing seat from the side walls of the sealing blocks, the sealing blocks are in clearance fit with the radial partition plate, and the sealing blocks are in clearance fit with the axial partition plate; at least part of the external corner of the partition plate is beveled, and a sealing strip is arranged at the beveled position of the partition plate. During use, the sealing block is jacked up by water pressure, so that a complete sealing cavity is formed among the sealing block, the partition plate and the sealing strip; the sealing block is a rotating piece, the sediment is thrown out through centrifugal force formed by the sealing block and returns to the first seal, the sediment discharging effect is achieved, and the service life of the sealing device is effectively prolonged.

Description

Technical Field

[0001] The utility model relates to a dynamic sealing structure, in particular to a water turbine main shaft sealing device and also to a water turbine. Background Art

[0002] For water with high sediment content, pump and turbine main shaft seals generally use non-contact seals or mechanical seals. The non-contact seal is a pump plate plus gap seal structure, which is far away from the main shaft; the mechanical seal is a split mechanical seal with a sand discharge structure, which is close to the main shaft. The pump plate plus gap seal structure has a good sealing effect, but if the gap seal fails, especially during the flood season with high sediment content, the leakage rate will increase, and granular sediment will enter the mechanical seal, wearing the main shaft shaft guard and causing pits on the main shaft cylindrical surface. Water leakage will enter between the main shaft and the mechanical seal and seep into the pit. It may also cause water to enter the bearing, causing bearing wear, and ultimately causing the entire turbine generator set to stop operating, requiring repair of the entire rotating part.

[0003] The utility model patent application with publication number CN 203258066 U discloses a main shaft working seal device for a horizontal turbine. The main shaft seal is a packing seal. A drain pipe is provided on the sealing seat in front of the seal, and a retaining ring is provided at the rear. After the leaked water passes through the gap seal of the runner stop ring, it is decompressed and enters the pump plate centrifugal seal. The pump plate centrifugal seal is provided with several drain pipes. Most of the sediment and some of the water are discharged through the drain pipes. When the remaining leaked water enters the gap seal device, it generates resistance to overcome the leakage. A small amount of leaked water is discharged through the drain pipe for secondary sand removal and enters the packing seal. Finally, some of the leaked water is discharged through the drain pipe. The layers of sealing effectively control the leakage of sediment and water in the water turbine room. This solution cannot effectively prevent leaked sediment from entering the gap between the main shaft and the bearing / bearing shell. Utility Model Content

[0004] Purpose of the utility model: The purpose of the utility model is to provide a turbine main shaft sealing device that increases the service life in a sediment basin; another purpose of the utility model is to provide a turbine.

[0005] Technical solution: The utility model describes a turbine main shaft sealing device, comprising a main shaft and a sealing seat; a sealing block and a partition are provided between the main shaft and the sealing seat, the sealing block being annular, sleeved outside the main shaft, and moving with the main shaft; the partition is located inside the sealing seat, and comprises a radial partition for isolating two adjacent sealing blocks, isolating the sealing block and the end face of the sealing seat, and an axial partition for isolating the sealing seat and the side wall of the sealing block, and a clearance fit is formed between the sealing block and the radial partition, and between the sealing block and the axial partition; the outer corners of the partition are at least partially beveled, and a sealing strip is provided at the beveled portion of the partition.

[0006] Preferably, the outer wall of the sealing block is provided with a spiral groove, and the sealing block is fixed outside the main shaft through the groove and a spring.

[0007] Preferably, in order to protect the spindle shaft stop, the spindle outer shell is provided with a protective sleeve, and the protective sleeve is provided with an annular groove for installing a sealing block. The sealing block is fixed in the annular groove by a groove and a spring and can slide up and down along the annular groove.

[0008] Preferably, the outermost peripheries of the upper and lower side surfaces of the sealing block are provided with raised rings, and the raised rings are in contact with the surface of the radial partition.

[0009] Preferably, the gap between the sealing block and the radial partition is 1 to 1.5 mm.

[0010] Preferably, the gap between the sealing block and the axial partition is 2-3 mm.

[0011] Preferably, the number of the sealing blocks and partitions is the same, no less than 4.

[0012] Preferably, in order to increase the service life of the partition, the friction surface of the partition is provided with a tungsten carbide hard alloy coating.

[0013] Preferably, in order to ensure the service life of the sealing block, the material of the sealing block is polyester polyurethane.

[0014] A water turbine comprising the above-mentioned water turbine main shaft sealing device.

[0015] Beneficial effects: Compared with the existing technology, the utility model has the following advantages: 1. It is suitable for pump stations with large sand content, and its service life is more than doubled that of mechanical seals and non-contact seals; 2. The main shaft is equipped with a stainless steel protective cover, and the main shaft shaft guard will not have wear problems; 3. The main shaft seal does not require lubrication or cooling water, and there is no water leakage at the main shaft seal when the unit is operating normally; 4. The production cost of the seal of the sealing structure is low, which greatly reduces the later operation and maintenance costs of the power station or pump station. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 This is a schematic structural diagram of the assembly state of the turbine main shaft sealing device of the utility model;

[0017] Figure 2 for Figure 1 Enlarged view of part A in the middle. DETAILED DESCRIPTION

[0018] The technical solution of the present utility model will be further described below with reference to the accompanying drawings.

[0019] The turbine in the prior art mainly has two sealing devices, the first is the pump plate gap seal, and the second is the mechanical seal. Among them, the pump plate gap sealing structure includes the pump plate 11, the top cover 1, etc. Figure 1As shown, the runner is fixed to the main shaft, several pump plates 11 are fixed inside the runner along the radial direction of the runner, the top cover 1 and the sealing seat 4 are relatively fixed, an inverted U-shaped leak-proof ring 10 is provided between the cover plate 1 and the runner, and a drain pipe 2 is provided above the top cover 1.

[0020] The top cover's stop ring (10) forms a 0.6-0.7mm gap between each side and the impeller. As water flows through this gap, the pressure decreases due to increased local resistance. When the water reaches the bottom of the runner's stop ring (10) groove, it suddenly expands, then contracts again as it enters the next gap. This repeated expansion and contraction reduces the water pressure to 0.15-0.2 MPa. Ultimately, the water flows through the pump plate (11) mounted on the back of the impeller, where the centrifugal force of the pump plate's rotation drains it into the top cover's drain tank. From there, the top cover drain pipe (2) drains the water to the water inlet pipe or sump. When the unit is operating normally at rated speed, virtually all water leaking from the gap sealed by the top cover stop ring (10) is drained to the drain tank by the pump plate (11) on the back of the impeller, with only a small amount of water leaking into the secondary sealing system.

[0021] like Figure 1 The turbine main shaft sealing device disclosed in the utility model is mainly composed of a sealing seat 4, a protective sleeve 5, a sealing block 7, and a partition 8; the protective sleeve 5 is a stainless steel protective sleeve, which is sleeved outside the main shaft and rotates with the main shaft, and the sealing seat 4 is sleeved outside the protective sleeve 5 and does not rotate with the main shaft; the sealing block 7 and the partition 8 are located between the protective sleeve 5 and the sealing seat 4.

[0022] The outer surface of the protective sleeve 5 is provided with a concave annular groove. Multiple annular sealing blocks 7 are mounted on the outside of the protective sleeve 5 through the annular groove, distributed axially along the protective sleeve 5 and capable of sliding axially along the annular groove. The outer circumference of each sealing block 7 is provided with a spiral groove. During assembly, the multiple sealing blocks 7 are held against the outside of the protective sleeve 5 by stainless steel springs 13 embedded in the groove, allowing them to rotate with the main shaft. The spacers 8 are also annular and, with the same number of sealing blocks 7, are installed within the sealing seat 4. The spacers 8 do not rotate with the main shaft. The main body of the spacers 8 has an L-shaped longitudinal cross-section and consists of two parts: radial spacers distributed radially along the protective sleeve 5 and axial spacers distributed axially along the protective sleeve 5. The radial spacers separate adjacent sealing blocks 7 and the top of the sealing seat 4, while the axial spacers separate the inner wall of the sealing seat 4 from the outer wall of the sealing blocks 7. The outer corners of the spacers 8 are chamfered / beveled, creating a cavity between the spacers 8 and the sealing seat 4, which is used to install the annular sealing strip 12.

[0023] There is a 2-3mm gap between the axial inner circle of the partition 8 and the outer circle of the sealing block 7, and between the axial outer circle of the partition 8 and the sealing seat 4. The height H1 of the sealing block 7 is 2-3mm less than the axial height H2 of the partition, that is, a 1-1.5mm gap is formed between the two sides of the sealing block 7 and the partition 8. Raised rings are provided on the upper and lower surfaces of the outermost circle of the sealing block 7. The raised rings ensure that the height of the outermost circle of the sealing block 7 is consistent with the height of the axial partition H2. The raised rings form contact between the outer circle of the sealing block 7 and the partition 8, thereby maintaining the relative position of the sealing block 7 and the partition 8, while reducing the contact friction loss between the sealing block 7 and the partition 8.

[0024] To extend the service life of the seal block 7 and diaphragm 8 in high-silt environments, the friction surface of diaphragm 8 (and the radial diaphragm surface between the raised ring of the seal block 7) is coated with a tungsten carbide hard alloy coating, achieving a hardness of 1350HV0.3. The seal block 7 is made of polyester polyurethane (high-wear PU), which has excellent wear and high temperature resistance (polyurethane elastomer has a wear resistance eight times that of carbide steel, seven times that of vulcanized rubber, and three times that of ultra-high molecular weight polyethylene).

[0025] During operation, the four sealing blocks 7 are secured to the exterior of the protective sleeve 5 by stainless steel springs 13. The radial partitions of the four partitions 8 are inserted between adjacent sealing blocks 7. Sealing strips 12 are installed at the chamfered / beveled areas on the exterior of the partitions 8. Finally, the sealing seat 4 is assembled. During unit operation, the sealing blocks 7 can freely swing up and down and left and right without becoming stuck. If the first pump plate seal becomes incapable of sealing due to erosion by sediment, leakage increases, and a large amount of pressurized water flows to the second contact seal. The water pressure lifts the sealing blocks 7, forming a complete sealed cavity between the sealing blocks 7, partitions 8, and sealing strips 12. The sealing blocks 7 are rotating components, and the centrifugal force they generate dislodges sediment and returns it to the first seal, achieving a sand removal effect.

[0026] This spindle seal works in conjunction with the pump plate gap seal, eliminating the need for external lubrication. The dual sealing system more than doubles the seal life. If both seals fail, only the partition plate 8, sealing block 7, and sealing strip 12 need to be replaced. These three components are inexpensive to manufacture, simple in structure, and easy to replace.

Claims

1. A turbine main shaft sealing device, comprising a main shaft and a sealing seat (4), characterized in that: A sealing block (7) and a partition (8) are provided between the main shaft and the sealing seat (4). The sealing block (7) is annular and is sleeved outside the main shaft and moves with the main shaft. The partition (8) is located inside the sealing seat (4) and includes a radial partition for isolating two adjacent sealing blocks (7) and isolating the sealing block (7) and the end face of the sealing seat (4), and an axial partition for isolating the sealing seat (4) and the side wall of the sealing block (7). The sealing block (7) and the radial partition, as well as the sealing block (7) and the axial partition, are both clearance-fitted. The outer corner of the partition (8) is at least partially beveled, and a sealing strip (12) is provided at the beveled portion of the partition (8).

2. The turbine main shaft sealing device according to claim 1, characterized in that: The outer wall of the sealing block (7) is provided with a spiral groove, and the sealing block (7) is fixed outside the main shaft through the groove and the spring (13).

3. The turbine main shaft sealing device according to claim 2, characterized in that: The main shaft outer shell is provided with a protective sleeve (5), and an annular groove for installing a sealing block (7) is provided on the outside of the protective sleeve (5). The sealing block (7) is fixed in the annular groove through a groove and a spring (13) and can slide up and down along the annular groove.

4. The turbine main shaft sealing device according to claim 1, characterized in that: The outermost peripheries of the upper and lower sides of the sealing block (7) are provided with raised rings, which are in contact with the surface of the radial partition.

5. The water turbine main shaft sealing device according to claim 1, characterized in that: The gap between the sealing block (7) and the radial partition is 1 to 1.5 mm.

6. The water turbine main shaft sealing device according to claim 1, characterized in that: The gap between the sealing block (7) and the axial partition is 2 to 3 mm.

7. The turbine main shaft sealing device according to claim 1, characterized in that: The number of the sealing blocks (7) and the partitions (8) is the same and no less than 4.

8. The turbine main shaft sealing device according to claim 4, characterized in that: The friction surface of the partition plate (8) is provided with a tungsten carbide hard alloy coating.

9. The water turbine main shaft sealing device according to claim 1, characterized in that: The material of the sealing block (7) is polyester polyurethane.

10. A water turbine, characterized in that: The invention comprises the turbine main shaft sealing device according to claim 1.

Images