WO2013131351A1

WO2013131351A1 - Multi-stage submersible pump for mines

Info

Publication number: WO2013131351A1
Application number: PCT/CN2012/079137
Authority: WO
Inventors: 陆伟刚; 李伟; 胡博; 李辉
Original assignee: 江苏大学
Priority date: 2012-03-09
Filing date: 2012-07-25
Publication date: 2013-09-12

Abstract

Disclosed is a multi-stage submersible pump for mines, wherein an electric motor is coaxial with a water pump and the electric motor can work submerged. The water pump is a multi-stage centrifugal pump and the lift head is higher than 300 metres. The water pump balance drum balancing the axial force uses an end face sealing method able to automatically compensate, overcoming the drawbacks of failure by wear of the radial sealing method. Support from a bearing (18)is added to the bottom end of a rotary shaft (20), and using mine water containing relatively little silt to lubricate the bearing overcomes the drawbacks of failure by wear of a sliding bearing.

Description

Multi-stage submersible pump

Technical field

The invention is a multi-stage submersible pump, in particular, the number of impellers for pumping sandy water in the coal mine is relatively large, the pump head is relatively high, the axial force of the impeller is relatively large, and the balance drum is generally used to balance the axial force. The multi-stage submersible pump belongs to the technical field of general mechanical product manufacturing.

Background technique

At present, most of the multi-stage submersible pumps use the balance drum to balance the axial force, as shown in Figure 1. Although there are many methods for balancing the axial force, the method of balancing the axial force of the drum is the simplest. The axial force balance of the balance drum plus balance disc used in the prior invention patent "A High-Efficiency High-Voltage Horizontal Multistage Centrifugal Pump" (ZL200710024398.2) is also much more complicated than the balance drum method shown in FIG. The multi-stage submersible pump with balance drum balancing axial force is the most widely used multi-stage submersible pump because it has the most compact structure and the lowest production cost. However, at present, the balance drum of the multi-stage submersible pump adopts the radial seal method which cannot be compensated. When working in the mine sandy water, it is easy to be worn by the sand and cause a lot of leakage, which greatly reduces the lift of the multi-stage submersible pump. scrapped. In order to overcome the shortcomings of the radial seal balance drum, the prior invention patent "Pump axial force balance device" (ZL87100241) invented a face-sealed, self-compensating balance drum method, but this invention found in practice that there are still serious technical defects, if not improved, it can not be in multi-grade mine Used in submersible pumps.

The technical disadvantage of the multi-stage submersible pump shown in Fig. 1 is that there is no bearing support at the bottom end of the rotating shaft, which causes the impeller ring and the impeller hub to wear and damage quickly in the operation of the sandy liquid, although there are many The bottom end of the rotary shaft of the grade submersible pump is supported by bearings, as shown in Figure 2 of the specification in ZL201020548965.1, but because the lubricating fluid of the bottom end bearing has a relatively large sand content, the bearing life is relatively short, and it is also a Technical flaws.

technical problem

In order to overcome the technical defects of the existing multi-stage submersible pump and improve the service life of the multi-stage submersible pump, The invention provides an innovative design multi-stage submersible pump, wherein the balanced axial force balance drum adopts an end face sealing method capable of automatically compensating, overcomes the defect of the radial sealing type wear failure, and the bottom end of the rotating shaft is increased. The bearing is supported, and the material is lubricated locally, and the bearing water with less sand is used to lubricate the bearing, which overcomes the defect of the sliding bearing wear failure.

Technical solution

The basic structure is the same as the existing multi-stage submersible pump in the coal mine. The electric motor and the water pump are coaxial, and the electric motor can work in diving. The water pump is a multi-stage centrifugal pump with a lift of more than 300 meters. The main innovations are:

1. The balance drum that balances the axial force of the rotor adopts an end face sealing method capable of automatic compensation, and the static ring as the balance drum main body can move axially, so that the static ring that does not rotate and the moving ring that rotates synchronously with the rotating shaft are always close together. The end face seal is composed of a main sealing surface and a secondary sealing surface. The outer diameter of the main sealing surface is larger than the diameter of the balance drum, the inner diameter of the main sealing surface is smaller than the diameter of the balance drum, and the dynamic ring sealing surface and the static ring sealing surface of the main sealing surface are fitted. Together, the secondary sealing surface is on the outer side of the main sealing surface, and there is a gap between the moving ring sealing surface of the secondary sealing surface and the static ring sealing surface, and the gap of the secondary sealing surface is between 0.2 mm and 2 mm.

All centrifugal pump impellers produce axial forces, and high-lift multi-stage centrifugal pumps produce large axial forces. Most of the existing multi-stage submersible pumps use balanced drum balance axial force. For multi-stage submersible pumps with lift heads higher than 300 meters, the pressure difference between the two ends of the balance drum is higher than 3 MPa, which is relatively large for radial clearance. In the case of the balance drum, there is a large amount of leakage and a high-speed jet is formed. Because the multi-stage submersible pump pumps the mine water containing sediment, a large amount of leakage will result in a harder sand. The high-speed jet wraps the sand particles, which will cause the balance drum gap to wear up quickly and increase, causing the leakage amount to increase sharply, which causes the head of the multi-stage submersible pump to quickly decrease and fail.

The end face seal balance drum is the same as the radial seal balance drum. There is a cylinder blocking high pressure zone and low pressure zone. The diameter of this cylinder is called balance drum diameter. The balance drum diameter determines the axial force balance. The difference is that the main body of the radial seal balance drum rotates synchronously with the rotating shaft, and it relies on the radial gap between the non-rotating final pump body to realize the dynamic and static transition. This gap will wear more, so the leakage is very high. Big. The end face seal balance drum relies on the end face friction of the moving ring and the static ring to realize the dynamic and static transition. The static ring is not rotated as the balance drum main body, and there is a static ring O-ring at the balance drum diameter to ensure that there is no leakage and balance. The other half of the drum rotates synchronously with the rotating shaft, and the sealing gap between the moving ring and the stationary ring is almost equal to zero, so the leakage amount is small. After the sealing surface wears, the static ring can also move axially, so that the sealing surface of the moving ring and the static ring continue to be attached together, which is the automatic compensation function of the end face sealing balance drum.

The superiority of the face seal balance drum was discovered in the 1980s. Although it has not been used in multi-stage submersible pumps, it has been used as a patent for invention (ZL87100241) in a submersible pump for wells. The seal balance drum has only the primary sealing surface and no secondary sealing surface of the present invention that increases outside the primary sealing surface. The end face seal balance drum without the secondary sealing surface is difficult to design. The specific pressure of the sealing surface is not too large. The sealing surface is damaged. The specific pressure of the sealing surface is too small. In operation, the sealing surface is pushed away by the high pressure liquid, and once pushed, once pushed When opened, it will cause a lot of leakage and completely defeat the balance drum. This defect has caused the ZL87100241 to be unpromoted.

The present invention with the addition of a secondary sealing surface effectively overcomes this drawback. Since the end face seal balance drum can balance the axial force in the case of a small amount of leakage, the specific pressure of the seal face should be relatively small compared with the general mechanical seal, which can greatly extend the life of the main seal face. However, a small amount of leakage on the main sealing surface increases the pushing force on the main sealing surface. When the instability of the pump working condition leads to an increase in the leakage amount, the pushing force on the sealing surface increases, and the pushing force increases. This will increase the amount of leakage, and the vicious cycle of pushing force and leakage will cause the main sealing surface to be pushed away by the high pressure liquid. However, after the auxiliary sealing surface is increased, the pressing force of the auxiliary sealing surface can be increased when the leakage of the main sealing surface increases, and the reasonable design can increase the leakage force, and the pressing force of the auxiliary sealing surface increases more than the main sealing. The amount of pushing force is increased to prevent the sealing surface from being pushed away.

The clearance of the secondary sealing surface should not be too large or too small. If it is larger than 2mm, the sensitivity is too low, and the pressing force adjustment effect of the secondary sealing surface will be lost. If it is less than 0.2mm, the service life will be affected. When the main sealing surface is worn, The pressure will be too large and the end face seal balance drum will wear out quickly.

2. Another innovation of the present invention is that the lower part of the water pump has a bearing seat including a water inlet guide vane and a liquid storage chamber, and a sliding bearing for supporting the bottom end of the rotating shaft. The lubricating fluid of the sliding bearing is derived from the liquid storage chamber at the lower part of the bearing housing, and the liquid The liquid in the storage chamber is derived from the liquid having a relatively small amount of sand in the upper portion of the inlet guide vane, and the inlet inlet window and the liquid storage chamber in the upper portion of the inlet guide vane are communicated through the axial through hole of the inlet guide vane.

Multi-stage submersible pumps have more impeller stages and longer pump shafts. Generally, sliding bearings are needed to assist the rotor. The existing multi-stage submersible pumps mostly rely on the impeller ring and the impeller hub as sliding bearings to support the rotor. However, the materials in these two places are generally not suitable for use as bearings, and the diameters of the two places are relatively large, the line speed is relatively high, and it is easy to wear and damage when running in the sandy water of the mine. ZL201020548965.1 proposes to install a three-composite radial sliding bearing on the bottom end of the rotating shaft, but the bottom end of the rotating shaft is the place with the largest amount of sand, and even the hard alloy is easy to wear and damage. The disclosed invention patent application "a hard alloy sliding bearing water-cooling cooling lubrication system for a submersible pump" (201010591094.6) proposes a sliding bearing for lubricating the bottom end of the rotating shaft at the surface of the pool, which can solve the problem, but is implemented too Complex, packaging, transportation and installation add to the trouble for users. The invention skillfully utilizes the place where the flow rate of the liquid in the guide vane is relatively low, the hard sand is easy to settle in the lower part, and the liquid with less sand content in the upper part of the guide vane is first introduced into the liquid storage chamber, and then a part of the sediment is precipitated. At the bottom of the storage chamber, the liquid at the bottom end of the lubricating bearing is less contained, which ensures a greatly improved service life of the bearing.

3. Another innovation of the present invention is that the inlet angle of the inlet guide vane of the lower portion of the water pump is 90 degrees, and the inlet angle of the inlet guide vane is 10 degrees to 20 degrees.

This is a technical innovation under the premise that the lower part of the pump of the multi-stage submersible pump has a bearing seat including the inlet guide vane. When the inlet angle of the inlet guide vane is 90 degrees, the overflow area of the vane inlet is Larger, lower flow rate, sand in sandy water is easy to precipitate, and the inlet angle of the inlet guide vane is 10 degrees to 20 degrees, which can make the flow of the impeller inlet have a peripheral speed, which can reduce the multi-stage submersible pump. Power under high flow conditions. Since the majority of multi-stage submersible pumps are low-ratio centrifugal pumps, reducing the power under high-flow conditions is to reduce their maximum power, thus ensuring safe operation of multi-stage submersible pumps under full lift conditions.

Beneficial effect

The invention has the beneficial effects of overcoming the defects of the existing multi-stage submersible pump, and manufacturing a multi-stage submersible pump with reliable axial force balance device, long end bearing life and relatively small power extreme value with low additional cost. Therefore, the multi-stage submersible pump of the present invention is more competitive in the market.

DRAWINGS

The invention will now be further described with reference to the drawings and embodiments.

Figure 1 is a simplified diagram of a prior art multi-stage submersible pump.

Figure 2 is a schematic diagram of a multi-stage submersible pump embodying the present invention.

Fig. 3 is a schematic enlarged view of the end face seal balance drum of Fig. 2.

Figure 4 is a two view of the stationary ring of Figure 3.

Figure 5 is a two-view view of a static ring of a conventional end face seal balancing drum (without a secondary sealing surface).

Figure 6 is a second elevational view of the bearing housing of Figure 2 including the inlet guide vanes.

In the figure: 1. low pressure chamber, 2. final stage pump body, 3. static ring stop pin, 4. balance drum diameter, 5. static ring spring, 6. static ring O-ring, 7. static ring pressure relief groove 8. Static ring, 9. Main sealing surface, 10. Moving ring, 11. Final impeller, 12. Final impeller back blade, 13. Liquid storage chamber, 14. Bearing seat, 15. Inlet guide vane axial Through hole, 16. guide vane inlet window, 17. inlet guide vane, 18. sliding bearing, 19. rotating shaft bottom end, 20. rotating shaft, 21. final pump body pressure relief hole, 22. secondary sealing surface clearance, 23. Radial clearance, 24. Main sealing surface inner diameter, 25. Main sealing surface outer diameter, 26. Secondary sealing surface outer diameter, 27. Secondary sealing surface, 28. Centripetal thrust ball bearing, 29. First stage impeller inlet, 30. Inlet water guide vane exit angle, 31. Inlet guide vane inlet angle.

Embodiments of the invention

The embodiment of the invention shown in FIG. 2 is a BQW10-300/5-37 multi-stage submersible pump. The basic structure is the same as the existing multi-stage submersible pump in the coal mine. The electric motor and the water pump are coaxial, and the electric motor can dive. Working, the pump is a multi-stage centrifugal pump with a 5-stage impeller and a head of 300 meters. It is different from the existing multi-stage submersible pump. The main innovation is that the balance drum that balances the axial force of the rotor adopts an end face seal that can be automatically compensated. the way. 3 and 4 show a more clear expression of the end face sealing method of the present invention, and the static ring 8 as the balance drum main body can be axially moved, so that the stationary ring 8 that does not rotate and the moving ring 10 that rotates synchronously with the rotating shaft 20 are always Close together, the end face seal is composed of a main sealing surface 9 and a secondary sealing surface 27, the outer sealing surface outer diameter 25 is larger than the balance drum diameter 4, the main sealing surface inner diameter 24 is smaller than the balance drum diameter 4, and the main sealing surface 9 is moving ring The sealing surface and the static ring sealing surface are bonded together, the secondary sealing surface 27 is outside the main sealing surface 9, the moving ring sealing surface of the secondary sealing surface 27 and the stationary ring sealing surface have a gap, and the secondary sealing surface gap 22 Between 0.2mm~2mm.

If it uses the radial seal balance drum shown in Figure 1 to balance the axial force, there will be a large amount of leakage at the radial gap 23, and more serious, the leakage of liquid will bring sediment, making the radial clearance 23 is quickly worn out, the gap is getting bigger and bigger, and the leakage is getting bigger and bigger, which will cause the pump lift to reach less than 300 meters and is not qualified for work. The embodiment of Figure 2 overcomes this drawback by employing an end face seal balancing drum.

The face seal balance drum is the same as the radial seal balance drum. The pressure difference is balanced by the pressure difference between the two end faces of a cylinder. The diameter of this cylinder is called the balance drum diameter 4, and the balance drum diameter 4 determines the size. The amount of axial force balance, no matter which balance drum can not fully balance the axial force, requires the radial thrust ball bearing 28 to bear the remaining axial force. The pressure in the high pressure zone is determined by the pump head, and the pressure in the low pressure zone is the atmospheric pressure or water level pressure of the inlet. The pressure at the lower end of the end face seal balance drum and the pressure on the outside side are equal to the pressure in the high pressure zone, and the pressure at the upper end of the end face seal balance drum and the pressure on the inner side pass through the static ring pressure relief groove 7, the low pressure chamber 1 and the final stage pump body pressure relief hole 21 The pool connection is equal to the pressure in the low pressure zone, which is also substantially the same as the radial seal balance drum.

The end face seal balance drum is different from the radial seal balance drum in that the main body of the radial seal balance drum rotates synchronously with the rotary shaft 20, and it relies on the radial gap 23 between the non-rotating final stage pump body 2 to realize the movement and static In the transition, this gap will wear more, so the amount of leakage is large. The end face seal balance drum relies on the end face friction of the moving ring 10 and the static ring 8 to realize the dynamic and static transition, and the static ring 8 as the end face seal balances the drum main body to be non-rotating, and has a static ring O-ring 6 at its balance drum diameter 4. It is ensured that there is no leakage here, and the other half of the end face seal balance drum is synchronously rotated with the rotating shaft 20 as the moving ring 10, and the sealing gap between the moving ring 10 and the stationary ring 8 is almost equal to zero, so that the leakage amount is small. After the sealing surface is worn, the static ring 8 can also move axially, so that the sealing surface of the moving ring 10 and the static ring 8 continue to be attached together, which is the automatic compensation function of the end face sealing balance drum, preventing the static ring 8 from rotating. The ring stop pin 3 does not prevent the axial movement of the stationary ring 8, and the static ring spring 5 ensures that the sealing surface of the moving ring 10 and the stationary ring 8 can be brought together without a pressure difference.

The superiority of the face seal balance drum was discovered in the 1980s. Although it has not been used in multi-stage submersible pumps, it has been used as a patent for invention (ZL87100241) in a submersible pump for wells. The seal balance drum has only the primary seal face 9 and no secondary seal face 27 of the present invention that increases outside the primary seal face. The end face seal balance drum without the secondary sealing surface 27 is difficult to design as shown in Fig. 5. The specific pressure of the sealing surface is not too large, the sealing surface is damaged, the specific pressure of the sealing surface is too small, and the sealing surface is high pressure during operation. The liquid pushes open, and once pushed open, it causes a large amount of leakage and completely defeats the balance drum. This defect has caused the ZL87100241 to be unpromoted.

The present invention in which the secondary sealing surface 27 is added effectively overcomes this drawback. Since the end face seal balance drum can balance the axial force in the case of a small amount of leakage, the specific pressure of the seal face should be relatively small compared with the general mechanical seal, which can greatly extend the life of the main seal face 9. However, a small amount of leakage of the main sealing surface 9 increases the pushing force on the main sealing surface 9. When the instability of the pump operating condition causes an increase in the leakage amount, the pushing force on the sealing surface increases, and the pushing force increases. With the vicious cycle of leakage, the main sealing surface 9 is inevitably pushed away by the high pressure liquid. However, after the secondary sealing surface 27 is increased, the increase in the pressing force of the two sealing surfaces is greater than the increase in the pushing force when the leakage of the main sealing surface 9 is increased, thereby preventing the sealing surface from being pushed away. The balance drum diameter 4 of the embodiment is 80 mm, the outer diameter 25 of the main sealing surface is 88 mm, the inner diameter 24 of the main sealing surface is 72 mm, and the outer diameter 26 of the secondary sealing surface is 110 mm, and the pressure acting on the balance drum by the head 300 m is calculated. Assuming a spring pressure of 10 kg, the main sealing surface 9 does not leak at all, and the dynamic reversal coefficient is 0.5, the force on the main sealing surface 9 is 25 kg, the specific pressure is 1.25 kg/cm ² , obviously the specific pressure is small, the main sealing surface 9 is not easy to damage. Assuming that the spring pressure is 10 kg, the main sealing surface 9 has a small amount of leakage, and the dynamic reaction coefficient reaches 0.54, the force on the main sealing surface 9 is 0.95 kg, and the specific pressure is 0.05 kg/cm ² . Obviously, the main sealing surface 9 has May maintain a fit. Assuming that the spring pressure is 10kg, the main sealing surface 9 has a relatively large leakage, and the dynamic inverse coefficient is greater than 0.55, the force on the main sealing surface 9 is a negative value, that is, the pushing force is greater than the pressing force, and the main sealing surface 9 is Will be pushed open, this is the flaw of ZL87100241. However, with the secondary sealing surface 27 of the present invention, this problem is solved. When the primary sealing surface 9 leaks, the pressure on the secondary sealing surface 27 is lowered, and the pressing force is increased, assuming that the primary sealing surface 9 There is a small amount of leakage, and the dynamic reversal coefficient reaches 0.6. At this time, the dynamic inverse coefficient on the secondary sealing surface 27 will be less than 1 but greater than the dynamic inverse coefficient of the main sealing surface 9 of 0.6, assuming that the integrated dynamic inverse coefficient on the sealing surface is 0.7, the sealing surface The upper force is 212kg and the specific pressure is 3.9kg/cm ² , which ensures that the sealing surface is not pushed away further, and because the force of the sealing surface acts on the leaking liquid at this time, as long as the leakage liquid contains The amount of sand is small, and the life of the sealing surface will still be relatively long. Since the leakage gap of the end face seal is much smaller than the radial gap 23 of the radial seal and the automatic compensation capability of the end face seal balance drum, the leakage amount is much smaller than that of the radial seal balance drum, so the sand passes from the low point to the final stage impeller. The sealing surface of the back blade 12 to the upper portion is difficult.

When the main sealing surface 9 has no leakage, since the liquid in the secondary sealing surface gap 22 is only in communication with the high pressure region and is completely disconnected from the low pressure region, the pressure on the secondary sealing surface 27 is equal to the pressure acting on the balancing drum, that is, the reverse The coefficient is equal to 1, so the specific pressure acting on the main sealing surface 9 is still 1.25 kg/cm ² .

Another innovation of the embodiment of the invention shown in Fig. 2 is that the lower portion of the water pump has a bearing housing 14 including a water inlet guide vane 17 and a liquid storage chamber 13, a sliding bearing 18 for supporting the bottom end 19 of the rotating shaft, and lubrication of the sliding bearing 18. The liquid is derived from the liquid storage chamber 13 in the lower part of the bearing housing 14. The liquid in the liquid storage chamber 13 is derived from the liquid having a relatively small amount of sand in the upper portion of the inlet guide vane 17, that is, the inlet inlet inlet window 17 has a vane inlet window 16 and a liquid. The storage chambers 13 communicate with each other through the inlet guide vanes of the water guide vanes.

Multi-stage submersible pumps have more impeller stages and longer pump shafts. Generally, sliding bearings are needed to assist the rotor. The multi-stage submersible pump like Figure 1 relies on the impeller ring and the impeller hub as sliding bearings to support the rotor. It is very easy to wear and damage. ZL201020548965.1 proposes to install a three-composite radial sliding bearing on the bottom end of the rotating shaft, but the bottom end 19 of the rotating shaft is the place with the largest amount of sand, and even the hard alloy is easy to wear and damage. The disclosed invention patent application "a hard alloy sliding bearing water-cooling cooling lubrication system for a submersible pump" (201010591094.6) proposes a sliding bearing for lubricating the bottom end of the rotating shaft at the surface of the pool, which can solve the problem, but is implemented too Complex, packaging, transportation and installation add to the trouble for users. The invention skillfully utilizes the place where the flow rate of the liquid in the guide vane is relatively low, the hard sand is easy to settle in the lower part, and the liquid with less sand content in the upper part of the guide vane is first introduced into the liquid storage chamber 13, and then a part of the sediment is introduced. Precipitated at the bottom of the storage chamber, so that the liquid at the bottom end of the lubrication bearing is less, which ensures that the service life of the bearing is greatly extended.

This can be seen more clearly from Figure 6, where the flow area at the vane inlet 16 is much larger than the vane outlet and the impeller inlet, which is approximately 0.025 m ² at a nominal flow of 10 m ³ /h. The average flow rate is only 0.1m/s, and the flow velocity at the actual guide vane inlet window 16 is still lower than this number. Therefore, the larger mass of sand is difficult to enter the guide vane inlet window 16, and only the light particles such as pulverized coal will enter with the liquid. The vane inlet window 16 enters the liquid storage chamber 13 through the inlet guide hole 15 of the inlet guide vane. Since the flow rate in the liquid storage chamber 13 is lower, some sand particles are precipitated, thereby lubricating the sliding pair of the sliding bearing 18 The wear of the bearing 18 is very slight. Since the pressure of the first stage impeller inlet 29 is the lowest, the liquid in the liquid storage chamber 13 flows into the first stage impeller inlet 29 through the sliding bearing 18, which provides a good lubrication and cooling effect on the sliding bearing 18.

Another innovation of the embodiment of the present invention shown in Fig. 2 is that the inlet angle 31 of the inlet guide vane of the lower portion of the water pump is 90 degrees, and the inlet angle 30 of the inlet guide vane is 10 degrees to 20 degrees.

This can be seen more clearly from Figure 6. This is a technical innovation under the premise that the lower part of the pump of the multi-stage submersible pump has a bearing seat 14 including the inlet guide vane 17. When the inlet angle of the inlet guide vane is 90 degrees, the inlet of the vane is over. The flow area is relatively large, the flow rate is relatively low, the sand in the sandy water is easy to precipitate, and the inlet angle of the inlet guide vane is 10 degrees to 20 degrees, which can make the flow of the impeller inlet have a peripheral velocity, which can reduce the multi-grade mine. The power of the submersible pump under high flow conditions. Since the majority of multi-stage submersible pumps are low-ratio centrifugal pumps, reducing the power under high-flow conditions is to reduce their maximum power, thus ensuring safe operation of multi-stage submersible pumps under full lift conditions.

Claims

The utility model relates to a multi-stage submersible pump, which is characterized in that: the electric motor and the water pump are coaxial, and the electric motor can be used for diving work, wherein the water pump is a multi-stage centrifugal pump and the head is higher than 300 m; the balance drum of the balance rotor axial force can be automatically The compensated end face sealing mode can be axially moved as a static ring of the balance drum main body, so that the non-rotating static ring and the moving ring rotating synchronously with the rotating shaft are always close together, and the end face sealing is common to the main sealing surface and the auxiliary sealing surface. The outer diameter of the main sealing surface is larger than the diameter of the balance drum, the inner diameter of the main sealing surface is smaller than the diameter of the balancing drum, the moving ring sealing surface of the main sealing surface and the static ring sealing surface are fitted together, and the auxiliary sealing surface is outside the main sealing surface. There is a gap between the moving ring sealing surface of the secondary sealing surface and the static ring sealing surface, and the gap of the secondary sealing surface is between 0.2 mm and 2 mm.
A multi-stage submersible pump according to claim 1, wherein the lower part of the water pump has a bearing seat including a water inlet guide vane and a liquid storage chamber, a sliding bearing for supporting the bottom end of the rotating shaft, and a lubricating liquid source for the sliding bearing. In the liquid storage chamber at the lower part of the bearing housing, the liquid in the liquid storage chamber is derived from the liquid with a relatively small amount of sand in the upper part of the inlet guide vane, and there is a guide vane inlet window and the liquid storage chamber through the inlet guide vane in the upper part of the inlet guide vane. The axial through holes are connected.
A multi-stage submersible pump according to claim 1 and claim 2, wherein the inlet angle of the inlet guide vane of the lower part of the water pump is 90 degrees, and the inlet angle of the inlet guide vane is 10 degrees to 20 degrees. .