Vertical low-cavitation single-stage centrifugal pump

Abstract

The utility model discloses a vertical low-cavitation single-stage centrifugal pump, belongs to the technical field of vertical single-stage centrifugal pumps, and particularly relates to a centrifugal pump with a vertical, single-stage and barrel-bag type structure. According to the vertical low-cavitation single-stage centrifugal pump, the energy difference value between the net positive suction head of the device and the necessary net positive suction head of the pump is increased, enough surplus is reserved, it is fully guaranteed that even under the extremely severe working condition or the potential hazard working condition, cavitation faults of the pump cannot be found, and the safety and reliability of long-term operation are improved. The pump comprises a power part with a pump shaft, a discharge shell is arranged below the power part, a pump cylinder is arranged below the discharge shell, and the lower end of the pump shaft penetrates through the discharge shell and is arranged in the pump cylinder. The pump is characterized in that a connecting pipe which is integrally communicated is arranged in the discharge shell and the pump cylinder, and the lower end of the connecting pipe is connected with a middle section; and the lower end of the pump shaft is connected with the impeller in the middle section and is provided with a suction inlet of the impeller.

Description

Technical Field

[0001] The utility model belongs to the technical field of vertical single-stage centrifugal pumps, and more specifically to a vertical single-stage centrifugal pump with a barrel-bag structure. Background Art

[0002] Centrifugal pumps are widely used in the national economy and industry. In recent years, an increasing number of power generation plants that utilize energy conservation, environmental protection, and resource recycling, such as biomass power generation, municipal solid waste incineration power generation, and industrial exhaust gas waste heat power generation, have been widely adopted. Condensate is transported in the condenser system of a power plant. Due to the limited installation location of the equipment, the pump inlet pressure is relatively low, requiring the pump to have an extremely low required NPSH. For low flow rates and low head conditions, traditional horizontal single-stage centrifugal pumps are often used. In theory, the required NPSH of the pump can meet the operating conditions. However, the wide fluctuation range of the thermal energy combustion value of new power generation plants leads to a wider range of water temperature fluctuations. In actual operation, extremely harsh or potentially hazardous operating conditions may occur, significantly reducing the NPSH of the system and causing cavitation damage to traditional horizontal pumps.

[0003] Traditional horizontal single-stage centrifugal pumps have a fixed structure, with the inlet pipe generally in a horizontal direction and the outlet pipe generally in a vertical upward direction. The pump body and piping layout cannot be changed according to specific project requirements. Summary of the Invention

[0004] The utility model is aimed at the above problems and provides a vertical low-cavitation single-stage centrifugal pump which improves the energy difference between the cavitation margin of the device and the required cavitation margin of the pump and leaves enough margin to fully ensure that the pump will not detect cavitation failure even under extremely harsh working conditions or potentially harmful working conditions, thereby improving the safety and reliability of long-term operation.

[0005] In order to achieve the above-mentioned purpose of the present invention, the present invention adopts the following technical scheme, the present invention includes a power part with a pump shaft, a discharge shell is arranged below the power part, and a pump barrel is arranged below the discharge shell, the lower end of the pump shaft passes through the discharge shell and is arranged in the pump barrel, and is characterized in that: the discharge shell and the pump barrel are provided with a connecting pipe that is connected as a whole, and the lower end of the connecting pipe is connected to the middle section; the lower end of the pump shaft is connected to the impeller in the middle section, and the lower end of the middle section is provided with a suction port of the impeller; a low-pressure chamber is formed between the lower part of the discharge shell and the connecting pipe, and a suction pipe interface connected to the low-pressure chamber is provided on the discharge shell; a high-pressure chamber is formed in the connecting pipe at the lower part of the discharge shell, and a discharge pipe interface is provided on the connecting pipe that passes through the low-pressure chamber and is arranged outside the discharge shell; the low-pressure chamber is connected to the pump barrel.

[0006] As a preferred solution of the present invention, the suction port at the lower end of the middle section is provided with a sealing ring that cooperates with the impeller, and a step surface is provided at the suction port below the sealing ring, and a gasket is provided on the step surface. The gasket is water-lubricated engineering plastic, and a gap is provided between the gasket and the impeller.

[0007] As another preferred solution of the present invention, radial guide bearings for the pump shaft are provided at both the upper and lower ends of the connecting pipe in the pump barrel.

[0008] As a third preferred solution of the present invention, the impeller is fixed on the pump shaft through a round nut and an impeller nut.

[0009] As a fourth preferred solution of the present invention, radial guide vanes of the impeller are also provided in the middle section.

[0010] As a fifth preferred solution of the present utility model, the power unit includes a coupling connected to the pump shaft and a thrust ball bearing.

[0011] The beneficial effects of the present invention are as follows: 1. The present invention improves the pump into a vertical structure, and the impeller is arranged in a physically low pump barrel. The length of the connecting pipe can be adjusted according to the engineering requirements to achieve the energy difference between the cavitation margin of the device and the required cavitation margin of the pump, and leave enough margin to fully ensure that the pump does not have cavitation failure, expand the practical application field of the pump, and is not only suitable for the condenser system of the generator set, but also for the transportation of saturated liquids in petrochemical plants and other industrial fluid transportation devices (small flow and low head). The impeller is equipped with radial guide vanes, which effectively reduces the circumferential size and the circumferential size of the pump barrel compared to the volute-type pressure water chamber used in traditional single-stage pumps, and reduces the circumferential size of the pump pit, saving the cost of foundation construction. Central supports are provided at both ends of the connecting pipe for installing radial guide bearings to support the rotor components, effectively prevent radial runout of the rotor components, and ensure that the pump operates smoothly, safely and reliably over a long period of time.

[0012] 2. The suction and discharge pipe connections are located simultaneously on the discharge housing, above the foundation plate, for easy pipe connection. The discharge housing is equipped with a low-pressure chamber and a high-pressure chamber. The suction pipe connection connects to the outer low-pressure chamber, while the discharge pipe connection connects to the inner high-pressure chamber. The entire discharge housing has a simple structure and can be constructed of welded steel. The inlet and outlet pipe connections are located at the same center height, allowing the inlet and outlet pipes to be arranged horizontally at 180°, vertically at 90° clockwise, and vertically at 90° counterclockwise, forming three possible combinations.

[0013] 3. A gasket is installed where the impeller suction port connects to the bell tube. Combined with the sealing ring, it forms a right-angled protection for the impeller. Made of water-lubricated engineering plastic, the gasket prevents the impeller, shaft, and other rotor components from plummeting in the event of a thrust ball bearing failure, potentially causing collision and abrasion between the impeller suction port and the bell tube. The gasket provides a perfect fit with the impeller, effectively extending its service life.

[0014] 4. The impeller and shaft are axially secured using an impeller nut. An additional round nut is added to achieve dual-nut locking of the impeller, preventing impeller loosening during long-term operation. The relatively thin round nut effectively reduces hydraulic interference with the impeller's suction flow. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It is a structural diagram of the present utility model.

[0016] Figure 2 yes Figure 1 A partial enlarged view of .

[0017] Figure 3 It is a structural schematic diagram of an embodiment of the utility model in which the discharge pipe interface and the suction pipe interface are arranged at 180 degrees.

[0018] Figure 4 This is a structural diagram of an embodiment of the utility model in which the discharge pipe interface and the suction pipe interface are arranged 90° clockwise.

[0019] Figure 5 This is a structural diagram of an embodiment of the utility model in which the discharge pipe interface and the suction pipe interface are arranged 90 degrees counterclockwise.

[0020] In the accompanying drawings, 1 is the power unit, 2 is the discharge casing, 3 is the pump barrel, 4 is the pump shaft, 5 is the bell tube, 6 is the sealing ring, 7 is the gasket, 8 is the impeller nut, 9 is the round nut, 10 is the impeller, 11 is the radial guide vane, 12 is the middle section, 13 is the connecting pipe, 14 is the radial guide bearing, 15 is the thrust ball bearing, and 16 is the pin coupling component. DETAILED DESCRIPTION

[0021] The utility model includes a power unit 1 with a pump shaft 4, a discharge housing 2 is provided below the power unit 1, and a pump barrel 3 is provided below the discharge housing 2, and the lower end of the pump shaft 4 passes through the discharge housing 2 and is arranged in the pump barrel 3, and is characterized in that: a connecting pipe 13 is provided in the discharge housing 2 and the pump barrel 3, and the lower end of the connecting pipe 13 is connected to the middle section 12; the lower end of the pump shaft 4 is connected to the impeller 10 in the middle section 12, and the lower end of the middle section 12 is provided with a suction port of the impeller 10; a low-pressure chamber is formed between the lower part of the discharge housing 2 and the connecting pipe 13, and a suction pipe interface connected to the low-pressure chamber is provided on the discharge housing 2; a high-pressure chamber is formed in the connecting pipe 13 at the lower part of the discharge housing 2, and a discharge pipe interface is provided on the connecting pipe 13 that passes through the low-pressure chamber and is arranged outside the discharge housing 2; the low-pressure chamber is connected to the pump barrel 3.

[0022] This utility model ensures the stable operation of the pump under low NPSH conditions. This structure effectively increases the energy difference between the NPSH of the device and the required NPSH of the pump, avoiding the performance degradation of the pump caused by cavitation problems. It is particularly suitable for harsh working conditions such as high temperature and low pressure. At the same time, the flexible arrangement of the suction pipe interface and the discharge pipe interface can meet various engineering needs and expand the scope of application.

[0023] The suction port at the lower end of the middle section 12 is provided with a sealing ring 6 that cooperates with the impeller 10. A step surface is provided at the suction port below the sealing ring 6, and a gasket 7 is provided on the step surface. The gasket 7 is water-lubricated engineering plastic, and a gap is provided between the gasket 7 and the impeller 10.

[0024] By providing a sealing ring 6 and a backing ring 7 at the suction port, the impeller 10 is effectively protected from collisions or grinding caused by failure of the thrust ball bearing 15, thereby protecting the impeller 10 and the bell tube 5 and extending the service life of the impeller 10. The backing ring 7 is made of water-lubricated engineering plastic with excellent wear resistance, and a gap is left between it and the impeller 10, avoiding the risk of component seizure due to thermal expansion during operation and further enhancing the operational stability of the equipment.

[0025] The upper and lower ends of the connecting pipe 13 in the pump barrel 3 are both provided with radial guide bearings 14 of the pump shaft 4.

[0026] Radial guide bearings 14 are respectively provided at the upper and lower ends of the connecting pipe 13 to provide stable radial support for the pump shaft 4, effectively control the radial runout of the rotor components, and ensure the stability and reliability of the pump during long-term operation.

[0027] The impeller 10 is fixed on the pump shaft 4 via a round nut 9 and an impeller nut 8 .

[0028] The impeller 10 is doubly locked by the impeller nut 8 and the round nut 9, thereby avoiding the problem of the impeller 10 loosening during long-term operation, thereby ensuring the operational safety of the equipment.

[0029] The radial guide vanes 11 of the impeller 10 are also provided in the middle section 12 .

[0030] The radial guide vanes 11 provided in the middle section 12 reduce the energy loss of the fluid and improve the pump head efficiency by optimizing the flow guidance performance.

[0031] The power unit 1 includes a coupling connected to the pump shaft 4 and a thrust ball bearing 15 .

[0032] The power unit 1 is connected to the pump shaft 4 through a coupling and a thrust ball bearing 15, which not only provides stable power transmission but also can withstand axial thrust, ensuring long-term and stable operation of the equipment.

[0033] The prime mover (electric motor) rotates the pump shaft 4 and impeller 10 through the coupling assembly. The medium enters through the suction port of the discharge housing 2, passes through the pump barrel 3, and is drawn into the impeller 10. The impeller 10 rotates and ejects the medium, increasing its head (pressure). The medium flows through radial guide vanes 11 and pipe 13, ultimately exiting the high-pressure chamber of the discharge housing 2 and the discharge pipe. The rotor assembly, comprising the impeller 10, pump shaft 4, and other components, is axially secured by thrust ball bearings 15 and withstands axial thrust. Two radial guide bearings 14, located on the upper and lower sides of pipe 13, provide radial support for the rotor assembly, ensuring long-term, smooth, and reliable operation of the impeller 10.

[0034] It can be understood that the above specific description of the present invention is only used to illustrate the present invention and is not limited to the technical solutions described in the embodiments of the present invention. Ordinary technicians in this field should understand that the present invention can still be modified or replaced by equivalents to achieve the same technical effects; as long as the use requirements are met, they are within the scope of protection of the present invention.

Claims

1. A vertical low-cavitation single-stage centrifugal pump, comprising a power unit (1) having a pump shaft (4), a discharge housing (2) disposed below the power unit (1), a pump barrel (3) disposed below the discharge housing (2), the lower end of the pump shaft (4) passing through the discharge housing (2) and disposed in the pump barrel (3), characterized in that: A connecting pipe (13) is provided in the discharge housing (2) and the pump barrel (3), and the lower end of the connecting pipe (13) is connected to the middle section (12); the lower end of the pump shaft (4) is connected to the impeller (10) in the middle section (12), and the lower end of the middle section (12) is provided with a suction port of the impeller (10); a low-pressure chamber is formed between the lower part of the discharge housing (2) and the connecting pipe (13), and a suction pipe interface connected to the low-pressure chamber is provided on the discharge housing (2); a high-pressure chamber is formed in the connecting pipe (13) at the lower part of the discharge housing (2), and a discharge pipe interface is provided on the connecting pipe (13) that passes through the low-pressure chamber and is provided outside the discharge housing (2); the low-pressure chamber is connected to the pump barrel (3).

2. A vertical low cavitation single-stage centrifugal pump according to claim 1, characterized in that: The suction port at the lower end of the middle section (12) is provided with a sealing ring (6) that cooperates with the impeller (10); a step surface is provided at the suction port below the sealing ring (6); a gasket (7) is provided on the step surface; the gasket (7) is made of water-lubricated engineering plastic; and a gap is provided between the gasket (7) and the impeller (10).

3. A vertical low cavitation single-stage centrifugal pump according to claim 1, characterized in that: The upper and lower ends of the connecting pipe (13) in the pump barrel (3) are both provided with radial guide bearings (14) of the pump shaft (4).

4. A vertical low cavitation single-stage centrifugal pump according to claim 1, characterized in that: The impeller (10) is fixed to the pump shaft (4) via a round nut (9) and an impeller nut (8).

5. A vertical low cavitation single-stage centrifugal pump according to claim 1, characterized in that: The middle section (12) is also provided with radial guide vanes (11) of the impeller (10).

6. A vertical low cavitation single-stage centrifugal pump according to claim 1, characterized in that: The power unit (1) includes a coupling connected to the pump shaft (4) and a thrust ball bearing (15).

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