A two-stage pump

Abstract

The application discloses a two-stage pump and belongs to the technical field of industrial pumps. The two-stage pump comprises a volute, a driving shaft, and a driving component for driving the driving shaft to rotate. The driving shaft comprises a first rotating shaft and a second rotating shaft. At least one front impeller is arranged outside the second rotating shaft. A rear impeller is arranged outside the second rotating shaft. A flow passage is arranged between the front impeller and the rear impeller. A connecting assembly is arranged in the flow passage and is connected with the first rotating shaft and the second rotating shaft. The outer diameter of the front impeller is larger than that of the rear impeller. The flow passage is arranged between the front impeller and the rear impeller, so that the flow area is increased, the pre-rotation intensity of fluid at the inlet of the rear impeller is weakened, the energy is fully converted by means of the increased flow passage at the inlet of the rear impeller, the fluid pressure at the inlet of the rear impeller is increased, meanwhile, the fluid is buffered, the pre-rotation intensity of fluid at the inlet of the rear impeller is weakened, and the overall performance of the pump is improved.

Description

Technical Field

[0001] This application relates to the field of industrial pump technology, and in particular to a two-stage pump. Background Technology

[0002] A multistage pump is a type of pump that increases fluid pressure by using multiple impellers connected in series. It is widely used in petrochemical, power, seawater desalination, and boiler feedwater industries. Traditional two-stage pumps typically have radial guide vanes between the impellers. The fluid must bypass these guide vanes, reducing the flow area between the impellers, increasing flow resistance, and decreasing pump efficiency. Utility Model Content

[0003] This application provides a two-stage pump that eliminates the radial guide vane structure before the rear impeller and connects the front and rear impellers with a connecting assembly. This allows for efficient energy conversion and reduces the outer diameter of the rear impeller by utilizing the enlarged flow cavity at the rear impeller inlet, thereby improving the overall pump performance. The technical solution adopted is as follows:

[0004] A two-stage pump includes a volute and a drive shaft, and a drive component for driving the drive shaft to rotate. The drive shaft includes a first shaft and a second shaft, with at least one front impeller and a rear impeller disposed on the outer side of the second shaft.

[0005] A flow passage cavity is provided between the front impeller and the rear impeller, and a connecting component is provided in the flow passage cavity to connect the first rotating shaft and the second rotating shaft;

[0006] The outer diameter of the front impeller is larger than the outer diameter of the rear impeller.

[0007] The front impeller can pre-compress the fluid, increase the pressure at the inlet of the rear impeller, thereby reducing cavitation caused by low inlet pressure and reducing erosion and vibration on the impeller surface.

[0008] Preferably, the volute is a split structure and is detachably connected via fastening components. These fastening components are high-strength alloy bolts; this simplifies the assembly process, reduces manufacturing costs, and allows for impeller replacement simply by removing the bolts during maintenance, thereby shortening maintenance time.

[0009] Preferably, the connecting assembly includes a plurality of specially designed lead screws, which are evenly distributed circumferentially.

[0010] More preferably, the specially designed lead screw is made of high-strength cast iron or stainless steel.

[0011] Preferably, the housing is provided with a liquid inlet and a liquid outlet, the liquid inlet being connected to the front impeller and the liquid outlet being connected to the rear impeller.

[0012] Preferably, there is an axial distance between the inlet side of the rear impeller and the outlet side of the front impeller.

[0013] Preferably, a gradually expanding flow channel is formed between the outlet diameter of the front impeller and the inlet diameter of the rear impeller.

[0014] Compared with the prior art, the beneficial effects of this application are as follows:

[0015] (1) A flow cavity is provided between the front impeller and the rear impeller of this application to increase the flow area and reduce the pre-swirling intensity of the fluid at the inlet of the rear impeller. With the help of the increased flow cavity at the inlet of the rear impeller, the energy is fully converted and the fluid pressure at the inlet of the rear impeller is increased. At the same time, it can buffer the fluid and reduce the pre-swirling intensity of the fluid at the inlet of the rear impeller, thereby improving the overall performance of the pump.

[0016] (2) The outer diameter of the front impeller of this application is larger than that of the rear impeller. When the fluid passes through the front impeller, it can increase the fluid pressure at the inlet of the rear impeller, which helps to reduce the cavitation phenomenon caused by the low inlet pressure. At the same time, it reduces the erosion and vibration on the impeller surface, thereby extending the service life of the pump. Attached Figure Description

[0017] Figure 1 This is the right view of this application;

[0018] Figure 2 This application Figure 1 Sectional view at point AA;

[0019] Figure 3 This is a schematic diagram of the specially designed lead screw arrangement for this application.

[0020] In the picture:

[0021] 1. Volute; 11. Shell 1; 12. Shell 2; 13. Connecting seat;

[0022] 2. Flow chamber; 3. Front impeller; 4. Rear impeller;

[0023] 5. Drive shaft; 51. First rotating shaft; 52. Second rotating shaft;

[0024] 6. Special lead screw, 7. Liquid inlet, 8. Liquid outlet, 9. Fastening components. Detailed Implementation

[0025] The technical solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the embodiments described in this application are only some embodiments of this application, and not all embodiments. Based on the embodiments in this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.

[0026] See Figures 1 to 3 To further elaborate on this application:

[0027] Combination Figure 2 A two-stage pump includes a volute 1 and a drive shaft 5, and a drive component for driving the drive shaft 5 to rotate. The drive shaft 5 includes a first rotating shaft 51 and a second rotating shaft 52. The first rotating shaft 51 is connected to the drive component, and the drive component may be a motor.

[0028] At least one front impeller 3 and a rear impeller 4 are provided on the outer side of the second rotating shaft 52. A flow passage 2 is provided between the front impeller 3 and the rear impeller 4. In this embodiment, there is one front impeller 3.

[0029] A connecting assembly is provided between the first rotating shaft 51 and the second rotating shaft 52 for coaxial connection. This connecting assembly rigidly connects the first rotating shaft 51 and the second rotating shaft 52, thereby increasing the flow area of ​​the flow cavity 2, which helps to reduce the fluid velocity and increase the fluid pressure within the flow cavity 2. Simultaneously, it buffers the fluid, weakens the fluid pre-swirl intensity at the inlet of the rear impeller 4, and thus improves the overall performance of the pump.

[0030] In this embodiment, the outer diameter of the front impeller 3 is larger than the outer diameter of the rear impeller 4. Preferably, the outer diameter of the rear impeller is 80% of the outer diameter of the front impeller 3. During operation, the front impeller 3 pressurizes the fluid, significantly increasing the inlet pressure of the rear impeller 4, thereby reducing cavitation and improving service life.

[0031] Since the outer diameter of the front impeller 3 is larger than that of the rear impeller 4, the fluid pressure at the inlet of the rear impeller 4 can be increased after the fluid passes through the front impeller 3. This helps to reduce cavitation caused by the low inlet pressure of the rear impeller 4, and at the same time reduces erosion and vibration on the impeller surface, thereby extending the service life of the pump.

[0032] Combination Figure 1 and Figure 2The volute 1 is a split structure, detachably connected via fastening components 9. In this embodiment, the volute 1 includes a first housing 11 and a second housing 12, with a connecting seat 13 between the first housing and the second housing 12. A plurality of fastening components 9, which are high-strength alloy bolts, are connected between the first housing 11 and the second housing 12. These fastening components 9 are evenly distributed circumferentially and are used in conjunction with anti-loosening washers to ensure reliable connection during long-term operation. The bolt connection simplifies the assembly process, enhances component versatility, and reduces manufacturing costs. During maintenance, only the bolts need to be removed to replace the impeller, shortening maintenance time.

[0033] Combination Figure 3 The connecting assembly includes several specially designed lead screws 6; in this embodiment, the specially designed lead screws 6 are made of high-strength cast iron or stainless steel. There are four specially designed lead screws 6, which are evenly distributed along the circumferential direction to rigidly connect the first rotating shaft 51 and the second rotating shaft 52.

[0034] The first housing 11 is provided with a liquid inlet 7, which is connected to the front impeller 3; the second housing 12 is provided with a liquid outlet 8, which is connected to the rear impeller 4; the fluid is drawn into the volute 1 by the front impeller 3 through the liquid inlet 7, compressed and transported to the flow chamber 2, and discharged from the liquid outlet 8 by the rear impeller 4.

[0035] In some embodiments, a gradually expanding flow channel is formed between the outlet diameter of the front impeller 3 and the inlet diameter of the rear impeller 4, which helps to reduce flow loss and improve pumping efficiency; preferably, the ratio of the outlet diameter of the front impeller 3 to the inlet diameter of the rear impeller 4 is 1:1-1.15.

[0036] In some embodiments, there is a certain axial distance between the inlet side of the rear impeller 4 and the outlet side of the front impeller 3, and the axial distance range enables the fluid to transition smoothly and maintain sufficient flow momentum; preferably, the axial distance between the inlet side of the rear impeller 4 and the outlet side of the front impeller 3 is 0.8–1.1 times the inlet diameter of the rear impeller.

Claims

1. A two-stage pump, comprising a volute and a drive shaft, and a drive component for driving the drive shaft to rotate, characterized in that: The drive shaft includes a first rotating shaft and a second rotating shaft. At least one front impeller is provided on the outer side of the second rotating shaft, and a rear impeller is provided on the outer side of the second rotating shaft. A flow passage cavity is provided between the front impeller and the rear impeller, and a connecting component is provided in the flow passage cavity to connect the first rotating shaft and the second rotating shaft; The outer diameter of the front impeller is larger than the outer diameter of the rear impeller.

2. The two-stage pump according to claim 1, characterized in that: The volute is a split structure and can be disassembled and connected via fastening components.

3. The two-stage pump according to claim 1, characterized in that: The connecting assembly includes several specially designed lead screws, which are evenly distributed circumferentially.

4. The two-stage pump according to claim 3, characterized in that: The specially designed lead screw is made of high-strength cast iron or stainless steel.

5. The two-stage pump according to claim 1, characterized in that: The housing is provided with a liquid inlet and a liquid outlet. The liquid inlet is connected to the front impeller, and the liquid outlet is connected to the rear impeller.

6. The two-stage pump according to claim 1, characterized in that: An axial distance is provided between the inlet side of the rear impeller and the outlet side of the front impeller.

7. The two-stage pump according to claim 1, characterized in that: A gradually expanding flow channel is formed between the outlet diameter of the front impeller and the inlet diameter of the rear impeller.

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