Anti-cavitation structure of multi-stage centrifugal pump

Abstract

The utility model discloses an anti-cavitation structure of a multistage centrifugal pump, which comprises an outer cylinder, a suction section, a water guide sleeve and an inducer, a water pump inlet is arranged on the outer cylinder, the suction section is arranged in the outer cylinder, a water inlet channel is arranged at the position of the suction section corresponding to the water pump inlet, a cavity is arranged in the suction section, the water guide sleeve is arranged in the cavity of the suction section, and the inducer is arranged in the water guide sleeve. A through hole I is formed in the end face of the right side of the suction section and communicated with the inner cavity, an inducer is arranged on the pump shaft in the suction section, a through hole II is formed in the circumference of the water guide sleeve and located on the left side of the inducer, a first-stage impeller is arranged on the pump shaft on the right side of the inducer, and a second-stage impeller is arranged on the pump shaft on the right side of the first-stage impeller. The middle section is connected with the suction section, a guide vane is arranged in the middle section, and a first-stage sealing ring is arranged at the position, corresponding to the first-stage impeller, of the suction section. According to the utility model, the liquid pressure at the inlet of the inducer can be improved, so that the anti-cavitation performance of the inducer and the first-stage impeller is improved.

Description

Technical Field

[0001] The utility model relates to the technical field of fluid mechanical pumps, in particular to an anti-cavitation structure of a multi-stage centrifugal pump. Background Art

[0002] During the operation of a centrifugal pump, the centrifugal pump can only operate stably when the device cavitation margin is greater than the required cavitation margin of the centrifugal pump. If the device cavitation margin is less than or close to the required cavitation margin of the centrifugal pump, cavitation will occur in the centrifugal pump, causing damage to the flow-through components. Therefore, corresponding measures must be taken when designing a water feed pump to increase the required cavitation margin of the centrifugal pump. The existing technology is to increase the required cavitation margin of the centrifugal pump by adding an inducer in front of the first-stage impeller. If simply adding an inducer cannot meet the operating requirements, cavitation may still occur. Utility Model Content

[0003] In order to solve the above problems, the utility model provides a multi-stage centrifugal pump anti-cavitation structure.

[0004] The purpose of the utility model is achieved in the following ways:

[0005] A multi-stage centrifugal pump anti-cavitation structure comprises an outer cylinder 2, a suction section 3, a water guide sleeve 4 and an inducer 5. The outer cylinder 2 is provided with a water pump inlet A, the outer cylinder 2 is provided with a suction section 3, a water inlet channel B is provided at a position corresponding to the water pump inlet A in the suction section 3, a cavity H is provided in the suction section 3, the water guide sleeve 4 is provided in the cavity H of the suction section 3, a through hole IG is provided on the right end face of the suction section 3, the through hole IG is communicated with the cavity H, and a through hole IG is provided on the suction section 3. An inducer 5 is mounted on the pump shaft 1 inside, a through hole ⅡJ is provided on the circumference of the water guide jacket 4, the through hole ⅡJ is located on the left side of the inducer 5, a first-stage impeller 8 is mounted on the pump shaft 1 on the right side of the inducer 5, a secondary impeller 10 is mounted on the pump shaft 1 on the right side of the first-stage impeller 8, a middle section 7 is mounted in the outer cylinder 2, the middle section 7 is connected to the suction section 3, a guide vane 9 is mounted in the middle section 7, and a first-stage sealing ring 6 is provided at a position corresponding to the first-stage impeller 8 on the suction section 3.

[0006] One end of the through hole IIJ is communicated with the cavity H, and the other end faces the entrance of the inducer wheel 5. The through hole IIJ has an angle of 20° to 40° with the axial direction.

[0007] The number of through holes IIJ on the circumference of the water guide sleeve 4 is 1 to 3 times the number of blades of the inducer 5 .

[0008] The total cross-sectional area of ​​the through holes IIJ is 0.05 to 0.1 times the outlet area of ​​the first-stage impeller 8 .

[0009] The total cross-sectional area of ​​the through hole IIJ is 0.2 to 0.5 times the area of ​​the through hole IG.

[0010] A sealing ring is provided between the water guide jacket 4 and the suction section 3 .

[0011] A sealing ring is provided between the outer cylinder 2 and the suction section 3 .

[0012] By adopting the above technical solution, the outlet of the first-stage impeller, through hole I, the inner cavity of the suction section, through hole II, the inducer, and the inlet of the first-stage impeller form a circulation channel. When the centrifugal pump is running, the liquid enters the suction section from the water pump inlet, flows to the first-stage impeller through the inducer, and the pressure of the liquid at the impeller outlet increases after the impeller does work. At this time, a part of the high-pressure liquid enters the inner cavity of the suction section through through hole I, and then enters the front end of the inducer inlet through through hole II to mix with the low-pressure liquid flowing from the water pump inlet, thereby increasing the liquid pressure at the inlet of the inducer, so that the anti-cavitation performance of the inducer and the first-stage impeller can be improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 It is a structural schematic diagram of the utility model.

[0014] Figure 2 It is a working principle diagram of the utility model.

[0015] Figure 3 It is a schematic diagram of the water guide sleeve structure. DETAILED DESCRIPTION

[0016] The technical solution of this patent is further described in detail below in conjunction with specific implementation methods.

[0017] like Figure 1 As shown, a multi-stage centrifugal pump anti-cavitation structure comprises a pump shaft 1 and an outer cylinder 2, wherein a water pump inlet A is arranged on the outer cylinder 2, a suction section 3 is arranged in the outer cylinder 2, a water inlet channel B is arranged at a position corresponding to the water pump inlet A in the suction section 3, a cavity H is arranged in the suction section 3, a water guide sleeve 4 is arranged in the cavity H of the suction section 3, a through hole IG is arranged on the right end face of the suction section 3, the through hole IG is communicated with the cavity H, an inducer 5 is arranged on the pump shaft 1 in the suction section 3, a through hole ⅡJ is arranged on the circumference of the water guide sleeve 4, the through hole ⅡJ is located on the left side of the inducer 5, a first-stage impeller 8 is arranged on the pump shaft 1 on the right side of the inducer 5, a secondary impeller 10 is arranged on the pump shaft 1 on the right side of the first-stage impeller 8, a middle section 7 is arranged in the outer cylinder 2, the middle section 7 is connected to the suction section 3, a guide vane 9 is arranged in the middle section 7, and a first-stage sealing ring 6 is arranged at a position corresponding to the first-stage impeller 8 on the suction section 3. A sealing ring is provided between the water guide sleeve 4 and the suction section 3. A sealing ring is provided between the outer cylinder 2 and the suction section 3.

[0018] The first-stage impeller outlet, through hole I, the inner cavity of the suction section, through hole II, the inducer, and the first-stage impeller inlet form a circulation channel. Figure 2As shown in the figure, when the centrifugal pump is running, the liquid flows along the solid line direction, enters the suction section from the water pump inlet, flows to the first-stage impeller through the inducer, and the impeller outlet liquid pressure increases after the impeller does work. At this time, a part of the high-pressure liquid flows along the dotted line direction, enters the inner cavity of the suction section through the through hole Ⅰ, and then enters the front end of the inducer inlet through the through hole Ⅱ to mix with the low-pressure liquid flowing from the water pump inlet, thereby increasing the liquid pressure at the inducer inlet, so that the anti-cavitation performance of the inducer and the first-stage impeller can be improved.

[0019] One end of the through hole IIJ is connected to the cavity H, and the other end is toward the inlet of the inducer 5. The through hole IIJ is at an angle of 20° to 40° with the axial direction. Figure 3 This is conducive to the liquid flowing back from the outlet of the first-stage impeller 8 to the inlet of the inducer 5 to flow into the impeller along with the liquid at the inlet of the centrifugal pump, without backflow.

[0020] The number of through holes IIJ on the circumference of the water guide sleeve 4 is 1 to 3 times the number of blades of the inducer 5. This ensures that the liquid flowing from the outlet of the first-stage impeller 8 back to the inlet of the inducer 5 can be fully mixed, and the liquid impact on the inducer 5 in the circumferential direction is also symmetrical.

[0021] The total cross-sectional area of ​​the through hole IIJ is 0.05 to 0.1 times the outlet area of ​​the first-stage impeller 8. The total cross-sectional area of ​​the through hole IIJ is 0.2 to 0.5 times the area of ​​the through hole IG. In this way, the liquid flow rate from the outlet of the first-stage impeller 8 back to the inlet of the inducer 5 can be controlled to be no more than 3% to 5% of the total flow rate of the centrifugal pump, thereby ensuring the efficiency of the centrifugal pump.

[0022] A sealing ring is provided between the water guide sleeve 4 and the suction section 3 to prevent the cavity H of the suction section 3 from directly penetrating with the flow channel C of the inducer 5, thereby ensuring that the high-pressure water in the cavity H of the suction section 3 flows into the flow channel C of the inducer 5 through the circumferential through hole IIJ of the water guide sleeve 4.

[0023] The utility model can be implemented when designing new products, and is particularly valuable when modifying existing units. Without changing the existing unit configuration and the main structure of the centrifugal pump, the internal structure of the centrifugal pump can be optimized to increase the necessary cavitation margin of the centrifugal pump to meet the operating needs.

Claims

1. A multi-stage centrifugal pump anti-cavitation structure, comprising an outer cylinder (2), a suction section (3), a water guide jacket (4) and an inducer (5), characterized in that: The outer cylinder (2) has a water pump inlet (A), the outer cylinder (2) is provided with a suction section (3), a water inlet passage (B) is provided at a position of the suction section (3) corresponding to the water pump inlet (A), a cavity (H) is provided in the suction section (3), a water guide sleeve (4) is provided in the cavity (H) of the suction section (3), a through hole I (G) is provided on the right end surface of the suction section (3), the through hole I (G) is communicated with the cavity (H), an inducer (5) is provided on the pump shaft (1) in the suction section (3), and a water guide sleeve (4) is provided in the cavity (H) of the suction section (3). A through hole II (J) is provided on the circumference of the pump shaft (4), the through hole II (J) being located on the left side of the inducer (5), a first-stage impeller (8) being mounted on the pump shaft (1) on the right side of the inducer (5), a secondary impeller (10) being mounted on the pump shaft (1) on the right side of the first-stage impeller (8), a middle section (7) being mounted in the outer cylinder (2), the middle section (7) being connected to the suction section (3), a guide vane (9) being mounted in the middle section (7), and a first-stage sealing ring (6) being provided at a position corresponding to the first-stage impeller (8) on the suction section (3).

2. The multi-stage centrifugal pump anti-cavitation structure according to claim 1, characterized in that: One end of the through hole II (J) is connected to the cavity (H), and the other end faces the inlet of the inducer wheel (5). The through hole II (J) is at an angle of 20° to 40° with the axial direction.

3. The multi-stage centrifugal pump anti-cavitation structure according to claim 1, characterized in that: The number of through holes II (J) on the circumference of the water guide sleeve (4) is 1 to 3 times the number of blades of the inducer (5).

4. The multi-stage centrifugal pump anti-cavitation structure according to claim 3, characterized in that: The total cross-sectional area of ​​the through hole II (J) is 0.05 to 0.1 times the outlet area of ​​the first-stage impeller (8).

5. The multi-stage centrifugal pump anti-cavitation structure according to claim 3, characterized in that: The total cross-sectional area of ​​the through hole II (J) is 0.2 to 0.5 times the area of ​​the through hole I (G).

6. The multi-stage centrifugal pump anti-cavitation structure according to claim 1, characterized in that: A sealing ring is provided between the water guide sleeve (4) and the suction section (3).

7. The multi-stage centrifugal pump anti-cavitation structure according to claim 1, characterized in that: A sealing ring is provided between the outer cylinder (2) and the suction section (3).

Images