Centrifugal pump structure capable of realizing minimum flow operation

Abstract

The utility model relates to a centrifugal pump structure capable of achieving operation with extremely small flow. The centrifugal pump structure can be suitable for centrifugal pumps which require extremely small operation flow and long-term stable operation. The structure comprises an inlet flange, a pump cylinder body, a suction pipe, an impeller, a guide vane, a shaft, a pump cover, an outlet flange, a fastener and the like, and the inlet flange, the outlet flange and the pump cover are installed on the pump body and used for sealing media in the pump; a conveying medium enters from the inlet flange, enters the impeller through the suction pipe, enters the guide vane after rotating and acting through the impeller, and enters the pump body through the guide vane runner. After a medium is conveyed into the pump body, one part of the medium returns to the suction pipe through the backflow hole in the suction pipe, and the other part of the medium is conveyed into the outlet pipeline through the outlet flange. Long-term stable operation of the centrifugal pump at a 1% design flow point can be achieved, and the design problem that the centrifugal pump needs a minimum flow operation working condition in actual engineering application is solved.

Description

Technical Field

[0001] This utility model relates to a centrifugal pump structure, specifically a centrifugal pump structure that can achieve operation at extremely low flow rates, solving the problem that ordinary centrifugal pumps cannot operate stably at extremely low flow rates. Background Technology

[0002] Currently, some power sector applications impose extremely stringent requirements on pump operating conditions, demanding long-term stable operation at 1% of the pump's design flow rate.

[0003] However, the normal, long-term stable operating flow range of centrifugal pumps is currently 30% to 120% of the design flow, which cannot meet this operating requirement. Centrifugal pumps will encounter the following problems when operating at an extremely low flow rate of 1%:

[0004] 1. The pump is operating with the outlet valve opening very small, resulting in significant pump vibration and noise.

[0005] 2. The pump is very inefficient when operating at extremely low flow rates;

[0006] 3. Due to its very low efficiency, the medium temperature rises during flow, which in turn leads to increased bearing temperature and shaft seal cavity temperature.

[0007] The above problems will cause irreversible damage to the pump's operation, and the pump cannot operate stably at extremely low flow rates for a long time. Utility Model Content

[0008] To address the aforementioned problems, the main objective of this invention is to provide a centrifugal pump structure capable of operating at extremely low flow rates, thus solving the problem that ordinary centrifugal pumps cannot operate stably at extremely low flow rates.

[0009] This utility model solves the above-mentioned technical problems through the following technical solution: a centrifugal pump structure that can achieve extremely low flow rate operation, the centrifugal pump structure that can achieve extremely low flow rate operation includes: a pump body, an inlet flange, an outlet flange, a pump cover, a suction pipe, and guide vanes; the inlet flange, the outlet flange, and the pump cover are all fixedly installed on the pump body by fasteners; an extended straight pipe type suction pipe is designed in front of the impeller inlet; the suction pipe is installed on the pump body by fasteners; the guide vanes are installed on the pump cover by fasteners; the suction pipe and the guide vanes are installed by a stop fit; multiple return holes are provided on the suction pipe.

[0010] In a specific embodiment of this utility model, the inlet flange is installed on the pump body by inlet flange fasteners, the outlet flange is installed on the pump body by outlet fasteners, and the pump cover is installed on the pump body by pump cover fasteners.

[0011] In a specific embodiment of this utility model, the suction pipe is installed on the pump body by suction pipe fasteners.

[0012] In a specific embodiment of this utility model, the guide vane is mounted on the pump cover by guide vane fasteners.

[0013] In a specific embodiment of this utility model, the pump barrel is integrally formed by forging.

[0014] In a specific embodiment of this utility model, the number of reflux holes is 2-8, arranged near the inlet of the pump body.

[0015] In a specific embodiment of this utility model, there are four reflux holes, which are arranged near the inlet of the pump body.

[0016] In a specific embodiment of this utility model, the diameter of the reflux hole ranges from 5 to 20 mm.

[0017] In a specific embodiment of this utility model, the guide vane is a radial guide vane structure using a closed casting method.

[0018] In a specific embodiment of this utility model, the impeller is a centrifugal torque blade structure, an integrally cast impeller, and the impeller is fixed to the shaft by an impeller nut.

[0019] The significant advantages of this invention are as follows: By setting multiple return holes on the suction pipe near the pump inlet, after the pumping medium enters the pump body, a portion of the medium returns to the suction pipe through the return holes, while the remaining portion is transported to the outlet pipe via the outlet flange. In the pump's hydraulic design, while maintaining the head, the flow rate is designed to be the outlet flow rate plus the total internal return flow rate. This allows the pump to operate at 30% of the design flow rate even when the outlet flow rate is only 1%, ensuring long-term stable operation of the pump unit at this operating point. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the overall structure of this utility model.

[0021] Figure 2 This is a schematic diagram of the inhalation tube in this utility model.

[0022] Figure 3 This is a schematic diagram of the medium flow direction.

[0023] The following are the names corresponding to the reference numerals in this utility model:

[0024] 1. Inlet flange; 2. Pump body; 3. Suction pipe fastener; 4. Outlet flange; 5. Suction pipe; 6. Guide vane; 7. Outlet flange fastener; 8. Guide vane fastener; 9. Impeller; 10. Pump cover fastener; 11. Pump cover; 12. Shaft; 13. Impeller nut; 14. Inlet flange fastener; 15. Return hole. Detailed Implementation

[0025] To make the technical means, creative features, objectives and effects of this utility model easier to understand, the following preferred embodiments of this utility model are given in conjunction with the accompanying drawings to illustrate the technical solution of this utility model in detail.

[0026] Figure 1 This is a schematic diagram of the overall structure of the present invention, as shown below. Figure 1 As shown: This utility model provides a centrifugal pump structure that can achieve extremely low flow rate operation. The structure includes a pump body 2, an inlet flange 1, an outlet flange 4, a pump cover 11, a suction pipe 5, and a guide vane 6. The inlet flange 1, the outlet flange 4, and the pump cover 11 are all fixedly installed on the pump body 2 by fasteners to seal the medium inside the pump. An extended straight pipe type suction pipe 5 is designed in front of the inlet of the impeller 9. The suction pipe 5 is installed on the pump body 2 by fasteners, and the guide vane 6 is installed on the pump cover 11 by fasteners. The suction pipe 5 and the guide vane 6 are installed by a stop fit.

[0027] Among them, the pump cylinder 2 adopts an enlarged cavity design and is manufactured by welding forgings, which is convenient to manufacture and has high dimensional accuracy.

[0028] The suction pipe 5 is installed on the pump body with fasteners, and the guide vane is installed on the pump cover with fasteners. The suction pipe and the guide vane are installed with a stop fit. An extended suction pipe is set in front of the impeller inlet inside the pump body. On the one hand, it has a flow stabilizing effect on the impeller inlet flow. On the other hand, it is convenient to make corresponding design openings on the inlet pipe to achieve extremely low flow rate operation. The impeller is fixed on the shaft with an impeller nut and rotates together with the shaft.

[0029] An extended suction pipe is installed inside the pump casing before the impeller inlet. This serves two purposes: firstly, it stabilizes the flow at the impeller inlet; secondly, it facilitates the design of appropriate openings in the inlet pipe to achieve operation at extremely low flow rates. The extended straight-pipe suction pipe, which is 5 to 10 times longer than that of a conventional centrifugal pump inlet, ensures the stability of the flow at the pump inlet.

[0030] The pump cylinder 2 is a welded part, and the flow passage is a uniform annular cavity, which can ensure the uniform flow of the conveyed medium within the annular cavity.

[0031] Both inlet flange 1 and outlet flange 4 are standard flanges, which ensures effective connection with the pump body and pipeline without requiring special design, thus guaranteeing versatility. Inlet flange 1 is installed on pump body 2 via inlet flange fastener 14, and outlet flange 4 is installed on pump body 2 via outlet fastener 7.

[0032] The pump cover 11 is integrally forged from a forging, which ensures the reliability of the pressure-bearing boundary and also guarantees the dimensional accuracy of its assembly with the pump barrel 2 and guide vane 6 through all machined surfaces. The pump cover 11 is installed on the pump barrel 2 by the pump cover fastener 10.

[0033] The suction pipe 5 is mounted on the pump body 2 via suction pipe fasteners 3. The suction pipe 5 is made of forging and has multiple reflux holes 15 on its wall, as detailed in the appendix. Figure 2 The suction pipe is equipped with multiple return holes to ensure effective backflow of the pump medium inside the pump casing. In practice, the number of return holes is 2-8, preferably 4, located near the pump inlet. The diameter of the return holes ranges from 5-20 mm. After the pump medium enters the pump body, a portion returns to the suction pipe through the return holes, while the other portion is transported to the outlet pipe via the outlet flange. In the pump's hydraulic design, while maintaining the head, the flow rate is designed to be the outlet flow rate plus the total internal backflow flow rate. This allows the pump to operate at 30% of the design flow rate when the outlet flow rate is at its minimum (1%), ensuring long-term stable operation at this point.

[0034] The guide vane 6 adopts a closed-type cast radial guide vane structure, and different hydraulic performances can be achieved by using different casting molds. It is installed on the pump cover 11 by guide vane fasteners 8, and is machined to ensure a stop fit with the suction pipe 5.

[0035] The impeller 9 adopts a centrifugal torque blade structure, is integrally cast, and achieves the required hydraulic performance through hydraulic design matching with the guide vane 6. It is fixed to the shaft 12 by the impeller nut 13 and rotates together with the shaft 12 to perform work.

[0036] Figure 3 This is a schematic diagram of the medium flow direction, such as... Figure 3 As shown: When this utility model is working, the shaft 12 rotates, driving the impeller 9 to rotate and do work on the conveying medium. The conveying medium enters the impeller 9 from the inlet flange 1 through the suction pipe 5. After the impeller 9 rotates and does work, it enters the guide vane 6 from the outlet of the impeller 9. The guide vane 6 converts the kinetic energy into pressure energy and enters the pump body 2 from the outlet of the guide vane 6. Inside the pump body 2, part of the conveying medium returns to the suction pipe 5 through the return hole on the suction pipe 5, and the other part of the conveying medium flows out of the pump through the outlet flange 4.

[0037] In this embodiment of the utility model, since a suction pipe 5 is provided and a return hole is designed in the suction pipe 5, the pump can operate at 30% of the design flow rate when the outlet flow rate is 1% of the minimum flow rate through hydraulic design, thereby ensuring that the pump set can operate stably at the minimum flow rate condition point for a long time.

[0038] The foregoing has shown and described the basic principles, main features, and advantages of this utility model. Those skilled in the art should understand that this utility model is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of this utility model. Various changes and modifications can be made to this utility model without departing from its spirit and scope, and all such changes and modifications fall within the scope of protection of this utility model as defined by the appended claims and their equivalents.

Claims

1. A centrifugal pump structure capable of realizing a minimum flow operation, characterized by: The centrifugal pump structure capable of realizing minimum flow operation comprises a pump barrel, an inlet flange, an outlet flange, a pump cover, a suction pipe and a guide vane.

2. The centrifugal pump structure capable of realizing minimal flow operation according to claim 1, characterized in that: The inlet flange is installed on the pump barrel through an inlet flange fastener, the outlet flange is installed on the pump barrel through an outlet fastener, and the pump cover is installed on the pump barrel through a pump cover fastener.

3. The centrifugal pump structure capable of realizing minimal flow operation according to claim 1, characterized in that: The suction pipe is installed on the pump barrel through a suction pipe fastener.

4. The centrifugal pump structure capable of realizing minimal flow operation according to claim 1, characterized in that: The guide vane is installed on the pump cover through a guide vane fastener.

5. The centrifugal pump structure capable of realizing minimal flow operation according to claim 1, characterized in that: The pump barrel is integrally formed by forging.

6. The centrifugal pump structure capable of realizing minimal flow operation according to claim 1, characterized in that: The number of the backflow holes is 2-8, which are arranged near the inlet of the pump barrel.

7. The centrifugal pump structure capable of realizing minimal flow operation according to claim 1, characterized in that: The number of the backflow holes is 4, which are arranged near the inlet of the pump barrel.

8. The centrifugal pump structure capable of realizing minimal flow operation according to claim 1, characterized in that: The diameter of the backflow hole ranges from 5 mm to 20 mm.

9. The centrifugal pump structure capable of realizing minimal flow operation according to claim 1, characterized in that: The guide vane is a radial guide vane structure formed by closed casting.

10. The centrifugal pump structure capable of realizing minimal flow operation according to claim 1, characterized in that: The impeller is a centrifugal torque blade structure integrally formed by casting, and the impeller is fixed on the shaft through an impeller nut.

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