Vertical high-flow low-cavitation condensate pump

Abstract

The utility model relates to a vertical large-flow low-cavitation condensate pump belongs to mechanical engineering pump technical field. Motor is provided on motor support, and the output end of motor is connected pump shaft through shaft coupling, and the lower end of motor support is detachably connected with the seat of spitting, and the seat of spitting is provided with pump export, the axial mechanical seal of pump shaft and axial force balance mechanism, and the seat of spitting is detachably connected with pump outer cylinder body, and pump outer cylinder body is provided with pump import, and two inner cylinder bodies are arranged in pump outer cylinder body, and upper guide bearing group and lower guide bearing group are arranged on pump shaft, and the flange end surface of inner cylinder body at lower end is connected with pump body through fastener, and is provided with recess for inlaying first sealing ring on the major surface of pump body, and pump body is connected with suction horn through fastener, and guide vane is arranged in pump body, and impeller is installed in guide vane, and inducer is installed at the front end of impeller. The utility model can effectively improve the cavitation performance of pump under the premise of not increasing the length and burying depth of outer cylinder body obviously.

Description

Technical Field

[0001] This utility model belongs to the field of mechanical engineering pump technology, specifically relating to a vertical high-flow-rate low-cavitation condensing pump. Background Technology

[0002] In a condensate recovery system, the condensate pump is an important pump used in the condensate recovery system and is an important component of the entire condensate system. Under high vacuum conditions, the condensate pump extracts condensate from the hot well of the condenser and delivers water at a saturation temperature close to the condenser pressure to participate in the water circulation of the entire steam turbine power generation process.

[0003] In the efficient power generation of waste heat gas, high-temperature and ultra-high-pressure gas power generation is a widely adopted new technology. Examples include small steam turbines in power plants and high-temperature and ultra-high-pressure gas power generation boilers, all of which are ultra-high-pressure boilers. Conventional horizontal centrifugal pumps and ordinary vertical centrifugal pumps cannot meet the cavitation performance requirements of condensate systems for recovery and water supply.

[0004] Vertical, high-flow, low-cavitation (NPSH) condensate pumps, referred to as vertical suspended pumps in the American Petroleum Institute (API) 610 standard, are vertical double-casing pumps. Because the pump's flow passages are all installed below ground level, they are unaffected by sunlight, air, and drive equipment such as motors, resulting in minimal temperature rise. Furthermore, the required net positive suction head (NPSHR) can be increased by increasing the burial depth to meet the plant's NPSHA requirements. For these reasons, they are widely used, particularly in power plant condensate transportation.

[0005] In recent years, power plants (thermal power, nuclear power, etc.) have shortened the burial depth of vertical suspended condensate pumps, a key auxiliary equipment, due to considerations such as energy conservation, efficiency improvement, and investment costs (due to geological structure and other factors). However, this has led to frequent issues such as flow interruptions and unstable operation during pump operation. Disassembly of the pump revealed cavitation at the impeller inlet, particularly near the impeller, exhibiting pitting, erosion, and electrochemical corrosion.

[0006] Currently, widely used vertical multistage bag pumps are often buried underground. Their first-stage impeller structure mostly adopts a suction type, with the lowest point underwater located at the end of the pump shaft. The insertion depth and the length of the outer casing are determined based on the net positive suction head (NPSHA) of the device. For projects where the pump burial depth L is not required, achieving the goal is not difficult (e.g., lengthening the inner connecting pipe L1 and the outer casing length L2). However, power plants and other applications (due to geological factors, investment costs, etc.) do not allow for lengthening the outer casing. If a horizontal centrifugal pump is used, its space requirement increases by more than three times, and the site layout becomes difficult to design. Utility Model Content

[0007] This invention addresses the aforementioned problems and overcomes the shortcomings of existing technologies by providing a vertical, high-flow, low-cavitation condensate pump. This invention can effectively improve the pump's cavitation performance without significantly increasing the length of the outer cylinder or the embedment depth.

[0008] To achieve the above objectives, the present invention adopts the following technical solution.

[0009] This utility model provides a vertical high-flow-rate low-cavitation condensate pump, including a motor, a motor bracket, a discharge seat, and an outer pump cylinder. The motor is mounted on the motor bracket, and its output end is connected to a pump shaft via a coupling. The lower end of the motor bracket is detachably connected to the discharge seat. The discharge seat includes a pump outlet, an axial mechanical seal for the pump shaft, and an axial force balancing mechanism. The discharge seat is detachably connected to the outer pump cylinder, and the outer pump cylinder has a pump inlet. Two inner cylinders are housed within the outer pump cylinder, and the two inner cylinders are fastened together. The pump shaft is equipped with an upper guide bearing assembly and a lower guide bearing assembly. The flange end face of the inner cylinder at the lower end is connected to the pump body by fasteners. A groove for embedding a first sealing ring is provided on the large end face of the pump body. The pump body is connected to the suction port by fasteners. A guide vane is provided in the pump body. An impeller is installed in the guide vane. The impeller is connected to the drive pump shaft. An inducer wheel is installed at the front end of the impeller. A bushing is provided at the front end of the inducer wheel. The bushing, the inducer wheel, and the impeller are fastened to the pump shaft as a whole by a lock nut.

[0010] Furthermore, the inducer is installed at the front end of the first-stage impeller to transfer the severely cavitation area within the pump from the inducer to the impeller.

[0011] Furthermore, the guide vane is provided with a circular blind hole, and a limiting pin is embedded in the suction horn. The limiting pin cooperates with the circular blind hole to prevent the guide vane from rotating.

[0012] Furthermore, the suction horn is also provided with a positioning pin for circumferentially limiting the guide vane.

[0013] Furthermore, the pump shaft has a threaded hole at its end, and the locking nut is locked in place by a set screw.

[0014] Furthermore, the suction horn is provided with an impeller sealing ring and a first slit screw for fixing the impeller sealing ring.

[0015] Furthermore, the guide vane is provided with a guide vane bushing and a second saddle screw for fixing the guide vane bushing.

[0016] Furthermore, a second sealing ring is provided at the end face where the pump body connects to the suction flare, and a pressure cap is also provided on the large end face of the pump body.

[0017] Furthermore, the upper guide bearing assembly is disposed within the inner cylinder, and the lower guide bearing assembly is disposed within the suction horn.

[0018] The beneficial effects of this utility model.

[0019] This invention employs a structure that adds an inducer before the first-stage impeller, significantly improving the pump's cavitation performance and increasing its net positive suction head (NPSHr). This shifts the area of ​​severe cavitation within the pump from the inducer to the first-stage impeller, thus meeting the low NPSH requirements without significantly increasing the burial depth of the outer casing. The precise installation and reliable operation of the internal flow components are ensured by the limiting pin structure between the guide vanes and the suction inlet, and by the locking nuts and set screws used to secure the impeller, inducer, and shaft sleeve to the pump shaft, reducing pump vibration. The rational structural design makes it particularly suitable for applications such as power plants where geological conditions or cost constraints prevent increasing the pump's burial depth, achieving high flow rate, low cavitation, and stable operation. Attached Figure Description

[0020] To make the technical problems solved, the technical solutions, and the beneficial effects of this utility model clearer, the present utility model will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present utility model and are not intended to limit the present utility model.

[0021] Figure 1 This is a schematic diagram of the overall cross-sectional structure of this utility model.

[0022] Figure 2 This is an exploded disassembly diagram of the flow-through component of this utility model.

[0023] The markings in the diagram are as follows: 1 is the motor, 2 is the motor bracket, 3 is the coupling, 4 is the pump shaft, 5 is the axial mechanical seal, 6 is the axial force balancing mechanism, 7 is the discharge seat, 8 is the pump outlet, 9 is the pump outer cylinder, 10 is the pump inlet, 11 is the inner cylinder, 12 is the upper guide bearing assembly, 13 is the impeller, 14 is the inducer, 15 is the shaft sleeve, 16 is the lock nut, 17 is the set screw, 18 is the pump body, 19 is the suction bell mouth, 20 is the guide vane, 21 is the guide vane bushing, 22 is the second seam screw, 23 is the first sealing ring, 24 is the limit pin, 25 is the impeller sealing ring, 26 is the first seam screw, 27 is the second sealing ring, 28 is the lower guide bearing assembly, 29 is the gland, and 30 is the positioning pin. Detailed Implementation

[0024] As shown in the accompanying drawings, this embodiment provides a vertical, high-flow, low-cavitation condensate pump with an overall vertical suspension structure. The motor 1 is fixedly mounted on the motor bracket 2, and the output shaft of the motor 1 is connected to the upper end of the pump shaft 4 via a coupling 3 for power transmission. The lower end of the motor bracket 2 is detachably connected to the discharge seat 7 via bolts or other fasteners. The discharge seat 7 integrates a pump outlet 8 with a flange for connecting to external pipelines. Furthermore, the discharge seat 7 also contains an axial mechanical seal 5 for sealing the pump shaft 4, and an axial force balancing mechanism 6 for balancing the axial force generated during pump operation.

[0025] The lower part of the discharge seat 7 is detachably connected to the upper end of the pump outer shell 9 via a flange. A pump inlet 10 is provided on the side of the pump outer shell 9. Inside the pump outer shell 9, two inner shells 11 are installed vertically connected, and they are joined together by fastening bolts to form the inner shell of the pump. The pump shaft 4 passes through the center of the inner shell 11, and upper guide bearing assembly 12 and lower guide bearing assembly 28 are respectively provided at the upper and lower positions along its length to support and guide the rotation of the pump shaft 4.

[0026] The flange end face of the inner cylinder 11 at the lowest end is connected to the upper end face of the pump body 18 by fastening bolts. A groove is formed on the large end face of the pump body 18, in which a first sealing ring 23 is embedded to ensure the sealing at the connection with the inner cylinder 11. The lower end of the pump body 18 is connected to the suction port 19 by fastening bolts, and a second sealing ring 27 is provided at the end face where the two are connected to ensure sealing. A lower guide bearing assembly 28 is installed inside the suction port 19 to support the lowest end of the pump shaft 4. An impeller sealing ring 25 is also installed on the suction port 19 and fixed by a first saddle bolt 26.

[0027] The core internal flow components of the pump body 18 include a guide vane 20, an impeller 13, and an inducer 14. The guide vane 20 is fixedly installed inside the pump body 18, and its outer side is engaged with a corresponding hole on the suction port 19 via a limiting pin 24 to prevent circumferential rotation of the guide vane 20. To further ensure the limiting effect, a positioning pin 30 can also be provided for auxiliary limiting. A guide vane bushing 21 is installed inside the guide vane 20 and fixed by a second saddle screw 22. The impeller 13 is installed inside the guide vane 20 and fixedly sleeved on the pump shaft 4. An inducer 14 is installed at the inlet front end of the impeller 13. A shaft sleeve 15 is sleeved on the front end (i.e., the lower end) of the inducer 14. The impeller 13, inducer 14, and shaft sleeve 15 are sequentially installed on the pump shaft 4, and then pressed from the shaft end by a locking nut 16 to secure them together with the pump shaft 4. To further prevent the locking nut 16 from loosening, a threaded hole is machined on the shaft end of the pump shaft 4, and a set screw 17 is screwed in to tighten the locking nut 16. A pressure cap 29 is also installed on the large end face of the pump body 18.

[0028] The working principle of this vertical high-flow-rate low-cavitation condensate pump is as follows: Motor 1 drives pump shaft 4 to rotate, which in turn drives inducer 14 and impeller 13 to rotate together. Fluid enters the annular space between the outer cylinder 9 and inner cylinder 11 from pump inlet 10, flows downward to suction bell mouth 19, and passes through inducer 14 and impeller 13 in sequence. As an axial flow impeller, inducer 14 first performs work on the fluid, increasing its pressure, thereby improving the cavitation conditions at the inlet of impeller 13. It transfers the area prone to severe cavitation from the impeller 13, which mainly performs work, to inducer 14, significantly reducing the pump's required net positive suction head (NPSHr). After being pressurized, the fluid is collected by guide vane 20 and its kinetic energy is converted before flowing into the flow channel of inner cylinder 11, and finally discharged from pump outlet 8 through discharge seat 7.

[0029] It is understood that the above specific description of this utility model is only used to illustrate this utility model and is not limited to the technical solutions described in the embodiments of this utility model. Those skilled in the art should understand that modifications or equivalent substitutions can still be made to this utility model to achieve the same technical effect; as long as the use needs are met, they are all within the protection scope of this utility model.

Claims

1. A vertical high-flow-rate low-cavitation condensate pump, comprising a motor (1), a motor support (2), a discharge seat (7), and an outer cylinder (9), characterized in that, The motor (1) is mounted on the motor bracket (2). The output end of the motor (1) is connected to the pump shaft (4) via a coupling (3). The lower end of the motor bracket (2) is detachably connected to the discharge seat (7). The discharge seat (7) is provided with a pump outlet (8), an axial mechanical seal (5) for the pump shaft (4), and an axial force balancing mechanism (6). The discharge seat (7) is detachably connected to the pump outer cylinder (9). The pump outer cylinder (9) is provided with a pump inlet (10). The pump outer cylinder (9) contains two inner cylinders (11), which are connected by fasteners. The pump shaft (4) is provided with an upper guide bearing assembly (12) and a lower guide bearing assembly (28). The flange end face of the inner cylinder (11) at the end is connected to the pump body (18) by fasteners, and a groove for embedding the first sealing ring (23) is provided on the large end face of the pump body (18). The pump body (18) is connected to the suction horn (19) by fasteners. A guide vane (20) is provided inside the pump body (18). An impeller (13) is installed inside the guide vane (20). The impeller (13) is connected to the pump shaft (4). An inducer wheel (14) is installed at the front end of the impeller (13). A bushing (15) is provided at the front end of the inducer wheel (14). The bushing (15), the inducer wheel (14) and the impeller (13) are fastened to the pump shaft (4) as a whole by a locking nut (16).

2. The vertical high-flow-rate low-cavitation condensate pump according to claim 1, characterized in that, The inducer (14) is installed at the front end of the first impeller (13) to transfer the severely cavitation area in the pump from the inducer (14) to the impeller (13).

3. A vertical high-flow-rate low-cavitation condensate pump according to claim 1, characterized in that, The guide vane (20) is provided with a circular blind hole, and the suction horn (19) is inlaid with a limiting pin (24). The limiting pin (24) cooperates with the circular blind hole to prevent the guide vane (20) from rotating.

4. A vertical high-flow-rate low-cavitation condensate pump according to claim 3, characterized in that, The inlet (19) is also provided with a positioning pin (30) for circumferentially limiting the guide vane (20).

5. A vertical high-flow-rate low-cavitation condensate pump according to claim 1, characterized in that, The pump shaft (4) has a threaded hole at its shaft end, and the locking nut (16) is locked and fixed by a set screw (17).

6. A vertical high-flow-rate low-cavitation condensate pump according to claim 1, characterized in that, The intake horn (19) is provided with an impeller (13) sealing ring and a first slit screw (26) for fixing the impeller (13) sealing ring.

7. A vertical high-flow-rate low-cavitation condensate pump according to claim 1, characterized in that, The guide vane (20) is provided with a guide vane (20) bushing and a second saddle screw (22) for fixing the guide vane (20) bushing.

8. A vertical high-flow-rate low-cavitation condensate pump according to claim 1, characterized in that, A second sealing ring (27) is provided at the end face where the pump body (18) connects to the suction horn (19), and a pressure cap (29) is also provided on the large end face of the pump body (18).

9. A vertical high-flow-rate low-cavitation condensate pump according to claim 1, characterized in that, The upper guide bearing assembly (12) is disposed inside the inner cylinder (11), and the lower guide bearing assembly (28) is disposed inside the suction horn (19).

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