Two-stage low-flow high-lift centrifugal pump

Abstract

The utility model discloses a two-stage small flow high-lift centrifugal pump belongs to part flow pump technical field, including pump body, primary impeller, secondary impeller, interstage partition, pump cover and pump shaft, interstage partition divides pump cavity into primary pump cavity and secondary pump cavity, and the pump shaft is through pump cover and interstage partition and is assembled fixed with primary impeller and second impeller, be equipped with primary outlet flow channel, transition flow channel no.

Description

Technical Field

[0001] This utility model relates to the field of partial flow pump technology, and in particular to a two-stage low-flow-rate high-lift centrifugal pump. Background Technology

[0002] Small-flow, high-lift pumps are designed for low-flow, heavy-duty applications, primarily used in the oil, petrochemical, and natural gas processing industries. Partial-flow pumps, due to their high efficiency, are widely used in the design of small-lift, high-flow pumps. They employ partial-flow design theory, where only a portion of the liquid flowing inside the pump is output through the diffuser at the pump outlet, while the remaining liquid flows in a forced rotational motion with the open impeller, thus achieving the desired low-flow, high-lift delivery.

[0003] However, for certain applications requiring higher heads, single-stage partial flow pumps cannot meet the head requirements. In such cases, a two-stage partial flow pump is needed. Existing two-stage pump structures typically consist of a primary impeller chamber and a secondary impeller chamber separated by a stage partition within the pump body. These two chambers are connected by an external bypass pipe. The primary impeller in the primary chamber draws fluid in through the pump inlet and delivers it to the secondary impeller chamber via the bypass pipe. The fluid is then discharged from the pump outlet by the secondary impeller in the secondary chamber, completing the secondary fluid transport and increasing the pump's head. However, the external bypass pipe is an independent component outside the pump body, adding to the pump's size and resulting in a large, complex, and aesthetically unappealing design. Another option is a one-time casting process that forms a transition channel connecting the two impeller chambers within the pump body. However, casting this transition channel is difficult, leading to a low one-time molding rate and increased production costs for the entire two-stage partial flow pump. Utility Model Content

[0004] The purpose of this invention is to address the shortcomings of existing technologies by proposing a two-stage low-flow-rate high-lift centrifugal pump that reduces production costs and ensures no increase in overall volume.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: A two-stage low-flow, high-lift centrifugal pump includes a pump body, a first-stage impeller, a second-stage impeller, a stage spacer, a pump cover, and a pump shaft. The pump body is connected to the pump cover. The stage spacer is fixedly disposed within the pump cavity enclosed by the pump body and the pump cover. The pump cavity is divided into a first-stage pump cavity for assembling the first-stage impeller and a second-stage pump cavity for assembling the second-stage impeller. The pump shaft passes through the pump cover and the stage spacer in sequence and is assembled and fixed to the first-stage and second-stage impellers. The first-stage and second-stage impellers are symmetrically arranged on both sides of the stage spacer. The pump body has a first-stage outlet channel penetrating the pump body along a first direction and a second-stage outlet channel penetrating the pump body along a second direction. A transition channel 1 penetrates the pump body in a directional direction, and a transition channel 2 penetrates the pump body in a third direction and sequentially connects the primary outlet channel and the transition channel 1. The pump cover is provided with a secondary inlet channel that penetrates the pump cover radially, and the inner end of the secondary inlet channel has a suction channel connected to the secondary pump chamber. The inner end of the primary outlet channel is connected to the primary pump chamber. The inner end of the transition channel 2 faces the pump cover and is connected to the outer end of the secondary inlet channel. The outer ends of the primary outlet channel, the outer ends of the transition channel 1, and the outer ends of the transition channel 2 are sealed by a plug. By setting a through-type primary outlet flow channel, transition flow channel one, and transition flow channel two on the pump body, with transition flow channel two connecting the primary outlet flow channel and transition flow channel one, and sealing the outer ends of the three with a plug, a transition channel is formed on the pump body for the fluid to flow out of the primary pump chamber. A radially through-type secondary inlet flow channel is set on the pump cover, allowing the fluid to enter the secondary pump chamber along the transition channel, completing the secondary conveying. The transition channel is machined on the pump body and pump cover by cutting, which is simple to process, does not occupy the external space of the pump body, and ensures that the overall volume of the pump does not increase. The shape of the transition channel is not visible from the outside, making the product more aesthetically pleasing. Compared with adding a casting transition channel at the same time, its casting process is simpler, has a higher yield, and reduces the corresponding production cost.

[0006] The suction channel is located at the center of the pump cover and is arranged in a ring shape on the outside of the pump shaft. The connection between the suction channel and the secondary pump chamber forms the impeller suction port. The ring-shaped suction channel improves the suction performance at the secondary impeller.

[0007] The interface between the suction channel and the secondary inlet channel has an inner guiding arc surface, and the impeller suction port has an outer guiding arc surface.

[0008] The secondary inlet channel is gradually widened along the direction of fluid flow.

[0009] The second direction is the same as the direction of the secondary inlet channel, and the third direction is parallel to the axial direction of the pump shaft.

[0010] The stage partition plate has a primary internal flow channel at the corresponding position to the primary impeller for wrapping the primary impeller, and the stage partition plate has a secondary internal flow channel at the corresponding position to the secondary impeller for wrapping the secondary impeller. The primary internal flow channel is connected to the primary outlet flow channel via a first channel, and the secondary internal chute is connected to the outlet channel of the pump body via a second channel.

[0011] At least one of the second channel and the outlet channel of the pump body is configured as a stepped channel structure, which includes a plurality of unit straight holes with decreasing diameters arranged along the fluid flow direction, and the unit straight holes are connected by transition holes of frustoconical shape. The stepped channel structure is easy to manufacture and meets the hydraulic requirements of the diffuser in a partial flow pump.

[0012] The primary and secondary impellers are identical open impellers, each including a hub and several straight blades arranged in a circumferential array on the hub. The hub has support plates for mounting the straight blades, which are toothed along the center, forming open flow channels between adjacent toothed support plates. This radially open impeller design reduces disc friction losses and improves pump efficiency.

[0013] The stage partition plate has a through hole in the middle. The hubs of the first-stage impeller and the second-stage impeller are mated and disposed within the through hole. Throttling bushings are fixed to the outer sides of the hubs of the first-stage and second-stage impellers. A throttling bushing is fixed within the through hole. A labyrinth sealing groove is provided on the outer wall of the throttling bushing or the inner wall of the throttling bushing. The labyrinth sealing method reduces leakage and pressure relief between stages.

[0014] This utility model has the following beneficial effects: By setting a through-type primary outlet flow channel, a transition flow channel one, and a transition flow channel two on the pump body, and the transition flow channel two connecting the primary outlet flow channel and the transition flow channel one, and sealing the outer ends of the three with a plug, a transition channel is formed on the pump body for the fluid to flow out of the primary pump chamber. A radially through-type secondary inlet flow channel is set on the pump cover, allowing the fluid to enter the secondary pump chamber along the transition channel to complete the secondary conveying. The transition channel is machined on the pump body and pump cover by cutting, which is simple to process, does not occupy the external space of the pump body, and does not increase the overall appearance size of the pump. The shape of the transition channel is not visible from the outside, making the product more aesthetically pleasing. Its casting process does not require casting the transition channel, thus simplifying the casting process, increasing the yield, and reducing the corresponding production cost. Attached Figure Description

[0015] To more clearly illustrate the technical solutions of the embodiments of this utility model, the drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this utility model and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0016] Figure 1 This is a schematic diagram of the structure of this utility model; Figure 2 This is a perspective view of the pump body in the utility model. Figure 3 For along Figure 2 A cross-sectional view along the BB direction; Figure 4 For along Figure 2 A cross-sectional view along the CC direction; Figure 5 For along Figure 2 A partial sectional view along the DD direction; Figure 6 This is a perspective view of the pump cover in the utility model. Figure 7 This is a cross-sectional view of the pump cover in the utility model. Figure 8 This is a schematic diagram of the structure of the intermediate partition plate of this utility model; Figure 9 This is a structural schematic diagram of the intermediate partition plate of this utility model from another angle.

[0017] Figure 10 This is a perspective view of the present invention; Figure 11 This is a front view of the first-stage impeller in this utility model; Figure 12 This is a cross-sectional view of the first-stage impeller in this utility model; Figure 13 for Figure 1 A magnified view of part A in the image.

[0018] Reference numerals: 1. Pump body; 101. Primary outlet flow channel; 102. Transition flow channel one; 103. Transition flow channel two; 104. Outlet channel; 2. Pump cover; 201. Secondary inlet flow channel; 202. Suction flow channel; 203. Inner guide arc surface; 204. Outer guide arc surface; 3. Pump shaft; 4. Primary impeller; 401. Hub; 402. Support plate; 403. Straight blade; 404. Open flow channel; 5. Secondary impeller; 6. Stage spacer; 601. Primary inner flow groove; 602. Secondary inner flow groove; 603. First channel; 604. Second channel; 605. Through hole; 7. Mechanical seal component; 8. Plug component; 9. Throttling bushing; 901. Labyrinth seal groove; 10. Throttling bushing. Detailed Implementation

[0019] To make the objectives, technical solutions, and advantages of the embodiments of this utility model clearer, the technical solutions of the embodiments of this utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this utility model, and not all embodiments. The components of the embodiments of this utility model described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0020] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0021] In the description of this utility model, it should be understood that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the utility model product is in use, or the orientation or positional relationship commonly understood by those skilled in the art. They are only used to facilitate the description of this utility model and to simplify the description, and are not intended to indicate or imply that the device or component referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this utility model.

[0022] like Figure 1As shown, this utility model provides a two-stage small-flow, high-lift centrifugal pump, including a pump body 1, a first-stage impeller 4, a second-stage impeller 5, a stage spacer 6, a pump cover 2, and a pump shaft 3. The pump body 1 and pump cover 2 are connected, forming a pump chamber. The stage spacer 6 is fixedly disposed within the pump chamber, dividing it into a first-stage pump chamber for assembling the first-stage impeller 4 and a second-stage pump chamber for assembling the second-stage impeller 5. The pump shaft 3 passes through the pump cover 2 and stage spacer 6 sequentially and is assembled and fixed to the first-stage impeller 4 and the second impeller. Similar to existing technologies, a mechanical seal 7 is installed at the penetration position of the pump cover 2. The structure of the mechanical seal 7 is the same as in existing technologies and will not be described in detail here. In this design, the first-stage impeller 4 and the second-stage impeller 5 are symmetrically arranged on both sides of the stage spacer 6. This symmetrical arrangement aims to achieve a self-balancing effect on the axial force acting on the pump shaft 3, while the residual axial force is borne by the angular bearing in the mechanical seal 7, thereby improving the reliability of the two-stage partial flow pump during operation.

[0023] like Figures 2-5 As shown, the pump body 1 is provided with a primary outlet flow channel 101 penetrating the pump body 1 in a first direction, a transition flow channel 102 penetrating the pump body 1 in a second direction, and a transition flow channel 103 penetrating the pump body 1 in a third direction and sequentially connecting the primary outlet flow channel 101 and the transition flow channel 102. The pump cover 2 is provided with a secondary inlet flow channel 201 penetrating the pump cover 2 in a radial direction, and the inner end of the secondary inlet flow channel 201 has a suction flow channel 202 connected to the secondary pump chamber. The inner end of the primary outlet flow channel 101 is connected to the primary pump chamber. The inner end of the transition flow channel 103 is arranged facing the side wall of the pump cover 2 and is connected to the outer end of the secondary inlet flow channel 201. The outer ends of the primary outlet flow channel 101, the outer ends of the transition flow channel 102, and the outer ends of the transition flow channel 103 are sealed by a plug 8. A primary outlet flow channel 101 and a transition flow channel 102, which are connected through the pump body 1, are connected to and exit the pump body 1 via a second transition flow channel 103 parallel to the axial direction. The outer ends of the three channels are sealed in sequence by three plugs 8, thus providing a transition channel on the pump body 1 for the fluid to flow out of the primary pump chamber. A similarly through-type secondary inlet flow channel 201 is provided on the pump cover 2, allowing the fluid to enter the secondary pump chamber along the transition channel to complete the secondary transport. The above-mentioned through-type channels can be machined on the pump body 1 and the pump cover 2 by cutting. The machining is simple, does not occupy the external space of the pump body 1, and does not increase the overall appearance size of the pump. The shape of the transition channel is not visible from the outside, making the product more aesthetically pleasing. At the same time, due to its casting process, there is no need to cast the transition channel, thus simplifying the casting process, increasing the yield, and reducing the corresponding production cost.

[0024] In this plan, such as Figure 2As shown, the first direction is parallel to the outlet channel 104 of the pump body 1, the second direction is the same as the direction of the secondary inlet channel 201, and the third direction is parallel to the circumferential direction of the pump shaft 3 to reduce the kinetic energy loss of the fluid in the transition channel. The plug 8 used in this scheme is a special plug for centrifugal pumps, which completes the sealing connection at the channel port through the threaded end and the sealing ring.

[0025] Specifically, the stage spacer 6 is fixed to the inside of the pump cover 2 with bolts, such as... Figure 9 As shown, it has a secondary internal flow channel 602 on the side facing the pump cover 2. The secondary impeller 5 is located in the secondary pump chamber enclosed by the pump cover 2 and the secondary internal flow channel 602. A second channel 604 is provided through the stage partition plate 6. The inner end of the second channel 604 is connected to the secondary internal flow channel 602, and its outer end is as shown. Figure 10 As shown, it is connected to the outlet channel 104 of the pump body, such as Figure 8 As shown, the stage partition plate 6 has a first-stage inner flow channel 601 on the side facing away from the pump cover 2. The first-stage impeller 4 is located in the first-stage pump chamber surrounded by the pump body 1 and the first-stage inner flow channel 601. A first channel 603 is provided through the stage partition plate 6. The inner end of the first channel 603 is connected to the first-stage inner flow channel 601, and its outer end is connected to the first-stage outlet flow channel 101 on the pump body 1.

[0026] like Figure 1 and Figure 3 As shown, the pump chamber is provided with a first stepped groove, a second stepped groove, and a third stepped groove in sequence along the direction away from the opening. The stage partition plate 6 is formed on the outer side and fits with the first stepped groove. The pump cover 2 is formed on the outer side and fits with the second stepped groove. The pump cover 2 is formed on the outer side and fits with the third stepped groove. The outer side of the pump cover 2 is fixed to the pump body 1 by a bracket. Sealing rings are provided between the first stepped groove and the first stepped part, and between the second stepped groove and the second stepped part, to ensure the sealing of the pump chamber.

[0027] Similar to existing technologies, to reduce the air binding effect during pump body 1 operation, an exhaust port is provided at the top of pump body 1, and a drain port is provided at the bottom of pump body 1 to facilitate pump maintenance in winter. Both the exhaust port and drain port are sealed using centrifugal pump-specific plugs. Specifically, in this solution, as... Figure 1 As shown, there are at least two exhaust ports. One exhaust port extends from the channel on the pump body 1 into the first-stage internal flow channel 601 to exhaust the first-stage pump chamber. The other exhaust port extends from the channel on the pump body 1 and the channel on the stage partition plate 6 into the second-stage internal flow channel 602 to drain the second-stage pump chamber. The number and arrangement of the drainage ports are the same as those of the exhaust ports, and will not be described in detail here.

[0028] like Figure 6 and Figure 7As shown, the suction channel 202 is located at the center of the pump cover 2 and is arranged in a ring shape on the outside of the pump shaft 3. The connection between the suction channel 202 and the secondary pump chamber forms an impeller suction port. The arrangement of the ring-shaped suction channel 202 improves the suction performance at the secondary impeller 5. At the same time, in order to reduce the kinetic energy loss of the fluid, the interface between the suction channel 202 and the secondary inlet channel 201 has an inner guide arc surface 203, and the impeller suction port has an outer guide arc surface 204. More preferably, the secondary inlet channel 201 is gradually widened along the fluid flow direction, so that the fluid entering the secondary inlet channel 201 smoothly transitions into the suction channel 202.

[0029] like Figure 10 As shown, at least one of the second channel 604 and the outlet channel 104 of the pump body 1 is configured as a stepped channel structure. The stepped channel structure includes several unit straight holes of different diameters arranged along the fluid flow direction. The diameter of each unit straight hole decreases along the fluid flow direction, and the unit straight holes are connected by a frustum-shaped conical hole. The stepped channel structure is easy to manufacture and also meets the hydraulic requirements of the diffuser in a partial flow pump.

[0030] like Figure 11 and Figure 12 As shown, the first-stage impeller 4 and the second-stage impeller 5 are open impellers with the same structure, including a hub 401 and a plurality of straight blades 403 arranged in a circular array on the hub 401. The support plates 402 for mounting the straight blades 403 on the hub 401 are toothed along the center, and an open flow channel 404 is formed between adjacent toothed support plates 402. The radially open impeller can reduce the disc friction loss of the impeller, thereby improving the efficiency of the pump.

[0031] like Figure 13 As shown, the stage partition plate 6 has a through hole 605 in the middle. The hub 401 of the first-stage impeller 4 and the hub 401 of the second-stage impeller 5 are mated in the through hole 605. The second-stage pump chamber is a high-pressure zone relative to the first-stage pump chamber. There is a discharge channel between the through hole 605 and the two hubs 401. In order to reduce the discharge flow and pressure between stages, a throttling bushing 9 is fixed on the outside of the hub 401 of the first-stage impeller 4 and the hub 401 of the second-stage impeller 5. A throttling bushing 10 is fixed in the through hole 605. A labyrinth sealing groove 901 is provided on the outer wall of the throttling bushing 9 or the inner wall of the throttling bushing 10. In this embodiment, as shown... Figure 13 As shown, the labyrinth sealing groove 901 is formed on the outer wall of the throttling bushing 9.

[0032] In the production and processing of the two-stage partial flow pump in this technical solution, the transition channel between stages is processed by machining through channels at corresponding positions on the pump body 1, pump cover 2, and stage partition 6. The processing method is simple, with a high yield and low production cost. When assembling the pump body 1, it is only necessary to align the secondary inlet channel 201 on the pump cover 2 with the transition channel 102 on the pump body 1, align the first channel 603 on the stage partition 6 with the primary outlet channel 101 on the pump body 1, and align the second channel 604 on the stage partition 6 with the outlet channel 104 on the pump body 1. The shape of the transition channel is not visible from the outside of the assembled partial flow pump product, and the overall appearance size of the pump does not increase.

[0033] The above description is merely a preferred embodiment of this utility model and is not intended to limit the utility model. Various modifications and variations can be made to this utility model by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this utility model should be included within the protection scope of this utility model.

Claims

1. A two-stage low-flow-rate high-lift centrifugal pump, comprising a pump body, a first-stage impeller, a second-stage impeller, a stage spacer, a pump cover, and a pump shaft, wherein the pump body is connected to the pump cover, the stage spacer is fixedly disposed within the pump cavity enclosed by the pump body and the pump cover, the pump cavity is divided into a first-stage pump cavity for assembling the first-stage impeller and a second-stage pump cavity for assembling the second-stage impeller, and the pump shaft sequentially passes through the pump cover and the stage spacer and is assembled and fixedly mounted to the first-stage impeller and the second impeller, characterized in that, The primary impeller and the secondary impeller are symmetrically arranged on both sides of the stage partition plate. The pump body is provided with a primary outlet flow channel penetrating the pump body in a first direction, a transition flow channel one penetrating the pump body in a second direction, and a transition flow channel two penetrating the pump body in a third direction and sequentially connecting the primary outlet flow channel and the transition flow channel one. The pump cover is provided with a secondary inlet flow channel penetrating the pump cover radially, and the inner end of the secondary inlet flow channel has a suction flow channel connected to the secondary pump chamber. The inner end of the primary outlet flow channel is connected to the primary pump chamber. The inner end of the transition flow channel two is set towards the pump cover and is connected to the outer end of the secondary inlet flow channel. The outer ends of the primary outlet flow channel, the outer ends of the transition flow channel one, and the outer ends of the transition flow channel two are sealed by a plug.

2. The two-stage low-flow high-head centrifugal pump according to claim 1, characterized in that, The suction channel is located at the center of the pump cover and is arranged in a ring shape on the outside of the pump shaft. The connection between the suction channel and the secondary pump chamber forms an impeller suction port.

3. The two-stage low-flow high-head centrifugal pump according to claim 2, characterized in that, The interface between the suction channel and the secondary inlet channel has an inner guiding arc surface, and the impeller suction port has an outer guiding arc surface.

4. The two-stage low-flow high-head centrifugal pump according to claim 2 or 3, characterized in that, The secondary inlet channel is gradually widened along the direction of fluid flow.

5. The two-stage low-flow high-head centrifugal pump according to claim 1, characterized in that, The second direction is the same as the direction of the secondary inlet channel, and the third direction is parallel to the axial direction of the pump shaft.

6. The two-stage low-flow high-head centrifugal pump according to claim 1 or 2 or 3 or 5, characterized in that, The stage partition plate has a primary internal flow groove at the corresponding position to the primary impeller for wrapping the primary impeller, and the stage partition plate has a secondary internal flow groove at the corresponding position to the secondary impeller for wrapping the secondary impeller. The primary internal flow groove is connected to the primary outlet flow channel via a first channel, and the secondary internal flow groove is connected to the outlet channel of the pump body via a second channel.

7. The two-stage low-flow high-head centrifugal pump according to claim 6, characterized in that, At least one of the second channel and the outlet channel of the pump body is configured as a stepped channel structure, the stepped channel structure including a plurality of unit straight holes with decreasing diameters arranged along the fluid flow direction, and the unit straight holes are connected by a frustum-shaped conical hole.

8. The two-stage low-flow high-head centrifugal pump according to claim 1, characterized in that, The first-stage impeller and the second-stage impeller are open impellers with the same structure, including a hub and several straight blades arranged in a circular array on the hub. The support plates of the hub for mounting the straight blades are toothed along the center, and an open flow channel is formed between adjacent toothed support plates.

9. The two-stage low-flow high-head centrifugal pump according to claim 8, characterized in that, The stage partition plate has a through hole in the middle. The hub of the first stage impeller and the hub of the second stage impeller are mated in the through hole. Throttling bushings are fixed on the outer side of the hubs of the first stage impeller and the second stage impeller. Throttling bushings are fixed in the through hole. Labyrinth sealing grooves are provided on the outer wall of the throttling bushing or the inner wall of the throttling bushing.

Images