Multistage multiphase pump

Abstract

The utility model discloses a multi-stage multiphase pump, and relates to the technical field of pumps. One end of the rotating shaft penetrates through the bearing box and extends into the pump body; the spiral-flow type impeller and the first centrifugal impeller are rotationally arranged outside the rotating shaft in a sleeving manner and are arranged at intervals in the axial direction of the rotating shaft; the first centrifugal impeller is close to the bearing box, the spiral-flow type impeller is located at the rear end of the pump body, and the spiral-flow type impeller and the liquid inlet jointly define a cavity with the space size required by smooth circulation of a gas-liquid mixed medium; the partition plate is fixedly arranged on the inner wall of the pump body. An outlet of the spiral-flow type impeller communicates with an inlet of the first centrifugal impeller through a first transition flow channel, and an outlet of the first centrifugal impeller communicates with the liquid outlet. And the cavity is communicated with the first transition runner. The common phenomenon that a flow channel is blocked by air mass in a traditional centrifugal pump is avoided. Therefore, the conveying stability of the multi-stage multiphase pump to the gas-liquid two-phase medium is improved, and the adaptability of the multi-stage multiphase pump under different working conditions is higher.

Description

Technical Field

[0001] This application relates to the technical field of pumps, and particularly to a multistage mixed-flow pump. Background Art

[0002] In fields such as petroleum, natural gas, chemical industry, and new energy, the efficient transportation of gas-liquid two-phase media is a key link in the production process. As the mainstream equipment in this field, the traditional centrifugal gas-liquid mixed-flow pump is designed based on the dynamic characteristics of single-phase fluids, and the medium is worked on by the centrifugal force generated by the rotation of the impeller. However, under the conditions of low inlet pressure and high gas content, due to the non-uniform phase evolution of the gas-liquid two-phase flow in the impeller passage, gas coalescence occurs, forming discrete large air masses. These air masses block the continuous flow of the liquid phase and weaken the kinetic energy transfer, resulting in a sharp drop in pump efficiency or even the loss of work capacity, severely restricting its application in scenarios such as shale gas exploitation and deep-sea oil and gas transportation. Utility Model Content

[0003] The embodiments of this application solve the problems raised in the background art by providing a multistage mixed-flow pump.

[0004] The embodiments of this application provide a multistage mixed-flow pump, which includes a pump body, a bearing box, a swirl impeller, a first centrifugal impeller, a rotating shaft, a partition plate, and a mechanical seal assembly; an inlet and an outlet are respectively arranged at the front end and the top of the pump body, and the pump body is detachably connected to the bearing box; one end of the rotating shaft passes through the bearing box and extends into the pump body; both the swirl impeller and the first centrifugal impeller are rotatably sleeved outside the rotating shaft, and are both arranged at intervals along the axial direction of the rotating shaft, and are both located inside the pump body; the first centrifugal impeller is close to the bearing box, and the swirl impeller is located at the rear end of the pump body, and together with the inlet, encloses a cavity with a spatial size that meets the smooth flow requirements of the gas-liquid mixed medium; the partition plate is fixedly arranged on the inner wall of the pump body and is located between the swirl impeller and the first centrifugal impeller, and is used to separate the working areas where the swirl impeller and the first centrifugal impeller are located; the outlet of the swirl impeller is connected to the inlet of the first centrifugal impeller through a first transition flow path, and the outlet of the first centrifugal impeller is connected to the outlet; the cavity and the first transition flow path are connected; the mechanical seal assembly is arranged on the rotating shaft and is located inside the bearing box.

[0005] In a possible implementation manner, the multistage mixed-flow pump further includes a guide vane; the guide vane is fixedly arranged on the inner wall of the inlet and is used to guide the gas-liquid mixed medium into the inlet of the swirl impeller.

[0006] In a possible implementation, the multistage mixed-flow pump further includes a guide vane; the guide vane is arranged at the outlet of the first centrifugal impeller and is used to suppress the gas-phase separation caused by the sudden change in the flow velocity of the gas-liquid mixed medium.

[0007] In a possible implementation, the axial depth of the cavity is greater than the outlet width of the vortex impeller.

[0008] In a possible implementation, the multistage mixed-flow pump further includes a second centrifugal impeller; the second centrifugal impeller is rotatably sleeved on the outer wall of the rotating shaft and is located on the side of the first centrifugal impeller away from the vortex impeller. The outlet of the first centrifugal impeller is connected to the inlet of the second centrifugal impeller through a second transition flow channel, and the outlet of the second centrifugal impeller is connected to the liquid outlet.

[0009] In a possible implementation, the diameter of the rotating shaft gradually decreases in the direction from the bearing box to the pump body.

[0010] One or more technical solutions provided in the embodiments of the present application have at least the following technical effects:

[0011] The multistage mixed-flow pump provided in the embodiments of the present application includes a pump body, a bearing box, a vortex impeller, a first centrifugal impeller, a rotating shaft, a partition plate, and a mechanical seal assembly. The first-stage impeller adopted in the present application is a vortex impeller. This vortex impeller is arranged in a rear-contracted manner and is located at the rear end of the pump body. Together with the liquid inlet, it encloses a cavity with a relatively large volume. This unique design provides sufficient flow space for the gas-liquid mixed medium, effectively reduces the flow resistance of the gas-liquid mixed medium in the pump body, and makes the gas-liquid mixed medium flow more smoothly.

[0012] During the operation of the multistage mixed-flow pump, the rotational movement of the vortex impeller will generate two typical characteristic flow patterns:

[0013] One is the direct through-flow. After the gas-liquid mixed medium enters the inlet of the vortex impeller through the liquid inlet, under the driving of the strong centrifugal force, it continuously accelerates along the flow channel of the vortex impeller, and finally is discharged from the outlet of the vortex impeller into the first transition flow channel and directly enters the secondary first centrifugal impeller, where the energy conversion process is completed, and the pressure and velocity of the gas-liquid mixed medium are further increased.

[0014] The second is the circulating flow. Due to the large cavity between the swirl impeller and the liquid inlet, a part of the gas-liquid mixed medium will generate a reverse flow under the action of the centrifugal field, forming a reflux path pointing from the outlet of the swirl impeller to the cavity. After this part of the gas-liquid mixed medium re-enters the first transition flow channel through the cavity, it will participate in the subsequent work process and cooperate with the direct through-flow to jointly complete the transportation task of the gas-liquid mixed medium.

[0015] Analyzing in depth from the perspective of hydrodynamic mechanisms, the centrifugal effect generated when the swirl impeller rotates will form a pressure gradient field pointing axially towards the liquid inlet. This pressure distribution characteristic makes the pressure in the working area of the swirl impeller significantly higher than the cavity pressure in the area without the impeller. Driven by the pressure difference, the gas-phase medium will naturally migrate and accumulate towards the low-pressure area, forming an orderly flow trend of the gas-phase medium.

[0016] This migration effect has two significant technical advantages. On the one hand, it effectively avoids the problem of accumulation and blockage of the gas-phase medium in the flow channels of the swirl impeller. The timely migration of the gas-phase medium towards the low-pressure area ensures the smoothness of the flow channels in the swirl impeller, enabling the swirl impeller to continuously and stably do work and improving the working efficiency of the swirl impeller. On the other hand, the gas-phase medium accumulated in the low-pressure area of the cavity will be continuously affected by the circulating gas-liquid mixed medium. When the gas-liquid mixed medium with high kinetic energy returns from the outlet of the swirl impeller, a significant velocity gradient will be formed in the cavity. The shear stress generated by this velocity gradient can break the aggregated large-sized bubbles into micron-sized bubbles, effectively controlling the bubble size.

[0017] The broken micron-sized bubbles will be continuously entrained into the first transition flow channel under the synergistic action of the circulating flow and the through-flow, and evenly distributed at the inlet of the secondary first centrifugal impeller. Since the gas-liquid mixed medium has obtained the basic pressure energy through the swirl impeller at this time, and the bubble size is effectively controlled within the micron level, the common "gas mass blocking the flow channel" phenomenon in traditional centrifugal pumps can be avoided. This not only significantly improves the transportation stability of the multistage mixed transportation pump for gas-liquid two-phase media, but also makes the multistage mixed transportation pump more adaptable to different working conditions. This design realizes the controllable migration of the gas-phase medium and the active regulation of the bubble size through the organic combination of flow field reconstruction and pressure field regulation, providing a solid structural guarantee for the efficient and stable operation under gas-liquid mixed transportation conditions. In practical applications, when applied to high gas content and high head working conditions, the swirl impeller can effectively solve the problem that traditional centrifugal impellers cannot transport high gas content media, while the secondary first centrifugal impeller can solve the transportation requirement of high head. The two cooperate with each other to jointly ensure the efficient and stable operation of the multistage mixed transportation pump under complex working conditions. Description of the Drawings

[0018] To more clearly illustrate the technical solutions in the embodiments of the present application, the following will briefly introduce the drawings required for the description of the embodiments of the present application. Obviously, the drawings in the following description are some embodiments of the present application. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0019] Figure 1 It is a schematic structural diagram of a multistage mixed-flow pump provided by an embodiment of the present application.

[0020] Icon: 1 - pump body; 11 - liquid inlet; 12 - liquid outlet; 13 - cavity; 2 - bearing box; 3 - swirl impeller; 4 - first centrifugal impeller; 5 - rotating shaft; 6 - mechanical seal assembly; 7 - deflector; 8 - guide vane; 9 - partition; 10 - first transition flow channel. Specific embodiments

[0021] The following will clearly and completely describe the technical solutions in the embodiments of the present application with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are some, but not all, of the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative efforts fall within the scope of protection of the present application.

[0022] In the description of the embodiments of the present application, it should be noted that the orientation or positional relationship indicated by the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the embodiments of the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation to the present application. The terms "first", "second", "third" are only used for descriptive purposes and cannot be construed as indicating or implying relative importance. In addition, the terms "installation", "connection", "connection" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected, or indirectly connected through an intermediate medium, and it can be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the embodiments of the present application can be understood according to specific circumstances.

[0023] The embodiments of the present application provide a multistage mixed-flow pump, as Figure 1As shown in the figure. The multistage mixed-flow pump includes a pump body 1, a bearing box 2, a vortex impeller 3, a first centrifugal impeller 4, a rotating shaft 5, a partition 9, and a mechanical seal assembly 6. The front end and the top of the pump body 1 are respectively provided with a liquid inlet 11 and a liquid outlet 12, and the pump body 1 is detachably connected to the bearing box 2. One end of the rotating shaft 5 passes through the bearing box 2 and extends into the pump body 1. The vortex impeller 3 and the first centrifugal impeller 4 are both rotatably sleeved outside the rotating shaft 5, and are both arranged at intervals along the axial direction of the rotating shaft 5, and are both located in the pump body 1. The first centrifugal impeller 4 is close to the bearing box 2, and the vortex impeller 3 is located at the rear end of the pump body 1, and together with the liquid inlet 11, they enclose a cavity 13 with a spatial dimension sufficient for the smooth flow of the gas-liquid mixed medium, that is, a relatively large cavity 13. The partition 9 is fixedly arranged on the inner wall of the pump body 1 and is located between the vortex impeller 3 and the first centrifugal impeller 4, and is used to separate the working areas where the vortex impeller 3 and the first centrifugal impeller 4 are located. The outlet of the vortex impeller 3 is connected to the inlet of the first centrifugal impeller 4 through a first transition flow channel 10, and the outlet of the first centrifugal impeller 4 is connected to the liquid outlet 12. The cavity 13 and the first transition flow channel 10 are connected. The mechanical seal assembly 6 is arranged on the rotating shaft 5 and is located in the bearing box 2.

[0024] It should be noted that the first-stage impeller adopted in this application is the vortex impeller 3. The vortex impeller 3 is arranged in a retracted manner and is located at the rear end of the pump body 1. Together with the liquid inlet 11, it encloses a cavity 13 with a relatively large volume. This unique design provides sufficient flow space for the gas-liquid mixed medium, effectively reduces the flow resistance of the gas-liquid mixed medium in the pump body 1, and makes the gas-liquid mixed medium flow more smoothly.

[0025] During the operation of the multistage mixed-flow pump, the rotation of the vortex impeller 3 will generate two typical characteristic flow patterns:

[0026] One is the direct through-flow. After the gas-liquid mixed medium enters the inlet of the vortex impeller 3 through the liquid inlet 11, under the drive of the strong centrifugal force, it continuously accelerates along the flow channel of the vortex impeller 3, and finally is discharged from the outlet of the vortex impeller 3 into the first transition flow channel 10, and then directly enters the secondary first centrifugal impeller 4, where the energy conversion process is completed, and the pressure and speed of the gas-liquid mixed medium are further increased.

[0027] The other is the circulating flow. Due to the existence of a relatively large cavity 13 between the vortex impeller 3 and the liquid inlet 11, part of the gas-liquid mixed medium will generate a reverse flow under the action of the centrifugal field, forming a return path pointing from the outlet of the vortex impeller 3 to the cavity 13. After this part of the gas-liquid mixed medium re-enters the first transition flow channel 10 through the cavity 13, it will participate in the subsequent work process and cooperate with the direct through-flow to jointly complete the transportation task of the gas-liquid mixed medium.

[0028] From an in-depth analysis of the hydrodynamic mechanism, the centrifugal effect generated when the swirl impeller 3 rotates will form a pressure gradient field pointing axially towards the liquid inlet 11. This pressure distribution characteristic makes the pressure in the working area of the swirl impeller 3 significantly higher than the pressure in the cavity 13 in the area without the impeller. Driven by the pressure difference, the gas-phase medium will naturally migrate and accumulate towards the low-pressure area, forming an orderly gas-phase medium flow trend.

[0029] This migration effect has two significant technical advantages. On the one hand, it effectively avoids the problem of accumulation and blockage of the gas-phase medium in the flow channel of the swirl impeller 3. The gas-phase medium migrates to the low-pressure area in a timely manner, ensuring the smoothness of the flow channel of the swirl impeller 3, enabling the swirl impeller 3 to continuously and stably do work, and improving the working efficiency of the swirl impeller 3. On the other hand, the gas-phase medium accumulated in the low-pressure area of the cavity 13 will be continuously affected by the circulating flow gas-liquid mixed medium. When the gas-liquid mixed medium with high kinetic energy returns from the outlet of the swirl impeller 3, a significant velocity gradient will be formed in the cavity 13. The shear stress generated by this velocity gradient can break the aggregated large-sized bubbles into micron-sized bubbles, effectively controlling the bubble size.

[0030] Under the synergistic action of the circulating flow and the through-flow, the broken micron-sized bubbles will be continuously entrained into the first transition flow channel 10 and evenly distributed at the inlet of the secondary first centrifugal impeller 4. Since the gas-liquid mixed medium has obtained the basic pressure energy through the swirl impeller 3 at this time, and the bubble size is effectively controlled within the micron range, the common "gas mass blocking the flow channel" phenomenon in traditional centrifugal pumps can be avoided. This not only significantly improves the transportation stability of the multi-stage mixed transportation pump for gas-liquid two-phase media, but also makes the multi-stage mixed transportation pump more adaptable to different working conditions. This design realizes the controllable migration of the gas-phase medium and the active regulation of the bubble size through the organic combination of flow field reconstruction and pressure field regulation, providing a solid structural guarantee for the efficient and stable operation under gas-liquid mixed transportation conditions. In practical applications, when applied to high gas content and high head working conditions, the swirl impeller 3 can effectively solve the problem that traditional centrifugal impellers cannot transport high gas content media, while the secondary first centrifugal impeller 4 can solve the transportation demand of high head. The two cooperate with each other to jointly ensure the efficient and stable operation of the multi-stage mixed transportation pump under complex working conditions.

[0031] Specifically, a receiving chamber is provided on one side of the partition 9 of the present application facing the first centrifugal impeller 4. The first centrifugal impeller 4 partially extends into the partition 9 and has a gap with the receiving chamber, making the layout of the entire device more compact.

[0032] In the embodiment of the present application, the multistage mixed-flow pump further includes a deflector 7. The deflector 7 is fixedly arranged on the inner wall of the liquid inlet 11 and is used to guide the gas-liquid mixed medium into the inlet of the swirl impeller 3. Through the effective guidance of the deflector 7 on the gas-liquid mixed medium, the present application effectively improves the flow characteristics of the gas-liquid mixed medium entering the inlet of the swirl impeller 3, makes the gas-liquid mixing more uniform and orderly, reduces the disorder and impact loss of the gas-liquid mixed medium at the inlet of the swirl impeller 3, and at the same time reduces the formation of "lump-shaped" and "block-shaped" gas phases, thereby improving the suction efficiency and energy conversion efficiency of the swirl impeller 3 for the gas-liquid mixed medium.

[0033] In the embodiment of the present application, the mechanical seal assembly 6 includes a main seal ring and a secondary seal ring arranged back-to-back, and the main seal ring and the secondary seal ring form an isolation cavity. Both the main seal ring and the secondary seal ring are sleeved on the outer wall of the rotating shaft 5. The isolation cavity is connected to an external isolation liquid circulation system. The isolation liquid in the isolation cavity of the present application reduces the wear speed of the main seal ring and the secondary seal ring and prolongs the overall service life of the mechanical seal assembly 6.

[0034] In the embodiment of the present application, the multistage mixed-flow pump further includes a guide vane 8. The guide vane 8 is arranged at the outlet of the first centrifugal impeller 4 and is used to suppress the gas phase separation caused by the sudden change in the flow rate of the gas-liquid mixed medium. When the gas-liquid mixed medium is thrown out at a high speed from the outlet of the first centrifugal impeller 4, its flow rate and flow direction will change sharply, and this sudden change in the flow rate is extremely likely to cause the separation phenomenon of the gas phase and the liquid phase media. The presence of the guide vane 8 can play a key regulating role. Through its unique flow channel design and the guidance of the fluid flow direction, it effectively suppresses the tendency of gas phase separation caused by the sudden change in the flow rate of the gas-liquid mixed medium. At the same time, the guide vane 8 can also rectify and stabilize the gas-liquid mixed medium reasonably, ensuring that the gas-liquid mixed medium can continue to flow to the subsequent stage more uniformly and stably, thereby avoiding the escape of the gas phase medium at the liquid outlet 12 due to local pressure changes or flow disorders, and ensuring the gas-liquid transportation efficiency and stability during the operation of the entire equipment.

[0035] In the embodiment of the present application, the axial depth of the cavity 13 is greater than the outlet width of the swirl impeller 3, which can effectively increase the flow-through space of the gas-liquid mixed medium and further improve its flow-through capacity. This design also strengthens the circulating flow effect and makes the gas-liquid mixed medium mix more evenly.

[0036] In the embodiment of the present application, the multistage mixed-flow pump further includes a second centrifugal impeller. The second centrifugal impeller is rotatably sleeved on the outer wall of the rotating shaft 5 and is located on the side of the first centrifugal impeller 4 away from the swirl impeller 3. The outlet of the first centrifugal impeller 4 is communicated with the inlet of the second centrifugal impeller through a second transition flow path, and the outlet of the second centrifugal impeller is communicated with the liquid outlet 12. By the series connection of the first centrifugal impeller 4 and the second centrifugal impeller in the present application, multiple pressurizations of the gas-liquid mixed medium in the multistage mixed-flow pump and stirring to break bubbles are achieved, which can effectively increase the head of the multistage mixed-flow pump, enable the multistage mixed-flow pump to better adapt to the requirements of the conveying pressure of the gas-liquid mixed medium under different working conditions, and also can improve the conveying efficiency of the multistage mixed-flow pump to a certain extent, ensuring that the gas-liquid mixed medium is more stably and efficiently conveyed from the liquid inlet 11 to the liquid outlet 12.

[0037] In the embodiment of the present application, the diameter of the rotating shaft 5 gradually decreases from the bearing housing 2 to the pump body 1. In the pump body 1 part, due to the action of the gas-liquid mixed medium flow and the pumping pressure, the rotating shaft 5 needs to bear large radial and axial forces. The design of its decreasing diameter makes the rotating shaft 5 have a smaller cross-sectional area in the pump body 1 part, so that it can more effectively resist the action of these forces and ensure the stable operation of the multistage mixed-flow pump.

[0038] The various embodiments in this specification are described in a progressive manner. For the same or similar parts between the various embodiments, reference can be made to each other. The key point of each embodiment is to illustrate the differences from other embodiments.

[0039] The above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit the present application. Although the present application has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements on some or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the present application.

Claims

1. A multistage mixed-flow pump, characterized in that, It includes a pump body (1), a bearing box (2), a swirl impeller (3), a first centrifugal impeller (4), a rotating shaft (5), a partition plate (9) and a mechanical seal assembly (6); An inlet (11) and an outlet (12) are respectively arranged at the front end and the top of the pump body (1), and the pump body (1) is detachably connected to the bearing box (2); One end of the rotating shaft (5) passes through the bearing box (2) and extends into the pump body (1); Both the swirl impeller (3) and the first centrifugal impeller (4) are rotatably sleeved outside the rotating shaft (5), and are both arranged at intervals along the axial direction of the rotating shaft (5), and are both located in the pump body (1); The first centrifugal impeller (4) is close to the bearing box (2), and the swirl impeller (3) is located at the rear end of the pump body (1), and together with the inlet (11), they enclose a cavity (13) with a spatial dimension required for the smooth flow of the gas-liquid mixed medium; The partition plate (9) is fixedly arranged on the inner wall of the pump body (1) and is located between the swirl impeller (3) and the first centrifugal impeller (4) for separating the working areas where the swirl impeller (3) and the first centrifugal impeller (4) are located; The outlet of the swirl impeller (3) is communicated with the inlet of the first centrifugal impeller (4) through a first transition flow channel (10), and the outlet of the first centrifugal impeller (4) is communicated with the outlet (12); The cavity (13) is communicated with the first transition flow channel (10); The mechanical seal assembly (6) is arranged on the rotating shaft (5) and is located in the bearing box (2).

2. The multiphase pump according to claim 1, wherein It further includes a deflector (7); The deflector (7) is fixedly arranged on the inner wall of the inlet (11) for guiding the gas-liquid mixed medium into the inlet of the swirl impeller (3).

3. The multiphase pumping unit according to claim 1, wherein, It further includes a guide vane (8); The guide vane (8) is arranged at the outlet of the first centrifugal impeller (4) for suppressing the gas phase separation caused by the sudden change in the flow rate of the gas-liquid mixed medium.

4. The multiphase pump according to claim 1, characterized in that The axial depth of the cavity (13) is greater than the outlet width of the swirl impeller (3).

5. The multiphase pump according to claim 1, wherein It further includes a second centrifugal impeller; The second centrifugal impeller is rotatably sleeved on the outer wall of the rotating shaft (5) and is located on the side of the first centrifugal impeller (4) away from the swirl impeller (3). The outlet of the first centrifugal impeller (4) is communicated with the inlet of the second centrifugal impeller through a second transition flow channel, and the outlet of the second centrifugal impeller is communicated with the outlet (12).

6. The multiphase pumping unit according to claim 1, wherein, The diameter of the rotating shaft (5) gradually decreases from the bearing box (2) to the direction of the pump body (1).

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