A high-pressure multistage centrifugal pump with low pressure fluctuation and low noise

Abstract

The embodiments of the present disclosure relate to a multi-stage centrifugal pump with low pressure fluctuation and low noise. The centrifugal pump includes a cylinder, a shaft, a balance drum and a bushing. The shaft is disposed in the cylinder and is configured to drive the impeller on the shaft to rotate so that the medium flows from the inlet of the centrifugal pump to the outlet of the centrifugal pump. The balance drum is circumferentially disposed on the shaft and is configured to at least partially balance the axial force exerted by the medium on the impeller, the balance drum rotates with the shaft, and a coating is disposed on the radial outer surface. The bushing is arranged in coordination with the coating of the balance drum and forms a combination with the bushing frame and is installed on the radial inner side of the end cover, wherein the bushing is made of a wear-resistant composite material and the end cover is fixedly disposed on the cylinder. According to the embodiments of the present disclosure, the pressure fluctuation and noise of the centrifugal pump can be reduced.

Description

Technical Field

[0001] Example embodiments of the present disclosure relate generally to the field of pumps, and more particularly to a high-pressure multi-stage centrifugal pump capable of achieving low pressure fluctuation and low noise. Background Art

[0002] Centrifugal pumps are common pumps in industry. In the traditional multi-stage centrifugal pump design, the balance drum component composed of a balance drum and a bushing is used to balance the axial force. Extending along the flow direction of the gap between the balance drum and the bushing, the pressure gradually decreases. A small amount of the medium that passes through the impeller passes through the balance drum gap and flows back to the first-stage impeller through the return pipe. There are two main sources of hydrodynamic noise in centrifugal pumps. One is the noise caused by the high-speed water jet flowing out of the impeller, and the other is the noise caused by the high-speed water jet flowing out of the balance drum gap. The latter factor is often ignored. Especially after the centrifugal pump has been running for a period of time, the gap between the balance drum and the bushing will gradually increase over time. At this time, the water outlet speed increases, resulting in increased pressure fluctuations and noise. In addition, during the operation of the centrifugal pump, due to the radial fluctuations of the pump shaft under the radial force, the gap between the balance drum and the bushing also fluctuates. In the most extreme case, the single-sided gap becomes zero, and collision may occur. These factors cause the leaked water flow to have different speeds, which further aggravates the pressure fluctuations in the centrifugal pump, and further increases the noise of the centrifugal pump during use.

[0003] Therefore, there is an urgent need for an improved centrifugal pump that can effectively reduce the pressure fluctuation caused by the high-speed water flow flowing out of the balance drum gap, thereby further reducing the noise of the centrifugal pump. Summary of the invention

[0004] In general, example embodiments of the present disclosure provide a centrifugal pump that aims to solve the above-mentioned and / or other potential problems.

[0005] The embodiment of the present disclosure relates to a centrifugal pump. The centrifugal pump comprises a cylinder; a shaft, which is arranged in the cylinder and configured to drive the impeller on the shaft to rotate so that the medium flows from the inlet of the centrifugal pump to the outlet of the centrifugal pump; a balance drum, which is circumferentially arranged on the shaft and configured to at least partially balance the axial force applied by the medium on the impeller, the balance drum rotates with the shaft, and a coating is arranged on the radial outer surface; and a bushing, which is arranged in cooperation with the coating of the balance drum and forms a combination with a bushing frame and is installed on the radial inner side of the end cover, wherein the bushing is made of a wear-resistant composite material, and the end cover is fixedly arranged on the cylinder.

[0006] According to the embodiments of the present disclosure, low pressure fluctuation of the centrifugal pump can be achieved, which not only makes the operation of the centrifugal pump more stable and reliable, but also can significantly reduce the noise generated during the operation.

[0007] In some embodiments, the centrifugal pump further comprises a muffler, which is mounted to the end cover and disposed radially outside the bushing frame, and the muffler comprises an annular bevel, the radial dimension of the annular bevel on the side close to the impeller is smaller than the radial dimension on the side away from the impeller, so as to form a medium retention area between the annular bevel and the end cover. In this way, the formation of vortex and its harmful effects can be suppressed.

[0008] In some embodiments, the muffler cover further comprises one or more muffler holes, which are circumferentially arranged in the middle of the annular slope of the muffler cover. In this way, the muffler effect can be further improved without affecting the overall strength of the muffler cover.

[0009] In some embodiments, the bushing holder is connected to the end cover, and the radial inner side of the bushing holder supports the bushing. In this way, when the bushing needs to be replaced, the bushing holder can be retained for continued use to control operation and maintenance costs.

[0010] In some embodiments, there is an interference fit between the bushing frame and the bushing. In this way, the bushing frame and the bushing can be firmly assembled.

[0011] In some embodiments, the radial outer side of the bushing holder includes a first side section close to the impeller and a second side section close to the muffler, and a first distance between the first side section and the axis of the shaft is less than a second distance between the second side section and the axis. In this way, a stepped radial outer side surface can be formed to facilitate installation and removal of the bushing holder.

[0012] In some embodiments, the radial gap between the coating and the bushing of the balance drum includes an inlet area, a groove area, and an outlet area, wherein the inlet area has a narrowing cross section along the flow direction of the medium, and the outlet area has a gradually expanding cross section along the flow direction of the medium. In this way, the pressure fluctuation and noise of the flow can be reduced.

[0013] In some embodiments, the groove area includes a plurality of groove units that are repeatedly arranged. In this way, the noise reduction effect can be further improved.

[0014] In some embodiments, each groove unit includes at least two grooves, each groove includes a vertical surface, a fillet surface and an inclined surface, and wherein the corresponding vertical surfaces of different grooves in the at least two grooves extend perpendicular to the axis of the shaft, but the depths of different grooves are different from each other; wherein the fillet radii of the corresponding fillet surfaces of the different grooves are different from each other; and wherein the corresponding inclined surfaces of the different grooves extend at the same angle relative to the axis of the shaft, but the lengths of the corresponding inclined surfaces are different from each other. In this way, impurities in the medium can be effectively retained, and the wear on the bushing and the coating can be reduced, thereby reducing the maintenance frequency of the centrifugal pump. Eddy currents can also be formed in the grooves to increase the resistance to the flow of the medium in the gap of the balancing drum, reduce the flow rate, and improve the noise reduction effect.

[0015] These and other aspects of the present disclosure will become more apparent from the following description of the embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The above and other objects, features and advantages of the exemplary embodiments disclosed herein will become more understandable through the following detailed description with reference to the accompanying drawings. In the accompanying drawings, several exemplary embodiments disclosed herein will be illustrated in an exemplary and non-limiting manner.

[0017] Figure 1 A schematic cross-sectional view showing the entirety of a centrifugal pump according to an embodiment of the present disclosure.

[0018] Figure 2 Shows Figure 1 A partial enlarged schematic diagram of part B in FIG.

[0019] Figure 3 A schematic cross-sectional view of a bushing holder according to an embodiment of the present disclosure is shown.

[0020] Figure 4 A front view of a sound attenuation hood according to an embodiment of the present disclosure is shown.

[0021] Figure 5 A side view of a sound attenuation hood according to an embodiment of the present disclosure is shown.

[0022] Figure 6 A schematic diagram according to an embodiment of the present disclosure is shown, which illustrates the positional relationship between the plating layer of the balance drum and the bushing disposed on the bushing holder and the radial gap formed.

[0023] Figure 7 An enlarged view of the radial gap is shown according to an embodiment of the present disclosure.

[0024] Figure 8 An enlarged view of a trench cell according to an embodiment of the present disclosure is shown.

[0025] Throughout the drawings, the same or similar reference numerals refer to the same or similar parts. DETAILED DESCRIPTION

[0026] The principles of the present disclosure will now be described with reference to some example embodiments. It will be understood that these embodiments are described only for illustration and for the purpose of helping those skilled in the art to understand and implement the present disclosure, and no limitation to the scope of the present disclosure is suggested. The disclosure described herein can be implemented in various ways except for the way described below.

[0027] In the following description and claims, unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs.

[0028] References in this disclosure to "one embodiment," "an embodiment," "an example embodiment," etc. indicate that the described embodiment may include a particular feature, structure, or characteristic, but not every embodiment necessarily includes the particular feature, structure, or characteristic. Moreover, such phrases do not necessarily refer to the same embodiment. Further, when a particular feature, structure, or characteristic is described in conjunction with an embodiment, it is claimed that it is within the knowledge of those skilled in the art to apply such feature, structure, or characteristic in conjunction with other embodiments, whether or not explicitly described.

[0029] It should be understood that although the terms "first" and "second" and the like may be used herein to describe various parts, these parts should not be limited by these terms. These terms are used only to distinguish one part from another part. For example, a first part may be referred to as a second part, and similarly, a second part may be referred to as a first part without departing from the scope of the example embodiments. As used herein, the term "and / or" includes any and all combinations of one or more of the listed items.

[0030] The terms used herein are used only for the purpose of describing specific embodiments and are not intended to limit the exemplary embodiments. As used herein, the singular forms "a", "an", and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that when used herein, the terms "include", "comprise", "have", "include", "contain", and / or "comprises" specify the presence of stated features, parts, and / or components, etc., but do not exclude the presence or addition of one or more other features, parts, components, and / or combinations thereof.

[0031] The embodiments of the present disclosure provide a solution that can reduce pressure fluctuations and noise in a centrifugal pump. Figures 1 to 8 The specific structure of the centrifugal pump according to the embodiment of the present disclosure is described in detail. Figure 1 , which shows a schematic cross-sectional view of a centrifugal pump 1 .

[0032] like Figure 1 As shown, a cylinder 90 is provided outside the centrifugal pump 1 to accommodate various components located inside the centrifugal pump 1. An inlet 11 and an outlet 12 are provided on the cylinder 90, wherein the inlet 11 and the outlet 12 can be connected to other pipeline components. When a medium such as water or other liquid flows into the centrifugal pump 1 from the inlet 11, it will be pressurized by the centrifugal pump 1, and the pressurized medium flows out from the outlet 12. A shaft 10 is provided inside the cylinder 90, and a plurality of impellers 13 are provided on the shaft 10. The shaft 10 can be driven by an electric motor or a steam turbine, and rotates at high speed around its axis A. As the shaft 10 rotates, the shaft 10 drives these impellers 13 to rotate, so that the medium flows from the inlet 11 of the centrifugal pump 1 to the outlet 12 of the centrifugal pump 1. A small amount of medium passes through the radial gap 60 of the balance drum and flows back to the first-stage impeller through the return pipe 14 on the end cover 15.

[0033] Continue to refer Figure 1 The centrifugal pump 1 is also provided with a balance drum 20. As shown, the balance drum 20 is circumferentially arranged on the shaft 10 and can rotate with the shaft 10. The balance drum 20 is a drum-shaped part used to balance the axial force of the centrifugal pump 1. The axial force formed by the pressure difference between the inlet and outlet ends of the balance drum can partially balance and offset the axial force formed by the pressure difference between the front and rear cover plates of the multiple impellers 13. Figure 1 As shown, a coating 22 is provided on the radial outer surface of the balance drum 20. In some embodiments, the coating may be a cobalt-nickel alloy coating, which has high hardness and wear resistance, corrosion resistance and high temperature resistance.

[0034] Figure 2 Shows Figure 1 A partial enlarged schematic diagram of part B in FIG. Figure 2 As shown, the centrifugal pump 1 further includes a bushing 30. The bushing 30 is arranged in cooperation with the coating 22 of the balance drum 20. The centrifugal pump 1 further includes an end cover 15, which is fixedly arranged on the cylinder 90. The bushing 30 is installed on the radial inner side of the end cover 15, and the bushing 30 is made of a wear-resistant composite material. The bushing 30 can be made of a high-molecular carbon fiber composite material with high strength, high temperature resistance and wear resistance, so as to avoid abrasion and bite with the coating 22 of the balance drum 20.

[0035] exist Figure 2 In the illustrated embodiment, the centrifugal pump 1 further comprises a bushing holder 32 . Figure 3A schematic cross-sectional view of a bushing frame 32 according to an embodiment of the present disclosure is shown. The bushing frame 32 and the end cover 15 can be connected by a combination of bolts and washers, and the radial inner side 33 of the bushing frame 32 supports the bushing 30. In this way, by setting the bushing frame 32, a combination can be formed with the bushing 30, and the structural design is optimized. Therefore, if the bushing 30 is greatly worn after use, only the bushing 30 can be replaced, and the bushing frame 32 can be retained for continued use, thereby achieving the effect of saving maintenance costs. In some embodiments, the bushing frame 32 can be made of stainless steel. It should be noted that this is only schematic, and the bushing frame 32 can also be made of other materials according to specific usage scenarios and requirements.

[0036] In some embodiments, there is an interference fit between the bushing holder 32 and the bushing 30. In this way, the bushing holder 32 and the bushing 30 can be firmly matched. In one embodiment, a liquid nitrogen cryogenic cooling method can be used to cool the bushing 30 and press the bushing 30 into the bushing holder 32, and one or more fasteners 17 can be used to fix the bushing holder 32 and the bushing 30, so that the bushing holder 32 and the bushing 30 are assembled into a combined structure to ensure that the bushing holder 32 and the bushing 30 do not move or rotate relative to each other during the operation of the centrifugal pump 1.

[0037] In some embodiments, the radial outer side 34 of the bushing holder 32 includes a first side section 341 and a second side section 342, wherein the first side section 341 is close to the impeller 13, and the second side section 342 is close to the muffler 40. A first distance D1 between the first side section 341 and the axis A of the shaft 10 is less than a second distance D2 between the second side section 342 and the axis A. In this way, as Figure 3 As shown, the bushing frame 32 forms a stepped radial outer side surface 34. This stepped arrangement can facilitate the installation and removal of the bushing frame 32.

[0038] Continue to refer Figure 3 A chamfer 1 343 is formed between the first side section 341 and the second side section 342, and the chamfer 1 343 can be set at 45 degrees with the second side section 342. In addition, a chamfer 2 344 can be set at 15 degrees with the first side section 341 and the end surface 345 of the bushing frame 32, and such a setting can facilitate avoiding scratches when installing the bushing frame 32. It should be noted that the angles listed here are only illustrative and not restrictive, and other angles also fall within the scope of the embodiments of the present disclosure.

[0039] exist Figure 2 In the illustrated embodiment, the centrifugal pump 1 further includes a muffler 40 . Figure 4 and Figure 5Different views of the muffler 40 according to an embodiment of the present disclosure are shown respectively. The muffler 40 can be mounted to the end cover 15 via a fastener 16 and is arranged on the radial outside of the bushing frame 32. The muffler 40 includes an annular bevel 42, and the radial dimension of the annular bevel 42 on the side close to the impeller 13 is smaller than the radial dimension on the side away from the impeller 13, thereby forming a medium retention area 43 between the annular bevel 42 and the end cover 15. By setting the medium retention area 43, the medium can be prevented from forming a vortex, thereby suppressing the harmful effects of the vortex.

[0040] In some embodiments, the silencer 40 can be stamped from a thin plate. Such a setting has a damping effect on pressure fluctuations, thereby improving the silencer effect of medium and high frequencies, effectively reducing pressure fluctuations, and suppressing the high-frequency noise caused by pressure fluctuations to the greatest extent.

[0041] In some embodiments, the muffler cover 40 further includes one or more muffler holes 44, which are circumferentially arranged in the middle of the annular slope 42 of the muffler cover 40. The muffler holes 44 are arranged in the middle without affecting the overall strength of the muffler cover 40. Figure 5 As shown, these muffler holes 44 can be evenly distributed in the circumferential direction of the muffler cover 40, and their number can be set according to specific needs. It should be noted that, Figure 5 The arrangement of the muffler holes 44 shown in the figure is merely illustrative and non-restrictive. The embodiments of the present disclosure do not impose any particular restrictions on the number and size of the muffler holes 44. By using these muffler holes 44, the pressure fluctuation of the fluid medium at the muffler cover 40 can be reduced, thereby further improving the noise reduction effect.

[0042] Combine the following Figures 6 to 8 The radial gap 60 between the plating layer 22 and the bushing 30 will be described in detail. Figure 6 The diagram shows a positional relationship between the plating layer 22 of the balance drum 20 and the bushing 30 disposed on the bushing holder 32 and a radial gap 60 formed therebetween according to an embodiment of the present disclosure. Figure 7 Shows Figure 6 An enlarged view of the radial gap 60 in FIG. Figure 7In the illustrated embodiment, the radial gap 60 generally includes an inlet area 61, a groove area 62, and an outlet area 63. The inlet area 61 has a reduced cross section along the flow direction of the medium, and the inlet area 61 allows the medium to have a certain buffer transition space when it flows into the radial gap 60, which can effectively suppress the swirl flow at the inlet, so that the pressure fluctuation and noise are reduced. In the illustrated embodiment, the outlet area 63 has a gradually expanding cross section along the flow direction of the medium. By using this diffusion method, the flow velocity of the medium will decrease when passing through, which helps to reduce the influence of the jet at the outlet. Since this avoids the medium from being injected into the expansion chamber located behind the muffler 40 at a higher speed, the pressure fluctuation and the noise caused thereby can be effectively reduced.

[0043] like Figure 7 As shown, the trench region 62 may include a plurality of trench units 620 that are repeatedly arranged. Figure 8 6 shows an enlarged view of the trench cell 620. Figure 8 As shown, the groove unit 620 is composed of three grooves, namely a large groove, a medium groove and a small groove. Each groove 621 includes a vertical surface 622, a rounded surface 623 and an inclined surface 624. The sizes of the three surfaces of different grooves are different. Specifically, the corresponding vertical surfaces 622 of different grooves 621 extend perpendicular to the axis A of the shaft 10, but the depths of different grooves 621 are different from each other. Secondly, the fillet radii of the corresponding rounded surfaces 623 of different grooves 621 are different from each other. Furthermore, the corresponding inclined surfaces 624 of different grooves 621 extend at the same angle (for example, 30°) relative to the axis A of the shaft 10, but the lengths of the corresponding inclined surfaces 624 are different from each other.

[0044] It should be noted that, although the figure shows that the groove unit 620 includes three grooves of different sizes, this is only schematic. Other numbers of grooves are also feasible. For example, the groove unit 620 may include two grooves, four grooves or more grooves. These situations all fall within the protection scope of the embodiments of the present disclosure.

[0045] In a preferred embodiment, the groove unit 620 can be arranged so that the first groove into which the medium flows is a large groove, and the last groove out of which the medium flows is a small groove. When the medium flows into the groove flow channel from the gap, since the first groove encountered by the medium is a large groove, its flow space expands rapidly, and the flow separates, thereby generating a backflow in the opposite direction of the overall flow, and an obvious vortex structure can be formed in the groove. The groove structure can increase the local resistance loss and reduce the leakage of the radial gap 60 of the balance drum, thereby achieving a better effect of balancing the axial force. In addition, since a low-pressure vortex zone is formed in each groove, impurities such as silt particles in the medium will be retained in this low-pressure vortex zone, thereby reducing the wear of the impurities on the bushing 30 and the coating 22, which can effectively extend the service life of the balance drum components.

[0046] According to the embodiment of the present disclosure, grooves of different sizes can retain sediment particles of different sizes, which can more effectively reduce particle friction. Since there is only slight friction or no friction between the coating 22 of the balance drum 20 and the bushing 30, the pressure fluctuation of the centrifugal pump 1 and the noise generated thereby will be greatly reduced.

[0047] Compared with the existing centrifugal pump design, the present invention designs a high-pressure multi-stage centrifugal pump with a special structural form with a balancing drum component and a silencer cover, which can achieve low pressure fluctuations during the operation of the centrifugal pump and thereby bring about a noise reduction design effect.

[0048] The specific implementation methods described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific implementation method of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

[0049] Although the subject matter has been described in language specific to structural features and / or methodological acts, it will be understood that the subject matter defined in the appended claims is not necessarily limited to the specific features or acts described above. Rather, the specific features and acts described above are disclosed as example forms of implementing the claims.

Claims

1. A centrifugal pump (1), characterized in that: include: Cylinder (90); A shaft (10) disposed in the cylinder (90) and configured to drive an impeller (13) on the shaft (10) to rotate so that a medium flows from an inlet (11) of the centrifugal pump (1) to an outlet (12) of the centrifugal pump (1); a balancing drum (20) which is circumferentially arranged on the shaft (10) and is configured to at least partially balance the axial force exerted by the medium on the impeller (13); the balancing drum (20) rotates with the shaft (10) and has a coating (22) on its radial outer surface; and A bushing (30) is arranged in cooperation with the coating (22) of the balance drum (20) and forms a combination with a bushing frame (32) and is installed on the radial inner side of the end cover (15), wherein the bushing (30) is made of a wear-resistant composite material, and the end cover (15) is fixedly arranged on the cylinder (90). The centrifugal pump (1) further comprises a muffler cover (40), the muffler cover (40) being mounted on the end cover (15) and being arranged radially outside the bushing frame (32), the muffler cover (40) comprising an annular bevel (42), the radial dimension of the annular bevel (42) on a side close to the impeller (13) being smaller than the radial dimension on a side away from the impeller (13), thereby forming a medium retention area (43) between the annular bevel (42) and the end cover (15), the muffler cover (40) further comprising one or more muffler holes (44), the muffler holes (44) being circumferentially arranged in the middle of the annular bevel (42) of the muffler cover (40), and The radial gap (60) between the coating (22) of the balance drum (20) and the bushing (30) comprises an inlet area (61), a groove area (62) and an outlet area (63), wherein the inlet area (61) has a narrowing cross-section along the flow direction of the medium, the outlet area (63) has a gradually expanding cross-section along the flow direction of the medium, and the groove area (62) comprises a plurality of repeatedly arranged groove units (620).

2. The centrifugal pump (1) according to claim 1, characterized in that: The bushing frame (32) is connected to the end cover (15), and the radial inner side surface (33) of the bushing frame (32) supports the bushing (30).

3. The centrifugal pump (1) according to claim 2, characterized in that: The bushing frame (32) and the bushing (30) are in interference fit.

4. The centrifugal pump (1) according to claim 2 or 3, characterized in that: The radial outer side surface (34) of the bushing frame (32) includes a first side section (341) close to the impeller (13) and a second side section (342) close to the muffler cover (40), wherein a first distance (D1) between the first side section (341) and the axis centerline (A) of the shaft (10) is smaller than a second distance (D2) between the second side section (342) and the axis centerline (A).

5. The centrifugal pump (1) according to claim 1, characterized in that: Each groove unit (620) includes at least two grooves (621), each groove (621) includes a vertical surface (622), a rounded surface (623) and an inclined surface (624), and wherein corresponding vertical surfaces (622) of different grooves (621) of the at least two grooves (621) extend perpendicularly to the axis (A) of the shaft (10), but the depths of the different grooves (621) are different from each other; wherein the fillet radii of the corresponding fillet surfaces (623) of the different grooves (621) are different from each other; and The corresponding inclined surfaces (624) of the different grooves (621) extend at the same angle relative to the axis (A) of the shaft (10), but the lengths of the corresponding inclined surfaces (624) are different from each other.

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