WO2023070766A1

WO2023070766A1 - Axial liquid intake structure and multi-stage centrifugal pump having same

Info

Publication number: WO2023070766A1
Application number: PCT/CN2021/131229
Authority: WO
Inventors: 杨丹飞; 余伟平; 余敏; 周维坚; 张丹艺
Original assignee: 浙江水泵总厂有限公司
Priority date: 2021-10-31
Filing date: 2021-11-17
Publication date: 2023-05-04
Also published as: CN114001033A

Abstract

An axial liquid intake structure and a multi-stage centrifugal pump having same. The axial liquid intake structure comprises a pump body (100), the pump body (100) comprising a liquid intake portion (10), a main shaft (30), and a suspension (40), wherein the liquid intake portion (10) is located at one end of the pump body (100), and the suspension (40) is located at the other end thereof; one end of the main shaft (30) is rotatably connected to the suspension (40); the liquid intake portion (10) is provided with a liquid inlet (11) in an extension direction of the main shaft (30), and an auxiliary bearing (31) is fixedly arranged on an inner side wall of the liquid inlet (11); and the other end of the main shaft (30) penetrates the suspension (40) and is then rotatably connected to the auxiliary bearing (31).

Description

Axial liquid inlet structure and its multistage centrifugal pump

related application

This application claims the priority of the Chinese patent application filed on October 31, 2021, with the application number 202111279067.X, and the title of the invention is "Axial liquid inlet structure and multi-stage centrifugal pump with the same", the entire content of which is incorporated by reference incorporated in this application.

technical field

The present application relates to related fields of water pumps, in particular to an axial liquid inlet structure and a multistage centrifugal pump with the same.

Background technique

Most of the current single-stage centrifugal pumps use a cantilever support structure, that is, axial liquid inlet and radial outlet; and multi-stage centrifugal pumps have a longer main shaft length, if the cantilever support structure is used, the distance between the liquid inlet and the cantilever Too large will lead to poor radial stability of the main shaft at the liquid inlet; therefore, most of the usual multistage centrifugal pumps adopt the structure of radial liquid inlet and radial outlet, so that the main shaft can be supported by bearings on both sides to ensure Radial stability for longer spindles.

However, when liquid is fed radially, according to the distance between the inner wall of the pump body connected to the liquid inlet and the radial liquid inlet, the pressure between the liquid and the inner wall of the pump is also different, so that the channel balance The cavitation performance in some positions is poor, that is, the cavitation performance of the radial liquid inlet is low.

The usual multi-stage centrifugal pumps are mostly designed with the flow rate in mind, and the design priority for cavitation performance is relatively low, so most of them directly adopt the traditional radial inlet and outlet structures.

Contents of the invention

Based on this, it is necessary to provide an axial liquid inlet structure with high cavitation performance and a multistage water pump having the same for the problem of poor radial liquid inlet cavitation performance of the multistage water pump.

The application firstly provides an axial liquid inlet structure, including a pump body; the pump body includes a liquid inlet part, a main shaft and a suspension; the liquid inlet part is located at one end of the pump body, and the suspension is located at the other end , one end of the main shaft is rotatably connected to the suspension; the liquid inlet part is provided with a liquid inlet along the extension direction of the main shaft, and an auxiliary bearing is fixed on the inner side wall of the liquid inlet; the other side of the main shaft One end passes through the suspension until it is rotatably connected with the auxiliary bearing.

The above-mentioned axial liquid inlet structure is respectively connected to the main shaft through the suspension and the auxiliary bearing, so that the main shaft can be supported on both sides, thereby increasing the stability of the main shaft under working conditions; in addition, by opening the liquid inlet along the extension direction of the main shaft , so that after the main shaft starts to rotate, the liquid to be transported enters the pump body along the axial direction, so that the channel balance in the liquid inlet is relatively high, and the cavitation performance of each position is the same or similar, and there is no position with relatively poor cavitation performance. Further, the effect of increasing the cavitation performance of the pump body is achieved.

In one of the embodiments, the auxiliary bearing is arranged at the center of the liquid inlet.

Such setting ensures that during the rotation of the main shaft, the liquid enters evenly at each position of the liquid inlet, so as to achieve the effect of increasing the cavitation performance of the pump body.

In one of the embodiments, the auxiliary bearing is a sliding bearing.

With such an arrangement, the axial offset generated during the rotation of the main shaft is offset by the sliding bearing, further increasing the stability of the main shaft.

In one of the embodiments, the auxiliary bearing is a water lubricated bearing.

It is set in this way to avoid the leakage of lubricating oil of other types of sliding bearings and contaminate the condensed water when the conveyed liquid is condensed water.

In one of the embodiments, the auxiliary bearing is fixedly connected to the inner side wall of the liquid inlet through a connecting piece.

In one of the embodiments, there are three connecting members, and they are uniformly distributed around the main axis.

Such setting, on the one hand, ensures that the auxiliary bearing is firmly fixed, thereby further increasing the stability during the rotation of the main shaft; on the other hand, the gap between the connecting piece and the inner wall of the liquid inlet is uniformly distributed around the main shaft, increasing the balance of the channel , thereby increasing the cavitation performance of the pump body.

In one of the embodiments, the main shaft is connected with the suspension through at least two sets of bearings.

Such setting ensures that the main shaft can be supported by at least two points in the suspension, thereby further improving the stability of the main shaft when the main shaft rotates by increasing the number of supporting points for the main shaft.

In one of the embodiments, one set of the bearings is arranged at the end of the suspension close to the liquid inlet part, and the other set of the bearings is arranged at the end of the suspension away from the liquid inlet part.

With such arrangement, the supporting points of the auxiliary bearing and the two sets of bearings are arranged as evenly as possible, so as to achieve the effect of improving the supporting stability of the main shaft.

In one embodiment, the set of bearings located at one end of the suspension close to the liquid inlet is a deep groove ball bearing, and the set of bearings located at the other end are two angular contact ball bearings.

The second aspect of the present application provides a multistage centrifugal pump, including the above-mentioned axial liquid inlet structure.

Description of drawings

FIG. 1 is a schematic cross-sectional structure diagram of the multistage centrifugal pump of the present application in the front view direction.

Fig. 2 is an enlarged structural schematic diagram of the liquid inlet part in Fig. 1 .

Fig. 3 is a left view structural diagram in Fig. 1 .

FIG. 4 is a schematic diagram of an enlarged structure at point A in FIG. 1 .

FIG. 5 is a schematic diagram of an enlarged structure at B in FIG. 4 .

Description of main component symbols:

100, pump body; 10, liquid inlet; 11, liquid inlet; 20, booster; 21, impeller; 22, middle shell; 30, main shaft; 31, auxiliary bearing; 311, sliding bearing pair; 312 Sliding bearing; 313, gap; 32, connector; 33, diversion space; 34, baffle; 40, suspension; 41, deep groove ball bearing; 42, angular contact ball bearing; 50, water pipe.

The above description of the symbols of the main components will further describe the present application in detail in combination with the accompanying drawings and specific embodiments.

Detailed ways

The following will clearly and completely describe the technical solutions in the embodiments of the application with reference to the drawings in the embodiments of the application. Apparently, the described embodiments are only some of the embodiments of the application, not all of them. Based on the embodiments in this application, all other embodiments obtained by persons of ordinary skill in the art without making creative efforts belong to the scope of protection of this application.

It should be noted that when a component is said to be "mounted on" another component, it can be directly on the other component or there can also be an intervening component. When a component is said to be "set on" another component, it may be set directly on the other component or there may be an intervening component at the same time. When a component is said to be "fixed" to another component, it may be directly fixed to the other component or there may be an intervening component at the same time.

Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the technical field to which this application belongs. The terms used herein in the specification of the application are only for the purpose of describing specific embodiments, and are not intended to limit the application. As used herein, the term "or/and" includes any and all combinations of one or more of the associated listed items.

At present, for single-stage or bipolar centrifugal pumps with a short main shaft length, the main shaft is mostly fixed by a cantilever support structure. The port can be opened at one end of the main shaft suspended in the air, and opened along the direction of the main shaft, that is, the liquid enters radially;

For a multi-stage centrifugal pump with a long main shaft, if the main shaft is also set with a cantilever support structure, due to the long main shaft, after the main shaft starts to rotate at a high speed, the stability of the suspended part of the main shaft is poor, which may cause radial runout of the main shaft or offset;

Therefore, the usual multistage centrifugal pumps mostly adopt the structure of radial liquid inlet and radial liquid outlet, such as CN1641224, the two ends of the main shaft are connected with the pump body through the bearing seat, and the liquid inlet and the liquid outlet are radially opened. , and is located between the two bearing seats to ensure the stability of the main shaft during the working process through the support of the two bearing seats;

However, during the radial liquid feeding process, due to the different flow path lengths on both sides of the main shaft at the liquid inlet, the flow velocity of the liquid on the side of the main shaft away from the liquid inlet is bound to be higher than that on the side of the main shaft close to the liquid inlet. Therefore, the pressure on the side of the main shaft away from the liquid inlet will be relatively low, resulting in poor cavitation performance (cavitation will occur when the pressure at the lowest point in the pump body is lower than the saturated vapor pressure at the temperature of the liquid being delivered) ;

However, in the design and manufacture process of current multi-stage centrifugal pumps, on the one hand, liquid flow and efficiency are mostly considered, and the design priority for cavitation performance is relatively low;

On the other hand, since the cavitation performance of the pump body involves many aspects such as hydrodynamic conditions, mechanical impact, material type and composition of the flow-passing parts, and electrochemical interaction between the surface of the material and the liquid, it is relatively complicated. It is also difficult to discover the problem that the radial liquid inlet structure will affect the cavitation performance of the pump body;

Therefore, most of the current multistage centrifugal pumps still adopt the traditional radial liquid inlet and radial liquid outlet structure.

In view of the above problems, the present application first provides an axial liquid inlet structure, including a pump body 100; the pump body 100 includes a liquid inlet portion 10, a main shaft 30 and a suspension 40; the liquid inlet portion 10 is located at one end of the pump body 100, and the suspension 40 is located at the other end, and one end of the main shaft 30 is rotatably connected to the suspension 40; the liquid inlet part 10 is provided with a liquid inlet 11 along the extension direction of the main shaft 30, and the inner side wall of the liquid inlet 11 is fixed with an auxiliary bearing 31, and the other side of the main shaft 30 One end passes through the suspension 40 to be rotatably connected with the auxiliary bearing 31 .

The suspension 40 and the auxiliary bearing 31 are respectively connected to the main shaft 30 in rotation, so that the main shaft 30 can be supported on both sides, thereby increasing the stability of the main shaft 30 in the working state; on this basis, the suspension 40 is connected to the auxiliary bearing 31 respectively At both ends of the main shaft 30, both ends of the main shaft 30 are supported, that is, there is no suspended part in the main shaft 30, so as to ensure that the main shaft 30 will not vibrate or deviate in the radial direction during the rotation process, and increase the working state of the main shaft 30. stability.

In addition, by opening the liquid inlet 11 along the extension direction of the main shaft 30, after the main shaft 30 starts to rotate, the liquid to be transported enters the pump body 100 along the axial direction, that is, the flow path of the liquid to be transported is the same, so that the uniformity of the liquid to be transported is achieved. The inflow makes the channel balance in the liquid inlet 11 higher, the cavitation performance of each position is the same or similar, and there is no position with relatively poor cavitation performance, thereby achieving the effect of improving the cavitation performance of the pump body 100 .

In the embodiment shown in FIG. 1 , the auxiliary bearing 31 is arranged at the center of the liquid inlet 11, so that the axial projection of the main shaft 30 is located at the center of the liquid inlet 11, thereby ensuring that during the rotation of the main shaft 30, the liquid inlet 11 The liquid inflows into each position evenly, so as to avoid the situation of high flow rate and poor cavitation performance in some positions due to uneven liquid inflow, and achieve the effect of improving the cavitation performance of the pump body 100.

In the embodiment shown in Fig. 1, the auxiliary bearing 31 is a sliding bearing, so as to offset the axial offset generated during the rotation of the main shaft 30, and further increase the stability of the main shaft 30; Optionally, the auxiliary bearing 31 is a water-lubricated bearing, so as to avoid the leakage of lubricating oil of other types of sliding bearings and contaminate the condensed water when the conveyed liquid is condensed water.

In the embodiment shown in FIG. 2, the auxiliary bearing 31 is fixedly connected to the inner wall of the liquid inlet 11 through the connecting piece 32, and there is a gap between the connecting piece 32 and the inner wall of the liquid inlet 11 for the normal passage of the liquid to be transported. , The connecting piece 32 and the inner wall of the liquid inlet 11 can be fixed by welding, bolting, integral molding and other common fixing methods. Optionally, the connecting piece 32 is fixed to the inner wall of the liquid inlet 11 by welding.

In some embodiments, multiple connectors 32 are provided and are evenly distributed around the main shaft 30 in the circumferential direction, on the one hand, to ensure that the auxiliary bearing 31 is firmly fixed, thereby further increasing the stability of the main shaft 30 during rotation;

On the other hand, the gap between the connecting piece 32 and the inner wall of the liquid inlet 11 is evenly distributed in the circumferential direction around the main shaft 30, so that the liquid to be transported can enter the pump body 100 evenly when entering through the liquid inlet 11 , so as to avoid the occurrence of high flow velocity and poor cavitation performance at some positions due to uneven liquid inlet, and achieve the effect of increasing the cavitation performance of the pump body 100 .

In the embodiment shown in FIG. 3 , there are three connecting members 32 , which are uniformly distributed around the main shaft 30 .

In the embodiment shown in FIG. 1 , the main shaft 30 is connected to the suspension 40 through at least two sets of bearings, so as to ensure that the main shaft 30 can be supported by at least two points in the suspension 40, thereby increasing the number of support points for the main shaft 30, Further improve the stability when the main shaft 30 rotates;

Comprehensively considering the increase in stability and cost after adding the number of bearings, optionally, the main shaft 30 is connected to the suspension 40 through two sets of bearings.

One group of bearings is arranged on the end of the suspension 40 close to the liquid inlet 10, and the other group of bearings is arranged on the end of the suspension 40 away from the liquid inlet 10. Since the distance between the auxiliary bearing 31 and the suspension 40 is usually greater than that of the suspension 40, by arranging the two sets of bearings at both ends of the suspension 40, the distance between the two sets of bearings can be increased as much as possible, and the distance can be as close as possible to the distance between the auxiliary bearing 31 and the bearing in the middle. distance, so that the arrangement of the supporting points between the auxiliary bearing 31 and the two sets of bearings is as uniform as possible, so as to achieve the effect of improving the support stability of the main shaft 30 .

The bearings here may be cylindrical bearings, sliding bearings, ball bearings or other commonly used rotating connection parts, which are not limited in this application. Optionally, the main shaft 30 is connected to the suspension 40 through ball bearings, and a set of bearings located at one end of the suspension 40 close to the liquid inlet part 10 is a deep groove ball bearing 41, and a set of bearings located at the other end are two angular contact bearings. Ball bearing 42.

Among them, the two angular contact ball bearings 42 are installed with wide end faces facing wide end faces, so as to bear large radial loads, limit the axial displacement of the main shaft 30 in two directions, and increase the axial stability of the main shaft 30 .

The present application also provides a multistage centrifugal pump, including the axial liquid inlet structure of any one of the above embodiments.

In the embodiment shown in Fig. 1 and Fig. 4, the multi-stage centrifugal pump also includes a supercharging part 20, and the supercharging part 20 is located between the liquid inlet part 10 and the suspension 40; the auxiliary bearing 31 includes a sliding bearing pair 311 and a sliding bearing Bearing 312, wherein the sliding bearing 311 is fixed to the connector 32, and one end of the main shaft 30 is connected to the sliding bearing 312; the pump body 100 also includes a water pipe 50, one end of the water pipe 50 communicates with the supercharging part 20, and the other end is connected to the sliding bearing 311 and the gap 313 between the sliding bearing 312 communicates.

Here, the pressurization part 20 is used to pressurize the liquid to be delivered entering the pressurization part 20 . The liquid to be transported enters the pump body 100 through the liquid inlet portion 10 , and after entering the booster portion 20 , it is pressurized by the booster portion 20 and delivered to other structures of the pump body 100 .

One end of the water pipe 50 communicates with the supercharging part 20, and the other end communicates with the gap 313, so that the part of the liquid to be transported after being pressurized by the supercharging part 20 can rush into the gap 313 through the water pipe 50, and then flow into the liquid from the gap 313 again. part 10; and through the flowing high-pressure liquid, the heat generated by the friction between the sliding bearing 312 and the sliding bearing pair 311 can be taken away together during the rotation of the main shaft 30, so as to avoid the heat accumulation in the gap 313 and cause parts to break down. Thermal expansion and contraction, the gap 313 occurs due to the expansion and disappearance of parts, and the effect of cooling the sliding bearing 312 in real time to ensure its normal operation is achieved.

In the embodiment shown in Fig. 1 and Fig. 4, the supercharging part 20 includes a plurality of impellers 21 arranged along the extending direction of the main shaft 30, and a flow space is formed between the impellers 21 and the inner side wall of the pump body 100, and the water pipe 50 is connected to the flow passage. Flow space connectivity.

For ease of description, the impeller 21 closest to the liquid inlet part 10 is defined as the first-stage impeller herein.

Specifically, the impellers 21 are fixedly connected to the main shaft 30, the water inlet of the impeller 21 is opened towards the direction of the liquid inlet 10, and the water outlet is opened along the radial direction. When the main shaft 30 rotates, it will drive the impellers 21 to rotate, so that , pressurize the liquid to be transported into the impeller 21 and throw it out to the next stage impeller 21, repeat the above process until the liquid to be transported leaves the pressurization part 20, so as to realize the pressurized transport function of the pressurization part 20.

The supercharger 20 is composed of a plurality of hollow middle casings 22, each impeller 21 corresponds to a middle casing 22, and the impeller 21 is arranged in the middle casing 22, between the impeller 21 and the inner side wall of the middle casing 22 A through-flow space is formed, and the through-flow space is used to guide the liquid to be transported, so that the liquid flowing out from the water outlet of the impeller 21 of this stage can enter the water inlet of the next-stage impeller under the guidance of the through-flow space.

Optionally, the corners of the through-flow space are all rounded to ensure that the liquid to be transported can turn naturally during the flow process, and avoid direct collision with the side wall of the through-flow space to cause liquid turbulence.

In addition, the arrangement of multiple middle casings 22 makes it possible to remove the corresponding middle casing 22 and replace the corresponding wearing parts when the wearing parts such as sealing rings and shaft seals in the middle casing 22 are damaged. The middle casing 22 itself and the impeller 21 can still be used continuously, which greatly saves the time and cost required for repair.

The water pipe 50 communicates with the flow space, that is, the flow space between the middle casing 22 and the impeller 21 of any stage communicates with the water pipe 50;

When the liquid to be transported enters the corresponding through-flow space through the first-stage impeller 21 , the pressurization has been completed for the first time, and the subsequent impeller 21 can further pressurize the liquid to be transported to meet different demands. Therefore, it can be understood that the liquid to be transported into any flow space is liquid that has been pressurized at least once, and by connecting the water pipe 50 with the flow space, it can be ensured that the liquid entering the water pipe 50 must be a pressurized liquid. To meet subsequent cooling needs.

Optionally, the flow space of the first-stage impeller 21 communicates with the water pipe 50, and the liquid pressurized by the first-stage impeller 21 is sufficient to meet the cooling requirements of the sliding bearing 312 in most cases; After passing through the gap 313, the part of the liquid needs to be pressurized again, that is, the original pressure energy of the part of the liquid will be consumed after passing through the gap 313. Therefore, the higher the initial pressure of the liquid used for cooling, the higher the energy consumed for cooling. higher consumption;

It can be understood that, in the case of the same cooling effect, if the water pipe 50 is chosen to communicate with the flow space of other impellers 21 , the energy consumption for cooling the sliding bearing 312 will be increased, thereby reducing the overall working efficiency of the pump body 100 .

Of course, if there is a high rotational speed of the main shaft 30 or other special circumstances that cause frictional heat generation to be faster, the water pipe 50 can also be connected to the flow space of other impellers 21 to obtain a higher liquid flow rate and increase the frictional heat generation rate. The cooling effect of the sliding bearing 312 is not specifically limited in this application.

In addition, since the first-stage impeller 21 is the impeller 21 closest to the liquid inlet 10, by connecting the water pipe 50 with the flow space of the first-stage impeller 21, the required length of the water pipe 50 can also be reduced, on the one hand reducing production costs, and on the other hand On the one hand, it reduces the possibility of accidental damage to the water pipe 50 .

In the embodiment shown in FIG. 5 , a baffle 34 is fixed at the end of the sliding bearing pair 311 away from the pressurized part 20 , and one end of the water pipe 50 is fixed to the baffle 34 . The baffle 34 is used to block the liquid to be transported entering the pump body 100 through the liquid inlet 11, so as to prevent the liquid to be transported from directly entering the gap 313 and mixing with the high-pressure liquid flushed out through the water pipe 50, causing the pressure of the liquid to drop, thereby affecting the sliding bearing. 312 cooling effect;

In addition, a diversion space 33 is formed between the baffle plate 34, the end face of the main shaft 30 and the inner side wall of the sliding bearing 311. The diversion space 33 communicates with the gap 313, and the angles in the diversion space 33 are inverted. There are rounded corners. After the high-pressure liquid in the water pipe 50 enters the diversion space 33, it flows out through the gap 313 between the sliding bearing 312 and the sliding bearing 311. The heat is taken away together to achieve the effect of cooling the sliding bearing 312 .

The technical features of the above-mentioned embodiments can be combined arbitrarily. To make the description concise, all possible combinations of the technical features in the above-mentioned embodiments are not described. However, as long as there is no contradiction in the combination of these technical features, should be considered as within the scope of this specification.

The above-mentioned embodiments only express several implementation modes of the present application, and the description thereof is relatively specific and detailed, but should not be construed as limiting the scope of the patent application. It should be noted that those skilled in the art can make several modifications and improvements without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the scope of protection of the patent application should be based on the appended claims.

Claims

An axial liquid inlet structure, characterized in that it includes a pump body;

The pump body includes a liquid inlet, a main shaft and a suspension;

The liquid inlet part is located at one end of the pump body, the suspension is located at the other end, and one end of the main shaft is rotatably connected to the suspension;

The liquid inlet part is provided with a liquid inlet along the extension direction of the main shaft, and an auxiliary bearing is fixed on the inner wall of the liquid inlet, and the other end of the main shaft passes through the suspension until it is rotatably connected with the auxiliary bearing. .
The axial liquid inlet structure according to claim 1, wherein the auxiliary bearing is arranged at the center of the liquid inlet.
The axial liquid inlet structure according to claim 1, wherein the auxiliary bearing is a sliding bearing.
The axial liquid inlet structure according to claim 3, wherein the auxiliary bearing is a water lubricated bearing.
The axial liquid inlet structure according to claim 1, wherein the auxiliary bearing is fixedly connected to the inner side wall of the liquid inlet through a connecting piece.
The axial liquid inlet structure according to claim 5, characterized in that there are three connecting members, which are uniformly distributed around the main shaft.
The axial liquid inlet structure according to claim 1, wherein the main shaft is connected with the suspension through at least two sets of bearings.
The axial liquid inlet structure according to claim 7, wherein one set of the bearings is arranged at the end of the suspension close to the liquid inlet, and the other set of the bearings is arranged at the suspension The end away from the liquid inlet part.
The axial liquid inlet structure according to claim 8, wherein the set of bearings located at one end of the suspension close to the liquid inlet is a deep groove ball bearing, and the set of said bearings located at the other end The bearings are two angular contact ball bearings.
A multistage centrifugal pump, characterized by comprising the axial liquid inlet structure according to any one of claims 1-9.