High-reliability multi-stage centrifugal pump

Abstract

The utility model discloses a high-reliability multi-stage centrifugal pump which comprises an outer cylinder body, a main shaft, a first-stage middle section, a flow guide body, a last-stage middle section, a pump cover and a suction side stuffing box body, wherein the first-stage middle section, the flow guide body and the last-stage middle section are coaxially mounted in the outer cylinder body, and impellers are mounted on the main shaft and matched with the first-stage middle section, the flow guide body and the last-stage middle section; the pump cover and the suction measuring stuffing box body are each provided with a bearing body, bearings are arranged in the bearing bodies and used for slewing bearing of the main shaft, stepped holes used for installation of shell sealing rings are formed in the first-stage middle section, the flow guide body and the last-stage middle section, impeller sealing rings are installed at the two ends of the impeller, and the impeller sealing rings are in running fit with the shell sealing rings. The balancing drum is installed on the main shaft and located at the position of the pump cover, the axis of the stepped hole has a downward eccentric distance ei in the plumb line direction relative to the outer circle axis of the corresponding first-stage middle section, the flow guide body and the last-stage middle section, and the eccentric distance ei = yi-yp.

Description

Technical Field

[0001] This application relates to the field of centrifugal pump technology, specifically a high-reliability multistage centrifugal pump. Background Technology

[0002] Horizontal multistage centrifugal pumps are widely used, especially in applications requiring high-pressure pumping. In existing technology, these centrifugal pumps typically have stepped holes in the first stage, guide vane, and final stage sections for mounting the housing sealing rings designed to coincide with the theoretical axis of the main shaft. To increase pumping pressure, multistage centrifugal pumps generally have a high number of stages. Due to the large number of impellers and the need for guide vanes between each impeller stage, the overall rotor length is long, resulting in a large span between the bearings at both ends. Figure 1 As shown, under the combined weight of its own body and the impeller, the main shaft 1 will naturally form a relatively rigid theoretical axis 12 that is bent downwards, resulting in an eccentricity. That is, the actual axis 13 of the main shaft 1 is a downward-curving flexible arc. Under the same conditions, the more stages a multistage pump has, the greater this eccentricity becomes. This is equivalent to generating a relatively large additional wear pressure on the lower side of the dynamic and static operating clearance (that is, the mating area between the housing seal ring 8 and the impeller seal ring 9), causing premature wear on the mating surface on the lower side of the operating clearance. After wear, the mating area between the housing seal ring 8 and the impeller seal ring 9 becomes approximately elliptical, and the upper clearance of the mating area is large, leading to an increase in the pump's volumetric loss and a decrease in both efficiency and head. Common solutions include designing a larger shaft diameter to enhance shaft rigidity and make the actual shaft centerline 13 coincide with the theoretical shaft centerline 12. However, this method increases costs and is limited by impeller hydraulic structure and other factors. Another approach is to increase the operating clearance size to avoid collision and wear at the dynamic and static operating clearance (i.e., the mating area between the casing sealing ring 8 and the impeller sealing ring 9). However, this will also increase the pump's volumetric loss, and both efficiency and head will decrease. The applicant proposes this solution through research and experimentation. Summary of the Invention

[0003] The purpose of this application is to provide a highly reliable multistage centrifugal pump to solve the problems in the prior art.

[0004] To achieve the above objectives, this application provides the following technical solution: a high-reliability multistage centrifugal pump, comprising an outer cylinder 4, a main shaft 1, a first-stage intermediate section 10 coaxially mounted within the outer cylinder 4, a guide fluid 7, and a final-stage intermediate section 11. The guide fluid 7 is plurality of units and disposed between the first-stage intermediate section 10 and the final-stage intermediate section 11. Impellers 6 are mounted on the main shaft 1 in pairs with the first-stage intermediate section 10, the guide fluid 7, and the final-stage intermediate section 11. The pump also includes pump covers 5 and suction stuffing boxes 19 located at both ends of the outer cylinder 4. Both the pump covers 5 and the suction stuffing boxes 19 are equipped with shafts. The bearing body 2 contains a bearing 3 for rotating support of the main shaft 1. The first stage intermediate section 10, the guide fluid 7, and the last stage intermediate section 11 are all provided with stepped holes 17 for installing housing sealing rings 8. Impeller 6 has impeller sealing rings 9 installed at both ends, and the impeller sealing rings 9 and housing sealing rings 8 are rotatably engaged. The system also includes a balance drum 22 mounted on the main shaft 1 and located at the pump cover 5. The axis of the stepped hole 17 has a downward eccentricity e relative to the corresponding outer circular axis of the first stage intermediate section 10, the guide fluid 7, and the last stage intermediate section 11 in the vertical direction. i The eccentricity e i =y i -y p ;y i The eccentricity of the impeller 6 on the main shaft 1 corresponding to the positions of the first stage middle section 10, the guide fluid 7, and the last stage middle section 11 is y. p The eccentricity at the balance drum 22 on the main shaft 1; wherein,

[0005] In the formula, G i The load at position 6 of the impeller; a i L is the axial distance from the impeller 6 to one of the bearings 3 closest to the balance drum 22; E is the distance between the two bearing 3 pivot points; J is the elastic modulus of the material of the main shaft 1; i The average moment of inertia at position 6 of the impeller;

[0006] In the formula, d i The diameter of the main shaft 1 at the position of the impeller 6;

[0007] In the formula, G p The load at the position of the balancing drum 22; a p L is the axial distance from the balance drum 22 to the adjacent bearing 3; E is the distance between the two bearing 3 support points; J is the elastic modulus of the material of the main shaft 1; p The average moment of inertia at the balancing drum 22;

[0008] In the formula, d p The diameter of the main shaft 1 at the balance drum 22.

[0009] Preferably, the guide fluid 7 includes a radial guide vane 701 and a guide fluid middle section 702 with an integral structure; an annular groove 703 is provided on one end face of the radial guide vane 701 on the guide fluid 7, and an axially protruding convex ring 704 is provided on one side of the guide fluid middle section 702. The annular groove 703, the convex ring 704 and the outer circle of the guide fluid 7 are coaxial, and there is an interference of 0.005 to 0.03 mm between the outer circle of the convex ring 704 of two adjacent guide fluids 7 and the corresponding inner wall of the annular groove 703.

[0010] Preferably, each of the guide fluids 7 has two stepped holes 17 located on the middle section 702 of the guide fluid and the radial guide vane 701, respectively. The inner diameter of the stepped hole 17 located on the middle section 702 of the guide fluid is larger than the inner diameter of the stepped hole 17 located on the radial guide vane 701.

[0011] Preferably, the guide body 7 is further provided with pin hole position A and pin hole position B, and the center of pin hole position A is located on the extension line of the line connecting the center of the stepped hole 17 and the center of the outer circle of the guide body 7. The line connecting the center of pin hole position B and the center of the outer circle of the guide body 7 forms an angle 18 with the line connecting pin hole position A and the center of the outer circle of the guide body 7, and the angle 18 is 40~50 degrees. The guide body 7 is provided with short pin hole 15 and long pin hole 16. The long pin hole 16 axially penetrates the guide body 7 and includes a large hole section 1601 and a small hole section 1602 that are coaxially connected. The short pin hole 15 is a countersunk hole and opens on the same side as the large hole section 1601. The short pin hole 15 and the long pin hole 16 on two adjacent guide bodies 7 are alternately formed at pin hole position A and pin hole position B, respectively.

[0012] Preferably, this high-reliability multistage centrifugal pump also includes a positioning pin 14, which is used to pass through the large hole section 1601 and fit into the small hole section 1602 and the short pin hole 15, so that all the stepped holes 17 are located on the same side relative to the outer circle center of the fluid guide 7.

[0013] Preferably, the guide fluid 7 and the final stage intermediate section 11 are also provided with a plurality of through holes 21 evenly distributed around their circumference. The axis of the through holes 21 is parallel to the outer circle axis of the guide fluid 7. The first stage intermediate section 10 is provided with a plurality of threaded holes 23 corresponding to the through holes 21. It also includes a tensioning stud 20 that passes through the through holes 21 and has external threaded sections at both ends. The external threaded section at one end of the tensioning stud 20 is screwed into the threaded hole 23, and the external threaded section at the other end is exposed on the final stage intermediate section 11 and screwed with a nut 24. The tensioning stud 20 and the nut 24 are used to connect the first stage intermediate section 10, the guide fluid 7 and the final stage intermediate section 11 into a whole.

[0014] The beneficial effects of this application are as follows: The high-reliability multistage centrifugal pump provided by this application adopts an eccentric setting for the stepped holes used to install the housing sealing rings on the first stage intermediate section, the guide fluid, and the last stage intermediate section. This makes the actual axis of the main shaft at the mating point between the impeller sealing ring and the housing sealing ring of each impeller coincide with the center line of the corresponding stepped hole. This allows the main shaft to work in its own flexible position, effectively reducing the collision and wear at the mating point between the housing sealing ring and the impeller sealing ring, thereby ensuring the operational reliability of the multistage centrifugal pump. Attached Figure Description

[0015] Figure 1 This is a cross-sectional view of the high-reliability multistage centrifugal pump of this application;

[0016] Figure 2 This is a front view of the fluid guide in this application;

[0017] Figure 3 for Figure 2 CC section view;

[0018] Figure 4 This is a rear view of the fluid guide in this application;

[0019] Figure 5 for Figure 4 DD section view;

[0020] Figure 6 This is a schematic diagram for calculating the eccentricity of the high-reliability multistage centrifugal pump in this application. Detailed Implementation

[0021] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0022] Please see Figure 1-6The present application describes a high-reliability multistage centrifugal pump. This high-reliability multistage centrifugal pump includes an outer cylinder 4, a main shaft 1, a first-stage intermediate section 10 coaxially mounted within the outer cylinder 4, a guide fluid 7, and a final-stage intermediate section 11. Several guide fluids 7 are arranged between the first-stage intermediate section 10 and the final-stage intermediate section 11. Impellers 6 are mounted on the main shaft 1 in pairs with the first-stage intermediate section 10, the guide fluid 7, and the final-stage intermediate section 11. The pump also includes pump covers 5 and suction stuffing boxes 19 located at both ends of the outer cylinder 4. Each stage is equipped with a bearing housing 2, and a bearing 3 is installed inside the bearing housing 2 to provide rotational support for the main shaft 1. Stepped holes 17 for installing housing sealing rings 8 are provided on the first-stage intermediate section 10, the guide fluid 7, and the last-stage intermediate section 11. Impeller sealing rings 9 are installed at both ends of the impeller 6, and the impeller sealing rings 9 and housing sealing rings 8 are rotatably engaged. The system also includes a balance drum 22 installed on the main shaft 1 and located at the pump cover 5. The axis of the stepped hole 17 has a downward eccentricity e relative to the corresponding outer circular axis of the first-stage intermediate section 10, the guide fluid 7, and the last-stage intermediate section 11 in the vertical direction. i eccentricity e i =y i -y p ;y i The eccentricity of the impeller 6 on the main shaft 1 corresponding to the positions of the first-stage intermediate section 10, the guide tube 7, and the last-stage intermediate section 11, in mm; y p The eccentricity at the balance drum 22 on the main spindle 1 is expressed in mm; where,

[0023] In the formula, G i The load at position 6 of the impeller is in kgf; i L is the axial distance from the impeller 6 to the bearing 3 closest to the balance drum 22, in cm; L is the distance between the two bearing 3 support points, in cm; E is the elastic modulus of the main shaft 1 material, in kgf / cm². 2 ;J i The average moment of inertia at position 6 of the impeller, in kgf / cm. 2 ;

[0024] In the formula, d i The diameter of the main shaft 1 at the impeller 6 position is in cm;

[0025] In the formula, G p The load at position 22 of the balance drum is expressed in kgf; p L is the axial distance from the balance drum 22 to the adjacent bearing 3, in cm; L is the distance between the two bearing 3 support points, in cm; E is the elastic modulus of the main shaft 1 material, in kgf / cm². 2 ;Jp The average moment of inertia at point 22 of the balancing drum, in kgf / cm². 2 ;

[0026] In the formula, d p The diameter of the main shaft 1 at the balance drum 22 is in cm.

[0027] According to the structure provided in this embodiment, the high-reliability multistage centrifugal pump provided in this embodiment uses an eccentric setting for the stepped holes 17 on the first stage intermediate section 10, the guide fluid 7, and the last stage intermediate section 11 for installing the housing sealing ring 8. This makes the actual axis 13 of the main shaft 1 at the mating point between the impeller sealing ring 9 of each impeller 6 and the housing sealing ring 8 coincide with the center line of the corresponding stepped hole 17. This allows the main shaft 1 to work in its own flexible position, effectively reducing the collision and wear at the mating point between the housing sealing ring 8 and the impeller sealing ring 9, thereby ensuring the operational reliability of the multistage centrifugal pump. The principle that the above structure can reduce the collision and wear at the mating point between the housing sealing ring 8 and the impeller sealing ring 9 is as follows: when the shaft diameter of the main shaft 1, the distance between the bearings 3 that serve as the fulcrum of rotation, and the load at the corresponding position on the main shaft 1 are determined, the maximum flexible eccentricity of the main shaft 1 at any position is determined. At this time, the actual rotation axis of the main shaft 1 is the actual axis 13 of the flexible bending of the main shaft 1. Since the outer circular axes of the first-stage intermediate section 10, the guide fluid 7, and the last-stage intermediate section 11 are coaxial with the axes of the bearings 3 at both ends after assembly, each stepped hole 17 is designed with an eccentric structure. In this way, the axial center position of each stepped hole 17 after assembly coincides with the actual axis 13 of the corresponding position of the main shaft 1. This fully utilizes the load-bearing capacity of the main shaft 1 itself, that is, the rotation axis of the main shaft 1 at the impeller 6 is coaxial with the rotation axis of the impeller sealing ring 9 relative to the housing sealing ring 8, so that the fit clearance between the impeller sealing ring 9 and the housing sealing ring 8 at the corresponding position is uniform and does not wear unevenly. This avoids the disadvantage of the traditional design where the axis of the stepped hole 17 is designed to be coaxial with the theoretical axis 12 of the main shaft 1 in a rigid state. In this case, the stepped hole 17 exerts a forced lifting support effect on the actual axis 13 of the main shaft 1, which causes the main shaft 1 to generate additional pressure on the lower side of the mating surface of the impeller sealing ring 9 and the housing sealing ring 8, resulting in collision and uneven wear. This effectively ensures the operational reliability of the multi-stage centrifugal pump.

[0028] In another embodiment of this application, please refer to [the relevant document / reference]. Figures 1 to 6The guide vane 7 includes an integral radial guide vane 701 and a guide vane middle section 702. An annular groove 703 is provided on one end face of the radial guide vane 701 on the guide vane 7, and an axially protruding convex ring 704 is provided on one side of the guide vane middle section 702. The annular groove 703, the convex ring 704 and the outer circle of the guide vane 7 are coaxial. There is an interference of 0.005 to 0.03 mm between the outer circle of the convex ring 704 of two adjacent guide vanes 7 and the corresponding inner wall of the annular groove 703. Correspondingly, annular grooves 703 or convex rings 704 are also provided on the first stage middle section 10 and the last stage middle section 11. In this way, the fitting between the first stage middle section 10 and the guide vane 7 and the guide vane 7 and the last stage middle section 11 can be completed. According to the structure provided in this embodiment, the coaxiality between the first-stage middle section 10, each guide fluid 7, and the last-stage middle section 11 after assembly is guaranteed. At the same time, the eccentricity direction of the stepped hole 17 on the first-stage middle section 10, each guide fluid 7, and the last-stage middle section 11 after assembly is also guaranteed to be in the same direction, and it is easy to disassemble and maintain.

[0029] In another embodiment of this application, please refer to [the relevant document / reference]. Figures 1 to 6 Each guide vane 7 has two stepped holes 17 located on the middle section 702 and the radial guide vane 701, respectively. The inner diameter of the stepped hole 17 on the middle section 702 is larger than that on the radial guide vane 701. Here, a housing sealing ring 8 installed in the stepped hole 17 at the middle section 702 mates with an impeller sealing ring 9 installed on the hub side of the impeller 6, and a housing sealing ring 8 installed in the stepped hole 17 at the radial guide vane 701 mates with an impeller sealing ring 9 installed on the suction side of the impeller 6. The sealing ring 9 is matched; by designing the inner diameter of the stepped hole 17 on the middle section 702 of the guide fluid to be larger than the inner diameter of the stepped hole 17 on the radial guide vane 701, the dimensions of the housing sealing ring 8 and the impeller sealing ring 9 are adapted to the impeller 6, effectively ensuring the stability of the multi-stage centrifugal pump; at the same time, designing the radial guide vane 701 and the middle section 702 of the guide fluid 7 as an integral structure improves the consistency of the positional accuracy of the two stepped holes 17 on the same guide fluid 7, which is conducive to ensuring assembly quality and improving the reliability of the multi-stage centrifugal pump.

[0030] In another embodiment of this application, please refer to [the relevant document / reference]. Figures 1 to 6The guide body 7 is also provided with pin hole positions A and B. The center of pin hole position A is located on the extension line of the line connecting the center of the stepped hole 17 and the center of the outer circle of the guide body 7. The line connecting the center of pin hole position B and the center of the outer circle of the guide body 7 forms an angle 18 with the line connecting pin hole position A and the center of the outer circle of the guide body 7. The angle 18 is 40 to 50 degrees; in this embodiment, the angle 18 is preferably 45 degrees. The guide body 7 is provided with short pin holes 15 and long pin holes 16. The long pin hole 16 axially penetrates the guide body 7 and includes a large hole section 1601 and a small hole section 1602 that are coaxially connected. The short pin hole 15 is a countersunk hole and opens on the same side as the large hole section 1601. The short pin holes 15 and long pin holes 16 on two adjacent guide bodies 7 are alternately formed at pin hole positions A and B, respectively. According to the structure provided in this embodiment, on the one hand, by setting short pin holes 15 and long pin holes 16, it is convenient to determine the phase of the stepped hole 17 in the circumferential direction of the guide fluid 7 and the relative position of the through hole 21 (see below) during processing, forming a reliable assembly reference. Through the cooperation of the positioning pin 14, the short pin hole 15 and the long pin hole 16, and the cooperation of the convex ring 704 and the annular groove 703, it can be ensured that the phase consistency of the stepped hole 17 on each guide fluid 7, the first stage middle section 10 and the last stage middle section 11 in the circumferential direction of the guide fluid 7 is consistent after assembly. On the other hand, by designing the short pin holes 15 and long pin holes 16 on two adjacent guide fluid 7 to be alternately formed at pin hole positions A and B, only one short pin hole 15 and one long pin hole 16 need to be processed on each guide fluid 7, thus realizing the phase consistency of the guide fluid 7. The assembly is sequential; specifically, for example, when the short pin hole 15 on the guide fluid 7 corresponding to the impeller 6 is machined at pin hole position A, the long pin hole 16 is machined at pin hole position B. Then, the long pin hole 16 on the guide fluid 7 corresponding to the impeller 6 of the next stage impeller 6 is machined at pin hole position A on the guide fluid 7, and the short pin hole 15 is machined at pin hole position B. It can be understood that the short pin hole 15 and / or long pin hole 16 are also machined on the first stage intermediate section 10 and the last stage intermediate section 11 corresponding to pin hole positions A and B of the guide fluid 7. That is, the first stage intermediate section 10, the guide fluid 7, and the last stage intermediate section 11 can be precisely positioned and connected by the locating pin 14 cooperating with the short pin hole 15 and the long pin hole 16, and by the annular groove 703 cooperating with the convex ring 704.

[0031] In another embodiment of this application, please refer to [the relevant document / reference]. Figures 1 to 6This high-reliability multistage centrifugal pump also includes a positioning pin 14, which is used to pass through the large hole section 1601 and fit into the small hole section 1602 and the short pin hole 15, so that all the stepped holes 17 are on the same side relative to the outer circle center of the guide fluid 7. In this way, since the guide fluid 7 is thick, by setting the long pin hole 16 to have a large hole section 1601 that does not cooperate with the positioning pin 14 and a small hole section 1602 that cooperates with the positioning pin 14, it is beneficial to reduce the length of the high-precision hole, thereby saving machining time and thus saving costs. On the other hand, the small hole section 1602 used for cooperation has a suitable length, which helps to reduce the difficulty of assembly and improve positioning accuracy. Furthermore, tapered sections are provided at the connection between the large hole section 1601 and the small hole section 1602 and at the opening of the short pin hole 15 to guide the positioning pin 14, which further reduces the assembly difficulty.

[0032] In another embodiment of this application, please refer to [the relevant document / reference]. Figures 1 to 6 The guide fluid 7 and the final stage intermediate section 11 are also provided with several through holes 21 evenly distributed around their circumference. The axis of the through holes 21 is parallel to the outer circle axis of the guide fluid 7. The first stage intermediate section 10 is provided with several threaded holes 23 corresponding to the through holes 21. It also includes a tensioning stud 20 that passes through the through holes 21 and has external threaded sections at both ends. The external threaded section at one end of the tensioning stud 20 is screwed into the threaded hole 23, and the external threaded section at the other end is exposed in the final stage intermediate section 11 and screwed with a nut 24. The tensioning stud 20 and the nut 24 are used to connect the first stage intermediate section 10, the guide fluid 7 and the final stage intermediate section 11 into a whole. In this way, the first stage intermediate section 10, the guide fluid 7 and the final stage intermediate section 11 constitute a stable component, which is convenient to install on the outer cylinder 4. It is understood that the installation and connection of this component with the outer cylinder 4 can adopt existing technology.

[0033] It should be noted that, in this document, the terms “comprising,” “including,” or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0034] In the description of this application, it should be understood that the terms "upper", "lower", "one end", "the other end", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application.

[0035] Furthermore, any content not described in detail in this specification is existing technology known to those skilled in the art.

[0036] Although embodiments of this application have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of this application, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A high-reliability multistage centrifugal pump, comprising an outer cylinder (4), a main shaft (1), a first-stage intermediate section (10) coaxially mounted within the outer cylinder (4), a guide fluid (7), and a final-stage intermediate section (11), wherein the guide fluid (7) is of several types and disposed between the first-stage intermediate section (10) and the final-stage intermediate section (11), and impellers (6) are mounted on the main shaft (1) in pairs with the first-stage intermediate section (10), the guide fluid (7), and the final-stage intermediate section (11), and further comprising pump covers (5) and suction stuffing boxes (19) respectively disposed at both ends of the outer cylinder (4), wherein the pump... Both the cover (5) and the suction filling box (19) are equipped with bearing bodies (2), and the bearing bodies (2) are equipped with bearings (3) for rotating support of the main shaft (1). The first stage intermediate section (10), the guide fluid (7), and the last stage intermediate section (11) are all provided with stepped holes (17) for installing housing sealing rings (8). Impeller sealing rings (9) are installed at both ends of the impeller (6). The impeller sealing rings (9) and the housing sealing rings (8) are rotatably engaged. The pump also includes a balance drum (22) installed on the main shaft (1) and located at the pump cover (5). The pump is characterized in that: The centerline of the stepped hole (17) has a downward eccentricity e in the vertical direction relative to the outer circular axis of the corresponding first-stage middle section (10), the guide fluid (7), and the last-stage middle section (11). i The eccentricity e i =y i -y p ;y i y is the eccentricity of the impeller (6) on the main shaft (1) corresponding to the positions of the first stage middle section (10), the guide fluid (7), and the last stage middle section (11). p The eccentricity at the balance drum (22) on the main shaft (1); wherein, In the formula, G i The load at the impeller (6) position; a i L is the axial distance from the impeller (6) to one of the bearings (3) near the balance drum (22); L is the distance between the fulcrums of the two bearings (3); E is the elastic modulus of the material of the main shaft (1); J is the axial distance from the impeller (6) to one of the bearings (3) near the balance drum (22); J is the distance from the impeller (6) to the bearing (3) near the balance drum (22); E is the elastic modulu i The average moment of inertia at the position of the impeller (6); In the formula, d i The shaft diameter of the main shaft (1) at the position of the impeller (6); In the formula, G p The load at the position of the balancing drum (22); a p L is the axial distance from the balance drum (22) to the adjacent bearing (3); L is the distance between the two bearing (3) pivot points; E is the elastic modulus of the spindle (1) material; J is the axial distance from the balance drum (22) to the adjacent bearing (3); ... E is the elastic modulus of the spindle (1) material; J is the axial distance from the balance drum (22) to the adjacent bearing p The average moment of inertia at the balancing drum (22); In the formula, d p The diameter of the main shaft (1) at the balance drum (22).

2. The high-reliability multistage centrifugal pump according to claim 1, characterized in that: The guide fluid (7) includes an integral radial guide vane (701) and a guide fluid middle section (702); an annular groove (703) is provided on one end face of the radial guide vane (701) on the guide fluid (7), and an axially protruding convex ring (704) is provided on one side of the guide fluid middle section (702). The annular groove (703), the convex ring (704) and the outer circle of the guide fluid (7) are coaxial, and the outer circle of the convex ring (704) of two adjacent guide fluids (7) has an interference of 0.005 to 0.03 mm with the corresponding inner wall of the annular groove (703).

3. The high-reliability multistage centrifugal pump according to claim 2, characterized in that: Each of the guide fluids (7) has two stepped holes (17) located on the middle section (702) and the radial guide vane (701), respectively. The inner diameter of the stepped hole (17) located on the middle section (702) is larger than the inner diameter of the stepped hole (17) located on the radial guide vane (701).

4. The high-reliability multistage centrifugal pump according to claim 2, characterized in that: The guide fluid (7) is also provided with pin hole position A and pin hole position B, and the center of pin hole position A is located on the extension line of the line connecting the center of the stepped hole (17) and the center of the outer circle of the guide fluid (7). The line connecting the center of pin hole position B and the center of the outer circle of the guide fluid (7) has an angle (18) with the line connecting pin hole position A and the center of the outer circle of the guide fluid (7), and the angle (18) is 40~50 degrees. The guide fluid (7) is provided with short pin hole (15) and long pin hole (16). The long pin hole (16) axially penetrates the guide fluid (7) and includes a large hole section (1601) and a small hole section (1602) coaxially connected. The short pin hole (15) is a countersunk hole and opens on the same side as the large hole section (1601). The short pin hole (15) and the long pin hole (16) on two adjacent guide fluids (7) are alternately formed at pin hole position A and pin hole position B, respectively.

5. The high-reliability multistage centrifugal pump according to claim 4, characterized in that: It also includes a positioning pin (14), which is used to pass through the large hole section (1601) and fit into the small hole section (1602) and the short pin hole (15) so that all the stepped holes (17) are on the same side relative to the outer circle center of the guide fluid (7).

6. The high-reliability multistage centrifugal pump according to claim 4, characterized in that: The guide fluid (7) and the final stage middle section (11) are also provided with a number of through holes (21) evenly distributed around their circumference. The axis of the through holes (21) is parallel to the outer circle axis of the guide fluid (7). The first stage middle section (10) is provided with a number of threaded holes (23) corresponding to the through holes (21). It also includes a tensioning stud (20) that passes through the through holes (21) and has external threaded sections at both ends. The external threaded section at one end of the tensioning stud (20) is screwed into the threaded hole (23), and the external threaded section at the other end is exposed on the final stage middle section (11) and screwed with a nut (24). The tensioning stud (20) and the nut (24) are used to connect the first stage middle section (10), the guide fluid (7) and the final stage middle section (11) into a whole.

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