Shaftless solid-liquid centrifugal pump

Abstract

The shaftless solid-liquid centrifugal pump comprises a plurality of mixed conveying units which are sequentially connected in series, each mixed conveying unit comprises a pump shell, a front guide vane, an impeller and a rear guide vane, the front guide vane, the impeller and the rear guide vane are arranged in the pump shell, the front guide vane, the impeller and the rear guide vane are coaxially and sequentially arranged in the conveying direction of the mixed conveying units, and the impeller comprises a shaft sleeve section and an outlet section which are communicated. A radial blade grid is arranged in the outlet section, the front guide vane is provided with a sleeve structure, a variable-pitch axial blade grid is arranged in the front guide vane, the front guide vane is arranged in the shaft sleeve section in a sleeved mode, the front end of the front guide vane is located outside the shaft sleeve section, and the rear end of a flow channel of the front guide vane is communicated with the inlet section of the impeller. The front guide vane of each mixed conveying unit is connected with the rear guide vane of the previous mixed conveying unit, the rear section of the pump shell is provided with a flow channel hub, and the rear guide vanes are variable wrap angle spiral blades and are fixed to the surface of the hub. The problems that particles of a solid-liquid mixed conveying system are prone to blockage in a flow channel and high in abradability are solved, and the rotation stability of the impeller is improved.

Description

Technical Field

[0001] The present invention relates to a solid-liquid mixed transportation pump, and more particularly to a shaftless solid-liquid centrifugal pump, belonging to the technical field of solid-liquid mixed transportation centrifugal pumps. Background Art

[0002] In industrial and agricultural production, centrifugal pumps are widely used to transport fluids containing a certain concentration of solid-phase particles. However, the presence of solid-phase media poses many challenges to the design and use of centrifugal pumps. First, solid-phase particles are prone to cause blockages in the flow channels and at the same time exacerbate the wear of the internal components of the pump, which seriously affects the performance and service life of the pump. Second, in application scenarios that require high transportation pressure, a multi-stage hydraulic structure is usually adopted, that is, multiple impellers and guide vanes are arranged in series. In this structure, the shaft and the rotor penetrate through the middle of the entire pump body, posing relatively high requirements for the lubrication and support of the shaft. Under harsh operating conditions with solid particles, this structure is more vulnerable to wear, resulting in a significant reduction in the equipment life. In addition, the presence of the shaft and the hub in traditional centrifugal pumps makes the flow channels of the impeller and the guide vane extend radially outward as a whole. This design not only reduces the efficiency of the pump, but also is not conducive to the smooth passage of solid particles, and at the same time exacerbates the wear of the wall surface.

[0003] To solve the above problems, the shaftless pump structure has emerged. This new structure highly couples the impeller and the motor rotor, effectively overcoming many drawbacks of traditional multi-stage solid-containing transportation centrifugal pumps. However, in order to fully utilize the advantages of the shaftless structure in terms of flow-through and hydraulics, corresponding improvements and adaptations to the hydraulic components are still needed. How to design impellers and guide vanes suitable for the shaftless structure to maximize the advantages of the shaftless structure, how to effectively reduce the wear of the internal components of the pump by solid particles while ensuring the pump efficiency, how to optimize the flow channel design to reduce the risk of blockage and at the same time improve the transportation efficiency of the solid-liquid two-phase flow are all technical problems that need to be solved urgently at present. Summary of the Invention

[0004] Based on the above background, the purpose of the present invention is to provide a shaftless solid-liquid centrifugal pump to solve the problems described in the background art.

[0005] To achieve the above invention purpose, the present invention provides the following technical solutions:

[0006] An axle - less solid - liquid centrifugal pump includes a plurality of mixed - transportation units connected in series in sequence. Each mixed - transportation unit includes a pump casing, a pre - guide vane, an impeller, and a post - guide vane disposed within the pump casing. The pre - guide vane, the impeller, and the post - guide vane are coaxially arranged in sequence along the transportation direction of the mixed - transportation unit. The impeller includes a connected shaft sleeve section and an outlet section. A radial vane cascade is provided within the outlet section. The pre - guide vane has a sleeve structure and a variable - pitch axial vane cascade is provided inside. The pre - guide vane is sleeved within the shaft sleeve section, and the front end of the pre - guide vane is located outside the shaft sleeve section. The rear end of the pre - guide vane is communicated with the outlet section of the impeller. A flow - passage hub is provided at the rear section of the pump casing. The post - guide vane is a variable - wrap - angle spiral vane and is fixed on the surface of the hub.

[0007] Preferably, the inlet diameter d a of the radial vane cascade satisfies the following relationship:

[0008] d a = d j - 0.1D;

[0009] The outlet diameter d b of the radial vane cascade satisfies the following relationship:

[0010] d b = d j - α;

[0011] In the formula, the value of α is 5 - 10 mm;

[0012] The axial height of the radial vane cascade is 2 - 3 mm.

[0013] Preferably, the rotational speed of the impeller is configured to be not less than 2950 rpm. The outer diameter D2 of the impeller satisfies the following relationship:

[0014]

[0015] In the formula, D2 is the outer diameter of the impeller, k D2 is an empirical coefficient, Q is the flow rate, and n is the pump rotational speed;

[0016] The value range of the outlet blade setting angle of the impeller is 23° - 26°;

[0017] The wrap - angle of the impeller satisfies the following relationship:

[0018]

[0019] In the formula, the value of γ is 0.7 - 0.8, and β2 represents the outlet blade setting angle of the impeller.

[0020] Preferably, along the conveying direction of the multiphase transportation unit, the cross-sectional area of the flow passage between the impeller, the rear guide vane and the front guide vane of the next-stage multiphase transportation unit changes gently. The nodes of each cross-sectional area of the flow passage follow the following relational expressions: S2 / S1 = 1.1 - 1.3, S3 / S2 = 0.7 - 0.9, S4 ≈ S1. In the formula, S1 is the cross-sectional area node of the flow passage between the front guide vane and the impeller of the current-stage multiphase transportation unit, S2 is the cross-sectional area node of the flow passage between the impeller and the rear guide vane of the current-stage multiphase transportation unit, S3 is the cross-sectional area node of the flow passage between the rear guide vane of the current-stage multiphase transportation unit and the front guide vane of the next-stage multiphase transportation unit, and S4 is the cross-sectional area node of the flow passage between the front guide vane and the impeller of the next-stage multiphase transportation unit.

[0021] Preferably, the outer diameter of the front end of the front guide vane is greater than the outer diameter of the sleeve structure of the front guide vane, and a flow guiding grid is provided at the front end of the front guide vane.

[0022] Preferably, the front guide vane is a stationary component, and the variable pitch axial cascade is a large-package angle blade structure; along the conveying direction of the multiphase transportation unit, the cross-sectional area distribution of the flow passage of the front guide vane shows a change trend of first slightly decreasing and then increasing.

[0023] Preferably, the setting angle of the outlet section of the rear guide vane adjacent to the impeller is greater than the setting angle of the outlet section of the rear guide vane far from the impeller.

[0024] Preferably, the cross-section distribution of the impeller is in an airfoil structure. Along the conveying direction of the multiphase transportation unit, the mass of the impeller increases non-linearly from the shaft sleeve section to the outlet section. The mass increase rate near the shaft sleeve section is greater than the mass increase rate near the outlet section, so that the overall mass increase curve shows a gradual change characteristic from steep to gentle. The advantage of such a setting is that it can not only increase the impact and wear resistance of imported particles, but also adjust the mass distribution of the rotor; for the combined rotor composed of the front-end cylindrical structure and the main impeller, the mass change curvature satisfies K2 = 0.3 - 0.4K1, K3 = 0.5 - 0.6K2, ensuring the operation stability of the shaftless.

[0025] Preferably, an inclined flow passage is provided in the outlet section of the impeller, and the inclination degree of the inclined flow passage is defined by the inclination angle of its center line. The value range of the inclination angle is 45° - 65°.

[0026] Compared with the prior art, the present invention has the following advantages:

[0027] A shaftless solid-liquid centrifugal pump of the present invention, through the matching structure of a pre-guide vane, an impeller, and a post-guide vane in a pump casing, improves the passability of solid particles in a flow channel, maximally solves the problems of easy blockage and high abrasion of particles in a solid-liquid mixed transportation system in the flow channel, and improves the rotational stability of the impeller. Its mixed transportation unit can adopt different numbers of series structures according to actual working conditions, enhancing the working range of the shaftless solid-liquid centrifugal pump. Brief Description of the Drawings

[0028] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the drawings in the following description are only the embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained according to the provided drawings.

[0029] Figure 1 is a schematic diagram of the internal structure of a shaftless solid-liquid centrifugal pump of the present invention;

[0030] Figure 2 is a schematic diagram of a partial structure of the impeller in the present invention;

[0031] Figure 3 is a schematic diagram of the structure of the impeller blades in the present invention;

[0032] Figure 4 is a graph of the mass change of the impeller in the present invention;

[0033] Figure 5 is a graph of the change in the flow area of a hydraulic stage in the present invention;

[0034] In the figure: 1, pre-guide vane; 2, impeller; 3, post-guide vane; 4, pump casing; 101, variable pitch axial cascade; 102, guide grid; 201, shaft sleeve section; 202, outlet section; 203, radial cascade; 401, flow channel hub. Detailed Embodiments

[0035] The following will further specifically illustrate the technical solutions of the present invention through specific embodiments and in combination with the drawings. It should be understood that the implementation of the present invention is not limited to the following embodiments, and any formal modification and / or change made to the present invention will fall within the protection scope of the present invention.

[0036] In the present invention, unless otherwise specified, all parts and percentages are in weight units, and the equipment and raw materials used can be purchased from the market or are commonly used in the art. The methods in the following embodiments are conventional methods in the art unless otherwise specified. The components or equipment in the following embodiments are general standard parts or components known to those skilled in the art, and their structures and principles can be known by those skilled in the art through technical manuals or obtained through conventional experimental methods.

[0037] The following will make a detailed description of the embodiments of the present invention with reference to the accompanying drawings. In the following detailed description, for the convenience of explanation, many specific details are set forth to provide a comprehensive understanding of the embodiments of the present invention. However, one or more embodiments can also be implemented by those skilled in the art without these specific details.

[0038] An embodiment of the present invention discloses a shaftless solid-liquid centrifugal pump, as Figure 1 shown. The shaftless solid-liquid centrifugal pump includes a plurality of mixed transportation units connected in series in sequence. Each mixed transportation unit includes a pump casing and a pre-guide vane, an impeller, and a post-guide vane arranged in the pump casing. The pre-guide vane, the impeller, and the post-guide vane are arranged coaxially in sequence along the transportation direction of the mixed transportation unit. The impeller includes a connected shaft sleeve section and an outlet section, and a radial cascade is arranged in the outlet section. The pre-guide vane has a sleeve structure and a variable pitch axial cascade is arranged inside. The pre-guide vane is sleeved in the shaft sleeve section and the front end of the pre-guide vane is located outside the shaft sleeve section. The rear end of the flow passage of the pre-guide vane is communicated with the inlet section of the impeller. The pre-guide vane of each mixed transportation unit is connected to the post-guide vane of the previous-level mixed transportation unit. A flow passage hub is arranged at the rear section of the pump casing, and the post-guide vane is a variable wrap angle spiral blade and is fixed on the surface of the hub.

[0039] Compared with the shaftless pump in the prior art, the shaft sleeve section of the impeller of this shaftless solid-liquid centrifugal pump has a long shaft sleeve structure, which is convenient for installing a small cascade inside. By cooperating with radial small holes through jet action, it can prevent small particles from aggregating in the center of the flow passage and reduce the number of collisions of large particles on the inner side of the inlet hub; the outer diameter of the impeller is smaller, while increasing the pump speed, it improves the stability of the rotor system; the wall thickness of the shaft sleeve section at the front end of the impeller is relatively thick, and stiffeners can be arranged inside for support; the inclination angle of the flow passage at the outlet section at the rear end of the impeller is increased, reducing the wear of particles on the wall surface and the congestion phenomenon at the wall outlet.

[0040] Specifically, the inlet diameter d a of the radial cascade satisfies the following relational expression,

[0041] d a = d j - 0.1D;

[0042] The outlet diameter d b of the radial cascade satisfies the following relational expression,

[0043] db = d j - α;

[0044] Wherein, the value of α is 5 to 10 mm;

[0045] The axial height of the radial cascade is 2 to 3 mm.

[0046] The above structure cooperates with the radial small-hole jet to achieve the function of driving away small particles from gathering at the center and reducing the collision of large particles on the inner hub of the inlet.

[0047] Specifically, the rotational speed of the impeller is configured to be not less than 2950 rpm, and the outer diameter D2 of the impeller satisfies the following relational expression,

[0048]

[0049] Wherein, D2 is the outer diameter of the impeller, k D2 is an empirical coefficient, Q is the flow rate, and n is the pump rotational speed.

[0050] The value range of the outlet blade setting angle of the impeller is 23° to 26°;

[0051] The wrap angle of the impeller satisfies the following relational expression,

[0052]

[0053] Wherein, the value of γ is 0.7 to 0.8, and β2 represents the outlet blade setting angle of the impeller.

[0054] The design of the impeller follows the principle of increasing the rotational speed, appropriately reducing the outer diameter, increasing the wrap angle, and reducing the outlet angle, so as to ensure that the head is not reduced and the wear is reduced.

[0055] As Figure 2 shown, in order to improve the wear resistance of the impeller and thus improve its service life, the design thickness of the inner side of the impeller is increased compared with the prior art.

[0056] As Figure 3 shown, the impeller blades adopt a structure with a blunt front and a thin rear.

[0057] Specifically, an inclined flow passage is provided in the outlet section of the impeller, and the inclination degree of the inclined flow passage is limited by the inclination angle of its center line. The value range of the inclination angle is 45° to 65°. This structure is designed to reduce the wear of the conveyed particles, avoid blockage at the wall outlet, and also increase the rotational stability.

[0058] Specifically, the outer diameter of the front end of the pre-guide vane is larger than the outer diameter of the sleeve structure of the pre-guide vane, and a flow guiding grid is provided at the front end of the pre-guide vane, so as to guide the conveyed particles to be evenly distributed along the axis.

[0059] Specifically, the front guide vane is a stationary component, and the variable pitch axial cascade is a large wrap angle blade structure. Along the conveying direction of the mixing and conveying unit, the cross-sectional area distribution of the front guide vane shows a trend of slightly decreasing first and then increasing.

[0060] Specifically, the wall thickness of the sleeve structure part where the front guide vane is connected to the outlet section of the impeller is greater than that of other parts of the sleeve structure. This structure enables good connection between the front guide vane and the outlet section of the impeller, and the flow-through area shows a uniform increase.

[0061] Specifically, the setting angle of the rear guide vane at the part adjacent to the outlet section of the impeller is greater than that at the part far from the outlet section of the impeller. This structure allows the conveyed particles to pass smoothly, and the flow-through area shows a uniform decrease.

[0062] The cooperation between the front guide vane and the rear guide vane realizes the change effect of the flow-through cross-section decreasing first and then increasing.

[0063] Specifically, as Figure 4 shown, the cross-section distribution of the impeller is in an airfoil structure, and the mass gradually increases from the shaft sleeve section to the outlet section. Along the conveying direction of the mixing and conveying unit, the mass of the impeller increases non-linearly from the shaft sleeve section to the outlet section. The mass increase rate near the shaft sleeve section is greater than that near the outlet section, making the overall mass increase curve show a gradual change characteristic from steep to gentle. The advantage of this setting is that it can not only increase the impact and wear resistance of the inlet particles, but also adjust the mass distribution of the rotor. The combined rotor composed of the front-end cylindrical structure and the main impeller has a mass change curvature that satisfies K2 = 0.3 - 0.4K1 and K3 = 0.5 - 0.6K2, ensuring the running stability of the shaftless.

[0064] Specifically, as Figure 5 shown, along the conveying direction of the mixing and conveying unit, the cross-sectional area of the flow channel between the impeller, the rear guide vane and the front guide vane of the next-stage mixing and conveying unit changes gently. The nodes of each flow channel cross-sectional area follow the following relational expressions: S2 / S1 = 1.1 - 1.3, S3 / S2 = 0.7 - 0.9, S4 ≈ S1. Here, S1 is the cross-sectional area node of the flow channel between the front guide vane of the current-stage mixing and conveying unit and the impeller of the current-stage mixing and conveying unit, S2 is the cross-sectional area node of the flow channel between the impeller of the current-stage mixing and conveying unit and the rear guide vane of the current-stage mixing and conveying unit, S3 is the cross-sectional area node of the flow channel between the rear guide vane of the current-stage mixing and conveying unit and the front guide vane of the next-stage mixing and conveying unit, and S4 is the cross-sectional area node of the flow channel between the front guide vane of the next-stage mixing and conveying unit and the impeller of the next-stage mixing and conveying unit. Figure 5It shows the change in the flow area of the shaftless solid-liquid centrifugal pump from the impeller inlet to the rear guide vane and then to the front guide vane of the next mixing and transportation unit. For the solid-liquid pumps in the prior art, the flow area gradually increases from the impeller inlet to the outlet. However, after entering the guide vane, the cross-sectional area first increases and then gradually decreases, and finally rises slowly. Generally speaking, its flow area changes greatly, being large and small alternately, resulting in unstable flow velocity of the solid-liquid mixture and an increased risk of collision and friction between solid particles and the wall surface. And from Figure 5 It can be seen that the change in the flow area of this shaftless solid-liquid centrifugal pump is not significant and tends to be flat, ensuring the smooth passage of the transported particles.

[0065] In this article, specific examples are used to elaborate on the principle and implementation mode of the present invention. The description of the above embodiments is only used to help understand the method and its core idea of the present invention. It should be pointed out that for those of ordinary skill in the art of this technology, without departing from the principle of the present invention, several improvements and modifications can be made to the present invention, and these improvements and modifications also fall within the protection scope of the claims of the present invention.

Claims

1. A shaftless solid-liquid centrifugal pump, characterized in that: The shaftless solid-liquid centrifugal pump comprises a plurality of mixed flow units connected in series in sequence, each mixed flow unit comprises a pump casing and a front guide vane, an impeller and a rear guide vane arranged in the pump casing, the front guide vane, the impeller and the rear guide vane are coaxially arranged in sequence along the conveying direction of the mixed flow unit, the impeller comprises a connected shaft sleeve section and an outlet section, a radial blade grid is arranged in the outlet section, the front guide vane has a sleeve structure and a variable pitch axial blade grid is arranged inside, the front guide vane is sleeved in the shaft sleeve section and the front end of the front guide vane is located outside the shaft sleeve section, the flow channel rear end of the front guide vane is connected to the inlet section of the impeller, the front guide vane of each mixed flow unit is connected to the rear guide vane of the previous mixed flow unit, the rear section of the pump casing is provided with a flow channel hub, and the rear guide vane is a variable wrap angle spiral blade and is fixed to the hub surface.

2. The shaftless solid-liquid centrifugal pump according to claim 1, wherein: The inlet diameter d of the radial cascade a satisfies the following relationship d a = d j -0.1D; The outlet diameter d of the radial cascade b satisfies the following relationship d b = d j - α; In the formula, the value of α is 5 to 10 mm; The axial height of the radial blade cascade is 2 to 3 mm.

3. The shaftless solid-liquid centrifugal pump according to claim 1, wherein: The rotation speed of the impeller is configured to be not less than 2950 rpm, and the outer diameter D2 of the impeller satisfies the following relationship, where D2 is the outer diameter of the impeller, and k D2 is the empirical coefficient, Q is the flow rate, and n is the pump speed; The outlet placement angle of the impeller is in the range of 23° to 26°; The wrap angle of the impeller satisfies the following relationship In the formula, the value of γ is 0.7~0.8, and β2 represents the outlet angle of the impeller.

4. The shaftless solid-liquid centrifugal pump according to claim 1, wherein: Along the conveying direction of the mixing unit, the cross-sectional area of ​​the flow channel between the impeller, the rear guide vane and the front guide vane of the next-stage mixing unit changes smoothly, and the nodes of each cross-sectional area of ​​the flow channel follow the following relationship: S2 / S1=1.1~1.3, S3 / S2=0.7~0.9, S4≈S1, wherein S1 is the cross-sectional area node of the flow channel between the front guide vane of the current mixing unit and the impeller of the current mixing unit, S2 is the cross-sectional area node of the flow channel between the impeller of the current mixing unit and the rear guide vane of the current mixing unit, S3 is the cross-sectional area node of the flow channel between the rear guide vane of the current mixing unit and the front guide vane of the next-stage mixing unit, and S4 is the cross-sectional area node of the flow channel between the front guide vane of the next-stage mixing unit and the impeller of the next-stage mixing unit.

5. The shaftless solid-liquid centrifugal pump according to claim 1, characterized in that: The front end outer diameter of the front guide vane is larger than the outer diameter of the sleeve structure of the front guide vane, and a guide grid is arranged at the front end of the front guide vane.

6. The shaftless solid-liquid centrifugal pump according to claim 1, wherein: The front guide vane is a stationary component, and the variable pitch axial blade grid is a large wrap angle blade structure; along the conveying direction of the mixed delivery unit, the flow channel cross-sectional area distribution of the front guide vane shows a trend of first slightly decreasing and then increasing.

7. The shaftless solid-liquid centrifugal pump according to claim 1, wherein: The placement angle of the rear guide vane adjacent to the outlet section of the impeller is greater than the placement angle of the rear guide vane away from the outlet section of the impeller.

8. The shaftless solid-liquid centrifugal pump according to claim 1, wherein: The cross-sectional distribution of the impeller is an airfoil structure. Along the conveying direction of the mixed delivery unit, the mass of the impeller increases nonlinearly from the shaft sleeve section to the outlet section, wherein the mass increase rate near the shaft sleeve section is greater than the mass increase rate near the outlet section, so that the overall mass increase curve presents a gradual characteristic from steep to slow.

9. The shaftless solid-liquid centrifugal pump according to claim 1, wherein: An inclined flow channel is provided in the outlet section of the impeller, and the inclination degree of the inclined flow channel is defined by the inclination angle of the center line thereof, and the value range of the inclination angle is 45° to 65°.

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