CN114607613A - Multistage semi-open type centrifugal pump capable of reducing abrasion - Google Patents

Abstract

The invention belongs to the technical field of centrifugal pumps, and discloses a multi-stage semi-open centrifugal pump with reduced wear, comprising a semi-open impeller, a guide vane and a pump body. The semi-open impeller includes a plurality of cylindrical blades, and the blades include blade suction Surface and blade pressure surface, the blade inlet is trimmed to be streamlined and thinned as much as possible. The semi-open impeller in the present invention increases the gap between the pump body and the rear cover plate of the impeller by removing the front cover plate of the impeller, avoiding the collision frequency between the front cover plate and the particles on the side of the front pump cavity and the wall surface, thereby reducing the distance between the impeller and the front cover. Wear at the pump chamber. And the streamlined outlet at the rear end of the back cover reduces the hydraulic loss and wear of the outflow, and the tip clearance controlled by the shape of the pump body can reduce the hydraulic loss of the semi-open impeller. Through the numerical simulation results, it is concluded that the semi-open impeller structure has the characteristics of greatly improving the wear of the impeller and the front pump cavity, which is of great significance for improving the operation stability of the multi-stage centrifugal pump, reducing the failure rate and improving the service life.

Description

A multi-stage semi-open centrifugal pump with reduced wear

technical field

The invention belongs to the technical field of centrifugal pumps, in particular to a multi-stage semi-open centrifugal pump with reduced wear.

Background technique

In the industrial field, more than 30% of energy is consumed due to wear and friction, and equipment loss due to wear accounts for more than 60% of the total loss. As an important fluid conveying equipment, centrifugal pumps are widely used in mining, metallurgy, water conservancy and other fields. The same multi-stage centrifugal pump is the main equipment for pumping groundwater. The groundwater in northern my country contains a lot of sediment, and the problem of pump wear caused by sandy water is very prominent. Multistage centrifugal pumps perform well in drainage operations. As movable drainage equipment, they are often used in rescue and disaster relief. The conveying medium inevitably contains insoluble solid particles such as sediment, coal slime, cinder, etc. Since the medium conveyed by the pump usually contains solid particles, the multi-stage centrifugal pump is easily affected by the erosion and wear of the particles, resulting in head drop and shutdown. , poor reliability, etc.

At present, wear-related prediction and protective measures have always been the research hotspots of experts and scholars in the pump industry. In addition, the measures for centrifugal pumps to deal with wear are often to reduce the number of blades to increase the clearance and increase the thickness of the blades, and do not involve more than half-open impellers.

SUMMARY OF THE INVENTION

The purpose of the present invention is to overcome the deficiencies in the prior art, provide a new idea for reducing wear, and provide a multi-stage semi-open centrifugal pump that reduces wear. The semi-open impeller in the multi-stage semi-open centrifugal pump of the present invention increases the gap between the pump body and the rear cover plate of the impeller by removing the front cover plate of the impeller, so as to avoid the collision between the front cover plate and the particles on the side of the front pump cavity and the wall surface , thereby reducing the wear at the impeller and the front pump chamber. The streamlined structure at the inlet of the blade and the streamlined outlet at the tail end of the rear cover reduce the hydraulic loss and wear of the outflow, and the tip clearance controlled by the shape of the pump body can reduce the hydraulic loss of the semi-open impeller.

To achieve the above object, the technical scheme adopted in the present invention is as follows:

A multi-stage semi-open centrifugal pump with reduced wear, comprising a semi-open impeller, guide vanes and a pump body, the semi-open impeller is located between the guide vanes and the pump body of the multi-stage pump, wherein the semi-open impeller includes vanes , The streamline structure of the rear cover plate, the inlet of the blade and the streamline structure of the outlet at the rear end of the rear cover plate. Multiple blades are evenly distributed on the rear cover plate along the circumferential direction. Viewed from the inlet, the semi-open impeller rotates clockwise, and the rear cover plate is in a clockwise direction. Disc-shaped, with cylindrical leaves.

Preferably, the parameters of the semi-open impeller are: impeller inlet diameter D _j =40mm, blade inlet diameter D ₁ =26mm, impeller hub diameter dh =18mm, blade inlet width _{b 1} =20mm, blade inlet placement angle β ₁ =41.2985°, impeller outer diameter (outlet diameter) D ₂ =78mm, blade outlet width b ₂ =11mm, blade outlet placement angle β ₂ =23°, and the number of blades Z=6.

Preferably, the inlet portion of the blade is trimmed into a streamlined structure through rounded corners.

Preferably, the rear end outlet of the rear cover plate is trimmed into a streamlined structure through rounded corners.

Preferably, the tip clearance between the tip of the semi-open impeller blade and the pump body is controlled by the shape of the pump body, and the tip clearance h=0.5mm˜2mm.

The beneficial effects of the present invention are:

The semi-open impeller in the multi-stage semi-open centrifugal pump of the present invention increases the gap between the pump body and the rear cover plate of the impeller by removing the front cover plate of the impeller, so as to avoid the collision between the front cover plate and the particles on the side of the front pump cavity and the wall surface , thereby reducing the wear at the impeller and the front pump chamber. The streamlined structure at the inlet of the blade and the streamlined outlet at the tail end of the rear cover reduce the hydraulic loss and wear of the outflow, and the tip clearance controlled by the shape of the pump body can reduce the hydraulic loss of the semi-open impeller. The semi-open impeller puts forward effective protective measures for the damage law and occurrence position of wear, which is of great significance to reduce the production cost and the loss caused by equipment failure and shutdown, and to improve the operation efficiency of the equipment. The semi-open impeller is of great significance to improve the operation stability of the multistage centrifugal pump, reduce the failure rate and improve the service life.

Description of drawings

Fig. 1 is the cross-sectional structural schematic diagram of the first stage of the multistage centrifugal pump according to the present invention

Figure 2 is a schematic diagram of the axial cross-sectional structure of the semi-open impeller of a multi-stage centrifugal pump

Figure 3 is a top view of the semi-open impeller of a multistage centrifugal pump

In the picture: 1-semi-open impeller, 2-guide vane, 3-pump body, 4-vane, 5-back cover, 6-blade inlet streamline structure, 7-impeller outlet streamline structure, 8-blade tip clearance.

Detailed ways

The present invention will be further described below with reference to the accompanying drawings and embodiments.

Example 1:

The multi-stage semi-open centrifugal pump includes a semi-open impeller 1, a guide vane 2 and a pump body 3, and the semi-open impeller 1 is located between the guide vane 2 and the pump body 3 of the multi-stage pump; 1. It includes a blade 4, a rear cover 5, a streamlined structure 6 at the inlet of the blade, and a streamlined structure 7 at the tail end of the rear cover. The rear cover is disc-shaped, and a plurality of blades are evenly distributed on the rear cover in the circumferential direction. See that the impeller rotates clockwise and the blades are cylindrical blades.

The selected parameters are impeller inlet diameter D _j = 40mm, blade inlet diameter D ₁ = 26mm, impeller hub diameter dh = 18mm, blade inlet width _{b 1} = 20mm, blade inlet placement angle β ₁ = 41.2985°, impeller outer diameter (outlet Diameter) D ₂ =78mm, vane outlet width b ₂ =11mm, vane outlet placement angle β ₂ =23°, vane number Z=6. The front cover of the impeller is removed, the inlet of the blade is trimmed to a rounded corner of 1 mm, and the outlet of the rear end of the rear cover is trimmed to a rounded corner with a radius of 1.5 mm.

The working principle of the present invention:

The semi-open impeller in the multi-stage semi-open centrifugal pump of the present invention increases the gap between the pump body and the rear cover plate of the impeller by removing the front cover plate of the impeller, so as to avoid the collision between the front cover plate and the particles on the side of the front pump cavity and the wall surface , thereby reducing the wear at the impeller and the front pump chamber. The streamlined structure at the inlet of the blade and the streamlined structure at the tail end of the rear cover reduce the hydraulic loss and wear of the outflow, and the tip clearance controlled by the shape of the pump body can reduce the hydraulic loss of the semi-open impeller. Through the numerical calculation of Euler-Lagrange bidirectional coupling in CFX 2019R1, the wear conditions of the closed impeller and the semi-open impeller under the same boundary conditions under the same parameters are obtained. Compared with the closed impeller, the wear of the semi-open impeller in the three-stage centrifugal pump is reduced by 78.44%. This proves that the semi-open impeller can greatly reduce the wear of the impeller and the front pump cavity, and the semi-open impeller can improve the operation stability of the multi-stage centrifugal pump, reduce the failure rate and improve the service life.

Claims (7)

1. The multistage semi-open centrifugal pump capable of reducing wear is characterized by comprising a semi-open impeller (1), a guide vane (2) and a pump body (3), wherein the semi-open impeller (1) is positioned between the guide vane (2) and the pump body (3) of the multistage pump; semi-open impeller (1) includes blade (4), back shroud (5), blade import streamlined structure (6) and back shroud tail end export streamlined structure (7), and a plurality of blades (4) are along circumference evenly distributed on back shroud (5), and it is clockwise rotation to see semi-open impeller (1) from the import.

2. A multistage semi-open centrifugal pump with reduced wear according to claim 1, characterized in that the vanes (4) are cylindrical vanes.

3. A multistage semi-open centrifugal pump with reduced wear according to claim 1, characterized in that the back cover plate (5) is disc-shaped.

4. A multistage semi-open centrifugal pump with reduced wear according to claim 1, characterized in that the parameters of the semi-open impeller (1) are: impeller inlet diameter D_j40mm blade inlet diameter D₁26mm, impeller hub diameter d_h18mm, blade inlet width b₁20mm blade inlet setting angle beta₁41.2985 ° for the impeller outer diameter, i.e. the outlet diameter D₂78mm, blade exit width b₂11mm blade outlet setting angle beta₂23 DEG, and the number of the blades Z is 6.

5. The multistage semi-open centrifugal pump of claim 1, wherein said vane inlet region is rounded to streamline configuration.

6. The multistage semi-open centrifugal pump of claim 1, wherein the outlet at the aft end of the back cover plate is rounded off to a streamlined configuration.

7. The multistage semi-open centrifugal pump of claim 1, wherein the tip clearance between the tip of the semi-open impeller blade and the pump body is 0.5mm to 2 mm.

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