Multi-stage centrifugal pump transition flow channel

Abstract

The utility model relates to a transition flow channel of a multistage centrifugal pump. The transition flow channel comprises a delivery chamber, a flow channel diffusion section and a suction chamber, an outlet of the delivery chamber located at the upper stage is communicated with an inlet of the flow channel diffusion section, and an outlet of the flow channel diffusion section is communicated with an inlet of the suction chamber; the delivery chamber is of a double-volute structure and is symmetrically arranged about the center line of the volute, and the sum of the areas of the two symmetrical throats is equal to the area of a single volute; the flow channel diffusion section obliquely penetrates through the pump body, the internal sectional area of the flow channel diffusion section is gradually increased in the direction from an inlet to an outlet until the sectional area is equal to or slightly smaller than the inlet area of the suction chamber, the flow channel diffusion section is symmetrically arranged about the center line of the volute, and the suction chamber is symmetrically arranged about the center line of the volute. According to the utility model, radial force can be basically balanced, so that the pump operates stably, and noise and vibration of a unit are reduced; the radial size of the pump body is small and space is saved; the efficient range is wide; the axial distance of the transition flow channel is reduced, and the axial size of the pump body is reduced.

Description

TECHNICAL FIELD

[0001] The utility model relates to a transition runner, concretely relates to a multi-stage centrifugal pump transition runner which can balance radial force basically, pump runs smoothly and has wide high -efficient range. BACKGROUND

[0002] The runner from the throat of the upper stage volute to the inlet of the lower stage impeller is called transition runner, which is mainly used in multi-stage volute centrifugal pump, and the main functions are as follows: leading the outlet of the upper stage pressure chamber to the inlet of the lower stage impeller; converting the speed energy of the volute into pressure energy with minimum hydraulic loss; providing uniform velocity field for the inlet of the lower stage impeller.

[0003] At present, the transition runner design method adopted in China adopts the design method of single volute, and the design method of the middle transition section is too general, and the radial size is too large, such as the transition runner design method described in the book "Modern Pump Theory and Design".

[0004] The Chinese patent with publication number CN 107035720 A applies a multi-stage centrifugal pump transition runner structure and a design method thereof. The structure and the design method have the following problems: 1. The water suction chamber is full spiral, and there is no specific water suction chamber design method; 2. The design method has the following problems: the cross-sectional area of the upper stage water pressure chamber is approximately equal to the cross-sectional area of the diffuser elbow, the liquid from the pressure chamber to the lower stage suction chamber has no change in the overall speed, which does not meet the high-efficiency design requirement. In order to make the flow in the circumferential direction of the impeller more uniform, the liquid should be accelerated into the inlet of the impeller, and the cross-sectional area of the suction chamber should be designed to be larger; 3. The cross section of the diffuser section is a trapezoidal structure, and the axial distance of the trapezoidal structure is greater than the rectangular structure with the same area and equal radial size. The overall structure of the pump is lengthened. UTILITY MODEL CONTENTS

[0005] In view of the above problems, the main purpose of the utility model is to provide a multi-stage centrifugal pump transition runner which can balance radial force basically, pump runs smoothly and has wide high-efficiency range.

[0006] The utility model solves the above technical problems through the following scheme: a multi-stage centrifugal pump transition runner, which comprises a pressure chamber, a runner diffuser section and a suction chamber.

[0007] The outlet of the pressure chamber in the upper stage is communicated with the inlet of the runner diffuser section, and the outlet of the runner diffuser section is communicated with the inlet of the suction chamber.

[0008] The pressure-out chamber is a double-volute structure and is symmetrically arranged along the volute center line, and the sum of the two symmetric throat areas is equal to the single-volute area; the flow passage diffusion section obliquely passes through the pump body, the internal cross-sectional area gradually increases from the inlet to the outlet of the flow passage diffusion section until the cross-sectional area is equal to or slightly smaller than the inlet area of the suction chamber, the flow passage diffusion section is symmetrically arranged along the volute center line, and the suction chamber is symmetrically arranged along the volute center line.

[0009] In the embodiment of the utility model, two flow isolation baffles are cast between the two suction chambers, the baffles are horizontally arranged, and the thickness is consistent with the volute wall thickness.

[0010] In the embodiment of the utility model, each section of the pressure-out chamber is a rectangular structure.

[0011] In the embodiment of the utility model, each section of the flow passage diffusion section is a rectangular structure.

[0012] In the embodiment of the utility model, the suction chamber is designed as a semi-circular ring structure, each section is a rectangle, and the rectangular width is equal to the width b3 of the pressure-out chamber inlet.

[0013] In the embodiment of the utility model, the flow passage diffusion section is designed as a diffusion pipe with a diffusion angle, the center connecting line of the diffusion section cross section is a spatial curve distributed on a cylindrical surface, each cross section is a rectangle, and the rectangular width is equal to the width b3 of the pressure-out chamber inlet.

[0014] In the embodiment of the utility model, the circular arc angle of the flow passage diffusion section is 180°, and the outlet of the upper-stage pressure-out chamber is introduced into the inlet of the lower-stage suction chamber.

[0015] The utility model discloses a multistage centrifugal pump transition flow passage, which has the advantages that compared with the common similar technology, the utility model can balance the radial force basically, makes the pump run stably, reduces the noise and vibration of the unit, saves space due to the small radial dimension of the pump body, has a wide high-efficiency range, reduces the axial distance of the transition flow passage and the axial dimension of the pump body, and the design of the suction chamber is clear, liquid accelerates into the impeller inlet, the flow in the circumferential direction of the impeller is more uniform, the liquid flow is improved, and the efficiency is improved. BRIEF DESCRIPTION OF DRAWINGS

[0016] Figure 1 It is a schematic view of the overall structure of the utility model (line drawing).

[0017] Figure 2It is the whole structure schematic diagram No. 2 (line drawing) of the utility model.

[0018] Figure 3 It is the whole structure schematic diagram No. 3 (effect drawing) of the utility model.

[0019] Figure 4 It is the whole structure schematic diagram No. 4 (effect drawing) of the utility model.

[0020] The following is the name corresponding to the mark in the utility model:

[0021] Pressing chamber 1, flow passage diffusion section 2, suction chamber 3, flow separation baffle 4. Specific implementation

[0022] The following gives the preferred embodiment of the utility model in conjunction with the drawings to detail the technical scheme of the utility model.

[0023] Figure 1 It is the whole structure schematic diagram No. 1 (line drawing) of the utility model, Figure 2 It is the whole structure schematic diagram No. 2 (line drawing) of the utility model, Figure 3 It is the whole structure schematic diagram No. 3 (effect drawing) of the utility model, Figure 4 It is the whole structure schematic diagram No. 4 (effect drawing) of the utility model, such as Figures 1-4 The multi-stage centrifugal pump transition flow passage provided by the utility model includes pressing chamber 1, flow passage diffusion section 2 and suction chamber 3. The transition flow passage is designed as two symmetrical single flow passages, and the sum of the areas of two symmetrical throats is equal to the area of single volute.

[0024] The upper pressing chamber outlet communicates with the flow passage diffusion section inlet, and the flow passage diffusion section outlet communicates with the suction chamber inlet. The pressing chamber is a double-volute structure and is symmetrically arranged with the volute center line. Each section of the pressing chamber is a rectangular structure, and the sum of the areas of two symmetrical throats is equal to the area of single volute. The flow passage diffusion section obliquely passes through the pump body. The internal cross-sectional area gradually increases from the flow passage diffusion section inlet to the outlet until the cross-sectional area is equal to or slightly smaller than the suction chamber inlet area. The flow passage diffusion section is symmetrically arranged with the volute center line, and each section of the flow passage diffusion section is a rectangular structure. The suction chamber is designed as a semi-circular ring structure, each section is a rectangle, and is symmetrically arranged with the volute center line. Two flow separation baffles 4 are cast between the two suction chambers. The flow separation baffle 4 is horizontally arranged, and the thickness is consistent with the volute wall thickness. The flow separation baffle 4 can reduce vortex and turbulent flow, which is conducive to improving flow distribution, improving efficiency and improving cavitation performance.

[0025] The outlet chamber is designed according to the velocity coefficient method, and each section of the outlet chamber is designed as a rectangle in order to facilitate casting and save axial space. According to the velocity coefficient method in the Modern Pump Theory and Design, the eighth section area S8 (half of the eighth section area of the single volute) of the outlet chamber can be calculated, and the inlet width b3 of the outlet chamber can be calculated. In order to facilitate casting, the suction chamber is designed as a ring-shaped suction chamber, and each section of the suction chamber is a rectangle, and the rectangle width is equal to the inlet width b3 of the outlet chamber.

[0026] The flow passage diffusion section is designed as a diffusion pipe with a diffusion angle, the center connecting line of the diffusion section section is a spatial curve distributed on a cylindrical surface, each section is a rectangle, and the rectangle width is equal to the inlet width b3 of the outlet chamber.

[0027] The circular arc angle of the flow passage diffusion section is 180°, the outlet of the previous stage outlet chamber is introduced into the inlet of the next stage suction chamber, the liquid flow direction is turned by 180°, and the size of the circular arc angle is determined according to design needs. In the utility model, Figure 1 、 Figure 2 The circular arc angle is 180°.

[0028] According to the known area 2Sy at the inlet of the impeller, in order to make the flow in the circumferential direction of the impeller more uniform, the liquid should accelerate into the inlet of the impeller, so that the area Sa / Sy of the section A-A is equal to C, and C is 1.5-2.2, and the smaller ratio is suitable for specific speed ns=30-220, and the larger ratio is suitable for ns≧220.

[0029] The area of the section C-C of the ring-shaped suction chamber is equal to the area of the section A-A, SC=Sa=C*Sy=D3*b3-d*b3.

[0030] D3 is the diameter of the ring-shaped suction chamber;

[0031] d is the shaft diameter of the suction chamber, which is known;

[0032] The diameter D3 of the ring-shaped suction chamber is D3=C*Sy / b3+d (formula 1).

[0033] The inlet area of the flow passage diffusion section can be approximately considered as the eighth section area of the outlet chamber, and the outlet area of the flow passage diffusion section is the area of the section A-A. Since the section of the flow passage diffusion section is not circular, the area of each section is changed into an equivalent circular area, and the equivalent diffusion angle is calculated.

[0034]

[0035] L is the length of the center connecting line of the diffusion section flow passage;

[0036] The center connecting line of the diffusion section flow passage is a spatial curve distributed on a cylindrical surface, and when it is unfolded on a plane, the shape is the diagonal line of a rectangle, so the length of L can also be calculated by the following formula:

[0037]

[0038] r - as shown in Fig. 2, is the projection of L in the plane perpendicular to the axis, approximately considered as a circular arc, and r is the radius of the circular arc; Figure 1

[0039] m - as shown in Fig. 2, is the axial distance between the center of the extrusion chamber and the center of the suction chamber, and is also the axial distance between the starting point and the ending point of the connecting line of the center of the flow passage of the diffusion section. It is known; Figure 2

[0040] The formula 2 and the formula 3 are converted to obtain:

[0041]

[0042] In the formula, the equivalent diffusion angle θ is in the range of 7° to 13°;

[0043] The value of θ is selected, and the value of r is calculated. According to the overall structure of the multistage pump, it is determined whether the value of r is reasonable. If the value of r meets the design requirements, the value of θ is feasible; if the value of r does not meet the structural design requirements, the value of θ is re-assigned, and the value of r is calculated; until the value of r meets the design requirements.

[0044] According to the calculated value of r, and knowing the starting point k and the ending point P of the circular arc where the radius r is located, the circular arc can be drawn. The point k is the centroid of the eighth cross section of the volute, and the point P is the centroid of the A-A cross section.

[0045] The diffusion section of the flow passage is equally divided into n sections according to the length of L, and the value of n is in the range of 2 to 8. According to the length of L, the longer the length of L, the larger the value of n. The equivalent circular area of each section is calculated by S8 and the equivalent diffusion angle θ.

[0046]

[0047] Since each cross section of the diffusion section is a rectangle, the width of the rectangle is equal to the width b3 of the inlet of the extrusion chamber, and the length of the rectangle, i.e. the height of the cross section, is calculated by the formula:

[0048] Connecting each cross section in order from the inlet to the outlet of the diffusion section, the shape of the flow passage of the diffusion section is obtained; the design of the transition flow passage is completed.

[0049] ​​The utility model discloses can balance radial force basically, make pump smooth operation, reduced the noise and vibration of unit;Pump body radial size is small, save space;Efficient range is wide;The axial distance of transition flow channel is reduced, and the axial size of pump body is reduced. Meanwhile, the utility model discloses the design of suction chamber, liquid accelerates into impeller entrance, and the flow of impeller circumferential direction is more uniform, improves the flow of liquid, improves the efficiency. The utility model discloses the cross section area of extrusion chamber and suction chamber as the benchmark, gradually diffusing design concept is used to the diffusion degree of intermediate flow channel, more conforms to the flow rule of pump. The whole calculation process is simple, and the calculation speed is fast, and the design time is shortened;The utility model discloses especially be applicable to the working condition of small flow high lift.

[0050] The above shows and describes the basic principle and main features of the utility model and the advantages of the utility model. The skilled person in the art should understand that the utility model is not limited to the above examples, and the above examples and descriptions in the specification are only to illustrate the principle of the utility model. Without departing from the spirit and scope of the utility model, the utility model can have various changes and improvements. These changes and improvements fall within the scope of the claimed utility model, and the scope of protection of the utility model is defined by the appended claims and their equivalents.

Claims

1. A multi-stage centrifugal pump transition flow passage characterized by: The multi-stage centrifugal pump transition flow channel comprises a discharge chamber, a flow channel diffusion section and a suction chamber; The outlet of the discharge chamber at the upper stage is communicated with the inlet of the flow channel diffusion section, and the outlet of the flow channel diffusion section is communicated with the inlet of the suction chamber; The discharge chamber is of double volute structure and symmetrically arranged with respect to the volute center line, and the sum of the throat areas of the two symmetric parts is equal to the area of a single volute; the flow channel diffusion section obliquely passes through the pump body, the internal cross-sectional area of the flow channel diffusion section gradually increases from the inlet to the outlet, until the cross-sectional area is equal to or slightly smaller than the inlet area of the suction chamber, the flow channel diffusion section is symmetrically arranged with respect to the volute center line, and the suction chamber is symmetrically arranged with respect to the volute center line.

2. The multi-stage centrifugal pump transition channel of claim 1, wherein: Two flow separation baffles are cast between the two suction chambers, and the baffles are horizontally arranged and have a thickness consistent with the volute wall thickness.

3. The multi-stage centrifugal pump transition channel of claim 1, wherein: The cross section of the discharge chamber is of rectangular structure.

4. The multi-stage centrifugal pump transition channel of claim 1, wherein: The cross section of the flow channel diffusion section is of rectangular structure.

5. The multi-stage centrifugal pump transition channel of claim 1, wherein: The suction chamber is designed to be a semi-circular ring structure, and each cross section is of rectangular structure with a width equal to the width b3 of the inlet of the discharge chamber.

6. The multi-stage centrifugal pump transition channel of claim 1, wherein: The flow channel diffusion section is designed to be a diffusion pipe with a diffusion angle, the center connecting line of the cross section of the diffusion section is a spatial curve distributed on a cylindrical surface, each cross section is of rectangular structure with a width equal to the width b3 of the inlet of the discharge chamber.

7. The multi-stage centrifugal pump transition channel of claim 1, wherein: The circular arc angle of the flow channel diffusion section is 180°, and the outlet of the discharge chamber at the upper stage is introduced into the inlet of the suction chamber at the lower stage.

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