Horizontal middle-open type multi-stage centrifugal pump transition flow channel and multi-stage centrifugal pump

Abstract

The invention provides a horizontal middle-open type multi-stage centrifugal pump transition runner and a multi-stage centrifugal pump, the two transition runners are symmetrical about the center of a volute chamber, the transition runners are used for communicating the volute chamber with a circular cavity for installing a next-stage impeller, each transition runner comprises a diffusion section, and the diffusion sections are gradually expanded in the flow direction; an acute angle is formed between the inlet of the diffusion section and the partition house and the horizontal center line and used for reducing the radial length of the diffusion section. The included angle between the inlet of the diffusion section and the horizontal center line and the included angle between the partition house and the horizontal center line are not larger than 30 degrees. And a guide plate is arranged in the transition flow channel at the front part of the circular cavity and is used for dividing the fluid before entering the circular cavity into two streams of fluid. The inner flowing structure is improved by changing the shape of the outer edge of the transition flow channel, the hydraulic power of fluid is reduced, and the purpose of further improving the lift and efficiency of the middle-open type multi-stage centrifugal pump at the low specific speed level is achieved.

Description

Technical Field

[0001] The invention relates to the field of fluid machinery, and in particular to a horizontal split-case multistage centrifugal pump transition channel and a multistage centrifugal pump. Background Art

[0002] The transition channel is mainly suitable for horizontal split multistage centrifugal pumps. The volute of this type of pump is integrally cast, the rotor is supported at both ends, and the pump body is supported in the center, with good stability. It has high reliability and is easy to maintain. The transition channel is the flow channel for liquid to flow between stages. The quality of the transition channel design not only determines the shape and castability of the pump body, but also has a certain impact on the efficiency of the pump.

[0003] The transition channel refers to the channel from the first-stage vortex throat to the inlet of the next-stage impeller (adjacent or non-adjacent). Its functions are:

[0004] 1. Lead the outlet of the first-stage water pressure chamber to the inlet of the other-stage impeller, and the liquid flow direction is turned 180°;

[0005] 2. Convert the velocity energy of the fluid flowing out of the vortex chamber into pressure energy and reduce hydraulic losses;

[0006] 3. Provide uniform inflow to the next stage impeller inlet.

[0007] At present, according to the different transition methods, it is generally divided into short transition flow channel and long transition flow channel. The existing transition flow channel structure has two forms: radial diffusion and oblique diffusion. Radial diffusion means that the transition flow channel has a diffusion section, which is located on the center line of the impeller. It diffuses to the diffusion section along the circumference of the volute of the diffusion flow channel at a certain diffusion angle and then enters the suction chamber of the next level. Oblique diffusion means that the diffusion flow channel does not diffuse along the circumference of the volute, but passes through the pump body obliquely and directly enters the next level of water absorption chamber. The efficiency of the radial diffusion transition flow channel is higher than that of the oblique diffusion flow channel, but the external dimensions are larger and the pump body structure is not compact. Although the oblique diffusion flow channel has a compact structure, its hydraulic efficiency is reduced and the cavitation of the water pump increases.

[0008] At present, the transition flow channels of domestic horizontal split-case multi-stage centrifugal pumps all adopt a combination of long transition flow channels and semi-spiral suction chambers. This not only makes the pump body too large in size and the structure not compact, but also increases the cavitation margin of the pump, resulting in large losses and reduced hydraulic efficiency. Summary of the invention

[0009] In view of the deficiencies in the prior art, the present invention provides a horizontal split-center multistage centrifugal pump transition flow channel and a multistage centrifugal pump, which improves the internal flow structure by changing the outer edge shape of the transition flow channel and reduces the fluid hydraulics, thereby further improving the head and efficiency of the low specific speed horizontal split-center multistage centrifugal pump. The horizontal split-center multistage centrifugal pump transition flow channel proposed by the present invention has the characteristics of simple structure, convenient processing, easy operation and implementation, etc.

[0010] The present invention achieves the above technical objectives through the following technical means.

[0011] A horizontal split-center multistage centrifugal pump transition channel, wherein two transition channels are symmetrical along the center of a vortex chamber, and the transition channel is used to connect the vortex chamber with a circular cavity where a next-stage impeller is installed. The transition channel includes a diffusion section, and the diffusion section gradually expands along the flow direction. The inlet and the partition position of the diffusion section form an acute angle with the horizontal center line, so as to reduce the radial length of the diffusion section.

[0012] Furthermore, the angle between the inlet and the compartment position of the diffusion section and the horizontal center line does not exceed 30°.

[0013] Furthermore, a guide plate is provided in the transition flow channel located in the front part of the circular cavity, which is used to divide the fluid before entering the circular cavity into two streams.

[0014] Furthermore, a recessed area is provided at the outer edge of the transition flow channel facing the guide plate, so as to reduce the influence of centrifugal force on the fluid, thereby dividing the fluid before entering the circular cavity into two flows of fluid with equal flow rates.

[0015] Furthermore, by adding at least one singular point on the outer edge profile of the transition flow channel, the outer edge of the transition flow channel presents a concave area that is concave inwards.

[0016] Furthermore, a de-rotation plate is provided in the circular cavity, and the de-rotation plate is located at the entrance of the transition channel into the circular cavity.

[0017] A horizontal split case multistage centrifugal pump comprises the horizontal split case multistage centrifugal pump transition flow channel.

[0018] The beneficial effects of the present invention are:

[0019] 1. The transition channel of the horizontal split multistage centrifugal pump described in the present invention has a partition position and a fluid inlet that form an acute angle of no more than 30° with the horizontal line to reduce the radial length of the diffusion section; and there is a recessed area on the outer edge of the transition channel, which is flush with the center of the guide plate to reduce the influence of centrifugal force on the fluid, so that the fluid can flow through the guide plate better, so that the fluid flow on the left and right sides of the guide plate is equal.

[0020] 2. The horizontal split-center multi-stage centrifugal pump transition channel described in the present invention, in the prior art, after the fluid flows through the diffusion section, due to the effect of centrifugal force, the fluid will be more biased to flow to the right side of the guide plate, resulting in unequal fluid flow on the left and right sides of the guide plate, uneven pressure distribution, and great hydraulic loss. Therefore, the present invention changes the outer edge of the transition channel so that there is a singular point on its outer edge profile, resulting in a partially recessed area of ​​the shell, thereby reducing the influence of centrifugal force on the fluid, making the fluid flow on the left and right sides of the guide plate equal and the pressure distribution more uniform.

[0021] 3. The horizontal split-case multistage centrifugal pump transition channel of the present invention has the characteristics of simple structure, convenient processing, and easy operation and implementation. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. The drawings described below are some embodiments of the present invention. For ordinary technicians in this field, it is obvious that other drawings can be obtained based on these drawings without paying any creative work.

[0023] Figure 1 It is a two-dimensional diagram of the transition flow channel of the horizontal split multi-stage centrifugal pump described in the present invention.

[0024] Figure 2 It is a structural schematic diagram of the transition flow channel of the horizontal split-case multi-stage centrifugal pump described in the present invention.

[0025] Figure 3 It is a three-dimensional model diagram of the transition flow channel of the horizontal split multi-stage centrifugal pump described in the present invention.

[0026] Figure 4 This is a comparison diagram of the lift of the transition channel of the horizontal split-case multi-stage centrifugal pump described in the present invention.

[0027] Figure 5 This is a comparison diagram of the efficiency of the transition channel of the horizontal split-case multistage centrifugal pump described in the present invention.

[0028] In the figure:

[0029] 1-vortex chamber; 2-diffusion section; 3-guide plate; 4-anti-rotation plate; 5-partition; 6-fluid inlet; 7-outer edge depression; 8-circular cavity. DETAILED DESCRIPTION

[0030] Embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present invention, and should not be construed as limiting the present invention.

[0031] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "axial", "radial", "vertical", "horizontal", "inner", "outer" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first" and "second" are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, the meaning of "multiple" is two or more, unless otherwise clearly and specifically defined.

[0032] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be an indirect connection through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0033] like Figure 1 and Figure 2 As shown, the horizontal split-center multi-stage centrifugal pump transition channel of the present invention has two transition channels symmetrically along the center of the vortex chamber 1. The transition channel is used to connect the vortex chamber 1 with the circular cavity 8 where the next-stage impeller is installed. The transition channel includes a diffusion section 2, which gradually expands along the flow direction. The inlet and partition 5 of the diffusion section 2 form an acute angle with the horizontal center line, which is used to reduce the radial length of the diffusion section. This helps to reduce the hydraulic loss of the fluid in the diffusion section and can also make the pump body structure compact. Generally speaking, the angle between the inlet and partition 5 of the diffusion section 2 and the horizontal center line does not exceed 30°, that is, the angle range is 0 to 30°. Figure 1 As shown, the embodiment is a model in which the inlet of the diffuser section 2 is deflected by 30° from the horizontal center line.

[0034] like Figure 2 and Figure 3 As shown, a guide plate 3 is provided in the transition channel located in front of the circular cavity 8, which is used to divide the fluid before entering the circular cavity into two streams. There is a recessed area 7 at the outer edge of the transition channel, which is flush with the center of the guide plate 3 to reduce the influence of centrifugal force on the fluid, so that the fluid can flow through the guide plate 3 better, so that the fluid flow on the left and right sides of the guide plate 3 is equal.

[0035] In the embodiment, the recessed area 7 is to add at least one singular point on the outer edge profile of the transition channel, so that the outer edge of the transition channel appears to be recessed inward. Therefore, the recessed area 7 can be a few inwardly recessed singular points added on the outer edge profile of the transition channel, or it can be an arc, curve or intersecting line formed by adding continuous inwardly recessed singular points on the outer edge profile of the transition channel. When the fluid flows through the diffusion section 2, due to the influence of centrifugal force, the fluid will deviate to the right side of the guide plate 3 and flow along the outer edge of the transition channel, which will cause uneven flow and uneven pressure distribution on both sides of the guide plate 3, generate larger vortices, and cause great hydraulic losses. Therefore, by adding a singular point to the outer edge profile, a recessed area 7 will appear on the outer edge of the model, which can press the fluid to the other side of the guide plate 3, so that the fluid flow on both sides of the guide plate 3 is equal, the pressure distribution is more uniform, and the hydraulic losses are reduced.

[0036] The circular cavity 8 is provided with a de-spinning plate 4, which is located at the entrance of the transition channel into the circular cavity. When the fluid flows into the circular cavity 8 from both sides, the de-spinning plate 4 provided therein can eliminate the motion circulation of the fluid and reduce the pre-spinning of the fluid, so that the fluid can flow into the inlet of the next stage impeller more evenly.

[0037] Figure 4 Shown is a head comparison diagram of the transition flow channel of the horizontal split-center multistage centrifugal pump described in the present invention. It can be seen from the figure that the present invention not only ensures the head under rated conditions, but also improves the head under low flow conditions, thereby eliminating the hump phenomenon of the characteristic curve and improving the operating stability of the horizontal split-center multistage centrifugal pump under low flow conditions. Figure 5 The figure shows the efficiency comparison of the transition channel of the horizontal split multistage centrifugal pump of the present invention. It can be seen from the figure that the efficiency of the present invention under the rated working condition is improved by 3-4 percentage points, and the high efficiency zone is ensured to appear near the rated working condition.

[0038] A horizontal split case multistage centrifugal pump comprises the horizontal split case multistage centrifugal pump transition flow channel.

[0039] It should be understood that although this specification is described according to various embodiments, not every embodiment contains only one independent technical solution. This narrative method of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment may also be appropriately combined to form other implementation methods that can be understood by those skilled in the art.

[0040] The series of detailed descriptions listed above are only specific descriptions of feasible embodiments of the present invention. They are not intended to limit the scope of protection of the present invention. All equivalent embodiments or changes that do not deviate from the technical spirit of the present invention should be included in the scope of protection of the present invention.

Claims

1. A horizontal split-center multistage centrifugal pump transition channel, wherein the two transition channels are symmetrical along the center of a vortex chamber (1), and the transition channel is used to connect the vortex chamber (1) with a circular cavity connected to the inlet of the next stage impeller, characterized in that: The transition flow channel comprises a diffuser section (2), the diffuser section (2) gradually expands along the flow direction, and the inlet and the partition (5) of the diffuser section (2) are located at an acute angle to the horizontal center line, so as to reduce the radial length of the diffuser section.

2. The horizontal split-case multistage centrifugal pump transition passage according to claim 1, characterized in that: The angle between the inlet of the diffusion section (2) and the compartment (5) and the horizontal center line does not exceed 30°.

3. The horizontal split-case multistage centrifugal pump transition passage according to claim 1, characterized in that: A guide plate (3) is provided in the transition flow channel located in the front part of the circular cavity, and is used to divide the fluid before entering the circular cavity into two streams of fluid.

4. The horizontal split-case multistage centrifugal pump transition channel according to claim 3, characterized in that: A recessed area (7) is provided on the outer edge of the transition flow channel facing the guide plate (3), so as to reduce the influence of centrifugal force on the fluid, thereby dividing the fluid before entering the circular cavity into two flows of fluid with equal flow rates.

5. The horizontal split-case multistage centrifugal pump transition passage according to claim 4, characterized in that: By adding at least one singular point on the outer edge profile of the transition flow channel, the outer edge of the transition flow channel presents a concave area (7) that is concave inwards.

6. The horizontal split-case multistage centrifugal pump transition passage according to claim 1, characterized in that: A de-rotation plate (4) is provided in the circular cavity, and the de-rotation plate (4) is located at the entrance of the transition channel into the circular cavity.

7. A horizontal split-case multistage centrifugal pump, characterized in that: The invention comprises the transition flow passage of a horizontal split-center multistage centrifugal pump as described in any one of claims 1 to 6.

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