JP7476071B2 - Vertical Pump - Google Patents

Description

The present invention relates to a vertical pump, and in particular to a vertical pump equipped with a vortex prevention device that suppresses the occurrence of air suction vortexes.

When using a vertical shaft pump (hereafter simply referred to as "pump") that is installed in a suction sump with a free surface, fluctuations in the water level in the suction sump or changes to specifications such as an increase in discharge volume when upgrading the pump can cause the flow field in the suction sump to change, resulting in an air-sucking vortex that can reach the bellmouth, the suction port of the suction casing that houses the impeller, from the water surface.

This air-sucking vortex often occurs when the flow of fluid near the water surface in the suction tank passes through the suction casing, separating on the downstream side of the suction casing and creating a swirling flow (hereafter referred to as "swirling flow"). If such a vortex is sucked into the pump, it can cause problems such as excessive vibration and reduced performance, and can also cause damage to the pump.

A pump has been disclosed in which prevention plates 34 (vortex suppression plates) are arranged on the left and right downstream sides of the pump suction pipe 30 (suction casing) to prevent the generation of air suction vortices (see paragraph 0006 and Figure 11 of Patent Document 1).

The pump described in Patent Document 1 suppresses the generation of swirling flow downstream of the pump suction pipe 30 by allowing the flow from the upstream side of the pump suction pipe 30 to flow out from the downstream side through the gap between the pump suction pipe 30 and the prevention plate 34.

JP 2001-041200 A

However, in the pump described in Patent Document 1, if the flow velocity in the suction tank increases or if drift occurs upstream of the suction tank, the flow from the upstream side of the pump suction pipe 30 (suction casing) may separate at the outer middle part of the prevention plate 34 (vortex suppression plate), creating a swirling flow that can cause an air suction vortex. In other words, installing a vortex suppression plate itself may create an air suction vortex.

The object of the present invention is to provide a vertical pump that can better suppress the occurrence of air-suction vortexes that occur when the flow rate in the suction tank increases.

In order to achieve the above object, the vertical pump according to the present invention includes a suction casing that houses an impeller, and a vortex prevention device that suppresses the generation of air-suction vortexes. The vortex prevention devices are disposed on the left and right of the downstream side of the suction casing in the mainstream direction of the fluid in a suction tank in which the suction casing is installed, facing the suction casing. The vortex prevention device includes a first vortex suppression plate and a second vortex suppression plate disposed downstream of the first vortex suppression plate in the mainstream direction. The first vortex suppression plate is installed farther from the central axis of the suction casing than the second vortex suppression plate, the first vortex suppression plate is an arcuate plate having a first radius about the central axis, the second vortex suppression plate is an arcuate plate having a second radius about the central axis, the first radius is larger than the second radius, a downstream end of the first vortex suppression plate in the mainstream direction and an upstream end of the second vortex suppression plate in the mainstream direction overlap at a circumferential position about the central axis, and portions of the first vortex suppression plate other than the downstream end and portions of the second vortex suppression plate other than the upstream end do not overlap, and a flow path is provided on the downstream side of the second vortex suppression plate in the mainstream direction .

The present invention provides a vertical pump that can further suppress the occurrence of air suction vortexes.

1 is a schematic vertical sectional view of a vertical pump according to a first embodiment of the present invention; FIG. FIG. 2 is an enlarged side view showing the periphery of the vortex prevention device according to the embodiment. FIG. 3 is a cross-sectional view taken along line III-III in FIG. 2. FIG. 2 is a view of the periphery of the vortex prevention device according to the embodiment, as viewed from the downstream side. FIG. 2 is an enlarged perspective view showing the periphery of the vortex prevention device according to the embodiment. FIG. 2 is a plan view showing a schematic flow around a vortex prevention device composed of a single vortex suppression plate. FIG. 2 is a plan view showing a schematic flow around a vortex suppression device according to the present embodiment, which is divided into a first vortex suppression plate and a second vortex suppression plate. FIG. 11 is a view of the periphery of the vortex prevention device according to the second embodiment, as viewed from the downstream side. FIG. 11 is a view of the periphery of the vortex prevention device according to the third embodiment, as viewed from the downstream side.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described in detail with reference to the accompanying drawings.
In the drawings shown below, the same reference numerals are used to refer to common or similar components, and duplicated explanations will be omitted as appropriate. Furthermore, the size and shape of the components may be exaggerated or distorted for ease of explanation.

First Embodiment
A first embodiment of the present invention will be described with reference to FIGS. 1 to 7. FIG.
FIG. 1 is a schematic vertical sectional view of a vertical pump 100 according to a first embodiment of the present invention.
As shown in FIG. 1, a vertical pump 100 is installed in, for example, a waterway 1 (suction tank) of a drainage pumping station.

The vertical pump 100 comprises a rotating shaft 2 aligned in the vertical direction, an impeller 3 attached to the lower end of the rotating shaft 2, and a suction casing 4 that houses the impeller 3. The suction casing 4 is installed at a predetermined distance from the base 12 of the waterway 1, the left and right side wall surfaces 15 of the waterway 1, and the downstream wall surface 16 of the waterway 1.

The suction casing 4 includes a casing liner 41, a bell mouth (suction port) 42, and a bowl portion 43. The casing liner 41 is disposed on the shroud side of the impeller 3. The bell mouth 42 is disposed on the lower side of the casing liner 41. The bowl portion 43 is disposed on the upper side of the casing liner 41. Here, a mixed flow pump that discharges fluid from the impeller 3 in a diagonal direction relative to the rotating shaft 2 is used in the vertical pump 100.

The vertical pump 100 also includes a lift pipe 5, a discharge bend 6, and a prime mover 7. The lift pipe 5 is connected to the upper side of the suction casing 4 and has the rotating shaft 2 inserted therethrough, causing the fluid to flow vertically upward. The discharge bend 6 is connected to the upper side of the lift pipe 5 and changes the flow of the fluid sent from the lift pipe 5 to a horizontal direction. The prime mover 7 is connected to the upper end of the rotating shaft 2 that protrudes above the discharge bend 6, and is a motor or the like that rotates and drives the rotating shaft 2.

A drain pipe 8 is connected to the end of the discharge bend 6 opposite the lift pipe 5. The vertical pump 100 is inserted into the mounting hole 10 from the suction end side, and the flange 9 on the discharge bend 6 is supported on the pump mounting floor 11, and is installed in the waterway 1.

When the impeller 3 is rotated via the rotating shaft 2 by the drive of the prime mover 7, the water flowing in from the bell mouth 42 is pressurized and passes through the suction casing 4, and is discharged into the discharge channel (not shown) via the lift pipe 5, discharge bend 6, and drain pipe 8.

The vertical shaft pump 100 of this embodiment is equipped with a vortex prevention device 20 that suppresses the generation of air suction vortexes that reach the vicinity of the bellmouth from the water surface.

Figure 2 is an enlarged side view showing the periphery of the vortex prevention device 20 according to this embodiment. Figure 3 is a cross-sectional view taken along line III-III in Figure 2. Figure 4 is a view of the periphery of the vortex prevention device 20 according to this embodiment from the downstream side, i.e., from A in Figure 2. Figure 5 is an enlarged perspective view showing the periphery of the vortex prevention device 20 according to this embodiment. Note that the internal structure of the suction casing 4 and the lift pipe 5 has been omitted in Figure 3.

As shown in Figures 2 to 4, the vortex prevention devices 20 are arranged facing the suction casing 4 on the left and right sides (see Figure 3) downstream of the suction casing 4 in the main flow direction 17 of the fluid in the waterway 1 in which the suction casing 4 is installed. The vortex prevention devices 20 are arranged radially outward of the suction casing 4 and spaced apart from the suction casing 4.

The vortex suppression device 20 has a first vortex suppression plate 21 and a second vortex suppression plate 22. The second vortex suppression plate 22 is disposed downstream of the first vortex suppression plate 21 in the main flow direction 17. The first vortex suppression plate 21 is disposed farther away from the central axis CL of the suction casing 4 than the second vortex suppression plate 22. The first vortex suppression plate 21 and the second vortex suppression plate 22 are plates whose lengths in the up-down direction are the same.

As shown in FIG. 5, the first vortex suppression plate 21 is attached to the suction casing 4 or the lift pipe 5 via support plates 31, 31 whose base ends are fixed to the inner surface of the first vortex suppression plate 21. The second vortex suppression plate 22 is attached to the suction casing 4 or the lift pipe 5 via support plates 32, 32 whose base ends are fixed to the inner surface of the second vortex suppression plate 22. Here, the tips of the upper support plates 31, 32 are fixed by welding or the like to a flange 51 provided at the lower end of the lift pipe 5. The tips of the lower support plates 31, 32 are fixed by welding or the like to a flange 44 provided at the lower end of the bowl portion 43.

The fixing points of the tips of the support plates 31, 32 may be at any point on the suction casing 4 or the lift pipe 5, and can be changed as appropriate. The width and thickness dimensions of the first vortex suppression plate 21 and the second vortex suppression plate 22 can be changed as appropriate, and the vertical length dimensions are determined taking into account the maximum and minimum water levels of the water to be sucked in when the vertical pump 100 is in use.

As shown in FIG. 3, the first vortex suppression plate 21 is an arcuate plate having a first radius R1 (see FIG. 3) centered on the central axis CL. The second vortex suppression plate 22 is an arcuate plate having a second radius R2 (see FIG. 3) centered on the central axis CL. Here, the first vortex suppression plate 21 and the second vortex suppression plate 22 are formed of plates of the same thickness. The first radius R1 is indicated by the inner radius, and the second radius R2 is indicated by the outer radius. The first radius R1 is set to be larger than the second radius R2.

The downstream end 23 of the first vortex suppression plate 21 in the main flow direction 17 and the upstream end 24 of the second vortex suppression plate 22 in the main flow direction 17 overlap at a circumferential position centered on the central axis CL. In other words, when viewed from a position on the central axis CL, there is no circumferential gap between the first vortex suppression plate 21 and the second vortex suppression plate 22.

Next, the operation of the vertical pump 100 configured as above will be described.
As shown in Figure 1, when the water level to be suctioned in the waterway 1 exceeds the lower end of the bell mouth 42 (see water level L1 in Figure 1) and the bell mouth 42 is fully submerged, when the vertical pump 100 is started, the rotation of the impeller 3 causes water to be sucked in through the bell mouth 42, increase in pressure, and the water passes through the suction casing 4, the lift pipe 5, the discharge bend 6, and is sent to the drain pipe 8.

If the vertical pump 100 were not equipped with the vortex breaker 20, the flow of the fluid in the water passage 1 near the water surface may separate on the downstream side of the suction casing 4 as it passes through the suction casing 4, causing a swirling flow. In this case, there is a risk of an air-suction vortex occurring that reaches from the water surface to the vicinity of the bellmouth 42 of the suction casing 4.
However, in this embodiment, the flow from the upstream side in the main flow direction 17 of the suction casing 4 flows between the suction casing 4 and the vortex prevention device 20 and flows out from the downstream side. This suppresses the generation of a swirling flow on the downstream side of the suction casing 4, thereby suppressing the occurrence of an air-suction vortex.

6 and 7, further operation of the vortex prevention device 20 will now be described.
Fig. 6 is a plan view showing a schematic flow around a vortex prevention device 35 composed of a single vortex suppression plate 36. Fig. 7 is a plan view showing a schematic flow around a vortex prevention device 20 of this embodiment composed of a first vortex suppression plate 21 and a second vortex suppression plate 22.

As shown in Figure 6, when one vortex suppression plate 36 is used, the flow from the upstream side in the main flow direction 17 of the suction casing 4 is divided into a flow that passes outside the vortex suppression plate 36 and a flow that passes inside the vortex suppression plate 36. If the specifications of the vertical pump are changed when updating it and the flow speed in the suction tank increases, the flow that passes outside the vortex suppression plate 36 may separate at the outer middle part of the vortex suppression plate 36, generating a swirling flow 37 that causes an air suction vortex. Here, the outside refers to the outside in the radial direction centered on the central axis CL, and the inside refers to the inside in the radial direction centered on the central axis CL.

On the other hand, when the vortex prevention device 20 shown in FIG. 7 is used, a radial gap is generated around the central axis CL between the first vortex suppression plate 21 having the large first radius R1 and the second vortex suppression plate 22 having the small second radius R2. Therefore, part of the flow passing inside the first vortex suppression plate 21 passes through the radial gap and outside the second vortex suppression plate 22. This suppresses the generation of a swirling flow (see swirling flow 37 in FIG. 6) in the outer middle part of the vortex prevention device 20, and the occurrence of an air suction vortex can be suppressed.

As described above, the vertical pump 100 according to this embodiment is equipped with vortex suppression devices 20 arranged on the left and right of the downstream side of the suction casing 4, facing the suction casing 4. The vortex suppression devices 20 have a first vortex suppression plate 21 and a second vortex suppression plate 22 arranged downstream of the first vortex suppression plate 21 in the mainstream direction 17. The first vortex suppression plate 21 is installed farther away from the central axis CL of the suction casing 4 than the second vortex suppression plate 22.

In this embodiment, the flow from the upstream side passes between the suction casing 4 and the vortex prevention device 20 and flows out from the downstream side, thereby suppressing the generation of swirling flow downstream of the suction casing 4.
Furthermore, a portion of the flow passing through the inside of the first vortex suppression plate 21 passes through a radial gap centered on the central axis CL and outside the second vortex suppression plate 22, thereby suppressing the generation of swirling flow in the outer middle part of the vortex prevention device 20.
Therefore, according to this embodiment, it is possible to provide the vertical pump 100 that can further suppress the occurrence of air-suction vortexes.

In this embodiment, the vortex suppression device 20 is divided into two plates, a first vortex suppression plate 21 and a second vortex suppression plate 22, in the main flow direction 17, but this is not limited to this and may be divided into three or more plates.

In addition, in this embodiment, the first vortex suppression plate 21 is an arc-shaped plate having a first radius R1 centered on the central axis CL, and the second vortex suppression plate 22 is an arc-shaped plate having a second radius R2 centered on the central axis CL. The first radius R1 is set to be larger than the second radius R2. In this configuration, the flow around the vortex prevention device 20 becomes smoother, including the flow passing through the inside of the first vortex suppression plate 21 and the outside of the second vortex suppression plate 22.

In addition, in this embodiment, the downstream end 23 of the first vortex suppression plate 21 and the upstream end 24 of the second vortex suppression plate 22 overlap at a circumferential position centered on the central axis CL. In this configuration, there is no circumferential gap between the first vortex suppression plate 21 and the second vortex suppression plate 22. As a result, a portion of the flow passing inside the first vortex suppression plate 21 can be more reliably made to pass outside the second vortex suppression plate 22, and the generation of a swirling flow in the outer middle part of the vortex prevention device 20 is more suppressed.

Second Embodiment
Next, a second embodiment of the present invention will be described with reference to FIG. 8, focusing on differences from the vertical shaft pump 100 of the first embodiment described above, and a description of commonalities will be omitted as appropriate.
FIG. 8 is a view of the periphery of a vortex prevention device 20a according to the second embodiment, viewed from the downstream side.

As shown in FIG. 8, the second embodiment differs from the first embodiment in that the vortex suppression device 20a has a plurality of through holes 25. In FIG. 8, the first vortex suppression plate 21a and the second vortex suppression plate 22a each have a plurality of through holes 25.

In addition, only one of the first vortex suppression plate 21a and the second vortex suppression plate 22a may have multiple through holes 25. In addition, in the second embodiment, the shape of the through holes 25 is circular, but this is not limited to this, and they may be, for example, oval, elliptical, rectangular, slit-shaped (including vertically and horizontally long), etc.

According to the second embodiment, a portion of the flow passing through the inside of the vortex prevention device 20a can pass through the through hole 25 to the outside of the vortex prevention device 20a. This further suppresses the generation of swirling flow. In addition, the weight of the vortex prevention device 20a is reduced, making it easier to attach the vortex prevention device 20a to the vertical pump 100.

Third Embodiment
Next, a third embodiment of the present invention will be described with reference to FIG. 9, focusing on differences from the vertical shaft pump 100 of the first embodiment described above, and a description of commonalities will be omitted as appropriate.
FIG. 9 is a view of the periphery of a vortex prevention device 20b according to the third embodiment, viewed from the downstream side.

As shown in FIG. 9, the third embodiment differs from the first embodiment in that the vortex suppression device 20b is divided in the vertical direction. In FIG. 9, the first vortex suppression plate 21b and the second vortex suppression plate 22b are each divided in the vertical direction.

In addition, only one of the first vortex suppression plate 21a and the second vortex suppression plate 22a may be divided in the vertical direction. In addition, in the third embodiment, the vortex prevention device 20b is divided into two in the vertical direction, but this is not limited to this, and it may be divided into three or more.

According to the third embodiment, the vortex prevention device 20b is divided in the vertical direction, and as a result, each component is lighter in weight, which avoids the difficulty of machining due to the large size of the components, and also makes it easier to attach the vortex prevention device 20b to the vertical pump 100.

Although the present invention has been described above based on the embodiments, the present invention is not limited to the above-mentioned embodiments and includes various modified examples. For example, the above-mentioned embodiments have been described in detail to clearly explain the present invention, and are not necessarily limited to those having all of the configurations described. In addition, it is possible to replace part of the configuration of one embodiment with the configuration of another embodiment, and it is also possible to add the configuration of another embodiment to the configuration of one embodiment. In addition, it is possible to add, delete, or replace part of the configuration of each embodiment with other configurations.

The vortex prevention devices 20, 20a, 20b described above may be combined as appropriate. For example, the vortex prevention device 20b of the third embodiment may have a plurality of through holes 25.
In addition, the first vortex suppression plates 21, 21a, 21b and the second vortex suppression plates 22, 22a, 22b are arcuate plates, but are not limited to this and may be any curved plate such as an elliptical plate, or a flat plate.
In the above embodiment, the vertical pump of the present invention is described as being applied to a mixed flow pump in which the flow discharged from the impeller 3 is within a conical surface whose axis is the rotating shaft 2. However, the present invention is not limited to this, and the vertical pump of the present invention can also be applied to an axial flow pump in which the flow discharged from the impeller 3 is within a cylindrical surface concentric with the rotating shaft 2.

1 Waterway (suction tank)
Reference Signs List 3 Impeller 4 Suction casing 17 Main flow direction 20, 20a, 20b Vortex prevention device 21, 21a, 21b First vortex suppression plate 22, 22a, 22b Second vortex suppression plate 23 End portion 24 End portion 25 Through hole 100 Vertical pump R1 First radius R2 Second radius CL Central axis

Claims (3)

A suction casing that houses the impeller therein;
and a vortex prevention device disposed on the left and right sides of the downstream side of the suction casing in the mainstream direction of the fluid in the suction tank in which the suction casing is installed, facing the suction casing, for suppressing the generation of an air suction vortex;
The vortex prevention device includes a first vortex suppression plate and a second vortex suppression plate disposed downstream of the first vortex suppression plate in the main flow direction,
The first vortex suppression plate is disposed farther away from a central axis of the suction casing than the second vortex suppression plate ,
the first vortex suppression plate is an arc-shaped plate having a first radius centered on the central axis, and the second vortex suppression plate is an arc-shaped plate having a second radius centered on the central axis,
the first radius is greater than the second radius;
a downstream end of the first vortex suppression plate in the mainstream direction and an upstream end of the second vortex suppression plate in the mainstream direction overlap with each other in a circumferential direction about the central axis, and a portion of the first vortex suppression plate other than the downstream end and a portion of the second vortex suppression plate other than the upstream end do not overlap with each other,
A flow passage is provided on the downstream side of the second vortex suppression plate in the main flow direction.
A vertical pump characterized by the above. The vertical pump according to claim 1, characterized in that the vortex prevention device has a plurality of through holes. The vertical pump according to claim 1, characterized in that the vortex prevention device is divided in the vertical direction.

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