JP5318240B2 - Suction tank - Google Patents

Description

  The present invention relates to a suction water tank provided in a drainage facility such as a pump station or a pump gate.

  The suction water tank is a water channel for guiding water to the pump. In this suction water tank, the allowable flow velocity at the shape of the water tank and the stagnation mouth (portion that moves from the open water channel to the closed water channel) is obtained by various model experiments and the like, and is defined by various standards. For example, in a water tank (referred to as a semi-closed water tank) having an inclined surface 12 at a stagnation mouth 11 as shown in FIG. 16 and having both an open channel and a closed water channel, the flow velocity at the stagnation port 11 is about 0.6 m / s. It has been established. This flow rate is a semi-closed water tank that does not generate air suction vortices that are harmful to the pump. In many drainage stations, the shape of the water tank and the water channel is determined based on this flow speed. However, in recent years, there has been a further demand for reduction in construction costs, and a further reduction in the size of the suction water tank is required, and there is a strong demand for a suction water tank that does not generate harmful vortices even at high flow rates. Yes.

  When the flow velocity at the stagnation port 11 is made faster than before and the suction water tank is made smaller, air suction vortices and bubbles entrained from the water surface become a problem. If an air suction vortex is generated and interferes with the impeller of the pump, vibration and noise are generated. In the worst case, the pump cannot be drained and there is a risk of inundation damage. When the flow rate is further increased in the conventional semi-closed water tank, as shown in FIG. 17, the tip of the hollow vortex generated in the vicinity of the stagnation mouth 11 is broken, and bubbles begin to be sucked into the pump P. When the vortex grows, it finally enters the pump P as a continuous vortex and the above phenomenon occurs.

  As shown in FIG. 17, in the open channel, the flow rate of the upper layer portion having a shallow depth is high. When the flow velocity is further increased, the incident wave and the reflected wave collide in the vicinity of the stagnation mouth 11 to cause a wave. Waves entrain air and generate many bubbles. The bubbles are entrained in the downward flow by the inclined surface 12, and the bubbles are sucked into the pump P and affect the pump P. In particular, as shown in FIG. 17, since the flow velocity on both sides is slowed by frictional resistance with the channel wall surface, a water flow having a swirl component is generated near both ends of the inclined surface 12, and when this grows, a hollow vortex is generated. It becomes easy to do. Furthermore, the bubble caused by the above-described wave also flows into the pump P along this vortex flow. That is, in the semi-closed water tank having the inclined surface 12, it can be said that both side portions of the inclined surface 12 are the portions where the air suction vortex and the bubble entrapment are most likely to occur.

  Further, in the open water tank shown in FIG. 18, when the flow velocity is increased, there is a problem that vortices are likely to be generated at both ends of the vortex prevention wall 20 due to the difference in flow velocity between the central portion and both side portions. Further, as shown in FIG. 19, also in the suction water tank in the pump gate in which the pumps P1 and P2 are attached to the gate 30, a water flow having a rotational component is generated between the side wall 25 of the suction water tank and the pumps P1 and P2. Cheap. Therefore, it can be said that both sides of the gate 30 are positions where air suction vortices and bubble entrainment are likely to occur.

Japanese Patent Laid-Open No. 2001-317496

  The present invention has been made in view of such a conventional problem, and even when the flow rate of the suction water tank including the semi-closed water tank of the drainage station and the suction water tank at the pump gate is increased, the pump is used. It is an object of the present invention to provide a suction water tank that can prevent harmful vortices and bubbles from being involved, or that does not guide vortices and bubbles to a pump.

In order to achieve the above-described object, one aspect of the present invention is a suction water tank configured as an open channel for guiding water to a pump, which is disposed on the upstream side of the pump, and one of the suction water tanks has a vortex prevention structure extending to the other side from the side, and both ends disposed are flow path forming member of the vortex prevention structure, the vortex prevention structure has a front face facing the flow of water In addition, the lower end of the vortex prevention structure is positioned below the lowest operating water level, and the flow path forming member has an inclined surface that is inclined from the side surface of the suction water tank toward the front surface of the vortex prevention structure. Features.

In a preferred aspect of the present invention, the vortex prevention structure has a substantially quadrangular vertical cross section parallel to the flow.
In a preferred aspect of the present invention, the connection length between the flow path forming member and the vortex prevention structure is 0.2D or more when the width D of the open channel is less than 1000 mm, and the width D of the open channel. When it is 1000 mm or more, it is 600 mm or less.
In a preferred aspect of the present invention, the inclined surface has a lower portion positioned below a minimum operating water level.
One reference example of the present invention is characterized in that the inclined surface is a smooth curved surface.
In a preferred aspect of the present invention, an angle of the inclined surface from a side surface of the suction water tank is 30 to 45 °.
In a preferred aspect of the present invention, the upper portion of the inclined surface is located above the maximum water level of the suction water tank.

Another reference example of the present invention is a suction water tank for guiding water to a pump, and has a vortex prevention structure disposed on the upstream side of the pump, and the vortex prevention structure faces the flow of water. The surface to be inclined is inclined upward toward the downstream.

Other reference examples of the present invention include a gate disposed in a suction water tank, a pump installed in the gate, for transferring water from an upstream region of the gate to a downstream region, and installed on an upstream side of the gate. A pump gate comprising at least one vortex preventing member.
In another reference example of the present invention, the vortex prevention member includes a flow path forming member having a front surface facing the flow of water, and a support member that supports the flow path formation member, and a plurality of the vortex prevention members Are attached to both ends of the gate.

  According to the present invention, since it is possible to form a liquid surface state in which a swirl flow is difficult to occur, it is possible to prevent the generation of a hollow vortex and an air suction vortex. Further, by preventing the generation of the hollow vortex, it is possible to prevent the bubbles generated by the waves from being entrained and entering the pump.

It is sectional drawing which shows the suction water tank in the 1st Embodiment of this invention. It is a top view when the suction water tank shown in FIG. 1 is seen from the top. It is a figure which shows the other structural example of a vortex prevention structure. It is sectional drawing which shows the suction water tank in the 2nd Embodiment of this invention. It is a top view when the suction water tank shown in FIG. 4 is seen from the top. It is sectional drawing which shows the suction water tank in the 3rd Embodiment of this invention. It is a top view when the suction water tank shown in FIG. 6 is seen from the top. It is a figure which shows the other structural example of the 3rd Embodiment of this invention. It is sectional drawing which shows the suction water tank which concerns on the 4th Embodiment of this invention. It is a top view which shows the suction water tank shown in FIG. It is the figure which looked at the suction water tank shown in FIG. 9 from the bottom. It is sectional drawing which shows the suction water tank of the pump gate in the 5th Embodiment of this invention. It is a top view when the suction water tank shown in FIG. 12 is seen from the top. It is a figure which shows the other structural example of the supporting member shown in FIG. 15A to 15D are views when another example of the vortex preventing member is viewed from above. It is a figure which shows the conventional suction water tank. It is a figure which shows the conventional suction water tank. It is a figure which shows the conventional suction water tank. It is a figure which shows the conventional suction water tank.

Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 is a cross-sectional view showing a suction water tank according to the first embodiment of the present invention, and FIG. 2 is a plan view when the suction water tank shown in FIG. 1 is viewed from above. In addition, the suction water tank of this embodiment is what is called a semi-closed water tank comprised from an open water channel and a closed water channel.

  As shown in FIGS. 1 and 2, a vertical shaft pump P is disposed at the end of the suction water tank. The vertical shaft pump P includes a casing 1, an impeller 2 accommodated in the casing 1, and a rotating shaft 3 connected to the impeller 2. The rotary shaft 3 is connected to a drive source (not shown). In such a configuration, when the impeller 2 is rotated, water is sucked from the opening at the lower end of the casing 1 and discharged to the outside of the suction water tank through the casing 1 and a discharge pipe (not shown). Water (for example, water from a river) flows in the direction of the arrow toward the pump P in the suction water tank as the pump P is operated. In addition, the code | symbol 11 has shown the stagnation mouth which transfers from an open channel to a closed channel.

  A vortex prevention structure 15 is disposed in the water channel upstream of the pump P. The vortex prevention structure 15 includes an upper surface 15a that is inclined upward toward the downstream side, a lower surface 15b that is connected at a lower end of the upper surface 15a and is inclined upward toward the substantially horizontal or upstream side, and an upper end and a lower surface of the upper surface 15a. It is basically composed of a surface 15c that connects 15b. In the example shown in FIG. 1, the upper surface 15a and the lower surface 15b are connected to each other at an acute angle. However, as shown in FIG. 3, the connection portion between the upper surface 15a and the lower surface 15b is a curved surface in order to prevent flow separation. It may be configured.

  FIG. 1 shows an example in which the vortex prevention structure 15 has a triangular cross-sectional shape. The feature of the vortex prevention structure 15 is that the upper surface 15a and the lower surface 15b are formed in the water channel, and the cross-sectional shape may be in accordance with the type of pump to be installed. The pump P may be a horizontal shaft pump or a submersible pump, or a tubular pump communicating with a water channel formed by the lower surface 15b. The vortex prevention structure 15 may be formed of concrete in conjunction with the construction of a water channel, or may be formed of steel in a suction tank that has already been completed.

  In the conventional suction water tank shown in FIG. 17, the flow of the liquid surface collides with the inclined surface 12 facing the water flow, and bubbles and air suction vortices (recessed vortices, intermittent vortices) are generated (hereinafter, this portion is entrained part S). The generated bubbles and air suction vortices (recessed vortices, intermittent vortices) were entrained by the downward water flow and led to the pump. According to the present embodiment, the flow on the liquid surface and the flow on the bottom surface are separated by the vortex prevention structure 15, and the flow velocity on the surface layer is slowed by the upper surface 15 a of the vortex prevention structure 15. Thereby, generation | occurrence | production of an air suction vortex can be suppressed in the entrainment part S, and it is prevented that a bubble and a vortex are taken to the pump P by changing the direction of a downward flow. In particular, even if bubbles are generated, the ascending speed is approximately 0.3 m / s, so that the air bubbles are faster than the descending flow and are not entrained and float on the water surface and do not reach the pump P.

  FIG. 4 is a cross-sectional view showing a suction water tank according to the second embodiment of the present invention, and FIG. 5 is a plan view when the suction water tank shown in FIG. 4 is viewed from above. Note that the configuration of the present embodiment that is not particularly described is the same as the configuration of the first embodiment described above, and thus redundant description thereof is omitted.

  As shown in FIGS. 4 and 5, the vortex prevention structure 15 further includes a horizontal surface 15d extending substantially horizontally from the upper surface 15a toward the upstream side, and a connection surface 15e connecting the horizontal surface 15d and the lower surface 15b. ing. The horizontal surface 15d and the connection surface 15e are located below the lowest operating water level of the pump P. Here, the minimum operating water level is the lowest water level at which the pump P can be operated.

  FIG. 6 is a cross-sectional view showing a suction water tank according to the third embodiment of the present invention, and FIG. 7 is a plan view of the suction water tank shown in FIG. The suction water tank of this embodiment is an open water tank comprised only from an open water channel.

  As shown in FIG. 6, a vertical shaft pump P is installed at the end of the suction water tank. Similarly to the above-described embodiment, by rotating the impeller 2, water is sucked from the opening at the lower end of the casing 1, and water is discharged through the casing 1 and a discharge pipe (not shown). Water (for example, water from a river) flows in the direction of the arrow toward the pump P in the suction water tank as the pump P is operated. 6 shows an example of a vertical shaft pump, a horizontal shaft pump or a submersible pump may be used.

As shown in FIG. 7, on the upstream side of the pump P, a vortex prevention wall (vortex prevention structure) 20 extending from one side surface 25 of the suction water tank to the other side surface 25 is disposed. In addition, flow path forming members 21 are disposed at both ends of the vortex prevention wall 20. The vortex prevention wall 20 has a surface (front surface) 20a facing the water flowing through the suction water tank, and the flow path forming member 21 is an inclined surface 21a inclined from the side surface 25 of the suction water tank toward the surface 20a of the vortex prevention wall 20. have. The lower end of the vortex prevention wall 20 is located below the minimum operating water level L _L.

  FIG. 8 is a diagram illustrating another configuration example of the present embodiment. In this example, a steel liner 22 is used as the flow path forming member. The liner 22 is fixed to the vortex prevention wall 20 and the side surface (side wall) 25 of the suction water tank by an anchor 23. The liner 22 is curved, whereby the inclined surface 22a connecting the vertical surface 20a of the vortex prevention wall 20 and the side surface 25 of the suction water tank is a smooth curved surface. According to such a configuration, water flowing in the vicinity of the side surface 25 can be smoothly guided to the central portion of the suction water tank. Furthermore, according to this example, the liner 22 can be easily attached to the existing vortex prevention wall 20, so that the discharge amount of the pump can be increased without changing the structure of the existing pump station. Note that a flat plate material made of steel may be used as the liner 22.

  In addition, although the suction water tank of this embodiment is what is called an open water tank, it is applicable also to the semi-closed water tank which has an inclined surface in a stagnation mouth. In the first to third embodiments, an example in which a vertical shaft pump is used is shown. However, the present invention is not limited to this, and other types of pumps such as a horizontal shaft type and a submersible type are used. It can also be applied to a suction tank.

  In the conventional open water tank and semi-closed water tank, the frictional resistance of both side walls influences, and the flow velocity at the side wall becomes slower than the central part of the water tank. For this reason, as shown in FIGS. 17 and 18, swirl flows are likely to occur on both side walls, and if the flow velocity is increased, harmful vortices are likely to be generated on the side walls. As a measure for preventing the generation of this swirling flow, Patent Document 1 proposes a technique of installing plates and rods at both ends of the water tank. However, in the pump station where drainage is performed, there is a problem that dust or the like flows and gets tangled or wound around a plate or a bar.

  According to the fourth embodiment described below, there is no entanglement of dust and the generation of vortices can be prevented. FIG. 9 is a cross-sectional view showing a suction water tank according to the fourth embodiment of the present invention, FIG. 10 is a plan view showing the suction water tank shown in FIG. 9, and FIG. 11 shows the suction water tank shown in FIG. FIG. Note that the configuration of the present embodiment that is not particularly described is the same as that of the third embodiment described above, and thus redundant description thereof is omitted.

  As shown in FIGS. 9 to 11, the vortex prevention wall (vortex prevention structure) 27 of the present embodiment has a front surface 27a facing the flow of water, and a flow path forming member at both ends of the front surface 27a. 28 is arranged. The front surface 27a is inclined downward toward the downstream, and therefore the flow path forming member 28 is also inclined downward toward the downstream. Each flow path forming member 28 has a triangular cross-sectional shape and has an inclined surface 28a. The inclined surface 28 a is inclined from the side surface 25 of the suction water tank to the front surface 27 a of the vortex prevention wall 27.

The inclined surface 21a of the flow path forming member 21 functions as a flow path forming surface, and the water flowing in the vicinity of the side surface 25 of the suction water tank is guided to the central part of the suction water tank by changing its direction by the inclined surface 21a. Such a flow of water can prevent a swirling flow as shown in FIG. Therefore, even when the speed of the water flowing through the suction water tank is increased, the generation of the air suction vortex in the vicinity of both side surfaces 25 can be prevented. The flow path forming member 21 may be formed of concrete according to the construction of the water channel, or may be formed of steel in an already completed water tank or the like. When the width D of the suction water tank is less than 1000 mm, the distance L between the inner end of the inclined surface 21a and the side surface 25 is preferably 0.2D or more, and when the width D is 1000 mm or more, the distance L is 600 mm or less. Preferably there is. The upper inclined surface 21a is more than the maximum water level L _H, it is preferred that lower portion located below the minimum operating level L _L. Furthermore, the angle θ from the side surface 25 of the inclined surface 21a is preferably 30 to 45 °.

  FIG. 12 is a cross-sectional view showing a suction water tank of a pump gate in the fifth embodiment of the present invention, and FIG. 13 is a plan view when the suction water tank shown in FIG. 12 is viewed from above. The suction water tank of this embodiment is an open water tank comprised only from an open water channel.

  As shown in FIGS. 12 and 13, a gate (door gate) 30 is disposed in the suction water tank, and two horizontal shaft pumps P <b> 1 and P <b> 2 are installed in parallel in the gate 30. The suction ports of these pumps P1 and P2 are located on the upstream side of the gate 30. The gate 30 is provided with a discharge flow path 31 corresponding to the two pumps P1 and P2. Each pump P <b> 1, P <b> 2 has a casing 1 having a suction port, an impeller 2 accommodated in the casing 1, and a drive device (motor) 32 that rotates the impeller 2. When the impeller 2 is rotated by the driving device 32, the water in the suction water tank is sucked from the suction port, and the water is transferred to the downstream region of the gate 30 through the discharge channel 31. A reverse flow prevention valve 33 for preventing the reverse flow of water is provided at the discharge port of the discharge flow path 31.

  Swirl prevention members 35 are disposed slightly above the pumps P1 and P2 and on both sides of the pumps P1 and P2. In the present embodiment, since the two pumps P1 and P2 are arranged, a total of three vortex preventing members 35 are arranged. More specifically, as shown in FIG. 13, these three vortex prevention members 35 are provided between the suction water tank side face 25 and the pump P1, between the pump P1 and the pump P2, and between the pump P2 and the suction water tank side face 25. Between each other. The number of pumps is not limited to two, and may be one or three or more. In this case, it goes without saying that the number of vortex preventing members 35 also changes according to the number of pumps.

  Each vortex prevention member 35 includes a front hanging plate (flow path forming member) 36 having a front surface facing the flow of water flowing through the suction water tank, and a support member 37 that supports the front hanging plate 36. The support member 37 is fixed to the gate 30 or the pump P, and the lower end of the front hanging plate 36 of the vortex preventing member 35 is located below the lowest water level at which the pumps P1 and P2 can operate as shown in FIG. As a support member, a horizontal plate 38 may be used as shown in FIG.

  According to such a configuration, since the distance D2 between the suction ports of the pumps P1 and P2 and the water collision surface (front surface of the front hanging plate 36) is shortened, the water flowing through the suction water tank can be quickly formed without forming a swirling flow. Are sucked into the suction ports of the pumps P1 and P2. Therefore, generation | occurrence | production of the air suction vortex in the edge part of a suction water tank can be prevented.

  FIG. 15A to FIG. 15D are views when another example of the vortex preventing member of this embodiment is viewed from above. As shown in FIGS. 15 (a) to 15 (d), the front drooping plate 36 of the vortex prevention member 35 may be inclined according to the installation position of the pumps P1 and P2 and the shape of the suction water tank (for example, a curved shape). Further, a curved portion 39 may be provided on the side portion of the front hanging plate 36. Moreover, it becomes possible to respond | correspond to various water channel shapes by setting it as the structure (for example, attachment structure by a volt | bolt, or hinge structure) which can adjust the angle of a front drooping plate.

  Although the embodiments of the present invention have been described so far, it is needless to say that the present invention is not limited to the above-described embodiments and may be implemented in various forms within the scope of the technical idea.

DESCRIPTION OF SYMBOLS 1 Casing 2 Impeller 3 Rotating shaft 11 Stagnation mouth 15 Vortex prevention structure 16 Recess 20 Vortex prevention wall 21 Flow path formation member 22 Liner 23 Anchor 25 Side surface of suction water tank (side wall)
27 Vortex prevention wall (vortex prevention structure)
28 Flow path forming member 30 Gate 31 Discharge flow path 32 Drive machine (motor)
33 Backflow prevention valve 35 Vortex prevention member 36 Front drooping plate (flow path forming member)
37 support member 38 horizontal plate 39 curved part P, P1, P2 pump S entrainment part

Claims (6)

A suction water tank configured as an open channel for guiding water to the pump,
A vortex prevention structure that is disposed upstream of the pump and extends from one side surface of the suction water tank to the other side surface;
A flow path forming member disposed at both ends of the vortex prevention structure,
The vortex prevention structure has a front surface facing the flow of water, and the lower end of the vortex prevention structure is located below a minimum operating water level,
The suction water tank, wherein the flow path forming member has an inclined surface that is inclined from a side surface of the suction water tank toward a front surface of the vortex prevention structure. The suction water tank according to claim 1, wherein the vortex prevention structure has a substantially rectangular vertical cross section parallel to the flow. The connection length between the flow path forming member and the vortex prevention structure is 0.2 D or more when the width D of the open channel is less than 1000 mm, and 600 mm when the width D of the open channel is 1000 mm or more. The suction water tank according to claim 1, wherein: The suction water tank according to claim 1, wherein a lower portion of the inclined surface is positioned below a minimum operating water level.   The suction water tank according to claim 1, wherein an angle of the inclined surface from a side surface of the suction water tank is 30 to 45 °. The suction water tank according to claim 1, wherein an upper portion of the inclined surface is located at or above a maximum water level of the suction water tank.

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