WO2019171774A1

WO2019171774A1 - Vertical shaft pump

Info

Publication number: WO2019171774A1
Application number: PCT/JP2019/001233
Authority: WO
Inventors: 祐治兼森
Original assignee: 株式会社酉島製作所
Priority date: 2018-03-08
Filing date: 2019-01-17
Publication date: 2019-09-12
Also published as: JP7094357B2; JPWO2019171774A1

Abstract

A vertical shaft pump 10 is provided with: a pump casing 12 disposed in a water intake tank 1; an impeller 25 disposed so as to be located at a water discharge start water level LWL; swirl prevention piping 30 which suppresses the generation of an air intake swirl Sv; and air supply piping 38 for supplying air into the pump casing 12. The swirl prevention piping 30 is provided with: an annular horizontal pipe 32 which surrounds the pump casing 12; and a first vertical pipe 35A, the lower end of which is connected to the horizontal pipe 32 and the upper end of which is closed. The air supply piping 38 is provided with: a first air intake pipe 40, one end of which is disposed at the water discharge start water level LWL in the water intake tank 1, and the other end of which is disposed within the first vertical pipe 35A; and an air supply pipe 50, one end of which is connected to the horizontal pipe 32, and the other end of which is connected to the pump casing 12 at a position below the impeller 25.

Description

Vertical shaft pump

The present invention relates to a vertical shaft pump.

A vertical shaft pump is known that includes a pump casing disposed in the water absorption tank so as to extend in the vertical direction and an impeller disposed rotatably in the pump casing.

Patent Document 1 discloses a stand-by type vertical shaft pump in which two types of intake pipes having different intake port positions are arranged and can be operated in advance before water flows into the water absorption tank. However, this pump cannot suppress the generation of an air suction vortex in which the water flow from the water surface toward the suction port includes air in the water absorption tank.

Patent Document 2 discloses a vertical shaft pump in which an annular horizontal pipe and a vertical pipe extending in the vertical direction are arranged outside the pump casing to suppress the generation of air suction vortices on the water surface of the water absorption tank. Has been. However, with this pump, the operation cannot be started before the water flows into the water absorption tank (preceding standby).

JP 2009-203806 A JP 2013-217217 A

An object of the present invention is to provide a vertical shaft pump that has both functions of suppressing the generation of air suction vortex and waiting in advance, and can effectively achieve drainage at a lower water level.

One aspect of the present invention includes a pump casing disposed in the water absorption tank so as to extend in the vertical direction, and an impeller disposed rotatably in the pump casing so as to be positioned at a drainage start water level of the water absorption tank. A vortex prevention pipe for suppressing the occurrence of air suction vortex in the water absorption tank, and when the water level in the water absorption tank becomes lower than the drainage start water level, the air in the water absorption tank is put into the pump casing. The vortex prevention pipe is disposed so as to extend in the vertical direction outside the pump casing and an annular horizontal pipe that surrounds a lower side of the drainage start water level of the pump casing. A first vertical pipe having a lower end connected to the horizontal pipe and a closed upper end, and the air supply pipe has one end disposed at the drainage start water level in the water absorption tank and the other end 1st vertical A vertical shaft pump comprising: a first intake pipe disposed in a pipe; and an air supply pipe having one end connected to the horizontal pipe and the other end connected to the lower side of the impeller of the pump casing. To do.

The drainage start water level is determined as a required specification based on the water level of a nearby river or sea and the surrounding building conditions. This vertical shaft pump is equipped with an air-water mixing operation that drains water while taking in air in the water absorption tank, a drainage operation that drains only water (total water), and a water column in the pump casing without drainage. Switch to air lock (drainage cut-off) operation with In addition, when the operator starts, the operation is in the air without holding the water column or draining.

In the air-water mixing operation, the first intake pipe sucks air, so that the amount of water absorbed from the suction port is reduced, but the flow speed of the water surface in the water absorption tank is slowed down, so that the water level that can be drained can be lowered. However, as the water level becomes lower than the drainage start water level, the water surface eventually reaches a flow velocity at which an air suction vortex is generated. The generation of the air suction vortex can be suppressed by a vortex prevention pipe arranged outside the pump casing. Therefore, drainage at a lower water level can be effectively realized without deepening the water absorption tank than a pump without a vortex prevention pipe or an air supply pipe. In addition, the first intake pipe and the air supply pipe constituting the air supply pipe are connected to the first vertical pipe and the horizontal pipe constituting the vortex prevention pipe, and these are also used as the air supply flow path. Therefore, despite having both functions of suppressing vortex generation and advance standby, a simple configuration can be realized as a whole pump.

Since the vertical shaft pump of the present invention includes the vortex prevention pipe and the air supply pipe, drainage at a lower water level can be effectively realized than a pump without one of them. Moreover, since the air supply piping also uses the pipes that make up the vortex prevention piping as the air supply flow path, the pump as a whole has a simple configuration despite having both the functions of suppressing vortex generation and waiting in advance. realizable.

Sectional drawing which shows the vertical shaft pump which concerns on embodiment of this invention. Sectional drawing which shows the air lock state of a vertical shaft pump. Sectional drawing which expanded a part of FIG. The principal part plane sectional view of FIG. Sectional drawing which expanded a part of FIG.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 shows a vertical shaft pump 10 (hereinafter referred to as “pump”) according to an embodiment of the present invention. The pump 10 drains the water that has flowed into the water absorption tank 1 to the downstream side. The pump 10 of this embodiment includes a vortex prevention pipe 30 and an air supply pipe 38 outside the pump casing 12, and depending on the water level of the water absorption tank 1, drainage (total water) operation, air-water mixing operation, and airlock (drainage). This is a stand-by standby type that switches to shut-off operation.

(Outline of vertical shaft pump)
As shown in FIG. 1, the pump 10 includes a pump casing 12, a rotating shaft 22, and an impeller 25.

The pump casing 12 is fixed to the installation floor 2 covering the upper part of the water absorption tank 1 so as to extend in the vertical direction in the water absorption tank 1. The pump casing 12 includes a pumping pipe 13 disposed in the water absorption tank 1 and a discharge pipe 19 disposed on the installation floor 2. The pumping pipe 13 includes a straight pipe 14, a vane casing 15, and a bell mouth 17, and is connected in this order from the upper side to the lower side. The discharge pipe 19 includes a discharge elbow 20 having a central axis curved by 90 degrees, and is connected to the upper end of the straight pipe 14. A water supply pipe (not shown) for draining to the downstream side is connected to the outlet of the discharge elbow 20.

The rotary shaft 22 passes through the discharge elbow 20 and is disposed along the axis of the pumping pipe 13. The rotary shaft 22 is rotatably supported by an underwater bearing (sliding part) 23 disposed in the straight pipe 14 and the bearing casing 16 in the vane casing 15. The upper end of the rotating shaft 22 protrudes outward from the discharge elbow 20, and the penetrating portion is sealed watertight by a shaft seal device.

The impeller 25 is disposed below the bearing casing 16 and is fixed to the lower end of the rotary shaft 22. The upper end 26 of the impeller 25 is disposed at the same height as the drainage start water level LWL. The drainage start water level LWL will be described in detail later.

A driving means (not shown) is connected to the upper end of the rotating shaft 22 protruding from the pump casing 12. As the drive means, an electric motor or a diesel engine which is one of internal combustion engines is used. When the driving means is driven, the impeller 25 is rotated integrally with the rotary shaft 22, so that the water in the water absorption tank 1 is discharged downstream through the pump casing 12.

2, when the water level in the water absorption tank 1 is lowered to the vortex generation water level VWL by drainage, a water flow (air suction vortex Sv) from the water surface toward the suction port 18 of the pump casing 12 is generated. The air suction vortex Sv is generated when the flow velocity of the water surface in the water absorption tank 1 reaches a certain level, and the cross-sectional area of the water absorption tank 1 affects the flow velocity. Therefore, the vortex generation water level VWL varies depending on the cross-sectional shape of each water absorption tank 1. Since the air in the water absorption tank 1 is continuously or intermittently sucked into the water flow of the air suction vortex Sv, vibrations that cause deterioration of the installation floor 2 are generated in the pump 10.

The vortex prevention pipe 30 is provided to suppress the generation of the air suction vortex Sv. The vortex prevention pipe 30 includes an annular horizontal pipe 32 that surrounds the lower side of the drainage start water level LWL of the pump casing 12, and a straight tubular vertical pipe 35 that is disposed so as to extend in the vertical direction outside the pump casing 12. Prepare. The inner diameter of the horizontal pipe 32 is larger than the outer diameter of the pump casing 12 (the upper part of the bell mouth 17), and a predetermined gap (flow path) is secured between them. The vertical pipe 35 is disposed at a position where the air suction vortex Sv is assumed by actual measurement or calculation. Generation of the air suction vortex Sv can be effectively suppressed by the water flow from the water surface toward the suction port 18 interfering with the vertical pipe 35.

On the other hand, when water suddenly flows into the water absorption tank 1 due to heavy rain or the like, if the drainage (starting of the pump 10) is delayed, the water may overflow from the water absorption tank 1. This problem can be solved by continuing the operation of the pump 10 even when there is no water in the water absorption tank 1, but in this case, there is a problem that the underwater bearing 23 is overheated and seizes on the rotating shaft 22.

As shown in FIG. 2, the air supply pipe 38 enables an air lock operation in which the water column WC is held in the pump casing 12, thereby preventing the underwater bearing 23 from being overheated and enabling the pump 10 to be continuously operated. Is provided. The air supply pipe 38 includes a first intake pipe 40, a second intake pipe 45, and an air supply pipe 50, and supplies air in the water absorption tank 1 into the pump casing 12 by the suction force of the pump 10. The intake port (one end) 41 of the first intake pipe 40 is disposed at the drainage start water level LWL, and the intake port (one end) 46 of the second intake pipe 45 is disposed at the drainage cutoff water level LLWL. The air supply pipe 50 communicates with the first intake pipe 40 and the second intake pipe 45, and the air supply port 51 (the other end) is connected to the bell mouth 17 so as to be positioned below the impeller 25. It is connected.

The advance standby type pump 10 including the air supply pipe 38 is started by an operator based on information of a local weather observation system, for example. Since the impeller 25 is in the air at the beginning when the water level in the water absorption tank 1 is lower than the lower end of the impeller 25, the pump 10 is operated in the air without draining. When the water level rises above the lower end of the impeller 25, the water in the water absorption tank 1 is sucked up by the impeller 25 and air is taken in through the first intake pipe 40. Therefore, the pump 10 is in a mixed state of water and air. Switch to a steam / water mixing operation. When the water level rises above the drainage start water level LWL (the upper end 26 of the impeller 25), since the intake of air through the first intake pipe 40 is blocked, the pump 10 is switched to a drainage operation that discharges only water.

When drainage causes the water level in the water absorption tank 1 to fall below the drainage start water level LWL, air is again taken in through the first intake pipe 40, so the pump 10 switches to the air-water mixing operation. When the water level falls below the drain cut-off water level LLWL, air is also taken in from the second intake pipe 45, so that the pump 10 switches to an air lock operation that holds the water column WC without draining. Thereafter, when the water level rises above the drainage cutoff water level LLWL, the pump 10 is switched to the air / water mixing operation again. That is, the operation state of the pump 10 is switched in the order of air lock operation, air / water mixing operation, drainage operation, air / water mixing operation, and air lock operation until the operator stops.

(Outline of water level setting in the water tank)
As shown in FIG. 1, the above-described drainage start water level LWL, drainage cutoff water level LLWL, and maximum water level HWL are defined in the water absorption tank 1. These are defined as heights from the bottom wall 3, and are set to increase in the order of the drainage cutoff water level LLWL, the drainage start water level LWL, and the highest water level HWL. At high water levels above the drainage start water level LWL, it is necessary to discharge only water without mixing air. At a low water level lower than the drainage start water level LWL, mixing of air is allowed. At an ultra-low water level below the drainage cut-off water level LLWL, it is necessary to shift to an air lock operation without draining.

The drainage start water level LWL and drainage cutoff water level LLWL are determined as required specifications based on the water level of a nearby river or sea and the status of surrounding buildings. The maximum water level HWL is determined by the depth of the water absorption tank 1 and the required specifications. That is, these water levels LWL, LLWL, and HWL are determined independently of the vortex generation water level VWL shown in FIG. In recent years, since there are many low requests for the drainage start water level LWL, the vortex generation water level VWL tends to be higher than the drainage start water level LWL.

Therefore, in the present embodiment, the vortex prevention pipe 30 and the air supply pipe 38 are provided to enable the preliminary standby operation while suppressing the generation of the air suction vortex Sv, and the drainage at a lower water level can be effectively realized. To do. In addition, the arrangement of the

pipes

30 and 38 having different functions prevents the configuration of the pump 10 from becoming complicated.

(Details of vortex prevention piping)
As shown in FIGS. 3 and 4, the vortex prevention pipe 30 includes one horizontal pipe 32 and a plurality of vertical pipes 35.

The horizontal pipe 32 is hollow, and referring to FIG. 1, the horizontal pipe 32 is disposed on the outer periphery of the pump casing 12 so as to be positioned at the drainage cutoff water level LLWL. The horizontal pipe 32 is fixed to the pump casing 12 by ribs 33 so as to be coaxial with the pump casing 12.

The vertical pipe 35 is hollow, the lower end is connected to the horizontal pipe 32, and the upper end is closed liquid-tight and air-tightly by the cover 36. The upper end of the vertical pipe 35 is disposed at a height equal to or higher than the vortex generation water level VWL when pumping 130% of the rated flow rate of the pump 10, and is disposed at a position higher than the highest water level HWL in this embodiment.

The plurality of vertical pipes 35 are arranged at predetermined intervals in the circumferential direction around the pump casing 12. More specifically, in the water absorption tank 1, three sides between the installation floor 2 and the bottom wall 3 are blocked by the side walls 4, and water flows from the left side where the side walls 4 are not present in FIG. In this embodiment, four vertical pipes 35 are provided at intervals of 90 degrees, two of which are arranged upstream in the water inflow direction F, and the other two are downstream in the water inflow direction F. Is arranged. Hereinafter, two upstream pipes are referred to as first vertical pipes 35A and two downstream pipes are referred to as second vertical pipes 35B as necessary.

(Details of air supply piping)
3 and FIG. 4, the air supply pipe 38 includes the same number of first intake pipes 40 as the first vertical pipes 35A, the same number of second intake pipes 45 as the second vertical pipes 35B, and a plurality of air supply pipes. A pipe 50 is provided. That is, in this embodiment, two sets of the first vertical pipe 35A and the first intake pipe 40, and the second vertical pipe 35B and the second intake pipe 45 are provided.

The intake port 41 of the first intake pipe 40 is disposed at the drainage start water level LWL, and the exhaust port (the other end) 42 of the first intake pipe 40 is disposed in the first vertical pipe 35A. The intake port 46 of the second intake pipe 45 is disposed at the drain cutoff water level LLWL, and the exhaust port 47 of the second intake pipe 45 is disposed in the second vertical pipe 35B. These

intake ports

41 and 46 are opened so as to be positioned in the depression of the water surface when the air suction vortex Sv is generated in order to make it less susceptible to the influence of waves on the water surface of the water absorption tank 1, so that the air can be stably supplied. It is configured to allow intake (supply).

More specifically, the first intake pipe 40 is coaxially arranged in the first vertical pipe 35A, and the second intake pipe 45 is coaxially arranged in the second vertical pipe 35B. Bending

portions

43 and 48 are formed below the

intake pipes

40 and 45 where the

intake ports

41 and 46 are located. The intake port 41 of the first intake pipe 40 protrudes outside from the first vertical pipe 35 </ b> A by the curved portion 43. The intake port 46 of the second intake pipe 45 protrudes outward from the lateral pipe 32 by a curved portion 48. The penetration portion of the first intake pipe 40 in the first vertical pipe 35A and the penetration portion of the second intake pipe 45 in the horizontal pipe 32 are sealed in a liquid-tight and air-tight manner by a sealing material or welding.

The

exhaust ports

42 and 47 of the

intake pipes

40 and 45 are disposed at a position higher than the highest water level HWL. More specifically, as shown in FIG. 1, the height T of the

intake pipes

40 and 45 is set to a value obtained by adding the suction head ΔH due to the maximum negative pressure generated in the bell mouth 17 by pumping to the maximum water level HWL. ing. The suction head ΔH is set by the following equation.

The air supply port 51 of the air supply pipe 50 is connected to the bell mouth 17 so as to be positioned at the drainage cutoff water level LLWL, and the connection port (one end) 52 of the air supply pipe 50 is connected to the inner periphery of the horizontal pipe 32. Yes. That is, the air supply pipe 50 communicates with the

intake pipes

40 and 45 through the vertical pipe 35 and the horizontal pipe 32, and the air supply pipe 38 also serves as the flow path of the vortex prevention pipe 30.

As shown most clearly in FIG. 4, in this embodiment, four air supply pipes 50 are provided, and these are arranged at equal intervals in the circumferential direction around the pump casing 12. Further, the four air supply pipes 50 and the four vertical pipes 35 are arranged at intervals in the circumferential direction, and are configured so that the angular positions in plan view do not match. Thus, the air flowing in from the vertical pipe 35 does not flow directly to the air supply pipe 50 but always flows through the horizontal pipe 32 to the air supply pipe 50, and is evenly supplied from the air supply pipe 50 into the bell mouth 17. Is done. As a result, the vibration of the pump 10 due to the supply air being biased locally can be suppressed.

Since this pump 10 has both functions of suppressing the generation of the air suction vortex Sv and leading standby, it is possible to effectively achieve drainage at a lower water level than a pump without the vortex prevention pipe 30 or the air supply pipe 38. .

Specifically, in the drainage operation, even if the water level in the water absorption tank 1 becomes the vortex generation water level VWL, the generation of the air suction vortex Sv can be suppressed by the vertical pipe 35. Therefore, vibration of the pump casing 12 due to the sucked air suction vortex Sv colliding with the impeller 25 can be prevented.

In the air-water mixing operation, the air in the water absorption tank 1 can be supplied from the first intake pipe 40 into the pump casing 12 by the suction force of the pump 10. Therefore, although the amount of water absorption from the suction inlet 18 decreases, since the flow velocity on the water surface in the water absorption tank 1 is slowed, the generation of the air suction vortex Sv can be suppressed and the level of water that can be drained can be lowered. However, even in this case, as the water level becomes lower, the water surface eventually reaches a flow velocity at which the air suction vortex Sv is generated.

In the air lock operation, the amount of water absorbed from the suction port 18 is further reduced by sucking the air in the water absorption tank 1 from the second intake pipe 45 by the suction force of the pump 10. Therefore, drainage from the pump casing 12 to the downstream side can be stopped reliably, and the state in which the water column WC is held in the pump casing 12 can be maintained. The water column WC cools the submersible bearing 23 which is a sliding component in the pump casing 12 and prevents overheating. Therefore, a standby operation in which the pump 10 is continuously driven can be realized.

Thus, since the operation state is switched depending on the water level in the water absorption tank 1 while suppressing the generation of the air suction vortex Sv by the vortex prevention pipe 30, the water absorption tank is more than a pump without the vortex prevention pipe 30 or the air supply pipe 38. Without deepening 1, drainage at a lower water level can be effectively realized.

In addition, the first intake pipe 40 and the supply pipe 50 that constitute the supply air pipe 38 are connected to the first vertical pipe 35A and the horizontal pipe 32 that constitute the vortex prevention pipe 30, and these are also used as a supply air flow path. doing. Therefore, despite having both functions of suppressing vortex generation and advance standby, the pump 10 as a whole can have a simple configuration.

Further, the upper ends of the

vertical pipes

35A and 35B and the upper ends of the

intake pipes

40 and 45 are arranged at a position higher than the highest water level HWL of the water absorption tank 1. Therefore, water is not sucked up through the

exhaust ports

42 and 47 of the

intake pipes

40 and 45 regardless of the operation state of the pump 10. Therefore, it is possible to prevent dust contained in the water in the water absorption tank 1 from entering the vertical pipe 35 through the

intake pipes

40 and 45. As a result, clogging of the air supply passage including the vortex prevention pipe 30 can be effectively prevented.

(Details of the first intake pipe)
When the first suction port 41 of the first intake pipe 40 is blocked by a wave generated on the water surface in a state where the water surface is located at the drainage start water level LWL, the supply of air into the pump casing 12 is shut off. When the supply and shutoff of air to the pump casing 12 are repeated in a short time by the waves, the pump 10 is vibrated.

In the present embodiment, since the two first intake pipes 40 are arranged, it is possible to prevent these intake ports 41 from being simultaneously blocked by waves. Moreover, in the present embodiment, the wavelength λ (see FIG. 5) of the wave generated in the water absorption tank 1 is measured, and the interval L1 (see FIG. 4) between the two intake ports 41 based on the wavelength λ is It is set as follows. The interval L1 is defined as the distance from one center to the other of the two intake ports 41.

Thus, the interval L1 between the two air inlets 41 is set so as not to be an integral multiple of the wavelength λ of the wave generated in the water tank 1. In other words, if the distance L1 between the two intake ports 41 is set so as to satisfy this equation, it is possible to prevent one of the two first intake pipes 40 and the other from being simultaneously blocked by waves. Therefore, it is possible to prevent repeated supply and shut-off of air in a short time that causes vibration of the pump 10.

As shown in FIG. 5, the intake port 41 of the first intake pipe 40 is opened by a curved portion 43 in a direction intersecting the water surface in the water absorption tank 1. Crossing the water surface means crossing the horizontal surface. Moreover, in the present embodiment, the wave height h of the wave generated in the water absorption tank 1 is measured, and from the wave height h to the upper end (upper top) of the lower end (lower top) of the intake port 41 of the first intake pipe 40. The dimension D1 is set to be high (h <D1). In addition, since the inlet 41 of this embodiment is opened in the direction orthogonal to the horizontal plane, the dimension D1 is the inner diameter of the inlet 41.

Thus, since the height (dimension D1) of the intake port 41 is set to be higher than the wave height h, the intake port 41 can be prevented from being blocked by the wave. Moreover, in the present embodiment, since the two first intake pipes 40 are provided, it is possible to prevent these intake ports 41 from being simultaneously blocked by waves. Moreover, it is possible to effectively prevent the gap L1 between the two intake ports 41 from being blocked by waves. Therefore, it is possible to effectively prevent repeated supply and shutoff of air in a short time, which causes vibration of the pump 10.

It should be noted that the distance L2 between the intake ports 46 of the other two second intake pipes 45 and the dimension D2 from the lower end to the upper end of each intake port 46 are preferably set similarly to the first intake pipe 40. Further, when the second intake pipe 45 is disposed on the outer peripheral portion of the horizontal pipe 32, it is preferable that the inner diameter of the horizontal pipe 32 is set similarly to the first intake pipe 40. However, since the two first intake pipes 40 are always opened in a state where the water surface is located at the drainage cutoff water level LLWL, the interval L2 and the dimension D2 of the second intake pipe 45 are not necessarily set in the above range. It does not have to be.

(Details of cross-sectional area (inner diameter) setting of each pipe)
In order to stabilize the suction of air in the water tank 1 and the supply of air to the pump casing 12, the cross-sectional area of the flow path from the intake port 41 of the first intake pipe 40 to the pump casing 12 (supply port 51) is It is set not to become small. More specifically, Av is the cross-sectional area of the vertical pipe 35, Ap is the cross-sectional area of the first intake pipe 40, Ar is the cross-sectional area of the horizontal pipe 32, and Ai is the cross-sectional area of the air supply pipe 50. When the number of 50 is Ni and the number of the first intake pipes 40 is Np, the following equations (1) to (4) are satisfied.

As in the above formula (1), the in-pipe cross-sectional area Av of the vertical pipe 35 is set to be larger than twice the cross-sectional area Ap of the first intake pipe 40 (Av−Ap> Ap).

Further, as in the above equation (2), the in-pipe cross-sectional area Ai of the air supply pipe 50 is obtained by subtracting the total of the cross-sectional areas Ap of the two first intake pipes 40 from the cross-sectional area Ar of the horizontal pipe 32. It is set smaller than the value. Specifically, the in-pipe cross-sectional area Ar of the horizontal pipe 32 is larger than the in-pipe cross-sectional areas (Np × Ap) of all the first intake pipes 40, and the area obtained by adding the supply pipes 50 to all the first intake pipes 40 ( Np × Ap + Ai). Thereby, the influence at the time of making the 1st intake pipe 40 (2nd intake pipe 45) penetrate in the horizontal pipe 32 is made small.

Further, the in-pipe cross-sectional area Ai of the air supply pipe 50 is set to be equal to or larger than the in-pipe cross-sectional area Ap of the first intake pipe 40 as shown in the above formula (3), and the air supply pipe 50 is set up as in the above formula (4). The number Ni is set to be equal to or greater than the number Np of the first intake pipes 40.

In this way, stable suction and supply of air can be realized by setting as in the above formulas (1) to (4) without reducing the flow path for supplying air. That is, when the water level in the water absorption tank 1 is lowered to the drainage start water level LWL, air can be sucked in quickly and stably.

As described above, since the pump 10 of the present embodiment includes the vortex prevention pipe 30 and the air supply pipe 38, drainage at a lower water level can be effectively realized than a pump without one of them. Moreover, since the air supply pipe 38 also uses the vortex prevention pipe 30 as an air supply flow path, the pump 10 as a whole has a simple configuration despite having both functions of suppressing vortex generation and leading standby. it can.

In addition, the vertical shaft pump 10 of the present invention is not limited to the configuration of the above embodiment, and various modifications can be made.

For example, the two first intake pipes 40 may be arranged on the downstream side of the water absorption tank 1 in the water inflow direction F, or may be arranged on the upstream side and the downstream side one by one. Further, the first intake pipe 40 and the second intake pipe 45 may be alternately arranged in the circumferential direction of the pump casing 12. Further, one each of the first intake pipe 40 and the second intake pipe 45 may be arranged, or three or more of each may be arranged. That is, the number and arrangement of the first intake pipes 40 and the second intake pipes 45 can be changed as necessary.

If the number of the first intake pipes 40 is increased, the interval L1 between the intake ports 41 does not need to be set in the above range. If the number of the second intake pipes 45 is increased, the interval L2 between the intake ports 46 need not be set in the above range. In these cases, the

intake ports

41 and 46 of the

intake pipes

40 and 45 may be arranged in parallel to the water surface (horizontal plane) of the water absorption tank 1, and the dimensions D1 and D2 need not be set in the above range. .

The upper end of the first intake pipe 40 may be disposed below the highest water level HWL. The upper end of the second intake pipe 45 may be disposed below the highest water level HWL. Further, the in-tube cross-sectional areas (inner diameters) of the vertical pipe 35, the horizontal pipe 32, the

intake pipes

40 and 45, and the air supply pipe 50 can be changed as necessary.

An air supply means such as a compressor is connected to the first vertical pipe 35A in which the first intake pipe 40 is arranged, and the pump casing 12 is in the stage where the water level in the water absorption tank 1 has not dropped to the drainage start water level LWL. Air may be supplied (air-water mixing operation can be performed).

DESCRIPTION OF SYMBOLS 1 Water absorption tank 2 Installation floor 3 Bottom wall 4 Side wall 10 Vertical shaft pump 12 Pump casing 13 Pumping pipe 14 Straight pipe 15 Vane casing 16 Bearing casing 17 Bell mouth 18 Suction port 19 Discharge pipe 20 Discharge elbow 22 Rotating shaft 23 Underwater bearing (slide Moving member)
25 Impeller 26 Upper end 30 Vortex prevention piping 32 Horizontal pipe 33 Rib 35 Vertical pipe 35A First vertical pipe 35B Second vertical pipe 36 Cover 38 Air supply piping 40 First intake pipe 41 Inlet (one end, opening)
42 Exhaust port (other end)
43 curved portion 45 second intake pipe 46 intake port (one end, opening)
47 Exhaust port (other end)
48 Bending part 50 Air supply pipe 51 Air supply port (other end)
52 Connection port (one end)
LWL Drainage start water level LLWL Drainage cutoff water level HWL Highest water level VWL Vortex generation water level WC Water column Sv Air suction vortex

Claims

A pump casing arranged to extend in the vertical direction in the water absorption tank;
An impeller disposed rotatably in the pump casing so as to be positioned at a drainage start water level of the water absorption tank;
A vortex prevention pipe for suppressing the occurrence of air suction vortex in the water absorption tank;
An air supply pipe for supplying air in the water absorption tank into the pump casing when the water level in the water absorption tank becomes lower than the drainage start water level;
The vortex prevention pipe is
An annular horizontal pipe that surrounds the lower side of the drainage start water level of the pump casing;
A first vertical pipe disposed outside the pump casing so as to extend in the vertical direction, having a lower end connected to the horizontal pipe and a closed upper end;
The air supply pipe is
A first intake pipe having one end arranged at the drainage start water level in the water absorption tank and the other end arranged in the first vertical pipe;
A vertical shaft pump comprising: an air supply pipe having one end connected to the horizontal pipe and the other end connected to the lower side of the impeller of the pump casing.
The vortex prevention pipe is located at a circumferential interval around the pump casing with respect to the first vertical pipe, and is arranged to extend in the vertical direction outside the pump casing, with a lower end at the horizontal pipe. A second vertical pipe connected to the upper end and closed at the upper end;
2. The air supply pipe further includes a second intake pipe, one end of which is disposed at a drainage cutoff water level of the water absorption tank lower than the drainage start water level, and the other end is disposed in the second vertical pipe. Vertical shaft pump described in 1.
The upper end of the first vertical pipe, the upper end of the second vertical pipe, the other end of the first intake pipe, and the other end of the second intake pipe are higher than the drainage start water level. The vertical shaft pump according to claim 2, which is disposed at a position higher than the highest water level.
The first vertical pipe including the first intake pipe is arranged in two sets with a circumferential interval around the pump casing,
4. The vertical pump according to claim 1, wherein an interval L <b> 1 between one end of the two sets of first intake pipes and the other end of the other satisfies the following. 5.
The vertical pump according to any one of claims 1 to 4, wherein the one end of the first intake pipe is opened in a direction intersecting with a water surface in the water absorption tank.
The relationship between the first vertical pipe and the first intake pipe satisfies the following formula (1):
The relationship between the horizontal pipe, the first intake pipe, and the air supply pipe satisfies the following formula (2):
The vertical shaft pump according to any one of claims 1 to 5, wherein a relationship between the supply pipe and the first intake pipe satisfies the following expressions (3) and (4).