JP6934780B2 - Vertical pump - Google Patents

Description

The present invention relates to a vertical shaft pump.

Patent Document 1 discloses a preceding standby pump in which a pair of air pipes are arranged in order to suppress the generation of an air suction vortex and the vibration of the pump accompanying the generation. One end of the air pipe is connected to the upstream side of the impeller of the pump casing, and the other end is open to the inside of the water absorption tank. In this preceding standby pump, the amount of air introduced into the pump casing is optimized by setting the connection position of the pair of air pipes with respect to the pump casing and the open position of the pair of air pipes in the water absorption tank. ..

JP-A-2009-203806

In the preceding standby pump of Patent Document 1, when the water level in the water absorption tank becomes lower than the 100% pumping water level that requires 100% pumping amount (single-phase flow of water only), air is immediately introduced into the pump casing. NS. Therefore, there is room for improvement in drainage at a water level lower than the 100% pumping water level.

An object of the present invention is to provide a vertical shaft pump capable of suppressing air suction and effectively draining water to a pumping stop water level.

In the present invention, the pump is located at a pump casing in which a suction port is arranged below the set pumping stop water level of the water absorption tank and a pumping water level set at a position higher than the pumping stop water level. An impeller arranged in the casing, a connecting pipe laid outside the pump casing so as to be connected to the lower side of the impeller of the pump casing, and a lower end connected to the connecting pipe. The lower end is arranged between the supply pipe laid outside the pump casing so as to extend upward from the connecting pipe and the pumping water level and the pumping stop water level, and outside the pump casing so as to extend upward from the pumping water level. an intake pipe which is plumbed to, respectively connected to the upper end of the intake pipe and the upper end of the feed tube, a merging pipe which is the piping to the outside of the pump casing, one end on the upper side than the impeller of the pump casing are connected, as the other end to the junction pipe is connected, the Bei example the communicating pipe is a pipe outside the pump casing, said confluent pipe is endless plumbed so as to surround the outer periphery of the pump casing Provide a vertical shaft pump consisting of pipes.

According to this vertical pump, when the water level in the water absorption tank is higher than the pumping water level, a part of the pumping water on the downstream side of the impeller in the pump casing passes through the communication pipe, the merging pipe, the supply pipe, and the connecting pipe. It is supplied (circulated) to the upstream side of the impeller in the pump casing. Therefore, even if the water level in the water absorption tank drops and an air suction vortex is generated, it is possible to prevent the air suction vortex (air) from entering the pump casing. As a result, it is possible to effectively realize a 100% pumping amount in which the pumping fluid is a single-phase flow of water only.

When the water level in the water absorption tank becomes lower than the lower end of the intake pipe, the air in the water absorption tank begins to flow in from the intake pipe. This air is mixed in the order of the intake pipe, the merging pipe, the supply pipe, and the connecting pipe, and then mixed in the pump casing. After that, when the amount of air flowing into the pump casing increases, the air also begins to flow into the communication pipe. In other words, even if the water level in the water absorption tank becomes lower than the pumping water level, the pumping water existing inside each pipe does not immediately cause air to flow into the pump casing, so that the airlock state does not occur immediately. .. Therefore, the inside of the water absorption tank can be drained to the lowest possible water level.

The connecting pipe is connected to the pump casing so as to be located at the pumping stop water level. According to this aspect, the pressure on the upstream side of the impeller in the pump casing can be effectively adjusted.

The connecting pipe is arranged so as to surround the pump casing, and includes an annular portion to which the lower end of the supply pipe is connected, and a connecting portion connecting the annular portion and the pump casing. According to this aspect, since the air flows into the pump casing through the annular portion and the connecting portion, the inflow of air into the pump casing can be further delayed.

The pump casing includes a discharge pipe arranged above the installation floor that covers the upper part of the water absorption tank, and the communication pipe is connected to the upper part of the discharge pipe. According to this aspect, when the vertical shaft pump is started, the communication pipe can be shared as a pipe for bleeding air, so that the number of parts can be reduced and the cost can be reduced.

The communication pipe and the merging pipe , the supply pipe and the merging pipe, and the intake pipe and the merging pipe are all connected via a flow rate adjusting valve. According to this aspect, the airlock can be effectively delayed to the pumping stop water level by adjusting the opening degree of the flow rate adjusting valve.

In the vertical shaft pump of the present invention, the pumping water in the pump casing can be supplied from the downstream side to the upstream side of the impeller through the communication pipe, the merging pipe, the supply pipe, and the connecting pipe. Even if the water level drops, it is possible to suppress the entry of air suction vortices and continue to pump 100% of the water. Further, when the lower end of the intake pipe is opened, the pumping water existing inside each pipe can suppress the suction of air, so that the air lock can be delayed and the water can be effectively drained even at a low water level.

The cross-sectional view which shows the vertical shaft pump which concerns on 1st Embodiment of this invention. The schematic diagram which shows the operating state when the water level is higher than the pumping water level. The schematic diagram which shows the operating state when the water level is lower than the pumping water level. FIG. 6 is a schematic view showing an operating state when the water level is further lowered as compared with FIG. FIG. 6 is a schematic view showing an operating state when the water level is further lowered as compared with FIG. The schematic diagram which shows the airlock state when the water level drops to the pumping stop water level. The cross-sectional view which shows the vertical shaft pump which concerns on 2nd Embodiment.

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

(First Embodiment)
FIG. 1 shows a leading standby type vertical shaft pump 10 according to an embodiment of the present invention. The vertical shaft pump 10 drains rainwater or the like that has flowed into the water absorption tank 1 to the downstream side, and is installed on an installation floor 2 that covers the upper part of the water absorption tank 1.

(Overview of vertical pump)
As shown in FIG. 1, the vertical shaft pump 10 includes a pump casing 12, a rotating shaft 24, and an impeller 26.

The pump casing 12 includes a pumping pipe 13 arranged in the water absorption tank 1 and a discharge pipe 19 arranged 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 arranged in the water absorption tank 1 through the mounting hole 2a of the installation floor 2. The straight pipe 14 is a pipe having a uniform diameter and extends downward from the inside of the mounting hole 2a. The vane casing 15 is a substantially elliptical tubular pipe that bulges outward in the radial direction, and is connected to the lower end of the straight pipe 14. The bell mouth 17 is a substantially conical cylindrical pipe whose diameter gradually increases toward the lower end, and is connected to the lower end of the vane casing 15. The lower end of the bell mouth 17 is a suction port 18 for sucking water in the water absorption tank 1, and is arranged at a predetermined interval with respect to the bottom surface 3 of the water absorption tank 1.

The discharge pipe 19 includes a discharge elbow 20 connected to the upper end of the pumping pipe 13. The discharge elbow 20 is a curved pipe whose central axis is curved by 90 degrees, and is connected to the upper end of the straight pipe 14. A base plate 21 for fixing the pump casing 12 to the installation floor 2 is provided below the discharge elbow 20. A water pipe 22 arranged on the installation floor 2 is connected to the outlet of the discharge elbow 20.

The rotating shaft 24 penetrates the discharge elbow 20 and is arranged along the central axis of the pumping pipe 13. The rotating shaft 24 is rotatably supported by submersible bearings 25A and 25B which are radial bearings. The upper end of the rotating shaft 24 projects outward from the discharge elbow 20. The portion of the discharge elbow 20 through which the rotating shaft 24 penetrates is watertightly sealed by a shaft sealing device (not shown).

The impeller 26 is fixed to the lower end of the rotating shaft 24 located inside the vane casing 15. A bearing case 16 is arranged inside the vane casing 15, and an impeller 26 is arranged under the bearing case 16.

A drive motor 28 is connected to the upper end of the rotating shaft 24. When the rotary shaft 24 is rotated by the drive of the drive motor 28, the impeller 26 rotates integrally with the rotary shaft 24, so that the water in the water absorption tank 1 is drained to the downstream side through the inside of the pump casing 12. NS.

The depth of the water absorption tank 1 (height from the bottom surface 3 to the bottom surface of the installation floor 2) is deeper when the preceding standby pump is used than when it is not. However, it may be required to install the leading standby type vertical shaft pump 10 in the shallow water absorption tank 1 which is different from the one for the leading standby pump. In addition, 100% pumping water level (pumping water level) WL1 that requires 100% pumping amount and pumping stop water level WL2 that stops drainage are also set as required specifications, and these water levels WL1 and WL2 are on standby in advance. It is lower than the set water level of the water absorption tank for the pump.

At 100% pumped storage water level WL1, only water is required to be discharged without air being mixed. Further, the pumping stop water level WL2 is a water level at which the vertical shaft pump 10 shifts to the airlock operation. In the airlock operation, the drive motor 28 continues to be driven (rotation of the impeller 26) by supplying air into the pump casing 12, but drainage from the pump casing 12 is stopped, and a water column is formed in the pump casing 12. This means waiting in a state where Wc is formed (see FIG. 6).

The impeller 26 needs to be arranged at a height of 100% pumping water level WL1. On the other hand, in the water absorption tank 1, the water level at which the air suction vortex is generated is determined by the diameter of the bell mouth (diameter of the suction port 18). This limit submersion depth (vortex generation water level) WL3 is lower than the 100% pumped storage water level WL1 in the case of the water absorption tank for the preceding standby pump. However, in the shallow water absorption tank 1 that is not for the preceding standby pump, the critical submersion depth WL3 is higher than the 100% pumping water level WL1 as shown in the figure. In this case, since an air suction vortex is generated at the 100% pumping water level WL1, 100% pumping amount cannot be realized. Specifically, the air suction vortex is a water flow generated from the water surface toward the suction port 18 of the pump casing 12, and the air in the water suction tank 1 is continuously or intermittently sucked into this water flow. In this case, since the pumping fluid in the pump casing 12 becomes a two-phase flow of water and air, it is not possible to meet the required specification of 100% pumping amount.

In order to meet such required specifications, if the actual water level WL0 in the water absorption tank 1 is 100% pumped water level WL1 or higher, the vertical shaft pump 10 of the present embodiment contains an air suction vortex from the suction port 18. If the water level WL0 drops below 100% of the pumping water level WL1, a gas-liquid adjusting pipe 30 is provided to delay the airlock as much as possible to the pumping stop water level WL2.

(Details of gas-liquid adjustment tube)
First, the pump casing 12 is arranged in the water suction tank 1 so that the suction port 18 is located below the set pumping stop water level WL2. The impeller 26 is arranged in the pump casing 12 so that the upper portion (fixed portion with the rotating shaft 24) is located at the 100% pumping water level WL1 which is higher than the pumping stop water level WL2.

The gas-liquid adjusting pipe 30 supplies a part of the pumping fluid in the pump casing 12 and the air in the water absorption tank 1 into the bell mouth 17, and is piped to the outside of the pump casing 12. When the water level WL0 is 100% or higher than the pumping water level WL1, a part of the pumping fluid is supplied to the upstream side of the impeller 26 to suppress the entry of the air suction vortex from the suction port 18. Further, when the water level WL0 drops below 100% of the pumped water level WL1, the air lock of the vertical pump 10 is delayed by delaying the inflow of air into the pump casing 12. Hereinafter, a specific configuration of the gas-liquid adjusting tube 30 will be described.

The gas-liquid adjusting pipe 30 includes a connecting pipe 31, a supply pipe 32, an intake pipe 33, a confluence pipe 34, and a communication pipe 35. All of these consist of rigid tubular pipes. The communication pipe 35, the merging pipe 34, the supply pipe 32, and the connecting pipe 31 form a water supply channel that supplies (refluxes) a part of the pumping fluid in the pump casing 12 to the upstream side of the impeller 26 in this order. The intake pipe 33, the merging pipe 34, the supply pipe 32, and the connecting pipe 31 form an air supply path for supplying the air in the water absorption tank 1 (outside the pump casing 12) to the upstream side of the impeller 26 in this order.

The connecting pipe 31 is connected to the bell mouth 17 on the lower side (upstream side) of the impeller 26. The connecting pipe 31 is connected to the bell mouth 17 so that the central axis is located at the same height as the pumping stop water level WL2, and protrudes outward in the radial direction from the bell mouth 17. That is, one end 31a of the connecting pipe 31 is arranged in the opening formed in the bell mouth 17, and the other end 31b of the connecting pipe 31 is arranged outside the bell mouth 17.

The lower end 32a of the supply pipe 32 is connected to the connecting pipe 31, and is laid so as to extend upward along the central axis of the pumping pipe 13 from the connecting pipe 31. In the present embodiment, the lower end of the supply pipe 32 made of a straight pipe is closed, and the other end 31b of the connecting pipe 31 is connected to the lower end side portion. Although the upper end 32b of the supply pipe 32 is arranged on the installation floor 2 through the base plate 21 in the present embodiment, it may be arranged in the water absorption tank 1.

The intake pipe 33 is piped in the vertical direction along the central axis of the pumping pipe 13. The lower end 33a of the intake pipe 33 is arranged so as to be located between the same height as the 100% pumping water level WL1 and the same height as the pumping stop water level WL2. The upper end 33b of the intake pipe 33 is arranged at the same height as the upper end 32b of the supply pipe 32.

Specifically, the lower end 33a of the intake pipe 33 is located at a position where air is not sucked when the water level WL0 is 100% or higher than the pumping water level WL1 and is open to the atmosphere when the water level WL0 is lower than the pumping stop water level WL2. Have been placed. That is, the same height as the 100% pumped water level WL1 is not a strict position, and when the water level WL0 is at the 100% pumped water level WL1, the lower end 33a is covered with water and air does not flow into the intake pipe 33. It means a substantial position where the purpose can be achieved. Further, the same height as the pumping stop water level WL2 means that when the water level WL0 is at the pumping stop water level WL2, the lower end 33a is exposed from the water and air flows into the intake pipe 33, which is substantially achieved. Means position. In the present embodiment, the lower end 33a of the intake pipe 33 is arranged at the same height as the 100% pumping water level WL1.

The upper end 33b of the intake pipe 33 is arranged on the installation floor 2 through the base plate 21 like the upper end 33b of the supply pipe 32, but may be arranged in the water absorption tank 1. In other words, the upper end 33b of the intake pipe 33 and the upper end 32b of the supply pipe 32 are both arranged on the installation floor 2 or in the water absorption tank 1. When arranged in the water absorption tank 1, it is preferable that the upper end 33b of the intake pipe 33 and the upper end 32b of the supply pipe 32 are arranged above the planned maximum water level of the water absorption tank 1 so as not to be immersed in water. ..

The merging pipe 34 communicates the supply pipe 32 and the intake pipe 33, and is connected to the upper end 32b of the supply pipe 32 and the upper end 33b of the intake pipe 33. The combined pipe 34 of the present embodiment is piped on the upper side of the installation floor 2. The merging pipe 34 is composed of an endless annular pipe, is coaxial with the central axis of the pumping pipe 13, and is arranged so as to surround the outer circumference of the discharge elbow 20.

The communication pipe 35 communicates the merging pipe 34 with the upper side (downstream side) of the impeller 26 of the pump casing 12. One end 35a of the communication pipe 35 is connected to the upper part of the discharge elbow 20, and the other end 35b of the communication pipe 35 is connected to the confluence pipe 34. An air hole 20a for removing air in the pump casing 12 when the vertical shaft pump 10 is started is formed at the top of the upper end of the discharge elbow 20, and one end 35a of the communication pipe 35 is connected to the air hole 20a. There is. As a result, the communication pipe 35 can be shared as a pipe for bleeding air, so that the number of parts is reduced and the cost is reduced.

The supply pipe 32 and the merging pipe 34, the intake pipe 33 and the merging pipe 34, and the communication pipe 35 and the merging pipe 34 are connected via flow rate adjusting valves 37A to 37C, respectively. These flow rate adjusting valves 37A to 37C are throttle valves that can adjust the opening rate through which the fluid can pass in the range of 100% (fully open) to 0% (fully closed). As the flow rate adjusting valves 37A to 37C, those that can be manually adjusted are used in this embodiment, but those that can be adjusted electrically may also be used. The flow rate adjusting valve 37A adjusts the amount of water, air, and a mixed fluid of water and air supplied from the confluence pipe 34 into the bell mouth 17. The flow rate adjusting valve 37B adjusts the amount of air supplied from the water absorption tank 1 into the confluence pipe 34 and the amount of water drained from the confluence pipe 34 into the water absorption tank 1. The flow rate adjusting valve 37C adjusts the amount of pumped water supplied from the discharge elbow 20 into the confluence pipe 34.

(Transition of operating state of vertical pump)
For example, the vertical shaft pump 10 is started at a water level WL0 (a state in which there may be no water in the water absorption tank 1) lower than the suction port 18 of the bell mouth 17 based on rainfall information or the like. Then, since there is no water in the pump casing 12, the impeller 26 rotates in the air (idle operation). When the water level WL0 rises and exceeds the 100% pumping water level WL1, the water in the water absorption tank 1 is sucked up from the suction port 18 of the bell mouth 17 by the rotation of the impeller 26, and the bell mouth 17, the vane casing 15, and the straight pipe 14 are sucked up. , And drained to the water pipe 22 via the discharge elbow 20 (steady operation).

As shown in FIG. 2, in steady operation, the pumping fluid in the pump casing 12 is a single-phase flow of water only, and there is no air in the pump casing 12. In this steady operation, a part of the pumped water sent from the discharge elbow 20 flows into the communication pipe 35. The reflux water, which is a part of the pumped water, is supplied into the bell mouth 17 through the communication pipe 35, the confluence pipe 34, the supply pipe 32, and the connection pipe 31. Further, a part of the recirculated water is drained from the combined pipe 34 through the intake pipe 33 into the water absorption tank 1.

FIG. 2 shows a state in which the water level WL0 is lower than the critical submersion depth WL3 due to steady operation. In this state, the flow velocity on the water surface increases due to the decrease in the amount of water in the water absorption tank 1, so that an air suction vortex is generated. However, since the reflux water is supplied to the upstream side of the impeller 26 and the inlet side of the pump casing 12 is boosted, the generated air suction vortex cannot enter the pump casing 12. Therefore, it is possible to prevent the air sucked by the air suction vortex continuously or intermittently from flowing into the pump casing 12. As a result, it is possible to meet the required specifications of 100% pumped water amount.

As shown in FIG. 3, when the water level WL0 is lower than the 100% pumped water level WL1 and approaches the lower end 33a of the intake pipe 33, the air in the water absorption tank 1 starts to flow into the intake pipe 33. The inflowing air is mixed into the merging pipe 34 from the intake pipe 33, and a part of the air is mixed in the supply pipe 32 by the flow of the recirculated water. Therefore, the inside of the merging pipe 34 and the inside of the supply pipe 32 are a two-phase flow of recirculated water and air.

As shown in FIG. 4, when the water level WL0 is lower than the lower end 33a of the intake pipe 33 and the lower end 33a is opened, all the water in the intake pipe 33 is returned to the water absorption tank 1. Then, the amount of air mixed in the combined pipe 34 and the supply pipe 32 increases, and the ratio (void ratio) of the air (gas phase) contained in the recirculated water (liquid phase) increases. Further, a part of the air mixed in the supply pipe 32 flows into the pump casing 12 through the connecting pipe 31. Further, a part of the air that has flowed into the pump casing 12 may flow into the communication pipe 35. Then, the void ratio of each pipe gradually increases as the water level WL0 decreases.

As shown in FIG. 5, when the water level WL0 further decreases and approaches the pumping stop water level WL2, an air pool Ar due to the mixed air is formed in the upper part of the discharge pipe 19. Then, air is also mixed in the communication pipe 35, and the recirculated water in the communication pipe 35 returns to the inside of the pump casing 12. As a result, only air is contained in the communication pipe 35. Further, the recirculated water and air inside the merging pipe 34, the supply pipe 32, and the connecting pipe 31 flow into the pump casing 12.

As shown in FIG. 6, when the water level WL0 drops to the pumping stop water level WL2, the air pool Ar in the discharge pipe 19 expands to the vertical pipe portion of the discharge elbow 20, and the water column Wc extends from there to the impeller 26. It is formed and becomes an airlock state. During this airlock operation, the water is not drained to the discharge pipe 19 side, so that water does not flow into the gas-liquid adjusting pipe 30. Therefore, the air sucked from the intake pipe 33 flows into the pump casing 12 through the merging pipe 34, the supply pipe 32, and the connecting pipe 31. This air supply maintains the airlock operation.

When the inflow of water into the water absorption tank 1 increases and the water level WL0 rises to 100% pumped water level WL1, the lower end 33a of the intake pipe 33 is blocked with water, and steady operation is restarted.

As described above, in the vertical shaft pump 10 of the present embodiment, even if the water level WL0 in the water absorption tank 1 is lower than the 100% pumping water level WL1, the recirculated water existing inside each pipe causes the pump casing 12 to be filled. Since the air does not flow in immediately, the airlock state does not occur immediately. Therefore, the water in the water absorption tank 1 can be reliably drained to the pumping stop water level WL2.

Since the connecting pipe 31 is connected to the pump casing 12 so as to be located at the pumping stop water level WL2, the pressure on the upstream side of the impeller 26 in the pump casing 12 can be effectively adjusted. Therefore, when the water level WL0 is 100% or higher than the pumped water level WL1, it is possible to effectively suppress the entry of the air suction vortex into the pump casing 12.

By comprehensively adjusting the opening ratio of the flow rate adjusting valves 37A to 37C, the flow rate between the supply pipe 32 and the merging pipe 34, between the intake pipe 33 and the merging pipe 34, and between the communicating pipe 35 and the merging pipe 34. Can be adjusted. Therefore, when the water level WL0 is higher than the 100% pumped water level WL1, the amount of recirculated water flowing into the pump casing 12 can be appropriately adjusted. As a result, the entry of the air suction vortex can be effectively suppressed. Further, when the water level WL0 is lower than the 100% pumped water level WL1, it is possible to prevent a large amount of air from entering the pump casing 12. As a result, the airlock (drainage stop) of the vertical pump 10 can be effectively delayed until the water level WL0 drops to the pumping stop water level WL2.

(Second Embodiment)
FIG. 7 shows a leading standby type vertical shaft pump 10 of the second embodiment. In this second embodiment, the connecting pipe 31 is composed of an annular portion 31A and a pair of connecting portions 31B and 31B. Other configurations are the same as those in the first embodiment.

The annular portion 31A is composed of an endless annular pipe, and is arranged so as to be located at the same height as the pumping stop water level WL2. Further, the annular portion 31A is arranged coaxially with the central axis of the pumping pipe 13 so as to surround the outer circumference of the bell mouth 17. The lower end 32a of the supply pipe 32 is connected to the annular portion 31A.

The connecting portions 31B and 31B connect the annular portion 31A and the bell mouth 17, and are formed of a straight straight pipe. That is, one end of the connecting portions 31B and 31B is connected to the bell mouth 17 so as to be located at the same height as the pumping stop water level WL2, and the other end of the connecting portions 31B and 31B is connected to the annular portion 31A. Further, the pair of connecting portions 31B and 31B are provided at positions facing each other in the radial direction of the annular portion 31A (bell mouth 17). However, three or more connecting portions 31B may be provided, or only one connecting portion 31B may be provided. When three or more are provided, it is preferable to provide them at equal intervals in the circumferential direction of the annular portion 31A.

In the gas-liquid adjusting tube 30 of the second embodiment, the same actions and effects as those of the first embodiment can be obtained. Moreover, when the water level WL0 is lower than the 100% pumped water level WL1, the air in the water absorption tank 1 flows into the annular portion 31A from the supply pipe 32, and then flows into the pump casing 12 from the connecting portion 31B. Therefore, the inflow of air into the pump casing 12 can be further delayed. Further, since two or more connecting portions 31B and 31B are provided at equal intervals in the circumferential direction, recirculated water and air can be supplied into the pump casing 12 without bias. Therefore, it is possible to suppress the inflow of the air suction vortex and stabilize the airlock operation.

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 connecting pipe 31 may be connected at a position different from the pumping stop water level WL2 as long as it is on the upstream side of the impeller 26 of the pump casing 12.

The confluence pipe 34 is not limited to the endless annular pipe, and the shape may be changed as needed as long as the upper end 32a of the supply pipe 32 and the upper end 33a of the intake pipe 33 can communicate with each other. Of course, the shapes of the connecting pipe 31 (annular portion 31A and connecting portion 31B), the supply pipe 32, the intake pipe 33, and the communication pipe 35 may be changed as necessary.

One end 35a of the communication pipe 35 may be connected to the lower top of the discharge elbow 20. Further, one end 35a of the communication pipe 35 may be connected to the water supply pipe 22, or may be connected to the pumping pipe 13 if it is on the downstream side of the impeller 26 of the pump casing 12. When connecting to the pumping pipe 13, the confluence pipe 34 is preferably arranged in the water absorption tank 1.

The communication pipe 35 and the merging pipe 34, the supply pipe 32 and the merging pipe 34, and the intake pipe 33 and the merging pipe 34 were connected via the flow rate adjusting valves 37A to 37C, but a predetermined portion of each joint portion (for example, intake air). Only between the pipe 33 and the merging pipe 34) may be connected via the flow rate adjusting valve. Further, instead of the flow rate adjusting valves 37A to 37C, the thickness (inner diameter) of each pipe may be changed according to the required amount of recirculated water and air.

1 ... Water absorption tank 2 ... Installation floor 2a ... Mounting hole 3 ... Bottom surface 10 ... Vertical pump 12 ... Pump casing 13 ... Pumping pipe 14 ... Straight pipe 15 ... Vane casing 16 ... Bearing case 17 ... Bellmouth 18 ... Suction port 19 ... Discharge Pipe 20 ... Discharge elbow 20a ... Air hole 21 ... Base plate 22 ... Water supply pipe 24 ... Rotating shaft 25A, 25B ... Submersible bearing 26 ... Impeller 28 ... Drive motor 30 ... Gas-liquid adjustment pipe 31 ... Connection pipe 31a ... One end 31b ... The other end 31A ... annular part 31B ... connection part 32 ... supply pipe 32a ... lower end 32b ... upper end 33 ... intake pipe 33a ... lower end 33b ... upper end 34 ... merging pipe 35 ... communication pipe 35a ... one end 35b ... other end 37A to 37C ... flow rate Control valve WL1 ... 100% pumping water level (pumping water level)
WL2 ... Pumping stop water level WL3 ... Limit submersion depth (vortex generation water level)
Ar ... Air pool Wc ... Water column

Claims (5)

A pump casing in which the suction port is located below the set pumping stop water level of the water suction tank, and
An impeller arranged in the pump casing so as to be located at a pumping water level set higher than the pumping stop water level.
A connecting pipe laid outside the pump casing so as to be connected below the impeller of the pump casing.
A supply pipe having a lower end connected to the connecting pipe and piped outside the pump casing so as to extend upward from the connecting pipe.
An intake pipe having a lower end arranged between the pumping water level and the pumping stop water level and piped outside the pump casing so as to extend above the pumping water level.
A confluence pipe connected to the upper end of the supply pipe and the upper end of the intake pipe and piped outside the pump casing, respectively.
Wherein said pump casing impeller end on the upper side is connected than, as the other end to the junction pipe is connected, Bei example the communicating pipe is a pipe outside the pump casing,
The combined pipe is a vertical shaft pump composed of an endless pipe laid so as to surround the outer periphery of the pump casing. The vertical shaft pump according to claim 1, wherein the connecting pipe is connected to the pump casing so as to be located at the pumping stop water level. The connecting pipe
An annular portion arranged so as to surround the pump casing and to which the lower end of the supply pipe is connected,
The vertical shaft pump according to claim 1 or 2, further comprising a connecting portion connecting the annular portion and the pump casing. The pump casing comprises a discharge pipe located above the installation floor covering the top of the water absorption tank.
The vertical shaft pump according to any one of claims 1 to 3, wherein the communication pipe is connected to an upper portion of the discharge pipe. The communication pipe and the merging pipe , the supply pipe and the merging pipe, and the intake pipe and the merging pipe are all connected via a flow rate adjusting valve, according to any one of claims 1 to 4. The described vertical shaft pump.

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