JPH05231399A - Pump - Google Patents

Abstract

PURPOSE:To shorten a siphon forming time and further to reduce a cost and improve reliability by quickly removing residual air in a top part of a siphon pipe of constituting a delivery pipe even without using a vacuum pump or the like at the time of starting. CONSTITUTION:A plurality of flow paths 11A, 11B placed in a position of the lower level in accordance with a side of increasing a flow speed are formed by dividing a siphon pipe 5 in a width direction, to connect these flow paths 11A, 11B in a top part 5a.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pump used for a large-capacity one that discharges a large amount of water with a low head.

[0002]

2. Description of the Related Art As is well known, in a pump having a low head with a small water level difference between suction and discharge, the siphon tube is placed at a level higher than the maximum water level (HWL) with the middle of the discharge pipe as the top. There are many so-called siphon-type pumps configured. In this siphon-type pump, it is necessary to remove air in the siphon pipe at the time of starting to form a siphon. As a siphon forming means, conventionally, the flow velocity in the siphon pipe is constant (at least 1 m / s or more There is a means to let the residual air in the top of the siphon flow out, or to form an intake hole in the top of the siphon to forcibly discharge the residual air using a vacuum pump etc. It was taken.

[0003]

However, of the siphon forming means at the time of starting the pump as described above, the former one has a structure in which the residual air is drawn in only by making the flow velocity constant or more, so that the siphon formation is not possible. Therefore, it takes a considerably long time, and the start of normal operation is delayed accordingly. Especially, in the case of a large-capacity pump, if the set flow rate at the time of siphon formation is low, it will be delayed for more than ten minutes. In the latter case, a vacuum pump or the like is required, which leads to an increase in equipment cost and an increase in the number of pump station components, resulting in a decrease in reliability of the entire system.

The present invention has been made to solve the above problems, and an object of the present invention is to provide a pump capable of shortening the siphon formation time and reducing the facility cost.

[0005]

In order to achieve the above-mentioned object, the present invention is such that the siphon type discharge pipe is divided in the width direction so that the one having a higher flow velocity satisfies the function of the siphon type discharge pipe. A plurality of flow paths at the lowest possible level are formed, and the plurality of flow paths are connected at the top of the siphon via a communication path.

[0006]

In general, the water discharged from the vertical shaft pump still has the rotational speed component given by the impeller, and the water flowing into the siphon pipe when the pump is started has a flow velocity difference in the width direction of the discharge pipe. .. At this time, in the present invention, among the plurality of flow passages formed by dividing the discharge pipe in the width direction, the one having the higher flow velocity is positioned at the lower level, so that the flow at the lowest level position is initially set. A siphon is formed on the road, and as a result, air in the remaining flow paths is sucked through the communication passage to sequentially promote siphon formation, and siphon formation as a whole is achieved in a short time.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. 1 and 2 are a schematic configuration diagram and a plan sectional view, respectively, showing a pump according to an embodiment of the present invention. In FIG. 1, reference numeral 1 is a pump casing, and one end of the pump casing is located in a water suction passage 2. The suction pipe 3 is connected,
A discharge pipe 5 extending to the drainage channel 4 is connected to the other end side. Reference numeral 6 denotes a rotary shaft which is provided vertically through the pump casing 1 and driven by an external rotary drive device (not shown), and an impeller 7 is attached to the lower end of the rotary shaft 6. 8 and 8 ′ are bearings for supporting the rotary shaft 6, 9
Is a fixed guide vane located above the impeller 7 and fixed to the pump casing 1. The discharge pipe 5 is formed as a siphon pipe by arranging the middle portion thereof as a top portion 5a at a level higher than the highest water level (HWL).

The inside of the siphon tube 5 has a partition wall 1 in its width direction.
The flow paths 11A and 11B are divided by 0 and are located at the lower level position on the side of higher flow velocity, and both flow paths 11A and 11B are formed on top of the siphon tube 5 as shown in FIG. In 5 a, they are communicated with each other via the communication passage 12. In FIG. 1, reference numeral 13 denotes a vacuum breaking valve attached to the top portion 5a of the siphon tube 5 for opening the valve when the pump is stopped to break the siphon.

Next, the operation of the above configuration will be described. When the rotary shaft 6 is driven by the rotary drive device, the impeller 7 rotates and the water in the water suction passage 2 is sucked up. At this time, the water sucked up follows the rotation direction of the impeller 7,
For example, since the velocity component swirling in the direction of arrow a in FIG. 2 is sent to the discharge pipe, that is, the siphon pipe 5, the flow velocity distribution is largest on one side in the width direction and is on the other side as indicated by the chain line. It is the smallest state. Siphon tube 5 above
Is divided into three flow passages 11A and 11B in the width direction, and the flow passage 11A on the side having the largest flow velocity is at a low level position, so that the flow velocity here is faster than other flow passages. Therefore, the residual air A is discharged earlier and the siphon is formed in a shorter time than the other flow paths.

When a siphon is first formed in the flow passage 11A, residual air A in the adjacent flow passage 11B is transferred to the communication passage 1
Since it is sucked into and discharged from the flow path 11B side through 2, the siphon formation of this flow path 11B is promoted. As a result, the siphon forming time of the siphon tube 5 as a whole is significantly shortened, and the shift to the normal operation is quickly performed. Further, since it is only necessary to form the flow passages 11A and 11B and the communication passage 12 in the siphon pipe 5 in order to promote the siphon formation, the equipment cost can be reduced as compared with the case where the residual air is forcibly discharged using a vacuum pump or the like. Can be suppressed,
The reliability of the entire machine can be improved.

The number of divisions of the siphon tube 5 in the width direction is not limited to that in the above embodiment, but can be changed appropriately.

[0012]

As described above, according to the present invention, the discharge pipe constituting the siphon is divided in the width direction to form a plurality of flow passages having lower level positions on the side having a higher flow velocity, and at the top portion. Since these flow paths are connected to each other, siphon formation can be promoted sequentially from the low-level flow path, and the overall siphon formation time can be shortened. Moreover, it is not necessary to install a vacuum pump or the like, and cost can be reduced. And reliability can be improved.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram showing a pump according to an embodiment of the present invention.

FIG. 2 is a plan sectional view of the pump.

3 is a cross-sectional view taken along the line III-III in FIG.

[Explanation of symbols]

 5 Discharge pipe (siphon pipe) 5a Top part 11A, 11B, 11C Flow path 12 Communication path HWL Maximum water level

Claims (1)

[Claims] 1. A pump in which the middle of the discharge pipe is located at a level higher than the maximum water level and the discharge pipe is arranged in a siphon shape, in which the siphon discharge pipe is divided in the width direction and A pump characterized in that a plurality of flow paths are formed at extremely low levels, and the plurality of flow paths are communicated with each other via a communication path at the top of the siphon.