JPH074379A - Axial mixed flow pump - Google Patents

Abstract

PURPOSE:To allow high pressure water, obtained by turning contraflow generated at the time of small water quantity operation such as the pump starting time or the nearly stopping time, to be effectively used as wash water. CONSTITUTION:A pipeline 6 for taking outside high pressure water Wa obtained by turning contraflow generated in a suction side area at the time of small water quantity operation is connected to a position more on the suction side than the position of an impeller 3 in a casing 1, and this high pressure water Wa is used as wash water for the backwash of a screen 10, the elimination of sand M, and the like.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an axial mixed flow pump installed and used in various pumping stations.

[0002]

2. Description of the Related Art In an axial mixed flow pump of this type, when a small amount of water is operated such as when the pump is started or stopped, the impeller rotates in a region upstream of the impeller in the casing, that is, on the suction side. A swirling backflow in the direction opposite to the direction occurs and the pressure in that region also rises, but conventionally, high pressure water due to such a swirling backflow is left as it is.

[0003]

As described above, in the conventional axial mixed flow pump, the high pressure water due to the swirling reverse flow generated in the suction side region is used at the time of a small amount of water operation such as starting and stopping. However, since it is high-pressure water, effective utilization of it has been desired.

The present invention has been made in view of the above demands, and it is possible to take out high-pressure water accompanying swirling backflow to the outside and effectively use it, for example, for backwashing a screen or removing sediments under a screen. It is intended to provide an axial mixed flow pump.

[0005]

In order to achieve the above object, an axial mixed flow pump according to the present invention has a casing on the suction side with respect to the position of the impeller in the casing on the suction side during a small amount of water operation. The pipe is connected to take out the high-pressure water generated by the swirling backflow generated as described above as external cleaning water.

[0006]

According to the present invention, when a small amount of water is operated, such as when the pump is started or stopped, high-pressure water is generated by the swirling reverse flow generated in the suction side region, and the high-pressure water is absorbed by the suction water. It will be taken out through the pipe connected to the side. Therefore, by opening the tip of the pipe on the downstream side of the screen, or by opening it toward the settling part at the bottom of the screen, the high-pressure water is used as washing water for backwashing the screen or removing settling. It can be used effectively, and by this,
Special maintenance work such as backwashing the screen can be omitted or saved.

[0007]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a configuration diagram showing an outline of an axial mixed flow pump according to an embodiment of the present invention. In FIG. 1, reference numeral 1 denotes a cylindrical casing of the axial mixed flow pump, inside of which a main shaft 2 is interposed. An impeller 3 which is rotationally driven by an external motor (not shown) is provided, and the water W in the pump well 4 is pumped by the rotation of the impeller 3.

On the peripheral wall portion of the suction bell 5, which is a portion of the casing 1 on the suction side with respect to the position of the impeller 3, a swirling reverse flow generated when a small amount of water is operated, such as when the pump is started or near stop. One end 6a of a pipe 6 for taking out the high-pressure water Wa by S is connected. Further, as shown in FIG. 2, the inner peripheral surface of the suction bell 5 impedes the swirl reverse flow S downstream of the connection position of the one end 6a of the pipe 6 in the swirl direction of the swirl reverse flow S. The rib 7 is fixedly projected. Reference numeral 8 is a check valve interposed in the pipe 6.

Reference numeral 9 denotes a sand settling portion provided on the upstream side of the suction flow path in the above-mentioned pump, and is a cleaning screen 10
Is installed. The other end 6b of the pipe 6 is opened toward the downstream surface of the screen 9, and the high-pressure water Wa is jetted toward the screen 10 and the sediment M to backwash the screen 9 and remove the sediment M. I'm trying to get rid of it. In the middle of the pipe 6,
An ejector pipe 11 that is opened above the water surface of the pump well 4 and sucks the air a is connected. 12 is an ejector.

Next, the operation of the axial mixed flow pump having the above construction will be described. When the pump is operating, the impeller 3 is rotationally driven via the main shaft 2 to perform a predetermined pumping, but when the pump is started or when a small amount of water is being operated, such as when the pump is about to stop, the suction bell 5 is swirled. The backflow S is generated and the pressure in the suction bell 5 rises. The swirling backflow S collides with the ribs 7 provided on the inner peripheral surface of the suction bell 5 to further increase the pressure. High-pressure water W due to such swirling backflow S
a is taken out through the pipe 6, and the other end 6b
Is sprayed toward the downstream surface of the screen 10 and the settling sand M, so that backwashing and sand settling M for the screen 10 is performed.
Will be automatically removed every time the pump operates with a small amount of water.

When the high-pressure water Wa is jetted as described above, since the air a is sucked by the ejector 12 through the ejector pipe 11 connected in the middle of the pipe 6, the high-pressure water Wa becomes a bubble. As a result, the large area such as the screen 10 can be cleaned at once.

In the above embodiment, the air a is sucked by the ejector 12 from the ejector pipe 11 connected in the middle of the pipe 6, but the water is sucked in by making the inlet of the ejector pipe 11 below the water surface. Alternatively, the amount of water for cleaning may be increased.

[0013]

As described above, according to the present invention, the high-pressure water due to the swirling backflow generated in the region on the suction side of the impeller position during the small amount of water operation such as when the pump is started or when the pump is about to be stopped is provided. Since it can be taken out to the outside, the taken-out high-pressure water can be effectively used, for example, for backwashing the screen or removing the sand settling portion. Therefore, by simply adding a simple configuration such as connecting a pipe to the suction side, high-pressure water generated during small-volume operation is effectively used to maintain the smoothness of the entire fluid flow, and maintenance work can be omitted or This has the effect of achieving savings.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing an outline of an axial mixed flow pump according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view of a suction portion of the axial mixed flow pump according to the embodiment.

[Explanation of symbols]

 1 Casing 3 Impeller 5 Suction Bell 6 Piping S Swing Reverse Flow Wa High Pressure Water

Claims (1)

[Claims] 1. A pipe is connected to a position closer to the suction side than the position of the impeller in the casing, for extracting high-pressure water by swirling backflow generated in the region on the suction side during small-volume operation as external cleaning water. A characteristic axial mixed flow pump.