JPH0631636B2 - Vertical pump management operation method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of operating a pump in a controlled manner.

Generally, pumps at the drainage pump station, which is installed to drain water from a waterway during a flood or the like, are under maintenance operation. This management operation is a test operation performed to confirm the operation of the pump and the prime mover in addition to the normal operation such as during a flood, in view of the characteristics that the reliability of this type of pump is important and the operation frequency is low. Therefore, since the pump is operated when the amount of water is small, the discharge valve downstream of the pump is fully closed to perform the shutoff operation.

The drainage pump station where such management operation is performed is the first
As shown in the figure, the vertical pump 2 is placed in the pit 1,
A prime mover 3 of the vertical shaft pump 2 is installed on the floor of the pit 1 to drain water through a pumping pipe 5 having a discharge valve 4 interposed.

By the way, the conventional management operation method of such a vertical shaft pump 2 is as follows. That is, this is a method in which the water level in the pit 1 is lowered so that the lower half of the impeller of the vertical shaft pump 2 is submerged, and then the shutoff operation is performed. this is,
When the shutoff operation is performed at the normal water level, the required axial power becomes excessively large. On the other hand, when the vertical shaft pump 2 is exposed above the water surface and idled, foreign matter is trapped between the impeller and the casing 6. Since a serious accident may occur at times, the air in the vertical shaft pump 2 is mixed into the water in the form of bubbles to reduce the apparent density of water, reduce the shaft power required for the deadline operation, and reduce foreign matter. It is intended to prevent the occurrence of a serious accident due to the biting of the.

However, in such a conventional method, the above-described effect is obtained only in the initial stage of the start of the management operation, and when the management operation is continued, the air in the vertical shaft pump 2 is discharged from the bell mouth 7 by the water which is about to flow. There was a problem that it was discharged to the outside and it became the same as performing the deadline operation at the normal water level.

This problem has occurred because the apparent density of water in the vertical pump 2 cannot be controlled to a density suitable for the management operation during the management operation.

The present invention has been made in view of the above situation, and keeps the apparent density of water in the vertical shaft pump during the management operation small to reduce the shaft power and prevent foreign matter from being caught. It is an object of the present invention to provide a management operation method for a vertical shaft pump that can be reliably achieved.

In order to achieve the above object, a method of managing operation of a vertical shaft pump according to the present invention is such that a discharge valve provided in a pumping pipe of a vertical shaft pump is closed in advance, and compressed air is provided between the discharge valve and a bell mouth. Is supplied, the shutoff operation of the vertical shaft pump is performed in a state where the water level in the pumping pipe is at the position of the impeller, and further, the supply of the compressed air is continued during the shutoff operation.

According to the present invention, by supplying compressed air between the discharge pipe of the vertical shaft pump and the bell mouth, by performing a shutoff operation of the vertical shaft pump in a state where the water level in the pumping pipe is at the position of the impeller,
The water inside the vertical pump and the compressed air are agitated to form a gas-liquid two-phase flow in which bubble-like air is mixed in the water, which reduces the apparent density of water in the vertical pump. Then, during the deadline operation, the supply of the compressed air is continued,
Since the control operation of the vertical pump is continued in water with apparently low density, the axial power required for the control operation of the vertical pump is reduced, and there is always water around the impeller. Foreign matter is prevented from being caught between the impeller and the casing by the lubrication action of.

As described above, during the maintenance operation of the vertical shaft pump, the apparent density of water in the vertical shaft pump can be controlled to a density suitable for a predetermined management operation.

In the present invention, since the compressed air is supplied to the inside of the vertical pump, the water level in the vertical pump can be lowered by the pressure of the compressed air regardless of the water level in the pit, which makes it difficult to adjust the water level in the pit. It can be omitted.

An embodiment of the present invention will be described below with reference to FIG.
In FIG. 2, the same reference numerals as those in FIG. 1 indicate the same or corresponding parts.

An impeller 8 is axially supported by a bearing portion 9 inside a casing 6 in FIG. 2, and a guide blade 10 is formed above the impeller 8. A bell mouth 7 is fixed to the lower end of the casing 6, and a pumping pipe 5 is connected to the upper end of the casing 6. A discharge valve 4 (see FIG. 1) is provided downstream of the pumping pipe 5. Further, one end of a pressure feeding pipe 11 is connected to the pumping pipe 5 in the vicinity of the casing 6 so as to communicate with the water feeding pipe 5, and the other end of the pressure feeding pipe 11 is connected to a compressed air source 12. Further, an on-off valve 13 is provided in the middle of the pressure feeding pipe 11.

Such a management operation method in the vertical shaft pump 2 is executed according to the following steps (1) to (3). That is, the discharge valve 4 is fully closed.

The on-off valve 13 is fully opened to supply the compressed air from the compressed air source 12 into the vertical shaft pump 2 through the pressure feeding pipe 11, and as shown in FIG. 2, the water level (water level) IW in the pumping pipe 5 is set to the impeller. Lower to position 8.

The shutoff operation of the vertical shaft pump 2 is started in this state, and during this shutoff operation, the compressed air source 12 continuously supplies an amount of compressed air commensurate with the amount of air discharged from the bell mouth 7 to the outside.

The operation of the above embodiment will be described. When the impeller 8 is rotated in a state where the water surface IW in the vertical pump 2 is lowered to such an extent that the lower part of the impeller 8 is submerged in water, water and air are agitated and bubbled air is mixed into the water. It becomes a so-called gas-liquid two-phase flow.

In this way, in the state where the vertical axis pump 2 is in a gas-liquid two-phase flow, the apparent density of the fluid in the vertical axis pump 2 decreases, and it is necessary even if the shutoff operation of the vertical axis pump 2 is continued. The shaft power does not increase, and an excessive load is prevented from acting on the prime mover of the vertical shaft pump 2. Further, foreign matter is prevented from being caught between the impeller 8 and the casing 6 due to the lubricating action of water.

The present invention is not limited to the above embodiment. For example, the deadline operation start timing of the vertical shaft pump 2 is not limited to the case where the deadline operation is performed after the water surface in the vertical shaft pump 2 is lowered, and the deadline operation is started when compressed air is supplied into the vertical shaft pump 2. You may start.

[Brief description of drawings]

FIG. 1 is a vertical sectional view showing a conventional example, and FIG. 2 is a vertical sectional view showing an embodiment of the present invention. 2 ... Vertical shaft pump 4 ... Discharge valve 5 ... Pumping pipe 7 ... Bell mouth 8 ... Impeller 11 ... Pressure pipe

Claims (1)

[Claims] 1. A discharge valve provided on a pumping pipe of a vertical shaft pump is closed in advance, compressed air is supplied between the discharge valve and a bell mouth, and the water level in the pumping pipe is at the position of an impeller. A method for managing operation of a vertical shaft pump, comprising: performing a deadline operation of the vertical shaft pump in a certain state, and further continuing the supply of the compressed air even during the deadline operation.