JPH04116293A - Operating method for horizontal shaft pump - Google Patents

Abstract

PURPOSE:To perform proper drainage in emergency by instantaneously applying the negative pressure of a vacuum tank to an intake pipe upstream an impeller when the water level of a water intake well reaches the pumping start water level, and raising the water level in the intake pipe to the water level that a horizontal shaft pump can drain via the self-suction capability for the pumping operation. CONSTITUTION:When the water level of a water intake well 1 reaches the pumping start water level HWL, a communicating valve 25 is fully opened instantly based on the water level detection signal detecting this water level. The negative pressure of a vacuum tank 22 is applied to a space 12, and the water level in an intake pipe 4 is instantaneously raised to the water level that a horizontal shaft pump can drain via the self-suction capability. When the water level of the water intake well 1 reaches the pumping start water level HWL, the air operation is instantaneously switched to the pumping operation. The air operation is instantaneously switched to the pumping operation when the water level of the water intake well 1 reaches the pumping start water level HWL, no lag is generated on the start timing of the pumping operation even in emergency when a large quantity of water abruptly flows into the water intake wall 1, thus the occurrence of a flood due to an abnormal rise of the water level of the water intake wall 1 can be surely prevented.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a method of operating a horizontal shaft pump.

[Prior Art] Conventionally, in the suction type horizontal shaft pump installed in the pump suction well 1 of the drainage pump station shown in Fig. 3, when the water level in the suction well 1 reaches the pumping start water level HWL, This water level HWL is detected by the pressure switch 23 of the vacuum system 2 or a water level detection means (not shown), and the vacuum pump 20 is started based on this detection signal, and the suction pipe 4 disposed upstream of the impeller 3 The water in the suction pipe 4 is sucked up to the level that reaches the impeller 3 in the pump casing 5, that is, the full water level, and after this state is detected by the full water detector 6, based on the full water detection signal. to operate the pump (rotate the impeller 3), and then open the discharge valve 7.
An operating method is adopted in which the pump is fully opened for drainage operation (pumping operation).

[Problem 31 to be solved by the invention] However, in the conventional operating method, after the water level in the water suction well l reaches the pumping start water level HWL, the vacuum pump 20 is started and the inside of the suction pipe 4 is placed under high load. It takes time to pressurize and fill the pump casing 5 with water, and since the discharge valve 7 is fully opened after the pump is started, it takes time before the water is actually drained.

Therefore, a relatively long time (about 10 minutes) is required after the water level in the water intake well 1 reaches the pumping start water level HWL until the pumping operation starts.

On the other hand, in recent years, the water retention function of geological formations has been declining due to an increase in paving ratio and a decrease in green areas due to the progress of urbanization. Moreover, since the amount of water flowing into the water absorption well 1 tends to increase, a situation in which a large amount of water suddenly flows into the water absorption well 1, such as a so-called flash flood, is likely to occur.

However, in the conventional horizontal shaft pump operation method, a relatively long time is required between the water level in the water intake well 1 reaching the pumping start water level HWL and the pumping operation starting. In an emergency when water suddenly flows into the water intake well l, there may be a delay in the start timing of the pumping operation.

As described above, if the start timing of the pumping operation is delayed, the water level in the water intake well 1 may rise abnormally, leading to a flood.

In addition, even if a failure occurs in the pump body, drive system, vacuum system 2, discharge valve 7, etc., a predetermined period of time will elapse after the water level in the suction well l reaches the pumping start water level HWL and water pumping (drainage) is required. The above-mentioned failure cannot be confirmed until the period has passed, and therefore, it may not be possible to properly drain the water in an emergency.

The present invention was developed in view of the above circumstances, and by operating at full speed regardless of the water level of the water intake well, it is possible to perform standby operation that can cope with sudden increases in water level, and to prevent abnormal rises in water level. The purpose of this invention is to provide a method of operating a horizontal shaft pump that can prevent flooding.

[Means for Solving the Problems] In order to achieve the above object, the present invention provides a system in which the vacuum pump is turned off from the lowest water level to just before the water intake well in which the horizontal shaft pump is installed reaches the pumping start water level. The operation creates a negative pressure in the vacuum tank, and the discharge valve of the horizontal shaft pump is opened to perform air operation, and when the water level in the water intake well reaches the pumping start water level, the negative pressure in the vacuum tank is instantly sucked upstream of the impeller. The horizontal shaft pump acts on the inside of the pipe to raise the water level in the suction pipe to a water level at which water can be drained by the self-priming capacity of the horizontal shaft pump, thereby performing water pumping operation.

[Function] According to the present invention, from the lowest water level to just before the water level in the water intake well reaches the pumping start water level, the vacuum tank is made to have a negative pressure by operating the vacuum pump, and the pump discharge valve is opened. and perform full-speed standby operation.

In this state, when the water level in the water intake well reaches the pumping start water level,
The negative pressure of the vacuum tank is instantaneously applied to the suction pipe upstream of the impeller to raise the water level in the suction pipe to a water level at which the horizontal shaft pump can drain water with its self-priming ability, thereby switching to pumping operation. In other words, when the water level in the water intake well reaches the pumping start water level, it is possible to immediately switch from submerged operation to pumping operation.

[Example] Embodiments of the present invention will be described below based on the drawings.

FIG. 1 is a schematic configuration diagram of one embodiment, and the same or equivalent parts as in the conventional example shown in FIG. 3 are given the same reference numerals, and detailed explanation thereof will be omitted.

In FIG. 1, the outlet of the discharge pipe 8 downstream of the discharge valve 7 faces the water of a drainage channel (for example, a river) 9.

The vacuum system 2 includes a vacuum pump 20, an intake pipe 24 that communicates the intake side of the vacuum pump 20 with the impeller inlet 10 of the pump casing 5, and an intake pipe 24 that is interposed in series with the intake pipe 24 from the vacuum pump 20 side. It is composed of a valve 21, a large-capacity vacuum tank 22, and a communication valve 25, and the pressure inside the vacuum tank 22 is detected by a pressure switch 23.

The vacuum tank 22 is connected to the suction pipe 4 when the discharge valve 7 is fully opened.
It has the function of raising the water level IWL in the well by an amount of H2 above the water level in the water absorption well I. In other words, the pumping start water level H
The horizontal shaft pump reaching the impeller 3 in the pump casing 5 from WL has a capacity that can raise the water level IWL in the suction pipe 4 corresponding to the height H2 to the water level at which water can be drained with self-priming ability. There is.

Specifically, when the discharge valve 7 is fully opened, a series of sealed spaces 12 formed from the water surface in the suction pipe 4 to the outlet of the discharge pipe 8 facing the water in the drainage channel 9 are instantly made negative pressure,
The vacuum system 2 has a capacity that can raise the water level IWL in the suction pipe 4 by an amount of H2 above the water level in the water suction well 1.
The amount H2 of raising the water level IWL is maintained appropriately by controlling the operation of the vacuum pump 20 based on the pressure detection signal of the pressure switch 23.

Next, the operation of the above configuration will be explained.

(2) When the water level in the water intake well l reaches the lowest ice level LWL from below the lowest water level LWL, this water level LWL is detected by a water level detection means (not shown), and the vacuum pump 20 is started based on the water level detection signal; The valve 21 is opened while the communication valve 25 is closed.

At the same time, the discharge valve 7 is fully opened based on the water level detection signal to perform full speed air operation of the pump, that is, full speed a operation.

(2) By operating the vacuum pump 20, the pressure inside the vacuum tank 22 is made negative.

(2) Full-speed standby operation is performed while increasing the negative pressure in the vacuum tank 22 until just before the water level in the water suction well 1 reaches the pumping start water level HWL.

■When the water level in the water intake well l reaches the pumping start water level HWL, the communication valve 2
Fully open 5 at once. As a result, the negative pressure of the vacuum tank 22 acts on the space 12, and the water level in the suction pipe 4 is instantly raised to a level at which the horizontal shaft pump can drain water with its self-priming capacity (see Figure 2). .

That is, when the water level of the water intake well 1 reaches the pumping start water level HWL, the submerged operation is instantly switched to the pumping operation.

In this way, when the water level in the water intake well reaches the pumping start water level HWL, the operation is instantly switched from submerged operation to pumping operation, so even in an emergency when a large amount of water suddenly flows into the water intake well, Since there is no delay in the start timing of the pumping operation, it is possible to reliably prevent flooding due to an abnormal rise in the water level of the water intake well 1.

In addition, the pump body, drive system, vacuum system 2, discharge valve 7
Even if a failure occurs in the communication valve 25, etc., the failure can be confirmed and dealt with before the water level in the water intake well l reaches the pumping start water level HWL, so in an emergency This enables proper drainage and improves the reliability of the drainage pump station.

[Effect of the invention] Since the present invention is configured as described above.

This produces the following effects.

In other words, when the water level in the water intake well reaches the pumping start water level,
Since submersible operation (full-speed standby operation) can be switched instantly to pumping operation (full-speed drainage operation), even in an emergency when a large amount of water suddenly flows into the water intake well, there is no delay in the start of pumping operation. This makes it possible to reliably prevent flooding caused by an abnormal rise in the water level in the water suction well, and even if a failure occurs in the pump body, drive system, or vacuum system, the water level in the water suction well will remain unchanged. Since failures can be identified and dealt with before the water reaches the starting water level, proper drainage is possible in emergencies and the reliability of the drainage pump station can be improved.

[Brief explanation of drawings]

FIG. 1 is a schematic configuration diagram of a device applied to the present invention, FIG. 2 is an explanatory diagram showing the relationship between the water level in a water suction well and the water level in a suction pipe, and FIG. 3 is a schematic configuration diagram of a conventional example. 1... Water intake well 3... Impeller 4... Suction pipe 7... Discharge valve 20... Vacuum pump 22... Vacuum tank HWL... Pumping start water level LWL... Minimum water level IWL ... Water level in the suction pipe H2 ... Height from the pumping start water level to the water level at which the horizontal shaft pump can drain water with its self-priming capacity

Claims (1)

[Claims] (1) From the lowest water level to just before the water intake well where the horizontal shaft pump is installed reaches the pumping start water level, the vacuum tank is brought to negative pressure by operating the vacuum pump, and the discharge valve of the horizontal shaft pump is closed. The valve is opened and air operation is performed, and when the water level in the water suction well reaches the pumping start water level, the negative pressure in the vacuum tank is instantaneously applied to the suction pipe upstream of the impeller, and the horizontal axis pump automatically suctions the water level in the suction pipe. A method of operating a horizontal shaft pump characterized by pumping water up to a water level that can be drained with capacity.