JPH0794834B2 - Pumping station - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention mainly relates to a pump station for performing a preceding standby operation provided for draining out water during rainfall, and further to a pump management operation in normal times. Also regarding what is available.

[Conventional technology]

As described in Japanese Patent Application Laid-Open No. 63-90697, the conventional device is slightly above the pump specific portion peculiar to the pump corresponding to the minimum water level level for sucking air when the water level when the pump is submerged is below this. There is an impeller provided at a position where when the water level becomes lower than the water level corresponding to the above-mentioned minimum water level, it is made idle by a vacuum break and the water is dropped to prevent drainage operation.

[Problems to be Solved by the Invention]

Usually, in order to perform the preliminary standby operation based on rainfall information, etc., it is desirable that the drainage operation can be performed at the lowest water level because the storage effect of the water absorption tank and the pipe increases.
In addition, it is effective to prevent eddies and surge phenomenon of the water absorption tank to make the flow rate appropriate according to the water level of the water absorption tank, and the stable operation of the pump can be performed.

However, the above-mentioned prior art does not consider drainage operation at a water level lower than the minimum water level, for example, drainage operation at a body water level lower than the known minimum water level of 1.4 to 1.7 times this diameter from the suction port of the suction bell. I can't.

An object of the present invention is to enable drainage operation at a water level lower than the minimum water level without generating harmful vortices when installing a plurality of vertical pumps that perform a preceding standby operation in the same water absorption tank, and The aim is to obtain a pumping station that can mitigate the surge phenomenon in the water absorption tank due to sudden start and stop of drainage.

[Means for Solving the Problems]

The above-mentioned object is provided with an intake pipe whose one end communicates with the inside of the casing below the pump impeller and whose other end is open to the atmosphere,
If the water level during the pumping operation is lower than that, multiple vertical shaft pumps are installed in the first water absorption tank to perform the stand-by standby operation from a water level lower than the water level corresponding to the lowest water level that sucks air from the suction bell mouth. And shifting the impeller positions of the plurality of vertical pumps from each other in the vertical direction so that the drainage start water levels of the plurality of vertical pumps are different from each other, and the impellers of the vertical pumps correspond to the minimum water level level applied to each vertical pump. It is achieved by arranging below the position where

[Action]

In a vertical pump that performs a preliminary standby operation from a water level lower than the water level corresponding to the minimum water level, actual drainage starts when the water level reaches the vicinity of the impeller. Therefore, if the impellers of a plurality of vertical shaft pumps are arranged at the same level, those vertical shaft pumps start actual drainage at the same time. In this regard, according to the present invention, the impeller positions of the vertical shaft pumps are vertically shifted from each other, and the pumping start water levels of the vertical shaft pumps are different from each other, so that the pumping start when viewed from the entire suction water tank is started. Can be performed step by step in units of pumps. Accordingly, it is possible to mitigate the surge phenomenon of the water absorption tank caused by the start of draining of all the plurality of preceding standby operation pumps at the same time, and to mitigate the sudden increase in the load on the power supply equipment.

In addition, since the impeller is located below the position corresponding to the minimum water level, pumping can be started from a water level lower than the minimum water level, and the actual storage of the water absorption tank can be reduced as much as the pumping start water level decreases. The capacity can be increased, and the storage effect for a sudden increase in water such as heavy rainfall can be increased.

The problem of vortices when starting pumping from a water level lower than the lowest water level is solved by providing an intake pipe. In other words, even if the water level falls below the minimum water level at which air is sucked in from the suction bellmouth during pumping, when the air becomes below the level at which air is sucked in from the intake pipe, the amount of air that corresponds to the decrease in water level is delivered to the pump. Inhaled. This allows
Even when the pump is operated at a water level lower than the minimum water level, the amount of water pumped by the pump is reduced, and drainage that prevents vortices due to air entrainment from the suction bell mouth is possible and abnormal vibration and noise can be prevented.

On the other hand, the distance from the water level corresponding to the minimum water level to the communication part between the intake pipe and the pump casing is equal to or more than the sum of the loss head of the pump suction part and the velocity head at the communication part of the intake pipe. It is preferable to set it small. According to this, the start of intake from the intake pipe when the water level is lowered and the stop of intake from the intake pipe when the water level is raised can be realized at the minimum water level level.

〔Example〕

 Embodiments of the present invention will be described below with reference to the drawings.

In FIG. 1, the suction bell 3 of the pump casing is connected to the lower side of the casing liner 2 of the pump casing 4 accommodating the impeller 1, and the pumping pipe 5 that is a part of the pump casing 4 is provided on the upper side. The discharge elbow 6 is connected to form a vertical shaft pump. A discharge pipe 7 and a discharge valve 8 are provided on the discharge side of the discharge elbow 6. Also,
An intake hole 9 is provided near the lower part of the impeller 1, and the intake hole 9
An intake pipe 10 is provided in connection with the intake pipe 10, an intake amount adjustment valve 11 is provided in the intake pipe 10, and a suction port 12 of the intake pipe 10 is installed in a water absorption tank to form a flow rate control device. The intake hole 9 has a conventional minimum water level, that is, below this water level, the suction bell 3
It is provided at a position where air is not sucked from the suction hole 9 at the lowest water level WL1. The static pressure (P) m in the intake hole 9 is expressed by the following equation. Where Po: atmospheric pressure (10.3m), Ba: saturated vapor pressure (0.3m), l: distance from the water surface to the intake hole (m), hs: pump casing suction head loss head (m), υ: intake Velocity (m) of the liquid to be handled in the hole portion If the static pressure P in the intake hole 9 becomes larger than Po-Ba, intake is not performed. Therefore, If so, it does not inhale. Therefore, the conventional minimum water level WL
Below 1 If the intake hole 9 is provided just below, the intake is not performed in the range A where the water level is higher than WL1, so that the drainage operation can be performed with a predetermined pump capacity. In the range B where the water level is lower than WL1, l decreases in the equation, so P becomes smaller than atmospheric pressure and intake is performed. Since an appropriate amount of intake air is given by the intake air amount control valve 11, an appropriate amount of intake air is controlled according to the water level to control the flow rate. In range B, the water level is
In the case of WL2, since P is slightly lower than atmospheric pressure, the amount of intake air is small and the flow rate of the pump is also slightly reduced. In this case, since the submersion depth S1 of the pump is sufficient for the pump flow rate at this time, no vortex occurs. When the water level is WL3, P
Since it decreases almost in proportion to the drop in water level, it becomes smaller than atmospheric pressure, the intake amount increases, the flow rate of the pump also decreases significantly, and it is possible to set the flow rate so that vortices do not occur even at the submersion depth S2. it can. When the water level is WL4, the amount of intake air becomes 15% to 20% of the pump flow rate, and pumping becomes impossible, resulting in idling operation. The submersion depth S3 at this time is designed so that the suction bell inlet level is such that a vortex does not occur at the flow rate immediately before the pumping failure. In addition, the opening degree of the intake air amount control valve 11 is constant in the entire range where the water level changes. Vortices do not occur even when the water level is below the conventional minimum water level of WL1, which enables safe operation without abnormal vibration or noise. The flow rate of the pump is controlled to about half of the predetermined flow rate by intake air at a water level at which the impeller 1 is slightly submerged from idle operation to submerged operation and at a water level slightly higher than the water level WL4 at which drain operation is changed to idle operation. Therefore, there is little change in the flow rate at the start and stop of drainage, the surge phenomenon can be alleviated, and stable operation of the pump is possible.

In addition, 20 is a bottom wall of the water absorption tank.

2 and 3 show an embodiment in which a plurality of vertical shaft pumps shown in FIG. 1 are installed.

FIG. 2 shows an example in which the impeller positions of the pumps are provided at the same level. In this case, although each pump is designed to reduce the surge phenomenon by controlling the flow rate as described above, the drain start water level WL5 and the drain stop water level WL4 are the same for each pump, and the flow rate for multiple pumps is Drainage or stoppage of drainage may cause a surge phenomenon in the water absorption tank. Furthermore, there is a possibility that power supply equipment may be adversely affected by sudden load changes.

FIG. 3 is an improved example of the example of FIG. 2, and in this embodiment, each pump has different impeller positions, and the drain start water level and drain stop water level of each pump are different. The drain start water level and drain stop water level of No. 1 pump, No. 2 pump and No. 3 pump are WL51, WL41, WL52, WL42, WL respectively.
It becomes 53, WL43. The No. 1 pump starts draining when the water level rises to WL51 due to the water discharge. At this time, the No. 2 and No. 3 pumps are still idling. The water level is rising
When it reaches WL52, the No. 2 pump starts draining, and when it reaches WL53, the No. 3 pump starts draining. In this way, since the idle operation state is sequentially shifted to the drainage operation, abrupt drainage can be prevented, abrupt drop in water level does not occur, and a surge phenomenon can be mitigated. Furthermore, rapid changes in load can be avoided. On the other hand, considering the situation where the water level drops, WL43 becomes No. 3
Only the pump first shifts from the drainage operation to the idling state, and as the water level drops below WL42 and WL41, No.2 pump, No.2 pump.
1 Move to the pump and idling state. Therefore, the sudden stop of drainage can be prevented, the sudden rise of the water level does not occur, the surge phenomenon can be mitigated, and the load fluctuation can be mitigated.

As described above, since the surge phenomenon and the load fluctuation can be alleviated, stable pump operation can be performed.

Next, with reference to FIG. 4, a method of backwashing with self-liquid when the intake pipe 10 is blocked by a foreign substance such as rubber will be described. First
A part of the intake pipe 10 and the discharge pipe 7 of the pump casing are connected by a pipe 14 to a vertical pump having a structure as shown in the figure.
A valve 13 is provided on the valve 14. When the water level is equal to or higher than the draining start water level WL5, the discharge valve 8 is throttled within a range in which the prime mover of the pump does not overload. At this time, the normally closed valve 13 is opened, and high-pressure water from the pump is caused to flow through the intake pipe 10, so that the foreign matter stuck in the intake pipe 10 can be backwashed. Although FIG. 4 shows the intake pipe 10 and the discharge pipe 7 connected by a pipe, the intake pipe 10 and the discharge elbow 6 of the pump casing may be connected.

Next, a method of backwashing with tap water, treated water, filtered water or the like when the intake pipe 10 is blocked by foreign matter such as dust will be described with reference to FIG. In a vertical pump as shown in FIG. 1, a part of the intake pipe 10 and the water supply device 15 are piped.
A pipe 13 was connected to the pipe 14, and a valve 13 was provided on the pipe 14. At this time, the water level may be in any state. By feeding water from the water supply device 15, opening the normally closed valve 13, and flowing high-pressure water from the water supply device 15 into the water suction pipe 10, foreign matter in the intake pipe 10 can be backwashed.

As described above, according to the vertical shaft pump of the present invention, it is possible to automatically and appropriately intake air according to the water level, and therefore, the distance of “pump suction part loss + intake hole part velocity head” from the conventional lowest water level. Drainage movement is possible to a low water level,
Moreover, it is possible to prevent generation of vortices and entrainment from the lower end of the air suction bell. In addition, since sudden drainage start and drainage stop can be mitigated, surge phenomenon in the water absorption tank can be mitigated, and stable pump operation can be performed.

In the embodiment shown in FIG. 1, since the intake port of the intake pipe is open to the atmosphere above the water absorption tank, the odor in the water absorption tank does not leak to the atmosphere above the pump through the intake pipe, and Even if the liquid to be handled flows backward from the intake pipe due to an erroneous operation, etc., it will not leak outside.

In the embodiment shown in FIG. 3, when a plurality of pumps are installed, the positions of the impellers of the vertical pumps are shifted vertically so that the draining operation start water level is different. When the water level rises, drainage is started one by one as the water level rises, and when the water level drops and shifts to standby operation, it also shifts to idle operation standby. Therefore,
Since all pumps do not perform drainage operation at the same time or shift to idling operation standby, surge phenomenon in the water absorption tank can be prevented and load fluctuation can be reduced, so stable operation can be performed There is.

According to the embodiment shown in FIG. 4, when the intake pipe is clogged with foreign matter such as dust, it can be backwashed with high-pressure water of the pump by operating with the discharge valve of the pump closed or throttled. Moreover, there is an effect that foreign matter in the intake pipe can be removed. In the embodiment shown in FIG. 5, when the intake pipe is blocked by foreign matter such as dust, high-pressure water such as fresh water is supplied from the water supply device. It can be removed and the intake pipe can be backwashed regardless of the water level in the water absorption tank. In the embodiment shown in FIG. 4, since the intake pipe is backwashed with its own liquid, there is an effect that the device can be simplified.

[Effect of the Invention] According to the present invention, the impeller positions of the plurality of vertical shaft pumps are vertically shifted from each other, and the pumping start water levels of the plurality of vertical shaft pumps are different from each other. Pumping can be started in stages on a pump-by-pump basis. As a result, the surge phenomenon in the water absorption tank due to the sudden start of drainage can be mitigated, and the load fluctuation of the power supply equipment can be mitigated.

Moreover, when the water level drops below the level at which air is sucked in from the intake pipe, air is sucked into the pump and the amount of pumped water is substantially reduced, which prevents the generation of harmful vortices. Since the impeller is placed below the minimum water level, pumping can be started from a water level lower than the minimum water level, and the pumping start water level can be lowered, and the depth of the water absorption tank can be increased accordingly. This has the effect of reducing the size.

[Brief description of drawings]

1 to 5 are side views showing an embodiment of a pumping station of the present invention and an embodiment of a vertical pump applied to the pumping station, respectively. 1 ... Impeller, 2 ... Casing liner, 3 ... Suction bell, 4 ... Pump casing, 5 ... Pumping pipe, 6 ... Discharge elbow, 7 ... Discharge pipe, 8 ... Discharge valve, 9 ... … Intake hole, 10 …… Intake pipe, 11 …… Intake amount control valve, 12 …… Suction port, 13 …… Valve, 14 …… Pipe, 15 …… Water supply device.

Claims (2)

[Claims] 1. A suction pipe, one end of which communicates with the other end of which is open to the atmosphere, is provided in the casing below the pump impeller, and when the water level during pumping operation is lower than that, air is sucked from the suction bell mouth. A plurality of vertical pumps that perform a preliminary standby operation from a water level lower than the water level corresponding to the lowest water level are installed in the same water absorption tank, and the impeller positions of the plurality of vertical pumps are vertically shifted from each other, and A pumping station, characterized in that the drainage starting water levels of the vertical shaft pumps are different from each other, and the impellers of the plurality of vertical shaft pumps are arranged below a position corresponding to the lowest water level level. 2. The pumping station according to claim 1, wherein the distance from the water level corresponding to the lowest water level to the communicating portion between the intake pipe and the pump casing is the loss head of the pump suction part and the intake pipe. 2. A pumping station, characterized in that it is set to be equal to or smaller than the sum of velocity heads at the communication part of.