JPH07145793A - Vertical shaft pump - Google Patents

Abstract

PURPOSE:To realize draining operation at a lower water level than the lowest water level without generating a harmful whirlpool by controlling the flow of a pump according to the lower water level than the lowest water level. CONSTITUTION:Preceding standby operation is conducted from a water level lower than the lowest water level WL1. The impeller 1 of a pump is arranged at a water level lower than the lowest water level WL1. An air intake pipe 10 whose other end is open to atmosphere is connected into a pump casing 4 at the lower part of the impeller 1. This connection position is set to that at the time of pump operation at the water level of the lowest water level WL1, air intake may be started from the air intake pipe 10 into the pump casing 4. As a result, when a water level becomes lower than the lowest water level WL1, the pressure inside the air intake pipe 10 becomes lower according to the lowering of the water level, and in response to this, an air intake quantity sucked into the pump casing 4 is increased, and the water raising quantity of the pump is decreased, and there becomes no rolling-in of air from a subjecting bell 3, and abnormal and noise can be prevented.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates mainly to a vertical shaft pump at a pumping station for carrying out a preceding standby operation provided for draining water discharged during rainfall, and can also be used for management operation of the pump in normal times. Regarding

[0002]

2. Description of the Related Art A conventional apparatus is disclosed in Japanese Patent Laid-Open No. 63-90697.
As described in the publication, when the water level when the pump is submerged is lower than this, an impeller is provided at a position slightly above the pump specific portion specific to the pump which corresponds to the lowest water level level for sucking air. When the water level becomes lower than the corresponding water level, there is a system in which a vacuum break breaks the water into a state of idling, which causes water to drop so that drainage operation cannot be performed.

[0003]

Generally, in order to perform the preceding standby operation based on the rainfall information or the like, in order to increase the storage effect of the water absorption tank or the drain, the drain operation is started at the lowest possible water level. However, it is effective to prevent eddies and surge phenomenon in the water absorption tank, and to make the pump operate stably.

However, the above-mentioned prior art does not consider drainage operation at a water level lower than the minimum water level, and for example, a known minimum water level of 1.4 to 1.7 times the diameter from the suction port of the suction bell. Drainage operation is not possible at water levels below the level.

The problem to be solved by the present invention is to control the flow rate of a pump in accordance with a water level lower than the lowest water level, and to enable drainage operation at a water level lower than the lowest water level without generating harmful vortices. To do.

[0006]

The vertical pump of the present invention which solves the above-mentioned problems has a water level during pumping operation that is lower than the water level corresponding to the lowest water level that sucks air from the suction bell mouth. In a vertical axis pump that performs a preliminary standby operation from a low water level, one end side is communicated with the impeller of the pump placed below the position corresponding to the minimum water level and the pump casing below this impeller and the other end side is open to the atmosphere. And a height position that allows the intake pipe to communicate with the inside of the pump casing so that intake starts from the intake pipe into the pump casing at a water level equal to or lower than the minimum water level during pumping operation of the vertical shaft pump. It is characterized by having done.

In this case, the height position at which the intake pipe communicates with the inside of the pump casing is such that the distance from the water level corresponding to the lowest water level is the loss head of the pump suction part and the velocity head part at the communication part of the intake pipe. It can be set equal to or smaller than the sum.

In any of the above cases, an intake amount adjusting valve for adjusting the intake amount of the atmosphere is provided in a part of the intake pipe, and the other end side of the intake pipe is opened to the atmosphere above the water absorption tank. It is preferably provided in a position.

Further, a pipe having one end connected to the intake pipe and the other end connected to the discharge side of the pump casing, and a valve provided on the pipe may be provided. In this case, it is preferable that a discharge valve is provided on the discharge side of the pump casing and the other end of the pipe is connected to the pump casing between the discharge valve and the impeller. Instead of this pipe, a water supply device for supplying water to the intake pipe and a pipe having one end connected to the intake pipe and the other end connected to the water supply device may be provided.

[0010]

In the pump operation, when the water level is above the minimum water level, the pressure at the position where one end of the intake pipe communicates with the pump casing (hereinafter referred to as the intake pipe communication portion) becomes atmospheric pressure or higher, so that intake is not performed. If the water level becomes lower than the minimum water level during pump operation, the pressure in the intake pipe communication part will decrease as the water level decreases, so the amount of intake air drawn into the intake pipe communication part via the intake pipe will decrease. Increase according to. The actual pumping volume of the pump decreases as the intake volume increases. In other words, if the water level decreases, the pumping volume will decrease accordingly, so that even if the water level is lower than the minimum water level, the entrainment of air from the suction bell is prevented, pumping is possible, and abnormal vibration and noise are prevented. it can.

Further, at the time of starting pumping and stopping pumping, since the pumping amount is controlled by the intake air and is less than a predetermined flow rate, abrupt pumping start and stop can be mitigated, and surge phenomenon in the water absorption tank can be mitigated, so stable operation You can

Particularly, since the height position of the communication portion of the intake pipe is set so as to start intake from the intake pipe into the pump casing at a water level equal to or lower than the minimum water level level during the pumping operation of the vertical shaft pump, Since the intake is stopped when the water level exceeds the level, it is possible to pump water with the normal pump capacity.

According to the one in which the intake pipe and the pump discharge pipe are connected by a pipe, or the one in which the water supply device is connected to the water intake pipe by a pipe, when the intake pipe or the intake pipe communicating portion is clogged with dust or the like, The dust can be removed by the pressure of the discharge water of the pump or the water supply of the water supply device, and stable operation can be secured.

[0014]

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 which is a part of the pump casing 4 is on the upper side. 5 and the discharge elbow 6 are 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. An intake hole 9 is provided near the lower part of the impeller 1, an intake pipe 10 is provided in connection with the intake hole 9, an intake amount adjusting valve 11 is provided in the intake pipe 10, and an intake port of the intake pipe 10 is provided. 12 constitutes a flow rate control device installed in the water absorption tank. The intake hole 9 is provided at a conventional minimum water level, that is, at a level below this water level, at a minimum water level WL1 for sucking air from the suction bell 3, the intake hole 9 is not inhaled. The static pressure P (m) at the intake hole 9 is expressed by the following equation.

[0016]

[Equation 1]

Here, Po: atmospheric pressure (10.3 m), Ba: saturated vapor pressure (0.3 m), L: distance from water surface to intake hole (m), hs: head loss of pump casing suction part (m) ), V: Flow velocity (m) of the handled liquid in the intake hole portion In the number 1, if the static pressure P in the intake hole 9 is larger than Po-Ba, intake is not performed. Therefore, if the relationship of the equation 2 is set, intake is not performed.

[0018]

[Equation 2]

That is, if the intake hole 9 is provided below the conventional minimum water level WL1 by the number 3 in the following equation, the water level becomes
Since intake is not performed in the range A of WL1 or more, drainage operation can be performed with a predetermined pump capacity.

[0020]

[Equation 3]

On the other hand, in the range B where the water level is lower than WL1, L decreases in the equation 1, so that 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 taken in accordance with 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 the atmospheric pressure, the intake amount is small and the flow rate of the pump is also slightly decreased. 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 decreases almost in proportion to the decrease in the water level, so P becomes smaller than atmospheric pressure, the intake amount increases, the flow rate of the pump also decreases significantly, and swirls occur even at the submersion depth S2. A flow rate that does not occur can be used. When the water level is WL4, the amount of intake air is 15% to 20% of the pump flow rate, and pumping is impossible, resulting in idling operation. The submersion depth S3 at this time is designed so that the suction bell inlet has a level such that a swirl does not occur at the flow rate immediately before the pumping is disabled. 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 at the conventional minimum water level WL1 or less, and safe operation without abnormal vibration or noise becomes possible. 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 drain 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 the surge phenomenon is alleviated by controlling the flow rate of each pump 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 a plurality of pumps can be adjusted at once. Drainage or stoppage of drainage may cause a surge phenomenon in the water absorption tank. Further, a sudden load change may adversely affect the power supply equipment.

FIG. 3 is an improved example of the example of FIG. 2. In this embodiment, the pumps have different impeller positions, and the drain start water level and the drain stop water level are different. . No. 1 pump, No. 1 2 pumps, no. Three
The drain start water level and drain stop water level of the pump are WL
51, WL41, WL52, WL42, WL53, WL
43. When water level rises to WL51 due to flooding, No. 1 pump starts draining. At this time, No. Two
No. The three pumps are still idling. When the water level further rises and reaches WL52, No. No. 2 pump starts draining and reaches No. 53 when it reaches WL53. 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 in which the water level drops, WL43 becomes No. Only 3 pumps first shift from drainage operation to idle state, and then WL42, W
As L41 and the water level dropped, No. 2 pumps, N
o. 1 Pump and shift to idle operation. 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 the self liquid when the intake pipe 10 is blocked by foreign matter such as dust will be described. The intake pipe 1 is attached to the vertical shaft pump having the structure shown in FIG.
A part of 0 and the discharge pipe 7 of the pump casing were connected by a pipe 14, and a valve 13 was provided in the pipe 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 the high pressure water of the pump is caused to flow into the intake pipe 10, so that the intake pipe 1
Foreign substances stuck in 0 can be backwashed. Although the intake pipe 10 and the discharge pipe 7 are connected by a pipe in FIG. 4, the intake pipe 10 and the discharge elbow 6 of the pump casing may be connected.

Next, with reference to FIG. 5, 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. In the vertical pump as shown in FIG. 1, a part of the intake pipe 10 and the water supply device 15 are connected by a pipe 14, and a valve 13 is 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. Therefore, the "pump suction part loss +
It is possible to perform drainage operation to a water level as low as the distance of "intake hole velocity head", and prevent vortex generation and entrainment of air from the lower end of the 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 opened 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. Further, 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 axis pumps are vertically shifted so that the draining operation start water level is made different. When the water level rises due to flooding, drainage starts one by one as the water level rises, and even when the water level drops and the machine shifts to standby operation, it also shifts to idle operation standby. Therefore, all the pumps can perform drainage operation at the same time,
Since it does not shift to idling operation standby, surge phenomenon in the water absorption tank can be prevented and load fluctuation can be reduced,
The effect is that stable operation can be performed.

According to the embodiment shown in FIG. 4, when the intake pipe is clogged with foreign matter such as dust, the pump can be backwashed with high-pressure water by operating with the discharge valve closed or squeezed. There is an effect that foreign matter in the intake pipe can be easily removed.

Further, in the embodiment shown in FIG. 5, when the intake pipe is clogged with foreign matter such as dust, high-pressure water such as fresh water is supplied from the water supply device, so that it is more reliable than the embodiment shown in FIG. Foreign substances 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, the device can be simplified.

[0032]

According to the present invention, an impeller is provided below the lowest water level, an intake hole is provided in the pump casing below the impeller, and an intake pipe is connected to the intake hole. Since the suction port of the is opened to the atmosphere, the suction flow rate of the pump can be controlled according to the water level in the water absorption tank, and as a result, vortices do not occur even at a water level lower than the conventional minimum water level level where vortices start to occur Since the drainage operation can be continued, the preceding standby operation can be stably performed.

Further, according to the present invention, since the pumping is started and stopped by the intake action, the surge phenomenon of the water absorption tank and the fluctuation of the power supply load can be alleviated.

[Brief description of drawings]

FIG. 1 is a side view showing an embodiment of a vertical shaft pump of the present invention.

FIG. 2 is a side view of an embodiment of a pumping station in which a plurality of other embodiments of the vertical shaft pump of the present invention are installed.

FIG. 3 is a side view showing a pumping station of the embodiment of FIG.

FIG. 4 is a side view showing still another embodiment of the vertical shaft pump of the present invention.

5 is a side view showing a modification of the embodiment of FIG.

[Explanation of symbols]

 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 Adjustment Valve 12 Suction Port 13 Valve 14 Pipe 15 Water Supply Device

Claims (7)

[Claims] 1. When the water level during the pumping operation is lower than that, in a vertical axis pump that performs the preceding 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, to the lowest water level level. An impeller of a pump arranged below a corresponding position, and an intake pipe having one end communicating with the inside of a pump casing below the impeller and the other end being open to the atmosphere, are provided with the above-mentioned minimum during pumping operation of the vertical pump. A vertical pump, wherein a height position is set so that the intake pipe communicates with the pump casing so as to start intake from the intake pipe into the pump casing at a water level equal to or lower than a water level. 2. The vertical pump according to claim 1, wherein
The height position for allowing the intake pipe to communicate with the inside of the pump casing is such that the distance from the water level corresponding to the lowest water level is the sum of the head loss of the pump suction part and the velocity head at the communicating part of the intake pipe. A vertical shaft pump characterized by being set equal or smaller than the sum. 3. The vertical pump according to claim 1 or 2, wherein an intake amount adjusting valve for adjusting an intake amount of atmospheric air is provided in a part of the intake pipe. 4. The vertical pump according to claim 1, wherein the other end of the intake pipe is provided at a position open to the atmosphere in the upper part of the water absorption tank. 5. A pump casing having a suction bell mouth arranged at an arbitrary distance from the bottom wall of the water absorption tank, and the water level during pump operation is equal to or lower than the lowest water level for sucking air from the suction bell mouth. An impeller provided in the pump casing below the position, an intake pipe having one end communicating with the pump casing below the impeller and the other end being open to the atmosphere, and one end communicating with the intake pipe, etc. A vertical shaft pump including a pipe whose end communicates with the discharge side of the pump casing, and a valve provided in the pipe. 6. The vertical shaft pump according to claim 5, wherein a discharge valve is provided on a discharge side of the pump casing, and the pump casing between the discharge valve and the impeller communicates the other end of the pipe. 7. A pump casing having a suction bell mouth arranged at an arbitrary distance from the bottom wall of the water absorption tank, and the water level during pump operation corresponds to the minimum water level level for sucking air from the suction bell mouth below this. An impeller provided in the pump casing below the position, an intake pipe having one end communicating with the pump casing below the impeller and the other end being open to the atmosphere, and for supplying water to the intake pipe. Vertical pump provided with the water supply device and the pipe having one end connected to the intake pipe and the other end connected to the water supply device.