JP2004339970A - Method and device for controlling pump discharge by switching siphon and pump equipment - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method and a device for controlling pump discharge by switching a siphon capable of largely changing pump discharge, simplifying pump equipment, and reducing cost and to provide the pump equipment. <P>SOLUTION: A siphon pipe 25 is connected to the discharge side of a pump 10, and a siphon breaker 27 is fitted to the siphon pipe 25. The siphon breaker 27 is opened and closed to switch between the formation and the non-formation of a siphon in the siphon pipe 25 to vary actual heads Ha and Ha1 so as to control pump discharge flow. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method and an apparatus for controlling a pump discharge flow rate by switching a siphon, and a pump facility.
[0002]
[Prior art]
Conventionally, pump equipment used in a wastewater treatment plant and the like is provided with a pump installed in a water tank on a suction side, connecting a discharge side of the pump to a water tank on a discharge side, and driving means connected to a pump shaft protruding from the upper part of the pump. By rotating the impeller, the water in the suction-side water tank is pumped to the discharge-side water tank.
[0003]
By the way, it is necessary to change the pump discharge flow rate by changing the required drain flow rate or the like. Then, in order to change the pump discharge flow rate, the operating speed of the diesel engine or the like as the driving means may be changed. However, there is no problem in changing the operating rotation speed of the driving means if the change is about 10% of the optimum rotation speed. However, if this is changed by 20% or more, the vibration becomes large and the operation becomes difficult. Inconvenience occurs. For this reason, it was difficult to significantly change the pump discharge flow rate only by changing the operation speed of the driving means. Therefore, in order to widen the range of changing the flow rate, a variable speed reducer (variable speed clutch) is interposed between the drive means and the pump to keep the operating speed of the drive means constant and to operate the pump by the variable speed reducer. A method of greatly changing the rotation speed has been used. However, there is a problem that the variable speed reducer is expensive, and the installation of the variable speed reducer complicates the equipment.
[0004]
[Problems to be solved by the invention]
The present invention has been made in view of the above points, and an object of the present invention is to provide a method and apparatus for controlling a pump discharge flow rate by siphon switching, which can drastically change a pump discharge flow rate and can simplify equipment and reduce costs. It is to provide a pump facility.
[0005]
[Means for Solving the Problems]
An invention according to claim 1 of the present invention is a method for controlling a pump discharge flow rate of a pump having a siphon pipe connected to a discharge side, wherein an actual head is changed by switching between siphon formation and non-siphon formation in the siphon pipe. And controlling the pump discharge flow rate by controlling the pump discharge flow rate by siphon switching. As described above, the pump discharge flow rate can be easily changed and controlled only by switching between siphon formation and siphon non-formation in the siphon pipe, so that an expensive driving device such as a variable speed reducer is separately required for pump discharge flow rate control. No need to install.
[0006]
The invention according to claim 2 is characterized in that the pump discharge flow rate is controlled by switching the siphon formation and the non-siphon formation in the siphon pipe to change the actual head and the pump operation speed. A method according to claim 1 for controlling a pump discharge flow rate by siphon switching. By combining the formation / non-formation of the siphon and the change of the pump operation speed as described above, it is possible to easily control the pump discharge flow over a wide range with a small change of the pump operation speed.
[0007]
According to a third aspect of the present invention, in the pump discharge flow rate control device for a pump having a siphon pipe connected to a discharge side, the pump discharge flow rate control apparatus closes when increasing the discharge flow rate of the pump and puts a siphon in the siphon pipe. A siphon-switching pump discharge flow control apparatus characterized by comprising a siphon breaker which is formed to reduce the discharge flow rate of the pump and open to break the siphon of the siphon pipe. The siphon pipe and the siphon breaker are originally installed in the pump equipment in order to prevent the backflow of water, and it is only necessary to use this, so that the equipment can be simplified and the cost can be reduced.
[0008]
According to a fourth aspect of the present invention, the pump discharge flow rate control device controls the opening and closing of the siphon breaker and the change of the operating speed of the pump so that the pump discharge flow rate becomes a predetermined flow rate. 4. The pump discharge flow control device according to claim 3, wherein the pump discharge flow control device is provided with a siphon switch.
[0009]
According to a fifth aspect of the present invention, in the pump equipment in which a siphon pipe is connected to a discharge side, a siphon is formed in the siphon pipe when increasing the discharge flow rate of the pump in the pump equipment, and the discharge flow rate of the pump is reduced. In this case, the pump equipment is provided with a pump discharge flow control device for breaking the siphon of the siphon pipe.
[0010]
The invention according to claim 6 is the pump equipment according to claim 5, wherein the pump equipment includes control means for controlling a change in the operating rotation speed of the pump.
[0011]
The invention according to claim 7 is characterized in that the pump discharge flow control device includes a pump suction side water level, a pump discharge side water level, or a pump discharge flow rate passing through the pump, or a water channel installed upstream or downstream of the pump. The pump equipment according to claim 5 or 6, wherein the flow rate of the flowing water channel is detected, and the siphon formation and the non-siphon formation in the siphon pipe are switched based on the detected value.
[0012]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 is an overall schematic configuration diagram of a pump facility according to an embodiment of the present invention. As shown in the figure, the pump equipment hangs the pump 10 on the floor 21 of the suction water tank 20, connects the siphon pipe 25 to the discharge side of the pump 10, and connects the discharge side of the siphon pipe 25 to the discharge water tank 40. It is configured. A driving means 17 is connected via a speed reducer 15 to a pump shaft 13 which is connected to an impeller (not shown) inside the pump 10 and protrudes from an upper portion of the pump 10. The driving means 17 is constituted by an engine such as a diesel engine. On the other hand, a siphon breaker (vacuum break valve) 27 is attached to the siphon pipe 25. The siphon breaker 27 includes an electric valve, a solenoid valve, and the like. One end is connected to the siphon pipe 25 and the other end is opened to the outside air, thereby introducing and shutting off air into the siphon pipe 25.
[0013]
Further, the pump equipment includes a control means 50 for controlling the discharge flow rate of the pump 10. The control means 50 inputs a water level signal from a water level sensor 41 installed in the discharge water tank 40, outputs an opening / closing signal to the siphon breaker 27, and outputs an operation speed control signal to the driving means 17. A governor is provided in the drive means 17 and is controlled so that the operation speed is constant. The operation speed is forcibly designated by the control means 50 by the input of the operation speed control signal. It is controlled so that it becomes. In this embodiment, the siphon breaker 27 and the control means 50 constitute a pump discharge flow control device.
[0014]
Next, the operation of the pump equipment will be described. Here, a case where the discharge flow rate of the pump 10 is controlled so that the water level in the discharge water tank 40 becomes constant will be described. First, the drive means 17 is driven to rotate the impeller of the pump 10 to pump water in the suction water tank 20 into the discharge water tank 40. The water level in the discharge water tank 40 is detected by the water level sensor 41, and the water level signal is input to the control means 50. The control means 50 which has input the water level signal determines whether the current water level in the discharge water tank 40 is higher or lower than the set water level. If the water level is higher, the pump discharge flow rate is reduced, and if the water level is lower, the pump discharge flow rate is increased. And outputs a control signal to the driving means 17 and / or the siphon breaker 27.
[0015]
In the present invention, the actual head is changed by switching between the siphon forming state and the non-siphon forming state in the siphon pipe 25 by the siphon breaker 27, and the pump operating flow rate is changed by the driving means 17 so that the pump discharge flow rate is changed. Is controlled so that it can be easily changed significantly. This will be specifically described below.
[0016]
FIG. 2 is an explanatory diagram of a change in the head of the pump 10 having the siphon pipe 25 when the siphon is formed and when the siphon is not formed. That is, as shown in FIG. 2A, when the siphon is formed in the siphon pipe 25 (siphon breaker 27 is closed), the actual head of the siphon-forming portion is lost, and the actual head Ha is:
Ha = discharge water level (DWL)-suction water level (SWL)
It is.
[0017]
Further, as shown in FIG. 2B, when the siphon is not formed in the siphon pipe 25 (siphon breaker 27 is open), the water pushed up by the pump 10 overflows to the upper part of the siphon pipe 25, so that the actual head Ha1 is ,
Ha1 = siphon pipe top overflow water level (EL)-suction water level (SWL)
It is.
[0018]
Therefore, when the siphon is formed and when the siphon is not formed,
Ha1-Ha = Δh
Minute head difference.
[0019]
When this is applied to the pump head curve H1 shown in FIG. 3A, a flow rate change of ΔQ1 (about 2.8 m ³ / s in this characteristic curve) can be obtained by the head difference Δh between the actual heads Ha and Ha1. You can see that. In other words, even if the pump is operated at a fixed constant rotation speed without changing the rotation speed of the pump, the discharge flow rate can be easily changed only by switching the formation and non-formation of the siphon in the siphon pipe 25 by the siphon breaker 27. Can be changed.
[0020]
Further, if the pump operation speed is slightly changed, it is possible to drastically change the pump discharge flow rate. FIG. 3B shows a head curve H1 (100%) when the pump operation speed is a normal set speed, and a head curve H1 (90%) when the pump speed is reduced by 10% from the set speed. %). That is, as can be seen from this characteristic curve, the discharge flow rate (discharge flow rate at the point a1) at the set number of revolutions (head lift curve H1 (100%)) at the time of siphon formation (actual head Ha) changes from the time of siphon non-formation (actual It can be seen that the difference ΔQ2 up to the discharge flow rate (discharge flow rate at the point a2) at the rotation speed (head curve H1 (90%)) at which the 10% rotation speed in the head Ha1) is reduced (this characteristic curve). About 6.3 m ³ / s). In general, even if the operating rotation speed of the driving unit 17 is changed by about ± 10% of the set rotation speed, a problem such as an increase in vibration of the driving unit 17 does not occur.
[0021]
That is, by controlling the driving means 17 and the siphon breaker 27 by the control means 50, the operating speed of the driving means 17 is appropriately changed within a range in which there is no problem (for example, a narrow range of about ± 10%), and at the same time, the siphon pipe 25 The formation and non-formation of the siphon are appropriately switched, thereby easily controlling the discharge flow rate in a wide range.
[0022]
The siphon pipe 25 and the siphon breaker 27 are also used for the original purpose, that is, for opening the siphon breaker 27 and breaking the siphon in order to prevent the backflow of water when the pump 10 stops.
[0023]
Incidentally, the switching between the siphon and the non-siphon may be performed by a water level or a flow rate signal. At this time, the water level includes a suction-side water level and a discharge-side water level, and the flow rates include a pump discharge flow rate and a water channel flow rate. The switching between the siphon and the non-siphon uses any of these state quantities. As a specific control method, formation / non-formation of a siphon is switched by a detection signal (state quantity) of an upper limit or a lower limit of a set value of a water level or a flow rate. As a method of measuring the pump discharge flow rate, a direct measurement method in which a flow meter is installed and measured in a water channel on the upstream or downstream side of the pump 10 or the pump, and a water level difference or a pressure difference between the suction side and the discharge side of the pump are obtained. There is an indirect measurement method that calculates and calculates a pump discharge flow rate from pump characteristics, and any method may be used. That is, for example, as in the above embodiment, (1) the pump discharge flow rate may be controlled so as to keep the water level in the discharge water tank 40 (that is, the water level on the discharge side of the pump) at a predetermined water level, or (2) suction. The pump discharge flow rate may be controlled so that the water level in the water tank 20 (that is, the water level on the suction side of the pump) is maintained at a predetermined level, or (3) the pump discharge flow rate may be controlled by directly measuring the pump discharge flow rate. Control may be performed so as to maintain a predetermined pump discharge flow rate. {Circle around (4)} Further, the flow rate of the channel flowing through the channel installed upstream or downstream of the pump may be detected, and the discharge flow rate of the pump may be controlled based on the detected value so that the channel flow rate becomes a predetermined flow rate. In the case of the water level on the discharge side as shown in (1), no siphon is formed above the set value, and the siphon is formed below. In the case of the flow rate as in (3) and (4), switching is performed such that the siphon is not formed when the flow rate exceeds the set value, and the siphon is formed when the flow rate is lower than the set value.
[0024]
Although the embodiments of the present invention have been described above, the present invention is not limited to the above embodiments, and various modifications may be made within the scope of the claims and the technical idea described in the specification and the drawings. Deformation is possible. It should be noted that any shape or structure not directly described in the specification and the drawings is within the scope of the technical idea of the present invention as long as the effects and effects of the present invention are exhibited. For example, in the above-described embodiment, the pump discharge flow rate is controlled over a wide range by controlling both the driving means 17 and the siphon breaker 27. The control of the means 17 may be omitted, and the pump operation speed may be kept constant at the set speed, and the pump discharge flow rate may be controlled only by switching between siphon formation and non-formation of the siphon pipe 25 by the siphon breaker 27.
[0025]
【The invention's effect】
According to the present invention as described in detail above, the following effects are produced.
(1) Since the pump discharge flow rate can be easily changed and controlled simply by switching between siphon formation and siphon non-formation in the siphon pipe, an expensive drive device such as a variable speed reducer is separately required for pump discharge flow control. No need to install. In particular, the siphon pipe and the siphon breaker are originally installed in the pump equipment in order to prevent backflow of water.Since it is only necessary to control the opening and closing operation of the siphon breaker as described above, it is possible to simplify the equipment. Cost reduction can be achieved.
[0026]
(2) By switching between siphon formation and non-formation in the siphon pipe and further changing the pump operating speed, it is possible to easily control a wide range of pump discharge flow rate with only a small change in the pump operating speed. Become.
[Brief description of the drawings]
FIG. 1 is an overall schematic configuration diagram of a pump facility using an embodiment of the present invention.
FIGS. 2 (a) and 2 (b) are explanatory diagrams of a change in head of a pump 10 having a siphon pipe 25 when a siphon is formed and when a siphon is not formed.
FIGS. 3A and 3B are diagrams showing a relationship between a pump head curve H1 and actual heads Ha and Ha1.
[Explanation of symbols]
Reference Signs List 10 pump 13 pump shaft 15 reduction gear 17 drive means 20 suction water tank 21 floor 25 siphon pipe 27 siphon breaker (pump discharge flow control device)
40 discharge water tank 41 water level sensor 50 control means (pump discharge flow control device)

Claims (7)

In a pump discharge flow rate control method for a pump having a siphon pipe connected to a discharge side,
A method for controlling a pump discharge flow rate by siphon switching, wherein an actual head is changed to control a pump discharge flow rate by switching between siphon formation and siphon non-formation in the siphon pipe. The siphon switching according to claim 1, wherein the actual discharge head is changed by switching between siphon formation and non-siphon formation in the siphon pipe, and the pump operation speed is changed to control the pump discharge flow rate. Pump discharge flow rate control method. In a pump discharge flow control device of a pump in which a siphon pipe is connected to a discharge side,
The pump discharge flow control device includes a siphon breaker that closes to increase the discharge flow rate of the pump and forms a siphon in the siphon pipe, and opens to reduce the discharge flow rate of the pump and breaks the siphon of the siphon pipe. A pump discharge flow control device by siphon switching. The pump discharge flow rate control device includes a control unit that controls opening and closing of the siphon breaker and changing of an operation speed of the pump so that the pump discharge flow rate becomes a predetermined flow rate. 4. The pump discharge flow control device according to claim 3, wherein the pump discharge flow rate is controlled by siphon switching. In a pump facility with a siphon pipe connected to the discharge side,
The pump equipment is characterized in that a siphon is formed in the siphon pipe when increasing the discharge flow rate of the pump, and a pump discharge flow control device that destroys the siphon of the siphon pipe when reducing the discharge flow rate of the pump is provided. And pump equipment. The pump equipment according to claim 5, wherein the pump equipment includes a control unit that controls a change in an operation rotation speed of the pump. The pump discharge flow control device detects and detects the suction-side water level of the pump, or the discharge-side water level of the pump, or the pump discharge flow rate passing through the pump, or the flow path flow rate flowing through the water path installed upstream or downstream of the pump. The pump equipment according to claim 5, wherein switching between siphon formation and non-siphon formation in the siphon pipe is performed based on a value.

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