JP4864185B2 - Operation method of water supply equipment - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a water supply apparatus, and more particularly to a water supply apparatus that supplies water such as tap water to an apartment house or a building using a pump.
[0002]
[Prior art]
FIG. 1 shows a configuration example of a water supply device of a type directly connected to a general water main. This water supply apparatus includes a pump 11, pressurizes water flowing in through an inflow pipe 12 directly connected to a main water pipe or the like with the pump 11, and supplies water to a water tap of a consumer at the end from the discharge pipe 13. Do. A check valve 15 is disposed on the discharge side of the pump 11 to prevent back flow of water when the pump is stopped. Further, a pressure tank 16 is provided to accumulate the water pressurized by the pump 11 so as to avoid frequent starting and stopping of the pump. A pressure sensor 17 for detecting the pressure on the discharge side of the pump is provided in the vicinity of the pressure tank of the discharge pipe 13, and the pressure signal detected here is transmitted to the control panel 19 and used for operation control of the pump.
[0003]
Similarly, the inflow pipe 12 is also provided with a pressure sensor 18 on the pump inflow side, and this signal is transmitted to the control panel 19 for use in controlling the operation of the pump. The control panel 19 includes an inverter device, and supplies a variable frequency / voltage to the pump 11 to arbitrarily control the rotation speed of the pump 11. Accordingly, the pressure on the pump discharge side is detected by the pressure sensor 17, and the pump discharge side pressure is controlled to the target pressure value by changing the rotation speed of the pump so that the pump discharge side pressure becomes constant. it can. The control panel 19 selects and starts / stops the operation target pump, detects various abnormal signals such as an abnormal temperature of the pump, and issues an alarm.
[0004]
The water supply device is provided with a flow switch 20 that detects an extremely small amount of water, and this signal is transmitted to the control panel 19. When the flow switch 20 detects an extremely small amount of water, the control panel 19 receives the signal and accumulates pressure in the pressure tank 16 by operating the pump for a certain period of time, and then has a so-called small water amount stop function for stopping the operation of the pump. ing. This function can prevent frequent start and stop of the pump when the amount of water used is extremely reduced at night and the like, and can also prevent idling of the pump. As such a small water volume stop operation, the pump stops at the same pressure at the time of detecting an extremely small water volume, and when the discharge side pressure drops by a predetermined value from the target pressure after stopping, the pump is started again, or before the small water volume stoppage Then, once the discharge pressure of the pump is increased and accumulated in the pressure tank, the pump is stopped, and the pump is restarted when the pressure on the discharge side decreases by a predetermined value from the target pressure.
[0005]
By the way, when supplying tap water or the like, generally, a water meter is attached and the amount of water used is measured. When such a water supply device is used as a directly connected water supply device directly connected to a water main, a water meter 21 is attached to the inflow pipe of the water supply device, and a water meter 22 is attached to each consumer. May be used. The water meter 21 attached to the inflow side of the water supply device is attached to, for example, a 40 mmφ pipe in order to measure the total amount of water supplied. On the other hand, water supplied from the discharge pipe 13 is distributed and supplied to each door at the end of the consumer. A water meter 22 is attached to a pipe of, for example, 20 to 25 mmφ in each of these doors. In this way, when the total amount of water used is measured on the inflow side of the water supply device and the total amount of water used in each water meter 22 of each pipe branched to the discharge side of the water supply device is compared, the amount of water is extremely small. It is known that when used continuously for a long time, there may be a difference in the accumulated water amount between the two. This phenomenon occurs when the accumulated water volume on the inflow side is larger than the total accumulated water volume on the discharge side, and is related to the above-described operation for stopping the small water volume, and is called a water meter overrun phenomenon. For example, in a relatively small-scale water supply device, the amount of usage of the water meter 22 provided on the consumer side is changed from the water meter 21 provided on the inflow side without installing the water meter on some consumers. Problems may arise when calculating the amount of water used by consumers without water meters by subtracting the total.
[0006]
[Problems to be solved by the invention]
This invention is made | formed in view of the situation mentioned above, and it aims at providing the water supply apparatus which can reduce the excessive phenomenon of the water meter which concerns, and can accumulate | store the amount of used water correctly.
[0007]
[Means for Solving the Problems]
The present invention provides a pump, a pressure tank connected to the discharge pipe of the pump, a pressure sensor for detecting the pressure on the discharge side of the pump, and a control panel including an inverter device for controlling the rotational speed of the pump; An operation method of a water supply apparatus comprising a metering device for metering water flowing into the pump, pressurizing the water metered by the metering device using the pump, and sending the water to an end consumer, The water supply device has a small water volume stop function for accumulating pressure in the pressure tank when the amount of water used becomes extremely small, and then stopping the operation of the pump, and the water supply device discharges the pump when the low water volume is stopped. when accumulated in the pressure tank was elevated to a discharge pressure of the pump over a period of 3 seconds in the case of raising the 5 to 7 m water head in the water supply device over-advanced symptoms to the water meter Yes, at the time of the small water stoppage The water supply device is characterized in that the head of the pump discharge pressure is increased to 3 m or less, and the time for increasing the discharge pressure of the pump is set to 30 seconds or more to suppress the excessive phenomenon of the water meter. This is the driving method.
[0008]
It is considered that the overrun phenomenon of the water meter occurs due to a sudden change in the flow rate on the inflow side during the operation of stopping a small amount of water. For this reason, by setting various conditions of the water supply device so as to gently change the flow rate on the inflow side during the operation of stopping the small amount of water, it becomes possible to alleviate the excessive phenomenon of the water meter and reduce it. . According to such a water supply apparatus, even when a water meter is provided on the inflow side, the amount of occurrence of the over-travel phenomenon is small, so that it can be used with confidence.
[0009]
Used in a state where water amount is extremely reduced, the small amount of water stopping operation is performed, for accumulating the water in more or less tank, change of the pulse-shaped inflow occurs. It is considered that the overrun phenomenon of the water meter is caused by the change in the inflow amount in the pulse form, and it is possible to reduce the over advance phenomenon by reducing the occurrence frequency.
[0010]
Another aspect exemplary embodiment of the present invention is to be that to reduce the capacity of the pressure tank for accumulating the time of low water stopped. As a result, the amount of change in the pulsed inflow that occurs when the small amount of water stops is reduced, so that the overrun phenomenon of the water meter can be reduced.
[0011]
In this onset bright, when accumulator during low water stopped, the upper boosting small cities, and / or Ru slowly increased. Thereby, the rapid change of the inflow amount at the time of the stop of the small water amount can be similarly prevented, and the excessive phenomenon of the water meter can be reduced.
[0012]
Further, in a preferred embodiment of the present invention, prior to Kisukuna water when it stopped after the pump start-up of, to set a longer acceleration time of the soft start. Thereby, the rapid change of the inflow amount at the time of the operation for stopping the small amount of water can be eased similarly, and the overrun phenomenon of the water flow device can be reduced.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. FIG. 1 shows a configuration example of a water supply apparatus which is a premise of the embodiment of the present invention, and the configuration of each device is as described above. FIG. 2 is a diagram illustrating the discharge pressure, the flow rate, and the like during the operation of stopping a small amount of water.
[0014]
First, the overrun phenomenon of the water meter does not occur during the normal operation of the pump. It is known that this occurs in a time zone in which the amount of water used is extremely reduced, such as at night, and is accompanied by a small water amount stop operation. In FIG. 2, when the discharge flow rate and the inflow flow rate up to the time t1 coincide with each other, these water amounts are the same and no particular problem occurs. When this flow rate is lower than the flow rate at which the pump stops the small amount of water, it becomes a problem when it continues for a long time.
[0015]
For example, when the flow switch 20 is operated at a speed of about 10 L / min or less, the operation for stopping a small amount of water starts after a predetermined detection time has elapsed. In this case, at time t1, the pump speed is set to 0 and the pump is stopped. However, since the water flow continues at the consumer end, although the water flow continues, this water is supplied with the water accumulated in the pressure tank 16, and the discharge flow rate does not change. The discharge side pressure detected by the pressure sensor 17 gradually decreases as shown in the figure. When the pump starting pressure p1 is reached, the pump is started by a soft start. After the pump stops at time t1, the inflow rate becomes zero, but when the pump starts, the inflow rate suddenly increases. However, since the end consumer side is almost closed, the pressure tank is mainly accumulated.
[0016]
The pump is started and the rotational speed is increased to ensure the pressure on the discharge side.At this time, the pressure tank accumulates more than the required flow rate on the discharge side, and the amount of water on the inflow side increases. At this time, the discharge pressure overshoots the predetermined pressure p2. For this reason, the inflow rate once becomes zero until time t3 after accumulating in the pressure tank, and becomes a steady state with the recovery of the overshoot state. The pump is operated at a predetermined rotational speed, and the discharge flow rate and the inflow rate are the same even though the amount of water is extremely small. Operation is continued in this state. Therefore, it is considered that the impeller of the water meter idles due to inertia due to the pulse-like change of the inflow flow rate during the operation of stopping the small amount of water, and the overtravel phenomenon occurs.
[0017]
3 to 6 show various means for reducing such over-travel phenomenon. FIG. 3 shows a result of reducing the occurrence frequency of the small water amount stop operation. FIG. 3 (a) shows the occurrence frequency of the conventional small water amount stop operation, and FIG. 3 (b) shows the small water amount stop operation in the improved state. Indicates the frequency of operation. As described above, the overrun phenomenon of the water meter is caused by the operation of stopping the small amount of water. Therefore, by reducing the frequency of occurrence, the amount of overrun of the water meter can be reduced in proportion thereto. To reduce the frequency of occurrence of this low water volume stop operation, it is confirmed that the low water volume stop state continues even after a lapse of a predetermined time after the flow switch first detects that the water volume is low. Since it enters the state, the frequency of the low water quantity stop operation can be lowered by lengthening the set time of the detection timer. In addition, the delay timer is operated so as to operate for a certain period even if the low water amount state is detected again when the pump is restarted after the low water amount is stopped. Similarly, by increasing the set time of the delay timer, the frequency of occurrence of the low water volume stop operation can be reduced. FIG. 3 (b) shows a case where the small water amount stop operation frequency is reduced to about half by such measures.
[0018]
FIG. 4 shows a case where the pressure tank is reduced. In FIG. 4A, it is assumed that the size of the conventional pressure tank 16 is about 20 L, for example. In this case, the inflow flow rate is pulsed as described above. FIG. 4B shows a case where the capacity of the pressure tank 16 is reduced to about 10 L, for example. By doing in this way, as shown in FIG.4 (b), the height of the pulse of an inflow flow rate can reduce, and, thereby, the excessive phenomenon of a water meter can be reduced.
[0019]
FIG. 5 shows a case where the pressure accumulation operation is performed by further pressurizing after the detection of the small water amount stop water amount. In the figure, a dotted line indicates a conventional method, and a solid line indicates an embodiment of the present invention. When the pressure accumulation operation is started at time t1, the rotational speed of the pump 11 is increased, and conventionally, the discharge pressure of about 5 to 7 m of water head is increased in about 3 seconds, and the operation for a predetermined time is continued. At this time, since the water is accumulated in the pressure tank 16, the inflow rate flows in a pulse shape as shown in FIG. In the embodiment of the present invention, the upper pressure increase during the pressure accumulation operation is reduced to about 3 m. Then, the pressure accumulation is performed slowly. For example, the discharge pressure is increased slowly over about 30 seconds, for example, compared to the conventional increase over about 3 seconds. Thus, even if it raises slowly, since it is a state in which almost no water is used on the consumer side, there is almost no influence on the consumer side. By doing in this way, as shown in FIG.5 (b), the peak of the inflow flow rate pulse becomes low, thereby reducing the excessive phenomenon of the water meter. Note that lowering the upper pressure increase during the pressure accumulation operation and slowly increasing the discharge pressure during the pressure accumulation operation may be performed independently, or both may be used in combination.
[0020]
FIG. 6 shows a countermeasure by setting a longer acceleration time when the pump is restarted after stopping a small amount of water. In the figure, a dotted line indicates a conventional method, and a solid line indicates a method according to this embodiment. A small amount of water is detected by the flow switch 20, and at the time t1 after the operation for a predetermined time has elapsed, the pump speed is set to zero and the pump operation is stopped. Then, the discharge pressure gradually decreases, and when the pressure reaches p1, the pump is restarted. The increase in pump speed at this time has conventionally been, for example, about 1 second as indicated by the dotted line in the figure. The increase time until the pump speed reaches the target discharge pressure is increased to about 3 seconds as shown by the solid line in the figure. By doing so, the peak of the pulse is remarkably reduced as shown in the flow rate of the inflow accumulated in the tank when the pump is restarted, and the steady state is continuously obtained. This significantly reduces the overrun phenomenon of the water meter. Note that the discharge pressure smoothly reaches the target discharge pressure without causing overshoot. Since the discharge flow rate is supplied from the pressure tank 16 to the end consumer side even when the pump is stopped, a constant amount is supplied regardless of the operation stop state of the pump. It should be noted that the overshoot phenomenon of the water meter can be effectively prevented by eliminating the overshoot of the discharge pressure at the time of starting the pump in this way, but the PI control gain of the pump operation speed control system is reduced, or the integral value As a result of measures such as increasing the pressure, the pump can be restarted smoothly as well.
[0021]
Although the example of a countermeasure for suppressing the excessive phenomenon of various water meters has been described above, it is needless to say that the excessive phenomenon can be further suppressed by using a combination or modification thereof.
[0022]
【Effect of the invention】
As described above, according to the present invention, in a water supply apparatus directly connected to a water main or the like, even when a water meter is installed on the inflow side thereof, the overrun phenomenon of the water meter is prevented. Accurate accumulation of water usage is possible.
[Brief description of the drawings]
FIG. 1 is a diagram showing an outline of a water supply apparatus.
FIG. 2 is a diagram showing a discharge pressure, a discharge flow rate, an inflow flow rate, and a pump speed, respectively, during a small water amount stop operation.
FIGS. 3A and 3B are diagrams showing the frequency of occurrence of a low water volume stop operation, where FIG. 3A shows a conventional example, and FIG. 3B shows an embodiment of the present invention.
FIGS. 4A and 4B are diagrams showing an inflow rate during a small water volume stop operation, where FIG. 4A shows a case where a pressure tank of a conventional normal size is employed, and FIG. 4B shows a small capacity of an embodiment of the present invention. The case where the pressure tank is adopted is shown.
FIG. 5 is a diagram showing (a) discharge pressure and (b) inflow rate at the time of stopping a small amount of water. The dotted line in the figure shows the conventional upper pressure increase and speed accumulation operation, and the solid line in the figure shows the present invention. The upper pressure increase and speed accumulation operation of the example embodiment are shown.
FIG. 6 is a graph showing discharge pressure, discharge flow rate, inflow flow rate, and pump speed when a small amount of water is stopped. The dotted line in the figure shows an example of acceleration time when restarting a conventional pump, and the solid line in the figure. These show the example of the acceleration time at the time of the pump restart of the embodiment of this invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 11 Pump 12 Inflow pipe 13 Discharge pipe 15 Check valve 16 Pressure tanks 17 and 18 Pressure sensor 19 Control panel 20 Flow switch 21 Inflow side water meter 22 Consumer side water meter

Claims (2)

A pump, a pressure tank connected to a discharge pipe of the pump, a pressure sensor for detecting a pressure on the discharge side of the pump, a control panel including an inverter device for controlling a rotation speed of the pump, and the pump An operation method of a water supply device comprising a metering device for metering inflowing water, pressurizing the water metered by the metering device using the pump, and sending the water to an end user,
The water supply device has a small water amount stop function for accumulating pressure in the pressure tank when the amount of water used becomes extremely small, and then stopping the operation of the pump,
The water supply apparatus, when accumulated in the pressure tank by increasing the discharge pressure of the pump when the low water stop, when raising the 5 to 7 m water head over the discharge pressure of the pump 3 seconds, A water supply device in which a overrun phenomenon occurs in the water meter;
To suppress the overrun phenomenon of the water meter by setting the head of the pressure increase of the discharge pressure of the pump at the time of stopping the small amount of water to 3 m or less and the time for increasing the discharge pressure of the pump to 30 seconds or more. A method for operating a water supply device. The water supply device is a water supply device in which an overtravel phenomenon occurs in the water meter when the soft start acceleration time is 1 second when the pump is started after the small amount of water is stopped.
The operation method of the water supply apparatus according to claim 1, wherein an acceleration time of the soft start is set to 3 seconds or more to suppress an overtravel phenomenon of the water meter.

Images