JP2539059B2 - Estimating inflow rate of filtration tank of water purification plant - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial field of application) [0001] The present invention relates to an apparatus for estimating a flow rate into a filter basin of a water purification plant.

(Prior Art) A water purification plant equipped with a self-cleaning rapid filtration basin generally has a system as shown in FIG. That is, the raw water is first stored in the settling tank 1, the impure wastes are settled there, the settling water is guided to the filter tank 3 through the settling water channel 2, the impure wastes are further filtered there, and the filtered water is purified water through the filtered water channel 4. Send to pond 5. A settling tank inflow flow meter 6 for measuring the flow rate flowing into the settling tank 1 and a total filtration flow meter 7 for measuring the total filtration flow rate are provided.
Further, the self-cleaning water 8 is made to flow backward from the filtered drain 4 to each of the filtration basins 3 and is discharged to the drainage basin 9. In addition, 10
Is the sludge discharged from the sludge discharge port provided in each sedimentation tank 1.

In such water purification plants, in recent years, as a method of controlling water quality, chemicals such as chlorine and caustic such as bactericidal agents and neutralizing agents are injected at a preset ratio (injection rate) to the settling water that flows into the filter basin. Then, the medium chlorine treatment method for controlling the water quality has been adopted.

(Problems to be solved by the invention) However, in a water purification plant equipped with such a self-cleaning rapid filtration basin, conventionally, there is no way to estimate the flow rate of the settling water flowing into the filtration basin during the filtration basin cleaning process. Since it is not provided, the flow rate into the filter basin, which is the target flow rate for injection, cannot be accurately measured when chemicals are injected, and it is not possible to accurately inject chemicals at the ratio set for the target flow rate. There was a problem.

That is, as shown in FIG. 3, the inflow flow rate 11 of the filtration basin of the water purification plant flows into the filtration basin 3 from the sedimentation basin 1 through the open channel of the sedimentation basin 2, so it is possible to directly measure the inflow flow rate of the filtration basin. Can not. However, with chemical injection control, the flow rate into the filter basin
It is necessary to inject chlorine and chemicals such as chlorine at the ratio specified for 11.

Therefore, it is necessary to estimate the inflow flow rate of the filtration basin from the flow rate of another place and inject the chemicals at a predetermined ratio.
The method of using the indicated value of 1 and the method of using the indicated value of the total filtration flow meter 7 can be considered.

However, in the former method using the indicated value of the settling tank inflow meter 6, a part of the settling tank inflow rate is consumed by the sludge 10 of the settling tank 1, and there are multiple settling tanks for maintenance of the settling tank 1. When water is filled in any one of the settling basins of No. 1, part of the inflow rate of the settling basin may be consumed due to the water filling. In such a case, the instruction of the settling basin inflow meter 6 is indicated. There was a problem that the value did not match the flow rate 11 into the filter and the chemical injection rate could not be accurately controlled to match the flow rate of the filter.

Further, the latter method using the indicated value of the total filtration flow meter 7 has the following problems. In other words, in the self-cleaning gravity filter, the self-cleaning water (backwash water) during cleaning of the filter
Since 8 is supplied from the filtered water conduit 4, the indicated value Q of the total filtration flow meter 7 sharply decreases during self-cleaning as shown in FIG. Therefore, the indicated value Q of this total filtration flow meter 7
If is used as it is as the flow rate into the filter, the chemical injection amount is actually lower than the required amount, and there is a problem that the chemical treatment cannot be performed sufficiently.

The present invention has been made in view of such conventional problems, and it is a filter tank of a water purification plant that can inject chemicals at an appropriate ratio corresponding to the actual inflow rate of the filter tank even during cleaning of the filter tank. An object is to provide an inflow flow rate estimation device.

[Structure of the Invention] (Means for Solving the Problems) A filter basin inflow rate estimation device of a water purification plant according to the present invention includes a filter basin equipped with a self-cleaning device, and a total filter for measuring a total filtration flow rate from the filter basin. Filtration flow rate measuring means, measurement signal opening / closing means for opening / closing the total filtration flow rate measurement signal from the total filtration flow rate measuring means in response to the self-cleaning signal from the self-cleaning device, and chemicals according to the total filtration flow rate measurement value. A chemical injection control means for controlling the injection amount and a total filtration flow rate measurement value from the total filtration flow rate measurement means are input and stored via the measurement signal opening / closing means, and a self-cleaning signal from the self-cleaning device is stored. When it is off, the total filtration flow rate measurement value from the total filtration flow rate measurement means is given to the chemical injection control means, and when the self-cleaning signal from the self-cleaning device is turned on and the measurement signal opening / closing means is opened. Is the total filtration flow rate measurement value stored that a measurement value storage means for providing to the chemical injection control unit by the time the.

(Operation) In the filter basin inflow flow rate estimation device of the water purification plant of the present invention, the total filtration flow rate is measured by the total filtration flow rate measuring means, and the measured value is given to the measured value storage means via the measurement signal opening / closing means. , Remember.

The measurement signal opening / closing means is closed when the self-cleaning signal of the self-cleaning device installed in the filtration pond is off, and the total filtration flow rate measurement value from the total filtration flow rate measurement means is input to the measurement value storage means and stored. Then, when the self-cleaning signal is ON, the signal is opened and the input of the total filtration flow rate measurement value from the total filtration flow rate measurement means to the measurement value storage means is stopped.

Then, the measurement value storage means gives the chemical injection control means the total filtration flow rate measurement value from the total filtration flow rate measurement means as it is when the measurement signal opening / closing means is closed, and the measurement signal opening / closing means opens. Sometimes I try to give the last measured value of total filtration flow rate that I remember.

Thus, even when the filtration tank is undergoing self-cleaning and the total filtration flow rate measurement value drops sharply, it is estimated that the flow rate into the filtration tank is almost equal to the total filtration flow rate before the start of self-cleaning. The amount of chemicals corresponding to the flow rate is injected into the filter, and the amount of chemicals corresponding to the actual flow rate into the filter is injected.

(Embodiment) An embodiment of the present invention will be described below in detail with reference to the drawings.

FIG. 1 shows an embodiment of the present invention. The sedimentation basin 1, sedimentation basin 2, filtration basin 3, filtration basin 4, washing basin 5 and total filtration flowmeter 7 are of the conventional construction shown in FIG. Is similar to.

In this embodiment, in addition to the above components, a chemical injection control device 12 and a chemical injection device 13 for injecting a predetermined amount of chemical into the settling water culvert 2 and a chemical injection control device.
A filter basin inflow rate estimating device 14 for giving an estimated filter basin inflow rate to 12 and a filter basin cleaning controller 15 for controlling the filter basin cleaning are provided.

Then, the filter basin inflow flow rate estimation device 14 stores a switch 17 which opens and closes in response to a filter basin cleaning signal 16 from the filter basin cleaning control device 15 and a total filtration flow rate measurement value 18 to the total filtration flow rate meter 7. It is composed of a flow rate measurement value storage device 19.

Next, the operation of the filter basin inflow rate estimation device of the water purification plant having the above configuration will be described.

The switch 17 of the filter basin inflow rate estimation device 14 is controlled to be opened and closed by a filter basin cleaning signal 16 output from the filter basin cleaning controller 15. The signal 16 during washing of this filter is shown in Fig. 2 (a).
As shown in, when any one of the filtration basins 3 connected so that the filtered water flows into the total filtration flow meter 7 is in the cleaning state, the output is output from the filtration basin cleaning control device 15. It

The total filtration flow meter 7 measures the total filtration flow rate 18 as shown in FIG. 2 (b) because the total filtration flow rate flowing into the water purification pond 5 decreases when any one of the filtration basins 3 is undergoing self-cleaning. Is input to the total filtration flow rate storage device 19 via the switch 17.

The total filtration flow rate storage device 19 is, as shown in FIG.
Switch 17 is closed and flow rate measurement value from total filtration flow meter 7
When 18 signals are input, the measured value 18 is used as it is as the estimated flow rate 20 of the inflow of the filter, and the chemical injection control device 12
When one of the filtration basins 2 is being washed and the switch 17 is opened, and the total filtration flow meter 7 does not input the total filtration flow rate measurement value 18, the last value stored and stored until then The total filtration flow rate measurement value is held and given to the chemical injection control device 12 as a filtration pond inflow flow rate estimated value 20.

The chemical injection control device 12 calculates the chemical injection amount target value 22 using the following formula based on the set and input chemical injection rate target value 21 and the filter pond inflow flow rate estimated value 20, and
Output to 13.

The chemical injector 13 injects an amount of chemical corresponding to the chemical injection target value 22 to the actual flow rate 11 of the filter basin as shown in FIG.

(Chemical injection amount) = (Chemical injection rate set value) × (Estimated value of flow rate into filter) In this way, the total flow rate is used as the flow rate into the filter, and if the filter is undergoing self-cleaning, the cleaning is performed. By keeping the total filtration flow rate immediately before the start as the flow rate into the filtration pond that flows into the filtration pond even during cleaning, the total filtration flow rate that decreases sharply during self-cleaning can be used, but it is almost It is possible to inject an appropriate amount of chemicals.

[Effects of the Invention] As described above, according to the present invention, the total filtration flow rate is used as the inflow rate of the filtration basin, and if any of the filtration basins is undergoing self-cleaning, the total filtration flow rate immediately before the self-cleaning starts. Since the amount of chemicals injected is controlled by holding the flow rate into the filter basin, the total filtration flow rate that decreases rapidly during self-cleaning is estimated to be the flow rate into the filter basin if it is a self-cleaning rapid filtration basin. Even when the chemicals are injected by using the same, the chemicals can be injected at an inflow rate almost commensurate with the actual inflow rate of the filtration basin, and the chemicals can be injected accurately.

[Brief description of drawings]

FIG. 1 is a system diagram of an embodiment of the present invention, FIG. 2 is a signal waveform diagram of each part of the above embodiment, FIG. 3 is a system diagram of a general water treatment plant, and FIG. It is a measurement signal waveform diagram of a filtration flow meter. 1 ... Sedimentation tank, 2 ... Sedimentation basin 3 ... Filtration basin, 4 ... Filtration basin 5 ... Purification basin, 7 ... Total filtration flow meter 11 ... Filtration basin inflow, 12 ... Chemical injection control device 13 …… Chemical injector 14 …… Filtration tank inflow flow rate estimation device 15 …… Filtration tank cleaning control device 16 …… Filtration tank cleaning signal 17 …… Switch, 18 …… Total filtration flow rate measurement value 19 …… Total filtration flow rate Storage device 20 …… Estimated flow rate into the filtration tank 21 …… Target value of chemical injection rate 22 …… Target value of chemical injection rate

Claims (1)

(57) [Claims] 1. A filtration basin equipped with a self-cleaning device, a total filtration flow rate measuring means for measuring a total filtration flow rate from the filtration basin, and a total filtration flow rate measurement upon receiving a self-cleaning signal from the self-cleaning device. Measurement signal opening / closing means for opening / closing a total filtration flow rate measurement signal from the means, chemical injection control means for controlling the chemical injection amount according to the total filtration flow rate measurement value, and total filtration flow rate measurement from the total filtration flow rate measuring means The value is input and stored through the measurement signal opening / closing means, and when the self-cleaning signal from the self-cleaning device is off, the total filtration flow rate measurement value from the total filtration flow rate measuring means is stored in the chemical injection control means. When the self-cleaning signal from the self-cleaning device is turned on and the measurement signal opening / closing means is opened, the total filtration flow rate measurement value stored by that time is given to the chemical injection control means. An apparatus for estimating a flow rate into a filter basin of a water purification plant, comprising a value storage means.