JP2020011175A - Chemical injection device - Google Patents

Abstract

To provide a chemical injection device used in a water treatment system, which can easily detect a degree of deterioration of a chemical to be injected.SOLUTION: There is provided a chemical injection device 6 used in a water treatment system 1. The chemical injection device 6 includes: a chemical tank 7 for storing chemical; a temperature detector 11 for detecting a temperature around the chemical tank 7 and/or a temperature of the chemical in the chemical tank 7; a deterioration degree calculation unit 12 that calculates a degree of deterioration of the chemical in a predetermined period based on a temperature detection result; and an alarm unit 13 that issues an alarm when an integrated value of the degree of deterioration from the start of storage of the chemical in the chemical tank 7 exceeds a first threshold.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a drug injection device.

  BACKGROUND ART Conventionally, as a water treatment system that generates treated water from raw water such as well water, a technology including an iron removing manganese removing device that removes iron and manganese contained in raw water on a water supply line is known (for example, Patent Document 1). The technology described in Patent Literature 1 discloses that, in order to oxidize iron contained in raw water to an insoluble iron compound (iron (III) hydroxide hydroxide or the like) on the upstream side of the iron removing / manganese removing apparatus, the raw water has hypochlorite. Add sodium acid. Then, the insoluble iron compound is removed by filtering through a filter medium of the iron removing and manganese removing device. In addition, manganese contained in the raw water supplied to the iron removal manganese removal device, when contacted with the filter medium of the iron removal manganese removal device, the oxidation proceeds due to the action of sodium hypochlorite, is adsorbed by the filter material, Removed.

JP 2011-173101 A

  Injection of sodium hypochlorite into raw water is usually controlled by comparing the residual chlorine concentration in treated water with a reference value. However, if sodium hypochlorite stored in the chemical tank deteriorates over time before the sodium hypochlorite is injected into the water treatment system using the chemical injection pump from the chemical injection device, It is necessary to increase the input amount of sodium chlorite, but with this increase, the amount of chloric acid generated by the decomposition of sodium hypochlorite also increases, and the chloric acid concentration (0.4 mg / L or less).

  Accordingly, there is a need for a method that can easily detect the degree of deterioration of sodium hypochlorite injected into a water treatment system. This is not limited to sodium hypochlorite, and there is a need for a method that can easily detect the degree of deterioration of a chemical injected into a water treatment system.

  An object of the present invention is to provide a drug injection device used in a water treatment system, which can easily detect the degree of deterioration of a drug to be injected.

  The present invention is a chemical injection device used in a water treatment system, and a chemical liquid tank for storing a chemical liquid, and a temperature detecting unit for detecting a temperature around the chemical liquid tank and / or a temperature of the chemical liquid in the chemical liquid tank. And a deterioration degree calculation unit that calculates the degree of deterioration of the chemical solution during a predetermined period based on the temperature detection result, and an integrated value of the degree of deterioration from the start of storage of the chemical solution in the chemical solution tank, A warning unit that issues a warning when the value exceeds a threshold value of 1.

  Further, the chemical solution contains sodium hypochlorite, and the alarm unit determines that the value obtained by subtracting the integrated value of the degree of deterioration from the effective chlorine concentration of the chemical solution at the time of starting the storage is lower than a second threshold value. It is preferable to issue an alarm in the event of a failure.

  Further, it is preferable that the deterioration degree calculating section calculates the deterioration degree using a deterioration degree coefficient per unit period and per unit temperature, which differs depending on an effective chlorine concentration of the chemical solution.

  In addition, it is preferable that the chemical dosing device of the present invention further includes a history storage unit that stores information relating to a chemical dosing history of the chemical solution to a line included in the water treatment system.

  ADVANTAGE OF THE INVENTION According to this invention, it becomes possible to provide the chemical | medical-feeding apparatus used in a water treatment system, and can detect easily the degree of deterioration of the chemical | medical-agent to which chemical | medical-pouring is performed.

It is a figure showing an example of the whole lineblock diagram of the water treatment system provided with the chemical dosing device concerning the embodiment of the present invention. FIG. 3 is a functional block diagram of the medicine injection device according to the embodiment of the present invention. It is a graph which shows the example of transition of the effective chlorine concentration with respect to the elapsed days after storing the chemical | medical solution containing sodium hypochlorite in a chemical | medical solution tank according to temperature. It is a graph which shows the example of change of the attenuation ratio of the effective chlorine concentration with respect to the elapsed days after storing the chemical | medical solution containing sodium hypochlorite in a chemical | medical solution tank according to temperature. It is a graph which shows the example of a transition of the degree of deterioration of a medicine with respect to the number of days elapsed after storing a medicine containing sodium hypochlorite in a medicine tank for each temperature. It is a graph which shows the example of change of the maximum injection rate of chlorine with respect to the elapsed days after storing the chemical | medical solution containing sodium hypochlorite in a chemical | medical solution tank according to temperature and initial concentration.

[1 Configuration of water treatment system]
Hereinafter, an overall configuration of a water treatment system including a drug device according to the present invention will be described with reference to the drawings.
FIG. 1 is an overall configuration diagram of a water treatment system 1 according to the present embodiment. As shown in FIG. 1, the water treatment system 1 according to the present embodiment includes a pressure pump 2, an inverter 3, a filtration device 4 as an iron removal manganese removal device, and a water storage tank 5.

  Further, the water treatment system 1 includes a chemical injection device 6 including a chemical injection pump 8 as a chlorinating agent supply unit, a discharge amount checker 9, a residual chlorine meter 10 as a residual chlorine concentration measuring unit, a control device 100, Is provided. In FIG. 1, the path of the electrical connection is indicated by a broken line.

  Further, the water treatment system 1 includes a primary water supply line L1, a secondary water supply line L2, and a medicine supply line L3. The “line” in this specification is a general term for lines such as a flow path, a path, and a pipe through which a fluid can flow.

  In the present specification, “primary water supply” refers to water supplied to a water tank having a required amount of retained water and water to which a chlorine agent solution is supplied. Further, the “secondary water supply” refers to water that is sent from the water tank unit and that is a target of measurement of the residual chlorine concentration. In the present embodiment, as described later, the processing tank provided in the filtration device 4 as a fresh water generator is positioned as a water tank unit.

  The primary water supply line L1 is a line that supplies the primary water supply W1 to the filtration device 4. The upstream end of the primary water supply line L1 is connected to a supply source (groundwater, industrial water, river water, etc.) of the primary water supply W1. The downstream end of the primary water supply line L <b> 1 is connected to the primary water supply inlet of the filtration device 4.

  The pressurizing pump 2 is a device that draws in the primary feed water W1 and discharges it to the filtering device 4. The pressurizing pump 2 is electrically connected to an inverter 3 (described later). The driving power whose frequency is converted is supplied from the inverter 3 to the pressurizing pump 2. The pressurizing pump 2 is driven at a rotation speed according to the frequency of the supplied driving power (hereinafter, also referred to as “driving frequency”).

  The inverter 3 is an electric circuit that supplies the frequency-converted driving power to the pressure pump 2. Inverter 3 is electrically connected to control device 100. A current value signal is input to the inverter 3 from the control device 100. Inverter 3 outputs driving power of a driving frequency corresponding to the input current value signal to pressurizing pump 2.

  The filtration device 4 as a device for removing iron and removing manganese is a facility that removes impurities contained in the introduced primary feed water W1 to produce a secondary feed water W2. The filtering device 4 includes a processing tank for storing a filtering material (not shown). This treatment tank has a required amount of retained water due to the presence of the void portion and the free board portion of the filter medium, and thus can be referred to as a water tank portion. The impurities contained in the primary feed water W1 include, in addition to those originally contained in the primary feed water W1 (eg, colloid particles), dissolved substances (eg, ferrous ions) in the primary feed water W1, and hypochlorite. There is a product (for example, ferric hydroxide) produced by a reaction with an acid salt solution (chlorinating agent solution). Note that manganese ions are hardly oxidized only by the hypochlorite solution charged in the primary feed water W1, and thus are removed by contact oxidation with a catalyst supported on a filter medium.

  The secondary water supply line L2 is a line for sending the secondary water W2 produced in the treatment tank (water tank section) of the filtration device 4 to a demand destination (not shown). The upstream end of the secondary water supply line L2 is connected to the secondary water supply outlet of the filtration device 4. The downstream end of the secondary water supply line L2 is connected to a demand destination (or a post-processing device) of the secondary water supply W2.

  The water storage tank 5 is a facility for temporarily storing the secondary water W2 produced by the filtration device 4. The water storage tank 5 is provided near the downstream side of the filtration device 4 in the secondary water supply line L2. The secondary water supply W2 stored in the water storage tank 5 is sent out to the demand destination via the secondary water supply line L2.

  The chemical injection device 6 is a device for injecting a chemical into the primary water supply line L1. The chemical injection device 6 includes a chemical liquid tank 7 and a chemical injection pump 8.

  The chemical tank 7 is a tank for storing a chlorinated solution as a chemical. In the present embodiment, the chlorinating agent solution is a hypochlorite solution represented by a sodium hypochlorite solution. The hypochlorite solution also serves as an oxidizing agent for oxidizing iron, manganese, and ammonia nitrogen contained in the primary feed water W1, and as a bactericide such as fungi. Note that the chlorinating agent solution is merely an example. Hereinafter, an example in which the chemical solution is a chlorinating agent solution will be described, but the aspect of the present embodiment is not limited to this.

  The chemical injection pump 8 is a device that supplies the chlorinated solution stored in the chemical liquid tank 7 to the primary water supply line L1 via the chemical supply line L3. The chemical injection pump 8 is provided adjacent to the chemical liquid tank 7. The chemical injection pump 8 is composed of, for example, a diaphragm pump that reciprocates the diaphragm by electromagnetic driving force. The chemical injection pump 8 is electrically connected to the control device 100. The operation of the diaphragm pump in the chemical injection pump 8 is controlled by a pulse signal transmitted from the control device 100. That is, every time a pulse signal is input from the control device 100, the chemical infusion pump 8 supplies a preset amount of the chlorinant solution from the chemical solution tank 7 to the primary water supply line L1.

  The drug supply line L3 is a line that connects between the drug solution tank 7 and the primary water supply line L1. The upstream end of the drug supply line L3 is connected to the drug injection pump 8. The downstream end of the drug supply line L3 is connected to the primary water supply line L1 at a connection J2. The connection part J2 is arranged between the connection part J1 and the filtration device 4 in the primary water supply line L1. A discharge amount checker 9 is provided on the medicine supply line L3.

  The discharge amount checker 9 is a device that detects the flow of the chlorine agent solution in the medicine supply line L3. The discharge amount checker 9 is provided between the liquid medicine tank 7 and the connection portion J1 on the medicine supply line L3. The discharge amount checker 9 is electrically connected to the control device 100. The discharge amount checker 9 transmits a detection signal to the control device 100 when detecting the flow of the chlorine solution in the medicine supply line L3.

  The residual chlorine meter 10 is a device that measures the residual chlorine concentration of the secondary feedwater W2 at the outlet side of the filtration device 4. Residual chlorine meter 10 is connected to secondary water supply line L2 at connection J2. The connection part J2 is disposed between the filtration device 4 and the water storage tank 5 in the secondary water supply line L2. The residual chlorine meter 10 is electrically connected to the control device 100. The residual chlorine concentration of secondary water W2 measured by residual chlorine meter 10 (hereinafter, also referred to as “measured residual chlorine concentration value SP”) is transmitted to control device 100 as a detection signal.

  In the present embodiment, the residual chlorine meter 10 is a continuous measurement type (for example, a polarographic electrode type) residual chlorine meter. During the operation of the water treatment system 1, the residual chlorine meter 10 always outputs a transmission signal of 4 to 20 mA to the control device 100 as a detection signal.

  The control device 100 is configured by a microprocessor (not shown) including a CPU and a memory. The control device 100 controls each unit constituting the water treatment system 1 described above. Further, an integrated timer unit (hereinafter, also referred to as “ITU”) (not shown) for managing time measurement and the like is incorporated in the microprocessor constituting the control device 100.

  The control device 100 controls each unit constituting the water treatment system 1 of the present embodiment. As shown in FIG. 1, the control device 100 is electrically connected to, for example, an inverter 3, a chemical injection pump 8, a discharge amount checker 9, a residual chlorine meter 10, and the like.

[2 Configuration of chemical dosing device]
FIG. 2 shows a functional block diagram of the medicine injection device 6.
The chemical injection device 6 includes the temperature detection unit 11, the deterioration degree calculation unit 12, the alarm unit 13, and the history storage unit 14 in addition to the chemical liquid tank 7 and the chemical injection pump 8 as described above. The chemical tank 7 and the chemical injection pump 8 are the same as the chemical tank 7 and the chemical injection pump 8 shown in FIG.

The temperature detection unit 11 detects the temperature around the chemical liquid tank 7 (particularly the air temperature) and / or the temperature of the chemical liquid in the chemical liquid tank 7.
When the temperature detection unit 11 detects the temperature around the chemical solution tank 7, the temperature detection unit 11 may be installed on a side surface of the chemical solution tank 7, for example. Accordingly, the temperature detection unit 11 can be hardly corroded by the chemical solution, and the possibility that the detection temperature changes depending on the detection location can be reduced.
Further, when the temperature detecting unit 11 detects the temperature of the chemical in the chemical tank 7, the temperature of the chemical is directly detected, so that the detected temperature and the temperature around the chemical tank 7 are compared. Therefore, the correlation with the degree of deterioration of the chemical solution increases.

The deterioration degree calculator 12 calculates the degree of deterioration of the chemical solution during a predetermined period based on the result of the temperature detection by the temperature detector 11. In particular, when the chemical liquid is a chemical liquid containing sodium hypochlorite, the deterioration degree calculating unit 12 is a deterioration degree coefficient per unit period and per unit temperature, as shown in a specific example in an example described later, The degree of deterioration can be calculated using a degree of deterioration coefficient that varies depending on the effective chlorine concentration of the chemical solution.
The deterioration degree calculating unit 12 may calculate the deterioration degree based on, for example, a table of the deterioration degree coefficient for each temperature stored in the storage unit (not shown) of the chemical dosing device 6.

  The alarm unit 13 issues an alarm when the integrated value of the degree of deterioration calculated by the degree of deterioration calculation unit 12 from the start of storage of the liquid medicine in the liquid medicine tank 7 exceeds a threshold value. In particular, when the chemical solution is a chemical solution containing sodium hypochlorite, the alarm unit 13 calculates the deterioration degree calculated by the deterioration degree calculation unit 12 from the effective chlorine concentration at the start of storing the chemical solution in the chemical solution tank 7. It is possible to issue an alarm when the value obtained by subtracting the integrated value of is smaller than the second threshold value.

  The history storage unit 14 detects information related to the drug injection history of the drug to the primary water supply line L1 included in the water treatment system 1, for example, the amount of the drug injected by the drug injection pump 8, the date and time of the injection, and the temperature detection unit 11 detects It stores history information such as the temperature of the chemical solution to be performed.

  By having the above-described configuration, the chemical dosing device 6 calculates the degree of deterioration of the chemical for a predetermined period based on the temperature around the chemical tank 7 and / or the temperature of the chemical, and the integrated value of the degree of deterioration exceeds the threshold. If an alarm occurs, an alarm is issued.

[3 Example]
Hereinafter, an example of the present embodiment will be described with reference to FIGS.
FIG. 3 is a graph showing an example of a change in the effective chlorine concentration with respect to the number of days elapsed after storing a chemical solution containing sodium hypochlorite in the chemical solution tank 7 for each temperature. FIG. 4 is a graph showing an example of a transition of the attenuation ratio of the effective chlorine concentration with respect to the number of days elapsed after storing the drug solution containing sodium hypochlorite in the drug solution tank 7 for each temperature. FIG. 5 is a graph showing an example of a transition of the degree of deterioration of the chemical with respect to the number of days elapsed after storing the chemical containing sodium hypochlorite in the chemical tank 7 for each temperature. FIG. 6 is a graph showing an example of transition of the maximum chlorine injection rate with respect to the number of days elapsed after storing a drug solution containing sodium hypochlorite in the drug solution tank 7 for each temperature and initial concentration.

  In FIG. 3, the triangles indicate the transition of the available chlorine concentration with respect to the elapsed days when the average daily temperature fluctuates between 19 ° C. and 28 ° C. The circles indicate the transition of the available chlorine concentration with respect to the number of elapsed days when the average daily temperature is mainly 20 ° C. The square marks indicate the transition of the available chlorine concentration with respect to the number of elapsed days when the average daily temperature is mainly 30 ° C. In any case, the effective chlorine concentration of the chemical at the start of the storage in the chemical tank 7 is 12%.

  In any case, the effective chlorine concentration decreases as the number of days after storing the drug solution in the drug solution tank 7 elapses. This is due to the deterioration of sodium hypochlorite in the chemical solution.

  Also, comparing the degree of decrease in effective concentration due to the level of the average temperature, the higher the average temperature in one day, the higher the degree of decrease in the effective chlorine concentration, that is, the degree of deterioration of sodium hypochlorite.

  In the graph shown in FIG. 3, the effective chlorine concentration decreases almost linearly and monotonously in the case of the circle, the triangle, and the square, but this is merely an example, Not limited. For example, the available chlorine concentration may monotonically decrease in a relatively large range while the elapsed days are relatively short, and may decrease monotonically in a small range after the elapsed days become longer.

  When the allowable effective chlorine concentration is, for example, 8.40 as shown by the dashed line in FIG. 3, in the case where the average daily temperature is mainly 30 ° C., the elapsed days have reached 6 days. At this point, the effective chlorine concentration is at the limit of the allowable range, so that sodium hypochlorite needs to be injected.

FIG. 4 is a graph obtained by converting the vertical axis of the graph of FIG. 3 into an attenuation ratio corresponding to the initial value of the effective chlorine concentration. Here, the damping ratio is calculated by the following equation.
Initial value conversion attenuation ratio on day N (%) = (effective chlorine concentration (%) on day N / effective chlorine concentration (%) of chemical solution when storage in chemical solution tank 7 is started) × 100・ (Equation 1)

  In FIG. 4, the initial value-converted attenuation ratio = 70% is shown by a dashed line as an allowable line of the initial value-converted attenuation ratio, corresponding to the effective chlorine concentration of 8.40% in FIG.

  In FIG. 4, similarly to FIG. 3, in the case of the circle, the triangle, and the square, the initial value conversion attenuation ratio monotonically decreases almost linearly. In the case where the average daily temperature is mainly 30 ° C, the initial value-converted attenuation ratio becomes the limit of the allowable range when the number of elapsed days reaches 6 days. Therefore, it is necessary to inject sodium hypochlorite. Become.

FIG. 5 is a graph obtained by converting the vertical axis of the graph of FIG. 4 into a chemical deterioration degree corresponding to the initial value conversion attenuation ratio. Here, the chemical deterioration degree is calculated by the following equation.
Degree of chemical deterioration on day N (%) = 100−initial value converted attenuation ratio on day N (%) (Equation 2)

  In FIG. 5, the degree of chemical deterioration = 30% is shown by a dashed line as an allowable line of the degree of chemical deterioration, corresponding to the initial value converted attenuation ratio = 70% in FIG.

  In FIG. 5, unlike FIG. 3 and FIG. 4, the degree of chemical deterioration monotonically increases almost linearly in the case of circles, triangles, and squares. In the case where the average daily temperature is mainly 30 ° C., the degree of chemical deterioration reaches the limit of the allowable range when the number of elapsed days reaches six days, and therefore, chemical injection of sodium hypochlorite is required.

In the examples of FIGS. 3 to 5, in the case where the average temperature per day is mainly 20 ° C., the concentration of sodium hypochlorite which was 12% on the 0th day was increased to 9.5% after 10 days. Therefore, the degree of deterioration of the effective chlorine concentration per day is (12-9.5) /10=0.25 (%).
On the other hand, in the case where the average daily temperature is mainly 30 ° C., the concentration of sodium hypochlorite, which was 12% on day 0, becomes 6% after 10 days, so that the effective chlorine concentration per day The degree of deterioration is (12-6) /10=0.60 (%).
As a result, the deterioration degree coefficient per day and the difference in average temperature per 1 ° C. is (0.60−0.25) / (30−20) = 0.035 (/ day · ° C.).

The deterioration degree calculation unit 12 uses the deterioration degree coefficient 0.035 (/ day · ° C.)
Degree of deterioration on day N = (average temperature on day N−20 ° C.) × 0.025 + 0.25 (formula 3)
Is calculated.

The alarm unit 13 calculates the effective chlorine concentration (%) on the Nth day by subtracting the integrated value of the degree of deterioration from 12%, which is the effective chlorine concentration on the 0th day. Specifically, assuming that the effective chlorine concentration after N days has passed is Y _N (%),
Y _N = Y _N−1 − (N-day deterioration degree) (expression)
Becomes
When this Y _N falls below the permissible line indicated by a chain line in FIG. 3, the alarm unit 13 to alarm an alarm.

  In addition, when sodium hypochlorite is injected by the injection device 6 when the alarm unit 13 issues an alarm, as described above, with an increase in the amount of sodium hypochlorite to be injected, It should be noted that the amount of chloric acid generated by the decomposition of sodium hypochlorite also increases, and may exceed the standard of chloric acid concentration (0.4 mg / L or less) specified by the Water Supply Law.

FIG. 6 shows the maximum chlorine injection rate with respect to the number of days elapsed since the storage of sodium hypochlorite in the chemical solution tank 7 for each initial concentration of sodium hypochlorite.
As the number of days since the storage of sodium hypochlorite in the chemical solution tank 7 has elapsed, the chloric acid generated by the decomposition of sodium hypochlorite has been accumulated, so that the maximum amount of chlorine that can be injected is The injection volume decreases monotonically.
Also, comparing the same storage temperature graphs, the higher the effective chlorine concentration of sodium hypochlorite at the start of storage, the more chloric acid generated by the decomposition of sodium hypochlorite is accumulated. The maximum chlorine injection that can be performed is lower.
Also, comparing the graphs in which the effective chlorine concentration by sodium hypochlorite at the start of storage is the same, the higher the storage temperature, the more chloric acid generated by the decomposition of sodium hypochlorite is accumulated. The maximum chlorine injection that can be performed is lower.

[4 Effects of the present embodiment]
According to the above-described medicine injection device 6, for example, the following effects can be obtained.
The chemical dosing device 6 calculates the degree of deterioration of the chemical solution in a predetermined period based on the temperature detection unit 11 that detects the temperature around the chemical solution tank 7 and / or the temperature of the chemical solution in the chemical solution tank 7 and the temperature detection result. And a warning unit 13 that issues a warning when the integrated value of the degree of deterioration from the start of storage of the chemical in the chemical tank 7 exceeds a first threshold value.

  The degree of deterioration can be determined by a simple method of calculating the degree of deterioration of the chemical solution for a predetermined period based on the temperature around the chemical solution tank 7 and / or the temperature of the chemical solution, and the integrated value of the degree of deterioration is determined by a threshold value. By issuing an alarm when the number exceeds the limit, it is possible to execute measures such as replacing the chemical stored in the chemical tank at an appropriate timing.

  Further, in the chemical injection device 6, the chemical solution contains sodium hypochlorite, and the alarm unit 13 sets the value obtained by subtracting the integrated value of the degree of deterioration from the effective chlorine concentration of the chemical solution at the start of storage as the second threshold value. An alarm is issued when the value falls below the limit.

  If the chemical contains sodium hypochlorite, take measures such as replacing the chemical in the chemical tank based on an alarm before the concentration of chloric acid in the treated water exceeds the standard specified by the Water Supply Law. It is possible to execute.

  In the chemical dosing device 6, the deterioration degree calculating unit 12 calculates the deterioration degree using a deterioration degree coefficient per unit period and per unit temperature, which differs depending on the effective chlorine concentration of the chemical solution.

  By using an appropriate deterioration degree coefficient according to the effective chlorine concentration of the chemical stored in the chemical tank, the degree of chloric acid contained in the treated water is determined by the Water Law by calculating the degree of deterioration more accurately. The risk of exceeding the standard can be reduced more reliably.

  In addition, the chemical dosing device 6 further includes a history storage unit 14 that stores information related to a chemical dosing history of a chemical to a line included in the water treatment system 1.

  As an example, by recording history information such as a medicine injection amount, a date and time of a medicine injection, and a temperature of a chemical solution, it becomes possible to manage the medicine injection based on these history information.

[5 Modifications]
In the above embodiment, the chemical infusion device 6 injects sodium hypochlorite into the water treated by the filtration device 4 as the iron removing and manganese removing device, but is not limited thereto. For example, the chemical injection device 6 may perform chemical injection into the water storage tank 5 based on the residual chlorine concentration in the water storage tank 5.

  Further, in the water treatment system 1 provided with the chemical infusion device 6, the filtration device 4 is described as being a device for removing iron and removing manganese, but is not limited thereto. For example, the filtering device 4 may be a sand filtering device.

  In addition, some of the components included in the drug injection device 6, for example, the deterioration degree calculation unit 12 and the alarm unit 13 may be included in the control device 100 instead of the drug injection device 6.

REFERENCE SIGNS LIST 1 Water treatment system 4 Filtration device 5 Water storage tank 6 Chemical injection device 7 Chemical liquid tank 8 Chemical injection pump 9 Discharge amount checker 10 Residual chlorine meter 11 Temperature detection unit 12 Deterioration degree calculation unit 13 Alarm unit 14 History storage unit 100 Chemical injection device

Claims (4)

A chemical dosing device used in a water treatment system,
A chemical tank for storing the chemical;
A temperature detector that detects the temperature around the chemical solution tank, and / or the temperature of the chemical solution in the chemical solution tank,
Based on the temperature detection result, a deterioration degree calculation unit that calculates the degree of deterioration of the chemical solution in a predetermined period,
An alarming unit that issues an alarm when the integrated value of the degree of deterioration from the start of storage of the liquid medicine in the liquid medicine tank exceeds a first threshold value. The chemical solution contains sodium hypochlorite,
2. The alarm unit according to claim 1, wherein the alarm unit issues an alarm when a value obtained by subtracting the integrated value of the degree of deterioration from the effective chlorine concentration of the chemical solution at the time of the storage start falls below a second threshold. 3. Injection device as described.   The medicine according to claim 2, wherein the deterioration degree calculation unit calculates the deterioration degree using a deterioration degree coefficient per unit period and a unit temperature, which differs depending on an effective chlorine concentration of the chemical solution. Note device. The chemical dosing device according to any one of claims 1 to 3, further comprising a history storage unit that stores information relating to a chemical dosing history of the chemical solution to a line included in the water treatment system.

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