JPH03293093A - Potable water sterilizing device - Google Patents

Abstract

PURPOSE:To stably maintain the chlorine concn. of potable water at all times in an adequate range even if the quality of city water fluctuates by controlling the quantity of the electricity to be supplied to the chlorine generating electrodes in accordance with the detected value of the chloride ion concn. and detected value of the electrical conductivity of the potable water so as to maintain the residual chlorine concn. of the potable water after chlorine sterilization in a prescribed range. CONSTITUTION:A pair of the chlorine generating electrodes 6 and a sensor 14 for detecting the chloride ion concn. are installed in the water of a water reservoir 2 and further, an electrical conductivity measuring cell 7 for detecting the electrical conductivity of the city water is installed at the intermediate point of a water feed piping 1. The chlorine generating electrodes 6 are connected via an energization control section 9 to a DC power source 8. This sterilizing device is so constituted as to detect the chloride ion concn. and electrical conductivity of the potable water and to variably control the quantity of the electricity to be supplied to the chlorine generating electrodes 6 in accordance with the C(Cl<->)/EC derived from the detected values thereof, by which the chlorine concn. of the potable water is maintained at all times in the correct range without being affected by the fluctuation in the quality of the potable water.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a drinking water sterilization device used by being incorporated into a drinking water supply system of a cup-type beverage vending machine, for example.

[Conventional technology]

In the above-mentioned cup-type beverage vending machine, the tap water supplied from the tap is stored in a water reservoir inside the aircraft, and from there it is distributed to various parts of the aircraft as water for manufacturing various drinks, water for making ice for the ice machine, etc. I have to.

On the other hand, in vending machines, the Food Sanitation Act requires that the drinking water stored in the water reservoir inside the machine be sterilized.

By the way, the tap water that is distributed from the water supply station to the demand end generally contains chlorine in the order of o, tpp-, but the above-mentioned vending machines generally pass the water supplied from the tap through an activated carbon filter. Since the water is introduced into the water reservoir, much of the chlorine contained in tap water is reduced and removed during the process of passing through the activated carbon filter.Furthermore, tap water is stored in the water reservoir for a long time. If the water is left untreated, the chlorine in the water may self-decompose, and the residual chlorine concentration of the water in the water reservoir will decrease, and if left untreated, the sterilizing ability will be lost.

For this reason, in vending machines, the drinking water stored in the water reservoir is sterilized again on the machine.
In addition to chemical addition methods and ozone sterilization methods, chlorine sterilization methods using electrolysis of tap water have recently been put into practical use in some areas.

This chlorine sterilization method uses chlorine ions (
This method makes effective use of chlorine ions (which themselves have no sterilizing ability), electrolyzes tap water, anodizes the chlorine ions, generates chlorine, and uses this chlorine to sterilize drinking water. Specifically, a pair of chlorine generating electrodes that apply a DC voltage are installed in the water of a water reservoir, and electricity is applied to these electrodes to electrolyze the water. As a result, the chlorine ions contained in the tap water lose electrons through anodic oxidation and are converted to chlorine, making the drinking water again contain chlorine and have sterilizing power. Note that the amount of chlorine generated in this case is proportional to the amount of electricity applied to the chlorine generating electrode, which is given by the voltage 9, the current 9, and the energization time.

On the other hand, if the drinking water stored in the water reservoir of a vending machine has a low chlorine concentration, it will not have sufficient sterilization effect, and if the chlorine concentration is too high, the characteristic odor of chlorine will be too strong and affect the flavor of the drink. spoil. Therefore, conventional technology takes this point into consideration, and when installing a vending machine, the quality of tap water (chlorine ion concentration, etc.) is determined at the site.

Based on the frequency of beverage sales in the vending machine, the chlorine generating electrode energization conditions (applied voltage 2 energizing current) were set at the time of installation of the vending machine in order to obtain an appropriate chlorine concentration in drinking water.

The sterilizer is operated under these energization conditions to sterilize drinking water.

[Problem to be solved by the invention]

However, if the conventional technology described above remains as it is, the following problems remain in actual operation. In other words, the quality of tap water (chlorine and chloride ion concentration) is not always constant, and the results of water quality surveys of local tap water throughout the year have confirmed that it fluctuates considerably depending on the time of day. .

For this reason, even if the energizing conditions of the chlorine generating electrode are adjusted appropriately when installing a vending machine as mentioned above, it is difficult to maintain the chlorine concentration of drinking water at a predetermined value if there is a change in the quality of tap water. Sometimes, the chlorine concentration becomes too low to provide sufficient disinfection, or conversely, the chlorine concentration becomes too high, causing problems such as the drinking water smelling like chlorine.

The present invention has been made in consideration of the above points, and an object of the present invention is to provide a drinking water sterilization device that can always stably maintain the chlorine concentration of drinking water within an appropriate range even when the quality of tap water changes. do.

[Means to solve the problem]

In order to solve the above problems, the sterilizing device of the present invention includes a means for detecting the electrical conductivity of drinking water, a means for detecting the chlorine ion concentration of drinking water, a means for controlling the amount of electricity supplied to the chlorine generating electrode, The amount of electricity supplied to the chlorine generating electrode shall be controlled based on the detected value of chlorine ion concentration and the detected value of electrical conductivity of the drinking water so as to maintain the residual chlorine concentration of the drinking water after sterilization within a predetermined range. do.

Furthermore, although it is desirable that the chlorine ion concentration detecting means described above uses a small ion-sensitive field effect transistor (ISFET) as a sensor since the electrode can be omitted, a glass electrode may also be used.

In addition, the electrical conductivity detection means in the above is implemented by installing an electrical conductivity cell as an independent component in the water supply waterway and connecting an electrical conductivity meter to this, and also using a chlorine generating electrode as a measuring electrode. It is also possible to detect the electrical conductivity of the beverage by connecting an electrical conductivity meter to the electrode.

Furthermore, instead of using the electrical conductivity meter, the amount of electricity supplied to the chlorine generating electrode may be controlled based on the current/voltage values obtained from the measured values of the current supplied to the chlorine generating electrode and the voltage between the electrodes. You can also do it.

Further, in order to cope with variations in the temperature of drinking water, it is preferable to correct the detected electrical conductivity value to the electrical conductivity at a reference temperature, and control the amount of electricity to be supplied based on this corrected value.

[Effect]

The amount of chlorine generated when tap water is electrolyzed is expected to vary depending on the chlorine ion concentration and electrical conductivity of the tap water. For this reason, when we electrolyzed samples of synthetic water whose chloride ion concentration and electrical conductivity were adjusted to various ratios under conditions of constant current and continuous current flow while continuously passing water through a water reservoir, we found that the electrical conductivity was If it was not constant, even if the chlorine ion concentration increased, the amount of chlorine generated did not increase proportionally, but on the contrary sometimes decreased. However, when the electrical conductivity was constant, as the chlorine ion concentration increased, the amount of chlorine generated also increased proportionally. However, in actual tap water, the electrical conductivity is constant and only the chlorine ion concentration does not change, so the amount of chlorine generated is the value obtained by dividing the chlorine ion concentration by the electrical conductivity (hereinafter referred to as C (cL->/E
C).

Therefore, from the relationship shown in Figure 5, the chloride ion concentration and electrical conductivity of drinking water supplied from the tap are detected, and the drinking water is adjusted according to the increase or decrease in C(CL-)/EC determined from the detected values. By variable control of the energization conditions of the chlorine generating electrode for electrolysis (energizing current 9 energizing time, etc.), even if the quality of tap water changes, the residual chlorine concentration in water sterilized with chlorine generated by electrolysis can be reduced. It can always be maintained within an appropriate range.

The reason why the amount of chlorine generated is determined by C(cL->/EC) is as follows.

If the electrical conductivity derived from chlorine ions is EC (cL), then Ctct-1/EC= a xECtet-,/E
Ca: Can be expressed as a proportionality coefficient. In tap water electrolysis, the reactions that generate oxygen and chlorine compete with each other at the anode, so the current flowing between the electrodes is considered to be the sum of the currents flowing during the two reactions. Here, the current flowing due to the chlorine generation reaction and E
C<cl, -s is proportional to the current flowing between the electrodes and EC
is considered to be proportional. Therefore, E C(cL −1
/EC can be considered as the ratio of the current that contributes to chlorine generation to the current flowing between the electrodes. That is, when electrolysis is performed with a constant current, E C (cL-)
/E By determining C, in other words, C(c
By determining L)/EC, the amount of chlorine generated is automatically determined.

In addition, when sterilizing drinking water by installing a chlorine generating electrode in the water reservoir in the machine for the above-mentioned cup-type beverage vending machine, it is important to consider the sterilization effect, the flavor of the drinking water, and the supply system from the water reservoir. Considering the amount of chlorine consumed in the piping route leading to the end, the chlorine concentration in the water in the water reservoir should be set to 0.4 to 1.
/I! It is preferable to maintain the temperature within the range of .

In addition, as means for detecting the electrical conductivity of drinking water, in addition to installing an electrical conductivity cell in the water supply pipe leading to the water reservoir and connecting an electrical conductivity meter to this cell, there are also methods for detecting the electrical conductivity of drinking water. The generating electrode is also used as an electrode for measuring electrical conductivity, an electrical conductivity meter is connected to the electrode, and the electrical conductivity of drinking water is detected by the electrical conductivity meter by switching the circuit to the DC power source for electrolysis. You can also do it.

Furthermore, instead of using the electrical conductivity meter described above, the current and interelectrode voltage of the chlorine generating electrode during electrolysis of drinking water are measured, and the current/voltage value obtained from these measurements is calculated as the electrical conductivity of the drinking water. It can also be used as an alternative value for degree.

Note that when measuring the electrical conductivity of drinking water using a chlorine generating electrode installed in a water reservoir as described above, the area of the electrode immersed in water may affect the measured value of electrical conductivity. Therefore, the measurement of electrical conductivity shall be carried out under the condition that the water level of the water reservoir is adjusted to a constant level.

Furthermore, the electrical conductivity of drinking water changes depending on the water temperature. Therefore, the temperature of drinking water is monitored with a temperature sensor, and the electrical conductivity determined by the electrical conductivity detection means is set to a reference temperature (for example, 25°C).
By correcting the electrical conductivity to , and then controlling the amount of electricity to be energized to the chlorine generating electrode based on this correction value, it is possible to control the chlorine concentration with higher accuracy.

〔Example〕

1 to 4 show drinking water sterilizers according to different embodiments of the present invention.

In each figure, 1 is the water supply pipe connected to the water supply, 2 is the water reservoir installed inside the vending machine, 3 is the water supply valve on the tap water introduction side, 4 is the activated carbon filter, and 5 is the drawer from the water reservoir 2 inside the drawer machine. These are the water distribution pipes installed between the end of the vending machine and the drinking water supply system of the vending machine.

Here, the tap water supplied from the tap is filtered through activated carbon filter 4.
The water is stored in the water reservoir 2 via the water reservoir 2, and from there it is distributed to the ice maker, carbonator, cup, etc. onboard the aircraft in accordance with sales operations. Further, as the water level in the water reservoir 2 decreases to the lower limit level as sales progress, the water supply valve 3 opens and tap water is replenished, and the water level recovers to the upper limit level again.

In the embodiment shown in FIG. 1, a drinking water supply system having such a configuration is equipped with a pair of chlorine generating electrodes 6 and a sensor 14 for detecting chlorine ion concentration in the water of the water reservoir 2, and a water supply pipe 1 in the middle of the water supply pipe 1. A self-conductivity measuring device is installed to detect the electrical conductivity of water. Here, the chlorine generating electrode 6 is connected to a DC power source 8 via an energization control section 9.

The sensor 14 for detecting the chloride ion concentration uses a small ion-sensitive field effect transistor (ISFET) that can omit electrodes, and the signal from the ion-sensitive field effect transistor (ISFET) is sent to the amplifier 1.
5 to the energization control section 9. In addition, the electrical conductivity self-container has a built-in pair of measurement electrodes.
The detection signal is given to the energization control section 9 via the electrical conductivity meter 10. Furthermore, the energization control section 9 is a timer.

C (C1-1
It has a function of adjusting and controlling the amount of electricity supplied to the chlorine generating electrode 6 based on /E C.

Specifically, for example, the control unit 9 is equipped with a microcomputer, and the drinking water C (cL-
Based on the relationship data between 1/E C and the amount of chlorine generated, calculate the appropriate residual chlorine concentration in drinking water after chlorine sterilization by comparing it with the detected value of C (cL-1/E C) in drinking water. 0,4
The amount of chlorine generated, that is, the conditions for energizing the chlorine generating electrode 6, is controlled so as to maintain the amount of chlorine generated (in the range of 1.about.1.about.1/l).

In other words, due to changes in tap water quality, C(cL-)/
When the E C detection value increases, the amount of electricity energized by the chlorine generating electrode 6, that is, the energization time 1 energizing current, etc., is reduced in accordance with the increase, and conversely, the C (cL-1/E C detection value decreases). If this occurs, the amount of electricity supplied is controlled to be increased.

As a result, it is not affected by fluctuations in the quality of tap water.
Always keep the chlorine concentration of the drinking water stored in the water reservoir 2 within an appropriate range (0.000
．． 4 to 1/1).

FIG. 2 shows an applied embodiment of the present invention.

The embodiment shown in Fig. 1 shows an example in which the electrical conductivity self is installed as an independent component, whereas the embodiment shown in Fig. 2 uses the chlorine generating electrode 6 installed in the water reservoir 2 to measure the electrical conductivity of drinking water. An electrical conductivity meter 10 is connected to the electrode 6, which also serves as an electrode.

In addition, the electrode 6 and the DC power source 8. A circuit changeover switch 11 is connected between the electric conductivity meter 10 and the electric conductivity meter 10 .

When measuring the electrical conductivity of drinking water with this configuration,
The switch 11 is switched to the electrical conductivity meter 10 side to detect the electrical conductivity of the drinking water, and the detection signal is given to the energization control section 9. Note that since the electrical conductivity measurement is affected by the contact area between the electrode 6 and the drinking water, it is necessary to keep the water level in the water reservoir 2 at a constant level when measuring the electrical conductivity. For this purpose, for example, the electrical conductivity is measured at the timing when the water supply valve 3 is opened and the water level in the water reservoir 2 reaches the upper limit level.

When this electrical conductivity measurement is completed, the switch 11 is again switched to the DC power supply 8 side, and based on the detected electrical conductivity value and the detected chloride ion concentration value of the drinking water obtained above, the same procedure as in the embodiment shown in FIG. 1 is carried out. The chlorine generating electrode 6 is controlled to be energized to electrolyze drinking water and generate chlorine.

According to this embodiment, the electrical conductivity self as an independent component shown in the embodiment of FIG. 1 can be omitted, and the sterilizer can be made more compact.

Further, FIG. 3 shows another applied embodiment of the present invention.

In this embodiment, instead of the electrical conductivity meter used in the embodiment shown in FIG. The current/voltage value obtained by the measuring means 12 with a DC voltage applied to the generating electrode 6 from the DC power source 8 is given to the control unit 9 as a substitute value for the electrical conductivity to control the amount of electricity energized by the electrode 6. This is what I did.

In this embodiment, the electrical conductivity of drinking water is detected based on the following points. In other words, it has been confirmed from the experimental results that the electrical conductivity of drinking water and the current/voltage values determined above are in a proportional relationship as shown in Figure 6. From the relationship with Figure 5, as shown in Figure 7, chloride ion concentration/(current/voltage)
The relationship between the value and the amount of chlorine generated is determined. Therefore, this relational data is stored in the microcomputer of the control unit 9, and the detected chlorine ion concentration value and the current/current detected during electrolysis are stored in the microcomputer of the control unit 9.
By performing a comparison calculation with the chlorine ion concentration/(current/voltage) value obtained from the voltage value, the chlorine concentration in the water reservoir can be controlled in the same manner as in the embodiment shown in FIG.

Note that in the case of a constant current control circuit, since the current is constant, it is sufficient to measure only the voltage and calculate the current/voltage value between it and the known current.

FIG. 4 shows an embodiment that corresponds to changes in the temperature of drinking water. That is, the electrical conductivity of drinking water has a property of changing depending on the water temperature. Therefore, in this embodiment, the temperature of the drinking water is monitored by a water temperature sensor 13 such as a resistance temperature detector or thermistor provided in the reservoir, and the water temperature measurement value is input to the control unit 9, and the electricity of the drinking water detected separately is monitored. The detected conductivity value is corrected using a predetermined correction formula to the electrical conductivity at a reference water temperature, for example, with water temperature of 25°C as the reference temperature, and the C derived from this correction value.
The amount of electricity supplied to the chlorine generating electrode 5 is controlled by 3°-, /EC. According to this embodiment, the chlorine concentration can be controlled with high precision without being affected by changes in electrical conductivity due to temperature fluctuations in drinking water.

Note that the installation location of the water temperature sensor 13 is not limited to the water reservoir 2, but if an electrical conductivity measuring self is installed in the water supply pipe l as shown in Fig. 1, it may be installed in parallel with the self. Good.

[Effects of the Invention] Since the drinking water sterilization device according to the present invention is configured as described above, it exhibits the following effects.

(1) Detect the chlorine ion concentration and electrical conductivity of drinking water,
By configuring the structure to variably control the amount of electricity supplied to the chlorine generating electrode based on C (cL-1/E It is possible to maintain the chlorine concentration within an appropriate range.
Through the in-flight drinking water supply system, it is possible to stably supply high-quality drinking water that has sufficient sterilizing power and does not impart a chlorine odor to drinks.

(2) Also, by using the chlorine generating electrode as an electrode for measuring electrical conductivity and detecting the electrical conductivity of drinking water through this chlorine generating electrode, the electrical conductivity cell as an independent component can be omitted. The sterilizer can be made more compact.

(3) By correcting the detected value of electrical conductivity to the electrical conductivity of the reference water temperature and using it for control, the chlorine concentration can be controlled with high precision without being affected by fluctuations in the temperature of drinking water.

[Brief explanation of drawings]

Figures 1 to 4 are configuration diagrams of different embodiments of the present invention, and Figure 5 shows the amount of chlorine generated and C obtained from samples of synthetic water with chlorine ion concentration and electrical conductivity adjusted to various ratios.
(Relationship diagram of cL-1/EC, Figure 6 is a diagram of the relationship between the electrical conductivity of drinking water and the current/voltage value measured with the chlorine generating electrode,
FIG. 7 is a diagram showing the relationship between chlorine ion concentration/current/voltage values and the amount of chlorine generated. In the figure, 1...Tap water supply pipe, 2...Water reservoir, 6...
Chlorine generating electrode, 7... electrical conductivity cell, 8... DC power supply, 9... energization control section, 10... electrical conductivity meter,
12... Current/voltage value measurement means, 13... Water temperature sensor. Figure Figure

Claims (1)

[Claims] 1) A pair of chlorine generating electrodes are provided to apply a DC voltage to a drinking water supply system including a water reservoir that stores water supplied from the tap water, and chlorine is contained in the tap water by electrolysis. In a drinking water sterilizer that sterilizes drinking water by anodizing the chlorine ions produced in the water and converting them into chlorine, the device includes a means for detecting the electrical conductivity of drinking water, a means for detecting the concentration of chlorine ions in drinking water, and a means for energizing the chlorine generating electrode. to maintain the residual chlorine concentration in drinking water after chlorine sterilization within a predetermined range.
A drinking water sterilization device characterized by controlling the amount of electricity supplied to a chlorine generating electrode based on a detected value of chlorine ion concentration and a detected value of electrical conductivity of drinking water. 2) The drinking water sterilizer according to claim 1, characterized in that the chlorine generating electrode is also used as an electrical conductivity measuring electrode, and an electrical conductivity meter is connected to the electrode to detect the electrical conductivity of the drinking water. Drinking water sterilizer. 3) In the drinking water sterilizer according to claim 1, the chlorine generating electrode is also used as an electrical conductivity measuring electrode, and based on the current/voltage value determined from the measured values of the current flowing through the electrode and the voltage between the electrodes. A drinking water sterilization device characterized by controlling the amount of electricity applied to a chlorine generating electrode. 4) In the drinking water sterilizer according to claim 1, the detected value of the electrical conductivity of the drinking water is corrected to the electrical conductivity of a reference temperature;
A drinking water sterilizer characterized in that the amount of electricity supplied to the chlorine generating electrode is controlled based on this correction value.