JP2001235446A - Residual chlorine meter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a miniaturized residual chlorine meter. SOLUTION: The residual chlorine meter is provided with a measuring cell provided with a feed water inlet 18 making sample water 22 flow at least on measurement, and a drain outlet 19 draining the sample water 22, a comparison electrode 17 arranged in the measuring cell 20, a flat plate-like detection electrode 16, a means for applying voltage between the detection electrode and the comparison electrode, and a means for detecting current flowing between the detection electrode and the comparison electrode. The residual chlorine meter is formed of a structure without using the sealed wiring, the motor and the glass beads of the conventional residual chlorine meter.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a residual chlorine meter, and more particularly to a residual chlorine meter used for a water quality monitoring system or the like and suitable for continuously monitoring water quality on-line.

[0002]

2. Description of the Related Art FIG. 10 is a diagram showing a basic configuration of a conventional residual chlorine meter. The sample water is supplied from the water supply port 18 to the measurement cell 30, the residual chlorine concentration in the sample water is measured by the detection electrode 16 and the comparison electrode 17, and the sample water is discharged from the drain port 19. In addition, a seal is provided so that the joint between the electrode and the lead wire does not come into contact with the sample water, but the structure in which the wiring seal portion 33 exists in the measurement container is adopted. Due to its structure, miniaturization is difficult, and the measurement cell is about 50 mm × 50 mm × 100 mm.

[0003] Further, in a residual chlorine meter using voltammetry or polarography, the detection electrode 16 is contaminated with use, and the performance sometimes deteriorates. Therefore, the glass beads 32 are put in the measurement cell, and the detection electrode 1
6, the detection electrode 16 itself is rotated, and dirt is removed by friction polishing with the glass beads 32 to extend the life. However, the detection electrode 16 itself is shaved by polishing, and the electrode itself needs to be replaced, and the electrode replacement time is usually once every two years. In addition, the residual chlorine analyzer that employs a method of washing the detection electrode 16 by hand requires cleaning once every two months.
The necessity of cleaning the reference electrode 17 does not matter. In addition,
Japanese Patent Application Laid-Open Nos. 8-278282, 8-304323, and 9-17
No. 8699, and the like.

[0004]

As a representative example of the measurement of tap water quality, in measuring the quality of tap water distribution, the quality of water at the end of a water distribution pipe that is consumed by a customer is measured to check whether the value is appropriate. It is preferable that the water quality is controlled appropriately, and a residual chlorine meter which forms a part of a small water quality meter which can be easily installed is required. The size desired for the measuring part of the residual chlorine meter is 30 mm x 15 mm
It is about × 15 mm. It has been difficult to downsize the conventional residual chlorine meter for the following reasons.

[0005] (1) In polarography or voltammetry, the ratio of the surface area of the anode (detection electrode) to the surface area of the cathode (comparative electrode) is set to about 1: 120.
It was difficult to store this ratio in a small measuring cell.

(2) When glass beads are used, a space for enclosing the glass beads is required, and the volume of the measuring cell is increased only in that space.

(3) There is a portion for sealing the joint between the electrode and the lead wire from the sample water, and the residual chlorine meter becomes large only in the portion where the seal portion exists.

Further, it is difficult to maintain the processing accuracy of the columnar electrode, and the processing is costly. Further, the electrode is polished in the method of cleaning the electrode with glass beads, so that the surface area of the electrode is gradually reduced. No consideration has been given to the possibility that the electrode characteristics may change.

Further, in the residual chlorine meter, since the contamination of the electrode leads to deterioration of the performance, the electrode is manually washed once every two months.
It did not take into account the need to change once every two years.

Due to the problem of the electrode life, it has been difficult to monitor the water quality on-line using a residual chlorine meter using a polarographic method, which does not require maintenance, and to control the water quality.

A first object of the present invention is to provide a miniaturized residual chlorine analyzer. A second object of the present invention is to provide a residual chlorine meter that is easy to maintain.

[0012]

In order to achieve the first object, a residual chlorine meter according to the present invention has a measuring port provided with a water inlet for flowing sample water and a drain for discharging the sample water at least at the time of measurement. A cell, a plate-like comparison electrode and a detection electrode arranged in the measurement cell, a means for applying a voltage between the detection electrode and the comparison electrode, and a current flowing between the detection electrode and the comparison electrode. This is provided with a means for performing.

Both the detection electrode and the reference electrode are preferably integrated with the inner wall of the measurement cell. Integrating with the inner wall means that, for example, each electrode may be embedded in the inner wall, or may be formed on the surface of the inner wall of each electrode by plating or sputtering.

It is preferable that the measuring cell is made of an insulator, and a joint portion with a lead wire is provided between the insulator and a flat plate electrode integrated with the insulator, so that a structure without a seal portion is preferable.

Further, in order to achieve the second object,
The residual chlorine meter of the present invention is a measuring cell having at least a water inlet through which sample water flows in at the time of measurement and a water outlet through which the sample water is drained, a detecting electrode, a comparative electrode arranged in the measuring cell, and a detecting cell. Means for applying a voltage between the electrode and the reference electrode, and means for detecting a current flowing between the detection electrode and the comparison electrode, wherein the detection electrode is disposed through the measurement cell, and The detection electrode is configured to be movable in a direction in which the detection electrode is moved.

As described above, by shifting the detection electrode in the direction penetrating the measurement cell, it is possible to easily replace the used electrode portion with the unused electrode portion.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a configuration diagram showing an example of an installation form in a consumer of a water quality meter equipped with a reagentless residual chlorine meter of the present invention. Tap water introduced from the water distribution pipe 1 enters the water distribution facility 5 via the shutoff valve 4 and the water meter 3,
At the same time, the water quality on the customer side is measured by the water quality meter 2. The water distribution facility 5 is composed of a piping network, and drinking water is supplied to a consumer from one of the locations via a water tap 6.

FIG. 2 is a schematic diagram showing the flow path inside the water quality meter.
The sample water introduced from the water distribution pipe 1 is supplied to the pressure reducing valve 7 and the filter 8
The air bubbles are removed in the defoaming tank 9 through. The sample water is introduced into the residual chlorine meter 10, the chromaticity measurement / analysis unit 11, and the turbidity measurement / analysis unit 12, respectively, and measurement is performed. In the chromaticity measurement / analysis section 11 and the turbidity measurement / analysis section 12, washing is performed with pure water 13 and washing water (for example, diluted hydrochloric acid) 14 after measurement. The water used for the measurement and cleaning is drained from the drain port 15.

FIGS. 3 and 4 are a plan view and a sectional view showing a residual chlorine meter according to an embodiment of the present invention. The detection electrode 16 and the comparison electrode 17 are embedded in a measurement cell 20 made of an insulator made by a microfabrication technique, and each electrode, a lead wire 23, and the like are provided between the measurement cell 20 and each electrode. And the structure is such that the joint does not come into contact with the sample water. The ratio of the surface area of the detection electrode 16 to that of the comparison electrode 17 is about 1:80.

The detection electrode and the reference electrode can be formed by a method of plating the surface of the measurement cell 20 which is an insulator with platinum or silver, or by a technique such as sputtering, so that the electrodes can be formed at low cost. In addition, since the measurement cell 20 is made of an inorganic material such as silicon or ceramic or an organic material such as acrylic resin, urethane resin, or epoxy resin and is manufactured by applying microfabrication technology, mass production leads to cost reduction. . Furthermore, since the shape of the measurement cell can be freely created, the structure is such that air bubbles that have entered the measurement cell can easily escape by forming an angle on the ceiling of the measurement cell. The sample water 22 is supplied into the measurement cell from the water supply port 18, the sample water 22 flows between the detection electrode 16 and the reference electrode 17, and the concentration of residual chlorine contained in the sample water is measured. After the measurement, the sample water 22 is discharged from the outlet 19.
With such a structure, there is no need to rotate the electrode unlike a circular electrode. Further, a temperature sensor 21 for temperature measurement is arranged in the measurement cell. The size of this measuring cell is about 30 mm × 15 mm × 15 mm. As described above, by reducing the material cost of the electrode unit and the downsizing of the measuring unit, it is possible to significantly reduce the cost, and it is possible to make the measuring unit disposable and to have a structure in which the measuring unit can be easily replaced.

FIGS. 5, 6, and 7 are a plan view, a cross-sectional view, and a cross-sectional view when the positions of the electrodes are changed as will be described later, showing a residual chlorine meter according to another embodiment of the present invention. The detection electrode 16 is longer than the height of the measurement cell 20 and has a structure penetrating the measurement cell. Water supply port 18
Supplies the sample water 22 to the measurement cell 20, and the sample water 22 flows through the measurement cell, and comes into contact with the detection electrode 16 and the comparison electrode 17 in the measurement cell, whereby the residual chlorine concentration in the sample water is measured. Further, the sample water is discharged from the drain port 19. In a residual chlorine analyzer using polarography or voltammetry, when a sample is measured, the detection electrode 16 is contaminated, and the performance is reduced. The present invention is characterized in that the used electrode 24 is pushed out of the measuring cell only by shifting the detection electrode, and the unused electrode 25 has a structure that can be easily replaced with the used electrode 24 as shown in FIG. . Further, even if the electrode is replaced, the surface area of the detection electrode 16 that comes into contact with the sample water is constant by having such a structure.

FIG. 8 is a signal block diagram of the residual chlorine meter of the present invention. The signals from the electrodes 16 and 17 and the temperature sensor 21 are amplified by the preamplifier 26 of the measuring circuit 29, and the output amplifier 27 amplifies to 4 to 20 mA DC or 1 to 5V. Further, a voltage is applied from the power supply circuit 28 to each circuit.

FIG. 11 is a diagram showing a measuring circuit of the residual chlorine meter. The detection electrode 16 is composed of a Pt electrode, and the comparison electrode 17
Consists of Ag electrodes. The current value measured by the IV converter 34 is converted into a voltage value and output.

FIG. 9 is a sectional view showing a residual chlorine meter according to still another embodiment of the present invention. Since silicon is used for the measurement cell 20 similar to the embodiment shown in FIG. 4, a preamplifier 26 for signal amplification can be arranged on the cell. Therefore, the distance between the sensor and the preamplifier can be reduced, and the signal from the sensor is less affected by noise, so that the measurement is stabilized.

[0025]

According to the present invention, since a plate electrode is used and a motor and glass beads used for electrode cleaning are not used, a small-sized residual chlorine analyzer can be obtained. Further, since the detection electrode and the reference electrode are integrated with the inner wall of the measurement cell and the wiring seal portion is not required, the size can be further reduced. In addition, since the structure does not require a driving part such as a motor, the production cost can be reduced and the power consumption can be reduced, and the measuring unit can be manufactured at a very low cost. A method of changing parts has become possible.

Further, by allowing the detection electrode to penetrate the measurement cell and to be movable in that direction, the replacement time can be greatly extended depending on the dimensional relationship between the length of the detection electrode and the measurement cell width. The number of replacements can be reduced, and the necessity of cleaning the electrodes is only performed at the time of replacement of the electrodes. Further, the contact area between the detection electrode and the sample water is maintained. In addition, since the detection electrode is not polished, the area ratio between the detection electrode and the reference electrode does not change, so that stable measurement can be performed.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing an example of an installation mode of a water quality meter equipped with a residual chlorine meter of the present invention in a customer.

FIG. 2 is a configuration diagram showing a flow path inside a water quality meter equipped with the residual chlorine meter of the present invention.

FIG. 3 is a plan view showing a residual chlorine meter according to one embodiment of the present invention.

FIG. 4 is a sectional view of the residual chlorine meter shown in FIG. 3;

FIG. 5 is a plan view showing a residual chlorine meter according to another embodiment of the present invention.

FIG. 6 is a cross-sectional view of the residual chlorine meter shown in FIG.

FIG. 7 is a sectional view when the positions of the electrodes of the residual chlorine meter shown in FIG. 5 are changed.

FIG. 8 is a signal block diagram of a residual chlorine meter according to the present invention.

FIG. 9 is a sectional view showing a residual chlorine meter according to still another embodiment of the present invention.

FIG. 10 is a configuration diagram of a conventional residual chlorine meter.

FIG. 11 is a diagram showing a measurement circuit of a residual chlorine meter.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Water distribution pipe 2 ... Water quality meter 3 ... Water meter 4 ... Shut-off valve 5 ... Water distribution equipment 6 ... Water tap 7 ... Pressure reducing valve 8 ... Filter 9 ... Defoaming tank 10 ... Residual chlorine meter 11 ... Chromaticity measurement analysis unit 12 ... Turbidity measurement / analysis section 13 ... Pure water 14 ... Washing water 15,19 ... Drain 16 ... Used electrode 25 ... Unused electrode 26 ... Preamplifier 27 ... Output amplifier 28 ... Power supply circuit 29 ... Measurement circuit 31 ... Motor 32 ... Glass beads 33 ... Wiring seal part 34 ... IV conversion part

Continued on the front page (72) Inventor, Tamio Ishihara 882 Ma, Hitachinaka-shi, Ibaraki Prefecture Within Hitachi Instruments Measuring Instruments Group (72) Inventor Katsutoshi Yamada 882 Ma, Hitachinaka-shi, Ibaraki Prefecture Hitachi Instruments Mfg. Co., Ltd. In group

Claims (4)

[Claims] 1. A measuring cell having at least a water inlet through which sample water flows in at the time of measurement and a drain through which the sample water is drained,
A flat comparison electrode and a detection electrode arranged in the measurement cell, a means for applying a voltage between the detection electrode and the comparison electrode, and a current flowing between the detection electrode and the comparison electrode. A residual chlorine meter having means for detecting. 2. The residual chlorine meter according to claim 1, wherein both the detection electrode and the comparison electrode are integrated with the inner wall of the measurement cell. 3. The residual chlorine meter according to claim 1, wherein a part of a measuring circuit is formed on the measuring cell. 4. A measuring cell having at least a water inlet through which sample water flows in at the time of measurement and a drainage outlet through which the sample water is drained,
A detection electrode, and a reference electrode arranged in the measurement cell,
Means for applying a voltage between the detection electrode and the comparison electrode, and means for detecting a current flowing between the detection electrode and the comparison electrode, wherein the detection electrode passes through the measurement cell A residual chlorine meter, wherein the residual chlorine meter is arranged so as to be movable in the penetrating direction, and can change a portion of the detection electrode in the measurement cell by the movement.