JP4153459B2 - Residual chlorine measuring device - Google Patents

Description

  The present invention relates to a residual chlorine measuring device that detects a residual chlorine concentration by polarography.

  In domestic water, pool water, 24-hour bath water, etc., chlorine is injected for sterilization thereof. The amount of chlorine injected is controlled by measuring the concentration of free residual chlorine contained in the sample water. As a reagent-free measuring method for measuring the free residual chlorine concentration, a polarographic method is mainly used. In the polarographic method, the ion concentration of a specific chemical species is measured by measuring the oxidation / reduction current flowing between two electrodes when a voltage is applied between the two electrodes (counter electrode and working electrode) immersed in the test water. Is a method of measuring. A three-electrode type using a reference electrode in addition to the counter electrode and the working electrode is also known. In the three-electrode type, the reference potential is applied to the reference electrode in order to specify the potential of the working electrode whose absolute potential is unknown. This three-electrode method has the advantage of being resistant to changes in conductivity. In the polarographic method, since the oxidation / reduction current value changes when the flow rate of the sample water in contact with the electrode changes, a measurement tank called a flow cell for immersing the electrode in the water sample with a constant flow rate is used.

Also, since the surface of the working electrode is contaminated by the reduction reaction, the ceramic beads are housed in a measuring tank, and the working electrode is rotated by a motor so that the electrode surface is rubbed against the ceramic beads to clean the electrode surface. Yes. Moreover, in patent document 1, only a pair of electrodes faces an annular bead reservoir, causing reflux in the annular bead reservoir, and causing the beads to collide with the electrode surface by centrifugal force. Is disclosed. According to this, contamination of the electrode can be effectively prevented, and the configuration can be simplified by not using a motor that rotates the electrode.
JP 2002-250711 (paragraphs 0019 to 0021, FIGS. 1 and 2)

  However, in the residual chlorine meter disclosed in Patent Document 1 described above, the beads that move together with the test water introduced into the cylindrical bead storage tank have a rotational motion along the bead storage tank. The current situation is that effective cleaning cannot be performed.

  The present invention has been made in view of these points, and an object thereof is to provide a residual chlorine measuring apparatus capable of satisfactorily cleaning an electrode.

A residual chlorine measuring device according to the present invention includes an introduction port for introducing a measurement fluid, a measurement chamber connected to the introduction port, a measurement tank having a discharge port connected to the measurement chamber and discharging the measurement fluid, and the measurement tank An electrode unit that is attached to a measurement fluid introduced into the measurement chamber from the introduction port and that contacts an electrode and outputs an oxidation / reduction current based on the concentration of free residual chlorine contained in the measurement fluid; and the measurement tank And a bead for cleaning the electrode of the electrode unit, wherein the measurement chamber of the measurement tank is centered on an axis that is orthogonal to the introduction direction of the measurement fluid and that extends in the horizontal direction. The introduction port is connected to the lower side of the annular measurement chamber so as to introduce the measurement fluid in a tangential direction, and the discharge port is provided at an upper portion of the measurement chamber, Uni Comprising a main body portion having a detection surface including a working electrode, a reference electrode and a counter electrode arranged concentrically in a plane, the detection surface of the main body portion from the introduction port to the discharge port of the measurement fluid The measurement tank is attached to the measurement tank so as to be in contact with the outer peripheral surface of the annular measurement chamber at a position approximately in the middle of the flow path of the measurement fluid in the measurement chamber. A mode in which beads set up by the measurement fluid circulate in a quarter of the measurement chamber by setting the flow rate of the measurement fluid introduced into the measurement chamber to be controllable , which is set smaller than the area. And a mode of circulating around the measurement chamber is freely selectable .

According to the present invention, the measurement chamber is formed in an annular shape centered on an axis that is orthogonal to the introduction direction of the measurement fluid and extends in the horizontal direction, and the introduction port is tangentially below the annular measurement chamber. Connected to introduce the measurement fluid, the discharge port is provided in the upper part of the measurement chamber, and the electrode unit has an annular measurement chamber in the middle of the flow path from the measurement fluid introduction port to the discharge port. It is mounted so that it is in contact with the outer peripheral surface, the cross-sectional area of the inlet is set smaller than the cross-sectional area of the outlet, and the flow rate of the measurement fluid introduced into the measurement chamber is configured to be controllable, thereby measuring Since the beads wound up by the fluid can be freely selected from a mode in which they circulate a quarter of the measurement chamber and a mode in which they circulate around the measurement chamber , if the electrode unit is heavily soiled, the beads Around the bead The cleaning performance can be increased by increasing the impact force to the detection surface. In other states, it is possible to prevent the life of the electrode from being reduced by circulating the beads only by 1/4 turn. In this case, the beads stored in the measurement chamber measure the high flow rate from the inlet. It is wound up along the outer periphery of the annular measurement chamber by the fluid and is in sliding contact with the detection surface of the electrode unit. Further, since the cross-sectional area of the discharge port is larger than the cross-sectional area of the introduction port, the flow velocity of the measurement fluid introduced into the measurement chamber gradually decreases. For this reason, the beads in sliding contact with the detection surface do not reach the discharge port and fall along the inner circumference of the annular measurement chamber by their own weight. The beads can be repeatedly wound up and dropped to reciprocate over a relatively short distance to increase the number of beads per unit area. Thereby, more uniform and efficient electrode cleaning becomes possible. In addition, since the beads reach the detection surface of the electrode unit in the form of riding on the flow of the measurement fluid against gravity, the impact on the detection surface is reduced by the balance between the flow velocity of the measurement fluid and the weight of the beads, and the electrode Life can be extended.

Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings.
FIG. 1 is a diagram showing the configuration of a flow cell for residual chlorine measurement according to one embodiment of the present invention, and FIG. 2 is a cross-sectional view taken along line AA ′ of the measurement tank body in FIG.
This flow cell is inserted into an inspection flow path that branches from the main circulation path of the measurement fluid such as target water to be sterilized and merges with the circulation path again, and forms a measurement chamber 1a for measuring residual chlorine therein. A measurement tank 1, an electrode unit 2 attached to the measurement tank 1, and beads 3 for cleaning the electrode unit 2 housed in the measurement tank 1 are configured.

  The measurement tank 1 has a cylindrical hole portion 11a whose central axis extends horizontally to the measurement tank main body 11, as shown in FIG. 2 by the AA ′ cross section of FIG. 1 (however, only the measurement tank main body 11 portion). The cylindrical hole portion 11a is formed in a shape dug from one surface, and is liquid-tightly sealed by a cylindrical fixing screw 12 so that the cylindrical portion 12a is coaxially disposed at the center thereof. An annular measurement chamber 13 is formed by the cylindrical hole portion 11a and the cylindrical portion 12a. An introduction port 14 for introducing a measurement fluid in a tangential direction in contact with the outer periphery of the measurement chamber 13 is formed below the annular measurement chamber 13. The introduction port 14 communicates with a measurement fluid introduction tube 15. In addition, a discharge port 16 is provided at a position exceeding 180 ° from the introduction port 14 in the upper part of the measurement chamber 13, and the discharge port 16 has a discharge path 17 extending upward and a discharge path extending horizontally from the discharge path 17. The exhaust pipe 19 communicates with the exhaust pipe 19. The cross-sectional area of the discharge port 17 is larger than the cross-sectional area of the introduction port 14. For example, when the introduction port 14 and the discharge port 17 have a circular cross section, the diameter of the discharge port 17 is set to be twice or more the diameter of the introduction port 14. Has been.

  The detection surface 2a at the tip of the electrode unit 2 is positioned at the intermediate position of the flow path of the measurement fluid from the inlet 14 to the outlet 16 of the measurement chamber 13, that is, on the outer peripheral surface opposite to the inlet of the annular measurement chamber 13. Is touching. As shown in FIG. 3, the electrode unit 2 is, for example, a three-electrode type, and is arranged concentrically in a plane in the order of the working electrode 21, the reference electrode 22 and the counter electrode 23 in this order from the center of the circular detection surface 2a. . These electrodes 21 to 23 are integrally sealed with a sealing material so as to be exposed only on the detection surface 2a. These electrodes 21 to 23 and the sealing material form a cylindrical main body 24. A fixing collar portion 25 and a connection portion 26 to which an electric wire is connected are respectively formed on the base end side of the main body portion 24.

Next, the operation of the thus configured residual chlorine measuring device will be described.
4 is an enlarged view showing a portion of the measurement chamber 13 in the present apparatus, and FIG. 5 is a cross-sectional view taken along the line BB ′ of FIG. In the figure, the dotted line arrow indicates the direction of the flow of the measurement fluid, and the solid line arrow indicates the movement of the bead 3.
The measurement fluid flowing through the inspection flow channel is introduced into the flow cell from the introduction pipe 15 and is guided to the lower end portion of the measurement chamber 13 of the measurement tank 1 through the introduction port 14 in the tangential direction of the outer periphery. The measurement fluid introduced into the measurement chamber 13 moves upward along the cylindrical wall portion on the outer side of the annular measurement chamber 13 as shown by a dotted arrow in the figure, and a part thereof is a discharge port. 16 and is discharged upward, and the rest returns to the measurement fluid introduction portion side of the measurement chamber 13.

  The beads 3 accommodated in the measurement chamber 13 ride on the flow of the measurement fluid and move counterclockwise along the outer wall portion of the annular measurement chamber 13 as indicated by the solid line arrow. It is in sliding contact with the detection surface 2a of the electrode unit 2. Whether the beads in sliding contact with the detection surface 2a move to the discharge port 16 side or naturally fall is determined by the balance between the flow velocity of the measurement fluid and its own weight. Since the diameter of the discharge port 16 is set to be twice or more the diameter of the introduction port 14, the flow velocity of the measurement fluid is maximum near the introduction port 14, but greatly decreases near the discharge port 1. For this reason, the beads 3 fall by their own weight without reaching the discharge port 16. The falling beads 3 fall along the inner peripheral wall portion of the annular measurement chamber 13. Further, as shown in FIG. 5, when the inlet 14 is provided at the center in the width direction of the measurement chamber 13, the flow velocity at the center is higher than the flow velocity at both ends, as shown in the figure. The beads 3 circulate along a trajectory from the inside to the outside.

Thus, according to the present apparatus, the beads 3 do not go around the measurement chamber 13 and the moving distance of the beads 3 is as short as about 1/4 of the measurement chamber 13, so even a small amount of unit space can be obtained. The number of beads occupies more. For this reason, the contact with the detection surface 2a is reliable and the beads can be uniformly brought into contact with the detection surface 2a over a wide range, and the cleaning effect is extremely high.
Further, according to the present apparatus, the beads 3 are jetted vertically upward against gravity, so that the strong impact of the beads 3 on the detection surface 2a of the electrode unit 2 is alleviated and the life of the electrodes is extended. It becomes possible to do.

  If the flow rate of the measurement fluid introduced from the introduction port 14 into the measurement chamber 13 is further increased, the beads 3 can be made to make a round in the measurement chamber 13. Therefore, by controlling the flow rate of the measurement fluid introduced into the measurement chamber 13, a mode in which the beads 3 are circulated by a quarter of the measurement chamber 13 and a mode in which the round of the measurement chamber 13 is circulated is selected. be able to. In this case, when the electrode unit 2 is heavily soiled, the bead 3 is made to circulate once and the impact force of the bead 3 on the detection surface 2a is increased to increase the cleaning ability. By circulating only four rounds, it is possible to prevent the life of the electrode from being reduced. Even in this case, the diameter of the discharge port 16 and the discharge paths 17 and 18 is set to be twice or more the diameter of the introduction port 14, and the discharge path 17 is formed to extend upward, so that the beads 3 are discharged. There is almost no discharge to the path 17 side.

It is a figure which shows the structure of the residual chlorine measuring apparatus which concerns on one Embodiment of this invention. It is A-A 'sectional drawing in FIG. 1 of the measurement tank main body used for the apparatus. It is a figure which shows the electrode unit in the apparatus, The figure (a) is an external appearance perspective view, The figure (b) is a front view which shows a front-end | tip part. It is a figure which expands and shows the part of the measurement chamber in the same apparatus. It is B-B 'sectional drawing in FIG.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Measurement tank, 2 ... Electrode unit, 3 ... Bead, 11 ... Measurement tank main body, 12 ... Cylindrical fixing screw, 13 ... Measurement chamber, 14 ... Introducing port, 15 ... Introducing pipe, 16 ... Discharge port, 17, 18 ... Discharge path, 19 ... discharge pipe.

Claims (2)

A measurement tank having an introduction port for introducing the measurement fluid, a measurement chamber connected to the introduction port, and a discharge port connected to the measurement chamber and discharging the measurement fluid;
An electrode unit that is attached to the measurement tank and that is in contact with the measurement fluid introduced into the measurement chamber from the introduction port and outputs an oxidation / reduction current based on the concentration of free residual chlorine contained in the measurement fluid;
A residual chlorine measuring device comprising: beads housed in the measuring tank and cleaning the electrodes of the electrode unit;
The measurement chamber of the measurement tank is formed in an annular shape around an axis that is orthogonal to the introduction direction of the measurement fluid and extends in the horizontal direction,
The introduction port is connected to introduce the measurement fluid in a tangential direction below the annular measurement chamber;
The outlet is provided in the upper part of the measurement chamber,
The electrode unit includes a main body portion having a detection surface including a working electrode, a reference electrode, and a counter electrode arranged concentrically in a plane, and the detection surface of the main body portion extends from the measurement fluid introduction port to the discharge port. Is attached to the measurement tank so as to be in contact with the outer peripheral surface of the annular measurement chamber at a substantially intermediate position of the flow path of the measurement fluid in the measurement chamber.
The measuring tank is set so that the cross-sectional area of the inlet is smaller than the cross-sectional area of the outlet ,
By configuring the flow velocity of the measurement fluid introduced into the measurement chamber to be controllable, the bead wound up by the measurement fluid circulates a quarter of the measurement chamber, and one round of the measurement chamber The residual chlorine measuring device is characterized in that it can freely select a mode of circulating the gas.   The residual chlorine measuring device according to claim 1, wherein when the cross section of the inlet and the outlet is circular, the diameter of the outlet is at least twice the diameter of the inlet.

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