JPH11118750A - Apparatus for setting of reference electrode - Google Patents

Abstract

PROBLEM TO BE SOLVED: To continuously measure a potential for a long time and reduce influences on corrosion of a metallic piping as a result of running of an electrolyte out to a water path part, by filling a gel substance obtained by dissolving the electrolyte in place of an electrolyte solution filled in a container. SOLUTION: A container main body 1 has an electrode fixed part 2 at one end, a leading end part 3 at the other end, and an ion transmission part 4 of an ion-passing solid material at a leading end of the part 3. A gel substance 9 obtained by dissolving an electrolyte is filled in the container main body 1, and a detecting part 8 of a reference electrode 10 is soaked in the gel substance. The leading end part 3 is set projecting to a water path part 6. The gel substance 9 and the water or a solution running in the water path part 6 are brought in touch with each other via the ion-passing solid material at the ion transmission part 4. The electrolyte of the gel substance 9 and an electrolyte of a solution inside the reference electrode 10 are the same kind of the same component concentration, so that components of the electrolyte of the inner solution are refrained from moving outside. Accordingly a potential can be measured continuously without exchanging the reference electrode 10.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to an apparatus for setting a reference electrode. More specifically, the present invention enables continuous measurement of the potential over a long period of time without stopping the flow of water in the potential measurement water system and without maintenance such as replenishing the electrolyte components eluted from the inside of the vessel. The present invention relates to an apparatus for setting a reference electrode for mounting a reference electrode for measuring a potential for determining a tendency.

[0002]

2. Description of the Related Art In order to predict the occurrence of local corrosion in piping such as a heat exchanger through which a fluid such as water or a solution flows,
As shown in JP-A-5-322831, the corrosion potential of a metal pipe is measured with reference to a reference electrode inserted into a flow path. However, elution of the electrolyte component in the solution inside the electrode from the detector at the tip of the reference electrode, which is made of an ion-permeable substance such as ceramics, causes a decrease in the measurement accuracy of the electrode and air from the detector at the tip of the reference electrode In order to prevent potential measurement value abnormalities and the like, it was necessary to replace the internal solution of the reference electrode with reduced measurement accuracy and to bleed air, and in that case, it was necessary to stop the flow of water through the potential measurement water system. As a method of preventing the measurement accuracy of the electrode from deteriorating due to the elution of the electrolyte component in the internal solution of the reference electrode, the internal solution is periodically replenished while the reference electrode is inserted in the water passage,
Although the replacement method can be considered, it is extremely difficult to replace the internal solution without removing it from the water flow line due to the structure of the electrode. Had to be removed. As a method for solving this problem, Japanese Unexamined Patent Publication No. Hei 5-107217 discloses a method in which a bypass pipe is provided so that electrodes can be attached / detached without stopping water flow. A piping device with a corrosion measurement function has been proposed which maintains the electrolyte concentration of the electrode internal solution and prevents the measurement accuracy of the electrode from being reduced. However, such a device requires installation of a bypass pipe and a valve. In addition, in order to prevent a decrease in measurement accuracy due to elution of the electrolyte component in the internal solution of the reference electrode, the reference electrode is removed from the potential measurement water system during normal times, so that the potential cannot be continuously measured, and the potential measurement is performed. Each time, it is necessary to open and close the valve of the water flow line, and to attach and remove the blind plug and the reference electrode.
On the other hand, as a method of preventing air from the detection part at the tip of the reference electrode, a method of inserting the reference electrode deeply into the flow path can be considered. However, many commercially available reference electrodes are made of glass, and are directly inserted deeply and tightened. Easy to be damaged when doing. In addition, when the pipe diameter is small, the flow of the fluid is greatly affected by the reference electrode protruding above the flow path, and the area through which water can pass is narrowed. High risk of doing. For this reason, when it is difficult to insert the reference electrode deeply, there is a problem that air is trapped in the detection section at the tip of the electrode, and accurate potential measurement cannot be performed. As a method for solving this problem, Japanese Patent Application Laid-Open No. HEI 6-185700 discloses a method in which an inspection box having a water inlet and a water outlet is provided in the middle of a pipe, and a metal pipe to be inspected and an electrode are installed in the inspection box. There has been proposed a corrosion inspection apparatus for a metal pipe in which a fluid is caused to flow upward from below to a detection unit, and a defoaming cell having an open upper surface is provided on the inflow side of the inspection cell.
However, in such a device, since the upper part of the inspection cell where the reference electrode is installed and the upper part of the defoaming cell have an open structure,
In addition to being unable to be used when the water pressure is high, there is a problem that when the degassed fluid is passed, oxygen is dissolved from the inspection cell or the degassing cell. In addition, 7-4333
In JP-A-5, a reference electrode is held in a bottomless cylindrical container filled with a mixture of a superabsorbent polymer impregnated with an electrolyte solution and pulp or silica gel, and a stopper made of a porous material is attached to the tip of the cylindrical container. A corrosion detection sensor for steel has been proposed. This sensor is portable and has the advantage that measurements can be made in the field, in all orientations, such as upwards or sideways.However, the measurement accuracy is low because the electrolyte solution is impregnated with the heterogeneous mixture. There is a problem that it does not improve sufficiently. The present inventors have previously made up a container filled with an electrolyte solution and a support having a water passage portion, the tip of the container protruding into the water passage portion of the support, and the leading end of the container has an ion-permeable portion. Developed a device for installing a reference electrode for measuring the potential of metal pipes made of conductive solid materials, and interposed a container filled with an electrolyte solution of the same type and concentration as the solution inside the reference electrode between the reference electrode and the flow path system This solves the problem that the measurement accuracy of the reference electrode decreases due to the elution of the electrolyte component in the internal solution of the reference electrode. Although the problem of elution of the electrolyte component in the reference electrode internal solution was solved by this reference electrode installation device, if this device was used for a long period of time, the electrolyte component in the container would become the state-of-the-art ion-permeable solid. The material gradually elutes from the material into the water passage, requiring maintenance such as replenishment of the electrolyte component in the container or replacement of the electrolyte solution, and corrosion of the metal piping by the eluted electrolyte component. For this reason, there has been a demand for a reference electrode installation apparatus in which the elution of the electrolyte component via the state-of-the-art ion-permeable solid material is further reduced.

[0003]

SUMMARY OF THE INVENTION The present invention enables continuous measurement of a potential for a long period of time without maintenance such as replenishing electrolyte components eluted from the inside of a container without stopping water flow in a potential measurement water system. Provided is a reference electrode installation device for mounting a reference electrode for measuring potential for determining the tendency of pipe corrosion, which can reduce the influence on the corrosion of metal pipes due to the elution of electrolyte into the water passage section. It was done for the purpose of doing.

[0004]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to solve the above-mentioned problems, and as a result, in the above-mentioned reference electrode installation apparatus, an electrolyte was used instead of the electrolyte solution filled in the container. By filling the gel-like substance in which is dissolved, the amount of the electrolyte component eluted into the water passage section through the ion-permeable solid material can be significantly reduced, and the measurement accuracy can be maintained at the same level as when the electrolyte solution is filled. The present invention has been completed based on this finding.
That is, the present invention provides (1) an electrode fixing portion at one end of a container body and a tip portion at the other end, and a reference electrode is immersed in a gel-like substance in which an electrolyte filled therein is dissolved. The electrode is fixed at the electrode fixing part, the tip of the tip is made of an ion-permeable solid material, and the tip protrudes from the water passage. An apparatus is provided. Further, as a preferred embodiment of the present invention, (2) the gel-like substance is composed of polyvinyl alcohol, carboxymethylcellulose or sodium carboxymethylcellulose and water.
(1) The reference electrode installation device according to (1), and (3) the reference electrode according to (1), wherein the water passage section is provided on the support so that both ends thereof are pipe connection ports. Installation equipment.

[0005]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to the drawings. FIG. 1A is a side view of one embodiment of the reference electrode installation apparatus of the present invention, and FIGS. 1B and 1C show a state where the reference electrode is fixed and attached to a support. It is sectional drawing. The device for setting a reference electrode of the present invention has an electrode fixing part 2 at one end of a container body 1 and a tip part 3 at the other end,
The leading end of the tip is an ion-permeable portion 4 made of an ion-permeable solid material. There is no particular limitation on the shape of the container body, and any shape may be used as long as it is a structure that can be filled with a gel-like substance in which an electrolyte is dissolved, and the detection unit at the tip of the reference electrode to be inserted can be immersed in the gel-like substance. can do. The material of the container body is not particularly limited as long as it is not corroded by a gel-like substance in which an electrolyte filled therein and a fluid flowing through the water-passing section are used.For example, a metal, an acrylic resin, a polyvinyl chloride resin, Plastics such as polypropylene can be used. For metal materials,
It is preferable to make them from the same material so that the dissimilar metal contact corrosion does not occur. Further, it is preferable that the container body is formed of a transparent material. By forming the container main body with a transparent material, the state inside the container can be observed, and appropriate measures can be taken promptly for abnormalities. The shape of the electrode fixing portion is not particularly limited as long as the reference electrode can be fixed, and may be a closed type or an open type.However, evaporation of the solvent from the gel material in which the electrolyte is dissolved is prevented. In order to prevent this, a structure that can be hermetically sealed is preferable. The electrode fixing portion is preferably made of a material that is not corroded by a gel-like substance in which an electrolyte is dissolved, and examples of such a material include rubber, plastic, and metal.

There is no particular limitation on the shape of the tip portion, but it is preferable that the tip portion be thin. Since the distal end portion is provided so as to protrude into the water passage portion, it is possible to avoid obstruction of the fluid flowing through the water passage portion by making the tip portion thin. The material of the tip is not particularly limited as long as it is not corroded by a gel-like substance in which the electrolyte filled therein and a fluid flowing through the water-passing section are used. For example, metal, acrylic resin, polyvinyl chloride resin, polypropylene And the like. The ion-permeable portion is at the forefront of the tip portion, and has a structure in which the gel-like substance in which the electrolyte in the container is dissolved and water or the solution flowing through the water-passing portion can be contacted through the ion-permeable solid material. ing. The ion-permeable solid material to be used is not particularly limited as long as it is a porous material having ion permeability. Examples of such an ion-permeable solid material include ceramics and Vyc.
or glass (made of Corning glass). In the reference electrode installation device of the present invention, the container main body, the electrode fixing portion and the tip portion can be separately formed and then joined, and the container main body and the tip portion or the container main body and the electrode fixing portion are integrally formed. After that, the electrode fixing portion or the distal end portion can be joined, or the container main body, the distal end portion, and the electrode fixing portion can be integrally molded. The method of joining the tip and the ion-permeable portion is such that the gel-like substance in which the electrolyte in the container is dissolved does not directly contact the water or the solution flowing through the water-passing portion, but comes into contact through the ion-permeable solid material. There is no particular limitation, and for example, bonding can be performed by a method using an adhesive, a method of fixing with a heat shrinkable tube, or the like.

There is no particular limitation on the reference electrode fixed to the reference electrode installation device of the present invention, and a reference electrode can be appropriately selected according to the purpose of use. As such a reference electrode, for example, Ag | AgCl | 3.5M KCl, Ag
| AgCl | Saturated KCl, Hg | Hg ₂ Cl ₂ | 0.1M
KCl, Hg | Hg ₂ Cl ₂ | 1.0 M KCl, Hg | H
g ₂ Cl ₂ | 3.5M KCl, Hg | Hg ₂ Cl ₂ | saturated K
Cl, Hg | Hg ₂ SO ₄ | saturated K ₂ SO ₄ . The electrolyte used for the gel substance in which the electrolyte to be filled in the container of the reference electrode installation device of the present invention is dissolved is preferably the same kind of electrolyte as the reference electrode internal solution, for example, potassium chloride, lithium chloride, chloride chloride. Sodium, potassium nitrate, barium chloride, potassium sulfate and the like can be appropriately selected and used. It is preferable that the concentration of the electrolyte component in the gel material in which the electrolyte is dissolved is selected so that the concentration of the electrolyte component in the gel material is equal to the concentration of the electrolyte component in the reference electrode internal solution. By setting the electrolyte in the gel substance in which the electrolyte filled in the device is dissolved and the electrolyte in the internal solution of the reference electrode to be the same type and the same electrolyte component concentration, the electrolyte component of the internal solution of the reference electrode can be detected. It is possible to suppress the transfer from the part to the outside, and it is possible to continuously measure the potential over a long period of time without replacing the reference electrode. In the present invention, there is no particular limitation on the gel-like substance that dissolves the electrolyte. A gel-like substance composed of a polymer substance and water can be used. Among these, a gel substance composed of polyvinyl alcohol, carboxymethylcellulose or sodium carboxymethylcellulose and water can be particularly preferably used. These are components of commercially available laundry paste and have the advantage of being easily available.
In the present invention, there is no particular limitation on the method for preparing the gel-like substance in which the electrolyte is dissolved, and for example, a gel-like substance is obtained by dissolving a polymer substance such as polyvinyl alcohol in warm water in which the electrolyte is dissolved and then cooling. Alternatively, a gel-like substance can be obtained by dissolving an electrolyte in a heated aqueous solution of a polymer substance and then cooling it. The gel substance in which the electrolyte used in the present invention is dissolved includes:
Preservatives and the like can be added as necessary.

[0008] The reference electrode installation device of the present invention can be attached to a support. FIG. 1B is a cross-sectional view in a direction parallel to the water passage showing a state where the reference electrode installation device is attached to the support, and FIG. 1C is a cross-section in a direction perpendicular to the water passage. FIG. The support 5 has a water passage 6, and both ends of the water passage are pipe connection ports 7 that can be connected to a pipe.
The structure of the pipe connection port is not particularly limited, and may be, for example, a screw type or a type using a flange.
The cross-sectional shape of the water passage section is not particularly limited, but is preferably the same shape as the connecting pipe. The material of the support is not particularly limited, but is preferably made of a non-conductive material that is not corroded by the fluid flowing through the water passage. Such materials include, for example, Teflon, vinyl chloride resin,
Examples thereof include polypropylene and polyacetal. In the reference electrode installation apparatus of the present invention, the reference electrode 10 is fixed to the electrode such that the detection section 8 at the tip of the reference electrode is immersed in the gel substance 9 in which the electrolyte filled in the container body and the tip is dissolved. It is fixed in part 2. The reference electrode installation device is installed such that its tip protrudes from the water passage. Although there is no particular limitation on the position of the ion-permeable portion made of the most ion-permeable solid material at the tip, it is preferably located near the center of the cross section of the water-permeable portion. Since the ion permeable portion is located near the center of the cross section of the water passage portion, air is hardly generated, and the flow of the fluid flowing through the water passage portion is hardly obstructed. The method for attaching the reference electrode installation device to the support is not particularly limited. For example, the device can be attached using an adhesive, or can be attached using screws. In FIG. 1, the reference electrode installation device is attached to a support with an adhesive.

FIG. 2A is a side view of another embodiment of the reference electrode installation apparatus of the present invention. The reference electrode installation device of this embodiment has an electrode fixing part 2 at one end of a container body 1 and a tip 3 at the other end, and the tip of the tip is made of an ion-permeable solid material. The transmissive part 4 is provided, and a male screw 11 for attaching the reference electrode setting device to the support is provided in the container body. FIG. 2B is a cross-sectional view in a direction parallel to the water-passing portion showing a state in which the reference electrode installation device is attached to the support, and FIG. 2C is a cross-section in a direction perpendicular to the water-passing portion. FIG. The support 5 of this embodiment has a T-shaped tube shape, and has a side tube 12 provided with a female screw that is screwed with a male screw 11 provided on the container body of the reference electrode installation device, and screwed in. Thereby, the reference electrode setting device can be attached to the support. In the reference electrode installation device of the present invention, the distal end protrudes into the water passage section, and the ion permeable section has the same function as the detecting section at the reference electrode distal end, so that air does not occur in the detecting section of the reference electrode. There is no need to bleed air. Therefore, continuous measurement of the potential can be accurately performed under stable water flow conditions without stopping water flow in the pipe. In addition, since the tip portion can be formed into a thin shape, when the reference electrode is inserted deeply, it is possible to reduce disturbance of flow caused by narrowing of the flow path, and blockage of piping due to clogging of foreign matter. Danger can be reduced. Furthermore, there is no fear of electrode damage, which is a concern when inserting and tightening the glass reference electrode deeply.

When using the reference electrode installation device of the present invention,
Since the water-passing portion of the support has a closed structure except for the pipe connection ports at both ends, it can be suitably used even when the water pressure is high or when the deaerated fluid is passed. When the reference electrode installation device of the present invention is used, the reference electrode can be removed at the electrode fixing portion and does not affect the water flow system, so that the reference electrode can be replaced without stopping water flow. be able to. Also, when replenishing or replacing the gel-like substance in which the electrolyte filled in the container of the reference electrode installation device is dissolved, the reference electrode is removed at the electrode fixing part, and the electrolyte is not affected without affecting the water flow system. Can be replenished or replaced with a gel-like substance in which is dissolved. Furthermore, in the reference electrode installation device of the present invention,
By using the same type of electrolyte as the internal solution of the reference electrode to be fixed to the gel-like substance in which the electrolyte to be filled therein is dissolved, and by making the concentration of the electrolyte component in the gel-like substance equal to the internal solution of the reference electrode, Since the transfer of the electrolyte component of the internal solution of the electrode to the outside is suppressed, it is possible to continuously measure the potential over a long period of time without replacing the reference electrode.
In the reference electrode installation device of the present invention, the gel-like substance in which the electrolyte filled in the container is dissolved has sufficient conductivity, does not itself cause an electrochemical reaction, and water or water flowing through the water passage section. Since it does not react with the solvent, and the potential measurement result highly correlated with the reference electrode installation device filled with the electrolyte aqueous solution inside the previously developed container can be obtained, it is possible to accurately determine the corrosion tendency of the piping. it can. In addition, since the elution rate of the electrolyte from the gel-like substance in which the electrolyte is dissolved through the ion-permeable portion is much smaller than that in the case of using the electrolyte solution, the potential measurement can be continued without maintenance for a long period of time. Can be done.

[0011]

EXAMPLES The present invention will be described in more detail with reference to the following Examples, which should not be construed as limiting the present invention. Example 1 and Comparative Example 1 100 parts by weight of a 25.5% by weight aqueous potassium chloride solution
The mixture was heated to ℃, and 70 parts by weight of a washing paste containing polyvinyl alcohol as a main component [Synthetic washing paste New One-Touch Nol manufactured by Diamond Paste Co., Ltd.] was added and uniformly dissolved.
The mixture was poured into a container having a shape shown in FIG. 1 attached to a stainless steel (SUS304) pipe, and cooled to prepare a gel-like substance in which potassium chloride was dissolved. An Ag | AgCl | saturated KCl reference electrode was immersed in the gel-like substance in this container, and fixed in the electrode fixing part. A 25.5% by weight aqueous solution of potassium chloride was placed in a container having the shape shown in FIG.
A | AgCl | saturated KCl reference electrode was immersed and fixed in the electrode fixing part. Using a reference electrode (Example 1) immersed in a gel substance in which potassium chloride was dissolved while passing water through a stainless steel pipe, and a reference electrode (Comparative Example 1) immersed in an aqueous potassium chloride solution, every other day The corrosion potential was measured nine times in total. The corrosion potential measured with a reference electrode immersed in a gel-like substance in which potassium chloride was dissolved was 2 days on the first day.
0.0 mV, 12.8 mV on day 9 and 14.8 on day 17
mV. The corrosion potential measured with the reference electrode immersed in the aqueous potassium chloride solution was 24.9 mV on the first day, 17.9 mV on the ninth day, and 19.7 mV on the 17th day. Table 1 shows the measured values of the corrosion potential by both electrodes and the difference between the measured values.

[0012]

[Table 1]

From the results shown in Table 1, the corrosion potential measured with a reference electrode immersed in an aqueous solution of potassium chloride was always higher than the corrosion potential measured with a reference electrode immersed in a gel-like substance in which potassium chloride was dissolved. The average of the difference between the nine sets of measured values is 5.07 mV, but the standard deviation is as small as 0.16 mV. Therefore, even if a reference electrode immersed in a gel substance in which potassium chloride is dissolved is used, an aqueous solution of potassium chloride can be used. It can be seen that highly reliable measurement is possible as in the case of using the reference electrode immersed in the sample. Example 2 In the same manner as in Example 1, 100 parts by weight of a 25.5% by weight aqueous solution of potassium chloride was heated to 70 ° C., and a washing paste containing polyvinyl alcohol as a main component [Synthetic washing made by Diamond Paste Industry Co., Ltd.] Glue New One Touch Noll] was added and uniformly dissolved, and then poured into a container having the shape shown in FIG. 1 and cooled to prepare a gel-like substance in which potassium chloride was dissolved. Simulated cooling water in which the tip of the container is placed in a beaker (simulated water used for cooling in a chemical plant or the like: pH 8, calcium hardness 280 mg / l, M alkalinity 240 mg / l, magnesium hardness 160 mg / Liter, water temperature of 25 ° C.), and the amount of chloride ion eluted into water from the ion-permeable portion was measured. The chloride ion elution rate was 0.56 mg / day. Comparative Example 2 Instead of a gel-like substance in which potassium chloride was dissolved, 25.
The amount of chloride ion eluted from the ion-permeable portion into water was measured in the same manner as in Example 2 except that a 5% by weight aqueous solution of potassium chloride was used. The chloride ion elution rate is 2.5
It was 5 mg / day. From the results of Example 2 and Comparative Example 2, the elution rate of chloride ions from the reference electrode installation device of the present invention using a gel-like substance in which potassium chloride was dissolved was determined by the chloride ions previously developed by the present inventors. About 22 times the elution rate of chloride ion from the reference electrode installation device using potassium aqueous solution
%, And it is estimated that the frequency of maintenance such as replacement of the medium in which the reference electrode is immersed is reduced to about one-fifth. Ag used in Example 1 and Comparative Example 1 | Ag
The chloride ion contained in the internal solution of the Cl | saturated KCl reference electrode was about 800 mg, and if chloride ion corresponding to the amount contained in the internal solution of the reference electrode was eluted, maintenance was required. In a reference electrode installation apparatus using an aqueous potassium chloride solution, maintenance is required in about 10 months, whereas in the reference electrode installation apparatus using a gel substance in which potassium chloride is dissolved in Example 1, the maintenance frequency is low. It is estimated that the maintenance frequency is about once every four years, and the maintenance frequency can be greatly reduced.

[0014]

By using the apparatus for setting a reference electrode for corrosion potential measurement of the present invention, the electrolyte component of the solution inside the electrode migrates from the detection section at the tip of the reference electrode, and the measurement accuracy of the reference electrode is reduced. It is possible to solve the problem of potential measurement value abnormality due to air bleeding of the detection part of the reference electrode tip, installation of bypass pipe as in the prior art, and installation of reference electrode with valve opening and closing work for each potential measurement , There is no need to remove. Further, even under a degassed environment or a pressurized environment, it is possible to continuously measure the corrosion potential of a metal pipe. In addition, by immersing the reference electrode in a gel-like substance in which the electrolyte is dissolved, elution of the electrolyte through the ion permeable portion into the water flow is suppressed, and the concentration of the electrolyte component inside the reference electrode installation device is increased. It can be kept constant over the period, and the maintenance frequency of the reference electrode installation device can be reduced. Further, it is possible to reduce the influence of corrosion on the metal pipe due to elution of the electrolyte into the channel system.

[Brief description of the drawings]

FIG. 1 is a side view and a cross-sectional view of one embodiment of a reference electrode installation device of the present invention.

FIG. 2 is a side view and a cross-sectional view of another embodiment of the reference electrode installation device of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Container main body part 2 Electrode fixing part 3 Tip part 4 Ion permeable part 5 Support body 6 Water passage part 7 Pipe connection port 8 Detecting part 9 Gel-like substance 10 Reference electrode 11 Male screw 12 Side pipe

Claims (1)

[Claims] An electrode fixing portion having an electrode fixing portion at one end of the container body and a tip portion at the other end, wherein a reference electrode is immersed in a gel-like substance in which an electrolyte filled therein is dissolved. Wherein the tip of the tip is made of an ion-permeable solid material, and the tip projects from the water-passing portion and is installed.