JPH037396Y2 - - Google Patents

Description

[Detailed explanation of the idea] "Industrial application field" This invention relates to a reference electrode for a seawater cooler.

``Conventional technology'' Seawater coolers cool the tube to the desired temperature by passing seawater inside the tube and the substance to be cooled outside, but since seawater is used as an electrolyte, preventing corrosion on the inside of the tube is important for equipment maintenance and management. It's getting old.

Usually, as a countermeasure to these problems, an electrode is installed inside the water chamber,
This is connected to the positive pole (plus) of a DC power supply, and the object is connected to the negative pole (minus), and a corrosion protection current is flowed from the electrode into the inner surface of the tube through seawater to perform galvanic corrosion protection.

Since the tube inlet or outlet is close to the electrode, the anticorrosive current tends to flow in, and if the adjustment is incorrect, the excessive anticorrosive current will precipitate dissolved matter in the seawater, which is undesirable.

For such adjustment, a reference electrode is installed to detect the anti-corrosion potential, but in the past, only the ends of the tube were measured, but corrosion occurred near the center of the tube despite the good anti-corrosion potential. Therefore, when the potential distribution inside the tube was investigated, it was found that the anti-corrosion potential was not maintained near the center of the tube. Therefore, the most effective corrosion prevention method requires detecting the corrosion protection potential near the center of the tube and maintaining and managing it at the desired corrosion protection potential.

In this case, the environment is normal temperature to 90℃, normal pressure to 5kg/
The conditions are a high temperature of cm ² G and a flow rate.

As an existing reference electrode that can be applied,
There is a silver/silver chloride reference electrode No. 170262.

FIG. 3a shows an embodiment in which the silver/silver chloride reference electrode is applied to measure the potential at the end of a tube.

In the figure, 1 is the above-mentioned silver/silver chloride reference electrode, and as shown in the enlarged view of figure b, this is filled with silver chloride crystals 3 melted and cast into a silver pipe 2. Connect the conductor 4 to the .

This electrode 1 is wrapped in a heat-shrink tube 15, embedded in a filler 6 made of insulating resin in the inner tube 5, and attached to the protective resin pipe 7 with a set screw 8.
Fix it with.

In the figure, numeral 9 indicates an insulating cover covered with the conductive wire (copper) 4.

The pipe 7 is placed near the entrance of the tube 10, as shown, and the potential is measured.

In the figure, 11 indicates a substance to be cooled, 12 indicates a tube plate, and 13 indicates seawater (electrolyte).

``The problem that the invention aims to solve'' However, conventional devices that use AgCl electrodes and automatically adjust the potential have been used for ship shells, condensers, buried pipes, etc. Compared to that of , it is simple and has less fluctuation.

For this reason, even if the reference electrode that can be applied to each of the above objects is applied directly to the end of the tube, where the conditions are gentler than the center of the tube, in a seawater cooler, the potential will become unstable in a short period of time, making it difficult to use. do not have.

That is, the molten silver chloride crystals fell off due to thermal expansion. Furthermore, due to temperature changes in the seawater, the resin filled in the connection between the Agcl electrode and the conductor to keep it airtight deteriorates due to thermal expansion, causing the outer cylinder to crack and seawater to infiltrate, resulting in large variations in the detected potential and instability. (For this reason, the contact point between the AgCl electrode and the conductor wire is covered with seawater, and the potentials of the copper and solder are supported, resulting in large variations.) ``Means for solving the problem'' and ``effects'' This proposal describes It was created in view of the above circumstances, and its gist is that a silver wire as a conductor is inserted into the inner surface of a silver pipe and then molten silver chloride is cast to form a silver/silver chloride reference electrode. This method eliminates the above-mentioned falling off of molten silver chloride crystals and the variation in detection potential.

"Example" This will be explained in detail below based on the drawings.

FIG. 1 shows how the potential at the center of the tube is measured using the electrode according to the invention.The electrode 1' is made by passing a silver wire 14 through the inner surface of the silver pipe 2 and casting molten silver chloride into the silver pipe 2. . This is placed in a protective resin pipe 7 via a filler 6, and a silver wire 14 is fixed to the protective resin pipe 7 through a filler 6 inside the pipe 7, and fillers 6' are filled at appropriate intervals. do.

Therefore, the silver wire 14 is protected by the insulating cover 9, and the seawater 13 penetrates into the protective resin pipe 7 and fills it, so that the silver wire 14 is directly exposed to the seawater (electrolyte).
13 is prevented from touching. The corrosion protection potential can be measured at the tube 10 of the seawater cooler by adjusting the lengths of the protective resin pipe 7 and the silver wire 14.
It is possible to measure the potential at any position on the inner surface (even the center).

In addition, 16 in the figure shows a rubber gasket.

According to the present configuration, the silver wire 14 serves as an anchor for the silver chloride crystal 3, and it is prevented from falling off even if it is no longer affected by the holding effect of the silver pipe 7 due to thermal expansion.

In addition, in order to keep the connection between the Agcl electrode and the conductor wire airtight, we have improved the conventional connection between the Agcl electrode and the copper wire so that even if the filling resin cracks, the detected potential will not change. By using a silver wire made of the same material as the AgCl electrode as a conductor, the cause of abnormal potential was removed and reproducible data could be obtained.

In addition, by using Ag-based conductors, the amount of filling resin can be reduced, making work easier and achieving stable performance even when downsized.

Figure 2 is a graph of the sensor thermal stability test.
The vertical axis is the potential of the sensor body (potential compared to a saturated calomel standard electrode), and the horizontal axis is temperature change. The test conditions were seawater using the reference electrode 1' of the present invention shown in FIG. 1, and as shown in the figure, good results were obtained.

``Effect of the invention'' It has become possible to measure the potential at any point inside the seawater cooler tube.

Stable potential measurement is now possible.

Long-term potential measurement is now possible (filling
by free adjustment of Agcl).

Even under conditions with temperature changes, the above
The combination of a reference electrode and an alarm device with these functions not only reduces the number of man-hours required for conventional monthly inspections, but also enables the detection and adjustment of abnormal potentials, improving the corrosion prevention effect and reducing maintenance and management costs. It became possible to reduce the width.

[Brief explanation of the drawing]

Figure 1 is an explanatory diagram of how this product is used, Figure 2 is a diagram of the sensor thermal stability test, and Figures 3 a and b are diagrams that explain how the potential is measured at the end of the tube using the conventional AgCl electrode, with an enlarged view of the main parts. FIG. 1... Silver/silver chloride reference electrode, 1'... Reference electrode,
2...Silver pipe, 3...Crystal, 4...Conducting wire, 5...
... Inner cylinder, 6, 6' ... Filling material, 7 ... Protective resin pipe, 8 ... Stopping screw, 9 ... Insulating cover,
10...Tube, 11...Substance to be cooled, 12...
Tube sheet, 13... seawater (electrolyte), 14... silver wire,
15...Heat shrink tube, 16...Rubber gasket.

Claims (1)

[Scope of utility model registration request] A reference electrode for a seawater cooler, characterized in that a silver wire serving as a conductor is inserted into the inner surface of a silver pipe, and then molten silver chloride is cast to constitute a silver/silver chloride reference electrode.