RU208305U1 - Two-chamber reference electrode for electrochemical protection systems against corrosion of the inner surface of capacitive equipment - Google Patents

Abstract

The utility model relates to electrical engineering and can be used for electrochemical protection against corrosion of the internal surface of capacitive equipment (vertical steel tank (RVS) and horizontal settling tank (GO)), when determining the protective potential of the internal surface of capacitive equipment. The two-chamber reference electrode contains a hollow housing made of a dielectric material with a metal contact fixed inside, filled with an electrolyte and divided into chambers by a partition. The body is made of cylindrical PTFE with an internal thread in the upper part of the body and with an external thread in the lower part of the body, the body is divided into two internal chambers by a porous hygroscopic baffle, the upper chamber of the body is filled with a saturated solution of copper sulphate, and the lower chamber of the body is plugged with a hygroscopic baffle with a lid and filled with conductive gel, the contact is made of a copper rod and placed in the upper chamber of the housing, the upper end of the copper rod is connected by solder to the insulated end of the cable, the upper end of the chamber, together with the junction of the cable and the copper rod, is hermetically fixed and insulated with an epoxy compound. EFFECT: improving the quality of measuring the protective potentials of the internal surface of capacitive equipment (RVS and GO) and providing automatic support for the protective potential at specified values with cathodic protection of the specified equipment, increasing the reliability of the reference electrode with ease of manufacture, increasing the service life, as well as expanding the arsenal technical means for measuring the potential of the inner surface of the container. 1 ill.

Description

The utility model relates to electrical engineering and can be used for electrochemical protection against corrosion of the inner surface of capacitive equipment (vertical steel tank (RVS) and horizontal sump (GO)) when determining the protective potential of the inner surface of capacitive equipment, and in the case of cathodic protection of the inner surface of RVS, automatically maintain the protective potential within the specified limits.

Known reference electrode with a long service life for cathodic protection (patent CN No. 207313710, publ. 2018). The reference electrode contains a ceramic body with a copper wire inside, connected to a cable. A filler made of copper sulfate crystals is placed inside the body. Most of the ceramic body is covered with a sealing enamel.

The disadvantage is the low efficiency of the device. The increased porosity in places where there is no coating does not exclude the possibility of electrolyte leakage, which has passed into a liquid state, its contamination and clogging of pores with dirt, which leads to a deterioration in the operation of the device, and reduces the accuracy of measurements of the protective potential. The device has a limited scope for measuring the potential of the inner surface of capacitive equipment.

Known two-chamber copper-sulfate non-polarizing reference electrode (patent RU No. 2339740, publ. 27.11.2008), containing a non-conductive housing with an electrolytic chamber with a copper rod mounted in it with a signal conductor and a potential sensor mounted on the housing. The body of the electrolytic chamber is filled with an electrolyte consisting of distilled water, copper sulfate and ethylene glycol. The housing contains a ceramic porous diaphragm and an ion-exchange membrane. The body is additionally equipped with a bentonite chamber filled with bentonite clay. At the junction of the chambers, a plastic stabilizing washer, an ion-exchange membrane and a plastic washer with a ceramic porous diaphragm pressed into it are installed. In the lower part, on the body of the bentonite chamber, there is a plastic washer with a ceramic porous diaphragm pressed into it. The diaphragm is designed to provide an electrolytic contact.

The disadvantages of the device are the complexity of the design, insufficient reliability of the reference electrode due to the possibility of liquid getting inside the electrode, oiling of bentonite clay with oil products inside the container, as a result of which there will be an increase in the resistance of the electrolyte and the impossibility of accurately measuring the potential of the inner surface of the container.

A long-acting reference electrode is known (patent RU No. 178871). The reference electrode for corrosion measurements in the electrochemical protection of underground metal structures contains a dielectric body and a perforated cover. Plates made of dissimilar metals are installed in a housing filled with an activator. The activator contains copper sulfate in an amount of 30 wt%, gypsum - 10 wt%, clay - 40 wt% and water in an amount of 20 wt%. The use of gypsum in an amount of 10 wt% does not allow the activator to completely solidify and prevent its leakage into the ground; the difficulty is the use of clay to create a good electrolytic contact. This leads to a low reliability of the reference electrode.

The disadvantages of the device are the insufficient reliability of the reference electrode in liquid media due to the possibility of liquid getting inside the electrode, as a result of which the electrolyte concentration will change, which will lead to a decrease in the measurement accuracy.

A long-acting reference electrode is known (patent RU No. 88355). The reference electrode contains a non-conductive housing with a built-in copper rod with a signal conductor and a potential sensor mounted on the housing. The body consists of an electrolytic chamber filled with an electrolyte containing 35-36 wt.% Copper sulfate, 25-30 wt.% Ethylene glycol, and 5-8 wt.% Thickener - fine silica (aerosil). The diaphragm is made of a plate of porous oxidized titanium with a thickness of 3.5 ÷ 4 mm and an average pore diameter of 0.04 ÷ 0.08 μm.

Insufficient reliability of the long-acting reference electrode is due to a small amount of thickener, which does not prevent the possibility of electrolyte leakage through the porous plate; also, the operation of the reference electrode in liquid media, due to the possibility of liquid entering the electrode, can lead to a change in the electrolyte concentration, and as a consequence to a decrease in the measurement accuracy ...

Known reference electrode containing a non-conductive housing with a copper electrode inside, filled with an electrolyte containing copper salt and ethylene glycol. The body is made of a ceramic material with open porosity, which occupies from 20 to 40% of its area, the electrolyte additionally contains pearlite with the following ratio of components, wt%:

perlite 10-50 copper salt 5-30 water 5-30 ethylene glycol 5-15 (patent RU No. 2706251, publ. 15.11.2019).

The case is made of a ceramic material with open porosity, in which this porosity reaches from 20 to 40% of the area of the entire case, allows the surface of the case to be used as an ion-exchange element to create an exchange of electrical particles between the ground and the copper electrode. The housing with the indicated porosity also serves as a filter against electrolyte contamination by soil moisture. Thanks to this design of the housing, a sufficiently wide contact with the working medium is ensured, and the reliability and accuracy of measurements of the protective potential is increased. The indicated porosity values are optimal. With a lower porosity, the potential of the reference electrode itself decreases, which is unacceptable, because, according to operational regulations, the reference electrode must have a constant value of the base potential, for example, "-100 ± 20 mV" relative to the reference silver chloride electrode with zero potential. With an increase in the degree of porosity of the ceramic body, dirt gets inside the electrolyte, which impairs the operation of the reference electrode. Clogging the pores themselves with dirt can cause the device to malfunction.

The disadvantages of the device are the lack of reliability of the reference electrode in liquid media. The indicated porosity values are optimal for using the electrode in soil. When using the electrode in liquid media, there is a possibility of liquid getting inside the electrode, as a result of which the electrolyte concentration will change, which will lead to a decrease in the measurement accuracy. All copper sulfate reference electrodes are manufactured for use in soil. Therefore, the use of bentonite clay, gypsum, etc. is not acceptable for their use in liquid media. Through porous gaskets and membranes, the container liquid will enter the electrode (pressure in containers up to 5 atm.), Clay, gypsum, etc. will soften, lose their properties, become oiled, and the device will give incorrect information.

The closest is the reference electrode, used in potentiometric studies in a controlled solution, including a hollow body made of dielectric material, with a metal contact reinforced inside, filled with electrolyte and divided into chambers by a partition (av. St. SU No. 138763, publ. 1961). The electrode is made in the form of a transparent glass body with a silver contact. The cavity in which the contact is located - the first chamber is filled with electrolyte, which includes the hardly soluble salt of the contact metal - silver chloride. The electrolyte is separated from the rest of the electrode by a septum - a membrane made of elastic material. The second chamber is also filled with electrolyte and is separated from the controlled solution in the container. The electrolytic contact of the electrolyte in the second chamber with the contact and the controlled solution is carried out through the salt bridges formed between the inner surface of the housing and the adjacent surfaces of the elastic membranes. Due to the presence of membranes, fluctuations in the temperature of the electrode and the pressure of the controlled solution will only lead to deformation of the membranes, without creating a pressure difference that causes the controlled solution to penetrate into the electrolyte and back.

The disadvantages of the device are:

- low efficiency and narrow field of application due to the impossibility of using the electrode inside the capacitive equipment when fully immersed in a liquid medium;

- low service life due to sensitivity to changes in pressure and temperature, as well as due to the fragile material of the body;

- high material costs due to the use of a silver contact.

The technical objectives of the utility model are to increase the efficiency of the reference electrode by improving the quality of measurements of the protective potentials of the inner surface of the capacitive equipment (RVS and HE) and to ensure automatic support of the protective potential in the specified values during cathodic protection of the inner surface of the capacitive equipment, to increase the reliability of the reference electrode when simplicity of manufacture, reduction of costs for the process of corrosion protection of RVS and HE, increase in service life, as well as expansion of technical means for measuring the potential of the inner surface of capacitive equipment.

Technical problems are solved by a two-chamber electrode for comparison of systems of electrochemical protection of the inner surface of capacitive equipment from corrosion, containing a hollow case made of a dielectric material, with a metal contact fixed inside, filled with electrolyte and divided into chambers by a partition.

The novelty is that the body is made of cylindrical fluoroplastic with an internal thread in the upper part of the body and with an external thread in the lower part of the body, the body is divided into two internal chambers by a porous hygroscopic partition, the upper chamber of the body is filled with a saturated solution of copper sulfate, and the lower chamber of the body plugged with a hygroscopic partition with a lid and filled with electrically conductive gel, the contact is made of a copper rod and placed in the upper chamber of the housing, the upper end of the copper rod is connected with solder to the insulated end of the cable, the upper end of the chamber, together with the junction of the cable and the copper rod, is hermetically fixed and insulated with epoxy compound ...

The figure shows a general view of a two-chamber reference electrode of systems for electrochemical protection of the inner surface of capacitive equipment from corrosion.

The essence of the utility model is as follows.

The two-chamber reference electrode of the systems of electrochemical protection of the inner surface of the capacitive equipment against corrosion contains a hollow body 1 made of a dielectric material, for example, from a fluoroplastic with a metal contact 2 fixed inside. hermetically sealed cable outlet with an epoxy compound housing, and with an external thread in the lower part of the housing. The diameter of the body is made from 30 mm to 50 mm. The body is divided into two internal chambers by a porous hygroscopic partition 3. The upper chamber of the body is filled with a saturated solution of copper sulfate 4. The lower chamber is filled with electrically conductive gel 5. A hygroscopic plug 6 is installed in the end of the lower chamber, which is pressed against the body by a cover 7 to create an electrolytic bond in the cover make a hole. As an electrically conductive gel 5, gelatin is used, for example, which will allow the reference electrode to remain operational even if liquid gets inside the lower chamber. The contact is made of a copper rod 2. The rod is made of a copper rod or wire with a diameter of 3-5 ° mm, with a length equal to the inner cavity of the upper chamber. The upper end of the copper rod is soldered to the insulated end of the cable 8. The junction of the cable and the copper rod is sealed in the upper end of the chamber with epoxy
compound 9.

The two-chamber reference electrode allows to improve the quality of measurements of the protective potentials of the inner surface of capacitive equipment (RVS and HE) and to provide automatic support of the protective potential in the specified values during cathodic protection of the internal surface of the RVS, to increase the reliability of the reference electrode with ease of manufacture, to reduce material costs for the protection process against corrosion of VST and HE, increase the service life, as well as expand the arsenal of technical means for measuring the potential of the inner surface of a container filled with a liquid medium.

A two-chamber reference electrode of the systems of electrochemical protection of the inner surface of the capacitive equipment from corrosion is assembled in the following sequence.

A copper rod with a soldered insulated cable outlet is installed through the upper end of the fluoroplastic cylindrical body. Insulated conductor of KPBP cable with a diameter of 11 mm. The cable gland is sealed by pouring an epoxy compound while sealing the upper end of the housing. For tight adhesion of the epoxy compound to the material of the electrode body, a thread is made on the inner surface of the upper part of the upper chamber, providing a surface roughness for reliable adhesion of the epoxy compound. Invert the electrode. The upper chamber is completely filled with a saturated solution of copper sulfate CuSO ₄ . The upper chamber is sealed (pressed in) with a porous ceramic hygroscopic partition-spacer dividing the body into two chambers of equal volumes. The second chamber is filled with an electrically conductive gel such as gelatin. A porous ceramic hygroscopic plug is installed (pressed in) into the end of the body. Sealing of the hygroscopic plug is provided by a gasket, which is pressed by a fluoroplastic cap screwed onto the lower end of the electrode body along the external thread. To create an electrolytic bond, a hole is made on the cover.

The reference electrode is fixed inside the RVS or HE and the cable is removed from the container. In the case of cathodic protection, the electrode is connected to the cathodic protection station.

The two-chamber reference electrode provides high quality measurements of the protective potentials of the inner surface of the capacitive equipment (RVS and HE) and provides automatic support of the protective potential in the specified values during cathodic protection of the internal surface of the RVS and HE, the design of the reference electrode provides an increase in the reliability of the reference electrode, and as a consequence an increase in the overhaul period, which makes it possible to revise the reference electrode during the period of shutdown of the capacitive equipment for repairs and preventive maintenance, established by the regulations, in five years, with ease of manufacture, a decrease in the cost of the process of corrosion protection of RVS and HE, an increase in the service life, and also expands the arsenal technical means for measuring the potential of the inner surface of the container.

Claims (1)

A two-chamber reference electrode for electrochemical protection systems of the inner surface of capacitive equipment against corrosion, containing a hollow body made of a dielectric material, with a metal contact fixed inside, filled with electrolyte and divided into chambers by a partition, characterized in that the body is made of cylindrical fluoroplastic with an internal thread in the upper part of the body and with an external thread in the lower part of the body, the body is divided into two internal chambers by a porous hygroscopic partition, the upper chamber of the body is filled with a saturated solution of copper sulfate, and the lower chamber of the body is plugged with a hygroscopic partition with a lid and filled with electrically conductive gel, the contact is made of a copper rod and is placed in the upper chamber of the housing, the upper end of the copper rod is soldered to the insulated end of the cable, the upper end of the chamber, together with the junction of the cable and the copper rod, is hermetically fixed and insulated with an epoxy compound sound.

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