JP2002275663A - Electrolytic protection process - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a process for electrolytic protection in the atmosphere for secure electrolytic protection of a coated surface. SOLUTION: In the process, a coating is applied to the metallic surface of a protection target, an electrode for electrolytic protection is established as a positive pole on the coated surface via an insulator, and an electric current is applied using the protection target as a negative pole to perform electrolytic protection of the protection target. Here, the electric current generated by a generator attached to a movable part of the protection target is rectified and applied to the electrode and the protection target.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for preventing cathodic corrosion in the atmosphere, and more particularly to a method suitable for cathodic protection of a gantry of a belt conveyor.

[0002]

2. Description of the Related Art An outline of an atmospheric cathodic protection system is shown in FIG. The anticorrosion target 3 is formed by coating a metal surface and applying a coating 4
The electrode 1 for cathodic protection is used as a positive electrode and the object 3 to be used as a negative electrode via an insulator 7, and the power supply 2 is connected to the power supply 2 with a conducting wire 5.
In a state where the metal surface is dried and a liquid film is not formed, no anticorrosion current flows, but there is no need for anticorrosion in a dry state since no rust is generated. Rust develops when the coating surface is wet due to rainfall or the like and the liquid film 6 is formed, but when electricity flows using the liquid film 6 as a medium, the rust of coating film defects is prevented from developing and the life of the coating film is significantly improved. Become longer.

However, a belt conveyor as shown in FIG. 3 has a length of several hundred meters or more, and there is a case where only a motor 15 has a commercial power supply. Therefore, it is necessary to wire the conducting wire 5 for several hundred meters, which greatly increases the cost for installation.
When the length of the conductive wire 5 is long, the conductive wire 5 is often cut in the middle, and it is difficult to maintain the anticorrosion effect.

[0004] In addition, even when already wired along the frame, the current flowing is often a high-voltage alternating current, and is converted to a direct current of about 1 to 20 V required for cathodic protection. Power distribution work, installation of equipment to reduce voltage and installation of direct current conversion equipment are required, and it is necessary to turn off the electricity flowing at the time of power distribution work, and the construction itself is not possible with equipment that is constantly operating In addition, if such a construction is performed on each part that requires cathodic protection, the installation cost increases. If the electric capacity supplied to the anticorrosion target has no margin, construction for increasing the electric capacity of the entire apparatus is also required, and the installation cost further increases.

As a method for solving such a problem, as shown in FIG. 5, an invention in which a solar cell 2 'and a sacrificial electrode 1' are combined as a power source is disclosed (Japanese Patent Laid-Open No. 7-31).
No. 6850). According to the present invention, when the sun is irradiated, corrosion is prevented by the electricity generated by the solar cell 2 ', and at night or when the sun is not irradiated, the power switch is switched by the switch 13 to dissolve the sacrificial electrode 1'. This is a method of preventing corrosion by using electricity. According to the present method, anticorrosion can be performed on the anticorrosion target 16 far from the commercial power supply without the need for the long conductive wire 5.

[0006] However, in the cathodic protection in the atmosphere, since the corrosion proceeds due to rain in rainy weather when the amount of sun irradiation is small or water condensed at night, electricity generated by the solar cell 2 'is not used effectively. The current generated by the erosion of the sacrificial electrode 1 'greatly contributes to corrosion prevention, and the life of the sacrificial electrode 1' is the life of the present system. Further, unlike the anticorrosion target in water or soil, the liquid film 6 formed on the surface of the target 16 in the atmosphere
Is high, the voltage generated by the sacrificial electrode 1 'applied in water and in the soil to protect the sacrificial electrode 1' is too low to narrow the anticorrosion range. Increase. Further, even if the panel of the solar cell 2 'is enlarged in order to secure a sufficient potential even in rainy weather or at night, the cost increases, and the method of fixing the panel becomes difficult.

[0007]

However, the conventional technique has a problem that the cost of installation increases in proportion to the distance in order to carry out the electrolytic protection of an object to be protected in the atmosphere far from the power supply. Accordingly, an object of the present invention is to provide a method of cathodic protection in the atmosphere that can be protected without a commercial power supply.

[0008]

The cathodic protection method of the present invention is as follows. (1) Paint the metal surface of the anticorrosion target, place an electrode for cathodic protection as a positive electrode via an insulator on the coating surface, and conduct electricity using the anticorrosion target as a negative electrode to perform anticorrosion of the anticorrosion target. A method of rectifying a current generated from a generator attached to a moving part of the object to be eroded and energizing the electrode and the object to be protected, (2) generated from the generator The method according to (1), wherein after the current is rectified and the rechargeable battery is charged, the rechargeable battery, the electrode, and the anticorrosion target are energized.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail. As shown in FIG. 1, the rotating body 8 is brought into contact with the moving unit 11, the movement of the moving body 11 is converted into a rotational movement, and the generator 9 is turned to generate power. The rotating body 8 may use a motor that is a power source of the moving unit, or may be provided separately from the motor. Since the electricity generated by the generator 9 is an alternating current, it is converted to a direct current by the rectifier 10 and connected by the conducting wire 5 with the electrode 1 for the cathodic protection and the object 3 to be corroded as the negative electrode. The surface of the anticorrosion target 3 is coated, and the electrode 1 is mounted thereon via an insulator 7.

The material of the anticorrosion target is preferably an iron or steel material because of its easiness of electrocorrosion protection and its many applications. As a material of the coating film, a phenol resin, an acrylic resin, an epoxy resin, a polyurethane resin, or the like can be used. Aluminum, titanium or the like can be used for the electrode for cathodic protection. As the insulator, rubber, resin, ceramics, or the like can be used.

If the moving unit 11 is a facility that constantly moves, the direct current generated from the rectifier 10 can be directly connected to the electrode 1 and the object 3 to maintain a stable corrosion protection voltage. It is possible, but in the case of equipment in which the moving body 11 moves or stops, the storage battery 12 is charged with the rectified current, and when the equipment does not move, it is stabilized by performing cathodic protection by the electricity of the storage battery 12. It is possible to prevent cathodic corrosion in the atmosphere.

The set voltage differs depending on the electric conductivity of the liquid film formed on the surface of the anticorrosion target. In the case of the anticorrosion target which is installed in a normal atmospheric environment and whose surface is coated, 1 to 20 V is applied.
It is preferable to set it in the range. If a high voltage is set when the resistance of the liquid film formed on the surface of the anticorrosion target is low,
When the current flows too much, it becomes over-corrosion-proof around the electrode, and peeling of the coating film occurs, thereby shortening the life of the coating film. On the other hand, when the resistance of the liquid film is high, if the voltage is set to a low voltage, the anticorrosion range in which the current flows becomes narrow, and in order to prevent the entire anticorrosion target from being corroded, it is necessary to install many electrodes, and the installation cost is high. Become.

[0013] The number of electrodes for the cathodic protection to be wired to the rectifier need not be one, and two or more electrodes can be provided.
Increasing the number of cathodic protection electrodes to be wired will reduce the number of generators and rectifiers, but the distance between the cathodic protection electrodes and the rectifiers will be longer, so for each equipment subject to corrosion protection,
The set voltage and electrode wiring may be determined.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIGS. 1 to 3 show an embodiment in which a belt conveyor is protected from corrosion. The surface of the steel base 16 of the belt conveyor is painted, and the electrode 1 for cathodic protection is installed on the coating film 4 via the insulator 7. The composition of the coating film was an epoxy resin, rubber was used as an insulator, and the material of the electrode for cathodic protection was aluminum. An alternating current is generated by a power generator 9 directly connected to a support roll 17 installed on a gantry, and is converted to a direct current by a rectifier 10. The converted DC current is connected by the conductive wire 5 with the electrode for cathodic protection as the positive electrode and the gantry 16 as the anticorrosion target as the negative electrode, and is protected by applying a voltage. By using the supporting roll 17 as the rotating body 8, the moving motion can be reliably converted to the rotating motion, and the apparatus can be simplified. The set voltage was 10 V. The number of the electrodes for cathodic protection to be wired to the rectifier was six.

[0015]

As described above, by using the electricity generated from the moving object of the anticorrosion target as a power source for the anticorrosion, stable and low-cost anticorrosion can be achieved even for equipment far from the commercial power supply. In addition, by combining the storage batteries, stable corrosion prevention can be performed even on equipment in which the movement of the moving body moves or stops.

[Brief description of the drawings]

FIG. 1 is a diagram showing an outline of the present invention using a power generator.

FIG. 2 is a diagram showing an outline of the present invention using a power generator and a storage battery.

FIG. 3 is a side view of a belt conveyor to which the present invention is applied.

FIG. 4 is a view schematically showing a conventional atmospheric cathodic protection method.

FIG. 5 is a view schematically showing a conventional atmospheric anticorrosion method combining a solar cell and a sacrificial electrode.

[Explanation of symbols]

 1: Electrode for corrosion protection 1 ': Sacrificial electrode 2: DC power supply 2': Solar cell 3: Corrosion protection object 4: Coating film 5: Conductive wire 6: Liquid film 7: Insulator 8: Rotating body 9: Generator 10: Rectifier 11: Moving part 12: Rechargeable battery 13: Switching switch 14: Belt 15: Motor 16: Stand 17: Support roll

Claims (2)

[Claims] 1. A metal surface of an object to be protected is coated, an electrode for cathodic protection is installed as a positive electrode via an insulator on the surface of the coating, and electricity is passed using the object to be protected as a negative electrode. The method according to claim 1, wherein a current generated from a generator attached to a moving part of the object to be protected is rectified to supply current to the electrode and the object to be protected. 2. The method according to claim 1, wherein after rectifying the current generated from the generator and charging the rechargeable battery, the rechargeable battery, the electrode and the object to be protected are energized.