JPH04313378A - Antifouling device - Google Patents

Abstract

PURPOSE:To prevent danger wherein chlorine is generated by electrolysis of seawater by controlling the electric potential of an anode in the noblest part. CONSTITUTION:In a device wherein a coated conductive layer (anode) 3 with a coated foul part 1, an electrode material (cathode) 4 and a reference electrode 5 are combined and weak DC current is allowed to flow in order to prevent contamination based on sticking of organisms on a marine structural material, the reference electrode 5 is arranged near to the part so that the anode the nearest approaches the cathode.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention prevents marine organisms and scale from adhering to and contaminating marine structures, ships, piping or waterways for seawater transportation, fishing nets, fish nets, or seawater intake screens. This invention relates to improvements in antifouling devices.

0002

[Prior Art] For example, piping that transports seawater for cooling water in power plants, screens at seawater intake ports, the sides of ships, piers,
Portions of floating structures, bridge piers, and other marine structures that are constantly in contact with seawater are covered with various seaweeds, barnacles, and other marine organisms such as shellfish, which can cause problems such as a decrease in water intake and a slowdown in ship navigation speed. The problem arises. For this reason, attached marine organisms must be removed periodically, which is a difficult task.

[0003] The mechanism of adhesion of marine organisms follows the order in which microorganisms such as red tide fungi attach to the surface and a biological film is formed, and then larvae of large organisms such as barnacles attach and grow. Therefore, an effective solution to the above problems is to prevent the attachment of microorganisms and the attachment and growth of larvae of large organisms, and various techniques have been proposed for this purpose.

[0004] Most of these methods are aimed at generating chlorine-based ions or copper ions around the object to be decontaminated to kill living organisms that attempt to adhere to the object. Depending on the mode of implementation, these techniques may lead to serious marine pollution and are therefore undesirable.

In view of this situation, the applicant provided a coating layer of a conductive material on the antifouling object, and arranged an electrode material such as titanium and a reference electrode in seawater so as not to come into contact with the coating layer. Then, a DC voltage is applied using the coating layer as an anode and the electrode material as a cathode, and a weak current is passed while controlling the potential difference between the reference electrode and the anode to a certain value, giving an electric shock to microorganisms that come into contact with the coating layer. proposed a device that prevents its adhesion by giving it (Japanese Patent Application No. 2-194257).

[0006] In implementing this technique, we have experienced that chlorine may be generated at the anode despite controlling the anode potential. When we investigated the cause, we found that
It was found that the measured anode potential varied depending on the distance from the cathode to the anode, with the potential being higher closest to the cathode and lower as the distance from the cathode increased. For this reason, Figure 2
As shown in , when the anode potential of the part far from the cathode is measured with a reference electrode and the potential is controlled based on that, the potential of the part close to the cathode becomes higher than expected.
This means that the generation of chlorine cannot be completely prevented.

[0007]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above problems and provide an antifouling device that completely prevents the generation of chlorine.

[0008]

[Means for Solving the Problems] The antifouling device of the present invention, as shown in FIG.
A conductive coating layer (3) that covers parts that require antifouling such as piping (1) or netting, an electrode material (4) placed in seawater so as not to come into contact with this coating layer, and a reference electrode (5). ) and a DC power source (6), the DC power source has the function of controlling the potential difference between the reference electrode and the anode within a certain range, and the coating layer is used as the anode and the electrode material is used as the cathode. It is characterized in that it is connected to a DC power source so that the reference electrode is placed near the part where the anode is closest to the cathode.

In the drawings, (8) represents an insulating material, and (9) represents an insulating material.
indicates seawater.

The antifouling device of the present invention may be appropriately configured depending on the type of object to be antifouled and the surrounding environmental conditions.
The coating layer may be provided directly on the object to be antifouled, or if the object to be antifouled requires insulation, an insulating layer may be provided between the two. In addition, for concrete waterways, bridge piers, ships, and other objects where it is difficult to apply a coating layer directly to the object to be antifouled, we can form a coating layer on an appropriate power supply and apply it to the surface of the object to be antifouled. It may be placed in

Regarding the coating layer, if there is a concern about abrasion, such as in areas where there is a fast flow of seawater, it is preferable to use one lined with a conductive rubber sheet, and if there is little seawater flow, it is preferable to use a conductive rubber sheet lining. A paint film will suffice. A coating layer may be formed on an antifouling object such as a net by a powder lining method using a composition consisting of thermoplastic resin powder and conductive substance powder.

[0012] Electrode materials include titanium base materials plated with noble metals, noble metal oxide coatings,
Alternatively, a rod-shaped body made of silver-lead alloy or carbon-based material is suitable. It is necessary to arrange the electrode material and the covering layer so that they do not come into direct contact with each other, and for this purpose it is preferable to partially cover the electrode material with an insulating material tube or the like.

A commercially available rectifier may be used as the DC power source.

[0014]

[Operation] As shown in Figure 2, the anode potential has a distribution, and a reference electrode is placed in the center of the steel pipe to reduce the potential difference with the anode by 1.
．． When controlled to 2V, the potential difference becomes higher than 1.2V in a portion close to the electrode material. In the example shown in FIG. 2, the maximum potential difference is about 1.5V, and there is a possibility that chlorine will be generated by electrolysis of seawater.

If the reference electrode is placed close to the electrode material, the potential of the highest anode potential can be controlled, thereby completely preventing the generation of chlorine.

[0016]

[Example] Steel pipe with flanges at both ends (caliber “100”)
A", length 1m), 10 pieces were prepared. The inner surface of each is lined with a conductive rubber sheet prepared by mixing 100 parts by weight of chloroprene rubber, 30 parts by weight of carbon black, 40 parts by weight of graphite, a vulcanizing agent, etc., and kneading and extruding the mixture in a conventional manner. A covering layer (3) was provided. The thickness of the sheet after vulcanization is 5 mm. All parts of the steel pipe that are not lined with conductive sheets, such as the flange surface and outer circumferential surface, are covered with an insulating material.

A hole is made near the flange of each coated steel pipe, and a reference electrode made of cylindrical silver whose side surface and rear end are covered with an insulating material and a small hole is made in the insulating material at the rear end is placed in the hole near the flange of the coated steel pipe. It was inserted so that it protruded slightly inside and fixed.

[0018] A donut-shaped plate made of titanium having a surface having the same shape and dimensions as the flange portion was plated with platinum to form an electrode material.

As shown in FIG. 1, the above-mentioned steel pipe was flange-jointed with an electrode material (4) in between to form a test pipe. The anode terminal, cathode terminal, and reference electrode terminal of the DC power supply (6) were wired to the connection terminal, electrode material, and reference electrode (5) provided on each steel pipe using connection cables.

[0020] Seawater was flowed through this pipe at a flow rate of 0.5 m/sec. A direct current of 10 to 30 mA was applied to each steel pipe, and the piping was antifouled while controlling the potential difference between the conductive coating layer and the reference electrode to about 1.2 V in terms of SCE.

[0021] A reference electrode was inserted into the pipe of the above-mentioned antifouling device so that it could move freely, and the anode potential was measured by moving the reference electrode from one end of the pipe to the other. The results were expressed as SCE converted values and shown in FIG. 1.

[0022]

[Effects of the Invention] Since the antifouling device of the present invention can control the maximum value of the anode potential, there is no concern that chlorine will be generated due to electrolysis of seawater.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view for explaining an example of the antifouling device of the present invention and a graph showing the distribution of anode potential.

FIG. 2 is a cross-sectional view for explaining a conventional antifouling device and a graph showing the distribution of anode potential.

[Explanation of symbols]

1. Antifouling object 3 Conductive coating layer 4 Electrode material 5 Reference electrode 6 DC power supply 8 Insulating material 9 Seawater

Claims (3)

[Claims] Claim 1: A conductive coating layer that covers parts of structures, ships, piping, or networks that come into contact with seawater that require antifouling, and an electrode material placed in seawater so as not to come into contact with the coating layer. In an antifouling device that essentially consists of a reference electrode and a DC power supply, the DC power supply has the function of controlling the potential difference between the reference electrode and the anode within a certain range, and the coating layer is used as the anode and the electrode material is used as the cathode. An antifouling device characterized in that it is connected to a DC power source so as to provide a reference electrode near the part where the anode is closest to the cathode. 2. The antifouling device according to claim 1, wherein the coating layer is a lining layer of conductive rubber or conductive resin, or a coating film of conductive paint. 3. The antifouling device according to claim 1, wherein the coating layer includes a power supply body.