JPH04313379A - Antifouling device - Google Patents

Abstract

PURPOSE:To nearly uniform the electric potential of an anode formed of a coated layer in the respective parts, to equalize the antifouling effect in each part of the coated layer and to prevent danger wherein chlorine is generated by electrolysis of seawater by arranging the electrode material as described below. CONSTITUTION:In an antifouling device for preventing sticking of marine organisms by allowing current to flow between a coated conductive layer 3 provided to a body 1 to be antifouled and the electrode material 4 arranged in the vicinity of the coated layer in order to prevent contamination based on sticking of organisms on a marine structural material, a network, a bandlike or a rodlike material is used as the electrode material 4. This electrode material is arranged in a position wherein the area of the part nearly equal in the distance apart from the surface of the coated layer becomes maximum.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention is a method for preventing marine organisms from adhering to and contaminating marine structures, ships, piping or waterways for transporting seawater, fishing nets, cage nets, or screens at seawater intake ports. Concerning improvements in soiling equipment.

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.

Most of these devices are designed to generate chlorine-based ions or copper ions around the object to be decontaminated, thereby killing 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 potential of the anode varies depending on the distance from the cathode to the anode, with the potential closest to the cathode being higher and decreasing farther from the cathode.

For example, in the piping antifouling device shown in FIG. 4, in which a doughnut-shaped electrode material (4) is placed between the flanges as a cathode, as shown in the graph of FIG. The anode potential in the central part is less noble than that in the part closer to the electrode material. As the steel pipe becomes longer, the anode potential at the center drops significantly, and there is a risk that the expected antifouling effect will not be obtained.

[0008] A similar problem occurs when a wide area such as a bridge pier or a waterway must be antifouled.

[0009]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems and provide an antifouling device in which the anode potential of each part of the coating layer is approximately the same.

0010

[Means for Solving the Problems] The antifouling device of the present invention, as shown in FIGS. 1 and 2, requires antifouling of structures, ships, pipes, networks, etc. that come into contact with seawater (9). It essentially consists of a conductive coating layer (3) that covers the area to be covered, an electrode material (4) placed in seawater so as not to come into contact with this coating layer, a reference electrode (5), and a DC power source (6). In the antifouling device, the DC power supply has the function of controlling the potential difference between the reference electrode and the anode within a certain range, and connects the coating layer to the anode,
Connect the electrode material (4) to a DC power source so that the electrode material serves as a cathode.
It is characterized in that a net-like, band-like, or rod-like material is used as the material, and it is arranged at a position where the area of the portion at approximately the same distance from the surface of the covering layer (3) is maximized.

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 (8) may be provided between the two.

[0012] Also, concrete waterways, bridge piers, ships, etc.
For objects for which it is difficult to directly provide a coating layer on the object to be antifouled, the coating layer may be formed on a suitable power supply and placed on the surface of the object to be antifouled.

Regarding the coating layer, if there is a concern about abrasion, such as in areas with fast seawater flow, it is preferable to use a conductive rubber sheet lining, and if there is little seawater flow, a conductive coating layer is preferable. A coating 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.

[0014] Electrode materials include titanium base materials plated with noble metals, noble metal oxide coatings,
Alternatively, silver-lead alloys or carbon-based materials are suitable.
It is necessary to arrange the electrode material and the coating 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 sheet.

[0015] Placing the electrode material at a position where the area of the part where the distance from the surface of the covering layer is approximately the same is maximized means that the distance from the surface of the covering layer to the electrode material is the same as that of the covering layer. This means that any part of the throat is within the specified range. Specifically, the anode potential of the coating layer is controlled over the entire surface within a range of 0.8 to 1.5 V (vs. SCE), preferably 1.0 to 1.2 V (vs. SCE). Hereinafter, the arrangement of electrode materials will be specifically explained using several antifouling devices as examples.

As shown in FIGS. 1 and 2, the antifouling body (
In an antifouling device where 1) is a pipe, a rod-shaped electrode material (4) is covered with an insulating tube, and the tube is cut out at a predetermined interval to partially expose the electrode material. It is preferable to arrange it on the surface of the covering layer (3) parallel to the direction. When the diameter of the pipe is large, two or more electrode materials as described above may be arranged at equal intervals on the inner surface of one pipe.

When the antifouling body (1) is a bridge pier and the covering layer (3) is flat, a net-like electrode material (
4) should be placed.

If the antifouling object (1) is an antifouling device such as a ship, which has a narrow width and a long covering layer (3) at the front and back, the strip-shaped electrode material (4) is attached along the longitudinal direction. Just place it.

[0019]

[Operation] Select the shape of the electrode material from among net, band, or rod shapes in consideration of the shape of the coating layer, and arrange the electrode material so that the distance between the electrode material and each part of the surface of the coating layer is approximately the same. As a result, the anodic potential of the coating layer became uniform. As a result, the antifouling effect of each part of the coating layer became equal.

[0020]

[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 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 in the center of each coated steel pipe, and a reference electrode made of cylindrical silver whose side surfaces and rear end are covered with an insulating material and a small hole is made in the insulating material at the rear end is attached to the tip. It was inserted and fixed so that it protruded slightly into the tube.

A titanium rod with a diameter of 1.0 mm and a length of 90 cm was plated with platinum to serve as an electrode material, and covered with an insulating material.

As shown in FIGS. 1 and 2, the above-mentioned rod was embedded in the coating layer (3) of each steel pipe to such an extent that half of the side surface was hidden. The rod insulating material (7) protruding inside the steel pipe was cut out at 10 cm intervals to expose the electrode material (4). The rod-shaped electrode material was bent and embedded in the rubber of the flange so that it could be connected to the outside at the flange.

Each steel pipe is flange-jointed to form a test pipe, and the anode terminal, cathode terminal, and reference electrode terminal of the DC power supply (6) are connected to the connection terminal, electrode material, and reference electrode (5) provided on each steel pipe. , each wired with a connecting cable.

[0025] Seawater was flowed through this pipe at a flow rate of 0.5 m/sec. The piping was antifouled by passing a direct current of 10 to 30 mA per steel pipe and controlling the potential difference between the conductive coating layer and the reference electrode to be approximately 1.2 V in SCE conversion.

A reference electrode was inserted into the above piping 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. SCE the result
It is expressed as a converted value and shown in Figure 3. From this data, in the above antifouling device, the anode potential of the coating layer is 1.1 to
It can be seen that the voltage is controlled within a range of 1.2V (vs. SCE).

[0027]

Effects of the Invention The antifouling device of the present invention has substantially the same antifouling effect over the entire surface of the coating layer. Therefore, it is not necessary to apply more current than necessary, and there is no need to worry about the anode potential of the coating layer becoming high in some areas, electrolyzing the seawater, and generating chlorine.

[Brief explanation of drawings]

FIG. 1 is a sectional view for explaining an example in which the antifouling device of the present invention is applied to piping.

FIG. 2 is a cross-sectional view taken along the line A-A in FIG. 1.

[Figure 3] Regarding the antifouling device of the present invention shown in Figure 1,
A graph showing the results of measuring the potential distribution of the coating layer.

FIG. 4 is a sectional view for explaining a conventional antifouling device applied to piping.

5 is a graph showing the results of measuring the potential distribution of the coating layer for the conventional antifouling device shown in FIG. 4. FIG.

[Explanation of symbols]

1. Antifouling object 3 Conductive coating layer 4 Electrode material 5 Reference electrode 6 DC power supply 7, 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. Connect to a DC power source so that the electrode material is mesh-shaped, band-shaped, or rod-shaped, and place it at a position where the area of the part that is approximately the same distance from the surface of the coating layer is maximized. Features antifouling equipment. 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.