JP4789043B2 - Seawater electrolyzer - Google Patents

Description

  The present invention relates to a seawater electrolysis apparatus in which scale is less likely to adhere to and accumulate on a cathode when electrolyzing seawater to produce electrolytically treated water containing a chlorinated oxidant.

  Seawater is electrolyzed by applying a DC voltage between the anode and cathode installed in the electrolytic cell, and marine organisms such as mussels, barnacles, and algae are attached to seawater cooling waterways and cooling equipment such as power plants. The technology to prevent is conventionally employed.

  Such electrolytic cells include a single electrode type electrolytic cell in which individual electrodes are connected to a DC power source to supply power, and a bipolar electrode type electrolytic cell in which a DC power source is connected to electrodes at both ends to supply power.

  Of these, the monopolar seawater electrolyzer is more complex as the size increases, and requires a large current to supply power to each electrode, but it is a bipolar seawater electrolyzer that supplies power only to the electrodes at both ends. Then, there is an advantage that a small current is sufficient. For example, when the current required for seawater electrolysis antifouling is compared between electrolytic cells in which 10 sets of anodes and cathodes are installed, a bipolar seawater electrolytic cell requires one-tenth of a monopolar seawater electrolytic cell. . For this reason, there is also an advantage that the DC power supply device may be downsized.

  On the other hand, however, the bipolar electrolyzer has a drawback in that the accumulation of scale is larger than that of the monopolar seawater electrolyzer because current leakage occurs between the electrodes or between the electrode and the tank wall.

In order to overcome the shortcomings of the bipolar seawater electrolysis tank, Japanese Patent Application Laid-Open No. 2002-186970 discloses a plurality of electrodes arranged to electrolyze a solution to be electrolyzed, a chamber frame in which the electrodes are stored, There is disclosed an invention of a bipolar electrolytic cell characterized in that a part or all of the peripheral edge of the electrode is covered with an insulator.
JP 2002-186970 A

  However, even if a part or all of the peripheral edge of the electrode is covered with an insulator, the leakage current increases as the electrolytic current increases, and the scale attached to the insulator increases.

  The present invention relates to a seawater electrolysis apparatus that electrolyzes salt-containing water to produce electrolytically treated water containing a chlorine-based oxidant, and prevents adhesion of scales generated by seawater electrolysis to electrodes and surrounding insulators. In particular, an object of the present invention is to provide a seawater electrolysis apparatus suitable for a bipolar electrolytic cell.

  In order to achieve the above object, the seawater electrolyzer was configured as follows.

1. Seawater electrolysis in which an anode and a cathode are opposed to each other inside the electrolytic cell at a predetermined interval, and seawater introduced into the electrolytic cell is electrolyzed with the anode and the cathode to generate electrolytically treated water containing a chlorinated oxidant. In the apparatus, a second cathode is provided on the inner surface of at least one of the pipes connected upstream and downstream of the electrolytic cell, and leakage current leaking from the anode is absorbed by the second cathode.
Further, in the seawater electrolysis apparatus, the cathode of the second DC power supply device is connected to the cathode, the anode of the second DC power supply device is connected to the second cathode, and the leakage current leaking from the anode is absorbed by the second cathode. It was decided.

  The second cathode provided on the inner surface of the pipe is a. A part of the insulation coating on the inner surface of the metal pipe is stripped to expose the metal surface; b. Affixing a metal piece to the inner surface of the metal pipe and insulatingly coating the inner surface of the metal pipe other than the surface of the metal piece; c. A metal rod or the like is projected inside the metal pipe, and the surrounding inner surface of the metal pipe is insulated and coated. The method for forming the second cathode is not limited to such a method.

  Further, the metal piece to be affixed to the inner surface of the pipe, the metal rod that protrudes into the pipe, etc. may be the same type of metal as the metal pipe or a different type of metal, such as a corrosion-resistant metal.

2. Seawater electrolysis in which an anode and a cathode are opposed to each other inside the electrolytic cell at a predetermined interval, and seawater introduced into the electrolytic cell is electrolyzed with the anode and the cathode to generate electrolytically treated water containing a chlorinated oxidant. In the apparatus, the inner surface of at least one of the pipes connected upstream and downstream of the electrolytic cell is formed on the second cathode, and the leakage current leaking from the anode is absorbed by the second cathode. That is, a pipe whose inner surface is not covered with insulation is connected to either or both of the upstream and downstream sides of the electrolytic cell.

  When the inner surface of the pipe is not made of a corrosion-resistant metal, the length of the pipe is a length that is electrically protected by a leakage current leaking from the anode. For example, in the case of a steel pipe, the pipe length is 10 times the pipe inner diameter. Or less.

In this way, it is possible to prevent the pipe as the second cathode from being corroded by seawater containing residual chlorine.

3. In the seawater electrolysis apparatus described above , the second DC power supply apparatus has a smaller capacity than the water electrolysis DC power supply connected between the anode and the cathode.

  In addition, this invention is not restricted to a bipolar electrode electrolytic cell, You may apply to a monopolar electrolytic cell. The seawater electrolyzer is not particularly limited as long as it is an apparatus that electrolyzes seawater to produce electrolytically treated water containing a chlorinated oxidant, such as an electrolyzer for producing sterilized water.

  The seawater electrolysis apparatus according to the present invention has the following effects.

  The second cathode is provided on the inner surface of either or both of the upstream and downstream pipes connected to the electrolytic cell, or the inner surface of the piping is used as the second cathode, so that from the anode in the electrolytic cell during seawater electrolysis The leakage current that leaks is absorbed by the second cathode, and it is possible to prevent the scale due to the leakage current from adhering to the insulator covering the cathode and the vicinity of the cathode peripheral edge.

  When the positive electrode of the second DC power supply device is connected to the cathode and the negative electrode is connected to the second cathode, the leakage current during seawater electrolysis is more strongly absorbed by the second cathode and the leakage current of the electrolysis current flows into the cathode. This can prevent the scales caused by the leakage current from adhering to the cathode and the insulator covering the cathode peripheral edge more effectively.

  The best embodiment of the seawater electrolysis apparatus according to the present invention will be described with reference to the drawings.

  As shown in FIG. 1, the seawater electrolysis apparatus 1 of the present invention includes an electrolytic cell 2 provided with an electrode 3, a DC power supply device 9 that applies a DC voltage to the electrode 3, an introduction pipe 30 that introduces seawater into the electrolytic cell 2, Anti-fouling which is composed of a supply pipe 31 for sending the electrolyzed water treated from the electrolyzer, etc., and produces electrolyzed water containing a chlorine-based oxidant from seawater, for example, preventing marine organisms from adhering in the water channel It is used for a washing water generating device for generating washing water for washing an apparatus or marine products.

  The electrode 3 is made of metal oxide coating or platinum plating, and is arranged in parallel with the flow of seawater flowing in the electrolytic cell 2, and at the front and rear end portions along the flow of seawater of each electrode 3, An electrical insulating plate 7 is attached. The electrical insulating plate 7 holds the electrode 3 in a predetermined position inside the electrolytic cell 2 and suppresses the generation of leakage current from the end of the electrode 3.

  The electrolytic cell 2 is a bipolar electrolytic cell, and the positive electrode of the DC power supply device 9 is connected to one of the electrodes 3 arranged outside to form the anode 4, and the negative electrode of the DC power supply device 9 is connected to the other electrode 3. Connected to form the cathode 5. In this way, when the DC power supply device 9 is connected between the anode 4 and the cathode 5 and a voltage is applied, the intermediate electrode 6 disposed between the anode 4 and the cathode 5 has a surface facing the anode 4 as a cathode. The back surface of the cathode serves as an anode, and the anode and the cathode are sequentially formed on the entire electrode 3 so as to face each other.

  The introduction pipe 30 and the supply pipe 31 are connected to the electrolytic cell 2 by fastening the introduction tube flange 30F and the supply tube flange 31F to the flange 2F of the electrolytic cell 2 with bolts and nuts (not shown), respectively.

As shown in FIG. 1, the second cathode 10 is installed in the introduction tube 30 via the electrical insulator 11. The second cathode 10 may be installed in a plate shape on the inner surfaces of the introduction tube 30 and the supply tube 31 . In this case, the inner surfaces of the introduction tube 30 and the supply tube 31 excluding the place where the second cathode 10 is installed, and the inner surface of the electrolytic cell body 2S are insulated by laying rubber lining or the like .
A second DC power supply 91 is connected between the second cathode 10 and the cathode 5.

The second cathode 10 is close to the circuit of the leakage current generated in the electrode 3, is provided at a position that reliably absorbs the leakage current and does not significantly affect the electrolysis action of seawater at the electrode 3. Such a position is appropriately set in consideration of the voltage applied between the electrodes 3 by the DC power supply device 9, the electrode interval between the electrodes 3, the number of electrodes, the area of the electrodes, the shape and material of the electrical insulating plate 7, and the like. When the second cathode 10 is installed in a plate shape , the inflow current density is 1 A / dm 2 or more as described in Japanese Utility Model Publication No. 4-17562 filed by the present applicant. It is desirable that the surface area be set .

Reference numeral 8 denotes an electric wire for connecting the second cathode 10 to the cathode 5 and the DC power supply device 9. As already mentioned, the inlet pipe 30 and the supply pipe 31 and the electrolytic bath 2, inlet flange 30F, are connected by tightening a bolt nut supply pipe flange 31F and the electrolyzer flange 2F.

  Next, the operation of the seawater electrolysis apparatus 1 will be described.

  A DC power supply device 9 is connected to the electrolytic cell 2, a voltage is applied between the anode 4 and the cathode 5, and seawater is introduced into the electrolytic cell 2 from the introduction tube 30. Then, seawater is electrolyzed while passing between the electrodes 3 and 3, and electrolytically treated water containing chlorine-based oxide (sodium hypochlorite) is generated from the seawater.

  The electrolytically treated water that has flowed out of the seawater electrolysis apparatus 1 through the supply pipe 31 is mixed with, for example, seawater as cooling water, thereby preventing marine organisms from attaching to and growing in the cooling apparatus.

In this case, since the second cathode 10 is installed in the introduction tube 30 via the electrical insulator 11, the leakage current generated from the anode 4 and the intermediate electrode 6 is absorbed by the second cathode 10. The leakage current absorbed by the second cathode 10 flows to the negative electrode of the DC power supply device 9 via the electric wire 8. As a result, no leakage current flows into the cathode 5 and the intermediate electrode 6, and no scale is generated around the electrical insulating plate 7 due to the leakage current.

This is the same even when the second cathode 10 is installed in the form of a plate on the inner surface of the introduction tube 30 and the supply tube 31. In this case, the surface area of the second cathode 10 is a current density of 1 A / dm 2 or more. If the scale is set to, even if the scale adheres to the second cathode 10, the adhesion of the scale is weak, and the scale does not accumulate due to separation from the second cathode 10 due to the flow of seawater.

  A second DC power supply 91 is connected between the second cathode 10 and the cathode 5, and this second DC power supply 91 absorbs the leakage current during seawater electrolysis more strongly into the second cathode. In order to prevent the leakage current of the electrolysis current from flowing into the cathode, a capacitor having a smaller capacity than the DC power supply device 9 is installed.

According to the seawater electrolysis apparatus 1 described above, when the second cathode 10 is set to a lower potential than the cathode 5 by the second DC power supply device 91, and when direct current voltage is applied to the electrode 3 by the DC power supply device 9, seawater electrolysis is performed, The leakage current generated from the anode 4 and the anode of the intermediate electrode 6 is more strongly absorbed by the second cathode 10. In addition, a current C from the cathode 5 to the second cathode 10 is generated, and the current C becomes a current in a direction opposite to the leakage current. Therefore, the leakage current is cut off, and scale adhesion is more effectively prevented.

  Accordingly, it is possible to more effectively prevent the scale from adhering to the periphery of the cathodes of the cathode 5 and the intermediate electrode 6 and the periphery of the electrical insulating plate 7 due to the leakage current than in the above example.

  In the experiment, since the second cathode 10 is provided, the amount of scale attached to the electrical insulating plate 7 on the cathode side is almost ½ that of the case without the second cathode, and the second DC power supply 91 is installed in the second. When a voltage was applied while connected to the cathode 10, the amount of scale adhesion was further reduced by 60%.

When the second cathode 10 is installed on the inner surfaces of the introduction tube 30 and the supply tube 31 in the form of a plate , the second cathode 10 may be provided if the surface area of the second cathode 10 is set to a current density of 1 A / dm 2 or more. Even if a scale adheres to the scale 10, the adhesion of the scale is weak, and the scale does not accumulate due to separation by flowing seawater.

Furthermore, although not shown in figure, the other example of the seawater electrolysis apparatus of this invention is demonstrated.

  In the seawater electrolysis apparatus 1, a second cathode pipe 12 is mounted between the electrolytic cell 2 and the introduction pipe 30 and between the electrolytic cell 2 and the supply pipe 31. The second cathode pipe 12 may be a steel pipe ordinarily used as a pipe, or may be composed of another metal, for example, a corrosion-resistant metal or an alloy. However, the electrolytically treated water containing a chlorinated oxidant is stronger in corrosive power than normal seawater, and steel and the like corrode early. Therefore, when using a steel pipe or the like for the second cathode pipe 12, the second cathode The length of the pipe 12 for use is set to a length equal to the distance at which the anticorrosion is performed by the leakage current generated from the anode 4 and the intermediate electrode 6, for example, a length shorter than 10 times the inner diameter of the pipe.

  Other configurations of the seawater electrolysis apparatus 1 are the same as those already described. Even if comprised in this way, since the 2nd cathode piping 12 absorbs a leakage current, generation | occurrence | production and adhesion of the scale to the cathode 5 vicinity can be prevented effectively.

It is sectional drawing which shows the seawater electrolysis apparatus concerning this invention.

DESCRIPTION OF SYMBOLS 1 Seawater electrolysis apparatus 2 Electrolysis tank 2F Electrolysis tank flange 2S Electrolysis tank body 3 Electrode 4 Anode 5 Cathode 5T Cathode terminal 6 Intermediate electrode 7 Electrical insulation board 8 Electric wire 9 DC power supply device 10 Second cathode 11 Electrical insulator 12 For second cathode Piping 12F Piping flange 30 for the second cathode Introducing pipe 30F Introducing pipe flange 31 Supply pipe 31F Supply pipe flange 91 Second DC power supply

Claims (3)

Seawater in which an anode and a cathode are opposed to each other inside the electrolytic cell at a predetermined interval, and seawater introduced into the electrolytic cell is electrolyzed with the anode and the cathode to generate electrolytically treated water containing a chlorine-based oxidant. In the electrolyzer,
A second cathode is provided on the inner surface of at least one of the pipes connected upstream and downstream of the electrolytic cell, the leakage current leaking from the anode is absorbed by the second cathode, and the cathode is connected to the second DC power supply device. A seawater electrolyzer characterized in that a positive electrode is connected, a negative electrode of the second DC power supply device is connected to the second cathode, and a leakage current leaking from the anode is absorbed by the second cathode . Seawater in which an anode and a cathode are opposed to each other inside the electrolytic cell at a predetermined interval, and seawater introduced into the electrolytic cell is electrolyzed with the anode and the cathode to generate electrolytically treated water containing a chlorine-based oxidant. In the electrolyzer,
The inner surface of at least one of the pipes connected upstream and downstream of the electrolytic cell is formed in the second cathode, the leakage current leaking from the anode is absorbed by the second cathode, and the second DC power supply device is absorbed by the cathode The seawater electrolysis apparatus is characterized in that a negative electrode of the second DC power supply device is connected to the second cathode, and a leakage current leaking from the anode is absorbed by the second cathode . The seawater electrolysis apparatus according to claim 1 or 2 , wherein the second DC power supply device has a smaller capacity than a DC power supply for water electrolysis connected between the anode and the cathode.