BR112013010763A2 - seawater electrolysis system and method - Google Patents

Abstract

"SEAWATER ELECTROLYSIS SYSTEM AND METHOD". This is a seawater electrolysis device that is provided with an electrode (30) that includes an anode (A) that is made of titanium coated with a material of coating containing iridium oxide, a cathode (K), an electrolysis vessel main body (20) that houses the anode (A) and cathode (K), and a power supply unit (40) that passes a current electrical between the anode (A) and the cathode (K) such that an electric current density at the surface of the anode (A) and the cathode (K) is 20 A/dm2 or more, where the water electrolysis device The seawater electrolyzes the seawater in the main body of the electrolysis vessel (20).

Description

"SEAWATER ELECTROLYSIS SYSTEM AND METHOD" Field of Invention The present invention relates to a seawater electrolysis system that has a seawater electrolysis device for generating hypochlorous acid by performing seawater electrolysis as well. refers to a method of electrolysis of seawater. Background of the Invention Thermal power plants, nuclear power plants, seawater desalination plants, chemical plants and others that use a large amount of seawater include parts in contact with seawater. Conventionally, the deposition (adhesion) and proliferation of seaweed and shells in these parts, for example, seawater inlets, piping, condensers and various types of coolers have caused serious problems.

In order to solve the problems described above, a seawater electrolysis device has been proposed which performs the electrolysis of natural seawater to generate hypochlorous acid and fills the hypochlorous acid thus generated into a water inlet. from the sea, thus suppressing the deposition of marine growth (reference to Patent Document 1, for example). The seawater electrolysis device has such a structure that anodes and cathodes, as * electrodes, are disposed within a cabinet-shaped electrolysis vessel main body to distribute the seawater within the vessel main body of electrolysis. As seawater contains chloride ions and hydroxide ions, the electrical current that passes between the anodes and the cathodes produces chlorine at the anodes and sodium hydroxide at the cathodes. The chlorine then reacts with sodium hydroxide to generate hypochlorous acid which is effective in suppressing marine growth adhesion. | In general, an electrode, particularly an anode, that is disposed within an electrolysis vessel of the seawater electrolysis device is constructed using a titanium base plate that is coated with a composite metal with platinum dominant (a material coating with platinum dominant) (reference to Patent Document 2, for example).

Although not yet practically available as a seawater electrolysis device, such a suggestion has been made that a composite metal with dominant iridium oxide, ie, a coating material with dominant iridium oxide, be used as a coating material. coating for an anode for electrolysis (reference to Patent Document 3, for example).

A seawater electrolysis device is also known in which concentrated water having a high concentration of salinity and discharged from seawater concentrating equipment, such as a seawater desalination plant, is used. like treated water. This seawater electrolysis device is the one in which the concentration of hypochlorous acid contained in the electrolyzed water produced by performing the concentrated water electrolysis is increased to decrease the consumption of electricity, thus improving the efficiency of the electrolysis device of seawater and also decrease the size of the seawater electrolysis device (reference to Patent Document 4, for example).

[Prior Art Documents] [Patent Documents] [Patent Document 1] Japanese Patent No. 3389082 [Patent Document 2] Japanese Published Unexamined Patent Application No. 2001-262388 [Patent Document 3) Published Patent Application Japanese unexamined No. H8-85894 [Patent Document 4] Japanese Unexamined Published Patent Application No. H9-294986 õ Summary of the Invention r Problem to be solved by the invention In an electrode coated with a platinum dominant coating material, : due to influences from oxygen generated in the vicinity of an anode and plates (calcium, magnesium, or similar) deposited in the vicinity of a cathode during electrolysis, early erosion of the electrode takes place. Therefore, it is necessary to wash and replace the electrode frequently, resulting in increased maintenance costs.

Furthermore, there is a tendency for chlorine to be generated more efficiently with an increase in the density of electric current at the electrode surface. This tendency is also found in a case where concentrated seawater is introduced into the seawater electrolysis device to generate hypochlorous acid.

However, the amount of oxygen generated in the vicinity of the anode and of plates deposited in the vicinity of the cathode is also increased with an increase in electric current density, resulting in rapid wear of the electrode. As a result, in the electrode coated with a platinum dominant coating material, it is impossible to increase the electric current density at the electrode surface. Thus, it was considered the technical common sense that the maximum value of electric current density is maintained at approximately 15 A/dm?, for example.

As described above, since it is necessary to keep the current density low during electrolysis, generating hypochlorous acid from seawater in sufficient quantity requires the arrangement of many electrodes, resulting in increases in manufacturing and costs. an increase in device size.

The present invention was produced in view of the problems described above, the aim of which is to provide a seawater electrolysis device, a seawater electrolysis system and a seawater electrolysis method capable of improving durability. , of electrodes and also suppress the reduction of effectiveness in the generation of chlorine.

Solution to the problem The inventors have been conducting research on an electrode for a seawater electrolysis device and have concluded that when an electrical current passes through an anode coated with an iridium oxide coating material dominant in a ! electric current density that exceeds 15 A/dm? is effective in improving electrode resistance and also suppressing the reduction in chlorine generating efficiency in contrast to the technical common sense of conventional electrodes coated with a coating material with a dominant plant.

In other words, the seawater electrolysis device is provided with an electrode that includes an anode made of titanium that is coated with a coating material containing iridium oxide and a cathode, an electrolysis vessel main body that ! houses the anode and cathode, and a power supply unit that passes an electrical current between the anode and the cathode in such a way that an electrical current density at the surface of the anode and the cathode is 20 A/dm? or more. In the seawater electrolysis method of the present invention, seawater is distributed within the main body of the electrolysis vessel, an electrical current is passed between the anode and the cathode in such a way that an electrical current density on the surface of the anode and that of the cathode is 20 Aldm? or more to electrolyze seawater inside the main body of electrolysis vessel.

In the present invention, the electric current density at the electrode surface is 20 A/dm? or more which is greater than a conventional electrical current density of 15 A/dm?. Therefore, hydrogen gas is generated at the cathode during electrolysis in a larger amount than a conventional case.

An electrode washing effect is exerted due to the large amount of hydrogen gas, thus making it possible to prevent the deposition of manganese plates on the anode and the deposition of calcium, magnesium or similar plates on the — cathode.

Although the amount of oxygen generated in the vicinity of the anode increases, an iridium oxide is sufficiently resistant to oxygen, thus making it possible to prevent the electrode from eroding by oxygen.

In the present invention, the density of electrical current at the surface of the anode and the cathode between which electrical current is passed by the power supply unit — can they be included in a range of 20 A/dm? or more and 40 Aldm? or less.

Can the electric current density preferably be included in a range of 20 A/dm? or more and 30 A/dm? or less.

When the electric current density is excessively large, eg í in excess of 40 A/dm°?, the amount of plates deposited on the anode and cathode exceeds the amount at which the hydrogen washout effect is effective. In contrast, in the present invention, an upper limit value of the electric current density is set at 40 —A/dm? and preferably at 30 A/dm?. Then, it is possible to effectively develop the washing effect by hydrogen and also effectively prevent the deposition of plates on the anode and cathode.

The seawater electrolysis device according to the present invention can be further (in addition) provided with one or more main bodies of electrolysis vessel, one or more connecting pipes, each connecting a seawater outlet port of one of the electrolysis vessel main bodies and a seawater inlet port of the other of the electrolysis vessel main bodies, and one or more degassing units to remove a gas within each of the connection.

s 15 With an increase in electrical current density, a thiquido-gas ratio decreases due to hydrogen generated at the cathode, thus resulting in a reduction in effectiveness 1 in generating chlorine. In contrast, when gas, in particular hydrogen gas, is removed by the degassing unit installed in the connecting piping, it is possible to keep the interior of the electrolysis vessel at a predetermined liquid-gas ratio or to reduce and also prevent reduction of effectiveness.

The seawater electrolysis system according to the present invention is provided with the seawater electrolysis device according to the present invention described above and a concentration unit for raising the concentration of chlorine ions - to be contained in seawater to be introduced into the main body of the electrolysis container.

The seawater electrolysis method, according to the present invention, increases the concentration of chloride ions contained in seawater that is subjected to electrolysis, distributes the seawater with increased concentration of chloride ions inside the electrolysis vessel main body, and generates an electric current between the anode and cathode to electrolyze seawater inside the electrolysis vessel main body.

In the present invention, concentrated water having the increased concentration of chloride ions and electrical conductivity is introduced into the seawater electrolysis device. Furthermore, as an anode coating material contains an iridium oxide, it is possible to set the electrical current density at the electrode surface to a high value, thus increasing the concentration of hypochlorous acid contained in the electrolyzed water produced by Istoé, through the generation of hypochlorous acid in an increased amount per unit electrode area, the electrode can be reduced in area to decrease the size of the device.

In the present invention, can the electric current density at the anode surface and at the cathode surface between which an electric current is passed by the power supply unit be included in a range of 20 A/dm? or more and 60 A/dm? or less. Can the electric current density be preferably included in a range of 20 A/dm? —or more and 50A/dm? or less.

When the electric current density is excessively large, for example in excess of 60 A/dm?, plates are generated at the anode and cathode in such a quantity that it exceeds the amount when the hydrogen washout effect is effective. In contrast, in the present invention, an upper limit value of electrical current density is set at 60 A/dm? and preferably at 50 A/dm?. Thus, it is possible to effectively exert the hydrogen washing effect and also effectively prevent the deposition of plates on the anode and cathode.

The seawater electrolysis system of the present invention can additionally be provided with a hydrogen separation unit that separates the hydrogen gas — generated in the seawater cathode after electrolysis. It is thus possible to exert the washing effect by hydrogen gas more efficiently and also effectively prevents the deposition of plates on the anode and cathode. In the seawater electrolysis device according to the present invention, a tantalum oxide can be added to the coating material.

Tantalum which is highly resistant to oxygen is added to the cladding material, thus making it possible to improve the resistance to oxygen generated at the anode and more effectively prevent abnormal electrode erosion.

In the seawater electrolysis device according to the present invention, it is acceptable for the electrode to include several double pole electrode plates in which one part —of that one seawater distribution direction is given as the anode and another part of these is given as the cathode, several groups of electrodes in which the double pole electrode plates are arranged at an interval in the distribution direction are arranged parallel to each other, and the double pole electrode plates in each of the groups electrodes adjacent to each other are arranged in such a way that the anode is opposite the cathode. | As described above, the double pole electrode plates, each of which has the anode and cathode, are arranged in a concentrated manner, thus making it possible to reduce the size of the device itself.

Furthermore, as each of the double pole electrode plates is disposed along the seawater distribution direction, there is no chance that the seawater distribution will be impeded. It is then possible to maintain a high flow velocity of seawater and also effectively prevent the deposition of plates on an electrode by seawater.

Furthermore, as the anode is opposite the cathode in each of the electrode groups that are adjacently parallel to each other, an electrical current is passed between the anode and the cathode, thus making it possible to effectively electrolyze the seawater that is distributed between ' tre the electrodes.

In the seawater electrolysis device according to the present invention, an interval between the double pole electrode plates adjacent to each other in the distribution direction in each of the electrode groups may be eight times or more than one. gap between electrode groups that are adjacently parallel to each other.

When the gap between the double pole electrode plates adjacent to each other in the distribution direction is small, an electrical current is generated which is distributed between the double pole electrode plates, i.e. a leakage current that contributes less to the electrolysis.

Leakage current becomes more apparent with an increase in electrical current density at the surface of an electrode.

In contrast, as described above, by maintaining an appropriate gap between double pole electrode plates adjacent to each other in the distribution direction, leakage current generation can be suppressed to prevent a : reduction in the effectiveness of seawater electrolysis . In the present invention, the seawater electrolysis device can be provided with a circulation flow path that mixes the seawater after electrolysis by flowing: from an outlet port of the electrolysis vessel main body with the seawater before flowing into the main body of electrolysis vessel from an inlet port.

There are concerns that plates may deposit on the surface of an electrode with an increase in electrical current density.

However, when seawater after electrolysis is mixed through the circulation flow path with seawater before electrolysis, it is possible to prevent the deposition of plates on the electrode surface since seed crystallization effects can be obtained by plate compositions contained in seawater that has passed through the electrolysis vessel of the seawater electrolysis device.

Effect of the Invention According to the present invention, it is possible to improve the resistance of an electrode and also to suppress the reduction in the effectiveness of generating chlorine by preventing the deposition of plates on the electrode.

Brief Description of the Drawings FIG. 1 is a diagram showing a first embodiment of a seawater electrolysis system in accordance with the present invention.

FIG. 2 is a longitudinal cross-sectional view showing a seawater electrolysis device of the first embodiment.

FIG. 3 is an enlarged view showing main parts of the seawater electrolysis device. FIG. 4 is a graph explaining a constant current control curve of a constant current control circuit in a power supply unit. FIG. 5 is a schematic view showing a second embodiment of a seawater electrolysis system in accordance with the present invention. FIG. 6 is a schematic view showing a modified example of the second embodiment. FIG. 7 is a schematic view showing a third embodiment of a seawater electrolysis system in accordance with the present invention. FIG. 8 is a schematic view showing a description of a hydrogen separator in the third embodiment. FIG. 9 is a graph showing the results of a test in determining efficacy in generating chlorine. ' . 15 FIG. 10 is a graph-showing the results of a test in determining electrode erosion. E 7 Detailed Description of the Invention | Next, an explanation will be made of the first embodiment of the present invention with respect to FIG. 1 through FIG. 4.

A 100A seawater electrolysis system of the first modality is such a system in which seawater is obtained from an inlet channel 1 through which seawater is distributed, seawater electrolysis is performed using a seawater electrolysis device 10 and then the thus treated seawater is filled in inlet channel 1.

The 100A seawater electrolysis system is, as shown in FIG. 1, supplied with the seawater electrolysis device 10, a storage tank 50, an inlet part 60, and a filling part 70. The seawater W which has been subjected to electrolysis by the device seawater electrolysis 10 is stored in the storage tank 50. The inlet part 60 introduces the seawater W into the seawater electrolysis device 10 from the inlet channel 1. Chimento 70 fills the seawater W in storage tank 50 into inlet channel 1, As shown in FIG. 2, the seawater electrolysis device 10 includes an electrolysis container main body 20, an electrode support box 26, terminal blocks 28,29, and a plurality of electrodes 30.

The electrolysis vessel main body 20 is provided with a substantially tubular outer shell 21, the ends of which are open. It is installed in a former

At the edge of the outer casing 21 an upstream cap part 22 for blocking the opening at one end.

A downstream cap part 24 is also installed at the other end of the outer shell 21 to block the opening at the other end.

The main body of electrolysis container 20 is fixed for pressure resistance predetermined by the outer casing 21, the upstream cap part 22 and the downstream cap part 24. Furthermore, the upstream cap part 22 is provided with a port inlet 23 connecting communicatively across the interior and exterior of the electrolysis container main body 20, and the downstream cap part 24 is provided with an outlet port 25 communicatively connecting through the interior and exterior of the body main electrolysis vessel 20. That is, in the main body of electrolysis vessel 20, seawater W is introduced from the inlet port 23 of the upstream cap part 22 and distributed in one direction inside the outer casing 21 from the inlet port 23 to the outlet port 25. Then seawater W flows from the outlet port 25 out of the main body of electrolysis vessel 20. Then the side of the inlet port The side of the main body of electrolysis vessel 20 is called the upstream, while the side of the output port 25 is called the downstream. The electrode support box 26 is a tubular member made of an electrically insulating material such as plastic and housed within the main body of electrolysis container 7 20 so as to extend in the seawater distribution direction W .

The electrode support box 26 is fixed to the upstream cap part 22 and the downstream cap part 24 by means of a plurality of fixing pieces 27. Furthermore, a plurality of support bars 26a for supporting the electrodes 30 is installed within the electrode support box 26. The terminal blocks 28, 29 have functions to supply an electrical current to the electrodes 30 supported within the electrode support box 26 from outside the main body of the electrolysis container. 20, and they are arranged in pairs on both sides of the electrode support box 26. The electrode 30 is formed in the shape of a plate, and a plurality of electrodes 30 are fixed and supported in arrangement on the support bar 26a in the box. of electrode support 26. In the present embodiment, three types of plates are used as electrodes 30, i.e., a double pole electrode plate 31, an anode plate 32 and a cathode plate 33. double pole 31 is structured from such that a titanium baseplate such as an electrode plate is made up of two parts, one of which is given as an anode A and the other of which is given as a cathode K.

That is, one half on one side of the double pole electrode plate 31 is constituted as anode A coated with a coating material containing iridium oxide (dominant iridium oxide coating material), while one half on the other side of the electrode plate 31 is constituted

Aeee ———————— The A An 9/31 as the cathode K uncoated with the dominant iridium oxide coating material.

Furthermore, the 32 anode plate is structured in such a way that the dominant iridium oxide coating material is coated over the entire titanium base plate, and the 32 anode plate as a whole acts as anode A during electrolysis. On the other hand, an uncoated titanium base plate is adopted as the 33 cathode plate, and the 33 cathode plate with a whole acts as the K cathode during electrolysis.

The amount of iridium oxide by mass ratio in the dominant iridium oxide coating material is set to 50% or more, and preferably, set in a range of 60% to 70%. Thereby, it is possible to obtain favorable coating effects from the iridium oxide.

Furthermore, it is preferred that tantalum is added to the dominant iridium oxide coating material. It is most preferred that the dominant iridium oxide coating material does not contain platinum.

Here, an explanation will be made of the arrangement of three different types of electrodes 30 i within the electrode support box 26. The double pole electrode plate 31, the anode plate 32 and the cathode plate 33 are respectively fixed and supported on support bars 26a inside electrode support box 26. * Of the above described electrodes 30, as shown in FIG. 2 and in FIG. 3, the various double pole electrode plates 31 are arranged such that they extend along the seawater distribution direction W, while each anode A faces the seawater inlet side and each cathode K faces the seawater outlet side. Furthermore, the double pole electrode plates 31 are arranged in series with a gap in the distribution direction, thus constituting a group of M electrodes. interval, that is, they are installed in a plural number parallel to each other.

Groups of electrodes M that are adjacently parallel to each other are arranged so as to deviate only by half the distance of each double pole electrode plate 31 relative to the distribution direction. Thus, the double pole electrode plates 31 in each of the electrode groups M, which are adjacently parallel to each other, are in a state where an anode A is opposite a cathode K. Furthermore, in the present modality, as shown in FIG. 3, it is preferred that an interval d1 between the double pole electrode plates 31 that are adjacent in the distribution direction in each of the electrode groups M is set to be 8 times or more an interval between the groups. —may electrodes M that are adjacently parallel to each other, that is, an interval d2 between the double pole electrode plates 31 that are adjacently parallel to each other.

On the other hand, the various anode plates 32 are arranged parallel to each other to the

"22 ..------- '*' - 33C3SC2" * € C22A 2CÚCs "[qq assssossspsstpspspptsoótsspssssRRRRRRRRRRRRRRRRRRRRERRRRRRRRRRRRRRRRRRRRFERRRRRRRRRRRRRRFRRRRRRRRERRERRRREREEEEEEEEEEEEEAA 10/31 W along the sea water distribution toward the downstream side of the electrode plates: double pole 31, and the various cathode plates 33 are arranged parallel to each other along the seawater distribution direction W on the upstream side of the double pole electrode plates 31.

A downstream end of each of the anode plates 32 is connected to the downstream terminal block 29 of the pair of terminal blocks 28, 29, while an upstream end of each of the anode plates 32 is opposite the cathode K of each of the double pole electrode plates 31 in a direction orthogonal to the distribution direction. In other words, the upstream end of the anode plate 32 and the cathode K of the double pole electrode plate 31 are alternately arranged so as to overlap when viewed in the direction orthogonal to the distribution direction. Furthermore, the upstream end of the cathode plate 33 is connected to the terminal block 28 of the pair of terminal blocks 28, 29. In addition, the downstream end of each of the cathode plates 33 is opposite the anode A of each of the double pole electrode plates 31 in the orthogonal direction to the distribution direction. In other words, the downstream end of each cathode plate 33 and the anode A of the double pole electrode plate 31 are alternately arranged so that they overlap when viewed from the direction orthogonal to the direction of the electrode. attribution. . The power supply unit 40 is a device for supplying an electrical current to be used during seawater electrolysis W and provided with a direct current power supply 41 and a constant current control circuit 42. dc power supply 41 is a power source to emit continuous electrical energy. In addition, the alternating electrical power output from an alternating current power supply, for example, can be rectified into direct current and then emitted.

The constant current control circuit 42 is a circuit for outputting a direct current supplied from the direct current power supply 41 as a constant current. Irrespective of a change in electrical resistance across the sections passing electrical current, the constant current control circuit 42 is capable of delivering a predetermined constant current to the section passing electrical current. That is, when continuous electrical power is input from the direct current power supply 41, as shown in FIG. 4, the constant current control circuit 42 controls a voltage value of the continuous electrical power over a wide range of AV deflection, whereby a desired electrical current value in the constant current control curve is output as a constant current.

In the above-described constant current control circuit 42, anodes A are connected to downstream terminal block 29 and cathodes K are connected to upstream terminal block 28 via a conductor on wires 43, 44. Thereby, a current constant generated in the constant current control circuit 42 is passed through electrodes 30 via terminal blocks 28, 29. In this case, in the power supply unit 40 of the present modality, the circuit — constant current control device 42 generates a constant current such that the electrical current density at the surface of electrode 30 is included in a range of 20 Aldm? at 40 A/dmº and preferably in a range of 20 A/dm? at 30 A/dm?. That is, constant current is generated depending on the surface area of electrode 30 within the main body of electrolysis vessel 20, and constant current is supplied to electrode 30, whereby the density of electric current at the surface of electrode 30 is it included in a 20 A/dm range? at 40 A/dm? and preferably in a range of 20 A/dm? at 30 A/dm?.

In an electrode coated with a conventional platinum-dominant composite metal (platinum-dominant coating material), the amount of oxygen and accelerated eroding plates of the electrode increases, with an increase in the density of electrical B 15 current. Then, a maximum value of the electric current density is set to "approximately 15 A/dm? - | onal. That is, electrolysis is performed at an electrical current density in a range of . 20 A/dm? at 40 A/dm?, and preferably 20 A/dm? at 30 A/dm?.

The storage tank 50 is a tank that temporarily stores seawater W flowing from the outlet port 25 of the main body of electrolysis vessel 20 in the seawater electrolysis device described above 10. To seawater W is introduced into the tank via an intermediate flow path 51 connected to the outlet port of the main body of electrolysis vessel 20.

Inlet port 60 includes an inlet flow path 61, a first pump 62, a first flow meter 64 and a first open/close control valve 63.

The inlet flow path 61 is a flow path which is connected at one end of this to the inlet channel 1 and at the other end to the inlet port 23 of the — electrolysis container main body 20 in the seawater electrolysis device. 10.

The first pump 62 is installed halfway along the inlet flow path 61. The first pump 62 pumps up the seawater W in the inlet channel 1 at a constant outlet, by which the seawater W is inserted into the input port 23.

The first flow meter 64 is installed downstream of the inflow path 61, sensing a flow rate Q of seawater W passing through the inflow path 61.

Furthermore, the first opening/closing control valve 63 is a valve which is installed upstream of the first flow meter 64 in the inlet flow path 61 and controlled to open and close based on the flow rate Q1 of the water in the mar W detected by the first flow meter 64. By this constitution, the flow rate of the water of the —marW that is distributed through the flow path is adjusted depending on an area ratio of a water distribution region of the from the inlet flow path 61 to that of the electrolysis vessel main body 20. Thus, it is possible to adjust the flow velocity of the seawater W which is distributed within the electrolysis vessel main body 20 at a speed arbitrary.

In the seawater electrolysis device 10 of the present embodiment, it is preferable that the first opening/closing control valve 63 is controlled in such a way that the flow velocity of the seawater W which is distributed within the main body of electrolysis vessel 20 is at least 0.7 m/s (meters/second) or more.

It is acceptable that the seawater flow velocity W within the main body | of electrolysis vessel 20 is adjusted not only by controlling the opening and closing of the first opening/closing control valve 63, but also "adjusted, for example, by controlling the output of the first pump 62. The filling part 70 includes a fill flow path 71, a second pump 72, a second open/close control valve 73, and a second flow meter 74.

The fill flow path 71 is a flow path that is connected at one end of this to storage tank 50 and connected at the other end to inlet channel 1.

The second pump 72 is installed halfway along the fill flow path 71. The second pump 72 pumps up the seawater W into the storage tank 50 at a constant outlet, whereby the water from the sea W is introduced into input channel 1.

The second flow meter 74 is installed downstream of the fill flow path 71, detecting a flow rate Q of seawater W passing through the fill flow path 71.

The second open/close control valve 73 is a valve that is installed upstream of the second flow meter 74 in the fill flow path 71 and controlled to open and close based on the flow rate Q of the water in the mar W detected by the second flowmeter 74. By this constitution, the flow rate of the —marW water to be filled in inlet channel 1 is adjusted. It is acceptable that not only the second open/close control valve 73 be controlled to open/close to adjust an amount of seawater W filled in the en- O IESRA ERR ER MO rs OA Aa AAAOA to E and eee ao e E EE tra 1, but also, for example, the second pump 72 is controlled to the output to ] adjust the amount of seawater W filled in the inlet channel 1. Then an explanation will be made for the operation of the seawater electrolysis device 10 of the present modality and a method to perform the domarW water electrolysis using the seawater electrolysis device 10.

The sea water W that is distributed through the cane! inlet 1 is partially introduced by the inlet part 60 in the electrolysis vessel main body 20 from the inlet port 23 of the electrolysis vessel main body 20 of the seawater electrolysis device 10. That is, the seawater W within the inlet channel 1 is pumped up to the inlet flow path 61 by the first pump 62, whereby the seawater W is introduced into the main body of electrolysis vessel 20 via the path inlet flow 61. By this constitution, the electrodes 30 inside the main body of electrolysis vessel 20 are immersed in seawater W. At that time, the first open/close control valve 63 is opened and closed depending on of a flow rate detected by the first flow meter 64. Thereby, the sea water W which is distributed within the main body of electrolysis container 20 in the distribution direction, is adjusted so as to have a desired flow rate. As described above, seawater W which is distributed within the main body of electrolysis vessel 20 is subjected to electrolysis by electrodes 30. That is, a desired constant current is generated in the constant current control circuit 42 with based on the continuous electrical energy from the dc power supply 41 in the power supply unit 40, and the constant current is supplied to the terminal blocks 28, 29 via the conductors on wires 43, 44. The electrical current is supplied via the blocks of terminals 28, 29 is distributed in series within the main body of electrolysis container 20 sequential- | through the anode plates 32, the double pole electrode plates 31 and the cathode plates 33.

More specifically, when an electrical current that is distributed to the anode plate 32 from the constant current control circuit 42 arrives at a cathode K of a double pole electrode plate 31 via seawater W, the current electrical is distributed within the double pole electrode plate 31 and thereby reaches anode A of the double pole electrode plate 31. Then the electrical current which is distributed through the seawater W arrives at the cathode K from another double pole electrode plate 31 opposite the above anode A. As described above, electrical current is distributed from the anode plate 32 to the plurality of double pole electrode plates 31 sequentially and finally distributed to the cathode plate 33. At this time, is the density of the electrical current on the surface of each of the electrodes 30 controlled by the constant current control circuit 42 over a range of 20 A/dm? at 40 A/dm? and preferably in a range of 20

Besides? at 30 A/dm?. : The electric current passing through seawater W, as described above, has a constant electric current density at the surface of the electrode 30 by the operation of a constant current control circuit 42 independent of a change in the —electrical resistance of the water in the sea W. ie the sea water W which is distributed within the main body of the electrolysis vessel 20 changes in value of electrical resistance from moment to moment.

However, as shown in FIG. 4, the constant current control circuit 42 controls the voltage at a predetermined deflection width AV, whereby the density of electric current at the surface of the electrode 30 is kept constant.

As described above, an electrical current is passed through seawater W between electrodes 30 to electrolyze it.

That is, at anode A, as shown in the following Formula (1), chlorine ions in seawater W lose electrons and to cause oxidation, thus resulting in the generation of chlorine.

Formula 12CI > Cl; + 2e (1) : On the other hand, at cathode K, as shown in the following formula (2), electrons ' are imparted to water in seawater W to cause a reduction, thus resulting in the generation of hydroxide ions and gas hydrogen. ' Formula 2 2H30 + 28 > 20H + HT (2) Furthermore, as shown in the following formula (3), the hydroxide ions generated at the cathode K react with the sodium ions in seawater W to generate sodium hydroxide.

Formula 3 2Na* + 20H > 2NaOH (3) Further, as shown in formula (4), sodium hydroxide reacts with chlorine to generate hypochlorous acid, sodium chloride and water.

Formula 4 Cl; + 2NaOH — NaCIO + NaCl + HO ...(4) As described above, seawater electrolysis W generates hypochlorous acid that is effective in suppressing marine growth adhesion.

Then, seawater W, which has been subjected to electrolysis, flows from the outlet port 25 of the main body of electrolysis vessel 20, passes through the intermediate flow path 51 and is temporarily stored in the storage tank 50. Then, seawater W in storage tank 50 is filled in inlet channel 1 /via the filling part 70. That is, seawater W containing hypochlorous acid in storage tank 50 is filled in inlet channel 1 via the path of fill flow 71 through the activation of the second pump 72. At that time, the second open/close control valve 73 is opened and closed depending on a flow rate detected by the second flow meter 74, thus adjusting an amount of the seawater W containing hypochlorous acid W which flows into inlet channel 1. : In this case, in general, manganese plates resulting from manganese ions contained in seawater W deposit on anode A coated with a coating material with dominant iridium oxide during electrolysis. As anode A undergoes accelerated erosion due to the deposition of manganese plates and also the catalytic activities on the surface of electrode 30 are reduced, there is a disadvantage in reducing the efficiency in the generation of chlorine. Furthermore, the resulting magnesium and calcium plaques contained in the water of marW are deposited on the cathode K to accelerate the erosion of electrode 30.

In contrast, according to the above modality, the electric current density on the surface of electrode 30 is set to 20 Aldm? or more, which is greater than a conventional electrical current density of 15 A/dm?. Thus, hydrogen gas is generated in association with electrolysis at the cathode K in a larger amount than a conventional case. The washing effect at electrode 30 can be developed due to the greater amount of hydrogen gas generated, thus making it possible to prevent the deposition of manganese plates on an anode A and the deposition of plates such as calcium and magnesium on the cathode K.' Furthermore, the amount of oxygen generated in the vicinity of an anode A is also increased with an increase in the density of electric current at the electrode surface 30. However, as iridium oxide is sufficiently resistant to oxygen, it is possible to prevent dir the erosion caused by oxygen of an anode A coated with the coating material containing iridium oxide.

When the electric current density on the surface of electrode 30 is excessively large, eg in excess of 40 Aldm?, the plates deposit on anode A and cathode K in such a quantity that it exceeds the amount where the washout effect by hydrogen is effective. In contrast, in the present embodiment, the upper limit of the electric current density is set at 40 A/dm?. Thus, it is possible to effectively develop the hydrogen washing effect and effectively prevent plaque deposition on anode A and —nocatodoK. Furthermore, when the upper limit of the electric current density is set to 30 A/dm?, it is possible to effectively develop the washing effect due to hydrogen and also effectively prevent plaque deposition.

As described above, in the present embodiment, the iridium oxide is contained in the coating material of anode A and the electric current density at the surface of the electrode30 is set in a range of 20 A/dm? at 40 A/dm? and preferably in a range of 20 A/dm? at 30 A/dm?. Then, it is possible to effectively develop the washing effect by hydrogen gas. Thus, it is also possible to improve the resistance of electrode 30 and

—-€2S- O-p[| o OY-Ç—Ç—Ç.—€22 pr ospSj—-€«psp—€.O€—2 qppp.O.Mpsoosopo AAA to AA 16/31 suppress the reduction in the effectiveness of chlorine generation by preventing Plaque deposition on : electrode 30. In addition to improved maintenance of the '10 seawater electrolysis device, the number of electrode 30 can be reduced to decrease device size due to greater efficiency in chlorine generation.

Furthermore, when tantalum oxide is added to the dominant iridium oxide coating material that coats anode A, tantalum exhibits great resistance to oxygen. As a result, it is possible to more effectively prevent the abnormal erosion of electrode 30 due to oxygen generated in the vicinity of anode A.

It is noted that no platinum is contained in the dominant iridium oxide coating material, thus making it possible to reduce the cost.

Still in the present embodiment, the double pole electrode plates 31 are arranged in series to form a group of M electrodes, and the various groups of M electrodes are arranged parallel to each other, whereby many double pole electrode plates 31 they are arranged in a concentrated way. IT'S; then, it is possible to decrease the size of the device, 5 while a large amount of total chlorine generation is ensured. ' In addition, as the double pole electrode plates 31 are individually disposed along the seawater distribution direction W, there is no chance that the ' seawater distribution W will be impeded. It is then possible to keep the seawater W at a high flow velocity and also to effectively develop the effect of preventing the deposition of plates on the electrode 30.

Then anode A is opposite cathode K between the groups of electrodes M that are adjacently parallel to each other. Then, an electric current is passed between anode A and cathode K, thus making it possible to effectively electrolyze seawater W which is distributed between electrodes 30.

When a gap is small between the double pole electrode plates 31 adjacent to each other in the seawater distribution direction W, an electric current is developed which is distributed between the double pole electrode plates 31, ie, a leakage current that contributes less to electrolysis. The leakage current becomes lighter with the increase in electrical current density at the surface of electrode 30, thus resulting in a reduction in the effectiveness of electrolysis in seawater.

In contrast, in the present embodiment, an interval d1 between adjacent double pole electrode plates 31 in the distribution direction in each of the M electrode groups is eight times or more than an interval d2 between the M electrode groups that are adjacently parallel to each other. That is, a gap between the double pole electrode plates 31 adjacent to each other in the distribution direction is properly maintained, thus making it possible to suppress the occurrence of leakage current and prevent the reduction in the effectiveness of

222 Oss“ - sO.“—€C«A AAA A O AE a a a 17/31 seawater electrolysis. Next, an explanation will be made for a seawater electrolysis system 100B of the second embodiment according to the present invention with respect to FIG. : 5. In the second modality, constituents similar to those of the first modality are given the same reference numbers, and a detailed explanation of these is omitted here. As shown in FIG. 5, the seawater electrolysis system 100B of the second embodiment is provided with a circulation part 80 between the inlet flow path 61 of an inlet part 60 and the fill flow path 71 of a fill part 70. The circulation part 80 mixes the seawater W within a — fill flow path 71 with the sea water in an inlet flow path 61. The circulation part 80 includes a path flow valve 81, a third flow meter 84, and a third open/close control valve 83.

The circulation flow path 81 is a flow path that is connected at one end to the fill flow path 71 and connected at the other end to the inlet flow path 61. In the present embodiment, one end of the ca. circulation flow path 81 is connected between a second pump 72 and a second: open/close control valve 73 in the fill flow path. The other end of the circulation flow path 81 is connected between a first: pump 62 and a first opening/closing control valve 63 in the inlet flow path 61.

The third flowmeter 84 is installed midway along the circulation flow path 81, sensing a flow rate Q; of seawater W passing through the circulation flow path 81.

In addition, the third open/close control valve 83 is a valve that is installed downstream of the third flow meter 84 in the circulation flow path 81, and controlled to open and close based on the seawater flow rate Q3 W detected by the third flowmeter 84. Thus, it is possible to control, whenever necessary, the flow rate of the seawater W flowing from the fill flow path 71 via a circulation flow path 81 to the inflow path 61.

In the above-described seawater electrolysis system 100B, when seawater W stored in a storage tank 50 after electrolysis is introduced by the second pump 72 into the fill flow path 71, the seawater W is separated. stop at seawater W which is distributed via the fill flow path 71 and seawater W which is distributed via the circulation flow path 81 at a branch part of the fill flow path 71 to which an end of the path flow flow 81 is connected.

Seawater W that has passed through the circulation flow path 81 is intro-

ducted in the inlet flow path 61 at the other end of the circulation flow path 81. That is, the seawater W, after electrolysis, which has passed through the circulation flow path 81 flows along with the water from sea W, before electrolysis, which has passed through inlet flow path 61 and is re-introduced into main body of electrolysis vessel 20. At this point, the third opening/closing control valve 83 is open and closed depending on a flow rate detected by the third flow meter 84, thus making it possible to adjust the flow rate of seawater W, after electrolysis, which flows along with the flowing seawater W through the inflow path 61.

As described above, seawater W, after electrolysis, which has flown from the outlet port 25 of the main body of electrolysis vessel 20 is distributed through the circulation flow path 81 and thereby flows back to the main body of electrolysis vessel 20 from inlet port 23 thereof.

In that case, slab compositions such as manganese, magnesium and calcium, deposited during electrolysis are found in seawater W after electrolysis. Seawater W is again introduced into the main body of electrolysis vessel 20, thus making it possible to prevent the deposition of plates on the surface of electrode 30 due to seed crystallization effects of the plate compositions. That is, the plaque compositions act like seed crystals and the newly generated plates deposit on the seed crystals, thus making it possible to avoid the precipitation of plaques on the surface of electrode 30. It is then possible to improve the resistance of electrode 30 and also suppress the reduction of efficiency in the generation of chlorine.

An explanation has so far been made in detail of the modalities of the present invention. The present invention should not, however, be restricted, and can be modified in —various ways including some change in the design without abandoning the technical idea of the same.

For example, in the 100B seawater electrolysis system, it is preferred that the seawater W that is filled from the fill portion 70 in inlet channel 1 is set to approximately 2500 ppm in terms of the acid — hypochlorous concentration .

In this case, the total amount of hypochlorous acid thus generated is substantially proportional to the total amount of electrical current supplied from the power supply unit 40 to electrodes 30. Then, the amount of electrical current supplied to electrodes 30 can be recorded to calculate the total amount of hypochlorous acid thus generated. Furthermore, the concentration of hypochlorous acid in seawater W that is filled in inlet channel 1 can be calculated by dividing the total amount of hypochlorous acid thus generated by a flow rate Q, of the seawater W which is filled in

19/31 | inlet channel 1. Then, the second open/close control valve 73 is controlled depending on the total amount of hypochlorous acid to determine the flow rate Q of seawater W that is filled in the channel of input 1. It is thus possible to adjust ] easily the concentration of hypochlorous acid in seawater W to 2500 ppm In addition, as a modified example shown in FIG. 6, it is acceptable that the seawater electrolysis device 10 is provided with a plurality of main bodies of electrolysis vessels 20 and that a connecting pipe 85 is installed to connect the outlet port 25 to the inlet port 23 of each of the electrolysis vessel main bodies 20 and a degassing valve 86 as a degassing unit to remove gas within the connecting piping 85. The degassing valve 86 is a valve that can be controlled to open and close. When the pressure inside the electrolysis vessel main body 20 increases to a predetermined high pressure, the degassing valve 86 is opened to release the gas into the seawater W.

A liquid-gas ratio decreases due to the hydrogen generated at the cathode K with an increase in the electric current density, thus resulting in a reduction in efficiency: in the generation of chlorine. However, in particular, the hydrogen gas is removed by the 'degassing valve 86 installed in the connecting pipe 85, by which it is possible to suppress the liquid-gas ratio inside the main body of electrolysis vessel 20 to a predetermined level ' and prevent the reduction in effectiveness.

In the above modality, an explanation has been made of the electrode 30 with respect to an example using a double pole electrode plate 31. However, it is acceptable that, for example, an anode plate 32 and a cathode plate 33 are disposed oppositely between itself, without using the double pole electrode plate 31 and an electrical current is passed through seawater W between the anode plate 32 and the cathode plate 33. It is also acceptable—that the anode plate 32 and the cathode plate 33 are alternately arranged, whereby electric current is passed through seawater W between the anode plate 32 and the cathode plate 33 which are adjacent and opposite each other.

Furthermore, in the above embodiment, the double pole electrode plate 31 is arranged such that an anode A is facing the seawater inlet side and the cathode K is facing the seawater outlet side. However, the double pole electrode plate 31 can be arranged in such a way that anode A is facing the seawater inlet side and cathode K is facing the seawater inlet side.

Next, an explanation will be made of a seawater electrolysis system 100C of the third embodiment according to the present invention with respect to FIG. 7 and FIG 8. In the third mode as well, constituents similar to those in the first mode will be given the same reference numbers, with a detailed explanation omitted here.

As shown in FIG. 7, the seawater electrolysis system 100C of the third mode is provided with a seawater electrolysis device 10, an inlet part 60, a hydrogen separator 90, a storage tank 50, an I part of filling 70 and a circulating part 80. The inlet part 60 introduces the domar water into the seawater electrolysis device 10 from an inlet channel 1. The hydrogen separator 90 separates the hydrogen into electrolyzed water and discharged to from the seawater electrolysis device 10. The storage tank 50 stores the electrolyzed water E that has been subjected to electrolysis by the seawater electrolysis device 10. The filling part 70 fills the electrolyzed water E of the tank. storage 50 in inlet channel 1. Circulation part 80 circulates electrolyte water | outlet E in the seawater electrolysis device 10. The seawater desalination device 65 is installed in the inlet part 60.

In that case, in the power supply unit 40 of the present embodiment, a constant current is generated by the constant current control circuit 42 such that an electrical current density at the surface of an electrode 30 is in the range of 20 A/dm? at 60 A/dm? and preferably in a range of 20 A/dm? at 50 A/dm?. º That is, constant current is generated depending on the surface area of electrode 30 within the main body of electrolysis vessel 20 and supplied to electrode 30. Thus, the density of electric current at the surface of electrode 30 is in a range of 20 A/dm? at 60 A/dm° and preferably in a range of 20 A/dm? at 50 A/dm?.

In an electrode coated with a conventional platinum-dominant composite metal (platinum-dominant coating material), the amount of oxygen and plates that accelerate electrode erosion is also increased with an increase in current density. electric. Then, a maximum value of the electric current density was set at approximately 15 A/dm?. In contrast, in the present embodiment, electrolysis is performed over an electric current density range of 20 A/dm? at 60 A/dm?, and preferably in a range of 20 A/dm? at 50 A/dm? which is bigger than a conventional case.

The inlet part 60 includes an inlet flow path 61, a first pump 62, a seawater desalination device 65, a first flow meter 64 and a first open/close control valve 63.

The sea water desalination device 65 is a device for separating sea water into pure water (salt water) and concentrated water C using a reverse osmosis membrane (RO membrane). The pure water separated by the seawater desalination device 65 is fed via a pure water line 66 into a pure water tank (not shown), while the concentrated water C is introduced into the water electrolysis device of the mar 10 via the first opening/closing control valve

63 of the inlet flow path 61. In the seawater electrolysis device 10 of the present embodiment, it is preferable that the first opening/closing control valve 63 is controlled so that the concentrated water C which is distributed within the main body of the electrolysis vessel20 has a flow velocity of at least 0.7 m/s or more.

It is acceptable that not only the first opening/closing control valve 63 is controlled to open and close to adjust the flow rate of concentrated water C within the main body of electrolysis vessel 20, but also that, for example, the first pump 62 is output controlled to adjust the flow rate of the concentrated water C within the main body of electrolysis vessel 20.

The hydrogen separator 90 is a device for separating the hydrogen gas contained in the electrolyzed water E flowing from the outlet port 25 of the main body of electrolysis container 20 in the seawater electrolysis device 10. How shown in FIG. 8, the hydrogen separator 90 is provided with a water receiving tank 92 having an exhaust pipe 91 in an upper part thereof, an introduction pipe 93 . which is connected to the outlet port 25 of the main body of electrolysis vessel 20 by means of the intermediate flow path 8 to direct electrolyzed water into an upward gas phase part 92a within the water receiving tank 92, a nozzle of ' sprinkler 94 installed midway along inlet piping 93 and an agitator 95 installed in a descending liquid phase portion 92b within the water take-up tank 92.

The sprinkling nozzle 94 ejects the electrolyzed water E which has been introduced into the introduction piping 93 in the ascending gas phase part 92a inside the water receiving tank 92. The agitator 95 is constituted with a screw 96 and a motor 97 which rotates the — screw 96, thus stirring a liquid grouped in the liquid phase part 92b of the water receiving tank 92. In addition, a discharge port 98 through which the water is installed in a lower part of the water receiving tank 92 electrolyzed is discharged.

Storage tank 50 is a tank that temporarily stores electrolyzed water E that is discharged from discharge port 98 of hydrogen separator 90.

The circulation part 80 is a part which circulates the electrolyzed water E flowing through the filling flow path 71 in the inlet flow path 61 of the inlet part 60. The circulation part 80 includes a circulation flow path 81, a third flow meter 82 and a third open/close control valve 83.

The circulation flow path 81 is a flow path that is connected at one end of this to the fill flow path 71 and connected at the other end.

inlet flow path 61. In the present embodiment, one end of the circulation flow path 81 is connected between the second pump 72 and the second open/close control valve 73 in the fill flow path 71 The other end of the circulation flow path 81 is connected between the first open/close control valve 63 and the first flow meter 64 in the inlet flow path 61.

The third flowmeter 82 is installed halfway along the circulation flow path 81, sensing a flow rate Q; of electrolyzed water E passing through the circulation flow path 81.

Furthermore, the third open/close control valve 83 is a valve that is installed downstream of the third flow meter 82 in the circulation flow path 81 and controlled to open and close based on the flow rate OQ; of the electrolyzed water E detected by the third flow meter 82. Through this constitution, it is possible to control the flow rate of the electrolyzed water E which is circulated to the inlet flow path 61 a —from the fill flow path 71 via the circulation flow path 81 at arbitrary rate. ' Next, an explanation of the operation of the 100C seawater electrolysis system of the present modality and a method to perform W seawater electrolysis using the 100C seawater electrolysis system will be given. The seawater W which is distributed through the inlet channel 1 is partially introduced into the seawater desalination device 65 through the inlet part 60. That is, the seawater W inside the inlet channel 1 is pumped. to the inlet flow path 61 by the first pump 62, whereby the seawater W is introduced to the seawater desalination device 65 via the inlet flow path 61. Thus, the —seawaterW is separated into water pure and concentrated water C.

The desalination device 65 allows seawater W to pass through the membrane RO by applying pressure to the seawater W, thereby concentrating the salt content of the seawater W to filter pure water. Thus, the concentration of chlorine ions in seawater W is increased, for example, up to a range of 20,000 mg/L to 30,000 to 40,000 mg/L, — resulting in the production of concentrated water C. Pure water is fed by means of a pure water line 66 to a pure water tank (not shown) which stores the pure water, while the concentrated water C is introduced via the inlet flow path 61 into the main body of electrolysis vessel 20.

Thereby, the electrodes 30 inside the main body of electrolysis vessel 20 are immersed in concentrated water C. At that time, the first opening/closing control valve 63 is opened and closed depending on a flow rate detected by the first flow meter. flow 64, by which the concentrated water C which is distributed in the

The dispensing position within the main body of electrolysis vessel 20 is adjusted so as to provide a value of a desired flow rate. Then, the concentrated water C that is distributed within the main body of electrolysis container 20 is subjected to electrolysis by electrode 30. That is, a desired constant current is generated in the constant current control circuit 42 with base in the constant electrical energy from the direct current power supply 41 in the power supply unit 40, and the constant current is supplied via conductors in wires 43, 44 to terminal blocks 28, 29. An electrical current supplied via the terminal blocks 28, 29 is distributed in series sequentially through an anode plate 32, a double pole electrode plate 31 and a cathode plate 33 within the main body of electrolysis vessel 20.

More specifically, the electrical current distributed from the constant current control circuit 42 to the anode plate 32 arrives at the cathode K of the double pole electrode plate 31 via concentrated water C. The electrical current is distributed inside the - 15 double pole electrode plate 31 and thus arrives at anode A of the double pole electrode plate 31. Then, the electric current passing through the concentrated water arrives at ' anode K of another pole electrode plate double 31 opposite anode A. As described above, electrical current is distributed from anode plate 32 sequentially through: through the various double pole anode plates 31 and finally distributed to cathode plate33. Is an electric current density of the electric current at that time on the surface of each of the electrodes 30 controlled by the constant current control circuit 42 so as to be in a range of 20 A/dm? at 60 A/dm? and preferably in a range of 20 A/dm? at 50 A/dm?.

As described above, the electrical current passing through concentrated water C has a constant electrical current density on the surface of each of the electrodes 30 due to the operation of the constant current control circuit 32, independent of a change in the electrical resistance of the concentrated water C. That is, the concentrated water C that is distributed within the main body of electrolysis vessel 20 undergoes a change in electrical resistance value from moment to moment. As shown in FIG. 4, the constant current control circuit 42 controls the voltage to provide a predetermined deflection width AV, whereby the density of electric current at the surface of the | electrode 30 is held constant.

As described above, an electrical current is distributed within the concentrated water C between electrodes 30, whereby the concentrated water C is subjected to electrolysis.

That is, in anode A, as shown in Formula (1) of the first modality, the chlorine ions in concentrated water C lose electrons and cause oxidation, thus generating chlorine.

On the other hand, at cathode K, as shown in Formula (2) of the first modality,

de, electrons are imparted to water in concentrated water C to cause a reduction, ' thus resulting in the generation of hydroxide ions and hydrogen gas. Furthermore, as shown in Formula (3) of the first embodiment, the hydroxide ions generated at the cathode K react with the sodium ions in concentrated water to generate sodium hydroxide.

Furthermore, as shown in Formula (4) of the first embodiment, sodium hydroxide reacts with chlorine to generate hypochlorous acid, sodium chloride and water.

As described above, based on the electrolysis of concentrated water C, hypochlorous acid is generated which is effective in suppressing marine growth deposition.

As the chlorine ion concentration in concentrated water C is increased to a value in the range of 30,000 mg/L to 40,000 mg/L, the hypochlorous acid concentration is preferably set in a range of 2,500 ppm to 5,000 ppm.

Then, the concentrated water C that has been subjected to electrolysis flows from the outlet port 25 of the main body of electrolysis vessel 20 as electrolyzed water E, together with hydrogen gas, passing through the intermediate flow path 8 and flowing in a 90 hydrogen separator.

: A gas-liquid mixing fluid composed of hydrogen gas and electrolyzed water E is introduced into an introduction pipe 93 of the hydrogen separator 90 and ejected: by a spray nozzle 94 into a gas phase part 92a of the receiving tank of water 92. Thus, hydrogen gas mixed with electrolyzed water E as bubbles is subjected to deaeration and emitted from the exhaust pipe 91.

On the other hand, the electrolyzed water E is stored in the liquid phase part 92b of the receiving water tank 92. The stored electrolyzed water E is stirred by a | agitator 95. That is, the electrolyzed water E is forcefully agitated by a spiral flow caused by a screw 96 rotated by a motor 97. Thus, the plates deposited in association with electrolysis are prevented from flocculating at the bottom of the receiving tank 92. The electrolyzed water E that has been temporarily stored in the receiving water tank 92 is discharged from the discharge port 98 installed at the bottom of the receiving water tank 92 and introduced into the storage tank 50.

When the electrolyzed water E which has been temporarily stored in the storage tank 50 is introduced by the second pump 72 into the filling flow path 71, the electrolyzed water E is branched into electrolyzed water E which is distributed through the flow path of fill 71 and the electrolyzed water E which is distributed through the circulation flow path 81 in a branch part of the fill flow path 71 to which an end of the circulation flow path 81 is connected.

The electrolyzed water E which is distributed through the fill flow path.

Inlet 71 is filled in inlet channel 1. That is, electrolyzed water E containing hypochlorous acid in storage tank 50 is filled in inlet channel 1 via fill flow path 71 by activating the second pump. 72. At this time, the second opening/closing control valve 73 is opened and closed depending on the flow rate detected by the second flow meter 74, thus adjusting the flow rate of the electrolyzed water E that is filled in the channel. input 1 and contains hypochlorous acid.

In this case, the total amount of hypochlorous acid generated is substantially proportional to the total amount of electrical current supplied from power supply unit 40 to electrodes 30. Then, the amount of electrical current supplied to electrodes 30 is recorded to calculate the amount total hypochlorous acid generated. Furthermore, the concentration of hypochlorous acid in the electrolyzed water E that is filled in inlet channel 1 can be calculated by dividing the total amount of hypochlorous acid generated by a flow rate Q, of the seawater W that is filled in the channel of inlet 1. Then, the second open/close control valve 73 is controlled depending on the total amount of hypochlorous acid to determine the flow rate Q, of the electrolyzed water E that is filled in inlet channel 1. Yeah, then, it is possible to adjust the concentration of hypochlorous acid in the electrolyzed water E. On the other hand, the electrolyzed water E which is distributed through the circulation flow path 81 is introduced into the inlet flow path 61 at the other end of the flow path of circulation 81. That is, the electrolyzed water E which has passed through the circulation flow path 81 flows together with the sea water W passing through the inlet flow path 61 and is again introduced into the body main of electrolysis vessel 20. At this time, the third opening/closing control valve 83 is —opened and closed depending on the flow rate detected by the third flowmeter 82, thus making it possible to adjust the flow rate of the electrolyzed E flowing water together with seawater W which is distributed through the inlet flow path 61.

As described above, the electrolyzed water E which flowed from the outlet port 25 of the electrolysis container main body 20 is distributed through the circulation flow path 81, thus flows again in the electrolysis container main body 20 from the gateway 23.

According to the above modality, concentrated water C with increased chlorine ion concentration and increased electrical conductivity is introduced into the seawater electrolysis device 10. Furthermore, as an anode A coating material contains an iridium oxide, it is Is it possible to configure the electric current density on the surface of electrode 30 in a range of 20 A/dm? at 60 A/dm? and preferably in a range of 20 Aldm? at 50 A/dm?. Thus, it is possible to increase the concentration of hypochlorous acid contained in the electrolyzed water generated E. That is, the hypochlorous acid is produced in an amount ] per unit of increased electrode area, thus making it possible to decrease the electrode area and decrease the size of the electrode. device. • Seawater in the vicinity of a river mouth or inside a bay has a lower concentration of chlorine ions than normal seawater and also lower electrical conductivity. So, there may be a problem with stability of operation due to abnormal electrode erosion. However, the concentrated water C is subjected to treatment by the seawater electrolysis device 10 to increase the concentration of chlorine ions and the electrical conductivity. Thus, it is possible to stabilize treatment performance.

Furthermore, the augmented hydrogen gas is subjected to a degassing process by the hydrogen separator 90. So there is no chance that the hydrogen gas will damage the second pump 72 and the piping that are subsequent to the storage tank 50.

Furthermore, as the circulation part 80 is installed, the plate compositions such as manganese, magnesium and calcium, generated during electrolysis are introduced into the main body Ú of the electrolysis vessel 20 together with the electrolyzed water E. Then, the E electrolysed water containing plate compositions is again introduced into the main body of electrolysis container 20, thus making it possible to prevent the deposition of plates on the surface of the electrode 30 by crystallization effects by seeding the plate compositions .

That is, the plaque compositions act as seed crystals and newly generated plaques are deposited on the seed crystals. Thus, it is possible to avoid the precipitation of plaques on the surface of the electrode 30. It is thus possible to improve the durability of the electrode 30 and also to suppress the reduction in the efficiency in the generation of chlorine.

When the electric current density on the surface of electrode 30 is excessively large, eg in excess of 60 A/dm?, the plates are generated at an anode A and a cathode K in such a quantity that it exceeds a quantity when the hydrogen washing effect is effective. In contrast, in the present modality, as an upper limit of the electric current density is set at 60 A/dm?, it is possible to effectively exert the washing effect due to the hydrogen and effectively prevent the deposition of —plates on the anodeA «e on cathode K. Furthermore, when an upper limit of the electrical current density is set at 50 A/dm?, it is possible to effectively develop the hydrogen washing effect and effectively prevent plaque deposition.

As described above, in the present embodiment, an anode A coating material contains an iridium oxide and the electrical current density at the surface of electrode 30 is set in a range of 20 A/dm? at 60 A/dm? and preferably in a range of 20 A/dm? at 50 A/dm?. Thus, it is possible to effectively obtain the washing effect due to the hydrogen gas. Thus, it is possible to improve the resistance of electrode 30 and suppress the

Bduction of effectiveness in the generation of chlorine preventing the deposition of plates on the electrode 30.

So, in addition to improvements in the maintenance of the seawater electrolysis device 10, the number of electrodes 30 can be decreased to decrease the device size due to a greater efficiency in chlorine generation.

In the above embodiment, an explanation has been made of the electrode 30 with respect to an example using a double pole electrode plate 31. However, it is acceptable that, by example, an anode plate 32 and a cathode plate 33 are disposed oppositely between a, without using the double pole electrode plate 31 and for an electric current to pass through the seawater W between the anode plate 32 and the cathode plate 33. It is also acceptable Ie the anode plate 32 and the plate cathode 33 are alternately arranged, in which case electrical current passes through the sea water W between the anode plate 32 and the cathode wire 33 which are adjacent and opposite each other. Furthermore, in the above modality, 1st double pole electrode plate 31 is arranged such that an anode A faces the seawater inlet side and a cathode K faces the outlet side. fa of sea water. However, the double pot electrode plate 31 can be arranged in such a way that anode A is facing the seawater inlet side and cathode K [is facing the seawater inlet side.

Furthermore, in the present embodiment, it is adopted that the seawater desalination device 65 using an RO membrane as a device for concentrating the tar water W generates the concentrated water C. However, the device for generating the concentrated water is not is restricted. to the above device and, for example, a method for concentrating seawater W using a distillation method can be adopted.

Furthermore, a method for separating hydrogen gas from electrolyzed water mixed with hydrogen E is not restricted to the method of the present embodiment in which the hydrogen separator 90 with the spray nozzle 94 is used, but may include a method in which the gas separator -liquid using a centrifugal machine, for example, is used as long as a gas-liquid mixing fluid can be separated into a gas and a liquid. It is also accepted that hydrogen is separated by not separately installing the hydrogen separator 90 as a gas-liquid separator, but by adding the storage tank 50, eg a gas-liquid separation function. liquid to dilute hydrogen gas by supplying air to a liquid phase.

In addition, the electrolyzed water E can all be supplied to the inlet 1, with a circulating part 80 installed, if the deposition of plates on the surface of the electrode 30 is not a problem.

Example Next, an explanation will be made of an example.

(Test of determination of effectiveness in the generation of chlorine)

A test was conducted to study a relationship between a current:electrical density at the surface of an electrode and the effectiveness of chlorine generation during the electrolysis of seawater W and concentrated water C. An anode plate and a plate of cathode were provided, each of which was a plate with an electrode area of 50 x 50 mm and arranged opposite each other with a 5 mm gap. Such as anode plate, used as a titanium base plate coated with a coating material containing an iridium oxide (1/02) in 50% or more by mass ratio. Furthermore, a titanium base plate free of a coating material was used as the cathode plate. The chlorine ion concentration in seawater W was 20,000 mg/L and the chlorine ion concentration in the concentrated water W was 30,000 a

40,000 mg/L. The anode plate and cathode plate were immersed in seawater W and concentrated water C. Seawater W and concentrated water C were distributed at a flow rate of 250 mL/min and an electric current was passed. between the anode plate and the cathode plate for electrolysis. Next, a determination was made for the effectiveness in generating chlorine at each electric current density. ' Efficiency in the generation of chlorine means a ratio of the amount of chlorine that is actually generated to the amount of chlorine that can theoretically be generated based on the " electric current density of distributed electric current. Fig. 9 shows the result determination of chlorine generation efficacy. As shown in FIG. 9, when the electric current density is less than 20 A/dm?, both sea water W and concentrated water C have chlorine generation efficacy increased with an increase in electric current density Unconcentrated seawater W is effective at constant chlorine generation, — when the electric current density is in a range of 20 A/dm? to 30 A/dmº? and dimi - gradually reduces the efficiency in the generation of chlorine when the electric current density | exceeds 30 A/dm?. Furthermore, when the electric current density is 20 A/dm? or 30 | Aldm?, the efficiency in the generation of chlorine is the highest value obtained, that is, 96%. | It was concluded that when the electric current density is 15 A/dm?, which is obtained as technical common sense for an electrode coated with a platinum-containing coating material, the chlorine generation efficiency is 93%. From this fact, it is now understood that even for seawater W, in an electrode coated with a coating material containing iridium oxide, the electric current density is configured to be in the range of 20 A/dm? at 30 A/dm?, thus making it possible to obtain a high efficiency in the generation of chlorine. The high efficiency in chlorine generation is considered to be caused by the increase in the amount of hydrogen gas generated resulting in the effect of washing the plates deposited on an anode plate and a cathode plate by hydrogen gas. ' An amount of chlorine that can theoretically be generated increases with an increase in electric current density. So, even when the efficiency in the generation of : chlorine shows the same value, a greater amount of chlorine is generated when the electrical current density is greater.

Thus, when the electric current density is set at 40 Aldm?, the chlorine generation efficiency is 93%, which is equivalent to the electric current density of 15 A/dm?. However, an amount of chlorine generated is greater at the electric current density of 40 A/dm2 than at the electric current density of 15 A/dm?. So is it effective to set the electric current density to 40 A/dm? in view of an amount of chlorine generated. On the other hand, when the electric current density exceeds 40 Aldm”?, it is outside a range where the washing effect can be effectively developed due to hydrogen gas. In addition, the chlorine generation efficiency is reduced compared to the electric current density of 15 A/dm?. Then, an upper limit of the electric current density is preferably set at 40 Afdm?. In this way, it was concluded that a greater amount of generated chlorine can be ensured, while the efficiency in the generation of chlorine is also kept high. When is the electrical current density in a range of 20 A/dm? at 50 " Aldm?, the concentrated water C is effective in generating constant chlorine. When the electric current density is set at 60 A/dm?, the concentrated water C maintains a high efficiency in the generation of chlorine, ie , 96%.

As is clear from the above description, is concentrated water C capable of achieving greater chlorine generation efficiency by setting the electric current density to be in a range of 20 A/dm? at 60 A/dm?. It was concluded that the electric current density can be made high compared to seawater W without being concentrated.

As described above, the chlorine generation efficacy determination test revealed that concentrated water C is introduced into the seawater electrolysis device 10, the electric current density at the electrode surface during electrolysis is set in the range of 20 A/dm? at 60 A/dm? and preferably in a range of 20 A/dm? at 50 — A/dm?, thus making it possible to obtain a high efficiency in the generation of chlorine.

The electrode gradually erodes when electrolysis is carried out for an extended period of time. Thus, the curve indicating the result in the determination in FIG. 9 is considered steeper. In addition, it is assumed that the most effective electric current density is set in the above range, in particular after electrode erosion.

(Electrolysis Lifetime Test Results) A test was conducted to study a relationship between an electric current density during seawater electrolysis W and an amount of catalyst retention.

As with the chlorine generation efficacy determination test, an anode plate and a cathode plate were provided, each of which was a plate with an electrode area of 50 x 50 mm and arranged opposite each other, with a range of 5 mm. ] Two types of electrode plates were prepared as the anode plate, that is, a titanium-based plate coated with a coating material containing iridium oxide (1rO2) at 50% or more mass ratio and a base plate titanium coated with a platinum (Pt)-containing coating material. A titanium base plate free of a coating material was used as the cathode plate.

The anode plate and the cathode plate were respectively immersed in seawater W, and the same was distributed at a flow rate of 250 mL/min.

Additionally, an electrical current is passed between the anode plate and the cathode plate for electrolysis.

Then, the determination was made for an amount of catalyst retention at each electric current density with time.

Catalyst retention amount means an amount of electrode catalyst retained after electrolysis.

The amount of catalyst retention decreases with time, whereby the electrode consequently erodes.

FIG. 10 shows the result of determining the amount of catalyst retention.

As shown in FIG. 10, it was concluded that when the titanium base plate coated with the platinum (Pt/Ti)-containing coating material is used as the anode plate, the amount of catalyst retention gradually decreases over time and In particular, the amount of catalyst retention apparently decreases with an increase in electric current density.

On the other hand, when the titanium base plate coated with the coating material containing iridium oxide (I/O 2 ) is used as the anode plate, the amount of re- | Catalyst voltage does not decrease over time. ! Thus, it was concluded that the anode plate coated with the coating material containing iridium oxide has greater electrode resistance than the anode plate coated with the coating material containing platinum.

Industrial Applicability The present invention relates to a seawater electrolysis system which is provided with a seawater electrolysis device to generate hypochlorous acid by performing seawater electrolysis and also relates to a method for seawater electrolysis.

According to the present invention, it is possible to improve the resistance of an electrode and suppress the reduction in the efficiency in the generation of chlorine by preventing the deposition of plates on the electrode.

Description of Reference Numbers

A: anode

' K: cathode M: electrode group

] W: sea water

C: concentrated water 10: seawater electrolysis device 20: electrolysis vessel main body 30: electrode 31: double pole electrode plate 32: anode plate 33: cathode plate 40: power supply unit 60 : inlet part 65: seawater desalination device (concentrating device) 70: filling part

80: circulation part

' 81: circulation flow path 90: hydrogen separator (hydrogen separation device)

" 100A, 100B, 100C: seawater electrolysis system

Claims (18)

CLAIMS ' 1. Seawater electrolysis device, CHARACTERIZED by the fact that it comprises: ' an anode which is made of titanium coated with a coating material containing iridium oxide, a cathode, a main body of an electrolysis vessel which houses the anode and the cathode, and a power supply unit that passes an electrical current between the anode and the cathode, where the seawater electrolysis device passes an electrical current between the anode and the cathode. How is an electrical current density at the surface of the anode and cathode included in a range of 20 A/dm? or more and 40 A/dm? or less to electrolyze seawater inside the main body of electrolysis vessel. 2. Seawater electrolysis device, according to claim 1, CHARACTERIZED by the fact that: the density of electric current on the surface of the anode and that of the cathode between which the electric current is passed by the power supply unit is included in a 20 A/dm range? or more and 30 A/dm? or less. ' 3. Seawater electrolysis device, according to claim 1, CHARACTERIZED by the fact that tantalum oxide is added to the coating material. 4. Seawater electrolysis device according to claim 1, CHARACTERIZED by the fact that: the electrode includes a plurality of double pole electrode plates in each of which a part of it in a water distribution direction from the sea is given as the anode and the other part is given as the cathode, several electrode groups, in which the double pole electrode plates are arranged at an interval in the distribution direction, are arranged parallel to each other, and the double pole electrode plates on electrode groups adjacently parallel to each other are arranged in such a way that the anode is opposite the cathode. 5. Seawater electrolysis device according to claim 4, “CHARACTERIZED by the fact that: a gap between the double pole electrode plates that are adjacent in the distribution direction in each of the electrode groups is set to be 8 times or more an interval between groups of electrodes that are adjacently parallel to each other. 6. Seawater electrolysis device according to claim 1, further CHARACTERIZED by the fact that it comprises: one or more main bodies of electrolysis container, one or more connecting pipes, each of which connects a seawater outlet port of one of the electrolysis vessel main bodies with a seawater inlet port of the other electrolysis vessel main body, and: one or several degassing units to remove a gas inside the connecting pipes. 7. Seawater electrolysis system, CHARACTERIZED by the fact that it comprises: the seawater electrolysis device, according to any one of claims 1 to 6; and a circulation flow path that mixes the seawater, after electrolysis, flowing from the outlet port of the electrolysis vessel main body with the seawater before flowing to the electrolysis vessel main body from of the entrance door. 8. Seawater electrolysis method using the seawater electrolysis device, according to any one of claims 1 to 6, CHARACTERIZED by the fact that: ' seawater is introduced into the main body of electrolysis container , is an electrical current passed between the anode and the cathode in such a way that an electrical current density at the surface of the anode and cathode is included in a range of 20 A/dm? or more and 40 A/dm? or less to electrolyze seawater inside the main body of electrolysis vessel. 9. Seawater electrolysis system, CHARACTERIZED by the fact that it comprises: a seawater electrolysis device having an anode that is made of titanium coated with a coating material containing iridium oxide, a cathode, a main body of an electrolysis vessel that houses the anode and cathode, and a power supply unit that passes an electrical current between the anode and the cathode, and a concentration unit to increase the concentration of chloride ions contained in the water of the to be introduced into the main body of the electrolysis vessel, where an electrical current is passed between the anode and the cathode to electrolyse the sea water within the main body of the electrolysis vessel. 10. Seawater electrolysis system, according to claim 9, CHARACTERIZED by the fact that: the density of electric current on the surface of the anode and cathode between which the electric current is passed by the power supply unit is included in a 20 A/dm range? or more and 60 A/dm? or less. 11. Seawater electrolysis system, according to claim 9, 'CHARACTERIZED by the fact that: the density of electric current on the surface of the anode and cathode between which S the electric current is passed by the source unit of power is included in a —20 A/dm range? or more and 50 A/dm? or less. 12. Seawater electrolysis system, according to claim 9, CHARACTERIZED by the fact that it is provided with a hydrogen separation device to separate the hydrogen gas generated at the cathode from the seawater after the electro - lysis. 13. Seawater electrolysis system according to claim 9, CHARACTERIZED by the fact that it is provided with a circulation flow path that mixes seawater, after electrolysis, which is discharged from the main body of electrolysis container with sea water to be introduced into the main body of electrolysis container. 14. Seawater electrolysis system, according to claim 9, CHARACTERIZED by the fact that tantalum oxide is added to the coating material. 15. Seawater electrolysis system according to claim 9, 'CHARACTERIZED by the fact that: the electrode includes a number of double pole electrode plates on which a portion of these in a seawater distribution direction is given as the anode and the other part is given as the cathode, | several groups of electrodes, in which the double pole electrode plates are arranged at an interval in the distribution direction, are arranged parallel to each other, and the double pole electrode plates on each of the electrode groups adjacently Parallel to each other are arranged in such a way that the anode is opposite the cathode. 16. Seawater electrolysis system according to claim 15, CHARACTERIZED by the fact that: a gap between the double pole electrode plates that are adjacent in the distribution direction in each of the electrode groups is set to be 8 times or more an interval between groups of electrodes that are adjacently parallel to each other. 17. Seawater electrolysis method using the seawater electrolysis device according to any one of claims 9 to 16, CHARACTERIZED by the fact that: the concentration of chloride ions contained in seawater that is subjected to it - trolysis is increased, seawater with increased concentration of chloride ions is introduced into the main body of electrolysis vessel, and an electric current is passed between the anode and cathode to electrolyze the sea water inside the main body of electrolysis vessel. 18. Seawater electrolysis method according to claim 18, CHARACTERIZED by the fact that: the density of electric current on the surface of the anode and cathode between which the electric current is passed by the power supply unit is included in a 20 A/dm range? or more and 60 A/dm? or less.