KR20130079569A - Seawater electrolysis system and seawater electrolysis method - Google Patents

Abstract

This seawater electrolysis device is an electrolytic cell containing an anode (A) made of titanium coated with a coating material containing iridium oxide, an electrode (30) containing a cathode (C), and an anode (A) and a cathode (C). A power supply device 40 is provided between the main body 20 and the positive electrode A and the negative electrode C so that the current density of the surface of the positive electrode is 20 A / dm 2 or more, and the seawater in the electrolytic cell main body 20 is provided. Electrolysis.

Description

Seawater electrolysis system and seawater electrolysis method {SEAWATER ELECTROLYSIS SYSTEM AND SEAWATER ELECTROLYSIS METHOD}

TECHNICAL FIELD This invention relates to the seawater electrolysis system provided with the seawater electrolysis apparatus which produces hypochlorous acid by electrolyzing seawater, and a seawater electrolysis method.

Conventionally, in a thermal power plant, a nuclear power plant, a seawater desalination plant, a chemical plant, etc., which use a large amount of seawater, the propagation of algae or shellfish in the parts in contact with the seawater, such as water intake, piping, condensers, and various coolers, etc. It becomes a big problem.

In order to solve this problem, seawater electrolysis apparatuses which produce hypochlorous acid by electrolyzing natural seawater and injecting the hypochlorous acid into the intake port to suppress adhesion of marine organisms have been proposed (for example, a patent) See Document 1).

That is, this seawater electrolytic apparatus has the structure in which the anode and the cathode as electrodes were arrange | positioned in the electrolytic cell main body which forms a case shape, and seawater is distribute | circulated in the said electrolytic cell main body. Since chloride ions and hydroxide ions are present in seawater, chlorine is produced at the anode and sodium hydroxide is produced at the cathode when an electric current flows between the anode and the cathode. And chlorine and sodium hydroxide react, and the hypochlorous acid which has the effect of inhibiting adhesion of marine organisms is produced | generated.

Here, as an electrode disposed in the electrolytic cell of the seawater electrolytic apparatus, in particular an anode, a coating of a composite metal mainly composed of platinum on a titanium substrate, that is, a platinum main coating material is generally used (for example, Patent Document 2 Reference).

Moreover, although there is no example of practical use as a seawater electrolytic apparatus, it is proposed to apply a composite metal mainly composed of iridium oxide, that is, an iridium oxide main coating material, as a coating material for an anode of electrolysis (for example, Patent Document 3). Reference).

Moreover, the seawater electrolysis apparatus which uses concentrated water with a high salt concentration discharged from seawater concentration apparatuses, such as a seawater desalination apparatus, as a treated water is also known. This seawater electrolytic apparatus reduces the power consumption by increasing the concentration of hypochlorous acid in the electrolytically treated water produced by electrolyzing concentrated water, and aims at making the seawater electrolytic apparatus more efficient and smaller (for example, Patent Document 4). Reference).

Japanese Patent Publication No. 3389082 Japanese Laid-Open Patent Publication 2001-262388 Japanese Patent Application Laid-open No. Hei 8-85894 Japanese Patent Laid-Open No. 9-294986

By the way, in the electrode using a platinum main body coating material, consumption of an electrode advances rapidly by the influence of the oxygen generate | occur | produced in the vicinity of a positive electrode at the time of electrolysis, and the scale (calcium, magnesium, etc.) which generate | occur | produces in the vicinity of a negative electrode. For this reason, it is necessary to frequently perform electrode cleaning or electrode exchange, and maintenance costs are high.

In addition, it is considered that the higher the current density at the electrode surface, the higher the chlorine generation efficiency. This tendency also appears in the case of introducing hypochlorous acid by introducing concentrated seawater into the seawater electrolyzer.

However, when the current density is increased, the amount of oxygen generated near the anode and the scale generated near the cathode also increases, so that electrode consumption is rapidly advanced. Therefore, in the electrode using a platinum-based coating material, the current density at the surface of the electrode cannot be increased. For example, it is common knowledge that the maximum value of the current density is reduced to about 15 A / dm 2.

Since it is necessary to suppress the current density of electrolysis in this way, in order to generate | occur | produce sufficient hypochlorous acid from seawater, many electrodes need to be arrange | positioned, resulting in the increase of manufacturing cost of an apparatus, and enlargement of an apparatus.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and provides a seawater electrolysis apparatus, a seawater electrolysis system, and a seawater electrolysis method capable of improving the durability of the electrode and suppressing a decrease in chlorine generation efficiency. The purpose.

Here, as a result of the inventors earnestly researching the electrode of the seawater electrolytic apparatus, the anode coated with the iridium oxide main coating material is 15 A / dm 2 as opposed to the common knowledge of the conventional electrode coated with the platinum main coating material. It has been found that energizing excess current density is effective for improving the durability of the electrode and reducing the decrease in the chlorine generation efficiency.

That is, the seawater electrolytic apparatus according to the present invention includes an anode made of titanium coated with a coating material containing iridium oxide, an electrode including a cathode, an electrolytic cell body accommodating the anode and the cathode, the anode and the cathode It is provided with a power supply device which energizes so that current density of an anode surface may be 20 A / dm <2> or more in between.

According to the seawater electrolytic method according to the present invention, seawater is circulated in the electrolytic cell body, and electricity is supplied between the positive electrode and the negative electrode so that the current density on the surface of the positive electrode is 20 A / dm 2 or more, and the seawater in the electrolytic cell body is electrolyzed. do.

In the present invention, since the current density at the electrode surface is 20 A / dm 2 or more, which is larger than the conventional 15 A / dm 2, the amount of hydrogen gas generated at the cathode along with electrolysis increases as compared with the conventional one. do. Since the washing effect of an electrode is expressed by this large amount of hydrogen gas, adhesion of manganese scale to an anode and adhesion of scales, such as calcium and magnesium, at a cathode can be prevented. In addition, although the amount of oxygen generated near the anode is also increased, since iridium oxide has sufficient durability against oxygen, it is possible to prevent the electrode from being consumed by the oxygen.

In this invention, the current density of the surface of the said positive electrode and the said negative electrode which are energized by the said power supply apparatus may be contained in 20 A / dm <2> or more and 40 A / dm <2> or less. Preferably, you may be included in the range of 20 A / dm <2> or more and 30 A / dm <2> or less.

When the current density is too large, for example, when it exceeds 40 A / dm 2, the amount of scale generated at the anode and the cathode exceeds the effective range of the washing effect of hydrogen. In contrast, in the present invention, since the upper limit of the current density is 40 A / dm 2 and preferably 30 A / dm 2, the cleaning effect can be effectively expressed by hydrogen, and the It is possible to effectively prevent scale attachment.

The seawater electrolytic apparatus according to the present invention further includes a plurality of the electrolyzer main bodies, a connecting tube connecting the outlet and the inlet of the seawater in the electrolyzer main bodies, and gas removing means for removing gas in the connecting tube. You may provide it.

As the current density is increased, the liquid gas ratio decreases due to hydrogen generation at the cathode, so that the chlorine generation efficiency is lowered. On the other hand, by removing especially hydrogen gas by the gas removal means formed in the connection pipe, the inside of an electrolytic cell can be suppressed below predetermined liquid gas ratio, and the efficiency fall can be prevented.

The seawater electrolytic system according to the present invention includes the seawater electrolytic apparatus according to the present invention described above, and a concentrating means for increasing the concentration of chloride ions contained in the seawater to be introduced into the electrolytic cell body.

The seawater electrolytic method according to the present invention increases the concentration of chloride ions contained in seawater to be electrolyzed, distributes seawater having a high chloride ion concentration in the electrolyzer body, and energizes the electrolyzer body through the anode and the cathode. Electrolyze seawater inside.

In this invention, the concentrated water which raised chloride ion concentration and electrical conductivity is introduce | transduced into a seawater electrolysis apparatus. Moreover, since iridium oxide is contained in the coating material of a positive electrode, the current density in an electrode surface can be set high, and the density | concentration of the hypochlorous acid contained in the electrolytically-processed water produced can be raised. That is, by increasing the generation amount of hypochlorous acid per unit area of the electrode, the electrode area can be reduced, and the device can be miniaturized.

In this invention, the current density of the surface of the said positive electrode and the said negative electrode which are energized by the said power supply apparatus may be contained in 20 A / dm <2> or more and 60 A / dm <2> or less. Preferably, you may be included in the range of 20 A / dm <2> or more and 50 A / dm <2> or less.

When the current density is too large, for example, when it exceeds 60 A / dm 2, the amount of scale generated at the anode and the cathode exceeds the effective range of the washing effect of hydrogen. In contrast, in the present invention, since the upper limit of the current density is set to 60 A / dm 2, preferably 50 A / dm 2, the cleaning effect can be effectively expressed by hydrogen, and the It is possible to effectively prevent scale attachment.

The seawater electrolysis system according to the present invention may further include hydrogen separation means for separating the hydrogen gas generated in the cathode from the seawater after the electrolysis. Thereby, the washing | cleaning effect by hydrogen gas can be expressed more effectively, and scale adhesion at an anode and a cathode can be effectively prevented.

In the seawater electrolytic apparatus according to the present invention, an oxide of tantalum may be added to the coating material.

By adding tantalum, which is highly resistant to oxygen, to the coating material, it is possible to improve durability against oxygen generated at the anode and to prevent abnormal consumption of the electrode more effectively.

In the seawater electrolysis apparatus according to the present invention, the electrode includes a plurality of bipolar electrode plates in which one side portion of the seawater flow direction becomes the positive electrode and the other side portion becomes the negative electrode. A plurality of electrode groups formed by arranging the bipolar electrode plates at intervals in the flow direction may be arranged in parallel to each other, and the bipolar electrode plates of the electrode groups adjacent to each other in parallel to each other may be disposed to face the positive electrode and the negative electrode. .

In this way, by intensively disposing the positive electrode plate having the positive electrode and the negative electrode, the device itself can be miniaturized.

Moreover, since each bipolar electrode plate is arrange | positioned along the distribution direction of seawater, distribution of seawater is not obstructed. Thereby, since the flow velocity of seawater can be kept high, the effect of preventing scale adhesion to the electrode by the seawater can be obtained effectively.

In addition, since the anode and the cathode of the electrode groups adjacent to each other in parallel to each other face each other, it is possible to conduct electrolysis to the seawater flowing through the electrodes efficiently by energizing the anode and the cathode.

In the seawater electrolytic apparatus according to the present invention, the distance between the bipolar electrode plates adjacent in the flow direction in each of the electrode groups may be 8 times or more than the distance between the electrode groups adjacent to each other in parallel.

When the distance between the two pole electrode plates which adjoin in a flow direction is small, the electric current which distributes between these two pole electrode plates, ie, an endnote electric current with small contribution to electrolysis, generate | occur | produces. This endnote current becomes remarkable as the current density at the electrode surface increases. On the other hand, by adequacy of the space | interval of the adjacent bipolar electrode plates in a flow direction as mentioned above, generation | occurrence | production of the said vagus current can be suppressed and the fall of seawater electrolysis efficiency can be prevented.

In the present invention, the seawater electrolytic apparatus may include a circulation passage for mixing the seawater after electrolysis flowing out of the outlet of the electrolyzer body to the seawater before inflow from the inlet of the electrolyzer body.

The higher the current density, the more concerned the adhesion of the scale to the electrode surface. However, by mixing the seawater after electrolysis with the seawater before electrolysis through the circulation flow path, a seeding effect due to the scale component contained in the seawater passing through the electrolytic cell of the seawater electrolysis device is obtained, so that the scale is formed on the electrode surface. The adhesion can be prevented.

According to the present invention, adhesion of the scale to the electrode can be prevented, thereby improving the durability of the electrode and suppressing the decrease in the chlorine generation efficiency.

BRIEF DESCRIPTION OF THE DRAWINGS It is a schematic diagram which shows 1st Embodiment of the seawater electrolysis system concerning this invention.
It is a longitudinal cross-sectional view which shows the seawater electrolysis apparatus in 1st Embodiment.
3 is an enlarged view of a main part of the seawater electrolytic apparatus.
4 is a graph illustrating a constant current control curve of the constant current control circuit in the power supply device.
It is a schematic diagram which shows 2nd Embodiment of the seawater electrolysis system which concerns on this invention.
It is a schematic diagram which shows the modification of 2nd Embodiment.
It is a schematic diagram which shows 3rd Embodiment of the seawater electrolysis system which concerns on this invention.
8 is a schematic view showing a hydrogen separation device according to a third embodiment.
9 is a graph showing the results of a chlorine generation efficiency measurement test.
10 is a graph showing the results of an electrode consumption measurement test.

EMBODIMENT OF THE INVENTION Hereinafter, 1st Embodiment of this invention is described with reference to FIG.

The seawater electrolysis system 100A of 1st Embodiment collects seawater from the water intake channel 1 in which seawater flows, electrolyzes seawater with the seawater electrolysis apparatus 10, and then processes the treated seawater into a water intake channel. It is a system to inject into (1).

As shown in FIG. 1, this seawater electrolysis system 100A includes a seawater electrolysis apparatus 10, a storage tank 50, a water intake section 60, and a water supply section 70. As for the storage tank 50, the seawater W electrolyzed by the seawater electrolysis apparatus 10 is stored. The water intake unit 60 introduces the seawater W into the seawater electrolytic apparatus 10 from the water intake channel 1. The water supply part 70 injects the seawater W of the storage tank 50 into the water intake channel 1.

As shown in FIG. 2, the seawater electrolytic apparatus 10 includes an electrolyzer body 20, an electrode support box 26, terminal plates 28 and 29, and a plurality of electrodes 30.

The electrolyzer main body 20 is equipped with the substantially normal outer cylinder 21 which both ends open, The one end of the outer cylinder 21 is provided with the upstream lid part 22 which closes the opening of one end side. Further, at the other end of the outer cylinder 21, a downstream lid portion 24 that closes the opening at the other end side is formed. The electrolytic cell main body 20 is secured by predetermined external pressure 21 by these outer cylinders 21, the upstream lid part 22, and the downstream lid part 24. As shown in FIG.

Moreover, the inflow port 23 which communicates inside and outside of the electrolytic cell main body 20 is formed in the upstream cover part 22, and the outlet port 25 which communicates inside and outside the electrolytic cell main body 20 in the downstream cover part 24 is formed. Is formed. That is, in the electrolytic cell main body 20, the seawater W is introduced from the inlet port 23 of the upstream side lid part 22, and the seawater W enters the outer cylinder 21 from the inlet port 23 side through the outlet port. After flowing in one direction toward the (25) side, it flows out of the electrolytic cell main body 20 from the outlet 25. Hereinafter, the inflow port 23 side in the electrolytic cell main body 20 is called an upstream side, and the outflow port 25 side is called a downstream side.

The electrode support box 26 is a member made of an electrical insulating material such as plastic, for example, and is housed in the electrolytic cell main body 20 so as to extend in the flow direction of the seawater W. This electrode support box 26 is being fixed to the upstream lid part 22 and the downstream lid part 24 through the some fixing member 27. As shown in FIG. Moreover, the support bar 26a for supporting the electrode 30 is provided in the inside of the electrode support box 26 in multiple numbers.

The terminal plates 28 and 29 have a role of supplying a current from the outside of the electrolytic cell main body 20 to the electrode 30 supported in the electrode support box 26, and is provided at both ends of the electrode support box 26. One pair is arranged.

The electrode 30 has a plate shape, and a plurality of electrodes are fixedly supported in an arrayed state by the support bars 26a of the electrode support box 26. In the present embodiment, three kinds of the positive electrode plate 31, the positive electrode plate 32, and the negative electrode plate 33 are used as the electrode 30.

The bipolar electrode plate 31 has a structure in which a titanium substrate as an electrode substrate is divided into two parts, one of which is the anode A and the other is the cathode K. As shown in FIG. That is, the positive electrode plate 31 has a positive electrode (A) in which one half of the region is coated with a coating material (iridium oxide main coating material) containing iridium oxide on the surface, and the other half of the half region is the iridium oxide main body. The coating material is a negative electrode K which is not coated on the surface.

In addition, the positive electrode plate 32 has a structure in which the iridium oxide main coating material is coated on the entire surface of the titanium substrate, and the whole of the positive electrode plate 32 functions as the positive electrode A during electrolysis. On the other hand, as the negative electrode plate 33, a titanium substrate without coating is employed, and the entire negative electrode plate 33 functions as the negative electrode K during electrolysis.

Moreover, as for the said iridium oxide main coating material, content of iridium oxide is set to 50% or more by mass ratio, Preferably it is set to 60%-70% of range. Thereby, the coating effect by iridium oxide can be acquired favorably.

Moreover, it is preferable that tantalum is added to the iridium oxide main coating material. Moreover, it is preferable that this iridium oxide main coating material does not contain platinum.

Here, the arrangement structure of the three types of electrodes 30 in the electrode support box 26 is demonstrated. The bipolar electrode plate 31, the positive electrode plate 32 and the negative electrode plate 33 are fixedly supported by the support bars 26a in the electrode support box 26, respectively.

As shown in FIGS. 2 and 3, the bipolar electrode plate 31 of the electrode 30 faces the positive electrode A toward the liquid inlet side, and the negative electrode K toward the liquid outlet side. A plurality of directions are arranged so as to follow the flow direction of the seawater W. Moreover, these bipolar electrode plates 31 comprise the electrode group M by being arranged in series at intervals in the flow direction. The electrode groups M are formed in plural at intervals so as to be parallel to each other, that is, plural in parallel.

Here, the electrode groups M adjacent to each other in parallel to each other are arranged in a state in which they are shifted by a half pitch of the bipolar electrode plate 31 in the flow direction relatively. Thereby, in the bipolar electrode plate 31 between the electrode groups M adjacent to each other in parallel with each other, the anode A and the cathode K are in opposing states. In addition, in this embodiment, as shown in FIG. 3, the space | interval d1 of the bipolar electrode plate 31 which adjoins in the said flow direction in each electrode group M is adjacent to each other in parallel. It is preferable that it is set to 8 times or more of the space | interval of group M comrades, ie, the space | interval d2 of the bipolar electrode plates 31 adjacent to each other in parallel.

On the other hand, a plurality of positive electrode plates 32 are arranged parallel to each other along the flow direction of the seawater W on the downstream side of the positive electrode plate 31, and a plurality of negative electrode plates 33 on the upstream side of the positive electrode plate 31. It is arranged parallel to each other along the flow direction of (W).

The positive electrode plate 32 is connected to a terminal plate 29 on the downstream side of the pair of terminal plates 28 and 29 on the downstream side thereof, and the upstream end portions of these positive electrode plates 32 are each of the positive electrode plate ( 31) is opposed to the cathode K in the direction orthogonal to the flow direction. In other words, the upstream end of the positive electrode plate 32 and the negative electrode K of the bipolar electrode plate 31 are disposed to be offset from each other so as to overlap each other in the direction orthogonal to the flow direction. In addition, the negative electrode plate 33 has an upstream end thereof connected to a terminal plate 28 on the upstream side of the pair of terminal plates 28 and 29, and the downstream end portions of these negative electrode plates 33 each have the above-described positive electrode. It faces in the direction orthogonal to the anode A of the plate 31 in a flow direction. In other words, the downstream end portion of the negative electrode plate 33 and the positive electrode A of the bipolar electrode plate 31 are disposed to be offset from each other so as to overlap each other in the direction orthogonal to the flow direction.

The power supply device 40 is a device for supplying a current provided to the electrolysis of the seawater W, and includes a DC power supply 41 and a constant current control circuit 42. The DC power supply 41 is a power supply for outputting DC power. For example, the DC power supply 41 may rectify and output AC power output from an AC power supply with DC.

The constant current control circuit 42 is a circuit for outputting the DC power supplied from the DC power supply 41 as a constant current, and is capable of outputting a predetermined constant current to the current conducting port regardless of the change in the electrical resistance in the current conduction section. have. In other words, when the DC power is input from the DC power supply 41, the constant current control circuit 42 controls the voltage value of the DC power in the range of the amplitude ΔV as shown in FIG. The current value is output as a constant current.

In such a constant current control circuit 42, the anode A is connected to the downstream terminal plate 29 via a pair of lead wires 43 and 44, and the cathode K is connected to the upstream terminal plate 28. ) As a result, the constant current generated by the constant current control circuit 42 is supplied to the electrode 30 via the terminal plates 28 and 29.

Here, in the power supply device 40 of the present embodiment, the current density at the surface of the electrode 30 is 20 A / dm 2 to 40 A / dm 2, preferably 20 A / dm 2 to 30 A / dm 2. The constant current control circuit 42 generates a constant current so as to be in the range of. That is, by generating a constant current corresponding to the surface area of the electrode 30 in the electrolytic cell body 20 and supplying the constant current to the electrode 30, the current density on the surface of the electrode 30 is 20 A / dm 2 to 40 A / dm 2, preferably 20 A / dm 2 to 30 A / dm 2.

In addition, in the electrode coated with a composite metal (platinum main coating material) mainly composed of platinum, which has been used conventionally, the current density increases because the amount of oxygen and scale for advancing the electrode increases with increasing current density. The maximum value of is set to about 15 A / dm 2. In contrast, in the present embodiment, electrolysis is performed in a range of 20 A / dm 2 to 40 A / dm 2, preferably 20 A / dm 2 to 30 A / dm 2, which has a higher current density than conventionally. Doing.

The storage tank 50 is a tank in which the seawater W flowing out from the outlet 25 of the electrolytic cell main body 20 in the seawater electrolytic apparatus 10 is temporarily stored, and the outlet port of the electrolytic cell main body 20 ( Seawater W is introduced inside through an intermediate flow passage 51 connected to 25).

The water intake unit 60 includes a water intake passage 61, a first pump 62, a first flow meter 64, and a first open / close control valve 63.

The intake flow passage 61 is a flow passage connected to the intake port 23 of the electrolytic cell main body 20 in the seawater electrolytic apparatus 10 while one end is connected to the water intake channel 1.

The 1st pump 62 is formed in the middle of this water intake flow path 61, and this sea water is made by the said 1st pump 62 pumping seawater W of the water intake channel 1 to a constant output. (W) is introduced into the inlet port 23.

The first flowmeter 64 is formed downstream of the water intake passage 61, and detects the flow rate Q ₁ of the seawater W passing through the water intake passage 61.

Moreover, the 1st opening / closing control valve 63 is a valve provided in the upstream of the 1st flowmeter 64 in the water intake flow path 61, The flow volume of the seawater W which the 1st flowmeter 64 detects ( It is controlled to open and close based on Q ₁ ). Thereby, by adjusting the flow volume of the seawater W which distribute | circulates a water intake channel according to the area ratio of the seawater distribution area | region of the water intake flow path 61 and the electrolyzer main body 20, The flow rate can be arbitrarily adjusted.

In the seawater electrolysis apparatus 10 of this embodiment, it is preferable that the 1st opening / closing control valve 63 is controlled so that the flow velocity of the seawater W which flows in the electrolyzer main body 20 may be at least 0.7 m / s or more. Do.

Moreover, not only the flow rate of the seawater W in the electrolytic cell main body 20 is controlled by the opening / closing control of the 1st opening / closing control valve 63, but the electrolytic cell main body is controlled by controlling the output of the 1st pump 62, for example. You may adjust the flow velocity of the seawater W in (20).

The water supply part 70 includes a water supply flow path 71, a second pump 72, a second open / close control valve 73, and a second flow meter 74.

The main water flow passage 71 is a flow passage where one end is connected to the storage tank 50 and the other end is connected to the water intake channel 1.

The 2nd pump 72 is formed in the middle of this main water flow path 71, The said 2nd pump 72 sends this seawater W in the storage tank 50 by a constant output, and this seawater W ) Is introduced into the water intake channel 1.

A second flow meter 74, is formed on the downstream side of the flow path in the flow path age 71, and detects a flow rate (Q ₂₎ of the water (W) to the art through the flow path in weeks (71).

Moreover, the 2nd opening-closing control valve 73 is a valve provided in the upstream side of the 2nd flowmeter 74 in the main water flow path 71, The flow volume of the seawater W which the 2nd flowmeter 74 detects ( It is controlled to open and close based on Q ₂ ). Thereby, the flow volume of the seawater W injected into the water intake channel 1 is adjusted. In addition, by adjusting the opening / closing control of the second opening / closing control valve 73, not only the injection amount of the seawater W to the water intake channel 1 is adjusted, but also the water intake is controlled by controlling the output of the second pump 72, for example. You may adjust the injection amount of the seawater W with respect to the channel 1.

Next, the action of the seawater electrolysis apparatus 10 of this embodiment and the electrolytic method of the seawater W using the seawater electrolysis apparatus 10 are demonstrated.

Some of the seawater W circulating through the water intake channel 1 is introduced into the electrolyzer body 20 from the inlet port 23 of the electrolyzer body 20 of the seawater electrolytic apparatus 10 by the water intake unit 60. . That is, the sea water W of the water intake channel 1 is pumped into the water intake flow path 61 by the first pump 62, and thus, the sea water W is introduced into the electrolytic cell body 20 through the water intake flow path 61. Is introduced. Thereby, the electrode 30 in the electrolytic cell main body 20 is immersed in seawater W. As shown in FIG. At this time, the first opening / closing control valve 63 is opened and closed in accordance with the flow rate detected by the first flowmeter 64, so that the flow rate of the seawater W flowing in the distribution direction in the electrolytic cell main body 20 is adjusted to a desired value. do.

Thus, the electrolysis is performed by the electrode 30 to the seawater W which distribute | circulates the inside of the electrolyzer main body 20. As shown in FIG. That is, a desired constant current is generated in the constant current control circuit 42 based on the DC power of the DC power supply 41 in the power supply device 40, and the constant current is passed through the lead wires 43, 44 to the terminal plates 28, 29. Is supplied. The electric current supplied through these terminal plates 28 and 29 flows through the inside of the electrolytic cell main body 20 in series to the positive electrode plate 32, the positive electrode plate 31, and the negative electrode plate 33.

Specifically, when the current circulated from the constant current control circuit 42 to the positive electrode plate 32 reaches the negative electrode K of the positive electrode plate 31 via the seawater W, the inside of the positive electrode plate 31 is removed. By passing through, it reaches the positive electrode A of the said positive electrode plate 31, and after that, it distribute | circulates the seawater W to the negative electrode K of the other positive electrode plate 31 which opposes this positive electrode A, To reach. In this way, the current flows through the positive electrode plate 32 sequentially through the plurality of bipolar electrode plates 31 and finally through the negative electrode plate 33. Moreover, the current density in the surface of each electrode 30 of the electric current at this time is 20 A / dm <2> -40A / dm <2> by the constant current control circuit 42, Preferably it is 20 A / dm <2>- It is controlled in the range of 30 A / dm 2.

As described above, the current flowing through the seawater W is constant by the action of the constant current control circuit 42 so that the current density at the surface of the electrode 30 is constant regardless of the change in the electrical resistance of the seawater W. That is, although the value of the electric resistance of the seawater W flowing in the electrolyzer main body 20 changes every time, as shown in FIG. 4, the constant-current control circuit 42 controls a voltage to predetermined amplitude (DELTA) V, The current density at the surface of the electrode 30 is kept constant.

As above, electric current flows through the seawater W between the electrodes 30, and electrolysis is performed with respect to the seawater W. FIG.

That is, in the anode A, as shown by the following formula (1), electrons e are taken away from chlorine ions in the seawater W, oxidation occurs, and chlorine is generated.

[Equation 1]

2Cl ^- → Cl ₂ + 2e ... (One)

On the other hand, in the cathode K, as shown in following (2) Formula, an electron is provided to the water in seawater W, reduction produces | generates, and hydroxide ion and hydrogen gas are produced | generated.

&Quot; (2) &quot;

^{_{2H 2 O + 2e → 2OH -}} + H 2 ↑ ... (2)

Moreover, as shown in following formula (3), the hydroxide ion produced | generated by the cathode K reacts with the sodium ion in seawater W, and sodium hydroxide is produced | generated.

&Quot; (3) &quot;

2Na ^{+ +} 2OH ^- → 2NaOH ... (3)

In addition, as shown in Formula (4), when sodium hydroxide and chlorine react, hypochlorous acid, sodium chloride, and water are produced | generated.

&Quot; (4) &quot;

Cl ₂ + 2NaOH → NaClO + NaCl + H ₂ O... (4)

In this way, hypochlorous acid is produced which has an inhibitory effect on the adhesion of marine products based on the electrolysis of seawater W.

And the seawater W by which electrolysis was carried out flows out from the outlet 25 of the electrolytic cell main body 20, and is temporarily stored in the storage tank 50 through the intermediate flow path 51. As shown in FIG. Thereafter, the seawater W in the storage tank 50 is injected into the water intake channel 1 through the water supply part 70. That is, the seawater W containing hypochlorous acid in the storage tank 50 is injected into the water intake channel 1 through the main water passage 71 by operating the second pump 72. At this time, the second opening / closing control valve 73 opens and closes according to the flow rate detected by the second flowmeter 74, thereby adjusting the flow rate of the seawater W containing hypochlorous acid to the water intake channel 1.

Here, the manganese scale resulting from the manganese ion contained in the seawater W at the time of electrolysis is affixed to the anode A which coat | covered the iridium oxide main coating material generally. The adhesion of the manganese scale causes the consumption of the anode A to proceed, and the catalytic activity on the surface of the electrode 30 is lowered, resulting in a problem that the chlorine generation efficiency is lowered. Moreover, the scale resulting from the magnesium and calcium contained in the seawater W adheres to the cathode K, and consumption of the electrode 30 advances also by this scale.

On the other hand, according to the said embodiment, since the current density in the electrode 30 surface is set to 20 A / dm <2> or more larger than the conventional 15 A / dm <2>, in the cathode K with electrolysis The amount of hydrogen gas generated is increased compared with the prior art. Since the washing effect of the electrode 30 is expressed by this large amount of hydrogen gas, adhesion of manganese scale to the positive electrode A and adhesion of scales such as calcium and magnesium to the negative electrode K can be prevented. have.

In addition, the amount of oxygen generated in the vicinity of the anode A is also increased by increasing the current density on the surface of the electrode 30, but since iridium oxide has sufficient durability against oxygen, it contains the iridium oxide. The anode A coated with the coating material can be prevented from being consumed by oxygen.

In addition, when the current density on the surface of the electrode 30 is too large, for example, when it exceeds 40 A / dm 2, the amount of scale generated in the positive electrode A and the negative electrode K is effective for the cleaning effect of hydrogen. It exceeds the range. In contrast, in this embodiment, since the upper limit of the current density is 40 A / dm 2, the cleaning effect is effectively expressed by hydrogen, effectively preventing the adhesion of scales on the anode A and the cathode K. can do. Moreover, when the upper limit of current density is 30 A / dm <2>, the washing effect by hydrogen can be expressed more effectively, and adhesion of a scale can be prevented effectively.

As described above, in the present embodiment, iridium oxide is contained in the coating material of the anode A, and the current density on the surface of the electrode 30 is in the range of 20 A / dm 2 to 40 A / dm 2, preferably Since it is set to 20 A / dm 2 to 30 A / dm 2, the cleaning effect by hydrogen gas can be effectively obtained. Thereby, since adhesion of the scale with respect to the electrode 30 can be prevented, it becomes possible to aim at the improvement of the durability of the electrode 30, and suppression of the fall of the chlorine generation efficiency.

Therefore, the maintenance property of the seawater electrolytic apparatus 10 can be improved, and the number of electrodes 30 can be reduced by high chlorine generation efficiency, and the apparatus can be miniaturized.

In addition, when tantalum oxide is added to the iridium oxide main coating material covering the anode A, since the tantalum exhibits high durability against oxygen, the electrode 30 by oxygen generated near the anode A Can be prevented more effectively.

Moreover, cost can be aimed at by not containing platinum in this iridium-oxide main coating material.

In addition, in this embodiment, the electrode group M is arrange | positioned in series and the electrode group M is arrange | positioned in parallel, and many electrode electrodes 31 are arranged in parallel with each other. ), The device itself can be miniaturized while largely securing the total amount of chlorine generated.

Moreover, since each bipolar electrode plate 31 is arrange | positioned along the distribution direction of the seawater W, distribution of the seawater W is not obstructed. Thereby, the flow velocity of the seawater W can be maintained high, and the effect of preventing the adhesion of the scale to the electrode 30 can be effectively obtained.

And since the positive electrode A and the negative electrode K of the electrode groups M which are adjacent to each other in parallel to each other face each other, the current flows between the positive electrode A and the negative electrode K, thereby between the electrodes 30. Electrolysis can be performed efficiently with respect to the seawater (W) which distribute | circulates.

Here, when the distance between the two pole electrode plates 31 which adjoin in the flow direction of seawater W is small, the electric current which flows through these two pole electrode plates 31, ie, the contribution to electrolysis is small Endnote current occurs. This vault current becomes remarkable as the current density on the surface of the electrode 30 becomes higher, resulting in a decrease in seawater electrolytic efficiency.

On the other hand, in this embodiment, the space | interval d1 of the bipolar electrode plate 31 comrades which adjoins in the flow direction in each electrode group M is the space | interval of electrode groups M which adjoin parallel to each other. Since it is set to 8 times or more of (d2), that is, the optimization of the space | interval of the adjacent bipolar electrode plates 31 adjacent to a flow direction is aimed at, generation | occurrence | production of the said vagus current is suppressed and the fall of seawater electrolytic efficiency falls Can be prevented.

Next, the seawater electrolysis system 100B of 2nd Embodiment which concerns on this invention is demonstrated with reference to FIG. In addition, in 2nd Embodiment, the same code | symbol is attached | subjected about the component same as 1st Embodiment, and detailed description is abbreviate | omitted.

As shown in FIG. 5, in the seawater electrolysis system 100B of the second embodiment, the main water flow passage 71 between the water intake passage 61 of the water intake unit 60 and the main water passage 71 of the water injection unit 70. Circulation portion 80 for mixing the seawater W of This circulation portion 80 includes a circulation flow path 81, a third flow meter 84, and a third open / close control valve 83.

The circulation flow path 81 is a flow path where one end is connected to the main water flow passage 71 and the other end is connected to the water intake flow passage 61. In this embodiment, one end of the circulation flow path 81 is connected between the 2nd pump 72 and the 2nd opening-closing control valve 73 in the main water flow path 71, and The other end is connected between the first pump 62 and the first opening / closing control valve 63 in the water intake passage 61.

The third flowmeter 84 is formed in the middle of the circulation flow path 81 and detects the flow rate Q ₃ of the seawater W passing through the circulation flow path 81.

Moreover, the 3rd opening-closing control valve 83 is a valve provided in the downstream of the 3rd flowmeter 84 in the circulation flow path 81, The flow volume of the seawater W which the 3rd flowmeter 84 detects ( It is controlled to open and close based on Q ₃ ). Thereby, the flow volume of the seawater W circulated from the main water flow passage 71 to the water intake flow passage 61 through the circulation flow passage 81 can be arbitrarily controlled.

In such seawater electrolysis system 100B, when the seawater W after electrolysis stored in the storage tank 50 is introduced into the main water passage 71 by the second pump 72, the seawater W is In the branch portion of the main water flow passage 71 to which one end of the circulation flow passage 81 is connected, it is classified into seawater W for circulating the main water passage 71 and seawater W for circulating the circulation passage 81. ) do.

The seawater W passing through the circulation flow path 81 is introduced into the water intake flow path 61 at the other end of the circulation flow path 81. That is, the seawater W after electrolysis passing through the circulation flow path 81 joins the seawater W before electrolysis passing through the water intake flow path 61 and is introduced into the electrolytic cell main body 20 again. At this time, the third opening / closing control valve 83 opens and closes according to the flow rate detected by the third flowmeter 84, so that the seawater W after electrolysis joining the seawater W through which the water intake passage 61 flows. The flow rate can be adjusted.

Thus, the seawater W after electrolysis which flowed out from the outlet 25 of the electrolytic cell main body 20 flows in from the inflow port 23 of the electrolytic cell main body 20 by circulating the circulation flow path 81.

Here, scale components, such as manganese, magnesium, and calcium which existed at the time of electrolysis, exist in the seawater W after electrolysis. By introducing such seawater W into the electrolyzer main body 20 again, it is possible to prevent scale adhesion to the surface of the electrode 30 by the termination effect by the scale component. That is, since the scale component becomes the seed and the newly generated scale adheres to the seed, precipitation of the scale on the surface of the electrode 30 can be avoided. Thereby, it becomes possible to aim at the improvement of the durability of the electrode 30, and suppression of the fall of the chlorine generation efficiency.

As mentioned above, although embodiment of this invention was described in detail, it is not limited to these and a some design change etc. are possible, unless it deviates from the technical idea of this invention.

For example, in the seawater electrolysis system 100B, it is preferable that the hypochlorous acid concentration of the seawater W injected into the water intake channel 1 from the water supply section 70 is approximately 2500 ppm.

Here, the total amount of hypochlorous acid generated is generally proportional to the total amount of current supplied from the power supply device 40 to the electrode 30. Therefore, by recording the amount of current supplied to the electrode 30, the total amount of hypochlorous acid generated can be grasped. The hypochlorous acid concentration of the seawater W injected into the water intake channel 1 is calculated by dividing the total amount of hypochlorous acid generated by the flow rate Q ₂ of the seawater W injected into the water intake channel 1. can do. Therefore, according to the total amount of hypochlorous acid, by controlling the second opening / closing control valve 73 to determine the flow rate Q ₂ of the seawater W injected into the water intake channel 1, the hypothesis in the seawater W The chloric acid concentration can be easily adjusted to the 2500 ppm.

For example, as a modified example, as shown in FIG. 6, the seawater electrolytic apparatus 10 has the some electrolyzer main body 20, and the outlet 25 and the inlet 23 of these electrolyzer main bodies 20 comrades. ), And the gas removal valve 86 as a gas removal means which removes the gas in the connection pipe 85 may be provided. In addition, the gas removal valve 86 is a valve which can open and close control, and when the pressure in the electrolytic cell main body 20 rises to predetermined | prescribed high pressure, the said gas removal valve 86 will open, and the gas in seawater W will open. Is released.

The higher the current density, the lower the liquid gas ratio due to hydrogen generation at the cathode K. Thus, the chlorine generation efficiency is lowered. However, the gas removal valve 86 formed in the connection pipe 85 is particularly suitable for hydrogen gas. By eliminating this, the inside of the electrolytic cell main body 20 can be restrained below predetermined liquid gas ratio, and the efficiency fall can be prevented.

In addition, in the said embodiment, although the example which used the bipolar electrode plate 31 as the electrode 30 was demonstrated, for example, the positive electrode plate 32 and the negative electrode plate 33 without using the bipolar electrode plate 31 were demonstrated. May be disposed to face each other, and current may be supplied to the seawater W between these positive electrode plates 32 and the negative electrode plates 33. Moreover, you may arrange | position these positive electrode plates 32 and negative electrode plates 33 alternately, and may carry an electric current through the seawater W between the positive electrode plate 32 and the negative electrode plate 33 which oppose each other next to each other.

Moreover, in the said embodiment, although the positive electrode A is arrange | positioned toward the liquid inlet side and the negative electrode K is toward the liquid outlet side, the positive electrode A has the liquid outlet side. In addition, the cathode K may be disposed toward the liquid inlet side.

Next, the seawater electrolysis system 100C of 3rd Embodiment which concerns on this invention is demonstrated with reference to FIG. In addition, also in 3rd Embodiment, the same code | symbol is attached | subjected about the component same as 1st Embodiment, and detailed description is abbreviate | omitted.

As shown in FIG. 7, the seawater electrolysis system 100C of the third embodiment includes a seawater electrolysis device 10, a water intake unit 60, a hydrogen separation device 90, a storage tank 50, The water supply part 70 and the circulation part 80 are provided. The water intake unit 60 introduces the seawater W into the seawater electrolytic apparatus 10 from the water intake channel 1. The hydrogen separation device 90 separates hydrogen in the electrolytically treated water E discharged from the seawater electrolysis device 10. In the storage tank 50, the electrolytically treated water E electrolyzed by the seawater electrolytic apparatus 10 is stored. The water injection part 70 injects the electrolytic treatment water E of the storage tank 50 into the water intake channel 1. The circulation unit 80 circulates the electrolytically treated water E to the seawater electrolytic apparatus 10. The dewatering device 65 is formed in the water intake section 60.

Here, in the power supply device 40 of the present embodiment, the current density on the surface of the electrode 30 is 20 A / dm 2 to 60 A / dm 2, preferably 20 A / dm 2 to 50 A / dm 2. The constant current control circuit 42 generates a constant current so as to be in the range of. That is, by generating a constant current according to the surface area of the electrode 30 in the electrolytic cell main body 20 and supplying the constant current to the electrode 30, the current density at the surface of the electrode 30 is 20 A / dm 2 to 60 A / dm 2, preferably 20 A / dm 2 to 50 A / dm 2.

In addition, in the electrode coated with a composite metal (platinum main coating material) mainly composed of platinum, which has been used conventionally, the current density increases because the amount of oxygen and scale for advancing the electrode increases with increasing current density. The maximum value of is set to about 15 A / dm 2. In contrast, in the present embodiment, electrolysis is performed in the range of 20 A / dm 2 to 60 A / dm 2, preferably 20 A / dm 2 to 50 A / dm 2, which has a higher current density than conventionally. Doing.

The water intake unit 60 includes a water intake passage 61, a first pump 62, a desalination device 65, a first flowmeter 64, and a first open / close control valve 63.

The desalination apparatus 65 is an apparatus for separating seawater into fresh water (demineralized water) and concentrated water (C) using a reverse osmosis membrane (RO membrane). The fresh water separated by the desalination device 65 is sent to a fresh water tank (not shown) via the fresh water line 66, and the concentrated water C opens the first opening / closing control valve 63 of the water intake passage 61. It is introduced into the seawater electrolytic apparatus 10 through.

In the seawater electrolysis apparatus 10 of this embodiment, it is controlled that the 1st opening / closing control valve 63 is controlled so that the flow velocity of the concentrated water C which flows in the electrolyzer main body 20 may be at least 0.7 m / s or more. desirable.

Moreover, not only the flow rate of the concentrated water C in the electrolytic cell main body 20 is controlled by the opening / closing control of the first opening / closing control valve 63, for example, the electrolytic cell is controlled by controlling the output of the first pump 62. You may adjust the flow rate of the concentrated water C in the main body 20.

The hydrogen separation device 90 is a device for separating the hydrogen gas contained in the electrolytically treated water E flowing out from the outlet 25 of the electrolytic cell main body 20 in the seawater electrolytic apparatus 10. As shown in FIG. 8, the hydrogen separation device 90 has an outlet port of the electrolytic cell main body 20 via a fluid receiving tank 92 with an exhaust cylinder 91 formed thereon and an intermediate flow path 8. An inlet pipe 93 connected to the 25 and drawing electrolytically treated water into the gas phase part 92a above the infusion tank 92, a spray nozzle 94 formed in the middle of the inlet pipe 93, The stirrer 95 formed in the liquid-phase part 92b below the inside of the fluid tank 92 is provided.

The spray nozzle 94 injects the electrolytically treated water E introduced into the introduction pipe 93 to the gas phase part 92a above the inside of the infusion tank 92. The stirrer 95 consists of the screw 96 and the motor 97 which rotates this screw 96, and stirs the liquid gathered in the liquid-phase part 92b of the infusion tank 92. As shown in FIG. In addition, a discharge port 98 through which the electrolytic treatment water is discharged is formed in the lower part of the infusion tank 92.

The storage tank 50 is a tank in which the electrolytically treated water E discharged from the discharge port 98 in the hydrogen separation device 90 is temporarily stored.

The circulation portion 80 is a portion that circulates the electrolytic treatment water E flowing through the main water passage 71 in the water intake passage 61 of the water intake portion 60. This circulation section 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 where one end is connected to the main water flow passage 71 and the other end is connected to the water intake flow passage 61. In this embodiment, one end of the circulation flow path 81 is connected between the 2nd pump 72 and the 2nd opening-closing control valve 73 in the main water flow path 71, and The other end is connected between the first opening / closing control valve 63 and the first flowmeter 64 in the water intake passage 61.

A third flow meter 82, is formed in the midway of the circulation flow path 81, and detects a flow rate (Q ₃₎ of the electrolytic treatment (E) to the art through the circulation flow path 81.

Moreover, the 3rd opening-closing control valve 83 is a valve provided in the downstream of the 3rd flowmeter 82 in the circulation flow path 81, and it is the thing of the electrolytic-processed water E which the 3rd flowmeter 82 detects. Opening and closing control is performed based on the flow rate Q ₃ . Thereby, the flow volume of the electrolytically treated water E circulated from the main water flow passage 71 to the water intake flow passage 61 through the circulation flow passage 81 can be arbitrarily controlled.

Next, the action of the seawater electrolysis system 100C of the present embodiment and the electrolytic method of the seawater W using the seawater electrolysis system 100C will be described.

Some of the seawater W which distributes the water intake channel 1 is introduced into the desalination apparatus 65 by the water intake section 60. That is, the sea water W of the water intake channel 1 is pumped into the water intake flow path 61 by the first pump 62, and thus, the sea water W in the desalination device 65 through the water intake flow path 61. Is introduced. As a result, the sea water (W) is separated into fresh water and concentrated water (C).

The desalination apparatus 65 applies pressure to the seawater W and passes it through the RO membrane to concentrate the salts of the seawater W and to filter the freshwater. Thereby, the chloride ion concentration of seawater W is concentrated, for example from 20,000 mg / L to 30,000-40,000 mg / L, and concentrated water C is produced | generated. Fresh water is sent to a fresh water tank (not shown) which stores fresh water via the fresh water line 66, and the concentrated water C is introduced into the electrolyzer body 20 through the water intake passage 61.

Thereby, the electrode 30 in the electrolytic cell main body 20 is immersed in the concentrated water C. As shown in FIG. At this time, the first opening / closing control valve 63 is opened and closed in accordance with the flow rate detected by the first flowmeter 64, so that the flow rate of the concentrated water C flowing in the distribution direction in the electrolytic cell main body 20 is at a desired value. Adjusted.

Thus, the electrolysis is performed by the electrode 30 to the concentrated water C which distribute | circulates the inside of the electrolytic cell main body 20. As shown in FIG. That is, a desired constant current is generated in the constant current control circuit 42 based on the DC power of the DC power supply 41 in the power supply device 40, and the constant current is passed through the lead wires 43, 44 to the terminal plates 28, 29. Is supplied. The electric current supplied through these terminal plates 28 and 29 flows through the inside of the electrolytic cell main body 20 in series to the positive electrode plate 32, the positive electrode plate 31, and the negative electrode plate 33.

Specifically, when the current circulated from the constant current control circuit 42 to the positive electrode plate 32 reaches the negative electrode K of the positive electrode plate 31 via the concentrated water C, the inside of the positive electrode plate 31 is increased. By passing through, it reaches the positive electrode A of the said positive electrode plate 31, and distribute | circulates the inside of concentrated water to the negative electrode K of the other positive electrode plate 31 which opposes this positive electrode A, To reach. In this way, the current flows through the positive electrode plate 32 sequentially through the plurality of bipolar electrode plates 31 and finally through the negative electrode plate 33. The current density at the surface of each electrode 30 of the current at this time is 20 A / dm 2 to 60 A / dm 2, preferably 20 A / dm 2 to the constant current control circuit 42. It is controlled in the range of 50 A / dm 2.

As described above, the current flowing through the concentrated water C causes the current density on the surface of the electrode 30 to be constant regardless of the change in the electrical resistance of the concentrated water C due to the action of the constant current control circuit 42. . That is, in the concentrated water C circulating in the electrolytic cell main body 20, the value of the electric resistance changes every time, but as shown in FIG. 4, the constant current control circuit 42 controls the voltage to a predetermined amplitude ΔV. As a result, the current density at the surface of the electrode 30 is kept constant.

As mentioned above, electrolysis is performed with respect to the concentrated water C by an electric current distribute | circulating in the concentrated water between the electrodes 30. As shown in FIG.

That is, in the positive electrode (A), as shown in formula (1) in the first embodiment, the electron e is desorbed from chloride ions in the concentrated water (C) to oxidize to generate chlorine.

On the other hand, in the cathode K, as shown to (2) Formula in 1st Embodiment, an electron is provided to the water in the concentrated water C, and reduction produces | generates, and hydroxide ion and hydrogen gas are produced | generated.

Moreover, as shown by Formula (3) in 1st Embodiment, the hydroxide hydroxide produced | generated by the cathode K reacts with the sodium ion in concentrated water, and sodium hydroxide is produced | generated.

In addition, as shown in Formula (4) in 1st Embodiment, hypochlorite, sodium chloride, and water are produced | generated by reaction of sodium hydroxide and chlorine.

Thus, based on the electrolysis of the concentrated water (C), hypochlorous acid having an inhibitory effect on the adhesion of marine products is produced.

The concentration of hypochlorous acid is preferably 2,500 to 5,000 ppm because the chloride ion concentration of the concentrated water (C) is increased to 30,000 to 40,000 mg / L.

The concentrated water C subjected to electrolysis is discharged from the outlet 25 of the electrolytic cell main body 20 as the electrolytic treatment water E together with the hydrogen gas, and passes through the intermediate flow path 8 to form a hydrogen separation device. Flows into (90).

The gas-liquid mixed fluid consisting of hydrogen gas and electrolytically treated water (E) is introduced into the inlet tube 93 of the hydrogen separation device 90, and the gas phase portion 92a of the fluid receiving tank 92 is sprayed by the spray nozzle 94. Is sprayed on. Thereby, the hydrogen gas mixed in the electrolytic treatment water E as a bubble is degassed, and is exhausted from the exhaust cylinder 91.

On the other hand, the electrolytically treated water E is stored in the liquid phase part 92b of the infusion tank 92. As shown in FIG. The stored electrolytic treatment water E is stirred by the stirrer 95. That is, the electrolytic treatment water E is forcibly stirred by the swirl flow generated by the screw 96 rotating by the motor 97. This prevents the scale generated with electrolysis from being deposited at the bottom of the infusion tank 92. The electrolytically treated water E once stored in the infusion tank 92 is discharged | emitted from the discharge port 98 formed in the bottom part of the infusion tank 92, and is introduce | transduced into the storage tank 50. FIG.

When the electrolytically treated water E temporarily stored in the storage tank 50 is introduced into the main water passage 71 by the second pump 72, the electrolytically treated water E is connected to one end of the circulation passage 81. In the branched part of the main water flow passage 71, it is classified into electrolytically treated water E for circulating the main water passage 71 and electrolytically treated water E for circulating the circulation flow passage 81.

The electrolytic treatment water E which distributes the main water flow passage 71 is injected into the water intake channel 1. That is, the electrolytically treated water E containing hypochlorous acid in the storage tank 50 is injected into the water intake channel 1 through the main water passage 71 by operating the second pump 72. At this time, the second opening / closing control valve 73 is opened and closed in accordance with the flow rate detected by the second flowmeter 74, thereby adjusting the flow rate of the electrolytic treatment water E containing hypochlorous acid to the water intake channel 1. do.

Here, the total amount of hypochlorous acid generated is generally proportional to the total amount of current supplied from the power supply device 40 to the electrode 30. Therefore, by recording the amount of current supplied to the electrode 30, the total amount of hypochlorous acid generated can be grasped. The hypochlorous acid concentration of the electrolytically treated water E injected into the water intake channel 1 is divided by the total amount of hypochlorous acid generated by the flow rate Q ₂ of the seawater W injected into the water intake channel 1. It can be calculated as Therefore, according to the total amount of hypochlorous acid, by controlling the second opening / closing control valve 73 to determine the flow rate Q ₂ of the electrolytic treatment water E injected into the water intake channel 1, the electrolytic treatment water ( The hypochlorous acid concentration in E) can be adjusted.

On the other hand, the electrolytic treatment water E for circulating the circulation flow path 81 is introduced into the water intake flow path 61 at the other end of the circulation flow path 81. That is, the electrolytically treated water E which has passed through the circulation flow path 81 joins the seawater W which passes through the water intake flow path 61, and is introduced into the electrolytic cell main body 20 again. At this time, the third open / close control valve 83 is opened and closed in accordance with the flow rate detected by the third flowmeter 82, whereby the flow rate of the electrolytically treated water E joining the seawater W through which the water intake passage 61 flows. Can be adjusted.

In this way, the electrolytically treated water E flowing out of the outlet 25 of the electrolytic cell main body 20 flows in from the inlet port 23 of the electrolytic cell main body 20 by circulating the circulation flow path 81.

According to the said embodiment, the concentrated water C which raised the chloride ion concentration and electrical conductivity is introduce | transduced into the seawater electrolysis apparatus 10. FIG. In addition, since iridium oxide is contained in the coating material of the positive electrode (A), the current density on the surface of the electrode 30 is in the range of 20 A / dm 2 to 60 A / dm 2, preferably 20 A / dm 2 to 50 A / dm 2 can be set, and the concentration of hypochlorous acid contained in the generated electrolytically treated water (E) can be increased. That is, by increasing the generation amount of hypochlorous acid per unit area of the electrode, the electrode area can be reduced, and the device can be miniaturized.

In addition, since the chloride ion concentration of the seawater in the bay and the bay is softer than that of ordinary seawater, and the electrical conductivity is also low, the stability of the operation may be a problem due to abnormal consumption of the electrode. By passing through the seawater electrolysis apparatus 10, since chlorine ion concentration and electrical conductivity can be improved, stabilization of processing performance can be attained.

In addition, since the increased hydrogen gas is degassed by the hydrogen separation device 90, the hydrogen gas does not damage the second pump 72 or the pipe at the rear stage via the storage tank 50.

Moreover, by forming the circulation part 80, scale components, such as manganese, magnesium, calcium, etc. which generate | occur | produced at the time of electrolysis, are introduce | transduced into the electrolytic cell main body 20 with electrolytically treated water E. FIG. Thus, electrolytically-treated water E containing the scale component is introduce | transduced into the electrolytic cell main body 20 again, and the adhesion of the scale to the surface of the electrode 30 can be prevented by the termination effect by the said scale component. That is, since the scale component becomes the seed and the newly generated scale adheres to the seed, precipitation of the scale on the surface of the electrode 30 can be avoided. Thereby, it becomes possible to aim at the improvement of the durability of the electrode 30, and suppression of the fall of the chlorine generation efficiency.

In addition, when the current density on the surface of the electrode 30 is too large, for example, when it exceeds 60 A / dm 2, the amount of scale generated in the positive electrode A and the negative electrode K is effective for the cleaning effect of hydrogen. It exceeds the range. In contrast, in the present embodiment, the upper limit of the current density is set to 60 A / dm 2, so that the cleaning effect is effectively expressed by hydrogen, effectively preventing the adhesion of scales on the positive electrode A and the negative electrode K. FIG. can do. Moreover, when the upper limit of current density is 50 A / dm <2>, the washing effect by hydrogen can be expressed more effectively, and adhesion of a scale can be prevented effectively.

As described above, in the present embodiment, iridium oxide is contained in the coating material of the anode A, and the current density on the surface of the electrode 30 is in the range of 20 A / dm 2 to 60 A / dm 2, preferably Since it is set to 20 A / dm 2 to 50 A / dm 2, the cleaning effect by hydrogen gas can be effectively obtained. Thereby, since adhesion of the scale with respect to the electrode 30 can be prevented, it becomes possible to aim at the improvement of the durability of the electrode 30, and suppression of the fall of the chlorine generation efficiency.

Therefore, the maintenance property of the seawater electrolytic apparatus 10 can be improved, and the number of electrodes 30 can be reduced by high chlorine generation efficiency, and the apparatus can be miniaturized.

In addition, in the said embodiment, although the example which used the bipolar electrode plate 31 as the electrode 30 was demonstrated, for example, the positive electrode plate 32 and the negative electrode plate 33 without using the bipolar electrode plate 31 were demonstrated. May be disposed to face each other, and current may be supplied to the seawater W between these positive electrode plates 32 and the negative electrode plates 33. Moreover, you may arrange | position these positive electrode plates 32 and negative electrode plates 33 alternately, and may carry an electric current through the seawater W between the positive electrode plate 32 and the negative electrode plate 33 which oppose each other next to each other.

Moreover, in the said embodiment, although the positive electrode A is arrange | positioned toward the liquid inlet side and the negative electrode K is toward the liquid outlet side, the positive electrode A has the liquid outlet side. In addition, the cathode K may be disposed toward the liquid inlet side.

Moreover, in this embodiment, although the desalination apparatus 65 which used the RO membrane was employ | adopted as a means which concentrates seawater W and produces | generates the concentrated water C, the means for generating the concentrated water C is limited to this. For example, you may employ | adopt the method of concentrating seawater W using the distillation method.

In addition, as a method of separating hydrogen gas from electrolytically treated water E in which hydrogen gas is mixed, it is not limited to the hydrogen separation apparatus 90 using the spray nozzle 94 as described in this embodiment, and gaseous liquid If the mixed fluid can be separated into a gas and a liquid, for example, a gas-liquid separator using a centrifugal separator or the like may be employed.

Moreover, the gas-liquid separation function which dilutes hydrogen gas is supplied to the storage tank 50, for example, by supplying air to the storage tank 50, for example, the liquid phase of the storage tank 50, without forming the hydrogen separation apparatus 90 as a gas-liquid separation apparatus separately. You may separate hydrogen by doing this.

Moreover, if scale adhesion to the surface of the electrode 30 does not become a problem, all the electrolytic treatment water E may be supplied to the water intake channel 1 without forming the circulation portion 80.

Example

Hereinafter, an embodiment will be described.

(Chlorine generation efficiency measurement test)

When electrolysis of seawater (W) and concentrated water (C), the test which examines the relationship between the current density of the electrode surface and chlorine generation efficiency was performed.

A positive electrode plate and a negative electrode plate having an electrode area of 50 x 50 mm in the form of a plate were prepared, and were disposed to face each other with a gap of 5 mm. The positive electrode plate as is, used was coated with coating material containing at least 50% iridium oxide (IrO ₂₎ in a mass ratio to the titanium substrate. As the negative electrode plate, a titanium substrate not coated with a coating material was used.

The chloride ion concentration of the seawater W was 20,000 mg / L, and the chloride ion concentration of the concentrated water C was 30,000-40,000 mg / L.

These positive electrode plates and negative electrode plates were immersed in seawater (W) and concentrated water (C), and the seawater (W) and concentrated water (C) were passed through at a flow rate of 250 ml / min, and electrolytically passed between the positive and negative plates. Was carried out. And the chlorine generation efficiency in each current density was measured.

In addition, the chlorine generation efficiency means the ratio of the amount of chlorine actually generated with respect to the amount of chlorine which can be theoretically generated based on the current density of the electric current to distribute | circulate.

The measurement result of this chlorine generation efficiency is shown in FIG.

As shown in FIG. 9, when the current density of both seawater W and concentrated water C is less than 20 A / dm 2, the chlorine generation efficiency increases as the current density increases.

In the case of unconcentrated seawater (W), the chlorine generation efficiency becomes constant when the current density is 20 A / dm 2 to 30 A / dm 2, and when the current density exceeds 30 A / dm 2, the chlorine generation efficiency gradually decreases. Going. Moreover, the highest value was obtained for the chlorine efficiency in case of 20A / dm <2> and 30A / dm <2> of current density as 96%.

In addition, when the current density which became technical common sense in the electrode using the coating material containing platinum is 15 A / dm <2>, the chlorine generation efficiency was 93%.

In this regard, also in the case of seawater (W), in the electrode using the coating material containing iridium oxide, by setting the current density in the range of 20 A / dm 2 to 30 A / dm 2, high chlorine generation efficiency I could see what I could get. This is considered to be attributable to the fact that the scale cleaning effect of the positive electrode plate and the negative electrode plate by the hydrogen gas was obtained because the amount of generated hydrogen gas was increased.

Here, the larger the current density, the greater the amount of chlorine that can occur in theory. Therefore, even if the chlorine generation efficiency shows the same value, the larger the current density, the more chlorine is generated.

Therefore, when the current density is 40 A / dm 2, the chlorine generation efficiency is 93%, which is equivalent to the current density of 15 A / dm 2, but the chlorine generation amount is 40 A / dm 2 when the current density is 40 A / dm 2. It becomes large compared with the case where current density is 15 A / dm <2>. Therefore, it can be said that setting the current density to 40 A / dm 2 is effective in view of the amount of chlorine generated. On the other hand, when current density exceeds 40 A / dm <2>, it will exceed the range which the washing | cleaning effect of hydrogen gas acts effectively, and will fall compared with the case where chlorine generation efficiency is 15 A / dm <2>. Therefore, it is preferable that the upper limit of current density shall be 40 A / dm <2>, and by this, it was found that the quantity of chlorine which generate | occur | produces can be ensured, keeping the chlorine generation efficiency high.

In the case of the concentrated water (C), the chlorine generation efficiency is constant when the current density is 20 A / dm 2 to 50 A / dm 2, and the chlorine generation efficiency is 93% even when the current density is 60 A / dm 2. Was keeping it.

In this regard, in the case of concentrated water (C), it can be seen that by setting the current density in the range of 20 A / dm 2 to 60 A / dm 2, high chlorine generation efficiency can be obtained. It was found that the current density can be made higher than that of.

As described above, by introducing the concentrated water C into the seawater electrolytic apparatus 10 by the chlorine generation efficiency measurement test, the current density at the electrode surface during electrolysis is 20 A / dm 2 to 60 A / dm 2, It turned out that high chlorine generation efficiency can be obtained by setting it preferably in the range of 20A / dm <2> -50A / dm <2>.

In addition, since the electrode is gradually consumed when the electrolysis is continued for a long time, the curve in FIG. 9 showing the measurement result is considered to be steeper. Therefore, it can be estimated that it is more effective to set the current density in the above range, especially after the electrode is consumed.

(Electrolytic life test results)

The test which examines the relationship between the current density and the catalyst holding amount at the time of the electrolysis of seawater W was performed.

Similarly to the chlorine generation efficiency measurement test, a positive electrode plate and a negative electrode plate having an electrode area of 50 × 50 mm in the form of a plate were prepared, and were disposed to face each other with a gap of 5 mm. As the positive electrode plate, _{two types of} a coating material containing 50% or more of iridium oxide (IrO ₂ ) by mass ratio were coated on the titanium substrate, and a coating material containing platinum (Pt) on the titanium substrate was used. As the negative electrode plate, a titanium substrate not coated with a coating material was used.

These positive electrode plates and negative electrode plates were respectively immersed in seawater W, flowed through the seawater W at a flow rate of 250 ml / min, and electrolysis was performed by energizing between the positive electrode plate and the negative electrode plate. And the catalyst holding amount in each current density was measured with time.

In addition, the catalyst holding amount means the catalyst amount of the electrode hold | maintained after electrolysis, and when a catalyst holding amount becomes small with time, an electrode will be consumed by that much. The measurement result of this catalyst holding amount is shown in FIG.

As shown in FIG. 10, when a coating material containing platinum is used as the positive electrode plate (Pt / Ti), the catalyst holding amount gradually decreases with time, and in particular, as the current density increases, the decrease of the catalyst holding amount is remarkable. I could see it lost.

On the other hand, when a coating material containing iridium oxide is used as the positive electrode plate (IrO ₂ ), the amount of catalyst retention does not decrease even if time passes.

Thereby, it turned out that the positive electrode plate using the coating material containing iridium oxide has higher durability of an electrode compared with the positive electrode plate using the coating material containing platinum.

Industrial availability

TECHNICAL FIELD This invention relates to the seawater electrolysis system provided with the seawater electrolysis apparatus which produces hypochlorous acid by electrolyzing seawater, and a seawater electrolysis method.

According to the present invention, adhesion of the scale to the electrode can be prevented, thereby improving the durability of the electrode and suppressing the decrease in the chlorine generation efficiency.

A… anode
K ... cathode
M… Electrode group
W ... sea water
C ... Concentrated water
10 ... Seawater electrolysis equipment
20 ... Electrolyzer body
30 ... electrode
31 ... Bipolar electrode plate
32 ... Positive electrode plate
33 ... Cathode plate
40 ... Power unit
60 ... Water intake
65. Desalination unit (concentration means)
70 ... Housewife
80... Circulation
81 ... Circulation euro
90... Hydrogen Separator (Hydrogen Separator)
100A, 100B, 100C... Seawater electrolysis system

Claims (18)

A seawater electrolytic apparatus comprising a positive electrode made of titanium coated with a coating material containing iridium oxide, a negative electrode, an electrolytic cell body for accommodating the positive electrode and the negative electrode, and a power supply unit for supplying electricity to the positive electrode and the negative electrode,
A seawater electrolysis device, wherein the current density of the surface of the anode is between 20 A / dm 2 and 40 A / dm 2, between the anode and the cathode, so as to electrolyze seawater in the electrolytic cell body. The method of claim 1,
A seawater electrolytic apparatus, wherein the current density of the surface of the positive electrode and the negative electrode that is energized by the power supply device is in a range of 20 A / dm 2 or more and 30 A / dm 2 or less. The method of claim 1,
A seawater electrolytic apparatus, wherein an oxide of tantalum is added to the coating material. The method of claim 1,
The electrode includes a plurality of bipolar electrode plates in which one side portion of the seawater flow direction becomes the positive electrode and the other side portion becomes the negative electrode,
A plurality of electrode groups formed by arranging these bipolar electrode plates at intervals in the flow direction are arranged in parallel with each other,
The bipolar electrode plate of the electrode groups adjacent to each other in parallel with each other is disposed so that the positive electrode and the negative electrode face each other. The method of claim 4, wherein
The seawater electrolysis apparatus in which the space | interval of the said bipolar electrode plates adjacent to the said flow direction in each said electrode group is set to 8 times or more of the space | interval of the adjacent electrode groups parallel to each other. The method of claim 1,
A plurality of said electrolyzer body,
A connecting pipe connecting the outlet and the inlet of the sea water in these electrolytic cell bodies,
The seawater electrolysis apparatus further provided with gas removal means which removes the gas in the said connection pipe. The seawater electrolytic apparatus according to any one of claims 1 to 6,
And a circulation flow path for mixing the seawater after electrolysis flowing out of the outlet of the electrolyzer body with the seawater before inflow from the inlet of the electrolyzer body. As a seawater electrolysis method using the seawater electrolysis apparatus of any one of Claims 1-6,
Sea water is introduced into the electrolytic cell body,
A seawater electrolytic method, wherein the current density on the surface of the anode is between 20 A / dm 2 and 40 A / dm 2, between the anode and the cathode, so as to electrolyze seawater in the electrolytic cell body. An anode made of titanium coated with a coating material containing iridium oxide, a cathode, an electrolytic cell body for accommodating the anode and the cathode,
A seawater electrolytic apparatus having a power supply unit configured to supply electricity to the anode and the cathode;
A seawater electrolytic system comprising concentration means for increasing the concentration of chloride ions contained in seawater to be introduced into the electrolytic cell body,
The seawater electrolysis system which energizes between the said anode and the said cathode, and electrolyses the seawater in the said electrolyzer main body. The method of claim 9,
The seawater electrolysis system of which the electric current density of the said positive electrode and the said negative electrode surface which are energized by the said power supply apparatus is contained in the range of 20 A / dm <2> or more and 60 A / dm <2> or less. The method of claim 9,
The seawater electrolysis system of which the current density of the surface of the said positive electrode and said negative electrode which are energized by the said power supply device is contained in the range of 20 A / dm <2> or more and 50 A / dm <2> or less. The method of claim 9,
And a hydrogen separation means for separating the hydrogen gas generated at the cathode from the seawater after the electrolysis. The method of claim 9,
And a circulation flow path for mixing the seawater after electrolysis discharged from the electrolyzer body with seawater to be introduced into the electrolyzer body. The method of claim 9,
A seawater electrolytic system in which an oxide of tantalum is added to the coating material. The method of claim 9,
The electrode includes a plurality of bipolar electrode plates in which one side portion of the seawater flow direction becomes the positive electrode and the other side portion becomes the negative electrode,
A plurality of electrode groups formed by arranging these bipolar electrode plates at intervals in the flow direction are arranged in parallel with each other,
The bipolar electrode plate of the electrode groups adjacent to each other in parallel with each other is disposed so that the positive electrode and the negative electrode face each other. The method of claim 15,
A seawater electrolytic system, wherein the distance between the bipolar electrode plates adjacent to each other in the flow direction in each of the electrode groups is set to at least eight times the distance between the electrode groups adjacent to each other in parallel. As a seawater electrolysis method using the seawater electrolysis apparatus according to any one of claims 9 to 16,
Increase the concentration of chloride ions in the seawater to be electrolyzed,
Seawater having a high chloride ion concentration is introduced into the electrolytic cell body,
The seawater electrolysis method which energizes between the said anode and the said cathode, and electrolyzes the seawater in the said electrolytic cell main body. The method of claim 18,
The seawater electrolytic method of which the current density of the surface of the said positive electrode and said negative electrode which are energized by the said power supply apparatus is contained in the range of 20 A / dm <2> or more and 60 A / dm <2> or less.

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