JP2013189699A - Apparatus for electrolysis of water - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an apparatus for electrolysis of water of which the size and the weight are reduced, wherein a high production function, a temperature control function, and a freezing prevention function are provided.SOLUTION: In generation of hydrogen and oxygen gas, improvement in generation efficiency and electric power efficiency can be achieved even under relatively low temperature conditions by using a laminated structure as an electrode for electrolysis. Thus, the size and the weight of an apparatus for electrolysis of water can be achieved. Wherein, a graphite plate is used as a substrate for the electrode. With respect to both surfaces thereof, a graphene layer is formed on the surface which is to be used as an anode, and a hydrogen storage metal layer or an alloy layer thereof with low oxygen and hydrogen overvoltage is formed on the surface which is to be used as an cathode, respectively. Thus the laminated structure is obtained. Also, temperature control and antifreeze can be achieved by providing an electrothermal mechanism using a corrosive-resistant electric heating material or a waterproofing electric heating material as a heat generation source in an electrolysis tank comprising a low concentration hydroxide-contaminated aqueous solution or purified and concentrated tap water, and by controlling external electric power which is applied to the electrothermal mechanism.

Description

  The present invention relates to a water electrolysis apparatus that generates hydrogen and oxygen gas, and more particularly to a water electrolysis apparatus that is reduced in size and weight and is provided with a high production function, a temperature control function, and an antifreezing function.

  The water electrolysis apparatus that generates hydrogen and oxygen and the method for generating the same are industrially mature technologies. In addition, various methods have already been proposed for water electrolyzers that have been miniaturized for use in various fields, and research and development for practical use has been made.

  The performance of the water electrolyzer is greatly influenced by the material and characteristics of the electrode for electrolysis to be used because the electrolysis itself is an oxidation-reduction reaction. Further, from the viewpoint of power efficiency, a material having low oxygen and hydrogen overvoltage is required, and nickel (Ni) is ideal for the anode and platinum (Pt) is ideal for the cathode. However, in practical use, titanium (Ti) and iron (Fe) genus alloys (for example, stainless steel containing nickel (Ni) and chromium (Cr)) are generally used. On the other hand, development of an electrode with high electrode reaction efficiency is also progressing with the reduction in size and weight of the water electrolysis apparatus.

  In an ordinary water electrolysis apparatus, an aqueous solution of sodium hydroxide (NaOH) having a concentration of 18 to 20% by weight or an aqueous solution of potassium hydroxide (KOH) of 25 to 30% is used industrially. The sodium hydroxide (NaOH) aqueous solution operates at a temperature of 50 to 70 degrees, and the potassium hydroxide (KOH) aqueous solution operates at a temperature range of 70 to 90 degrees. In this case, generally, as a method of maintaining the temperature in the electrolytic cell in a stable thermal equilibrium state, electric power applied to the electrode for electrolysis from the outside is controlled. On the other hand, for miniaturized water electrolyzers, for safety reasons, low concentration of the above chemical substances and operation at a relatively low temperature have been emphasized, and studies have been made on the temperature inside the electrolytic cell. The same control method is taken.

When considering the application of the water electrolyzer in various fields, it is necessary to consider the problem of freezing of the aqueous solution in the tank when used in cold regions in winter. For this reason, it is requested | required that aqueous solution, such as a battery mounted in the motor vehicle etc., should not freeze to -20 degree | times as a specification in a cold region. In order to solve the above problems, the chemical substance sodium borohydride (NaBH ₄ ) is mixed with the electrolytic aqueous solution as an antifreezing agent by not affecting the hydrogen and oxygen gas generation characteristics in the water electrolysis tank. Has been shown to be effective. Sodium borohydride (NaBH ₄ ) is stable in a 10-20% sodium hydroxide (NaOH) aqueous solution, and by mixing 70-260 g / L, the coagulation temperature is kept at −20 ° C. or less. Yes. (See Patent Documents 1 and 2)

  In addition, although an electric heating material or an electric heating element is also used, various electric heating wires that can be controlled by a thermostat, and antifreezing materials processed into a sheet shape have been put into practical use. These electrothermal materials are a method of preventing the freezing by transferring heat from the outside by winding or covering the outside of the electrolytic cell and inputting electric power to generate heat. The thermostat as a control device used here has a function of turning on the supplied power at a temperature of 3 degrees and turning it off at 10 degrees.

JP 2003-146618 A JP 2005-520759 A

  However, it is difficult to use a conventional electrolytic electrode to improve the generation efficiency and power efficiency of the water electrolyzer and to reduce the size and weight. In order to solve the above problems, it is particularly desired to use a material having low oxygen and hydrogen overvoltage, light weight, high electric conductivity, and excellent electrolytic reaction efficiency. In addition, the conventional method for controlling the operating temperature and the method for preventing the electrolytic solution from freezing may cause problems and dangers in the use and application of the water electrolysis apparatus in various fields. In fact, when a water electrolysis device is mounted on a truck or the like, it is necessary to quickly bring the temperature inside the electrolytic cell into a thermal equilibrium state and maintain a stable operating state at that temperature. Since the temperature of the inside gradually rises, it takes a considerable time to realize stable operation.

  In particular, when the concentration of the electrolyte in the aqueous solution is as small as 1% or less, the electrical conductivity of the aqueous solution is considerably reduced. Therefore, even if the interval between the electrodes for electrolysis is narrowed to 5 mm or less, the required generation of hydrogen and oxygen gas In order to obtain the amount, it is necessary to apply a certain amount of electric power, and accordingly, the temperature in the electrolytic cell rises considerably due to generation of Joule heat in the aqueous solution. Therefore, if the heat generation temperature due to power loss or the like is 80 ° C. or higher, the generation of water vapor in the electrolytic cell begins to occur, which is not preferable because it involves danger in use.

  On the other hand, in order to prevent freezing of the aqueous solution in the electrolytic cell, a dangerous chemical substance must be used in a relatively large amount. In general, various types of heating wires and sheet-shaped heating materials are used for anti-freezing, but they must be wrapped around or covered with the outside of the electrolytic cell. When mounted or used in an external environment other than indoors, it may be damaged or corroded by exposure to wind and rain, and may lead to a serious accident due to leakage.

  The present invention has been made to solve the problems in the prior art, and improves the generation efficiency and power efficiency of the water electrolysis apparatus, resulting in smaller and lighter weight, and stability by achieving the electrolysis temperature in a short time. The purpose is to provide a new method in order to realize efficient operation and prevention of freezing of the electrolytic aqueous solution.

  The present invention provides efficient and stable generation of hydrogen and oxygen gas by using an electrode for electrolysis with good electrolytic reaction efficiency, early achievement of stable operating temperature by an electric heating mechanism provided with an electrothermal material as a heat source in an electrolytic cell, and an aqueous solution It was made based on the knowledge from the experimental results on the freeze prevention of sewage.

  Therefore, in order to achieve the above-described object, the present invention improves the generation efficiency of hydrogen and oxygen gas by using an electrode material having good electrolytic reaction efficiency, and also provides an electric heating mechanism using an electric heating material inside the electrolytic cell. Thus, the electrolysis temperature is raised to a short time to achieve stable operation of the water electrolysis apparatus, and the electrolytic solution is prevented from freezing in cold weather.

  Hereinafter, the problem solving means will be described in order.

  The first solution in the present invention is that the electrode for electrolysis is made of a lightweight substance having a low hydrogen and oxygen overvoltage, good electrolysis reaction efficiency even at a relatively low temperature, and hydrogen and oxygen gas of the water electrolysis apparatus. It is to provide a method for improving the generation efficiency. As a result, it is possible to achieve power saving and reduction in size and weight of the water electrolysis apparatus.

  The theoretical decomposition voltage required for electrolysis of water to generate 1 volume of oxygen for 2 volumes of hydrogen is about 1.23 V at 25 degrees, but in reality, the overvoltage at the electrode and the Joule heat in the aqueous solution Energy loss such as generation must be considered. Since electrolysis of water is an oxidation-reduction electrode reaction, the material and performance of the electrode used are very important factors in the selection. From the viewpoint of power utilization efficiency, a material with a low oxygen overvoltage of 0.3 V is required for the anode, and a material with a hydrogen overvoltage of 0.1 to 0.2 V is required for the cathode.

  As the anode material satisfying the above requirements, platinum, nickel (Ni), iron (Fe) group alloys, titanium (Ti) and graphite correspond to this, but from the viewpoint of cost, iron (Fe). Group alloys, titanium (Ti) and graphite are preferable, and graphite is most preferable from the viewpoint of miniaturization and weight reduction of the water electrolysis apparatus. Further, as the cathode material, there are platinum, nickel (Ni), molybdenum (Mo), iron (Fe), graphite and the like, but preferably an alloy of nickel (Ni), iron (Fe), molybdenum (Mo) Graphite is good. However, from the viewpoint of durability in an aqueous solution and reduction in size and weight, it is most preferable to use graphite, which is also a lightweight material.

  Graphite is a porous material. It is a hexagonal and hexagonal plate-like crystal elemental mineral composed of carbon. Its structure is a turtle-like layered material, and the layers are connected by strong covalent bonds, but the layers are weak. They are connected by van der Waals forces. The graphite crystal has a strongly anisotropic layered structure with an in-plane distance between carbon atoms of 0.142 nm and a distance between layer planes of 0.335 nm. It is a porous body that exhibits a so-called intercalation effect. Therefore, porous graphite also has a high adsorption and storage capability for hydrogen. This high adsorption and storage capacity for hydrogen greatly affects the generation efficiency of hydrogen and oxygen gas.

In the electrolysis of water, since the electrolytic reaction is dominant over the occlusion of hydrogen, hydrogen ions (H ⁺ ) adsorbed on the cathode side are generated as hydrogen gas by discharge. Therefore, using a highly reactive hydrogen storage material as an electrode for electrolysis can be an effective means for improving the production efficiency of hydrogen and oxygen gas.

Therefore, it is known that graphite as an electrode material tends to have a higher generation amount of hydrogen and oxygen gas per unit power than the other electrode materials due to high reactivity at the electrode. In particular, a structure in which a sheet-like graphene layer is formed on the surface of graphite has excellent characteristics of hydrogen adsorption and storage. Therefore, when used as an electrode for electrolysis, hydrogen and oxygen gas per unit power High efficiency in the generation of can be expected. Graphene is a sheet of sp ² bonded carbon atoms with a thickness of 1 atom, but has a hexagonal lattice structure like graphite.

  Graphite itself is formed by stacking a large number of graphene sheets, but when processing into an electrode, a surface layer is a complex layer having many defects rather than a graphene layer. Therefore, when used as an electrolytic electrode, it is most preferable to treat the double-sided processed layer of graphite flatly by polishing, etching or the like, and to stack graphene on both sides to a thickness of several μm. Therefore, it is possible to form a fairly stable surface by using graphite as an electrode substrate and laminating a graphene layer on the surface thereof. As a formation method for forming the graphene layers on both surfaces of the graphite, there are a vacuum deposition method, a sputtering method, a CVD method, and the like, and a graphene layer with few defects can be formed by these vapor phase growth methods.

  In addition, the electrode for electrolysis in which the hydrogen storage metal layer and the hydrogen storage alloy layer having a low hydrogen overvoltage are formed on both surfaces of the graphite, not the graphene layer, in the generation of hydrogen and oxygen gas per unit power. High efficiency can be greatly expected. Even in this case, it can be formed by the vapor phase growth method. Note that the layer-forming material on both surfaces of the graphite is not limited to the materials described above as long as it is a hydrogen storage material with low oxygen and hydrogen overvoltage. Of course, the hydrogen storage material layer having a low oxygen overvoltage is used as an anode, and the hydrogen storage material layer having a low hydrogen overvoltage is used as a cathode.

  In addition, the graphene layer, the hydrogen storage metal layer or its alloy layer may be formed only on one side of the graphite plate. In this case, the formation surface of the hydrogen storage material layer is used as a cathode and the other graphite surface is used as an anode. , Or vice versa, and in any case, the electrode reaction efficiency is not particularly affected. For example, when a metal layer such as nickel (Ni), titanium (Ti), molybdenum (Mo) or iron (Fe) or an alloy layer thereof having a lower hydrogen overvoltage than graphite is formed on the cathode surface and used as an electrolytic electrode, The production efficiency is significantly improved due to the high electrode reaction characteristics. However, although graphite itself is insoluble, there is no problem. However, in order to increase the corrosion resistance of the cathode material, it is necessary to form an extremely thin stable film on the surface of the forming layer, and chromium (Cr) having excellent corrosion resistance is 10 to 10. It is necessary to mix about 20%. The contained chromium (Cr) is a metal that combines with oxygen to form a stabilized ultrathin film of about 5 nm on the surface. Stainless steel used as an electrolytic electrode also contains 10 to 20% of chromium (Cr), so that it does not particularly affect the generation efficiency by electrolysis.

The hydrogen storage material is composed of a material having a hydrogen storage property and a hydrogen release property, but most of the iron (Fe) group is a material having a hydrogen release property. Therefore, when a metal layer such as nickel (Ni) or iron (Fe) or an alloy layer thereof is used as a cathode, hydrogen ions (H ⁺ ) adsorbed on the cathode are quickly released as hydrogen gas by discharge.

  The second solving means in the present invention is that an electrothermal mechanism using an electrothermal material is provided in the electrolytic cell, and the temperature in the electrolytic cell is raised to a stable operating temperature that is in a thermal equilibrium state in a short time, so that the water electrolysis apparatus can be operated quickly and stably. It is to provide a method of realizing.

  There are two types of electrode arrangement for electrolysis: series (bipolar) and parallel (single). In the parallel type, a large number of electrodes are connected in parallel, but the current capacity per pole is large, and the voltage requires about 1.9 to 2.6V. On the other hand, in the case of the series type, the electrodes are alternately insulated and assembled, and the voltage is increased by the number of intermediate electrodes. Needless to say, the solution in the present invention can be applied to either type of water electrolysis apparatus.

  When the operation is started by supplying electric power to the water electrolysis apparatus from the outside, the initial temperature is room temperature, but the temperature rises gently with time. At this time, as the temperature rises, the voltage and current fluctuate and become unstable, so the production amount of hydrogen and oxygen gas itself also fluctuates, and a stable production amount cannot be obtained until the temperature in the tank reaches a thermal equilibrium state.

  The above problem can be solved by providing an electric heating mechanism with an electric heating material in the electrolytic cell, and adding external electric power to the electrolytic cell and controlling it. The electric heating mechanism provided in the electrolytic cell makes it possible to effectively control the temperature in the electrolytic cell. In the heating method using an electrothermal material attached to the outside of the electrolytic cell, it is heated from the outside by the applied power, so it takes time not only to transfer the heat to the inside of the electrolytic cell, but also the amount of power consumed. Don't be foolish However, the electric heating material built-in type in the present invention is most preferable because it directly transfers heat to the aqueous solution in the electrolytic cell, so that it takes a very short time to raise to the target temperature, and it is economical because it consumes less power. Is the method. Needless to say, after the target temperature is reached, the water electrolysis apparatus can be stably operated by controlling the power applied to the electrothermal material to stop.

  Since the electrothermal material to be used is installed in the electrolytic cell, it is preferable to use a corrosion-resistant material or a waterproof material, and it is most preferable that these materials have a low power specification. Moreover, the electric heating material to be used may be a material processed into a linear shape, a mesh shape or a sheet shape, and the arrangement in the electrolytic cell is between the bottom surface region, the tank wall region, the electrode built-in cell outer wall and the electrolytic cell inner wall. However, it is most preferable that the electrothermal material is placed on the outer wall of the electrode-embedded cell. By this installation method, the electrolytic aqueous solution in the cell with a built-in electrode can be heated through the outer wall of the cell, and the electrolytic aqueous solution between the outer wall of the cell and the inner wall of the tank can be heated at the same time. Moreover, it can be heated quickly.

  The third solving means in the present invention can be said to be a consequence of the second solving means, but is a water in which an electrothermal mechanism using an electrothermal material is provided in the electrolytic cell, and electric power is controlled from an external power source to prevent the aqueous electrolytic solution from freezing. It is to provide a method for realizing an electrolysis apparatus.

  When water electrolyzers are used in cold regions in winter, freezing of the aqueous electrolytic solution is a major problem, but using an electrothermal mechanism with an electrothermal material provided in the electrolytic cell is the most effective method for preventing freezing. It is.

  As a recent trend, downsizing of the apparatus itself is being promoted in order to enable application of the water electrolysis apparatus to various fields. With the miniaturization of the apparatus, the distance between the electrodes in the electrolytic cell is also reduced to 1 to 5 mm. In addition, the amount of sodium hydroxide (NaOH) or potassium hydroxide (KOH) in the aqueous solution tends to decrease as the distance between the electrodes decreases, and the concentration is 0.1 to 1.0%.

  On the other hand, although it is a special case, the use of tap water from which substances such as chlorine have been removed as a disturbance factor that hinders water electrolysis by passing a water purifier or an ion exchange resin is also being studied. Such a tendency is very preferable because the handling of chemical substances as dangerous substances is reduced. Although tap water contains trace amounts of calcium (Ca), sodium (Na), potassium (K), etc., these substances contribute to electrolysis. Therefore, if purified tap water can be concentrated at a low cost by an appropriate method, it is expected to contribute to electrolysis more effectively, and it is no longer necessary to use chemical substances such as hydroxides that are dangerous to handle. preferable.

The use of chemical substances such as sodium borohydride (NaBH ₄ ) has already been studied as an antifreezing agent for aqueous solution in the electrolytic cell, but a large amount of contamination is required to maintain the solidification temperature below -20 ° C. Therefore, it is contrary to the tendency to use an aqueous solution or a purified tap water with a reduced amount of chemical substances, and it is not a preferable method because it involves danger in handling.

  Moreover, as antifreezing materials such as tap water, linear or sheet-shaped electric heating materials that can be controlled by a thermostat are generally used. Freezing can be prevented by surrounding such an electrothermal material around the outside of the electrolytic layer. However, as described above, when mounted on a truck or the like, there is a risk of damage or corrosion due to exposure to wind and rain. In addition, there is a possibility that serious problems such as electric leakage may occur.

  The purpose of antifreezing itself is to prevent structural changes inside the electrolytic cell, changes in the characteristics of the electrolytic aqueous solution, and changes in the electrolytic reaction by preventing the electrolytic aqueous solution from freezing. Therefore, the heat generated by providing an electric heating material inside the electrolytic cell and applying electric power from the outside is more effective because it is directly transmitted to the aqueous electrolytic solution, and the electric power consumed by it can be reduced.

  The above problem can be solved by using the electric heating material provided in the already described electrolytic cell as it is for preventing freezing. Moreover, temperature control for preventing freezing may be performed using a thermostat, or may be performed using another control device. However, as the antifreezing temperature of the electrolytic aqueous solution is around 6 degrees, it is sufficient to control it with a separate power source from the viewpoint of power efficiency rather than controlling with a thermostat.

  The specifications of the electric heating material to be used and the arrangement in the electrolytic cell have already been described. Thereby, the same effect as the case of the second solution can be obtained. Moreover, although there are various types of electrothermal materials, it does not greatly affect the reduction in size and weight of the water electrolysis apparatus.

  As described above, the present invention uses an electrode for electrolysis that enables efficient production, and provides an electrothermal material for heating an aqueous solution inside the electrolytic layer, and controls the external power applied to them. Thus, a water electrolysis apparatus capable of improving the production efficiency of hydrogen and oxygen gas through stable operation and preventing the electrolytic aqueous solution from freezing is provided.

  According to the present invention, a graphite plate is used as an electrode substrate, and a graphene layer, a hydrogen storage metal layer having a low oxygen overvoltage or an alloy layer thereof is formed on a surface used as an anode, and a surface used as a cathode. By forming a graphene layer, a hydrogen storage metal layer with a low hydrogen overvoltage, or an alloy layer thereof, the generation efficiency of hydrogen and oxygen gas can be improved, and the power efficiency can be improved. The high generation efficiency and high power efficiency can be selected according to the purpose of use of the electrode area for electrolysis, and since a lightweight graphite plate is used as the electrode substrate, the water electrolysis apparatus can be reduced in size and weight. Can be achieved at the same time.

  In addition, according to the present invention, there is a function of preventing generation of hydrogen and oxygen gas by stable operation and freezing by providing an electric heating mechanism with an electric heating material inside the electrolytic layer and controlling external electric power applied thereto. By providing a water electrolyzer that can be used, it is possible not only to avoid the use of dangerous anti-freeze chemicals, but also to cause serious problems such as damage and corrosion due to exposure to wind and rain, and the associated leakage Can also be avoided. In addition, even if an electrothermal mechanism using an electrothermal material is provided inside the electrolytic layer, the water electrolysis apparatus can be sufficiently reduced in size and weight, so that it can be applied to various fields by using the functions described above. .

  It is a perspective view which shows the structure of the electrode for electrolysis.   It is the contrast graph which shows the temperature rise by the passage of time, and the equilibrium temperature state when not using the electrothermal mechanism in the operation of the water electrolysis apparatus and when using it

  Hereinafter, the aspect is demonstrated regarding the method of improving the production | generation efficiency of the water electrolyzer based on embodiment of this invention, the method of implement | achieving the stable operation at electrolysis temperature, and the method of preventing freezing of aqueous electrolytic solution.

  First, a method for increasing the generation efficiency and power efficiency of hydrogen and oxygen gas by using the electrode for electrolysis with high electrolytic reaction efficiency according to the first embodiment of the present invention will be described below.

  FIG. 1 is a perspective view showing the structure of an electrode for electrolysis used for carrying out the present invention. A laminated structure in which graphene layers 12 and 13 are formed on both surfaces of a graphite plate 11 by a plasma CVD apparatus after providing a terminal hole for attaching a power supply terminal to a graphite plate as a base material, polishing and etching 1 shows an electrode 1 for electrolysis.

The electrode 1 for electrolysis has an area of 30 × 20 cm ² and a thickness of 0.8 mm. The electrode 1 for electrolysis is incorporated into two electrolysis cells as a set of three, but since four cells are incorporated in the electrolysis tank, the number of electrolysis electrode plates 1 is twelve. This is a configuration in which eight electrodes for a motor are connected in series. The interelectrode distance is 5 mm.

In the water electrolysis apparatus used in the experiment, an electrolytic cell box (34 × 18 × 26 cm ² ) is assembled from stainless steel, and the upper lid is formed from a thick plastic. As for the electrolytic cell case, it is preferable to use a reinforced plastic material similar to the battery mounted on the automobile from the viewpoint of weight reduction. In addition, the upper lid is provided with a power supply terminal for the electrolytic electrode, a power supply terminal for the electric heating material, a temperature measurement terminal, a pressure valve, and a hydrogen and oxygen gas outlet. The electrolytic aqueous solution is obtained by adding 0.7% by weight of sodium hydroxide (NaOH) to distilled water (9.5 l).

  The electric system is composed of a power supply and a control system. The power supply employs a chopper method with a voltage of 24V and a current of 50A as output rated values, an ON / OFF cycle of 25 msec and 40 Hz, an ON state of 70%, and an OFF state of 30%. The control system includes a supply current control and a temperature control circuit.

  A hydrogen and oxygen gas generation experiment was conducted with the water electrolysis apparatus having the above-described configuration. The generated amount per unit power calculated from the generated amount per minute under the condition that the temperature in the electrolytic cell was 60 degrees. Was about 5.2 cc / W, and about 4.8 cc / W was obtained under the condition of 50 degrees. The above experimental results can be sufficiently tolerated in various applications of the water electrolysis apparatus. In fact, in the fuel economy test of trucks equipped with a diesel engine, an improvement in fuel efficiency of more than 27% has been obtained, and this test result shows that the water electrolysis apparatus can be applied to many areas. ing.

  The results shown above are due to the improvement in the efficiency of the electrolytic reaction of the electrode for electrolysis as a laminated structure in which a graphene layer is formed on both surfaces of a graphite plate as an electrode substrate. It was confirmed that the electrode for electrolysis greatly contributes to improvement of generation efficiency and power efficiency.

  On the other hand, a graphite plate is used as an electrode substrate, a graphene layer is formed on the anode side, and an iron (Fe) -nickel (Ni) -titanium (Ti) alloy layer is formed on the cathode side. The experiment was conducted under the same conditions as above, but the production efficiency exceeded the above results.

  Based on the above results, a graphite plate is used as an electrode substrate, and a graphene layer, which is a hydrogen storage material layer, a hydrogen storage metal layer with a low oxygen overvoltage, or an alloy layer thereof is formed on the surface to be used as an anode, and is also used as a cathode. By forming a graphene layer, a hydrogen storage metal layer with a low hydrogen overvoltage, or an alloy layer thereof on the surface to be produced, the generation efficiency of hydrogen and oxygen gas was improved, and the power efficiency was also improved. Moreover, from the above results, the area of the electrode for electrolysis can be selected according to the purpose of use, and since a lightweight graphite plate is used as the electrode substrate, the water electrolysis apparatus can also be reduced in size and weight.

  By providing an electrothermal mechanism using an electrothermal material for heating in the electrolytic cell according to the second embodiment of the present invention, a method for realizing a stable operation in an electrolysis temperature of the water electrolysis apparatus in a short time and freezing of the aqueous electrolytic solution A method for preventing this will be described below.

  The electrothermal material according to the present invention includes various materials such as nichrome, tantalum, and graphite. The electrothermal material used in the experiment is a nichrome wire processed into a sheet shape. The sheet-shaped electric heating material is formed in a zigzag meandering shape of linear nichrome wire, and is a thin foldable flat sheet with excellent insulation, heat resistance, and corrosion resistance, sandwiched from both sides, corrosion resistance, heat resistance The structure is formed by bonding with an adhesive or welding with heat. Both ends of the linear electric heating material are provided with terminals for coupling with external electrodes. This terminal can be used to input power from the outside.

  The sheet-like electrothermal material is installed in a state where it is wound around the outer wall of the electrolysis cell in the electrolyzer and attached so as not to be displaced. The terminal of the sheet-like electrothermal material is connected to a terminal provided on the upper part of the electrolytic cell and an electric wire covered with a corrosion-resistant film. At this time, the junction between the heating wire terminal and the electric wire is welded to prevent the occurrence of sparks or the like. Moreover, the electrode provided in the upper part of the electrolytic cell is connected with the power supply device. At this time, the power supply incorporates a control device capable of controlling the temperature, thereby sensing the signal from the temperature sensor and controlling the power supply. The power source is designed to have a structure in which the electric power applied to the sheet-like electrothermal material and the electrode for electrolysis is independent and control is performed independently.

  FIG. 2 is a graph showing a temperature rise and an equilibrium temperature state when the water electrolysis apparatus is operated. The horizontal axis indicates the operating time, and the vertical axis indicates the temperature in the electrolytic cell. A temperature curve a shows a graph of a temperature rise and a thermal equilibrium temperature state due to normal operation in which external power is applied only to the electrode for electrolysis, and a temperature curve b shows the sheet-like electrothermal material simultaneously with the electrode for electrolysis. The graph also shows the temperature rise and thermal equilibrium temperature state due to operation with external power applied.

  As is apparent from the graph, in normal operation in which power is supplied from the outside to only the electrode for electrolysis, the temperature rises slowly, and it takes a considerable time to reach a certain temperature that is the thermal equilibrium temperature. In addition, during operation in which electric power is applied to the sheet-like electrothermal material simultaneously with the electrode for electrolysis, the temperature rises rapidly, and the time required to reach a certain temperature that is the equilibrium temperature is considerably shortened. At this time, the electric power applied from the outside to the sheet-like electrothermal material is controlled so that the power supply is automatically turned off and the power supply is interrupted when the temperature inside the electrolytic cell exceeds 45 degrees. Thereafter, by supplying power only to the electrolytic electrode and controlling the power, the water electrolysis apparatus can be stably operated.

  As described above, the water electrolysis apparatus according to the present invention is provided with an electrothermal mechanism using an electrothermal material in an electrolytic cell, to which electric power is simultaneously applied from an external power source to the electrode for electrolysis, and the temperature in the electrolytic cell is rapidly increased. By making the temperature a constant temperature, which is the thermal equilibrium temperature, it is possible to stably obtain the target amount of hydrogen oxygen gas produced.

  Further, in the practice of the present invention, an experiment was conducted using a water electrolysis apparatus similar to the above, using purified and concentrated tap water as an aqueous solution for electrolysis without using hydroxide as an aqueous electrolyte. . As a result, it was possible to obtain the same temperature characteristics as when the hydroxide was used as the aqueous electrolyte, and at the same time, to stably obtain the generation amounts of hydrogen and oxygen gas. Therefore, according to the present invention, water and electricity that can be sufficiently stably operated by using the safest concentrated purified tap water without using chemical substances such as hydroxides that are dangerous to handle as an electrolyte. A disassembly device can be provided.

  On the other hand, in carrying out the present invention, an experiment for confirming prevention of freezing of the electrolytic aqueous solution was also conducted. This experiment was carried out in an atmosphere where the water electrolysis apparatus was installed in a freezing room of −30 degrees or less and shut off from the outside. In order to prevent the aqueous solution from freezing, the electric power applied was set so that the temperature in the electrolytic cell was ON at 2 degrees, OFF at 6 degrees, or a constant temperature at 6 degrees. As a result, freezing of the aqueous electrolytic solution did not occur even in a long experiment. In addition, after the experiment, hydrogen and oxygen gas production experiments were performed with the water electrolysis apparatus, but no change occurred in the operation characteristics such as production efficiency.

  As described above, the water electrolysis apparatus according to the present invention includes an electrothermal mechanism using an electrothermal material in an electrolytic cell, senses the temperature in the electrolytic cell with a temperature sensor, and controls the power supplied thereby, It was possible to prevent freezing. As a result, it is possible to prevent damage or corrosion due to exposure to wind and rain, because it does not use freeze-preventing chemical substances that are dangerous to handle and does not prevent freezing by surrounding the electrothermal material outside the electrolytic layer. There is no fear, and there is no danger of serious problems such as leakage. In addition, since it is not necessary to use a thermostat for the control of power from the power source, power consumption can be reduced.

1: Electrode for electrolysis 11: Graphite plate 12: Deposited graphene layer 13: Deposited graphene layer 14: Terminal hole for attaching a power supply terminal a: Temperature rise curve when no heating material is used b: Using heating material Temperature rise curve when

Claims (2)

  In order to improve the generation efficiency and power efficiency of hydrogen and oxygen gas, a lightweight graphite plate is used as an electrode substrate, and on both sides, graphene is a hydrogen storage material layer on the surfaces used as an anode and a cathode, respectively. Water electrolysis apparatus characterized in that a layered structure formed by forming a layer, a hydrogen storage metal layer having a low oxygen and hydrogen overvoltage or an alloy layer thereof is used as an electrode for electrolysis.   Heat generation in the electrolytic cell consisting of low-concentration hydroxide mixed aqueous solution or concentrated purified tap water to achieve the electrolytic reaction temperature in a short time from the start of operation and to prevent freezing of the aqueous solution in the electrolytic cell 2. The water electrolysis apparatus according to claim 1, wherein an electrothermal mechanism is provided as a source by a corrosion-resistant electrothermal material or a waterproof electrothermal material.

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