JP6142281B2 - Hydrogen generating device, hydrogen generating unit and energy system using them - Google Patents

Description

  The present invention relates to a hydrogen generation device, a hydrogen generation unit, and an energy system using them, which obtain hydrogen by decomposing water into hydrogen and oxygen using light.

  Conventionally, as a method of using a semiconductor material that functions as a photocatalyst, it is known to generate water or generate electrical energy by decomposing water by irradiating the semiconductor material with light (for example, Patent Documents). 1).

  Patent Document 1 discloses a photowater electrolysis device having a function of converting light energy obtained from sunlight into hydrogen energy. This photowater electrolysis apparatus is composed of a plurality of layered photowater electrolysis cells.

  Each photowater electrolysis cell has a box-shaped casing whose outer peripheral portion is surrounded by an outer wall made of a transparent glass plate or synthetic resin plate, and is inclined at an arbitrary angle from the horizontal state. An electrolytic solution is accommodated in the lower part of the photowater electrolysis cell, and a partition that divides the photowater electrolysis cell into two spaces is provided at the center in the thickness direction. This partition wall is formed by integrally joining a gas separation membrane disposed on the upper side and a photowater electrolysis electrode membrane assembly disposed on the lower side, and serves to separate generated hydrogen and generated oxygen. Fulfill.

  A photocatalyst electrode and a platinum counter electrode are respectively formed on both sides of a Nafion membrane, which is an ion conductive membrane, disposed in the central portion in the thickness direction in the photowater electrolysis electrode membrane assembly. In this photowater electrolysis electrode membrane assembly, photowater electrolysis is caused by irradiation with sunlight, and oxygen is produced from the photocatalyst electrode and hydrogen is produced from the platinum counter electrode. In addition, a rectangular through hole is formed at the lower end of the partition wall, and the electrolytic solution can flow through the photowater electrolysis cell through the through hole.

  A flow hole having a rectangular shape in plan view is formed on the outer wall of the photowater electrolysis cell, and a movable wall is provided that allows the opening area of the flow hole to be varied. The movable wall is configured to be slidable along the height direction (longitudinal direction) of the outer wall. When the movable wall moves upward, the opening area of the opening portion decreases, and when the movable wall moves downward, the opening area increases. Here, the upper end of the photoelectrolytic electrode membrane assembly and the upper end of the movable wall are disposed at substantially the same height.

  Moreover, the leg of the perpendicular dropped from the upper end of the photowater electrolysis electrode membrane assembly toward the outer wall of the photowater electrolysis cell coincides with the lower end position of the flow hole. For this reason, the liquid level height of the electrolytic solution in the photowater electrolysis cell substantially coincides with the heights of the upper end of the photowater electrolysis electrode membrane assembly and the upper end of the movable wall. And since a flow hole is provided in the outer wall of the photowater electrolysis cell and the electrolyte solution can be circulated between the adjacent photowater electrolysis cells via the flow hole, each photowater electrolysis cell is separated from the flow of the electrolyte solution. It is connected in series so that the electrolyte solution can be supplied and discharged in all the photowater electrolysis cells.

JP 2008-75097 A

  However, in the case of such a photowater electrolysis device, when a problem occurs in some photowater electrolysis cells constituting the photowater electrolysis device for some reason, the other photowater electrolysis cells are connected in series. Discontinuation of the flow path makes it impossible for the entire flow path to circulate, and the influence spreads over the entire photowater electrolysis apparatus.

  In order to solve the conventional problems, a hydrogen generation device according to the present invention includes a housing including a light-transmitting surface, a separator that divides a space inside the housing into a first space and a second space. , A counter electrode disposed in the first space, an optical semiconductor electrode disposed in the second space and formed on the conductive substrate, and an electrical connection portion connecting the optical semiconductor electrode and the counter electrode And an electrolyte containing water in the first space and the second space, an electrolyte supply hole that penetrates the casing that supplies the electrolyte, a casing that contacts the first space, and The hydrogen side gas / liquid discharge hole installed at a position lower than the electrolyte solution supply hole and the oxygen side gas installed at a position lower than the electrolyte solution supply hole through the casing in contact with the second space. A plurality of hydrogen generation cells having liquid discharge holes are provided. Furthermore, the electrolyte solution storage unit for sending the electrolyte solution to the hydrogen generation cell and recovering from the hydrogen generation cell, the electrolyte supply main extending from the electrolyte storage unit, and a plurality of branches from the electrolyte supply main, Branching destination of each of the hydrogen generation cells connected to the electrolyte supply hole, a gas-liquid discharge main extending from the electrolyte storage section, and a plurality of branches from the gas-liquid discharge main, And a gas-liquid discharge pipe connected to the gas-liquid discharge hole of each hydrogen generation cell. Among the plurality of hydrogen generation cells, the higher the hydrogen generation cell, the lower the flow resistance of the electrolyte supplied, so that the flow rate of the electrolyte supplied to the plurality of hydrogen generation cells becomes the same. By irradiating light to the optical semiconductor electrode configured as described above, water is decomposed to generate hydrogen.

  According to the energy generation system using the hydrogen generation device and the hydrogen generation unit according to the present invention, it is possible to solve the above-mentioned problems in the serial flow of the electrolyte in the plurality of photohydrogen generation cells, and there is a difference in height between them. Problems that arise when electrolyte solution supply pipes are connected in parallel to a plurality of hydrogen generation cells can also be solved.

FIG. 1 is a schematic diagram showing a configuration of a hydrogen generation cell according to Embodiment 1 of the present invention. FIG. 2 is a schematic view of the configuration of the hydrogen generation cell according to Embodiment 1 of the present invention as viewed from the first space side. FIG. 3 is a schematic diagram showing the configuration of the hydrogen generation device according to Embodiment 1 of the present invention. FIG. 4 is a schematic diagram showing the configuration of the hydrogen generation device according to Embodiment 2 of the present invention. FIG. 5 is a schematic diagram showing the configuration of the energy system according to Embodiment 3 of the present invention. FIG. 6 is a schematic diagram showing a configuration of an energy system according to Embodiment 4 of the present invention.

(Knowledge that became the basis of the invention)
In the case of the photowater electrolysis apparatus disclosed in Patent Document 1, a plurality of photowater electrolysis cells are arranged in a positional relationship having a height difference. Practically, when installing a photowater electrolysis apparatus composed of a plurality of photowater electrolysis cells in a certain place, it is inevitable to arrange the plurality of photowater electrolysis cells in a positional relationship having a height difference. In other words, it is not practical to arrange all the photowater electrolysis cells in a row in the horizontal direction.

  By the way, in the photowater electrolysis apparatus of patent document 1, supply of the electrolyte solution to each photowater electrolysis cell is caused by the overflow of the electrolyte solution in the adjacent upstream (higher side) photowater electrolysis cell. Is done. Similarly, the electrolyte solution is discharged from each photowater electrolysis cell by overflowing and flowing out of the electrolyte solution to the adjacent downstream (low-position) photowater electrolysis cell.

  By adopting such a mechanism, the electrolytic solution flows in series in all the photowater electrolysis cells using the potential energy obtained by the positional cell arrangement having a height difference as a driving force.

  However, in the case of such a photowater electrolysis device, when a malfunction occurs in some photowater electrolysis cells constituting the photowater electrolysis device for some reason, the influence spreads to the entire photowater electrolysis device.

  For example, consider a case where a malfunction occurs in one of the photowater electrolysis cells in a photowater electrolysis apparatus in which a plurality of photowater electrolysis cells are stacked. In this case, the cell is repaired in order to eliminate the problem, and the operation of the cell is stopped or the cell is removed from the photowater electrolysis device during the repair work.

  At this time, the flow of the electrolyte flowing in series via the plurality of photowater electrolysis cells is cut off at the location of the cell where the failure occurred. In the serial flow, if the flow is interrupted at any one place in the flow path, the flow of the entire flow path becomes impossible.

  Therefore, in the above-described case, although only one cell has a problem, all the cells cannot supply and discharge the electrolyte solution, and the operation is forced to stop. This is a problem when considering the practical application of the photowater electrolysis apparatus.

  However, in order to solve this problem of serial distribution, it is not necessary to simply connect the electrolyte supply pipes in parallel to a plurality of hydrogen generation cells installed at different heights. When parallel distribution is performed, the following three other problems occur.

  The first issue is about water pressure. When a plurality of hydrogen generating cells are connected by an electrolyte supply pipe, the electrolytes in all the cells are connected through the electrolyte in the electrolyte supply pipe. Then, a certain hydrogen generation cell will receive all the water pressure resulting from the electrolyte solution in the cell installed in a position higher than itself. Therefore, it is necessary to change the water pressure resistance design of each cell depending on the height of installation. This is a problem in terms of practicality, manufacturing cost, and complexity during construction.

  The second problem is about the amount of electrolyte supplied to each hydrogen generation cell. Considering the same parallel flow configuration as the first problem, the electrolyte solution is supplied from the electrolyte solution supply pipe to each cell. Here, a case is considered in which a mechanism for adjusting the electrolyte supply amount is not provided in the preceding stage of the electrolyte supply hole of each cell. Then, in order to supply the electrolytic solution to a cell arranged at a higher position, a higher electrolytic solution supply pressure is required to lift the electrolytic solution to the position of the cell. For this reason, electrolyte flows preferentially only to the cell arrange | positioned in a low position, and troubles appear in electrolyte supply to the cell arrange | positioned in a high position. As a result, the amount of electrolyte supplied to each cell varies depending on the position where it is installed.

  The third problem is about the electrolyte back flow in the electrolyte supply pipe. Again, consider the same parallel distribution configuration as the first issue. Here, when the supply of the electrolytic solution is stopped, the electrolytic solution in the electrolytic solution supply pipe located higher than the cell flows backward with respect to a certain cell according to gravity. The reverse flow occurs throughout the electrolyte solution supply pipe, and finally stabilizes in a state in which the electrolyte solution in the electrolyte solution supply pipe is removed. Thereafter, when supplying the electrolyte solution again to each cell, the electrolyte solution must be supplied by an amount corresponding to the space from which the electrolyte solution has been removed due to the backflow, resulting in a large energy loss when viewed from the whole system.

  Accordingly, in view of the above-described conventional problems, the present invention provides a hydrogen generation device and a hydrogen generation unit that generate hydrogen using a water decomposition reaction by an optical semiconductor, and an energy system using them.

  Specifically, a plurality of hydrogen generation cells constituting the hydrogen generation device are arranged in a positional relationship having a height difference, and connected in parallel as viewed from the flow of the electrolyte, and at the same time, the water pressure and supply amount of the electrolyte And provide a way to solve the backflow problem. In order to put the hydrogen generation device into practical use, a simple and rational connection member and method for connecting hydrogen generation cells for generating a sufficient amount of hydrogen are provided by connecting a large number of hydrogen generation cells. .

  The hydrogen generation device according to the present invention includes a plurality of hydrogen generation cells that are arranged in a positional relationship having a height difference and that are connected in parallel as viewed from the flow of the electrolyte. Here, the electrolytic solution flow rate adjusting device and the backflow prevention device are installed at the positions described above, thereby having the following functions for the flow of the electrolytic solution.

  In the following description of the present application, a description will be given in the case where an optical semiconductor electrode described later is an n-type semiconductor and generates oxygen, and a counter electrode is a hydrogen generating side. However, when the photo semiconductor electrode is a p-type semiconductor, it will be explained by replacing hydrogen and oxygen in the description corresponding to the case of the n-type semiconductor.

  First, the case where the electrolyte solution is supplied will be described. The electrolytic solution sent from the electrolytic solution storage unit is supplied from the electrolytic solution supply main pipe through the electrolytic solution supply pipes to the inside of the casing. At this time, the water pressure of the electrolyte applied to each electrolyte supply pipe varies depending on the height at which each hydrogen generation cell is installed and the path from the electrolyte storage unit. Therefore, by providing a flow rate adjusting device in the middle of each electrolytic solution supply pipe, the flow rate of the electrolytic solution supplied to each cell is all made equal.

  As a result, it is possible to prevent a situation in which the electrolytic solution is preferentially supplied only to a cell to which a high water pressure is applied, and the electrolytic solution is not supplied to a cell having only a low water pressure. In each cell to which the electrolytic solution is supplied, the electrolytic solution at a position higher than the gas-liquid discharge hole is automatically discharged from the gas-liquid discharge hole according to gravity. Therefore, the height of the electrolyte surface is determined by the height of the gas-liquid discharge hole.

  Here, since the electrolytic solution supply hole is at a position higher than the gas-liquid discharge hole, the electrolytic solution supply hole is necessarily kept at a position higher than the electrolytic solution surface. Thereby, the electrolytic solution in each cell is isolated from the electrolytic solution supply main pipe and the electrolytic solution in each electrolytic solution supply pipe. Therefore, the above-mentioned problem concerning the water pressure caused by connecting the electrolytes in the plurality of hydrogen generation cells via the electrolyte supply main and the electrolyte supply pipe is solved.

  Next, the case where the supply of the electrolytic solution is stopped will be described. Paying attention to a hydrogen generation cell, the electrolyte supply hole of the cell is subjected to water pressure derived from the electrolyte supply main pipe and the electrolyte in the electrolyte supply pipe at a position higher than the supply hole, The electrolyte flows back into the cell. Therefore, in the electrolyte supply main pipe, a backflow prevention device is provided at a position higher than a branch portion between the electrolyte supply pipe and the electrolyte supply main pipe of the cell. Thereby, the electrolyte backflow to the cell as described above is prevented.

  If this is performed for all the cells, the backflow prevention device is provided between all two adjacent branches on the electrolyte supply main pipe. As a result, the electrolyte back flow in the electrolyte supply main pipe and the electrolyte supply pipe is completely prevented. In this way, the electrolyte solution is always kept in the vicinity of the electrolyte solution supply hole of each cell, and it becomes possible to eliminate the energy loss as described above when supplying the electrolyte solution to each cell again. .

  From another point of view, the effect of adopting the hydrogen generating cell connection configuration of the present invention can be seen. In the photowater electrolysis apparatus of Patent Document 1, the supply of the electrolyte solution to each photowater electrolysis cell is performed by the inflow of the electrolyte solution overflowing in the adjacent photowater electrolysis cell. Similarly, the electrolyte solution is discharged from each photowater electrolysis cell when the electrolyte solution overflows to the adjacent photowater electrolysis cell.

  That is, the photoelectrolytic cells are connected in series as viewed from the flow of the electrolytic solution. In this case, when a problem occurs in a certain photowater electrolysis cell and the electrolyte solution cannot be distributed to the cell, the influence of the electrolyte solution distribution in the photowater electrolysis device is interrupted. As a result, during the period until the repair of the cell is completed, the operation of the majority of other normal cells must be stopped.

  In contrast, in the hydrogen generation device of the present invention, a plurality of hydrogen generation cells are connected in parallel as viewed from the flow of the electrolyte. In this case, each hydrogen generation cell is directly connected to the electrolyte supply pipe, and the electrolyte does not flow through other hydrogen generation cells. Therefore, even when a malfunction occurs in a certain hydrogen generation cell and the electrolyte cannot be distributed to the cell, if the cell is closed at the location where the cell is connected to the electrolyte supply pipe, The supply of the electrolytic solution is continued as usual. That is, the majority of other normal cells can be operated even during the repair period of the cell, and the entire hydrogen generation device can be operated.

  In view of the above, the configuration of the present invention in which a plurality of hydrogen generation cells are arranged in a positional relationship having a height difference and connected in parallel as viewed from the flow of the electrolyte is suitable as a hydrogen generation device. It can be said.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The following embodiment is an example, and the present invention is not limited to the following embodiment. Moreover, in the following embodiment, the same code | symbol may be attached | subjected to the same member and the overlapping description may be abbreviate | omitted.

(Embodiment 1)
A hydrogen generation device according to Embodiment 1 of the present invention will be described with reference to FIGS. 1, 2, and 3. FIG. 1 is a schematic diagram showing the configuration of a hydrogen generation cell used in the hydrogen generation device of the present embodiment, and FIG. 2 shows the configuration of the hydrogen generation cell used in the hydrogen generation device of the present embodiment as viewed from the first space side. FIG. 3 is a schematic diagram showing the configuration of the hydrogen generation device of the present embodiment.

  The hydrogen generation cell 100 according to the present embodiment includes a housing 1 in which at least the surface irradiated with the irradiation light 31 is translucent. The separator 2 is provided in a direction substantially parallel to the surface irradiated with the irradiation light 31 of the housing 1 so that the space inside the housing 1 is divided into two. In the second space 4 and the first space 3 and the second space 4 separated by the separator 2, the conductive substrate 5 is oriented in a direction substantially parallel to the surface irradiated with the irradiation light 31 of the housing 1. Is provided. An optical semiconductor electrode 6 is formed on the conductive substrate 5. A counter electrode 7 is provided in the first space 3. The electrical connection portion 8 electrically connects the conductive substrate 5 and the counter electrode 7. The electrolytic solution 9 containing water exists in the first space 3 and the second space 4.

  If it demonstrates along the advancing direction of the irradiation light 31 with which the hydrogen generation cell 100 is irradiated, from the side which irradiates the irradiation light 31, the one surface of the housing | casing 1 which has translucency from the side irradiated with the irradiation light 31, electrolysis The liquid 9, the optical semiconductor electrode 6, the conductive substrate 5, the separator 2, the counter electrode 7, the electrolytic solution 9, and the other surface of the casing 1 are arranged in this order. The conductive substrate 5 and the separator 2 may be in contact with each other or may be separated from each other. Further, the counter electrode 7 and the separator 2 may be in contact with each other or separated from each other. The separator 2 plays a role of exchanging ions between the electrolytic solution 9 in the first space 3 and the electrolytic solution 9 in the second space 4. Therefore, at least a part of the separator 2 is in contact with the electrolytic solution 9 in the first space 3 and the second space 4. In addition, a gap is provided between a part of the separator 2 or between the separator 2 and the inner wall of the housing 1 so that the electrolytic solution 9 can be circulated between the first space 3 and the second space 4.

  The oxygen-side gas / liquid discharge hole 12 is the case so that the electrolyte supply hole 10 penetrates the case 1, the hydrogen-side gas / liquid discharge hole 11 passes through the first space 3 side of the case 1. 1 are respectively provided so as to penetrate the second space 4 side. At this time, the hydrogen-side gas-liquid discharge hole 11 and the oxygen-side gas-liquid discharge hole 12 are arranged at a position lower than the electrolyte solution supply hole 10.

  Next, each configuration of the hydrogen generation cell 100 will be specifically described.

  The surface to which the irradiation light 31 of the housing 1 is irradiated has corrosion resistance and insulation against the electrolytic solution 9, and transmits light in the visible light region, more preferably light including peripheral wavelengths in the visible light region. Use materials. Examples of the material include glass and resin. The material of the other surface of the housing 1 only needs to have corrosion resistance and insulation against the electrolytic solution 9 and does not need to have a property of transmitting light. As the material, in addition to the glass and resin described above, a metal whose surface is corrosion-resistant and insulated can be used.

  The separator 2 has a function of allowing the electrolyte in the electrolytic solution 9 to permeate and suppressing the permeation of hydrogen and oxygen in the electrolytic solution 9. Examples of the material of the separator 2 include a solid electrolyte such as a polymer solid electrolyte. Examples of the polymer solid electrolyte include ion exchange membranes such as Nafion.

  As the conductive substrate 5, a conductive substrate or a substrate on which a conductive material is formed is used. Examples of the conductive substrate 5 include a platinum plate, indium tin oxide (ITO) glass, and fluorine-doped tin oxide (FTO) glass.

The optical semiconductor electrode 6 is formed of an n-type semiconductor or a p-type semiconductor. If the optical semiconductor electrode 6 is formed of an n-type semiconductor, oxygen is generated from the optical semiconductor electrode 6 and hydrogen is generated from the counter electrode 7. Conversely, if the optical semiconductor electrode 6 is a p-type semiconductor, hydrogen is generated from the optical semiconductor electrode 6 and oxygen is generated from the counter electrode 7. The photo semiconductor electrode 6 needs to decompose water by excitation of electrons by light irradiation. Therefore, the band edge level of the conduction band is 0 eV (vs. NHE) or less, which is the standard reduction potential of hydrogen ions, and the band edge level of the valence band is 1.23 eV (the standard oxidation potential of water). vs. NHE) or more. Such semiconductors include titanium, zirconium, vanadium, tantalum, niobium, tungsten, iron, copper, zinc, cadmium, gallium, indium and germanium oxides, oxynitrides and nitrides, complex oxides thereof, acids Nitride and nitride, and those obtained by adding alkali metal ions or alkaline earth metal ions to these are preferably used. In addition, a film made of a material having a band edge level in the conduction band equal to or lower than a standard reduction potential of hydrogen ions of 0 eV (vs. NHE) and a band edge level in the valence band of 1.23 eV (vs. A laminated film obtained by bonding films made of a substance higher than (NHE) to each other is also effectively used. As an example, for example, a WO ₃ / ITO / Si laminated film is preferably used.

  The counter electrode 7 is made of a conductive material that is active in a hydrogen generation reaction when the optical semiconductor electrode 6 is an n-type semiconductor and active in an oxygen generation reaction when it is a p-type semiconductor. Examples of the material of the counter electrode 7 include carbon and noble metals that are generally used as an electrode for water electrolysis. Specifically, carbon, platinum, platinum-supporting carbon, palladium, iridium, ruthenium, nickel, and the like can be employed.

  As the electrical connection portion 8, a general metal conductor can be used.

  The electrolytic solution 9 placed in the first space 3 and the second space 4 may be an electrolytic solution containing water, and may be acidic, neutral, or basic. For example, sulfuric acid, hydrochloric acid, potassium chloride, sodium chloride, potassium sulfate, sodium sulfate, sodium bicarbonate, sodium hydroxide and the like are preferably used.

  For the electrolyte solution supply hole 10, a material having corrosion resistance and insulation properties with respect to the electrolyte solution 9 is used. The hydrogen-side gas-liquid discharge hole 11 and the oxygen-side gas-liquid discharge hole 12 have corrosion resistance and insulating properties with respect to the electrolyte 9, and do not permeate and absorb hydrogen or oxygen at a pressure below atmospheric pressure. A material having is used. Specifically, glass, a metal with a resin surface subjected to corrosion resistance and insulation processing, or the like can be used.

  The mutual positional relationship between the electrolyte solution supply hole 10, the hydrogen side gas / liquid discharge hole 11 and the oxygen side gas / liquid discharge hole 12 is as described above.

  Next, the operation of the hydrogen generation cell 100 will be described.

  In the hydrogen generation cell 100, the light transmitted through the electrolytic solution 9 placed in the housing 1 and the second space 4 enters the optical semiconductor electrode 6. The optical semiconductor electrode 6 absorbs light and photoexcitation of electrons occurs, and in the optical semiconductor electrode 6, electrons are generated in the conduction band and holes are generated in the valence band. At this time, the contact between the optical semiconductor electrode 6 and the electrolytic solution 9 causes band bending near the surface of the optical semiconductor electrode 6 (interface with the electrolytic solution 9). Therefore, holes generated by light irradiation follow the band bending. Then, it moves to the surface of the optical semiconductor electrode 6 (interface with the electrolytic solution 9). These holes oxidize water molecules on the surface of the optical semiconductor electrode 6 to generate oxygen (the following chemical formula (1)).

  On the other hand, electrons generated in the conduction band move to the conductive substrate 5 side. The electrons moved to the conductive substrate 5 move to the counter electrode 7 side through the electrical connection portion 8. Electrons that move inside the counter electrode 7 and reach the surface of the counter electrode 7 (interface with the electrolytic solution 9) reduce protons on the surface of the counter electrode 7 to generate hydrogen (the following chemical formula (2)).

4h ⁺ + 2H ₂ O → O ₂ ↑ + 4H ⁺ (1)
4e ⁻ + 4H ⁺ → 2H ₂ ↑ (2)
Hydrogen bubbles generated on the surface of the counter electrode 7 float in the electrolytic solution 9 placed in the first space 3 and reach the liquid surface of the electrolytic solution 9. Thereafter, the gas moves to the outside of the hydrogen generation cell 100 through the hydrogen side gas / liquid discharge hole 11.

  On the other hand, oxygen bubbles generated on the surface of the optical semiconductor electrode 6 float in the electrolytic solution 9 placed in the second space 4 and reach the liquid surface of the electrolytic solution 9. Thereafter, the gas moves to the outside of the hydrogen generation cell 100 through the oxygen-side gas / liquid discharge hole 12.

  As the generation of hydrogen and oxygen by photolysis of water proceeds, the amount of the electrolyte 9 decreases. In order to compensate for this decrease, the required amount of electrolyte is supplied from the electrolyte supply hole 10 to the first space 3 and the second space 4. At this time, if the electrolyte is supplied excessively, it is automatically discharged by gravity from the hydrogen-side gas-liquid discharge hole 11 and the oxygen-side gas-liquid discharge hole 12, so that the first space 3 and the second space 4 The liquid surface height of the electrolyte solution 9 is always kept constant at the height of the hydrogen side gas / liquid discharge hole 11 and the oxygen side gas / liquid discharge hole 12. For this reason, the liquid level of the electrolytic solution 9 does not reach the height of the electrolytic solution supply hole 10. Therefore, the water pressure of the electrolytic solution at the location of the electrolytic solution supply hole 10 is not applied to the electrolytic solution 9 in the cell, and the water pressure in the cell is always kept within a certain range without excessively rising.

  The hydrogen generation device 300 according to the present embodiment includes a plurality of hydrogen generation cells 310. The configuration of the hydrogen generation cell 310 is the same as that of the hydrogen generation cell 100 described in the present embodiment. In order to circulate the electrolytic solution to the plurality of hydrogen generation cells 310, an electrolytic solution storage unit 13 having an electrolytic solution delivery and recovery function is provided.

  An electrolytic solution supply main pipe 14 extends from the electrolytic solution storage unit 13, and a plurality of electrolytic solution supply pipes 15 branch from the electrolytic solution supply main pipe 14. The tip of each electrolyte supply pipe 15 is connected to the electrolyte supply hole 10 of the hydrogen generation cell 310. A flow rate adjusting device 16 that adjusts the flow rate of the electrolyte flowing into the hydrogen generation cell 310 is provided in the middle of the electrolyte supply pipe 15. Between the two adjacent electrolyte solution supply pipe branch portions on the electrolyte solution supply main pipe 14, a backflow prevention device 17 for preventing the electrolyte solution from flowing back is provided.

  A hydrogen-side gas-liquid discharge main pipe 18 extends from the electrolyte storage unit 13, and a plurality of hydrogen-side gas-liquid discharge pipes 19 branch from the hydrogen-side gas-liquid discharge main pipe 18. The tip of the hydrogen side gas / liquid discharge pipe 19 is connected to the hydrogen side gas / liquid discharge hole 11. Similarly, an oxygen-side gas / liquid discharge main pipe 20 extends from the electrolyte storage unit 13, and a plurality of oxygen-side gas / liquid discharge pipes 21 branch from the oxygen-side gas / liquid discharge main pipe 20. The tip of the oxygen side gas / liquid discharge pipe 21 is connected to the oxygen side gas / liquid discharge hole 12.

  The electrolytic solution storage unit 13, the electrolytic solution supply main tube 14, and the electrolytic solution supply tube 15 are formed of a material having corrosion resistance to the electrolytic solution. For example, glass, resin, metal whose surface is corrosion-resistant and insulated, and the like can be used.

  The electrolytic solution storage unit 13 is provided with a mechanism for supplying water and an electrolyte into the storage unit so that the electrolytic solution concentration can be appropriately adjusted. In addition, a mechanism for sending a necessary amount of electrolyte to the electrolyte supply main pipe 14 and a mechanism for recovering excess electrolyte from the hydrogen side gas / liquid discharge main 18 and oxygen side gas / liquid discharge main 20 are provided.

  The flow rate adjusting device 16 is formed of a material having corrosion resistance to the electrolytic solution at least on the contact surface with the electrolytic solution. Further, the flow rate adjusting device 16 is provided with a mechanism for adjusting the electrolyte flow rate so that an equal amount of electrolyte flows into each hydrogen generation cell. An example of such a flow control device 16 is a needle valve. When each hydrogen generation cell is installed, the needle valve is opened / closed according to the positional relationship (for example, the lower the hydrogen generation cell, the needle valve is closed to increase the flow resistance) and flow into each hydrogen generation cell. Adjust the flow rate of the electrolyte to be the same.

  The backflow prevention device 17 is formed of a material having corrosion resistance to the electrolytic solution at least on the contact surface with the electrolytic solution. Further, the backflow prevention device 17 is provided with a mechanism for flowing the electrolyte in the forward direction and not flowing the electrolyte in the reverse direction. An example of such a backflow prevention device 17 is a check valve.

  The flow rate adjusting device 16 and the backflow prevention device 17 can be electronically controlled by providing a valve that can be electrically opened and closed with a flow rate sensor.

  The hydrogen-side gas-liquid discharge main pipe 18 and the hydrogen-side gas-liquid discharge pipe 19 are formed of a material that has a function of preventing hydrogen from permeating and adsorbing at a pressure equal to or lower than atmospheric pressure and having corrosion resistance to the electrolyte. The For example, glass, resin, metal whose surface is corrosion-resistant and insulated, and the like can be used.

  The oxygen-side gas-liquid discharge main pipe 20 and the oxygen-side gas-liquid discharge pipe 21 are formed of a material that has a function of preventing oxygen from permeating and adsorbing at a pressure equal to or lower than atmospheric pressure and having corrosion resistance to the electrolyte. The For example, glass, resin, metal whose surface is corrosion-resistant and insulated, and the like can be used.

  In the conventional photowater electrolysis apparatus, each photowater electrolysis cell is connected in series as viewed from the flow of the electrolyte solution, so that the electrolyte solution cannot be circulated independently to each cell. Therefore, when the electrolyte solution flow to a certain photowater electrolysis cell becomes impossible, the electrolyte solution flow of the entire photowater electrolysis device has to be stopped. However, by adopting the configuration of the hydrogen generation device 300 according to the present embodiment, a plurality of hydrogen generation cells are connected in parallel as viewed from the electrolyte flow, and each hydrogen generation cell is directly connected to the electrolyte supply pipe. In addition, it is possible to distribute the electrolyte independently to each hydrogen generation cell. That is, even when the electrolyte solution cannot flow to a certain hydrogen generation cell, other cells can continue to operate.

  In addition, when the electrolyte supply pipe is simply connected in parallel to a plurality of hydrogen generation cells installed at different heights, there is a problem that the flow rate of the electrolyte to each hydrogen generation cell is different, and a certain hydrogen There has been a problem that the electrolytic solution supply main pipe located higher than the electrolytic solution supply hole of the production cell and the electrolytic solution in the electrolytic solution supply pipe flow back into the cell. However, the above problem can be solved by adopting the configuration of the hydrogen generation device 300 according to the present embodiment.

  Next, the operation of the hydrogen generation device 300 will be described. Among the operations of the hydrogen generation device 300, the operations of the hydrogen generation cells 310 constituting the hydrogen generation device 300 are the same as those of the hydrogen generation cell 100 described above in the present embodiment. Therefore, description of the operation of each hydrogen generation cell is omitted here.

  The electrolytic solution stored in the electrolytic solution storage unit 13 is supplied to each hydrogen generation cell 310 through the electrolytic solution supply main pipe 14 and the electrolytic solution supply tube 15 when the electrolytic solution storage unit 13 operates. Is done. At this time, the flow rate adjusting device 16 adjusts the electrolyte flow rate so that an equal amount of electrolyte flows into all the hydrogen generation cells 310.

  The electrolyte discharged from the hydrogen-side gas-liquid discharge hole 11 and the oxygen-side gas-liquid discharge hole 12 of each hydrogen generation cell is supplied to the hydrogen-side gas-liquid discharge pipe 19 and the oxygen-side gas-liquid discharge pipe 21, and further to the hydrogen side. The gas-liquid discharge main pipe 18 and the oxygen-side gas-liquid discharge main pipe 20 are returned to the electrolyte storage unit 13.

  The hydrogen stored in the upper part of the first space 3 of each hydrogen generation cell 310 flows out of the hydrogen side gas / liquid discharge hole 11 and passes through the hydrogen side gas / liquid discharge pipe 19 and further through the hydrogen side gas / liquid discharge main pipe 18. Collected.

  Oxygen stored in the upper part of the second space 4 of each hydrogen generation cell 310 flows out from the oxygen-side gas / liquid discharge hole 12 and passes through the oxygen-side gas / liquid discharge pipe 21 and further through the oxygen-side gas / liquid discharge main pipe 20. Discharged and collected as needed.

  Since the amount of the electrolytic solution is reduced by the amount of water decomposed by light irradiation in the hydrogen generation device 300, the electrolytic solution storage unit 13 is appropriately supplemented with water and an electrolyte. Thereby, the density | concentration of the electrolyte solution 9 in the hydrogen production | generation cell 310 is kept constant.

  When the hydrogen generation cell 310 is not irradiated with light, such as at night, the operation of the hydrogen generation device 300 can be stopped as appropriate. Along with this, the operation of the electrolytic solution storage unit 13 can also be stopped. At this time, the electrolyte solution in the electrolyte solution supply main pipe 14 and the electrolyte solution supply tube 15 is not subjected to water pressure due to the electrolyte solution delivery, and tends to flow downward due to gravity.

  Here, the backflow prevention device 17 provided between the two adjacent electrolyte solution supply pipe branch portions on the electrolyte supply main pipe 14 is operated, and the backflow of the electrolyte is prevented. Thereby, even when the hydrogen generation device 300 is stopped, the electrolytic solution can remain in the electrolytic solution supply main pipe 14 and the electrolytic solution supply pipe 15.

  As a result of the above, it is possible to collect hydrogen generated by a hydrogen generation device having a configuration in which a plurality of hydrogen generation cells are arranged in a positional relationship having a height difference and are connected in parallel as viewed from the flow of the electrolyte. . Thereby, it becomes easy to perform construction on the roof of a building or a hydrogen station, and the practicality is improved.

(Embodiment 2)
A hydrogen generation device according to Embodiment 2 of the present invention will be described with reference to FIG. FIG. 4 is a schematic diagram showing a hydrogen generation device according to the second embodiment.

  The hydrogen generation device 400 of the present embodiment includes a hydrogen generation cell 410, an electrolyte supply main pipe 14, an electrolyte supply pipe 15, a flow rate adjustment device 16, a backflow prevention device 17, a hydrogen side and oxygen side gas-liquid discharge main pipe 18. , 20 and the hydrogen-side and oxygen-side gas-liquid discharge pipes 19, 21 are integrated to form a hydrogen generation unit 420, and joints 22, 23, and 24 are added. The hydrogen generation device 300 has the same configuration. Therefore, only the configuration of the hydrogen generation unit 420, the joint, and the connection mechanism of the hydrogen generation unit will be described here.

  The hydrogen generation device 400 according to the present embodiment includes a plurality of hydrogen generation units 420.

  The configuration of the hydrogen generation cell 410 constituting the hydrogen generation unit 420 is the same as that of the hydrogen generation cell 100 described above in the present embodiment. In addition, an electrolyte supply pipe 15 among the electrolyte supply pipe 15 connected to the electrolyte supply hole 10 of each hydrogen generation cell 410, the flow rate adjusting device 16 provided in the middle of the electrolyte supply pipe 15, and the electrolyte supply main pipe 14. The hydrogen generation unit 420 also includes a portion connected to the hydrogen generation cell 410 and disposed near the hydrogen generation cell 410 and the backflow prevention device 17 provided on the portion of the electrolyte supply main pipe 14. Further, the hydrogen side and oxygen side gas / liquid discharge pipes 19 and 21 connected to the hydrogen side and oxygen side gas / liquid discharge holes 11 and 12 of each hydrogen generation cell 410, and the hydrogen side and oxygen side gas / liquid discharge main pipe 18, A portion that is connected to the hydrogen-side and oxygen-side gas-liquid discharge pipes 19 and 21 and is disposed in the vicinity of the hydrogen generation cell 410 is also included in the hydrogen generation unit 420.

  The hydrogen generation unit 420 is provided with joints 22, 23 and 24 as follows.

  In the electrolyte supply main pipe 14, joints 22 that are simply connected to each other are provided at both ends of a portion allocated and divided to each hydrogen generation cell 410. The joint 22 may be made of a material having corrosion resistance and insulating properties with respect to the electrolytic solution, and may be a mechanism that does not cause leakage of the electrolytic solution. For example, rubber, resin, metal whose surface is corrosion-resistant and insulated, and the like can be used.

  In the hydrogen-side gas-liquid discharge main pipe 18, joints 23 that are simply connected to each other are provided at both ends of a portion assigned to each hydrogen generation cell 410 and divided. The joint 23 is made of a material having a function of preventing hydrogen from permeating and adsorbing at a pressure below atmospheric pressure, and has a mechanism that does not cause hydrogen leakage, and a material having corrosion resistance and insulation against an electrolyte. It is sufficient if it is configured to satisfy the mechanism that does not cause leakage of the electrolytic solution. For example, rubber, resin, metal whose surface is corrosion-resistant and insulated, and the like can be used.

  In the oxygen-side gas-liquid discharge main pipe 20, joints 24 that are simply connected to each other are provided at both ends of a portion assigned and divided to each hydrogen generation cell 410. The joint 24 is made of a material having a function of preventing oxygen from permeating and adsorbing at a pressure lower than atmospheric pressure, a mechanism that does not cause oxygen leakage, and a material having corrosion resistance and insulating properties against the electrolytic solution. It is sufficient if it is configured to satisfy the mechanism that does not cause leakage of the electrolytic solution. For example, rubber, resin, metal whose surface is corrosion-resistant and insulated, and the like can be used.

  This makes it possible to connect two identical hydrogen generation units 420 at at least three points of the joints 22, 23 and 24. By simply preparing a plurality of single hydrogen generation units 420 and repeating the connection, the hydrogen generation device 400 can be extended endlessly.

  In the conventional photowater electrolysis apparatus, it is necessary to attach a hydrogen collection pipe to each of the photowater electrolysis cells to be arranged. Therefore, the length of the hydrogen collection pipe is extremely long and complicated. There were problems such as difficulty and many man-hours required for piping installation. However, by adopting the configuration of the hydrogen generation device 400 of the present invention, it is possible to significantly reduce the length of the pipe for collecting hydrogen and the number of manifolds to solve the above problems. In addition, a large number of hydrogen generation cells can be easily and rationally connected.

  Since the operation of the hydrogen generation device 400 is the same as that of the hydrogen generation device 300 described in Embodiment 1, the description thereof is omitted.

(Embodiment 3)
The energy system of Embodiment 3 of this invention is demonstrated using FIG. FIG. 5 is a schematic diagram showing the configuration of the energy system according to the third embodiment.

  The energy system 500 of the present embodiment is provided with a hydrogen storage unit 26, a hydrogen supply pipe 27, and a fuel cell 28 in addition to the hydrogen generation device 25 having the same configuration as the hydrogen generation device 300 of the first embodiment. .

  In the energy system 500 of the present embodiment, the material and configuration of the hydrogen generation device 25 are the same as those of the hydrogen generation device 300 shown in the first embodiment. Only parts related to the hydrogen supply pipe 27 and the fuel cell 28 will be described.

  The hydrogen storage unit 26 is provided so that one is connected to the hydrogen-side gas-liquid discharge main pipe 18 and the other is connected to the hydrogen supply pipe 27. The other end of the hydrogen supply pipe 27 is provided so as to be connected to the fuel cell 28.

  The hydrogen storage unit 26 and the hydrogen supply pipe 27 are formed of a material having a function of preventing hydrogen from permeating and adsorbing at a pressure below atmospheric pressure. For example, glass, resin, metal, etc. can be used.

  The hydrogen storage unit 26 has a function of taking in and storing a necessary amount of hydrogen flowing through the hydrogen side gas-liquid discharge main pipe 18 and a function of flowing out a necessary amount of the stored hydrogen to the hydrogen supply pipe 27.

  As the fuel cell 28, a general fuel cell using hydrogen as a negative electrode active material can be adopted. For example, a polymer electrolyte fuel cell, a phosphoric acid fuel cell, a molten carbonate fuel cell, a solid oxide fuel cell, an alkaline electrolyte fuel cell and the like can be used.

  Next, the operation of the energy system 500 will be described. Among the operations of the energy system 500, the hydrogen generation device 25 is the same as the hydrogen generation device 300 shown in the first embodiment, and thus the description thereof is omitted here. The hydrogen storage unit 26, the hydrogen supply pipe 27, and the fuel cell are omitted. Only the operation related to 28 will be described.

  Hydrogen flowing through the hydrogen-side gas-liquid discharge main pipe 18 of the hydrogen generation device 25 flows into the hydrogen storage unit 26 by the operation of the hydrogen storage unit 26 and is temporarily stored. Further, the stored hydrogen is supplied from the hydrogen storage unit 26 to the fuel cell 28 through the hydrogen supply pipe 27 in accordance with the operating state of the fuel cell 28. In addition to hydrogen, a gas containing a positive electrode active material, such as air, is sent to the fuel cell 28, and power generation and hot water supply are performed in the fuel cell 28. The consumed hydrogen is discharged from the fuel cell 28 as water or the like.

  As a result, an energy system is provided in which the light energy of the irradiation light can be converted into hydrogen energy by the hydrogen generation device 25 and further converted into electric energy by the fuel cell 28 as necessary.

(Embodiment 4)
The energy system of Embodiment 4 of this invention is demonstrated using FIG. FIG. 6 is a schematic diagram showing the configuration of the energy system of the present embodiment.

  The energy system 600 of the present embodiment includes an oxygen storage in addition to the hydrogen generation device 25, the hydrogen storage unit 26, the hydrogen supply pipe 27, and the fuel cell 28 having the same configuration as the hydrogen generation device 300 of the first embodiment. A portion 29 and an oxygen supply pipe 30 are provided.

  In the energy system 600 of the present embodiment, the materials and configurations of the hydrogen generation device 25, the hydrogen storage unit 26, the hydrogen supply pipe 27, and the fuel cell 28 are the same as those of the energy system 500 shown in the third embodiment. Therefore, the description is omitted. Here, only parts related to the oxygen storage unit 29 and the oxygen supply pipe 30 will be described.

  The oxygen storage unit 29 is provided so that one is connected to the oxygen-side gas-liquid discharge main pipe 20 and the other is connected to the oxygen supply pipe 30. The other end of the oxygen supply pipe 30 is provided so as to be connected to the fuel cell 28.

  The oxygen storage unit 29 and the oxygen supply pipe 30 are formed of a material having a function of preventing hydrogen from permeating and adsorbing at a pressure equal to or lower than atmospheric pressure. For example, glass, resin, metal, etc. can be used.

  Next, the operation of the energy system 600 will be described. Among the operations of the energy system 600, the hydrogen generation device 25, the hydrogen storage unit 26, the hydrogen supply pipe 27, and the fuel cell 28 are the same as those of the energy system 500 shown in the third embodiment, and thus description thereof is omitted. Here, only operations related to the oxygen storage unit 29 and the oxygen supply pipe 30 will be described.

  Oxygen flowing through the oxygen side gas-liquid discharge main pipe 20 of the hydrogen generation device flows into the oxygen storage unit 29 by the operation of the oxygen storage unit 29 and is temporarily stored. Further, the stored oxygen is supplied from the oxygen storage unit 29 to the fuel cell 28 through the oxygen supply pipe 30 in accordance with the operating state of the fuel cell 28. The fuel cell 28 is supplied with hydrogen as the negative electrode active material and oxygen as the positive electrode active material, and the fuel cell 28 generates power and hot water. The consumed hydrogen and oxygen react to become water and are discharged from the fuel cell 28. Since the energy system 600 of the present embodiment uses pure oxygen to operate the fuel cell, the energy conversion efficiency of the fuel cell is significantly higher than that of the energy system 500 of the third embodiment using air or the like. A system is provided.

  The hydrogen generation device of the present invention and the energy system using the hydrogen generation device can be suitably used as a hydrogen supply source for a fuel cell or the like because water can be decomposed by light irradiation to generate hydrogen.

DESCRIPTION OF SYMBOLS 1 Case 2 Separator 3 1st space 4 2nd space 5 Conductive substrate 6 Photo semiconductor electrode 7 Counter electrode 8 Electrical connection part 9 Electrolyte 10 Electrolyte supply hole 11 Hydrogen side gas-liquid discharge hole 12 Oxygen side gas-liquid Discharge hole 13 Electrolyte storage part 14 Electrolyte supply main pipe 15 Electrolyte supply pipe 16 Flow control device 17 Backflow prevention device 18 Hydrogen side gas / liquid discharge main pipe 19 Hydrogen side gas / liquid discharge pipe 20 Oxygen side gas / liquid discharge main pipe 21 Oxygen side gas-liquid discharge pipe 22, 23, 24 Joint 25 Hydrogen generation device 26 Hydrogen storage part 27 Hydrogen supply pipe 28 Fuel cell 29 Oxygen storage part 30 Oxygen supply pipe 31 Irradiation light 100, 310, 410 Hydrogen generation cell 420 Hydrogen generation unit 300,400 Hydrogen generation device 500,600 Energy system

Claims (8)

A housing including a surface having translucency;
A separator that divides the space inside the housing into a first space and a second space;
A counter electrode disposed in the first space;
An optical semiconductor electrode disposed in the second space and formed on a conductive substrate;
An electrical connection for connecting the optical semiconductor electrode and the counter electrode;
An electrolyte containing water in the first space and the second space;
An electrolyte supply hole penetrating the casing for supplying the electrolyte solution;
A hydrogen-side gas-liquid discharge hole that passes through the casing in contact with the first space and is installed at a position lower than the electrolyte supply hole;
An oxygen-side gas-liquid discharge hole that passes through the housing in contact with the second space and is installed at a position lower than the electrolyte supply hole;
A plurality of hydrogen production cells having
An electrolyte storage unit for delivering the electrolyte to the hydrogen generation cell and recovering from the hydrogen generation cell;
An electrolyte supply main extending from the electrolyte storage section;
A plurality of branches from the electrolyte supply main, and each branch destination is connected to the electrolyte supply hole of each of the hydrogen generation cells;
A gas-liquid discharge main extending from the electrolyte storage unit;
A plurality of branches from the gas-liquid discharge main pipe, and each branch destination is connected to the gas-liquid discharge hole of each of the hydrogen generation cells,
Among the plurality of hydrogen generation cells, the flow rate of the electrolyte supplied to the plurality of hydrogen generation cells is the same by decreasing the flow resistance of the electrolyte supplied to the hydrogen generation cell disposed above. Configured to be
A hydrogen generation device that generates hydrogen by decomposing water by irradiating the photo semiconductor electrode with light. A flow rate adjusting device that adjusts the flow rate of the electrolyte flowing into each of the hydrogen generation cells in the middle of each of the electrolyte supply pipes;
2. The hydrogen generation device according to claim 1, further comprising a backflow prevention device that prevents backflow of the electrolyte solution between branch portions of the electrolyte solution supply tubes adjacent on the electrolyte solution supply main pipe. The flow rate adjusting device is a needle valve;
The backflow prevention device is a check valve;
The hydrogen generation device according to claim 2 . In the electrolyte storage part, having a mechanism for supplying water and electrolyte from the outside,
The hydrogen generation device according to claim 1 or 2. The hydrogen generation cell in the hydrogen generation device according to claim 2 ;
Of the electrolyte supply pipe, the flow rate adjusting device, and the electrolyte supply main pipe in the hydrogen generation device according to claim 2 , a portion in the vicinity of the hydrogen generation cell;
The backflow prevention device in the hydrogen generation device according to claim 2 , provided in a portion in the vicinity of the hydrogen generation cell of the electrolyte supply main pipe ,
The gas-liquid discharge pipe in the hydrogen generation device according to claim 2 , the gas-liquid discharge main pipe, and the portion in the vicinity of the hydrogen generation cell,
Joints of other hydrogen generation units are connected to both ends of the electrolyte supply main in the vicinity of the hydrogen generation cell and both ends of the gas-liquid discharge main in the vicinity of the hydrogen generation cell. A hydrogen generation unit with a connectable joint. Adjoining a plurality of hydrogen generating units according to claim 5;
A joint provided on the electrolyte supply main of each hydrogen generation unit and a joint provided on the gas-liquid discharge main are connected to each other,
An electrolyte storage unit,
The remaining joints provided in the electrolyte supply main of the hydrogen generation unit are provided in the electrolyte supply main extending from the electrolyte storage section, and in the gas-liquid discharge main of the hydrogen generation unit. The remaining joint was connected to a gas-liquid discharge main extending from the electrolyte storage part,
Hydrogen generation device. The hydrogen generation device;
A storage part of hydrogen generated by the hydrogen generation device;
A fuel cell,
An energy system using the hydrogen generation device according to claim 1, 2 or 6. The energy system according to claim 7, further comprising a storage part of oxygen generated by the hydrogen generation device.

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