Hydrogen production device

Abstract

To provide a hydrogen production device in which a novel approach is used.SOLUTION: A hydrogen production device with an IS process includes a reactor including a light source, a reflector, and a reaction tube. The reactor is a device which performs thermal decomposition reaction of a reactant gas which is at least one selected from the group consisting of sulfuric acid, sulfur trioxide, and hydrogen iodide. In the inside of the reaction tube, a reaction region for heating the reactant gas with light emitted from the light source is set. The reflector has a reflecting surface which condenses the light emitted from the light source into the reaction region. The reactant gas introduced into the reaction tube undergoes thermal decomposition in the reaction region.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a hydrogen generating apparatus. [Background technology]

[0002] In recent years, hydrogen has been attracting attention as an environmentally friendly new energy source, and various hydrogen production methods have been investigated. In particular, methods of producing hydrogen using renewable energy and water as a raw material have attracted attention as a way to achieve carbon neutrality. Patent Document 1 discloses a catalyst that can be used for water electrolysis. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2019 / 240200 Summary of the Invention [Problem to be solved by the invention]

[0004] The use of expensive metals such as platinum and iridium as electrode materials is an issue with water electrolysis, and although much research has been done, no sufficient improvements have been made. Therefore, it is desirable to propose a new method, different from electrolysis, to generate hydrogen from water using renewable energy.

[0005] An object of the present invention is to provide a hydrogen generating device using a novel method. [Means for solving the problem]

[0006] A hydrogen generation apparatus according to one embodiment of the present invention comprises: A hydrogen generation apparatus using an IS process, comprising a reaction device including a light source, a reflector, and a reaction tube, the reactor is an apparatus for carrying out a thermal decomposition reaction of a reaction gas which is at least one selected from the group consisting of sulfuric acid, sulfur trioxide, and hydrogen iodide; a reaction region in which the reaction gas is heated by light emitted from the light source is defined inside the reaction tube; the reflecting mirror has a reflecting surface that focuses the light emitted from the light source onto the reaction region; The reaction gas introduced into the reaction tube is thermally decomposed in the reaction region. [Effects of the Invention]

[0007] According to the present invention, a hydrogen generating device using a novel method is provided. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a schematic diagram showing the configuration of a hydrogen generation apparatus according to one embodiment of the present invention. [Figure 2] FIG. 2 is a cross-sectional view illustrating a heating mechanism in a reaction apparatus. DETAILED DESCRIPTION OF THE INVENTION

[0009] Specific embodiments of the present invention will be described below with reference to the drawings, but the present invention is not limited to these embodiments. The dimensions of each component shown in the drawings have been appropriately modified for the purpose of explanation and may differ from the actual form.

[0010] The hydrogen generator of the present invention is a hydrogen generator for the IS process. The IS process is a method for chemically decomposing water. Direct thermal decomposition of water requires an ultra-high temperature of approximately 4000°C. However, the IS process combines the following chemical reactions (1) to (4) to thermally decompose water into hydrogen and oxygen at a relatively low reaction temperature. The reaction in formula (1) is called the Bunsen reaction and can proceed at room temperature. The reactions in formulas (2) to (4) are all thermal decomposition reactions that require the supply of thermal energy from an external source. The reaction in formula (2) proceeds at approximately 450°C, the reaction in formula (3) at approximately 500°C, and the reaction in formula (4) at approximately 900°C. By appropriately circulating the product gases excluding hydrogen and oxygen as raw materials for other reactors, the entire system can decompose water to generate hydrogen and oxygen. I2+SO2+2H2O → H2SO4+2HI (1) 2HI → H2+I2(2) H2SO4 → SO3 + H2O (3) SO3 → SO2 + 0.5O2(4)

[0011] Fig. 1 is a schematic diagram showing the configuration of a hydrogen generator 1 according to one embodiment of the present invention. The hydrogen generator 1 shown in Fig. 1 is a hydrogen generator for an IS process, and includes a membrane Bunsen reactor 10, a sulfuric acid decomposition reactor 20, a sulfur trioxide decomposition reactor 30, a hydrogen iodide decomposition reactor 40, and a hydrogen tank 50. The sulfuric acid decomposition reactor 20, the sulfur trioxide decomposition reactor 30, and the hydrogen iodide decomposition reactor 40 are all examples of the reactors of the present invention.

[0012] With reference to Figure 1, each step in generating hydrogen from water by the IS process using a hydrogen generator 1 will be described. First, water, iodine, and sulfur dioxide are supplied to a membrane Bunsen reactor 10. The raw water is water produced, for example, by a water purification system. In the IS process, iodine and sulfur dioxide can be recycled once they are supplied to the system, so in principle, water is the only raw material that needs to be continuously supplied to the hydrogen generator 1 from outside the system.

[0013] The membrane Bunsen reactor 10 is a device for carrying out the reaction (Bunsen reaction) shown in formula (1) above, which produces sulfuric acid and hydrogen iodide from iodine, sulfur dioxide, and water. The membrane Bunsen reactor 10 includes, for example, a cathode chamber in which a cathode is placed, an anode chamber in which an anode is placed, and a cation exchange membrane between the cathode chamber and the anode chamber. When sulfur dioxide and water are supplied to the anode chamber and iodine is supplied to the cathode chamber, and a voltage is applied between the anode and cathode, hydrogen ions migrate from the anode chamber to the cathode chamber through the cation exchange membrane, causing the reaction shown in formula (5) on the anode side and the reaction shown in formula (6) on the cathode side. The membrane Bunsen reactor 10 may also be equipped with an appropriate catalyst. These reactions produce sulfuric acid in the anode chamber of the membrane Bunsen reactor 10 and hydrogen iodide in the cathode chamber. 2H2O+SO2 → H2SO4+2H + +2e - (5) 2H + +I2+2e - → 2HI (6)

[0014] The sulfuric acid produced in the anode chamber of the membrane Bunsen reactor 10 is then supplied to the sulfuric acid decomposition reactor 20. The sulfuric acid decomposition reactor 20 is a device that produces sulfur trioxide and water by the reaction of formula (3). The reaction of formula (3) is a thermal decomposition reaction that proceeds at approximately 500°C, and the sulfuric acid decomposition reactor 20 is equipped with a heating mechanism. Details of the heating mechanism will be described later. The sulfur trioxide and water produced by the reaction of formula (3) are separated by a gas separator (not shown). The configuration of the gas separator is not particularly limited, and any known gas separator can be used. The water obtained by separation is, for example, cooled and liquefied, and then supplied to the membrane Bunsen reactor 10.

[0015] The sulfur trioxide produced and separated in the sulfuric acid decomposition reactor 20 is then supplied to the sulfur trioxide decomposition reactor 30. The sulfur trioxide decomposition reactor is a device that produces sulfur dioxide and oxygen by the reaction of formula (4). The reaction of formula (4) is a thermal decomposition reaction that proceeds at approximately 900°C, and the sulfur trioxide decomposition reactor 30 is equipped with a heating mechanism. The details of the heating mechanism will be described later. The sulfur dioxide and oxygen produced by the reaction of formula (4) are separated by a gas separator (not shown). The sulfur dioxide obtained by separation is supplied to the membrane Bunsen reactor 10. The oxygen obtained by separation is released, for example, into the atmosphere.

[0016] Meanwhile, hydrogen iodide produced in the cathode chamber of the membrane Bunsen reactor 10 is then supplied to the hydrogen iodide decomposition reactor 40. The hydrogen iodide decomposition reactor 40 produces hydrogen and iodine through the reaction of formula (2). The reaction of formula (2) is a thermal decomposition reaction that proceeds at approximately 450°C, and the hydrogen iodide decomposition reactor 40 is equipped with a heating mechanism. Details of the heating mechanism will be described later. The hydrogen and iodine produced through the reaction of formula (2) are separated by a gas separator (not shown). The hydrogen obtained by the separation is sent to the hydrogen tank 50 and stored. To increase the purity of the stored hydrogen, moisture may be removed from the hydrogen gas by passing it through a dehumidifier before being sent to the hydrogen tank 50. The iodine obtained by the separation is cooled and liquefied, and then supplied to the membrane Bunsen reactor 10. Through the above process, hydrogen can be generated using water as a raw material while sulfur and iodine are circulated within the hydrogen generator 1.

[0017] Next, the sulfuric acid decomposition reaction apparatus 20 will be described, focusing on the heating mechanism. Fig. 2 is a schematic cross-sectional view showing the configuration of the sulfuric acid decomposition reaction apparatus 20 in this embodiment. As shown in Fig. 2, the sulfuric acid decomposition reaction apparatus 20 includes a reaction tube 21, a light source 22, a reflecting mirror 23, and a gas separator 24. In the sulfuric acid decomposition reaction apparatus 20 of this embodiment, two sets of heating mechanisms each including a light source 22 and a reflecting mirror 23 are provided facing each other with one reaction tube 21 between them. Fig. 2 is a cross-sectional view of a plane passing through the central axis of the reaction tube 21 and the centers of the two light sources 22.

[0018] The reaction tube 21 is a tube for heating the reaction gas supplied therein to cause the thermal decomposition reaction to proceed. As shown in FIG. 2, a reaction region R in which the thermal decomposition reaction proceeds is defined inside the reaction tube 21. The reaction gas supplied to the reaction tube 21 of the sulfuric acid decomposition reaction apparatus 20 is sulfuric acid gas. In this embodiment, the sulfuric acid gas is supplied from the lower part of the reaction tube 21. The reaction tube 21 is made of a material that can sufficiently withstand at least the high temperatures required for the thermal decomposition reaction and that is not susceptible to reaction, corrosion, deterioration, etc. caused by the reaction gas passing through the inside. The reaction tube 21 is made of, for example, quartz or glass. The inner diameter of the reaction tube 21 may be, for example, 0.5 mm or more and 5 mm or less.

[0019] The light source 22 and the reflecting mirror 23 constitute a heating mechanism for heating the reaction gas supplied into the reaction tube 21. The light source 22 is connected to a power source (not shown) and converts the supplied power into light and emits the light. The light source 22 may be, for example, a xenon lamp, a halogen lamp, or a laser diode. As shown in FIG. 2, the light L emitted from the light source 22 is appropriately reflected by the reflecting surface 23a of the reflecting mirror 23 and focused in the reaction region R in the reaction tube 21. The light focused by the light source 22 and the reflecting mirror 23 heats the sulfuric acid gas in the reaction region R to approximately 500°C, which is required for the reaction of formula (3), and the thermal decomposition reaction of formula (3) proceeds.

[0020] The gas separator 24 is provided at one end of the reaction tube 21, and selectively allows the water and sulfur trioxide produced by the thermal decomposition reaction of formula (3) to pass through while blocking sulfuric acid gas, which is the reaction gas, and separates the reaction gas from the produced gas. By providing the sulfuric acid decomposition reaction apparatus 20 with the gas separator 24, it is possible to prevent the discharge of unreacted reaction gas, increase the purity of the produced gas, and improve the utilization efficiency of the reaction gas.

[0021] The water and sulfur trioxide that have permeated the gas separator 24 are discharged from the upper part of the reaction tube 21. The discharged gas is separated into water and sulfur trioxide by, for example, a gas separator further provided on the upper part of the reaction tube 21, and the separated gas is supplied to another reaction device.

[0022] It is preferable that the reflecting surface 23a of the reflecting mirror 23 is a spheroid, and that the light source 22 is disposed at one focus of the reflecting surface, and the reaction region R is located at the other focus of the reflecting surface. With this configuration, more of the light emitted from the light source 22 can be concentrated on the reaction region R.

[0023] The power supplied to the light source 22 is preferably renewable energy. By using renewable energy as the energy source for the light source 22, carbon dioxide emissions from the pyrolysis process can be reduced.

[0024] The above description has focused on the heating mechanism of the sulfuric acid decomposition reaction apparatus 20, but the sulfuric acid decomposition reaction apparatus 20 may have additional components (not shown) as appropriate. Examples of the additional components include, but are not limited to, a coating material, a sealing material, a heat insulating material, a dehumidifier, a cooler, a thermometer, a pressure gauge, a flow meter, and an MFC (Mass Flow Controller).

[0025] Although the sulfuric acid decomposition reactor 20 has been described above, the heating mechanism for heating the reaction gas may be similar in the sulfur trioxide decomposition reactor 30 and the hydrogen iodide decomposition reactor 40. That is, the configurations and preferred embodiments of the reaction tube 21, light source 22, and reflector 23 described above are also similar in the reaction tubes, light sources, and reflectors of the sulfur trioxide decomposition reactor 30 and the hydrogen iodide decomposition reactor 40, respectively. The temperature of the reaction region R during the thermal decomposition reaction may be approximately 900°C in the sulfur trioxide decomposition reactor 30 and approximately 450°C in the hydrogen iodide decomposition reactor 40. The temperature of the reaction region R can be adjusted, for example, by controlling the output of the light source or the flow rate of the reaction gas. A configuration may be adopted in which the temperature of the reaction region R is monitored and the output of the light source or the flow rate of the reaction gas is controlled based on the temperature change to maintain an optimal temperature for the thermal decomposition reaction in each reactor.

[0026] The hydrogen generation apparatus 1 of the present invention includes a configuration in which at least one of the sulfuric acid decomposition reactor 20, sulfur trioxide decomposition reactor 30, and hydrogen iodide decomposition reactor 40 is a reactor having the above-mentioned heating mechanism. However, as explained above, it is preferable that two or more of the sulfuric acid decomposition reactor 20, sulfur trioxide decomposition reactor 30, and hydrogen iodide decomposition reactor 40 are reactors having the above-mentioned heating mechanism. In this case, different types of light sources may be used as light sources for the heating devices provided in each reactor depending on the type of substance to be thermally decomposed therein.

[0027] For example, if a reactor for thermally decomposing sulfuric acid or sulfur trioxide is defined as a first reactor, the first light source provided in the first reactor preferably emits light having a peak in at least one of the wavelengths of 3.8 μm to 4.2 μm and 6.8 μm to 7.2 μm. Since the wavelength ranges match the absorption wavelengths of sulfuric acid or sulfur trioxide, the heating efficiency of the reaction gas is improved by emitting light in the wavelength range from the light source.

[0028] Incidentally, the IS process requires high temperatures of up to 900°C for the thermal decomposition reaction of sulfuric acid, sulfur trioxide, and hydrogen iodide, and one of the challenges is selecting a heating mechanism to achieve such high temperatures. High-temperature gas-cooled reactors are being considered as a typical heating mechanism, but there are still challenges to overcome before it can be put into practical use and widespread use, from the perspectives of manufacturing a reaction vessel that can withstand high-temperature helium, radioactive waste, and ensuring safety.

[0029] On the other hand, establishing a method for generating hydrogen using renewable energy and water as a raw material is important for achieving carbon neutrality. Hydrogen generation by electrolysis of water has been considered as a method using renewable energy, but there are issues with this method, such as the need for expensive catalysts. Furthermore, the use of renewable energy in the IS process mentioned above has not previously been considered.

[0030] The hydrogen generator of the present invention uses a light source and a reflecting mirror to form a reaction region that is locally heated to a high temperature within the reaction tube, thereby achieving the high temperatures required for the IS process and generating hydrogen from water as a raw material through thermal decomposition. Since the hydrogen generator of this embodiment uses electricity as the energy source for the thermal decomposition reaction, if renewable energy is used for the electricity, hydrogen can be generated throughout the process without emitting carbon dioxide. Furthermore, because there is no need to use expensive catalysts as in the electrolysis of water, cost advantages can also be expected. [Explanation of symbols]

[0031] 1 Hydrogen generator 10. Membrane Bunsen Reactor 20 Sulfuric acid decomposition reactor 21 Reaction tube 22 Light source 23 Reflector 23a Reflective surface 24 Gas separator 30 Sulfur trioxide decomposition reactor 40 Hydrogen iodide decomposition reactor 50 Hydrogen Tank

Claims

1. A hydrogen generation apparatus using an IS process, comprising a reaction device including a light source, a reflector, and a reaction tube, the reactor is an apparatus for carrying out a thermal decomposition reaction of a reaction gas which is at least one selected from the group consisting of sulfuric acid, sulfur trioxide, and hydrogen iodide; a reaction region in which the reaction gas is heated by light emitted from the light source is defined inside the reaction tube; the reflecting mirror has a reflecting surface that focuses the light emitted from the light source onto the reaction region; A hydrogen generating apparatus in which the reaction gas introduced into the reaction tube is thermally decomposed in the reaction region.

2. 2. The hydrogen generation apparatus according to claim 1, wherein the reflecting surface is a spheroid, the light source is disposed at one focus of the reflecting surface, and the reaction region is located at the other focus of the reflecting surface.

3. The reactor includes at least a first reactor for carrying out thermal decomposition of sulfuric acid or sulfur trioxide, The first light source provided in the first reactor emits light having a peak in at least one of wavelengths of 3.8 μm or more and 4.2 μm or less and 6.8 μm or more and 7.2 μm or less. The hydrogen generating device according to claim 1 or 2.

4. 3. The hydrogen generating apparatus according to claim 1, further comprising a gas separator provided at one end of the reaction tube for blocking the reaction gas and allowing gas generated by thermal decomposition of the reaction gas to pass through.

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