JP2007051328A - Hydrogen production device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for effectively combining an SOFC (Solid Oxide Fuel Cell) for increasing the efficiency in a hydrogen production process by water vapor electrolysis utilizing a reducing gas; to provide an effective method for reforming a reducing gas; to provide a method for producing hydrogen; and to provide a device for performing these methods. <P>SOLUTION: In the hydrogen production method, e.g., regarding a method where, in a high temperature water vapor electrolyzer wherein an electrolytic cell is partitioned into an anode chamber and a cathode by a solid oxide electrolyte membrane, water vapor is fed to the cathode chamber, a reducing gas is fed to the anode chamber, and the water vapor is electrolyzed in the cathode chamber, so as to produce hydrogen; a solid oxide fuel cell is driven in parallel with the high temperature water vapor electrolyzer, the exhaust gas exhausted from a fuel chamber in the solid oxide fuel cell is fed to the anode chamber in the high temperature water vapor electrolyzer, and electric power obtained by the solid oxide fuel cell is used as the electric power of the high temperature water vapor electrolyzer. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a method and apparatus for producing hydrogen by high-temperature electrolysis or electrochemical decomposition of water vapor, and in particular, a cathode side of an electrolysis apparatus in which an electrolysis part is divided into an anode side and a cathode side by a solid oxide electrolyte membrane. The present invention relates to an electrolysis apparatus suitable for use in an electrolysis method with reduced electrolysis power by supplying water vapor to the anode and supplying a reducing gas to the anode side for electrolysis.

Water electrolysis methods for the purpose of hydrogen production include alkaline water electrolysis, solid polymer water electrolysis, and high temperature steam electrolysis. Alkaline water electrolysis and solid polymer water electrolysis, which are electrolyzed near room temperature, require an electrolytic voltage of 1.8 V or more, and the amount of electric power required for hydrogen production is large, so it cannot be said to be an economical hydrogen production method. On the other hand, high temperature steam electrolysis (SOEC) using a solid oxide electrolyte as a diaphragm is high in temperature and can use thermal energy for water decomposition, so the electrolysis voltage can be reduced to 1.5 V or less. The amount of power required for hydrogen production can be reduced. Furthermore, recently, by supplying natural gas to the anode side of the electrolytic cell, the oxide ions (O ²⁻ ) moving from the cathode side to the anode side in the solid oxide electrolyte membrane are reacted on the anode side, Electrolysis method that can significantly reduce power consumption by using chemical potential for water decomposition (Deoxidizer Gas Assisted Solid Oxide Electrolysis Cell: referred to as SOEC in this specification) Has been proposed (Patent Document 1). Further, in the patent filed by the present inventors, the gas that can be supplied to the anode side in SOEC is not limited to natural gas (methane). It has been shown that a gasified gas or a gas obtained by pyrolyzing an organic substance may be used (Patent Document 2).

In the method proposed in Patent Document 1 above, natural gas is directly supplied to the anode side of the electrolysis unit and reacted with oxide ions present on the anode side, and the reaction energy is decomposed in water on the cathode side. To use. In this case, in principle, the depolarization action by methane lowers the electrolysis voltage of water, so the theoretical electrolysis voltage becomes almost zero. In a practical water electrolysis apparatus, a voltage obtained by adding an overvoltage to this is required, but the above-mentioned patent document 1 claims that water electrolysis can be performed at a total voltage of about 0.5V. However, since the electric power supplied from the outside is expensive, in order to achieve the purpose of producing hydrogen for obtaining electric power efficiently and inexpensively, a process that can produce hydrogen more efficiently and inexpensively Is required.
US Pat. No. 6,051,125 JP 2004-060041 A

  A solid oxide fuel cell (SOFC) is known as a method for efficiently obtaining electric power. Therefore, it is considered that a more efficient high-purity hydrogen production process can be established by combining SOFC and high-temperature steam electrolysis using a reducing gas. However, simply using SOFC separately installed as a power source for high-temperature steam electrolysis using reducing gas is not enough to study the efficiency of the entire process.

  When building a high-purity hydrogen production process, when using hydrocarbons such as methane as the reducing gas, in order to suppress carbon deposition on the electrodes in the electrolytic cell, It is necessary to perform steam reforming or partial oxidation reforming. Furthermore, effective supply of necessary heat is important in steam reforming, and it is required that heat supply can be efficiently performed as an entire process.

  The present invention provides a method for effectively combining SOFCs, an effective reducing gas reforming method, a hydrogen producing method, and a hydrogen producing process in order to achieve high process efficiency in a hydrogen producing process using reducing gas utilizing steam electrolysis. A device is provided.

  As a result of intensive studies to solve the above problems and to provide a system capable of efficiently producing high-purity hydrogen, the present inventors have conducted a high-temperature steam electrolysis apparatus using a solid oxide electrolyte membrane. In a system for producing hydrogen by operating a fuel cell using a solid oxide electrolyte membrane in parallel with a high-temperature steam electrolyzer, communicating an anode chamber of the electrolyzer and a fuel chamber of the fuel cell, It is possible to improve the efficiency of the hydrogen production process by steam electrolysis by using the reducing gas also as the fuel gas in the fuel cell and using the power generated in the fuel cell as the power for electrolysis of the high-temperature steam electrolyzer. As a result, the present invention has been completed. The configuration of the present invention will be described below.

First, the basic principle of a hydrogen production apparatus using a high-temperature steam electrolysis apparatus using a solid oxide electrolyte membrane used in the present invention will be described with reference to FIG.
The high-temperature steam electrolysis cell 1 is partitioned by a solid oxide electrolyte diaphragm 6 into an anode chamber 5 in which an anode (anode) 3 is disposed and a cathode chamber 4 in which a cathode (cathode) 2 is disposed. High-temperature steam 9 is supplied to the cathode chamber 4 of the electrolytic cell, reducing gas 10 such as hydrocarbon is supplied to the anode chamber 5 of the electrolytic cell, and electric power 7 is converted into direct current by the AC-DC converter 8 to convert the anode 3 and When the cathode 2 is energized, the high-temperature steam 9 supplied to the cathode chamber 4 is decomposed into hydrogen ions and oxygen ions by electrolysis. The generated oxygen becomes oxide ions 13 and selectively passes through the solid oxide electrolyte membrane 6 and moves to the anode chamber 5. As a result, hydrogen 11 is obtained from the cathode chamber 4. The gas discharged from the cathode chamber 4 contains water vapor. By removing this water vapor with a condenser, an adsorption dryer or the like, high purity hydrogen gas can be obtained. A reducing gas 10 such as hydrocarbon is supplied to the anode chamber 5, and the oxide ions 13 that have moved from the cathode chamber 4 through the electrolyte membrane 6 react with the reducing gas 10. As a result, oxygen is consumed and contributes to the formation of a concentration gradient of oxide ions, so that the voltage required for water electrolysis is reduced and the power consumption is greatly reduced. From the anode chamber 5, the exhaust gas 12 containing reaction products, such as a carbon dioxide and water vapor | steam, is discharged | emitted.

On the other hand, the basic principle of the fuel cell using the solid oxide electrolyte membrane used in the present invention will be described with reference to FIG.
The solid oxide fuel cell 31 is partitioned into a fuel chamber 34 and an air chamber 35 by a diaphragm 36 of a solid oxide electrolyte. Electrodes 32 and 33 are disposed on both sides of the electrolyte membrane 36 and are electrically connected via a load (external circuit). The electrodes 32 and 33 are called a fuel electrode and an air electrode, respectively. A fuel gas 37 containing hydrocarbons, hydrogen and the like is supplied to the fuel chamber 34, and oxygen or air 38 containing oxygen is supplied to the air chamber 35. The oxygen or acid in the air supplied to the air chamber receives electrons from the air electrode 33 to become oxide ions 41, diffuses in the electrolyte membrane 36, and moves to the fuel chamber 34. In the fuel chamber 34, hydrogen or hydrocarbons in the fuel gas 37 react with the oxide ions 41 that have moved from the air chamber 35 through the electrolyte membrane 36 to generate water or carbon dioxide. Electrons released during this reaction move from the fuel electrode 32 to the air electrode 33 via an external circuit. This generates electricity. Therefore, the fuel electrode 32 functions as an anode (negative electrode), and the air electrode 33 functions as a cathode (positive electrode). Exhaust gas 39 containing carbon dioxide, water (water vapor) and the like is discharged from the fuel chamber 34, and air 40 with reduced oxygen is discharged from the air chamber 35.

  In the method according to one aspect of the present invention, the high-temperature steam electrolysis apparatus using the solid oxide electrolyte membrane described above and the fuel cell using the solid oxide electrolyte membrane are operated in parallel, and the solid oxide type The exhaust gas discharged from the fuel chamber of the fuel cell is supplied to the anode chamber of the high temperature steam electrolyzer. Further, in the method according to another aspect of the present invention, a high temperature steam electrolysis apparatus using a solid oxide electrolyte membrane and a fuel cell using a solid oxide electrolyte membrane are operated in parallel, and high temperature steam electrolysis is performed. The exhaust gas discharged from the anode chamber of the apparatus is supplied to the fuel chamber of the solid oxide fuel cell. That is, one embodiment of the present invention is to supply water vapor to the cathode chamber of a high-temperature steam electrolysis apparatus in which an electrolytic cell is partitioned into an anode chamber and a cathode by a solid oxide electrolyte diaphragm, and supply a reducing gas to the anode chamber. In a method for producing hydrogen by electrolyzing water vapor in a chamber, a solid oxide fuel cell is operated in parallel with a high temperature steam electrolyzer, and exhaust gas discharged from the fuel chamber of the solid oxide fuel cell is discharged. The present invention relates to a method for producing hydrogen, characterized in that power supplied to an anode chamber of a high-temperature steam electrolyzer and obtained by a solid oxide fuel cell is used as power for the high-temperature steam electrolyzer. In another aspect of the present invention, water vapor is supplied to a cathode chamber of a high-temperature steam electrolysis apparatus in which an electrolytic cell is partitioned into an anode chamber and a cathode chamber by a solid oxide electrolyte membrane, and a reducing gas is supplied to the anode chamber. In the method for producing hydrogen by electrolyzing water vapor in the cathode chamber, the solid oxide fuel cell is operated in parallel with the high temperature steam electrolyzer, and the exhaust gas discharged from the anode chamber of the high temperature steam electrolyzer is The present invention relates to a method for producing hydrogen, characterized in that electric power supplied to a fuel chamber of a solid oxide fuel cell and used by the solid oxide fuel cell is used as electric power for a high temperature steam electrolyzer. The present invention further relates to an apparatus for carrying out such a hydrogen production method. That is, still another aspect of the present invention includes a high-temperature steam electrolysis apparatus that supplies a reducing gas to an anode chamber by partitioning an electrolytic cell into an anode chamber and a cathode chamber by a solid oxide electrolyte membrane, and power generation by a solid oxide electrolyte membrane. A hydrogen production apparatus comprising a solid oxide fuel cell in which a cell is partitioned into a fuel chamber and an air chamber, wherein the anode chamber of the high-temperature steam electrolyzer and the fuel chamber of the solid oxide fuel cell communicate with each other In addition, the present invention relates to a hydrogen production apparatus characterized in that electric power obtained by a solid oxide fuel cell is supplied as electric power for electrolysis of a high-temperature steam electrolysis apparatus.

  FIG. 3 shows a concept of a hydrogen production apparatus according to one embodiment of the present invention. In the hydrogen production apparatus shown in FIG. 3, the solid oxide fuel cell 31 is disposed on the upstream side, the high-temperature steam electrolysis apparatus 1 using the solid oxide electrolyte membrane is disposed on the downstream side, and the fuel chamber 34 of the fuel cell 31 is disposed. The exhaust gas 39 discharged from the exhaust gas 39 is supplied to the anode chamber 5 of the high-temperature steam electrolysis apparatus 1 as a reducing gas. The same reference numerals as those in FIGS. 1 and 2 are used for the components of the high-temperature steam electrolysis apparatus 1 and the fuel cell 31. The description of the same mechanism as that described with reference to FIGS. 1 and 2 will be omitted as appropriate.

A reducing gas containing hydrocarbons, hydrogen and the like is supplied as a fuel gas 37 to the fuel chamber 34 of the solid oxide fuel cell 31. When a hydrocarbon such as methane is used as the fuel gas, water vapor is introduced into the fuel to suppress carbon deposition on the electrode and passes through the reforming catalyst layer to change the methane into CO and H _2. The reformed gas can be supplied to the fuel chamber 34 of the solid oxide fuel cell 31 as the fuel gas 37. Air 38 is supplied to the air chamber 35 of the solid oxide fuel cell 31. By the mechanism described above, the oxide ions 41 in the air 38 move from the air chamber 35 through the solid oxide electrolyte membrane 36 to the fuel chamber 34 and react with CH ₄ , CO, and H ₂ in the fuel gas. , CO and H ₂ , CO ₂ and H ₂ O, respectively. Electrons released during this reaction move from the fuel electrode 32 to the air electrode 33 via an external circuit. This generates electricity.

The exhaust gas 39 discharged from the fuel chamber 34 of the solid oxide fuel cell 31 is supplied to the anode chamber 5 of the solid oxide electrolyte membrane high temperature steam electrolyzer 1 disposed downstream. In the fuel chamber 34 of the solid oxide fuel cell 31, as described above, CH ₄ , CO, and H ₂ in the fuel gas react with oxygen to become CO, H ₂ , CO ₂ , and H ₂ O, respectively. Since only a portion of the CH ₄ in the fuel has reacted, a considerable proportion of the CH ₄ etc. remains unreacted in the exhaust gas. Therefore, by supplying the exhaust gas 39 from the fuel chamber 34 of the solid oxide fuel cell 31 to the anode chamber 5 of the high temperature steam electrolysis apparatus 1, steam electrolysis can be performed by effectively using the reducing gas component in the exhaust gas 39. It can be carried out. Further, since the fuel gas is further reformed in the fuel chamber 34 of the solid oxide fuel cell 31 by the above-described reaction, carbon deposition on the electrode in the high-temperature steam electrolysis apparatus 1 can be further suppressed. High temperature steam 9 is supplied to the cathode chamber 4 of the high temperature steam electrolysis apparatus 1. In the apparatus of the present invention shown in FIG. 3, the fuel electrode 32 and the air electrode 33 of the solid oxide fuel cell 31 at the front stage are connected to the cathode 2 and the anode 3 of the high-temperature steam electrolysis apparatus 1 at the rear stage, respectively. Since the solid oxide fuel cell 31 has high conversion efficiency, the amount of electricity generated by the solid oxide fuel cell 31 can sufficiently cover the amount of electricity required for the operation of the solid oxide electrolyte membrane high-temperature steam electrolyzer 1. be able to. The electric power supplied from the solid oxide fuel cell 31 causes the electrolysis of water vapor in the cathode chamber 4 of the high-temperature water vapor electrolysis apparatus 1 by the mechanism described above, thereby producing hydrogen 11. Thus, according to the hydrogen production method of the present invention, power is generated by a solid oxide fuel cell using a part of the reducing gas, and the power is supplied to the steam electrolyzer. By introducing the fuel cell exhaust gas into the anode chamber of the steam electrolyzer while reforming the gas, the power required for steam electrolysis is efficiently generated by the solid oxide fuel cell, and to the steam electrolyzer. The supplied reducing gas can also be modified. According to the present invention, power is generated by a solid oxide fuel cell using a reducing gas supplied as a raw material gas, and electric power obtained thereby is used for high-temperature steam electrolysis. is there. Furthermore, since the conversion efficiency is high as a feature of the solid oxide fuel cell, the conversion efficiency to hydrogen as a whole system is improved as compared with the electrolysis using electric power by normal thermal power generation. In addition, since reforming of the fuel gas is also performed in the upstream solid oxide fuel cell, the reformed gas is supplied to the high-temperature steam electrolyzer on the downstream side, and reforming of the raw material gas is performed. Part of the process can be omitted.

  Further, the solid oxide fuel cell 31 generates a large amount of heat due to heat generation due to an oxidation reaction (chemical reaction heat) and ohmic cross of generated electric power (joule heat due to electric resistance). On the other hand, the solid oxide electrolyte membrane high-temperature steam electrolysis apparatus 1 requires a high temperature of 500 to 1100 ° C. for efficient operation. Accordingly, by supplying the high-temperature exhaust gas 39 discharged from the fuel chamber 34 of the solid oxide fuel cell 31 to the anode chamber 5 of the high-temperature steam electrolysis apparatus 1 as a reducing gas, heat necessary for the high-temperature steam electrolysis apparatus 1 is obtained. Part of it. Further, the exhaust 40 discharged from the air chamber 35 of the solid oxide fuel cell 31 is also at a high temperature, and the heat of this exhaust can be used as a heating source for the high-temperature steam 9. Furthermore, when the above-described reforming catalyst layer is used, since steam reforming is a large endothermic reaction, it is important to quickly supply heat to the reforming catalyst layer. In the method of the present invention, for example, the heat of the exhaust 40 from the air chamber 35 of the solid oxide fuel cell 31 can be used as a supply heat source to the reforming catalyst layer. Further, the exhaust gas 12 from the anode chamber 5 and the hydrogen gas 11 from the cathode chamber 4 of the subsequent high-temperature steam electrolysis apparatus 1 are also discharged in a high temperature state. Therefore, the heat of these gases can be used as a heat source for the high-temperature steam 9 or a heat source supplied to the reforming catalyst layer, and a system with high heat utilization efficiency can be obtained. In this way, when constructing a system with high heat utilization efficiency by reusing heat from exhaust gas or the like as a heat source, the shorter the heat transfer distance, the less loss and effective use. It is desirable that the high-temperature steam electrolyzer or the reforming catalyst layer be disposed adjacent to the same high-temperature vessel.

  FIG. 4 shows a concept of a hydrogen production apparatus according to another aspect of the present invention. In the hydrogen production apparatus shown in FIG. 4, the high-temperature steam electrolysis apparatus 1 using a solid oxide electrolyte membrane is disposed on the upstream side, the solid oxide fuel cell 31 is disposed on the downstream side, and the anode of the high-temperature steam electrolysis apparatus 1 The exhaust gas 12 discharged from the chamber 5 is configured to be supplied to the fuel chamber 34 of the fuel cell 31 as fuel gas. The same reference numerals as those in FIGS. 1 and 2 are used for the components of the high-temperature steam electrolysis apparatus 1 and the fuel cell 31. The description of the same mechanism as that described with reference to FIGS. 1 and 2 will be omitted as appropriate.

A reducing gas 10 containing hydrocarbons, hydrogen and the like is supplied to the anode chamber 5 of the solid oxide electrolyte membrane high-temperature steam electrolysis apparatus 1. Here, as the reducing gas 10, a gas subjected to steam reforming that introduces steam into a gas containing hydrocarbons and passes the reforming catalyst layer to change hydrocarbons such as methane into CO and H ₂ is used. Can do. High temperature steam 9 is supplied to the cathode chamber 4 of the high temperature steam electrolysis apparatus 1. As will be described later, the electricity generated by the solid oxide fuel cell 31 at the subsequent stage is supplied to the electrodes 2 and 3 of the high-temperature steam electrolysis apparatus, and the water vapor is generated in the cathode chamber 4 of the high-temperature steam electrolysis apparatus 1 by the mechanism described above. The hydrogen gas 11 is produced. The exhaust gas 12 discharged from the anode chamber 5 of the solid oxide electrolyte membrane high-temperature steam electrolysis apparatus 1 is supplied as a fuel gas to the fuel chamber 34 of the solid oxide fuel cell 31 disposed downstream.

In the anode chamber 5 of the high-temperature steam electrolysis apparatus 1, CH ₄ , CO, H ₂ in the reducing gas reacts with oxygen that has moved through the solid oxide electrolyte membrane 6, and CO, H ₂ , CO ₂ , H, respectively. _Although it becomes ₂ O, since only a part of the CH ₄ in the reducing gas has reacted, a considerable proportion of CH ₄ etc. remains unreacted in the exhaust gas. Therefore, by supplying the exhaust gas from the anode chamber 5 of the high-temperature steam electrolysis apparatus 1 to the fuel chamber 34 of the solid oxide fuel cell 31, fuel that effectively utilizes unreacted reducing gas components in the exhaust gas 12. The reaction in the battery can be performed. In addition, since the reducing gas is reformed in the anode chamber 5 of the high-temperature steam electrolysis apparatus 1, carbon deposition on the electrodes in the solid oxide fuel cell 31 can be suppressed.

Air 38 is supplied to the air chamber 35 of the solid oxide fuel cell 31. By the mechanism described above, the oxide ions 41 in the air 38 move from the air chamber 35 through the solid oxide electrolyte membrane 36 to the fuel chamber 34 and react with CH ₄ , CO, and H ₂ in the fuel gas. , CO and H ₂ , CO ₂ and H ₂ O, respectively. Electrons released during this reaction move from the fuel electrode 32 to the air electrode 33 via an external circuit. This generates electricity.

  In the apparatus of the present invention shown in FIG. 4, the fuel electrode 32 and the air electrode 33 of the downstream solid oxide fuel cell 31 are connected to the cathode 2 and the anode 3 of the upstream high temperature steam electrolyzer 1, respectively. Since the solid oxide fuel cell 31 has high conversion efficiency, the amount of electricity generated by the solid oxide fuel cell 31 can sufficiently cover the amount of electricity required for the operation of the solid oxide electrolyte membrane high-temperature steam electrolyzer 1. be able to. Electrolysis in the high-temperature steam electrolysis apparatus 1 is performed by the electric power supplied from the solid oxide fuel cell 31. Thus, according to the hydrogen production method of the present invention, high-temperature steam electrolysis is performed using a part of the reducing gas, and reforming of the reducing gas is performed, and the exhaust gas of the high-temperature steam electrolysis apparatus is converted into a solid oxide. By introducing it into the fuel chamber of the fuel cell, both the high-temperature steam electrolyzer and the solid oxide fuel cell can be operated efficiently, and the power required for steam electrolysis can be efficiently achieved by the solid oxide fuel cell. By generating electricity, the high-temperature steam electrolysis apparatus can be operated without externally supplying power. Furthermore, since the conversion efficiency is high as a feature of the solid oxide fuel cell, the conversion efficiency to hydrogen as a whole system is improved as compared with the electrolysis using electric power by normal thermal power generation. In addition, since the reforming of the reducing gas is also performed in the upstream high-temperature steam electrolyzer, the reformed gas is supplied to the downstream solid oxide fuel cell, and the raw material gas is modified. Some quality processes can be omitted.

  Further, the solid oxide fuel cell 31 generates a large amount of heat due to heat generation due to an oxidation reaction (chemical reaction heat) and ohmic cross of generated power (joule heat due to electric resistance). On the other hand, the solid oxide electrolyte membrane high-temperature steam electrolysis apparatus 1 requires a high temperature of 500 to 1100 ° C. in order to operate efficiently. Therefore, by using the high temperature exhaust gas 39 discharged from the fuel chamber 34 of the solid oxide fuel cell 31 and the high temperature exhaust gas 40 discharged from the air chamber 35 as heating sources for the reducing gas 10 and the high temperature steam 9. The thermal efficiency of the entire system can be improved. Furthermore, when the above-described reforming catalyst layer is used, since steam reforming is a large endothermic reaction, it is important to quickly supply heat to the reforming catalyst layer. In the method of the present invention, for example, the heat of the high-temperature exhaust gas 39 discharged from the fuel chamber 34 of the solid oxide fuel cell 31 and the high-temperature exhaust 40 from the air chamber are used as a heat source supplied to the reforming catalyst layer. You can also. Furthermore, since the hydrogen 11 from the cathode chamber 4 of the high-temperature steam electrolysis apparatus 1 is also discharged at a high temperature, the heat of this hydrogen gas is transferred to the heating source or reforming catalyst layer of the high-temperature steam 9 or the reducing gas 10. It can also be used as a supply heat source, and a system with high heat utilization efficiency can be obtained. In this way, when constructing a system with high heat utilization efficiency by reusing heat from exhaust gas or the like as a heat source, the shorter the heat transfer distance, the less loss and effective use. It is desirable that the high-temperature steam electrolyzer or the reforming catalyst layer be disposed adjacent to the same high-temperature vessel.

  In any of the solid oxide fuel cell 31 and the high-temperature steam electrolysis apparatus 1 that are constituent elements of the hydrogen production apparatus according to the present invention, the cell that is the most important member for function expression is mainly the both surfaces of the solid electrolyte membrane and the membrane. It is comprised by the electrode (anode / cathode) arrange | positioned. As the solid oxide electrolyte, zirconium oxide (YSZ, CSZ, ScSZ) to which yttrium, calcium, scandium or the like that conducts oxide ions is added can be used.

  Since the conductivity of the oxide electrolyte improves as the temperature increases, it is usually preferable to use the oxide electrolyte at a high temperature of 500 to 1100 ° C. In addition, it is desirable to make the oxide electrolyte membrane as thin as possible in order to reduce resistance.

  As an electrode material, an air electrode 33 which is an electrode exposed to a high temperature oxidizing atmosphere, that is, an anode 3 in the high temperature steam electrolysis apparatus 1 and an electrode to which oxygen (air) is supplied in the solid oxide fuel cell 31. As for, for example, lanthanum cobaltite and lanthanum manganate which are conductive oxides can be used. In addition, as a material of the electrode 2 on the side exposed to reducing conditions, that is, the cathode 2 in the high temperature steam electrolysis apparatus 1 and the electrode 32 on the solid oxide fuel cell 31 on which the reducing gas is introduced. Since it is exposed to a high temperature / reducing atmosphere, a cermet made of a metal such as Ni or Ru and ceramics can be used. Any electrode is preferably formed of a porous material in order to maintain gas diffusibility.

  In high-temperature steam electrolysis using reducing gas, unlike the solid oxide fuel cell and simple high-temperature steam electrolysis, both the anode side and the cathode side have a reducing atmosphere, so both use a metal cermet electrode for a simpler configuration. It can be.

  In any process, as reducing gas or fuel gas, natural gas, kerosene, hydrocarbons such as methanol, these reformed gases, biomass-derived gasification gas, methane fermentation gas, or ammonia gas should be used. Can do.

  Since the sulfur compound contained in the reducing gas or the fuel gas reduces the activity of the reforming catalyst and the electrode, it is desirable to perform a desulfurization treatment or the like as a pretreatment on these raw material gases. In addition, when an organic silicon compound is contained in the source gas, it is decomposed at high temperatures to become inorganic particles, which may cause deterioration of the characteristics of the porous electrode. It is desirable to do.

  If the reducing gas or fuel gas contains a large amount of hydrocarbon-based compounds, it may be thermally decomposed at a high temperature to precipitate carbon, which may adversely affect the electrodes, etc. In order to suppress carbon deposition, it is desirable to add an appropriate amount of water vapor.

  Further, when a hydrocarbon gas is used as the raw material gas, it is preferable to supply the hydrogen production apparatus according to the present invention after steam reforming of hydrocarbons to obtain a reformed gas containing a reducing gas and hydrogen. . As the reformer that can be used for this purpose, a metal catalyst such as Ni, Ru, Pt, Rh, Pd or an alloy catalyst thereof is used alone or in combination and is supported on a support such as alumina, zirconia, silica, etc. An apparatus configured to introduce a gas to be processed (raw material gas) and water vapor under heating into the reforming catalyst layer filled with the catalyst can be used. In addition to the above, alloys such as Co, Fe, Cu, Ag, and Ir can be used as the metal catalyst, and oxides such as ceria, lanthanum cobaltite, lanthanum manganate, and lanthanum gallate are used as the support. Can also be used.

  In addition, the current density can be increased by pressurizing the steam and / or air and / or the raw material gas supplied to the fuel cell and / or the steam electrolyzer, and the pressurized hydrogen can be directly obtained from the steam electrolyzer. The pressure range at the time of pressurization is preferably from atmospheric pressure to 300 atm. However, in the case of pressurization, the reaction vessel needs to have a pressure-resistant structure in which a safety margin is added to at least the pressure. .

  In a fuel cell and a high-temperature steam electrolysis apparatus using a solid oxide electrolyte membrane, it is usually desirable to avoid high-speed heating or cooling as much as possible from the viewpoint of thermal stress. Even in the process of the present invention, high-speed heating or cooling can be performed by continuous operation. It is preferable to avoid cooling.

  Care must be taken when starting and stopping the hydrogen production apparatus according to the present invention, and since it takes time to start from room temperature, the temperature is maintained at 150 ° C. or higher, for example, even when the operation is stopped. Thus, it is desirable to take a method of suppressing the generation of thermal stress at the time of temperature rise and shortening the startup time. In addition, when the hydrogen production apparatus according to the present invention is continuously operated, it is preferable to store the produced hydrogen. For the purpose of hydrogen storage, high-pressure gas cylinders, hydrogen storage alloys, and the like can be used. Moreover, when the generated electric power is surplus, it is possible to cope with fluctuations in the required amount of hydrogen by storing electric power in the secondary battery.

  FIG. 5 shows a specific configuration example of a hydrogen production apparatus in which a high-temperature steam electrolysis apparatus according to the present invention and a solid oxide fuel cell are combined. In the following FIGS. 5, 6, 8, 9, and 10, the same reference numerals as those used in FIGS. 1 to 4 are used for the constituent elements of the fuel cell and the steam electrolysis apparatus. Moreover, description of the same mechanism as that described with reference to FIGS.

  In the apparatus shown in FIG. 5A, cylindrical solid oxide electrolyte membranes 36 and 6 whose one ends are closed are disposed in a container, so that a solid oxide fuel cell 31 and a high-temperature steam electrolysis apparatus 1 are configured. The Electrodes are arranged on both sides of the cylindrical solid oxide electrolyte membranes 36 and 6 (not shown). A cylindrical tube 50 can be arranged inside the cylindrical solid oxide electrolyte membranes 36 and 6 to form a gas flow path. The outside of the solid oxide electrolyte membrane 36 constituting the fuel cell 31 functions as a fuel chamber 34 and the inside of the fuel cell 31 as an air chamber 35, and the outside of the solid oxide electrolyte membrane 6 constituting the electrolyzer 1 is the cathode of the electrolyzer. The chamber 4 and the inside function as the anode chamber 5. The fuel chamber 34 of the fuel cell 31 and the cathode chamber 4 of the high temperature steam electrolysis apparatus 1 are separated by a partition. In the apparatus shown in FIG. 5A, the space outside the cylindrical solid oxide electrolyte membrane 36 and the space inside the cylindrical solid oxide electrolyte membrane 6 communicate with each other through an opening 51.

  In the apparatus shown in FIG. 5A, a reducing gas (fuel gas) 37 is introduced into a fuel chamber 34 of the fuel cell (outside the cylindrical solid oxide electrolyte membrane 36). On the other hand, air 38 is introduced into the cylindrical tube 50 arranged inside the cylindrical solid oxide electrolyte membrane 36 and guided to the air chamber 35. The region outside the cylindrical solid oxide electrolyte membrane 36 is the fuel chamber 34 of the solid oxide fuel cell, and the region inside the cylindrical solid oxide electrolyte membrane 36 is the air chamber 35 of the solid oxide fuel cell. Functions and the reaction proceeds by the mechanism described above, and electric power is generated between the fuel electrode and the air electrode. The generated electric power is supplied to the anode and cathode of the adjacent high-temperature steam electrolysis apparatus 1. The gas in the air chamber 35 is discharged as air 40. The gas in the fuel chamber 34 is led from the opening 51 below the fuel chamber 34 to the anode chamber 5 (inside the cylindrical solid oxide electrolyte membrane 6) of the adjacent high-temperature steam electrolysis apparatus 1. High temperature steam 9 is introduced into the cathode chamber 4 of the high temperature steam electrolysis apparatus 1. Oxide ions move from the cathode chamber 4 to the anode chamber 5 through the solid oxide electrolyte membrane 6, the electrolytic reaction of high-temperature steam proceeds, and hydrogen 11 is recovered. The gas introduced into the anode chamber 5 of the high-temperature steam electrolysis apparatus 1 is discharged as exhaust gas 12 through a cylindrical tube 50 disposed inside the cylindrical solid oxide electrolyte membrane 6.

  In the apparatus shown in FIG. 5B, instead of the opening 51, the space inside the cylindrical solid oxide electrolyte membrane 36 constituting the fuel cell 31 and the cylindrical solid oxide electrolyte constituting the electrolysis apparatus 1 are used. A space outside the membrane 6 communicates with the cylindrical tube 50. The outside of the solid oxide electrolyte membrane 36 constituting the fuel cell 31 functions as an air chamber 35 and the inside of the fuel cell 34 as a fuel chamber 34, and the outside of the solid oxide electrolyte membrane 6 constituting the electrolyzer 1 is the anode of the electrolyzer. The chamber 5 and the inside function as the cathode chamber 4.

  In the apparatus shown in FIG. 5B, reducing gas (fuel gas) 37 is guided to the inside (fuel chamber 34) of a cylindrical solid oxide electrolyte membrane 36. On the other hand, the air 38 is guided to the outside (air chamber 35) of the cylindrical solid oxide electrolyte membrane 36. The region outside the cylindrical solid oxide electrolyte membrane 36 functions as the air chamber 35 of the fuel cell, and the region inside the cylindrical solid oxide electrolyte membrane 36 functions as the fuel chamber 34 of the fuel cell. As a result, the reaction proceeds and electric power is generated between the fuel electrode and the air electrode. The generated electric power is supplied to the anode and cathode of the adjacent high-temperature steam electrolysis apparatus 1. The gas in the air chamber 35 is discharged as air 40. The gas in the fuel chamber 34 passes through the cylindrical tube 50 disposed inside the cylindrical solid oxide electrolyte membrane 36 and passes through the anode chamber 5 (the cylindrical solid oxide electrolyte membrane 6 of the cylindrical solid oxide electrolyte membrane 6). To the outer area). High-temperature water vapor 9 is introduced into the cathode chamber 4 of the electrolysis apparatus 1 (region inside the cylindrical solid oxide electrolyte membrane 6) through the cylindrical tube 50. Oxide ions move from the cathode chamber 4 to the anode chamber 5 through the solid oxide electrolyte membrane 6, the electrolytic reaction of high-temperature steam proceeds, and hydrogen 11 is recovered. The gas introduced into the anode chamber 5 of the high-temperature steam electrolysis apparatus 1 is discharged from the opening 52 as the exhaust gas 12.

  The apparatus shown in FIG. 5C is a space inside the cylindrical solid oxide electrolyte membrane 36 constituting the fuel cell 31 and a space inside the cylindrical solid oxide electrolyte membrane 6 constituting the electrolysis apparatus 1. Are communicated by the cylindrical tube 50. The outside of the solid oxide electrolyte membrane 36 constituting the fuel cell 31 functions as the air chamber 35 and the inside of the fuel cell 31 as the fuel chamber 34, and the outside of the solid oxide electrolyte membrane 6 constituting the electrolysis apparatus 1 is the high temperature steam electrolysis. The cathode chamber 4 and the inside of the apparatus 1 function as an anode chamber 5.

  In the apparatus shown in FIG. 5C, a reducing gas (fuel gas) 37 is guided to the inside (fuel chamber 34) of the cylindrical solid oxide electrolyte membrane 36. On the other hand, the air 38 is guided to the outside (air chamber 35) of the cylindrical solid oxide electrolyte membrane 36. The area outside the cylindrical solid oxide electrolyte membrane 36 is the air chamber 35 of the solid oxide fuel cell 31, and the area inside the cylindrical solid oxide electrolyte membrane 36 is the fuel chamber of the solid oxide fuel cell 31. It functions as 34, and reaction advances by the mechanism demonstrated above, and electric power generate | occur | produces between a fuel electrode and an air electrode. The generated electric power is supplied to the anode and cathode of the adjacent high-temperature steam electrolysis apparatus 1. The gas in the air chamber 35 is discharged as air 40. The gas in the fuel chamber 34 passes through the cylindrical tube 50 disposed inside the cylindrical solid oxide electrolyte membrane 36 and passes through the anode chamber 5 (the cylindrical solid oxide electrolyte membrane 6 of the cylindrical solid oxide electrolyte membrane 6). To the inner area). High-temperature water vapor 9 is introduced into the cathode chamber 4 of the electrolysis apparatus 1 (the region outside the cylindrical solid oxide electrolyte membrane 6). Oxide ions move from the cathode chamber 4 to the anode chamber 5 through the solid oxide electrolyte membrane 6, the electrolytic reaction of high-temperature steam proceeds, and hydrogen 11 is recovered. The gas introduced into the anode chamber 5 of the high temperature steam electrolysis apparatus 1 is discharged as the exhaust gas 12 through the cylindrical tube 50.

  5A to 5C, the solid oxide fuel cell 31 is disposed on the upstream side, and the high-temperature steam electrolysis apparatus 1 is disposed on the downstream side, and is discharged from the fuel chamber 34 of the solid oxide fuel cell 31. In FIG. 5A to FIG. 5C, the flow from the reducing gas (fuel gas) 37 to the exhaust gas 12 is shown. If the setting is reversed, the high-temperature steam electrolyzer 1 is disposed on the upstream side and the solid oxide fuel cell 31 is disposed on the downstream side, and the exhaust gas discharged from the anode chamber 5 of the high-temperature steam electrolyzer 1 is solidified downstream. The apparatus can be configured to be introduced into the fuel chamber 34 of the physical fuel cell 31.

  In FIGS. 3 to 5, the method of sequentially performing high-temperature steam electrolysis and power generation by arranging either the high-temperature steam electrolysis apparatus or the solid oxide fuel cell on the upstream side and the other on the downstream side has been described. A high-temperature steam electrolyzer and a solid oxide fuel cell are configured in one reaction vessel, and the anode chamber of the high-temperature steam electrolyzer and the fuel chamber of the solid oxide fuel cell are used as a common space. It is also possible to supply reducing gas, supply high-temperature water vapor to the cathode chamber of the electrolyzer, and air to the air chamber of the fuel cell to allow the high-temperature water vapor electrolysis reaction and the fuel cell reaction to proceed simultaneously. Included within the scope of the invention. That is, another aspect of the present invention is to supply water vapor to the cathode chamber of a high-temperature water vapor electrolysis apparatus in which the electrolytic cell is divided into an anode chamber and a cathode chamber by a solid oxide electrolyte membrane, and to supply a reducing gas to the anode chamber. In the method for producing hydrogen by electrolyzing water vapor in the cathode chamber, a chamber partitioned by a solid oxide electrolyte membrane is further formed in the electrolytic cell, and this is formed into an air chamber of the solid oxide fuel cell. In parallel with the high-temperature steam electrolyzer, the reductive gas supplied in combination with the anode chamber of the electrolytic cell as the fuel chamber of the solid oxide fuel cell is used as the fuel gas, and the air is supplied to the air chamber. A hydrogen production method characterized in that a solid oxide fuel cell is operated and the electric power obtained by the solid oxide fuel cell is used as electric power for a high-temperature steam electrolyzer. To.

  A specific example of an apparatus for carrying out the method according to the embodiment of the present invention is shown in FIG. The apparatus shown in FIG. 6 has a structure similar to that shown in FIGS. 5 (a) to 5 (c), but the partition between the solid oxide fuel cell 31 and the high-temperature steam electrolysis apparatus 1 is eliminated, and the apparatus shown in FIG. The space outside the cylindrical solid oxide electrolyte membrane 36 constituting the oxide fuel cell 31 and the space outside the cylindrical solid oxide electrolyte membrane 6 constituting the high-temperature steam electrolysis apparatus 1 are made the same space. Yes. Spaces outside the cylindrical solid oxide electrolyte membranes 36 and 6 function as the fuel chamber 34 of the fuel cell 31 and the anode chamber 5 of the electrolysis apparatus 1, respectively. The spaces inside the cylindrical solid oxide electrolyte membranes 36 and 6 function as the air chamber 35 of the fuel cell 31 and the cathode chamber 4 of the electrolysis apparatus 1, respectively.

  A reducing gas (fuel gas) 37 is introduced into the fuel chamber 34 of the fuel cell (outside the cylindrical solid oxide electrolyte membrane 36). On the other hand, air 38 is introduced into the cylindrical tube 50 arranged inside the cylindrical solid oxide electrolyte membrane 36 and guided to the air chamber 35. The region outside the cylindrical solid oxide electrolyte membrane 36 functions as the fuel chamber 34 of the fuel cell, and the region inside the cylindrical solid oxide electrolyte membrane 36 functions as the air chamber 35 of the fuel cell. As a result, the reaction proceeds and electric power is generated between the fuel electrode and the air electrode. The generated electric power is supplied to the anode and cathode of the adjacent high-temperature steam electrolysis apparatus 1. The gas in the air chamber 35 is discharged as air 40. The gas in the fuel chamber 34 reacts with the oxide ions that have moved through the solid oxide electrolyte membrane 36 to be reformed, and the inside of the container is outside the cylindrical solid oxide electrolyte membrane 6 (high-temperature steam electrolysis). To function as the anode chamber 5 of the device 1. High-temperature steam 9 is introduced into the cathode chamber 4 (region inside the cylindrical solid oxide electrolyte membrane 6) of the high-temperature steam electrolysis apparatus 1 through the cylindrical tube 50. Oxide ions move from the cathode chamber 4 to the anode chamber 5 through the solid oxide electrolyte membrane 6, the electrolytic reaction of high-temperature steam proceeds, and hydrogen 11 is recovered. The gas in the anode chamber 5 of the high temperature steam electrolysis apparatus 1 is discharged as exhaust gas 12.

  In the hydrogen production method of the present invention, the electric output from the solid oxide fuel cell can be taken out not only to supply power to the high-temperature steam electrolyzer but also to the outside, thereby generating power only for external output. Alternatively, all the electric power generated in the solid oxide fuel cell can be used for steam electrolysis to produce hydrogen, or in the middle, hydrogen can be produced while outputting electric power to the outside. In addition, when hydrogen is produced while outputting electric power to the outside, the ratio between the output to the outside and the output to the steam electrolyzer can be arbitrarily controlled. Furthermore, if electric power can be supplied to the steam electrolyzer from the outside, the amount of hydrogen produced can be increased by supplying the steam electrolyzer with electric power exceeding the power generation capacity of the solid oxide fuel cell.

  Regarding the operation control of the hydrogen production apparatus of the present invention, by changing the utilization rate (or power generation amount) of the reducing gas in the solid oxide fuel cell with respect to the whole process of hydrogen production, the power demand or the hydrogen demand can be met. It is possible to perform combined operation. For example, the power generation by the solid oxide fuel cell and the amount of hydrogen produced by the high-temperature steam electrolyzer are balanced as the amount of reducing gas and the supply and demand of electric power, and of course, the device of the present invention is used for efficient hydrogen production. If power generation using a solid oxide fuel cell is the main component, surplus power can be output to the outside of the electrolysis unit, and it is also necessary for the electrolysis unit to reduce the amount of power generated by the solid oxide fuel cell. Only a part of the electric power is supplied by the solid oxide fuel cell, and the shortage is supplied from the outside, whereby hydrogen production can be mainly used.

  As an example of specific operation control of the hydrogen production apparatus of the present invention, hydrogen production is mainly performed in a time zone where power demand is low (for example, at night) while balancing the hydrogen production amount and the external power supply amount. In a time zone where power demand is high (for example, during the daytime), there is a method for responding to power demand fluctuations by performing control that suppresses hydrogen production and mainly uses external power output. The apparatus according to the present invention can be effectively used as a power supply-hydrogen production composite apparatus as a highly efficient distributed system in factories, buildings, and local units.

  When all the power required for electrolysis is provided by power generation using a solid oxide fuel cell, it is necessary to balance the output of the solid oxide fuel cell with the operating conditions where the power consumed by the high-temperature steam electrolyzer is equal. preferable. For this purpose, it is preferable to combine one or more solid oxide fuel cells with a plurality of high-temperature steam electrolyzers.

  For example, the hydrogen production apparatus according to the present invention can be configured by arranging two high-temperature steam electrolyzers and one solid oxide fuel cell and electrically connecting them in series. In this case, if all the electrical connections are in series, the current of the entire electric circuit is constant (A0). Therefore, the total voltage (V1 + V2) applied to each electrolyzer is the voltage (V0) output from the fuel cell. The operating conditions may be set so that the current becomes the same as that of () (see FIG. 7).

The power output from the solid oxide fuel cell is, for example, 0.8 to 0.6 V when the current density is 0.2 A / cm ^{2 to} 0.5 A / cm ² , whereas the reducing gas Since the voltage required for high-temperature steam electrolysis using the same voltage may be as low as 0.5 V or less at the same current density, the number of electrolysis devices can be increased accordingly.

  For example, as shown in FIG. 7, when two sets of electrolyzers are connected to one fuel cell, the reducing gas used in the fuel cell is about half of the reducing gas reacted in the electrolyzer (fuel cell). The utilization rate of the reducing gas at 1 is about one third of the reducing gas used in the whole apparatus in calculation). Increasing the number of electrolyzers has the advantage of increasing the reducing gas utilization rate in the electrolyzer, but the flowing current is reduced, so the amount of hydrogen produced per electrolyzer decreases. Therefore, it is desirable that the number of electrolyzers connected is appropriately set according to the amount of power generated by the fuel cell. Specifically, for example, by changing the reducing gas utilization rate of the fuel cell, the entire output of the fuel cell is adjusted, the amount of power supplied from the fuel cell to the electrolyzer is adjusted, or a plurality of electrolyzers are arranged. By adopting a method such as changing the connection form, the connection form between the fuel cell and the electrolyzer can be suitably designed.

Further, as described above, promptly supplying heat from the fuel cell, which is a high-temperature heat source, to the steam electrolysis apparatus leads to an improvement in process efficiency.
FIGS. 8 and 9 show preferred specific examples of arrangement of elements and gas flow when a hydrogen production apparatus according to the present invention is configured by combining one or a plurality of fuel cells and a plurality of steam electrolyzers. Show. In the present invention, in order to improve the heat mobility from the fuel cell as a heat source to the electrolyzer, the fuel cell and the electrolyzer are alternately arranged close to each other and the gas flow and the heat flow are combined. It is effective to do. 8 and 9, a fuel cell and a steam electrolyzer are configured by arranging a plurality of cylindrical solid oxide electrolyte membranes having one end closed as described in FIGS. 5 and 6 in one container. The space outside the cylindrical solid oxide electrolyte membrane is commonly used as the fuel chamber of the fuel cell and the anode chamber of the electrolysis device, and the space inside the cylindrical solid oxide electrolyte membrane is used as the air for the fuel cell. Used as a chamber or a cathode chamber of an electrolyzer. 8 and 9, the same reference numerals as those used in FIGS. 1 to 6 are used for the components of the fuel cell and the steam electrolysis apparatus. Further, the gas flow and the reaction at each location are the same as those described in detail with reference to FIGS.

  In the apparatus shown in FIG. 8, the example which installed the fuel cell orthogonally at the entrance of the reducing gas 37 of a high temperature steam electrolyzer is shown. The introduced reducing gas 37 is reformed and heated while undergoing a reaction (reaction involving power generation) in the fuel cell unit 31, supplied as a reducing gas to the electrolyzer unit 1, and heated in the electrolyzer unit 1 with high-temperature steam. A reaction for producing hydrogen 11 from 9 is performed. Thereby, the reuse efficiency of the heat | fever in a hydrogen production apparatus can be improved.

  FIG. 9 shows an example in which the fuel cell unit 31 and the electrolyzer unit 1 are arranged adjacent to each other in one container. In this embodiment, the thermal conductivity from the fuel cell to the electrolyzer can be enhanced over the entire hydrogen production apparatus.

  As shown in FIG. 9, when a plurality of fuel cells 31 and a plurality of electrolyzers 1 are arranged adjacent to each other in one container, various arrangements as shown in FIG. 10 are conceivable. 10C and 10D, each circle indicates either a fuel cell or an electrolyzer.

  In the present invention, a gas reformer can be disposed between the fuel chamber of the solid oxide fuel cell and the anode chamber of the high-temperature steam electrolysis apparatus. Specifically, when a solid oxide fuel cell is arranged in the previous stage, exhaust gas discharged from the fuel chamber of the solid oxide fuel cell is introduced into the gas reformer and Further, hydrocarbon gas (fuel gas) and water vapor are introduced to perform steam reforming of the fuel under heating, and the resulting reformed gas can be introduced as a reducing gas into the anode chamber of the subsequent high-temperature steam electrolyzer. . When a high-temperature steam electrolysis apparatus is arranged in the previous stage, exhaust gas discharged from the anode chamber of the high-temperature steam electrolysis apparatus is introduced into the gas reformer, and hydrocarbon gas (fuel gas) is further added to the gas reformer. ) And steam are introduced to perform steam reforming of the fuel under heating, and the resulting reformed gas can be supplied as a fuel gas to the fuel chamber of the solid oxide fuel cell in the subsequent stage. As the gas reformer used for such a purpose, as described above, a metal catalyst such as Ni, Ru, Pt, Rh, Pd or an alloy catalyst thereof may be used alone or in combination, and alumina, zirconia may be used. An apparatus having a configuration in which a gas to be treated (raw material gas) and water vapor are introduced under heating into a reforming catalyst layer filled with a carrier such as silica can be used.

  Specific configuration examples of the apparatus according to such an embodiment are shown in FIGS. 11 and 12, the same elements as those in FIGS. 3 and 4 are denoted by the same reference numerals, and the description thereof is omitted.

In FIG. 11, the solid oxide fuel cell is installed on the upstream side and the high temperature steam electrolyzer is installed on the downstream side, and reforming is performed between the fuel chamber 34 of the solid oxide fuel cell and the anode chamber 5 of the high temperature steam electrolyzer. A container 91 is installed. In addition, a reformer 95 is also arranged in front of the solid oxide fuel cell 31, and a reformed gas 37 obtained by steam reforming hydrocarbons such as methane with the reformer 95 is used as a fuel for the solid oxide fuel cell. It can also be supplied to the chamber 34. The reformer 91 is supplied with a hydrocarbon such as methane and steam 92 as a raw material for the reducing anode gas, and performs steam reforming of the raw material gas. Further, exhaust gas 39 discharged from the fuel chamber 34 of the solid oxide fuel cell is introduced into the reformer 91. For steam reforming, for example, 2.5 mol or more of H ₂ O is required for 1 mol of methane, but exhaust gas 39 discharged from the fuel chamber 34 of the solid oxide fuel cell is introduced into the reformer 91. By doing so, the high-temperature steam contained in the exhaust gas 39 can be used as it is. When the subsequent solid oxide fuel cell 31 is generated using 1 mol of methane, assuming that the reaction rate is 80%, the off gas 39 in the fuel chamber contains 3.9 mol of H ₂ O. When 2 mol of methane is used in the subsequent high-temperature steam electrolyzer, 5 mol of H ₂ O is required as the water vapor, but 3.9 mol is supplied from the off-gas 39, so that additional H ₂ is supplied. The amount of O may be 1.1 mol. The off-gas 39 contains 20% of unreacted fuel gas, 0.2 mol of CO and 0.6 mol of hydrogen in calculation. Since this is also introduced into the anode chamber 5 of the high temperature steam electrolysis apparatus 1, assuming that the reaction rate in the high temperature steam electrolysis apparatus 1 is 80%, (0.2 + 0.6) mol × 0.8 (reaction rate) = The amount of high-purity hydrogen produced can be increased by 0.64 mol.

In addition, the heat balance of the apparatus having such a configuration will be considered. In FIG. 11, the heat balance in each apparatus is shown. Here, it is assumed that the operation is performed with the following material balance. Further upstream of the solid oxide fuel cell 31 by placing the reformer, CO 1 mole to supply methane 1 mole of water 2.5 mol of 96, _{H 2} 3 _moles, H 2 O 1.5 moles The reformed gas is prepared. This was done and the reaction was supplied to the fuel chamber 34 of the solid oxide fuel cell _31, CO 2 0.8 mol, CO 0.2 _mol, H 2 0.6 _mol, H 2 O 3.9 moles of Off-gas 39 is discharged from the fuel chamber 34. The off-gas 39 is supplied to the reformer 91, and further, 2 moles of methane and 1.1 mole of H ₂ O are additionally supplied to the reformer 91 as 92 to perform gas reforming, and CO 2.2 mol, H ₂ 6.6 mol, H ₂ O 3 mol, CO ₂ 0.8 mol of reformed gas 93 is obtained. This reformed gas 93 is supplied to the anode chamber 5 of the high temperature steam electrolysis apparatus 1.

  The reformers 91 and 95 require heat for the steam reforming reaction and heat for generating high-temperature steam from the respective raw material gases, particularly water. Further, the reformer 91 needs to supply 451 kJ of heat when reforming 2 mol of methane. On the other hand, the calorific value in the solid oxide fuel cell 31 is 328 kJ, the calorific value in the high-temperature steam electrolysis apparatus 1 is 408 kJ when the overvoltage is 0.3 V, and 272 kJ when the voltage is 0.2 V. By using it, it is possible to cover all the amount of heat necessary for the reforming reaction, and it can also be used for heating water. The reformer 95 can also supply heat by catalytic combustion of the fuel gas contained in the off gas. The total heat balance of the entire apparatus is 1612 kJ, whereas the total calorific value is 1850 kJ, and hydrogen can be produced by operating the apparatus without supplying heat from the outside.

  In order to quickly supply heat from the solid oxide fuel cell and the high temperature steam electrolyzer to the reformer 91, the catalyst layer of the reformer 91 is used as a solid oxide fuel cell and / or a high temperature steam electrolyzer. It is also effective to install in a cell container.

FIG. 12 shows a high-temperature steam electrolyzer installed upstream and a solid oxide fuel cell installed downstream, and a reformer between the anode chamber 5 of the high-temperature steam electrolyzer and the fuel chamber 34 of the solid oxide fuel cell. 101 is installed. In addition, a reformer 105 is also arranged in front of the high temperature steam electrolysis apparatus 1, and the reformed gas 10 obtained by steam reforming a hydrocarbon 106 such as methane with the reformer 105 is supplied to the anode chamber 5 of the high temperature steam electrolysis apparatus. It can also be supplied. The reformer 101 is supplied with a hydrocarbon 102 such as methane as a raw material gas for a fuel cell, and performs steam reforming of the raw material gas. Further, the exhaust gas 12 discharged from the anode chamber 5 of the high-temperature steam electrolysis apparatus is introduced into the reformer 101. When performing electrolysis using two moles of methane in high temperature steam electrolysis apparatus 1, assuming the reaction rate of 80%, on calculation, H _{2 O} is 7.8 mol to off-gas of the anode chamber, H ₂ 2 Mole, 0.4 mol of CO, and 1.6 mol of CO ₂ are contained. In the reformer 101, 2.5 mol of H ₂ O is required when reforming 1 mol of methane, but about 1/3 to 1/2 of the off gas 12 in the anode chamber 5 of the high temperature steam electrolysis apparatus 1 is reduced. If introduced into the reformer, the amount of H ₂ O is satisfied by the high-temperature steam in the off-gas 12, so that the gas reforming reaction can be performed without introducing steam from outside the system. Moreover, since 0.4 mol of H ₂ and about 0.13 mol of CO in the off gas 12 of the anode chamber 5 are also supplied to the fuel chamber of the solid oxide fuel cell, the amount of power generation is increased.

  The amount of heat absorbed by the reformer 101 is about 225 kJ, and even heat generated by the solid oxide fuel cell can be adequately covered. Therefore, heat is provided by providing a reforming catalyst layer in the cell container of the solid oxide fuel cell. You can get a balance. On the other hand, since the amount of heat required for the reaction of the reformer 105 cannot be entirely covered by the heat generated by the high-temperature steam electrolyzer, for example, the reformer 105 is divided and the external reformer and the high-temperature steam electrolyzer cell container By providing an internal reformer, it is effective to increase the thermal efficiency to balance the heat in the high-temperature steam electrolyzer. Further, heat obtained by burning off-gas of the high-temperature steam electrolysis apparatus may be used for heating the reformer 105.

  Several specific embodiments in which the reformer is disposed between the anode chamber of the high-temperature steam electrolysis apparatus and the fuel chamber of the solid oxide fuel cell are shown in FIGS. FIG. 13a shows a reformer 110 disposed in the gas outlet portion of the fuel chamber 34 of the solid oxide fuel cell in the apparatus having the configuration shown in FIG. 5a. FIG. 13b shows a reformer 110 disposed between the fuel chamber 34 of the solid oxide fuel cell and the anode chamber 5 of the high-temperature steam electrolysis apparatus in the apparatus having the configuration shown in FIG. In any form, the exhaust gas of the fuel chamber 34 is introduced into the reformer 110, and further, the raw material gas and the water vapor 111 are introduced into the reformer 110, and the reformed gas becomes the anode of the high temperature steam electrolyzer. It is introduced into the chamber 5.

  Further, FIG. 14a shows that the reformer 110 is disposed between the fuel chamber 34 of the solid oxide fuel cell and the anode chamber 5 of the high temperature steam electrolyzer in the apparatus having the configuration shown in FIG. Further, FIG. 14b shows that the reformer 110 is disposed between the fuel chamber 34 of the solid oxide fuel cell and the anode chamber 5 of the high-temperature steam electrolysis apparatus in the apparatus having the configuration shown in FIG. In any form, the exhaust gas from the upstream apparatus is introduced into the reformer 110, and further, the raw material gas and, if necessary, the water vapor 111 are introduced into the reformer 110, and the reformed gas flows downstream. It is introduced in the side device.

  In the form shown in FIGS. 13 and 14, in order to improve the heat mobility from the subsequent solid oxide fuel cell or high-temperature steam electrolyzer cell serving as a heat source to the reforming catalyst layer, they are accommodated in the same container. In addition, it is preferable to devise such as arranging the gas flow and the heat flow in close proximity and arrangement alternately. By providing the reforming catalyst layer on the partition walls of the high-temperature steam electrolyzer and the solid oxide fuel cell, heat transfer from both cells can be enhanced.

Embodiments of the present invention are as follows.
1. Water vapor is supplied to the cathode chamber of a high-temperature steam electrolysis apparatus in which the electrolytic cell is divided into an anode chamber and a cathode by a solid oxide electrolyte membrane, and a reducing gas is supplied to the anode chamber to perform electrolysis of water vapor in the cathode chamber. In the method for producing hydrogen by the operation, the solid oxide fuel cell is operated in parallel with the high temperature steam electrolyzer, and the exhaust gas discharged from the fuel chamber of the solid oxide fuel cell is supplied to the anode chamber of the high temperature steam electrolyzer And a method for producing hydrogen, wherein the electric power obtained by the solid oxide fuel cell is used as electric power for the high-temperature steam electrolyzer.

  2. Water vapor is supplied to the cathode chamber of a high-temperature steam electrolysis apparatus in which the electrolytic cell is divided into an anode chamber and a cathode chamber by a solid oxide electrolyte membrane, and a reducing gas is supplied to the anode chamber to perform electrolysis of water vapor in the cathode chamber. In the method for producing hydrogen, the solid oxide fuel cell is operated in parallel with the high temperature steam electrolyzer, and the exhaust gas discharged from the anode chamber of the high temperature steam electrolyzer is supplied to the fuel chamber of the solid oxide fuel cell. A method for producing hydrogen, characterized in that the electric power supplied and obtained by a solid oxide fuel cell is used as electric power for a high-temperature steam electrolyzer.

  3. Water vapor is supplied to the cathode chamber of a high-temperature steam electrolysis apparatus in which the electrolytic cell is divided into an anode chamber and a cathode chamber by a solid oxide electrolyte membrane, and a reducing gas is supplied to the anode chamber to perform electrolysis of water vapor in the cathode chamber. In the method for producing hydrogen, a chamber partitioned by a solid oxide electrolyte membrane is further formed in the electrolytic cell, and this is used as an air chamber of the solid oxide fuel cell, and the anode chamber of the electrolytic cell is solid. The solid oxide fuel cell is operated in parallel with the high-temperature steam electrolyzer by using the reducing gas supplied in combination as the fuel chamber of the oxide fuel cell as the fuel gas and supplying air to the air chamber. A method for producing hydrogen, characterized in that electric power obtained by a solid oxide fuel cell is used as electric power for a high-temperature steam electrolyzer.

  4). In the first or third item, the hydrocarbon gas is subjected to steam reforming to be converted into a reformed gas containing a reducing gas and hydrogen, and the obtained reformed gas is supplied to the fuel chamber of the solid oxide fuel cell. The method described.

  5. The hydrocarbon gas is subjected to steam reforming to be converted into a reformed gas containing a reducing gas and hydrogen, and the obtained reformed gas is supplied to the anode chamber of the high-temperature steam electrolysis apparatus according to the above item 2 or 3. Method.

  6). In the first, third, or fourth item, the exhaust gas discharged from the fuel chamber of the solid oxide fuel cell is subjected to steam reforming, and the resulting reformed gas is supplied to the anode chamber of the high-temperature steam electrolyzer. The method described.

  7). The exhaust gas discharged from the anode chamber of the high-temperature steam electrolysis apparatus is subjected to steam reforming, and the obtained reformed gas is supplied to the fuel chamber of the solid oxide fuel cell according to any one of the above items 2 to 4. the method of.

  8). Steam reforming is performed using a catalyst layer filled with a catalyst such as alumina, zirconia, or silica, which is a single or composite of metal catalysts such as Ni, Ru, Pt, Rh, and Pd, or an alloy catalyst thereof. 8. The method according to any one of items 4 to 7 above.

9. The method according to any one of Items 1 to 8, wherein heat generated in the solid oxide fuel cell is used as a heat source for heating the high-temperature steam electrolyzer.
10. A high-temperature steam electrolyzer that partitions an electrolytic cell into an anode chamber and a cathode chamber by a solid oxide electrolyte membrane and supplies a reducing gas to the anode chamber, and a solid in which a power generation cell is partitioned into a fuel chamber and an air chamber by a solid oxide electrolyte membrane A hydrogen production apparatus comprising an oxide fuel cell, wherein an anode chamber of a high-temperature steam electrolyzer and a fuel chamber of a solid oxide fuel cell communicate with each other, and can be obtained by a solid oxide fuel cell A hydrogen production apparatus characterized in that electric power is supplied as electric power for electrolysis of a high-temperature steam electrolysis apparatus.

  11. In a high-temperature steam electrolysis apparatus that divides an electrolytic cell into an anode chamber and a cathode chamber by a solid oxide electrolyte membrane, supplies a reducing gas to the anode chamber, and supplies high-temperature water vapor to the cathode chamber. A chamber partitioned by an electrolyte membrane is formed and used as an air chamber of a solid oxide fuel cell. A reducing gas supplied by using an anode chamber of an electrolytic cell as a fuel chamber of a solid oxide fuel cell is used. It is configured so that the solid oxide fuel cell is operated in parallel with the high-temperature steam electrolyzer by supplying air to the air chamber as fuel gas, and the electric power obtained by the solid oxide fuel cell is A hydrogen production apparatus characterized by being supplied as electric power for a high-temperature steam electrolysis apparatus.

  12 A gas reformer that converts the hydrocarbon gas into a reformed gas containing a reducing gas and hydrogen by steam reforming, wherein the reformed gas discharge port of the gas reformer is an anode chamber or a solid of a high-temperature steam electrolyzer Item 12. The hydrogen production apparatus according to Item 10 or 11, connected to a fuel chamber of an oxide fuel cell.

  13. 13. A gas reformer for subjecting a hydrocarbon gas to steam reforming between an anode chamber of a high temperature steam electrolyzer and a fuel chamber of a solid oxide fuel cell is disposed according to the above item 10 or 12. Hydrogen production equipment.

  14 The gas reformer for subjecting the hydrocarbon gas to steam reforming is disposed between the anode chamber of the high-temperature steam electrolyzer and the fuel chamber of the fuel cell in the electrolytic cell. Hydrogen production equipment.

  15. The gas reformer has a catalyst layer filled with a catalyst such as alumina, zirconia, silica or the like, which is a metal catalyst such as Ni, Ru, Pt, Rh, Pd or an alloy catalyst thereof alone or in combination. The hydrogen production apparatus according to any one of Items 12 to 14 above.

  16. 16. The apparatus according to any one of items 10 to 15, wherein heat generated in the solid oxide fuel cell is supplied as a heat source for heating the high-temperature steam electrolysis apparatus.

  Using the apparatus shown in FIG. 8, a fuel cell was used for power generation, and the generated power was supplied as a direct current power source to a high-temperature steam electrolysis apparatus to conduct a hydrogen production experiment. The electrolysis apparatus 1 used cylindrical yttrium-stabilized zirconia (YSZ) with one end closed as a solid oxide electrolyte membrane 6 and arranged Ni-zirconia cermet electrodes inside and outside thereof. Similarly, the fuel cell 31 uses cylindrical yttrium-stabilized zirconia (YSZ) with one end closed as a solid oxide electrolyte membrane 36, and a Ni-zirconia cermet electrode on the outside and a lanthanum manganate electrode on the inside.

  This is placed in a container, and at 800 ° C., gas 37 obtained by reforming methane gas through the reforming catalyst layer is supplied to the space outside the cylindrical cell, and air 38 is supplied to the space inside the fuel cell 31. First, power generation by the fuel cell 13 was confirmed.

  Next, the positive electrode (air electrode: electrode inside the cylindrical solid oxide electrolyte membrane 36) of the fuel cell 31 is used as the anode electrode (electrode outside the cylindrical solid oxide electrolyte membrane 6) of the electrolysis apparatus 1. Connect the negative electrode of the fuel cell 31 (fuel electrode: electrode outside the cylindrical solid oxide electrolyte membrane 36) to the cathode electrode of the electrolysis device (electrode inside the cylindrical solid oxide electrolyte membrane 6). Then, water vapor 9 was introduced into the space inside the cylindrical cell of the electrolysis apparatus 1.

  It was confirmed that hydrogen was generated inside the cylindrical cell of the electrolysis apparatus 1 and recovered as hydrogen gas 11.

  According to the present invention, a high-temperature steam electrolyzer using a solid oxide electrolyte membrane is combined with a solid oxide fuel cell, and a common gas is used as the reducing gas of the steam electrolyzer and the fuel gas of the fuel cell, By using the power generated in the fuel cell as a power source for electrolysis of the steam electrolyzer, high-purity hydrogen can be produced very efficiently. According to the present invention, hydrogen can be produced by high-temperature steam electrolysis without external power supply. Furthermore, according to a preferred aspect of the present invention, it is possible to provide a hydrogen production apparatus with extremely high thermal efficiency by reusing heat generated in the fuel cell as a heat source necessary for the high temperature steam electrolysis reaction.

It is a figure which shows the basic principle of the manufacturing apparatus of hydrogen by the high temperature water vapor electrolysis apparatus using a solid oxide electrolyte membrane. It is a figure which shows the basic principle of the fuel cell using a solid oxide electrolyte membrane. It is a figure which shows the concept of the hydrogen production apparatus which concerns on 1 aspect of this invention. It is a figure which shows the concept of the hydrogen production apparatus which concerns on the other aspect of this invention. It is a figure which shows the specific structural example of the hydrogen production apparatus which concerns on 1 aspect of this invention. It is a figure which shows the specific structural example of the hydrogen production apparatus which concerns on the other aspect of this invention. It is a figure which shows the relationship between the voltage and electric current of a fuel cell and an electrolysis apparatus at the time of electrically connecting one fuel cell and two electrolysis apparatuses in series. It is a figure which shows the specific structural example of the hydrogen production apparatus which concerns on the other aspect of this invention. It is a figure which shows the specific structural example of the hydrogen production apparatus which concerns on the other aspect of this invention. It is a figure which shows the various forms of arrangement | sequence in the case of arranging a some electrolytic device and a fuel cell. It is a figure which shows the concept of the hydrogen production apparatus which concerns on the other aspect of this invention. It is a figure which shows the concept of the hydrogen production apparatus which concerns on the other aspect of this invention. It is a figure which shows the specific structural example of the hydrogen production apparatus which concerns on the other aspect of this invention. It is a figure which shows the specific structural example of the hydrogen production apparatus which concerns on the other aspect of this invention.

Claims (16)

Water vapor is supplied to the cathode chamber of a high-temperature steam electrolysis apparatus in which the electrolytic cell is divided into an anode chamber and a cathode chamber by a solid oxide electrolyte membrane, and a reducing gas is supplied to the anode chamber to perform electrolysis of water vapor in the cathode chamber. In the method for producing hydrogen, the solid oxide fuel cell is operated in parallel with the high temperature steam electrolyzer, and the exhaust gas discharged from the fuel chamber of the solid oxide fuel cell is transferred to the anode chamber of the high temperature steam electrolyzer. A method for producing hydrogen, characterized in that the electric power supplied and obtained by a solid oxide fuel cell is used as electric power for a high-temperature steam electrolyzer. Water vapor is supplied to the cathode chamber of a high-temperature steam electrolysis apparatus in which the electrolytic cell is divided into an anode chamber and a cathode chamber by a solid oxide electrolyte membrane, and a reducing gas is supplied to the anode chamber to perform electrolysis of water vapor in the cathode chamber. In the method for producing hydrogen, the solid oxide fuel cell is operated in parallel with the high temperature steam electrolyzer, and the exhaust gas discharged from the anode chamber of the high temperature steam electrolyzer is supplied to the fuel chamber of the solid oxide fuel cell. A method for producing hydrogen, characterized in that the electric power supplied and obtained by a solid oxide fuel cell is used as electric power for a high-temperature steam electrolyzer. Water vapor is supplied to the cathode chamber of a high-temperature steam electrolysis apparatus in which the electrolytic cell is divided into an anode chamber and a cathode chamber by a solid oxide electrolyte membrane, and a reducing gas is supplied to the anode chamber to perform electrolysis of water vapor in the cathode chamber. In the method for producing hydrogen, a chamber partitioned by a solid oxide electrolyte membrane is further formed in the electrolytic cell, and this is used as an air chamber of the solid oxide fuel cell, and the anode chamber of the electrolytic cell is solid. The solid oxide fuel cell is operated in parallel with the high-temperature steam electrolyzer by using the reducing gas supplied in combination as the fuel chamber of the oxide fuel cell as the fuel gas and supplying air to the air chamber. A method for producing hydrogen, characterized in that electric power obtained by a solid oxide fuel cell is used as electric power for a high-temperature steam electrolyzer. The method according to claim 1 or 3, wherein the hydrocarbon gas is subjected to steam reforming to convert to a reformed gas containing a reducing gas and hydrogen, and the obtained reformed gas is supplied to a fuel chamber of a solid oxide fuel cell. . The method according to claim 2 or 3, wherein the hydrocarbon gas is subjected to steam reforming to convert to a reformed gas containing a reducing gas and hydrogen, and the resulting reformed gas is supplied to the anode chamber of the high-temperature steam electrolysis apparatus. The method according to claim 1, 3 or 4, wherein the exhaust gas discharged from the fuel chamber of the solid oxide fuel cell is subjected to steam reforming, and the resulting reformed gas is supplied to the anode chamber of the high-temperature steam electrolysis apparatus. The method according to any one of claims 2 to 4, wherein the exhaust gas discharged from the anode chamber of the high-temperature steam electrolysis apparatus is subjected to steam reforming, and the obtained reformed gas is supplied to the fuel chamber of the solid oxide fuel cell. Steam reforming is performed using a catalyst layer filled with a catalyst such as alumina, zirconia, or silica, which is a single or composite of metal catalysts such as Ni, Ru, Pt, Rh, and Pd, or an alloy catalyst thereof. The method according to claim 4, wherein the method is performed. The method according to claim 1, wherein the heat generated in the solid oxide fuel cell is used as a heat source for heating the high-temperature steam electrolysis apparatus. A high-temperature steam electrolyzer that partitions an electrolytic cell into an anode chamber and a cathode chamber by a solid oxide electrolyte membrane and supplies a reducing gas to the anode chamber, and a solid in which a power generation cell is partitioned into a fuel chamber and an air chamber by a solid oxide electrolyte membrane A hydrogen production apparatus comprising an oxide fuel cell, wherein an anode chamber of a high-temperature steam electrolyzer and a fuel chamber of a solid oxide fuel cell communicate with each other, and can be obtained by a solid oxide fuel cell A hydrogen production apparatus characterized in that electric power is supplied as electric power for electrolysis of a high-temperature steam electrolysis apparatus. In a high-temperature steam electrolysis apparatus that divides an electrolytic cell into an anode chamber and a cathode chamber by a solid oxide electrolyte membrane, supplies a reducing gas to the anode chamber, and supplies high-temperature water vapor to the cathode chamber. A chamber partitioned by an electrolyte membrane is formed and used as an air chamber of a solid oxide fuel cell. A reducing gas supplied by using an anode chamber of an electrolytic cell as a fuel chamber of a solid oxide fuel cell is used. It is configured so that the solid oxide fuel cell is operated in parallel with the high-temperature steam electrolyzer by supplying air to the air chamber as fuel gas, and the electric power obtained by the solid oxide fuel cell is A hydrogen production apparatus characterized by being supplied as electric power for a high-temperature steam electrolysis apparatus. A gas reformer that converts the hydrocarbon gas into a reformed gas containing a reducing gas and hydrogen by steam reforming, wherein the reformed gas discharge port of the gas reformer is an anode chamber or a solid of a high-temperature steam electrolyzer The hydrogen production apparatus according to claim 10 or 11, wherein the hydrogen production apparatus is connected to a fuel chamber of an oxide fuel cell. The hydrogen production apparatus according to claim 10 or 12, wherein a gas reformer for subjecting hydrocarbon gas to steam reforming is disposed between the anode chamber of the high-temperature steam electrolysis apparatus and the fuel chamber of the solid oxide fuel cell. . The hydrogen production according to claim 11 or 12, wherein a gas reformer for subjecting the hydrocarbon gas to steam reforming is disposed between the anode chamber of the high-temperature steam electrolysis apparatus and the fuel chamber of the fuel cell in the electrolytic cell. apparatus. The gas reformer has a catalyst layer filled with a catalyst such as alumina, zirconia, silica or the like, which is a metal catalyst such as Ni, Ru, Pt, Rh, Pd or an alloy catalyst thereof alone or in combination. The hydrogen production apparatus according to any one of claims 12 to 14. The apparatus according to claim 10, wherein heat generated in the solid oxide fuel cell is supplied as a heat source for heating the high-temperature steam electrolysis apparatus.

Images