Hydrogen production system

Abstract

According to exemplary embodiments of the present invention, a hydrogen production system is provided. The present invention comprises: a hydrogen generation unit configured to receive reduced iron from a reduced iron generation unit configured to generate reduced iron by reducing powdered iron ore in a reducing gas atmosphere, and to generate hydrogen from ammonia by bringing the reduced iron into contact with the ammonia; and a regeneration unit configured to receive the reduced iron from the hydrogen generation unit and to regenerate the reduced iron by reducing the reduced iron in a hydrogen gas atmosphere. According to other exemplary embodiments of the present invention, a method for producing hydrogen is provided.

Description

hydrogen production system

[0001] The present invention relates to a hydrogen production system.

[0002] More specifically, the present invention relates to a hydrogen production system linked to a steel mill.

[0003] In the past, the technology for storing and transporting hydrogen was to compress or liquefy hydrogen at high pressure. However, recently, a technology for storing and transporting hydrogen using ammonia is being reviewed and applied, and this technology using ammonia is attracting attention as it is more efficient than the existing high-pressure or liquefaction technology.

[0004] To transport and use the hydrogen stored in the ammonia, a process is required to decompose the ammonia back into hydrogen. The following reaction formula is used to produce hydrogen by decomposing ammonia.

[0005] [Reaction Formula 1]

[0006] 2NH3→ N2+ 3H2 (△H=46 kJ / mol)

[0007] This is a graph showing the thermodynamic equilibrium concentrations of ammonia and hydrogen according to the temperature and pressure of Fig. 1. As shown in Fig. 1, the ammonia decomposition reaction described above is an endothermic reaction, and the equilibrium conversion rate increases as the temperature increases. However, since the mole number of reactants is greater than the mole number of products, the equilibrium conversion rate decreases as the pressure increases.

[0008] In order to use hydrogen transported in the form of ammonia, it must go through an ammonia decomposition process to decompose the transported ammonia at the point of use, which requires a catalyst and heat energy for ammonia decomposition.

[0009] Therefore, in order to reduce energy consumption in the ammonia decomposition reaction, it is required to apply a catalyst that operates efficiently even at low temperatures.

[0010] Metal catalysts dispersed on metal oxide supports have been extensively studied as conventional ammonia decomposition catalysts. Figure 2 is a graph showing ammonia decomposition catalyst activity (turnover number). As can be seen from Figure 2, Ru catalysts are known to be the most efficient catalysts, while non-precious metal catalysts such as Ni, Co, and Fe are used.

[0011] Meanwhile, the steel industry is currently developing a hydrogen reduction process that converts the iron ore reducing agent from carbon to hydrogen. The hydrogen reduction process requires a high-temperature reaction to reduce iron ore, and the reduced iron produced thereby can have high thermal energy. When such reduced iron is used as a catalyst for the ammonia decomposition reaction, the energy required for ammonia decomposition can be efficiently supplied, thereby increasing the efficiency of the ammonia decomposition process. However, when reduced iron is used as a catalyst for the ammonia decomposition reaction, the surface of the reduced iron is nitrided, resulting in Fe x N y Problems have arisen with the formation of iron nitride in the structure. Therefore, the development of technologies to address the aforementioned issues is necessary.

[0012] (Patent Document 1) Japanese Patent Publication No. 2011-179089.

[0013] The technical idea of ​​the present invention aims to solve a problem by providing a hydrogen production system linked to a steelmaking process.

[0014] The objectives of the present invention are not limited to the above-described content. Those skilled in the art will have no difficulty understanding the additional objectives of the present invention from the overall description of the present invention.

[0015] According to exemplary embodiments of the present invention, a hydrogen production system is provided. The hydrogen production system includes a hydrogen production unit configured to receive reduced iron from a reduced iron production unit configured to reduce iron ore in a reducing gas atmosphere to produce reduced iron, and to contact the reduced iron with ammonia to produce hydrogen from the ammonia; and a regeneration unit configured to receive the reduced iron from the hydrogen production unit and to regenerate the reduced iron by reducing the reduced iron in a hydrogen gas atmosphere.

[0016] The reducing gas may include any one of hydrogen, carbon monoxide, and combinations thereof.

[0017] The above-mentioned reduced iron generation unit may include any one of a fluidized bed reduction furnace, a shaft furnace, and a combination thereof.

[0018] The above ammonia is 3000~9000 h -1 It can be supplied to the hydrogen generating unit so as to contact the reduced iron at a space velocity of .

[0019] The temperature of the reduced iron supplied to the above hydrogen generation unit may be 600 to 1000°C.

[0020] The size of the above reduced iron may be 0.5 to 2 mm.

[0021] The reduction treatment of the reduced iron may be performed at a temperature equal to or higher than the supply temperature of the reduced iron supplied to the regeneration unit.

[0022] The reduced iron supplied to the above regeneration unit can be reduced in a hydrogen gas atmosphere at 600°C or higher.

[0023] The above hydrogen production system can be configured so that some of the hydrogen produced in the hydrogen production unit is provided to the regeneration unit.

[0024] According to other exemplary embodiments of the present invention, a method for producing hydrogen is provided. The method for producing hydrogen includes the steps of reducing iron ore to prepare reduced iron using any one of a fluidized bed reactor, a shaft furnace, and a combination thereof; providing ammonia to the reduced iron to produce hydrogen through an ammonia decomposition reaction; and, after the ammonia decomposition reaction, providing hydrogen gas to the reduced iron to perform a reduction treatment on the reduced iron.

[0025] Some of the hydrogen produced by the above ammonia decomposition reaction can be provided to the reduction treatment step of the reduced iron.

[0026] In the step of producing the above hydrogen, the temperature of the reduced iron may be 600 to 1000°C.

[0027] The size of the above reduced iron may be 0.5 to 2 mm.

[0028] The reduction treatment of the above reduced iron can be performed at a temperature equal to or higher than the temperature of the reduced iron immediately after the ammonia decomposition reaction.

[0029] The reduction treatment of the above reduced iron can be performed at a temperature of 600°C or higher.

[0030] According to exemplary embodiments of the present invention, a hydrogen production system linked to a steelmaking process can be provided.

[0031] The various advantageous and beneficial effects of the present invention are not limited to the above-described contents, and will be more easily understood in the course of explaining specific embodiments of the present invention.

[0032] FIG. 1 is a drawing for explaining a hydrogen production system according to exemplary embodiments.

[0033] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the attached drawings. Prior to this, it should be noted that the terms and words used in this specification and claims should not be construed as limited to their conventional or dictionary meanings. Based on the principle that the inventor can appropriately define the concepts of terms to best explain his or her invention, they should be interpreted in a way that aligns with the technical spirit of the present invention.

[0034] Hereinafter, when explaining with reference to drawings, identical or corresponding components are given the same drawing reference numerals and redundant descriptions thereof are omitted.

[0035] In the embodiments below, terms such as first, second, etc. are not used in a limiting sense, but are used for the purpose of distinguishing one component from another.

[0036] In the following embodiments, singular expressions include plural expressions unless the context clearly indicates otherwise.

[0037] In the embodiments below, terms such as “include” or “have” mean that a feature or component described in the specification is present, and do not preclude the possibility that one or more other features or components may be added.

[0038] For convenience of explanation, the sizes of components in the drawings may be exaggerated or reduced. For example, the sizes and thicknesses of each component shown in the drawings are arbitrarily indicated for convenience of explanation, and thus the present invention is not necessarily limited to what is shown.

[0039] If a particular embodiment is capable of being implemented differently, a particular process sequence may be performed in a different order than described. For example, two processes described in succession may be performed substantially simultaneously, or in a reverse order from the described order.

[0040] In addition, when describing the present invention, if it is determined that a detailed description of a related known configuration or function may obscure the gist of the present invention, the detailed description is omitted.

[0041] FIG. 1 is a drawing for explaining a hydrogen production system (10) according to exemplary embodiments.

[0042] Referring to FIG. 1, a hydrogen production system (10) according to exemplary embodiments may include a reduced iron production unit (100), a hydrogen production unit (200), and a regeneration unit (300).

[0043] In this way, the hydrogen production system (10) uses reduced iron to produce hydrogen. Iron (Fe) has a lower global warming potential (GWP) for CO2 emissions required for mining and extraction compared to other metal elements that can be used as catalysts for ammonia decomposition reactions. Therefore, by directly using iron utilized in the steelmaking process as a catalyst for the ammonia decomposition reaction, carbon dioxide emissions that may occur during a separate ammonia decomposition catalyst manufacturing process can be substantially reduced. In addition, since it is cheaper than other metal elements that can be used as ammonia decomposition catalysts, the unit cost of hydrogen production generated during the catalyst manufacturing process can be lowered, which can be more advantageous from an economic perspective.

[0044] According to exemplary embodiments, the reduced iron generating unit (100) may be configured to generate reduced iron by reducing iron ore in a reducing gas atmosphere.

[0045] The operating conditions of the reduced iron generator (100) are not particularly limited as long as it can perform iron ore reduction. As a non-limiting example, the reduced iron generator (100) can be operated in a pressure range of 2 to 8 barg and a temperature range of 500 to 1000°C. More specifically, the reduced iron generator (100) can be operated in a temperature range of 700 to 1000°C.

[0046] The reduced iron production unit (100) may include any one of a fluidized bed reduction furnace, a shaft furnace, and a combination thereof. The fluidized bed reduction furnace can reduce iron ore by introducing and transporting iron ore fines in the furnace to form a fluidized bed of iron ore fines and supplying reducing gas to the fluidized bed of iron ore fines. The reducing gas can be supplied from the bottom of the fluidized bed reduction furnace. The shaft furnace is configured to allow iron ore fines in pellet form supplied to the top of the furnace to move to the bottom of the furnace. The reducing gas is supplied so as to contact the iron ore fines countercurrently with respect to the direction of movement of the iron ore fines. Such a fluidized bed reduction furnace and shaft furnace can omit the coke process of a conventional iron making process, thereby significantly reducing carbon dioxide emissions compared to a conventional iron making process.

[0047] As a non-limiting example, the reduced iron production unit (100) may include a plurality of fluidized bed reactors connected in series. In this case, fine iron ore may be fed and transported to each of the plurality of fluidized bed reactors and subjected to reduction treatment. The reducing gas supplied to a fluidized bed reactor positioned at the rear end based on the feeding and transport direction of the fine iron ore may be captured at the top of the fluidized bed reactor and then supplied to a fluidized bed reactor positioned at the front end. This may further enhance the reduction efficiency of the fine iron ore.

[0048] The reducing gas may comprise hydrogen, carbon monoxide, or a combination thereof. From a carbon dioxide emission perspective, it is preferred that the reducing gas be composed essentially of hydrogen.

[0049] The hydrogen generation unit (200) may be configured to generate hydrogen by thermally decomposing ammonia over a catalyst. More specifically, the hydrogen generation unit (200) may be configured to generate hydrogen from ammonia by bringing the reduced iron generated in the reduced iron generation unit (100) into contact with ammonia. The generated hydrogen may flow to the upper portion of the hydrogen generation unit (200). Not only the generated hydrogen but also nitrogen decomposed from ammonia may be distributed in the upper portion of the hydrogen generation unit (200). That is, a mixed gas including hydrogen, nitrogen, and un-decomposed ammonia may be distributed in the upper portion of the hydrogen generation unit (200). According to exemplary embodiments, hydrogen may be separated and purified from the mixed gas by any one of a membrane separation method, a pressure swing adsorption (PSA) method, a thermal swing adsorption (TSA) method, a vacuum swing adsorption (VSA) method, and a combination thereof. More specifically, hydrogen may be separated and purified by the pressure swing adsorption (PSA) method.

[0050] As a non-limiting example, the hydrogen generation unit (200) may be a fluidized bed reactor having a fluidized bed of reduced iron formed therein. In this case, ammonia may be supplied to the hydrogen generation unit (200) so that it can come into contact with the fluidized bed of reduced iron. To this end, the ammonia may be supplied to any one of the upper, lower, or upper and lower portions of the hydrogen generation unit (200).

[0051] The hydrogen generation unit (200) can receive reduced iron from the reduced iron generation unit (100). The reduced iron generation unit (100) reduces iron ore under high temperature environmental conditions, and thus the reduced iron provided from the reduced iron generation unit (100) can contain thermal energy corresponding to the high temperature. By utilizing such reduced iron as a catalyst for the ammonia decomposition reaction, the thermal energy required for the ammonia decomposition reaction can be supplied. Accordingly, the hydrogen generation unit (200) can perform the ammonia decomposition reaction using the autothermal energy of the reduced iron even without heating the catalyst for the ammonia decomposition reaction, thereby improving the energy efficiency of the hydrogen production system (10).

[0052] The internal average temperature of the hydrogen generation unit (200) may be 600 to 900°C. More specifically, the internal average temperature of the hydrogen generation unit (200) may be 600 to 850°C. The internal average temperature of the hydrogen generation unit (200) may be 600 to 700°C. The internal average temperature of the hydrogen generation unit (200) may be determined by the reduced iron supplied to the hydrogen generation unit (200). Since the reduced iron has high thermal conductivity, the interior of the hydrogen generation unit (200) may be heated by the sensible heat of the reduced iron. As a non-limiting example, the internal average temperature of the hydrogen generation unit (200) may be lower than the temperature of the reduced iron supplied to the hydrogen generation unit (200). More specifically, the internal average temperature of the hydrogen generation unit (200) may be substantially the same as the temperature of the reduced iron supplied to the hydrogen generation unit (200).

[0053] According to exemplary embodiments, the temperature of the reduced iron supplied to the hydrogen generation unit (200) may be 600 to 1000°C. More specifically, the temperature of the reduced iron supplied to the hydrogen generation unit (200) may be 600 to 900°C. The temperature of the reduced iron supplied to the hydrogen generation unit (200) may be 650 to 900°C. The temperature of the reduced iron supplied to the hydrogen generation unit (200) may be 650 to 850°C.

[0054] If the temperature of the reduced iron supplied to the hydrogen generation unit (200) is less than 600°C, the heat energy required for the ammonia decomposition reaction may not be sufficiently supplied, which may lower the ammonia decomposition efficiency. If the temperature of the reduced iron supplied to the hydrogen generation unit (200) exceeds 1000°C, the ammonia decomposition rate may not increase significantly compared to the excessive heat energy supplied to the hydrogen generation unit (200), which may lower the heat supply efficiency for ammonia decomposition. In addition, at a temperature higher than the Curie temperature (1043°C) of iron, the structure and properties of the iron may change, which may make quality control difficult in subsequent processes.

[0055] According to exemplary embodiments, the size of the reduced iron may be 0.5 to 2 mm. More specifically, the size of the reduced iron may be 0.5 to 1 mm. The size of the reduced iron may be 1 to 2 mm. The size of the reduced iron was measured based on the long axis of the reduced iron.

[0056] When the size of the reduced iron exceeds 2 mm, the contact efficiency between ammonia and reduced iron decreases, which may result in poor ammonia decomposition efficiency. Therefore, reducing the size of the reduced iron can improve ammonia decomposition efficiency. However, when the size of the reduced iron is less than 0.5 mm, the specific surface area of ​​the reduced iron increases excessively, which may lead to surface oxidation or nitrification. Furthermore, small particle sizes can hinder gas flow within the reactor, resulting in differential pressure, which may reduce ammonia decomposition efficiency.

[0057] According to exemplary embodiments, the ammonia is 3000 to 9000 h -1 The ammonia can be supplied to the hydrogen generating unit (200) to contact the reduced iron at a space velocity of 3000 to 8000 h -1 The ammonia can be supplied to the hydrogen generating unit (200) to contact the reduced iron at a space velocity of 3000 to 6000 h -1 It can be supplied to the hydrogen generation unit (200) to contact the reduced iron at a space velocity of .

[0058] The space velocity of ammonia is 9000h -1 If the space velocity of ammonia exceeds 3000 h, the volume flow rate of ammonia to be processed per unit volume of reduced iron filled in the hydrogen generation unit (200) may become excessively high. In this case, the ammonia decomposition efficiency (conversion rate) may be excessively reduced. The lower the space velocity of ammonia, the better the ammonia decomposition efficiency. However, if the space velocity of ammonia is 3000 h -1 If less, excessively high amounts of reduced iron may be required per unit volume of ammonia.

[0059] Ammonia can be provided to the hydrogen generation unit (200) in the form of ammonia gas. The composition of the ammonia gas is not particularly limited as long as it can produce hydrogen by causing an ammonia decomposition reaction on a reduced iron catalyst.

[0060] When reduced iron is used as a catalyst for the ammonia decomposition reaction, the reduced iron is nitrided and Fe is formed on the surface of the reduced iron. x N y Iron nitride of the form Fe can be formed x N y Iron nitride in the form of iron is an impurity that can be produced by nitriding reduced iron in an ammonia decomposition reaction. As a non-limiting example, iron nitride may be one or more of Fe4N, Fe3N, and Fe2N. The quality of products produced in subsequent processes using reduced iron as a raw material may be deteriorated due to iron nitride. Therefore, in order to recycle the reduced iron used in the hydrogen generation unit (200) in the steelmaking process, it is necessary to remove iron nitride.

[0061] According to exemplary embodiments, the regeneration unit (300) may be configured to receive reduced iron from the hydrogen generation unit (200) and regenerate the reduced iron by reducing the reduced iron in a hydrogen gas atmosphere. This allows the iron nitride formed on the reduced iron to be removed and recycled. The regenerated reduced iron may be circulated to the hydrogen generation unit (200). The regenerated reduced iron may be provided as a raw material for steel sheets to an electric furnace process in a steelmaking process or a steelmaking process.

[0062] According to exemplary embodiments, the reduction treatment of the reduced iron may be performed at a temperature higher than the supply temperature of the reduced iron supplied to the regeneration unit (300). That is, the reduction treatment of the reduced iron may be performed at a temperature that is substantially the same as the supply temperature of the reduced iron supplied to the regeneration unit (300) or higher than the supply temperature of the reduced iron supplied to the regeneration unit (300). As a non-limiting example, the reduced iron supplied to the regeneration unit (300) may be reduced in a hydrogen gas atmosphere of 600°C or higher. The reduced iron supplied to the regeneration unit (300) may be reduced in a hydrogen gas atmosphere of 700°C or higher. The reduced iron supplied to the regeneration unit (300) may be reduced in a hydrogen gas atmosphere of 800°C or higher. The reduced iron supplied to the regeneration unit (300) may be reduced in a hydrogen gas atmosphere of 1,000°C or lower. If the reduction treatment temperature of reduced iron exceeds 1,000°C, the structure and properties of the iron may change. Consequently, quality control of the product may become difficult when using reduced iron provided from the regeneration unit (300). If the reduction treatment temperature of the reduced iron is lower than the supply temperature of the reduced iron to the regeneration unit (300), the regeneration efficiency of the reduced iron may be poor.

[0063] The hydrogen gas used for the reduction treatment may be derived from the hydrogen generation unit (200). According to exemplary embodiments, the hydrogen production system (10) may be configured such that some of the hydrogen generated in the hydrogen generation unit (200) is provided to the regeneration unit (300). For this purpose, the hydrogen generation unit (200) and the regeneration unit (300) may be fluidly connected to each other. More specifically, the upper portion of the hydrogen generation unit (200) where hydrogen is captured and the regeneration unit (300) may be connected to each other by a fluid connection means such as an air duct. In this way, the hydrogen production system (10) can independently supply an atmospheric gas for the reduction treatment of reduced iron within the system, thereby improving the reduction treatment efficiency of the hydrogen production system (10). The proportion of the hydrogen generated in the hydrogen generation unit (200) and provided to the regeneration unit (300) is not particularly limited as long as the regeneration unit (300) can perform the reduction treatment of reduced iron.

[0064] [How to produce hydrogen]

[0065] According to exemplary embodiments, a method of producing hydrogen may include a reduced iron preparation step, a hydrogen production step, and a reduced iron regeneration step.

[0066]

[0067] The step of preparing reduced iron may be to reduce iron ore by using any one of a fluidized bed reactor, a shaft furnace, or a combination thereof. Since the fluidized bed reactor and the shaft furnace reduce iron ore in a high-temperature environment, the reduced iron, which is a product of the iron ore reduction process, may contain heat energy corresponding to the high temperature. Since this reduced iron can be utilized as a catalyst for the ammonia decomposition reaction, the energy efficiency of the hydrogen production process can be improved.

[0068] According to exemplary embodiments, the reducing gas may be any one of hydrogen, carbon monoxide, and combinations thereof.

[0069] The hydrogen production step may involve providing ammonia to reduced iron to produce hydrogen through an ammonia decomposition reaction. The temperature of the reduced iron may be 600 to 1000°C. The size of the reduced iron may be 0.5 to 2 mm. Ammonia may be produced at a temperature of 3000 to 9000 h. -1 It can be provided to contact the reduced iron at a space velocity of . As a result, ammonia can be thermally decomposed to produce hydrogen. The produced hydrogen can be separated and purified by any one of membrane separation, pressure swing adsorption (PSA), thermal swing adsorption (TSA), vacuum swing adsorption (VSA), and a combination thereof. More specifically, the produced hydrogen can be separated and purified by pressure swing adsorption (PSA).

[0070] The reduced iron regeneration step may be to reduce the reduced iron by providing hydrogen gas to the reduced iron after the ammonia decomposition reaction. As a result, Fe generated on the surface of the reduced iron during the ammonia decomposition process x N y Reduced iron can be regenerated by removing iron nitride in the form of reduced iron. The regenerated reduced iron can be recycled as a catalyst for ammonia decomposition. Alternatively, it can be supplied to steelmaking processes and used as a raw material for steel (steel plate).

[0071] The reduction treatment of reduced iron may be performed at a temperature equal to or higher than the temperature of the reduced iron immediately after the ammonia decomposition reaction. According to exemplary embodiments, the reduction treatment of reduced iron may be performed at a temperature of 600°C or higher.

[0072] In the reduced iron regeneration step, the hydrogen gas used as the atmospheric gas for the reduction process can utilize the hydrogen generated in the hydrogen generation step. That is, some of the hydrogen produced by the ammonia decomposition reaction can be provided to the reduced iron reduction process step.

[0073] In addition, matters substantially overlapping with the hydrogen production system described above can be equally applied to the present hydrogen production method, and thus a detailed description thereof is omitted.

[0074] Hereinafter, embodiments of the present invention will be described in detail so that those skilled in the art can easily implement them. However, the present invention may be implemented in various different forms and is not limited to the embodiments described herein.

[0075] Test Example 1: Confirmation of ammonia decomposition efficiency by reduced iron size

[0076] The ammonia decomposition efficiency was confirmed by supplying reduced iron and ammonia under the conditions shown in Table 1 below to a reactor in which the internal average temperature was substantially the same as the reduced iron temperature.

[0077] Ammonia decomposition efficiency was confirmed by measuring the decomposed ammonia using a mass spectrometer while injecting ammonia under the respective reduced iron temperature conditions for the examples and each comparative example. The measurements were compared under these conditions. The ammonia decomposition reaction pressure conditions were all controlled to the same value of 7 barg.

[0078] ClassificationReduced iron temperature (℃)Reduced iron size (mm)Ammonia decomposition efficiency (%)Example 1800 1~291.5Comparative example 1700 2.8~3.443.1Comparative example 2700 3.4~4.037.9Comparative example 3800 2.8~3.483.0Comparative example 4800 3.4~4.077.8

[0079] Referring to Table 1, the ammonia decomposition efficiency of Example 1, in which the size of the reduced iron was small, was the highest. However, the ammonia decomposition efficiency of Comparative Examples 1 to 4, in which the size of the reduced iron was relatively large, was relatively inferior.

[0080] Test Example 2: Confirmation of ammonia decomposition efficiency by ammonia space velocity

[0081] Ammonia decomposition efficiency was confirmed by supplying reduced iron and ammonia to a fluidized bed reactor with an average internal temperature of 700°C under the conditions shown in Table 2 below. In addition, the temperature of the reduced iron was controlled to approximately 700°C. The internal pressure of the fluidized bed reactor was controlled to 7 barg.

[0082] The ammonia decomposition efficiency was measured at the same reduced iron size as in Example 1 described above, and the reaction temperature was controlled to 700°C, and the ammonia decomposition rate performance according to space velocity was measured and confirmed.

[0083] Separation space velocity (h) -1 ) Ammonia decomposition efficiency (%) Example 2500090.7 Comparative example 51000069.4 Comparative example 62000059.7 Comparative example 74000050.1

[0084] Referring to Table 2, the ammonia decomposition efficiency of Example 2, in which the space velocity satisfies the range suggested by the present invention, was the best. However, in the case of Comparative Examples 5 to 7, it was confirmed that the ammonia decomposition efficiency rapidly decreased beyond the range suggested by the present invention.

[0085] Test Example 3: Confirmation of Regeneration of Reduced Iron

[0086] The formation of iron nitride was confirmed for the reduced iron before the ammonia decomposition reaction, the reduced iron after the ammonia decomposition reaction, and the reduced iron after the reduction treatment, and the results are shown in Table 3 below. The reduced iron before the ammonia decomposition reaction was the reduced iron produced in the reduced iron production section. As the reduced iron after the ammonia decomposition reaction, the reduced iron obtained by contacting the reduced iron before the ammonia decomposition reaction with ammonia in a hydrogen production section at about 600°C was used. As the reduced iron after the reduction treatment, the reduced iron obtained by reducing the reduced iron after the ammonia decomposition reaction in a hydrogen gas atmosphere at about 800°C was used.

[0087] Iron nitride was measured using XRD analysis, and the intensity (arbitray unit, au) for each crystal was quantified and analyzed for comparison.

[0088] Distinction Fe3N+Fe2N(au)Fe4N(au)Reduced iron before decomposition reaction00Reduced iron after decomposition reaction31758Reduced iron after reduction treatment012

[0089] Referring to Table 3, it was confirmed that iron nitride was formed on the surface of reduced iron by the ammonia decomposition reaction, but that the iron nitride could be effectively removed by reduction treatment in a hydrogen gas atmosphere.

[0090] The present invention has been described in more detail through drawings and examples. However, the configurations described in the drawings or examples described in this specification are merely embodiments of the present invention and do not represent all of the technical ideas of the present invention. Therefore, it should be understood that various equivalents and modified examples may exist as of the time of this application.

[0091] [Explanation of symbols]

[0092] 10: Hydrogen production system

[0093] 100: Reduced iron production unit

[0094] 200: Hydrogen generation unit

[0095] 300: Regeneration Department

Claims

1. A hydrogen generating unit configured to receive reduced iron from a reduced iron generating unit configured to reduce iron ore in a reducing gas atmosphere to produce reduced iron, and to contact the reduced iron with ammonia to produce hydrogen from the ammonia; and A hydrogen production system including a regeneration unit configured to receive the reduced iron from the hydrogen generation unit and regenerate the reduced iron by reducing the reduced iron in a hydrogen gas atmosphere.

2. In paragraph 1, A hydrogen production system wherein the reducing gas comprises one of hydrogen, carbon monoxide, and a combination thereof.

3. In paragraph 1, The above-mentioned reduced iron generating unit is a hydrogen production system including any one of a fluidized bed reduction reactor, a shaft furnace, and a combination thereof.

4. In paragraph 1, The above ammonia is 3000~9000 h -1 A hydrogen production system supplied to the hydrogen generation unit so as to contact the reduced iron at a space velocity of .

5. In paragraph 1, A hydrogen production system in which the temperature of reduced iron supplied to the above hydrogen generation unit is 600 to 1000°C.

6. In paragraph 1, A hydrogen production system in which the size of the above reduced iron is 0.5 to 2 mm.

7. In paragraph 1, A hydrogen production system in which the reduction treatment of the reduced iron is performed at a temperature equal to or higher than the supply temperature of the reduced iron supplied to the regeneration unit.

8. In paragraph 7, A hydrogen production system in which the reduced iron supplied to the above-mentioned regeneration unit is subjected to reduction treatment in a hydrogen gas atmosphere at a temperature of 600°C or higher.

9. In paragraph 1, The above hydrogen production system, A hydrogen production system configured such that some of the hydrogen generated in the hydrogen generation unit is provided to the regeneration unit.

10. A step of preparing reduced iron by reducing iron ore using any one of a fluidized bed reactor, a shaft reactor, and a combination thereof; A step of providing ammonia to the above reduced iron to produce hydrogen through an ammonia decomposition reaction; and A method for producing hydrogen, comprising a step of providing hydrogen gas to the reduced iron to perform reduction treatment on the reduced iron after the ammonia decomposition reaction.

11. In paragraph 10, A method for producing hydrogen in which some of the hydrogen produced by the above ammonia decomposition reaction is provided to the reduction treatment step of the reduced iron.

12. In paragraph 10, In the step of producing the above hydrogen, A method for producing hydrogen in which the temperature of the above reduced iron is 600 to 1000°C.

13. In paragraph 10, A method for producing hydrogen wherein the size of the reduced iron is 0.5 to 2 mm.

14. In paragraph 10, A method for producing hydrogen, wherein the reduction treatment of the reduced iron is performed at a temperature equal to or higher than the temperature of the reduced iron immediately after the ammonia decomposition reaction.

15. In paragraph 14, A method for producing hydrogen, wherein the reduction treatment of the above reduced iron is performed at a temperature of 600°C or higher.

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