Hydrogen production system and hydrogen production method

Abstract

According to exemplary embodiments of the present invention, a hydrogen production system and a hydrogen production method can be provided that ensures improved resource efficiency by recycling by-products generated in a hydrogen production process.

Description

Hydrogen production system and hydrogen production method

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

[0002] Although hydrogen is emerging as a major energy source for the 21st century alongside natural gas, technological development and demonstration are required due to a lack of economic viability.

[0003] In terms of production direction, hydrogen can be classified into Gray hydrogen technology, which utilizes natural gas reforming or byproduct hydrogen generated during steelmaking or petrochemical processes as an energy source; Blue hydrogen technology, which includes techniques for capturing and storing CO2 produced during these processes; and Green hydrogen technology, which produces hydrogen through the electrolysis of water using renewable energy sources. Recently, Turquoise hydrogen production technology, which produces carbon and hydrogen by thermally decomposing methane-containing gases at high temperatures, has been attracting attention.

[0004] Blue-green hydrogen production technology minimizes the generation of carbon dioxide, a greenhouse gas, and can be utilized in various fields because it emits carbon in a solid form. Therefore, there is a need for technological development to efficiently produce blue-green hydrogen.

[0005] (Patent Document 1) Korean Published Patent Application No. 10-2024-0062164

[0006] The problem that the technical concept of the present invention aims to solve is to provide a hydrogen production system and a hydrogen production method with improved resource efficiency.

[0007] The problems of the present invention are not limited to those described above. A person skilled in the art to which the present invention pertains will have no difficulty understanding additional problems of the present invention from the overall details of the specification.

[0008] According to exemplary embodiments for solving the problem of the present invention, a hydrogen production system is provided. The hydrogen production system comprises: a first reactor configured to react a first raw gas containing methane with a first reduced iron to provide a first carbon material and hydrogen; and a second reactor configured to react a second raw gas containing a first carbon dioxide with the first carbon material to provide carbon monoxide.

[0009] It may further include a third reactor configured to react the carbon monoxide with water to provide hydrogen and a second carbon dioxide.

[0010] The above second carbon dioxide can be circulated to the above second reactor.

[0011] The thermal energy generated in the third reactor can be circulated to the second reactor.

[0012] The thermal energy generated in the third reactor can be circulated to the first reactor.

[0013] The temperature of the first reduced iron above may be 500 to 1100°C or lower.

[0014] The above first raw material gas may not contain oxygen.

[0015] The temperature of the second reactor above may be 800 to 1000°C.

[0016] The space velocity (h) of the second source gas mentioned above -1 ) is 1,000~30,000h -1 It could be.

[0017] The above-mentioned first reduced iron may be derived from an ironmaking reduction furnace.

[0018]

[0019] According to other exemplary embodiments, a method for producing hydrogen is provided. The method for producing hydrogen comprises: a first reaction step of reacting a first raw gas containing methane with a first reduced iron to provide a first carbon material and hydrogen; and a second reaction step of reacting a second raw gas containing a first carbon dioxide with the first carbon material to provide carbon monoxide.

[0020] The first reaction step and the second reaction step may be performed in a single reactor.

[0021] After the second reaction step above, the differential pressure inside the reactor may be less than 2 barg.

[0022] According to exemplary embodiments of the present invention, a hydrogen production system and a hydrogen production method with improved resource efficiency can be provided by recycling by-products generated during the hydrogen production process.

[0023] In addition, by recycling the energy generated during the resource recycling process, it is possible to provide a hydrogen production system and a hydrogen production method with improved energy efficiency.

[0024] The various and beneficial advantages and effects of the present invention are not limited to those described above and will be more easily understood in the process of explaining specific embodiments of the present invention.

[0025] FIG. 1 is a drawing for illustrating a hydrogen production system according to exemplary embodiments.

[0026] FIG. 2 is a drawing for illustrating a hydrogen production system according to other exemplary embodiments.

[0027] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the attached drawings. Prior to this, terms and words used in this specification and claims should not be interpreted as being limited to their ordinary or dictionary meanings. Instead, based on the principle that the inventor can appropriately define the concepts of terms to best describe his invention, they should be interpreted in a meaning and concept consistent with the technical spirit of the present invention.

[0028] In the following descriptions with reference to the drawings, identical or corresponding components are assigned the same reference numerals, and redundant descriptions thereof will be omitted.

[0029] In the following embodiments, the terms first, second, etc. are used not in a limiting sense, but for the purpose of distinguishing one component from another component.

[0030] In the following embodiments, the singular expression includes the plural expression unless the context clearly indicates otherwise.

[0031] In the following embodiments, terms such as "include" or "have" mean that the features or components described in the specification are present, and do not preclude the possibility that one or more other features or components may be added.

[0032] In the drawings, the size of components may be exaggerated or reduced for convenience of explanation. For example, the size and thickness of each component shown in the drawings are depicted arbitrarily for convenience of explanation, so the present invention is not necessarily limited to what is illustrated.

[0033] Where an embodiment can be implemented differently, a specific process sequence may be performed differently from the order described. For example, two processes described consecutively may be performed substantially simultaneously or proceed in the reverse order of the description.

[0034] In addition, in describing the present invention, if it is determined that a detailed description of related known components or functions may obscure the essence of the invention, such detailed description is omitted.

[0035] The present invention will be described in detail below through each embodiment. It should be noted that each embodiment described in this specification is not limited to a single embodiment but may also be combined with other embodiments. Accordingly, the citation of claims in the patent claims is merely an example of an embodiment, and the technical concept of the present invention should not be interpreted as being limited only to a combination with the cited claims; rather, combinations with various claims are also included within the scope of the technical concept of the present invention.

[0036] The present invention will be described in detail below through examples. However, it should be noted that the following examples are intended merely to illustrate and embody the present invention and are not intended to limit the scope of the present invention. This is because the scope of the present invention is determined by the matters described in the patent claims and matters reasonably inferred therefrom.

[0037] [Hydrogen Production System]

[0038] FIG. 1 is a drawing for illustrating a hydrogen production system (10) according to exemplary embodiments.

[0039] Referring to FIG. 1, the hydrogen production system (10) includes a first reactor (100) and a second reactor (200).

[0040] The first reactor (100) is configured to react a first raw gas containing methane with a first reduced iron to provide a first carbon material and hydrogen. In this way, the hydrogen production system (10) can produce hydrogen from methane using reduced iron, thereby providing a so-called blue-green hydrogen production technology.

[0041] The structure of the first reactor (100) is not particularly limited, provided that it includes a space within which the first raw gas and the first reduced iron can sufficiently come into contact to produce hydrogen. As a non-limiting example, the first reactor (100) may be any one of a fluidized bed reactor, a vertical reactor, a rotary kiln reactor, and a combination thereof. In a fluidized bed reactor, a fluidized bed of the first reduced iron is formed within, and a reaction may occur by the contact between the fluidized bed of the first reduced iron and the first raw gas. In a vertical reactor, a reaction may occur by the first raw gas flowing from bottom to top and the first reduced iron falling from a stationary bed or from top to bottom coming into contact with each other. In a rotary kiln reactor, a reaction may occur by the first reduced iron and the first raw gas rotating and mixing inside an inclined rotating drum.

[0042] Hydrogen can be generated in the first reactor (100) through the following reaction equation 1.

[0043] [Reaction Equation 1]

[0044] CH4→C+2H2; △H=74.9kJ / mol

[0045] The first raw gas is a raw gas for producing blue-green hydrogen and is a gas mainly containing methane. The methane content of the first raw gas may be 80 to 100% by volume, but the present invention is not limited thereto. As a non-limiting example, the first raw gas may consist of methane. The remainder of the first raw gas may be any one of a reducing gas, an inert gas, or a mixture thereof in order to suppress side reactions between the first reduced iron and the first raw gas. The reducing gas may be hydrogen. The inert gas may be nitrogen.

[0046] According to exemplary embodiments, the first source gas may substantially not contain oxygen. If the first source gas contains oxygen, it may react with carbon during the methane decomposition process to produce carbon dioxide.

[0047] Iron (I) is used as a catalyst for hydrogen production. Generally, precious metals such as ruthenium (Ru) or nickel (Ni) have been used as catalysts for hydrogen production. These materials exhibit high catalytic activity. However, components such as precious metals and nickel are expensive and have limited reserves. Furthermore, the mining and extraction processes generate large amounts of carbon dioxide, resulting in a relatively high Global Warming Potential (GWP). In contrast, iron (Fe) is cheaper than precious metal catalysts, has abundant reserves, and possesses a low GWP. Therefore, there is a need to utilize iron as a catalyst for hydrogen production.

[0048] The temperature of the first reduced iron may be 500 to 1100°C or lower. More specifically, the temperature of the first reduced iron may be 750 to 1000°C. The temperature of the first reduced iron may be 750 to 900°C. In this way, the hydrogen production system (10) can supply the thermal energy required for hydrogen production by using the first reduced iron at a high temperature. In this case, there is no need to consume excessive energy to heat the first reduced iron to a predetermined target temperature in the first reactor (100). That is, thermal energy for hydrogen production can be secured by directly using the first reduced iron at a high temperature or by supplying only a small amount of energy. As a result, the energy efficiency of the hydrogen production system (10) can be increased.

[0049] If the temperature of the first reduced iron is less than 500℃, the hydrogen production efficiency is low. If the temperature of the first reduced iron exceeds 1100℃, it may cause an overload of the equipment and impair stability.

[0050] The first reduced iron may be supplied to the first reactor (100) in an externally heated state. According to exemplary embodiments, the first reduced iron may be derived from a steelmaking reduction furnace. The reduction of iron ore is performed at a high temperature. Thus, by linking the steelmaking process with the hydrogen production system (10), high-temperature reduced iron can be efficiently supplied.

[0051] The first reduced iron may be iron reduced to 40 to 100% relative to iron ore, but the present invention is not limited to this.

[0052] As a steelmaking reduction furnace, a rotary kiln, a shaft furnace, or a fluidized bed reduction furnace, a fixed-bed reduction furnace, or a moving-bed reduction furnace may be used. The first reduced iron according to exemplary embodiments of the present invention may be reduced through a shaft furnace, a fluidized bed reduction furnace, or any one of these combined forms. More preferably, the first reduced iron may be reduced through a fluidized bed reduction furnace. In a fluidized bed reduction furnace, the raw material is suspended in the air by a reducing gas, and the raw material and the reducing gas are mixed together as if they were liquids, thereby causing a reduction reaction. As a result, a sufficient contact area between the raw material and the reducing gas can be secured. In addition, physical impact applied to the raw material can be minimized, thereby ensuring the durability of the first reduced iron to be used as a catalyst, and fine particles of the first reduced iron can be dispersed, minimizing loss during the transport process of the first reduced iron.

[0053] The first carbon material refers to materials primarily containing carbon generated through the above-described reaction scheme 1. According to exemplary embodiments, the first carbon material may contain 60% or more carbon by weight. In addition, it may contain the remainder being iron (Fe) and unavoidable impurities. The iron may be derived from the first reduced iron, and in a high-temperature environment, some Fe may combine with carbon and be included in the first carbon material.

[0054] The second reactor (200) may be configured to react a second raw gas containing a first carbon dioxide with a first carbon material to provide carbon monoxide. As such, according to exemplary embodiments, carbon monoxide that can be used as a reducing gas can be produced by consuming carbon dioxide. This can contribute to reducing carbon dioxide and allows the first carbon material to be recycled, thereby increasing the energy and resource efficiency of the hydrogen production system (10). The reaction between carbon dioxide and the first carbon material in the second reactor (200) may follow the following reaction equation 2. At this time, the carbon dioxide conversion reaction may be catalyzed by the iron contained in the first carbon material and the first reduced iron transported together during the transport process of the first carbon material.

[0055] [Reaction Equation 2]

[0056] C + CO2 → 2CO; △H=175.5kJ / mol

[0057] The structure of the second reactor (200) is not particularly limited as long as it can provide a space for the second raw gas and the first carbon material to react. As a non-limiting example, the second reactor (200) may be any one of a fluidized bed reactor, a vertical reactor, a rotary kiln reactor, a fixed bed reactor, a moving bed reactor, and a combination thereof.

[0058] According to exemplary embodiments, the temperature of the second reactor (200) may be 800 to 1000°C. If the temperature of the second reactor (200) is excessively low, the conversion rate of carbon dioxide is low, resulting in a large amount of unreacted carbon dioxide and potentially generating greenhouse gases. While it is preferable for the temperature of the second reactor (200) to be higher, it may be 1000°C or lower for the sake of equipment stability.

[0059] According to exemplary embodiments, the second reactor (200) can be controlled so that the differential pressure within the reactor is less than 2 barg. The differential pressure of the second reactor (200) refers to the pressure difference between the inlet and the outlet relative to the direction of gas flow within the second reactor (200). If the differential pressure within the second reactor (200) is high, it can reduce equipment stability and reduce reaction efficiency. Therefore, it is important to control the differential pressure of the second reactor (200) to be low. According to exemplary embodiments, by consuming the first carbon material to produce carbon monoxide, the volume occupied by the solid material within the second reactor (200) can be reduced. Consequently, pressure loss or resistance that may occur as the solid material obstructs the gas flow within the second reactor (200) can be reduced.

[0060] According to exemplary embodiments, the first reactor (100) and the second reactor (200) may be reactors connected sequentially. In this case, the first carbon material may be transferred from the first reactor (100) to the second reactor (200).

[0061] According to other exemplary embodiments, the second reactor (200) may be substantially the same as the first reactor (100). In this case, when the methane reaction in the first reactor (100) is completed, the second raw gas can be supplied to the reactor to be used as the second reactor (200). That is, the first reactor (100) and the second reactor (200) can be distinguished based on the supplied raw gas and reaction products. This minimizes damage to the first reduced iron that may occur during the transfer process. Additionally, after the first carbon material is consumed and the differential pressure within the reactor decreases, hydrogen can be continuously produced by supplying the first raw gas again. Furthermore, not only the first carbon material but also the first reduced iron can be utilized as a catalyst for the carbon dioxide conversion reaction, thereby increasing the carbon dioxide conversion efficiency.

[0062] The second raw gas is a gas that mainly contains carbon dioxide and is a raw gas for the production of carbon monoxide. If the second raw gas mainly contains carbon dioxide, its composition is not particularly limited, but as a non-limiting example, it may contain 50 to 100% carbon dioxide by volume. In addition, the remainder may contain unavoidable impurities that may be included in the carbon dioxide production and transport process.

[0063] According to exemplary embodiments, the space velocity (h) of the second source gas -1 ) is 1,000~30,000h -1 It may be. If the space velocity of the second source gas is excessively high, the carbon dioxide conversion efficiency may decrease. If the space velocity of the second source gas is excessively low, the production of carbon monoxide per hour may decrease.

[0064] FIG. 2 is a drawing for illustrating a hydrogen production system (20) according to other exemplary embodiments.

[0065] Referring to FIG. 2, the hydrogen production system (20) may further include a third reactor (300) configured to react carbon monoxide with water to provide hydrogen and a second carbon dioxide. In this way, the hydrogen production system (20) can produce hydrogen using the produced carbon monoxide, thereby further increasing the hydrogen production efficiency.

[0066] The hydrogen production reaction in the third reactor (300) can follow a water-gas shift reaction as shown in reaction equation 3 below.

[0067] [Reaction Equation 3]

[0068] CO + H2O → H2+ CO2; △H=-41.2kJ / mol

[0069] According to exemplary embodiments, the second carbon dioxide produced in the third reactor (300) can be circulated to the second reactor (200). As a result, the hydrogen production system (20) can produce the carbon dioxide required for carbon monoxide production on its own. Additionally, the carbon dioxide generated during the hydrogen production process can be consumed to reduce the carbon dioxide generated during the hydrogen production process.

[0070] According to exemplary embodiments, the thermal energy generated in the third reactor (300) can be circulated to the first reactor (100). According to exemplary embodiments, the thermal energy generated in the third reactor (300) can be circulated to the second reactor (200). Referring to reaction equation 3, the hydrogen production reaction in the third reactor (300) is an exothermic reaction, and thermal energy is generated during the hydrogen production process. By circulating this thermal energy to a reactor that consumes thermal energy within the hydrogen production system (20), the energy efficiency of the hydrogen production system (20) can be increased. The means of transferring thermal energy from the third reactor (300) is not particularly limited, but as a non-limiting example, a heat exchanger having steam and a heat exchange pipe may be used. In this case, the steam may exchange heat with the first raw gas or the second raw gas.

[0071] [Hydrogen Production Methods]

[0072] According to exemplary embodiments, a hydrogen production method comprises: a first reaction step of reacting a first raw gas containing methane with a first reduced iron to provide a first carbon material and hydrogen; and a second reaction step of reacting a second raw gas containing a first carbon dioxide with the first carbon material to provide carbon monoxide.

[0073] According to exemplary embodiments, the first reaction step and the second reaction step can be performed in a single reactor. This minimizes the loss of the first carbon material that may occur during the process of transporting the first carbon material.

[0074] According to exemplary embodiments, after the second reaction step, the differential pressure within the reactor may be less than 2 barg. As a result, a constant hydrogen production efficiency can be secured even when performing continuous hydrogen production.

[0075] According to exemplary embodiments, the temperature of the first reduced iron may be 500 to 1100°C or lower. This allows for the supply of thermal energy required to produce hydrogen in the first reaction step.

[0076] According to exemplary embodiments, the first reduced iron may be derived from an ironmaking reduction furnace.

[0077] According to exemplary embodiments, the first source gas may not contain oxygen. As a result, the amount of carbon dioxide generated can be minimized.

[0078] According to exemplary embodiments, the second reaction step may be performed at 800 to 1000°C. If the second reaction step is excessively low, the conversion rate of carbon dioxide may be reduced.

[0079] According to exemplary embodiments, the space velocity (h) of the second source gas -1 ) is 1,000~30,000h -1 It may be. If the space velocity of the second source gas deviates from the range described above, the conversion efficiency of carbon dioxide may decrease.

[0080] According to exemplary embodiments, the hydrogen production method may further include a third reaction step in which carbon monoxide generated in a second reaction step is reacted with water to provide hydrogen and carbon dioxide. In this case, the thermal energy generated in the third reaction step may be circulated to the first reaction step or the second reaction step. As a result, additional hydrogen can be produced, and the energy efficiency of the hydrogen production method can be increased.

[0081] [Test Example]

[0082] Test Example 1: Carbon Dioxide Conversion Rate Experiment

[0083] Hydrogen was produced by continuously supplying methane to a reactor receiving reduced iron derived from the steelmaking process. Subsequently, when the differential pressure of the reactor exceeded approximately 2 barg, the supply of methane was stopped and carbon dioxide was supplied to the reactor. At this time, the reactor temperature was controlled at approximately 900°C, and the space velocity of carbon dioxide was approximately 4000 h -1 It was controlled by.

[0084] Afterwards, the purity of carbon monoxide collected at the downstream end of the reactor and the conversion rate of carbon dioxide are shown in Table 1 below.

[0085] Separation Reactor Outlet CO Purity Carbon Dioxide Conversion Rate (%)(%) 95 90.2

[0086] Referring to Table 1, it was confirmed that the hydrogen production system according to exemplary embodiments can produce hydrogen through a methane decomposition reaction and, at the same time, contribute to reducing carbon dioxide by utilizing solid carbon, which is a reaction byproduct.

[0087] Test Example 2: Verification of hydrogen production efficiency of a hydrogen production system

[0088] The hydrogen production efficiency of the hydrogen production system was verified through the calculation of the material balance equation related to the hydrogen production system according to exemplary embodiments.

[0089] The conversion rate in each reactor was assumed to be 90%. The material balance of the source gas and product gas carrying out the reaction in each reactor was assumed as shown in Table 1 below.

[0090] Classification Reactor 1 Reactor 2 Reactor 3 input output input output input output Methane (1st feedstock gas) Hydrogen Carbon (1st carbon material) Carbon (1st carbon material) Carbon dioxide (1st carbon dioxide) Carbon monoxide Carbon monoxide Water Hydrogen Carbon dioxide (2nd carbon dioxide) Molar Flow Rate (mol / h) 100 180 90 90 100 180 180 180 162 162 Remaining Amount (mol / h) 10---10-18 18--

[0091] Referring to Table 1, it was confirmed that carbon monoxide and additional hydrogen can be produced using the reaction byproduct generated through the methane decomposition reaction.

[0092] Although the invention has been described with reference to the above embodiments, those skilled in the art will understand that various modifications and changes can be made to the invention without departing from the spirit and scope of the invention as described in the following claims.

Claims

1. A first reactor configured to react a first raw material gas containing methane with a first reduced iron to provide a first carbon material and hydrogen; and A hydrogen production system comprising: a second reactor configured to react a second raw material gas containing a first carbon dioxide with the first carbon material to provide carbon monoxide.

2. In Paragraph 1, A hydrogen production system further comprising a third reactor configured to react the above carbon monoxide with water to provide hydrogen and a second carbon dioxide.

3. In Paragraph 2, A hydrogen production system that circulates the above-mentioned second carbon dioxide to the above-mentioned second reactor.

4. In Paragraph 2, A hydrogen production system that circulates thermal energy generated in the third reactor to the second reactor.

5. In Paragraph 2, A hydrogen production system that circulates thermal energy generated in the third reactor to the first reactor.

6. In Paragraph 1, A hydrogen production system in which the temperature of the first reduced iron is 500 to 1100°C or lower.

7. In Paragraph 1, The above first raw gas is a hydrogen production system that does not contain oxygen.

8. In Paragraph 1, A hydrogen production system in which the temperature of the second reactor is 800 to 1000°C.

9. In Paragraph 1, The space velocity (h) of the second source gas mentioned above -1 ) is 1,000~30,000h -1 Phosphorus hydrogen production system.

10. In Paragraph 1, The above-mentioned first reduced iron is a hydrogen production system derived from an ironmaking reduction furnace.

11. A first reaction step of reacting a first raw material gas containing methane with a first reduced iron to provide a first carbon material and hydrogen; and A method for producing hydrogen comprising: a second reaction step of reacting a second raw material gas containing a first carbon dioxide with the first carbon material to provide carbon monoxide.

12. In Paragraph 11, A method for producing hydrogen in which the first reaction step and the second reaction step are performed in a single reactor.

13. In Paragraph 11, A method for producing hydrogen in which the differential pressure inside the reactor is less than 2 barg after the second reaction step above.

Images