Ammonia decomposition reactor, hydrogen generation apparatus, and hydrogen generation method using the same

Abstract

To provide an ammonia decomposition reactor, a hydrogen production apparatus, and a hydrogen production method using the same, which have improved reaction reliability and energy efficiency. [Solution] The ammonia decomposition reactor comprises a first chamber and a second chamber, the operating temperature of the first chamber being 410°C or lower, the first chamber comprising at least one selected from the group consisting of carbon steel, low alloy steel, stainless steel, and nickel alloys, and the second chamber comprising a nickel alloy (N) satisfying the following formula 1. T ) can include [Formula 1] T≦15μm In the above formula 1, T is the nickel alloy (N T A cylindrical specimen with a cross-sectional diameter of 2 mm and a height of 200 mm was prepared, and when the cylindrical specimen was exposed to a gas stream containing 97.2 vol% NH3, 2.1 vol% H2, and 0.7 vol% N2, and a temperature environment of 500°C for 100 hours, it showed the maximum nitrided depth.

Description

[Technical Field]

[0001] The disclosures of this application relate to an ammonia decomposition reactor, a hydrogen production apparatus, and a hydrogen production method using the same. [Background technology]

[0002] In various industrial sectors, hydrocarbon fossil fuels such as coal and oil are used as energy sources. However, hydrocarbon fossil fuels are limited in quantity and face the problem of future depletion, as well as the problem of accelerating climate change and global warming by continuously emitting carbon during combustion.

[0003] Therefore, there is a growing global need for new, renewable, and environmentally friendly energy sources.

[0004] Hydrogen is attracting attention as an energy source that can achieve carbon neutrality because it has a high energy storage capacity per unit mass and does not emit carbon during combustion.

[0005] In recent years, research and development have been progressing on technologies for generating hydrogen. Ammonia is being used as a hydrogen source because it can be used as a carrier that can store and transport hydrogen at high density, does not emit carbon when decomposed, and can be decomposed into nitrogen and hydrogen only. [Overview of the project] [Problems that the invention aims to solve]

[0006] One objective of this disclosure is to provide an ammonia decomposition reactor with improved reaction reliability and energy efficiency.

[0007] One objective of this disclosure is to provide a hydrogen generation apparatus with improved reaction reliability and energy efficiency.

[0008] One objective of this disclosure is to provide a hydrogen production method that offers improved reaction reliability and energy efficiency.

Means for Solving the Problem

[0009] The ammonia decomposition reactor according to an embodiment of the present disclosure includes a first chamber into which a first gas stream containing ammonia flows, and a second chamber into which a second gas stream discharged from the first chamber and containing ammonia, nitrogen and hydrogen flows. The operating temperature of the first chamber is 410 °C or lower, and the first chamber includes at least one selected from the group consisting of carbon steel, low alloy steel, stainless steel, and nickel-based alloy. The second chamber can include a nickel-based alloy (N T ) that satisfies the following formula 1.

[0010] [Formula 1] T≦15μm

[0011] In Formula 1, T is the maximum value of the depth nitrided in the central axis direction from the side surface of the cylindrical test piece when the nickel-based alloy (N T ) is prepared as a cylindrical test piece with a cross-sectional diameter of 2 mm and a height of 200 mm, and the cylindrical test piece is exposed to a gas stream containing 97.2 vol% NH3, 2.1 vol% H2, and 0.7 vol% N2, and a temperature environment of 500 °C for 100 hours. The depth can be measured by SEM (Scanning Electron Microscopy) and EDS (Energy Dispersive X-ray Spectroscopy) analysis.

[0012] In some embodiments, in Formula 1, T≦13μm may also be satisfied.

[0013] In some embodiments, the first gas stream can contain ammonia at 90 vol% to 100 vol%.

[0014] In some embodiments, the operating temperature of the second chamber may exceed 410 °C.

[0015] In some embodiments, the operating temperature of the second chamber may be greater than 410°C to 800°C.

[0016] In some embodiments, the second chamber is made of the nickel alloy (N T ) may be composed of.

[0017] In some embodiments, the nickel alloy (N T ) may contain one or more alloys classified into any one of the groups selected from UNS N06601, UNS N06625, UNS N06690, UNS N07718, UNS N07792, and UNS N06002, based on the UNS (Unified Numbering System).

[0018] In some embodiments, the ammonia conversion rate in the first chamber may be 1.4% or higher, and the ammonia conversion rate in the second chamber may be 80% to 99.95%.

[0019] In some embodiments, at least one of the first chamber and the second chamber may include a catalyst-filled section packed with a catalyst.

[0020] In some embodiments, the first chamber and the second chamber each include a catalyst-filled section packed with a catalyst, and the first space velocity, which is the space velocity of the catalyst in the first chamber, can have operating conditions that are the same as or greater than the second space velocity, which is the space velocity of the catalyst in the second chamber.

[0021] In some embodiments, while the ammonia decomposition reaction is taking place in the first and second chambers, the ratio of the first space velocity of the catalyst in the first chamber to the second space velocity of the catalyst in the second chamber may be 1 to 25.

[0022] The hydrogen generation apparatus according to the embodiments of this disclosure may include the ammonia decomposition reactor described above.

[0023] A hydrogen production method according to an embodiment of the present disclosure comprises: introducing a first gas stream containing ammonia into a first chamber; partially decomposing the ammonia in the first chamber at a temperature of 410°C or less to produce hydrogen and nitrogen; introducing a second gas stream discharged from the first chamber and containing ammonia, nitrogen, and hydrogen into a second chamber; and partially decomposing the ammonia in the second chamber to produce hydrogen and nitrogen, wherein the first chamber comprises at least one selected from the group consisting of carbon steel, low alloy steel, stainless steel, and nickel alloys, and the second chamber comprises a nickel alloy (N) satisfying the following formula 1. T ) can include

[0024] [Formula 1] T ≤ 15 μm

[0025] In Equation 1, T is the nickel alloy (N T A cylindrical specimen with a cross-sectional diameter of 2 mm and a height of 200 mm is prepared. When the cylindrical specimen is exposed to a gas stream containing 97.2 volume% NH3, 2.1 volume% H2, and 0.7 volume% N2, and a temperature environment of 500°C for 100 hours, the maximum depth of nitridation from the side of the cylindrical specimen in the direction of the central axis is determined. This depth can be measured by SEM (Scanning Electron Microscopy) and EDS (Energy Dispersive X-ray Spectroscopy) analysis.

[0026] In some embodiments, T ≤ 13 μm may be used in Equation 1.

[0027] In some embodiments, the first gas stream may contain ammonia at a concentration of 90% to 100% by volume.

[0028] In some embodiments, the ammonia in the first chamber may be partially decomposed such that the ammonia conversion rate is 1.4% or higher, and the ammonia in the second chamber may be partially decomposed such that the ammonia conversion rate is 80% to 99.95%.

[0029] In some embodiments, the second chamber is made of the nickel alloy (N T ) may be composed of.

[0030] In some embodiments, the invention may further include filling at least one of the first chamber and the second chamber with a catalyst.

[0031] In some embodiments, the hydrogen production method further includes filling each of the first and second chambers with a catalyst, and the ammonia decomposition reaction in each of the first and second chambers can be carried out under operating conditions in which the first space velocity, which is the space velocity of the catalyst in the first chamber, is the same as or greater than the second space velocity, which is the space velocity of the catalyst in the second chamber.

[0032] In some embodiments, while the ammonia decomposition reaction is taking place in the first and second chambers, the ratio of the first space velocity of the catalyst in the first chamber to the second space velocity of the catalyst in the second chamber may be 1 to 25. [Effects of the Invention]

[0033] The ammonia decomposition reactor according to the embodiments of this disclosure can achieve improved corrosion resistance and energy efficiency.

[0034] The hydrogen generation apparatus according to the embodiments of this disclosure can maintain its initial performance characteristics for a long period of time.

[0035] The hydrogen production method according to the embodiments of this disclosure can provide improved reaction reliability and energy efficiency.

[0036] If corrosion increases on the internal surface of the reactor during the ammonia supply process, hydrogen production efficiency may decrease, or the flow rate and purity of the hydrogen produced may become non-uniform.

[0037] However, in the ammonia decomposition reactor according to the embodiments of this disclosure, the structural stability of the reactor is maintained, thereby ensuring the efficiency and / or reproducibility of the hydrogen production reaction, and as a result, hydrogen of uniform quality can be supplied more stably. [Brief explanation of the drawing]

[0038] [Figure 1] Figure 1 is a schematic diagram showing an ammonia decomposition reactor according to one embodiment of the present disclosure. [Figure 2] Figure 2 is a schematic block diagram showing a hydrogen generation apparatus according to one embodiment of the present disclosure. [Figure 3] Figure 3 is a schematic process flow diagram of a hydrogen production method according to one embodiment of the present disclosure. [Figure 4] Figure 4 is a graph showing the evaluation results of corrosion resistance based on operating temperature when the operating time of the first chamber in Example 1, Example 1-1, and Example 1-2 is set to 36 hours. [Figure 5] Figure 5 is a graph showing the evaluation results of corrosion resistance based on operating temperature, assuming an operating time of 100 hours for the first chamber in Examples 1, 1-1, and 1-2. [Figure 6] Figure 6 shows SEM (Scanning Electron Microscope) images of the cross-sections of nitrided test specimens after evaluating the corrosion resistance based on the operating time of the first chamber in Examples 1 to 5. [Figure 7] Figures 7a and 7b are SEM (Scanning Electron Microscope) images of the cross-sections of nitrided specimens after evaluating the corrosion resistance based on the operating time of the second chamber in Examples 1-5 and Comparative Examples 1-4. [Figure 8]Figure 8 is a graph showing the evaluation results of the corrosion rate for the first chamber in Examples 1 to 5. [Figure 9] Figure 9 is a graph showing the evaluation results of the corrosion rate for the second chamber in Example 1 and Comparative Examples 2 and 3. [Modes for carrying out the invention]

[0039] Hereinafter, exemplary embodiments of the present disclosure will be described in detail with reference to the drawings, so as to be easily implemented by a person ordinary skill in the art to which the present invention pertains. However, these embodiments are illustrative and not limiting to the present invention.

[0040] <Ammonia decomposition reactor> Figure 1 schematically shows an ammonia decomposition reactor according to one embodiment of the present disclosure.

[0041] An ammonia decomposition reactor 100 according to an embodiment of the present disclosure may include a first chamber 10 into which a first gas stream containing ammonia flows, and a second chamber 20 into which a second gas stream discharged from the first chamber 10 and containing ammonia, nitrogen, and hydrogen flows. The operating temperature of the first chamber 10 may be 410°C or lower.

[0042] In other words, the ammonia decomposition reactor 100 may include a first chamber 10 to which a first gas stream containing ammonia is supplied, and a second chamber 20 to which a second gas stream discharged from the first chamber 10 and containing ammonia, nitrogen, and hydrogen is supplied. The operating temperature of the first chamber 10 may be 410°C or lower.

[0043] The first chamber 10 includes at least one selected from the group consisting of carbon steel, low alloy steel, stainless steel, and nickel-based alloys, and the second chamber 20 includes a nickel-based alloy (N) satisfying the following formula 1. T ) can include

[0044] [Formula 1] T ≤ 15 μm

[0045] In Formula 1, T may be the maximum value of the depth nitrided in the central axis direction from the side surface of the nickel-based alloy (N T ) when prepared as a cylindrical test piece with a cross-sectional diameter of 2 mm and a height of 200 mm, and the cylindrical test piece is exposed to a gas stream containing 97.2 vol% NH3, 2.1 vol% H2, and 0.7 vol% N2 and a temperature environment of 500 °C for 100 hours. The depth can be measured by SEM (Scanning Electron Microscopy) and EDS (Energy Dispersive X-ray Spectroscopy) analysis.

[0046] Thereby, the ammonia decomposition reactor 100 can suppress or reduce internal corrosion.

[0047] In this specification, "nickel-based alloy" can be used in the sense of including all alloys mainly composed of nickel and added with one or more metal elements such as chromium (Cr), iron (Fe), molybdenum (Mo), cobalt (Co), aluminum (Al), titanium (Ti), tungsten (W).

[0048] Also, in this specification, an alloy satisfying Formula 1 is referred to as "nickel-based alloy (N T )" to distinguish it from the nickel-based alloy.

[0049] In the case of high-purity ammonia, the chamber may be rapidly corroded at a high temperature exceeding 410 °C.

[0050] In the ammonia decomposition reactor 100, by forming the second chamber 20, whose operating temperature can be controlled below 410 °C and, if necessary, above 410 °C, with the nickel-based alloy (N T ), overall nitridation can be effectively prevented or reduced.

[0051] When metals forming components such as chambers are exposed to high-temperature, high-purity ammonia, they can undergo a nitriding reaction with the ammonia, potentially forming nitride products from the surface to the interior of the metal. If these nitride products form inside the chamber, microscopic cracks may develop, reducing the flow characteristics of the gas stream and hindering reaction uniformity. This can ultimately lead to problems such as a shortened chamber replacement cycle and increased maintenance costs.

[0052] The ammonia decomposition reactor 100 ensures that even when high-purity ammonia comes into contact with the inner surface of the first chamber 10, the nitriding reaction on the surface is significantly reduced or not accelerated in a temperature environment of 410°C or lower.

[0053] The ammonia decomposition reactor 100 produces a nickel-based alloy (N) that satisfies formula 1 above. T On the internal surface of the second chamber 20, which includes the above, the nitriding reaction by ammonia can be suppressed or reduced even in high-temperature environments exceeding 410°C, thereby ensuring improved nitriding resistance.

[0054] For example, T, represented by equation 1, can be measured as follows.

[0055] The aforementioned nickel alloy (N T When a cylindrical specimen of ) is exposed to a gas stream containing 97.2 volume% NH3, 2.1 volume% H2, and 0.7 volume% N2, and a temperature environment of 500°C for 100 hours, a nitrided cylindrical specimen can be obtained.

[0056] As used herein, the term "nitrided layer or nitrided portion" refers to a region in which nitrogen has diffused into the metal to form a metal nitride (MxNy) structure, which can be experimentally confirmed, for example, by XRD analysis or SEM-EDS. In the said region, the metal nitride phase may be detected by X-ray diffraction (XRD) analysis at a 2θ value corresponding to MxNy, such as Fe4N, CrN, or other metal nitride phases, depending on the substrate metal. On the other hand, the term "non-nitrided layer or non-nitrided portion" refers to a region of the metal substrate in which such a nitride phase is not observed under the same analytical conditions.

[0057] For example, 41 specimens can be obtained by cutting a nitrided cylindrical specimen at 5 mm intervals along its height from one end, perpendicular to the height. Scanning electron microscope (SEM) images can be taken of the circular cross-sections of the obtained specimens. The elemental composition of the SEM images can be analyzed using the energy-dispersive X-ray spectroscopy (EDS) function of the scanning electron microscope (SEM).

[0058] As a non-limiting example, a focused ion beam-scanning electron microscope (FIB-SEM) can be used as the scanning electron microscope. For example, a plasma focused ion beam-scanning electron microscope (FIB-SEM) manufactured by Thermo Fisher Scientific can be used.

[0059] In other words, in unnitrided metals, nitrides are either absent or undetectable. The elemental composition in a SEM image can be analyzed using the energy-dispersive X-ray spectroscopy (EDS) function of a scanning electron microscope (SEM), which allows for the identification of nitrides.

[0060] Nitriding depth refers to how deeply nitrogen penetrates the metal surface during the ammonia treatment process, and is used here as a measure related to corrosion resistance.

[0061] Based on the elemental composition analysis, the nitrided depth can be measured from any three points on the outermost frame of the circular cross-section in the direction of the central axis. The "nitrided depth" can refer to the depth in the direction perpendicular to the outer surface (side) of the cylindrical test specimen, that is, the depth in the direction extending along the central axis of the cylinder. The smaller the maximum value of the nitrided depth, the higher the corrosion resistance can be evaluated.

[0062] The operating temperature of the first chamber 10 can represent the average temperature, thereby allowing the first chamber 10 to be controlled to an average temperature of 410°C or less. The average temperature of the first chamber 10 can be calculated, for example, as the arithmetic mean of the inlet and outlet temperatures of the first chamber 10, or as the mass flow rate average temperature or ambient average temperature within the first chamber 10. The average temperature can be selected in an appropriate manner depending on the flow conditions, measurement environment, and system configuration, and may include an error range of ±10°C or ±1°C depending on the measurement conditions and environment.

[0063] In some embodiments, the overall temperature of the first chamber 10 can be controlled to 410°C or less.

[0064] As a result, the ammonia decomposition reactor 100 can achieve improved reaction reliability and energy efficiency.

[0065] In some embodiments, T in Equation 1 may be, for example, 13 μm or less, 12 μm or less, or 10 μm or less. This allows the ammonia decomposition reactor 100 to further improve operational stability and energy efficiency.

[0066] The first gas stream may contain ammonia in amounts of, for example, 90% to 100% by volume, 95% to 99.9% by volume, or 99% to 99.999% by volume.

[0067] As a non-limiting example, the first gas stream may contain 99.9% by volume of ammonia and trace amounts of impurities. These impurities may include, for example, water vapor, nitrogen, oxygen, hydrogen, and the like.

[0068] The ammonia decomposition reaction in the first chamber 10 and the second chamber 20 proceeds as shown in the following reaction equation and is an endothermic reaction.

[0069] [Reaction Equation] 2NH3 → N2 + 3H2

[0070] As a result, ammonia is partially decomposed in the first chamber 10, producing hydrogen and nitrogen. Consequently, the second gas stream discharged from the first chamber 10 contains unreacted ammonia that remains undecomposed, as well as hydrogen and nitrogen, which are the decomposition products of the ammonia.

[0071] During the ammonia decomposition reaction, the operating temperature of the first chamber 10, i.e., the internal temperature, is 410°C or lower and can be maintained at, for example, 250°C to 410°C, 270°C to 390°C, 270°C to 370°C, or 310°C to 370°C.

[0072] This makes it possible to further suppress corrosion in the first chamber 10 and to control the amount of hydrogen contained in the second gas stream.

[0073] In some embodiments, the ammonia conversion rate in the first chamber 10 may be 1.4% or higher, for example, 7% or higher, 7.5% or higher, 10% or higher, 11% to 30%, or 15% to 25%.

[0074] The ammonia conversion rate (%) can be calculated using the following formula. [Calculation formula] Ammonia conversion rate (%) = {(supply ammonia flow rate) - (unreacted ammonia flow rate) / (supply ammonia flow rate)} × 100

[0075] As a non-limiting example, the concentration of each gas in a gas mixture stream can be measured using conventional gas concentration analysis methods and corresponding analyzers. Examples of these methods and analyzers include gas chromatography (GC), Fourier transform infrared (FT-IR) spectroscopy, and mass spectrometry (MS).

[0076] In the second chamber 20, the ammonia contained in the second gas stream is partially decomposed to produce hydrogen and nitrogen.

[0077] In some embodiments, the operating temperature of the second chamber 20 may exceed 410°C. This allows for further suppression or reduction of nitriding by ammonia while effectively decomposing high-purity ammonia. In this case, the operating temperature may refer to the average temperature, and the above-mentioned details can be used to define the average temperature.

[0078] In some embodiments, the overall temperature of the second chamber 20 can be controlled to a range of over 410°C to 800°C.

[0079] During the ammonia decomposition reaction, the internal temperature of the second chamber 20 is 500°C or higher and can be maintained at, for example, 500°C to 800°C, 500°C to 780°C, 510°C to 780°C, 510°C to 750°C, or 600°C to 700°C.

[0080] This makes it possible to further suppress corrosion in the second chamber 20 and significantly improve the ammonia decomposition rate.

[0081] In some embodiments, the ammonia conversion rate in the second chamber 20 may be 80% to 99.95%, for example, 90% to 99.95%, 95% to 99.95%, or 99% to 99.95%.

[0082] In some embodiments, the first chamber 10 may be made of a material including at least one selected from the group consisting of carbon steel, low alloy steel, stainless steel and nickel alloys, and may be designed to operate at a temperature of about 250°C to 410°C, and the second chamber 20 may be made of a nickel alloy (N T They may be formed from materials containing ) and can be designed to operate at temperatures of approximately 500°C to approximately 800°C. Therefore, the first and second chambers 10 and 20 are substantially free from corrosion even after at least 36 hours of ammonia decomposition operation.

[0083] In some embodiments, the first chamber 10 and / or the second chamber 20 may include a catalyst-filled section packed with a catalyst. The catalyst-filled section may be, for example, a catalyst-filled tube, which can be installed inside the first chamber 10 and / or the second chamber 20.

[0084] In some embodiments, the first chamber 10 and the second chamber 20 each include a catalyst-filled section, and the first space velocity, which is the space velocity of the catalyst in the first chamber 10, can have operating conditions that are the same as or greater than the second space velocity, which is the space velocity of the catalyst in the second chamber 20. Here, "space velocity" may be volumetric space velocity, and the amount of gas (Nm³) that the catalyst can process per unit time is the volumetric space velocity. 3 ( / hr) catalyst packing amount (Nm³ 3 This is the value obtained by dividing by ), and this can represent the amount of gas that a unit amount of catalyst can process per unit time.

[0085] In some embodiments, while the ammonia decomposition reaction takes place in the first chamber 10 and the second chamber 20 respectively, the ratio of the first space velocity of the catalyst in the first chamber 10 to the second space velocity of the catalyst in the second chamber 20 may be, for example, 1 to 25, 1 to 10, or 1 to 5.

[0086] In some embodiments, during the ammonia decomposition reaction, the catalyst in the first chamber 10 is used for 4,000 hours. -1 The above first spatial velocity can be achieved. The first spatial velocity is, for example, 4,000hr -1 ~120,000hr -1 , or 10,000hr -1 ~100,000hr -1 This may also be the case. This suppresses corrosion in the first chamber 10 and allows for effective control of the ammonia conversion rate.

[0087] In some embodiments, during the ammonia decomposition reaction, the catalyst in the second chamber 20 is used for 1,000 hours. -1 The above second spatial velocity can be achieved. The second spatial velocity is, for example, 1,000hr -1 ~100,000hr -1 , 4,000hr -1 ~10,000hr -1 This may also be the case. This suppresses corrosion in the second chamber 20, prevents a decrease in catalyst performance, and allows for the efficient decomposition reaction of unreacted ammonia.

[0088] For example, the first and second space velocities can be controlled based on the flow rates of the gas streams flowing into the first chamber 10 and the second chamber 20, respectively, and the packing volume of the catalysts installed in each chamber 10 and 20. In non-limiting examples, the flow rate of each gas stream can be measured using a mass flow meter or a volumetric flow meter, and the packing volume of each catalyst can be calculated based on the diameter and height of the catalyst layer. In some embodiments, the catalyst may include an active metal supported on a carrier, and the carrier may be doped with a metal element. The carrier may be, for example, a zeolite, silica, alumina, and the metal element may include, for example, Zn, Co, Cu, K, Na, Cs, Mo, Se, Pd, Pt, Ba, Mg, Ca, etc.

[0089] The material forming the first chamber 10 contained in the ammonia decomposition reactor 100 may include carbon steel, low-alloy steel, stainless steel, and / or nickel-based alloys.

[0090] In some embodiments, the first chamber 10 may be made of carbon steel, low-alloy steel, stainless steel, and / or nickel-based alloy.

[0091] In some embodiments, the first chamber 10 may include low-alloy steel, stainless steel, and / or nickel-based alloys.

[0092] The low-alloy steel may, for example, contain alloying elements in amounts of 1% to 35% by weight, 1% to 30% by weight, or 5% to 35% by weight, based on the total weight. Non-limiting examples include alloying elements such as carbon, silicon, manganese, nickel, aluminum, chromium, phosphorus, sulfur, molybdenum, copper, and nitrogen.

[0093] The aforementioned stainless steel may include, for example, austenitic stainless steel, ferritic stainless steel, martensitic stainless steel, and the like.

[0094] In some embodiments, the first chamber 10 is made of a nickel-based alloy (N T ) can include

[0095] The material forming the second chamber 20 contained in the ammonia decomposition reactor 100 is a nickel-based alloy (N) satisfying formula 1. T ) can include

[0096] In some embodiments, the second chamber 20 is made of a nickel-based alloy (N T This can be configured as follows. This prevents or suppresses a decrease in the thermal conductivity of the second chamber 20, thereby achieving improved operational stability and energy efficiency.

[0097] In some embodiments, nickel alloys (NT The alloy may contain 40% to 80% by weight of nickel. The nickel content is based on the total weight of the nickel-based alloy.

[0098] In one embodiment, nickel alloy (N T The nickel content in the product may be, for example, 40% to 78% by weight, or 52% to 75% by weight.

[0099] In some embodiments, nickel alloys (N T These may include, for example, Ni-Cu-Fe alloys, Ni-Cr-Mo-W alloys, Ni-Cr-Fe-Mo alloys, and / or Ni-Cr-Co-W alloys.

[0100] The aforementioned nickel alloy (N T For example, it may include one or more alloys that are classified into any one of the groups selected from UNS N06601, UNS N06625, UNS N06690, UNS N07718, UNS N07792, and UNS N06002 according to the UNS (Unified Numbering System).

[0101] In some embodiments, the ammonia decomposition reactor 100 may further include a connecting line 1a that connects the first chamber 10 and the second chamber 20.

[0102] The connecting line 1a may be a connecting tube, and may be made of a nickel-based alloy (N T ) can include

[0103] As a non-limiting example, the first chamber 10 and / or the second chamber 20 may have a heat exchanger type structure in which heat is continuously supplied, or they may have an adiabatic reactor type structure in which a preheated gas stream is supplied and the decomposition reaction takes place.

[0104] As a non-limiting example, the first chamber 10 and / or the second chamber 20 may each include an inlet or outlet into which a gas stream flows in or out, and the inlets and outlets may include one or more as needed.

[0105] As a non-limiting example, the ammonia decomposition reactor 100 may include an operating temperature control device to maintain the operating temperature of the first chamber 10 at approximately 410°C or lower. For example, the operating temperature control device may include a heater, a thermocouple, and / or a controller. The heater may be a heating means operated by, for example, an electric resistance heater, an induction heater, or an external heat source. The thermocouple can maintain the temperature range by sensing the temperature in the first chamber in real time, and the controller can maintain the temperature range by controlling the operation of the heater based on the temperature information. The operating temperature control device is not particularly limited in its configuration or installation method.

[0106] For example, the ammonia decomposition reactor 100 according to the above-described embodiment of this disclosure can also be provided in the form of an ammonia decomposition system including it.

[0107] The ammonia decomposition system according to the embodiments of this disclosure may include the ammonia decomposition reactor 100 described above.

[0108] <Hydrogen generator> Figure 2 is a schematic block diagram showing a hydrogen generation apparatus according to one embodiment of the present disclosure.

[0109] The hydrogen generation apparatus 200 according to the embodiments of this disclosure can achieve improved operational stability and energy efficiency by including the ammonia decomposition reactor 100 described above.

[0110] In some embodiments, the hydrogen generator 200 may include, for example, an ammonia supply unit 30, a vaporization unit 40, a preheating unit 50, an ammonia decomposition reactor 100, a hydrogen collection unit 60, a hydrogen purification unit 70, a hydrogen storage unit 80, and / or a heat supply unit 90, which can be connected to each other via connecting lines. The connecting lines may be, for example, connecting pipes.

[0111] As a non-limiting example, the connecting pipe may include carbon steel, low-alloy steel, stainless steel, and / or nickel-based alloys.

[0112] The arrangement, length, and other characteristics of the connecting pipes can be changed in various ways as needed.

[0113] In one embodiment, the connecting line directly connected to the ammonia decomposition reactor 100 is made of a nickel-based alloy (N T ) can include

[0114] The ammonia supply unit 30 can store and supply ammonia. The ammonia supply unit 30 can store and supply, for example, ammonia in gaseous form (hereinafter sometimes abbreviated as "gas-phase ammonia") or ammonia in liquid form (hereinafter sometimes abbreviated as "liquid-phase ammonia").

[0115] When the ammonia supply unit 30 stores and supplies liquid-phase ammonia, for example, liquid-phase ammonia may be supplied from the ammonia supply unit 30 to the vaporization unit 40, and gaseous ammonia vaporized by the vaporizer from the vaporization unit 40 may be supplied to the first chamber 10.

[0116] As a non-limiting example, the ammonia supply unit 30 may be an ammonia storage tank.

[0117] The hydrogen generator 200 may include a preheating unit 50 connected to the vaporization unit 40, and the gaseous ammonia can be preheated in the preheating unit 50 by a preheater.

[0118] In some embodiments, the hydrogen generator 200 may include a hydrogen collection unit 60 into which a third gas stream discharged from the second chamber 20 flows. The third gas stream may include residual ammonia that remains undecomposed in the second chamber 20 from the unreacted ammonia, hydrogen, and nitrogen.

[0119] The hydrogen collection unit 60 can collect hydrogen by separating residual ammonia and / or nitrogen using, for example, a temperature swing adsorption (TSA), pressure swing adsorption (PSA), or vacuum pressure swing adsorption (VPSA) method. The hydrogen collection unit 60 can be configured to separate residual ammonia from the product stream and selectively recover high-purity hydrogen.

[0120] The hydrogen collection unit 60 may include an adsorption tower filled with an adsorbent. The adsorption tower may be, for example, one or more adsorption towers connected together, one adsorption tower connected to one or more other towers, or a combination thereof.

[0121] The adsorbent may include, for example, a hydrogen-selective adsorbent, a nitrogen-selective adsorbent, and / or an ammonia-selective adsorbent. The adsorbent may include, for example, CaCl2 / Al2O3, MgCl2 / Al2O3, silica, alumina, activated carbon, and / or zeolite. The structure of the zeolite may be, for example, in the form of MFI, CHA, CHA-Cs, CHI, ERI, FAU, FER, GOO, HEU, LTA, MER, MON, MOR, RHO, AEI, AFX, DDR, LEV, RTH, etc.

[0122] In one embodiment, the structure of the zeolite may be, for example, in the form of CHA, LTA, and / or FAU.

[0123] In some embodiments, the hydrogen generator 200 may further include a hydrogen purification unit 70 and / or a hydrogen storage unit 80 connected to the hydrogen collection unit 60.

[0124] The hydrogen purification unit 70 can purify hydrogen using, for example, a pressure swing adsorption (PSA) or a vacuum pressure swing adsorption (VPSA) method.

[0125] The hydrogen storage unit 80 can store, for example, hydrogen separated from at least one of the hydrogen collection unit 60 and the hydrogen purification unit 70.

[0126] As a non-limiting example, the hydrogen storage unit 80 may be a hydrogen storage tank.

[0127] The purity of the hydrogen produced by the hydrogen generator 200 and stored in the hydrogen storage unit 80 may be 99% by volume or higher, for example, 99.9% by volume or higher.

[0128] The hydrogen production rate stored in the hydrogen storage unit 80 is 1,300 Nm³. 3 It may be greater than or equal to / h, for example, 1,300 Nm 3 / h~800,000Nm 3 / h is also acceptable.

[0129] The hydrogen generator 200 can, for example, use the gas stream discharged from the hydrogen collection unit 60 and / or the hydrogen purification unit 70 as an off-gas stream, trim gas stream, etc. The generator may include a heat supply unit 90 that can recover the off-gas stream, trim gas stream, etc., and generate and supply thermal energy. The off-gas stream, trim gas stream, etc., can include, for example, hydrogen, nitrogen, and / or ammonia.

[0130] The heat supply unit 90 can supply thermal energy to the first chamber 10, the second chamber 20, the vaporization unit 40, and / or the preheating unit 50 using the trim gas stream and / or the off gas stream. By using the trim gas stream or the off gas stream as a heat source for the ammonia decomposition reaction in this way, energy efficiency can be further improved.

[0131] As a non-limiting example, the heat supply unit 90 may include a combustor, a heat exchanger, and the like. The off-gas stream and / or the trim gas stream can be supplied to the combustor for combustion, which can heat the outer wall of the first chamber 10 or the like via the high-temperature combustion gas stream, or transfer heat to the heat exchanger coil.

[0132] The ammonia supply unit 30, vaporization unit 40, preheating unit 50, ammonia decomposition reactor 100, hydrogen collection unit 60, hydrogen purification unit 70, hydrogen storage unit 80, and / or heat supply unit 90 included in the hydrogen generation device 200 can be connected to each other via connecting lines 2a, 3a, 4a, 5a, 6a, 7a, 8a, 9a, and 10a.

[0133] The connecting line may be, for example, a connecting pipe.

[0134] As a non-limiting example, the connecting pipe may include carbon steel, low-alloy steel, stainless steel, and / or nickel-based alloys.

[0135] The arrangement, length, and other characteristics of the connecting pipes can be changed in various ways as needed.

[0136] As a non-limiting example, the ammonia supply unit 30, vaporization unit 40, preheating unit 50, ammonia decomposition reactor 100, hydrogen collection unit 60, hydrogen purification unit 70, hydrogen storage unit 80, and / or heat supply unit 90 may each include one or more inlets and / or outlets into which a gas stream flows in or out.

[0137] <Hydrogen generation method> Figure 3 is a schematic process flow diagram illustrating a hydrogen production method according to one embodiment of the present disclosure.

[0138] The hydrogen production method according to the embodiments of this disclosure can produce hydrogen with high initial energy efficiency over a long period of time using the ammonia decomposition reactor 100 and / or the hydrogen production apparatus 200 described above.

[0139] According to the hydrogen production method described above, a first gas stream containing ammonia is introduced into the first chamber 10 (S10).

[0140] The first gas stream may contain ammonia in amounts of, for example, 90% to 100% by volume, 95% to 99.9% by volume, or 99% to 99.999% by volume.

[0141] As a non-limiting example, the first gas stream may contain 99.9% by volume of ammonia and trace amounts of impurities, such as water vapor, nitrogen, oxygen, and hydrogen.

[0142] In some embodiments, the hydrogen generation method can supply the first gas stream from an ammonia supply unit 30 that stores and supplies ammonia to the first chamber 10. This allows the first gas stream to be discharged from the ammonia supply unit 30 and flow into the first chamber 10.

[0143] The ammonia supply unit 30 can store and supply, for example, gaseous ammonia or liquid ammonia.

[0144] As a non-limiting example, the ammonia supply unit 30 can supply the liquid-phase ammonia to the vaporization unit 40. When the liquid-phase ammonia is vaporized in the vaporization unit 40, the first gas stream may include the gaseous ammonia vaporized by the vaporizer in the vaporization unit 40.

[0145] In the first chamber 10, ammonia is partially decomposed at a temperature of 410°C or lower, producing hydrogen and nitrogen (S20).

[0146] As a result, the second gas stream discharged from the first chamber 10 contains unreacted ammonia that remains undecomposed, and hydrogen and nitrogen, which are decomposition products of the ammonia.

[0147] The ammonia decomposition reaction in the first chamber 10 can be carried out at a temperature of 410°C or lower, for example, between 250°C and 410°C, 270°C and 390°C, 270°C and 370°C, or 310°C and 370°C.

[0148] By carrying out the ammonia decomposition reaction within the aforementioned temperature range, corrosion in the first chamber 10 can be further suppressed, and the amount of hydrogen contained in the second gas stream can be controlled to reduce the rate of the nitriding reaction on the inner surface of the second chamber.

[0149] In some embodiments, ammonia in the first chamber 10 can be partially decomposed such that the ammonia conversion rate is 1.4% or more. The ammonia conversion rate in the first chamber 10 may be, for example, 7% or more, 7.5% or more, 10% or more, 11% to 30%, or 15% to 25%.

[0150] A second gas stream, containing ammonia, nitrogen, and hydrogen, is discharged from the first chamber and flows into the second chamber (S30).

[0151] In the second chamber, ammonia is partially decomposed to produce hydrogen and nitrogen (S40).

[0152] The ammonia decomposition reaction in the second chamber 20 can be carried out at temperatures above 500°C, for example, at temperatures of 500°C to 800°C, 500°C to 780°C, 510°C to 780°C, 510°C to 750°C, or 600°C to 700°C.

[0153] By carrying out the ammonia decomposition reaction within the aforementioned temperature range, the reaction reliability of the second chamber 20 is improved, and sufficient hydrogen production efficiency can be achieved.

[0154] In some embodiments, ammonia in the second chamber 20 can be partially decomposed such that the ammonia conversion rate is 80% to 99.95%. The ammonia conversion rate in the second chamber 20 may be, for example, 90% to 99.95%, 95% to 99.95%, or 99% to 99.95%.

[0155] In some embodiments, the hydrogen production method may further include filling at least one of the first chamber 10 and the second chamber 20 with a catalyst. The catalyst can be, for example, filled into a catalyst-filled tube and installed inside the first chamber 10 and / or the second chamber 20.

[0156] In some embodiments, the first chamber 10 and the second chamber 20 are further packed with catalysts, and the ammonia decomposition reaction can be carried out in each of the first chamber 10 and the second chamber 20 under conditions where the first space velocity, which is the space velocity of the catalyst in the first chamber 10, is greater than the second space velocity, which is the space velocity of the catalyst in the second chamber 20.

[0157] In some embodiments, while the ammonia decomposition reaction is taking place in the first chamber 10 and the second chamber 20, the ratio of the first space velocity of the catalyst in the first chamber 10 to the second space velocity of the catalyst in the second chamber 20 may be 1 to 25. The ratio of the first space velocity to the second space velocity may be, for example, 1 to 25, 1 to 10, or 1 to 5.

[0158] In some embodiments, during the ammonia decomposition reaction, the catalyst in the first chamber 10 is used for 4,000 hours. -1 The above first spatial velocity can be achieved. The first spatial velocity is, for example, 4,000hr-1 ~120,000hr -1 , or 10,000hr -1 ~100,000hr -1 This may also be the case. This suppresses corrosion in the first chamber 10 and allows for effective control of the ammonia conversion rate.

[0159] In some embodiments, during the ammonia decomposition reaction, the catalyst in the second chamber 20 is used for 1,000 hours. -1 The above second spatial velocity can be achieved. The second spatial velocity is, for example, 1,000hr -1 ~100,000hr -1 , 4,000hr -1 ~10,000hr -1 This may also be the case. This suppresses corrosion in the second chamber 20, prevents a decrease in catalyst performance, and allows for the efficient decomposition reaction of unreacted ammonia.

[0160] In some embodiments, the hydrogen generation method allows a third gas stream discharged from the second chamber 20 to flow into the hydrogen collection unit 60. The third gas stream may contain residual ammonia, hydrogen, and nitrogen that remain undecomposed in the second chamber 20.

[0161] The hydrogen collection unit 60 can separate residual ammonia or separate and collect hydrogen using, for example, a temperature swing adsorption (TSA), pressure swing adsorption (PSA), or vacuum pressure swing adsorption (VPSA) method.

[0162] The hydrogen collection unit 60 may include an adsorption tower filled with an adsorbent. The adsorbent and the adsorption tower are as described above.

[0163] In some embodiments, the hydrogen generation method allows the fourth gas stream discharged from the hydrogen collection unit 60 to flow into the hydrogen purification unit 70.

[0164] In some embodiments, the hydrogen generation method can allow the hydrogen discharged from the hydrogen purification unit 70 to flow into the hydrogen storage unit 80.

[0165] The hydrogen purification unit 70 can purify hydrogen using, for example, a pressure swing adsorption (PSA) or a vacuum pressure swing adsorption (VPSA) method.

[0166] The hydrogen storage unit 80 can store hydrogen separated from at least one of the hydrogen collection unit 60 and the hydrogen purification unit 70. In a non-limiting example, the hydrogen storage unit 80 may be a hydrogen storage tank.

[0167] The purity of the hydrogen produced by the hydrogen production method and stored in the hydrogen storage unit 80 may be 99% by volume or higher, for example, 99.9% by volume or higher.

[0168] The hydrogen production rate stored in the hydrogen storage unit 80 is 1,300 Nm³. 3 It may be greater than or equal to / h, for example, 1,300 Nm 3 / h~800,000Nm 3 / h is also acceptable.

[0169] In some embodiments, off-gas streams, trim gas streams, etc., discharged from the hydrogen collection unit 60 and / or hydrogen purification unit 70 can be fed into the heat supply unit 90. The off-gas streams, trim gas streams, etc., may include, for example, hydrogen, nitrogen, and / or ammonia.

[0170] The embodiments of this disclosure will be further described below with reference to specific experimental examples. The examples and comparative examples included in the experimental examples are illustrative of this disclosure and do not limit the scope of the attached claims.

[0171] Example 1 A hydrogen production apparatus was manufactured, comprising an ammonia storage tank made of SUS304 material; an ammonia decomposition reactor with a first chamber made of SUS304 material and a second chamber made of Inconel625 material; a hydrogen collection unit made of SUS304 material; a hydrogen purification unit made of SUS304 material; and a hydrogen storage tank made of SUS304 material. These are connected by connecting pipes in the order described. The connecting pipe between the first chamber and the second chamber is made of Inconel625 material, and the remaining connecting pipes are made of SUS304 material.

[0172] The first and second chambers are each fitted with packed tubes filled with catalysts. Separation of hydrogen and ammonia in the hydrogen collection and hydrogen purification sections was performed using an adsorption tower by the Temperature Swing Adsorption (TSA) method. The adsorbent packed into the adsorption tower was zeolite 5A. Using the manufactured hydrogen generator, hydrogen was produced according to the conditions shown in Tables 1 and 2 below.

[0173] Example 2 A hydrogen generation apparatus was manufactured in the same manner as in Example 1, except that the second chamber and the connecting tube between the first and second chambers were made of Inconel 601 material. Using the manufactured hydrogen generator, hydrogen was produced according to the conditions shown in Tables 1 and 2 below.

[0174] Example 3 A hydrogen generation apparatus was manufactured in the same manner as in Example 1, except that the first chamber was made of carbon steel. Using the manufactured hydrogen generator, hydrogen was produced according to the conditions shown in Tables 1 and 2 below.

[0175] Example 4 Using the hydrogen generator manufactured in Example 1, hydrogen was produced according to the conditions shown in Tables 1 and 2 below.

[0176] Example 5 Using the hydrogen generator manufactured in Example 1, hydrogen was produced according to the conditions shown in Tables 1 and 2 below.

[0177] Comparative Example 1 A hydrogen generation apparatus was manufactured in the same manner as in Example 1, except that it included an ammonia decomposition reactor equipped with a second chamber but without a first chamber. In this case, the second chamber was formed in the same manner as the second chamber in Example 1. Hydrogen was produced using the manufactured hydrogen generator according to the conditions shown in Table 2 below.

[0178] Comparative Example 2 A hydrogen generation apparatus was manufactured in the same manner as in Example 1, except that the second chamber was made of SUS304. Using the manufactured hydrogen generator, hydrogen was produced according to the conditions shown in Tables 1 and 2 below.

[0179] Comparative Example 3 A hydrogen generation apparatus was manufactured in the same manner as in Example 1, except that the second chamber was made of SUS316. Using the manufactured hydrogen generator, hydrogen was produced according to the conditions shown in Tables 1 and 2 below.

[0180] Comparative Example 4 A hydrogen generation apparatus was manufactured in the same manner as in Comparative Example 1, except that the second chamber was formed from Inconel 601 material. Hydrogen was produced using the manufactured hydrogen generator according to the conditions shown in Table 2 below.

[0181] [Table 1]

[0182] [Table 2]

[0183] Experimental example Experimental Example 1: Evaluation of Corrosion Resistance In the above-described examples and comparative examples, the corrosion resistance of the inner surfaces of the first and second chambers was evaluated using metal test specimens made of the same material as the inner surfaces of the first and second chambers (hereinafter referred to as "corresponding metal test specimens").

[0184] Under substantially identical atmospheric conditions, the nitriding reaction by ammonia occurring on the inner surfaces of the first and second chambers can be carried out at substantially the same rate and using the same reaction equation on the surfaces of corresponding metal test pieces, even considering the effects of test errors and differences in surface conditions. It was confirmed that the presence or absence of catalyst in the first and second chambers does not significantly affect the nitriding reaction of ammonia.

[0185] Therefore, the evaluation results of corrosion resistance on corresponding metal test pieces were used as an index for evaluating corrosion resistance on the internal surfaces of the first and second chambers.

[0186] (1) Corrosion resistance due to the operating temperature of the first chamber 1) In Example 1, a metal test piece made of the same material (SUS304) as the first chamber was prepared in a cylindrical shape with a circular cross-sectional diameter of 2 mm and a height of 200 mm (hereinafter referred to as "cylindrical test piece").

[0187] Furthermore, cylindrical test specimens made of SUS316 and Inconel625 were prepared using the same method, and these were designated as Example 1-1 and Example 1-2, respectively.

[0188] A gas stream supply section, a gas stream discharge section, and a vertical quartz tube reactor connected to a furnace were prepared.

[0189] Each cylindrical test specimen was placed in the vertical quartz tube reactor, and the internal temperature of the vertical quartz tube reactor was raised to the operating temperature at a heating rate of 10°C / min. At this time, a gas stream containing 99.99999 volume% NH3 was continuously supplied to the vertical quartz tube reactor.

[0190] The operating temperature of the vertical quartz tube reactor was increased by 10°C increments from 300°C to 450°C, and the vertical quartz tube reactor was operated at the operating temperature for 36 hours to obtain nitrided cylindrical test specimens.

[0191] Forty-one specimens were obtained by cutting a nitrided cylindrical specimen at 5 mm intervals along its height from one end, perpendicular to the height. Scanning electron microscope (SEM) images were taken of the circular cross-sections of the obtained specimens using a Thermo Fisher Scientific Helios PFIB instrument. The magnification conditions were selected to accurately measure the nitriding depth; for example, magnifications of 2000x and 500x were used depending on whether the nitriding depth was 40 μm or less or 40 μm or more.

[0192] The elemental composition within the aforementioned SEM images was analyzed using the energy-dispersive X-ray spectroscopy (EDS) function of the same SEM instrument. The specific analysis conditions were as follows. - Acceleration voltage: kV -Analysis mode: Point analysis (Point)? Area analysis (Map)? - Presence or absence of coating on the cross-section of the test specimen: - Analysis time:

[0193] Based on the elemental composition analysis, the nitridation depth was measured in the direction of the central axis from three arbitrary points on the outermost frame of the circular cross-section. We evaluated that the smaller the maximum depth of nitriding, the higher the corrosion resistance. The results are shown in Table 3 and Figure 4. Since it is not possible to show the nitriding depth at all temperatures in Table 3, the results are shown separately for 390°C, 410°C, and 430°C.

[0194] [Table 3]

[0195] 2) Cylindrical test specimens made of SUS304, SUS316, and Inconel625 were prepared using the same method as described above. For the cylindrical specimens, the maximum nitrided depth was evaluated using the same method as described above, except that the operating time of the vertical quartz tube reactor was changed to 100 hours. The results are shown in Table 4 and Figure 5.

[0196] [Table 4]

[0197] From Tables 3 and 4 and Figures 4 and 5 above, it was confirmed that corrosion of the internal surface of the first chamber begins to increase rapidly at temperatures above 410°C. Furthermore, as the operating time under conditions above 410°C increased, the corrosion rate of the internal surface of the first chamber accelerated even further.

[0198] (2) Corrosion resistance based on the operating time of the first chamber In Examples 1 to 5, a metal test specimen made of the same material as the first chamber was prepared as a cylindrical shape with a circular cross-sectional diameter of 2 mm and a height of 200 mm (hereinafter referred to as "cylindrical test specimen").

[0199] A gas stream supply section, a gas stream discharge section, and a vertical quartz tube reactor connected to a furnace were prepared.

[0200] A cylindrical test specimen was placed in the vertical quartz tube reactor, and the internal temperature of the vertical quartz tube reactor was increased at a heating rate of 10°C / min to the operating temperature of the first chamber corresponding to Table 1.

[0201] Subsequently, the cylindrical specimens were exposed to the environment corresponding to Table 1 for 100 hours from the time the operating temperature of the first chamber was reached, thereby obtaining nitrided cylindrical specimens.

[0202] For the nitrided cylindrical specimens, the maximum nitrided depth was evaluated using the same method as described above. The results are shown in Table 5 and Figure 6.

[0203] (3) Corrosion resistance due to the operating time of the second chamber In Examples 1-5 and Comparative Examples 1-4, metal test specimens made of the same material as the second chamber were prepared in a cylindrical shape with a circular cross-section diameter of 2 mm and a height of 200 mm (hereinafter referred to as "cylindrical test specimens").

[0204] A gas stream supply section, a gas stream discharge section, and a vertical quartz tube reactor connected to a furnace were prepared.

[0205] A cylindrical test specimen was placed in the vertical quartz tube reactor, and the internal temperature of the vertical quartz tube reactor was increased at a heating rate of 10°C / min to the operating temperature of the second chamber corresponding to Table 2.

[0206] Subsequently, the cylindrical specimens were exposed to the environment corresponding to Table 2 for 100 hours from the time the operating temperature of the second chamber was reached, and nitrided cylindrical specimens were obtained.

[0207] For the nitrided cylindrical specimens, the maximum nitrided depth was evaluated using the same method as described above. The results are shown in Table 5, Figures 7a and 7b. The SEM measurement conditions for Examples 1-5 and Comparative Example 1 are as follows. HV (High voltage): 15.00kV CURR (Beam Current): 1.6nA MAG (Magnification): 2000x DET(Detector): CBS(Circular Backscatter Detector) The SEM measurement conditions for Comparative Examples 2-4 are as follows: HV (High voltage): 15.00kV CURR (Beam Current): 1.6nA MAG (Magnification): 500x

[0208] [Table 5]

[0209] Referring to Table 5 above, in Example 3, where the first chamber was made of carbon steel, the corrosion level during long-term operation was relatively high.

[0210] In contrast, nickel alloys (N) satisfy the aforementioned equation 1. T The second chamber in the example, including the above, was evaluated as having a low level of corrosion even after long-term operation, demonstrating improved reliability and stability.

[0211] In Example 5, the hydrogen concentration in the gas stream supplied to the second chamber was relatively low, resulting in reduced corrosion resistance.

[0212] In Comparative Examples 1 and 4, a gas stream containing 99.99999 volume% ammonia was supplied directly to the high-temperature second piping without passing through the chamber, resulting in rapid nitriding and degraded reliability and stability during long-term operation. In Comparative Example 4, the corrosion rate increased even further because the second chamber was manufactured from Inconel 601 material.

[0213] In Comparative Examples 2 and 3, the second chamber was manufactured from SUS304 and SUS316 materials, respectively. However, since these materials did not satisfy the above formula 1, the corrosion resistance after long-term operation deteriorated further.

[0214] Experimental Example 2: Evaluation of Corrosion Rate (1) Corrosion rate of the first chamber In Examples 1 to 5, a metal test specimen made of the same material as the first chamber was prepared as a cylindrical shape with a circular cross-sectional diameter of 2 mm and a height of 200 mm (hereinafter referred to as "cylindrical test specimen").

[0215] A gas stream supply section, a gas stream discharge section, and a vertical quartz tube reactor connected to a furnace were prepared.

[0216] A cylindrical test specimen was placed in the vertical quartz tube reactor, and the internal temperature of the vertical quartz tube reactor was increased at a heating rate of 10°C / min to the operating temperature of the first chamber corresponding to Table 1.

[0217] Subsequently, cylindrical specimens were exposed to the environmental conditions corresponding to Table 1 for 36 hours, 100 hours, 200 hours, and 400 hours, respectively, starting from the time the operating temperature of the first chamber was reached, to obtain nitrided cylindrical specimens.

[0218] For the nitrided cylindrical specimens, the maximum nitrided depth was evaluated using the same method as described above. The results are shown in Table 6 and Figure 8.

[0219] [Table 6]

[0220] According to Table 6, in Example 3, where a carbon steel chamber was used, the increase in corrosion rate was greater than in the other examples as the operating time increased at an operating temperature of 350±10℃.

[0221] (2) Corrosion rate of the second chamber In Example 1 and Comparative Examples 2 and 3, a metal test specimen made of the same material as the second chamber was prepared as a cylindrical specimen with a circular cross-section diameter of 2 mm and a height of 200 mm (hereinafter referred to as "cylindrical test specimen").

[0222] A vertical quartz tube reactor connected to the gas stream supply unit and furnace was prepared.

[0223] A cylindrical test specimen was placed in the vertical quartz tube reactor, and the temperature of the vertical quartz tube reactor was increased at a heating rate of 10°C / min to the operating temperature of the second chamber corresponding to Table 2.

[0224] Subsequently, cylindrical specimens were exposed to the atmospheres corresponding to those shown in Table 2 for 36 hours, 100 hours, 200 hours, and 400 hours, respectively, starting from the time the operating temperature of the second chamber was reached, to obtain nitrided cylindrical specimens.

[0225] For the nitrided cylindrical specimens, the maximum nitrided depth was evaluated using the same method as described above. The results are shown in Table 7 and Figure 9.

[0226] [Table 7]

[0227] Referring to Table 7 above, at an operating temperature of 510±10℃, a nickel-based alloy (N) that satisfies the aforementioned formula 1 is T The degree of nitriding to the second chamber in Example 1, including ), was very low, and the increase in the maximum nitrided depth was small even after long-term operation, demonstrating improved reliability and safety.

[0228] In contrast, in the comparative example, since the second chambers were made of SUS304 and SUS316 material, respectively, the corrosion resistance deteriorated at the operating temperature, and the rate of corrosion increased significantly as the operating time increased.

[0229] Experimental Example 3: Hydrogen Production Efficiency Hydrogen was produced under the following conditions using the hydrogen generation apparatus described in Examples 1 to 5 above. Inflow velocity of the first gas stream into the first chamber: 1041.7 kg / hr Emission rate of the second gas stream discharged from the first chamber: 1041.7 kg / hr Inflow velocity of the second gas stream into the second chamber: 1041.7 kg / hr Emission rate of the third gas stream discharged from the second chamber: 1041.7 kg / hr

[0230] The purity of the hydrogen produced by the hydrogen generator and stored in the hydrogen storage unit is 99.9% by volume, and the hydrogen production rate was 2040.3 Nm³ in Examples 1-3. 3 / h, 2038.5Nm in Example 4 3 / hr, 2038.4Nm in Example 5 3 It was / hr.

Claims

1. A first chamber into which a first gas stream containing ammonia flows, The system includes a second chamber into which a second gas stream containing ammonia, nitrogen, and hydrogen is discharged from the first chamber, The operating temperature of the first chamber is 410°C or lower. The first chamber includes at least one selected from the group consisting of carbon steel, low-alloy steel, stainless steel, and nickel-based alloys. The second chamber is made of a nickel-based alloy (N) that satisfies the following formula 1. Ｔ Ammonia decomposition reactors, including: [Formula 1] T ≤ 15 μm (In the above formula 1, T is the nickel alloy (N Ｔ A cylindrical test specimen with a cross-sectional diameter of 2 mm and a height of 200 mm was prepared, and the cylindrical test specimen was subjected to 97.2 volume% NH ３ , 2.1 volume% H ２ , and 0.7 volume% N ２ This is the maximum depth of nitridation from the side of the cylindrical specimen in the direction of the central axis after exposure to a gas stream containing and a temperature environment of 500°C for 100 hours, and this depth was measured by SEM (Scanning Electron Microscopy) and EDS (Energy Dispersive X-ray Spectroscopy) analysis.

2. The ammonia decomposition reactor according to claim 1, wherein in the above formula 1, T ≤ 13 μm.

3. The ammonia decomposition reactor according to claim 1, wherein the first gas stream contains ammonia in an amount of 90% to 100% by volume.

4. The ammonia decomposition reactor according to claim 1, wherein the operating temperature of the second chamber is greater than 410°C.

5. The second chamber is made of the nickel-based alloy (N Ｔ The ammonia decomposition reactor according to claim 1, comprising the following components.

6. The aforementioned nickel alloy (N Ｔ The ammonia decomposition reactor according to claim 1, comprising one or more alloys classified by the UNS (Unified Numbering System) into any one of the group consisting of UNS N06601, UNS N06625, UNS N06690, UNS N07718, UNS N07792, and UNS N06002.

7. The ammonia decomposition reactor according to claim 1, wherein the ammonia conversion rate in the first chamber is 1.4% or more, and the ammonia conversion rate in the second chamber is 80% to 99.95%.

8. The ammonia decomposition reactor according to claim 1, wherein at least one of the first chamber and the second chamber includes a catalyst-filled section packed with a catalyst.

9. The ammonia decomposition reactor according to claim 1, wherein the first chamber and the second chamber each include a catalyst-filled section packed with a catalyst, and the first space velocity, which is the space velocity of the catalyst in the first chamber, has an operating condition that is the same as or greater than the second space velocity, which is the space velocity of the catalyst in the second chamber.

10. The ammonia decomposition reactor according to claim 9, wherein, while the ammonia decomposition reaction is carried out in the first chamber and the second chamber, the ratio of the first space velocity of the catalyst in the first chamber to the second space velocity of the catalyst in the second chamber is 1 to 25.

11. A hydrogen generation apparatus comprising the ammonia decomposition reactor described in claim 1.

12. The steps include introducing a first gas stream containing ammonia into the first chamber, The first step is to partially decompose ammonia in the first chamber at a temperature of 410°C or lower to produce hydrogen and nitrogen, The steps include: introducing a second gas stream, which is discharged from the first chamber and contains ammonia, nitrogen, and hydrogen, into the second chamber; The step includes the partial decomposition of ammonia in the second chamber to produce hydrogen and nitrogen, The first chamber includes at least one selected from the group consisting of carbon steel, low-alloy steel, stainless steel, and nickel-based alloys. The second chamber is made of a nickel-based alloy (N) that satisfies the following formula 1. Ｔ Hydrogen production methods including: [Formula 1] T ≤ 15 μm (In the above formula 1, T is the nickel-based alloy (N Ｔ ) was prepared as a cylindrical test piece with a cross-sectional diameter of 2 mm and a height of 200 mm, and the cylindrical test piece was placed in 97.2 vol% of NH ３ , 2.1 vol% of H ２ , and 0.7 vol% of N ２ When exposed to a gas stream containing and a temperature environment of 500 ° C. for 100 hours, it is the maximum value of the depth nitrided in the central axis direction from the side surface of the cylindrical test piece, and the depth is measured by SEM (Scanning Electron Microscopy) and EDS (Energy Dispersive X-Ray Spectroscopy) analysis.).

13. The hydrogen production method according to claim 12, wherein in the above formula 1, T ≤ 13 μm.

14. The hydrogen production method according to claim 12, wherein the first gas stream contains ammonia in an amount of 90% to 100% by volume.

15. The second chamber is made of the nickel-based alloy (N Ｔ A hydrogen generation method according to claim 12, comprising the following:

16. The hydrogen production method according to claim 12, wherein in the first chamber ammonia is partially decomposed such that the ammonia conversion rate is 1.4% or more, and in the second chamber ammonia is partially decomposed such that the ammonia conversion rate is 80% to 99.95%.

17. The hydrogen production method according to claim 12, further comprising the step of filling at least one of the first chamber and the second chamber with a catalyst.

18. The hydrogen production method according to claim 17, further comprising the step of filling each of the first and second chambers with a catalyst, wherein the ammonia decomposition reaction in each of the first and second chambers is carried out under operating conditions in which the first space velocity, which is the space velocity of the catalyst in the first chamber, is the same as or greater than the second space velocity, which is the space velocity of the catalyst in the second chamber.

19. The hydrogen production method according to claim 18, wherein, while the ammonia decomposition reaction is carried out in the first chamber and the second chamber, the ratio of the first space velocity of the catalyst in the first chamber to the second space velocity of the catalyst in the second chamber is 1 to 25.

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