Ammonia handling device and method for producing same

Abstract

An ammonia handling device (1) comprises an ammonia contact part (10) which includes a modified layer (12) that contains a β-phase NiAl intermetallic compound, and which is configured such that ammonia contacts the modified layer (12). The ammonia contact part (10) includes a metallic base material (11), and the modified layer (12) may cover the metallic base material (11).

Description

Ammonia handling device and manufacturing method thereof

[0001] The present disclosure relates to an ammonia handling apparatus and a method for manufacturing the same.

[0002] Ammonia does not contain carbon in its molecules and does not produce carbon dioxide when burned. Therefore, efforts are being made to use ammonia as a fuel to reduce carbon dioxide emissions into the atmosphere. However, ammonia is known to react with metals to form nitride compounds.

[0003] Patent Document 1 discloses a method for denitrifying exhaust gases, in which ammonia is injected from an ammonia injector into high-temperature exhaust gases containing nitrogen oxides and having a temperature of 480°C or higher, and catalytic reduction is carried out using a denitrification catalyst. The ammonia injector has an Fe-Al alloy layer containing 25 to 30% aluminum formed on the surface of a steel material.

[0004] Japanese Unexamined Patent Publication No. 6-114236

[0005] However, the Fe—Al alloy layer used in the prior art may not be able to sufficiently suppress nitridation in an environment with a high ammonia concentration. Because nitride compounds are hard and brittle, for example, nitridation of metals may result in a deterioration in the mechanical properties of the metal.

[0006] Therefore, an object of the present disclosure is to provide an ammonia handling apparatus capable of suppressing nitridation due to ammonia, and a method for manufacturing the same.

[0007] The ammonia handling device according to the present disclosure includes a reforming layer containing a β-phase NiAl intermetallic compound, and an ammonia contact portion configured to allow ammonia to contact the reforming layer.

[0008] The ammonia contacting portion may include a metal substrate, and the modified layer may cover the metal substrate.

[0009] The metal substrate is nickel or a nickel alloy.

[0010] The ammonia contacting the reforming layer may be at a temperature of 200°C or higher.

[0011] The ammonia handling device may be an ammonia-fired gas turbine, an ammonia-fired boiler, an ammonia-fired furnace, an ammonia fuel cell device, an ammonia-fired engine, an ammonia synthesis device, or a component included therein.

[0012] In the method for manufacturing an ammonia handling apparatus according to the present disclosure, the reformed layer is formed by diffusing aluminum into nickel or a nickel alloy.

[0013] According to the present disclosure, it is possible to provide an ammonia handling apparatus capable of suppressing nitridation due to ammonia, and a method for manufacturing the same.

[0014] FIG. 1 is a schematic diagram showing an ammonia handling apparatus according to an embodiment. FIG. 2 is a schematic diagram showing an ammonia-combustion gas turbine according to an embodiment. FIG. 3 is a schematic diagram showing an ammonia-combustion boiler according to an embodiment. FIG. 4 is a schematic diagram showing an ammonia fuel cell apparatus according to an embodiment. FIG. 5 is a schematic diagram showing an ammonia-fired engine according to an embodiment. FIG. 6 is a schematic diagram showing an ammonia synthesis apparatus according to an embodiment. FIG. 7 is an SEM (scanning electron microscope) image showing that the EDS (energy dispersive X-ray spectroscopy) measurement point is position A close to the outer surface of the reformed layer. FIG. 8 is an SEM image showing that the EDS measurement point is position B close to the metal substrate of the reformed layer. FIG. 9 is a graph comparing the nitride layer depth between the examples and the comparative examples.

[0015] Hereinafter, several exemplary embodiments will be described with reference to the drawings. Note that the dimensional proportions of the drawings are exaggerated for the convenience of explanation and may differ from the actual proportions.

[0016] As shown in Fig. 1, the ammonia handling apparatus 1 includes an ammonia contact section 10. The ammonia contact section 10 includes a metal substrate 11 and a modified layer 12 that covers the metal substrate 11 and contains a β-phase NiAl intermetallic compound. The ammonia contact section 10 is configured so that ammonia comes into contact with the modified layer 12.

[0017] The metal substrate 11 is not particularly limited, but may be, for example, nickel, iron, magnesium, aluminum, or an alloy containing these elements. As will be described later, when the modified layer 12 is formed by a diffusion and penetration treatment, the metal substrate 11 is preferably nickel or a nickel alloy.

[0018] The nickel alloy may be an alloy in which nickel is the most abundant by weight. The nickel alloy may also contain 50 wt% or more of nickel. The nickel alloy may contain iron and chromium, and optionally at least one element selected from the group consisting of carbon, silicon, manganese, phosphorus, sulfur, nickel, molybdenum, cobalt, copper, tungsten, aluminum, titanium, niobium, tantalum, vanadium, rhenium, zirconium, boron, and nitrogen, with the balance being nickel and unavoidable impurities. The unavoidable impurities may be elements other than those listed above, including the optional elements listed above. The total amount of unavoidable impurities contained in the nickel alloy may be 0.5 wt% or less, or 0.10 wt% or less. The content of each element of the unavoidable impurities contained in the nickel alloy may be 0.05 wt% or less, or 0.01 wt% or less.

[0019] The iron content of the nickel alloy may be 1 wt% or more and 25 wt% or less, 3 wt% or more, or 5 wt% or more, or 20 wt% or less, 16 wt% or less, or 12 wt% or less.

[0020] The chromium content of the nickel alloy may be 1 wt% or more and 35 wt% or less. The chromium content of the nickel alloy may be 4 wt% or more, 8 wt% or more, or 12 wt% or more. The chromium content of the nickel alloy may be 30 wt% or less, 25 wt% or less, or 20 wt% or less.

[0021] The modified layer 12 covers the metal substrate 11. The modified layer 12 may cover the surface of the metal substrate 11 and be in direct contact with the metal substrate 11. Alternatively, an intervening layer (not shown), such as a platinum layer, may be provided between the metal substrate 11 and the modified layer 12, so that the modified layer 12 is in indirect contact with the metal substrate 11. The modified layer 12 is disposed between the metal substrate 11 and ammonia. The modified layer 12 may cover at least a portion of the metal substrate 11 so as to prevent the metal substrate 11 from coming into contact with ammonia.

[0022] However, if there is a portion in the ammonia contact section 10 where the reactivity between the metal substrate 11 and ammonia is low, such as when the temperature of ammonia or the concentration of ammonia is low, the metal substrate 11 does not need to be covered with the modified layer 12 in that portion. That is, the modified layer 12 may cover only the portion of the metal substrate 11 where the reactivity between the metal substrate 11 and ammonia is high. Therefore, the modified layer 12 may cover only a portion of the metal substrate 11, or may cover the entire surface of the metal substrate 11. The modified layer 12 may be disposed on the outermost surface of the ammonia contact section 10. Furthermore, a ceramic layer (not shown) or the like may be provided on the surface of the modified layer 12 opposite to the metal substrate 11.

[0023] The modified layer 12 contains a β-phase NiAl intermetallic compound. The β-phase NiAl intermetallic compound has a higher effect of suppressing nitridation by ammonia than an intermetallic compound of iron and aluminum. The β-phase NiAl intermetallic compound also has a higher effect of suppressing nitridation by ammonia than an intermetallic compound of iron and aluminum. ３ The β-phase NiAl intermetallic compound has a higher effect of suppressing nitridation by ammonia than the β-phase NiAl intermetallic compound. The β-phase NiAl intermetallic compound has a higher effect of suppressing nitridation by ammonia and is not easily nitrided even when in contact with ammonia. Therefore, by covering the metal substrate 11 with the modified layer 12, nitridation of the metal substrate 11 can be suppressed. The modified layer 12 may be a single layer of the β-phase NiAl intermetallic compound.

[0024] In the modified layer 12, the ratio of the number of aluminum atoms to the total number of nickel and aluminum atoms is preferably 25% or more and 60% or less. When the aluminum content is within this range, a β-phase NiAl intermetallic compound can be generated in the modified layer 12. In the modified layer 12, the ratio of the number of aluminum atoms to the total number of nickel and aluminum atoms may be 30% or more, 35% or more, or 40% or more. In addition, in the modified layer 12, the ratio of the number of aluminum atoms to the total number of nickel and aluminum atoms may be 55% or less. Note that the content of the β-phase NiAl intermetallic compound in the modified layer 12 may be 50% or more, 60% or more, 70% or more, or 80% or more in atomic ratio.

[0025] In addition to nickel and aluminum, the modified layer 12 may contain elements contained in the metal substrate 11. For example, in addition to nickel and aluminum, the modified layer 12 may contain at least one element selected from the group consisting of carbon, silicon, manganese, phosphorus, sulfur, molybdenum, cobalt, copper, tungsten, titanium, niobium, tantalum, vanadium, rhenium, zirconium, boron, and nitrogen. Furthermore, in addition to nickel and aluminum, the modified layer 12 may contain a platinum group element such as platinum.

[0026] The thickness of the modified layer 12 is preferably 10 μm or more and 100 μm or less. When the thickness of the modified layer 12 is 10 μm or more, nitriding can be more reliably suppressed. Furthermore, when the thickness of the modified layer 12 is 100 μm or less, the modified layer 12 can be easily formed on the metal substrate 11. The thickness of the modified layer 12 may be 15 μm or more, 20 μm or more, or 25 μm or more. Furthermore, the thickness of the modified layer 12 may be 80 μm or less, 60 μm or less, or 40 μm or less.

[0027] In the manufacturing method of the ammonia handling apparatus 1, the reformed layer 12 can be formed by diffusing and penetrating aluminum into nickel or a nickel alloy using a diffusion and penetration process such as a pack process, a vapor phase process, or a slurry process. For example, when forming the reformed layer 12 using a pack process, the aluminum concentration and thickness of the reformed layer 12 can be adjusted by adjusting the concentration of aluminum or aluminum alloy powder and the treatment time. The reformed layer 12 can also be formed on the surface of the metal substrate 11 by methods such as thermal spraying, build-up welding, plating, and powder spraying. When forming the reformed layer 12 using these methods, the metal substrate 11 is not particularly limited and may be a metal other than nickel or a nickel alloy.

[0028] After the modified layer 12 is formed on the metal substrate 11, heat treatment may be performed. The conditions for the heat treatment are not particularly limited as long as a β-phase NiAl intermetallic compound can be generated, and may be, for example, 850°C or higher and 1100°C or lower. Setting the heat treatment temperature to 850°C or higher facilitates the generation of NiAl intermetallic compounds. Setting the heat treatment temperature to 1100°C or lower reduces the impact on the metal substrate 11. The heat treatment time may be, for example, 0.5 hours or longer. Setting the heat treatment time to 0.5 hours or longer increases the thickness of the modified layer 12. In the case of diffusion and penetration treatment, the thickness of the modified layer 12 tends to increase as the heat treatment time increases. However, once a certain thickness is achieved, the thickness of the modified layer 12 does not depend significantly on the time, even if the heat treatment time is extended. Therefore, from the viewpoint of manufacturing efficiency, the upper limit of the heat treatment time may be 12 hours or shorter, 8 hours or shorter, or 6 hours or shorter.

[0029] In this embodiment, an example has been described in which the ammonia contact unit 10 includes a metal substrate 11 and a modified layer 12. However, the ammonia contact unit 10 does not necessarily have to include a metal substrate 11. Even if the ammonia contact unit 10 does not include a metal substrate 11, the modified layer 12 can suppress nitridation by ammonia. An ammonia contact unit 10 that does not include a metal substrate 11 can be manufactured, for example, by melting a NiAl alloy. Alternatively, an ammonia contact unit 10 that does not include a metal substrate 11 can be obtained by forming a modified layer 12 on the surface of a temporary substrate by a method such as powder spraying as described above, and then removing the temporary substrate. Such an ammonia contact unit 10 may be subjected to heat treatment after forming the modified layer 12, as described above.

[0030] The ammonia contact unit 10 is configured so that ammonia comes into contact with the reformed layer 12. Because the reformed layer 12 can suppress nitridation by ammonia even at high temperatures, the ammonia that comes into contact with the reformed layer 12 may be at 200°C or higher. The ammonia that comes into contact with the reformed layer 12 may be at 300°C or higher, 400°C or higher, or 500°C or higher. The ammonia that comes into contact with the reformed layer 12 may be at 1000°C or lower, for example.

[0031] Next, the ammonia handling apparatus 1 will be described. The ammonia handling apparatus 1 according to this embodiment may be an ammonia combustion gas turbine, an ammonia combustion boiler, an ammonia combustion furnace, an ammonia fuel cell apparatus, an ammonia-fired engine, an ammonia synthesis apparatus, or a component included therein. Each ammonia handling apparatus 1 will be described in detail below.

[0032] (Ammonia combustion gas turbine) First, an example will be described in which the ammonia handling apparatus 1 is an ammonia combustion gas turbine 100. Fig. 2 is a schematic diagram showing the ammonia combustion gas turbine 100 according to one embodiment. As shown in Fig. 2, the ammonia combustion gas turbine 100 according to this embodiment includes a compressor 110, a combustion device 120, and a turbine 130.

[0033] The compressor 110 takes in external air, compresses it, and supplies the compressed air to the combustion device 120. The compressor 110 is mechanically connected to the generator G and the turbine 130 via a rotating shaft 111.

[0034] The combustion device 120 burns fuel containing ammonia using the air sent from the compressor 110 to generate combustion gas. The combustion device 120 includes a burner 121, a liner 126, a transition piece 127, and a casing 128.

[0035] The burner 121 injects ammonia into the combustion chamber 140 and burns the ammonia. The burner 121 includes a supply pipe 122, a nozzle 123, an air supplier 124, and a liner head 125. The supply pipe 122 is connected to the nozzle 123, and fuel containing ammonia is supplied to the nozzle 123 from a fuel tank (not shown) via the supply pipe 122. The nozzle 123 injects the fuel containing ammonia into the combustion chamber 140. The air supplier 124 supplies air sent from the compressor 110 through an air flow path 141 into the combustion chamber 140. The liner head 125 is an upstream end wall that constitutes the combustion chamber 140. The burner 121 combusts the fuel injected into the combustion chamber 140 to generate combustion gas.

[0036] The combustion chamber 140 is formed by members including a liner 126 and a transition piece 127. The burner 121 is connected to the front end of the liner 126. The transition piece 127 is connected to the rear end of the liner 126 opposite the burner 121. The transition piece 127 connects the rear end of the liner 126 to an inlet of the turbine 130. Combustion gas generated in the combustion chamber 140 by the burner 121 is supplied to the turbine 130 via the transition piece 127.

[0037] The turbine 130 includes turbine blades (not shown), which are rotated by the passage of combustion gas generated in the combustion device 120. The turbine blades of the turbine 130 are mechanically connected to the compressor 110 via a rotary shaft 111. Therefore, the rotation of the turbine blades promotes the rotation of the compressor 110, which drives the generator G to generate electricity.

[0038] Here, ammonia before combustion or unburned ammonia at a high temperature of, for example, 200° C. or higher passes through the supply pipe 122, the nozzle 123, the liner head 125, the liner 126, the transition piece 127, and the turbine 130. When ammonia comes into contact with the metal materials that make up these components, nitrides may be generated.

[0039] Therefore, the ammonia-burning gas turbine 100 is equipped with an ammonia contact unit 10. Specifically, the components included in the ammonia-burning gas turbine 100, namely, a supply pipe 122, a nozzle 123, a liner head 125, a liner 126, a transition piece 127, and a turbine 130, are equipped with the ammonia contact unit 10. The ammonia contact unit 10 includes a modified layer 12 containing a β-phase NiAl intermetallic compound, and is configured so that ammonia comes into contact with the modified layer 12. Therefore, the ammonia contact unit 10 can suppress nitriding by ammonia.

[0040] (Ammonia combustion boiler) Next, the ammonia combustion boiler 200 according to this embodiment will be described with reference to Fig. 3. As shown in Fig. 3, the ammonia combustion boiler 200 according to this embodiment includes a furnace 210, a combustion gas horizontal movement section 220, a combustion gas descending section 230, and a burner 240.

[0041] The furnace 210 extends in the vertical direction, and the combustion gas horizontal transfer section 220 is connected to the upper part of the furnace 210, which is on the downstream side of the furnace 210. The combustion gas horizontal transfer section 220 extends horizontally from the upper part of the furnace 210. The combustion gas descending section 230 is on the downstream side of the combustion gas horizontal transfer section 220, and is connected to the end of the combustion gas horizontal transfer section 220 on the opposite side from the furnace 210. The combustion gas descending section 230 extends downward from the end of the combustion gas horizontal transfer section 220, and discharges the combustion gas generated in the furnace 210 to the outside.

[0042] A plurality of burners 240 are provided on the wall of the lower part of the furnace 210. The burners 240 include nozzles and inject fuel containing ammonia into the furnace 210. The fuel injected from the burners 240 is combusted in the furnace 210 to generate high-temperature combustion gas. In addition to ammonia, the fuel may also include a carbonaceous fuel such as pulverized coal.

[0043] Here, ammonia before combustion or unburned ammonia at a high temperature of 200° C. or higher passes through the furnace 210, the combustion gas horizontal transfer section 220, the combustion gas descending section 230, and the burner 240. When ammonia comes into contact with the metal materials that make up these sections, nitrides may be produced.

[0044] Therefore, the ammonia combustion boiler 200 is equipped with an ammonia contact section 10. Specifically, the components included in the ammonia combustion boiler 200, that is, the furnace 210, the combustion gas horizontal transfer section 220, the combustion gas descending section 230, and the burner 240, are equipped with the ammonia contact section 10. The ammonia contact section 10 includes a reformed layer 12 containing a β-phase NiAl intermetallic compound, and is configured so that ammonia comes into contact with the reformed layer 12. Therefore, the ammonia contact section 10 can suppress nitridation by ammonia.

[0045] (Ammonia Combustion Furnace) Similar to the ammonia combustion boiler 200, an ammonia combustion furnace such as an industrial furnace also includes a burner. Ammonia before combustion or unburned ammonia at a high temperature of 200° C. or higher passes through the furnace and the burner. When ammonia comes into contact with the metal materials that make up these, nitrides may be generated.

[0046] Therefore, the ammonia combustion furnace is equipped with an ammonia contact unit 10. Specifically, the furnace and burner, which are components included in the ammonia combustion furnace, are equipped with the ammonia contact unit 10. The ammonia contact unit 10 includes a modified layer 12 containing a β-phase NiAl intermetallic compound, and is configured so that ammonia comes into contact with the modified layer 12. Therefore, the ammonia contact unit 10 can suppress nitridation by ammonia.

[0047] (Ammonia fuel cell device) Next, an ammonia fuel cell device 300 according to this embodiment will be described with reference to Fig. 4. As shown in Fig. 4, the ammonia fuel cell device 300 includes a fuel cell main body 310, an ammonia decomposer 320, and a heat exchanger 330.

[0048] The fuel cell body 310 includes an anode 311, an air electrode 312, and an electrolyte 313. The fuel cell body 310 according to this embodiment is an SOFC. At the anode 311, hydrogen is oxidized to generate anode off-gas containing water (water vapor). At the electrolyte 313, oxygen ions (O ２－ ) moves from the air electrode 312 to the fuel electrode 311. At the air electrode 312, the oxygen ions are reduced to generate a cathode off-gas containing oxygen.

[0049] A fuel supply pipe 314 is connected to the inlet of the anode 311, and hydrogen is supplied to the anode 311. An ammonia decomposer 320 and a heat exchanger 330 are provided in the fuel supply pipe 314. Ammonia is supplied from a tank (not shown) containing ammonia to the ammonia decomposer 320 and the heat exchanger 330, and ammonia is decomposed to produce hydrogen. An anode exhaust pipe 315 is connected to the outlet of the anode 311, and anode off-gas generated at the anode 311 is exhausted from the fuel cell main body 310. A heat exchanger 330 is provided in the anode exhaust pipe 315. A cathode exhaust pipe 316 is connected to the outlet of the air electrode 312, and cathode off-gas generated at the air electrode 312 is exhausted from the fuel cell main body 310. The cathode exhaust pipe 316 is provided with the heat exchanger 330.

[0050] The ammonia decomposer 320 decomposes ammonia to generate hydrogen. The ammonia decomposer 320 contains an ammonia decomposition catalyst, such as a ruthenium catalyst or a nickel catalyst, in a container, and decomposes ammonia into hydrogen and nitrogen by contacting the ammonia with the catalyst at a temperature of, for example, 400° C. to 800° C.

[0051] The heat exchanger 330 is connected to the fuel supply pipe 314, the anode exhaust pipe 315, and the cathode exhaust pipe 316. The heat exchanger 330 exchanges the heat of the anode off-gas discharged from the fuel electrode 311 and the heat of the cathode off-gas discharged from the air electrode 312 with the heat of the fuel supplied to the fuel electrode 311 from the ammonia decomposer 320 via the fuel supply pipe 314. The fuel contains ammonia that was not decomposed in the ammonia decomposer 320, and the above-mentioned ammonia decomposition catalyst that decomposes ammonia is disposed in the flow path through which the fuel passes in the heat exchanger 330. Therefore, the heat exchanger 330 decomposes the ammonia remaining in the fuel to generate hydrogen.

[0052] Here, ammonia before combustion or unburned ammonia at high temperatures, such as 200° C. or higher, passes through the fuel cell main body 310, the ammonia decomposer 320, the heat exchanger 330, the fuel supply pipe 314, and the anode exhaust pipe 315. If ammonia comes into contact with the metal materials that make up these components, nitrides may be produced.

[0053] Therefore, the ammonia fuel cell device 300 is provided with an ammonia contactor 10. Specifically, the components included in the ammonia fuel cell device 300, namely the fuel cell main body 310, the ammonia decomposer 320, the heat exchanger 330, the fuel supply pipe 314, and the anode exhaust pipe 315, are provided with the ammonia contactor 10. The ammonia contactor 10 includes a reforming layer 12 containing a β-phase NiAl intermetallic compound, and is configured so that ammonia comes into contact with the reforming layer 12. Therefore, the ammonia contactor 10 can suppress nitridation by ammonia.

[0054] (Ammonia-fired engine) Next, the ammonia-fired engine 400 will be described with reference to Fig. 5. As shown in Fig. 5, the ammonia-fired engine 400 includes a cylinder block 410, a cylinder head 420, and a piston 430. The cylinder block 410 has a cylinder 411. The piston 430 is disposed within the cylinder 411. A combustion chamber 440 is disposed within the cylinder 411, between the cylinder head 420 and the piston 430.

[0055] The cylinder head 420 is provided with an injection unit 421 that injects fuel containing ammonia into the combustion chamber 440. The cylinder head 420 has an intake port 422 and an exhaust port 423 that communicate with the combustion chamber 440. The cylinder head 420 is provided with an intake valve 424 that can open and close the intake port 422 of the cylinder head 420 from the combustion chamber 440 side. When the intake valve 424 is opened, air is supplied to the combustion chamber 440 through the intake port 422. The cylinder head 420 is also provided with an exhaust valve 425 that can open and close the exhaust port 423 of the cylinder head 420 from the combustion chamber 440 side. When the exhaust valve 425 is opened, exhaust gas generated by combustion of the fuel in the combustion chamber 440 is discharged to the outside of the ammonia-fired engine 400 through the exhaust port 423.

[0056] Here, ammonia before combustion or unburned ammonia at a high temperature of 200° C. or higher passes through the cylinder 411, the exhaust port 423, the intake valve 424, the exhaust valve 425, and the piston 430. When ammonia comes into contact with the metal materials that make up these components, nitrides may be generated.

[0057] Therefore, the ammonia-fired engine 400 is provided with an ammonia contact unit 10. Specifically, the components included in the ammonia-fired engine 400, such as the cylinder 411, the exhaust port 423, the intake valve 424, the exhaust valve 425, and the piston 430, are provided with the ammonia contact unit 10. The ammonia contact unit 10 includes a modified layer 12 containing a β-phase NiAl intermetallic compound, and is configured so that ammonia comes into contact with the modified layer 12. Therefore, the ammonia contact unit 10 can suppress nitridation by ammonia.

[0058] (Ammonia synthesis apparatus) Next, the ammonia synthesis apparatus 500 will be described with reference to Fig. 6. As shown in Fig. 6, the ammonia synthesis apparatus 500 includes a raw material supply unit 510 and a reactor 520.

[0059] The raw material supply unit 510 supplies nitrogen and hydrogen, which are raw materials for ammonia, to the reactor 520. In this embodiment, the raw material supply unit 510 supplies a mixed raw material containing ammonia and nitrogen to the reactor 520 via a raw material supply pipe 530. The raw material supply unit 510 may include an ammonia supply unit that supplies ammonia to the reactor 520 and a nitrogen supply unit that supplies nitrogen to the reactor 520.

[0060] The reactor 520 produces ammonia from a raw material containing nitrogen and hydrogen supplied from the raw material supply unit 510. The reactor 520 contains an ammonia catalyst structure 525 that produces ammonia from nitrogen and hydrogen. The production of ammonia is promoted by contacting the raw material containing nitrogen and hydrogen with the ammonia catalyst structure 525. The type of the reactor 520, the reaction conditions within the reactor 520, and the like are not particularly limited. The ammonia produced in the reactor 520 is discharged from the reactor 520 through a discharge pipe 531.

[0061] The ammonia catalyst structure 525 includes a catalyst such as an iron-based catalyst, a metal carrier that supports the catalyst, and a metal casing that houses the catalyst and the metal carrier.

[0062] Here, ammonia before combustion or unburned ammonia at a high temperature of 200° C. or higher passes through the reactor 520, the ammonia catalyst structure 525, and the exhaust pipe 531. If ammonia comes into contact with the metal materials that make up these components, nitrides may be produced.

[0063] Therefore, the ammonia synthesis apparatus 500 is provided with an ammonia contact unit 10. Specifically, the reactor 520, which is a component included in the ammonia synthesis apparatus 500, the metal carrier and metal casing included in the ammonia catalyst structure 525, and the discharge pipe 531 are provided with the ammonia contact unit 10. The ammonia contact unit 10 includes a reforming layer 12 containing a β-phase NiAl intermetallic compound, and is configured so that ammonia comes into contact with the reforming layer 12. Therefore, the ammonia contact unit 10 can suppress nitridation by ammonia.

[0064] As described above, the ammonia handling apparatus 1 according to this embodiment includes the reforming layer 12 containing the β-phase NiAl intermetallic compound, and is equipped with the ammonia contact section 10 configured so that ammonia comes into contact with the reforming layer 12.

[0065] The β-phase NiAl intermetallic compound has a high effect of suppressing nitridation by ammonia and is not easily nitrided even when in contact with ammonia. Therefore, the ammonia handling apparatus 1 according to this embodiment can suppress nitridation by ammonia.

[0066] Hereinafter, the present embodiment will be described in more detail with reference to the following examples, but the present embodiment is not limited to the following examples.

[0067] (Example) First, a nickel alloy of ALLOY600 was prepared. ALLOY600 is an alloy containing 16 wt% Cr and 8 wt% Fe, with the remainder being Ni and unavoidable impurities. Also, a mixed powder containing aluminum alloy powder, alumina as a sintering inhibitor, and ammonium chloride as an activator was prepared.

[0068] Next, the nickel alloy was buried in the mixed powder and heated at around 900°C for about 1.5 hours, and a diffusion and penetration treatment was carried out by pack cementation to diffuse aluminum into the surface of the nickel alloy, thereby obtaining a sample according to this example.

[0069] The cross section of the sample according to this example was observed with an SEM and subjected to elemental analysis by EDS. Figure 7 is an SEM image showing that the EDS measurement point was position A, which is close to the outer surface of the modified layer. Figure 8 is an SEM image showing that the EDS measurement point was position B, which is close to the metal substrate of the modified layer. Table 1 shows the EDS measurement results at position A. Table 2 shows the EDS measurement results at position B.

[0070]

[0071]

[0072] 7 and 8 confirmed that a modified layer approximately 30 μm thick was formed on the surface of the metal substrate by the diffusion and penetration treatment. Table 1 revealed that at position A, the ratio of the number of aluminum atoms to the total number of nickel and aluminum atoms was approximately 47%. Table 2 also revealed that at position B, the ratio of the number of aluminum atoms to the total number of nickel and aluminum atoms was approximately 43%. The ratio of the number of aluminum atoms to the total number of nickel and aluminum atoms was also higher at position A than at position B. The atomic ratio of aluminum to nickel in the modified layer was approximately 1:1, indicating that the modified layer contained a β-phase NiAl intermetallic compound. Furthermore, FIGS. 7 and 8 confirmed the presence of two separate layers, the metal substrate and the modified layer, and that the modified layer was homogeneous, indicating that the modified layer was a single β-phase phase, with iron and chromium solid-solubilized in NiAl.

[0073] Comparative Example 1 A sample was obtained in the same manner as in Example, except that the nickel alloy ALLOY600 was replaced with SUS310S stainless steel containing 25 wt % Cr and 20 wt % Ni, with the remainder being Fe and unavoidable impurities.

[0074] Comparative Example 2 The ALLOY 600 used in the example was used as a sample for this example, without being subjected to the diffusion and penetration treatment.

[0075] Comparative Example 3: ALLOY 738LC was used as the sample without diffusion coating. ALLOY 738LC contained 8.5 wt% cobalt, 16.0 wt% chromium, 1.8 wt% molybdenum, 2.6 wt% tungsten, 1.8 wt% tantalum, 3.4 wt% aluminum, 3.4 wt% titanium, 0.9 wt% niobium, 0.10 wt% carbon, 0.010 wt% boron, and 0.060 wt% zirconium, with the balance being nickel and unavoidable impurities. ALLOY 738LC is a nickel alloy with an aluminum atomic ratio of approximately 11% to the total number of nickel and aluminum atoms, and is known to contain γ and γ' phases. Unlike the samples of the Examples, with this aluminum ratio, no β phase appears.

[0076] [Evaluation] (Ammonia Exposure Test) The sample obtained as described above was exposed to an ammonia-saturated state at 500°C for 100 hours. After the ammonia exposure test, the sample was cut, and the depth of the nitride layer on the cut surface was observed with an optical microscope. The results are shown in Figure 9.

[0077] As shown in FIG. 9 , the sample of Comparative Example 1 showed slightly less nitriding than the sample of Comparative Example 2, or almost the same degree. Meanwhile, the sample of Comparative Example 3 showed less nitriding than the samples of Comparative Examples 1 and 2, but the sample according to the Example showed even more nitriding suppression, with the nitride layer depth below the detection limit. These results demonstrate that Ni-Al intermetallic compounds can suppress nitriding caused by ammonia compared to Fe-Al intermetallic compounds. Furthermore, β-phase NiAl intermetallic compounds can further suppress nitriding caused by ammonia compared to γ-phase and γ'-phase. These results suggest that even when exposed to a high-temperature ammonia environment, nitriding caused by ammonia can be suppressed by the formation of a dense aluminum nitride layer in the β-phase.

[0078] The entire contents of Japanese Patent Application No. 2023-073374 (filing date: April 27, 2023) are incorporated herein by reference.

[0079] Although several embodiments have been described, the embodiments can be modified or varied based on the above disclosure. All components of the above embodiments and all features described in the claims may be individually extracted and combined, unless they contradict each other.

[0080] REFERENCE SIGNS LIST 1 ammonia handling device 10 ammonia contact portion 11 metal substrate 12 modified layer

Claims

1. An ammonia handling apparatus comprising: a modified layer including a β-phase NiAl intermetallic compound; and an ammonia contact portion configured to allow ammonia to contact the modified layer.

2. the ammonia contact portion includes a metal substrate; 10. The ammonia handling apparatus of claim 1, wherein the modified layer covers the metal substrate.

3. 3. The ammonia handling apparatus of claim 2, wherein the metal substrate is nickel or a nickel alloy.

4. 4. The ammonia handling apparatus according to claim 1, wherein the ammonia contacting the reforming layer is at a temperature of 200° C. or higher.

5. The ammonia handling apparatus according to any one of claims 1 to 3, wherein the ammonia handling apparatus is an ammonia combustion gas turbine, an ammonia combustion boiler, an ammonia combustion furnace, an ammonia fuel cell apparatus, an ammonia-fired engine, an ammonia synthesis apparatus, or a component included therein.

6. A method for manufacturing an ammonia handling apparatus according to any one of claims 1 to 3, The method for manufacturing an ammonia handling apparatus, wherein the modified layer is formed by diffusing aluminum into nickel or a nickel alloy.