Ammonia production system and ammonia production method

Abstract

To improve the production efficiency of ammonia.SOLUTION: The ammonia manufacturing system includes the solid oxide electrolysis cell 10 to which the water vapor and the nitrogen-containing gas are supplied and which generates the hydrogen and the ammonia by the electrolysis reaction of the supplied gas, the water vapor supplying line L10 which guides the water vapor to the solid oxide electrolysis cell 10, the separation portion 60 to which the mixture gas containing the ammonia, the hydrogen, and the nitrogen gas discharged from the solid oxide electrolysis cell 10 is guided and which separates the hydrogen and the nitrogen gas contained in the mixture gas, and the circulating line L10 which guides the hydrogen and the nitrogen gas separated by the separation portion 60 to the water vapor supplying line L32.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to an ammonia production system and an ammonia production method. [Background technology]

[0002] Electrolysis cells, which produce hydrogen and oxygen by electrochemically decomposing water, are a hydrogen production method that does not involve carbon dioxide emissions and has excellent environmental properties. Among these, solid oxide electrolysis cells (SOECs) use ceramics such as yttria-stabilized zirconia as the electrolyte and can produce hydrogen more efficiently than other electrolysis cells because they use high-temperature steam as the feedstock. Furthermore, for the purpose of decarbonization, co-electrolysis is also possible, using carbon dioxide (CO2) as the feedstock and electrolytic hydrogen as the reducing agent to directly produce carbon monoxide (CO).

[0003] It has been proposed to generate ammonia gas in such an electrolytic cell via a reducing gas consisting of nitric oxide together with hydrogen (for example, Patent Document 1). Patent Document 1 describes a system for generating new hydrogen compounds such as ammonia via a reducing medium consisting of water vapor and nitric oxide, which is supplied to the hydrogen electrode side of the electrolytic cell and turns into a gas at the operating temperature. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2007-077464 Summary of the Invention [Problem to be solved by the invention]

[0005] High-temperature steam electrolysis in electrolytic cells allows for highly efficient hydrogen production, but the storage and transportation of the produced hydrogen requires the development of new technologies, infrastructure development, and cost reduction. Meanwhile, infrastructure for the storage and transportation of ammonia is already in place, and demonstration operations are underway as a carbon-free fuel at power plants. Therefore, directly recovering ammonia as a product of the electrolytic cell would enable more efficient production of ammonia as a hydrogen carrier.

[0006] One possible method for producing ammonia is to generate ammonia by co-electrolysis of water vapor and nitrogen in a solid oxide electrolysis cell. However, it is not possible to co-electrolyze all of the supplied water vapor and nitrogen, and therefore a mixed gas of nitrogen, hydrogen, ammonia, and water vapor is discharged from the solid oxide electrolysis cell. As such, the solid oxide electrolysis cell discharges unreacted nitrogen and water vapor as impurities in addition to ammonia and hydrogen, making it difficult to efficiently produce ammonia as a hydrogen carrier.

[0007] The present disclosure has been made in view of the above circumstances, and has an object to provide an ammonia production system and an ammonia production method that can improve the efficiency of ammonia production. [Means for solving the problem]

[0008] In order to solve the above problems, the ammonia production system and the ammonia production method of the present disclosure employ the following measures. An ammonia production system according to one aspect of the present disclosure includes a solid oxide electrolysis cell that is supplied with a gas containing water vapor and nitrogen and produces hydrogen and ammonia through an electrolytic reaction of the supplied gas; a water vapor supply line that introduces water vapor to the solid oxide electrolysis cell; a separation unit that introduces a mixed gas containing ammonia, hydrogen, and nitrogen discharged from the solid oxide electrolysis cell and separates the hydrogen and nitrogen contained in the mixed gas; and a circulation line that introduces the hydrogen and nitrogen separated in the separation unit to the water vapor supply line.

[0009] An ammonia production method according to one aspect of the present disclosure is an ammonia production method in which ammonia is produced in an ammonia production system, the ammonia production system comprising: a solid oxide electrolysis cell to which hydrogen, nitrogen, and water vapor are supplied, and which performs a co-electrolysis reaction of hydrogen generated by electrolyzing the supplied water vapor with the supplied nitrogen; a water vapor supply line that introduces water vapor to the solid oxide electrolysis cell; and a separation unit to which a mixed gas containing ammonia, water vapor, hydrogen, and nitrogen discharged from the solid oxide electrolysis cell is introduced and which separates the hydrogen and nitrogen contained in the mixed gas, and the ammonia production system comprises a circulation step of introducing the gas containing hydrogen and nitrogen separated in the separation unit to the water vapor supply line. [Effects of the Invention]

[0010] According to the present disclosure, it is possible to improve the efficiency of ammonia production. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is a schematic configuration diagram illustrating a hydrogen production system according to an embodiment of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0012] Hereinafter, an embodiment of an ammonia production system and an ammonia production method according to the present disclosure will be described with reference to the drawings.

[0013] As shown in FIG. 1 , an ammonia production system 1 according to this embodiment includes a solid oxide electrolysis cell (SOEC) 10, a water vapor supply unit 20 that supplies water vapor to the SOEC 10, a power supply device 40 that supplies power to the SOEC 10, an air supply unit 50 that supplies air to the SOEC 10, a separation unit 60 that separates nitrogen and hydrogen from a mixed gas discharged from the SOEC 10, a nitrogen supply device 80 that supplies nitrogen to the water vapor that is supplied to the SOEC 10, and a hydrogen supply device 90 that supplies hydrogen to the water vapor that is supplied to the SOEC 10.

[0014] The SOEC 10 has a hydrogen electrode (not shown) and an oxygen electrode (not shown). A high-temperature, high-pressure oxidizing gas (air, as an example, in this embodiment) is supplied to the oxygen electrode side of the SOEC 10, and high-temperature, high-pressure steam is supplied to the hydrogen electrode side. The SOEC 10 may also include a cell consisting of the hydrogen electrode and the oxygen electrode, a steam electrolysis chamber (not shown) having a plurality of cells, a steam supply header (not shown), a product gas discharge header (not shown), an oxidizing gas supply header (not shown), and an oxidizing gas discharge header (not shown).

[0015] By applying a negative voltage to the hydrogen electrode and a positive voltage to the oxygen electrode, the water vapor contained in the supplied steam receives electrons at the hydrogen electrode and is electrolyzed to generate hydrogen molecules and oxygen ions (O2-) (see reaction formula (1) below). The generated hydrogen is extracted to the outside together with the supplied steam. In addition, in the SOEC 10, hydrogen and nitrogen produced on the hydrogen electrode side undergo a co-electrolytic reaction to produce ammonia gas (see reaction formula (2) below).

[0016] Meanwhile, the oxygen ions pass through the solid electrolyte membrane (not shown) due to the potential difference, move to the oxygen electrode, release electrons, and become oxygen molecules (see reaction formula (3) below). The generated oxygen is discharged to the outside together with the oxidizing gas supplied to the oxygen electrode. H2O+2e- → H2+O2- (1) 3H2+N2→2NH3 (2) 2O2- → O2 + 4e- (3)

[0017] The electrolysis of water vapor in the SOEC10 is an endothermic reaction. Furthermore, at the hydrogen electrode of the SOEC10, the coexistence of the produced hydrogen and nitrogen causes a co-electrolysis reaction, producing ammonia. In terms of chemical equilibrium in equation (2), a high-pressure, low-temperature state is desirable for the production of ammonia. On the other hand, from the perspective of improving the energy efficiency of the electrolysis in the SOEC10 and promoting the ammonia production reaction, it is desirable for the supplied mixed gas to be in a high-temperature state.

[0018] Furthermore, the amount of hydrogen (hydrogen generated by the above reaction formula (1) and circulated hydrogen, which will be described later) and the amount of nitrogen required in the SOEC 10 for the production of ammonia (the above reaction formula (2)) are determined by controlling the flow rates of steam supplied from the steam supply unit 20 and nitrogen supplied from the nitrogen supply device 80, which will be described later, in accordance with the amount of ammonia produced, and by appropriately setting the composition of the raw material gases, such as steam, nitrogen, and hydrogen, and the reaction temperature and pressure for ammonia synthesis.

[0019] The water vapor supply unit 20 supplies water vapor to the SOEC 10. The water vapor supply unit 20 and the SOEC 10 are connected by a water vapor supply line L10.

[0020] The nitrogen supply device 80 includes a nitrogen supply unit 81, a nitrogen line L11 connecting the nitrogen supply unit 81 and the water vapor supply line L10, and a flow rate control valve 82 provided on the nitrogen line L11. The nitrogen supply device 80 supplies nitrogen to the water vapor supply line L10. The nitrogen supply device 80 supplies nitrogen to the SOEC 10 via the water vapor supply line L10. The gas supplied from the nitrogen supply device 80 may be a nitrogen-containing gas (e.g., air).

[0021] The hydrogen supply device 90 includes a hydrogen supply unit 91, a hydrogen line L12 connecting the hydrogen supply unit 91 and the steam supply line L10, and a flow rate control valve 92 provided on the hydrogen line L12. The hydrogen supply device 90 supplies hydrogen to the steam supply line L10. The hydrogen supply device 90 supplies hydrogen to the SOEC 10 via the steam supply line L10. The hydrogen supply device 90 supplies hydrogen to the steam supply line L10 during system startup or emergency shutdown, thereby creating a reducing atmosphere for the gas supplied to the SOEC 10.

[0022] The air supply unit 50 supplies an oxidizing gas (air in this embodiment) to the SOEC 10. The air supply unit 50 and the SOEC 10 are connected by an air supply line L20. A flow rate adjustment valve 51 is provided on the air supply line L20.

[0023] The mixed gas discharged from the mixed gas line L30 of the SOEC 10 is introduced into the separation unit 60. The separation unit 60 separates hydrogen and nitrogen from the mixed gas. The separation unit 60 separates hydrogen and nitrogen by cooling the mixed gas and condensing the ammonia and water vapor contained in the mixed gas.

[0024] The separation unit 60 includes a first cooling unit 61 (cooling unit) that cools the mixed gas discharged from the mixed gas line L30 of the SOEC 10, a second cooling unit 62 that further cools the mixed gas cooled in the first cooling unit 61, and an ammonia separation facility 63 that separates condensed ammonia and condensed water vapor (water) from nitrogen and hydrogen. In addition, a reaction unit (not shown) that reacts hydrogen and nitrogen contained in the mixed gas at a temperature equal to or lower than the mixed gas outlet temperature of the SOEC 10 to produce ammonia may be provided upstream of the separation unit 60 (between the SOEC 10 and the separation unit 60) or between the first cooling unit 61 and the second cooling unit 62.

[0025] The first cooling section 61 exchanges heat between the mixed gas and a circulating medium (for example, water vapor). The first cooling section 61 cools the mixed gas and heats the circulating medium. The second cooling section 62 is provided downstream of the first cooling section 61 in the mixed gas flow. The second cooling section 62 exchanges heat between the mixed gas and a cooling medium (for example, steam or feed water). The second cooling section 62 cools the mixed gas and heats the cooling medium. The mixed gas is cooled in the first cooling section 61 and the second cooling section 62, whereby at least a portion of the ammonia and water vapor contained in the mixed gas is condensed. Therefore, a gas-liquid two-phase flow containing ammonia, water (condensed water and water vapor), hydrogen, and nitrogen flows into the ammonia separation equipment 63.

[0026] The ammonia separation equipment 63 is provided in the mixed gas flow downstream of the second cooling section 62. The ammonia separation equipment 63 separates the liquid condensed water and ammonia from the gaseous nitrogen and hydrogen.

[0027] The reaction section 64 may be provided upstream of the first cooling section 61 or between the first cooling section and the second cooling section in the mixed gas flow. The reaction section 64 can produce ammonia by reacting hydrogen and nitrogen through catalytic action even when the mixed gas has a temperature lower than the SOEC outlet temperature.

[0028] An ammonia water recovery line L31 is connected to the ammonia separation equipment 63. The ammonia water recovery line L31 supplies condensed ammonia water and condensed water to the outside of the system. In addition, a circulation line L32 is connected to the ammonia separation equipment 63. The circulation line L32 connects the ammonia separation equipment 63 to the steam supply line L10. The circulation line L32 guides the hydrogen and nitrogen separated in the ammonia separation equipment 63 and the ammonia and steam remaining as gas to the steam supply line (L10). The circulation line L32 is provided with a circulation blower 70, a heating unit 71, and a flow rate adjustment valve 72, in this order from the upstream side.

[0029] The heating section 71 heats the nitrogen and hydrogen using the heat recovered by the first cooling section 61. The heating section 71 exchanges heat between the nitrogen and hydrogen and the circulating medium. The heating section 71 heats the nitrogen and hydrogen and cools the refrigerant medium. The heating section 71 and the first cooling section 61 are connected by a circulating medium line L25. The circulating medium flows through the circulating medium line L25. Note that this heat exchange may be performed directly without using a heat medium.

[0030] Next, the flow of fluids in the ammonia production system 1 according to this embodiment will be described. Steam is introduced from the steam supply unit 20 into the steam supply line L10. The steam introduced into the steam supply line L10 flows through the steam supply line L10 and is supplied to the SOEC 10. At this time, hydrogen and nitrogen are supplied to the steam flowing through the steam supply line L10 via a circulation line L32. Note that, when a sufficient amount of hydrogen and nitrogen is not supplied to the steam flowing through the steam supply line L10 and supplied to the SOEC 10, such as during startup or emergency shutdown, hydrogen and nitrogen may be supplied from the nitrogen supply device 80 or the hydrogen supply device 90.

[0031] The gas flowing through the water vapor supply line L10 is supplied to the SOEC 10. The mixed gas supplied to the SOEC 10 is a mixture of water vapor, nitrogen, and hydrogen.

[0032] Power is supplied to the SOEC 10 from the power supply device 40 (power supply step).

[0033] High-temperature, high-pressure air is supplied to the SOEC 10 from the air supply unit 50. As described above, hydrogen and ammonia are produced in the SOEC 10. The mixed gas that has completed the reaction in the SOEC 10 flows into the mixed gas line L30. The mixed gas that has flowed into the mixed gas line L30 is led to the separation unit 60. The mixed gas discharged from the SOEC 10 contains unreacted water vapor and nitrogen in addition to hydrogen and ammonia.

[0034] On the other hand, the oxidizing gas discharged from the SOEC 10 is discharged to the outside of the ammonia production system 1 via an oxidizing gas discharge line L21.

[0035] The mixed gas discharged from the reaction section 64 is cooled in the first cooling section 61 and the second cooling section 62 of the separation section 60. At this time, the mixed gas is cooled to about 40°C. As a result, the water vapor and ammonia gas contained in the mixed gas are condensed to a saturated state at 40°C, separated from the gas phase components nitrogen and hydrogen, and recovered as ammonia water. The ammonia water is supplied to the outside of the ammonia production system 1 via the ammonia water recovery line L31.

[0036] Meanwhile, the nitrogen and hydrogen separated in the ammonia separation equipment 63 are introduced into the circulation line L32. The nitrogen and hydrogen flowing through the circulation line L32 are heated in a heating unit 71 and introduced into the steam supply line L10.

[0037] According to this embodiment, the following advantageous effects are achieved. In this embodiment, a circulation line L32 is provided that guides the hydrogen and nitrogen separated in the separation section 60 to the steam supply line L10. This allows the hydrogen and nitrogen to be returned to the inlet side of the SOEC 10 and supplied to the SOEC 10 again. Therefore, it is possible to reduce or eliminate the amount of hydrogen supplied to the SOEC 10 from a separately provided hydrogen supply device. Therefore, it is possible to reduce the size of the hydrogen supply device or eliminate the need for the hydrogen supply device, thereby reducing the equipment costs of the ammonia production system 1. Furthermore, it is possible to reduce or eliminate the amount of hydrogen supplied to the SOEC 10 from a separately provided hydrogen supply device, thereby reducing the operating costs.

[0038] Furthermore, it is possible to reduce the amount of nitrogen supplied to the SOEC 10 from a separately provided nitrogen supply device. Therefore, it is possible to reduce the size of the nitrogen supply device, thereby reducing the equipment cost of the ammonia production system 1. Furthermore, it is possible to reduce the amount of nitrogen supplied to the SOEC 10 from a separately provided nitrogen supply device, thereby reducing the operation cost.

[0039] Furthermore, if the hydrogen supplied from the circulation line L32 can eliminate the need to supply hydrogen from a separately provided hydrogen supply device, there is no need to supply hydrogen from outside the system. This eliminates the need to manage equipment outside the system, which can be complicated to manage, and makes it easier to manage the equipment for ammonia production.

[0040] In addition, unreacted nitrogen in the SOEC 10 is supplied again to the SOEC 10 via a circulation line L32. The nitrogen supplied again to the SOEC 10 is used to generate ammonia. Therefore, there is no need to supply and discharge excess nitrogen from outside the system, and the generation efficiency of the entire system can be improved.

[0041] In this embodiment, the separation unit 60 separates the hydrogen and nitrogen from the ammonia and water vapor by condensing the ammonia contained in the mixed gas in the first cooling unit 61 and the second cooling unit 62 that cool the mixed gas. This makes it possible to preferably separate the hydrogen and nitrogen from the ammonia and hydrogen.

[0042] Furthermore, this embodiment includes a heating unit 71 that heats the hydrogen and nitrogen introduced into the steam supply line L10, and the heating unit 71 recovers heat by heating the hydrogen and nitrogen using the exhaust heat of the first cooling unit 61. This improves the energy efficiency of the entire system compared to when the exhaust heat of the first cooling unit 61 is not used.

[0043] This embodiment also includes a reaction section 64 that generates ammonia by further reacting hydrogen and nitrogen contained in the mixed gas discharged from the SOEC 10 at a temperature equal to or lower than the temperature of the mixed gas discharged from the SOEC 10. This increases the ammonia concentration in the mixed gas not only in the SOEC 10 but also in the reaction section, thereby increasing the amount of ammonia produced in the entire system.

[0044] Furthermore, due to the equilibrium relationship between nitrogen, hydrogen, and ammonia required for ammonia production, high pressure is suitable for ammonia production. Under high pressure, water vapor and ammonia can be efficiently condensed and recovered by cooling them to around 40°C.

[0045] The present disclosure is not limited to the above-described embodiments, and various modifications can be made without departing from the spirit of the present disclosure.

[0046] The ammonia producing system and the ammonia producing method described in the above-described embodiment can be understood, for example, as follows. An ammonia production system according to a first aspect of the present disclosure includes a solid oxide electrolysis cell (10) that is supplied with a gas containing water vapor and nitrogen and produces hydrogen and ammonia by electrolytic reaction of the supplied water vapor, a water vapor supply line (L10) that introduces water vapor to the solid oxide electrolysis cell (10), a separation unit (60) that introduces a mixed gas containing ammonia, hydrogen, and nitrogen discharged from the solid oxide electrolysis cell (10) and separates the hydrogen and nitrogen contained in the mixed gas, and a circulation line (L32) that introduces the hydrogen and nitrogen separated in the separation unit (60) to the water vapor supply line (L10).

[0047] The above configuration includes a circulation line that guides the hydrogen and nitrogen separated in the separation unit to the steam supply line, thereby returning the hydrogen and nitrogen to the inlet side of the solid oxide electrolysis cell and supplying them to the solid oxide electrolysis cell again. Therefore, the amount of hydrogen supplied from a separately provided hydrogen supply device to the solid oxide electrolysis cell can be reduced or eliminated. Therefore, the hydrogen supply device can be made smaller or eliminated, thereby reducing the equipment costs of the ammonia production system. Furthermore, the amount of hydrogen supplied from a separately provided hydrogen supply device to the solid oxide electrolysis cell can be reduced or eliminated, thereby reducing the operating costs.

[0048] Furthermore, the amount of nitrogen supplied from a separately provided nitrogen supply device to the solid oxide electrolysis cell can be reduced. This allows the nitrogen supply device to be made smaller, thereby reducing the equipment costs of the ammonia production system. Furthermore, the amount of nitrogen supplied from a separately provided nitrogen supply device to the solid oxide electrolysis cell can be reduced, thereby reducing the operating costs. Specifically, nitrogen is supplied from the nitrogen supply device to the water vapor supply line via nitrogen line L11 by flow control valve 82 so as to compensate for the nitrogen component recovered outside the system as ammonia in the separation section.

[0049] Furthermore, if a separate hydrogen supply device can be eliminated, there is no need to supply hydrogen, which is an intermediate product, from outside the system. This eliminates the need to manage equipment outside the system, which can be complicated to manage, and makes it easier to manage the equipment for ammonia production.

[0050] Furthermore, the nitrogen that has not reacted in the solid oxide electrolysis cell is supplied again to the solid oxide electrolysis cell via a circulation line. The nitrogen supplied again to the solid oxide electrolysis cell is used to produce ammonia. Therefore, the efficiency of ammonia production can be improved.

[0051] In addition, in the ammonia production system according to a second aspect of the present disclosure, in the above-described first aspect, the separation unit (60) includes a cooling unit (61) that cools the mixed gas discharged from the solid oxide electrolysis cell, and the mixed gas is cooled in the cooling unit (61) to condense ammonia and water vapor contained in the mixed gas, thereby separating hydrogen and nitrogen.

[0052] In the above-described configuration, the separation section (60) separates hydrogen and nitrogen by condensing ammonia and water vapor contained in the mixed gas in a cooling section that cools the mixed gas, thereby enabling favorable separation of hydrogen and nitrogen.

[0053] In addition, the ammonia production system according to a third aspect of the present disclosure is the same as that of the second aspect, except that it includes a heating unit (71) that heats the hydrogen and nitrogen introduced to the steam supply line (L10) through the circulation line (L32), and the heating unit (71) heats the hydrogen and nitrogen by utilizing exhaust heat from the cooling unit (61).

[0054] The above-mentioned configuration includes a heating unit that heats the hydrogen and nitrogen introduced into the steam supply line, and the heating unit recovers heat by using the waste heat from the cooling unit to heat the hydrogen and nitrogen, thereby improving the energy efficiency of the entire system compared to when the waste heat from the cooling unit is not used.

[0055] Furthermore, the ammonia production system according to a fourth aspect of the present disclosure is the ammonia production system of any one of the first to third aspects, further comprising a reaction section (64) that is provided in the mixed gas flow between the solid oxide electrolysis cell (10) and the separation section (60), and that produces ammonia by reacting hydrogen and nitrogen contained in the mixed gas discharged from the solid oxide electrolysis cell (10).

[0056] This embodiment also includes a reaction section 64 that generates ammonia by further reacting hydrogen and nitrogen contained in the mixed gas discharged from the SOEC 10 at a temperature equal to or lower than the temperature of the mixed gas discharged from the SOEC 10. This increases the ammonia concentration in the mixed gas not only in the SOEC 10 but also in the reaction section, thereby increasing the amount of ammonia produced in the entire system.

[0057] The above configuration includes a reaction section 64 that generates ammonia by further reacting hydrogen and nitrogen contained in the mixed gas discharged from the solid oxide electrolysis cell at a temperature equal to or lower than the temperature of the mixed gas discharged from the SOEC 10. This increases the ammonia concentration in the mixed gas not only in the SOEC 10 but also in the reaction section. This increases the amount of ammonia produced in the entire system.

[0058] In the ammonia producing system according to a fifth aspect of the present disclosure, in any one of the first to third aspects, nitrogen is supplied from a nitrogen supply facility to the steam supply line (L10) via a nitrogen line (L11) so as to compensate for the nitrogen component contained in the ammonia recovered by condensing and separating the mixed gas in the separation section.

[0059] An ammonia production method according to a sixth aspect of the present disclosure is an ammonia production method for producing ammonia in an ammonia production system, the ammonia production system comprising: a solid oxide electrolysis cell (10) to which a gas containing water vapor and nitrogen is supplied and which produces hydrogen and ammonia through an electrolytic reaction of the supplied gas; a water vapor supply line (L10) for introducing water vapor to the solid oxide electrolysis cell (10); and a separation unit (60) to which a mixed gas containing ammonia, hydrogen, and nitrogen discharged from the solid oxide electrolysis cell (10) is introduced and which separates the hydrogen and nitrogen contained in the mixed gas; and the ammonia production system comprises a circulation step of introducing the hydrogen and nitrogen separated in the separation unit (60) to the water vapor supply line (L10). [Explanation of symbols]

[0060] 1. Ammonia production system 10. Solid Oxide Electrolysis Cell (SOEC) 20 Steam supply section 40 Power supply 50 Air supply unit 51 Flow control valve 60 Separation section 61 1st cooling section 62 2nd cooling section 63 Ammonia separation facility 70 Circulation Blower 71 Heating section 72 Flow control valve 80 Nitrogen supply device 81 Nitrogen supply unit 82 Flow control valve 90 Hydrogen supply device 91 Hydrogen Supply Unit 92 Flow control valve L10 Steam supply line L11 Nitrogen line L12 Hydrogen Line L20 Air supply line L21 Oxidizing gas exhaust line L25 Circulating medium line L30 mixed gas line L31 Ammonia water recovery line L32 Circulation Line

Claims

1. A solid oxide electrolytic cell is supplied with a gas containing water vapor and nitrogen, and hydrogen and ammonia are produced by the electrolytic reaction of the supplied gas. A water vapor supply line that guides water vapor to the solid oxide type electrolytic cell, A mixed gas containing ammonia, hydrogen, and nitrogen discharged from the solid oxide electrolytic cell is introduced into a separation unit that separates the hydrogen and nitrogen contained in the mixed gas. A circulation line that guides the hydrogen and nitrogen separated in the separation unit to the steam supply line, An ammonia production system comprising: a reaction unit that reacts hydrogen and nitrogen contained in the mixed gas discharged from the solid oxide electrolytic cell to produce ammonia.

2. The ammonia production system according to claim 1, wherein the separation unit has a cooling unit for cooling the mixed gas discharged from the solid oxide electrolytic cell, and the mixed gas is cooled in the cooling unit and hydrogen and nitrogen are separated by condensing the ammonia and water vapor contained in the mixed gas.

3. The circulation line includes a heating unit for heating the hydrogen and nitrogen that are introduced to the steam supply line, The ammonia production system according to claim 2, wherein the heating unit heats hydrogen and nitrogen using the waste heat from the cooling unit.

4. The ammonia production system according to any one of claims 1 to 3, wherein nitrogen is supplied from a nitrogen supply facility to the steam supply line via a nitrogen line to supplement the nitrogen component contained in the ammonia recovered by condensing and separating the mixed gas in the separation unit.

5. A method for producing ammonia in an ammonia production system, The ammonia production system is A solid oxide electrolytic cell is supplied with a gas containing water vapor and nitrogen, and hydrogen and ammonia are produced by the electrolytic reaction of the supplied gas. A water vapor supply line that guides water vapor to the solid oxide type electrolytic cell, A mixed gas containing ammonia, hydrogen, and nitrogen discharged from the solid oxide electrolytic cell is introduced into a separation unit that separates the hydrogen and nitrogen contained in the mixed gas. The system comprises a reaction unit that reacts hydrogen and nitrogen contained in the mixed gas discharged from the solid oxide electrolytic cell to produce ammonia, A method for producing ammonia, comprising a circulation step that guides the hydrogen and nitrogen separated in the separation section to the steam supply line.

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