Hydrogen gas production device, hydrogen gas supply device, fuel cell system, mobile body, and hydrogen gas production method

Abstract

Provided is a small, simple hydrogen gas production device that allows gas produced in sequence using liquefied ammonia as a raw material to flow downstream without stagnation, does not require a separate pressure reducer for creating a pressure difference between the upstream and downstream sides of a separation membrane, and can remove nitrogen without using a high-pressure compressor, thereby consuming less power. [Solution] The hydrogen gas production device of the embodiment includes a tank of liquefied ammonia, a primary purification section and a secondary purification section that remove residual ammonia gas and nitrogen gas from decomposition gas of ammonia gas, and a pressure reducer. The separation membrane of the purification section from which nitrogen gas is removed separates hydrogen gas from nitrogen gas by the differential pressure between the upstream and downstream sides of the separation membrane. The pressure reducer is provided in a purified gas line through which hydrogen gas flows, and reduces the pressure on the upstream side of the pressure reducer. The differential pressure is formed as a part of the pressure difference formed between the tank internal pressure and the pressure on the upstream side of the pressure reducer.

Description

[Technical field]

[0001] The present invention relates to a hydrogen gas production device that produces hydrogen gas using liquefied ammonia as a raw material, a hydrogen gas supply device, a fuel cell system, a mobile body, and a hydrogen gas production method. [Background technology]

[0002] Due to the trend towards carbon neutrality, fuel cells are widely used in fuel cell vehicles (FCVs) and on-site facilities for home or business use. A method for producing hydrogen gas using ammonia as a raw material is known as a method for producing hydrogen gas that serves as fuel gas for fuel cells without generating carbon dioxide. In this method, ammonia gas is generally heated to a high temperature and decomposed by contacting it with a catalyst to produce a mixed gas mainly consisting of hydrogen gas and nitrogen gas.

[0003] The ammonia decomposition gas contains undecomposed residual ammonia and the like in addition to nitrogen gas. When the residual ammonia is supplied to the negative electrode (fuel electrode) of the fuel cell together with hydrogen gas, the platinum catalyst of the negative electrode is poisoned, reducing the catalytic activity and the power generation performance of the fuel cell. Therefore, it is preferable to sufficiently remove the ammonia remaining in the ammonia decomposition gas. Conventionally, it has been known to adsorb ammonia on an adsorbent such as zeolite and remove it from the ammonia decomposition gas (for example, Non-Patent Documents 1 and 3, Patent Documents 1 to 3).

[0004] Furthermore, if nitrogen gas is not removed from the ammonia decomposition gas, the maximum output during power generation will decrease, and therefore it is preferable to remove the nitrogen gas from the ammonia decomposition gas. Conventionally, in order to remove the nitrogen gas from the ammonia decomposition gas, it has been known to use a pressure swing ammonia (PSA) method or a cryogenic separation method (for example, Non-Patent Documents 1 and 2, Patent Document 3). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2017-104778 A [Patent Document 2] International Publication No. 2023 / 022995 [Patent Document 3] Japanese Patent Publication No. 126689 / 1989 [Non-patent literature]

[0006] [Non-Patent Document 1] Taiyo Nippon Sanso Corporation, Cabinet Office, Strategic Innovation Promotion Program (SIP), Project "Energy Carriers", Research Theme "Basic Technology for Ammonia Hydrogen Stations", Final Report (public), March 25, 2019 [Non-Patent Document 2] Akihiro Numata, "Hydrogen Recovery by Cryogenic Separation", Hitachi Review, Vol. 53, No. 12, p. 1164-1971 (1971) [Non-Patent Document 3] Junyoung Cha et al., “Ammonia as an efficient COx-free hydrogen carrier Fundamentals and feasibility analyzes for fuel cell applications”, Applied Energy, Vol. 224, p. 194-204 (2018) Summary of the Invention [Problem to be solved by the invention]

[0007] In the hydrogen production process using liquefied ammonia as a raw material described in Patent Documents 1, 3 and Non-Patent Document 1, a method for producing purified hydrogen is disclosed in which, after hydrogen is generated by catalytic decomposition of ammonia, residual ammonia is removed by adsorption using an adsorbent, and nitrogen is separated and removed by a PSA method or a cryogenic separation method. The purified hydrogen obtained by these methods can be used as fuel for polymer electrolyte fuel cells (PEFCs), which are widely used as small, highly efficient power generation systems. Non-Patent Document 2 also discloses details of the related cryogenic separation method. Nitrogen removal by the PSA method or cryogenic separation method in these methods generally requires a high-pressure compressor, which requires installation space. Furthermore, in the PSA method, nitrogen removal is performed by repeatedly adsorbing nitrogen to an adsorbent under pressure and desorbing and discharging nitrogen from the adsorbent at the time of decompression, so the compressor must be frequently started and kept running, and therefore a large amount of power is consumed. In the cryogenic separation method, nitrogen is liquefied or adsorbed to an adsorbent under a single layer of high pressure conditions or under cooling conditions using adiabatic expansion from a high pressure state, and then separated and removed, so the power consumption is very large. To carry out the PSA method or cryogenic separation method, which require such operations, large equipment is required, and it is difficult to mount or install such equipment on a mobile body or small on-site facility.

[0008] On the other hand, Non-Patent Document 3 discloses a hydrogen production process using liquefied ammonia as a raw material, which is composed of only a hydrogen production process by catalytic decomposition of ammonia and a subsequent process of removing residual ammonia gas by adsorption using an adsorbent, and omits the nitrogen separation process by the PSA method or cryogenic separation method, which consumes a large amount of power and requires large equipment. In the hydrogen production process of Non-Patent Document 3, when the produced hydrogen is used as fuel for a polymer electrolyte fuel cell (PEFC), the above-mentioned residual ammonia gas that poisons the anode catalyst of the fuel cell (PEFC) is removed, so that the produced hydrogen can be used as fuel for the fuel cell (PEFC), and the device consumes little power, so that it can be mounted or installed on a mobile body or a small on-site facility, making it possible to reduce the size and weight of the device. However, since nitrogen separation is not performed in the process of Non-Patent Document 3, nitrogen equivalent to a molar ratio of hydrogen:nitrogen=75:25 remains in the produced hydrogen. For this reason, in the process of Non-Patent Document 3, when the hydrogen produced is supplied to a fuel cell (PEFC) to generate electricity, the presence of nitrogen increases concentration polarization due to a decrease in hydrogen concentration at the negative electrode, resulting in a significant decrease in power generation efficiency, especially at high output.

[0009] Patent Document 2, like Non-Patent Document 3, omits the nitrogen separation step and shows an embodiment in which nitrogen-containing hydrogen produced in a hydrogen production process consisting only of a hydrogen production step by catalytic decomposition of ammonia and an adsorption and removal step of residual ammonia gas is supplied to a fuel cell (PEFC) to generate electricity, and in particular discloses an embodiment in which the above-mentioned decrease in power generation efficiency is improved by modifying the negative electrode on the fuel cell (PEFC) side, such as by cutting a groove, or by intermittently purging nitrogen that accumulates in high concentration at the negative electrode during power generation. However, even with such an embodiment, the decrease in power generation efficiency due to the increase in concentration polarization is essentially unavoidable, and the very fact that a special fuel cell (PEFC) different from the specifications generally available on the market is required presents a problem in terms of versatility.

[0010] The present invention aims to provide a small and simple hydrogen gas production device that consumes little power, and further to provide a hydrogen gas supply device, a fuel cell system, a mobile body, and a hydrogen gas production method. The present invention provides a pressure difference between the vapor pressure in a liquefied ammonia tank and the pressure on the downstream side of a separation membrane, so that gas generated sequentially using liquefied ammonia as a raw material flows downstream without stagnation, and by forming a pressure difference between the upstream and downstream sides of the separation membrane as part of the pressure difference, it is not necessary to use a pressure reducer separate from the pressure reducer used to form the pressure difference, and in addition, nitrogen can be removed without using a high-pressure compressor. The present invention also aims to provide a small and simple hydrogen gas production device that consumes little power, and further to provide a hydrogen gas supply device, a fuel cell system, a mobile body, and a hydrogen gas production method. [Means for solving the problem]

[0011] The present disclosure encompasses the following aspects. Aspect 1 A hydrogen gas production apparatus for producing hydrogen gas by supplying liquefied ammonia as a raw material, the liquefied ammonia, ammonia gas obtained by vaporizing the liquefied ammonia, a decomposition gas obtained by decomposing the ammonia gas, and a purified gas obtained by purifying the decomposition gas, in a single direction, A tank for storing liquefied ammonia; a raw ammonia line for conducting the liquefied ammonia from the tank downstream; a vaporizer provided in the raw ammonia line for vaporizing the liquefied ammonia into ammonia gas; A heater for heating the vaporized ammonia gas to a temperature for decomposition; an ammonia decomposition section connected to the raw ammonia line downstream of the vaporizer, for decomposing the ammonia gas heated to the decomposition temperature by contacting the ammonia gas with a catalyst to generate a decomposition gas containing hydrogen gas, nitrogen gas, and residual ammonia gas; a decomposition gas line connected to the ammonia decomposition unit and configured to guide the decomposition gas downstream; a cooler provided in the decomposition gas line for cooling the decomposition gas; a primary purification section connected to the cracked gas line downstream of the cooler, for removing one of the residual ammonia gas and the nitrogen gas from the cooled cracked gas to generate a primary purified gas; a primary purified gas line connected to the primary purification section and configured to guide the primary purified gas downstream; a secondary purification section connected to the primary purified gas line, for removing the other of the residual ammonia gas and the nitrogen gas from the primary purified gas to generate a secondary purified gas; a secondary purified gas line connected to the secondary purification section, which guides the secondary purified gas downstream and discharges it; The refining section from which the residual ammonia gas is removed out of the first refining section and the second refining section is an ammonia adsorption section having an adsorbent that adsorbs the residual ammonia gas, a hydrogen separation section, wherein the purification section from which the nitrogen gas is removed out of the first purification section and the second purification section has a separation membrane, and the separation membrane is configured to selectively allow the hydrogen gas to permeate by a pressure difference created between an upstream side and a downstream side of the separation membrane, thereby separating the hydrogen gas from the nitrogen gas; The hydrogen gas production apparatus further includes a pressure reducer provided in a purified gas line, of the first purified gas line and the second purified gas line, which is connected to the hydrogen separation unit and through which the hydrogen gas that has permeated the separation membrane flows, the pressure reducer sucking in the purified gas flowing through the purified gas line and discharging it downstream to reduce the pressure of the purified gas upstream of the pressure reducer; a pressure difference is formed between the vapor pressure of ammonia gas vaporized in the tank and the pressure upstream of the pressure reducer, so that the liquefied ammonia and the gas flow downstream from the tank to the secondary purified gas line, and the pressure difference is formed as a part of the pressure difference.

[0012] Aspect 2 2. The hydrogen gas production device according to aspect 1, wherein a compressor for increasing the pressure of the decomposition gas or the first purified gas is not provided upstream of the separation membrane.

[0013] Aspect 3 2. The hydrogen gas production device according to aspect 1, further comprising a compressor configured to increase the pressure of the cracked gas or the first purified gas, disposed upstream of the hydrogen separation unit.

[0014] Aspect 4 The hydrogen gas production apparatus according to aspect 1 or 2, wherein the tank has a heater for keeping the vapor pressure constant by heating the inside of the tank so that the flow of the liquefied ammonia and the gas downstream from the tank to the secondary purified gas line is maintained.

[0015] Aspect 5 The cooler and the vaporizer constitute a first heat exchanger having a first high-temperature side passage through which the decomposition gas flows and a first low-temperature side passage through which the liquefied ammonia flows, The hydrogen gas production apparatus according to any one of aspects 1 to 4, wherein the first heat exchanger is configured to cool the decomposition gas and heat and vaporize the liquefied ammonia by heat exchange between the decomposition gas flowing through the first high-temperature side passage and the liquefied ammonia flowing through the first low-temperature side passage.

[0016] Aspect 6 The hydrogen gas production apparatus according to aspect 5, further comprising a second cooler provided upstream or downstream of the first cooler in the decomposition gas line to cool the decomposition gas, when the cooler is referred to as a first cooler.

[0017] Aspect 7 7. The hydrogen gas production apparatus according to claim 6, wherein the cracked gas passing through the second cooler is cooled by heat exchange with outside air or a liquid refrigerant cooled by heat exchange with outside air.

[0018] Aspect 8 the heater for raising the temperature is provided downstream of the vaporizer in the raw ammonia line, a combustor that combusts a part of any of the decomposition gas, the first refined gas, and the second refined gas, which are extracted from the ammonia decomposition section or downstream of the ammonia decomposition section, together with air, and discharges a combustion gas; a combustion gas line connected to the combustor and through which the combustion gas flows; a part of the combustion gas line and the heater for raising the temperature constitute a second heat exchanger having a second high-temperature side passage through which the combustion gas flows and a second low-temperature side passage through which the ammonia gas flows, The hydrogen gas production apparatus according to any one of aspects 1 to 7, wherein the second heat exchanger is configured to cool the combustion gas and raise the temperature of the ammonia gas by heat exchange between the combustion gas flowing through the second high-temperature side passage and the ammonia gas flowing through the second low-temperature side passage.

[0019] Aspect 9 the ammonia adsorption unit includes a regeneration heater that heats the adsorbent that has adsorbed the residual ammonia gas, an inert gas introduction line that introduces an inert gas from the outside, and a desorbed ammonia discharge line through which the residual ammonia gas desorbed from the adsorbent flows; The hydrogen gas production apparatus according to any one of aspects 1 to 7, wherein the ammonia adsorption unit is configured such that, by being heated by the regenerative heater, the residual ammonia gas adsorbed in the adsorbent is desorbed from the adsorbent and discharged from the ammonia adsorption unit through the desorbed ammonia discharge line together with the inert gas introduced through the inert gas introduction line.

[0020] Aspect 10 The ammonia decomposition unit further includes a combustor that combusts a part of any of the decomposition gas, the first refined gas, and the second refined gas, which are extracted from the ammonia decomposition unit or downstream of the ammonia decomposition unit, together with air, and discharges the combustion gas; 10. The hydrogen gas production apparatus according to claim 9, wherein the residual ammonia gas discharged together with the inert gas is guided to the combustor and combusted.

[0021] Aspect 11 the heater for raising the temperature is provided downstream of the vaporizer in the raw ammonia line, The hydrogen gas production apparatus further includes a combustion gas line connected to the combustor and through which the combustion gas flows, a part of the combustion gas line and the heater for raising the temperature constitute a second heat exchanger having a second high-temperature side passage through which the combustion gas flows and a second low-temperature side passage through which the ammonia gas flows, The hydrogen gas production apparatus of aspect 10, wherein the second heat exchanger is configured to cool the combustion gas and raise the temperature of the ammonia gas by heat exchange between the combustion gas flowing through the second high temperature side passage and the ammonia gas flowing through the second low temperature side passage.

[0022] Aspect 12 A re-liquefaction unit is connected to the desorbed ammonia discharge line and the tank, and configured to liquefy the residual ammonia gas desorbed from the adsorbent to separate it from the inert gas; The hydrogen gas production apparatus according to any one of aspects 9 to 11, wherein the residual ammonia gas discharged together with the inert gas is guided to the re-liquefaction section, liquefied to be separated from the inert gas, and recovered in the tank.

[0023] Aspect 13 the ammonia adsorption unit has a plurality of ammonia adsorbers arranged in parallel in the one direction, Each of the plurality of ammonia adsorbers includes the adsorbent, the inert gas introduction line, and the desorbed ammonia discharge line, the ammonia adsorption unit is configured such that, in one or more ammonia adsorbers among the plurality of ammonia adsorbers, the residual ammonia gas desorbed from the adsorbent by being heated by the regenerative heater is discharged through the desorbed ammonia discharge line together with the inert gas introduced from the inert gas introduction line, while the decomposed gas or the primary purified gas is introduced into the remaining ammonia adsorbers, the residual ammonia gas in the gas is adsorbed by the adsorbent of the ammonia adsorber and removed, and the decomposed gas or the primary purified gas from which the residual ammonia gas has been removed is guided to a downstream side of the ammonia adsorption unit, and the one or more ammonia adsorbers and the remaining ammonia adsorbers are switchable between the plurality of ammonia adsorbers.

[0024] Aspect 14 14. The hydrogen gas production apparatus according to any one of aspects 1 to 13, wherein the ammonia adsorption unit has a plurality of ammonia adsorbers arranged in series in the one direction, and each of the plurality of ammonia adsorbers has the adsorbent.

[0025] Aspect 15 15. The hydrogen gas production apparatus according to any one of aspects 1 to 14, further comprising: a flow rate regulator provided in the raw ammonia line downstream of the vaporizer to regulate a flow rate of the ammonia gas; and / or an upstream pressure regulator provided in the gas line through which the gas guided to the hydrogen separation unit flows to regulate a pressure of the gas flowing in the gas line.

[0026] Aspect 16 16. The hydrogen gas production device according to any one of aspects 1 to 15, wherein the primary purification section is the ammonia adsorption section, and the secondary purification section is the hydrogen separation section.

[0027] Aspect 17 A hydrogen gas supply device that supplies hydrogen gas to a destination, A hydrogen gas production apparatus according to any one of aspects 1 to 16, a final gas discharge line connected to a secondary purified gas line of the hydrogen gas production apparatus, which guides and discharges the secondary purified gas discharged from the secondary purified gas line toward the supply destination, the final gas discharge line having a branch portion branched so that the secondary purified gas flows to a side different from the supply destination; a purified gas tank connected to the branching portion and configured to store the secondary purified gas flowing to the different side; a compressor provided upstream of the branching portion in the final gas discharge line and configured to pressurize the secondary purified gas into the purified gas tank; a set of switching valves that are provided in the final gas discharge line and switch the flow path of the secondary purified gas flowing through the final gas discharge line, switching between flowing the secondary purified gas discharged from the secondary purified gas line toward the purified gas tank, directing the secondary purified gas in the purified gas tank to the supply destination side and discharging it, or directing the secondary purified gas discharged from the secondary purified gas line to the supply destination side and discharging it.

[0028] Aspect 18 A hydrogen gas production apparatus according to any one of aspects 1 to 16 or a hydrogen gas supply apparatus according to aspect 17; a polymer electrolyte fuel cell having a negative electrode and a positive electrode, the negative electrode and the positive electrode being connected to an external load, and configured to generate electricity by supplying a secondary purified gas discharged from the hydrogen gas production device or the hydrogen gas supply device to the negative electrode and supplying air to the positive electrode.

[0029] Aspect 19 The fuel cell system includes: a purified gas supply line connected to a secondary purified gas line of the hydrogen gas production apparatus or a final gas discharge line of the hydrogen gas supply apparatus, for leading the secondary purified gas discharged from the line to the negative electrode; a hydrogen-containing gas discharge line provided with a flow path switch, which guides a hydrogen-containing gas containing surplus hydrogen gas discharged from the negative electrode without being consumed during the power generation and nitrogen gas contained in the secondary purified gas that has permeated a separation membrane of the hydrogen gas production device to the secondary purified gas line or the final gas discharge line connected to the purified gas supply line and merges with the secondary purified gas; a hydrogen-containing gas treatment line that branches off from the hydrogen-containing gas discharge line via the flow path switch and discharges the hydrogen-containing gas to the outside, The flow path switch is configured to switch the flow direction of the hydrogen-containing gas to either the side of the secondary purified gas line or the final gas discharge line, or the side of the hydrogen gas treatment line; The hydrogen-containing gas is configured to be circulated and supplied to the negative electrode together with the secondary purified gas discharged from the secondary purified gas line or the final gas discharge line by switching the flow direction of the hydrogen-containing gas to the side of the secondary purified gas line or the final gas discharge line, when the amount of electricity generated by the polymer electrolyte fuel cell or the elapsed time during the power generation from the point when the flow direction of the hydrogen-containing gas is switched to the secondary refined gas line or the final gas discharge line reaches a respective predetermined value, the flow direction of the hydrogen-containing gas is switched to the hydrogen-containing gas treatment line side, and the hydrogen-containing gas containing the concentrated nitrogen gas from the point when the flow direction of the hydrogen-containing gas is switched to the secondary refined gas line or the final gas discharge line side is discharged to the outside, The fuel cell system of embodiment 18 is configured such that upon completion of discharge of the hydrogen-containing gas containing the concentrated nitrogen gas from the hydrogen-containing gas processing line to the outside, the flow direction of the hydrogen-containing gas is switched to the side of the secondary purification line or the final gas discharge line.

[0030] Aspect 20 The primary purification unit of the hydrogen gas production device and the hydrogen gas supply device is an ammonia adsorption unit, and the secondary purification unit is a hydrogen separation unit, a purified gas supply line connected to a secondary purified gas line of the hydrogen gas production apparatus or a final gas discharge line of the hydrogen gas supply apparatus, for leading the secondary purified gas discharged from the line to the negative electrode; a hydrogen-containing gas discharge line provided with a flow path switch, which guides a hydrogen-containing gas containing surplus hydrogen gas discharged from the negative electrode without being consumed during the power generation and nitrogen gas contained in the secondary purified gas that has permeated a separation membrane of the hydrogen gas production device to the secondary purified gas line or the final gas discharge line connected to the purified gas supply line and merges with the secondary purified gas; a hydrogen-containing gas treatment line branched off from the hydrogen-containing gas discharge line via the flow path switch and connected to a primary purified gas line of the hydrogen gas production apparatus or the hydrogen gas supply apparatus; The flow path switch is configured to switch the flow direction of the hydrogen-containing gas to either the side of the secondary purified gas line or the final gas discharge line, or the side of the hydrogen gas treatment line; The hydrogen-containing gas is configured to be circulated and supplied to the negative electrode together with the secondary purified gas discharged from the secondary purified gas line or the final gas discharge line by switching the flow direction of the hydrogen-containing gas to the side of the secondary purified gas line or the final gas discharge line, When the amount of electricity generated by the polymer electrolyte fuel cell during the power generation from the point in time when the flow direction of the hydrogen-containing gas is switched to the second purified gas line or the final gas discharge line, or the elapsed time, reaches a respective predetermined value, the flow direction of the hydrogen-containing gas is switched to the hydrogen-containing gas treatment line side, and the hydrogen-containing gas containing the concentrated nitrogen gas from that point in time is led to the first purified gas line via the hydrogen-containing gas treatment line, merges with the first purified gas flowing in the first purified gas line and is led to the hydrogen separation section, the nitrogen gas is separated and removed by the separation membrane, and the gas after the merger from which the nitrogen gas has been separated and removed is supplied to the negative electrode via the second purified gas line or the final gas discharge line, and the hydrogen gas supply line, A fuel cell system as described in aspect 18, configured so that upon completion of the separation and removal of the nitrogen gas from the gas after the confluence, the flow direction of the hydrogen-containing gas is switched to the side of the secondary purified gas line or the final gas discharge line.

[0031] Aspect 21 A mobile object, A fuel cell system according to embodiment 20; and a motor connected to the negative and positive electrodes of the fuel cell system, driven by electricity generated by power generation in a fuel cell of the fuel cell system, and generating power to propel the mobile body.

[0032] Aspect 22 A hydrogen gas production method for producing hydrogen gas by supplying liquefied ammonia as a raw material, the liquefied ammonia, ammonia gas obtained by vaporizing the liquefied ammonia, a decomposition gas obtained by decomposing the ammonia gas, and a purified gas obtained by purifying the decomposition gas, in a single direction, A step of guiding the liquefied ammonia from a tank storing the liquefied ammonia downstream and vaporizing the liquefied ammonia into ammonia gas; heating the vaporized ammonia gas to a decomposition temperature; a step of decomposing the ammonia gas heated to the decomposition temperature by contacting the ammonia gas with a catalyst to generate a decomposition gas containing hydrogen gas, nitrogen gas, and residual ammonia gas; cooling the cracked gas; removing one of the residual ammonia gas and the nitrogen gas from the cooled cracked gas to generate a first purified gas; removing the other of the residual ammonia gas and the nitrogen gas from the first purified gas to generate a second purified gas; In the step of generating the first purified gas and the step of generating the second purified gas, the step of removing the residual ammonia gas is a step of adsorbing the residual ammonia gas onto an adsorbent using an adsorbent that adsorbs the residual ammonia gas, In the step of generating the first purified gas and the step of generating the second purified gas, the step of removing the nitrogen gas is a step of selectively permeating the hydrogen gas by a pressure difference created between an upstream side and a downstream side of the separation membrane to separate the hydrogen gas from the nitrogen gas, The hydrogen gas production method further includes a step of sucking in the purified gas containing the hydrogen gas that has permeated the separation membrane and discharging it downstream, thereby reducing the pressure of the purified gas on the upstream side, a pressure difference is formed between the vapor pressure of ammonia gas vaporized in the tank and the pressure on the upstream side, so that the liquefied ammonia and the gas flow downstream from the tank to the downstream side of the separation membrane, by reducing the pressure on the upstream side, and the pressure difference is formed as part of the pressure difference. Effect of the Invention

[0033] According to the hydrogen gas production device and the hydrogen gas production method of the above aspects, when hydrogen gas is produced while supplying liquefied ammonia as a raw material, a pressure difference is provided between the vapor pressure in the liquefied ammonia tank and the pressure on the downstream side of the separation membrane, so that the gas produced sequentially using the liquefied ammonia as a raw material flows downstream without stagnation, and a pressure difference between the upstream side and the downstream side of the separation membrane is formed as part of the pressure difference, so that it is not necessary to use a pressure reducer separate from the pressure reducer for forming the pressure difference, and in addition, nitrogen removal can be performed without using a high-pressure compressor, thereby reducing the power consumption and making the equipment small and simple. Also, a hydrogen gas supply device, a fuel cell system, and a mobile body equipped with such a hydrogen gas production device can be obtained. [Brief description of the drawings]

[0034] [Figure 1] FIG. 1 is a diagram showing a configuration of a hydrogen gas production device A1 according to an embodiment. [Diagram 2] FIG. 2 is a diagram showing the configuration of a hydrogen gas production device A5 according to one embodiment. [Diagram 3] FIG. 2 is a diagram showing the configuration of a hydrogen gas production device A2 according to one embodiment. [Figure 4] FIG. 2 is a diagram showing the configuration of a hydrogen gas production device A3 according to one embodiment. [Diagram 5] FIG. 2 is a diagram showing the configuration of a hydrogen gas production device A4 according to one embodiment. [Figure 6] FIG. 2 is a diagram showing a configuration of a hydrogen gas supply device B1 according to one embodiment. [Figure 7] FIG. 2 is a diagram showing a configuration of a hydrogen gas supply device B2 according to an embodiment. [Figure 8] FIG. 1 is a diagram showing a configuration of a fuel cell system C1 according to an embodiment. [Figure 9] FIG. 2 is a diagram showing the configuration of a fuel cell system C2 according to an embodiment. [Figure 10] FIG. 2 is a diagram showing the configuration of a fuel cell system C3 according to an embodiment. [Figure 11] FIG. 2 is a diagram showing the configuration of a fuel cell system C4 according to an embodiment. [Figure 12] FIG. 2 is a diagram showing the configuration of a fuel cell system C5 according to an embodiment. [Figure 13] FIG. 2 is a diagram showing the configuration of a fuel cell system C6 according to an embodiment. [Figure 14] FIG. 2 is a diagram showing the configuration of a fuel cell system C7 according to one embodiment. [Figure 15] FIG. 2 is a diagram showing the configuration of a fuel cell system C9 according to one embodiment. [Figure 16] FIG. 2 is a diagram showing the configuration of a fuel cell system C8 according to one embodiment. [Figure 17] FIG. 1 is a diagram showing the configuration of a fuel cell system C10 according to an embodiment. [Figure 18] FIG. 2 is a diagram showing the configuration of a fuel cell system C11 according to one embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0035] Hereinafter, a hydrogen gas production device, a hydrogen gas supply device, a fuel cell system, a mobile body, and a hydrogen gas production method according to embodiments will be described.

[0036] 1 shows the configuration of a hydrogen gas production apparatus A1 according to one embodiment. In the following description, hydrogen gas production apparatuses An (n is an integer from 1 to 5) may be collectively referred to as hydrogen gas production apparatus A.

[0037] The hydrogen gas production apparatus A1 is an apparatus for producing hydrogen gas by supplying liquefied ammonia as a raw material, and sequentially flowing the liquefied ammonia, ammonia gas obtained by vaporizing the liquefied ammonia, decomposition gas obtained by decomposing the ammonia gas, and purified gas obtained by refining the decomposition gas in one direction. The term "one direction" refers to the direction in which the liquefied ammonia, ammonia gas, decomposition gas, and purified gas flow through each part (including lines and devices) constituting the hydrogen gas production apparatus A1 (hereinafter also referred to as the gas flow direction).

[0038] The hydrogen gas production apparatus A1 includes a tank 1, a raw ammonia line 3, a vaporizer 5, a heating heater 7, an ammonia decomposition section 9, a decomposition gas line 11, a cooler 13, a primary purification section 15, a primary purified gas line 17, a secondary purification section 19, and a secondary purified gas line 21.

[0039] The tank 1 is a container for storing liquefied ammonia. The ammonia to be liquefied ammonia may be synthesized using the Haber-Bosch process using hydrogen gas obtained from natural gas, coal gas, etc., through a steam reforming reaction or a shift reaction, and nitrogen gas in the air, or may be synthesized using hydrogen gas obtained by water electrolysis and nitrogen gas in the air, and the synthesis method is not limited. The tank 1 generally includes a nozzle having an openable valve (not shown) for replenishing the liquefied ammonia from the outside when the amount of the liquefied ammonia inside decreases.

[0040] It is preferable that the liquefied ammonia stored in the tank 1 has components such as carbon monoxide, hydrogen sulfide, sulfur compounds such as sulfur dioxide, etc. sufficiently removed in advance. The second purified gas, which is produced by the hydrogen gas production device A1 using the liquefied ammonia as a raw material and will be described later, is mainly composed of hydrogen gas and is used as a fuel gas for a polymer electrolyte fuel cell (PEFC), for example. In this case, if the second purified gas contains the above-mentioned components as impurities, the negative electrode of the PEFC may be poisoned and the power generation performance may be reduced. Therefore, it is preferable that the liquefied ammonia stored in the tank 1 has impurities sufficiently removed to the extent that the poisoning of the electrode does not become a problem. Ammonia obtained by synthesizing hydrogen gas obtained by water electrolysis with nitrogen gas is unlikely to contain the above-mentioned impurities, and is preferable as the liquefied ammonia that is the raw material for the second purified gas. The amount of the above-mentioned impurities can also be generally suppressed to an acceptable level by sufficiently controlling the purity in each step of the synthesis of ammonia synthesized by the Haber-Bosch process from raw materials such as natural gas and coal gas.

[0041] Liquefied ammonia is stored in tank 1 so that a gas phase space filled with vaporized ammonia gas is formed above the liquid level in tank 1, and the liquid phase liquefied ammonia and the gas phase ammonia gas form a gas-liquid equilibrium state at the temperature inside tank 1. During operation of hydrogen gas production apparatus A1, tank 1 is normally sealed except for supply valve 4, which will be described later. The pressure of the gas phase inside tank 1 during operation of hydrogen gas production apparatus A1 (hereinafter also referred to as tank internal pressure) is maintained at the saturated vapor pressure of ammonia at the temperature inside tank 1, except in cases where the supply amount of liquefied ammonia fluctuates suddenly, etc. As will be described later, this tank internal pressure becomes part of the driving force that moves gas within the system during the process of producing hydrogen gas from liquefied ammonia in hydrogen gas production apparatus A1.

[0042] The raw ammonia line 3 is a line that guides liquefied ammonia from the tank 1 to the downstream side. In this specification, the line may include a pipe as well as a valve provided in the pipe. The raw ammonia line 3 is provided with a supply valve 4 that is opened when the liquefied ammonia in the tank 1 is supplied to the downstream side.

[0043] The vaporizer 5 is provided in the raw ammonia line 3 and is a device that vaporizes the liquefied ammonia to produce ammonia gas. The vaporizer 5 is equipped with a heating mechanism and can provide the liquefied ammonia with a heat quantity larger than the latent heat of vaporization of the liquefied ammonia. The heating mechanism can be a heat exchanger (for example, the first heat exchanger 25 shown in FIG. 5, which will be referred to later) that exchanges heat between the liquefied ammonia and a high-temperature gas, an electric heater, or the like, or can be used in combination. The heat exchanger is not limited to the first heat exchanger 25, and may be one that vaporizes the liquefied ammonia by guiding a heat medium, which is a fluid heated by a heat source, to the heat exchanger of the vaporizer 5 when there is some heat source outside that has a sufficient heat quantity and temperature for the vaporization (this embodiment is not shown). This heat exchanger is preferably used both at the start-up and during normal operation (during operation other than at the start-up) of the hydrogen gas production apparatus A1.

[0044] Heating heater 7 is a device that heats vaporized ammonia gas to a decomposition temperature. The decomposition temperature is a temperature required for the decomposition reaction of ammonia gas (reaction formula 2NH3→3H2+N2) in ammonia decomposition section 9, and is set according to the performance of the catalyst, etc., so that a sufficient decomposition rate of ammonia gas is obtained. Heating heater 7 may be provided downstream of vaporizer 5 in raw ammonia line 3 to heat ammonia gas flowing in raw ammonia line 3, or may be provided in ammonia decomposition section 9 to heat the device of ammonia decomposition section 9 (for example, a decomposition tower described later), or may be provided in both of these locations as in the example shown in FIG. 1.

[0045] The heating heater 7 may be an electric heater or a heat exchanger (for example, the second heat exchanger 33 shown in FIG. 5) that exchanges heat between ammonia gas and a high-temperature gas, or may be used in combination. Of these, the electric heater is preferably used in the ammonia decomposition section 9 because it can be heated independently by energization when the hydrogen gas production apparatus A1 is started up, and the decomposition reaction can be easily started. In addition, when there is an external heat source having a sufficient amount of heat and temperature for the temperature increase, the second heat exchanger 33 can heat the fluid heat medium heated by the heat source to a predetermined decomposition temperature by guiding the fluid heat medium to the second heat exchanger 33. Such a second heat exchanger 33 is preferably used both at the start-up and during steady operation (during operation other than at the start-up) of the hydrogen gas production apparatus A1. In addition, heating can be performed using a combustion gas described later as a heat source in the second heat exchanger 33, and in this case, it is preferably used during steady operation of the hydrogen gas production apparatus A1.

[0046] According to one embodiment, as shown in FIG. 2, the heating heater 7 can be configured to perform autothermal reforming (ATR), in which a part of the ammonia gas introduced into the ammonia decomposition section 9 is burned together with air to heat the remaining ammonia gas to a decomposition temperature. This configuration can also be used in combination with an electric heater, a second heat exchanger 33, and the like. FIG. 2 is a diagram showing the configuration of a hydrogen gas production device A5. In the hydrogen gas production device A5, as the heating heater 7 provided in the ammonia decomposition section 9, a configuration for performing autothermal reforming (ATR) and an electric heater provided in the device of the ammonia decomposition section 9 (for example, a decomposition tower) are used in combination, but the electric heater can be omitted. In the hydrogen gas production device A5, an outside air introduction line 10 for introducing outside air is connected to the ammonia decomposition section 9 in order to perform autothermal reforming. In the device of the ammonia decomposition section 9, a combustion oxidation catalyst for promoting the combustion of ammonia gas may be provided upstream of a catalyst described later for promoting the decomposition reaction. The combustion oxidation catalyst may be a carrier of porous ceramics molded into a granulated or honeycomb shape, or a carrier of a metal having nitridation resistance molded into a honeycomb shape (e.g., nickel (Ni), nickel alloys such as Inconel (registered trademark) 600, 625, 718 and 750, Incoloy (registered trademark) 800 and 825, Hastelloy (registered trademark) C276 and C22, Nimonic (registered trademark) 75, 80A and 90, and stainless steel such as SUS310S), carrying ultrafine catalyst particles made of at least one of precious metals such as platinum (Pt), palladium (Pd), ruthenium (Ru), rhodium (Rh), iridium (Ir), and oxides of metals such as manganese (Mn), cobalt (Co), chromium (Cr), and copper (Cu). Furthermore, according to the configuration in which autothermal reforming is performed (ATR), the device of the ammonia decomposition unit 9 that is in a stopped state can be heated quickly, and the ammonia decomposition unit 9 can be started up.

[0047] Returning to Fig. 1, the ammonia decomposition section 9 is connected to the raw ammonia line 3 downstream of the vaporizer 5, and is a section for decomposing (cracking) ammonia gas heated to a decomposition temperature by contacting it with a catalyst to generate a decomposition gas containing hydrogen gas, nitrogen gas, and residual ammonia gas. The ammonia decomposition section 9 preferably uses a decomposition tower in which ammonia gas is brought into contact with a catalyst arranged inside while flowing from below to above, and decomposed.

[0048] The catalysts used for ammonia decomposition are sodium (Na), potassium (K), rubidium (R b), cesium (Cs), magnesium (Mg), calcium (Ca), strontium (St), barium (Ba), rare earth elements (e.g., cerium (Ce), lanthanum (La), yttrium (Y), etc.), aluminum (Al), silicon (Si), titanium (Ti), zirconium (Zr), or other elements, oxides, oxynitrides, or composite oxides, composite oxynitrides, or zeolites, graphite, activated carbon, nanocarbons (e.g., vapor-grown carbon fiber, carbon nanotubes, carbon nanohorns, graphene, etc.) and other supports having a large specific surface area are preferably used. Furthermore, as a support component that provides a high promoter effect, materials containing amides and imides of alkali metals and alkaline earth metals (e.g., NaNH2, Ca(NH2)2, Mg(NH2)2, CaNH, LiCaN, etc.) may be used as a support or mixed with the above-mentioned support. For the ultrafine particles of the catalyst component, those having a fine particle size (1 nm or more and less than 1 μm) such as iron (Fe) oxide, nickel (Ni), cobalt (Co), ruthenium (Ru), palladium (Pd), rhodium (Rh), iridium (Ir), platinum (Pt) are used, and preferably, ultrafine particles of ruthenium (Ru) are used, which can particularly promote the decomposition reaction at low temperatures and lower the decomposition temperature. The decomposition temperature when performing the decomposition reaction using a catalyst carrying ultrafine particles of ruthenium (Ru) is affected by the material, composition, structure, etc. of the above-mentioned carrier, but is set to, for example, 500 to 600 ° C. for a ruthenium (Ru)-supported catalyst that shows excellent performance. This makes it easier to decompose ammonia gas at a high decomposition rate (for example, about 95 to 99% at an absolute pressure of 1 MPa or less, although it also depends on the pressure inside the ammonia decomposition unit 9).

[0049] The catalyst used in the ammonia decomposition unit 9 may be filled with granules or may be arranged in a honeycomb shape so as to reduce the pressure loss of the ammonia gas flowing inside the ammonia decomposition unit 9, and various forms can be used. The catalyst formed in a honeycomb shape may be a catalyst carrier carrying the above-mentioned ultrafine particle catalyst for ammonia decomposition formed into a honeycomb shape, or may be a metal honeycomb having nitridation resistance coated with a catalyst carrier carrying the above-mentioned ultrafine particle catalyst for ammonia decomposition.

[0050] The decomposition gas mainly contains hydrogen gas and nitrogen gas in a molar ratio of 75:25, for example, in accordance with the production ratio in the reaction formula 2NH3 → 3H2 + N2, and when generated in the ammonia decomposition unit 9, it also contains a small amount (for example, 1000 volume ppm to 5 volume %) of undecomposed residual ammonia gas that may poison the electrodes of a polymer electrolyte fuel cell (PEFC).

[0051] The decomposed gas line 11 is connected to the ammonia decomposition section 9 and is a line for conducting the decomposed gas downstream.

[0052] The cooler 13 is a device provided in the cracked gas line 11 and cools the cracked gas. By cooling the cracked gas to, for example, less than 100°C, preferably to about room temperature (about 25°C) or lower, a larger amount of residual ammonia gas can be adsorbed by the adsorbent in the ammonia adsorption section described below, improving the removal rate of the residual ammonia gas. In addition, by cooling the cracked gas, a larger amount of hydrogen gas can be separated from nitrogen gas in the hydrogen separation section described below, improving the removal rate of nitrogen gas. In addition, in the case where the hydrogen separation section includes a polymer separation membrane or a resin container that is sensitive to heat, cooling can also prevent deterioration of these materials.

[0053] The primary purification section 15 is connected to the cracked gas line 11 downstream of the cooler 13, and is a section that removes one of the residual ammonia gas and the nitrogen gas from the cooled cracked gas to generate a primary purified gas. Furthermore, the secondary purification section 19 provided downstream of the primary purification section 15 is a section that removes the remaining one of the residual ammonia gas and the nitrogen gas from the primary purified gas to generate a secondary purified gas. Below, the hydrogen gas production apparatus A1 will be described in detail for the case where the residual ammonia gas is removed in the primary purification section 15 and the nitrogen gas is removed in the secondary purification section 19.

[0054] The primary purification section 15 of the hydrogen gas production apparatus A1 shown in Fig. 1 is an ammonia adsorption section that removes residual ammonia gas. In the following description, the ammonia adsorption section that is the primary purification section 15 is referred to as the ammonia adsorption section 15. The ammonia adsorption section 15 has an adsorbent that adsorbs the residual ammonia gas. The ammonia adsorption section 15 uses an adsorption tower that adsorbs the residual ammonia gas to the adsorbent arranged inside while flowing the cracked gas from the inlet side to the outlet side.

[0055] The adsorbent used in the ammonia adsorption section 15 is preferably a porous adsorbent having many Lewis acid sites, such as zeolite of X type or A type, and in particular, zeolite having many pores with a pore diameter of about 5 to 20 Å, among which zeolite 13X, is preferably used. In these zeolites, it is preferable that at least one cation of lithium (Li), calcium (Ca), and sodium (Na) is contained. These adsorbents can be repeatedly used because they can be heated at the time when they reach breakthrough by adsorbing residual ammonia gas, etc., and can be regenerated by desorbing ammonia gas, etc. Note that, when moisture is contained in the decomposition gas as an impurity or a by-product of ammonia decomposition in the configuration (also called autothermal reformer) (ATR) that performs the above-mentioned autothermal reforming, not only the residual ammonia gas but also the moisture is adsorbed by the adsorbent in the ammonia adsorption section 15 and removed from the decomposition gas.

[0056] When the heating heater 7 has the above-mentioned autothermal reforming (ATR) configuration, water vapor is also adsorbed by the adsorbent in addition to the residual ammonia gas, and the breakthrough time of the adsorbent in the ammonia adsorption section 15 is shortened. Therefore, when the heating heater 7 has the autothermal reforming (ATR) configuration, it may be necessary to increase the frequency of the adsorbent regeneration process.

[0057] The primary purified gas, which has passed through ammonia adsorption section 15 and from which residual ammonia gas has been removed, is a mixed gas consisting of approximately 75 volume % hydrogen gas and 25 volume % nitrogen gas. When the secondary purified gas obtained by further refining the primary purified gas at a later stage (downstream) is used as fuel gas for a polymer electrolyte fuel cell (PEFC), the concentration of residual ammonia gas that will poison electrodes in the primary purified gas is, for example, less than several hundred ppb by volume, and preferably less than 100 ppb by volume.

[0058] The primary purified gas line 17 is connected to the primary purification section 15 and is a line that guides the primary purified gas downstream.

[0059] The secondary purification section 19 is connected to the primary purified gas line 17 and is a section that removes the other of the residual ammonia gas and nitrogen gas from the primary purified gas to generate a secondary purified gas. Here, a case where nitrogen gas is removed from the primary purified gas from which the residual ammonia gas has already been removed will be described in particular. The secondary purification section 19 of the hydrogen gas production device A1 shown in FIG. 1 is a hydrogen separation section that removes nitrogen gas. In the following description, the hydrogen separation section that is the secondary purification section 19 will be referred to as the hydrogen separation section 19. The hydrogen separation section 19 has a separation membrane and is configured to selectively permeate hydrogen gas by a differential pressure (hereinafter simply referred to as differential pressure) created between the upstream side and the downstream side of the separation membrane to separate it from the nitrogen gas. The hydrogen separation section 19 has an inlet for the primary purified gas and an outlet for the secondary purified gas (hereinafter referred to as the inlet and the outlet, respectively), and a flow-type gas separation membrane module is used in which a separation membrane having a structure capable of permeating and separating hydrogen gas from the purified gas is arranged in the middle of the flow path of the purified gas flowing from the inlet to the outlet.

[0060] Gas is pressed into the separation membrane module installed inside the hydrogen separation section 19 from the inlet, and due to the pressure difference between the upstream side (inlet side) and downstream side (outlet side) inside the module separated by the separation membrane, hydrogen gas selectively permeates the separation membrane from the components contained in the gas, while nitrogen gas hardly permeates at all, and is discharged from each exhaust line.

[0061] As a separation membrane for separating hydrogen gas, generally used are membranes made of palladium (Pd) or palladium alloys, membranes made of crystalline or amorphous ceramics such as zeolite, porous silica, porous alumina, porous aluminosilicate, etc., and porous polymer membranes having a separation layer made of aromatic polyamide, aromatic polyimide, polytetrafluoroethylene (PTFE), etc. As a separation membrane, one that has high performance (selective permeability) of allowing more hydrogen gas to permeate than nitrogen gas at a specified differential pressure and has a large amount of hydrogen gas permeating (fast permeation rate) is preferably used.

[0062] Among the above separation membranes, membranes made of palladium (Pd) or palladium alloys are particularly excellent in selective permeability to hydrogen gas, and can obtain high-purity hydrogen gas of 99.97% by volume or more as specified in the international standard ISO14687-2 2012 Grade D (hereinafter referred to as ISO14687-2) in one pass. However, since palladium (Pd) is rare and expensive, it is difficult to fabricate a membrane with a large surface area, and there are problems such as a very slow hydrogen gas permeation speed, particularly around room temperature (about 25°C), and the need to apply an extremely large differential pressure. Therefore, it is not suitable for quickly refining a large amount of hydrogen gas required for the operation of a fuel cell system or a mobile body, which will be described later. In addition, in order to separate hydrogen gas using a separation membrane made of palladium (Pd) or a palladium alloy, it is necessary to heat the decomposition gas to a high temperature upstream of the hydrogen separation unit 19. Therefore, separation membranes made of palladium (Pd) or a palladium alloy are excluded from the separation membranes used in the hydrogen separation unit 19.

[0063] On the other hand, separation membranes having a separation layer made of crystalline or amorphous ceramics such as zeolite (e.g., SOD-type zeolite), porous silica, porous alumina, and porous aluminosilicate, and porous polymer separation membranes having a separation layer made of aromatic polyamide, aromatic polyimide, polytetrafluoroethylene (PTFE), etc. are less expensive than palladium (Pd) or palladium alloy separation membranes, and there are fewer restrictions on raw material resources. As these separation membranes, those having a large number of micropores with a pore size at the angstrom level (1 angstrom or more and less than 100 nm) are used, and separation based on the difference in molecular size of gas components is possible. As these micropores, those having a narrow pore size distribution of about 3 Å, which corresponds to the middle of the molecular diameters of hydrogen and nitrogen, are particularly preferable. Therefore, as the separation membrane of the hydrogen separation unit 19, a ceramic separation membrane or a polymer separation membrane with the above-mentioned specifications is preferably used.

[0064] In particular, polymer separation membranes are generally lightweight and can be molded into various shapes (for example, thin and fine hollow fibers). In a separation membrane module in which such hollow fiber membranes are bundled and enclosed in a container, a separation membrane with a large surface area can be efficiently enclosed in the container, and the amount of hydrogen gas permeation per module size can be increased, which is advantageous for installation of on-site equipment in a narrow space or mounting on a mobile body. In addition, some polymer separation membranes are surface-treated to increase the selective permeability and permeation amount (permeation rate) of hydrogen gas. With such polymer separation membranes, sufficient hydrogen gas permeation rate can be obtained at around room temperature (about 25°C) even under relatively small differential pressure conditions, so there is no need to pressurize the primary purified gas upstream of the hydrogen separation section 19, and the power required for producing hydrogen gas can be reduced, which is advantageous in reducing production costs. For this reason, a polymer separation membrane with the above-mentioned specifications is particularly preferably used.

[0065] The magnitude of the pressure difference between the upstream side and downstream side of the separation membrane is set to an appropriate value so as to obtain a predetermined hydrogen gas permeation rate. For example, when separation is performed at about room temperature (about 25°C) using a polymer separation membrane with good performance, the pressure difference is set, for example, within the range of about 0.5 to 0.9 MPa.

[0066] Selective permeability and the amount of permeation (permeation rate) are generally affected by temperature, and as the temperature rises, the selective permeability decreases slightly while the amount of permeation (permeation rate) increases in many cases. Therefore, it is preferable to determine the temperature of the gas introduced into the separation membrane module taking into consideration the balance between the two. In addition, when separation is performed using a polymer separation membrane, which generally has lower heat resistance than separation membranes made of ceramics or the like, it is preferable that the hydrogen gas production device A1 can be suitably operated, for example, at around room temperature (about 25°C) and that sufficient selective permeability and amount of permeation (permeation rate) of hydrogen gas can be achieved at the same time in that temperature range.

[0067] The amount of secondary purified gas permeated per unit time, which is separated and permeated by the separation membrane, is determined by the permeation area of ​​the separation membrane, the permeation coefficient of the secondary purified gas in the separation membrane, and the magnitude of the differential pressure, according to the following formula 1. Here, the permeation coefficient is the permeation area, differential pressure, and amount of secondary purified gas permeated per unit time specific to the separation membrane. Formula 1: (Secondary purified gas permeation rate per unit time through separation membrane [kg-H2 / h]) = (separation membrane permeation area [m 2 ]) × (permeability coefficient of secondary purified gas [kg-H2 / (m 2 ·MPa·h) ×(Differential pressure [MPa]) In the hydrogen gas production apparatus A1, the amount of secondary purified gas permeated per unit time corresponds to the amount of secondary purified gas produced per unit time. Therefore, the amount of secondary purified gas produced per unit time is also given by Equation 1.

[0068] Since a sufficient membrane area is required to ensure a desired permeation amount (permeation rate) of the secondary purified gas, if a sufficient membrane area cannot be ensured with only one separation membrane module, the hydrogen separation section 19 may be configured with multiple separation membrane modules arranged in parallel in the gas flow direction. Based on the above-mentioned formula 1, the required number of separation membrane modules to be arranged in parallel can be determined based on the value calculated by the following formula 2 as a guide. The part after the decimal point of the calculation result is rounded up. Formula 2: (Number of parallel separation membrane modules required) = (target amount of secondary purified gas permeated per unit time [kg-H2 / h]) / {(Separation membrane permeation area per separation membrane module [m 2 ]) × (permeation area of ​​the separation membrane specific to the separation membrane module, differential pressure and unit time, Secondary purified gas permeation rate [kg-H2 / (m 2 ·MPa·h) × (Set differential pressure [MPa])}

[0069] As the polymer separation membrane, for example, a "Polymer Separation Membrane Module for Hydrogen Gas Separation" manufactured by Toray Industries, Inc., which is a modularized hollow fiber polymer membrane, or "POREFLON NANO 0.3" manufactured by Sumitomo Electric Fine Polymer, Inc. can be suitably used.

[0070] The secondary purified gas is a gas produced by the hydrogen gas production apparatus A1 and discharged from the hydrogen gas production apparatus A1. The secondary purified gas is a mixed gas (mainly hydrogen gas) mainly composed of hydrogen gas, which does not substantially contain residual ammonia gas that may poison the negative electrode when used as a fuel gas for a polymer electrolyte fuel cell (PEFC), and furthermore, most of the nitrogen gas has been removed by the hydrogen separation unit 19. The mixed gas (mainly hydrogen gas) as the secondary purified gas is composed of, for example, about 95 to 98 volume % hydrogen gas and about 2 to 5 volume % nitrogen gas. Therefore, the amount of nitrogen gas contained in the secondary purified gas is significantly less than when nitrogen removal is not performed (nitrogen concentration: about 25 volume %). Therefore, when the secondary purified gas is used as a fuel gas for a polymer electrolyte fuel cell (PEFC), concentration polarization is suppressed compared to when nitrogen removal is not performed, so that high power generation efficiency can be maintained and a decrease in maximum output during power generation is unlikely to occur. In addition, since the energy density of the secondary refined gas is increased compared to when nitrogen removal is not performed, the amount of energy that can be stored when the secondary refined gas is filled into an external tank (for example, a refined gas tank (including a high-pressure hydrogen tank) described below) is greatly improved.

[0071] ISO14687-2 specifies the allowable concentrations of impurities such as ammonia, which have the effect of poisoning the electrodes of polymer electrolyte fuel cells (PEFCs), and also stipulates that the hydrogen purity must be 99.97% or higher. According to this regulation, the allowable concentration of helium is less than 300 ppm by volume, and the combined allowable concentration of nitrogen and argon is less than 100 ppm by volume, but these trace components only slightly dilute the concentration of hydrogen gas, and have almost no effect on the characteristics of polymer electrolyte fuel cells (PEFCs) even if they are contained in the secondary refined gas. On the other hand, most of the nitrogen gas contained in the first purified gas is removed in the second purified gas (for example, the hydrogen gas concentration is about 95 to 98% by volume), and the concentration polarization at the negative electrode when the second purified gas is used as the fuel gas of a polymer electrolyte fuel cell (PEFC) is significantly suppressed compared to the case where nitrogen removal is not performed (hydrogen gas concentration is about 75% or less), and the power generation efficiency and the maximum output during power generation are not significantly different from the case where high-purity hydrogen specified in ISO14687-2 is used. Therefore, when generating power using a polymer electrolyte fuel cell (PEFC) using the second purified gas as fuel, a special polymer electrolyte fuel cell (PEFC) with a groove on the negative electrode as described in Non-Patent Document 3 is not particularly required. In addition, the energy density when filled in an external tank at high pressure and the properties as a fluid, such as the flow path resistance at around room temperature (about 25°C) generated by the flow of the second purified gas, are not significantly different from those of high-purity hydrogen gas that meets the above standards.

[0072] The secondary purified gas line 21 is connected to the secondary purification section 19 (hydrogen separation section) and is a line that guides the secondary purified gas downstream and discharges it from the hydrogen gas production apparatus A1. The discharged secondary purified gas may be directly supplied to a supply destination (for example, a fuel cell or a high-pressure hydrogen tank described later) or may be stored in a purified gas tank of a hydrogen gas supply apparatus described later.

[0073] The liquefied ammonia, ammonia gas, cracked gas, primary purified gas, and secondary purified gas (hereinafter, these gases may be collectively referred to as a series of gases) are configured to flow downstream via the raw ammonia line 3, cracked gas line 11, primary purified gas line 17, and secondary purified gas line 21, respectively, due to the pressure difference between the vapor pressure of ammonia in tank 1 and the pressure downstream of the separation membrane (upstream side of pressure reducer 22) reduced by pressure reducer 22, which is provided downstream of the separation membrane and reduces the pressure and exhausts the secondary purified gas. The pressure difference that serves as the driving force for hydrogen separation by the separation membrane is formed as a pressure drop between the upstream side and downstream side of the separation membrane, which is caused by the pressure reduction and exhaust by pressure reducer 22. That is, the pressure difference is formed as a part of the pressure difference. Here, the pressure upstream of the separation membrane means the pressure of the gas downstream of the portion closest to the hydrogen separation unit 19 (upstream pressure regulator 18 in the example shown in FIG. 1) on the primary purified gas line 17 connected to the hydrogen separation unit on the upstream side of the hydrogen separation unit 19. In addition, the downstream side of the separation membrane means the gas pressure upstream of the point closest to the hydrogen separation section 19 (the downstream pressure regulator 20 in the example shown in Figure 1) on the secondary purified gas line 21 connected to the hydrogen separation section 19 on the downstream side of the hydrogen separation section 19.

[0074] The pressure difference for separating and permeating hydrogen through the separation membrane is directly adjusted by adjusting or driving the upstream pressure regulator 18 , the pressure reducer 22 , and the downstream pressure regulator 20 .

[0075] The upstream pressure regulator 18 is a device that adjusts the pressure upstream of the hydrogen separation section 19 to an appropriate pressure by adjusting the opening of the flow path between the primary purification section 15 (ammonia adsorption section 15) and the hydrogen separation section 19. A general pressure regulating valve (pressure reducing valve) can be used for the upstream pressure regulator 18, but it is more preferable that the upstream pressure regulator 18 also has a function of detecting the mass flow rate of the gas before hydrogen separation that flows through the upstream pressure regulator 18.

[0076] The pressure reducer 22 is a device that reduces the pressure on the upstream side of the pressure reducer 22 (i.e., the downstream side of the hydrogen separation unit 19) by sucking in the secondary purified gas containing hydrogen gas that has permeated the separation membrane in the hydrogen separation unit 19 and discharging it to the downstream side. For example, a pump is used as the pressure reducer 22. The pressure on the upstream side of the pressure reducer 22 is reduced by the pressure reducer 22, thereby creating a reduced pressure state on the downstream side of the separation membrane that generates the above-mentioned differential pressure as part of the above-mentioned pressure difference. In this way, the differential pressure is created by using the common pressure reducer 22 to create the above-mentioned pressure difference that is formed so that the liquefied ammonia, ammonia gas, cracked gas, primary purified gas, and secondary purified gas flow downstream from the tank 1 to the secondary purified gas line 21, so that there is no need to separately place a pressure reducer such as a pressure reducer pump for creating the above-mentioned differential pressure on the downstream side of the separation membrane. That is, in the hydrogen gas production apparatus A1, the pressure reducer for creating the above-mentioned pressure difference and the pressure reducer for creating the above-mentioned differential pressure are shared by the pressure reducer 22.

[0077] Downstream pressure regulator 20 is a device that adjusts the opening of the flow path between hydrogen separation section 19 and pressure reducer 22 to alleviate the reduced pressure state created by pressure reducer 22, and appropriately adjusts the pressure downstream of hydrogen separation section 19 to control the flow rate of the secondary purified gas permeating the separation membrane to a predetermined flow rate. A general pressure regulating valve (pressure reducing valve) can be used for downstream pressure regulator 20, as with upstream pressure regulator 18, but it is more preferable for downstream pressure regulator 20 to also have a function for detecting the mass flow rate of the secondary purified gas flowing through downstream pressure regulator 20. This allows the pressure difference across the separation membrane in hydrogen separation section 19 to be appropriately adjusted, and the secondary purified gas containing hydrogen gas that has permeated the separation membrane at a flow rate determined based on the pressure difference is passed through secondary purified gas line 21 by pressure reducer 22 and discharged.

[0078] The hydrogen gas production apparatus A1 further includes a nitrogen gas discharge line 23 for discharging to the outside a gas mainly composed of nitrogen (nitrogen-based gas) from which most of the hydrogen gas has been separated by the hydrogen separation unit 19. Hereinafter, the "nitrogen-based gas" may be simply referred to as "nitrogen gas." The nitrogen gas discharge line 23 is connected to an outlet for the nitrogen-based gas from the hydrogen separation unit 19 so that the nitrogen-based gas is discharged to the outside of the hydrogen separation unit 19. A nitrogen discharge pressure regulator 24 is provided in the nitrogen gas discharge line 23. Nitrogen discharge pressure regulator 24 is a device that adjusts the opening of the flow path of nitrogen gas discharge line 23 to maintain the pressure at the nitrogen-based gas outlet of hydrogen separation section 19 at a pressure slightly lower than the pressure at the inlet to the inside of hydrogen separation section 19 of the primary purified gas before hydrogen separation adjusted by upstream pressure regulator 18, and adjusts the flow rate of the nitrogen-based gas flowing through nitrogen gas discharge line 23 to a flow rate obtained by subtracting the flow rate of the secondary purified gas flowing through downstream pressure regulator 20 from the flow rate of the primary purified gas before hydrogen separation flowing through upstream pressure regulator 18. Although a general pressure adjusting valve (pressure reducing valve) can be used for nitrogen discharge pressure regulator 24, it is more preferable that the nitrogen discharge pressure regulator 24 also has a function of detecting the mass flow rate of the nitrogen-based gas flowing through it, and controlling the flow rate of the nitrogen-based gas so that the flow rate is equal to the value obtained by subtracting the mass flow rate of the secondary purified gas flowing through downstream pressure regulator 20 from the mass flow rate of the primary purified gas before hydrogen separation flowing through upstream pressure regulator 18. The nitrogen-based gas is continuously discharged from the hydrogen separation section 19 through a nitrogen gas discharge line 23 by a nitrogen discharge regulator 24 .

[0079] In the hydrogen gas production device A1, the liquefied ammonia and a series of gases flow downstream, driven by the pressure difference between the internal pressure (vapor pressure) of the tank 1 and the pressure upstream of the pressure reducer 22 formed by the decompression and exhaust of the pressure reducer 22. The gas flowing downstream is ammonia gas generated in the raw ammonia line 3 downstream of the vaporizer 5, which changes to decomposition gas in the decomposition gas line 11 downstream of the ammonia decomposition section 9, changes to primary purified gas in the primary purified gas line 17 downstream of the primary purification section 15 (here, the ammonia adsorption section 15), and changes to secondary purified gas in the secondary purified gas line 21 downstream of the secondary purification section (here, the hydrogen separation section 19). Through the above process in which the gas changes sequentially in this way, it is necessary to maintain the internal pressure (vapor pressure) of the tank 1 at a predetermined supply pressure so that the liquefied ammonia and a series of gases flow downstream without stagnation from the tank 1 to the secondary purified gas line 21. Furthermore, the pressure difference is adjusted as described above by the upstream pressure regulator 18 and the downstream pressure regulator 20. This allows a series of gas flows from the tank 1 to the downstream side, and enables the production of secondarily purified gas at a predetermined production amount per unit time by the separation membrane.

[0080] During operation of the hydrogen gas production apparatus A1, as liquefied ammonia flows downstream from the tank 1, the gas volume increases due to evaporation of the liquefied ammonia, the temperature rise and decomposition of the ammonia gas, and the gas volume decreases due to cooling in the cooler 13. Even if such state changes occur, in the hydrogen gas production apparatus A1, these gases do not stagnate or flow back, and the gas pressure always decreases sequentially as it proceeds downstream. In order to do so, it is preferable that the processing capacity (processing amount per unit time) and flow path resistance (pressure loss) of each device in the hydrogen gas production apparatus A1 and the flow path resistance (pressure loss) of each gas line are appropriately designed and controlled in addition to the internal pressure (vapor pressure) of the tank 1 and the pressure reduction and exhaust capacity of the pressure reducer 22.

[0081] In the hydrogen gas production apparatus A1, the pressure difference between the internal pressure (vapor pressure) of the tank 1 and the pressure downstream of the separation membrane reduced by the pressure reducer 22 can be used to create the pressure difference, and hydrogen gas is separated using the separation membrane. This does not require a high-pressure compressor (for example, one that pressurizes to 1 MPa or more) that is generally used to separate hydrogen gas using the pressure swing (PSA) method or the cryogenic separation method, and it is not necessary to frequently start and keep running the high-pressure compressor as in the PSA method. In addition, cooling using adiabatic expansion from a high-pressure state under a single layer of high pressure as in the cryogenic separation method is not required. Therefore, according to the hydrogen gas production apparatus A1, the power consumed to increase the pressure upstream of the separation membrane can be reduced, and the energy consumed in producing hydrogen gas can be reduced. In addition, while a high-pressure compressor, etc. required for implementing the PSA method or the cryogenic separation method is large, the hydrogen gas production apparatus A1 does not require a high-pressure compressor, and the installation space can be omitted, making it possible to make the hydrogen gas production apparatus A1 small and simple. In other words, according to the hydrogen gas production apparatus A1, when hydrogen gas is produced using liquefied ammonia as a raw material, nitrogen gas can be removed (hydrogen gas can be separated) without using a high-pressure compressor, etc., which results in less power consumption and makes the hydrogen gas production apparatus A1 small and simple.

[0082] Such a hydrogen gas production device A1 is small and can be mounted on a mobile object such as a fuel cell vehicle (FCV), a fuel cell (FC) ship, etc. According to the hydrogen gas production device A1, the separation of hydrogen gas can be continuously performed using a separation membrane, and therefore it is suitable for continuously supplying fuel gas to, for example, a polymer electrolyte fuel cell (PEFC).

[0083] The hydrogen gas production apparatus A1 may also include a compressor 17a that pressurizes the primary purified gas, as shown in parentheses on the primary purified gas line 17 in Fig. 1. The primary purified gas is pressurized to, for example, 0.1 to 0.5 MPa by the compressor 17a. For example, a pump or a compressor is used as the compressor 17a.

[0084] In this case, the internal pressure (vapor pressure) of the tank 1 is maintained at a predetermined supply pressure so that the liquefied ammonia and a series of gases flow downstream from the tank 1 through the second purified gas line 21 without stagnation, thereby enabling the flow of the liquefied ammonia and a series of gases downstream of the tank 1, and the permeation production of the second purified gas at a predetermined throughput per unit time in the separation membrane is possible. That is, by providing the pressurizer 17a, the internal pressure (vapor pressure) of the tank 1 can be reduced by the amount of pressurization by the pressurizer 17a (for example, 0.1 to 0.5 MPa) compared to when the pressurizer 17a is not provided. As a result, the pressure in the ammonia decomposition section 9 downstream of the tank 1 is also reduced by about the amount of pressurization compared to when the pressurizer 17a is not provided. The ammonia decomposition reaction (2NH3 → 3H2 + N2) in the ammonia decomposition section 9 is a reaction in which the gas volume increases as the reaction proceeds, so that under a constant decomposition temperature condition, the lower the pressure, the higher the ammonia decomposition rate, and the more hydrogen gas is produced, and the amount of residual ammonia gas can be reduced. Therefore, by providing the pressurizer 17a, the pressure in the ammonia decomposition section 9 can be reduced, and as a result, the ammonia decomposition rate in the ammonia decomposition section 9 can be improved. Furthermore, by providing the pressurizer 17a, even if the internal pressure (steam pressure) of the tank 1 unexpectedly drops due to a sudden drop in the external environmental temperature, etc., and the pressure difference required for hydrogen separation in the separation membrane is insufficient, the insufficient pressure can be compensated for by the pressurization, and the throughput of membrane separation can be maintained. Note that the above parentheses in FIG. 1 indicate that the components are optional, and whether or not the pressurizer 17a is provided in the hydrogen gas production apparatus A1 can be selected after taking into consideration the advantages and disadvantages described above.

[0085] According to one embodiment, the tank 1 preferably has a heater 1a for keeping warm, as shown in FIG. 3. FIG. 3 is a diagram showing a hydrogen gas production apparatus A2 according to one embodiment. The heater 1a for keeping warm is a device that maintains the vapor pressure so that the flow of liquefied ammonia and a series of gases from the tank 1 to the secondary purified gas line 21 to the downstream side is maintained by heating the inside of the tank 1. Specifically, the heater 1a for keeping warm is a device that heats and keeps the temperature inside the tank 1 at a predetermined temperature so that the tank internal pressure (vapor pressure) is maintained at the supply pressure when the secondary purified gas is produced at a predetermined production amount per unit time, both in the case where the pressurizer 17a is not provided and in the case where it is provided. As described above, this supply pressure is a pressure at which the liquefied ammonia and a series of gases flow downstream without stagnation from the tank 1 to the secondary purified gas line 21. The heater 1a for keeping warm increases the vapor pressure of the liquefied ammonia in the tank 1, and the tank 1 is heated and maintained at a temperature where the tank internal pressure becomes the supply pressure, thereby enabling the flow of the liquefied ammonia and a series of gases downstream of the tank 1, and the production of the secondary purified gas at a predetermined throughput per unit time in the separation membrane. In addition, by providing the heater 1a for keeping warm, even if a sudden drop in the external environmental temperature occurs, the temperature of the tank 1 can be controlled to be constant, thereby stabilizing the internal pressure (vapor pressure), and even if the differential pressure required for hydrogen separation in the separation membrane is insufficient, the pressure shortage can be compensated for by the heating in the tank 1, and the throughput of the membrane separation can be maintained. By suppressing the fluctuation of the tank internal pressure in this way, the throughput of the liquefied ammonia per unit time and the production volume of the secondary purified gas can be stabilized.

[0086] In the hydrogen gas production apparatus A2 shown in Fig. 3, when the pressurizer 17a is not provided and the hydrogen gas production apparatus is operated using only the pressure reduced by the pressure reducer 22 as the pressure that forms the pressure difference together with the tank internal pressure, the temperature inside the tank 1 is preferably maintained at, for example, about 40 to 50°C by the heater 1a for heat retention so that the tank internal pressure is maintained at the supply pressure. By maintaining the temperature inside the tank 1 at a temperature slightly higher than the normal outside air temperature in this manner, the internal pressure of the tank 1 is maintained at about 1.6 to 2 MPa, and as a result, the internal pressure in the downstream ammonia decomposition section 9 is, for example, about 1.1 to 1.5 MPa. Furthermore, a differential pressure (for example, about 0.5 to 0.9 MPa) required for hydrogen separation of a predetermined processing amount per unit time can be applied to the separation membrane of the downstream hydrogen separation section 19.

[0087] On the other hand, in the hydrogen gas production apparatus A2 shown in Fig. 3, when the pressurizer 17a is provided in addition to the pressure reducer 22, as described above, the internal pressure (vapor pressure) of the tank 1 can be reduced compared to when the pressurizer 17a is not provided, and the pressure in the ammonia decomposition section 9 is also reduced. As a result, the ammonia decomposition rate in the ammonia decomposition section 9 is improved, more hydrogen gas is produced, and the amount of residual ammonia gas can be reduced. At that time, the inside of the tank 1 is heated and maintained by the heater 1a for heat retention so that the internal pressure (vapor pressure) of the tank 1 is maintained at the supply pressure.

[0088] When the above-mentioned pressurizer 17a is provided, the temperature in the tank 1 is preferably maintained at about 35 to 40° C. so that the tank internal pressure is maintained at the supply pressure. By maintaining the temperature in the tank 1 at a temperature slightly higher than the normal outside air temperature in this way, the internal pressure of the tank 1 is maintained at about 1.4 to 1.6 MPa. As a result, the pressure in the downstream ammonia decomposition section 9 is also reduced to, for example, about 0.9 to 1.1 MPa, so that the decomposition rate of the ammonia decomposition reaction can be maintained high at about 97 to 99% when a particularly high-performance decomposition catalyst is adopted. Furthermore, the downstream separation membrane can also be given a differential pressure (for example, 0.5 to 0.9 MPa) required for hydrogen separation of a predetermined processing amount per unit time. Note that, as described above, when the pressurizer 17a is not provided and the heating temperature in the tank 1 is set to about 40 to 50° C., the pressure in the ammonia decomposition section 9 is, for example, about 1.1 to 1.5 MPa, and even when the above-mentioned high-performance decomposition catalyst is adopted, the decomposition rate of the ammonia decomposition reaction is about 95 to 97%.

[0089] The heater 1a for keeping warm can be disposed on the outside or inside of the container body of the tank 1. The heater 1a for keeping warm is preferably one that indirectly heats the liquefied ammonia. For example, the heater 1a for keeping warm may be a heating mechanism such as a heat exchanger or a heater having a temperature control function, or a heat-insulating material that covers the outside of the container body of the tank 1, or these may be used in combination. Heating of the inside of the tank 1 by the heater 1a for keeping warm can be performed intermittently or continuously during operation of the hydrogen gas production device A2. When heating is performed intermittently, it starts when the temperature or pressure inside the tank 1 measured during operation of the hydrogen gas production device A2 reaches a predetermined lower limit value, and ends when it reaches a predetermined upper limit value.

[0090] In addition, as the amount of liquefied ammonia in tank 1 decreases due to the continuous supply of liquefied ammonia downstream, the liquefied ammonia in tank 1 usually vaporizes to fill the gas phase space in tank 1, and the heat of vaporization is removed at that time, causing the cooling of tank 1. Therefore, the temperature and pressure in tank 1 will gradually decrease during operation unless the heat of vaporization is compensated for by heating from the outside. Therefore, by continuously heating tank 1 with heater 1a for heat retention to compensate for the heat of vaporization during operation of hydrogen gas production device A2, the progress of such cooling can be prevented and the temperature and internal pressure in tank 1 can be maintained.

[0091] In the above embodiment, as in the hydrogen gas production apparatuses A1 and A2, the first purification section 15 is the ammonia adsorption section 15, and the second purification section 19 is the hydrogen separation section 19. According to these embodiments, the residual ammonia gas is removed in the ammonia adsorption section 15 before the hydrogen gas is separated in the hydrogen separation section 19. Therefore, the nitrogen-based gas separated from the hydrogen gas in the hydrogen separation section 19 contains almost no residual ammonia gas, and the concentration (less than several hundreds of ppb by volume after the residual ammonia gas is removed, preferably less than 100 ppb by volume) is low enough not to conflict with, for example, odor regulations (the regulation standard at the site boundary in the Offensive Odor Prevention Act in Japan is 2 ppm by volume in industrial areas and industrial-only areas, and 1 ppm by volume in other areas), and if the hydrogen gas concentration in the nitrogen-based gas is below the lower flammability limit, it can be released directly into the atmosphere. Therefore, there is no need to remove the residual ammonia gas from the nitrogen-based gas separated from the hydrogen gas in the hydrogen separation section 19, and the equipment is simplified.

[0092] On the other hand, according to an embodiment different from the embodiment described above, the primary purification section 15 may be a hydrogen separation section, and the secondary purification section 19 may be an ammonia adsorption section, as shown in Fig. 4. Fig. 4 is a diagram showing a hydrogen gas production apparatus A3 of one embodiment. Fig. 4 shows a case where the above-mentioned compressor 17a is not provided upstream of the separation membrane of the hydrogen separation section, but the compressor 17a may be provided, and the effects in each case are similar to those described above. In this embodiment as well, liquefied ammonia, ammonia gas, cracked gas, primary purified gas (here, gas mainly composed of hydrogen gas and containing residual ammonia gas not decomposed in the ammonia decomposition section 9), and secondary purified gas (here, gas mainly composed of hydrogen from which residual ammonia gas has been removed from the primary purified gas) flow downstream via the raw ammonia line 3, cracked gas line 11, primary purified gas line 17, and secondary purified gas line 21 due to the pressure difference between the vapor pressure of ammonia gas vaporized in tank 1 and the pressure upstream of pressure reducer 22, which is provided downstream of the separation membrane of primary purification section (hydrogen separation section) 15 and reduces the pressure by pressure reducer 22 that reduces the pressure and exhausts the primary purified gas. In addition, the pressure difference that serves as the driving force for hydrogen separation by the separation membrane is formed as a pressure drop between the upstream and downstream sides of the separation membrane that occurs when the pressure reducer 22 reduces the pressure and exhausts the pressure. In other words, the pressure difference is formed as a part of the pressure difference. Throughout the above process, the internal pressure (vapor pressure) of the tank 1 must be maintained at a predetermined supply pressure so that the liquefied ammonia and a series of gases flow smoothly downstream from the tank 1 to the second purified gas line 21. For this reason, the tank 1 is preferably further provided with the above-mentioned heater 1a for keeping the temperature insulated (not shown in FIG. 3) in order to heat the inside and maintain the required internal pressure (vapor pressure). In the hydrogen gas production apparatus A3, the permeation amount per unit time of the hydrogen-based gas containing a trace amount of residual ammonia gas separated and permeated by the separation membrane (almost equal to the production amount of the second purified gas per unit time of the hydrogen gas production apparatus A3) and the required number of parallel separation membrane modules are determined by the above-mentioned formulas 1 and 2, respectively.

[0093] According to one embodiment, as shown in FIG. 5, the cooler 13 and the vaporizer 5 preferably constitute a first heat exchanger 25 having a first high-temperature side flow path through which the cracked gas flows and a first low-temperature side flow path through which the liquefied ammonia flows. FIG. 5 is a diagram showing a hydrogen gas production apparatus A4 according to one embodiment. The first heat exchanger 25 is configured to cool the cracked gas and heat and vaporize the liquefied ammonia by heat exchange between the cracked gas flowing through the first high-temperature side flow path and the liquefied ammonia flowing through the first low-temperature side flow path. According to this embodiment, the heat source required for vaporizing the liquefied ammonia is procured within the hydrogen gas production apparatus A4, and the heat of the high-temperature cracked gas can be effectively utilized, thereby improving the energy efficiency when producing hydrogen gas. Note that in the drawings referred to hereinafter, including FIG. 5, lines that appear at the same height position or the same horizontal position with respect to a line that is partially interrupted, such as the raw ammonia line 3, are the same line parts.

[0094] In this embodiment, when the cooler 13 is referred to as the first cooler 13, the hydrogen gas production apparatus A4 may further include a second cooler 27 that is provided upstream or downstream of the first cooler 13 in the cracked gas line 11 and cools the cracked gas, as shown in FIG. 5. In the hydrogen gas production apparatus A4 shown in FIG. 5, the second cooler 27 is provided downstream of the first cooler 13. The removal rate of the residual ammonia gas by the ammonia adsorption section 15 increases as the temperature of the cracked gas decreases, preferably when the temperature is around room temperature (about 25°C) or lower. Therefore, when the cooling capacity of the first cooler 13 is insufficient and the temperature of the cracked gas after cooling is several tens of degrees Celsius or higher than room temperature (for example, about 25°C), the cooling by the second cooler 27 can compensate for the insufficient cooling by the first cooler 13, and the removal rate of the residual ammonia gas can be increased.

[0095] Furthermore, in this embodiment, the second cooler 27 may be one having a heat exchanger structure, a forced air-cooling structure using an air-cooling fan or the like to blow outside air, or one using electronic cooling. Of these, the cracked gas passing through the second cooler 27 having a heat exchanger structure is preferably cooled by heat exchange with outside air or a liquid refrigerant cooled by heat exchange with outside air. When the second cooler 27 is provided upstream of the first cooler 13, it is preferable to use air taken into the second cooler 27 from the outside as the refrigerant. When the second cooler 27 is provided downstream of the first cooler 13, it is preferable to use a liquid refrigerant such as cooling water cooled by heat exchange with outside air using a radiator (not shown) as the refrigerant. After heat exchange with the cracked gas in the second cooler 27, the liquid refrigerant can be returned to the radiator and cooled again by heat exchange with outside air, and circulated for use in the second cooler 27.

[0096] According to one embodiment, the temperature-raising heater 7 is provided downstream of the vaporizer 5 in the raw ammonia line 3, and the hydrogen gas production apparatus A4 further includes a combustor 29 and a combustion gas line 31, as shown in FIG. The combustor 29 is a device that burns a part of any of the gases (hereinafter, also referred to as off-gas) among the cracked gas, the primary purified gas, and the secondary purified gas extracted from the ammonia decomposition section 9 or downstream of the ammonia decomposition section 9 with air, and discharges the combustion gas. The off-gas may be extracted directly from the ammonia decomposition section 9, or may be extracted from any position on the line downstream of the ammonia decomposition section 9, for example, the upstream or downstream side of the first cooler 13, the downstream side of the ammonia adsorption section 15, or the downstream side of the hydrogen separation section 19. In the example shown in FIG. 5, the off-gas is extracted from a middle part of the cracked gas line 11, and is guided to the combustor 29 through a branch gas line 30 that branches off from a part of the cracked gas line 11 downstream of the second cooler 27. The branch gas line 30 is a line that connects the ammonia decomposition section 9 or a part of the line from which the off-gas is extracted to the combustor 29. An outside air introduction line 32 that introduces air from the outside is connected to the combustor 29. The off-gas contains highly combustible hydrogen gas and can therefore be combusted together with air.

[0097] The combustion gas line 31 is connected to the combustor 29 and is a line through which the combustion gas flows. A part of the combustion gas line 31 and the heating heater 7 preferably constitute a second heat exchanger 33 having a second high-temperature side passage through which the combustion gas flows and a second low-temperature side passage through which the ammonia gas flows. The second heat exchanger 33 is configured to cool the combustion gas and raise the temperature of the ammonia gas by heat exchange between the combustion gas flowing through the second high-temperature side passage and the ammonia gas flowing through the second low-temperature side passage. The combustion gas can be generated using the gas generated in the hydrogen gas production device A4 as fuel, so that the heat source required to raise the temperature of the ammonia gas can be obtained within the hydrogen gas production device A4. The combustion of the off-gas by the combustor 29 is continuously performed at all times during the steady operation of the hydrogen gas production device A, except when the hydrogen gas production device A is started up.

[0098] The amount of air introduced from outside into the combustor 29 is preferably an amount such that the amount of oxygen in the air is equal to or greater than the stoichiometric ratio for combustion relative to the amount of off-gas introduced into the combustor 29. By supplying a sufficient amount of oxygen (air) required for combustion, incomplete combustion of the off-gas can be suppressed.

[0099] A combustion oxidation catalyst for promoting the combustion of ammonia gas may be provided upstream inside the combustor 29. By providing a combustion oxidation catalyst inside the combustor 29, even when the hydrogen gas concentration in the cracked gas is low and the ammonia gas concentration is high during start-up of the hydrogen gas production apparatus A, the cracked gas can be efficiently combusted and the ammonia gas can be heated and raised in temperature in the second heat exchanger 33. The combustion oxidation catalyst may be, as in the case of the above-mentioned combustion oxidation catalyst provided in the ammonia decomposition section 9, a carrier of porous ceramics molded into a granulated or honeycomb shape, or a metal having nitridation resistance molded into a honeycomb shape (for example, nickel (Ni), nickel alloys such as Inconel (registered trademark) 600, 625, 718 and 750, Incoloy (registered trademark) 800 and 825, Hastelloy (registered trademark) C276 and C22, Nimonic (registered trademark) 75, 80A and 90, stainless steel such as SUS310S, etc.) carrying at least one of ultrafine particle catalysts of precious metals such as platinum (Pt), palladium (Pd), ruthenium (Ru), rhodium (Rh), iridium (Ir), and oxides of metals such as manganese (Mn), cobalt (Co), chromium (Cr), copper (Cu), etc. In addition, if the above-mentioned combustion oxidation catalyst is not provided in the combustor 29, another independent heating means such as electric heating must be provided in the temperature-raising heater 7, and the ammonia gas must be heated and raised in temperature when the hydrogen gas production apparatus A is started.

[0100] The combustion gas may contain nitrogen oxides (NOx) generated due to nitrogen gas mixed in the cracked gas or nitrogen gas in the air. For this reason, a denitration device (not shown) that removes NOx by a method such as three-way catalytic decomposition or selective catalytic reduction (SCR) using a catalyst that decomposes NOx may be provided in the combustor 29. This allows denitration to be performed in parallel with the combustion of the off-gas. When denitration is performed by the SCR method, residual ammonia gas contained in gas such as the cracked gas acts as a reducing agent that selectively reduces NOx and converts it into harmless nitrogen gas and water vapor. Therefore, when the amount of residual ammonia gas is insufficient for the amount of NOx in the combustion gas, liquefied ammonia can be additionally supplied from the tank 1 through an appropriately provided line (not shown) to the denitration device in the combustor 29 to make up for the shortage, and can be used.

[0101] According to one embodiment, as shown in Fig. 5, the ammonia adsorption section 15 preferably includes a regeneration heater 35 for heating the adsorbent that adsorbs the residual ammonia gas, an inert gas introduction line 37 for introducing an inert gas from the outside, and a desorbed ammonia discharge line 39 through which the residual ammonia gas desorbed from the adsorbent flows. The ammonia adsorption section 15 is configured such that the residual ammonia gas adsorbed in the adsorbent is desorbed from the adsorbent by being heated by the regeneration heater 35, and is discharged from the ammonia adsorption section 15 through the desorbed ammonia discharge line 39 together with the inert gas introduced through the inert gas introduction line 37. As a result, when the adsorbent of the ammonia adsorption section 15 reaches breakthrough due to adsorption of the residual ammonia gas, etc., the adsorbent is heated to desorb the adsorbed residual ammonia gas, etc., and the adsorbent is regenerated and can be used repeatedly.

[0102] For example, an electric heater can be used as the regenerative heater 35. In the example shown in Fig. 5, the regenerative heater 35 is provided in the device of the ammonia adsorption section 15 (for example, the above-mentioned adsorption tower), and heats the adsorbent together with the device of the ammonia adsorption section 15. For example, when the adsorbent is X-type zeolite, 90% or more of the adsorbed ammonia gas is desorbed by heating to about 400°C or more.

[0103] In the example shown in Fig. 5, the inert gas introduction line 37 is connected to the primary purified gas line 17. The portion of the inert gas introduction line 37 extending from the connection position with the primary purified gas line 17 to the ammonia adsorption section 15 device shares a part of the flow path with the primary purified gas line 17. In the example of Fig. 5, the inert gas passes through the inert gas introduction line 37, flows in the opposite direction to the primary purified gas in this flow path, and is introduced into the ammonia adsorption section 15 device. The inert gas is preferably a gas that is not chemically reactive with ammonia and does not substantially inhibit the adsorption of ammonia gas to the adsorbent, and is preferably a rare gas such as nitrogen gas, argon gas, or helium gas. Nitrogen gas is exemplified in the drawing.

[0104] In the example shown in Fig. 5, the desorbed ammonia discharge line 39 is connected to the cracked gas line 11. A portion of the desorbed ammonia discharge line 39 extending from the ammonia adsorption section 15 to a connection position with the cracked gas line 11 shares a part of a flow path with the cracked gas line 11. A portion of the desorbed ammonia discharge line 39 extending from this connection position toward the combustor shares a flow path with the branch gas line 30. In the example shown in Fig. 5, the desorbed ammonia gas flows together with the inert gas in the former flow path in the opposite direction to the cracked gas, and further flows in the latter flow path in the same direction as the off-gas, and is discharged through the desorbed ammonia discharge line 39.

[0105] The inert gas does not necessarily need to be introduced into the ammonia adsorbing section 15 in the direction shown in Fig. 5 above, and the inert gas may be introduced from the upstream side of the ammonia adsorbing section 15 in the same direction as the decomposition gas (in this case, the inert gas introduction line 37 is connected to the upstream side of the ammonia adsorbing section 15). In that case, the desorbed ammonia gas from the ammonia adsorbing section 15 flows together with the inert gas toward the downstream side of the ammonia adsorbing section 15 in the same direction as the flow of the primary purified gas, and is discharged (in this case, the desorbed ammonia discharge line 39 is connected to the downstream side of the ammonia adsorbing section 15).

[0106] In this embodiment, the hydrogen gas production apparatus A4 preferably further includes the combustor 29 described above. The ammonia gas discharged together with the inert gas is guided to the combustor 29 and combusted. Since the off-gas supplied to the combustor 29 contains highly combustible hydrogen gas, the ammonia gas desorbed from the adsorbent in the ammonia adsorption section 15 and discharged can be combusted together with the hydrogen gas to be rendered harmless and odorless. This allows the ammonia gas, the release of which into the atmosphere is restricted, to be treated by incineration. Since the configuration of this embodiment can be designed to be relatively small, the hydrogen gas production apparatus A4 can be suitably used in small on-site facilities and mobile bodies.

[0107] Furthermore, in this embodiment, the heating heater 7 is provided downstream of the vaporizer in the raw ammonia line 3, and the hydrogen gas production apparatus A4 is connected to the combustor 29 and further includes a combustion gas line 31 through which the combustion gas flows, and it is preferable that a part of the combustion gas line 31 and the heating heater 7 constitute the above-mentioned second heat exchanger 33.

[0108] According to one embodiment, in the above embodiment in which the ammonia adsorption section 15 includes the regenerator heater 35, the inert gas introduction line 37, and the desorbed ammonia discharge line 39, the hydrogen gas production apparatus A further includes a reliquefaction section (gas-liquid separator) 41 that is connected to the desorbed ammonia discharge line 39 and the tank 1 and is configured to liquefy the ammonia gas desorbed from the adsorbent and separate it from the inert gas, as shown in Figs. 12 and 13 to be referred to later. The ammonia gas discharged together with the inert gas is led to the reliquefaction section (gas-liquid separator) 41, where it is separated from the inert gas by being liquefied, and is recovered in the tank 1. The inert gas separated from the ammonia liquefied in the reliquefaction section (gas-liquid separator) 41 is discharged outside the system after the remaining ammonia is removed by adsorption or the like. The desorbed ammonia discharge line 39 is preferably provided with a compressor 42 for compressing the ammonia gas, and a cooler 43. This allows the ammonia gas desorbed from the adsorbent, discharged, and compressed to be efficiently cooled, liquefied, and recovered. According to this embodiment, the ammonia gas, the release of which into the atmosphere is restricted, is returned to the liquefied ammonia in the tank 1, which is the raw material for hydrogen gas, thereby minimizing the outflow of the desorbed ammonia gas into the external environment. For example, a pump is used as the compressor 42. Since the re-liquefaction section (gas-liquid separator) 41 is generally a relatively large device, the hydrogen gas production apparatus A of this embodiment can be suitably used for a slightly large on-site facility or a slightly large mobile body (for example, a ship, etc.). In addition, the configuration of this embodiment can be used in combination with the configuration of the above-mentioned embodiment in which the ammonia gas discharged from the ammonia adsorption section 15 is combusted by the combustor 29, as shown in FIG. 13.

[0109] In the above-mentioned embodiment in which the residual ammonia gas discharged from the ammonia adsorption section 15 is combusted by the combustor 29, the ammonia adsorption section 15 preferably has a plurality of ammonia adsorbers 15A, 15B arranged in parallel with the gas flow direction as shown in Fig. 16 which will be referred to later. The above-mentioned adsorption tower is preferably used for each of the plurality of ammonia adsorbers 15A, 15B. The number of the plurality of ammonia adsorbers included in the ammonia adsorption section 15 is two in the illustrated example, but is not limited to two and may be three, four or more.

[0110] The multiple ammonia adsorbers 15A have the above-mentioned adsorbent, an inert gas introduction line 37A, and a desorbed ammonia discharge line 39A. The multiple ammonia adsorbers 15B have the above-mentioned adsorbent, an inert gas introduction line 37B, and a desorbed ammonia discharge line 39B. The adsorbents of the ammonia adsorbers 15A and 15B are each configured similarly to the above-mentioned adsorbent, and the same type of adsorbents can be used for both adsorbents.

[0111] In the example shown in FIG. 16, the inert gas introduction lines 37A and 37B are connected to the ammonia adsorbers 15A and 15B so as to extend from an inert gas supply port 37c in two branches, and are connected to each other at the supply port 37c. The inert gas supplied from the supply port 37c is introduced from the supply port 37c through the inert gas introduction lines 37A and 37B into the ammonia adsorbers 15A and 15B. In the example shown in FIG. 16, the primary purified gas line 17 extends from each of the ammonia adsorbers 15A and 15B, merges, and extends toward the hydrogen separation unit 19, and the parts of the primary purified gas line 17 extending from each of the ammonia adsorbers 15A and 15B are connected to the inert gas introduction lines 37A and 37B, and share a flow path with the inert gas introduction lines 37A and 37B.

[0112] In the example shown in FIG. 16, the desorbed ammonia discharge lines 39A and 39B extend from the ammonia adsorbers 15A and 15B, respectively, join, and extend toward the combustor 29. In the example shown in FIG. 16, the decomposed gas line 11 is branched into two on the way from the ammonia decomposition section 9 toward the ammonia adsorption section 15, and is connected to the ammonia adsorbers 15A and 15B, respectively. The portions of the decomposed gas line 11 connected to the ammonia adsorbers 15A and 15B share a flow path with the inert gas introduction lines 37A and 37B. In the example shown in FIG. 16, the branched gas line 30 is connected to the portion where the desorbed ammonia discharge lines 39A and 39B join, and shares a flow path with the desorbed ammonia discharge lines 39A and 39B.

[0113] The ammonia adsorption section 15 is preferably configured such that, while the residual ammonia gas desorbed from the adsorbent by heating by the regenerative heater 35 in one or more of the multiple ammonia adsorbers is discharged through the desorbed ammonia discharge line 39 together with the inert gas introduced from the inert gas introduction line 37, the cracked gas or the first purified gas is introduced into the remaining ammonia adsorbers, the residual ammonia gas in the gas is adsorbed by the adsorbent of the ammonia adsorber and removed, and the cracked gas or the first purified gas from which the residual ammonia gas has been removed is guided to the downstream side of the ammonia adsorption section. The ammonia adsorption section 15 is preferably configured such that the one or more ammonia adsorbers and the remaining ammonia adsorbers can be switched between in this manner between the multiple ammonia adsorbers 15A and 15B. This switching is performed by the linked switching operation of the valves (which have a structure of, for example, a three-way valve) at the branching portion of the cracked gas line 11 and the joining portion of the desorbed ammonia discharge line 39 at the timing before the adsorbent adsorbing the ammonia gas reaches breakthrough. According to this embodiment, the ammonia adsorber that adsorbs the residual ammonia gas (uses the adsorbent) and the ammonia adsorber that desorbs the residual ammonia gas (regenerates the adsorbent) are repeatedly switched, so that the adsorbent can be used and regenerated simultaneously without the need to stop the operation of the hydrogen gas production apparatus A, and the apparatus can be operated continuously for a long time. According to this embodiment, the operation of the hydrogen gas production apparatus A does not need to be stopped, and a part of the combustion gas generated by burning the off gas in the combustor 29 is led to the heating heater 7 through the combustion gas line 31, and the ammonia gas is heated in the heating heater 7. At the same time, a part of the remaining combustion gas is led to the ammonia adsorber that regenerates the adsorbent through the regeneration treatment gas line 28, and heated by contacting the outer wall surface of the ammonia adsorber device (adsorption tower). The regeneration treatment gas line 28 extends from the combustor 29 toward the ammonia adsorption section 15, and is divided into two on the way to be connected to the ammonia adsorbers 15A and 15B, respectively.Such a configuration contributes to reducing energy loss when adsorption of residual ammonia gas at low temperature and desorption of residual ammonia gas at high temperature are carried out in parallel.

[0114] In the example of Fig. 16 described above, the inert gas passes through the inert gas introduction line 37A or 37B, flows in the primary purified gas line 17 in the opposite direction to the primary purified gas, and is introduced into the ammonia adsorber 15A or 15B. Furthermore, in the example of Fig. 16, the desorbed ammonia gas flows together with the inert gas in the decomposition gas line 11 in the opposite direction to the decomposition gas, and further flows in the same direction as the off-gas in the flow path of the desorbed ammonia discharge line 39A or 39B, and is discharged. However, the inert gas does not necessarily need to be introduced into the ammonia adsorber 15A or 15B in this direction, and the inert gas may be introduced from the upstream side of the ammonia adsorbers 15A, 15B in the same direction as the decomposition gas (in this case, the inert gas introduction line 37A, 37B is connected to the upstream side of the ammonia adsorbers 15A, 15B). In this case, the desorbed ammonia gas from the ammonia adsorbers 15A, 15B flows, together with the inert gas, toward the downstream side of the ammonia adsorbers 15A, 15B in the same direction as the primary purified gas and is discharged (in this case, the desorbed ammonia discharge lines 39A, 39B are connected to the downstream side of the ammonia adsorption section 15).

[0115] According to one embodiment, as shown in FIG. 15, the ammonia adsorption unit 15 has two ammonia adsorbers 15X and 15Y arranged in series in the gas flow direction, and each of the two ammonia adsorbers 15X and 15Y preferably has an adsorbent. Each of the multiple ammonia adsorbers 15X and 15Y has a structure similar to that of the adsorption tower described above. In the example shown in FIG. 15, the two ammonia adsorbers 15X and 15Y are connected to each other in the gas flow direction by a connection line 15a. The gas in which the residual ammonia gas is adsorbed in the ammonia adsorber 15X is led to the ammonia adsorber 15Y through the connection line 15a.

[0116] According to this embodiment, the small amount of residual ammonia gas remaining in the gas that has passed through the upstream ammonia adsorber (hereinafter referred to as the primary adsorber) 15X is adsorbed by an adsorbent in the downstream ammonia adsorber (hereinafter referred to as the secondary adsorber) 15Y and removed, thereby further reducing the concentration of residual ammonia gas in the purified gas. The residual ammonia in the purified gas that has passed through the secondary adsorber 15Y is preferably less than 100 ppb by volume. This improves the effect of preventing poisoning of electrodes by residual ammonia gas when the secondary purified gas is supplied to a polymer electrolyte fuel cell (PEFC).

[0117] The adsorbent of the primary adsorber 15X is preferably a solid Lewis acid type adsorbent similar to that used in the case where only one adsorber is used. Specifically, a porous adsorbent having many Lewis acid sites such as zeolites of type X or type A is used. In particular, zeolites having many pores with a pore diameter of about 5 to 20 Å, especially zeolite 13X, are preferably used. These zeolites preferably contain at least one cation selected from lithium (Li), calcium (Ca), and sodium (Na). These adsorbents can be regenerated by desorbing ammonia gas, etc. by heating them at the time when the adsorption of ammonia gas, etc. reaches breakthrough, so that they can be used repeatedly.

[0118] The adsorbent in the secondary adsorber 15Y is preferably a Bronsted acid type adsorbent, specifically, an adsorbent having Bronsted acid sites and high acidity and large exchange capacity, such as activated alumina, silica / alumina gel, activated carbon whose surface is treated with a strong non-volatile acid such as sulfuric acid or phosphoric acid, activated carbon impregnated with such an acid, silica gel, alumina gel, or ion exchange resin having a strong or ultra-strong acid ion exchange group (e.g., a hydrocarbon or fluorocarbon polymer having many sulfonic acid or sulfate groups). When the adsorbent reaches breakthrough in the secondary adsorber 15Y, it is removed from the secondary adsorber 15Y and replaced with a new one. Alternatively, if the secondary adsorption device 15Y is configured so that it can be operated to flow a liquid strong acid or super strong acid stronger than these adsorbents, depending on the above-mentioned Bronsted acid type adsorbent, or during the shutdown of the hydrogen gas production device A, the ammonium ions (NH4 + ) to hydrogen ions (H + ) and regenerate it. In addition, the adsorbent removed at the time of breakthrough may be regenerated and reused by performing the above-mentioned offline regeneration treatment by ion exchange. In addition, for adsorbents such as activated alumina and silica-alumina gel, offline regeneration treatment by calcination may be effective. Note that since most of the residual ammonia gas is usually adsorbed by the primary adsorber 15X, the actual amount of residual ammonia gas adsorbed by the adsorbent in the secondary adsorber 15Y is very small. Therefore, even a small amount of the adsorbent in the secondary adsorber 15Y can often be used for a relatively long time.

[0119] According to one embodiment, the hydrogen gas production apparatus A preferably includes a flow rate regulator 6 that is provided downstream of the vaporizer 5 in the raw ammonia line 3 and that regulates the flow rate of the ammonia gas, as shown in FIG.

[0120] The flow rate regulator 6 is a device that adjusts the flow rate of ammonia gas to a predetermined flow rate. A mass flow meter, an ultrasonic flow meter, an electromagnetic flow meter, or the like can be used as the flow rate regulator 6. The throughput of liquefied ammonia per unit time is set according to the mass flow rate of ammonia gas adjusted by the flow rate regulator 6. The throughput of this liquefied ammonia per unit time is determined by the following formula based on the throughput per unit time of the primary purified gas in the separation membrane of the hydrogen separation section 19, etc. Formula 3: (Liquid ammonia processing capacity per unit time [kg-NH3 / h]) = (amount of ammonia adsorbed per unit time in the ammonia adsorption section 15 [kg-NH3 / h]) + (Primary purified gas throughput per unit time in the hydrogen separation section 19 separation membrane [kg-H2 / h]) + (Amount of off-gas removed per unit time [kg / h])

[0121] In formula 3, the amount of ammonia adsorption per unit time in the first term is approximately equal to the amount of ammonia remaining per unit time in the ammonia decomposition section 9 (= decomposition gas flow rate × residual ammonia gas concentration). The amount of off-gas taken out per unit time in the third term needs to be taken into consideration when the off-gas is branched downstream of the ammonia decomposition section 9 in order to obtain a heat medium for heating the ammonia gas in the first heat exchanger 25 and a combustion gas required for incinerating the ammonia gas desorbed from the adsorbent in the ammonia adsorption section 15.

[0122] Based on the amount of liquefied ammonia processed per unit time determined by equation 3, (i) the amount of heat exchanged per unit time in each section that performs heat exchange (e.g., first heat exchanger 25, second heat exchanger 33), (ii) the required amount of catalyst based on the flow rate of the gas to be processed in the ammonia decomposition section 9, (iii) the required amount of adsorbent in the ammonia adsorption section 15, and (iv) the required number of parallel separation membrane modules in the hydrogen separation section (according to equation 2 described above) are also set.

[0123] (Hydrogen gas supply device) Next, a hydrogen gas supply device according to an embodiment will be described.

[0124] A hydrogen gas supply device B1 according to one embodiment is shown in Fig. 6. A hydrogen gas supply device B2 according to one embodiment is shown in Fig. 7. In the following description, the hydrogen gas supply devices B1 and B2 may be collectively referred to as the hydrogen gas supply device B. The hydrogen gas supply device B1 is a device that supplies hydrogen gas to a supply destination. The hydrogen gas supply device B1 includes the above-mentioned hydrogen gas production device A, a final gas discharge line 61, a refined gas tank 63, a compressor 65, and a set of switching valves 67.

[0125] The final gas discharge line 61 is connected to the secondary purified gas line 21 of the hydrogen gas production apparatus A, and guides the secondary purified gas discharged from the secondary purified gas line 21 toward a supply destination and discharges it, and has a branching section 61a that branches so that the secondary purified gas flows to a side different from the supply destination. Examples of the supply destination include a fuel cell and a high-pressure hydrogen tank, which will be described later.

[0126] The refined gas tank 63 is a container connected to the branching portion 61a and stores the secondary refined gas that flows to a side different from the supply destination. For example, a high-pressure tank in which the internal pressure is maintained at, for example, 80 MPa to 90 MPa when filled with the secondary refined gas may be used as the refined gas tank 63, or a simple tank (buffer tank) for temporarily storing a small amount of the secondary refined gas may be used (for example, the refined gas tank 63 shown in FIG. 10, which will be referred to later). The above-mentioned high-pressure tank can be suitably used as the refined gas tank 63 when the hydrogen gas supply device B is installed in, for example, a hydrogen station that supplies hydrogen gas to a mobile body such as a fuel cell vehicle (FCV). The hydrogen gas supply device B in the illustrated example includes only one refined gas tank 63, but the number of refined gas tanks included in the hydrogen gas supply device B may be two, three or more. The hydrogen gas supply device B may include, as the multiple refined gas tanks 63, for example, multiple small tanks connected in parallel to each other at the branching portion 61a. As the small tank, for example, a pressure accumulator that stores the second purified gas at a high pressure of about 10 to 90 MPa can be used.

[0127] The pressurizer 65 is provided upstream of the branched portion 61a in the final gas discharge line 61, and is a device for pressurizing the secondary purified gas into the purified gas tank 63. A pump or a compressor can be used as the pressurizer 65, and these can be used in combination. In the example shown in FIG. 6 and FIG. 7, the purified gas tank 63 is the above-mentioned high-pressure tank, and the pressurizer 65 is a compressor capable of pressurizing the secondary purified gas into the purified gas tank 63 at high pressure. The pressurizer 65 can not only increase the pressure downstream of the pressurizer 65 higher than the upstream side, but also simultaneously reduce the pressure upstream of the pressurizer 65, so that it can also serve as the pressure reducer 22 provided in the secondary purified gas line 21, and the pressure reducer 22 can be omitted from the secondary purified gas line 21 in some cases. In an apparatus in which the pressure reducer 22 is omitted, the pressure reducer 22 of the hydrogen gas production apparatus A is composed of the pressurizer 65, and the secondary purified gas line 21 of the hydrogen gas production apparatus A is composed of the secondary purified gas line 21 and the final gas discharge line 61.

[0128] The set of switching valves 67 is provided in the final gas discharge line 61 and switches the flow path of the secondary purified gas flowing through the final gas discharge line 61. In the example shown in Figures 6 and 7, the set of switching valves 67 includes a valve 67a provided upstream of a branch portion 61a of the final gas discharge line 61, a valve 67b provided at the branch portion 61a, and a valve 67c provided downstream of the branch portion 61a of the final gas discharge line 61. The set of switching valves 67 is configured to switch between flowing the secondary purified gas discharged from the secondary purified gas line 21 toward the purified gas tank 63, guiding the secondary purified gas in the purified gas tank 63 to the supply destination side and discharging it, or guiding the secondary purified gas discharged from the secondary purified gas line 21 to the supply destination side and discharging it, by switching the open / closed states of these valves 67a to 67c.

[0129] The hydrogen gas supply device B is preferably used as an on-site hydrogen station that supplies hydrogen gas to a mobile object such as a fuel cell vehicle (FCV). The liquefied ammonia supplied from outside to the tank 1 of the hydrogen gas production device A can be transported by a transport means such as a tank truck.

[0130] According to one embodiment, the final gas discharge line 61 is preferably provided with a third cooler 69 downstream of the branching portion 61a. This makes it possible to prevent the external tank from being overheated due to adiabatic compression of the secondary purified gas in the external tank when the high-pressure secondary purified gas stored in the purified gas tank 63 is rapidly supplied to and stored in the external tank. Cooling by the third cooler 69 is effective when the purified gas tank 63 is the above-mentioned high-pressure tank. The external tank is, for example, a high-pressure hydrogen tank mounted on a mobile body such as a fuel cell vehicle (FCV). The secondary purified gas is cooled to a cooling temperature of, for example, −40 to −30° C. by the third cooler 69. For the third cooler 69, for example, a heat exchanger that exchanges heat between the secondary purified gas and a refrigerant can be used. The refrigerant used is a refrigerant that is cooled by a powerful cold source (for example, a refrigerator) separately provided outside and that can be used at the above-mentioned cooling temperature.

[0131] According to one embodiment, the final gas discharge line 61 is preferably provided with a fourth cooler 62 upstream of the compressor 65. When the purified gas tank 63 is the above-mentioned high-pressure tank and the compressor 65 is a compressor capable of injecting the secondary purified gas at high pressure into the purified gas tank 63, the secondary purified gas is cooled in advance by the fourth cooler 62 before being compressed by the compressor 65, thereby making it possible to prevent the purified gas tank 63 from being overheated due to the secondary purified gas being adiabatically compressed by the compressor 65. The secondary purified gas is cooled to a cooling temperature of, for example, −40 to −30° C. The fourth cooler 62 may be, for example, a heat exchanger that exchanges heat between the secondary purified gas and a refrigerant. The refrigerant used is the above-mentioned refrigerant that is cooled by a powerful cold source (for example, a refrigerator) separately provided outside and that can be used at the cooling temperature.

[0132] (Fuel Cell System) Next, a fuel cell system C according to an embodiment will be described.

[0133] 8 to 18 show fuel cell systems C1 to C11. FIG. 8 is a diagram showing the configuration of a fuel cell system C1 according to an embodiment. FIG. 9 is a diagram showing the configuration of a fuel cell system C2 according to an embodiment. FIG. 10 is a diagram showing the configuration of a fuel cell system C3 according to an embodiment. FIG. 11 is a diagram showing the configuration of a fuel cell system C4 according to an embodiment. FIG. 12 is a diagram showing the configuration of a fuel cell system C5 according to an embodiment. FIG. 13 is a diagram showing the configuration of a fuel cell system C6 according to an embodiment. FIG. 14 is a diagram showing the configuration of a fuel cell system C7 according to an embodiment. FIG. 15 is a diagram showing the configuration of a fuel cell system C8 according to an embodiment. FIG. 16 is a diagram showing the configuration of a fuel cell system C9 according to an embodiment. FIG. 17 is a diagram showing the configuration of a fuel cell system C10 according to an embodiment. FIG. 18 is a diagram showing the configuration of a fuel cell system C11 according to an embodiment. In the following description, the fuel cell systems C1 to C11 are collectively referred to as fuel cell system C.

[0134] The fuel cell system C includes the above-mentioned hydrogen gas production device A or the above-mentioned hydrogen gas supply device B, and a polymer electrolyte fuel cell (PEFC) 81. Since a polymer electrolyte fuel cell (PEFC) has high power generation efficiency, a low operating temperature, and is lightweight and small, the fuel cell system C is suitable for use as a power generation system for mobile objects such as fuel cell vehicles (FCVs) and on-site facilities for home or commercial use.

[0135] The polymer electrolyte fuel cell (PEFC) 81 includes an anode and a cathode, and is connected to an external load 91. The polymer electrolyte fuel cell 81 is configured to generate electricity by supplying hydrogen gas discharged from the hydrogen gas production device A or the hydrogen gas supply device B to the anode and air to the cathode. When the polymer electrolyte fuel cell 81 generates electricity, the required flow rate of hydrogen gas supplied from the hydrogen gas production device A or the hydrogen gas supply device B is determined according to the output current value.

[0136] The polymer electrolyte fuel cell (PEFC) 81 has a single cell formed by stacking a catalyst layer with a gas diffusion layer provided on both sides of a polymer electrolyte membrane and a separator as a current collector, and preferably constitutes a cell stack of a bipolar structure in which a plurality of single cells are stacked in series. The cell stack has a negative electrode side terminal connected to the negative electrode of each single cell, and a positive electrode side terminal connected to the positive electrode of each single cell. The polymer electrolyte fuel cell (PEFC) 81 shown in the figure constitutes a cell stack, and the negative electrode side terminal and the positive electrode side terminal are connected to an external load 91.

[0137] The negative electrode catalyst layer of the single cell is, for example, a layer made of carbon black carrying a catalyst, which is ultrafine particles of a platinum group metal such as platinum (Pt), and the positive electrode catalyst layer is, for example, a layer made of carbon black carrying a catalyst, which is ultrafine particles of a platinum group metal oxide such as iridium (Ir) oxide. These are bonded to both sides of the electrolyte membrane, respectively, to form the negative electrode and positive electrode of a polymer electrolyte fuel cell (PEFC) 81. The electrolyte membrane is made of a very strong acidic fluorocarbon polymer mainly having ion exchange groups such as sulfonic acid groups and carboxyl groups, and has a high hydrogen ion (hydronium ion H3O + ) conductivity. For the separator, a thin plate made of graphite, carbonaceous material, or a composite material containing these, which has sufficient electronic conductivity and mechanical strength, and is chemically stable in the bonding with a super-strongly acidic electrolyte and in the reduction / oxidation environment at the negative and positive electrodes, is often used. An external load 91 is connected between the negative and positive terminals, and hydrogen gas and oxygen gas are supplied to the negative and positive electrodes, respectively, to output direct current power and generate electricity. At this time, if the hydrogen gas supplied to the negative electrode of the polymer electrolyte fuel cell (PEFC) 81 contains gas components such as carbon monoxide, ammonia, hydrogen sulfide, or sulfur compounds such as sulfur dioxide, the negative electrode catalyst platinum, etc. is strongly poisoned by these gas components, and the catalytic activity is reduced, resulting in a significant decrease in the power generation performance of the polymer electrolyte fuel cell (PEFC). Therefore, the concentration of these gas components in the secondary purified gas needs to be reduced to within the allowable concentration range that does not cause such poisoning, and it is preferable that the concentration is within the allowable range specified in ISO14687-2, which is the international standard for hydrogen gas for fuel cells.

[0138] A hydrogen gas supply pump 79 is provided downstream of the pressure reducer 22 in the final gas discharge line 61. The hydrogen gas supply pump 79 is a device for supplying a secondary purified gas containing a high concentration of hydrogen gas to a polymer electrolyte fuel cell (PEFC) 81. Note that the secondary purified gas of the fuel supplied to the polymer electrolyte fuel cell 81 generally contains hydrogen ions (hydronium ions HO) in the electrolyte membrane. + ) is added, but lines and the like for adding this moisture (water vapor) are omitted in FIGS. 8 to 18.

[0139] A hydrogen gas supply line 83 connected to the final gas discharge line 61 via a hydrogen gas supply pump 79 is connected to a hydrogen gas supply port of the solid polymer electrolyte fuel cell (PEFC) 81, which supplies the second purified gas to the negative electrode of the solid polymer electrolyte fuel cell (PEFC) 81. On the other hand, a hydrogen gas discharge line 84 is connected to a hydrogen gas discharge port of the solid polymer electrolyte fuel cell 81, which discharges gas containing surplus hydrogen gas not consumed during power generation (hereinafter referred to as hydrogen-containing gas) from the negative electrode of the solid polymer electrolyte fuel cell 81. A pressure regulator 85 is provided in the hydrogen gas discharge line 84, and the hydrogen gas discharge line 84 is connected to the final gas discharge line 61 downstream of the pressure regulator 85 so as to merge with the final gas discharge line 61. The merged hydrogen-containing gas is supplied to the negative electrode of the solid polymer electrolyte fuel cell 81 together with the second purified gas discharged from the final gas discharge line 61, thereby forming a hydrogen gas circulation loop via the negative electrode. Furthermore, the hydrogen gas discharge line 84 is provided with a flow path switch 86, and is provided with a hydrogen gas treatment line 87 that branches off from the hydrogen gas discharge line 84 via the flow path switch 86 and discharges the hydrogen-containing gas to the outside. As the flow path switch 86, for example, a three-way valve can be used. The flow path switch 86 switches the flow path of the hydrogen-containing gas so that the hydrogen-containing gas flows in either a direction toward the final gas discharge line 61 side or a direction toward the outside side. In a normal operating state, the flow path switch 86 is set so that the hydrogen-containing gas flows from the hydrogen gas discharge line 84 toward the final gas discharge line 61 side, and the above-mentioned circulation loop is formed.

[0140] The hydrogen-containing gas after merging from the hydrogen gas discharge line 84 to the final gas discharge line 61 is circulated and supplied to the negative electrode of the solid polymer electrolyte fuel cell 81 by the hydrogen gas supply pump 79 together with the second purified gas supplied from the final gas discharge line 61, and reused for power generation. Here, the pressure regulator 85 is a device that adjusts the pressure of the hydrogen-containing gas discharged from the solid polymer electrolyte fuel cell 81. The pressure regulator 85 maintains the pressure of the second purified gas at the negative electrode under a constant pressure of about several hundreds of kPa during power generation by the solid polymer electrolyte fuel cell (PEFC) 81. Due to the effect of the circulation loop at that time, the amount of the second purified gas supplied per unit time to the negative electrode is maintained sufficiently excessive with respect to the amount of the second purified gas consumed per unit time required to obtain the output current of the solid polymer electrolyte fuel cell 81. Furthermore, it maintains the pressure balance with the air pressure supplied to the positive electrode side via the electrolyte membrane, and also contributes to the adjustment of the amount of moisture in the negative electrode. The pressure regulator 85 uses a pressure regulating valve that keeps the primary pressure constant on the upstream side of the pressure regulator 85. In addition, most of the water generated at the positive electrode during power generation in a polymer electrolyte fuel cell (PEFC) is discharged from the air exhaust port on the positive electrode side, together with the oxygen gas and nitrogen gas in the air that are not consumed at the positive electrode.

[0141] In the normal operating state of the fuel cell system C1 shown in FIG. 8, as described above, the flow path of the hydrogen-containing gas switched by the flow path switch 86 is maintained in the direction from the hydrogen gas discharge line 84 toward the final gas discharge line 61, thereby forming the above-mentioned hydrogen gas circulation loop. At this time, a stable high output is obtained for a while after the start of power generation by the polymer electrolyte fuel cell (PEFC) 81. However, the secondary purified gas that permeates the separation membrane of the secondary purification section and is supplied to the polymer electrolyte fuel cell 81 via the final gas discharge line 61 and the hydrogen gas supply line 83 contains a small amount of nitrogen gas, about 2 to 5 volume %, along with hydrogen gas, which is the main component. Therefore, during power generation by the polymer electrolyte fuel cell 81, the secondary purified gas containing nitrogen gas is supplied and continues to be circulated and supplied to the polymer electrolyte fuel cell 81 through the hydrogen gas discharge line 84 and the like. During that time, only hydrogen gas is consumed as fuel at the negative electrode of the polymer electrolyte fuel cell 81, so that a phenomenon occurs in which the nitrogen gas concentration gradually increases from the initial concentration of about 2 to 5 volume % in the above-mentioned circulation loop. Such an increase in nitrogen gas concentration can increase concentration polarization at the negative electrode of the solid polymer fuel cell 81 and reduce power generation efficiency, so it is necessary to reduce the nitrogen gas concentration in the circulation loop before the effect reaches an unacceptable level.

[0142] In the fuel cell system C1, as described above, the hydrogen gas discharge line 84 is provided with a flow path switch 86, and the hydrogen gas treatment line 87 is branched from the hydrogen gas discharge line 84 via the flow path switch 86 and discharges the hydrogen-containing gas to the outside. Before the increase in the nitrogen gas concentration described above progresses and the decrease in power generation efficiency exceeds an allowable level, the flow path of the hydrogen-containing gas is switched by the flow path switch 86 so that the direction of the hydrogen-containing gas is toward the hydrogen gas treatment line 87 side, so that the nitrogen gas concentrated gas that has stayed in the circulation loop can be discharged to the outside of the system by the hydrogen gas supply pump 79. When the discharge of the hydrogen-containing gas staying in the circulation loop to the outside (outside) is completed and the inside of the circulation loop is completely replaced by the secondary purified gas supplied by the supply pump 79, the nitrogen gas concentration in the hydrogen-containing gas staying in the circulation loop is restored to approximately the initial state (for example, about 2 to 5 volume %). At that time, the flow path switch 86 is returned to the side of the final gas discharge line 61 in the normal state. Even during the series of processes described above, it is possible to continue power generation in the polymer electrolyte fuel cell 81. The above-described configuration of the fuel cell system C1, which intermittently discharges concentrated nitrogen gas to the outside of the system, makes it possible to restore the nitrogen gas concentration that has increased in the first circulation loop described above to its initial state (for example, about 2 to 5% by volume), prevents an increase in concentration polarization at the negative electrode of the polymer electrolyte fuel cell 81 and a decrease in power generation efficiency, and maintains stable, high-output power generation.

[0143] In the above-mentioned configuration, the hydrogen-containing gas discharged from the hydrogen gas processing line 87 still contains a high concentration of hydrogen gas and is combustible. For this reason, when discharging the hydrogen-containing gas, it is preferable to take fire prevention measures such as mixing the hydrogen-containing gas with a gas mainly composed of low-flammability nitrogen gas discharged from the nitrogen gas discharge line 23 of the hydrogen separation unit 19 of the hydrogen gas production device A or the hydrogen gas supply device B provided in the fuel cell system C1, mixing the gas with a large amount of air under a condition where fire, static electricity, etc. are sufficiently eliminated, and discharging the gas outside the system. In addition, it is preferable to provide a flame arrester for preventing backfire at the tip of the pipe that finally discharges the gas outside the system.

[0144] The above-mentioned configuration of the fuel cell system C1, which intermittently discharges the nitrogen gas-enriched gas outside the system, is similar to the embodiment disclosed in Patent Document 2, which intermittently purges the nitrogen gas accumulated in the negative electrode during power generation of the solid polymer electrolyte fuel cell. However, the initial concentration of nitrogen gas in the fuel gas supplied to the solid polymer electrolyte fuel cell is high at about 25% by volume in Patent Document 2, whereas the initial concentration of nitrogen gas in the fuel gas is much lower, for example, at about 2 to 5% by volume in the fuel cell system C1 of the present invention. Therefore, concentration polarization at the negative electrode during normal operation is suppressed compared to Patent Document 2, and higher power efficiency is obtained. Furthermore, in the fuel cell system C1 of the present invention, due to the difference in the initial concentration of nitrogen gas described above, the frequency of the discharge required to restore the nitrogen gas concentration is reduced compared to Patent Document 2, and the amount of hydrogen gas lost by discharge outside the system is significantly less than that of Patent Document 2. It should be noted that the fuel cell systems C3 to C11 in FIGS. 10 to 18 also show examples in which a configuration similar to that of the fuel cell system C1 is provided, in which concentrated nitrogen gas is intermittently discharged to the outside of the system.

[0145] FIG. 9 shows another fuel cell system C2 that can prevent the increase in concentration polarization and the decrease in power generation efficiency at the negative electrode of the solid polymer fuel cell 81, and maintain stable, high-output power generation. Since the fuel cell system C2 is configured to utilize the separation membrane of the hydrogen separation unit after the removal of residual ammonia gas, the hydrogen gas production device A or hydrogen gas supply device B provided therein is preferably configured to have an ammonia adsorption unit as the primary purification unit 15 and a hydrogen separation unit as the secondary purification unit. In the fuel cell system C2, instead of the configuration in which nitrogen gas-enriched gas is intermittently discharged to the outside of the system in the fuel cell system C1 shown in FIG. 8, a hydrogen gas treatment line 87 is provided that branches off from the hydrogen gas discharge line 84 via a flow path switch 86 and merges with the secondary purification gas line 21 upstream of the separation membrane of the secondary purification unit 19 (hydrogen separation unit). For example, a three-way valve can be used as the flow path switch 86. The hydrogen gas treatment line 87 is provided with a reflux pump 88, and further provided with a pressure adjusting valve 89 and a check valve 90 at a portion before the line joins the secondary purified gas line 21.

[0146] In the fuel cell system C2, before the increase in the nitrogen gas concentration continues and the decrease in power generation efficiency exceeds an allowable level, the flow path is switched by the flow path switch 86 so that the direction in which the hydrogen-containing gas is discharged is the direction toward the hydrogen gas treatment line 87, and the reflux pump 88 is started. The hydrogen-containing gas in which nitrogen gas is concentrated and which has stayed in the circulation loop is pressurized by the reflux pump 88, passes through the hydrogen gas treatment line 87, and merges with the primary purified gas passing through the primary purified gas line 17 on the upstream side of the separation membrane of the hydrogen separation unit 19. In the portion of the hydrogen gas treatment line 87 before this merger, the pressure of the hydrogen-containing gas in which nitrogen gas is concentrated in the hydrogen gas treatment line 87 is regulated by the pressure regulating valve 89 so that it is equal to the pressure of the primary purified gas in the primary purified gas line. This pressure regulation prevents the hydrogen-containing gas from moving upstream of the primary purified gas line 17 and the primary purified gas from flowing into the hydrogen gas treatment line 87. Thereafter, the hydrogen-containing gas in which nitrogen gas has been concentrated is separated together with the primary purified gas by a separation membrane to separate the nitrogen gas contained therein (at this time, the primary purified gas becomes a secondary purified gas from which nitrogen gas has been separated), and is then supplied by supply pump 79 to solid polymer electrolyte fuel cell 81 as fuel gas via final gas discharge line 61 and hydrogen gas supply line 83. In the above, the flow rate per unit time of the hydrogen-containing gas in which nitrogen gas has been concentrated, transported by reflux pump 88, needs to be limited to a level that does not exceed the separation process capacity of the separation membrane at the time of the merging.

[0147] When the inside of the circulation loop is completely replaced by the second purified gas and the hydrogen-containing gas from which nitrogen gas has been removed, supplied by the supply pump 79, the nitrogen gas concentration in the gas staying in the circulation loop recovers to approximately the initial state (for example, about 2 to 5 volume %), the flow path switch 68 is returned to the side of the final gas discharge line 61 under normal conditions, and the reflux pump 88 is stopped. Here, the check valve 90 prevents the inflow of the first purified gas into the hydrogen gas treatment line 87, which would cause a pressure drop in the hydrogen gas treatment line 87 after the reflux pump 88 is stopped.

[0148] Even during the series of processes described above, it is possible to continue power generation in the polymer electrolyte fuel cell 81. The above-described configuration of the fuel cell system C2 for removing nitrogen gas from nitrogen-concentrated gas makes it possible to restore the nitrogen gas concentration that has increased in the first circulation loop described above to its initial state (for example, about 2 to 5% by volume), preventing an increase in concentration polarization and a decrease in power generation efficiency at the negative electrode of the polymer electrolyte fuel cell 81, and maintaining stable, high-output power generation.

[0149] The fuel cell system C2 that removes nitrogen gas from the nitrogen-enriched gas described above has a slightly more complicated configuration than the fuel cell system C1 described above, but has the advantage that the amount of hydrogen gas lost by being discharged outside the system can be reduced to almost zero by using only the components in the fuel cell system C2. A configuration similar to this fuel cell system C2 can also be applied to the fuel cell systems C3 to C11 shown in Figures 10 to 18 in place of a configuration similar to the fuel cell system C1 described above that intermittently discharges nitrogen-enriched gas outside the system.

[0150] In the above-mentioned fuel cell system C1 and fuel cell system C2, in order to reduce the dead volume that is difficult to discharge when discharging gas remaining in the circulation loop, it is preferable that the piping length between the junction of the hydrogen gas discharge line 84 and the final gas discharge line 61 and the flow path switch 86 be as short as possible.

[0151] Next, in the above-mentioned fuel cell system C1 and fuel cell system C2, the timing at which the flow path switch 86 is switched from the state in which the circulation loop is formed during normal operation (in fuel cell system C2, the reflux pump 88 is started at the same time) to move on to the processing of concentrated gas of the nitrogen gas in the circulation loop (hereinafter referred to as the "processing start point"), and the timing at which the process is completed and the flow path switch 86 is switched back again to the original state (in fuel cell system C2, the reflux pump 88 is stopped at the same time; hereinafter referred to as the "processing end point").

[0152] In the fuel cell system C1 and the fuel cell system C2, from the point in time when the flow path switch 86 is set so that the direction of the hydrogen-containing gas changes from the hydrogen gas processing line 87 side to the final gas discharge line 61 side during power generation (the circulation loop is formed at this point, and is hereinafter referred to as the "circulation loop formation point"), the concentration of nitrogen gas in the gas staying in the circulation loop gradually increases from the initial state (for example, about 2 to 5 volume %) as power generation progresses. This increase in the nitrogen gas concentration in the circulation loop causes an increase in the concentration polarization of the hydrogen gas at the negative electrode of the solid polymer electrolyte fuel cell 81, reducing the power generation efficiency. The point in time when this reduction in power generation efficiency reaches an unacceptable level is the above-mentioned "treatment start point". This "unacceptable level" is arbitrary and can be appropriately assumed depending on the target and purpose of the supply of generated power. The nitrogen gas concentration in the circulation loop at which the power generation efficiency drops to an assumed "unacceptable level" is the upper limit of the allowable nitrogen gas concentration, and the above-mentioned "treatment start point" is the point at which the nitrogen gas concentration in the circulation loop reaches this upper limit of the allowable nitrogen gas concentration.

[0153] The nitrogen gas concentration in the circulation loop can be actually monitored by providing a predetermined concentration detection means in the circulation loop, but it is preferable to use an index that can be detected more easily. Hereinafter, the nitrogen gas concentration in the circulation loop at a certain time point after the formation of the circulation loop during power generation is a function of the volume in the circulation loop (including the gas phase volume of the negative electrode of the solid polymer fuel cell 81), the initial concentration of nitrogen gas in the circulation loop (approximated by the nitrogen gas concentration in the secondary purified gas supplied as fuel, for example, about 2 to 5% by volume), and the amount of electricity generated by the solid polymer fuel cell 81 from the formation of the circulation loop to that time point. Among these, the volume in the circulation loop and the initial concentration of nitrogen gas in the circulation loop are preset values ​​of this fuel cell system and are constants. In addition, the output current of the solid polymer fuel cell 81 is generally a value that is preset as a power generation condition, and is constantly monitored. Therefore, the amount of electricity generated by the solid polymer fuel cell 81 can also be easily constantly monitored as an integral value of the output current over time. From the above, the nitrogen gas concentration in the circulation loop is a function of the amount of electricity generated and the elapsed time since the circulation loop is formed, and both can be easily monitored at all times. Therefore, if the amount of electricity generated and the elapsed time since the circulation loop is formed at the time when the decrease in power generation efficiency reaches the above-mentioned unacceptable level are obtained in advance by experiment as their respective predetermined values, these can be used as indicators that can be monitored at all times instead of the above-mentioned upper limit of the allowable nitrogen gas concentration. From the above, the "processing start time" in the fuel cell systems C1 and C2 is detected as the time when the flow path switch 86 is set so that the direction of the hydrogen-containing gas is changed from the final gas discharge line 61 side to the hydrogen gas processing line 87 side, and the amount of electricity generated or the elapsed time since the circulation loop is formed reaches the above-mentioned respective predetermined values. At this timing, the flow path switch 86 can be switched, etc.

[0154] As described above, in the fuel cell system C1, the entire amount of gas that has reached the upper limit of the allowable nitrogen gas concentration and is staying in the circulation loop at the "start time of treatment" is discharged out of the system, and in the fuel cell system C2, the nitrogen gas concentrated in the entire amount is separated and removed using the separation membrane, thereby allowing the nitrogen gas concentration in the circulation loop to be roughly restored to the initial nitrogen gas concentration (for example, about 2 to 5 volume %). The "end time of treatment" is the time when the above treatment is terminated. The mass of gas that has reached the upper limit of the allowable nitrogen gas concentration and is staying in the circulation loop at this "start time of treatment" is roughly calculated by the following formula 4. Formula 4: (The mass of the gas with the maximum allowable nitrogen gas concentration remaining in the circulation loop [kg]) ≒(Circulation loop volume [m 3 ]) × (gas density at internal pressure and temperature of circulation loop [kg / m 3 ]) ≒(Circulation loop volume [m 3 ]) × (nitrogen gas density at circulation loop internal pressure and temperature [kg / m 3 ])

[0155] On the right side of Equation 4, "gas density at the internal pressure and temperature of the circulation loop" is the density of the gas at the maximum allowable nitrogen gas concentration at the internal pressure and temperature of the circulation loop. Nitrogen gas has a density at least one order of magnitude greater than hydrogen gas, so when the nitrogen gas concentration rises to, for example, about 20-30 volume percent, the contribution of the nitrogen gas density becomes dominant in the gas density. For this reason, although the actual value of the maximum allowable nitrogen gas concentration is unknown, we will assume here that it is approximated by the density of pure nitrogen gas. Furthermore, the nitrogen gas density at the internal pressure and temperature of the circulation loop can be calculated using the following Equation 5.

[0156] Formula 5: (Nitrogen gas density at internal pressure and temperature in the circulation loop [kg / m 3 ]) = (nitrogen gas density at standard condition 0.1013 MPa, 0°C 1.250 [kg / m 3 ]) ×273.2 / (273.2 + temperature inside the circulation loop [℃]) × (Circulation loop internal pressure [MPa]) / (0.1013 [MPa])

[0157] In formula 5, the pressure inside the circulation loop can be approximated by the primary pressure of the pressure regulator 85, and the temperature inside the circulation loop can be approximated by the temperature inside the solid polymer electrolyte fuel cell, which is often monitored. Therefore, from formulas 4 and 5, an approximate value of the mass of the gas with the upper limit of the allowable nitrogen gas concentration staying in the circulation loop is calculated. In the fuel cell systems C1 and C2, when processing the hydrogen-containing gas containing nitrogen gas with the upper limit of the allowable nitrogen gas concentration staying in the circulation loop, the mass flow rate per unit time of the gas in the hydrogen gas processing line 87 can be measured by providing, for example, a mass flow meter or the like (not shown). If the above processing is performed for a time obtained by dividing the mass of the gas with the upper limit of the allowable nitrogen gas concentration staying in the circulation loop roughly calculated by formulas 4 and 5 by the measured mass flow rate per unit time, for example, about twice the amount, the processing is estimated to be almost completed. This is regarded as the "processing end point", and the flow path switch 86 can be switched again at this timing.

[0158] (Mobile) Next, the moving body of the embodiment will be described. The moving body includes the above-mentioned fuel cell system C and a motor.

[0159] The motor is a device that is driven by the supply of electric power generated by the polymer electrolyte fuel cell (PEFC) and generates power to propel a moving object. The motor is a load that is connected to the negative and positive electrodes of the fuel cell system C. The motor is preferably connected to the negative and positive terminals of the polymer electrolyte fuel cell (PEFC) that constitutes the cell stack. When power is supplied from the polymer electrolyte fuel cell (PEFC), the motor is driven (for example, to rotate the rotating shaft in a rotary motor, or to move linearly in a linear motor) to output mechanical power.

[0160] The mobile object preferably further comprises a motor and a secondary battery connected to the polymer electrolyte fuel cell (PEFC). The secondary battery is generally connected in parallel to the motor and the polymer electrolyte fuel cell (PEFC), and a floating charge configuration is often adopted in which the secondary battery can be charged while the motor is driven by the polymer electrolyte fuel cell (PEFC) (not shown). This makes it possible to stabilize the power supplied to the motor even if the output of the polymer electrolyte fuel cell (PEFC) or the rotation speed of the motor fluctuates.

[0161] The moving body is, for example, an airspace moving body such as an airplane, helicopter, drone, etc., a land moving body such as a vehicle (passenger car, truck, bus, etc.), a railroad car, cargo handling machine, etc., and a water moving body such as a ship. The moving body further includes a driving body that is driven by the transmission of mechanical power output from the motor to propel the moving body. For example, the driving body is a propeller or rotor that propels the flight of an airspace moving body such as an airplane, helicopter, drone, etc., a wheel or caterpillar that propels the movement of the moving body in a land moving body such as a vehicle (passenger car, truck, bus, etc.), a railroad car, cargo handling machine, etc., and a screw or water jet mechanism that propels the navigation of the moving body in a water moving body such as a ship.

[0162] The mobile body may further include a tank for storing at least a portion of the secondary purified gas discharged from the hydrogen gas production device A or the hydrogen gas supply device B (the high-pressure hydrogen tank described above).

[0163] The tank 1 of the fuel cell system C may be filled with liquefied ammonia as cargo or fuel for a moving object and mounted on the moving object, for example.

[0164] (Hydrogen gas production method) Next, a hydrogen gas production method according to an embodiment will be described. The hydrogen gas production method of the embodiment is a method for producing hydrogen gas by supplying liquefied ammonia as a raw material, and sequentially flowing the supplied liquefied ammonia, ammonia gas obtained by vaporizing the liquefied ammonia, a cracked gas obtained by decomposing the ammonia gas, and a purified gas obtained by purifying the cracked gas in one direction.

[0165] The hydrogen gas production method includes the following steps S1 to S7. Step S1: guiding liquefied ammonia downstream from a tank storing the liquefied ammonia and vaporizing it into ammonia gas. Step S2 of heating the vaporized ammonia gas to a temperature for decomposition. Step S3 in which the ammonia gas heated to the decomposition temperature is brought into contact with a catalyst for decomposition to generate decomposition gas containing hydrogen gas, nitrogen gas and residual ammonia gas. Step S4 of cooling the cracked gas. Step S5 of removing one of the residual ammonia gas and the nitrogen gas from the cooled cracked gas to generate a primary purified gas. Step S6 of removing the other of the residual ammonia gas and the nitrogen gas from the primary purified gas to generate a secondary purified gas. Step S7: reducing the pressure of the purified gas on the upstream side by sucking in the purified gas containing the hydrogen gas that has permeated the separation membrane and discharging it on the downstream side.

[0166] Of step S5 for producing a primary purified gas and step S6 for producing a secondary purified gas, the step for removing residual ammonia gas is a step for adsorbing the residual ammonia gas onto an adsorbent using an adsorbent that adsorbs the residual ammonia gas. Of step S5 for producing a primary purified gas and step S6 for producing a secondary purified gas, the step for removing nitrogen gas is a step in which a separation membrane is used to selectively allow hydrogen gas to permeate by using a pressure difference created between the upstream and downstream sides of the separation membrane to separate hydrogen gas from nitrogen gas.

[0167] By performing the decompression (vacuum exhaust) in the decompression step S7, a pressure difference is formed between the vapor pressure in the tank and the pressure on the downstream side of the separation membrane so that liquefied ammonia, ammonia gas, cracked gas, first purified gas, and second purified gas flow downstream from the tank to the downstream side of the separation membrane. The pressure difference is formed as a pressure drop between the upstream side and the downstream side of the separation membrane caused by the decompression exhaust. In other words, the hydrogen gas production method of the embodiment in which the pressure difference is formed as part of the pressure difference can be performed using, for example, any of the hydrogen gas production device A, hydrogen gas supply device B, and fuel cell system C described above.

[0168] According to the hydrogen gas production method of the embodiment, when hydrogen gas is produced while supplying liquefied ammonia as a raw material, a pressure difference is provided between the vapor pressure in the liquefied ammonia tank and the pressure on the downstream side of the separation membrane, so that gas produced sequentially using liquefied ammonia as a raw material flows downstream without stagnation, and a pressure difference between the upstream side and the downstream side of the separation membrane is formed as part of the pressure difference, so that it is not necessary to use a pressure reducer other than the pressure reducer for forming the pressure difference. In addition, separation of hydrogen gas (removal of nitrogen gas) can be performed without using a high-pressure compressor (for example, one that pressurizes to 1 MPa or more), and therefore less power is consumed. In addition, hydrogen gas can be produced with small and simple equipment.

[0169] The above describes the hydrogen gas production device, hydrogen gas supply device, fuel cell system, mobile body, and hydrogen gas production method of the present invention. However, the present invention is not limited to the above-described embodiments, and various improvements and modifications may be made without departing from the spirit and scope of the present invention. [Explanation of symbols]

[0170] 1 Tank 1a Heater for keeping warm 3. Raw ammonia line 4 Supply valve 5. Carburetor 6 Flow regulator 7 Heating heater 9. Ammonia decomposition section 10. Outside air intake line 11 Decomposition gas line 13 Cooler 15 Primary purification section (ammonia adsorption section shown in figures other than Figure 4) 15A, 15B, 15X, 15Y Ammonia Adsorbers 15a connection line 17 Primary purification gas line 17a Pressurizer 18 Upstream pressure regulator 19 Secondary purification section (hydrogen separation section shown in figures other than Figure 4) 20 Downstream pressure regulator 21 Secondary refinery gas line 22 Pressure reducer 23 Nitrogen gas exhaust line 24 Nitrogen exhaust pressure regulator 25 1st heat exchanger 27 Second cooler 28 Gas line for regeneration treatment 29 Combustor 30 Branch gas line 31 Combustion gas line 32 Outside air intake line 33 Second heat exchanger 35 Regeneration heater 37, 37A, 37B Inert gas introduction line 37c supply port 39, 39A, 39B Desorbed ammonia discharge line 41 Reliquefaction section 42 Compressor 43 Cooler 61 Final gas exhaust line 62 4th cooler 63 Refined Gas Tank 65 Pressurizer 67 A set of changeover valves 67a, 67b, 67c valves 69 Third cooler 79 Refined gas supply pump 81 Solid polymer fuel cell 83 Refined Gas Supply Line 84 Hydrogen-containing gas exhaust line 86 Flow Switch 88 Circulation Pump 87 Hydrogen-containing gas processing line 91 External load

Claims

1. A hydrogen gas production apparatus for producing hydrogen gas by supplying liquefied ammonia as a raw material, the supplied liquefied ammonia, ammonia gas obtained by vaporizing the liquefied ammonia, a decomposition gas obtained by decomposing the ammonia gas, and a purified gas obtained by purifying the decomposition gas, in one direction, a tank for storing liquefied ammonia; a raw ammonia line for guiding the liquefied ammonia from the tank downstream; a vaporizer provided in the raw ammonia line for vaporizing the liquefied ammonia into ammonia gas; a heater for heating the vaporized ammonia gas to a temperature for decomposition; an ammonia decomposition unit connected to the raw ammonia line downstream of the vaporizer, for decomposing the ammonia gas heated to the decomposition temperature by bringing the ammonia gas into contact with a catalyst to generate a decomposed gas containing hydrogen gas, nitrogen gas, and residual ammonia gas; a decomposition gas line connected to the ammonia decomposition unit and guiding the decomposition gas downstream; a cooler provided in the decomposition gas line for cooling the decomposition gas; a primary purification section connected to the cracked gas line downstream of the cooler, for removing one of the residual ammonia gas and the nitrogen gas from the cooled cracked gas to produce a primary purified gas; a primary purified gas line connected to the primary purification section and guiding the primary purified gas downstream; a secondary purification unit connected to the primary purified gas line, for removing the other of the residual ammonia gas and the nitrogen gas from the primary purified gas to generate a secondary purified gas; a secondary purified gas line connected to the secondary purification section, which guides the secondary purified gas downstream and discharges it; the refining section from which the residual ammonia gas is removed out of the primary refining section and the secondary refining section is an ammonia adsorption section having an adsorbent that adsorbs the residual ammonia gas, a hydrogen separation unit, wherein one of the primary purification unit and the secondary purification unit from which the nitrogen gas is removed has a separation membrane, and the separation membrane is configured to selectively allow the hydrogen gas to permeate and separate it from the nitrogen gas by a pressure difference created between an upstream side and a downstream side of the separation membrane; the hydrogen gas production apparatus further includes a pressure reducer provided in a purified gas line, one of the primary purified gas line and the secondary purified gas line, that is connected to the hydrogen separation unit and through which the hydrogen gas that has permeated the separation membrane flows, the pressure reducer sucking in the purified gas flowing through the purified gas line and discharging it downstream to reduce the pressure of the purified gas upstream of the pressure reducer; By reducing the pressure on the upstream side of the pressure reducer, a pressure difference is formed between the vapor pressure of the ammonia gas vaporized in the tank and the pressure on the upstream side of the pressure reducer so that the liquefied ammonia, the ammonia gas, the decomposition gas, and the purified gas flow downstream from the tank to the secondary purified gas line, and the differential pressure is formed as part of the pressure difference; the heater for raising the temperature is provided downstream of the vaporizer in the raw ammonia line, a combustor that combusts, together with air, a portion of any of the cracked gas, the primary purified gas, and the secondary purified gas extracted from the ammonia decomposition section or downstream of the ammonia decomposition section, and discharges a combustion gas; a combustion gas line connected to the combustor and through which the combustion gas flows, a part of the combustion gas line and the heater for temperature increase constitute a first heat exchanger having a first high-temperature side flow path through which the combustion gas flows and a first low-temperature side flow path through which the ammonia gas flows, The hydrogen gas production device is configured such that the combustion gas is cooled and the temperature of the ammonia gas is increased by heat exchange between the combustion gas flowing through the first high-temperature side flow path and the ammonia gas flowing through the first low-temperature side flow path.

2. 2. The hydrogen gas production device according to claim 1, wherein a compressor for increasing the pressure of the decomposed gas or the primary purified gas is not provided upstream of the separation membrane.

3. 2. The hydrogen gas production device according to claim 1, further comprising a compressor for increasing the pressure of the cracked gas or the primary purified gas, provided upstream of the hydrogen separation section.

4. 3. The hydrogen gas production apparatus according to claim 1, wherein the tank has a heater for heat retention that maintains the vapor pressure by heating the inside of the tank so that the flow of the liquefied ammonia, the ammonia gas, the decomposed gas, and the purified gas downstream from the tank to the secondary purified gas line is maintained.

5. the cooler and the vaporizer constitute a second heat exchanger having a second high-temperature side passage through which the cracked gas flows and a second low-temperature side passage through which the liquefied ammonia flows, 3. The hydrogen gas production device according to claim 1, wherein the second heat exchanger is configured to cool the decomposition gas and heat and vaporize the liquefied ammonia by heat exchange between the decomposition gas flowing through the second high-temperature side flow path and the liquefied ammonia flowing through the second low-temperature side flow path.

6. The hydrogen gas production device according to claim 5, further comprising a second cooler provided upstream or downstream of the first cooler in the decomposition gas line to cool the decomposition gas, when the cooler is referred to as a first cooler.

7. 7. The hydrogen gas production device according to claim 6, wherein the decomposition gas passing through the second cooler is cooled by heat exchange with external air or a liquid refrigerant cooled by heat exchange with external air.

8. A hydrogen gas production apparatus for producing hydrogen gas by supplying liquefied ammonia as a raw material, and sequentially flowing the supplied liquefied ammonia, ammonia gas obtained by vaporizing the liquefied ammonia, decomposed gas obtained by decomposing the ammonia gas, and purified gas obtained by purifying the decomposed gas in one direction, a tank for storing liquefied ammonia; a raw ammonia line for guiding the liquefied ammonia from the tank downstream; a vaporizer provided in the raw ammonia line for vaporizing the liquefied ammonia into ammonia gas; a heater for heating the vaporized ammonia gas to a temperature for decomposition; an ammonia decomposition unit connected to the raw ammonia line downstream of the vaporizer, for decomposing the ammonia gas heated to the decomposition temperature by bringing the ammonia gas into contact with a catalyst to generate a decomposed gas containing hydrogen gas, nitrogen gas, and residual ammonia gas; a decomposition gas line connected to the ammonia decomposition unit and guiding the decomposition gas downstream; a cooler provided in the decomposition gas line for cooling the decomposition gas; a primary purification section connected to the cracked gas line downstream of the cooler, for removing one of the residual ammonia gas and the nitrogen gas from the cooled cracked gas to produce a primary purified gas; a primary purified gas line connected to the primary purification section and guiding the primary purified gas downstream; a secondary purification unit connected to the primary purified gas line, for removing the other of the residual ammonia gas and the nitrogen gas from the primary purified gas to generate a secondary purified gas; a secondary purified gas line connected to the secondary purification section, which guides the secondary purified gas downstream and discharges it; the refining section from which the residual ammonia gas is removed out of the primary refining section and the secondary refining section is an ammonia adsorption section having an adsorbent that adsorbs the residual ammonia gas, a hydrogen separation unit, wherein one of the primary purification unit and the secondary purification unit from which the nitrogen gas is removed has a separation membrane, and the separation membrane is configured to selectively allow the hydrogen gas to permeate and separate it from the nitrogen gas by a pressure difference created between an upstream side and a downstream side of the separation membrane; the hydrogen gas production apparatus further includes a pressure reducer provided in a purified gas line, one of the primary purified gas line and the secondary purified gas line, that is connected to the hydrogen separation unit and through which the hydrogen gas that has permeated the separation membrane flows, the pressure reducer sucking in the purified gas flowing through the purified gas line and discharging it downstream to reduce the pressure of the purified gas upstream of the pressure reducer; By reducing the pressure on the upstream side of the pressure reducer, a pressure difference is formed between the vapor pressure of the ammonia gas vaporized in the tank and the pressure on the upstream side of the pressure reducer so that the liquefied ammonia, the ammonia gas, the decomposition gas, and the purified gas flow downstream from the tank to the secondary purified gas line, and the differential pressure is formed as part of the pressure difference; the ammonia adsorption unit includes a regeneration heater that heats the adsorbent that has adsorbed the residual ammonia gas, an inert gas introduction line that introduces an inert gas from the outside, and a desorbed ammonia discharge line through which the residual ammonia gas desorbed from the adsorbent flows; the ammonia adsorption unit is heated by the regeneration heater, whereby the residual ammonia gas adsorbed on the adsorbent is desorbed from the adsorbent and discharged from the ammonia adsorption unit through the desorbed ammonia discharge line together with the inert gas introduced through the inert gas inlet line.

9. a combustor that combusts a portion of any of the cracked gas, the primary purified gas, and the secondary purified gas, which are extracted from the ammonia decomposition section or downstream of the ammonia decomposition section, together with air, and discharges the combustion gas; 9. The hydrogen gas production device according to claim 8, wherein the residual ammonia gas discharged together with the inert gas is introduced into the combustor and combusted.

10. the heater for raising the temperature is provided downstream of the vaporizer in the raw ammonia line, the hydrogen gas production apparatus further includes a combustion gas line connected to the combustor and through which the combustion gas flows; a part of the combustion gas line and the heater for temperature increase constitute a first heat exchanger having a first high-temperature side flow path through which the combustion gas flows and a first low-temperature side flow path through which the ammonia gas flows, 10. The hydrogen gas production device according to claim 9, wherein the first heat exchanger is configured to cool the combustion gas and raise the temperature of the ammonia gas by heat exchange between the combustion gas flowing through the first high-temperature side passage and the ammonia gas flowing through the first low-temperature side passage.

11. a re-liquefaction unit connected to the desorbed ammonia discharge line and the tank, and configured to liquefy the residual ammonia gas desorbed from the adsorbent to separate it from the inert gas; 9. The hydrogen gas production device according to claim 8, wherein the residual ammonia gas discharged together with the inert gas is guided to the re-liquefaction section, liquefied and separated from the inert gas, and recovered in the tank.

12. the ammonia adsorption unit has a plurality of ammonia adsorbers arranged in parallel in the one direction, each of the plurality of ammonia adsorbers includes the adsorbent, the inert gas introduction line, and the desorbed ammonia discharge line; 12. The hydrogen gas production apparatus according to claim 8, wherein the ammonia adsorption unit is configured such that, in one or more ammonia adsorbers among the plurality of ammonia adsorbers, the residual ammonia gas desorbed from the adsorbent by heating by the regenerative heater is discharged through the desorbed ammonia discharge line together with the inert gas introduced from the inert gas inlet line, while the decomposed gas or the primary purified gas is introduced into the remaining ammonia adsorbers, the residual ammonia gas in the gas is adsorbed by the adsorbent of the ammonia adsorber and removed, and the decomposed gas or the primary purified gas from which the residual ammonia gas has been removed is guided downstream of the ammonia adsorption unit, and the one or more ammonia adsorbers and the remaining ammonia adsorbers are switchable among the plurality of ammonia adsorbers.

13. A hydrogen gas production apparatus for producing hydrogen gas by supplying liquefied ammonia as a raw material, and sequentially flowing the supplied liquefied ammonia, ammonia gas obtained by vaporizing the liquefied ammonia, decomposed gas obtained by decomposing the ammonia gas, and purified gas obtained by purifying the decomposed gas in one direction, a tank for storing liquefied ammonia; a raw ammonia line for guiding the liquefied ammonia from the tank downstream; a vaporizer provided in the raw ammonia line for vaporizing the liquefied ammonia into ammonia gas; a heater for heating the vaporized ammonia gas to a temperature for decomposition; an ammonia decomposition unit connected to the raw ammonia line downstream of the vaporizer, for decomposing the ammonia gas heated to the decomposition temperature by bringing the ammonia gas into contact with a catalyst to generate a decomposed gas containing hydrogen gas, nitrogen gas, and residual ammonia gas; a decomposition gas line connected to the ammonia decomposition unit and guiding the decomposition gas downstream; a cooler provided in the decomposition gas line for cooling the decomposition gas; a primary purification section connected to the cracked gas line downstream of the cooler, for removing one of the residual ammonia gas and the nitrogen gas from the cooled cracked gas to produce a primary purified gas; a primary purified gas line connected to the primary purification section and guiding the primary purified gas downstream; a secondary purification unit connected to the primary purified gas line, for removing the other of the residual ammonia gas and the nitrogen gas from the primary purified gas to generate a secondary purified gas; a secondary purified gas line connected to the secondary purification section, which guides the secondary purified gas downstream and discharges it; the refining section from which the residual ammonia gas is removed out of the primary refining section and the secondary refining section is an ammonia adsorption section having an adsorbent that adsorbs the residual ammonia gas, a hydrogen separation unit, wherein one of the primary purification unit and the secondary purification unit from which the nitrogen gas is removed has a separation membrane, and the separation membrane is configured to selectively allow the hydrogen gas to permeate and separate it from the nitrogen gas by a pressure difference created between an upstream side and a downstream side of the separation membrane; the hydrogen gas production apparatus further includes a pressure reducer provided in a purified gas line, one of the primary purified gas line and the secondary purified gas line, that is connected to the hydrogen separation unit and through which the hydrogen gas that has permeated the separation membrane flows, the pressure reducer sucking in the purified gas flowing through the purified gas line and discharging it downstream to reduce the pressure of the purified gas upstream of the pressure reducer; By reducing the pressure on the upstream side of the pressure reducer, a pressure difference is formed between the vapor pressure of the ammonia gas vaporized in the tank and the pressure on the upstream side of the pressure reducer so that the liquefied ammonia, the ammonia gas, the decomposition gas, and the purified gas flow downstream from the tank to the secondary purified gas line, and the differential pressure is formed as part of the pressure difference; the ammonia adsorption unit includes a plurality of ammonia adsorbers arranged in series in the one direction, each of the plurality of ammonia adsorbers including the adsorbent; the adsorbent of a first ammonia adsorber among the plurality of ammonia adsorbers is an adsorbent having Lewis acid sites, and the adsorbent of a second ammonia adsorber disposed downstream of the first ammonia adsorber is an adsorbent having Bronsted acid sites.

14. 3. The hydrogen gas production apparatus according to claim 1, further comprising: a flow rate regulator provided in the raw ammonia line downstream of the vaporizer to regulate a flow rate of the ammonia gas; and / or an upstream pressure regulator provided in the gas line through which the decomposed gas or the purified gas guided to the hydrogen separation section flows and regulating a pressure of the gas flowing in the gas line.

15. 3. The hydrogen gas production device according to claim 1, wherein the primary purification section is the ammonia adsorption section, and the secondary purification section is the hydrogen separation section.

16. A hydrogen gas supply device that supplies hydrogen gas to a supply destination, The hydrogen gas production device according to claim 1; a final gas discharge line connected to a secondary purified gas line of the hydrogen gas production apparatus, which guides and discharges the secondary purified gas discharged from the secondary purified gas line toward the supply destination, the final gas discharge line having a branch portion that branches off so that the secondary purified gas flows to a side different from the supply destination; a purified gas tank connected to the branching portion and configured to store the secondary purified gas flowing to the different side; a compressor provided in the final gas discharge line upstream of the branching portion, for pressurizing the secondary purified gas into the purified gas tank; a set of switching valves provided in the final gas discharge line for switching the flow path of the secondary purified gas flowing through the final gas discharge line, the set of switching valves switching whether the secondary purified gas discharged from the secondary purified gas line flows toward the purified gas tank, the secondary purified gas in the purified gas tank is guided to the supply destination side and discharged, or the secondary purified gas discharged from the secondary purified gas line is guided to the supply destination side and discharged.

17. The hydrogen gas production device according to claim 1 or the hydrogen gas supply device according to claim 16; a polymer electrolyte fuel cell having an anode and a cathode, the anode and the cathode being connected to an external load, and configured to generate electricity by supplying secondary purified gas discharged from the hydrogen gas production device or the hydrogen gas supply device to the anode and air to the cathode.

18. A hydrogen gas production device or a hydrogen gas supply device, A fuel cell system comprising the following solid polymer fuel cell: The hydrogen gas production equipment A hydrogen gas production apparatus for producing hydrogen gas by supplying liquefied ammonia as a raw material, the supplied liquefied ammonia, ammonia gas obtained by vaporizing the liquefied ammonia, a decomposition gas obtained by decomposing the ammonia gas, and a purified gas obtained by purifying the decomposition gas, in one direction, a tank for storing liquefied ammonia; a raw ammonia line for guiding the liquefied ammonia from the tank downstream; a vaporizer provided in the raw ammonia line for vaporizing the liquefied ammonia into ammonia gas; a heater for heating the vaporized ammonia gas to a temperature for decomposition; an ammonia decomposition unit connected to the raw ammonia line downstream of the vaporizer, for decomposing the ammonia gas heated to the decomposition temperature by bringing the ammonia gas into contact with a catalyst to generate a decomposed gas containing hydrogen gas, nitrogen gas, and residual ammonia gas; a decomposition gas line connected to the ammonia decomposition unit and guiding the decomposition gas downstream; a cooler provided in the decomposition gas line for cooling the decomposition gas; a primary purification section connected to the cracked gas line downstream of the cooler, for removing one of the residual ammonia gas and the nitrogen gas from the cooled cracked gas to produce a primary purified gas; a primary purified gas line connected to the primary purification section and guiding the primary purified gas downstream; a secondary purification unit connected to the primary purified gas line, for removing the other of the residual ammonia gas and the nitrogen gas from the primary purified gas to generate a secondary purified gas; a secondary purified gas line connected to the secondary purification section, which guides the secondary purified gas downstream and discharges it; the refining section from which the residual ammonia gas is removed out of the primary refining section and the secondary refining section is an ammonia adsorption section having an adsorbent that adsorbs the residual ammonia gas, a hydrogen separation unit, wherein one of the primary purification unit and the secondary purification unit from which the nitrogen gas is removed has a separation membrane, and the separation membrane is configured to selectively allow the hydrogen gas to permeate and separate it from the nitrogen gas by a pressure difference created between an upstream side and a downstream side of the separation membrane; the hydrogen gas production apparatus further includes a pressure reducer provided in a purified gas line, one of the primary purified gas line and the secondary purified gas line, that is connected to the hydrogen separation unit and through which the hydrogen gas that has permeated the separation membrane flows, the pressure reducer sucking in the purified gas flowing through the purified gas line and discharging it downstream to reduce the pressure of the purified gas upstream of the pressure reducer; a hydrogen gas production apparatus, wherein the pressure on the upstream side of the pressure reducer is reduced, thereby forming a pressure difference between the vapor pressure of ammonia gas vaporized in the tank and the pressure on the upstream side of the pressure reducer, so that the liquefied ammonia, the ammonia gas, the decomposition gas, and the purified gas flow downstream from the tank to the secondary purified gas line, and the differential pressure is formed as part of the pressure difference; The hydrogen gas supply device is A hydrogen gas supply device that supplies hydrogen gas to a supply destination, The hydrogen gas production device; a final gas discharge line connected to a secondary purified gas line of the hydrogen gas production apparatus, which guides and discharges the secondary purified gas discharged from the secondary purified gas line toward the supply destination, the final gas discharge line having a branch portion that branches off so that the secondary purified gas flows to a side different from the supply destination; a purified gas tank connected to the branching portion and configured to store the secondary purified gas flowing to the different side; a compressor provided in the final gas discharge line upstream of the branching portion, for pressurizing the secondary purified gas into the purified gas tank; a set of switching valves that are provided in the final gas discharge line and switch a flow path of the secondary purified gas flowing through the final gas discharge line, the set of switching valves switching whether the secondary purified gas discharged from the secondary purified gas line flows toward the purified gas tank, the secondary purified gas in the purified gas tank is guided to the supply destination side and discharged, or the secondary purified gas discharged from the secondary purified gas line is guided to the supply destination side and discharged, Polymer electrolyte fuel cells are a polymer electrolyte fuel cell including an anode and a cathode, the anode and the cathode being connected to an external load, and configured to generate electricity by supplying a secondary purified gas discharged from the hydrogen gas production device or the hydrogen gas supply device to the anode and air to the cathode; The fuel cell system includes: a purified gas supply line connected to a secondary purified gas line of the hydrogen gas production device or a final gas discharge line of the hydrogen gas supply device, for guiding the secondary purified gas discharged from the line to the negative electrode; a hydrogen-containing gas discharge line provided with a flow path switch, which guides a hydrogen-containing gas containing surplus hydrogen gas, which is not consumed during the power generation and is discharged from the negative electrode, and nitrogen gas, which is contained in the secondary purified gas and has permeated a separation membrane of the hydrogen gas production device, to the secondary purified gas line or the final gas discharge line connected to the purified gas supply line, and merges the hydrogen-containing gas with the secondary purified gas; a hydrogen-containing gas treatment line that branches off from the hydrogen-containing gas discharge line via the flow path switch and discharges the hydrogen-containing gas to the outside, the flow path switch is configured to switch the flow direction of the hydrogen-containing gas to one of the secondary purified gas line side or the final gas discharge line side and the hydrogen-containing gas treatment line side; the flow direction of the hydrogen-containing gas is switched to the side of the secondary purified gas line or the final gas discharge line, so that the hydrogen-containing gas is circulated and supplied to the negative electrode together with the secondary purified gas discharged from the secondary purified gas line or the final gas discharge line; When the amount of electricity generated by the polymer electrolyte fuel cell or the elapsed time during the power generation from the time when the flow direction of the hydrogen-containing gas is switched to the secondary purified gas line or the final gas discharge line reaches a predetermined value, the flow direction of the hydrogen-containing gas is switched to the hydrogen-containing gas treatment line side, and the hydrogen-containing gas containing the concentrated nitrogen gas from that time is discharged to the outside, A fuel cell system configured such that, upon completion of discharge of the hydrogen-containing gas containing the concentrated nitrogen gas from the hydrogen-containing gas processing line to the outside, the flow direction of the hydrogen-containing gas is switched to the side of the secondary purified gas line or the final gas discharge line.

19. The following hydrogen gas production device or the following hydrogen gas supply device, A fuel cell system comprising the following solid polymer fuel cell: The hydrogen gas production equipment A hydrogen gas production apparatus for producing hydrogen gas by supplying liquefied ammonia as a raw material, the supplied liquefied ammonia, ammonia gas obtained by vaporizing the liquefied ammonia, a decomposition gas obtained by decomposing the ammonia gas, and a purified gas obtained by purifying the decomposition gas, in one direction, a tank for storing liquefied ammonia; a raw ammonia line for guiding the liquefied ammonia from the tank downstream; a vaporizer provided in the raw ammonia line for vaporizing the liquefied ammonia into ammonia gas; a heater for heating the vaporized ammonia gas to a temperature for decomposition; an ammonia decomposition unit connected to the raw ammonia line downstream of the vaporizer, for decomposing the ammonia gas heated to the decomposition temperature by bringing the ammonia gas into contact with a catalyst to generate a decomposed gas containing hydrogen gas, nitrogen gas, and residual ammonia gas; a decomposition gas line connected to the ammonia decomposition unit and guiding the decomposition gas downstream; a cooler provided in the decomposition gas line for cooling the decomposition gas; a primary purification section connected to the cracked gas line downstream of the cooler, for removing one of the residual ammonia gas and the nitrogen gas from the cooled cracked gas to produce a primary purified gas; a primary purified gas line connected to the primary purification section and guiding the primary purified gas downstream; a secondary purification unit connected to the primary purified gas line, for removing the other of the residual ammonia gas and the nitrogen gas from the primary purified gas to generate a secondary purified gas; a secondary purified gas line connected to the secondary purification section, which guides the secondary purified gas downstream and discharges it; the refining section from which the residual ammonia gas is removed out of the primary refining section and the secondary refining section is an ammonia adsorption section having an adsorbent that adsorbs the residual ammonia gas, a hydrogen separation unit, wherein one of the primary purification unit and the secondary purification unit from which the nitrogen gas is removed has a separation membrane, and the separation membrane is configured to selectively allow the hydrogen gas to permeate and separate it from the nitrogen gas by a pressure difference created between an upstream side and a downstream side of the separation membrane; the hydrogen gas production apparatus further includes a pressure reducer provided in a purified gas line, one of the primary purified gas line and the secondary purified gas line, that is connected to the hydrogen separation unit and through which the hydrogen gas that has permeated the separation membrane flows, the pressure reducer sucking in the purified gas flowing through the purified gas line and discharging it downstream to reduce the pressure of the purified gas upstream of the pressure reducer; a hydrogen gas production apparatus, wherein the pressure on the upstream side of the pressure reducer is reduced, thereby forming a pressure difference between the vapor pressure of ammonia gas vaporized in the tank and the pressure on the upstream side of the pressure reducer, so that the liquefied ammonia, the ammonia gas, the decomposition gas, and the purified gas flow downstream from the tank to the secondary purified gas line, and the differential pressure is formed as part of the pressure difference; The hydrogen gas supply device is A hydrogen gas supply device that supplies hydrogen gas to a supply destination, The hydrogen gas production device; a final gas discharge line connected to a secondary purified gas line of the hydrogen gas production apparatus, which guides and discharges the secondary purified gas discharged from the secondary purified gas line toward the supply destination, the final gas discharge line having a branch portion that branches off so that the secondary purified gas flows to a side different from the supply destination; a purified gas tank connected to the branching portion and configured to store the secondary purified gas flowing to the different side; a compressor provided in the final gas discharge line upstream of the branching portion, for pressurizing the secondary purified gas into the purified gas tank; a set of switching valves that are provided in the final gas discharge line and switch a flow path of the secondary purified gas flowing through the final gas discharge line, the set of switching valves switching whether the secondary purified gas discharged from the secondary purified gas line flows toward the purified gas tank, the secondary purified gas in the purified gas tank is guided to the supply destination side and discharged, or the secondary purified gas discharged from the secondary purified gas line is guided to the supply destination side and discharged, Polymer electrolyte fuel cells are a polymer electrolyte fuel cell including an anode and a cathode, the anode and the cathode being connected to an external load, and configured to generate electricity by supplying a secondary purified gas discharged from the hydrogen gas production device or the hydrogen gas supply device to the anode and air to the cathode; the primary purification unit of the hydrogen gas production device and the hydrogen gas supply device is an ammonia adsorption unit, and the secondary purification unit is a hydrogen separation unit; a purified gas supply line connected to a secondary purified gas line of the hydrogen gas production device or a final gas discharge line of the hydrogen gas supply device, for guiding the secondary purified gas discharged from the line to the negative electrode; a hydrogen-containing gas discharge line provided with a flow path switch, which guides a hydrogen-containing gas containing surplus hydrogen gas, which is not consumed during the power generation and is discharged from the negative electrode, and nitrogen gas, which is contained in the secondary purified gas and has permeated a separation membrane of the hydrogen gas production device, to the secondary purified gas line or the final gas discharge line connected to the purified gas supply line, and merges the hydrogen-containing gas with the secondary purified gas; a hydrogen-containing gas treatment line branching from the hydrogen-containing gas discharge line via the flow path switch and connected to a primary purified gas line of the hydrogen gas production apparatus or the hydrogen gas supply apparatus, the flow path switch is configured to switch the flow direction of the hydrogen-containing gas to one of the secondary purified gas line side or the final gas discharge line side and the hydrogen-containing gas treatment line side; the flow direction of the hydrogen-containing gas is switched to the side of the secondary purified gas line or the final gas discharge line, so that the hydrogen-containing gas is circulated and supplied to the negative electrode together with the secondary purified gas discharged from the secondary purified gas line or the final gas discharge line; When the amount of electricity generated by the polymer electrolyte fuel cell or the elapsed time during the power generation from the time point when the flow direction of the hydrogen-containing gas is switched to the secondary purified gas line or the final gas discharge line reaches a predetermined value, the flow direction of the hydrogen-containing gas is switched to the hydrogen-containing gas treatment line side, and the hydrogen-containing gas containing the concentrated nitrogen gas from that point on is led to the primary purified gas line via the hydrogen-containing gas treatment line, merges with the primary purified gas flowing in the primary purified line, and is led to the hydrogen separation unit, where the nitrogen gas is separated and removed by the separation membrane, and the secondary purified gas after the merger from which the nitrogen gas has been separated and removed is supplied to the negative electrode via the secondary purified gas line or the final gas discharge line and the purified gas supply line, A fuel cell system configured such that, upon completion of the separation and removal of the nitrogen gas from the primary purified gas after the merging, the flow direction of the hydrogen-containing gas is switched to the side of the secondary purified gas line or the final gas discharge line.

20. A mobile body comprising the following fuel cell system and the following motor: The fuel cell system The following hydrogen gas production device or the following hydrogen gas supply device, A fuel cell system comprising the following solid polymer fuel cell: The hydrogen gas production equipment A hydrogen gas production apparatus for producing hydrogen gas by supplying liquefied ammonia as a raw material, the supplied liquefied ammonia, ammonia gas obtained by vaporizing the liquefied ammonia, a decomposition gas obtained by decomposing the ammonia gas, and a purified gas obtained by purifying the decomposition gas, in one direction, a tank for storing liquefied ammonia; a raw ammonia line for guiding the liquefied ammonia from the tank downstream; a vaporizer provided in the raw ammonia line for vaporizing the liquefied ammonia into ammonia gas; a heater for heating the vaporized ammonia gas to a temperature for decomposition; an ammonia decomposition unit connected to the raw ammonia line downstream of the vaporizer, for decomposing the ammonia gas heated to the decomposition temperature by bringing the ammonia gas into contact with a catalyst to generate a decomposed gas containing hydrogen gas, nitrogen gas, and residual ammonia gas; a decomposition gas line connected to the ammonia decomposition unit and guiding the decomposition gas downstream; a cooler provided in the decomposition gas line for cooling the decomposition gas; a primary purification section connected to the cracked gas line downstream of the cooler, for removing one of the residual ammonia gas and the nitrogen gas from the cooled cracked gas to produce a primary purified gas; a primary purified gas line connected to the primary purification section and guiding the primary purified gas downstream; a secondary purification unit connected to the primary purified gas line, for removing the other of the residual ammonia gas and the nitrogen gas from the primary purified gas to generate a secondary purified gas; a secondary purified gas line connected to the secondary purification section, which guides the secondary purified gas downstream and discharges it; the refining section from which the residual ammonia gas is removed out of the primary refining section and the secondary refining section is an ammonia adsorption section having an adsorbent that adsorbs the residual ammonia gas, a hydrogen separation unit, wherein one of the primary purification unit and the secondary purification unit from which the nitrogen gas is removed has a separation membrane, and the separation membrane is configured to selectively allow the hydrogen gas to permeate and separate it from the nitrogen gas by a pressure difference created between an upstream side and a downstream side of the separation membrane; the hydrogen gas production apparatus further includes a pressure reducer provided in a purified gas line, one of the primary purified gas line and the secondary purified gas line, that is connected to the hydrogen separation unit and through which the hydrogen gas that has permeated the separation membrane flows, the pressure reducer sucking in the purified gas flowing through the purified gas line and discharging it downstream to reduce the pressure of the purified gas upstream of the pressure reducer; a hydrogen gas production apparatus, wherein the pressure on the upstream side of the pressure reducer is reduced, thereby forming a pressure difference between the vapor pressure of ammonia gas vaporized in the tank and the pressure on the upstream side of the pressure reducer, so that the liquefied ammonia, the ammonia gas, the decomposition gas, and the purified gas flow downstream from the tank to the secondary purified gas line, and the differential pressure is formed as part of the pressure difference; The hydrogen gas supply device is A hydrogen gas supply device that supplies hydrogen gas to a supply destination, The hydrogen gas production device; a final gas discharge line connected to a secondary purified gas line of the hydrogen gas production apparatus, which guides and discharges the secondary purified gas discharged from the secondary purified gas line toward the supply destination, the final gas discharge line having a branch portion that branches off so that the secondary purified gas flows to a side different from the supply destination; a purified gas tank connected to the branching portion and configured to store the secondary purified gas flowing to the different side; a compressor provided in the final gas discharge line upstream of the branching portion, for pressurizing the secondary purified gas into the purified gas tank; a set of switching valves that are provided in the final gas discharge line and switch a flow path of the secondary purified gas flowing through the final gas discharge line, the set of switching valves switching whether the secondary purified gas discharged from the secondary purified gas line flows toward the purified gas tank, the secondary purified gas in the purified gas tank is guided to the supply destination side and discharged, or the secondary purified gas discharged from the secondary purified gas line is guided to the supply destination side and discharged, Polymer electrolyte fuel cells are a polymer electrolyte fuel cell including an anode and a cathode, the anode and the cathode being connected to an external load, and configured to generate electricity by supplying a secondary purified gas discharged from the hydrogen gas production device or the hydrogen gas supply device to the anode and air to the cathode; The motor is A moving body is a motor that is connected to the negative electrode and the positive electrode of the fuel cell system, is driven by the supply of electricity generated by the fuel cell of the fuel cell system, and generates power to propel the moving body.

21. A hydrogen gas production method for producing hydrogen gas by supplying liquefied ammonia as a raw material, and sequentially flowing the supplied liquefied ammonia, ammonia gas obtained by vaporizing the liquefied ammonia, a decomposed gas obtained by decomposing the ammonia gas, and a purified gas obtained by purifying the decomposed gas in one direction, A step of guiding the liquefied ammonia from a tank storing the liquefied ammonia downstream and vaporizing the liquefied ammonia into ammonia gas; heating the vaporized ammonia gas to a decomposition temperature; a step of bringing the ammonia gas heated to the decomposition temperature into contact with a catalyst to decompose the ammonia gas, thereby generating a decomposed gas containing hydrogen gas, nitrogen gas, and residual ammonia gas; cooling the cracked gas; removing one of the residual ammonia gas and the nitrogen gas from the cooled cracked gas to generate a primary purified gas; removing the other of the residual ammonia gas and the nitrogen gas from the primary purified gas to generate a secondary purified gas; a step of removing the residual ammonia gas from the step of generating the primary purified gas and the step of generating the secondary purified gas, the step of removing the residual ammonia gas from the residual ammonia gas by using an adsorbent that adsorbs the residual ammonia gas; The step of removing the nitrogen gas from the step of generating the primary purified gas and the step of generating the secondary purified gas is a step of separating the hydrogen gas from the nitrogen gas by selectively allowing the hydrogen gas to permeate through a ceramic or polymer separation membrane by a pressure difference created between an upstream side and a downstream side of the separation membrane, The hydrogen gas production method further includes a step of reducing the pressure of the purified gas upstream by sucking in the purified gas containing the hydrogen gas that has permeated the separation membrane and discharging it downstream, a pressure difference is formed between the vapor pressure of ammonia gas vaporized in the tank and the pressure on the upstream side, such that the liquefied ammonia, the ammonia gas, the decomposed gas, and the purified gas flow downstream from the tank to the downstream side of the separation membrane by reducing the pressure on the upstream side, and the differential pressure is formed as part of the pressure difference, and the differential pressure is 0.5 MPa to 0.9 MPa.

22. A hydrogen gas production apparatus for producing hydrogen gas by supplying liquefied ammonia as a raw material, and sequentially flowing the supplied liquefied ammonia, ammonia gas obtained by vaporizing the liquefied ammonia, decomposed gas obtained by decomposing the ammonia gas, and purified gas obtained by purifying the decomposed gas in one direction, a tank for storing liquefied ammonia; a raw ammonia line for guiding the liquefied ammonia from the tank downstream; a vaporizer provided in the raw ammonia line for vaporizing the liquefied ammonia into ammonia gas; a heater for heating the vaporized ammonia gas to a temperature for decomposition; an ammonia decomposition unit connected to the raw ammonia line downstream of the vaporizer, for decomposing the ammonia gas heated to the decomposition temperature by bringing the ammonia gas into contact with a catalyst to generate a decomposed gas containing hydrogen gas, nitrogen gas, and residual ammonia gas; a decomposition gas line connected to the ammonia decomposition unit and guiding the decomposition gas downstream; a cooler provided in the decomposition gas line for cooling the decomposition gas; a primary purification section connected to the cracked gas line downstream of the cooler, for removing one of the residual ammonia gas and the nitrogen gas from the cooled cracked gas to produce a primary purified gas; a primary purified gas line connected to the primary purification section and guiding the primary purified gas downstream; a secondary purification unit connected to the primary purified gas line, for removing the other of the residual ammonia gas and the nitrogen gas from the primary purified gas to generate a secondary purified gas; a secondary purified gas line connected to the secondary purification section, which guides the secondary purified gas downstream and discharges it; the refining section from which the residual ammonia gas is removed out of the primary refining section and the secondary refining section is an ammonia adsorption section having an adsorbent that adsorbs the residual ammonia gas, a hydrogen separation unit in which one of the primary purification unit and the secondary purification unit from which the nitrogen gas is removed has a separation membrane, the separation membrane being a ceramic separation membrane or a polymer separation membrane configured to selectively permeate the hydrogen gas and separate it from the nitrogen gas by a pressure difference created between the upstream side and the downstream side of the separation membrane; the hydrogen gas production apparatus further includes a pressure reducer provided in a purified gas line, one of the primary purified gas line and the secondary purified gas line, that is connected to the hydrogen separation unit and through which the hydrogen gas that has permeated the separation membrane flows, the pressure reducer sucking in the purified gas flowing through the purified gas line and discharging it downstream to reduce the pressure of the purified gas upstream of the pressure reducer; a pressure difference is formed between the vapor pressure of ammonia gas vaporized in the tank and the pressure upstream of the pressure reducer, and the pressure difference is formed as part of the pressure difference, so that the liquefied ammonia, the ammonia gas, the decomposition gas, and the purified gas flow downstream from the tank to the secondary purified gas line by reducing the pressure upstream of the pressure reducer, and the pressure difference is 0.5 MPa to 0.9 MPa.

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