Ammonia-hydrogen mixed fuel production device, fuel supply system, and hydrogen production method

Abstract

[Problem] To provide: an ammonia-hydrogen mixed fuel production device capable of stably obtaining hydrogen from ammonia even when the required ratio of fuel is changed; and a fuel supply system. [Solution] The present invention comprises: an oxygen supply unit 1013 for supplying oxygen having a desired concentration; a raw material supply unit 1014 for supplying ammonia, which is a raw material gas, having a desired concentration; a reforming reactor 1015 which converts the ammonia into hydrogen by using the oxygen having a desired concentration and supplied from the oxygen supply unit 1013, and thereby forms a reformed gas G12; a gas component analyzer 1017 which is provided in a reformed gas discharge line L4 for discharging the reformed gas G12 from the reforming reactor 1015, and which measures the concentration of the hydrogen and / or the ammonia in the reformed gas G12; and a plate-type heat exchanger 1030 which is provided at an intersection part between a raw material supply line L3 for supplying a raw material gas G11 and the reformed gas discharge line L4 for discharging the reformed gas G12, and which heat-exchanges the raw material gas G11 with the high-temperature reformed gas G12.

Description

Ammonia-hydrogen blended fuel production device, fuel supply system, and hydrogen production method

[0001] The present invention relates to an apparatus for producing ammonia-hydrogen mixed fuel, a fuel supply system, and a method for producing hydrogen.

[0002] Recently, ammonia utilization technology has been attracting attention as a way to achieve carbon neutrality. ３ ) to hydrogen (H ２ One example of a method for producing ethylenediaminetetraacetic acid is the ammonia decomposition method (see Patent Document 1).

[0003] JP 2022-144912 A JP 2023-83706 A

[0004] However, the proposed decomposition method for obtaining hydrogen from ammonia disclosed in Patent Document 1 requires the use of an ammonia decomposition device that supplies heat from outside the reactor. This ammonia decomposition device using external heating uses, for example, a burner to decompose ammonia (NH ３ ) and H2, which is the off-gas from the PSA (Pressure Swing Adsorption) unit. ２ / N ２ This method involves mixing ammonia gas with air (oxygen) and burning it, but the main fuel, ammonia, burns slower than other fuels such as methane, and there are challenges not only in ensuring reliable ignition and stabilizing combustion, but also in suppressing the production of nitrogen oxides.

[0005] By the way, the composition of the fuel (hydrogen (H ２ ) / ammonia (NH ３ The composition ratio) and flow rate may fluctuate depending on the requirements of downstream boilers, gas engines, industrial furnaces, etc. When such fluctuations are large (for example, a fluctuation from a turndown ratio of 1:1 (load factor of 100%) to a turndown ratio of 5:1 (20%)), it is difficult to respond quickly and with stable control when converting ammonia to hydrogen in the ammonia cracker.

[0006] Furthermore, in an ATR (Autothermal Reformer: hereinafter also referred to as "ATR") device that oxidatively decomposes ammonia, ammonia is oxidized by oxygen in an oxidative decomposition catalyst section. Self-heating due to oxidation causes oxidative decomposition and decomposition reactions of ammonia to progress in the ATR catalyst section, resulting in reforming into hydrogen. In the prior art technology described in Patent Document 2, ammonia itself, which is the raw material for ammonia reforming, is oxidized on the catalyst. For this reason, oxidation does not occur unless the catalyst is heated to 200°C or higher, so it is necessary to preheat the catalyst or raw material gas in advance.

[0007] In addition, the target of the present invention is, for example, 100 m per hour. ３ ~2,000m ３ Small- to medium-sized systems capable of generating hydrogen of this magnitude produce fuel for furnaces, gas engines, and boilers, which have large load fluctuations and frequent daily start and stop (DSS) cycles, and therefore must respond quickly to load fluctuations and DSS. Furthermore, because they are small- to medium-sized, the reactor size is small, and if a lot of heat is released from the reactor, the amount of ammonia oxidation must be increased to compensate for the heat required for the ammonia decomposition reaction, resulting in lower hydrogen yield and thermal efficiency. Furthermore, in order to package the system, the number of devices must be reduced and the reactor must be made compact.

[0008] Furthermore, when hydrogen is supplied to boilers, industrial furnaces, etc., these devices frequently undergo turndown, shutdown, and startup, making it desirable to have a self-contained system that allows for easy and rapid response. Conventional technology equipment requires heating to 200°C or higher, at which point the oxidative decomposition reaction can begin, during startup. This necessitates the installation of separate heating equipment, which complicates the equipment and makes rapid response difficult due to the long heating time. Furthermore, if the turndown ratio is less than 30% of the design flow rate (load rate < 30%, hereinafter also referred to as "low load rate less than 30%), the measurement and control accuracy of the gas flow rate in the system, the reaction efficiency of the ATR, and the heat transfer coefficient of the heat exchanger decrease, making it difficult to operate the equipment efficiently and stably.

[0009] In view of the above problems, the present invention provides an ammonia-hydrogen mixed fuel production device, a fuel supply system, and a hydrogen production method that can stably and quickly obtain hydrogen from ammonia even when the required composition ratio or amount of fuel changes.

[0010] (1) An ammonia-hydrogen mixed fuel production apparatus according to one aspect of the present invention is provided. ２ an oxygen supply unit that supplies ammonia (NH ３ a raw material supply unit that supplies ammonia (NH ３ ) to hydrogen (H ２ a reforming reactor that converts hydrogen and ammonia into a reformed gas; a gas component analyzer that is provided in a reformed gas discharge line that discharges the reformed gas from the reforming reactor and that measures the concentration of either hydrogen or ammonia, or both, in the reformed gas; and a plate-type heat exchanger that is provided at an intersection of a raw material supply line that supplies the raw material gas and the reformed gas discharge line that discharges the reformed gas and that exchanges heat between the raw material gas and the high-temperature reformed gas.

[0011] (2) Another aspect of the present invention is an ammonia-hydrogen mixed fuel manufacturing apparatus according to the invention (1), characterized in that it further comprises: a storage tank provided in the reformed gas discharge line for storing the reformed gas; and a recycle line branching off from the reformed gas discharge line at a branching point for recycling a portion of the reformed gas to the raw material supply line.

[0012] (3) Another aspect of the present invention is an apparatus for producing ammonia and hydrogen mixed fuel according to the invention (2), characterized in that oxygen from the oxygen supply unit is directly introduced into the reforming reactor.

[0013] (4) Another aspect of the ammonia-hydrogen mixed fuel manufacturing apparatus according to the present invention is the invention (1) or (2), characterized in that the oxygen supply unit is an oxygen separation device that separates oxygen from air to a desired concentration.

[0014] (5) Another aspect of the ammonia-hydrogen mixed fuel manufacturing apparatus according to the present invention is characterized in that, in the invention of (1) or (2), the oxygen supply unit is an air dryer that removes moisture from the supplied air.

[0015] (6) Another aspect of the present invention is an ammonia-hydrogen mixed fuel production device according to the invention (1) or (2), characterized in that the oxygen supply unit adds 3 to 20 volume % of oxygen to the amount of ammonia supplied.

[0016] (7) Another aspect of the ammonia-hydrogen mixed fuel manufacturing device according to the present invention is characterized in that, in the invention of (1) or (2), the amount of oxygen supplied from the oxygen supply unit is controlled based on the concentration of either or both of the hydrogen and the ammonia from the gas component analyzer.

[0017] (8) Another aspect of the present invention is an ammonia-hydrogen mixed fuel production device according to the invention (1), characterized in that the reforming reactor comprises: a housing having an inlet for introducing ammonia and a flammable gas other than ammonia and an outlet for discharging a generated gas; a first catalyst unit disposed inside the housing and having a first catalyst that generates heat by burning the flammable gas introduced from the inlet; and a second catalyst unit disposed between the first catalyst unit and the outlet, heated by the heat generated by the first catalyst unit, and having a second catalyst that generates hydrogen from ammonia.

[0018] (9) Another aspect of the present invention is an ammonia-hydrogen mixed fuel production device according to the invention (8), characterized in that the first catalyst section is disposed between the inlet and the second catalyst section.

[0019] (10) Another aspect of the ammonia-hydrogen mixed fuel manufacturing apparatus according to the present invention is the invention of (8), characterized in that the reactor includes a dispersion section between the first catalyst section and the second catalyst section, which disperses the gas flowing out from the first catalyst section toward the second catalyst section.

[0020] (11) Another aspect of the ammonia-hydrogen mixed fuel manufacturing device according to the present invention is the invention (8), characterized in that it comprises: an outlet flow path for discharging a reformed gas containing hydrogen from the outlet; a tank provided in the outlet flow path for storing the outflowed reformed gas containing hydrogen; and a return flow path branched from a branching portion of the outlet flow path for returning the reformed gas containing hydrogen to the inlet.

[0021] (12) Another aspect of the fuel supply system according to the present invention is characterized in that, using the ammonia-hydrogen mixed fuel production apparatus of (2), a part of the reformed gas is supplied to the reforming reactor side as recycled gas in the case of low load operation with a turndown ratio of less than 30%.

[0022] (13) Another aspect of the method for producing hydrogen according to the present invention is characterized in that it uses the ammonia-hydrogen mixed fuel production apparatus of (8), and includes: an introduction step of introducing an introduction gas containing ammonia and a combustible gas other than ammonia into a reactor; a combustion step of selectively combusting the combustible gas in the introduced introduction gas with a first catalyst; a second catalyst heating step of heating a second catalyst that generates hydrogen from ammonia with heat generated in the combustion step; and a reforming step of stopping the introduction of the combustible gas and generating hydrogen from ammonia using the second catalyst after the temperatures of the first catalyst and the second catalyst reach a predetermined temperature.

[0023] According to the present invention, even when the required flow rate of fuel changes (for example, when the load factor is low, such as less than 30%), hydrogen can be stably obtained from ammonia.

[0024] A plate-type heat exchanger is installed at the intersection of the inlet raw material gas introduction line and the reformed gas discharge line, and this plate-type heat exchanger is used to heat exchange the temperature of the inlet raw material gas introduced into the reforming reactor with the high-temperature reformed gas flowing out of the reforming reactor, thereby raising the introduction temperature of the raw material gas. This allows the fuel (reformed H) required to raise the temperature of the inlet raw material gas to be used. ２ ) consumption can be reduced.

[0025] Furthermore, when the turndown ratio in the system is below 30%, a portion of the reformed gas can be recycled to the inlet of the reforming reactor as recycled gas to maintain the flow rates in the heat exchange process and reaction process at a certain level (>30%), thereby preventing a decrease in the controllability of the system, measurement accuracy of gas flow rates, etc., and thermal efficiency of the system.

[0026] As described above, the present invention can provide a reactor and a method for producing hydrogen that are highly thermally efficient and can quickly respond to load fluctuations and start-up / shutdown on the demand side.

[0027] 1 is a schematic diagram of an apparatus for producing ammonia and hydrogen mixed fuel according to a first embodiment of the present invention. FIG. 2 is a schematic diagram of an apparatus for producing ammonia and hydrogen mixed fuel according to a modified example of the first embodiment of the present invention. FIG. 3 is a schematic diagram of an apparatus for producing ammonia and hydrogen mixed fuel according to a second embodiment of the present invention. FIG. 4 is a schematic diagram of an apparatus for producing ammonia and hydrogen mixed fuel according to a second embodiment of the present invention. FIG. 5 is a schematic diagram of a testing process of an apparatus for producing ammonia and hydrogen mixed fuel according to a second embodiment of the present invention. FIG. 6 is a schematic diagram of a testing process of an apparatus for producing ammonia and hydrogen mixed fuel according to a third embodiment of the present invention. FIG. 7 is a schematic diagram of a process of an apparatus for producing ammonia and hydrogen mixed fuel according to a third embodiment of the present invention. FIG. 8 is a cross-sectional view showing the internal structure of a reactor according to a fifth embodiment of the present invention. FIG. 9 is a structural view of a distribution section to be installed inside a reactor according to the fifth embodiment of the present invention. FIG. 10 is a structural view of another distribution section to be installed inside a reactor according to the fifth embodiment of the present invention. FIG. 11 is a cross-sectional view showing the internal structure of another reactor according to the fifth embodiment of the present invention. FIG. 12 is a perspective view of a first catalyst section, illustrating the size of the first catalyst section. FIG. 13 is a perspective view of a second catalyst section, illustrating the size of the second catalyst section. FIG. 14 is a view illustrating a temperature gradient between the second catalyst section and a housing. 14 is a diagram showing a structure for starting up a reactor using at least a portion of hydrogen produced in a second catalytic section. FIG. 15 is a graph showing the temperature distribution inside a reactor when combustible gas is combusted in a catalytic section under specific reaction conditions in the fifth embodiment. FIG. 16 is a graph showing the temperature distribution inside a reactor when ammonia reforming is performed in a reactor without adding combustible gas. FIG. 17 is a flowchart showing a method for producing hydrogen. FIG. 18 is a cross-sectional view showing the internal structure of a reactor of a sixth embodiment according to the present invention. FIG. 19 is a cross-sectional view showing the internal structure of a reactor of a seventh embodiment according to the present invention. FIG. 19 is a cross-sectional view taken along line A-A of FIG. 14, showing a cross-sectional view of the second catalytic section installed in the second stage.

[0028] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the embodiments of this specification, the same components are designated by the same reference numerals throughout.

[0029] 1A is a schematic diagram of an ammonia-hydrogen mixed fuel production apparatus according to a first embodiment of the present invention. As shown in FIG. 1A, an ammonia-hydrogen mixed fuel production apparatus 1010A-1 of this embodiment produces an ammonia-hydrogen mixed fuel having a desired concentration of oxygen (O ２ ) and a raw material (ammonia (NH ３ a raw material supply unit 1014 that supplies ammonia (NH ３ ) to hydrogen (H ２ ) to produce reformed gas G １２ and a reformed gas G from the reforming reactor 1015. １２ and a gas component analyzer 1017 for analyzing the concentration of either or both of hydrogen and ammonia in the gas.

[0030] The raw material supply unit 1014 supplies ammonia (NH ３ ) is supplied from the raw material supply unit 1014 to the reforming reactor 1015 via an ammonia supply line L1. ３ The oxygen supply unit 1013 supplies oxygen (O ２ ) is supplied from the oxygen supply unit 1013 to the reforming reactor 1015 through an oxygen supply line L ２ via oxygen (O ２ ) is supplied. ２ ) and ammonia (NH ３ ) merges at confluence A and enters line L ３ The inlet raw material gas G １１ The resulting mixture is introduced into the reforming reactor 1015 as the fuel.

[0031] In addition, the reformed gas G discharged from the reforming reactor 1015 １２ is the reformed gas discharge line L ４ Through the product (fuel (H ２ )) 1018 is used on the external demand side X. Here, in FIG. 1, reference numeral 1020 denotes a reformed gas discharge line L ４10 shows a cooler interposed between the reformed gas and the product gas, 1021 a moisture separator, 1022 a compressor, and 1023 a storage tank (hereinafter also referred to as a "product tank") for storing the reformed gas.

[0032] The oxygen supply unit 1013 for supplying oxygen may be, for example, a cryogenic separation device, a pressure swing adsorption (PSA) device, a membrane separation device, or the like, which converts oxygen (O ２ ) can be mentioned, but the present invention is not limited to these.

[0033] Alternatively, an air dryer, for example, that removes moisture from the supplied air may be used as the oxygen supply unit 1013 instead of the pressure swing adsorption (PSA) unit. The air dryer may use an adsorption method or a cooling method.

[0034] The air dryer removes moisture from the air and prevents a catalyst such as platinum (Pt) used in the reforming reactor 1015 from being inhibited by water adsorption.

[0035] Here, the adsorption method is a method of removing moisture using, for example, zeolite. The cooling method makes it possible to remove moisture by adjusting the saturated vapor pressure corresponding to the cooling temperature (for example, by cooling to 20°C or less). The cooling temperature is preferably 20°C or less, and more preferably -20°C or less.

[0036] According to this embodiment, when oxygen is supplied from air and moisture in the air is removed by an air dryer, for example, a platinum (Pt) catalyst used in the reforming reactor 1015 is prevented from being poisoned by moisture.

[0037] In addition, the reformed gas discharge line L ４ The fuel 1018 is ammonia (NH ３ ) and hydrogen (H ２ ) and the composition ratio (NH ３ / H ２ ) or one of the gas compositions, and a gas component analyzer 1017 is installed to measure the reformed gas G １２ The gas composition is measured.

[0038] The gas component analyzer 1017 may be, for example, a hydrogen concentration meter that analyzes hydrogen, an ammonia analyzer that analyzes ammonia, or an ammonia / hydrogen composition analyzer that simultaneously measures the composition of hydrogen and ammonia, but the present invention is not limited to these. Here, the main analyzer used as the gas component analyzer 1017 is, for example, a gas chromatograph (H ２ , N.H. ３ Gas analysis), thermal conductivity gas analyzer (H ２ gas analysis), infrared absorption spectrophotometer (NH ３ However, the present invention is not limited to such a method.

[0039] In this way, the raw material ammonia (NH ３ ) is reformed in the reforming reactor 1015 to produce a reformed gas G １２ The composition ratio (NH ３ / H ２ ) is measured by the gas component analyzer 1017, whereby the fuel composition required on the downstream demand side X is measured intermittently or continuously.

[0040] This measurement value is sent online as a measurement signal to a separate control device 1031, and the control valve V １１ , V １２ For example, the control device 1031 may perform control such that the difference between the fuel composition requested by the demand unit X and the measured fuel composition is corrected.

[0041] In this embodiment, ammonia (NH ３ ) with respect to the supply amount of oxygen (O ２ It is preferable to add hydrogen (H ). This is because if it is 3% by volume or less, the hydrogen reforming rate will decrease, which is not preferable. If it is added in excess of 20% by volume, oxidation will proceed beyond the amount of heat required for ammonia decomposition, resulting in the loss of hydrogen (H ２ ) This is because it leads to a decrease in yield and thermal efficiency, which is undesirable.

[0042] Here, in order to produce hydrogen from ammonia, as shown in the following formula (1), in the case of external heating, this endothermic heat is converted into ammonia (NH ３ ) and hydrogen (H ２ ) is combusted and supplied to the reforming reactor 1015. ３ →0.5N ２ +1.5H ２ Endothermic ΔH = +45.9 kJ / mol (1) However, ammonia (NH ３ ) As the decomposition reaction progresses, the reaction temperature drops and eventually stops unless heat is supplied.

[0043] In the present invention, when 12 to 16% by volume of oxygen is added, the heat generated by the two oxidation reactions of the following formulas (2) and (3) can cover the endothermic heat of the ammonia decomposition reaction, thereby achieving a high decomposition rate. ３ +0.25O ２ →H ２ +0.5N ２ +0.5H ２ O Heat generation △H = -75 kJ / mol ... (2) NH ３ +0.75O ２ →0.5N ２ +1.5H ２ O Heat generation △H = -317kJ / mol...(3)

[0044] As described above, the conversion rate increases as the reaction temperature (the amount of oxygen added) and the amount of catalyst increase. However, if the amount of oxygen added is too large, ammonia and the generated hydrogen are oxidized (consumed) by oxygen, so there is an upper limit to the conversion rate of ammonia (NH ３ On the other hand, if the amount is too small, the increase in reaction temperature due to heat generation is small, and the reaction (decomposition rate) does not proceed below the temperature due to the ammonia decomposition reaction. ３ ) is supplied, for example, at 3% by volume.

[0045] As the reforming catalyst 1015A of the reforming reactor 1015, it is preferable to use a known NH3-ATR catalyst and a known NH3 decomposition catalyst, either singly or in combination. ３-ATR catalyst" and "NH ３ The ratio of "NH ３ The catalyst temperature of the ATR catalyst is 150 to 750°C, and the ３ The catalyst temperature of the decomposition catalyst is preferably 400 to 750°C.

[0046] In a combination of catalysts optimal for the ammonia decomposition reaction (formula 1) and the ammonia oxidation reaction (formulas (2) + (3)) described above, the oxidation reaction has a fast reaction rate and therefore proceeds 100% in 20 to 30% of the entire catalyst layer, whereas the decomposition reaction has a slower reaction rate than the oxidation reaction and the reaction temperature drops as the reaction progresses, requiring a large amount of catalyst.

[0047] Therefore, it is preferable to divide the optimal catalyst for each reaction in the amount required for the above reactions in a ratio of 1:2 to 1:6. Also, some catalysts are suitable for both reactions, and in such cases, one type of catalyst (1:0) may be used.

[0048] The ATR catalyst is preferably a catalyst made of one or more of ruthenium (Ru), platinum (Pt), nickel (Ni), cobalt (Co), iron (Fe), manganese (Mn), and molybdenum (Mo), but the present invention is not limited to this.

[0049] The NH3 decomposition catalyst is preferably a catalyst made of one or more of ruthenium (Ru), nickel (Ni), cobalt (Co), iron (Fe), manganese (Mn), and molybdenum (Mo), but the present invention is not limited to this.

[0050] The reaction temperature in the reforming reactor 1015 is, for example, 150 to 850°C, preferably 300 to 700°C, and the pressure is 0.03 to 0.9 MPaG, preferably 0.07 to 0.7 MPaG. The reason for specifying the temperature and pressure within the predetermined ranges is to allow the reforming reaction to proceed efficiently.

[0051] Ammonia (NH ３The oxidation reaction of ) depends on the performance of the catalyst, but for example, starts at 150 to 200°C, and the reaction rate increases with the reaction temperature. If the temperature inside the reforming reactor 1015 becomes, for example, 700°C or higher, the activity of the catalyst may decrease (for example, if the aggregation of active metals due to heat is promoted, reducing the active surface area), so the reaction temperature is preferably in the range of 150 to 750°C.

[0052] Furthermore, the lower the pressure, the more advantageous it is for hydrogen production in terms of chemical equilibrium, but a pressure of 0.03 to 0.9 MPaG is preferable when taking into consideration the supply pressure to downstream combustion equipment and pressure loss due to catalyst layers, etc. Note that when a honeycomb catalyst (which has low pressure loss) is used as the catalyst or depending on the downstream equipment, a low pressure such as 0.07 MPaG may be more advantageous for the reaction.

[0053] This ammonia-hydrogen mixed fuel production device is used to supply the ammonia (NH ３ ) as fuel, and the demand from the demand side (NH ３ / H ２ It is possible to construct a fuel supply system according to the fuel composition and flow rate.

[0054] Here, the gas component analyzer 17 can measure either or both of the hydrogen concentration and the ammonia concentration, but in this embodiment, hydrogen measurement will be described as an example.

[0055] That is, the demand for fuel 1018 from the demand unit X side, such as an engine, boiler, or heating furnace, which is arranged downstream (NH ３ / H ２ The reformed gas G is analyzed by a gas component analyzer (hydrogen concentration meter) 1017 installed downstream of the reforming reactor 15 according to the composition and flow rate of the reformed gas G. １２ Hydrogen (H ２ ) concentration is measured, and the required H ２ Concentration (NH ３ The amount of oxygen supplied from the oxygen separator 1013 is controlled so as to satisfy the above condition (decomposition rate).

[0056] Ammonia (NH ３ The decomposition rate of raw ammonia (NH ３ ) to oxygen (O２ ) is added. ３ ) 0 to 16 vol% oxygen (O ２ ) can be added to control the content in the range of 0 to 100 vol%. ３ +0.25O ２ →H ２ +0.5N ２ +0.5H ２ O ... (5) <Exothermic reaction> NH ３ +0.75O ２ →0.5N ２ +1.5H ２ O... (6) <Exothermic reaction>

[0057] Ammonia (NH ３ ) is used to generate heat from the oxidation reaction of NH ３ This promotes the decomposition reaction. As a result, ammonia is used as a raw material. The product ammonia (NH ３ ) / Hydrogen (H ２ ) mixed gas supply amount and its hydrogen (H ２ ) concentration can be freely controlled.

[0058] As described above, according to the present invention, ammonia (NH ３ ) to hydrogen (H ２ ) to produce hydrogen (H ２ ) production, for example, to supply fuel to engines, boilers, heating furnaces, etc., and depending on the purpose and demand, ammonia (NH ３ ) / Hydrogen (H ２ ) composition ratio (composition ratio combustable by, for example, a combustion appliance on the fuel demand section X side) can be adjusted according to demand.

[0059] Here, conventionally, O ２ / NH ３ Increase the ratio and H ２ and NH ３ The reforming reactor 1015 is internally heated by catalytic combustion of a part of the reformed gas G. １２ H inside ２is consumed, resulting in increased self-consumption losses.

[0060] In this embodiment, such a reformed gas G １２ H inside ２ In order to minimize the self-consumption losses of the inlet feed gas G introduced into the reforming reactor 1015 using a highly efficient plate-type heat exchanger 1030. １１ The gas temperature of the reformed gas G １２ The inlet raw material gas G １１ The introduction temperature of the

[0061] The plate-type heat exchanger 1030 is installed at the inlet raw material gas G １１ Introduction line L ３ and the reformed gas discharge line L ４ The inlet raw material gas G １１ The reformed gas G is a high-temperature gas. １２ By exchanging heat with the refrigerant, the temperature is raised to, for example, 450° C. or higher.

[0062] By such a temperature raising operation, the inlet raw material gas G introduced into the reforming reactor 1015 １１ As a result, the gas temperature of the inlet raw material gas G is increased compared to when the plate-type heat exchanger 1030 is not installed or when other types of heat exchangers (for example, shell-and-tube type heat exchangers) are installed. １１ The fuel required to raise the temperature (H ２ ) consumption losses can be reduced.

[0063] In this way, the inlet source gas G １１ Introduction line L ３ and the reformed gas discharge line and L ４ A plate-type heat exchanger 1030 is installed at the intersection of the inlet raw material gas G introduced into the reforming reactor 1015 using this highly efficient plate-type heat exchanger 1030. １１ The temperature of the high-temperature reformed gas G flowing out from the reforming reactor 1015 is １２ This increases the temperature of the inlet raw material gas G １１ The fuel required to raise the temperature (reformed H２ ) consumption can be reduced, and the reformed gas G １２ H inside ２ In this way, the self-consumption loss of the reformed gas G １２ The H concentration in the gas was measured by an in-line gas component analyzer (hydrogen concentration meter) 1017. ２ The concentration is adjusted to meet the product gas specifications. ２ / NH ３ In addition to improving the heat transfer coefficient, the plate-type heat exchanger 1030 is compact, lightweight, and can be freely installed either horizontally or vertically, making it suitable for small installation locations for small to medium-sized businesses.

[0064] In this embodiment, the inlet source gas G １１ Reactor inlet temperature (T １ ) at the outlet of the reforming reactor 1015 so that the temperature of the reformed gas G １２ The gas temperature (T ２ The plate-type heat exchanger 1030 exchanges heat so that the temperature of the reformed gas is 550° C. or higher (preferably 580° C.).

[0065] The heat exchange in the plate-type heat exchanger 1030 is performed by exchanging the reformed gas G at a high temperature of 550° C. or more. １２ The inlet temperature (T ｉｎ ) and low temperature gas (inlet raw material gas G １１ ) outlet temperature after heat exchange (T ｏｕｔ It is preferable to carry out heat exchange so that the temperature difference (Δt) between the first and second electrodes is, for example, 10 to 150°C, preferably 50 to 20°C.

[0066] This is because when the temperature difference (Δt) exceeds 150° C., the inlet raw material gas G １１ To heat ２ / NH ３ This is because the ratio increases, resulting in a decrease in thermal efficiency, which is undesirable. Also, if the temperature difference (Δt) is less than 10°C, the heat transfer area of ​​the plate-type heat exchanger 1030 needs to be increased, which increases the cost and pressure loss of the plate-type heat exchanger 1030, both of which are undesirable.

[0067] The plate-type heat exchanger 1030 is preferably a gas-gas plate-type heat exchanger having high heat resistance of at least 500°C or more, more preferably 600°C or more.

[0068] Examples of the plate heat exchanger 1030 include a plate heat exchanger manufactured by Chandon Wintec Technology and a plate heat exchanger manufactured by Bosal Energy, but the present invention is not limited to these.

[0069] (Test Examples 1 and 2, Comparative Example 1) Test examples and comparative examples according to the first embodiment will be described below, but the present invention is not limited to these. ３ and a raw material gas G consisting of air. １１ the reformed gas G １２ After being heated by heat exchange with the NH ３ The oxidation and decomposition reactions were carried out.

[0070] (Comparative Example 1) As a comparative example, inlet raw material gas G １１ and reformed gas G １２ The heat exchanger used was a shell and tube type heat exchanger. １２ and inlet raw material gas G １１ The raw gas G is then heat exchanged using a shell and tube heat exchanger. １１ The mixture was heated from 30° C. to 400° C. and supplied to the reforming reactor 1015 .

[0071] The ammonia decomposition rate was 97%. The ammonia and air supply rates were 300 Nm ３ / hr, 204 Nm ３ / hr, and O ２ / NH ３ The molar ratio was 0.143. The reforming catalyst 1015A was a Co-based catalyst 40 L packed into the reforming reactor 1015, and the inlet pressure of the reforming reactor 1030 was 0.13 MPaG. The thermal efficiency at this time was 78.9%. Here, the thermal efficiency is defined as "thermal efficiency = (energy of reformed gas / energy of raw material) x 100".

[0072] (Test Example 1) In Test Example 1, the inlet raw material gas G １１ and reformed gas G １２ A plate-type heat exchanger 1030 was used for heat exchange with the reformed gas G １２ and inlet raw material gas G １１ The raw material gas was heated from 30°C to 520°C by heat exchange with the air, and then supplied to the reforming reactor 1015. The ammonia decomposition rate was 97%. The ammonia and air supply rates were 300 Nm ３ / hr, 177 Nm ３ / hr, and O ２ / NH ３ The molar ratio was 0.124. The reforming catalyst 1015A was packed into the reforming reactor 1015 together with 40 L of the Co-based catalyst, and the inlet pressure of the reactor was 0.13 MPaG. The thermal efficiency at this time was 81.2%.

[0073] (Test Example 2) In Test Example 2, the inlet raw material gas G １１ and reformed gas G １２ A plate-type heat exchanger 1030 is used as the heat exchanger for the reformed gas G １２ and inlet raw material gas G １１ The raw material gas was heated from 30°C to 580°C (60°C higher than in Test Example 1) by heat exchange with the air, and then supplied to the reforming reactor 1015. The ammonia decomposition rate at this time was 97%. The supply rates of ammonia and air were each 300 Nm ３ / hr, 164.2 Nm ３ / hr, and O ２ / NH ３ The molar ratio was 0.124. The reforming catalyst 1015A was packed into the reforming reactor 1015 together with 40 L of the Co-based catalyst, and the inlet pressure of the reactor was 0.13 MPaG. The thermal efficiency at this time was 82.4%.

[0074] From the results of Comparative Example 1 and Test Examples 1 and 2, it can be seen that by using the plate-type heat exchanger 1030, the reformed gas G １２ and inlet raw material gas G １１By exchanging heat with high efficiency, it was confirmed that thermal efficiency was improved.

[0075] [Modification of the First Embodiment] Fig. 1B is a schematic diagram of an ammonia-hydrogen mixed fuel production apparatus according to a modification of the first embodiment. Note that the same components as those in the first embodiment are denoted by the same reference numerals, and the description thereof will be omitted. As shown in Fig. 1B, the ammonia-hydrogen mixed fuel production apparatus 1010A-2 of this embodiment is the same as that of the ammonia-hydrogen mixed fuel production apparatus 1010A-1 of the first embodiment, except that hydrogen (H ２ ) into the hydrogen introduction line L ９ As a reforming catalyst 1015A in the reforming reactor 1015, a first catalyst section 13 is arranged on the inlet side, and a second catalyst 21 is arranged on the downstream side of the first catalyst section 13 in the gas flow direction.

[0076] The first catalyst section 13 is a platinum catalyst such as platinum for burning hydrogen, and the second catalyst is either a known NH3 ATR catalyst or a known NH3 decomposition catalyst, or both. ９ This is for introducing hydrogen into the first catalyst 13 at the initial start-up of the system, and the introduction of hydrogen causes catalytic combustion, thereby raising the internal temperature within the reforming reactor 1015 (details will be described later).

[0077] In addition, reformed gas G is used as a hydrogen source other than when the system is started up. １２ When the reformed gas G from the product tank 1023 can be used, １２ reformed gas introduction line L １０ Here, the reformed gas is introduced through the reformed gas introduction line L １０ A moisture removal section 1026 for removing moisture contained in the reformed gas is provided in the hydrogen introduction line L ９ , reformed gas line L １０ An on-off valve V for controlling the introduction of hydrogen or reformed gas is provided. ４ , V ５ are provided respectively.

[0078] At the beginning of system startup, the on-off valve V ４is opened and hydrogen is introduced from a hydrogen supply unit (for example, a hydrogen cylinder) 1019. By introducing this hydrogen, the inlet raw material gas G １１ There is hydrogen (H ２ ) added to the inlet source gas G １１ Then, hydrogen (H ２ ) added to the inlet source gas G １１ is introduced into the housing 1 from the inlet 1a at room temperature (for example, 30° C.) and reaches the first catalyst section 13. By using platinum as a catalyst in this first catalyst section 13, hydrogen combustion begins, and as a result, the inlet raw material gas G １１ The gas temperature is increased to heat the second catalyst section 21 .

[0079] This is because, since the entire system is at room temperature (low temperature) during system startup, no external heating is required using a separate heat source, but the second catalyst section 21 is heated by catalytic heating within the reforming reactor 1015 to promote the ammonia reforming reaction (details will be described later). ４ to stop the supply of hydrogen from the hydrogen supply unit (for example, hydrogen cylinder) 1019.

[0080] In this way, at the start of system operation, in addition to the hydrogen supply from the hydrogen supply unit (hydrogen cylinder) 1019, the reformed gas (product hydrogen) G from the product tank 1023 is supplied. １２ By using this, it is possible to reduce the consumption of the hydrogen supply unit (hydrogen cylinder) 1019.

[0081] 2A and 2B are schematic diagrams of an ammonia-hydrogen mixed fuel production apparatus according to a second embodiment. The same components as those in the first embodiment are denoted by the same reference numerals, and the description thereof will be omitted. As shown in FIGS. 2A and 2B, an ammonia-hydrogen mixed fuel production apparatus 1010B (1010B-1, 1010B-2) according to this embodiment further includes a reformed gas discharge line and an L ４ and the reformed gas G １２ a product tank 1023 which is a reformed gas storage tank for storing the reformed gas, and a reformed gas discharge line L４ At branch point B, the raw material supply line L ３ Reformed gas G １２ Part of the recycled gas G １３ Recycling Line L ６ This recycling line L ６ The connection point is the introduction line L ３ The gas junction C is located on the inlet side of the plate-type heat exchanger 1030. ６ The raw material gas G introduced into the reforming reactor 1015 is １１ Reformed gas G １２ Some of it is recycled and mixed.

[0082] In this embodiment, in the ammonia-hydrogen mixed fuel production apparatus 1010B-1, as shown in FIG. 2A, in the case of low load operation (less than 30% but 15% or more) where the load factor is less than 30%, the inlet line L of the reforming reactor 1015 ３ Reformed gas G １２ Part of the recycled gas G １３ The raw gas G １１ Reformed gas G １２ NH that can respond to low load fluctuations by supplementing ３ We offer reforming systems.

[0083] In the case of normal operation (load factor: 100% to 30%), as in the ammonia-hydrogen mixed fuel production apparatus 1010B-2 shown in FIG. 2B, the on-off valve V １ is set to "closed", and the recycle line is supplied with the recycle gas G １３ The operation will be such that no power is supplied.

[0084] In this way, the reformed gas G １２ Part of the reformed gas recycling G １３ By returning the gas to the reforming reactor 1015 side as a gas, the flow rate of the gas flowing through the reforming reactor 1015 system is maintained at 30% or more of the design flow rate.

[0085] Here, H ２ and N ２ Reformed gas G consisting of １２ Recycle gas G１３ However, if the gas is recycled as a fuel, energy is consumed to heat it up to the reaction temperature, resulting in a decrease in thermal efficiency.

[0086] In the case of the reforming reactor 1015, ２ / NH ３ Increase the ratio and H ２ and NH ３ As a result, H ２ In order to solve this problem, in this embodiment, as in the first embodiment, a highly efficient plate-type heat exchanger 1030 is used to change the temperature of the inlet raw material gas introduced into the reforming reactor 1015 to that of the high-temperature reformed gas G flowing out of the reforming reactor 1015. １２ This increases the temperature of the raw material gas G １１ The fuel required to raise the temperature (H ２ ) consumption is being significantly reduced.

[0087] In the present invention, the "design flow rate" refers to the amount of NH ３ and oxygen (air), and 100% corresponds to the maximum flow rate. Therefore, "30%" corresponds to 30% of this design (maximum) flow rate on a volume (Vol) basis.

[0088] Here, the reformed gas G with a low turndown ratio １２ Recycle gas G １３ When the recycled gas is recycled to the reforming reactor 1015 as the recycled gas G １３ H inside ２ and raw material air (oxygen (O ２ )) may be mixed and fall within the hydrogen explosive concentration range.

[0089] Therefore, in this embodiment, when oxygen is supplied to the reforming reactor 1015, oxygen (O ２ ) oxygen bypass line L ７ The oxygen bypass line L ７In this embodiment, oxygen is introduced directly into the reforming reactor 1015 via an oxygen burner. ３ , oxygen bypass line L ７ ) to obtain NH ３ and oxygen are introduced by separate burners (not shown).

[0090] In contrast, separate burners are not used, and separate lines (inlet lines L ３ , oxygen bypass line L ７ ) and two types of gases (NH ３ , O ２ ) may be installed so that two types of gases can be introduced into the reforming reactor 1015.

[0091] Next, the recycling line L ６ 3A and 3B, the operation process for low load turndown using the on-off valve V is described. <Normal demand operation (turndown ratio: 100% to 30%)> Normal operation (turndown ratio: 100% to 30%) is performed by turning on / off the on-off valve V as shown in FIG. １ is closed and the system is operated in the same manner as in the configuration of the first embodiment (FIG. 1).

[0092] <Low-load operation with a turndown ratio of less than 30% (turndown ratio: 15% to 30%)> [Step 0] Normally, the demand side X operates in a turndown request mode (turndown operation) with a turndown ratio of 30% to 100% (see FIG. 3A).

[0093] [Step 1] In step 1, a request (low load operation with a turndown ratio of less than 30% (turndown ratio: less than 30%; in this example, turndown ratio: 20%)) is input to the control unit 1031 from the demand unit X side.

[0094] [Step 2] In step 2, the open / close valve V １ is changed from closed to open (see FIG. 3B).

[0095] [Step 3] In step 3, the reformed gas G １2Part of the recycling line L ６ Recycle gas G １３ (recycling begins). Reformed gas G １２ Part of the recycled gas G １３ By returning the gas to the reforming reactor 1015 side as a gas, the flow rate of the gas flowing through the reforming reactor 1015 system is maintained at 30% or more of the design flow rate.

[0096] [Step 4] In step 4, a change in demand (turndown ratio: from 20% to 80%) is input to the control unit 1031 from the demand unit X side.

[0097] [Step 5] In step 5, the opening and closing valve V １ is switched from open to closed, the recycle is stopped, and normal operation is resumed (see FIG. 3A).

[0098] In this way, in the case of low load operation where the turndown ratio in the system is less than 30% (turndown ratio: less than 30%; in this example, the turndown ratio: 20%), the reformed gas G １２ Part of the recycled gas G １３ By recycling the gas as a gas, the flow rate of the heat exchange process and reaction process can be maintained at a certain level (>30%). This makes it possible to prevent a decrease in the controllability of the system, measurement accuracy of gas flow rate, etc., and thermal efficiency of the system.

[0099] (Test Example 3) In Test Example 1, the system configuration shown in FIG. 1 was used, and ammonia (NH ３ ) and oxygen (O ２ ) and the supply amount is 60 Nm ３ / hr, 35.4 Nm ３ / hr and a turndown ratio of 20% (low load operation with a turndown ratio of less than 30%), the operation was the same as in Test Example 1. The gas flow velocity in the hot side flow path of the plate heat exchanger 1030 was reduced from 10.5 m / s in Test Example 1 to 2.1 m / s, and the gas flow velocity in the reforming reactor 1015 was reduced from 6.4 m / s to 1.9 m / s.

[0100] As a result, the overall heat transfer coefficient of the plate heat exchanger 1030 is 40 Wm ２ / K to 12Wm ２ / K.

[0101] Due to the decrease in the overall heat transfer coefficient and the uneven flow of gas, the inlet raw gas G １１ Reactor inlet temperature (heat exchanger outlet temperature) T １１ The increase in temperature was limited to 180°C.

[0102] To compensate for this temperature drop, air (O ２ ) supply amount is 48.8 Nm ３ / hr, and O ２ / NH ３ The ratio was set to 0.171. The ammonia decomposition rate was 92%. The thermal efficiency was 70.3%.

[0103] (Test Example 4) In Test Example 3, the system configuration shown in FIG. 2A was used, and ammonia (NH ３ ) and air (O ２ ) and the supply amount was 60 Nm ３ / hr, 35.4 Nm ３ / hr and the turndown ratio was 20%.

[0104] Recycling Line L ６ Therefore, 90Nm ３ / hr recycled gas G １３ and ammonia (NH ３ ) and reformed gas mixed gas flow rate is 150 Nm ３ The procedure was the same as in Test Example 3, except that the time was changed to / hr.

[0105] Reformed gas is recycled gas G １３ By recycling the feedstock as a fuel, the turndown ratio was increased to 50%, and the inlet temperature of the feedstock reforming reactor 1015 was accordingly increased to 400°C. To compensate for this temperature drop, oxygen (O ２ ) is 50.3 Nm ３ / hr.

[0106] Here, the air passes through an oxygen bypass line L that bypasses the plate-type heat exchanger 1030. ７ The NH4 was bypassed by the NH4 and directly supplied to the reforming reactor 1015 via a burner. ３The decomposition rate was 96%, and the thermal efficiency was 73.6%.

[0107] Test Examples 2 and 3 show that a part of the reformed gas is used as the bypass gas G １３ By recycling it as fuel, the thermal efficiency improved from 70.3% to 73.6%.

[0108] Comparing Test Example 3 and Test Example 4, in Test Example 3, the reformed gas was not recycled, so the thermal efficiency dropped to 70.3%, but by recycling the reformed gas as in Test Example 4, the thermal efficiency increased to 73.6%, an improvement of approximately 3%.

[0109] As a result, even during low-load operation where the turndown ratio is less than 30%, which is the lower limit of the design flow rate, the measurement accuracy and control accuracy of the gas flow rate in the system, the reaction efficiency of the ATR, and the heat transfer coefficient of the heat exchanger are not reduced, and the device can be operated efficiently and stably.

[0110] 4A and 4B are schematic diagrams of an apparatus for producing ammonia-hydrogen mixed fuel. The same components as those in the first and second embodiments are denoted by the same reference numerals, and the description thereof will be omitted. As shown in FIGS. 4A and 4B, an apparatus for producing ammonia-hydrogen mixed fuel 1010C (1010C-1, 1010C-2) of this embodiment has a reformed gas discharge line L between a compressor 1022 and a product tank 1023. ４ A switching valve (or three-way valve) 1024 is installed in the １２ When the gas composition is below a predetermined value, a buffer tank 1025 is provided to temporarily store the gas.

[0111] Then, based on the measurement by the gas component analyzer 1017, the changeover valve (or three-way valve) 1024 is switched to change the reformed gas G １２ The storage location can be changed as needed.

[0112] In the ammonia-hydrogen mixed fuel production apparatus 1010C-1 of this embodiment, as shown in FIG. 4A, when there is a demand operation (turndown operation) of 30% to 100% on the demand side X, the on-off valve V ３is set to "closed" and the reformed gas G １２ is not sent to the demand side X, and the reformed gas G １２ Hydrogen (H ２ ) concentration is required H ２ If the concentration satisfies the requirement, the product gas 1018 is stored in the product tank 1023. ２ ) 1018 is provided to the demand section X side.

[0113] In addition, when the demand side X requests low load operation (15% to 30%) with a turndown ratio of less than 30%, the reformed gas G １２ In order to recycle and reform a part of the ３ is set to "open", and the recycled gas G １３ Buffer gas line L that supplies ８ via the recycling line L ６ Recycled Gas G １３ Buffer gas line L ８ The buffer gas G １３ When supplying the product gas 1018, the on-off valve V ３ has been installed.

[0114] In this embodiment, the reformed gas G １２ In addition, during low load operation (15% to 30%) where the turndown ratio is less than 30%, the recycled gas can be supplied from the buffer tank 1025 as shown in FIG. 4B, thereby enabling a rapid response to the demand on the demand side X.

[0115] [Fifth Embodiment] Next, specific variations of the reforming reactors in the first to fourth embodiments will be described. Fig. 5 is a cross-sectional view showing the internal structure of a reactor 10 according to the fifth embodiment. The reactor 10A is a reactor that performs autothermal reforming (ATR) of ammonia. The ATR reactor (hereinafter also referred to as "reactor") 10 includes a first catalyst section 13 and a second catalyst section 21.

[0116] The first catalyst section 13 is connected to the inlet raw material gas G１１ The second catalytic section 21 is for catalytic combustion of ammonia using oxygen (exothermic reaction). In the reactor 10A, heat is generated by combustion of a flammable gas such as hydrogen in the first catalytic section 13. The generated heat is then released into the gas G １１Ｈ However, the ammonia flows into the second catalyst section 21, heating the second catalyst section 21. In the second catalyst section 21, the reaction heat of the ammonia decomposition reaction (endothermic reaction) is supplied by utilizing the heat generated by the partial oxidation reaction (exothermic reaction) of ammonia using oxygen. Therefore, the reactor 10A is thermally self-sustaining without the need for an external heat source (heating furnace, etc.), and can decompose ammonia (produce hydrogen) with an efficient and simple reactor configuration.

[0117] The reactor 10A has a first catalyst section 13 as a configuration capable of generating a reaction for heating the second catalyst section 21 used for ammonia reforming before the ammonia reforming. This reaction proceeds at the inlet section of the reactor 10A, and there is no need to provide a heat source outside the reactor 10A for supplying heat to the inside of the reactor 10A. With this configuration, the reactor 10A can be started up quickly when ammonia reforming is performed, and the time required for starting reforming and changing the load can be shortened.

[0118] The reactor 10A comprises a housing 1, which has an inlet 2 and an outlet 3. The housing 1 has a cylindrical shape that is circular when viewed from above, but may also have a rectangular shape when viewed from above. The cross-sectional areas of the inlet 2 and the flow path 11 formed inside are different, and the inlet 2 and the outlet 3 are narrower than the internal flow path 11 (a portion with a locally expanded cross-sectional area). The flow path 11 is formed between the inlet 2 and the outlet 3. The flow path 11, as will be described in detail later, is provided with a gas G (gas G １１ , G １１Ｈ , G １２ ) will be played.

[0119] The flow path 11 is defined by a heat insulating material 12 arranged along the inner wall of the housing 1. The housing 1 is not completely cylindrical, but has a shape that locally narrows inside near the inlet 2. Furthermore, near the outlet 3, the housing 1 has a shape that narrows toward the outlet 3. Of the flow path 11 formed by being surrounded by the heat insulating material 12, the shape between the inlet 2 and the upper end of the locally widened portion formed below the inlet 2 has a cylindrical shape (for example, a perfect circle when viewed from above). However, the shape between the inlet 2 and the upper end of the locally widened portion formed below the inlet 2 may have a square tube shape (for example, a rectangle when viewed from above).

[0120] The inlet 2 is an inlet source gas G １１ The inlet port is an opening through which the raw material gas G is introduced into the housing 1 (reactor 10A). １１ is a gas containing ammonia, oxygen, and flammable gases other than ammonia. Therefore, ammonia and flammable gases other than ammonia are introduced into the housing 1 through the inlet 2. Hereinafter, the term "flammable gas" refers to flammable gases excluding ammonia. The definition and examples of flammable gases will be described later.

[0121] It is not necessary for ammonia and the combustible gas to be supplied simultaneously in a mixed state. Therefore, for example, ammonia and the combustible gas are introduced into the reactor 10 through the inlet 2 either together or independently. The combustible gas may be, for example, hydrogen. １１ The inlet raw gas G may also contain components used in the combustion of combustible gases and ammonia reforming, such as oxygen. １１ The inlet raw material gas G introduced into the housing 1 may contain gases other than ammonia, flammable gases, and oxygen. １１ is supplied to the first catalyst section 13. The inlet raw material gas G introduced into the first catalyst section 13 １１ is the gas G with heat generated by the catalytic reaction １１Ｈ Generate.

[0122] The first catalyst section 13 generates a gas G having heat. １１Ｈ The gas G １１Ｈ The generated heated gas G flows into the second catalyst section 21.１１Ｈ is the inlet source gas G １１ The gas G containing the generated heat includes ammonia heated by the heat generated by the combustion of the combustible gas in the first catalytic section 13 and oxygen not used in the first catalytic section 13. １１Ｈ may also contain unburned flammable gases.

[0123] The second catalyst section 21 emits the reformed gas G generated by the catalytic reaction. １２ The reformed gas G １２ The reformed gas G flows out from the outlet 3. １２ The opening is an opening through which the reformed gas G flows out from the inside of the housing 1 (reactor 10). １２ is, for example, hydrogen generated in the reactor 10, nitrogen generated along with hydrogen, and the introduced inlet raw material gas G １１ These are unreacted gases and accompanying gases. １１ , G １１Ｈ , G １２ are collectively referred to as gas G.

[0124] The reactor 10 can be operated at a rate of, for example, 100 m per hour. ３ ~2,000m ３ The reactor 10 has a small to medium size capable of generating hydrogen of 1000 kJ / s. The gas hourly space velocity (GHSV) of the gas G that can flow through the inside of the reactor 10 is, for example, 1,000 / hr or more and 50,000 / hr or less, preferably 3,000 / hr or more and 30,000 / hr or less. Therefore, as for the size of the reactor 10, for example, if the housing 1 has a cylindrical (approximately cylindrical) shape, the diameter of the housing 1 can be set to, for example, 300 mm or more and 800 mm or less. Furthermore, if the housing 1 is a square housing having a rectangular shape when viewed from above, the width and depth of the housing 1 can both be set to, for example, 300 mm or more and 800 mm or less.

[0125] As in the present disclosure, if the diameter, width, and depth are less than 1 m, for example, the outer surface area of ​​the casing 1 per unit volume of the first catalytic section 13 and the second catalytic section 21 becomes large, making heat radiation to the outside of the wall surface of the reactor 10A more likely. Furthermore, if the diameter, width, and depth of the casing 1 are increased to suppress heat radiation, the height of the casing 1 becomes smaller. This reduces the flow rate of the gas G, which may result in the gas G not dispersing uniformly inside the casing 1 or making it difficult for the gas G to diffuse into the catalyst. Therefore, in the example of the present disclosure, the reactor 10A is made compact, and sufficient insulation is provided for the first catalytic section 13 and the second catalytic section 21. This minimizes the radiation of heat generated by the combustion of the combustible gas and the oxidation of ammonia from the outer wall of the reactor 10A, thereby covering the heat absorbed by the ammonia decomposition reaction and achieving high hydrogen yield and thermal efficiency.

[0126] The first catalytic part 13 is disposed inside the housing 1, between the inlet 2 and the second catalytic part 21. By disposing the first catalytic part 13 in this position, the second catalytic part 21 can be heated by the heat generated by the catalytic reaction of the first catalytic part 13, and this heating can reform ammonia in the second catalytic part 21. This makes it possible to shorten the time until ammonia reforming (start-up time).

[0127] The first catalyst part 13 and the second catalyst part 21 are provided in the flow path 11 inside the housing 1. The first catalyst part 13 is provided on the upstream side of the gas flow in the flow path 11, and the second catalyst part 21 is provided on the downstream side of the gas flow in the flow path 11. Therefore, the gas G2 flowing out from the first catalyst part 13 flows into the second catalyst part 21.

[0128] The first catalyst section 13 includes a first catalyst. The first catalyst is a catalyst that converts the inlet raw material gas G １１ In the example of the present disclosure, the combustible gas is introduced from the inlet 2 together with ammonia. However, the combustible gas may be introduced from the inlet 2 separately from the ammonia. In the example of the present disclosure, first, an inlet raw material gas G containing ammonia and a combustible gas is introduced. １１is introduced from the inlet 2, and the combustible gas is, for example, selectively combusted in the first catalyst section 13. As a result, the reaction gas containing ammonia is heated by the heat generated by the combustion of the combustible gas, and the reaction gas acts as a heat medium to heat the second catalyst section 21 in the subsequent stage.

[0129] As described above, it is preferable that no ammonia or only a very small amount of ammonia is burned by selectively burning the combustible gas in the first catalyst section 13. Therefore, for example, the combustible gas can be selectively burned by using a catalyst that can selectively burn the combustible gas or by setting the temperature (for example, 80°C or lower) at which the combustible gas can be selectively ignited (burned).

[0130] The type of flammable gas is not particularly limited as long as it is a gas other than ammonia and easily combustible at room temperature (e.g., 30°C). For example, flammable gases specified in the Container Safety Regulations (Ministry of International Trade and Industry Ordinance No. 50 of 1966), which is a Japanese law, as well as at least one type of alcohol gas (vapor) such as methanol, ethanol, and propanol can be used. Further, the flammable gas can be the reformed gas G of the product stored in the product tank 1023 (see FIG. 1, etc.) or 1025 (see FIG. 4A). １２ In this case, in order to avoid poisoning of the catalyst by moisture, the reformed gas G １２ Since it is necessary to remove the moisture inside, a moisture removal unit 1026 is provided (see FIG. 1B). The moisture removal unit 1026 removes moisture by a cooling method and by using an adsorbent, thereby preventing poisoning of the first catalyst unit 13.

[0131] In the example of the present disclosure, the first catalyst provided in the first catalyst section 13 is platinum, and the combustible gas is hydrogen. Therefore, the reaction shown in the following thermochemical reaction formula (11) proceeds: H ２ +1 / 2O ２ →H ２ O Heat generation ΔH = -284 kJ / mol ... (11)

[0132] The heat generated by the combustion in the first catalytic section 13 is the heat generated by the combustion of the combustible gas. Therefore, the amount of generated heat is the amount of combustion of the combustible gas, that is, the amount of combustion of the inlet raw material gas G１１ Therefore, by providing the first catalyst part 13 that burns the combustible gas, the amount of heat generated can be controlled, and the heating temperature of the housing 1 can be suppressed.

[0133] The first catalyst section 13 is configured by disposing (packing) a particulate first catalyst on, for example, a porous plate. The particle diameter of the first catalyst is, for example, 1 mmφ or more and 10 mmφ or less.

[0134] FIG. 6 is a perspective view of the first catalyst section 13 and illustrates the size of the first catalyst section 13. FIG. 6 also illustrates the insulating material 12 surrounding the first catalyst section 13. For convenience, FIG. 6 depicts the insulating material 12 as having a rectangular shape, but this is not limited thereto. The first catalyst section 13 is cubic or rectangular (rectangular) and has a width W1, a depth D1, and a height H1. When the first catalyst section 13 is particulate, the width W1, depth D1, and height H1 of the entire particles when the particles are arranged (packed) in a rectangular shape are specified. When the first catalyst section 13 is a honeycomb catalyst, the distance between opposing outer surfaces of the honeycomb catalyst is the width W1, depth D1, and height H1.

[0135] H1 / W1 is, for example, 0.1 or more and 1.0 or less, preferably 0.3 or more and 0.7 or less. W1 / D1 is, for example, 0.5 or more and 2 or less, preferably 0.9 or more and 1.1 or less, and more preferably 1. The thickness T1 of the heat insulating material 12 in the portion surrounding the first catalyst section 13 is, for example, 50 mm or more and 300 mm or less, preferably, for example, 100 mm or more and 200 mm or less.

[0136] Returning to FIG. 5 , the inner wall of the housing 1 is provided with a thermal insulator 12. Different thermal insulators may be used in the vicinity of the inlet 2 and outlet 3 and in the portion housing the first catalyst section 13 and the second catalyst section 21. The thermal insulator 12 is made of a material that is heat-resistant and has excellent mechanical strength, and has some flexibility (elasticity). Therefore, although the thermal insulators 12 and 14 are made of different materials in the example of the present disclosure, they may be made of the same material by adjusting their shapes, for example. The thermal insulator 12 is made of, for example, a heat-resistant material having a filamentous or fibrous shape, specifically, for example, ceramic fiber or cement castable, but is not limited thereto. Note that the flexibility (elasticity) of the thermal insulator 12 in this embodiment is not as great as that of the thermal insulator 14 described later with reference to the third embodiment.

[0137] The reactor 10A includes a first distribution section 18A as shown in Fig. 5A and a second distribution section 18B as shown in Fig. 5D. As shown in Fig. 5A, the first distribution section 18A is installed between the first catalytic section 13 and the second catalytic section 21. By installing the first distribution section 18A between the first catalytic section 13 and the second catalytic section 21 in this manner, the gas G2 flowing out from the first catalytic section 13 is dispersed toward the second catalytic section 21.

[0138] In addition, as shown in FIG. 5A, by providing a first dispersion section 18A between the first catalyst section 13 and the second catalyst section 21, the gas G having heat generated in the first catalyst section 13 can be １１Ｈ ) can be prevented from being transmitted only to the vicinity directly below the first catalyst section 13, and can be made to come into uniform and even contact with the entire second catalyst section 21 arranged below the first catalyst section 13.

[0139] As shown in FIG. 5A, the first dispersion section 18A of the present disclosure provided between the first catalyst section 13 and the second catalyst section 21 directs the heated gas G generated in a direction obliquely downward from the center of the first catalyst section 13. １１Ｈ In this case, the gas G having heat generated directly below as well as in the diagonally downward direction may be blown out. １１ＨAlternatively, a porous plate filled with particulate first catalyst 13 may also serve as first dispersion section 18A. Alternatively, first dispersion section 18A may be separately and independently installed below first catalyst 13.

[0140] 5B and 5C are enlarged views of the X portion of the first dispersion section 18A in Fig. 5A, showing modified examples of the first dispersion section 18A. In Fig. 5B, the pores 18b are uniformly formed in the dispersion plate 18a that constitutes the first dispersion section 18A-1.

[0141] 5C, two types of holes (pores 18b-1 and 18b-2) are formed in the dispersion plate 18a that constitutes the first dispersion section 18A-2, with the small-diameter pores 18b-1 being formed on the central side and the large-diameter pores 18b-2 being formed on the peripheral side of the small-diameter pores 18b-1, thereby adjusting the aperture ratio. This may result in the outflow of gas G2 being more uniformly discharged on the peripheral side of the first dispersion section 18A-2 in the horizontal direction than on the central side.

[0142] In addition, as shown in FIG. 5D, the second dispersion section 18B of another example is installed between the inlet 2 and the first catalyst section 13, so that the inlet raw material gas G １１ can be dispersed toward the first catalyst section 13. Note that, although the disclosure shown in FIG. 5D also includes the first dispersion section 18A, if the dispersion conditions are favorable, the first dispersion section 18A may not be provided.

[0143] In addition, the second dispersion section 18B shown in Figure 5D may be provided above the first catalyst section 13 to form a uniform gas flow inside the second dispersion section 18B and minimize the temperature distribution in the arranged second catalyst section 21.

[0144] When the second dispersion section 18B is provided between the inlet 2 and the first catalyst section 13, for example, a basket filled with spherical or raschling-shaped filler material may be placed. Alternatively, a bottomed tube with openings on the side or bottom, or a member for adjusting the wind direction, such as a louver or wind direction plate, may be installed.

[0145] Furthermore, as shown in FIG. 5D of the present disclosure, a spherical wire mesh cage 18 filled with alumina balls 18d may be provided at a position where the flow path expands from the inlet 2 of the housing 1 (the bottom of the cage protrudes into the space of the flow path 11), and the rectified gas may pass through a packed bed formed of spherical alumina balls 18c, so that the rectified gas is dispersed from the inlet 2 to the expanding part of the reactor.

[0146] The reactor 10A includes a second catalyst section 21. The second catalyst section 21 has a honeycomb shape, and the specific structure of the second catalyst section 21 will be described later with reference to a third embodiment. The second catalyst section 21 is disposed between the first catalyst section 13 and the outlet 3, and includes a second catalyst. The second catalyst is heated by the heat generated in the first catalyst section 13, and the gas G having the generated heat is then circulated through the second catalyst section 21. １１Ｈ It is a catalyst that generates hydrogen from the ammonia contained in

[0147] The second catalyst supported on the second catalytic section 21 is a catalyst that reforms ammonia. Hydrogen is produced from ammonia through reforming. The specific components of the catalyst are not particularly limited as long as the catalyst is capable of reforming ammonia. For example, it is preferable that the catalyst contains a transition metal such as Ru, Co, Ni, Fe, or Pt as its main component.

[0148] Fig. 7 is a perspective view of the second catalyst section 21, and is a diagram illustrating the size of the second catalyst section 21. Fig. 7 also illustrates the heat insulating materials 12 and 22 that surround the second catalyst section 21.

[0149] The second catalyst section 21 is surrounded by multiple types of heat insulating materials 12, 22. The second catalyst section 21 is cubic or rectangular parallelepiped (rectangular) in shape and has a width W2, a depth D2, and a height H2. H2 / W2 is, for example, 0.5 to 3, preferably 0.8 to 2. W2 / D2 is, for example, 0.5 to 2, preferably 0.9 to 1.1, and more preferably 1. The total thickness T2 of the heat insulating materials 12, 22 surrounding the second catalyst section 21 is, for example, 50 mm to 300 mm, preferably 100 mm to 200 mm.

[0150] In the relationship between the first catalyst portion 13 and the second catalyst portion 21, W2 / W1 is, for example, 1 or more and 5 or less, preferably 2 or more and 3 or less. The first catalyst portion 13 and the second catalyst portion 21 are both covered on the sides with heat insulating material. The ratio (T1 / T2) of the thickness T1 of the heat insulating material covering the first catalyst portion 13 to the thickness T2 of the heat insulating material covering the second catalyst portion 21 is, for example, 1 or more and 3 or less, preferably 1 or more and 2 or less.

[0151] 5A and 5D, the reforming in the second catalyst section 21 mainly proceeds in two stages. Specifically, for example, the reactions include partial oxidation of ammonia (reaction formula (12) below), an oxidation reaction of ammonia (reaction formula (13) below), and a decomposition reaction of ammonia (reaction formula (14) below). The reactions of reaction formulas (12) and (13) mainly proceed on the upper side (front stage) of the second catalyst section 21, and the reaction of reaction formula (14) mainly proceeds on the lower side (lower stage) of the second catalyst section 21. However, the reforming does not necessarily proceed in two stages. NH ３ +0.25O ２ →H ２ +0.5N ２ +0.5H ２ O Heat generation △H = -75 kJ / mol ... (12) NH ３ +0.75O ２ →0.5N ２ +1.5H ２ O Heat generation △H=-317kJ / mol...(13) NH ３ →1.5H ２ +0.5N ２ Endothermic △H=+45.9kJ / mol…(14)

[0152] In particular, hydrogen is produced by the reaction of reaction formula (14), and a hydrogen-containing gas G3 is obtained.

[0153] FIG. 8 illustrates the temperature gradient between the second catalyst section 21 and the housing 1. For example, gas G2 at temperature T1 (e.g., approximately 630°C) reaches the second catalyst section 21 (particularly the second flow path 211). As a result of heat conduction within the end 213 of the second catalyst section 21, the temperature of the outer surface of the second catalyst section 21 drops to temperature T2 (e.g., approximately 450°C). Furthermore, the heat insulation 22 surrounding the second catalyst section 21 further impedes heat conduction, causing the temperature of the surface of the heat insulation 22 opposite the second catalyst section 21 to drop to temperature T3 (e.g., approximately 350°C). Finally, heat conduction is also impeded by the heat insulation 12, 22, causing the temperature of the surface of the heat insulation 12, 22 opposite the second catalyst section 21 to drop to temperature T4 (e.g., below 70°C). Finally, slight heat conduction occurs within the housing 1, causing the temperature at the outer surface of the housing 1 to drop to temperature T5 (e.g., below 50°C). Therefore, damage (oxidation, corrosion) caused by heat to the material (for example, carbon steel) that constitutes the housing 1 can be suppressed.

[0154] Compared to catalytic cracking, another technology for producing hydrogen from ammonia, ATR can achieve a higher GHSV, which is advantageous in terms of hydrogen production volume. However, the high GHSV results in a large pressure loss in the second catalyst section 21. In addition, the oxidation reaction in the second catalyst section 21 generates a large amount of heat, causing the inside of the reactor 10A to reach a high temperature of 600°C or higher.

[0155] In the ammonia decomposition reaction, lower pressure and higher temperature are advantageous from the standpoint of chemical equilibrium, as the reaction shifts toward the product (hydrogen). However, if the pressure loss is large, the inlet pressure of the reactor 10 is set high, which is unfavorable in terms of both chemical equilibrium and the compression energy of the gas G1 (raw material gas). However, higher temperatures are advantageous in terms of chemical equilibrium. However, by setting the temperature high, the reactor 10A (particularly the housing 1) is used in a temperature range where nitriding is likely to occur. Specifically, for example, at the internal temperature of the reactor 10, for example, in the temperature range of 500°C to 700°C, the nitrogen generated by the decomposition of ammonia promotes nitriding of iron, cobalt, molybdenum, etc., making the structures constituting the reactor 10 brittle. For this reason, it is necessary to use high-quality materials that are as resistant to nitriding as possible (e.g., "Inconel 600" (registered trademark) etc.) and keep the internal temperature of the reactor 10 low. This increases the cost of hydrogen production and makes it difficult for the ammonia decomposition reaction to proceed.

[0156] Therefore, in the reactor 10A of the present disclosure, in order to suppress heat radiation to the outside of the reactor 10 and to lower the temperature of the structures constituting the reactor 10 to a temperature lower than the nitriding temperature of approximately 600°C (for example, 450°C or lower), the side surfaces of the first catalyst section 13 are wrapped (covered) with a heat insulating material 12, and the side surfaces of the second catalyst section 21 are wrapped (covered) with heat insulating materials 12 and 22. This suppresses heat radiation through the side surfaces of the first catalyst section 13 and the second catalyst section 21, and makes it possible to lower the surface temperature (outside temperature) of the reactor 10 to a temperature lower than the nitriding temperature (for example, 80°C or lower).

[0157] FIG. 9 shows a structure for starting the reactor 10A using at least a portion of the hydrogen generated in the second catalyst section 21. The reactor 10A includes a heat exchanger 51, a tank 52, a pump 53, an outlet flow path 54, and a return flow path 54b. The tank 52 stores hydrogen generated in the second catalyst section 21 and discharged from the outlet 3. The hydrogen discharged from the outlet 3 is cooled to, for example, 40°C or less by cooling water CW in the heat exchanger 51 and flows into the tank 52. The tank 52 is provided in the outlet flow path 54 and stores the discharged hydrogen. The outlet flow path 54 discharges hydrogen from the outlet 3 and is, for example, a pipe. The return flow path 54b branches from a branching portion 54a of the outlet flow path 54 and returns hydrogen to the inlet 2 and is, for example, a pipe. The hydrogen in the tank 52 is returned to the inlet 2 by the operation of the pump 53. The return flow path 54b is provided with a valve 54c for regulating the flow rate of hydrogen. The hydrogen from the outlet passage 54 is used as a product.

[0158] The initial start-up of the reactor 10A is performed using a combustible gas (e.g., hydrogen in a hydrogen cylinder) stored in a separately installed cylinder or the like. As the reforming progresses, hydrogen is generated in the second catalyst section 21 as shown in reaction formula (4), and the generated hydrogen is stored in the tank 52. When the reactor 10A is started up, some or all of the hydrogen stored in the tank 52 is used as the combustible gas. This eliminates the need for a cylinder or the like when starting up the reactor 10 for the second time or later.

[0159] Fig. 10 is a graph showing an example of the temperature distribution inside the reactor 10 when combustible gas is combusted in the first catalytic section 13 under specific reaction conditions in the first embodiment. The graph shown in Fig. 10 shows the temperature distribution at the start of the reactor 10 for ammonia reforming. The horizontal axis represents the height position (cm) from the upper end of the first catalytic section 13 toward the second catalytic section 21 (downstream in the gas flow), and the vertical axis represents the temperature. For reference, the first catalytic section 13 and the second catalytic section 21 are shown at corresponding positions among the height positions shown on the horizontal axis of Fig. 10.

[0160] The reaction conditions are as follows: ３In the reactor 10 that produces hydrogen at 1000kJ / hr, the first catalyst section 13 used a platinum catalyst (3 mmφ spherical) in which 2 wt % of platinum was supported on an alumina carrier. The second catalyst section 21 used a honeycomb catalyst (W1 = 150 mm, D1 = 150 mm, H1 = 50 mm) supporting cobalt. The width ratio: W2 / W1 was 1, and the thickness ratio of the heat insulating material: T1 / T2 was 1. The first catalyst section 13 was disposed between the inlet 2 and the second catalyst section 21 in a portion having the same cross-sectional area as the second catalyst section 21. Specifically, the horizontal cross-sectional areas of both the first catalyst section 13 and the second catalyst section 21 were 300 mm x 300 mm = 90,000 mm. ｍ The amount of the first catalyst packed was 3 L, and the amount of the second catalyst packed was 40.5 L.

[0161] After hydrogen reduction at 600°C, the inlet raw material gas G １１ The flow rates of ammonia and oxygen are 250 Nm ３ / hr, 40Nm ３ / hr, plus 10 Nm of hydrogen ３ / hr was added and supplied to the first catalyst section 13 (startup of the reactor 10). The temperature distribution in the first catalyst section 13 and the second catalyst section 21 at this time is shown in FIG.

[0162] As shown in FIG. 10, an inlet source gas G containing hydrogen is introduced from the inlet. １１ is introduced into the housing 1 from the inlet 1a at room temperature (e.g., 30°C), passes through the heat insulating material 12 area, and reaches the first catalyst section 13. In this first catalyst section (platinum catalyst) 13, hydrogen is combusted to produce the inlet raw material gas G １１ As an example, in FIG. 10, the gas temperature of the inlet raw material gas G introduced at 30° C. １１ As the gas passes through the first catalyst section 13, the temperature starts to rise (from 30° C. to 280° C.) due to hydrogen combustion, and the gas temperature rises further.

[0163] That is, the inlet raw material gas G １１is introduced and ignited by catalytic combustion in the first catalytic section 13, the heat of combustion of hydrogen causes the temperature in the first catalytic section 13 to rise rapidly from room temperature (30°C).The temperature near the outlet of the first catalytic section 13 then reaches a temperature of, for example, about 180°C to 300°C, at which the partial oxidation reaction of ammonia (the reaction shown in reaction formula (2)) that proceeds near the inlet of the second catalytic section 21 in the subsequent stage can proceed.

[0164] The inside of the reactor 10B is insulated by heat insulating materials 12, 22, etc. For example, the gas G having heat generated by the catalytic reaction at a temperature of about 200°C or higher １１Ｈ As a result of the inflow of the ammonia gas, the second catalytic section 21 is heated, and the partial oxidation reaction and oxidation reaction of ammonia, which are represented by reaction formulas (12) and (13), proceed near the inlet of the second catalytic section 21. Because these are exothermic reactions, the temperature of the gas G flowing through the second catalytic section 21 further increases, and the temperature of the flowing gas G increases, for example, to 600°C or higher. However, as the gas flows downstream in the second catalytic section 21, the ammonia decomposition reaction (hydrogen production reaction), which is represented by reaction formula (14), becomes dominant. Therefore, the temperature of the gas G flowing through the second catalytic section 21 begins to decrease.

[0165] 11 is a graph showing the temperature distribution inside the reactor 10 when the supply of a combustible gas (e.g., hydrogen) is stopped and ammonia reforming is performed in the reactor 10A. The graph shown in FIG. 11 shows the temperature distribution inside the reactor 10 when the inlet raw material gas G containing no hydrogen is reformed using the second catalyst section 21 that has already been heated as shown in the graph of FIG. １１ 10 is a graph showing ammonia reforming (without hydrogen).

[0166] In FIG. 10, the temperature of the second catalyst section 21 is already in the heating range of about 600° C. to 700° C., so that the inlet raw material gas G containing, for example, ammonia (but not hydrogen) and having a temperature of about 30° C. (room temperature) １１ When the inlet source gas G １１ (without hydrogen) passes through the first catalyst section 13 without igniting. １１The inlet raw material gas G (without hydrogen) is introduced into the second catalyst section 21. At this time, although there may be some variation depending on the timing of stopping the hydrogen supply, the inlet temperature is between room temperature and 200°C and the gas flows into the second catalyst section 21. １１ (No hydrogen) The reaction proceeds in the second catalyst section 21 heated to about 600°C to 700°C.

[0167] Furthermore, the temperature of the second catalytic section 21 is maintained high in an adiabatic state, and the decomposition reaction of ammonia continues in the second catalytic section 21 even without the addition of a flammable gas, as shown in Figure 11. Note that there are some fluctuations in the heat exchange in the heat exchanger 1030 depending on the timing of hydrogen supply stop, and the inlet raw material gas G １１ The temperature of the inlet (without hydrogen) ranges from room temperature to 200°C. In FIG. 11, two types of temperature plots are shown as examples, but suitable conditions may be set appropriately in the system. Note that the temperature examples are merely examples, and the present invention is not limited to these. Note that at a relatively early timing after the hydrogen supply is stopped, although there is some fluctuation in the heat exchange in the heat exchanger 1030, the inlet raw material gas G １１ The inlet temperature (without hydrogen) ranges from room temperature to 200°C. In Figure 11, two types of temperature plots are shown as examples, but once the heat exchange with the high-temperature gas at the reactor outlet becomes steady, it reaches 500°C or higher. Note that the temperature examples are merely examples, and the present invention is not limited to these.

[0168] FIG. 12 is a flowchart showing a method for producing hydrogen (hereinafter referred to as the production method of the present disclosure). The production method shown in FIG. 12 can be performed using, for example, the reactor 10 (FIGS. 5A and 5D). Therefore, the description of FIG. 12 will be made with reference to FIG. 5 as appropriate. For convenience, FIG. 12 exemplifies hydrogen as the combustible gas. The production method of the present disclosure is also a method for reforming ammonia, and includes steps S1 to S4. As shown in FIG. 12, step S1 (introduction step) introduces an inlet feed gas G containing ammonia and a combustible gas other than ammonia. １１This is a step of introducing a flammable gas (hydrogen-containing introduced gas) into the reactor 10A. As a result, hydrogen is combusted in the first catalyst section 13, and the second catalyst section 21 is heated. The amount of the flammable gas added to the ammonia is not particularly limited, but is, for example, 0.02 mol to 0.06 mol, preferably 0.03 mol to 0.05 mol, of the flammable gas (hydrogen, etc.) per mol of ammonia.

[0169] Step S2 (heating step, combustion step) is a step in which the introduced inlet raw material gas G １１ This is a step of selectively combusting the combustible gas in the inlet raw material gas G in the first catalyst section 13. １１ This can be done by lighting it on fire.

[0170] Step S2 (heating step, combustion step) is a step of further heating the second catalytic section 21 (an example of a second catalyst) by, for example, heat generated by burning the combustible gas in the first catalytic section 13. As described above, the second catalytic section 21 is a catalytic section that generates hydrogen from ammonia. By heating the second catalytic section 21, the temperature of the second catalytic section 21 is raised to a predetermined temperature. There are no particular restrictions on the predetermined temperature, but it is preferably a temperature at which the reactions of the above reaction formulas (12) to (14) can proceed, for example. In addition, the temperature is raised to the predetermined temperature by appropriately adjusting the temperature of the inlet raw material gas G １１ This can be done by adjusting the concentration of flammable gases in the

[0171] Step S3 (reforming step) is a step in which the introduction of the combustible gas (hydrogen) is stopped after the temperature of the second catalyst section 21 (an example of a second catalyst) reaches a predetermined temperature. Since the introduction of the combustible gas (hydrogen) is stopped, the combustible gas (hydrogen) is no longer supplied to the first catalyst section 13, and combustion of the combustible gas (hydrogen) in the first catalyst section 13 is stopped.

[0172] Step S4 (reforming step) is a step of generating hydrogen from ammonia using the second catalyst section 21. The introduction of the combustible gas (hydrogen) is stopped when the inlet raw material gas G containing ammonia is １１However, the introduction of the flammable gas may be stopped by stopping the introduction of the gas containing ammonia and the flammable gas (hydrogen) and then introducing a gas containing ammonia but not the flammable gas (hydrogen).

[0173] By stopping the introduction of the combustible gas, the inlet raw material gas G containing ammonia and oxygen １１ (Gas without hydrogen introduction) does not react in the first catalyst section 13 and is supplied to the second catalyst section 21 .

[0174] The reaction pressure in the second catalytic section 21 (particularly the pressure at which the reactions of reaction formulas (2) and (3) proceed) is, for example, 0.02 MPaG to 0.6 MPaG, preferably 0.05 MPaG to 0.3 MPaG. The reaction temperature is, for example, 180°C to 800°C, preferably 200°C to 650°C. The oxygen content in the gas supplied to the second catalytic section 21 is, for example, 0.1 mol to 0.2 mol, preferably 0.12 mol to 0.16 mol per mol of ammonia. Oxygen is also consumed in the first catalytic section 13 installed upstream of the second catalytic section 21. Therefore, it is preferable to determine the amount of oxygen in the gas introduced into the reactor 10, taking into account the amount of oxygen consumed in both the first catalytic section 13 and the second catalytic section 21.

[0175] The above points can be summarized as follows: In the present disclosure, in the initial process of the step, combustible gas (hydrogen) is ignited in the first catalytic section 13 and platinum catalytic combustion occurs. As a result, the temperature of the second catalytic section 21 rises to a temperature at which the oxidation reaction of ammonia can be initiated. Then, hydrogen is produced by the oxidative decomposition of ammonia in the second catalytic section 21.

[0176] In boilers and heating furnaces that are frequently started and stopped, the reaction gas needs to be preheated to 200°C or higher before each start-up. Conventionally, an external heater (such as an electric heater or a burner) was required for this heating, and it took time to heat up the temperature. Therefore, in the present disclosure, １１When a combustible gas such as hydrogen and oxygen are added to the reaction gas, a combustion reaction proceeds in the first catalyst section 13 from room temperature (e.g., 30°C), and the temperature inside the reactor rises (see Figure 10). １１ The temperature of the reaction gas is raised in the reactor 10 to a temperature at which the oxidation reaction of ammonia begins in the second catalyst section 21 at the subsequent stage. This eliminates the need for a heating furnace and also speeds up the response of the temperature rise. This is because the reaction gas can be heated directly, rather than indirectly from the outside, resulting in a quick response. After that, the gas to which no hydrogen has been added is fed to the inlet gas G １１ By introducing the hydrogen as the second catalyst portion 21, the reforming reaction proceeds in the second catalyst portion 21.

[0177] In addition, in the present disclosure, the second catalyst part 21 is a honeycomb catalyst having a honeycomb shape, which improves the insulating properties of the second catalyst part 21 and the housing 1, and suppresses the dissipation of heat generated by the combustion of combustible gas in the first catalyst part 13 and the heat generated by the oxidation of ammonia in the second catalyst part 21.

[0178] The main subject of this disclosure is "hydrogen production capacity of 10 Nm ３ / hr~2,000Nm ３ In a small- to medium-sized reactor (1000 kJ / hr), the ratio of the reactor's outer surface area to the catalyst unit volume is large. This facilitates heat dissipation, lowering the temperature of the gas G and resulting in a lower ammonia decomposition rate. On the other hand, thickening the insulation material 12 increases the outer diameter of the reactor 10, hindering the compactness of the small-scale device. Alternatively, a large amount of oxygen must be supplied to maintain the temperature equivalent to the heat dissipation, resulting in a decrease in the hydrogen yield. Therefore, a honeycomb catalyst is used in this disclosure. Because no reaction occurs on the outer surface of the honeycomb in a honeycomb catalyst, no heat is generated on the surface in contact with the inner surface of the reactor 10 (the surface of the insulation material 12). Furthermore, because the outer wall of the honeycomb is ceramic, the catalyst itself has excellent thermal insulation properties. This allows for both compactness and improved hydrogen yield.

[0179] Furthermore, in the present disclosure, the first catalyst part 13 and the second catalyst part 21 are arranged in a portion having the same cross-sectional area (a locally expanding portion inside the housing 1). This makes it possible to suppress heat dissipation. Furthermore, as will be described in detail later with reference to the second embodiment, the first catalyst part 13 is arranged between the inlet 2 and the upper end of the locally expanding portion formed below the inlet 2. This makes it possible to increase the thickness T1 of the heat insulating material 12 covering the first catalyst part 13, thereby significantly suppressing heat dissipation from the first catalyst part 13.

[0180] In addition, in the present disclosure, the sizes of the first catalyst section 13 and the second catalyst section 21 are set as described above. The production of hydrogen from ammonia to achieve carbon neutrality requires high thermal efficiency in the production process. Therefore, the requirements for the reactor 10A are high thermal insulation, low pressure loss, and high one-pass conversion rate. To reduce pressure loss and increase thermal insulation, H1 / (W1×D1), H ２ / (W2 × D2) should be small. However, if these values ​​are too small, the flow rate of the gas G decreases, making it difficult for the gas G to diffuse inside the first catalytic section 13 and the second catalytic section 21, and the ammonia conversion rate decreases. Furthermore, the uniformity of the dispersion of the gas G is impaired, resulting in uneven flow and a decrease in the ammonia decomposition rate. Therefore, in the present disclosure, the sizes of the first catalytic section 13 and the second catalytic section 21 are optimized and set as described above, thereby improving the ammonia decomposition efficiency.

[0181] According to this embodiment, a reactor and a method for producing hydrogen with high thermal efficiency that can quickly respond to load fluctuations and start-up / shutdown on the demand side X can be provided, and the obtained hydrogen can be sent to, for example, a boiler, an industrial furnace, etc. for use.

[0182] [Sixth Embodiment] Figure 13 is a cross-sectional view showing the internal structure of a reactor 10B according to a sixth embodiment. Note that components identical to those in the fifth embodiment are denoted by the same reference numerals, and their description will be omitted. In the sixth embodiment, the first catalyst section 13 is installed near the inlet 2, unlike the first embodiment. Therefore, the first catalyst section 13 is disposed in a portion having a smaller horizontal cross-sectional area than the cross-sectional area of ​​the installation location of the second catalyst section 21. Furthermore, the shape between the inlet 2 and the upper end of the locally widened portion formed below the inlet 2 is a rectangular tube (rectangular in top view). However, the shape of the inlet 2 may also be cylindrical (circular in top view).

[0183] A dispersion section 18 is provided below the first catalyst section 13, and the lower surface of the dispersion section 18 is located in the locally widened portion. The thickness T1 of the insulating material 12 surrounding the first catalyst section 13 in the second embodiment is longer than the thickness T1 of the insulating material 12 surrounding the first catalyst section 13 in the first embodiment. Furthermore, in the second embodiment, the shape of the first catalyst section 13 is honeycomb-shaped, unlike the first embodiment. Therefore, the first catalyst section 13 is a honeycomb catalyst, similar to the second catalyst section 21. The specific structure of the first catalyst section 13 will be described later with reference to the third embodiment.

[0184] The experiment shown in FIG. 10 was also conducted for the sixth embodiment to verify its effectiveness. The experimental conditions were as follows: the first catalyst portion 13 was a honeycomb catalyst supporting platinum. The honeycomb catalyst had dimensions of width W1 = 150 mm, depth D1 = 150 mm, and height H1 = 50 mm. The amount of the first catalyst packed was 2.25 L. The other experimental conditions were the same as those shown in FIG. 10. The cross-sectional area of ​​the first catalyst portion 13 was 150 mm x 150 mm, W2 / W1 = 2, and T1 / T2 = 1.4.

[0185] Even when verified under such experimental conditions, the same effect as in the fifth embodiment (temperature distribution shown in FIG. 10) was obtained.

[0186] Seventh Embodiment Figure 14 is a cross-sectional view showing the internal structure of a reactor 10C according to a seventh embodiment. Components identical to those in the fifth and sixth embodiments are designated by the same reference numerals, and their description will be omitted. In the seventh embodiment, the housing 1 has an enlarged portion 17 between the inlet 2 and the second catalyst section 21, in which the cross-sectional area of ​​the flow path 11 formed inside the housing 1 expands toward the downstream side of the gas flow. The thermal insulator 12 is disposed along the inner surface of the housing 1, and the thickness of the thermal insulator 12 is the same regardless of the location. Therefore, the cross-sectional area of ​​the flow path 11 defined by the thermal insulator 12 expands in the enlarged portion 17 of the housing 1.

[0187] The first catalyst section 13 is disposed in the expansion section 17. By disposing the first catalyst section 13 in this position, the heated gas G2 generated in the first catalyst section 13 spreads downward along the heat insulating material 12. This makes it possible to prevent the heated gas G2 from being blown against the heat insulating material 12, and to prevent heat from being released to the outside of the reactor 10 through the heat insulating material 12.

[0188] In the example of the present disclosure, the first catalyst section 13 is installed inside the expansion section 17. Because both the first catalyst section 13 and the cylindrical body 15 have a rectangular shape, the size of the gap 16 increases the further downstream the gas flow is. In the first catalyst section 13, the temperature increases due to heat generated in the first flow path 131 the further downstream the gas flow is, so by making the gap 16 larger the further downstream the gas flow is, the insulating effect due to the presence of a gas phase can be increased.

[0189] The first catalyst section 13 is installed inside the reactor 10, for example, near the inlet 2, to prevent the heat generated by the combustion of the combustible gas from being unintentionally released to the outside, and the gas G having the generated heat supplied to the second catalyst section 21 １１Ｈ to a temperature effective for ammonia reforming (for example, 200°C or higher). This makes it possible to suppress damage to the reactor 10 (particularly the housing 1) due to heat. Furthermore, since ammonia reforming is performed, the reactor 10 can be quickly started up (prepared before ammonia reforming).

[0190] The first catalyst section 13 is disposed with a gap 16 between it and the surface 121 of the thermal insulator 12. The surface 121 faces the flow path 11 (the surface that defines the flow path 11) and is the surface that comes into contact with the gas G flowing inside the reactor 10. Therefore, because gas G is present in the gap 16, a gas phase exists between the thermal insulator 12 and the first catalyst section 13. This makes it difficult for heat generated in the first catalyst section 13 to be transferred to the thermal insulator 12. While the thermal insulator 12 has an insulating effect, some heat transfer (heat dissipation to the outside) may occur. Therefore, by using the gap 16 to avoid thermal contact between the first catalyst section 13 and the thermal insulator 12 (including contact via the solid cylindrical body 15), heat dissipation to the outside of the reactor 10 is suppressed, allowing for effective use of heat. Furthermore, thermal damage to the housing 1 can be suppressed.

[0191] The first catalyst section 13 is, for example, a honeycomb catalyst having a honeycomb shape, and has a first flow path 131 that is rectangular, for example, when viewed from above (not shown), but may also have a circular, honeycomb, or hexagonal first flow path 131. The first catalyst section 13 has a rectangular shape (cubic, rectangular parallelepiped, etc.) with some thickness. The first catalyst section 13 includes the first flow path 131 and a first holder 132. The first flow path 131 is a flow path that follows the gas flow (gas flow in the flow path 11) formed between the inlet 2 and the outlet 3.

[0192] The first holder 132 is a holder that partitions the first flow path 131 and holds the first catalyst. By providing the first catalyst section 13 with the first flow path 131 and the first holder 132, a catalytic reaction can proceed with the gas G flowing through the first flow path 131 without significantly increasing the pressure loss of the gas G flowing through the flow path 11. More specifically, by suppressing the pressure loss of the first catalyst section 13 (pressure loss is proportional to the square of the linear velocity) while increasing the GHSV of the gas G flowing through the first catalyst section 13 as much as possible, the amount of the first catalyst used can be reduced and the reactor 10 can be made more compact.

[0193] The method of supporting the first catalyst on the first holder 132 is not particularly limited. In the example of the present disclosure, for example, a raw material containing a binder (e.g., clay powder) can be extruded into the shape of the first catalyst part 13, and the catalyst component can be supported after firing. For example, in the first catalyst part 13 manufactured in this way, the inlet raw material gas G flowing through the first flow path 131１１ The first catalyst diffuses into the first holder 132, and a catalytic reaction proceeds in the first holder 132 near the first flow path 131. However, the first catalyst may be supported on, for example, the surface of the first holder 132 so as to face the first flow path 131.

[0194] The number of first flow paths 131 is not particularly limited. For example, when viewed from above the first catalyst section 13 (when the first catalyst section 13 is viewed from the inlet 2), the number of first flow paths 131 is 645.16 mm. ２ (1 inch ２ The number of cells in the first flow paths 131 per first catalyst section 13 is 200 to 2,000, preferably 400 to 1,200. The first flow paths 131 have the same cross-sectional area throughout the thickness direction of the first catalyst section 13 and extend linearly in the vertical direction. The first flow paths 131 are also regularly arranged at equal intervals.

[0195] The first flow path 131 is formed in a first holder 132. In the first catalyst section 13, the thickness of the corner wall (peripheral wall thickness) surrounding the first flow path 131, i.e., the thickness of the first end 133 (the end formed on the side of the first flow path 131) of the first holder 132, is thicker than the distance between adjacent first flow paths 131. A flammable gas such as hydrogen flows through the first flow path 131, and combustion of the flammable gas progresses in the first flow path 131. As a result, the first flow path 131 becomes hot (e.g., 150°C to 250°C, e.g., approximately 200°C), and heat generated in the first catalyst section 13 is supplied to the second catalyst section 21 in the subsequent stage. Therefore, even if some heat radiation to the housing 1 is unavoidable, it is preferable to suppress the amount of heat unintentionally radiated from the first catalyst section 13 to the outside of the reactor 10 (heat radiation amount).

[0196] The sides of the first catalyst part 13 are surrounded by, for example, flexible (elastic) heat insulating material 14. This can promote the inflow and outflow of gas G and suppress heat radiation to the sides. In particular, since the housing 1 is present on the sides of the first catalyst part 13, the heat insulating material 14 can suppress heat radiation to the housing 1. The heat insulating material 14 is made of, for example, a heat-resistant material having a filamentous or fibrous shape, and specifically, for example, rock wool, but is not limited to this.

[0197] The first catalyst section 13 is housed in, for example, a cylindrical body 15 having a bottom. The dispersion section 18 is provided on the bottom surface of the cylindrical body 15. As described above, the inlet 2 is formed in the housing 1, and the cylindrical body 15 is housed so as to fit into the inlet 2. Therefore, the gas G1 introduced through the inlet 2 flows into the cylindrical body 15, and then flows inside the cylindrical body 15, which also serves as the flow path 11.

[0198] The cylindrical body 15 includes a main body 151 that houses the first catalyst section 13. The outer shape of the main body 151 (e.g., a square tube, a cylinder, etc.) matches the shape of the inlet 2 (e.g., a rectangle, a circle, etc.).

[0199] A heat insulating material 14 is provided between the inner wall surface 154 of the cylindrical body 15 and the side surface 134 of the first catalyst section 13. The heat insulating material 14 is arranged so as to fill the space between the inner wall surface 154 and the side surface 134 as closely as possible. Furthermore, since the heat insulating material 14 is provided between the inner wall surface 154 and the side surface 134, the gas G1 introduced from the inlet 2 flows into the first flow path 131 without passing between the inner wall surface 154 and the side surface 134.

[0200] In this way, by disposing the heat insulating material 14 between the inner wall surface 154 and the side surface 134, a heat insulating effect is obtained. Furthermore, the first end 133 of the heat insulating material 14 is disposed so as to surround the first flow path 131, and heat is not generated at the first end 133 where the gas G1 does not flow, or outside the first end 133. Furthermore, the first end 133 makes it difficult for heat generated in the first flow path 131 to be transferred to the outside. Therefore, it is possible to suppress unintentional heat dissipation to the outside of the reactor 10 and to improve the heat utilization efficiency. It is also possible to suppress damage to the housing 1 due to heat.

[0201] The second catalyst section 21 is constructed by arranging a plurality of (e.g., four) unit second catalyst sections 215 horizontally in a square shape and stacking them vertically in a plurality of tiers (e.g., eight tiers). By constructing the second catalyst section 21 from a combination of a plurality of unit second catalyst sections 215 in this manner, the shape of the second catalyst section 21 can be flexibly changed to suit the design conditions, such as the shape and size of the second catalyst section 21, and the placement location, etc. However, the second catalyst section 21 does not need to be constructed from a plurality of unit second catalyst sections 215, and may be constructed in a single shape. Furthermore, the second catalyst section 21 is not limited to a rectangular shape (prism), and may be, for example, a round shape (cylinder), etc.

[0202] The unit second catalyst portion 215 is the same as the first catalyst portion 13 except for the supported catalyst. Therefore, the explanations (manufacturing method, dimensions, shape, etc.) for the first catalyst portion 13 can also be applied to the unit second catalyst portion 215.

[0203] FIG. 15 is a cross-sectional view taken along line A-A in FIG. 140, showing the second catalyst section 21 installed in the second stage. For example, the rectangular second catalyst section 21 is arranged inside the cylindrical housing 1, in the center of the housing 1 when viewed from above. The housing 1 may also be rectangular (cylindrical with corners). The insulating material 22 is wrapped around the second catalyst section 21 in the same manner as the first catalyst section 13. The insulating material 22 is the same as the insulating material 14, except that it is wrapped around a different object. Furthermore, the insulating material 12 is arranged on the outside of the insulating material 22, in the same manner as the first catalyst section 13.

[0204] Returning to FIG. 14 , the second catalyst section 21 is a honeycomb catalyst having a honeycomb shape, similar to the first catalyst section 13. In the illustrated example, the honeycomb shape has second flow paths 211 that are rectangular in top view, but the second flow paths 211 may also have, for example, a circular, honeycomb, or hexagonal shape. The second catalyst section 21 includes the second flow paths 211 and a second holder 212. The second flow paths 211 (second flow path) are flow paths along the gas flow (gas flow in the flow path 11) formed between the inlet 2 and the outlet 3. In the example of the present disclosure, the second flow paths 211 have the same cross-sectional area throughout the thickness direction of the second catalyst section 21 and extend linearly in the vertical direction. Furthermore, the second flow paths 211 are regularly arranged at equal intervals.

[0205] The second holder 212 is a holder that partitions the second flow path 211 and holds the second catalyst. With the second catalyst section 21 having such a structure, a catalytic reaction can proceed with the gas G flowing through the second flow path 211 without significantly increasing the pressure loss of the gas G flowing through the flow path 11. As a result, by suppressing the pressure loss of the second catalyst section 21 (pressure loss is proportional to the square of the linear velocity) while increasing the GHSV of the gas G flowing through the second catalyst section 21 as much as possible, the amount of catalyst used can be reduced and the reactor 10 can be made compact.

[0206] The second flow path 211 is formed in the second holder 212. The thickness of the end 213 (the lateral end of the second flow path 211) of the second holder 212 is thicker than the distance between adjacent second flow paths 211 so as to surround the second flow path 211. An exothermic reaction, described below, proceeds in the second flow path 211. As a result, the second flow path 211 reaches a high temperature (e.g., 600°C or higher and 800°C or lower), and heat generated in the first catalyst section 13 is supplied to the downstream second catalyst section 21. Therefore, even if some heat radiation to the housing 1 is unavoidable, it is preferable to suppress the amount of heat unintentionally radiated from the first catalyst section 13 to the outside of the reactor 10 (heat radiation amount). Therefore, similar to the first catalyst section 13, providing the end 213 can suppress heat radiation to the outside.

[0207] In the seventh embodiment, an experiment similar to that shown in FIG. 10 was also conducted to verify the effects. The experimental conditions were the same as those of the second embodiment except that T1 / T2 = 1. Even when verified under these experimental conditions, the same effects as those of the fifth embodiment (temperature distribution shown in FIG. 10) were obtained.

[0208] The present invention can be applied to all ammonia-hydrogen mixed fuel production devices.

[0209] 1010A to 1010C Ammonia and hydrogen mixed fuel manufacturing apparatus 1013 Oxygen supply section 1014 Raw material supply section 1015 Reforming reactor 1017 Gas component analyzer 1018 Fuel 1022 Compressor 1023 Product tank 1024 Switching valve 1025 Buffer tank 1026 Moisture removal section 1030 Plate type heat exchanger 1 Housing 10A, 10B, 10C Reactor 11 Flow path 12 Heat insulating material 121 Surface 13 First catalyst section 131 First flow path 132 First holder 133 First end 134 Side surface 14 Heat insulating material 15 Cylinder 151 Main body 154 Inner wall surface 16 Gap 17 Expansion section 18A First dispersion section 18B Second dispersion section 2 Inlet 21 Second catalyst section 211 Second flow path 212 Second holder 213 End 215 Unit second catalyst section 22 Heat insulating material 3 Outlet 51 Heat exchanger 52 Tank 53 Pump 54 Outlet flow path 54a Branching section 54b Return flow path S1 Step (introduction step) S2 Step (heating step) S3 Step (reforming step) S4 Step (reforming step) A Confluence section L1 Ammonia supply line L ２ Oxygen supply line L ３ Introduction line L ４ Reformed gas discharge line L ５ Product supply line L ６ Recycling Line L ７ Oxygen bypass line L ８ Buffer gas line G Gas G １１ Inlet raw gas G １１Ｈ Gas with generated heat G １２ Reformed gas G １３ Recycled gas V １ On-off valve V ３ On-off valve V ４ On-off valve V ５ On-off valve V １１ Regulating valve V １２ Regulating valve

Claims

1. An ammonia-hydrogen mixed fuel production apparatus, comprising: an oxygen supply unit that supplies oxygen at a desired concentration; a raw material supply unit that supplies ammonia at a desired concentration; a reforming reactor that converts ammonia into hydrogen using oxygen at a desired concentration from the oxygen supply unit to obtain a reformed gas; a gas component analyzer that is provided in a reformed gas discharge line for discharging the reformed gas from the reforming reactor and measures the concentration of either or both of hydrogen and ammonia in the reformed gas; and a plate-type heat exchanger that is provided at an intersection of a raw material supply line for supplying the raw material gas of ammonia and oxygen and the reformed gas discharge line for discharging the reformed gas, and exchanges heat between the raw material gas and the high-temperature reformed gas.

2. The ammonia-hydrogen mixed fuel production apparatus according to claim 1, further comprising: a storage tank that is provided in the reformed gas discharge line and stores the reformed gas; and a recycle line that branches from the reformed gas discharge line at a branch portion and recycles a part of the reformed gas to the raw material supply line.

3. The ammonia-hydrogen mixed fuel production apparatus according to claim 2, wherein the oxygen from the oxygen supply unit is directly introduced into the reforming reactor.

4. The ammonia-hydrogen mixed fuel production apparatus according to claim 1 or 2, wherein the oxygen supply unit is an oxygen separation device that separates oxygen from air to a desired concentration.

5. The ammonia-hydrogen mixed fuel production apparatus according to claim 1 or 2, wherein the oxygen supply unit is an air dryer that removes moisture in the supplied air.

6. The ammonia-hydrogen mixed fuel production apparatus according to claim 1 or 2, wherein the oxygen supply unit adds 3 to 20% by volume of oxygen with respect to the supply amount of ammonia.

7. The ammonia-hydrogen mixed fuel production apparatus according to claim 1 or 2, wherein the oxygen supply amount from the oxygen supply unit is controlled based on the concentration of either or both of hydrogen and ammonia from the gas component analyzer.

8. The ammonia-hydrogen mixed fuel production apparatus according to claim 1, wherein the reforming reactor includes a housing having an inlet for introducing ammonia and a combustible gas other than ammonia, and an outlet for discharging the produced gas, a first catalyst unit disposed inside the housing and including a first catalyst that generates heat by burning the combustible gas introduced from the inlet, and a second catalyst unit disposed between the first catalyst unit and the outlet, the second catalyst unit being heated by the heat generated in the first catalyst unit and including a second catalyst that generates hydrogen from ammonia.

9. The ammonia-hydrogen mixed fuel production apparatus according to claim 8, wherein the first catalyst unit is disposed between the inlet and the second catalyst unit.

10. The ammonia-hydrogen mixed fuel production apparatus according to claim 8, wherein the reactor includes a dispersion unit disposed between the first catalyst unit and the second catalyst unit for dispersing the gas flowing out of the first catalyst unit toward the second catalyst unit.

11. The ammonia-hydrogen mixed fuel production apparatus according to claim 8, further comprising an outflow passage through which a reformed gas containing hydrogen flows out from the outlet, a tank provided in the outflow passage for storing the reformed gas containing the outflowing hydrogen, and a return passage branched from a branch portion of the outflow passage for returning the reformed gas containing hydrogen to the inlet.

12. A fuel supply system, characterized in that when using the ammonia-hydrogen mixed fuel production apparatus according to claim 2 and operating at a low load with a turndown ratio of less than 30%, a part of the reformed gas is supplied as recycled gas to the reforming reactor side.

13. A method for producing hydrogen, characterized by using the ammonia-hydrogen mixed fuel production apparatus according to claim 8 and including an introduction step of introducing an introduced gas containing ammonia and a combustible gas other than ammonia into the reforming reactor, a combustion step of selectively burning the combustible gas in the introduced gas with a first catalyst, a second catalyst heating step of heating a second catalyst that generates hydrogen from ammonia with the heat generated in the combustion step, and a reforming step of stopping the introduction of the combustible gas and generating hydrogen from ammonia using the second catalyst after the temperatures of the first catalyst and the second catalyst reach a predetermined temperature.

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