Combustion-type ammonia decomposition device

Abstract

The purpose of the present invention is to provide a combustion-type ammonia decomposition device wherein NH3 and an oxidant are supplied to the combustion-type ammonia decomposition device, combustion heat generated by a combustor is utilized to the maximum extent as heat for decomposing NH3 into N2 and H2, and, furthermore, the decomposition gas is purified to efficiently produce H2. Provided is a combustion-type ammonia decomposition device (101) comprising a combustor (11) configured by a burner, a combustion furnace (12) in which the combustor (11) is disposed, a heating furnace (14) connected following the combustion furnace (12), and a catalyst vessel (15) connected following the heating furnace (14), wherein: in the combustion furnace (12), NH3 and an oxidant supplied to the combustor (11) are combusted, and a combustion gas containing steam and N2 generated in the combustion furnace (12) is supplied to the subsequent heating furnace (14); in the heating furnace (14), NH3 supplied separately to the heating furnace (14) is heated and decomposed by the combustion gas, and decomposition gas produced by decomposing the NH3 in the heating furnace (14) is supplied to the subsequent catalyst vessel (15); and in the catalyst vessel (15), residual NH3 contained in the decomposition gas is decomposed by using a catalyst (16).

Description

Combustion-type ammonia decomposition device

[0001] The present invention relates to an ammonia decomposition device that decomposes ammonia gas into nitrogen and hydrogen using a combustion flame.

[0002] For ammonia (NH ３ ) gas to hydrogen (H ２ ) and nitrogen (N ２ ) decomposition reaction, is promoted under high temperature and low pressure conditions in chemical equilibrium state. At normal pressure, the NH ３ decomposition reaction can be easily carried out by using a catalytic reaction at 400 °C or higher. As a catalyst for NH ３ decomposition, metals having NH ３ decomposition activity such as iron (Fe), cobalt (Co), nickel (Ni), ruthenium (Ru), etc. are known. These catalysts are supported on inorganic carriers such as alumina (Al ２ O ３ ) and zeolite. Industrially, Fe catalysts and Ni catalysts, which are relatively inexpensive, are widely used.

[0003] As a reactor for continuously decomposing NH ３ , a method is generally adopted in which a catalytic reaction tube (cracking tube) filled with a catalyst is heated from the outside to compensate for the heat of the endothermic reaction accompanying NH ３ decomposition. On the other hand, autothermal reforming (ATR: Auto Thermal Reformer), which directly utilizes the heat generated by burning (oxidation reaction) a part of the raw material NH ３ and decomposes (non-oxidation reaction) the remaining raw material NH ３ , is also used as an NH ３ decomposition technology (see, for example, Patent Documents 1 to 5).

[0004] For Patent Documents 1 to 4, as a combustion method, a method of burning a mixed gas of NH ３ and an oxidizing agent on the catalyst surface using an oxidation catalyst is disclosed. For Patent Document 5, a method is disclosed in which a part of the supplied ammonia is oxidized and burned using a burner of a combustor, and the generated combustion heat is used for the decomposition reaction of the remaining ammonia.

[0005] Japanese Patent Publication No. 2010-214225, Japanese Patent Publication No. 5483705, Japanese Patent Publication No. 2023-76221, Japanese Patent Publication No. 2023-83706, Japanese Patent Publication No. 7319965

[0006] In Patent Document 5, the decomposition gas temperature after the catalytic tank reaction downstream of the combustor is high at 700°C or higher, resulting in a large energy loss, and thus NH ３ From H ２ This results in a decrease in conversion efficiency to NH. Furthermore, all NH is supplied to the burner of the combustor. ３ Oxygen (O) is supplied. ２ ) Using the burner in a state of insufficient NH ３ Because it burns, there was a problem in that its ignition ability and combustion stability were reduced.

[0007] Towards the realization of a carbon-neutral society, H ２ Gas is attracting attention as a new energy source. ２ When transporting gas to a remote location, liquefied hydrogen ２ Gas or compressed H ２ It is generally transported as a gas, but compressed H ２ Gas is unsuitable for large-scale transport, and liquefied hydrogen ２ Gas is H ２ One challenge is that its low boiling point requires a great deal of energy to liquefy.

[0008] On the other hand, NH ３ Because its physical properties are similar to propane and its boiling point is high, H ２ It is easier to transport compared to NH. ３ A supply chain has already been established for its use as a raw material for fertilizer. ３ H ２ It has also attracted attention as a carrier, and NH has been transported to the consumption area. ３ Decompose H ２ By extracting it, it can be expected to have various uses as an energy source and raw material.

[0009] Therefore, in the present invention, NH is used in the combustion-type ammonia decomposition apparatus. ３ By supplying an oxidizer, the combustion heat generated in the combustor is maximized, NH ３ From N ２ and H２ The heat of decomposition is used to further purify the decomposition gas and H ２ The aim is to manufacture them efficiently.

[0010] To achieve the above objectives, the present invention provides the following means: [1] A combustion-type ammonia decomposition apparatus comprising a combustor composed of a burner, a combustion furnace in which the combustor is installed, a heating furnace following the combustion furnace, and a catalyst tank following the heating furnace, wherein in the combustion furnace, ammonia and an oxidizing agent supplied to the combustor are combusted, the combustion gas containing nitrogen and water vapor generated in the combustion furnace is supplied to the following heating furnace, in the heating furnace ammonia separately supplied to the heating furnace is heated and decomposed by the combustion gas, the ammonia decomposition gas produced by the decomposition of ammonia in the heating furnace is supplied to the following catalyst tank, and in the catalyst tank residual ammonia contained in the ammonia decomposition gas is decomposed using a catalyst. [2] The combustion-type ammonia decomposition apparatus according to [1], wherein the oxidizing agent supplied to the combustor is an oxidizing agent with an oxygen concentration of 25 vol% to 100 vol%. [3] The combustion-type ammonia decomposition apparatus according to [1] or [2], wherein the combustion-type ammonia decomposition apparatus comprises a gas purification device following the catalyst tank, wherein nitrogen and hydrogen are separated and purified from the ammonia decomposition gas discharged from the catalyst tank, and the unpurified ammonia decomposition gas containing hydrogen from the separated and purified gas is supplied to the combustor. [4] The combustion-type ammonia decomposition apparatus according to any one of [1] to [3], wherein the combustion-type ammonia decomposition apparatus comprises a condenser following the catalyst tank and a purifier following the condenser, wherein unreacted ammonia and water containing ammonia are separated from the ammonia decomposition gas discharged from the catalyst tank, and ammonia and water are separated from the water containing ammonia in the purifier.[5] The combustion-type ammonia decomposition apparatus according to any one of [1] to [4], further comprising an oxidant flow control valve for controlling the flow rate of an oxidant supplied to the combustor, and a gas analyzer for analyzing the composition of the combustion gas introduced from the combustion furnace to the heating furnace in order to determine the flow rate of the oxidant, and further comprising an ammonia flow control valve for controlling the flow rate of ammonia supplied to the combustor, and a thermometer for measuring the temperature of the ammonia decomposition gas introduced from the heating furnace to the catalyst tank in order to determine the flow rate of ammonia.

[0011] According to the present invention, NH is used in a combustion-type ammonia decomposition device. ３ The oxidizer is supplied, and the heat of combustion generated in the combustor is converted into NH ３ From N ２ and H ２ The heat of decomposition is used to further purify the decomposition gas and H ２ It can be manufactured efficiently.

[0012] This is a diagram illustrating the configuration of a combustion-type ammonia decomposition apparatus according to the first embodiment. This is a diagram illustrating the configuration of a combustion-type ammonia decomposition apparatus according to the second embodiment. This is a diagram illustrating the configuration of a combustion-type ammonia decomposition apparatus according to the third embodiment. ２ This graph shows an example of the relationship between concentration and flame temperature. ２ Potential and H ２ This graph shows an example of the relationship with concentration.

[0013] The present invention will be described below based on preferred embodiments.

[0014] <First Embodiment> Figure 1 illustrates a combustion-type ammonia decomposition apparatus according to the first embodiment. The combustion-type ammonia decomposition apparatus 101 of this embodiment comprises a combustor 11, a combustion furnace 12 in which the combustor 11 is installed, a heating furnace 14 following the combustion furnace 12, and a catalyst tank 15 following the heating furnace 14.

[0015] The combustor 11 consists of a burner. When an oxidizer close to the theoretical amount of oxygen is supplied to the burner, the burner forms a stable flame 13. Furthermore, the combustor 11 contains at least NH as fuel.３ NH is supplied. In the combustor 11, ３ A fuel containing the oxidizer is mixed with the oxidizer to form a stable flame 13.

[0016] The combustor 11 contains combustion NH ３ The supply path 21 and the oxidizer supply path 22 are connected. In the combustor 11 shown in the illustration, combustion NH ３ A supply route 21 and an oxidizing agent supply route 22 are provided separately. ３ The mixing of the oxidizer may be performed before the mixed gas starts burning in the combustor 11. In the illustrated example, the oxidizer in the oxidizer supply path 22 is indicated as "OX."

[0017] In the combustor 11, without using other fuels such as hydrocarbon fuels (petroleum, natural gas, etc.) or carbon fuels (coal, charcoal, etc.), mainly NH ３ It can be stably burned as fuel. Also, NH ３ H can be produced by its decomposition. ２ A portion of it may be burned in the combustor 11 or the combustion furnace 12. As will be described in more detail later, as part of the fuel, H ２ or NH ３ Off-gas containing the above may be supplied to the combustor 11.

[0018] The oxidizing agent supplied to the combustor 11 is NH ３ An oxidizing agent capable of oxidizing NH is preferred. ３ H produced by decomposition ２ It may contain an oxidizing agent capable of oxidizing NH. ３ From the perspective of burning it in a mixed state with an oxidizing agent, NH ３ Similarly, an oxidizing agent contained in the gas phase is preferred. Specific examples of oxidizing agents include O ２ gas or O ２ Examples of gases containing these gases include:

[0019] Equation (1) is NH ３ , H ２ , N ２ , O ２ An example of an oxidation reaction of a gas mixture containing [the specified substance] is shown.

[0020] NH ３(g) + αH ２ (g) + βN ２ (g) + (0.75 + 0.5α)O ２ (g) → (1.5 + α)H ２ O(g) + (0.5 + β)N ２ (g) (1)

[0021] The flame 13 formed by the combustor 11 can generate high temperature in the combustion furnace 12 where the combustor 11 is installed. The combustor 11 can also be combusted using only NH ３ . Equation (2) shows the reaction equation between NH ３ and O ２ , and this reaction is an exothermic reaction with ΔH = -317 kJ / mol.

[0022] NH ３ (g) + 0.75O ２ (g) → 1.5H ２ O(g) + 0.5N ２ (g) (2)

[0023] The combustion furnace 12 forms a combustion chamber when NH ３ burns. In the combustion furnace 12, the combustion gas generated by the combustion of NH ３ is temporarily accommodated. The reaction proceeding in the combustion furnace 12 is not limited to the combustion (oxidation reaction) of NH ３ , and may include the decomposition (non-oxidation reaction) of NH ３ . The combustion gas in the combustion furnace 12 may include the gas generated by the combustion of NH ３ (N ２ and H ２ O), the gas generated by the decomposition of NH ３ (N ２ and H ２ ), unreacted NH ３ , etc. When the oxidant contains N ２ , the N ２ is also included in the combustion gas.

[0024] The NH ３When a fuel and an oxidant containing it are burned, high-temperature combustion gas is generated in the combustion furnace 12. The temperature of the combustion gas can be, for example, 700 °C or higher, more preferably 1000 °C or higher, although it depends on the combustion conditions described in detail later. The combustion gas contains N generated by the combustion or decomposition of NH ３ and water vapor generated by the combustion of NH ２ . The combustion gas generated in the combustion furnace 12 is introduced into the heating furnace 14 following the combustion furnace 12. A combustion gas supply path 24 is provided between the combustion furnace 12 and the heating furnace 14 in the illustrated example.

[0025] In the heating furnace 14, NH for decomposition is supplied from a decomposition NH supply path 23 different from the combustion NH supply path 21 for the combustor 11. The NH supplied from the decomposition NH supply path 23 to the heating furnace 14 is mixed with the combustion gas supplied from the combustion furnace 12, so that NH is heated and decomposed to generate NH decomposition gas. As shown on the right side of Equation (3), the NH decomposition gas is a gas in which NH, N, and H are mixed. In the following description, the NH decomposition gas may sometimes be simply referred to as "decomposition gas".

[0026] NH(g) → 1.5(1 - γ)H(g) + 0.5(1 - γ)N(g) + γNH(g) (3)

[0027] The heating furnace 14 forms a reaction chamber when NH is thermally decomposed. In the heating furnace 14, an atmosphere with a lower proportion of O and a higher proportion of NH may be formed compared to the inside of the combustion furnace 12. Thereby, the combustion (oxidation reaction) of NH can be suppressed in the heating furnace 14 compared to the inside of the combustion furnace 12. Also, H is present in the heating furnace 14. ２ ​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​If H exists, ２ It can also suppress combustion.

[0028] NH from combustion gas in the heating furnace 14 ３ Heat is transferred to NH ３ As the temperature of rises, NH ３ Decomposition (non-oxidation reaction) proceeds. NH decomposes in the heating furnace 14. ３ The decomposition NH does not pass through the combustion furnace 12. ３ NH supplied from supply route 23 ３ In addition, NH contained in the combustion gas supplied from the combustion furnace 12 ３ It is also possible that a catalyst 16, such as the catalyst tank 15 described later, is not required to be placed inside the heating furnace 14. ３ Because the temperature is high, chemical equilibrium is reached even without using catalyst 16. ３ The decomposition may proceed.

[0029] The decomposition gas generated in the heating furnace 14 is supplied to the catalyst tank 15 which follows the heating furnace 14. In the decomposition gas supply path 25, the decomposition gas is NH ３ , N ２ , H ２ O, H ２ It may include. The decomposition gas introduced into the catalyst tank 15 still maintains a high temperature, and the sensible heat of this gas activates the catalyst 16, and the undecomposed residual NH ３ to N ２ and H ２ It can be broken down into these components. As a result, at the outlet of the catalyst tank 15, as shown on the right side of equation (4), N ２ and H ２ You can obtain gas that has been decomposed into this.

[0030] NH ３ (g) → 1.5H ２ (g) + 0.5N ２ (g) (4)

[0031] NH shown in equations (3) and (4) ３ The decomposition reaction is an endothermic reaction, and it is known that in equation (4), ΔH = +46.11 kJ / mol. As the reaction in equation (4) progresses, the temperature of the decomposition gas at the outlet of the catalyst tank 15 decreases.

[0032] The catalyst 16 is not particularly limited, but any known NH ３ A suitable decomposition catalyst may be selected from among them. NH ３ Specific examples of decomposition catalysts include transition metal catalysts such as iron (Fe), cobalt (Co), nickel (Ni), vanadium (V), chromium (Cr), manganese (Mn), and molybdenum (Mo); rare earth catalysts such as lanthanum (La), cerium (Ce), and neodymium (Nd); and precious metal catalysts such as ruthenium (Ru), rhodium (Rh), iridium (Ir), palladium (Pd), and platinum (Pt).

[0033] It is preferable to place the catalyst 16 in the catalyst tank 15 while supported on a carrier. The carrier is not particularly limited, but examples include alumina, silica, zirconia, titania, zeolite, mullite, cordierite, etc. The carrier may be porous with a large specific surface area, for example, in a honeycomb or particulate form.

[0034] In the catalyst tank 15, unreacted NH contained in the decomposition gas introduced into the catalyst tank 15 from the heating furnace 14 ３ However, at a temperature lower than the temperature inside the heating furnace 14, N ２ and H ２ It is broken down into. As a result, the decomposition gas discharged from the catalyst tank 15 has a higher residual NH content compared to the decomposition gas introduced from the heating furnace 14 to the catalyst tank 15. ３ The proportion of H ２ The proportion can be increased.

[0035] In this embodiment, the catalyst 16 is activated by the sensible heat of the decomposition gas supplied from the heating furnace 14, so there is no need to compensate for the endothermic reaction by heating from outside the catalyst tank 15, as in the external heating method. However, if the temperature is too high, the catalyst 16 may be damaged. From the viewpoint of avoiding energy loss, NH ３The temperature of the decomposition gas may decrease due to endothermic reactions associated with the decomposition reaction, but heat dissipation from the heating furnace 14 and the catalyst tank 15 (including the decomposition gas supply path 25 in the illustrated example) to the outside is suppressed. The flow of decomposition gas from the heating furnace 14 to the catalyst tank 15 (flow rate, residence time, etc.) can be designed as appropriate. For example, while the temperature of the decomposition gas is high, NH is in thermal equilibrium within the heating furnace 14. ３ The decomposition reaction may proceed, and when the temperature of the decomposition gas decreases, the catalyst 16 is used in the catalyst tank 15 to convert NH ３ The decomposition reaction may be allowed to proceed.

[0036] Furthermore, in this embodiment, the O in the oxidizing agent supplied to the combustor 11 ２ It is preferable that the oxidizing agent has a concentration of 25 vol% to 100 vol%. ２ gas or O ２ When using a gas containing O as an oxidizing agent, ２ Other components include, N ２ Examples include argon (Ar). ２ The oxidizing agent containing air or O obtained from the atmosphere ２ Enriched air is also acceptable. ２ Enriched air contains oxygen in the air. ２ It can also be obtained by adding N from air. ２ It may be obtained by removing [a certain element].

[0037] The graph in Figure 4 shows the amount of O supplied to the combustor 11. ２ An example of the relationship between concentration and the temperature of flame 13 is shown. Also, the graph in Figure 5 is O ２ Potential and H ２ An example of the concentration relationship is shown. The horizontal axis of the graph represents the amount of NH supplied to the combustor 11. ３ and O ２ It is the ratio of NH ３ O that can be oxidized in its entirety ２ The quantity is set to 1. However, O ２ Even if the quantity is 1, NH in the combustion furnace 12 ３ Complete combustion is not guaranteed, as decomposition gases may be released from the combustion furnace 12 before all of the fuel is burned.

[0038] As shown in Figure 4, O in the oxidizing agent ２By increasing the concentration, it becomes possible to increase the temperature of the flame 13 formed in the combustor 11. On the other hand, the N in the oxidizer ２ As the amount of NH decreases, the amount of combustion gas decreases, and as a result, it becomes possible to reduce the volume of the combustion furnace 12. Also, the amount of NH in the heating furnace 14 ３ The heating and decomposition efficiency also improves.

[0039] Furthermore, the oxidizing agent O ２ As a result of increasing the concentration, N in the decomposition gas ２ As the amount decreases, H at the inlet of catalyst tank 15 ２ It also has the effect of increasing the concentration. As a result, the product is processed in the gas purification device 33. ２ This improves the gas separation efficiency when extracting the gas.

[0040] In Figures 4 and 5, the oxidizing agent used in the proportional relationship is air (Air). Compared to when air is used as the oxidizing agent, O ２ When using (100 vol%), a higher temperature flame is generated, and the O in the decomposition gas ２ The concentration (mole fraction) increases.

[0041] NH for decomposition ３ NH supplied from supply route 23 to heating furnace 14 ３ The flow rate should preferably be such that the predetermined oxygen ratio m (see equation (5)) is in the range of 0.15 to 0.3.

[0042] m = (O in the oxidizer actually supplied to the combustor) ２ Quantity / Theoretical amount required to completely combust the entire amount of ammonia and ammonia decomposition gas supplied ２ quantity) (5)

[0043] The denominator of the oxygen ratio m shown in equation (5) is the NH supplied to the combustor 11 or heating furnace 14. ３ and the total amount of NH generated in the combustion furnace 12, including the decomposition gas. ３ and the O required for the complete stoichiometric combustion of the decomposition gases ２ This represents the flow rate. Furthermore, the molecule of the oxygen ratio m is the oxygen in the oxidizer actually supplied to the combustor 11. ２ This represents the flow rate. In other words, the oxygen ratio m is theoretically equal to O ２Flow rate (denominator of fractional expression) and actual O ２ It is expressed as a ratio to the flow rate (the numerator of the fractional expression).

[0044] The value of the oxygen ratio m should fall within the above range. ３ By supplying an oxidizing agent, the temperature of the decomposition gas after the reaction is completed in the catalyst tank 15 following the heating furnace 14 is set to 250°C or higher and less than 700°C, and NH is produced using catalyst 16. ３ The decomposition reaction can proceed. Also, as mentioned above, in the combustion furnace 12, NH supplied to the heating furnace 14 ３ To generate enough heat to raise the temperature, NH ３ Supply O ２ While reducing the concentration, NH can be produced without using catalyst 16. ３ It can allow the decomposition reaction to proceed. NH ３ By reducing energy loss not involved in the decomposition reaction, as a result, NH ３ From H ２ This makes it possible to increase the conversion efficiency to [the specified value].

[0045] The catalyst tank 15 can use at least two or more catalysts 16 with different physical or chemical properties. By using catalysts 16, NH can be produced even at low temperatures below 700°C. ３ H at a high rate ２ and N ２ It can be decomposed into these components. The catalyst 16 is not particularly limited, but catalysts containing nickel (Ni) and catalysts containing ruthenium (Ru) can be preferably used.

[0046] A gas purification device 33 may be installed following the catalyst tank 15. By installing the gas purification device 33 at the outlet of the catalyst tank 15, N2 is purified from the decomposition gas discharged from the catalyst tank 15. ２ and H ２ The gas can be separated and purified. The gas purification apparatus 33 can use a membrane-type purifier or a pressure swing-type separator / purifier using an adsorbent.

[0047] As the gas purification apparatus 33, a membrane gas separator or a pressure swing type (PSA, VPSA, VSA) or temperature swing type (TSA) gas separator / purifier using an adsorbent can be used. In the pressure swing type adsorption method, PSA in the broad sense can be distinguished into PSA in the narrow sense and VPSA, VSA depending on the pressure conditions of adsorption and desorption.

[0048] In this embodiment, mainly H ２ The objective is to purify the decomposition gas using as the generated gas. For this reason, if a pressure swing type separation and purification apparatus is used, due to the principle of the apparatus, H ２ Unrefined decomposition gas (off-gas) containing NH is produced. Therefore, this unrefined off-gas is used as part of the fuel for the combustor 11. ３ It may be used in combination with the gas. Of the gas separated and purified in the gas purification device 33, H ２ Preferably, the off-gas containing the above is supplied to the combustor 11 while being stored in the buffer tank 34 as needed.

[0049] In the illustrated gas purification apparatus 33, product H ２ Recovery path 33a and off-gas recovery path 33b are provided on the outlet side. A buffer tank 34 follows the off-gas recovery path 33b. Furthermore, H is supplied from the buffer tank 34 via the off-gas supply path 35. ２ Off-gas containing can be supplied to the combustor 11.

[0050] If the condenser 31, described later, is not located between the outlet of the catalyst tank 15 and the inlet of the gas purification device 33, the decomposition gas may be directly introduced from the catalyst tank 15 to the gas purification device 33. In this case, an adsorbent such as zeolite is used to remove NH from the decomposition gas. ３ , H ２ The NH may be purified. In addition, to remove moisture from the decomposition gas, a moisture removal agent that chemically reacts with moisture may be used on the decomposition gas discharge path 26 connected to the outlet of the catalyst tank 15. The gas purification apparatus 33 uses NH ３ A device for adsorbing and purifying H ２ A separate device may be provided for adsorption and purification of NH. ３ Unreacted NH recovered by an adsorption and purification device ３This can be used as fuel for the combustor 11. ２ Regarding the apparatus for adsorbing and purifying the product H, the gas purification apparatus 33 uses product H ２ This is similar to the case of separating off-gas.

[0051] In this embodiment, at least NH is used in the combustor 11 and the combustion furnace 12. ３ Includes, and further H ２ Water is produced when a fuel that may contain N is burned. Therefore, N is used in the gas purification device 33. ２ and H ２ When separating the H ２ , N ２ , H ２ O, NH ３ It may include.

[0052] A scrubber or the like can be used in the condenser 31 following the catalyst tank 15. The scrubber sprays water onto the decomposition gas to cool it and produce liquid-phase water in which water vapor in the decomposition gas and sprayed water are mixed. In addition, although the condenser 31 is not particularly limited, a device that removes moisture by condensing it through cooling, compression, etc. of the gas, such as a cooler or compressor, may also be used.

[0053] In the condenser 31, unreacted NH is removed from the decomposition gas discharged from the catalyst tank 15. ３ and NH ３ Water containing is separated. When the water condenses, undecomposed NH ３ Since it dissolves in water, a purifier 32 is installed following the condenser 31 to separate the water and NH ３ It is preferable to separate and purify it.

[0054] In the purifier 32, NH ３ From water containing NH ３ The water is separated from the purifier 32. ３Adsorbents such as zirconium phosphate that can absorb and desorb can be used. The water separated in the purifier 32 can be reused as water to condense water vapor in the gas in the scrubber of the condenser 31. NH separated in the purifier 32 ３ It can be used as fuel for the combustor 11.

[0055] At the outlet side of the condenser 31 in the illustrated example, mainly unreacted NH ３ and H ２ The first discharge path 31a from which O is discharged, and mainly H ２ and N ２ A second discharge path 31b is provided through which the gas is discharged. The gas on the second discharge path 31b side contains unreacted NH that could not be dissolved in the water on the first discharge path 31a side. ３ This may include a purifier 32 following the first discharge path 31a in the illustrated example, and a gas purification device 33 following the second discharge path 31b in the illustrated example.

[0056] In the condenser 31, H ２ Under conditions where O condenses, NH ３ H ２ It may dissolve in O to produce aqueous ammonia. In the condenser 31, NH in the decomposition gas ３ Dissolve the H in the decomposition gas. ２ To cool O, condensed liquid water may be supplied. In this case, liquid water or ammonia water may be introduced into the purifier 32 through the first discharge path 31a.

[0057] When liquid water containing dissolved ammonia is introduced into the purifier 32, the NH dissolved in the water in the purifier 32 ３ water and NH ３ It is separated into. The purifier 32 is not particularly limited, but a tower filled with an adsorbent such as zeolite can be used. NH in water ３ , ammonium (NH ４ ＋ ) They may be adsorbed onto the adsorbent as ions.

[0058] Unreacted NH adsorbed onto the adsorbent in the purifier 32 ３The method for recovering the adsorbent is not particularly limited, and any appropriate method can be adopted. For example, depending on the properties of the adsorbent, a method of desorption and recovery using a vacuum pump, heater, etc., can be used. In addition, unreacted NH can be recovered from the adsorbent. ３ The adsorption capacity of the adsorbent is regenerated by its detachment.

[0059] NH separated from water in the purifier 32 ３ NH ３ It is recovered via the recovery route 32a. Also, NH ３ The water remaining after separation is H ２ O is recovered via recovery path 32b. H ２ The water discharged from the oxygen recovery path 32b may be purified as needed and then reused. For example, unreacted NH4 in the condenser 31 from the decomposition gas. ３ The water supplied to separate the substances may circulate between the condenser 31 and the purifier 32.

[0060] The above-mentioned combustion NH ３ Supply route 21, oxidizing agent supply route 22, decomposition NH ３ Supply path 23, combustion gas supply path 24, decomposition gas supply path 25, decomposition gas discharge path 26, first discharge path 31a, second discharge path 31b, NH ３ Recovery route 32a, H ２ O Recovery route 32b, product H ２ Examples of various routes, such as the recovery route 33a, the off-gas recovery route 33b, and the off-gas supply route 35, include piping. The cross-sectional area and length of each route can be appropriately set according to the composition and flow rate of the fluid flowing through the route, the properties of the parts connected before and after the route, and other factors.

[0061] In this embodiment, NH is heated in the heating furnace 14. ３ The mixture is heated and NH is produced in the catalyst tank 15. ３ The decomposed gas is purified in the gas purification device 33, and H ２ The objective is to efficiently extract O. ２ If it includes NH ３ The decomposition (non-oxidation reaction) efficiency decreases, which is undesirable.

[0062] Therefore, a gas analyzer 42 was installed at the outlet of the combustion furnace 12 to analyze the O in the combustion gas. ２ It is preferable to measure the concentration and control the flow rate of the oxidizer supplied to the combustor 11 with the oxidizer flow rate control valve 41. The gas analyzer 42 analyzes the composition of the combustion gas introduced from the combustion furnace 12 to the heating furnace 14 in order to determine the flow rate of the oxidizer supplied to the combustor 11. It is desirable that the oxygen concentration in the combustion gas at the outlet of the combustion furnace 12 be 0.2% or less.

[0063] Furthermore, in this embodiment, NH heated in the heating furnace 14 ３ Since the catalyst is decomposed in the catalyst tank 15, the inlet gas temperature of the catalyst tank 15 is an important parameter for operating the catalyst 16. Therefore, a thermometer 52 is installed at the inlet of the catalyst tank 15, and the NH supplied to the combustor 11 is controlled so that the inlet gas temperature is maintained at the optimal temperature. ３ Flow rate, NH ３ The flow rate is controlled by the flow control valve 51. The thermometer 52 measures the amount of NH supplied to the combustor 11. ３ To determine the flow rate, the temperature of the decomposition gas introduced from the heating furnace 14 to the catalyst tank 15 is measured.

[0064] The combustor 11 contains H contained in the decomposition gas generated by the gas purification device 33. ２ NH ３ It can also be supplied as fuel. For this reason, in order to control the inlet gas temperature of the catalyst tank 15, NH ３ By controlling the flow rate, the amount of NH supplied as fuel can be controlled. ３ The flow rate can be minimized.

[0065] <Other Embodiments> This embodiment is not limited to the configuration shown in Figure 1. For example, as shown in Figures 2-3, the arrangement of the combustion furnace 12, heating furnace 14, catalyst tank 15, gas analyzer 42, and thermometer 52 can be different from that shown in Figure 1. In the configuration shown in Figure 1, the combustion furnace 12, heating furnace 14, and catalyst tank 15 are each composed of separate furnace bodies or containers.

[0066] In both the configuration shown in Figure 1 and the configuration different from Figure 1, the combustion furnace 12 generates sufficient heat through combustion, and the heating furnace 14 generates NH without using the catalyst 16. ３The decomposition reaction proceeds, and in the catalyst tank 15, the catalyst 16 is used to generate NH even at a lower temperature than inside the heating furnace 14. ３ The decomposition reaction can proceed. Furthermore, for configurations different from Figure 1 (such as the second embodiment in Figure 2 and the third embodiment in Figure 3), the condenser 31, purifier 32, gas purification device 33, buffer tank 34, and off-gas supply path 35 can be used in the same way as in the configuration shown in Figure 1.

[0067] In the combustion-type ammonia decomposition apparatus 102 shown in Figure 2, the combustion furnace 12 and the heating furnace 14 are formed within the same furnace body 112. In this case, the gas analyzer 42 can be placed in the boundary region between the combustion furnace 12 and the heating furnace 14 within the same furnace body 112. Also, in the configuration shown in Figure 2, similar to the configuration in Figure 1, a thermometer 52 is placed in the decomposition gas supply path 25 between the heating furnace 14 and the catalyst tank 15.

[0068] In the combustion-type ammonia decomposition apparatus 103 shown in Figure 3, the combustion furnace 12, the heating furnace 14, and the catalyst tank 15 are formed within the same furnace body 113. In this case, a gas analyzer 42 is positioned in the boundary region between the combustion furnace 12 and the heating furnace 14 within the same furnace body 113, and a thermometer 52 is positioned in the boundary region between the heating furnace 14 and the catalyst tank 15 within the same furnace body 113.

[0069] Although not specifically shown in the figures, in this embodiment, a combustion gas supply path 24 is provided between the combustion furnace 12 and the heating furnace 14, and a configuration in which the heating furnace 14 and the catalyst tank 15 are formed within the same furnace body is also conceivable. In this case, a gas analyzer 42 may be placed in the combustion gas supply path 24 between the combustion furnace 12 and the downstream furnace body (heating furnace 14 and catalyst tank 15), and a thermometer 52 may be placed in the boundary region between the heating furnace 14 and the catalyst tank 15 within the same furnace body.

[0070] If the combustion gas supply path 24 is omitted between the combustion furnace 12 and the heating furnace 14, the heating furnace 14 region may follow the combustion furnace 12 region within the same furnace body 112, 113. The boundary region between the combustion furnace 12 and the heating furnace 14 within the same furnace body 112, 113 may have the same cross-sectional area as the combustion furnace 12 region or the heating furnace 14 region with respect to the gas flow direction, or it may have a different cross-sectional area than the combustion furnace 12 region or the heating furnace 14 region. It is preferable that the gas flow direction is generally from the combustion furnace 12 towards the heating furnace 14, and that backflow from the heating furnace 14 towards the combustion furnace 12 is suppressed.

[0071] If the boundary region between the combustion furnace 12 and the heating furnace 14 has the same cross-sectional area as the regions of the combustion furnace 12 and heating furnace 14 before and after it, the gas analyzer 42 may be positioned at an appropriate location in the boundary region between the combustion furnace 12 and the heating furnace 14 in the direction of gas flow. Depending on the situation, the position of the gas analyzer 42 in the direction of flow within the same furnace body may be changed. Examples of positions for the gas analyzer 42 in the boundary region between the combustion furnace 12 and the heating furnace 14 include a position closer to the combustion furnace 12, a position closer to the heating furnace 14, or a position intermediate between the two.

[0072] If the same furnace body 112, 113 includes a combustion furnace 12 and a heating furnace 14, decomposition NH ３ The supply path 23 is provided in the area of ​​the heating furnace 14. As described above, the decomposition NH ３ NH supplied from supply route 23 ３ When mixed with the combustion gas supplied from the combustion furnace 12, the NH inside the heating furnace 14 is compared to the NH inside the combustion furnace 12. ３ It is preferable that the combustion (oxidation reaction) of the combustion gas can be suppressed. The composition of the combustion gas in the combustion furnace 12 and the amount of NH supplied to the heating furnace 14 relative to the combustion gas are also important. ３ By appropriately setting the proportions, etc., the NH for decomposition ３ From supply route 23 to NH ３ After the supply of NH, the gas composition and gas temperature are adjusted to lower the oxidant concentration and gas temperature in the heating furnace 14 compared to that in the combustion furnace 12. ３ This can suppress combustion (oxidation reaction).

[0073] If the decomposition gas supply path 25 is omitted between the heating furnace 14 and the catalyst tank 15, the region of the catalyst tank 15 may follow the region of the heating furnace 14 within the same furnace body 113. The boundary region between the heating furnace 14 and the catalyst tank 15 within the same furnace body 113 may have the same cross-sectional area as the region of the heating furnace 14 or the region of the catalyst tank 15 with respect to the gas flow direction, or it may have a different cross-sectional area than the region of the heating furnace 14 or the catalyst tank 15. It is preferable that the gas flow direction is generally from the heating furnace 14 toward the catalyst tank 15, and that backflow from the catalyst tank 15 toward the heating furnace 14 is suppressed.

[0074] If the boundary region between the heating furnace 14 and the catalyst tank 15 has the same cross-sectional area as the regions of the heating furnace 14 and catalyst tank 15 before and after it, the thermometer 52 may be placed at an appropriate position in the boundary region between the heating furnace 14 and the catalyst tank 15 in the direction of gas flow. Depending on the situation, the position of the thermometer 52 in the direction of flow within the same furnace body may be changeable. Examples of positions for the thermometer 52 in the boundary region between the heating furnace 14 and the catalyst tank 15 include a position closer to the heating furnace 14, a position closer to the catalyst tank 15, or a position intermediate between the two.

[0075] Although the present invention has been described above based on preferred embodiments, the present invention is not limited to the embodiments described above, and various modifications are possible without departing from the spirit of the invention. Modifications include adding, substituting, omitting, or otherwise changing the components in each embodiment. It is also possible to combine components used in two or more embodiments as appropriate.

[0076] 11... Combustor, 12... Combustion furnace, 13... Flame, 14... Heating furnace, 15... Catalyst tank, 16... Catalyst, 21... Combustion NH ３ Supply route, 22... Oxidizing agent supply route, 23... Decomposition NH ３ Supply route, 24... Combustion gas supply route, 25... Decomposition gas supply route, 26... Decomposition gas discharge route, 31... Condenser, 31a... First discharge route, 31b... Second discharge route, 32... Purifier, 32a... NH ３ Recovery route, 32b...H ２ O Recovery route, 33... Gas purification device, 33a... Product H ２Recovery route, 33b... Off-gas recovery route, 34... Buffer tank, 35... Off-gas supply route, 41... Oxidizer flow control valve, 42... Gas analyzer, 51... NH ３ Flow control valve, 52... thermometer, 101, 102, 103... combustion type ammonia decomposition unit, 112, 113... furnace body.

Claims

1. A combustion-type ammonia decomposition apparatus comprising: a combustor composed of a burner; a combustion furnace in which the combustor is installed; a heating furnace following the combustion furnace; and a catalyst tank following the heating furnace, wherein in the combustion furnace, ammonia and an oxidizing agent supplied to the combustor are combusted; the combustion gas containing nitrogen and water vapor generated in the combustion furnace is supplied to the following heating furnace; in the heating furnace, ammonia separately supplied to the heating furnace is heated and decomposed by the combustion gas; the ammonia decomposition gas produced by the decomposition of ammonia in the heating furnace is supplied to the following catalyst tank; and in the catalyst tank, residual ammonia contained in the ammonia decomposition gas is decomposed using a catalyst.

2. The combustion-type ammonia decomposition apparatus according to claim 1, characterized in that the oxidizing agent supplied to the combustor is an oxidizing agent having an oxygen concentration of 25 vol% to 100 vol%.

3. The combustion-type ammonia decomposition apparatus according to claim 1 or 2, wherein the combustion-type ammonia decomposition apparatus comprises a gas purification apparatus following the catalyst tank, wherein nitrogen and hydrogen are separated and purified from the ammonia decomposition gas discharged from the catalyst tank, and the unpurified ammonia decomposition gas containing hydrogen from the separated and purified gas is supplied to the combustor.

4. The combustion-type ammonia decomposition apparatus according to claim 1 or 2, comprising a condenser following the catalyst tank and a purifier following the condenser, wherein in the condenser, unreacted ammonia and ammonia-containing water are separated from the ammonia decomposition gas discharged from the catalyst tank, and in the purifier, ammonia and water are separated from the ammonia-containing water.

5. The combustion-type ammonia decomposition apparatus according to claim 1 or 2, further comprising: an oxidant flow control valve for controlling the flow rate of an oxidant supplied to the combustor; a gas analyzer for analyzing the composition of the combustion gas introduced from the combustion furnace to the heating furnace in order to determine the flow rate of the oxidant; and the combustion-type ammonia decomposition apparatus further comprising: an ammonia flow control valve for controlling the flow rate of ammonia supplied to the combustor; and a thermometer for measuring the temperature of the ammonia decomposition gas introduced from the heating furnace to the catalyst tank in order to determine the flow rate of ammonia.

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