Hydrogen production apparatus for producing hydrogen from ammonia

Abstract

A hydrogen production apparatus of the present invention comprises: an ammonia decomposition reactor for decomposing ammonia to discharge a mixed gas including hydrogen, nitrogen, and unreacted ammonia; an ammonia remover for receiving the mixed gas, adsorbing and removing the unreacted ammonia included in the mixed gas, and discharging a first product gas including hydrogen and nitrogen and a first tail gas; and a nitrogen remover for receiving the first product gas, removing nitrogen included in the first product gas, and discharging a second product gas including hydrogen and a second tail gas, wherein the second product gas discharged from the nitrogen remover is resupplied to the nitrogen remover as a purge gas and a pressurizing gas. According to the hydrogen production apparatus of the present invention, high-purity hydrogen can be continuously produced in large quantities.

Description

Hydrogen production device that produces hydrogen from ammonia

[0001] The present invention relates to a hydrogen production device that produces hydrogen from ammonia.

[0002] Hydrogen production technology can be generally categorized into gray hydrogen technology, which produces carbon dioxide in the process of producing hydrogen from fossil fuels; blue hydrogen technology, which produces synthesis gas using unused energy sources such as low-grade coal, petroleum coke, biomass, and waste, and reforms it to produce hydrogen; and green hydrogen technology, which produces hydrogen through water electrolysis using renewable energy sources.

[0003] Green hydrogen is considered a next-generation energy source, but due to the high cost of hydrogen production, research into hydrogen production through natural gas reforming and ammonia decomposition is also ongoing. Natural gas reforming, however, emits carbon dioxide during hydrogen production, making hydrogen production using ammonia, which does not emit carbon dioxide during the reaction, increasingly important.

[0004] In particular, ammonia is 120 kg / m 3 It is being emphasized as an essential technology for achieving carbon neutrality as it can utilize existing storage and transportation infrastructure almost as is as an ultra-high-capacity hydrogen storage and transport vehicle with a storage capacity of .

[0005] Hydrogen produced from ammonia decomposition can be used in various applications. However, to use it at a fuel-quality level, ammonia removal and high-purity hydrogen must be secured. Removal of unreacted residual ammonia and hydrogen / nitrogen separation processes are key elements in producing high-purity hydrogen. Temperature swing adsorption (TSA) or pressure swing adsorption (PSA) processes are commonly used for this purpose. The PSA process separates gases by varying the pressure of the adsorbent to adsorb the adsorbate. The PSA process involves a series of steps, including adsorption, desorption, pressure accumulation, and pressure reduction, and product quality and recovery rates can be ensured by varying conditions such as pressure, temperature, and gas flow at each step. However, due to the trade-off between recovery rate and purity in the PSA process, a process that can improve recovery rate while maintaining high purity is needed.

[0006] According to one aspect of the present invention, a hydrogen production device capable of mass-producing high-purity hydrogen can be provided.

[0007] According to one aspect of the present invention, a hydrogen production device can be provided that reduces the amount of raw materials input and reduces the amount of exhaust gas.

[0008] According to one embodiment of the present invention, a hydrogen production device is provided, comprising: an ammonia decomposition reactor for decomposing ammonia to discharge a mixed gas containing hydrogen, nitrogen, and unreacted ammonia; an ammonia remover for receiving the mixed gas, removing unreacted ammonia contained in the mixed gas by adsorption, and discharging a first product gas and a first tail gas; and a nitrogen remover for receiving the first product gas, removing nitrogen contained in the first product gas, and discharging a second product gas and a second tail gas, wherein the second product gas discharged from the nitrogen remover is resupplied to the nitrogen remover as a cleaning gas and a pressure-saving gas.

[0009] According to another embodiment of the present invention, a hydrogen production device is provided, wherein the first tail gas discharged from the ammonia remover is resupplied as combustion gas for removing unreacted ammonia from the ammonia decomposition reactor, the first product gas discharged from the ammonia remover is resupplied as accumulator gas to the ammonia remover, and the second tail gas discharged from the nitrogen remover is resupplied as cleaning gas to the ammonia remover.

[0010] According to another embodiment of the present invention, a hydrogen production device is provided, wherein the first generated gas comprises 75 to 80 vol% hydrogen and 20 to 25 vol% nitrogen.

[0011] According to another embodiment of the present invention, a hydrogen production device is provided, wherein the first tail gas comprises 10 to 20 vol% hydrogen, 40 to 45 vol% nitrogen, and 40 to 45 vol% ammonia.

[0012] According to another embodiment of the present invention, a hydrogen production device is provided, wherein the first generated gas contains 0.3 to 1 ppm of ammonia.

[0013] According to another embodiment of the present invention, a hydrogen production device is provided, wherein the second generated gas contains at least 99% by volume of hydrogen.

[0014] According to another embodiment of the present invention, a hydrogen production device is provided, wherein the second tail gas comprises 25 to 30 volume % of hydrogen and 70 to 75 volume % of nitrogen.

[0015] According to another embodiment of the present invention, a hydrogen production device is provided, wherein the second tail gas contains 0.5 to 1 ppm of ammonia.

[0016] According to another embodiment of the present invention, a hydrogen production device is provided, wherein the ammonia remover and the nitrogen remover include carbon molecular sieve (CMS), zeolite, metal-organic framework (MOF), or covalent organic frameworks (COF) as adsorbents.

[0017] According to another embodiment of the present invention, a hydrogen production device is provided, wherein the adsorption time in the ammonia remover is 360 to 480 seconds and the adsorption pressure is 7 to 8 barG.

[0018] According to another embodiment of the present invention, a hydrogen production device is provided, wherein the adsorption time in the nitrogen remover is 240 to 360 seconds and the adsorption pressure is 7 to 8 barG.

[0019] According to one embodiment of the present invention, the purity of hydrogen produced can be increased.

[0020] According to one embodiment of the present invention, high-purity hydrogen can be continuously mass-produced.

[0021] According to one embodiment of the present invention, environmental pollution occurring during the hydrogen production process can be reduced.

[0022] FIG. 1 is a schematic drawing of a hydrogen production device according to one embodiment of the present invention.

[0023] Figure 2 is a schematic diagram showing the process of an ammonia decomposition reactor according to one embodiment of the present invention.

[0024] Figure 3 is a schematic diagram showing the process of an ammonia remover according to one embodiment of the present invention.

[0025] Figure 4 is a schematic diagram showing the process of a nitrogen remover according to one embodiment of the present invention.

[0026] Figure 5 is a diagram showing the pressure change inside an ammonia remover.

[0027] Figure 6 is a diagram showing the pressure change inside the nitrogen remover.

[0028] Figure 7 is a diagram showing the concentration of ammonia contained in the first generated gas and the concentration of ammonia contained in the second generated gas.

[0029] Figure 8 is a diagram showing the hydrogen concentration of the second generated gas.

[0030] Hereinafter, the present invention will be described in detail with reference to the attached drawings. However, these are merely exemplary and the present invention is not limited to the specific embodiments described as examples.

[0031] FIG. 1 is a schematic diagram showing a hydrogen production device according to one embodiment of the present invention.

[0032] Referring to the above drawing 1, a hydrogen production device according to one embodiment of the present invention includes an ammonia decomposition reactor (101), an ammonia remover (201), and a nitrogen remover (301).

[0033] The ammonia remover (201) and nitrogen remover (301) of the present invention can remove ammonia and nitrogen, respectively, through a pressure swing adsorption (PSA) process. By operating the two processes in conjunction, the product gas and tail gas generated in each process can be recycled.

[0034] Figure 2 is a process diagram schematically illustrating the process of an ammonia decomposition reactor (101) according to one embodiment of the present invention. The ammonia decomposition reactor (101) decomposes ammonia to produce hydrogen and nitrogen. Specifically, the ammonia decomposition reactor (101) decomposes ammonia to discharge a mixed gas containing hydrogen, nitrogen, and unreacted ammonia.

[0035] The ammonia decomposition reactor (101) may be one or more. If there are two or more ammonia decomposition reactors (101), ammonia can be divided into small portions and simultaneously decomposed, and the temperature of the ammonia decomposition reactor (101) can be uniformly controlled, which can be efficient.

[0036] The reaction equation for ammonia decomposition may be an endothermic reaction as follows.

[0037] Ammonia decomposition reaction: 2NH3→ N2+ 3H2(△H=46 kJ / mol)

[0038] An ammonia decomposition reactor (101) according to one embodiment may include a reaction unit (102) in which the ammonia decomposition reaction described above occurs to produce nitrogen and hydrogen. The internal temperature of the reaction unit (102) may be, for example, 500 to 650°C, but the temperature conditions may vary depending on the process configuration and the catalyst used. The internal pressure of the reaction unit (102) is not particularly limited, but may be, for example, 0 to 7 barG. The above-mentioned pressure range may vary depending on the operating pressure of an ammonia remover (201), a nitrogen remover (301), etc. located at the rear end of the ammonia decomposition reactor (101).

[0039] An ammonia decomposition reactor (101) according to one embodiment may include a combustion unit (103) that supplies heat to the reaction unit (102). The combustion unit (103) may heat the reaction unit (102) by combusting combustion air and fuel, and may supply the heat to the reaction unit (102).

[0040] The above combustion unit (103) can be supplied with fuel and combustion air, and can generate heat through a combustion reaction with oxygen in the combustion air. The fuel is not particularly limited as long as it is a fuel commonly used for combustion reactions, but may be, for example, fossil fuel-based LNG or LPG, but may be used in combination with hydrogen and ammonia to prevent CO2 emissions in advance.

[0041] The internal temperature of the combustion unit (103) is not particularly limited, but may be, for example, 700 to 1000°C. The combustion unit (103) in the above-described temperature range can efficiently heat the reaction unit (102) so that the ammonia decomposition reaction can proceed.

[0042] The above ammonia decomposition reactor (101) may include a catalyst as needed to improve the decomposition reaction efficiency. The catalyst may be a conventional catalyst used in ammonia decomposition, and specifically, may be a nickel-based catalyst, a ruthenium-based catalyst, etc.

[0043] One embodiment may further include a liquid ammonia tank (104) for supplying liquid ammonia to the ammonia decomposition reactor (101). In addition, an ammonia pump (not shown) for supplying the liquid ammonia may further be included.

[0044] One embodiment may further include an air blower (105) for supplying combustion air from the outside to the combustion unit (103) in the ammonia decomposition reaction process.

[0045] FIG. 3 is a drawing schematically showing the process of an ammonia remover (201) according to one embodiment of the present invention. The ammonia remover (201) according to one embodiment can receive the mixed gas discharged from the ammonia decomposition reactor (101) and remove unreacted ammonia contained in the mixed gas by adsorption. Specifically, the ammonia remover (201) removes the unreacted ammonia contained in the mixed gas by adsorption, and discharges a first product gas containing hydrogen and nitrogen and a first tail gas. The first product gas discharged from the ammonia remover (201) is supplied to a nitrogen remover (301).

[0046] According to one embodiment of the present invention, the first tail gas discharged from the ammonia remover (201) can be re-supplied to the ammonia decomposition reactor (101) as combustion gas for removing unreacted ammonia.

[0047] According to one embodiment of the present invention, a portion of the first generated gas discharged from the ammonia remover (201) can be resupplied to the ammonia remover (201) as a pressurized gas.

[0048] The first product gas may comprise 75 to 80 volume percent hydrogen, 20 to 25 volume percent nitrogen, and 0.3 to 1 ppm ammonia.

[0049] The first tail gas may comprise 10 to 20 volume percent hydrogen, 40 to 45 volume percent nitrogen, and 40 to 45 volume percent ammonia.

[0050] The first tail gas discharged from the ammonia remover (201) can be re-supplied as combustion gas to the ammonia decomposition reactor (101), for example, the first tail gas can be transferred to the combustion section (103) of the ammonia decomposition reactor and used as fuel. The first tail gas contains ammonia. By using unreacted ammonia as combustion fuel, the energy efficiency of the ammonia decomposition reactor (101) can be increased, and the unreacted ammonia can be removed by combustion. Alternatively, the ammonia contained in the first tail gas transferred to the combustion section (103) can be mixed with a fuel for the decomposition reaction and used as fuel.

[0051] When a portion of the first generated gas discharged from the ammonia remover (201) is re-supplied to the ammonia remover (201) as a pressurized gas, the nitrogen partial pressure inside the ammonia remover (201) is lowered, so that the nitrogen adsorption amount can be reduced and the adsorption performance of the ammonia remover (201) can be improved. When the adsorption performance of the ammonia remover (201) is improved, the breakthrough time of the adsorption tower is increased, and ultimately the overall cycle time of the ammonia removal process can be reduced. The reduction in the cycle in the ammonia removal process of the ammonia remover (201) reduces the amount of gas consumed as a cleaning gas, thereby reducing the amount of hydrogen ultimately discarded. As a result, the recovery rate of the entire process increases.

[0052] Ammonia adsorption is the selective adsorption of ammonia from a mixed gas containing hydrogen, nitrogen, and unreacted ammonia, and ammonia can be adsorbed using an adsorbent. The ammonia remover (201) may include a plurality of adsorption towers. The adsorbent is not particularly limited as long as it is a material that selectively adsorbs ammonia, but must be an adsorbent with high ammonia selectivity. The ammonia adsorbent must have the highest ammonia selectivity, and it is preferably an adsorbent with higher nitrogen selectivity than hydrogen selectivity. For example, it may be at least one selected from the group consisting of CMS (Carbon Molecular Sieve), zeolite, MOF (Metal-organic framework), COF (Covalent organic frameworks), activated carbon, alumina, silica, etc. Table 1 shows the adsorption performance of a CMS adsorbent as an example.

[0053] Gas adsorption pressure (bar)Adsorption capacity (mmol / g)CMSH270.37N271.16NH376.02

[0054] In the ammonia remover (201), the adsorbent that has adsorbed ammonia can desorb and recover ammonia while the adsorbent is regenerated through processes such as depressurization and cleaning, and the desorbed ammonia can be recovered and recycled. Specifically, the ammonia remover (201) can desorb ammonia according to a cleaning process in order to regenerate the adsorbent that has adsorbed ammonia. The cleaning of the ammonia remover (201) can be divided into high-temperature cleaning and low-temperature cleaning. The high-temperature cleaning may refer to a process of desorbing ammonia adsorbed on the adsorbent of the ammonia remover (201) with high-temperature nitrogen gas, and the low-temperature cleaning may be a process of cooling the temperature of the adsorbent.

[0055] The ammonia remover (201) may include a first product gas storage tank (202) for storing a first product gas containing hydrogen and nitrogen from which ammonia has been removed, and a first tail gas storage tank (203) for storing ammonia removed from the ammonia remover (201). In this case, the first product gas stored in the first product gas storage tank (202) is supplied to a nitrogen remover (301).

[0056] The ammonia remover (201) can undergo the processes of equalizing pressure, accumulating pressure, adsorption, depressurizing, and desorption. Figure 5 shows the internal pressure change of one adsorption tower of the ammonia remover and the nitrogen remover.

[0057] The ammonia removal device (201) may include multiple adsorption towers. In this case, each adsorption tower operates simultaneously and in conjunction. Table 2 shows the cycles of four adsorption towers according to an exemplary embodiment. Here, one cycle may take approximately 28 minutes. Upon completion of one cycle, the next cycle begins immediately. In multiple adsorption towers, the cycles may be repeated, and the ammonia removal process may be performed continuously.

[0058] The cycle of the adsorption tower according to the exemplary implementation example below is only illustrative of the present invention and does not limit the scope of the appended claims, and it is obvious to those skilled in the art that various changes and modifications are possible within the scope and technical idea of ​​the present invention.

[0059] SEQ step123456789101112Time (sec)3036030303603030360303036030BED 1ADSEQ2RESTEQ1BDPGEQ1EQ2PRPRBED 2BDPGEQ1EQ2PRPRADSEQ2RESTEQ1BED 3EQ2PRPRADSEQ2RESTEQ1BDPGEQ1BED 4EQ2RESTEQ1BDPGEQ1EQ2PRRADS

[0060] Each symbol represents the following process.

[0061] ADS(Adsorption): Adsorption process

[0062] EQ1 (pressure equalization): primary pressure equalization process

[0063] EQ2 (pressure equalization): secondary pressure equalization process

[0064] REST(rest): Rest process

[0065] BD(blowdown): depressurization process

[0066] PR(pressurization): pressurization process

[0067] PG (purge): desorption process

[0068] The pressure equalization process is the process of equalizing the pressure between two or more adsorption towers. The pressure equalization process can be divided into two stages: the primary and secondary equalization processes. Each adsorption tower has a valve connected to the other adsorption towers. The pressure equalization process can be performed by opening and closing the valves according to the process sequence.

[0069] The primary pressure equalization process involves opening the valves of the adsorption towers that have undergone the desorption process and the resting phase, thereby equalizing the pressure of the adsorption tower that has undergone the desorption process with that of the adsorption tower that has undergone the resting phase. The primary pressure equalization process can take approximately 30 seconds. The pressure of the adsorption towers that have undergone the primary pressure equalization process can be approximately 1 barG.

[0070] The secondary pressure equalization process involves opening the valves of the adsorption towers that have undergone the primary pressure equalization process and the adsorption towers that have undergone the secondary pressure equalization process, thereby equalizing the pressure of the latter with that of the former. The secondary pressure equalization process can take approximately 30 seconds. The pressure of the adsorption towers that have undergone the secondary pressure equalization process can reach approximately 4 barG.

[0071] After the secondary equalization process is completed, a pressurization process is performed. The first generated gas discharged from the ammonia remover (201) is re-supplied as the pressurized gas of the ammonia remover (201). By supplying the pressurized gas, the pressure inside the adsorption tower can be pressurized from about 4 barG to about 7.5 barG for about 390 seconds.

[0072] After the pressure accumulation process is completed, the adsorption process is performed. The mixed gas is supplied from the ammonia decomposition reactor (101), and ammonia is adsorbed and removed. The adsorption time of the ammonia remover (201) may be 360 ​​to 480 seconds, and the adsorption pressure may be 7 to 8 barG. When the adsorption time is 360 to 480 seconds, there is an advantage of being able to maintain the ammonia removal rate. When the adsorption time exceeds 480 seconds, there is a problem of a decrease in the ammonia removal rate because the adsorption tower can no longer adsorb ammonia and it is discharged. When the adsorption pressure is 7 to 8 barG, there is an advantage of being able to maximize the ammonia removal rate. When the adsorption pressure is less than 7 barG, there is a problem of not being able to remove ammonia and discharging it because the adsorption amount that the adsorbent can adsorb ammonia is reduced due to impurities.

[0073] After the adsorption process is completed, a secondary pressure equalization process is performed. The valves of the adsorption tower that underwent the adsorption process and the adsorption tower that underwent the first pressure equalization process are opened to match the pressure of the adsorption tower that underwent the adsorption process with that of the adsorption tower that underwent the first pressure equalization process. The secondary pressure equalization process can take approximately 30 seconds. The pressure of the adsorption towers that underwent the second pressure equalization process can reach approximately 4 barG.

[0074] Afterwards, the adsorption tower has a resting phase. The resting phase can last for approximately 360 seconds.

[0075] After the resting phase is completed, the first pressure equalization process is performed. The valves of the adsorption towers that have undergone the resting phase and the adsorption towers that have undergone the desorption process are opened to match the pressure of the adsorption towers that have undergone the resting phase with the pressure of the adsorption towers that have undergone the desorption process. The pressure of the adsorption towers that have undergone the first pressure equalization process can be approximately 1 barG. The first pressure equalization process can last approximately 30 seconds.

[0076] Afterwards, a depressurization process is performed. This process adjusts the pressure of the adsorption tower to 0 barG in preparation for the desorption process. The depressurization process can last approximately 30 seconds.

[0077] Next, the desorption process is performed. With the valve at the top of the adsorption tower closed, the pressure is reduced using a vacuum pump. As the pressure in the adsorption tower decreases, the weakly physically bound adsorbate within the adsorbent is removed. During the desorption process, the pressure in the adsorption tower is reduced to approximately -0.9 barG, allowing the adsorbate to be removed.

[0078] Fig. 4 is a drawing schematically showing the process of a nitrogen remover (301) according to one embodiment of the present invention. The nitrogen remover (301) according to one embodiment removes nitrogen gas contained in a first product gas and discharges a second product gas containing hydrogen and a second tail gas. A portion of the second product gas discharged from the nitrogen remover (301) can be resupplied to the nitrogen remover (301) as a cleaning gas and a pressurized gas, and the remaining portion of the second product gas can be recovered.

[0079] When the second generated gas discharged from the nitrogen remover (301) is supplied to the nitrogen remover (301) as a cleaning gas and a pressurized gas, purity stability in the nitrogen remover (301) can be secured.

[0080] The second product gas containing hydrogen gas recovered from the nitrogen remover (301) can also be used as hydrogen energy, etc. The second product gas storage tank (302) can store the recovered second product gas.

[0081] A portion of the second generation gas stored in the second generation gas storage tank (302) can be supplied to the nitrogen remover (301) as a cleaning gas and a pressurized gas.

[0082] A portion of the second generation gas stored in the second generation gas storage tank (302) can be supplied to a place that requires it, and can be used, for example, in fuel cells, petrochemical processes, ammonia synthesis, iron and steel processes, etc.

[0083] The second tail gas discharged from the above nitrogen remover (301) can be re-supplied as a cleaning gas to the above ammonia remover (201).

[0084] The second product gas may contain more than 99% by volume of hydrogen.

[0085] The second tail gas may contain 25 to 30 volume percent hydrogen, 70 to 75 volume percent nitrogen, and 0.5 to 1 ppm ammonia.

[0086] The second tail gas containing nitrogen gas removed from the nitrogen remover (301) can be used for cleaning the ammonia remover (201). When the second tail gas is re-supplied as a cleaning gas to the ammonia remover (201), the amount of hydrogen discarded during the hydrogen production process is reduced by reusing the second tail gas instead of discarding it, thereby improving the recovery rate of the hydrogen production process.

[0087] By linking ammonia removal and nitrogen removal processes, the recovery rate and purity of hydrogen produced can be increased. Furthermore, by reusing raw materials, wasteful exhaust gases can be minimized, preventing environmental pollution during hydrogen production.

[0088] The nitrogen remover (301) may include a plurality of adsorption towers. The nitrogen remover (301) may include an adsorbent, which is a material that selectively adsorbs nitrogen. The adsorbent is not particularly limited as long as it is a material that selectively adsorbs nitrogen, but may be at least one selected from the group consisting of CMS, zeolite, MOF, COF, activated carbon, alumina, silica, and the like.

[0089] The above nitrogen remover (301) may include a second tail gas storage tank (303) for storing second tail gas discharged from the nitrogen remover (301) and a second production gas storage tank (302) for storing second production gas.

[0090] The nitrogen remover (301) can undergo the processes of equalizing pressure, accumulating pressure, adsorption, depressurizing, and desorption. Figure 6 shows the internal pressure change of one adsorption tower of the ammonia remover and the nitrogen remover.

[0091] The nitrogen remover (301) may include multiple adsorption towers. In this case, each adsorption tower operates simultaneously and in conjunction. Table 3 shows the cycles of four adsorption towers according to an exemplary embodiment. Here, one cycle takes 20 minutes. The cycles of the adsorption towers according to the exemplary embodiment below are merely illustrative of the present invention and do not limit the scope of the appended claims. It will be apparent to those skilled in the art that various changes and modifications are possible within the scope and technical idea of ​​the present invention.

[0092] SEQ step123456789101112Time (sec)3024030302403030240303024030BED 1ADSEQ2RESTEQ1BDPGEQ1EQ2PRPRBED 2BDPGEQ1EQ2PRPRADSEQ2RESTEQ1BED 3EQ2PRPRADSEQ2RESTEQ1BDPGEQ1BED 4EQ2RESTEQ1BDPGEQ1EQ2PRRADS

[0093] Each symbol is the same as that shown in Table 2 above.

[0094] The equalization process is the same as that described in the ammonia remover (201) above.

[0095] After the first and second equalization processes are completed, a pressurization process is performed. The second generated gas discharged from the nitrogen remover (301) is re-supplied as the pressurized gas of the nitrogen remover (301). By supplying the pressurized gas, the pressure inside the adsorption tower can be pressurized from about 4 barG to about 7.5 barG for about 270 seconds.

[0096] After the pressure accumulation process is completed, the adsorption process is performed. The first generated gas is supplied from the ammonia remover (201), and nitrogen is adsorbed and removed. The adsorption time of the nitrogen remover (301) may be 240 to 360 seconds, and the adsorption pressure may be 7 to 8 barG. The maximum adsorption amount that the adsorbent can adsorb ammonia and the maximum adsorption power that can adsorb nitrogen are different. Nitrogen undergoes the adsorption process for a relatively shorter time than ammonia.

[0097] When the adsorption time is 240 to 360 seconds, there is an advantage in maintaining the nitrogen removal rate. When the adsorption time exceeds 360 seconds, there is a problem in that the nitrogen removal rate is reduced because the adsorption tower can no longer adsorb nitrogen and it is discharged. When the adsorption pressure is 7 to 8 barG, there is an advantage in maximizing the nitrogen removal rate. When the adsorption pressure is less than 7 barG, there is a problem in that the nitrogen cannot be removed and is discharged because the adsorption amount that the adsorbent can adsorb is reduced due to impurities.

[0098] The adsorption pressure of the nitrogen remover (301) may be lower than the adsorption pressure of the ammonia remover (201). The differential pressure (0.1 barG) between the ammonia remover (201) and the nitrogen remover (301) may be used as the driving force for the gas. In this case, the gas can be transferred to the nitrogen remover even without a separate gas transfer device in the ammonia remover (301).

[0099] After the adsorption process is completed, a secondary pressure equalization process, a rest stage, a depressurization process, and a desorption process are performed, and each process is the same as that described in the ammonia remover (201).

[0100] Example

[0101] Below, the present invention is further described with reference to specific experimental examples. The embodiments of the present invention are not limited to these examples, and high-purity hydrogen can be secured by changing operating conditions and can respond to fluctuations in ammonia decomposition rates.

[0102] Ammonia was introduced into an ammonia decomposition reactor to obtain a mixed gas containing hydrogen, nitrogen, and unreacted ammonia. An ammonia remover including four adsorption towers and a nitrogen remover including four adsorption towers were used.

[0103] In the ammonia remover, the mixed gas was fed at 20 SLPM into the adsorption tower of the ammonia remover, which went through a primary equalization process for 30 seconds, pressure equalization at 1 barG, a secondary equalization process for 30 seconds, pressure equalization at 4 barG, and then a pressurization process at 7.5 barG for 390 seconds. CMS was used as the adsorbent. After that, the adsorption process was performed at 7.5 barG for 420 seconds, and the first product gas containing hydrogen and nitrogen and the first tail gas were discharged. Thereafter, the first product gas was supplied to the first product gas storage tank, and the first tail gas was supplied to the first tail gas storage tank and stored. Thereafter, the adsorption tower went through a secondary equalization process for 30 seconds, pressure equalization at 4 barG, and had a rest period of 360 seconds. After that, the adsorption tower went through a primary pressure equalization process for 30 seconds, pressure equalization at 1 barG, a depressurization process was performed for 30 seconds to reduce the pressure of the adsorption tower to 0 barG, and a desorption process was performed to remove the adsorbate by reducing the pressure of the adsorption tower to -0.9 barG for 360 seconds. The desorption flow rate of the desorption process was 1.3 SLPM.

[0104] After that, in the nitrogen remover, the first product gas stored in the first product gas storage tank was fed into the adsorption tower of the nitrogen remover, which went through the first equalization process for 30 seconds, equalizing the pressure at 1 barG, the second equalization process for 30 seconds, equalizing the pressure at 4 barG, and then the accumulating process at 7.5 barG for 270 seconds. CMS was used as the adsorbent. After that, the adsorption process was performed at 7.4 barG for 300 seconds, removing the nitrogen contained in the first product gas, and discharging the second product gas containing hydrogen and the second tail gas. The adsorption pressure of the ammonia remover was 7.5 barG, and the adsorption pressure of the nitrogen remover was 7.4 barG, so that the differential pressure (0.1 barG) between the two processes was used as the driving force for the gases. The second product gas was supplied to the second product gas storage tank, and the second tail gas was supplied to the second tail gas storage tank and stored. Thereafter, the adsorption tower underwent a second pressure equalization process for 30 seconds, pressure equalization to 4 barG, and a rest period of 240 seconds. Thereafter, the adsorption tower underwent a first pressure equalization process for 30 seconds, pressure equalization to 1 barG, a depressurization process for 30 seconds, pressure reduction of the adsorption tower to 0 barG, and a desorption process to remove the adsorbate by reducing the pressure of the adsorption tower to -0.9 barG for 240 seconds. The desorption flow rate of the desorption process was 1.0 SLPM.

[0105] One cycle of repeating the above sequence 3 times was repeated 10 times.

[0106] From the second cycle onwards, the first tail gas stored in the first tail gas storage tank is re-supplied as combustion gas for removing unreacted ammonia from the ammonia decomposition reactor, the first product gas stored in the first product gas storage tank is re-supplied as accumulator gas to the ammonia remover, the second tail gas stored in the second tail gas storage tank is re-supplied as cleaning gas to the ammonia remover, and the second product gas stored in the second product gas storage tank is re-supplied as cleaning gas and accumulator gas to the nitrogen remover.

[0107] The operating conditions of the ammonia remover and nitrogen remover are shown in Table 4.

[0108] Classification Ammonia Remover Nitrogen Remover Adsorption Time (sec) 420300 Adsorption Pressure (barG) 7.57.4 Average Desorption Pressure (barG) -0.9-0.85 Injection Gas Flow Rate (SLPM) 2018.9 Purge Flow Rate (SLPM) 1.31.0

[0109] While the process was in progress, the concentration of ammonia contained in the first generated gas and the concentration of ammonia contained in the second generated gas were measured, and the results are shown in Fig. 7.

[0110] The concentrations of ammonia in the first product gas, second tail gas, and second product gas were measured using a Fourier transform infrared spectroscopy (FT-IR) device of the IGS analyzer model from Antaris. The peaks of functional groups corresponding to ammonia concentration were identified, and a concentration calibration curve was created for the identified peaks to analyze the ammonia concentration.

[0111] The concentration of hydrogen in the secondary product gas was analyzed by gas chromatography using Agilent's Model 8890GC. Because high-purity hydrogen cannot be directly measured, impurities N2 and NH3 were analyzed and relative integration was used to calculate the hydrogen concentration.

[0112] The concentrations of each component in the first tail gas, as well as the nitrogen and hydrogen concentrations in the first product gas and second tail gas, were analyzed using the HPR-20 R&D model from Hiden Analytical. This analytical method uses quadrupole mass spectrometry, which detects specific ions when substances with different voltages reach the detector. This allowed for the development of calibration curves for each substance and subsequent analysis.

[0113] The ammonia concentration in the first product gas after the ammonia remover was confirmed to be significantly low at approximately 0.3 ppm. The ammonia concentration in the second product gas after the nitrogen remover was confirmed to be around 0.04 ppm, demonstrating the ability to obtain high-purity hydrogen containing almost no ammonia.

[0114] After 10 cycles, the compositions of the first tail gas, the first product gas, the second tail gas, and the second product gas are shown in Table 5.

[0115] Gas1 Tail Gas1 Production Gas2 Tail Gas2 Production GasN242Volume%25Volume%71Volume%20ppmH244Volume%75Volume%29Volume%99Volume%NH314Volume%0.3ppm0.6ppm0.04ppm

[0116] The hydrogen concentration of the second generated gas was measured while the process was in progress, and the results are shown in Fig. 8. By linking the processes of the ammonia remover and the nitrogen remover, it was confirmed that high-purity hydrogen of 99.99% by volume or more could be continuously produced.

[0117] The hydrogen recovery rate was calculated using the following formula.

[0118] Hydrogen recovery rate = (H2 production amount - nitrogen removal unit pressure amount - nitrogen removal unit cleaning amount) / H2 injection amount in the connected process

[0119] As a result, it was confirmed that a remarkably high hydrogen recovery rate of 87.9% could be achieved.

[0120] Description of the symbol

[0121] 101: Ammonia Decomposition Reactor

[0122] 102: Reaction section

[0123] 103: Combustion section

[0124] 104: Liquid ammonia tank

[0125] 105: Air blower

[0126] 201: Ammonia remover

[0127] 202: First generation gas storage tank

[0128] 203: First tail gas storage tank

[0129] 301: Nitrogen Remover

[0130] 302: Second generation gas storage tank

[0131] 303: Second tail gas storage tank

Claims

1. An ammonia decomposition reactor that decomposes ammonia to emit a mixed gas containing hydrogen, nitrogen, and unreacted ammonia; An ammonia remover that receives the above mixed gas, adsorbs and removes unreacted ammonia contained in the mixed gas, and discharges a first product gas and a first tail gas; and It includes a nitrogen remover that receives the first generation gas, removes nitrogen contained in the first generation gas, and discharges the second generation gas and the second tail gas. A hydrogen production device in which the second generated gas discharged from the above nitrogen remover is resupplied to the nitrogen remover as a cleaning gas and a pressurized gas.

2. In paragraph 1, The first tail gas discharged from the above ammonia remover is re-supplied to the ammonia decomposition reactor as combustion gas for removing unreacted ammonia. The first generated gas discharged from the ammonia remover is resupplied to the ammonia remover as a pressurized gas, A hydrogen production device in which the second tail gas discharged from the above nitrogen remover is re-supplied as a cleaning gas to the above ammonia remover.

3. In paragraph 1, A hydrogen production device, wherein the first generated gas contains 75 to 80 volume% of hydrogen and 20 to 25 volume% of nitrogen.

4. In paragraph 1, A hydrogen production device, wherein the first tail gas contains 10 to 20 vol% of hydrogen, 40 to 45 vol% of nitrogen, and 40 to 45 vol% of ammonia.

5. In paragraph 3, A hydrogen production device, wherein the first generated gas contains 0.3 to 1 ppm of ammonia.

6. In paragraph 1, A hydrogen production device, wherein the second generated gas contains 99% or more of hydrogen by volume.

7. In paragraph 1, A hydrogen production device, wherein the second tail gas contains 25 to 30 volume% of hydrogen and 70 to 75 volume% of nitrogen.

8. In paragraph 7, A hydrogen production device, wherein the second tail gas contains 0.5 to 1 ppm of ammonia.

9. In paragraph 1, A hydrogen production device, wherein the ammonia remover and the nitrogen remover include CMS (Carbon Molecular Sieve), zeolite, MOF (Metal-organic framework) or COF (Covalent organic frameworks) as an adsorbent.

10. In paragraph 1, A hydrogen production device, wherein the adsorption time in the above ammonia remover is 360 to 480 seconds and the adsorption pressure is 7 to 8 barG.

11. In paragraph 1, A hydrogen production device, wherein the adsorption time in the above nitrogen remover is 240 to 360 seconds and the adsorption pressure is 7 to 8 barG.

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