Pressure swing adsorption apparatus for refining high purity hydrogen from ammonia decomposition and hydrogen refining method using the same

Abstract

The present invention relates to a pressure swing adsorption apparatus for purifying high purity hydrogen from ammonia decomposition and a hydrogen purification method using the same. More specifically, by forming a structure in which different adsorbents are filled in each of a number of adsorption towers including a guard bed section and a hydrogen purification section, high purity hydrogen can be purified from a hydrogen mixed gas generated after ammonia decomposition, the adsorbent for removing ammonia can be easily replaced, the possibility of a rapid shortening of the life of the adsorbent in the hydrogen purification section due to a trace amount of ammonia can be minimized, and hydrogen can be efficiently recovered from the guard bed section. Therefore, compared to the existing pressure swing adsorption process composed of a pretreatment section and a hydrogen purification section, it is advantageous in that it is possible to maximize the hydrogen recovery rate and to deal with large changes in the ammonia concentration in the raw material.

Description

[Technical field]

[0001] The present invention relates to a pressure swing adsorption apparatus for purifying high-purity hydrogen from ammonia decomposition and a hydrogen purification method using the same, and more particularly to a pressure swing adsorption apparatus for purifying high-purity hydrogen from ammonia decomposition and a hydrogen purification method using the same, which uses a pressure swing adsorption apparatus equipped with a number of adsorption towers including a guard bed section and a hydrogen purification section to improve physical adsorption selectivity for impurities such as nitrogen (N2), ammonia (NH3), and moisture (H2O) in a mixed gas containing hydrogen gas, and reduce the amounts of these components to trace amounts or less to produce a high-purity hydrogen product. [Background technology]

[0002] In recent years, the development of ammonia-based hydrogen storage, transportation, extraction and utilization technologies has attracted much attention in order to achieve the carbon neutral goal. When importing clean ammonia from overseas, ammonia decomposition technology is required to supply hydrogen domestically, and the by-products generated after ammonia decomposition include nitrogen (N2), ammonia (NH3) and moisture (H2O) in addition to hydrogen. Therefore, in order to produce high-purity hydrogen, it is necessary to remove nitrogen, moisture and ammonia. To purify ammonia decomposition hydrogen, moisture, ammonia and nitrogen are generally removed in that order, and different adsorbents can be used for each.

[0003] Ammonia is mainly removed by adsorption through chemical bonding with the acidic groups of the adsorbent, and the temperature swing adsorption purification method is used to regenerate the adsorbent used at high temperatures.The pressure swing adsorption purification method is only possible by physical adsorption due to the intermolecular attraction between the impurity and the adsorbate.

[0004] Currently, a method for producing high-purity hydrogen using ammonia has not yet been commercialized, and a technology that combines a Temperature Swing Adsorption (TSA) process to remove undecomposed ammonia and a Pressure Swing Adsorption process to remove nitrogen has been developed as a method for separating only high-purity hydrogen from ammonia decomposition gas.

[0005] However, since existing commonly used ammonia adsorbents chemically adsorb ammonia through an acid-base reaction, they can only adsorb and desorb ammonia through a temperature swing adsorption process, while an adsorbent capable of physical adsorption is required for use in a pressure swing adsorption process.In addition, existing pressure swing adsorption hydrogen purification processes for producing high-purity hydrogen selectively remove CO, CH4, and CO2 from a gas mixture containing H2, CO2, CH4, CO, etc., and focus only on downsizing the equipment and improving hydrogen recovery rate.

[0006] The existing U.S. Patent No. 3,986,849 discloses a process for removing CO2 and N2 contained in hydrogen, in which eight or more adsorption towers are used, raw gas is treated simultaneously in two or more adsorption towers, and three or more stages of pressure equalization are applied.

[0007] In addition, U.S. Patent No. 5,250,088 discloses a pressure swing adsorption process using three or more adsorption towers to remove moisture and hydrocarbons contained in hydrogen, and also discloses a method of increasing the efficiency of the separation process by further including a tank for storing a purge gas.

[0008] However, in these existing patent documents, although the efficiency of the separation process can be increased by using multiple adsorption towers, when the hydrogen purification device for ammonia decomposition hydrogen is not operated, the already adsorbed ammonia component may be desorbed before operation, contaminating the adsorbent for nitrogen separation, resulting in a problem of shortening the life of the adsorbent. Also, since the life of the adsorbent for ammonia separation is shorter than that of the adsorbent for nitrogen separation, when the existing adsorbents are used in a stacked manner, there is a problem that all the adsorbents must be replaced.

[0009] Therefore, research is needed into a new separation process that can selectively adsorb moisture, ammonia, and nitrogen from the hydrogen gas mixture during the ammonia decomposition process to produce high-purity hydrogen while minimizing the shortening of the adsorbent's lifespan due to impurities such as trace amounts of ammonia. [Prior art documents] [Patent documents]

[0010] [Patent Document 1] U.S. Patent No. 3,986,849 [Patent Document 2] U.S. Patent No. 5,250,088 Summary of the Invention [Problem to be solved by the invention]

[0011] In order to solve the above problems, an object of the present invention is to provide a pressure swing adsorption device for purifying hydrogen from ammonia decomposition by forming a structure in which different adsorbents are filled in each of a number of adsorption towers including a guard bed section and a hydrogen purification section.

[0012] Another object of the present invention is to provide a method for purifying hydrogen using a pressure swing adsorption device, which is capable of purifying high purity hydrogen by improving the selective adsorption of moisture, ammonia and nitrogen in a hydrogen gas mixture, and maximizes hydrogen recovery rate and productivity. [Means for solving the problem]

[0013] The present invention provides a pressure swing adsorption device for purifying hydrogen from ammonia decomposition, comprising a number of adsorption towers connected to a raw material supply pipe, the adsorption towers including a guard bed section and a hydrogen purification section, a vacuum pump connected to the adsorption towers and maintaining the adsorption towers in a vacuum state, and a number of valves for opening and closing a number of tubes connected to the adsorption towers and the vacuum pump, wherein the guard bed section is located at a lower end of the hydrogen purification section, and the adsorption towers in the guard bed section are filled with a first adsorbent and a second adsorbent in a multi-layer structure that selectively adsorb and remove moisture and ammonia contained in a hydrogen mixed gas produced after ammonia decomposition supplied through the raw material supply pipe, and the hydrogen purification section is located at an upper end of the guard bed section, and the adsorption towers in the hydrogen purification section are filled with a third adsorbent that selectively adsorbs and removes nitrogen contained in the hydrogen mixed gas from which moisture and ammonia have been removed in the guard bed section.

[0014] The present invention also provides a method for purifying hydrogen using the pressure swing adsorption apparatus of claim 1, comprising a number of adsorption towers connected to a raw material supply pipe and including a guard bed section and a hydrogen purification section, a vacuum pump connected to the adsorption towers and maintaining the adsorption towers in a vacuum state, and a number of valves for opening and closing a number of pipes connected to the adsorption towers and the vacuum pump, the method comprising the steps of: supplying a hydrogen mixed gas produced after ammonia decomposition through a raw material supply pipe into the adsorption towers in the guard bed section; a step of selectively adsorbing and removing ammonia by passing the hydrogen mixed gas from which moisture has been removed through a second adsorbent filled in an upper layer of an adsorption tower in the guard bed section to selectively adsorb and remove ammonia; a step of supplying the hydrogen mixed gas from which moisture and ammonia have been removed into an adsorption tower of a hydrogen purification unit; and a step of passing the supplied hydrogen mixed gas from which moisture and ammonia have been removed through a third adsorbent filled in an adsorption tower in the hydrogen purification unit to selectively adsorb and remove nitrogen, thereby obtaining purified hydrogen. Effect of the Invention

[0015] The pressure swing adsorption device according to the present invention has a structure in which different adsorbents are filled in each of a number of adsorption towers, including a guard bed section and a hydrogen purification section, so that high-purity hydrogen can be produced from a hydrogen mixed gas produced after ammonia decomposition, the adsorbent for removing ammonia can be easily replaced, and the possibility of a rapid shortening of the life of the adsorbent in the hydrogen purification section due to trace amounts of ammonia can be minimized.

[0016] In addition, since the pressure swing adsorption device of the present invention can efficiently recover hydrogen from the guard bed section, it has the advantage of being able to maximize the hydrogen recovery rate and handle large changes in the ammonia concentration in the raw material compared to existing pressure swing adsorption processes composed of a pretreatment section and a hydrogen purification section. Furthermore, when the operation of the device is stopped for a while or left for an extended period of time, the remaining gas in the guard bed section is blocked from flowing into the hydrogen purification section, thereby preventing contamination of the adsorbent filled in the hydrogen purification section and maintaining separation performance.

[0017] In addition, the hydrogen purification method using the pressure swing adsorption device of the present invention is capable of purifying high purity hydrogen by physically adsorbing impurities such as moisture (H2O), ammonia (NH3) and nitrogen (N2) contained in the hydrogen mixed gas generated after ammonia decomposition so that the impurities are reduced to trace amounts or less, and the selective adsorption of moisture, ammonia and nitrogen is improved to maximize the hydrogen recovery rate and productivity. Furthermore, the initial investment cost is low, and when only the pressure swing adsorption process is applied, a separate temperature swing adsorption process is not required and a heat source for regeneration is not required, thereby reducing the operating cost.

[0018] The effects of the present invention are not limited to those mentioned above, and should be understood to include all effects that can be inferred from the following description. [Brief description of the drawings]

[0019] [Figure 1]FIG. 1 is a schematic diagram of a five-column pressure swing adsorption apparatus including a guard bed section and a hydrogen purification section according to the present invention. [Diagram 2] FIG. 1 is a configuration diagram of a pressure swing adsorption apparatus including a six-tower guard bed section and a hydrogen purification section according to the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0020] The invention will now be explained in more detail with reference to an embodiment.

[0021] The present invention relates to a pressure swing adsorption device capable of removing moisture, ammonia, and nitrogen from a hydrogen mixed gas produced by ammonia decomposition to produce high-purity hydrogen, and a hydrogen purification method using the same.

[0022] As described above, in the existing pressure swing adsorption process for ammonia decomposition hydrogen, when moisture, ammonia, and nitrogen are removed in that order, if ammonia is adsorbed on the nitrogen separation adsorbent, the nitrogen separation adsorbent loses its adsorption capacity, so ammonia must never be transferred to the nitrogen adsorbent. In addition, when the hydrogen purification device for ammonia decomposition hydrogen is not operated, the already adsorbed ammonia component may be desorbed before operation and contaminate the nitrogen separation adsorbent, resulting in a problem of shortening the life of the adsorbent. In addition, since the life of the ammonia separation adsorbent is shorter than the life of the nitrogen separation adsorbent, there is a problem that all the adsorbents must be replaced when existing adsorbents are used in layers.

[0023] Therefore, the present invention provides a pressure swing adsorption device having a structure in which different adsorbents are filled in each of a number of adsorption towers, including a guard bed section for separating moisture and ammonia and a hydrogen purification section for separating nitrogen, thereby making it possible to purify high-purity hydrogen from a hydrogen mixed gas generated after ammonia decomposition, easily replace the adsorbent for removing ammonia, and minimize the possibility of a rapid shortening of the life of the adsorbent in the hydrogen purification section due to trace amounts of ammonia.

[0024] In addition, since hydrogen can be efficiently recovered from the guard bed section, the hydrogen recovery rate can be maximized compared to the existing pressure swing adsorption process, and there is an advantage in that it can handle large changes in the ammonia concentration in the raw material. Furthermore, when the operation of the device is stopped for a while or left for an extended period of time, the remaining gas in the guard bed section is blocked from flowing into the hydrogen purification section, thereby preventing contamination of the adsorbent filled in the hydrogen purification section and maintaining separation performance.

[0025] (a) Configuration of Pressure Swing Adsorption Device 100 Specifically, the present invention provides a pressure swing adsorption apparatus 100 for purifying hydrogen from ammonia decomposition, the pressure swing adsorption apparatus 100 comprising a number of adsorption towers, each of which is connected to a raw material supply pipe 101 and includes a guard bed section and a hydrogen purification section; a vacuum pump 131, connected to the adsorption towers and configured to maintain the adsorption towers in a vacuum state; and a number of valves for opening and closing the number of tubes connected to the adsorption towers and the vacuum pump 131. The guard bed section is located at the lower end of the hydrogen purification section, and the adsorption towers in the guard bed section are filled with a first adsorbent and a second adsorbent in a multi-layer structure, which selectively adsorb and remove moisture and ammonia contained in a hydrogen mixed gas generated after ammonia decomposition supplied through the raw material supply pipe 101. The hydrogen purification sections 111 to 116 are located at the upper end of the guard bed section, and the adsorption towers in the hydrogen purification section are filled with a third adsorbent which selectively adsorbs and removes nitrogen contained in the hydrogen mixed gas from which moisture and ammonia have been removed in the guard bed section.

[0026] The pressure swing adsorption (PSA) device does not remove impurities such as carbon monoxide (CO), methane (CH4), and carbon dioxide (CO2) as in a typical hydrogen purification process, but improves the physical adsorption selectivity for impurities such as moisture (H2O), undecomposed ammonia (NH3), and nitrogen (N2) generated in the ammonia decomposition process, thereby reducing these components to trace amounts or less to produce high-purity hydrogen. The pressure swing adsorption device 100 may preferably be a vacuum pressure swing adsorption (VPSA) device.

[0027] In the case of the existing four-tower pressure swing adsorption apparatus, two or more kinds of adsorbents are stacked in one adsorption tower to simultaneously adsorb moisture, ammonia, and nitrogen from the hydrogen mixed gas and then purify it, but when undecomposed ammonia comes into contact with the adsorbent that adsorbs nitrogen, the performance of the adsorbent decreases and the lifespan is shortened. In addition, the pressure swing adsorption apparatus can be configured with a pre-treatment section in which two or more adsorption towers are arranged in parallel and a hydrogen purification section in which four or more adsorption towers are arranged in parallel, but it is difficult to recover hydrogen in the adsorption towers of the pre-treatment section, so there is a limit to increasing the hydrogen recovery rate, and since vacuum pumps are required for each of the pre-treatment section and the hydrogen purification section, the power consumption is higher than that of the above apparatus. The configuration of the above adsorption process does not easily respond to changes in the ammonia concentration in the raw material, and when the adsorbent is replaced, all the stacked adsorbents must be replaced, so there are problems with increased investment and operating costs.

[0028] The present invention comprises a number of adsorption towers including a guard bed section that first adsorbs and removes moisture and ammonia, and a hydrogen purification section that adsorbs and purifies nitrogen. This solves the problems of performance degradation and shortened lifespan of the adsorbent that adsorbs nitrogen, and reduces investment and operating costs.

[0029] The guard bed section and the hydrogen purification section may be configured as separate systems, and the process operation steps may be configured to operate in conjunction with each other.

[0030] The guard bed section and the hydrogen purification section are connected in series with each other, and two or more, preferably four or more, more preferably five or six adsorption tower sets each composed of the guard bed section and the hydrogen purification section connected in series can be arranged in parallel. Each adsorption tower set passes the hydrogen mixed gas supplied through the raw material supply pipe 101 first through the guard bed section and then through the hydrogen purification section, thereby adsorbing moisture and ammonia in order through the steps of adsorption, depressurization, washing, raw material pressure accumulation, and product pressure accumulation, thereby purifying high purity hydrogen.

[0031] The minimum pressure of the adsorption tower in the guard bed section can be maintained at 1 / 4 or less, preferably 1 / 3 to 2 / 5, of the raw material supply pressure when the hydrogen mixed gas flows in the raw material flow direction (cocurrent direction). If the minimum pressure is lower than 1 / 4 or less, a problem may occur in which the ammonia component in the guard bed section flows into the hydrogen purification section.

[0032] The lower layer of the adsorption tower in the guard bed section is filled with a first adsorbent, and the upper layer is filled with a second adsorbent. Therefore, when the hydrogen mixed gas is supplied from the raw material supply pipe 101, moisture and ammonia can be selectively adsorbed while passing through the lower and upper layers of the adsorption tower in sequence.

[0033] The first adsorbent is filled in the lower layer of the adsorption tower of the guard bed section and is at least one type selected from the group consisting of first activated alumina, silica gel, alumina silica gel, and zeolite capable of removing moisture, and is preferably the first activated alumina or silica gel.

[0034] The first adsorbent may be contained in an amount of 1 to 70% by weight, preferably 1 to 60% by weight, and most preferably 1 to 50% by weight, based on the second adsorbent. If the content of the first adsorbent is less than 1% by weight, moisture may not be sufficiently removed, whereas if it exceeds 70% by weight, it may not be easy to deal with changes in ammonia concentration.

[0035] The second adsorbent is filled in the upper layer of the adsorption tower of the guard bed section and is at least one type selected from the group consisting of metal-impregnated activated carbon, silica gel, alumina silica gel, zeolite, and second activated alumina, and is preferably metal-impregnated activated carbon, silica gel, or zeolite.

[0036] The metal-impregnated activated carbon is characterized by having excellent ammonia selectivity and a high ammonia adsorption amount. The metal-impregnated activated carbon is activated carbon impregnated with one or more metals selected from the group consisting of Mg, Ca, Mn, and Cu, and is preferably magnesium (Mg)-impregnated activated carbon or calcium (Ca)-impregnated activated carbon, and is most preferably magnesium (Mg)-impregnated activated carbon. The magnesium-impregnated activated carbon has a very excellent ammonia adsorption performance compared to other metal-impregnated activated carbons, and has the advantage of adsorbing a large amount of ammonia even with a small amount of impregnation.

[0037] The amount of metal impregnated in the metal-impregnated activated carbon may be 1 to 10% by weight, preferably 1 to 8% by weight, and most preferably 1 to 6% by weight. If the amount of metal impregnated is less than 1% by weight, the ammonia adsorption performance may not reach the expected value, whereas if the amount of metal impregnated is more than 10% by weight, the regeneration time of the adsorbent increases, making it difficult to configure the pressure fluctuation step, and it may become difficult to adsorb ammonia in a very small amount of 0.1 ppm or less.

[0038] The silica gel, zeolite and second activated alumina also have excellent ammonia selectivity and fast ammonia adsorption rate, so they can be used to remove extremely small amounts of ammonia in the pressure swing adsorption process.

[0039] The second adsorbent may be contained in an amount of 30 to 99% by weight, preferably 3 to 60% by weight, and most preferably 12 to 50% by weight, based on the first adsorbent. If the content of the second adsorbent is less than 30% by weight, the amount of ammonia adsorbed may decrease, whereas if the content exceeds 99% by weight, it is difficult to easily deal with changes in water concentration.

[0040] The hydrogen purification unit has a structure in which two or more, preferably four or more, and more preferably five or six or more adsorption towers are arranged in parallel. The hydrogen purification unit passes a hydrogen mixed gas in which moisture and ammonia have been purified as it passes through the guard bed unit, and performs the processes of adsorption, primary pressure equalization, cleaning, secondary pressure equalization, depressurization, cleaning and pressure accumulation in conjunction with the guard bed unit to adsorb and remove nitrogen, thereby obtaining a high hydrogen recovery rate and high purity hydrogen.

[0041] The hydrogen purification unit has an adsorption tower filled with a third adsorbent, and can selectively adsorb nitrogen contained in the hydrogen mixed gas from which moisture and ammonia have been purified to produce high-purity hydrogen.

[0042] The third adsorbent may be one or more selected from the group consisting of zeolite NaA, zeolite CaA, zeolite CaNaA, zeolite LiX, zeolite LiNaX, zeolite LiCaX, zeolite LiNaCaX, zeolite NaX, zeolite CaX, zeolite CaNaX and zeolite KX, preferably zeolite LiX, zeolite CaX or a mixture thereof, and most preferably zeolite CaX.

[0043] The pressure swing adsorption system 100 may further include a hydrogen storage tank that collects purified hydrogen from the adsorption tower.

[0044] In particular, although not explicitly described in the following examples or comparative examples, in the pressure swing adsorption apparatus 100 according to the present invention, the hydrogen purification process was continuously carried out 100 times using the hydrogen mixed gas produced after ammonia decomposition while changing each of the following eight conditions:

[0045] As a result, unlike other conditions and other numerical ranges, when all of the following conditions are met, the purity of the refined hydrogen is 99.99% or more, and the hydrogen recovery rate is improved to 92.5% or more.

[0046] (1) the minimum pressure of the adsorption tower in the guard bed section is maintained so as not to be lower than 1 / 3 to 2 / 5 of the raw material supply pressure, (2) the first adsorbent is a first activated alumina or silica gel filled in a lower layer of the adsorption tower in the guard bed section and capable of removing moisture, (3) the first adsorbent is filled in an amount of 10 to 35% by weight relative to the second adsorbent in the adsorption tower in the guard bed section, (4) the second adsorbent is filled in an upper layer of the adsorption tower in the guard bed section and is a metal-impregnated activated carbon capable of removing ammonia, (5) the second adsorbent is filled in an amount of 65 to 90% by weight relative to the first adsorbent in the adsorption tower in the guard bed section, (6) the metal-impregnated activated carbon is magnesium (Mg)-impregnated activated carbon or calcium (Ca)-impregnated activated carbon, (7) the amount of metal impregnated in the metal-impregnated activated carbon is 1 to 8% by weight, and (8) the third adsorbent is zeolite LiX, zeolite CaX, or a mixture thereof.

[0047] However, if any one of the eight conditions above is not met, the recovery rate of the refined hydrogen will be low at 75% or less, and unadsorbed moisture, ammonia or nitrogen will be detected above the standard range, resulting in a low purity of the refined hydrogen at 86% or less.

[0048] 1 is a configuration diagram of a pressure swing adsorption apparatus 100 including a five-tower guard bed section and a hydrogen purification section according to the present invention. Referring to FIG. 1, the pressure swing adsorption apparatus 100 includes guard bed sections 121-125 connected to a raw material supply pipe 101 and a number of adsorption towers 111-115 including a hydrogen purification section, the guard bed sections 121-125 and the number of adsorption towers 111-115 are connected in series, a vacuum pump 131 connected to maintain each of the guard bed sections 121-125 in an individual vacuum state, and a number of valves for opening and closing a number of pipes 102-108 connecting the guard bed sections 121-125, the number of adsorption towers 111-115, and the vacuum pump 131.

[0049] In addition, the guard bed section 121-125 has five adsorption towers GB1, GB2, GB3, GB4, and GB5 arranged in parallel, and the hydrogen purification section has five adsorption towers 111-115 arranged in parallel. The adsorption towers of the guard bed section and the hydrogen purification section are connected in series, and an adsorption step, a first pressure equalization step, a second pressure equalization step, a providing purge step, a third pressure equalization step, a countercurrent blowdown step, a vacuum purge step, a first pressurization step, a second pressurization step, a third pressurization step, and a final pressurization step by product can be organically performed together as one cycle.

[0050] A raw material supply pipe 101, to which the hydrogen mixed gas is supplied, is connected to the lower end of the adsorption tower in the guard bed section 121-126 via a first raw material supply valve 11. Each of the adsorption towers in the guard bed section and the hydrogen purification section performs a cycle of a water, ammonia, and nitrogen adsorption stage contained in the hydrogen mixed gas supplied through the raw material supply pipe 101, a first pressure equalization stage, a second pressure equalization stage, a purge gas supply stage, a third pressure equalization stage, a countercurrent depressurization stage, a vacuum purge stage, a first pressure accumulation stage, a second pressure accumulation stage, a third pressure accumulation stage, and a product pressure accumulation stage, thereby purifying high purity hydrogen from the by-product generated after ammonia decomposition.

[0051] At the bottom of the adsorption tower in the guard bed section, there are located first to fifth raw material supply valves 11, 21, 31, 41, 51 to which the hydrogen mixed gas is supplied from the raw material supply pipe 101, and first to fifth counterflow pressure reducing valves 12, 22, 32, 42, 52 to adjust the pressure via the vacuum pump 131. In addition, at the top of the adsorption tower in the guard bed section, there are located first to fifth discharge valves 11-1, 21-1, 31-1, 41-1, 51-1 to discharge the hydrogen mixed gas from which moisture and ammonia have been removed.

[0052] The adsorption towers of the hydrogen purification unit are provided with first to fifth vacuum purge valves 16, 26, 36, 46, 56 at their upper parts, with first to sixth pressure equalizing valves 15, 25, 35, 45, 55 for pressure equalization at their upper parts connected to the vacuum purge valves, and with first to fifth pressure accumulating valves 14, 24, 34, 44, 54 for product pressure accumulation at their upper parts connected to the pressure equalizing valves. In addition, the adsorption towers of the hydrogen purification unit are provided with first to fifth product production valves 13, 23, 33, 43, 53 for transferring purified hydrogen at their uppermost parts, and with first to sixth counterflow pressure reducing valves 12-1, 22-1, 32-1, 42-1, 52-1 for adjusting the pressure of the adsorption towers at their lower parts.

[0053] The guard bed section and the hydrogen purification section can perform the desorption process by supplying cleaning gas during the vacuum purge step through the first to fifth counterflow pressure reducing valves 12 to 52 and 12-1 to 52-1. The main reason for providing separate counterflow pressure reducing valves for the guard bed section and the hydrogen purification section is to prevent ammonia from flowing back from the guard bed section to the hydrogen purification section due to a pressure difference.

[0054] The adsorption towers 121-126 in the guard bed section and the adsorption towers 111-116 in the hydrogen purification section are connected in series via a number of pipes 102-108 that interconnect the adsorption towers. Moisture and ammonia are removed in the guard bed section, and nitrogen is removed in the hydrogen purification section, thereby producing high-purity hydrogen, enabling a high hydrogen recovery rate and low-power operation.

[0055] 2 is a configuration diagram of a pressure swing adsorption apparatus 100-1 including a six-tower guard bed section and a hydrogen purification section according to the present invention. Referring to FIG. 2, the six-tower pressure swing adsorption apparatus 100-1 can increase the recovery rate more than the five-tower pressure swing adsorption apparatus 100, and the basic purification method is similar to the hydrogen purification method using the five-tower pressure swing adsorption apparatus described below, which is performed in this order: adsorption, pressure equalization, purge gas supply, pressure equalization, countercurrent depressurization, vacuum purge, pressure accumulation, and product pressure accumulation.

[0056] (b) A method for purifying hydrogen using a pressure swing adsorption apparatus including a guard bed section and a hydrogen purification section Meanwhile, the present invention relates to a method for purifying hydrogen using a pressure swing adsorption apparatus 100 according to the present invention, which comprises a number of adsorption towers connected to a raw material supply pipe 101 and including guard bed sections and hydrogen purification sections 111-116, a vacuum pump 131 connected to the adsorption towers and maintaining the adsorption towers in a vacuum state, and a number of valves for opening and closing a number of pipes connected to the adsorption towers and the vacuum pump 131. The method includes the steps of supplying a hydrogen mixed gas produced after ammonia decomposition into the adsorption towers in the guard bed section through the raw material supply pipe 101, and passing the supplied hydrogen mixed gas through a first adsorbent filled in the lower section of the adsorption towers in the guard bed section, thereby The present invention provides a hydrogen purification method using a pressure swing adsorption device, the method including the steps of: selectively adsorbing and removing moisture; selectively adsorbing and removing ammonia by passing the hydrogen mixed gas from which the moisture has been removed through a second adsorbent packed in an upper layer of an adsorption tower in the guard bed section; supplying the hydrogen mixed gas from which the moisture and ammonia have been removed into adsorption towers 111-116 of a hydrogen purification section; and selectively adsorbing and removing nitrogen by passing the supplied hydrogen mixed gas from which the moisture and ammonia have been removed through a third adsorbent packed in the adsorption towers 111-116 in the hydrogen purification section to obtain purified hydrogen.

[0057] The step of supplying the hydrogen mixed gas may be supplied to the hydrogen mixed gas discharged after removing moisture and ammonia components in one of the adsorption towers in the guard bed section. Here, the other adsorption tower in the guard bed section may perform a step of physically adsorbing and removing moisture and ammonia from the hydrogen mixed gas generated after ammonia decomposition by performing a process including a step of receiving gas at atmospheric pressure or higher from the hydrogen purification units 111-116 for cleaning after countercurrently reducing the pressure to below the adsorption operation pressure, a raw material pressure accumulation step, and a product pressure accumulation step.

[0058] The supplied hydrogen mixed gas may be purified after selectively adsorbing moisture when passing through the lower part of the adsorption tower in the guard bed section, and then selectively adsorbing ammonia when passing through the upper part in sequence. In particular, in the step of selectively adsorbing ammonia and then purifying the hydrogen mixed gas, the moisture may be adsorbed so that the ammonia content in the purified hydrogen mixed gas is less than 0.1 ppm, and then the hydrogen mixed gas may be purified.

[0059] According to an embodiment, the guard bed section includes first to fifth adsorption towers, each of which may sequentially perform an adsorption step, a first pressure equalization step, a second pressure equalization step, a purge gas providing step, a countercurrent depressurization step, a vacuum purge step, a first pressure accumulation step, a second pressure accumulation step, and a product pressure accumulation step in order to remove moisture and ammonia from the hydrogen mixed gas supplied from the raw material supply pipe 101, and the hydrogen purification section includes first to fifth adsorption towers 111-11, each of which may sequentially perform an adsorption step, a first pressure equalization step, a second pressure equalization step, a purge gas providing step, a countercurrent depressurization step, a vacuum purge step, a first pressure accumulation step, a second pressure accumulation step, and a product pressure accumulation step in order to remove nitrogen components from the hydrogen mixed gas from which moisture and ammonia have been removed, supplied from the guard bed section, and increase the purity and recovery rate of the hydrogen product.

[0060] Preferably, the guard bed section includes first to fifth adsorption towers, each of which can sequentially perform an adsorption stage, a first equalization stage, a second equalization stage, a purge gas providing stage, a countercurrent depressurization stage, a vacuum purge stage, a first pressure accumulating stage, a second pressure accumulating stage, a third pressure accumulating stage, and a product pressure accumulating stage; and the hydrogen purification section includes first to fifth adsorption towers 111 to 115, each of which can sequentially perform an adsorption stage, a first equalization stage, a second equalization stage, a purge gas providing stage, a third pressure accumulating stage, a countercurrent depressurization stage, a vacuum purge stage, a first pressure accumulating stage, a second pressure accumulating stage, a third pressure accumulating stage, and a product pressure accumulating stage.

[0061] More specifically, the other four adsorption towers other than the adsorption tower to which the hydrogen mixed gas from which ammonia has been removed is supplied in the guard bed section and hydrogen purification sections 111-116 can sequentially execute one cycle of the adsorption stage, the first pressure equalization stage, the second pressure equalization stage, the purge gas supply stage, the third pressure equalization stage, the countercurrent depressurization stage, the vacuum purge stage, the first pressure accumulation stage, the second pressure accumulation stage, the third pressure accumulation stage, and the product pressure accumulation stage, and the second adsorption tower can sequentially execute one cycle from the third pressure accumulation stage, the third adsorption tower from the vacuum purge stage, the fourth adsorption tower from the purge gas supply stage, and the fifth adsorption tower from the first pressure equalization stage.

[0062] According to another embodiment, the guard bed section includes first to sixth adsorption towers, each of which sequentially performs an adsorption step, a first pressure equalization step, a second pressure equalization step, a third pressure equalization step, a purge gas providing step, a countercurrent depressurization step, a vacuum purge step, a first pressure accumulating step, a second pressure accumulating step, a third pressure accumulating step, and a product pressure accumulating step in order to remove moisture and ammonia from the hydrogen mixed gas supplied from the raw material supply pipe 101, and the hydrogen purification section includes first to sixth adsorption towers 111 to 116, each of which sequentially performs an adsorption step, a first pressure equalization step, a second pressure equalization step, a third pressure equalization step, a purge gas providing step, a countercurrent depressurization step, a vacuum purge step, a first pressure accumulating step, a second pressure accumulating step, a third pressure accumulating step, and a product pressure accumulating step in order to remove nitrogen components from the hydrogen mixed gas from which moisture and ammonia have been removed, supplied from the guard bed section, thereby increasing the purity and recovery rate of the hydrogen product.

[0063] Preferably, the guard bed section includes first to sixth adsorption towers, each of which sequentially performs an adsorption stage, a first pressure equalization stage, a second pressure equalization stage, a third pressure equalization stage, a purge gas supply stage, a countercurrent pressure reduction stage, a vacuum purge stage, a first pressure accumulation stage, a second pressure accumulation stage, a third pressure accumulation stage, a fourth pressure accumulation stage, and a product pressure accumulation stage in order to remove moisture and ammonia from the hydrogen mixed gas supplied from the raw material supply pipe 101, and the hydrogen purification section includes first to sixth adsorption towers 111. to 116, each of the first to sixth adsorption towers may sequentially perform an adsorption step, a first pressure equalization step, a second pressure equalization step, a third pressure equalization step, a fourth pressure equalization step, a purge gas providing step, a countercurrent depressurization step, a vacuum purge step, a first pressure accumulating step, a second pressure accumulating step, a third pressure accumulating step, a fourth pressure accumulating step, and a product pressure accumulating step in order to remove nitrogen components from the hydrogen mixed gas from which moisture and ammonia have been removed and which is supplied from the guard bed section to increase the purity and recovery rate of the hydrogen product.

[0064] More preferably, the guard bed section includes first to sixth adsorption towers, each of which sequentially performs an adsorption stage, a first pressure equalization stage, a second pressure equalization stage, a third pressure equalization stage, a purge gas supply stage, a countercurrent pressure reduction stage, a vacuum purge stage, a first pressure accumulation stage, a second pressure accumulation stage, a third pressure accumulation stage, a fourth pressure accumulation stage, and a product pressure accumulation stage in order to remove moisture and ammonia from the hydrogen mixed gas supplied from the raw material supply pipe 101, and the hydrogen purification section includes first to sixth adsorption towers 11. 1 to 116, each of the first to sixth adsorption towers may sequentially perform an adsorption step, a first pressure equalization step, a second pressure equalization step, a third pressure equalization step, a purge gas providing step, a fourth pressure equalization step, a countercurrent depressurization step, a vacuum purge step, a first pressure accumulating step, a second pressure accumulating step, a third pressure accumulating step, a fourth pressure accumulating step, and a product pressure accumulating step in order to remove nitrogen components from the hydrogen mixed gas from which moisture and ammonia have been removed and which is supplied from the guard bed section to increase the purity and recovery rate of the hydrogen product.

[0065] In the step of supplying into the adsorption towers 111 to 116 of the hydrogen purification unit, the hydrogen mixed gas from which the ammonia has been purified may be supplied into one of the adsorption towers in the hydrogen purification unit.

[0066] The step of selectively adsorbing nitrogen and obtaining purified hydrogen may be performed by adsorbing the ammonia and purifying the hydrogen mixture so that the nitrogen content in the purified hydrogen mixture is less than 10 ppm.

[0067] The hydrogen purification method using the pressure swing adsorption apparatus 100 may further include, after the step of obtaining purified hydrogen, a step of collecting the obtained hydrogen in a hydrogen storage tank, and a step of circulating and supplying the hydrogen in the hydrogen storage tank for use in the cleaning step of another adsorption tower and the product pressure storage step of the guard bed unit and the hydrogen purification unit 111-116.

[0068] Each of the multiple adsorption towers including the guard bed section and hydrogen purification sections 111 to 116 can perform one cycle of adsorbing and purifying moisture, ammonia, and nitrogen, and then periodically repeat the hydrogen purification process by supplying the hydrogen mixed gas.

[0069] The method may further include a step of regenerating the first and second adsorbents in the guard bed section by supplying the tail gas discharged from the adsorption towers 111-116 of the hydrogen purification section as a purge gas to the adsorption towers of the guard bed section after the countercurrent depressurization step is completed. Here, the tail gas stream discharged separately from the hydrogen product stream is continuously discharged, so that the method may be operated so that it is continuously supplied as a heat source for heating the ammonia decomposition device.

[0070] The moisture, ammonia and nitrogen removal process using the pressure swing adsorption system 100 of the present invention can be operated as follows with multiple adsorption columns including guard bed sections and hydrogen purification sections.

[0071] According to one embodiment, each of the adsorption towers 121-125 of the guard bed section and each of the adsorption towers 111-115 of the hydrogen purification section may include an adsorption step, a first pressure equalization step, a second pressure equalization step, a purge gas providing step, a third pressure equalization step, a countercurrent depressurization step, a vacuum purge step, a first pressure accumulating step, a second pressure accumulating step, a third pressure accumulating step, and a product pressure accumulating step.

[0072] In the operation method of FIG. 1, a hydrogen mixed gas generated after decomposition of ammonia, which is a raw gas, is supplied to the first adsorption tower 121 of the guard bed section through the raw material supply pipe 101 with the first supply valve 11 connected to the first adsorption tower 121 of the guard bed section open. When moisture and undecomposed ammonia, which are impurities contained in the hydrogen mixed gas supplied to the first adsorption tower 111, pass through the first and second adsorbents filled in a multi-layer structure in the first adsorption tower 121 of the guard bed section, moisture and ammonia are sequentially adsorbed and purified, and a mixed gas containing the remaining nitrogen and hydrogen is obtained. Then, the mixed gas containing nitrogen and hydrogen passes through the first adsorption tower 121 of the guard bed section, and is transported through the pipe 103 with the valve 11-1 open, and is supplied to the first adsorption tower 111 in the hydrogen purification section.

[0073] The ammonia concentration in the hydrogen mixed gas supplied to the hydrogen purification units 111-116 is monitored in real time to maintain the ammonia concentration at less than 0.1 ppm. Here, while the first adsorption tower 121 of the guard bed unit and the first adsorption tower 111 of the hydrogen purification unit perform the adsorption step, the second adsorption tower 122 of the guard bed unit and the second adsorption tower 112 of the hydrogen purification unit sequentially perform the product accumulation step starting from the first accumulation step in the steps of one cycle.

[0074] First, the fifth adsorption tower 125 of the guard bed section and the fifth adsorption tower 115 of the hydrogen purification section perform a first equalization step to reduce pressure in parallel flow through the second pressure equalization valves 24 and 54, and perform a third accumulation step to accumulate pressure in counterflow flow using gas supplied from the pipe 108 of the hydrogen purification section. The second adsorption tower 112 performs final product accumulation using high purity hydrogen produced in the first adsorption tower 121 of the guard bed section and the first adsorption tower 111 of the hydrogen purification section after counterflow accumulation. For product accumulation, the second equalization valves 24 and 54 are closed and the second accumulator valve 24 is opened to accumulate the product up to the adsorption pressure.

[0075] Here, the third adsorption tower 123 of the guard bed section and the third adsorption tower 113 of the hydrogen purification section sequentially perform a vacuum purge step and a first pressure accumulation step in the steps of one cycle. In the purge gas supply step, the fourth adsorption tower 124 of the guard bed section and the fourth adsorption tower 114 of the hydrogen purification section provide the necessary vacuum purge gas to the third adsorption tower 123 and the third adsorption tower 113 of the hydrogen purification section through the piping 106 with the third vacuum purge valve 36 open, and perform vacuum desorption through the vacuum pump piping 102 with the third counterflow pressure reducing valve 32 open.

[0076] After the vacuum purge step, the third adsorption tower 123 and the third adsorption tower 113 of the hydrogen purification unit perform a first pressure accumulation step by depressurizing through the third pressure equalization step of the fourth adsorption tower 114 of the hydrogen purification unit through the valves and piping. In order to prevent ammonia contamination of the hydrogen purification unit, the fourth adsorption tower 124 of the guard bed unit performs a countercurrent depressurization step without the third pressure equalization step, and discharges with the fourth countercurrent depressurization valve 42 open. The fourth adsorption tower 114 of the hydrogen purification unit performs a countercurrent depressurization step after the third pressure equalization step, with the countercurrent depressurization valve 42-1 open. After the first pressure accumulation stage, the third adsorption tower 123 of the guard bed section and the third adsorption tower 113 of the hydrogen purification section perform a second pressure accumulation stage by parallel depressurization through the second equalization stage of the fifth adsorption tower 125 of the guard bed section and the fifth adsorption tower 115 of the hydrogen purification section, and this is performed through piping 107 with the third vacuum purge valve 36 closed and the fourth equalization valve 45 and the fifth equalization valve 55 open.

[0077] After the first adsorption tower 121 of the guard bed section and the first adsorption tower 111 of the hydrogen purification section perform the adsorption step, the first raw material supply valve 11 is closed and parallel depressurization is performed in the first and second equalization steps. Here, the second adsorption tower 122 of the guard bed section and the second adsorption tower 112 of the hydrogen purification section perform the adsorption step by opening the second raw material supply valve 21. The first and third equalization valves 15 and 35 are opened, and the first adsorption tower 121 of the guard bed section and the first adsorption tower 111 of the hydrogen purification section perform the first equalization step and countercurrent depressurization through the pipe 107, and the third adsorption tower 123 of the guard bed section and the third adsorption tower 113 of the hydrogen purification section perform the third accumulation step to perform countercurrent accumulation. After the first pressure equalization step, the first adsorption tower 121 in the guard bed section and the first adsorption tower 111 in the hydrogen purification section open the first and fourth pressure equalization valves 15, 45, and perform parallel depressurization in a second pressure equalization step through piping 107, and perform countercurrent pressure accumulation in a second accumulation step in the fourth adsorption tower 124 in the guard bed section and the fourth adsorption tower 114 in the hydrogen purification section.

[0078] The third adsorption tower performs a product pressure accumulation step using high purity hydrogen produced in the second adsorption tower 122 of the guard bed section and the second adsorption tower 112 of the hydrogen purification section after countercurrent pressure accumulation. For product pressure accumulation, the first and third pressure equalization valves 15 and 35 are closed, and the third pressure accumulation valve 34 is opened to perform a product pressure accumulation step up to the adsorption pressure. Here, the fourth adsorption tower 124 of the guard bed section and the fourth adsorption tower 114 of the hydrogen purification section sequentially perform a vacuum purge step and a first pressure accumulation step among the steps of one cycle. The fifth adsorption tower 125 of the guard bed section and the fifth adsorption tower 115 of the hydrogen purification section provide the vacuum purge gas required for the fourth adsorption tower GB-4 of the guard bed section and the fourth adsorption tower 114 of the hydrogen purification section through the pipe 106 with the fourth and fifth vacuum purge valves 46 and 56 open as a purge gas supply step, and perform vacuum desorption through the vacuum pump pipe 102 with the fourth countercurrent pressure reducing valve 42 open.

[0079] After the vacuum purge step, the fourth adsorption tower 124 of the guard bed section and the fourth adsorption tower 114 of the hydrogen purification section perform a first pressure accumulation step by parallel pressure reduction through the third pressure equalization step of the fifth adsorption tower 115 of the hydrogen purification section through the valves and piping. In order to prevent ammonia contamination of the hydrogen purification section, the fifth adsorption tower 125 of the guard bed section performs a countercurrent pressure reduction step without the third pressure equalization step, and discharges with the fifth countercurrent pressure reduction valve 52 open. The fifth adsorption tower 115 of the hydrogen purification section performs a countercurrent pressure reduction step after the third pressure equalization step, with the fifth countercurrent pressure reduction valve 52-1 open.

[0080] After the first pressure accumulation stage, the fourth adsorption tower 124 of the guard bed section and the fourth adsorption tower 114 of the hydrogen purification section perform a second pressure accumulation stage by parallel depressurization through the second pressure equalization stage of the first adsorption tower 121 of the guard bed section and the first adsorption tower 111 of the hydrogen purification section, and this is performed through piping 107 with the fourth vacuum purge valve 46 closed and the first and fourth equalization valves 15, 45 open.

[0081] After the second adsorption tower 122 of the guard bed section and the second adsorption tower 112 of the hydrogen purification section perform the adsorption step, the second raw material supply valve 21 is closed and parallel depressurization is performed in the first equalization step and the second equalization step. Here, the third adsorption tower 123 of the guard bed section and the third adsorption tower 113 of the hydrogen purification section perform the adsorption step by opening the third raw material supply valve 31. The second and fourth equalization valves 25 and 45 are opened, and the second adsorption tower 122 of the guard bed section and the second adsorption tower 112 of the hydrogen purification section perform the first equalization step and perform countercurrent depressurization through the pipe 107, and the fourth adsorption tower 124 of the guard bed section and the fourth adsorption tower 114 of the hydrogen purification section perform the third accumulation step and perform countercurrent accumulation.

[0082] After the first pressure equalization step, the second adsorption tower 122 of the guard bed section and the second adsorption tower 112 of the hydrogen purification section open the second and fifth equalization valves 25, 55 and perform parallel depressurization through a second equalization step through pipe 107, and the fifth adsorption tower 125 of the guard bed section and the fifth adsorption tower 115 of the hydrogen purification section perform countercurrent depressurization through a second pressure accumulation step. The fourth adsorption tower 124 of the guard bed section and the fourth adsorption tower 114 of the hydrogen purification section perform a product pressure accumulation step using high purity hydrogen produced in the third adsorption tower 123 of the guard bed section and the third adsorption tower 113 of the hydrogen purification section after countercurrent pressure accumulation.

[0083] For the product pressure accumulation step, the second and fifth pressure equalization valves 25, 55 are closed, and the fourth pressure accumulating valve 44 is opened to perform the product pressure accumulation step up to the adsorption pressure. Here, the fifth adsorption tower 125 of the guard bed section and the fifth adsorption tower 115 of the hydrogen purification section sequentially perform the vacuum purge step and the first pressure accumulation step among the steps of one cycle. In the purge gas supply step, the first adsorption tower 121 of the guard bed section and the first adsorption tower 111 of the hydrogen purification section provide the vacuum purge gas required for the fifth adsorption tower 125 of the guard bed section and the fifth adsorption tower 115 of the hydrogen purification section through the pipe 106 with the first and fifth vacuum purge valves 16, 56 open, and perform vacuum desorption through the vacuum pump pipe 102 with the fifth counterflow pressure reducing valve 52 open.

[0084] After the vacuum purge step, the fifth adsorption tower 125 of the guard bed section and the fifth adsorption tower 115 of the hydrogen purification section perform a first pressure accumulation step by parallel pressure reduction through the third pressure equalization step of the first adsorption tower 111 of the hydrogen purification section through the valves and piping. In order to prevent ammonia contamination of the hydrogen purification section, the first adsorption tower 121 of the guard bed section performs a countercurrent pressure reduction step without the third pressure equalization step, and discharges with the first countercurrent pressure reduction valve 12 open. The first adsorption tower 111 of the hydrogen purification section performs a countercurrent pressure reduction step after the third pressure equalization step with the first countercurrent pressure reduction valve 12-1 open. After the first pressure accumulation stage, the fifth adsorption tower 125 of the guard bed section and the fifth adsorption tower 115 of the hydrogen purification section perform a second pressure accumulation stage by parallel depressurization through the second equalization stage of the second adsorption tower 122 of the guard bed section and the second adsorption tower 112 of the hydrogen purification section, and this is performed through piping 107 with the fifth vacuum purge valve 56 closed and the second and fifth equalization valves 25, 55 open.

[0085] After the third adsorption tower 123 of the guard bed section and the third adsorption tower 113 of the hydrogen purification section perform the adsorption step, the third raw material supply valve 31 is closed and parallel depressurization is performed in the first and second equalization steps. Here, the fourth adsorption tower 124 of the guard bed section and the fourth adsorption tower 114 of the hydrogen purification section open the fourth raw material supply valve 41 to perform the adsorption step. The third and fifth equalization valves 35 and 55 are opened to perform the first equalization step and parallel depressurization is performed through the pipe 107, and the fifth adsorption tower 125 of the guard bed section and the fifth adsorption tower 115 of the hydrogen purification section perform the third accumulation step to perform countercurrent accumulation.

[0086] After the first equalization stage, the third adsorption tower 123 in the guard bed section and the third adsorption tower 113 in the hydrogen purification section open the first and third equalization valves 15, 35 and perform parallel depressurization through the second equalization stage through piping 107, and perform countercurrent depressurization through the second accumulation stage in the first adsorption tower 121 in the guard bed section and the first adsorption tower 111 in the hydrogen purification section.

[0087] The fifth adsorption tower 125 of the guard bed section and the fifth adsorption tower 115 of the hydrogen purification section perform a product accumulation step using high purity hydrogen produced in the fourth adsorption tower 124 of the guard bed section and the fourth adsorption tower 114 of the hydrogen purification section after countercurrent pressure accumulation in the third pressure accumulation step. For product accumulation, the first and third pressure equalization valves 15 and 35 are closed and the fifth pressure accumulating valve 54 is opened to perform the product accumulation step up to the adsorption pressure. Here, the first adsorption tower 121 of the guard bed section and the first adsorption tower 111 of the hydrogen purification section sequentially perform the vacuum purge step and the first pressure accumulation step among the steps of one cycle. In the purge gas supply stage, the second adsorption tower 122 of the guard bed section and the second adsorption tower 112 of the hydrogen purification section supply the necessary vacuum purge gas to the first adsorption tower 121 of the guard bed section and the first adsorption tower 111 of the hydrogen purification section through piping 106 with the first and second vacuum purge valves 16, 26 open, and perform vacuum desorption through the vacuum pump piping 102 with the first counterflow pressure reducing valve 12 open.

[0088] After the vacuum purge step, the first adsorption tower 121 and the first adsorption tower 111 of the hydrogen purification unit perform a first pressure accumulation step by parallel pressure reduction in the third pressure equalization step of the second adsorption tower 112 of the hydrogen purification unit through the valves and piping. In order to prevent ammonia contamination of the hydrogen purification unit, the second adsorption tower 122 of the guard bed unit performs a countercurrent pressure reduction step without the third pressure equalization step, and is discharged with the second countercurrent pressure reduction valve 22 open.

[0089] After the third equalization step, the second adsorption tower 112 of the hydrogen purification unit performs a countercurrent depressurization step with the second countercurrent depressurization valve 22-1 open. After the first pressure-accumulation step, the first adsorption tower 121 of the guard bed unit and the first adsorption tower 111 of the hydrogen purification unit perform a second pressure-accumulation step by parallel depressurization in the second equalization step of the third adsorption tower 123 of the guard bed unit and the third adsorption tower 113 of the hydrogen purification unit, with the first vacuum purge valve 16 closed and the first and third equalization valves 15, 35 open through the pipe 107.

[0090] After the fourth adsorption tower 124 of the guard bed section and the fourth adsorption tower 114 of the hydrogen purification section perform the adsorption step, the fourth raw material supply valve 41 is closed and parallel depressurization is performed in the first and second equalization steps. Here, the fifth adsorption tower 125 of the guard bed section and the fifth adsorption tower 115 of the hydrogen purification section open the fifth raw material supply valve 51 to perform the adsorption step. The first and fourth equalization valves 15 and 45 are opened to perform the first equalization step and parallel depressurization is performed through the pipe 107, and the first adsorption tower 121 of the guard bed section and the first adsorption tower 111 of the hydrogen purification section perform the third accumulation step to perform countercurrent accumulation.

[0091] After the first pressure equalization step, the fourth adsorption tower 124 of the guard bed section and the fourth adsorption tower 114 of the hydrogen purification section open the second and fourth pressure equalization valves 45, 25 and perform parallel depressurization through the second pressure equalization step through the pipe 107, and perform the second pressure accumulation step of the second adsorption tower 122 of the guard bed section and the second adsorption tower 112 of the hydrogen purification section to perform countercurrent pressure accumulation. The first adsorption tower 121 of the guard bed section and the first adsorption tower 111 of the hydrogen purification section perform a product pressure accumulation step using high purity hydrogen produced in the fifth adsorption tower 125 of the guard bed section and the fifth adsorption tower 115 of the hydrogen purification section after countercurrent pressure accumulation. For product pressure accumulation, the pressure accumulation valves 45, 25 are closed and the first pressure accumulation valve 14 is opened to perform the product pressure accumulation step up to the adsorption pressure. Here, the second adsorption tower 122 of the guard bed section and the second adsorption tower 112 of the hydrogen purification section sequentially perform the vacuum purge step and the first pressure accumulation step among the steps of the one cycle.

[0092] In a purge gas supply step, the third adsorption tower 123 of the guard bed section and the third adsorption tower 113 of the hydrogen purification section supply the necessary vacuum purge gas to the second adsorption tower 122 of the guard bed section and the second adsorption tower 112 of the hydrogen purification section through piping 106 with the second and third vacuum purge valves 26, 36 open, and perform vacuum desorption through the vacuum pump piping 102 with the second counterflow pressure reduction valve 22 open. After the vacuum purge step, the second adsorption tower 122 and the second adsorption tower 112 of the hydrogen purification section perform a first pressure accumulation step by parallel pressure reduction due to the third pressure equalization step of the third adsorption tower 113 of the hydrogen purification section through the valves and piping.

[0093] In order to prevent ammonia contamination of the hydrogen purification section, the third adsorption tower 123 of the guard bed section performs a countercurrent depressurization step without a third equalization step, and discharges with the third countercurrent depressurization valve 32 open. The third adsorption tower 113 of the hydrogen purification section performs a countercurrent depressurization step after the third equalization step, with the third countercurrent depressurization valve 32-1 open. After the first pressure accumulation step, the second adsorption tower 122 of the guard bed section and the second adsorption tower 112 of the hydrogen purification section perform a second pressure accumulation step by parallel depressurization due to the second equalization step of the fourth adsorption tower 124 of the guard bed section and the fourth adsorption tower 114 of the hydrogen purification section, and performs the second pressure accumulation step through the pipe 107 with the second vacuum purge valve 26 closed and the second and fourth equalization valves 25, 45 open.

[0094] After completion of the one cycle, the adsorption towers 121-125 in the guard bed section and the adsorption towers 111-115 in the hydrogen purification section continue to operate by performing the same steps as in the one cycle, namely the adsorption stage, the first pressure equalization stage, the second pressure equalization stage, the purge gas supply stage, the third pressure equalization stage, the countercurrent depressurization stage, the vacuum purge stage, the first pressure accumulation stage, the second pressure accumulation stage, the third pressure accumulation stage, and the product pressure accumulation stage.

[0095] As described above, the hydrogen purification method using the pressure swing adsorption apparatus 100 of the present invention is capable of purifying high purity hydrogen by physically adsorbing impurities such as moisture (H2O), ammonia (NH3), and nitrogen (N2) contained in the hydrogen mixed gas generated after ammonia decomposition to less than trace amounts, and can maximize hydrogen recovery rate and productivity by improving the selective adsorption of moisture, ammonia, and nitrogen. Furthermore, the initial investment cost is low, and when only the pressure swing adsorption process is applied, a separate temperature swing adsorption process is not required and a heat source for regeneration is not required, thereby reducing operating costs.

[0096] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to the following examples.

[0097] Example 1: Hydrogen purification using a pressure swing adsorption apparatus 100 including a five-column guard bed section and a hydrogen purification section adsorption tower A process was carried out to purify hydrogen from a mixed gas containing 74.775 vol. % hydrogen, 24.925 vol. % nitrogen, and 3,000 ppm ammonia using a pressure swing adsorption apparatus 100 including a guard bed section in which five adsorption towers are arranged in parallel and a hydrogen purification section in which five adsorption towers are arranged in parallel.

[0098] The lower layers of the first to fifth adsorption towers in the guard bed section were filled with 8% by weight of silica gel as a first adsorbent capable of adsorbing moisture, and the upper layers of the first to fifth adsorption towers were filled with 15% by weight of activated carbon impregnated with 5% by weight of magnesium as a second adsorbent capable of adsorbing ammonia, forming a multi-layer structure. Each of the first to fifth adsorption towers in the hydrogen purification section was filled with zeolite CaX capable of adsorbing nitrogen. The supply pressure of the raw gas was 5.5 atm. The process cycles of the guard bed section and the hydrogen purification section were maintained the same, and the start pressures of the countercurrent depressurization steps of the guard bed section and the hydrogen purification section were 0.8 barg and 0.5 barg, respectively.

[0099] Each adsorption tower in the five-tower guard bed section was continuously operated to perform the adsorption stage, the first equalization stage, the second equalization stage, the purge gas supply stage, the countercurrent depressurization stage, the vacuum purge stage, the first accumulator stage, the second accumulator stage, the third accumulator stage, and the product accumulator stage, and each adsorption tower in the hydrogen purification section was continuously operated to perform the adsorption stage, the first equalization stage, the second equalization stage, the third equalization stage, the purge gas supply stage, the countercurrent depressurization stage, the vacuum purge stage, the first accumulator stage, the second accumulator stage, the third accumulator stage, and the product accumulator stage. Here, the raw gas throughput was 22.00 N / min.

[0100] Measurement of the hydrogen purified by the pressure swing adsorption apparatus 100 revealed that the purity of the purified hydrogen was 99.999%, and the hydrogen recovery rate was 86.7%.

[0101] Example 2: Hydrogen purification using a pressure swing adsorption apparatus 100-1 including a six-column guard bed section and an adsorption tower in a hydrogen purification section A process was carried out to purify hydrogen from a mixed gas containing 74.775 vol. % hydrogen, 24.925 vol. % nitrogen, and 3,000 ppm ammonia using a pressure swing adsorption apparatus 100-1 including a guard bed section in which six adsorption towers are arranged in parallel and a hydrogen purification section in which six adsorption towers are arranged in parallel.

[0102] The lower layers of the first to sixth adsorption towers in the guard bed section were filled with 8% by weight of silica gel as a first adsorbent capable of adsorbing moisture, and the upper layers of the first to sixth adsorption towers were filled with 15% by weight of activated carbon impregnated with 5% by weight of magnesium as a second adsorbent capable of adsorbing ammonia, forming a multi-layer structure. Each of the first to sixth adsorption towers in the hydrogen purification section was filled with zeolite CaX capable of adsorbing nitrogen. The supply pressure of the raw gas was 5.5 atm. The process cycles of the guard bed section and the hydrogen purification section were maintained the same, and the start pressures of the countercurrent depressurization steps of the guard bed section and the hydrogen purification section were 0.8 barg and 0.5 barg, respectively.

[0103] Each of the adsorption towers GB1 to GB6 in the six-tower guard bed section performs the adsorption stage, the first equalization stage, the second equalization stage, the third equalization stage, the purge gas supply stage, the countercurrent depressurization stage, the vacuum purge stage, the first accumulating stage, the second accumulating stage, the third accumulating stage, the fourth accumulating stage, and the product accumulating stage, and each of the adsorption towers 111 to 116 in the hydrogen purification section performs the adsorption stage, the first equalization stage, the second equalization stage, the third equalization stage, the purge gas supply stage, the fourth equalization stage, the countercurrent depressurization stage, the vacuum purge stage, the first accumulating stage, the second accumulating stage, the third accumulating stage, the fourth accumulating stage, and the product accumulating stage. Here, the raw gas throughput was 22.00 N / min.

[0104] Measurement of the hydrogen refined by pressure swing adsorption apparatus 100-1 revealed that the purity of the refined hydrogen was 99.999%, and the hydrogen recovery rate was 87.414%. [Explanation of symbols]

[0105] 100, 100-1 Pressure swing adsorption device 101 Raw material supply pipe 102~108 Many tubes 111-116 1st to 6th adsorption towers of hydrogen purification section 121-126 Guard bed section No. 1-6 adsorption towers 131 Vacuum Pump 11, 21, 31, 41, 51, 61 1st to 6th raw material supply valves 11-1, 21-1, 31-1, 41-1, 51-1, 61-1 Discharge valves for 1st to 6th guard beds 12, 22, 32, 42, 52, 62 Counterflow pressure reducing valves for 1st to 6th guard beds 12-1, 22-1, 32-1, 42-1, 52-1, 62-1 Countercurrent pressure reducing valves for the 1st to 6th hydrogen purification units 13, 23, 33, 43, 53, 63 1st to 6th product production valves 14, 24, 34, 44, 54, 64 Accumulator valves 1-6 15, 25, 35, 45, 55, 65 1st to 6th pressure equalizing valves 16, 26, 36, 46, 56, 66 1st to 6th vacuum purge valves

Claims

1. A pressure swing adsorption apparatus comprising: a number of adsorption towers connected to a raw material supply pipe, the adsorption towers including a guard bed section and a hydrogen purification section; a vacuum pump connected to the adsorption towers for maintaining the adsorption towers in a vacuum state; and a number of valves for opening and closing a number of pipes connected to the adsorption towers and the vacuum pump, the guard bed section is located at a lower end of the hydrogen purification section, and an adsorption tower in the guard bed section is filled with a first adsorbent and a second adsorbent in a multi-layer structure, the first adsorbent and the second adsorbent selectively adsorbing and removing moisture and ammonia contained in a hydrogen mixed gas generated after ammonia decomposition supplied through the raw material supply pipe, a pressure swing adsorption device for purifying hydrogen from ammonia decomposition, wherein the hydrogen purification section is located at an upper end of the guard bed section, and an adsorption tower in the hydrogen purification section is filled with a third adsorbent that selectively adsorbs and removes nitrogen contained in the hydrogen mixed gas from which moisture and ammonia have been removed in the guard bed section.

2. 2. The pressure swing adsorption apparatus for purifying hydrogen from ammonia decomposition according to claim 1, wherein the guard bed section and the hydrogen purification section are connected in series to each other, and the apparatus has a structure in which two or more adsorption tower sets each composed of the guard bed section and the hydrogen purification section connected in series are arranged in parallel.

3. 2. The pressure swing adsorption apparatus for producing hydrogen from ammonia decomposition as claimed in claim 1, wherein the minimum pressure of the adsorption tower in the guard bed section is maintained at no lower than 1 / 4 of the feed pressure.

4. 2. The pressure swing adsorption device for purifying hydrogen from ammonia decomposition according to claim 1, wherein the first adsorbent is filled in a lower layer portion of the adsorption tower of the guard bed section and is one or more types selected from the group consisting of first activated alumina, silica gel, alumina silica gel, and zeolite capable of removing moisture.

5. 2. The pressure swing adsorption apparatus for purifying hydrogen from ammonia decomposition as recited in claim 1, wherein the first adsorbent comprises 1 to 70 wt. % relative to the second adsorbent.

6. 2. The pressure swing adsorption apparatus for purifying hydrogen from ammonia decomposition according to claim 1, wherein the second adsorbent is filled in an upper layer portion of the adsorption tower of the guard bed section and is one or more types selected from the group consisting of metal-impregnated activated carbon capable of removing ammonia, silica gel, alumina silica gel, zeolite, and second activated alumina.

7. 7. The pressure swing adsorption apparatus for purifying hydrogen from ammonia decomposition according to claim 6, wherein the metal-impregnated activated carbon is activated carbon impregnated with one or more metals selected from the group consisting of Mg, Ca, Mn, and Cu.

8. 2. The pressure swing adsorption apparatus for purifying hydrogen from ammonia decomposition as recited in claim 1, wherein the second adsorbent comprises 30 to 99 wt. % relative to the first adsorbent.

9. 2. The pressure swing adsorption apparatus for purifying hydrogen from ammonia decomposition according to claim 1, wherein the third adsorbent is one or more selected from the group consisting of zeolite NaA, zeolite CaA, zeolite CaNaA, zeolite LiX, zeolite LiNaX, zeolite LiCaX, zeolite LiNaCaX, zeolite NaX, zeolite CaX, zeolite CaNaX, and zeolite KX.

10. The minimum pressure of the adsorption tower in the guard bed section is maintained at no lower than 1 / 3 to 2 / 5 of the raw material supply pressure, the first adsorbent is filled in a lower layer of the adsorption tower of the guard bed section, and is a first activated alumina or silica gel capable of removing moisture; the first adsorbent is filled in an adsorption tower of the guard bed section at a ratio of 10 to 35% by weight relative to the second adsorbent, The second adsorbent is filled in an upper layer of the adsorption tower of the guard bed section and is a metal-impregnated activated carbon capable of removing ammonia, the second adsorbent is filled in an adsorption tower of the guard bed section at a ratio of 65 to 90% by weight with respect to the first adsorbent, The metal-impregnated activated carbon is magnesium (Mg)-impregnated activated carbon or calcium (Ca)-impregnated activated carbon, The amount of metal impregnated in the metal-impregnated activated carbon is 1 to 8% by weight, 2. The pressure swing adsorption apparatus for purifying hydrogen from ammonia decomposition as recited in claim 1, wherein the third adsorbent is zeolite LiX, zeolite CaX, or a mixture thereof.

11. 2. A method for purifying hydrogen using a pressure swing adsorption apparatus according to claim 1, comprising: a number of adsorption towers connected to a raw material supply pipe, the adsorption towers including a guard bed section and a hydrogen purification section; a vacuum pump connected to the adsorption towers for maintaining the adsorption towers in a vacuum state; and a number of valves for opening and closing a number of pipes connected to the adsorption towers and the vacuum pump, supplying a hydrogen mixed gas produced after ammonia decomposition into the adsorption tower of the guard bed section through a raw material supply pipe; passing the supplied hydrogen mixed gas through a first adsorbent filled in a lower layer of the adsorption tower in the guard bed section to selectively adsorb and remove moisture; passing the hydrogen mixed gas from which moisture has been removed through a second adsorbent filled in an upper portion of the adsorption tower in the guard bed section to selectively adsorb and remove ammonia; supplying the hydrogen mixed gas from which moisture and ammonia have been removed into an adsorption tower of a hydrogen purification unit; obtaining purified hydrogen by passing the supplied hydrogen mixed gas from which moisture and ammonia have been removed through a third adsorbent filled in an adsorption tower in the hydrogen purification unit to selectively adsorb and remove nitrogen; A method for purifying hydrogen using a pressure swing adsorption device, comprising:

12. The step of selectively adsorbing and removing ammonia is a step of adsorbing and removing ammonia so that a content of ammonia in the hydrogen mixed gas from which moisture has been removed is less than 0.1 ppm, 12. The method of claim 11, wherein the step of obtaining purified hydrogen by selectively adsorbing and removing nitrogen comprises adsorbing and removing nitrogen such that a nitrogen content in the hydrogen mixed gas from which ammonia has been removed is less than 10 ppm.

13. the guard bed section includes first to fifth adsorption towers, each of which sequentially performs an adsorption step, a first pressure equalization step, a second pressure equalization step, a purge gas supply step, a countercurrent depressurization step, a vacuum purge step, a first pressure accumulation step, a second pressure accumulation step, and a product pressure accumulation step to remove moisture and ammonia from the hydrogen mixed gas supplied from the raw material supply pipe; 12. The method of claim 11, wherein the hydrogen purification unit includes first to fifth adsorption towers, and each of the first to fifth adsorption towers sequentially performs an adsorption step, a first pressure equalization step, a second pressure equalization step, a purge gas providing step, a countercurrent depressurization step, a vacuum purge step, a first pressure accumulation step, a second pressure accumulation step, and a product pressure accumulation step in order to increase the purity and recovery rate of the hydrogen product while removing nitrogen components from the hydrogen mixed gas from which moisture and ammonia have been removed and which is supplied from the guard bed unit.

14. the guard bed section includes first to sixth adsorption towers, each of which sequentially performs an adsorption step, a first pressure equalization step, a second pressure equalization step, a third pressure equalization step, a purge gas providing step, a countercurrent depressurization step, a vacuum purge step, a first pressure accumulation step, a second pressure accumulation step, a third pressure accumulation step, and a product pressure accumulation step to remove moisture and ammonia from the hydrogen mixed gas supplied from the raw material supply pipe; 12. The method of claim 11, wherein the hydrogen purification unit includes first to sixth adsorption towers, and each of the first to sixth adsorption towers sequentially performs an adsorption step, a first pressure equalization step, a second pressure equalization step, a third pressure equalization step, a purge gas providing step, a countercurrent depressurization step, a vacuum purge step, a first pressure accumulating step, a second pressure accumulating step, a third pressure accumulating step, and a product pressure accumulating step in order to increase the purity and recovery rate of the hydrogen product while removing nitrogen components from the hydrogen mixed gas from which moisture and ammonia have been removed and which is supplied from the guard bed unit.

15. 15. The method for purifying hydrogen using a pressure swing adsorption device according to claim 13 or 14, further comprising the step of supplying a tail gas discharged from the adsorption tower of the hydrogen purification unit as a purge gas to the adsorption tower of the guard bed unit after the countercurrent depressurization step is completed, thereby regenerating the first and second adsorbents of the guard bed unit.

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