Hydrogen purification process based on PSA (Pressure Swing Adsorption) device

Abstract

The invention relates to the technical field of PSA (Pressure Swing Adsorption) hydrogen extraction, in particular to a hydrogen purification process based on a PSA device, which comprises the following steps: raw material gas is firstly decompressed and enters the PSA device, a product hydrogen after impurity removal is sent to the outside, desorbed gas of the PSA device is pressurized by a desorbed gas compressor and is sent to a first-section shift converter, the raw material gas enters an adsorption tower in an adsorption state, and the desorbed gas enters a second-section shift converter; under the action of a special adsorbent, CO, N2, CH4O, CH4, AR and other components in the raw material gas are adsorbed, and high-purity H2 flows out of the tower top, is subjected to pressure stabilization metering through a regulating valve and then is sent out. According to the hydrogen purification process based on the PSA device, residual impurities can be deeply removed by using two-stage pressure swing adsorption, additionally arranging a two-stage adsorption tower and performing post-treatment detection on hydrogen, the impurity content required by high-purity hydrogen needs to be controlled at a ppm level, the purity of the hydrogen can stably rise to 99.99% or even higher through two-stage PSA, and the purity of the hydrogen is greatly improved. The use standard of ultra-high-purity hydrogen in the production of semiconductors and photovoltaic cells is met, and the process stability and the yield of products are guaranteed.

Description

Technical Field

[0001] The present invention relates to the technical field of PSA hydrogen extraction, and in particular to a hydrogen purification process based on a PSA device. Background Art

[0002] As the world's attention to clean energy continues to rise, new energy technologies represented by hydrogen fuel cells are booming. Application scenarios such as hydrogen fuel cell vehicles and distributed power generation systems require extremely high hydrogen purity, usually reaching 99.99% or even higher. The presence of trace amounts of impurities may poison the fuel cell electrodes and reduce power generation efficiency. The hydrogen obtained by traditional water electrolysis is often mixed with trace amounts of oxygen and water vapor, making it difficult to meet strict purity requirements; fossil fuel reforming hydrogen production, in addition to hydrogen, also produces a large amount of impurities such as carbon monoxide, carbon dioxide, and sulfide, making subsequent purification difficult.

[0003] Chemical industry: Hydrogen is the core reactant in classic chemical processes such as synthetic ammonia and methanol synthesis. In the synthetic ammonia reaction, nitrogen and hydrogen need to be mixed in a precise ratio. Insufficient hydrogen purity will greatly reduce the ammonia synthesis conversion rate and damage the catalyst due to impurity accumulation. The impurity composition of hydrogen produced as a byproduct of traditional coal chemical industry is complex, including tar, aromatics, hydrogen sulfide, etc. Direct use will not only affect product quality, but also corrode equipment and pipelines.

[0004] Disadvantages of early gas separation technology:

[0005] Cryogenic distillation: It was once used for large-scale hydrogen purification. The principle is to use the difference in boiling points of different gases to separate them in a low-temperature environment. However, this process requires large-scale refrigeration equipment to maintain ultra-low temperatures (usually below -150°C), consumes a lot of energy, has high equipment investment costs, takes a long time to start and stop the device, and is complicated to operate. It is not suitable for small and medium-scale hydrogen purification needs and conditions where the purity of hydrogen needs to be adjusted in real time.

[0006] Membrane separation technology: With the help of special material membranes, separation is achieved based on the size and solubility of gas molecules. However, it has limited selectivity and is sensitive to the impurity composition of the mixed gas. Once the impurities are complex, the hydrogen recovery rate drops sharply; the membrane material is easily contaminated and aged by impurities, and needs to be replaced frequently, increasing operating costs; and it is difficult to obtain high-purity hydrogen with single-stage membrane separation, and multi-stage combination increases the complexity and cost of the equipment.

[0007] PSA is the abbreviation of pressure adsorption. It is a new gas separation technology. Taking the adsorbent molecular sieve as an example, its principle is to separate the gas mixture by utilizing the difference in the "adsorption" performance of molecular sieves to different gas molecules. The PSA hydrogen purification device is a device that purifies hydrogen in petroleum through PSA.

[0008] PSA technology works by the selective adsorption / desorption characteristics of adsorbents for gases under pressure fluctuations. Under normal temperature and medium pressure conditions, the adsorbent accurately captures impurities such as carbon monoxide, carbon dioxide, and methane, and releases hydrogen. The process avoids ultra-low temperature and extreme high pressure environments, has low energy consumption, and simple equipment. Adsorbent regeneration is achieved through pressure reduction and vacuuming, and it can be recycled, has a long life, and reduces raw material and operation and maintenance costs. However, the existing PSA hydrogen purification device cannot achieve continuous separation and purification of gas. Summary of the invention

[0009] The object of the present invention is to provide a hydrogen purification process based on a PSA device to solve the problems raised in the above background technology.

[0010] To achieve the above object, the present invention provides the following technical solution: A hydrogen purification process based on a PSA device, comprising the following steps:

[0011] S1: Raw gas pretreatment:

[0012] The hydrogen-containing raw gas first enters the filter to remove solid particles and droplets. These impurities include dust, rust particles, and oil droplets. A mechanical filter is used, and the filter mesh size can be selected according to the size of the particles in the raw gas, preferably 5-20μm, to intercept solid impurities;

[0013] For raw gas containing more liquid droplets, a gas-liquid separator can be used to separate the liquid by gravity sedimentation or centrifugal force, because liquid and solid impurities may block the micropores of the adsorbent, reduce the performance of the adsorbent, and even damage the components in the adsorption tower;

[0014] Preheat the raw gas. If the raw gas temperature is low, the adsorbent performance may change or condensation may occur due to temperature changes after entering the adsorption tower. Preheating the raw gas to 30-50°C through a heat exchanger helps maintain the stability of the adsorption process.

[0015] S2: Adsorption process:

[0016] The raw gas enters the adsorption tower which is in the adsorption state from the bottom of the adsorption tower. Under the sequential selective adsorption of multiple adsorbents, various impurities in it are adsorbed in turn, and the unadsorbed H2 flows out from the top of the tower as product gas, and is sent to the outside after being stabilized by the pressure regulating system;

[0017] S3: Pressure equalization and pressure reduction process:

[0018] As the adsorption step is coming to an end, a large amount of high-pressure hydrogen remains in the adsorption tower. To avoid waste, the pressure equalization and pressure reduction operation is started. After the adsorption process is completed, the higher-pressure hydrogen in the tower is put into other lower-pressure adsorption towers that have completed regeneration along the adsorption direction. This process is not only a pressure reduction process, but also a process of recovering effective gas in the dead space of the bed, ensuring the full recovery of H2.

[0019] S4: Sequential release process:

[0020] After the pressure equalization and decompression process is completed, the gas from the adsorption tower is put into the adsorption tower that has just been reversed along the adsorption direction to serve as the gas source for flushing and regeneration;

[0021] S5: Reverse process:

[0022] After the forward release process is completed, the adsorption front has reached the bed outlet, and the pressure of the adsorption tower is reduced to near normal pressure in the opposite direction of adsorption. The adsorbed impurities begin to be desorbed from the adsorbent in large quantities, and the desorbed gas is sent to the desorbed gas mixing tank;

[0023] S6: Flushing process:

[0024] After the reverse discharge process is completed, the adsorption bed is flushed by the forward discharge gas from other towers to reduce the partial pressure of the adsorbed components and fully desorb them, thereby achieving the purpose of adsorbent regeneration;

[0025] S7: Voltage equalization and boosting process:

[0026] The higher pressure effective gas from other adsorption towers is used to pressurize the adsorption tower in turn. This process corresponds to the equalization and pressure reduction process. It is not only a pressure-raising process, but also a process of recovering hydrogen in the dead space of the bed of other towers.

[0027] S8: Product gas pressure boosting process:

[0028] The raw gas enters the adsorption tower in the adsorption state. Under the action of the special adsorbent, CO, N2, CH4O, CH4, and AR components in the raw gas are adsorbed, and high-purity H2 flows out from the top of the tower and is sent out after being metered by the regulating valve for pressure stabilization.

[0029] After the pressure equalization and pressure increase process is completed, in order to allow the adsorption tower to smoothly switch to the next adsorption and ensure that the product purity does not fluctuate during this process, it is necessary to slowly and steadily increase the pressure of the adsorption tower to the adsorption pressure with product hydrogen through a program-controlled valve with an adjustment function;

[0030] S9: Post-processing of product hydrogen:

[0031] The purified hydrogen flowing out of the adsorption tower first enters the buffer tank, and the buffered hydrogen can be stored in a high-pressure storage tank for subsequent use;

[0032] S10: Quality inspection and adjustment:

[0033] The stored hydrogen is quality tested, mainly for its purity, impurity content and other indicators. Gas chromatographs and other instruments are used to ensure that the quality of the hydrogen meets the standards. Based on the test results, if the hydrogen purity does not meet the requirements, the process parameters of the PSA device can be adjusted, such as adsorption time and desorption pressure, or the hydrogen can be purified by deoxygenation and dehumidification.

[0034] Preferably, the PSA hydrogen extraction device consists of 10 adsorption towers, 1 raw gas separator, 1 forward gas discharge buffer tank, 1 reverse gas discharge buffer tank, 1 desorption mixing tank and a series of programmable valves.

[0035] Preferably, the commonly used adsorbents in S2 include molecular sieves, activated carbon, and silica gel. The 5A molecular sieve has a strong adsorption capacity for impurities such as N2 and CO; activated carbon can effectively adsorb some macromolecular organic matter and impurities such as sulfides; and silica gel has a good adsorption effect on moisture.

[0036] Preferably, the function of the buffer tank is to stabilize the flow and pressure of hydrogen. The size of the buffer tank is determined according to the hydrogen production and the needs of downstream users. The volume of the buffer tank is determined based on 10-20% of the hourly hydrogen production.

[0037] Preferably, the pressure of the storage tank is determined according to the user's requirements and storage conditions, and is preferably between 1-20 MPa. For large-scale hydrogen storage, a higher pressure is usually used to reduce the volume of the storage tank.

[0038] Preferably, during the S2 adsorption process, when the front of the mass transfer zone of the adsorbed impurities reaches a certain position in the reserved section of the bed outlet, the raw gas feed valve and the product gas outlet valve of the adsorption tower are turned off, the adsorption is stopped, and the adsorption bed begins to enter the regeneration process.

[0039] Preferably, during the S5 reverse release process, the impurities accumulated in the adsorption tower reach a peak value and need to be desorbed and discharged urgently, the reverse release program is started, the bottom valve of the adsorption tower is opened in reverse, the pressure drops rapidly from 0.3MPa to 0.02-0.05MPa, and the impurities originally adsorbed in the pores are affected by the sudden drop in pressure, break free from the adsorption force, and escape in large quantities in the form of gas to form desorbed gas. These desorbed gases carry impurities and are quickly introduced into the desorbed gas buffer tank for collection for subsequent treatment.

[0040] Preferably, the impurity molecules in S8 are adsorbed in the pores due to their strong interaction with the adsorbent surface; while the hydrogen molecules have weak adsorption force with the adsorbent due to their own physical and chemical properties, so they can directly pass through the bed and flow out smoothly from the top of the adsorption tower to become the initially purified product hydrogen.

[0041] Compared with the prior art, the present invention has the following beneficial effects:

[0042] 1. The hydrogen purification process based on the PSA device can deeply remove residual impurities by using two-stage pressure swing adsorption, adding a secondary adsorption tower and hydrogen post-processing detection. The impurity content required for high-purity hydrogen needs to be controlled at the ppm level. The two-stage PSA can steadily increase the hydrogen purity to 99.99% or even higher, meeting the use standards for ultra-high purity hydrogen in the production of semiconductors and photovoltaic cells, and ensuring product process stability and yield.

[0043] 2. The hydrogen purification process based on the PSA device reduces the impurity content to nearly the detection limit through secondary adsorption. Taking CO removal as an example, the CO residual content after the first stage of PSA may be tens of ppm, which can be sharply reduced to less than 1 ppm after the second stage of treatment, thereby extending the service life of the catalyst in the downstream process and reducing production costs.

[0044] 3. The hydrogen purification process based on the PSA device can balance purity and recovery efficiency. The first-level adsorption tower first separates most of the impurities and recovers a large amount of hydrogen; the second-level adsorption tower focuses on the precise adsorption of a small amount of residual impurities, reducing the loss of hydrogen with the venting of impurities. The overall hydrogen recovery rate can be increased by 5-15%. In the large-scale industrial hydrogen production scenario, more high-purity hydrogen products can be harvested with the same raw gas input, which is in line with the demands of efficient resource utilization and energy conservation and emission reduction.

[0045] 4. The hydrogen purification process based on the PSA device shows super adaptability through the combination of different adsorbents in multiple adsorption towers and dynamic adjustment of process parameters. The first-stage adsorption adopts a large-capacity, high-resistance to impurity impact adsorbent coarse screening, and the second-stage fine-tunes the adsorption strategy according to the residual impurities to ensure that regardless of the quality of the raw gas and how the composition changes, it can stably output qualified high-purity hydrogen, broaden the range of raw material selection, and reduce the dependence on high-quality raw materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings in the following description are only some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying creative labor.

[0047] Figure 1 It is a process flow chart of the present invention;

[0048] Figure 2 The pressure swing adsorption process flow chart of the present invention. DETAILED DESCRIPTION

[0049] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0050] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0051] See also Figure 1-Figure 2 , the present invention provides a technical solution:

[0052] A hydrogen purification process based on a PSA device comprises the following steps:

[0053] S1: Raw gas pretreatment:

[0054] The hydrogen-containing raw gas first enters the filter to remove solid particles and droplets. These impurities include dust, rust particles, and oil droplets. A mechanical filter is used, and the filter mesh size can be selected according to the size of the particles in the raw gas, preferably 5-20μm, to intercept solid impurities;

[0055] For raw gas containing more liquid droplets, a gas-liquid separator can be used to separate the liquid by gravity sedimentation or centrifugal force, because liquid and solid impurities may block the micropores of the adsorbent, reduce the performance of the adsorbent, and even damage the components in the adsorption tower;

[0056] Preheat the raw gas. If the raw gas temperature is low, the adsorbent performance may change or condensation may occur due to temperature changes after entering the adsorption tower. Preheating the raw gas to 30-50°C through a heat exchanger helps maintain the stability of the adsorption process.

[0057] S2: Adsorption process:

[0058] The raw gas enters the adsorption tower which is in the adsorption state from the bottom of the adsorption tower. Under the sequential selective adsorption of multiple adsorbents, various impurities in it are adsorbed in turn, and the unadsorbed H2 flows out from the top of the tower as product gas, and is sent to the outside after being stabilized by the pressure regulating system;

[0059] S3: Pressure equalization and pressure reduction process:

[0060] As the adsorption step is coming to an end, a large amount of high-pressure hydrogen remains in the adsorption tower. To avoid waste, the pressure equalization and pressure reduction operation is started. After the adsorption process is completed, the higher-pressure hydrogen in the tower is put into other lower-pressure adsorption towers that have completed regeneration along the adsorption direction. This process is not only a pressure reduction process, but also a process of recovering effective gas in the dead space of the bed, ensuring the full recovery of H2.

[0061] S4: Sequential release process:

[0062] After the pressure equalization and decompression process is completed, the gas from the adsorption tower is put into the adsorption tower that has just been reversed along the adsorption direction to serve as the gas source for flushing and regeneration;

[0063] At the beginning of the release, the pressure in the adsorption tower is at the adsorption pressure (generally 0.5-3.0MPa), and as the release process proceeds, the pressure gradually decreases. The pressure at the end of the release is usually determined by the subsequent process requirements and system design, and generally drops to a relatively low value that is still higher than normal pressure, such as 0.1-0.3MPa.

[0064] The forward discharge flow rate needs to be precisely controlled, and a regulating valve is usually used to adjust the forward discharge speed. If the forward discharge flow rate is too large, the adsorbent will precipitate impurities too early, affecting the subsequent reverse discharge and flushing effects, and may cause a greater impact on the adsorbent bed; if the forward discharge flow rate is too small, the adsorption cycle will be extended and the processing capacity of the device will be reduced.

[0065] S5: Reverse process:

[0066] After the forward release process is completed, the adsorption front has reached the bed outlet, and the pressure of the adsorption tower is reduced to near normal pressure in the opposite direction of adsorption. The adsorbed impurities begin to be desorbed from the adsorbent in large quantities, and the desorbed gas is sent to the desorbed gas mixing tank;

[0067] At the beginning of the reverse release, the pressure in the adsorption tower is at a relatively low pressure after the end of the forward release (such as 0.1-0.3MPa), and then the reverse release valve is quickly opened to connect the adsorption tower with the external low-pressure environment (such as a desorption gas buffer tank at or near normal pressure), and the pressure in the adsorption tower decreases rapidly. At the end of the reverse release, the pressure in the adsorption tower is basically close to normal pressure, but may be slightly higher than normal pressure due to factors such as system resistance, generally within the range of 0.01-0.05MPa.

[0068] The reverse speed has an important influence on the desorption effect of impurities. Rapid reverse can form a large pressure difference in a short time, which is conducive to the rapid desorption of impurities, but too fast reverse may cause severe vibration of the adsorbent bed, causing wear and even breakage of the adsorbent particles, affecting the service life of the adsorbent. Therefore, the reverse speed needs to be reasonably controlled according to factors such as the properties of the adsorbent, the structure of the adsorption tower and the type of impurities. Generally, the optimization of the reverse speed is achieved by selecting a suitable reverse valve diameter, designing a reasonable reverse piping system and adopting appropriate control strategies (such as step-by-step reverse, current-limited reverse, etc.).

[0069] The inversion process is one of the key steps in adsorbent regeneration. It effectively desorbs impurities on the adsorbent, restores the adsorption capacity of the adsorbent, and ensures that the adsorbent can work normally in the next adsorption cycle. The quality of the inversion effect is directly related to the service life of the adsorbent and the long-term stable operation of the PSA unit. If the inversion is not thorough, there will be a lot of residual impurities on the adsorbent, which will lead to a decrease in the adsorption performance of the adsorbent in subsequent adsorption cycles, affecting the purity and output of hydrogen; at the same time, residual impurities may also accumulate in the adsorbent bed, causing bed blockage, increasing system pressure drop, and further affecting device performance. Therefore, during the inversion process, it is necessary to pay close attention to parameters such as the change in inversion pressure and the composition of the desorption gas, and adjust the inversion operating conditions in time to ensure that the adsorbent is fully regenerated.

[0070] The gas discharged during the reverse discharge process contains a large amount of impurities, such as carbon monoxide, carbon dioxide, nitrogen, etc., as well as a small amount of incompletely desorbed hydrogen. These reverse discharge gases cannot be discharged directly and need to be treated. The reverse discharge gas is usually introduced into a buffer tank, which, on the one hand, plays a buffering and pressure stabilizing role, and on the other hand, can be preliminarily separated to recycle the hydrogen therein (such as as fuel gas or raw material gas for other processes). The remaining impure gas needs to be further processed, such as combustion, washing, adsorption and other processes, to remove the harmful components therein so that it can meet the environmental emission standards before being discharged.

[0071] S6: Flushing process:

[0072] After the reverse discharge process is completed, the adsorption bed is flushed by the forward discharge gas from other towers to reduce the partial pressure of the adsorbed components and fully desorb them, thereby achieving the purpose of adsorbent regeneration;

[0073] S7: Voltage equalization and boosting process:

[0074] The higher pressure effective gas from other adsorption towers is used to pressurize the adsorption tower in turn. This process corresponds to the equalization and pressure reduction process. It is not only a pressure-raising process, but also a process of recovering hydrogen in the dead space of the bed of other towers.

[0075] S8: Product gas pressure boosting process:

[0076] The raw gas enters the adsorption tower in the adsorption state. Under the action of the special adsorbent, CO, N2, CH4O, CH4, and AR components in the raw gas are adsorbed, and high-purity H2 flows out from the top of the tower and is sent out after being metered by the regulating valve for pressure stabilization.

[0077] After the pressure equalization and pressure increase process is completed, in order to allow the adsorption tower to smoothly switch to the next adsorption and ensure that the product purity does not fluctuate during this process, it is necessary to slowly and steadily increase the pressure of the adsorption tower to the adsorption pressure with product hydrogen through a program-controlled valve with an adjustment function;

[0078] S9: Post-processing of product hydrogen:

[0079] The purified hydrogen flowing out of the adsorption tower first enters the buffer tank, and the buffered hydrogen can be stored in a high-pressure storage tank for subsequent use;

[0080] S10: Quality inspection and adjustment:

[0081] The stored hydrogen is quality tested, mainly for its purity, impurity content and other indicators. Gas chromatographs and other instruments are used to ensure that the quality of the hydrogen meets the standards. Based on the test results, if the hydrogen purity does not meet the requirements, the process parameters of the PSA device can be adjusted, such as adsorption time and desorption pressure, or the hydrogen can be purified by deoxygenation and dehumidification.

[0082] Product Requirements

[0083] Product pressure 2.8MPa(G);

[0084] The purity of the product CO+CO2 is less than 10ppm.

[0085] According to the above gas quality conditions and product gas requirements, the raw gas is first decompressed to 2.9MPa(G) and enters the PSA-1 unit, and the product hydrogen after impurities are removed is sent to the outside. The desorbed gas from the PSA-1 unit is pressurized by the desorbed gas compressor and sent to the first-stage conversion furnace.

[0086] The raw gas from outside the boundary is decompressed to 2.9MPa(G) and enters the PSA-1 hydrogen extraction device, which consists of 10 adsorption towers, 1 raw gas separator, 1 forward gas release buffer tank, 1 reverse gas release buffer tank, 1 desorption mixing tank and a series of programmable valves. The raw gas enters the adsorption tower in the adsorption state. Under the action of the special adsorbent, CO, N2, CH4O, CH4, AR and other components in the raw gas are adsorbed, and high-purity H2 flows out from the top of the tower and is sent out of the boundary after being stabilized and metered by the regulating valve.

[0087] The PSA hydrogen extraction device adopts the 10-2-5 / P process, that is, a total of 10 adsorption towers, 2 towers for adsorption, 5 times of equalization, and flushing and regeneration. The adsorbent saturated with impurity components is regenerated through 5 equalization pressure drops, forward placement, reverse placement, flushing, 5 times of equalization pressure increases, and final increase. After this series of processes, the adsorption tower completes a complete "adsorption-regeneration" cycle and is ready for the next adsorption. Each adsorption tower alternately performs adsorption and regeneration to achieve continuous separation and purification of the gas.

[0088] After being regulated and pressure stabilized, the desorbed gas is sent to the desorbed gas compressor to be pressurized to 6.5MPa (G) and then sent to the first-stage conversion furnace of the conversion unit and used before being incorporated into the main line to preheat the conversion gas.

[0089] See the table below for the raw gas conditions.

[0090]

[0091]

[0092] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the statement "comprise a ..." do not exclude the presence of other identical elements in the process, method, article or device including the elements.

[0093] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A hydrogen purification process based on a PSA device, characterized in that: The following steps are involved: S1: Raw gas pretreatment: The hydrogen-containing raw gas first enters the filter to remove solid particles and droplets. These impurities include dust, rust particles, and oil droplets. A mechanical filter is used, and the filter mesh size can be selected according to the size of the particles in the raw gas, preferably 5-20μm, to intercept solid impurities; For raw gas containing more liquid droplets, a gas-liquid separator can be used to separate the liquid by gravity sedimentation or centrifugal force, because liquid and solid impurities may block the micropores of the adsorbent, reduce the performance of the adsorbent, and even damage the components in the adsorption tower; Preheat the raw gas. If the raw gas temperature is low, the adsorbent performance may change or condensation may occur due to temperature changes after entering the adsorption tower. Preheating the raw gas to 30-50°C through a heat exchanger helps maintain the stability of the adsorption process. S2: Adsorption process: The raw gas enters the adsorption tower which is in the adsorption state from the bottom of the adsorption tower. Under the sequential selective adsorption of multiple adsorbents, various impurities in it are adsorbed in turn, and the unadsorbed H2 flows out from the top of the tower as product gas, and is sent to the outside after being stabilized by the pressure regulating system; S3: Pressure equalization and pressure reduction process: As the adsorption step is coming to an end, a large amount of high-pressure hydrogen remains in the adsorption tower. To avoid waste, the pressure equalization and pressure reduction operation is started. After the adsorption process is completed, the higher-pressure hydrogen in the tower is put into other lower-pressure adsorption towers that have completed regeneration along the adsorption direction. This process is not only a pressure reduction process, but also a process of recovering effective gas in the dead space of the bed, ensuring the full recovery of H2. S4: Sequential release process: After the pressure equalization and decompression process is completed, the gas from the adsorption tower is put into the adsorption tower that has just been reversed along the adsorption direction to serve as the gas source for flushing and regeneration; S5: Reverse process: After the forward release process is completed, the adsorption front has reached the bed outlet, and the pressure of the adsorption tower is reduced to near normal pressure in the opposite direction of adsorption. The adsorbed impurities begin to be desorbed from the adsorbent in large quantities, and the desorbed gas is sent to the desorbed gas mixing tank; S6: Flushing process: After the reverse discharge process is completed, the adsorption bed is flushed by the forward discharge gas from other towers to reduce the partial pressure of the adsorbed components and fully desorb them, thereby achieving the purpose of adsorbent regeneration; S7: Voltage equalization and boosting process: The higher pressure effective gas from other adsorption towers is used to pressurize the adsorption tower in turn. This process corresponds to the equalization and pressure reduction process. It is not only a pressure-raising process, but also a process of recovering hydrogen in the dead space of the bed of other towers. S8: Product gas pressure boosting process: The raw gas enters the adsorption tower in the adsorption state. Under the action of the special adsorbent, CO, N2, CH4O, CH4, and AR components in the raw gas are adsorbed, and high-purity H2 flows out from the top of the tower and is sent out after being metered by the regulating valve for pressure stabilization. After the pressure equalization and pressure increase process is completed, in order to allow the adsorption tower to smoothly switch to the next adsorption and ensure that the product purity does not fluctuate during this process, it is necessary to slowly and steadily increase the pressure of the adsorption tower to the adsorption pressure with product hydrogen through a program-controlled valve with an adjustment function; S9: Post-processing of product hydrogen: The purified hydrogen flowing out of the adsorption tower first enters the buffer tank, and the buffered hydrogen can be stored in a high-pressure storage tank for subsequent use; S10: Quality inspection and adjustment: The stored hydrogen is quality tested, mainly for its purity, impurity content and other indicators. Gas chromatographs and other instruments are used to ensure that the quality of the hydrogen meets the standards. Based on the test results, if the hydrogen purity does not meet the requirements, the process parameters of the PSA device can be adjusted, such as adsorption time and desorption pressure, or the hydrogen can be purified by deoxygenation and dehumidification.

2. The hydrogen purification process based on a PSA device according to claim 1, characterized in that: The PSA hydrogen extraction device is composed of 10 adsorption towers, 1 raw gas separator, 1 forward gas discharge buffer tank, 1 reverse gas discharge buffer tank, 1 desorption mixing tank and a series of program-controlled valves.

3. The hydrogen purification process based on a PSA device according to claim 1, characterized in that: Commonly used adsorbents in S2 include molecular sieves, activated carbon, and silica gel. 5A molecular sieve has a strong adsorption capacity for impurities such as N2 and CO; activated carbon can effectively adsorb some large molecular organic matter and impurities such as sulfides; silica gel has a good adsorption effect on moisture.

4. The hydrogen purification process based on a PSA device according to claim 1, characterized in that: The function of the buffer tank is to stabilize the flow and pressure of hydrogen. The size of the buffer tank is determined according to the hydrogen production and the needs of downstream users. The volume of the buffer tank is determined based on 10-20% of the hourly hydrogen production.

5. The hydrogen purification process based on a PSA device according to claim 1, characterized in that: The pressure of the storage tank is determined according to the user's requirements and storage conditions, and is preferably between 1-20 MPa. For large-scale hydrogen storage, a higher pressure is usually used to reduce the volume of the storage tank.

6. The hydrogen purification process based on a PSA device according to claim 1, characterized in that: During the S2 adsorption process, when the front of the mass transfer zone of the adsorbed impurities reaches a certain position in the reserved section of the bed outlet, the raw gas feed valve and the product gas outlet valve of the adsorption tower are closed, the adsorption is stopped, and the adsorption bed begins to enter the regeneration process.

7. The process for purifying hydrogen based on a PSA device according to claim 1, characterized in that: During the S5 reverse release process, the impurities accumulated in the adsorption tower reach a peak value and need to be desorbed and discharged urgently. The reverse release program is started, and the bottom valve of the adsorption tower is opened in reverse. The pressure drops rapidly from 0.3MPa to 0.02-0.05MPa. The impurities originally adsorbed in the pores are affected by the sudden drop in pressure, break free from the adsorption force, and escape in large quantities in the form of gas to form desorbed gas. These desorbed gases carry impurities and are quickly introduced into the desorbed gas buffer tank for collection and subsequent treatment.

8. The process for purifying hydrogen based on a PSA device according to claim 1, characterized in that: The impurity molecules in S8 are adsorbed in the pores due to their strong interaction with the adsorbent surface; Due to its physical and chemical properties, hydrogen molecules have weak adsorption force with the adsorbent and can pass directly through the bed. It flows out smoothly from the top of the adsorption tower and becomes the initially purified product hydrogen.

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