Adsorbent regeneration method of PSA hydrogen production adsorption tower

Abstract

The invention provides an adsorbent regeneration method of a PSA hydrogen production adsorption tower, and belongs to the technical field of adsorbent regeneration, and the adsorbent regeneration method comprises the following steps: S1, slowly heating and preliminarily preheating nitrogen, and simultaneously introducing the nitrogen into the adsorption tower; s2, heating the nitrogen, continuously introducing the nitrogen into the adsorption tower, further desorbing impurities in the adsorbent, and stopping heating the nitrogen until the temperature at a nitrogen outlet of the adsorption tower reaches the lowest and rises; s3, continuously carrying out cold blowing cooling on the adsorption tower by using nitrogen; s4, after cooling is completed, nitrogen containing a small amount of oxygen is introduced into the adsorption tower, light oxidation activation is conducted on the adsorbent, and regeneration is completed. Hot nitrogen uniformly penetrates through an adsorbent layer, contacts with and desorbs impurities, then is matched with condensation-gasification circulation of low-pressure steam to further dredge micropores of the adsorbent, and is supplemented with a small amount of oxygen to oxidize impurities on the surface of the adsorbent, recover the activity of the adsorbent and effectively regenerate the adsorbent, so that the adsorption performance of the adsorbent is 90% or above of the initial performance.

Description

Technical Field

[0001] The present invention relates to the technical field of adsorbent regeneration, and in particular to an adsorbent regeneration method for a PSA hydrogen production adsorption tower. Background Art

[0002] PSA hydrogen production utilizes pressure swing adsorption (PSA) to efficiently extract high-purity hydrogen from mixed gases. This technology relies on the selective adsorption properties of a solid adsorbent (molecular sieve) for various gas components under varying pressures. Through a cyclic process of high-pressure adsorption of impurities and low-pressure desorption, the PSA system not only effectively separates hydrogen from other components but also ensures the regeneration and recycling of the adsorbent material.

[0003] Since 2020, during the PSA hydrogen production process at a certain project, excessive feed gas, with fluctuating composition and multiple high-level exceeding standards for hydrogen sulfide, naphthalene, benzene, and ammonia, has been introduced into the adsorption tower. This has severely poisoned the adsorbent, significantly reducing its adsorption efficiency and selectivity. Conventional regeneration methods have struggled to restore the adsorbent to optimal performance, bringing production to a near standstill. During this period, hydrogen recovery rates declined, and power consumption reached a record high of 0.48 kWh / m³. This not only disrupted the normal production process but also forced the equipment to undergo more frequent regeneration, further increasing energy consumption and operating costs.

[0004] Faced with this challenge, existing technologies typically resort to directly replacing the adsorbent to quickly resume production. However, this approach has significant limitations and additional costs. First, replacing the adsorbent is not only expensive, but also requires hazardous waste disposal, increasing the environmental burden and compliance costs. Second, the adsorbent procurement cycle is long and the replacement process is complex, seriously affecting the continuous production of hydrogen and downstream gas demand, potentially resulting in missing the optimal profit period. Therefore, directly replacing the adsorbent is not a wise move, and there is an urgent need to find a more cost-effective solution to ensure production stability and economic benefits. Summary of the Invention

[0005] The object of the present invention is to provide a method for regenerating an adsorbent of a PSA hydrogen production adsorption tower to solve the problems raised in the above background technology.

[0006] To achieve the above object, the present invention provides the following technical solutions:

[0007] A method for regenerating an adsorbent in a PSA hydrogen production adsorption tower:

[0008] S1, slowly heating the nitrogen for preliminary preheating, and simultaneously passing the nitrogen into the adsorption tower to purge the adsorbent and remove some volatile impurities;

[0009] S2, heating the nitrogen gas and continuously passing it into the adsorption tower to further remove impurities in the adsorbent until the temperature at the nitrogen outlet of the adsorption tower reaches a minimum and then increases, and then stopping the nitrogen heating;

[0010] S3, after stopping heating, continue to use nitrogen to blow cold air on the adsorption tower to cool it;

[0011] S4, after cooling is completed, nitrogen containing a small amount of oxygen is introduced into the adsorption tower to perform mild oxidation activation on the adsorbent;

[0012] S5, dry hydrogen is introduced into the adsorption tower, and the adsorbent is allowed to cool further naturally, and regeneration is completed.

[0013] Preferably, in step S1, the initial preheating temperature of nitrogen is 80-120°C, and the purging time is 20-40 minutes.

[0014] Preferably, in step S2, the nitrogen temperature is heated to 180-220°C.

[0015] Deep heating to 180-220°C can effectively break the chemical bonds between the poisoned adsorbent and the impurities, promoting impurity desorption while avoiding damage to the adsorbent's internal structure due to excessive temperatures. This temperature exhibits good desorption effects on various types of poisoned adsorbents, such as activated carbon-based adsorbents poisoned by hydrogen sulfide and molecular sieve adsorbents poisoned by benzene and naphthalene.

[0016] Preferably, in step S2, low-pressure steam is intermittently introduced along with nitrogen, the amount of low-pressure steam introduced is 2-5% of the nitrogen flow rate, the intermittent introduction is once every 5-8 minutes, and each time lasts for 1-2 minutes.

[0017] Since the adsorbent has a strong affinity for water molecules, the dew point of nitrogen must be controlled during the process of regenerating the adsorbent using hot nitrogen to prevent water from being re-adsorbed by the adsorbent. Relatively speaking, within the effective range, the lower the dew point of nitrogen, the better, but the corresponding cost will be higher.

[0018] The present invention takes the opposite approach. During the high-temperature desorption process, a small amount of low-pressure steam is intermittently introduced. The low-pressure steam contacts the relatively low-temperature adsorbent surface and condenses, forming condensed water in the adsorbent micropores and occupying a certain space. As the hot nitrogen continues to be introduced, the adsorbent temperature rises, and the liquid water vaporizes into water vapor under the action of heat, rapidly expanding in volume. This expansion force can effectively open micropores that are blocked or partially blocked by impurities. Through this condensation-vaporization cycle, the adsorbent micropores are unblocked and their activity is restored. At the same time, the intermittent introduction of small amounts of low-pressure steam can ensure that the condensed water is fully vaporized, avoiding the impact of excessive water vapor on the adsorbent desorption effect.

[0019] Preferably, in step S2, when the temperature at the nitrogen outlet of the adsorption tower reaches the minimum and rebounds by 10°C, the nitrogen heating is stopped.

[0020] Preferably, in step S3, cooling is completed when the temperature at the nitrogen outlet of the adsorption tower drops to 40-60°C.

[0021] Preferably, in step S4, the content of oxygen in the nitrogen is 0.5-1.5 vol%.

[0022] Preferably, in step S4, the temperature of the mild oxidation activation is 50-70° C., and the time is 10-15 minutes.

[0023] By introducing a small amount of oxygen, it reacts with the active sites on the surface of the adsorbent and some residual organic impurities, removing substances such as carbon deposits formed by the adsorption of impurities, restoring the active groups on the surface of the adsorbent, further activating the internal microstructure of the adsorbent, and enhancing its adsorption affinity for the target gas.

[0024] Preferably, the nitrogen flow rate is controlled at 100-150m 3 / h, the pressure is maintained at 10-50Kpa, and the dew point of nitrogen is ≤-50℃.

[0025] The flow rate is preferably 100-150m 3 / h, and the pressure is maintained at 10-50KPa, so that the hot nitrogen can evenly penetrate the adsorbent layer, fully contact with the adsorbent and desorb impurities at low pressure, preventing the adsorption tower from being overloaded, avoiding possible mechanical scouring damage to the adsorbent by nitrogen, and reducing energy waste.

[0026] Preferably, in step S5, dry hydrogen at room temperature is introduced into the adsorption tower to make the pressure in the adsorption tower 10KPa, and the tower is sealed and placed for 2-3 days, and then cooled naturally to complete the regeneration.

[0027] The beneficial effects of the above technical solution of the present invention are as follows:

[0028] 1. The present invention allows hot nitrogen to evenly penetrate the adsorbent layer, fully contacting and desorbing impurities. Then, the adsorbent micropores are further dredged through the condensation-gasification cycle of low-pressure steam. A small amount of oxygen is then added to oxidize and remove impurities on the adsorbent surface, restoring the active groups on the adsorbent surface and effectively removing impurities on the poisoned adsorbent. The adsorption performance of the adsorbent is restored to more than 90% of its initial performance, significantly improving the hydrogen production efficiency and purity of the PSA hydrogen production system.

[0029] 2. The activation process of this invention begins by introducing low-pressure steam, which physically unclogs micropores, removing most impurities and some organic impurities that react violently with oxygen. Oxygen is then introduced for further activation, preventing violent oxidation reactions that could damage the adsorbent structure. This gentle and comprehensive regeneration process minimizes damage to the adsorbent structure, extending the adsorbent's service life by 1.5-2.5 times and reducing the frequency and associated costs of adsorbent replacement.

[0030] 3. Regeneration of the adsorbent in the PSA hydrogen production adsorption tower is expensive, and the parameters of the online regeneration method are difficult to control. Any error can easily lead to scrapping, which is very costly in terms of economic and efficiency. Therefore, the adsorbent often needs to be removed and shipped to the manufacturer for regeneration using conventional methods, which is time-consuming and labor-intensive. The present invention provides an online regeneration method for the adsorbent in the PSA hydrogen production adsorption tower. Compared with conventional regeneration methods, the output and power consumption of hydrogen production after regeneration are greatly optimized, with significant economic, time-consuming, labor-intensive, and social benefits. According to actual production, the production output has reached a maximum of 2.7 t / h, and the unit power consumption of production has been reduced to 0.43 kWh / m³. DETAILED DESCRIPTION

[0031] The technical solutions in the embodiments of the present invention are described clearly and completely below. Those skilled in the art should know that the embodiments described below are only part of the embodiments of the present disclosure, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present invention.

[0032] Example 1

[0033] A method for regenerating an adsorbent of a PSA hydrogen production adsorption tower comprises the following steps:

[0034] S1, slowly heating nitrogen to preheat to 100°C, and at the same time, passing nitrogen into the adsorption tower to purge the adsorbent for 30 minutes to remove some volatile impurities;

[0035] S2, heat the nitrogen temperature to 220 ° C, and continue to pass it into the adsorption tower to further remove impurities in the adsorbent. During this process, as the nitrogen is passed in, low-pressure steam is intermittently mixed in. The mixing amount of low-pressure steam is 5% of the nitrogen flow rate, once every 8 minutes, and each time lasts for 1 minute. When the temperature at the nitrogen outlet of the adsorption tower reaches the lowest, stop passing the low-pressure steam. When the temperature at the nitrogen outlet of the adsorption tower reaches the lowest and rises by 10 ° C, stop nitrogen heating;

[0036] S3, after stopping nitrogen heating, continue to use room temperature nitrogen to cold blow the adsorption tower until the temperature at the nitrogen outlet of the adsorption tower drops to 50°C, and the cooling is completed;

[0037] S4, after cooling is completed, nitrogen containing 1.5 vol% oxygen is introduced into the adsorption tower at a temperature of 50°C for 15 minutes to perform mild oxidation activation on the adsorbent;

[0038] S5, after activation is completed, dry nitrogen at room temperature is introduced into the adsorption tower to make the pressure in the adsorption tower 10KPa, and the tower is sealed and placed for 3 days to allow the adsorbent to further cool naturally, and regeneration is completed.

[0039] In the above steps S1-S4, the nitrogen flow rate used was controlled at 130m 3 / h, pressure is 30Kpa, dew point is -60℃.

[0040] Example 2

[0041] A method for regenerating an adsorbent of a PSA hydrogen production adsorption tower comprises the following steps:

[0042] S1, slowly heating nitrogen to 80°C, and simultaneously passing nitrogen into the adsorption tower to purge the adsorbent for 20 minutes to remove some volatile impurities;

[0043] S2, heat the nitrogen temperature to 200 ° C, and continue to pass it into the adsorption tower to further remove impurities in the adsorbent. During this process, as the nitrogen is passed in, low-pressure steam is intermittently mixed in. The mixing amount of low-pressure steam is 3% of the nitrogen flow rate, once every 8 minutes, and each time lasts for 2 minutes. When the temperature at the nitrogen outlet of the adsorption tower reaches the lowest, stop passing the low-pressure steam. When the temperature at the nitrogen outlet of the adsorption tower reaches the lowest and rises by 10 ° C, stop nitrogen heating;

[0044] S3, after stopping nitrogen heating, continue to use room temperature nitrogen to cold blow the adsorption tower until the temperature at the nitrogen outlet of the adsorption tower drops to 60°C, and the cooling is completed;

[0045] S4, after cooling is completed, nitrogen containing 0.5% oxygen is introduced into the adsorption tower at a temperature of 60°C for 15 minutes to perform mild oxidation activation on the adsorbent;

[0046] S5, after activation is completed, dry nitrogen at room temperature is introduced into the adsorption tower to make the pressure in the adsorption tower 10KPa, and the tower is sealed and placed for 2 days to allow the adsorbent to further cool naturally, and regeneration is completed.

[0047] In the above steps S1-S4, the nitrogen flow rate used was controlled at 100m 3 / h, pressure is 50Kpa, dew point is -50℃.

[0048] Example 3

[0049] A method for regenerating an adsorbent of a PSA hydrogen production adsorption tower comprises the following steps:

[0050] S1, slowly heating nitrogen to preheat to 120°C, and simultaneously passing nitrogen into the adsorption tower to purge the adsorbent for 40 minutes to remove some volatile impurities;

[0051] S2, heat the nitrogen temperature to 180 ° C, and continue to pass it into the adsorption tower to further remove impurities in the adsorbent. During this process, as the nitrogen is passed in, low-pressure steam is intermittently mixed in. The mixing amount of low-pressure steam is 2% of the nitrogen flow rate, once every 5 minutes, and each time lasts for 1 minute. When the temperature at the nitrogen outlet of the adsorption tower reaches the lowest, stop passing the low-pressure steam. When the temperature at the nitrogen outlet of the adsorption tower reaches the lowest and rises by 10 ° C, stop nitrogen heating;

[0052] S3, after stopping nitrogen heating, continue to use room temperature nitrogen to cold blow the adsorption tower until the temperature at the nitrogen outlet of the adsorption tower drops to 60°C, and the cooling is completed;

[0053] S4, after cooling is completed, nitrogen containing 1 vol% oxygen is introduced into the adsorption tower at a temperature of 60°C for 10 minutes to perform mild oxidation activation on the adsorbent;

[0054] S5, after activation is completed, dry nitrogen at room temperature is introduced into the adsorption tower to make the pressure in the adsorption tower 10KPa, and the tower is sealed and placed for 3 days to allow the adsorbent to further cool naturally, and regeneration is completed.

[0055] In the above steps S1-S4, the nitrogen flow rate used was controlled at 150m 3 / h, pressure is 10Kpa, dew point is -70℃.

[0056] Comparative Example 1

[0057] The difference between this comparative example and Example 1 is that in step S2, low-pressure steam is not mixed in, and the other steps are the same as those in Example 1.

[0058] In this comparative example, the specific steps of S2 are: heating the nitrogen temperature to 220°C and continuously passing it into the adsorption tower. When the temperature at the nitrogen outlet of the adsorption tower reaches the lowest and rises by 10°C, stopping the nitrogen heating.

[0059] Comparative Example 2

[0060] The difference between this comparative example and Example 1 is that in step S2, when the temperature at the nitrogen outlet of the adsorption tower reaches the lowest, the nitrogen heating is stopped.

[0061] Comparative Example 3

[0062] The difference between this comparative example and Example 1 is that in step S4, mild oxidation activation is not performed, and regeneration is completed when the cooling in step S3 is completed.

[0063] Comparative Example 4

[0064] The difference between this comparative example and Example 1 is that in steps S1 to S4, the dew point of nitrogen is -20°C.

[0065] The results of the operation according to Examples 1-3 and Comparative Examples 1-4 are shown in the following table:

[0066] Adsorption performance recovery (%) Output (t / h) Specific power consumption (kWh / m³) Example 1 93% 2.73 0.43 Example 2 92% 2.71 0.43 Example 3 92% 2.70 0.43 Comparative Example 1 83% 2.43 0.46 Comparative Example 2 76% 2.24 0.47 Comparative Example 3 81% 2.38 0.46 Comparative Example 4 63% 1.85 0.51

[0067] Comparing Examples 1-3 with Comparative Examples 1-4, it can be seen that the adsorbent performance recovery after regeneration in the embodiments of the present invention reached over 90%. After commissioning, the output was significantly higher than that of the comparative examples, and the unit power consumption was significantly lower than that of the comparative examples. The present invention allows hot nitrogen to evenly penetrate the adsorbent layer, fully contacting and desorbing impurities. The adsorbent micropores are then further unblocked through a condensation-gasification cycle of low-pressure steam. A small amount of oxygen is then added to oxidize and remove impurities on the adsorbent surface, restoring the active groups on the adsorbent surface, effectively removing impurities from the poisoned adsorbent, and restoring the adsorption performance of the adsorbent.

[0068] While the above-described ideal embodiments of the present invention are provided as a guide, it will be apparent to those skilled in the art that such embodiments are provided by way of example only. Those skilled in the art will appreciate numerous modifications, variations, and alternatives without departing from the spirit and scope of the present invention. It should be understood that in practicing the present invention, various alternatives to the embodiments of the present invention described herein may be employed. The appended claims are intended to define the scope of the present invention and, therefore, cover modular components, equivalents, or alternatives within the scope of these claims.

Claims

1. A method for regenerating an adsorbent of a PSA hydrogen production adsorption tower, characterized in that: The following steps are involved: S1, slowly heating the nitrogen for preliminary preheating, and simultaneously passing the nitrogen into the adsorption tower to purge the adsorbent and remove some volatile impurities; S2, heating the nitrogen gas and continuously passing it into the adsorption tower to further remove impurities in the adsorbent until the temperature at the nitrogen outlet of the adsorption tower reaches a minimum and then increases, and then stopping the nitrogen heating; S3, after stopping heating, continue to use nitrogen to blow cold air on the adsorption tower to cool it; S4, after cooling is completed, nitrogen containing a small amount of oxygen is introduced into the adsorption tower to perform mild oxidation activation on the adsorbent; S5, dry hydrogen is introduced into the adsorption tower, and the adsorbent is allowed to cool further naturally, and regeneration is completed.

2. The adsorbent regeneration method for a PSA hydrogen production adsorption tower according to claim 1, characterized in that: In step S1, the initial preheating temperature of nitrogen is 80-120° C., and the purging time is 20-40 minutes.

3. The adsorbent regeneration method for a PSA hydrogen production adsorption tower according to claim 1, characterized in that: In step S2, the nitrogen temperature is heated to 180-220°C.

4. The adsorbent regeneration method for a PSA hydrogen production adsorption tower according to claim 1, characterized in that: In step S2, low-pressure steam is intermittently introduced along with nitrogen. The amount of low-pressure steam introduced is 2-5% of the nitrogen flow rate, and the intermittent introduction is once every 5-8 minutes, and each time lasts for 1-2 minutes.

5. The adsorbent regeneration method for a PSA hydrogen production adsorption tower according to claim 1, characterized in that: In step S2, when the temperature at the nitrogen outlet of the adsorption tower reaches the minimum and rebounds by 10°C, the nitrogen heating is stopped.

6. The adsorbent regeneration method for a PSA hydrogen production adsorption tower according to claim 1, characterized in that: In step S3, when the temperature at the nitrogen outlet of the adsorption tower drops to 40-60°C, the cooling is completed.

7. The adsorbent regeneration method for a PSA hydrogen production adsorption tower according to claim 1, characterized in that: In step S4, the content of oxygen in the nitrogen is 0.5-1.5 vol%.

8. The adsorbent regeneration method for a PSA hydrogen production adsorption tower according to claim 4, characterized in that: In step S4, the temperature of the mild oxidation activation is 50-70° C. and the time is 10-15 minutes.

9. The adsorbent regeneration method for a PSA hydrogen production adsorption tower according to any one of claims 1 to 8, characterized in that: The nitrogen flow rate is controlled at 100-150m 3 / h, the pressure is maintained at 10-50Kpa, and the dew point of nitrogen is ≤-50℃.

10. The adsorbent regeneration method for a PSA hydrogen production adsorption tower according to claim 1, characterized in that: In step S5, dry hydrogen is introduced to make the pressure in the adsorption tower 10KPa, and the tower is sealed and placed for 2-3 days, and then cooled naturally to complete the regeneration.