Method for regenerating a dual-bed molecular sieve adsorber

Abstract

The application provides a regeneration method of a double-bed molecular sieve adsorber, which comprises the following steps: step 1, multiple pulse pressure change treatments are carried out on the adsorption saturated adsorption tower, each pulse cycle comprises one rapid pressure reduction and one short-term pressure rise, the pressure in the tower is gradually reduced to the final regeneration pressure according to a preset sequence; step 2, under the condition of maintaining the final regeneration pressure, high-temperature purge gas is introduced from the inlet end of the adsorption tower to form a high-temperature heat wave, the high-temperature heat wave is pushed from the inlet end to the outlet end in the form of a wave, and the adsorbent bed is regenerated in sections; and step 3, the discharge valve is closed, the pressure in the adsorption tower is increased to the adsorption pressure, and the adsorption tower is restored to the adsorption working state. Compared with the traditional uniform speed pressure reduction or high-temperature regeneration, the regeneration time is significantly shortened through the multiple pulse pressure change treatments and the cooperation of the heat wave purge.

Description

Technical Field

[0001] This application relates to the field of dual-bed molecular sieves, and more particularly to a method for regenerating a dual-bed molecular sieve adsorber. Background Technology

[0002] A dual-bed molecular sieve adsorber, also known as a dual-tower molecular sieve adsorber or dual-bed molecular sieve adsorber, is a type of equipment used in industrial gas separation and purification, commonly found in air separation units and oxygen / nitrogen production systems. Dual-bed refers to the equipment containing two independent adsorption towers / beds that operate alternately. While one tower is adsorbing, the other tower is desorbing and regenerating, thus achieving continuous gas production. Specifically, in the adsorption stage: compressed air enters the adsorption tower, and the molecular sieve preferentially adsorbs impurities such as moisture, carbon dioxide, and hydrocarbons from the air, while oxygen and nitrogen pass through and are sent to the subsequent distillation unit. In the regeneration stage: when one tower approaches saturation, the system switches to the other tower. The saturated tower desorbs the adsorbed impurities by reducing pressure or heating, restoring the molecular sieve's adsorption capacity.

[0003] The bed of a dual-bed molecular sieve adsorber is divided into upper and lower layers along the axial direction. The bottom layer is generally filled with activated alumina, which preferentially adsorbs a large amount of water; the upper layer is filled with molecular sieves, which specifically adsorb CO2 and hydrocarbons. Because water molecules are highly polar, they are easily adsorbed on alumina. The removal of water molecules requires a higher temperature and takes a longer time. Summary of the Invention

[0004] In view of this, this application proposes a regeneration method for a dual-bed molecular sieve adsorber to improve the water molecule removal efficiency.

[0005] A method for regenerating a dual-bed molecular sieve adsorber includes the following steps: Step 1: Perform multiple pulsed pressure swing treatments on the adsorption tower that has reached adsorption saturation. Each pulse cycle includes a rapid pressure drop and a brief pressure increase, so that the pressure inside the tower gradually decreases to the final regeneration pressure according to a preset sequence. Step 2: Under the condition of maintaining the final regeneration pressure, high temperature purge gas is introduced from the inlet end of the adsorption tower to form a high temperature heat wave. This high temperature heat wave is pushed from the inlet end to the outlet end in the form of a wave to regenerate the adsorbent bed segment by segment. Step 3: Close the discharge valve and restore the pressure inside the adsorption tower to the adsorption pressure, so that the adsorption tower returns to the adsorption working state.

[0006] The technical advantage of this application is that, through multiple pulse-type voltage transformation processes combined with hot wave purging, the regeneration time is significantly shortened compared to traditional uniform voltage reduction or high-temperature regeneration.

[0007] This application's thermal purging only heats the purging gas, not the entire molecular sieve bed, reducing heating energy consumption by 70%–80%; the elimination of the cold purging step further saves energy. Total energy consumption is reduced by 60%–70%.

[0008] By implementing the regeneration method of this application, the high-temperature exposure time of molecular sieves is reduced from 60-90 minutes to 5-10 minutes, the thermal shock is significantly reduced, and the pulverization rate of molecular sieves is slowed down. Detailed Implementation

[0009] The embodiments of the technical solution of this application will be described in detail below. The following embodiments are only used to illustrate the technical solution of this application more clearly, and are therefore only examples, and should not be used to limit the scope of protection of this application.

[0010] Step 1: Perform multiple pulsed pressure swing treatments on the adsorption tower that has reached adsorption saturation. Each pulse cycle includes a rapid pressure drop and a brief pressure rise, so that the pressure inside the tower gradually decreases according to a preset sequence to the final regeneration pressure.

[0011] In a preferred embodiment, step 1 is specifically performed as follows: Step 11: First rapid blood pressure reduction Open the discharge valve of the adsorption tower to rapidly reduce the pressure inside the tower from the adsorption pressure P0 to the first intermediate pressure P1. The pressure reduction rate is 0.2 to 0.4 MPa / min, and the pressure reduction time is 0.5 to 1.5 minutes.

[0012] Optimal parameters: P0=0.6MPa, P1=0.3MPa, pressure reduction rate 0.3MPa / min, time 1 minute.

[0013] Step 12: First brief pressurization Close the discharge valve slightly to allow the pressure inside the tower to rise from P1 to the second intermediate pressure P2. The pressure increase rate is 0.05–0.15 MPa / min, and the pressure increase time is 0.5–1.5 minutes.

[0014] Optimal parameters: P2 = 0.4 MPa, pressure increase rate 0.1 MPa / min, time 1 minute.

[0015] Step 13: Second rapid blood pressure reduction Open the discharge valve again to rapidly reduce the pressure inside the tower from P2 to the third intermediate pressure P3. The pressure reduction rate is 0.15–0.3 MPa / min, and the pressure reduction time is 0.5–1.5 minutes.

[0016] Optimal parameters: P3 = 0.2 MPa, pressure reduction rate 0.2 MPa / min, time 1 minute.

[0017] Step 14: Second brief pressurization Close the discharge valve slightly to allow the pressure inside the tower to rise from P3 to the fourth intermediate pressure P4. The pressure increase rate is 0.05–0.15 MPa / min, and the pressure increase time is 0.5–1.5 minutes.

[0018] Optimal parameters: P4 = 0.3 MPa, pressure increase rate 0.1 MPa / min, time 1 minute.

[0019] Step 15: Third rapid blood pressure reduction Open the discharge valve again to rapidly reduce the pressure inside the tower from P4 to the final regeneration pressure P5. The pressure reduction rate is 0.15–0.3 MPa / min, and the pressure reduction time is 0.5–1.5 minutes.

[0020] Optimal parameters: P5 = 0.1 MPa, pressure reduction rate 0.2 MPa / min, time 1 minute.

[0021] Step 2: Under the condition of maintaining the final regeneration pressure, high-temperature purging gas is introduced from the inlet end of the adsorption tower to form a high-temperature heat wave. This high-temperature heat wave is pushed from the inlet end to the outlet end in the form of a wave to regenerate the adsorbent bed segment by segment.

[0022] In a preferred embodiment, step 2 is specifically performed as follows: Step 21: Start the fast-response heater Turn on the fast-response heater installed on the inlet pipe of the adsorption tower to heat the purge gas from room temperature to the target regeneration temperature T1.

[0023] Optimal parameters: T1 = 170~200℃, heater response time ≤ 5min.

[0024] Step 22: Introduce high-temperature purging gas High-temperature purging gas heated to T1 is introduced into the inlet of the adsorption tower at a preset flow rate Q to maintain the pressure inside the tower at P5.

[0025] Optimal parameters: Q = 50% to 70% of the conventional purging airflow, P5 = 0.1 MPa.

[0026] In a preferred embodiment, the purging gas in step 2 is nitrogen, which is deeply dried and then heated to T1.

[0027] Furthermore, the nitrogen gas is deeply dried, then plasma activated, and then heated to T1.

[0028] Step 23: High-temperature heat wave propulsion High-temperature purge gas enters the adsorption tower from the inlet end, forming a high-temperature region in the bed with a temperature significantly higher than that upstream and downstream, i.e., a high-temperature heat wave. This high-temperature heat wave propagates towards the outlet end in the form of a wave, with a propagation velocity of 5–15 cm / min.

[0029] Characteristics of high-temperature heat waves: Gas temperature inside the heat wave: T1±10℃ Heat wave width: 10%–20% of the total bed height Bed temperature before and after the heat wave: 50–60°C at the inlet and 30–50°C at the outlet. Step 24: Tracking, Monitoring, and Propulsion Control Three to five temperature monitoring points are set along the axial direction of the adsorption tower to monitor the temperature changes at each point in real time. When the temperature at a certain monitoring point reaches T1-20℃, it is determined that the high-temperature heat wave has passed through the cross section of that monitoring point.

[0030] Step 25: High-temperature heat wave reaches the outlet end When the temperature monitoring point at the outlet reaches T1-20℃, it is determined that the high-temperature heat wave has passed through the entire bed. The fast-response heater is then shut down, and the supply of high-temperature purging gas is stopped.

[0031] Step 3: Close the discharge valve and restore the pressure inside the adsorption tower to the adsorption pressure, so that the adsorption tower returns to the adsorption working state.

[0032] In a preferred embodiment, step 3 is specifically performed as follows: Step 31: Primary pressure equalization Open the equalizing valve and use the gas in another adsorption tower that is in the adsorption state to equalize and pressurize the regenerated adsorption tower, so that the pressure inside the tower rises from P5 to the first intermediate pressurization pressure P6.

[0033] Optimal parameters: P5=0.1MPa, P6=0.3MPa, equalization time 2-3 minutes.

[0034] Step 32: Final pressurization Close the equalizing valve and open the pressurizing valve to use the purified raw material air to finally pressurize the adsorption tower, raising the pressure inside the tower from P6 to the adsorption pressure P0.

[0035] Optimal parameters: P6=0.3MPa, P0=0.6MPa, pressurization time 3-5 minutes.

[0036] The implementation effects of the solution in this application will be verified below with reference to the embodiments and comparative examples.

[0037] Example 1: Basic Scheme – Pulse Transformer Combined with Thermal Wave Purging Equipment conditions: a certain 60000Nm 3The / h air separation unit uses a vertical double-tower molecular sieve adsorber, also known as a dual-bed molecular sieve adsorber. Each tower bed is 3.5m high and contains activated alumina (lower layer, 1.0m high) and 13X molecular sieve (upper layer, 2.5m high). The conventional adsorption cycle is 4 hours. Regeneration is achieved using a pulse voltage swing process at a regeneration temperature of 170℃ and a regeneration time of 150 minutes.

[0038] Specifically: Step 1: 3-pulse transformer Open the adsorption tower discharge valve and perform pressure transformation according to the following pulse sequence: First rapid blood pressure reduction: 0.6 MPa → 0.3 MPa, rate of reduction: 0.3 MPa / min, time: 1 min; First brief pressurization: 0.3MPa→0.4MPa, pressurization rate 0.1MPa / min, time 1min; Second rapid pressure reduction: 0.4MPa→0.2MPa, pressure reduction rate 0.2MPa / min, time 1min; Second brief pressurization: 0.2MPa→0.3MPa, pressurization rate 0.1MPa / min, time 1min; The third rapid blood pressure reduction: 0.3 MPa → 0.1 MPa, with a reduction rate of 0.2 MPa / min, taking 1 minute; Step 2: Thermal wave purging for deep regeneration Maintaining the pressure inside the tower at 0.1 MPa, activate the fast-response induction heater to heat the purge gas (dirty nitrogen) from 30°C to 170°C. (5000 Nm³) 3 A high-temperature purge gas flow rate of / h (55% of the conventional regeneration gas flow rate) is introduced from the inlet of the adsorption tower. The hot wave propagates towards the outlet at a speed of 12 cm / min, with a width of 0.5 m (14% of the total bed height). When the temperature monitoring point at the outlet reaches 150°C, it is determined that the hot wave has completed its journey, the heater is turned off, and the supply of high-temperature purge gas is stopped. The total time for the hot wave purging phase is 23 minutes.

[0039] Step 3: Equalizing pressure charging Open the equalizing valve and use the gas from the other tower to raise the pressure of this tower from 0.1MPa to 0.3MPa in 3 minutes; close the equalizing valve and open the pressurizing valve to raise the pressure of this tower from 0.3MPa to 0.6MPa using the purified raw material air in 5 minutes.

[0040] Example 2 The difference from Example 1 is that the purge gas in step 2 is replaced with air separation product N2 instead of polluted nitrogen. The N2 is further dried to a dew point below -100°C (water vapor partial pressure <0.0014Pa) by a membrane dryer, and then the O2 content is reduced to below 1ppb by a palladium-based deoxygenation catalyst.

[0041] Step 2: Parameter Adjustment Purge gas: Ultra-dry N2 (dew point < -100℃, O2 < 1ppb); Heat wave temperature: 140℃ (the temperature can be lowered due to the enhanced partial pressure displacement effect of dry N2). Heat wave propagation speed: 14 cm / min; Total time for the heat wave purging phase: 20 minutes.

[0042] Example 3: Plasma-activated N2-assisted regeneration The difference from Example 2 is that in step 2, ultra-deep dried N2 is introduced into the DBD plasma generator before entering the adsorption tower. The DBD plasma generator adopts a coaxial dielectric barrier discharge structure, with a discharge frequency of 50kHz, a voltage of 15kV (peak), and a power density of 0.8W / cm³. 3 .

[0043] Step 2: Parameter Adjustment Purge gas: Deeply dried N2 (containing N· and N2) activated by DBD plasma + N2 * Active factors, NO X Concentration <1ppm); Thermal wave temperature: 80℃ (the temperature can be further reduced because the active agent can weaken the binding force between water molecules and the surface of the adsorbent). Heat wave propagation speed: 16 cm / min; Total time for the heat wave purging phase: 17 minutes.

[0044] Comparative Example 1: Traditional Craftsmanship Process conditions: Same as the device conditions in Example 1, using a uniform pressure reduction combined with full-bed heating and regeneration process.

[0045] Regeneration steps: Uniform pressure reduction: 0.6MPa→0.1MPa, pressure reduction rate 0.0625MPa / min, time 8min; Full bed heating: The waste nitrogen gas is heated to 170℃ and introduced from the inlet end, heating the entire bed simultaneously for 90 minutes. During the heating period, the temperature difference of the bed reaches 35-50℃. Cold blowing: Stop heating and continue to introduce ambient temperature waste nitrogen to cool the bed to below 30°C, which takes 60 minutes; Equalizing pressure: 0.1MPa→0.6MPa, time 12min.

[0046] Comparative Example 2: Only multiple pulse transformers, without thermal wave purging The difference from Example 1 is that only step 1 is performed, and step 2 is replaced by room temperature N2 purging (without heating).

[0047] Step 2 parameters: N2 purging at room temperature, temperature 30℃, flow rate 5000 Nm³. 3 / h, time 23min.

[0048] Comparative Example 3: Only thermal wave purging, without multiple pulse transformers Difference from Example 1: Skip step 1 and proceed directly to step 2 (thermal wave purging).

[0049] Step 2 parameters: Same as in Example 1.

[0050] Comparative Example 4: Uniform pressure reduction combined with thermal wave purging The difference from Example 1 is that the asymmetric voltage transformation in step 1 is replaced with uniform voltage reduction (0.6MPa→0.1MPa, uniform speed for 8min).

[0051] Step 1 parameters: uniform pressure reduction, pressure reduction rate 0.0625MPa / min, time 8min.

[0052] Comparative Example 5: Multiple pulse-type transformer combined with full-bed heating (without heat wave purging) The difference from Example 1 is that the heat wave purging in step 2 is replaced with traditional full-bed heating (170°C, constant temperature heating).

[0053] Step 2 parameters: Full bed heating, temperature 170℃, constant temperature for 60 minutes, followed by cold blowing for 40 minutes.

[0054] Comparative Example 6: Multiple pulse-type transformer purging combined with thermal wave purging (using conventional dirty nitrogen gas, without deep drying) The difference from Example 1 is that conventional polluted nitrogen (dew point -45°C) was used as the purging gas, and no deep drying treatment was performed.

[0055] Step 2 parameters: Same as in Example 1, but the purging gas is conventional dirty nitrogen (dew point -45°C).

[0056] The effects of each embodiment and comparative example are shown in the table below: Comparative Example 1 uses a traditional regeneration process, namely uniform pressure reduction combined with full-bed heating and cold blowing. Example 1 uses the "pulse-type pressure reduction combined with thermal wave purging" scheme proposed in this invention. Comparing the two under the same equipment conditions, as shown in the table above, the regeneration time of Example 1 is only 36 minutes, which is 78.8% shorter than the 170 minutes of Comparative Example 1. This is mainly due to two aspects: First, the pulse-type pressure reduction uses an asymmetric pressure change mode of "fast pressure reduction and slow pressure increase" to utilize the stress wave effect generated by the sudden pressure change to promote the rapid desorption of adsorbate from the molecular sieve surface, which greatly accelerates the desorption process compared to uniform pressure reduction; Second, the thermal wave purging adopts a directional propulsion method, which only heats the bed in the leading edge region of the thermal wave, rather than heating the entire bed at the same time. The thermal wave purging stage takes only 23 minutes, which is much shorter than the 90 minutes required for full-bed heating in Comparative Example 1. At the same time, it avoids the cold blowing stage (60 minutes for Comparative Example 1), because the bed temperature gradient is clear and the heat utilization efficiency is high under the thermal wave mode, and rapid cooling can be achieved without additional cold blowing.

[0057] In terms of energy consumption, the heating energy consumption of Example 1 is only 31.5% of that of Comparative Example 1, which is a reduction of 68.5%. This is because the heat wave purging only needs to heat about 14% of the gas in the bed height within the heat wave width range, and the purging gas flow rate is only 55% of the conventional regeneration gas flow rate, resulting in concentrated heat and less heat loss; while Comparative Example 1 requires heating the entire bed to 170°C simultaneously and for 90 minutes, resulting in serious heat waste.

[0058] Regarding regeneration quality, the residual moisture content of Example 1 was only 40% of that of Comparative Example 1, and the outlet CO2 decreased from 0.6 ppm to 0.5 ppm. This demonstrates that the present invention not only has a fast regeneration speed and low energy consumption, but also significantly better regeneration quality than traditional processes. The repeated stress alternation generated by pulsed pressure reduction helps to break the binding force between the adsorbate and the adsorbent. Combined with the directional propulsion of the thermal wave, it achieves segmented deep regeneration. The synergistic effect of both results in a more thorough regeneration of the molecular sieve.

[0059] Comparative Example 2 retains the pulsed pressure reduction steps of Example 1, but replaces the thermal wave purging with room temperature N2 purging (without heating).

[0060] Although Comparative Example 2 achieved a shorter regeneration time (37 min, comparable to 36 min in Example 1) through pulsed depressurization, demonstrating that pulsed depressurization can indeed effectively accelerate the desorption process and shorten the regeneration cycle, its regeneration quality was severely inadequate—the residual water content was as high as 6.8%, which is 6.8 times that of Example 1, and the outlet CO2 exceeded 1.0 ppm, which is more than twice that of Example 1, far from meeting the requirements for deep regeneration.

[0061] This comparison clearly demonstrates that the physical stress effect generated by pulsed pressure reduction alone is insufficient to achieve deep regeneration of molecular sieves; high-temperature purging is necessary to effectively remove water molecules and CO2 adsorbed deep within the micropores of the molecular sieve. While room-temperature purging can remove surface adsorbates to some extent, it cannot effectively desorb strongly bound adsorbates within the micropores of the molecular sieve without thermal energy. The thermal wave purging in Example 1, through the directional propulsion of high-temperature gas, provides sufficient thermodynamic driving force for adsorbate desorption, making it a crucial step in achieving deep regeneration.

[0062] Comparative Example 3 skipped the pulsed depressurization step and directly performed thermal purging. The thermal purging parameters of Comparative Example 3 were exactly the same as those of Example 1, so the regeneration time (38 min vs. 36 min) and heating energy consumption (31.5%) were basically the same, indicating that the pulsed depressurization step itself had almost no additional impact on heating energy consumption. However, in terms of regeneration quality, the residual moisture content of Comparative Example 3 (2.3) was 2.3 times that of Example 1 (1.0), and the outlet CO2 (0.8 ppm) was also 60% higher than that of Example 1 (0.5 ppm).

[0063] This comparison clearly demonstrates that pulsed depressurization plays an irreplaceable role in improving regeneration quality. The mechanism lies in the rapid pressure changes during pulsed depressurization, which generate stress alternation within the adsorbent particles. This stress alternation, similar to a breathing effect, promotes the release of strongly bound adsorbates, especially water molecules, from the micropores of the molecular sieve. Simultaneously, the asymmetric "fast depressurization, slow repressurization" mode causes the adsorption bed to undergo repeated pressurization-depressurization cycles. Each pressure drop further loosens the desorbed but not yet fully diffused adsorbate molecules into the gas flow, creating favorable conditions for subsequent thermal wave purging. After pulsed pretreatment, the thermal wave only needs to perform deep desorption, rather than heating the entire bed from scratch.

[0064] Comparative Example 4 retained the thermal wave purging, but replaced the pulsed pressure reduction with a uniform pressure reduction (pressure reduction rate 0.0625 MPa / min, time 8 min), and finally reduced the pressure to the same pressure of 0.1 MPa.

[0065] Comparative Example 4 used a uniform pressure reduction method, while Example 1 used a pulsed pressure reduction method. During the process of achieving the same pressure drop, the pressure reduction time was not significantly different between the two (5 min vs. 8 min), and the total regeneration time was also not significantly different (36 min vs. 38 min). However, Example 1 showed a clear advantage in regeneration quality: the residual moisture content was only 55.6% of that of Comparative Example 4 (1.0 vs. 1.8), and the outlet CO2 was 28.6% lower (0.5 ppm vs. 0.7 ppm).

[0066] This comparison demonstrates that the core advantage of pulsed depressurization lies not in shortening the depressurization time itself, but in the stress alternation effect generated by its unique "rapid depressurization and slow rise" asymmetric pressure-switching mode. During uniform depressurization, the pressure decreases steadily, and the stress change in the adsorption bed is gradual and unidirectional, failing to generate sufficient stress impact to disrupt the binding force between the adsorbate and the adsorbent. In contrast, pulsed depressurization generates a sharp pressure drop (depressurization rate 0.2–0.4 MPa / min) in each rapid depressurization phase, followed by a relatively slow pressure recovery (rise rate 0.05–0.15 MPa / min) in a brief rise phase. This asymmetric pressure-switching cycle generates an alternating stress field within the adsorbent particles, prompting the adsorbate to detach from the micropores, significantly improving the regeneration effect of subsequent thermal wave purging.

[0067] Comparative Example 5 retained the pulsed depressurization step, but replaced the thermal wave purging with traditional whole-bed constant temperature heating (170℃, constant temperature for 60 min + cold blowing for 40 min).

[0068] Although Comparative Example 5 also used pulsed pressure reduction for pretreatment, the regeneration time was as high as 115 min due to the use of traditional full-bed heating, including 60 min of constant temperature heating and 40 min of cold blowing, which is 3.2 times that of Example 1 (36 min); the heating energy consumption reached 131.5%, which is 76.0% higher than Example 1, and even exceeds 100% of the traditional process, because full-bed constant temperature heating requires a large amount of heat input.

[0069] It is worth noting that the two are basically equivalent in terms of regeneration quality (both have a residual moisture content of 1.0 and an outlet CO2 of 0.5 ppm), which indicates that thermal wave purging does not sacrifice regeneration quality while significantly shortening the time and reducing energy consumption.

[0070] The advantages of thermal wave purging lie in its mechanism of action: Traditional whole-bed heating requires simultaneous heating from the inlet to the entire bed, with heat gradually transferred from the bed surface to the interior, resulting in low heat transfer efficiency, significant heat loss, and an additional 60-minute cooling phase. Thermal wave purging, however, employs a directional propulsion method, heating only a thin area (only 0.5m wide, approximately 14% of the bed height) at the leading edge of the thermal wave. This results in concentrated heat, high utilization, and a purging gas flow rate that is only 55% of the conventional regeneration gas flow rate, thus significantly reducing energy consumption. Furthermore, because heat is gradually absorbed by the bed during the thermal wave propulsion process, the outlet temperature remains consistently low, allowing it to naturally return to near-normal temperature after regeneration without the need for an additional cooling step, thereby avoiding the time consumed by the cooling phase.

[0071] The only difference between Comparative Example 6 and Example 1 is that conventional dirty nitrogen (dew point -45°C) was used as the purging gas, and no deep drying treatment was performed.

[0072] Comparative Example 6 used conventional waste nitrogen gas with a dew point of -45°C, while the waste nitrogen gas in Example 1 underwent alumina pretreatment inside the adsorption tower, resulting in a lower actual moisture content. The residual moisture content (1.5) of Comparative Example 6 was 50% higher than that of Example 1 (1.0), and the outlet CO2 was also slightly higher (0.6 ppm vs. 0.5 ppm). This comparison illustrates that the dryness of the purge gas directly affects the regeneration quality. When the purge gas itself has a high water content, it still carries a significant amount of water vapor under high-temperature conditions. This reduces the water vapor partial pressure difference between the adsorbent surface and the gas flow, weakening the desorption driving force and causing some water molecules to be re-adsorbed back onto the molecular sieve surface, thus affecting the regeneration depth. Example 2 further utilizes a membrane dryer to dry the purge gas to a dew point below -100°C, reducing the residual water content to 0.3 ppm and the outlet CO2 to 0.3 ppm, further validating the gain effect of deep drying.

[0073] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

Claims

1. A method for regenerating a dual-bed molecular sieve adsorber, characterized in that, Includes the following steps: Step 1: Perform multiple pulsed pressure swing treatments on the adsorption tower that has reached adsorption saturation. Each pulse cycle includes a rapid pressure drop and a brief pressure increase, so that the pressure inside the tower gradually decreases to the final regeneration pressure according to a preset sequence. Step 2: Under the condition of maintaining the final regeneration pressure, high temperature purge gas is introduced from the inlet end of the adsorption tower to form a high temperature heat wave. This high temperature heat wave is pushed from the inlet end to the outlet end in the form of a wave to regenerate the adsorbent bed segment by segment. Step 3: Close the discharge valve and restore the pressure inside the adsorption tower to the adsorption pressure, so that the adsorption tower returns to the adsorption working state.

2. The regeneration method for a dual-bed molecular sieve adsorber as described in claim 1, characterized in that, In step 1, the pulse cycle of the pulse-type transformer treatment is 2 to 5 times. In each pulse cycle, the rapid pressure reduction rate is 0.15 to 0.4 MPa / min, and the brief pressure increase rate is 0.05 to 0.15 MPa / min, so that the pressure inside the tower decreases to the final regeneration pressure P5 according to the pulse decreasing sequence. The final regeneration pressure P5 is 0.05 to 0.15 MPa.

3. The regeneration method for the dual-bed molecular sieve adsorber as described in claim 1, characterized in that, The specific operation process for step 1 is as follows: Step 11: Open the discharge valve of the adsorption tower to rapidly reduce the pressure inside the tower from the adsorption pressure P0 to the first intermediate pressure P1. The pressure reduction rate is 0.2-0.4 MPa / min, and the pressure reduction time is 0.5-1.5 minutes. Step 12: Close the discharge valve slightly to allow the pressure inside the tower to rise from P1 to the second intermediate pressure P2. The pressure increase rate is 0.05 to 0.15 MPa / min, and the pressure increase time is 0.5 to 1.5 minutes. Step 13: Open the discharge valve again to rapidly reduce the pressure inside the tower from P2 to the third intermediate pressure P3. The pressure reduction rate is 0.15-0.3 MPa / min, and the pressure reduction time is 0.5-1.5 minutes. Step 14: Close the discharge valve slightly to allow the pressure inside the tower to rise from P3 to the fourth intermediate pressure P4. The pressure increase rate is 0.05 to 0.15 MPa / min, and the pressure increase time is 0.5 to 1.5 minutes. Step 15: Open the discharge valve again to rapidly reduce the pressure inside the tower from P4 to the final regeneration pressure P5. The pressure reduction rate is 0.15-0.3 MPa / min, and the pressure reduction time is 0.5-1.5 minutes.

4. The regeneration method for the dual-bed molecular sieve adsorber as described in claim 1, characterized in that, The specific operation process for step 2 is as follows: Step 21: Turn on the fast-response heater installed on the inlet pipe of the adsorption tower to heat the purge gas from room temperature to the target regeneration temperature T1; Step 22: Introduce high-temperature purging gas heated to T1 into the inlet of the adsorption tower at a preset flow rate Q, and maintain the pressure inside the tower at P5; Step 23: High-temperature purge gas enters the adsorption tower from the inlet end, forming a high-temperature heat wave in the bed; the high-temperature heat wave advances towards the outlet end at a speed of 5-15 cm / min; The gas temperature inside the heat wave is T1±10℃; The width of the heat wave is 10% to 20% of the total height of the bed. After the heat wave passes through, the bed temperature in the inlet area is 50-60℃, and the bed temperature in the outlet area is 30-50℃. Step 24: Set up several temperature monitoring points along the axial direction of the adsorption tower and monitor the temperature changes of each monitoring point in real time; when the temperature of a certain monitoring point reaches T1-20℃, it is determined that the high temperature heat wave has passed through the cross section where the monitoring point is located. Step 25: When the temperature monitoring point at the outlet reaches T1-20℃, it is determined that the high-temperature heat wave has passed through the entire bed, and the high-temperature purging gas is stopped.

5. The regeneration method for a dual-bed molecular sieve adsorber as described in claim 1, characterized in that, The purging gas is nitrogen, which is then deeply dried and heated to T1.

6. The regeneration method for a dual-bed molecular sieve adsorber as described in claim 5, characterized in that, The nitrogen gas is deeply dried, then activated by plasma, and then heated to T1.

7. The regeneration method for a dual-bed molecular sieve adsorber as described in claim 6, characterized in that, In step 2, the nitrogen gas is deeply dried to a dew point below -100°C. During nitrogen plasma activation, the discharge frequency is 40–60 kHz, the voltage is 10–20 kV, and the power density is 0.5–1.0 W / cm³. 3 The activated nitrogen gas contains active factors including N· and N2. + N2 * , and NO X Concentration < 1 ppm.

8. The regeneration method for a dual-bed molecular sieve adsorber as described in claim 1, characterized in that, Step 3 is performed as follows: Step 31: Open the pressure equalization valve and use the gas in another adsorption tower that is in the adsorption state to equalize and pressurize the regenerated adsorption tower, so that the pressure in the tower rises from P5 to the first intermediate pressurization pressure P6. Step 32: Close the equalizing valve and open the pressurizing valve to use the purified raw material air to finally pressurize the adsorption tower, so that the pressure inside the tower rises from P6 to the adsorption pressure P0.

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