A three-column pressure swing adsorption apparatus and displacement process

Abstract

The application discloses a three-tower series connection pressure swing adsorption device and a displacement process. While ensuring that product gas of a difficult-to-adsorb component reaches the quality requirement of high-purity gas, the device can only adopt a first-stage pressure swing adsorption device, so that the product gas yield of the difficult-to-adsorb component reaches or exceeds the product gas yield of a second-stage or more than two-stage pressure swing adsorption device commonly used at present. Meanwhile, the device provided by the application can also obtain product gas of an easy-to-adsorb component with high purity and high yield.

Description

Technical Field

[0001] This invention relates to pressure swing adsorption (PSA) gas separation technology, specifically to a three-tower series PSA device and a displacement process. Background Technology

[0002] Pressure Swing Adsorption (PSA) technology has been used in gas separation and purification for over seventy years, and is widely applied in various industries requiring gas separation. Examples include PSA for nitrogen production (separating nitrogen from air), PSA for oxygen production (separating oxygen from air), and PSA for hydrogen production (separating and purifying hydrogen from refinery gas). PSA technology utilizes PSA units. Currently, most PSA units in use, when in adsorption mode, involve the feed gas passing through only one adsorption tower from its entry into the adsorption tower to the acquisition of the target product gas. Additionally, some systems employ multi-stage PSA units. However, multi-stage PSA units are actually two or more PSA units connected in series. An intermediate product gas is obtained through a pre-stage PSA unit, and the target product gas is obtained through a final stage PSA unit. Therefore, in multi-stage PSA units, the feed gas also actually passes through only one adsorption tower.

[0003] Chinese invention patent CN00113035.8 discloses a pressure swing adsorption (PSA) process that uses multiple adsorption towers connected in series to maintain a constant amount of adsorbent while reducing the total amount of adsorbent, resulting in smaller equipment size and lower operating energy consumption. The adsorption process consists of two or more stages, with the direction of the adsorbed gas flow changing back and forth according to a specific pattern. Furthermore, when the depressurized effluent from the adsorption tower flows back into the tower, the distribution of easily adsorbed components within the tower becomes more rational. In this process, the adsorption towers are connected in series by connecting the outlet of the first tower to the outlet of the second tower, the inlet of the second tower to the inlet of the third tower, and the outlet of the third tower to the outlet of the fourth tower, and so on. In addition to series connections, adsorption towers in the adsorption state may also be connected in parallel. Each tower experiences multiple adsorption states, which are continuous. The gas flow direction within the tower needs to be reversed at different adsorption stages. In this method, when the product gas is a difficult-to-adsorb component, the purity of the product gas varies and it is difficult to guarantee a high purity. Furthermore, the product gas flow is discontinuous. In this patent, the adsorbent in the adsorption tower is already saturated or nearly saturated before the pressure is reduced. During the pressure reduction, the gas in the adsorption tower is first discharged into multiple empty tanks, and then pressure is equalized with other adsorption towers. When the gas is discharged into the empty tanks, a large amount of easily adsorbed components will desorb from the adsorbent and be discharged into the empty tanks. When pressure is equalized, a large amount of components discharged into the pressure equalization and boosting adsorption tower are easily adsorbed gases. As a result, the purity of the product gas containing the difficult-to-adsorb component cannot meet the requirements for high-purity gas quality.

[0004] Chinese invention patent CN103695063A discloses a method for concentrating low-concentration methane gas. This method involves concentrating the low-concentration methane gas using a pressure swing adsorption (PSA) process. N (N≥3) adsorption towers are used for adsorption, each containing adsorbent. Within one adsorption cycle, N adsorption stages are performed, with each tower undergoing N-1 series adsorption cycles. After the N towers in series are pressurized in each adsorption stage, the tower that has undergone N-1 adsorption cycles is flushed and displaced, then vacuumed for desorption. The remaining N-1 towers are then pressurized in reverse to the adsorption pressure and undergo adsorption again. This cycle completes one adsorption cycle. In this patent, the adsorption towers are connected end-to-end, and the number of towers simultaneously in series adsorption is the total number of towers minus one. This patent targets easily adsorbed components as the product gas, which can significantly increase the content of these components. Even with low purity of the difficult-to-adsorb components, the easily adsorbed components in the target product can achieve a high yield. However, to ensure high purity of the difficult-to-adsorb components, the yield of the easily adsorbed components in the target product gas will inevitably decrease. The process technology in this patent results in discontinuous gas flows for the easily and difficult-to-adsorbed components, which may cause pressure fluctuations between them. When pressure equalization and counter-pressurization are performed between adsorption towers, the feed gas does not enter any of the adsorption towers, leading to a buildup of feed gas pressure. Furthermore, this patent only allows for one pressure equalization operation and cannot significantly improve the yield of the difficult-to-adsorbed components.

[0005] Chinese invention patent CN102423602A discloses a series adsorption gas separation process that ensures the product gas discharged from the adsorption towers maintains a consistently high concentration. It overcomes the shortcomings of existing technologies where product gas is discharged after only one adsorption tower, resulting in low purity. This process uses at least six adsorption towers working together in a cyclic adsorption process. Simultaneously, each adsorption tower completes one step. The raw material gas enters the first adsorption tower sequentially through a valve, where impurities are adsorbed by the adsorbent to obtain intermediate gas. This intermediate gas then flows out through a valve and into the second adsorption tower, where impurities are adsorbed by the adsorbent to obtain product gas. The product gas then flows out through a valve and enters the next stage. The raw material gas undergoes one adsorption step to obtain intermediate gas, which is then adsorbed again to obtain product gas, resulting in a high purity of the product gas. This patent uses two adsorption towers in series to adsorb easily adsorbed components from the raw material gas, obtaining a product of high purity but difficult-to-adsorb components. However, this technical solution cannot simultaneously guarantee high purity of both easily and difficult-to-adsorb components while achieving extremely high yields for both. Summary of the Invention

[0006] To address the aforementioned technical problems, this invention proposes a three-tower series pressure swing adsorption (PSA) device and a displacement process. While ensuring that the product gas quality of the difficult-to-adsorb components meets the requirements for high-purity gas, it can use only a single-stage PSA device to achieve a product gas yield of the difficult-to-adsorb components that meets or exceeds the product gas yield of the two-stage or three-stage PSA devices commonly used in the prior art. At the same time, it can obtain a high-purity, high-yield product gas of the easily adsorbed components.

[0007] The objective of this invention is achieved through the following technical solution: a three-tower series pressure swing adsorption device and a displacement process, comprising at least nine adsorption towers and corresponding valves and fittings, wherein the adsorption towers are connected in series and parallel.

[0008] Each adsorption tower is controlled by 16 valves to switch between various states.

[0009] The lower interface of the adsorption tower is connected to 9 valves, and the upper interface is connected to 7 valves.

[0010] Preferably, the nine valves connected to the lower interface of the adsorption tower include: The gas from the outlet of the secondary adsorption tower enters the primary adsorption tower through the primary adsorption inlet valve; the primary adsorption inlet valves of each adsorption tower are connected in parallel through adsorption pipeline 2. The secondary adsorption inlet valve allows gas from the outlet of the tertiary adsorption tower to enter the secondary adsorption tower; the secondary adsorption inlet valves of each adsorption tower are connected in parallel through adsorption pipeline 1. The feed gas enters the adsorption tower through the three-stage adsorption inlet valve. The three-stage adsorption inlet valves of each adsorption tower are connected in parallel through the feed gas pipeline. The gas from the outlet of the primary displacement adsorber enters the displacement adsorber through the displacement gas pressure boosting inlet valve. The displacement gas pressure boosting inlet valves of each adsorption tower are connected in parallel through displacement pipelines. The displacement gas inlet valve allows the displacement gas to enter the displacement adsorber. The displacement gas inlet valves of each adsorption tower are connected in parallel through the displacement gas pipeline. The reverse exhaust valve is used to discharge the gas inside the adsorption tower when the adsorption tower is in the reverse depressurization process. The reverse exhaust valves of each adsorption tower are connected in parallel through the reverse pipeline. When the adsorption tower is in a vacuum and depressurization state, the gas inside the adsorption tower is discharged from the adsorption tower through the extraction and exhaust valve. The extraction and exhaust valves of each adsorption tower are connected in parallel through extraction pipelines. The gas from the outlet of the secondary pressure equalization and depressurization adsorption tower enters the primary pressure equalization and depressurization adsorption tower through the primary pressure equalization and depressurization inlet valve; the gas from the outlet of the secondary displacement gas adsorption tower enters the primary displacement gas adsorption tower through the primary pressure equalization and depressurization inlet valve; the primary pressure equalization and depressurization inlet valves of each adsorption tower are connected in parallel through the pressure equalization pipeline 2. The secondary equalization and depressurization inlet valve allows gas from the outlet of the tertiary equalization and depressurization adsorption tower to enter the secondary equalization and depressurization adsorption tower; gas from the outlet of the displacement adsorption tower also enters the secondary displacement gas adsorption tower through the secondary equalization and depressurization inlet valve; the secondary equalization and depressurization inlet valves of each adsorption tower are connected in parallel through equalization pipeline 1.

[0011] Preferably, the seven valves connected to the upper interface of the adsorption tower include: The tertiary adsorption exhaust valve connects the tertiary adsorption tower, the secondary adsorption tower, and the primary adsorption tower in series via the tertiary adsorption exhaust valve, the secondary adsorption inlet valve, and the primary adsorption inlet valve; the tertiary adsorption exhaust valve of each adsorption tower is connected in parallel via adsorption pipeline 1. The gas inside the secondary adsorption tower is discharged into the primary adsorption tower through the secondary adsorption exhaust valve. Inside, the secondary adsorption exhaust valves of each adsorption tower are connected in parallel through adsorption pipeline 2; The primary adsorption exhaust valve allows the gas inside the primary adsorption tower to be discharged from the adsorption tower, serving as a difficult-to-clean exhaust valve. The adsorbed component product gas is discharged into the difficult-to-adsorb component product gas pipeline, and the primary adsorption exhaust valve of each adsorption tower is connected in parallel through the difficult-to-adsorb component product gas pipeline. Three-stage pressure equalization and depressurization exhaust valve, three-stage pressure equalization and depressurization adsorption tower, two-stage pressure equalization and depressurization adsorption tower, and one-stage pressure equalization and depressurization adsorption tower The adsorbers are connected in series via a three-stage equalization exhaust valve, a two-stage equalization inlet valve, a two-stage equalization exhaust valve, and a one-stage equalization inlet valve. The displacement gas from the outlet of the displacement adsorption tower is discharged into the two-stage displacement gas adsorption tower through the three-stage equalization exhaust valve. The displacement adsorption tower, the two-stage displacement gas adsorption tower, the one-stage displacement gas adsorption tower, and the displacement gas pressurization adsorption tower are connected in series during the displacement state via a three-stage equalization exhaust valve, equalization pipeline 1, a two-stage equalization inlet valve, a two-stage equalization exhaust valve, equalization pipeline 2, a one-stage equalization inlet valve, and a one-stage equalization exhaust valve (or a displacement pipeline and a displacement gas pressurization inlet valve). The three-stage equalization exhaust valves of each adsorption tower are connected in parallel via equalization pipeline 1. The gas in the secondary pressure equalization and depressurization adsorption tower is discharged into the primary pressure equalization and depressurization adsorption tower through the secondary pressure equalization and depressurization valve; the gas from the outlet of the secondary replacement gas adsorption tower is discharged into the primary replacement gas adsorption tower through the secondary pressure equalization and depressurization valve; the secondary pressure equalization and depressurization valves of each adsorption tower are connected in parallel through the pressure equalization pipeline 2. The gas in the primary pressure equalization and depressurization adsorption tower is discharged into the pressure equalization and pressurization adsorption tower through the primary pressure equalization and depressurization exhaust valve; the gas from the outlet of the primary displacement gas adsorption tower is discharged into the displacement gas pressurization adsorption tower through the primary pressure equalization and depressurization exhaust valve; the primary pressure equalization and depressurization exhaust valves of each adsorption tower are connected in parallel through displacement pipelines. The reverse riser valve allows the reverse pressurized gas to enter the adsorption tower that requires reverse pressurization. The reverse riser valves of each adsorption tower are connected in parallel through the reverse riser gas pipeline.

[0012] In addition to providing a three-tower series pressure swing adsorption (PSA) device, this invention further provides a three-tower series PSA displacement process, which is achieved by using the aforementioned three-tower series PSA device: In a three-tower series pressure swing adsorption unit, when the pressure swing adsorption process is used to separate and purify the gas displacement state, four adsorption towers are connected in series to complete the displacement process. In the displacement state, three of the four adsorption towers are connected in series, one end to the other. The adsorption tower upstream in the series connection is the first adsorption tower, the adsorption tower in the middle is the second adsorption tower, and the adsorption tower downstream is the third adsorption tower. The upper interface of the third adsorption tower is then connected to the upper or lower interface of the fourth adsorption tower, thus realizing the series connection of the four adsorption towers. The series connection method of the first, second, and third adsorption towers is the same as the series connection method when these three adsorption towers are in the adsorption state and the pressure equalization and depressurization state. In the displacement state, the first adsorption tower is the adsorption tower being displaced, the second adsorption tower receives the gas components flowing from the first adsorption tower, the third adsorption tower receives the gas components flowing from the second adsorption tower, and the fourth adsorption tower receives the gas components flowing from the third adsorption tower. In the adsorption state, the two adsorption towers are connected in series, end to end. The feed gas enters the first adsorption tower from the lower inlet. The adsorption tower is filled with one or more adsorbents that have a good adsorption effect on easily adsorbed components. For example, carbon molecular sieves are used in pressure swing adsorption nitrogen generators, oxygen molecular sieves are used in pressure swing adsorption oxygen generators, and activated carbon or silica gel with a good adsorption effect on carbon dioxide, or 5A molecular sieve with a good adsorption effect on carbon monoxide, etc., are used in pressure swing adsorption hydrogen generators. After the feed gas comes into contact with the adsorbent bed, the easily adsorbed components are adsorbed by the corresponding adsorbents and separated from the feed gas. Most of the difficult-to-adsorb components and a small portion of the easily adsorbed components flow out of the first adsorption tower from the upper inlet. One adsorption tower is in a tertiary adsorption state. Gas flowing out of the adsorption tower in the tertiary adsorption state continues to enter the adsorption tower through the lower interface of the second adsorption tower in the adsorption state. Most of the easily adsorbed components in the gas are adsorbed by the adsorbent in the adsorption tower, while most of the difficult-to-adsorb components and trace amounts of easily adsorbed components flow out of the adsorption tower through the upper interface. The second adsorption tower is in a secondary adsorption state. Gas flowing out of the adsorption tower in the secondary adsorption state continues to enter the adsorption tower through the lower interface of the third adsorption tower in the adsorption state. The difficult-to-adsorbed components pass through the adsorbent bed and flow out of the adsorption tower through the upper interface, resulting in a product gas of difficult-to-adsorbed components that meets the quality requirements of high-purity gas. The third adsorption tower is in a primary adsorption state. When the adsorption tower is in the adsorption state, the adsorbent inside the tower will exhibit three state zones: the adsorbent bed that has reached saturation adsorption capacity is the saturation zone; the adsorbent bed that has adsorbed some easily adsorbed components but has not yet reached saturation adsorption capacity is the mass transfer zone; and the adsorbent bed that has not yet adsorbed easily adsorbed components is the blank zone. The three state zones are arranged sequentially along the airflow direction. As the adsorption time increases, the three state zones gradually move towards the upper interface of the adsorption tower. Within one cycle, each adsorption tower undergoes three adsorption states; correspondingly, within one cycle, each adsorption tower undergoes three pressure equalization and depressurization states. Each regenerated adsorption tower first enters one adsorption state, then enters a second adsorption state, and then enters a third adsorption state. The pressure equalization and depressurization state after the first adsorption state is called the first pressure equalization and depressurization state, after the second adsorption state it is called the second pressure equalization and depressurization state, and after the third adsorption state it is called the third pressure equalization and depressurization state. Before entering the first adsorption state after three pressure equalization and depressurization states, it must go through three pressure increase states: pressure equalization and pressure increase by replacement gas and one reverse pressure increase. Before entering the second adsorption state after one pressure equalization and depressurization state, it must go through two reverse pressure increases and one pressure increase state. Before entering the third adsorption state after two pressure equalization and depressurization states, it must go through three reverse pressure increases and one pressure increase state.

[0013] When the mass transfer zone moves out of the adsorption tower in the tertiary adsorption state and into the adsorption tower in the secondary adsorption state, the current adsorption state of these three adsorption towers ends. At this time, the mass transfer zone is located at the bottom of the adsorption tower in the secondary adsorption state, closest to the lower interface. There is still a large amount of adsorbent in the upper part of the mass transfer zone, which is a blank area. Therefore, it can be ensured that the quality of the product gas of the difficult-to-adsorb component flowing out of the adsorption tower in the primary adsorption state meets the quality requirements of high-purity gas. When the adsorption state ends, the adsorbent bed in the adsorption tower into which the raw gas directly enters has become a saturated zone and no longer has the adsorption function. The gas composition remaining in the voids of the adsorption tower is the same as that of the raw gas and still contains a large amount of difficult-to-adsorb components. If these gases are directly discharged from the device, a large amount of difficult-to-adsorb components will be discharged, and the yield of difficult-to-adsorb components will be greatly reduced. In order to recover this part of the difficult-to-adsorb components, a pressure equalization process is set after the adsorption state ends. During the pressure reduction phase, the three adsorption towers, originally in the adsorption phase, continue in series, connected end-to-end. The difficult-to-adsorb components in the third adsorption tower flow out from the top interface and directly into the equalization and pressure-boosting adsorption tower from the top interface. Most of the easily adsorbed components in the voids of the second adsorption tower, as well as those desorbed from the adsorbent during the pressure reduction process, are adsorbed by the adsorbent in the mass transfer zone and blank zone. Most of the difficult-to-adsorbed components and a small portion of the easily adsorbed components in the voids of the second adsorption tower flow out from the top interface and then enter the third adsorption tower from the bottom interface. The easily adsorbed components are adsorbed by the adsorbent, while the difficult-to-adsorbed components and trace amounts of easily adsorbed components flow out from the top interface of the third adsorption tower. The gas flows out from the upper interface of the first adsorption tower and into the second adsorption tower, which is in a state of equal pressure and pressure increase. The gas in the void of the first adsorption tower and the easily adsorbed components desorbed from the adsorbent during the equal pressure and pressure decrease process flow out of the adsorption tower from the upper interface of the first adsorption tower and then flow into the second adsorption tower from the lower interface. Most of the easily adsorbed components are adsorbed by the adsorbent, and most of the difficult-to-adsorb components and a small part of the easily adsorbed components flow out of the adsorption tower from the upper interface of the second adsorption tower and enter the third adsorption tower from the lower interface. The easily adsorbed components are adsorbed by the adsorbent, and the difficult-to-adsorb components and trace amounts of easily adsorbed components flow out from the upper interface of the third adsorption tower and flow into the equal pressure and pressure increase adsorption tower from the upper interface of the adsorption tower, which is in a state of equal pressure and pressure increase. During pressure equalization, gas from the high-pressure adsorption tower will flow into the low-pressure adsorption tower, causing the pressure in the high-pressure adsorption tower to decrease (this is called pressure equalization depressurization), and the pressure in the low-pressure adsorption tower to increase (this is called pressure equalization boosting). During pressure equalization depressurization, easily adsorbed components adsorbed on the adsorbent will gradually desorb from the adsorbent as the pressure decreases. The desorbed easily adsorbed components will push and follow the gas in the adsorption tower voids towards the upper interface of the adsorption tower. Since the adsorbent in the adsorption tower that was originally in the tertiary adsorption state no longer has adsorption capacity, the desorbed easily adsorbed components will flow out of the adsorption tower along with the original gas in the adsorption tower voids. If the adsorption tower that has just finished the tertiary adsorption state is used directly to equalize the pressure of the adsorption tower that needs pressure equalization boosting, a large amount of easily adsorbed components will flow into the adsorption tower that needs pressure equalization boosting, which will have a significant impact on the purity of the difficult-to-adsorb components in the product gas. During pressure equalization and depressurization, most of the easily adsorbed components entering the second adsorption tower are adsorbed by the adsorbent in the blank zone. A small portion of the easily adsorbed components, along with the difficult-to-adsorb components, flow out from the upper interface of the second adsorption tower and enter the third adsorption tower. The easily adsorbed components are adsorbed by the adsorbent in the third adsorption tower. The majority of the gas flowing out from the upper interface of the third adsorption tower consists of difficult-to-adsorb components, while also containing trace amounts of easily adsorbed components. The quality of this latter portion of gas is equivalent to that of the difficult-to-adsorb component product gas. This latter portion of gas flows into the adsorption tower under pressure equalization and depressurization conditions and will not affect the quality of the difficult-to-adsorb component product gas, thus ensuring the quality of the difficult-to-adsorb components. The product gas quality meets the requirements for high-purity gas. At the same time, since the adsorbent in the first adsorption tower has no adsorption capacity when the adsorption state ends, the easily adsorbed components desorbed from the adsorbent in the first adsorption tower will all flow into the second adsorption tower. During the process of the easily adsorbed components flowing into the second adsorption tower, the easily adsorbed components will push the gas components that were originally in the voids of the first adsorption tower into the second adsorption tower. When the pressure equalization and depressurization state ends, most of the gas in the voids of the first adsorption tower is the easily adsorbed component, thus ensuring that the product gas of the difficult-to-adsorb components can obtain a high yield. In the displacement state, the three adsorption towers, originally in the pressure equalization and depressurization state, continue to be connected in series, as in the pressure equalization and depressurization state. The displacement gas enters the first adsorption tower from the lower inlet. The easily adsorbed components and a small amount of difficult-to-adsorb components that were originally in the voids of the adsorption tower are pushed out of the adsorption tower from bottom to top by the displacement gas through the upper inlet. The first adsorption tower is in the displacement state. The gas that has been pushed out then enters the second adsorption tower from the lower inlet. Most of the easily adsorbed components are adsorbed by the adsorbent. In the mass transfer zone and blank zone, adsorption occurs. The difficult-to-adsorb components and a small amount of easily adsorbed components flow out of the second adsorption tower from the upper interface, placing the second adsorption tower in a secondary displacement gas adsorption state. The gas flowing out of the second adsorption tower then enters the third adsorption tower from the lower interface. Easily adsorbed components are adsorbed by the adsorbent, while the difficult-to-adsorb components and trace amounts of easily adsorbed components flow out of the third adsorption tower from the upper interface, placing the third adsorption tower in a primary displacement gas adsorption state. The gas flowing out of the third adsorption tower then... The gas flows into the fourth adsorption tower from either the upper or lower inlet, placing it in a pressurized state. The quality of the gas flowing into the fourth adsorption tower is equivalent to that of the difficult-to-adsorb component product gas, ensuring that it does not affect the quality of the difficult-to-adsorb component product gas and thus guaranteeing that the quality of the difficult-to-adsorb component product gas meets the requirements for high-purity gas. The displacement gas pushes the small amount of difficult-to-adsorb components remaining in the voids of the first adsorption tower after the pressure equalization and depressurization process into the second adsorption tower. After the displacement state, the components remaining in the voids of the first adsorption tower are high-purity easily adsorbed components. These easily adsorbed components, along with the easily adsorbed components desorbed from the adsorbent during the reverse depressurization and vacuum depressurization processes, are pressurized by the compressor and used as the easily adsorbed component product gas output device. Since only a small amount of difficult-to-adsorbed components remain in the voids of the first adsorption tower after the pressure equalization and depressurization process, only a small amount of displacement gas is needed to push the difficult-to-adsorbed components out of the first adsorption tower. The pressurization of the displacement gas consumes only a small amount of energy and will not cause a significant increase in the energy consumption of the entire system.

[0014] In the displacement state, adsorption state, and pressure equalization and reduction state, the airflow direction in the three adsorption towers connected end to end is completely consistent.

[0015] Preferably, the product gas containing easily adsorbed components is used as the replacement gas, and the resulting flow of product gas containing difficult-to-adsorb components is continuous.

[0016] Within one cycle, after each adsorption tower completes the desorption and pressurization phases, it sequentially undergoes the following functional states: primary adsorption, primary pressure equalization and depressurization, primary displacement gas adsorption, secondary reverse pressurization, secondary adsorption, secondary pressure equalization and depressurization, secondary displacement gas adsorption, tertiary reverse pressurization, tertiary adsorption, tertiary pressure equalization and depressurization, displacement, reverse depressurization, vacuum depressurization, displacement gas pressurization, pressure equalization and pressurization, and primary reverse pressurization; then it re-enters the primary adsorption phase. These states cycle repeatedly to ensure continuous production. The easily adsorbed components discharged from the adsorption tower during reverse depressurization and vacuuming are the easily adsorbed component product gas. Apart from these two processes, there is no easily adsorbed component discharge device during the entire operation, thus ensuring that the easily adsorbed component product gas can achieve a near 100% yield.

[0017] Compared with the prior art, the present invention has the following advantages: In existing technologies, if the easily adsorbed component is a medium with a small adsorption capacity, in order to obtain a higher yield of the difficult-to-adsorb component while ensuring that the purity of the difficult-to-adsorb component meets the usage requirements, some operating conditions often require the use of two or three stages of pressure swing adsorption devices in series, which also increases the number of adsorption towers. The present invention uses a single pressure swing adsorption device, sets up a multi-step pressure equalization process, and adopts a three-adsorption tower simultaneous adsorption method. While ensuring the quality of the product gas, it significantly improves the yield, reduces energy consumption and equipment investment, and can simultaneously obtain a high-purity, high-yield product gas of the easily adsorbed component.

[0018] For pressure swing adsorption (PSA) hydrogen extraction devices, under the premise that the purity of the product hydrogen (≥99.999%) and the impurity content (N2≤5ppm, CO≤1ppm, CO2≤1ppm, CH4≤1ppm, H2O≤3ppm) meet the requirements for high-purity hydrogen in GB / T3634.2-2011, the product hydrogen yield is significantly higher than that of existing single-stage PSA hydrogen extraction devices. For example, for chlor-alkali gas purification hydrogen extraction devices, the highest product hydrogen yield of existing PSA devices is about 92%. Using the method in this invention, the product hydrogen yield can reach over 98% by solvent method calculation. The product hydrogen yield value is obtained as follows: the purity of the feed gas and product hydrogen is analyzed by gas chromatography, and the feed gas flow rate and product hydrogen production are measured by the volumetric method in Appendix A of GB / T19773-2005. The product hydrogen yield value is then obtained by dividing the product hydrogen production by the amount of hydrogen in the feed gas. For pressure swing adsorption (PSA) oxygen and nitrogen generators, provided that the oxygen purity (≥90%) and nitrogen purity (≥99.5%) meet the basic parameter requirements in JB / T6427-2015, the unit power consumption for oxygen production and the unit power consumption for nitrogen production are significantly lower than the minimum requirements in JB / T6427-2015; for example, for a product oxygen pressure of 0.2 MPa and a gas production rate of 200 m³ / h. 3For a PSA oxygen generator with a capacity of [number] m³ / h, the standard specifies a unit oxygen production power consumption of ≤1.0 kW·h / m³. 3 Using the method of this invention, the unit oxygen production power consumption is ≤0.6kW·h / m³. 3 For a product with an oxygen pressure of 0.005 MPa and a gas production rate of 8000 m³ / h... 3 For an axial flow VPSA oxygen generator with a capacity of [number] m³ / h, the minimum power consumption per unit oxygen production in the standard is 0.35 kW·h / m³. 3 Using the method of this invention, the unit oxygen production power consumption is ≤0.25kW·h / m³. 3 For a gas production rate of 3000m³ 3 For a PSA nitrogen generator with a capacity of [number] m³ / h, the standard specifies a unit nitrogen production power consumption of ≤0.43 kW·h / m³. 3 Using the method of this invention, the unit nitrogen production power consumption is ≤0.29kW·h / m³. 3 The above unit oxygen production power consumption and unit nitrogen production power consumption values ​​were obtained by measurement and calculation in accordance with the provisions of JB / T6427. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of a three-tower series pressure swing adsorption displacement device in an embodiment of the present invention. Detailed Implementation

[0020] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and not intended to limit it. Furthermore, it should be noted that, for ease of description, the accompanying drawings show only the parts relevant to the present invention, and not all of the structures.

[0021] The present invention provides a three-tower series pressure swing adsorption device and a displacement process. The applicable three-tower series pressure swing adsorption device for this process is as follows: Figure 1 As shown, it includes: There are at least 9 adsorption towers and corresponding valves and fittings, and the adsorption towers are connected in series and parallel.

[0022] Each adsorption tower is controlled by 16 valves to switch between various states.

[0023] The 16 valves are numbered 1-16. The complete valve tag number is formed by prefixing the number with the corresponding adsorption tower code, such as A1, A2, ..., A16, B1, B2, ..., B16. Valves with the same number have the same function, and their connection methods and functions are as follows: There are nine valves connected to the lower interface of the adsorption tower, namely: The primary adsorption inlet valves A7, B7, ..., I7 allow gas from the outlet of the secondary adsorption tower to enter the primary adsorption tower. The primary adsorption inlet valves of each adsorption tower are connected in parallel through adsorption pipeline 2. Secondary adsorption inlet valves A8, B8, ..., I8 allow gas from the outlet of the tertiary adsorption tower to enter the secondary adsorption tower; the secondary adsorption inlet valves of each adsorption tower are connected in parallel through adsorption pipeline 1. The three adsorption inlet valves A1, B1, ..., I1 allow the raw gas to enter the three adsorption tower. The three adsorption inlet valves of each adsorption tower are connected in parallel through the raw gas pipeline. Displacement gas boosting inlet valves A4, B4, ..., I4 allow gas from the outlet of the primary displacement adsorber to enter the displacement gas boosting adsorber. The displacement gas boosting inlet valves of each adsorption tower are connected in parallel through displacement pipelines. Replacement gas inlet valves A2, B2, ..., I2, through which replacement gas enters the replacement adsorber. The replacement gas inlet valves of each adsorption tower are connected in parallel through replacement gas pipelines. The reverse exhaust valves A3, B3, ..., I3 are used to discharge the gas in the adsorption tower during the reverse depressurization process. The reverse exhaust valves of each adsorption tower are connected in parallel through the reverse pipeline. The gas inside the adsorption tower is discharged through the extraction and exhaust valves A16, B16, ..., I16 when the adsorption tower is in a vacuum and pressure reduction state. The extraction and exhaust valves of each adsorption tower are connected in parallel through extraction pipelines. Gas from the outlet of the secondary pressure equalization and depressurization adsorption tower enters the primary pressure equalization and depressurization adsorption tower through the primary equalization and depressurization inlet valves A5, B5, ..., I5; gas from the outlet of the secondary displacement gas adsorption tower enters the primary displacement gas adsorption tower through the primary equalization and depressurization inlet valves; the primary equalization and depressurization inlet valves of each adsorption tower are connected in parallel through equalization pipeline 2. Secondary equalization and depressurization inlet valves A6, B6, ..., I6 allow gas from the outlet of the tertiary equalization and depressurization adsorption tower to enter the secondary equalization and depressurization adsorption tower; gas from the outlet of the displacement adsorption tower enters the secondary displacement gas adsorption tower through the secondary equalization and depressurization inlet valve; the secondary equalization and depressurization inlet valves of each adsorption tower are connected in parallel through equalization pipeline 1.

[0024] There are 7 valves connected to the upper interface of the adsorption tower, namely: The tertiary adsorption exhaust valves A9, B9, ..., I9 are connected in series with the secondary adsorption tower and the primary adsorption tower through the tertiary adsorption exhaust valve, the secondary adsorption inlet valve, the secondary adsorption exhaust valve, and the primary adsorption inlet valve; the tertiary adsorption exhaust valve of each adsorption tower is connected in parallel through adsorption pipeline 1. Secondary adsorption exhaust valves A10, B10, ..., I10 allow gas inside the secondary adsorption tower to pass through them. The exhaust gas is discharged into the primary adsorption tower, and the secondary adsorption exhaust valves of each adsorption tower are connected in parallel through adsorption pipeline 2. Primary adsorption exhaust valves A15, B15, ..., I15 allow gas inside the primary adsorption tower to pass through the primary adsorption exhaust valves. The gas discharged from the adsorption tower is discharged into the difficult-to-adsorb component product gas pipeline as the difficult-to-adsorb component product gas. The primary adsorption exhaust valve of each adsorption tower is connected in parallel through the difficult-to-adsorb component product gas pipeline. Three equalization and pressure reduction exhaust valves A11, B11, ..., I11; the three equalization and pressure reduction adsorption tower and the two equalization and pressure reduction adsorption tower; The primary pressure equalization and depressurization adsorption tower is connected in series via a tertiary pressure equalization and depressurization exhaust valve, a secondary pressure equalization and depressurization inlet valve, a secondary pressure equalization and depressurization exhaust valve, and a primary pressure equalization and depressurization inlet valve. The displacement gas from the outlet of the displacement adsorption tower is discharged into the secondary displacement gas adsorption tower through the tertiary pressure equalization and depressurization exhaust valve. The displacement adsorption tower, the secondary displacement gas adsorption tower, the primary displacement gas adsorption tower, and the displacement gas pressurization adsorption tower are connected in series during the displacement state via a tertiary pressure equalization and depressurization exhaust valve, pressure equalization pipeline 1, a secondary pressure equalization and depressurization inlet valve, a secondary pressure equalization and depressurization exhaust valve, pressure equalization pipeline 2, a primary pressure equalization and depressurization inlet valve, and a primary pressure equalization and depressurization exhaust valve (or a displacement pipeline and a displacement gas pressurization inlet valve). The tertiary pressure equalization and depressurization exhaust valves of each adsorption tower are connected in parallel via pressure equalization pipeline 1. Secondary equalization and depressurization exhaust valves A12, B12, ..., I12 are used to discharge gas from the secondary equalization and depressurization adsorption tower into the primary equalization and depressurization adsorption tower; gas from the outlet of the secondary replacement gas adsorption tower is discharged into the primary replacement gas adsorption tower through the secondary equalization and depressurization exhaust valves; the secondary equalization and depressurization exhaust valves of each adsorption tower are connected in parallel through equalization pipeline 2. Gas from the primary pressure equalization and depressurization adsorption tower is discharged into the pressure equalization and boosting adsorption tower through primary pressure equalization and depressurization exhaust valves A13, B13, ..., I13; gas from the outlet of the primary displacement gas adsorption tower is discharged into the displacement gas boosting adsorption tower through primary pressure equalization and depressurization exhaust valves; the primary pressure equalization and depressurization exhaust valves of each adsorption tower are connected in parallel through displacement pipelines. Reverse riser valves A14, B14, ..., I14 allow reverse pressurized gas to enter the adsorption tower requiring reverse pressurization. The reverse riser valves of each adsorption tower are connected in parallel through reverse gas pipelines.

[0025] In one embodiment of the present invention, the following is employed: Figure 1 When the device is shown, the replacement process of the pressure swing adsorption device is as shown in Table 1. One cycle can be divided into nine sections and 27 steps.

[0026] Table 1 Replacement process sequence

[0027] In this embodiment, the adsorption towers in each section simultaneously in the adsorption state are identical. Each section contains three steps, and the functional states achieved by different adsorption towers in these three steps are different. All the functional states achieved by the nine adsorption towers in these three steps constitute all the functional states experienced by an adsorption tower in one cycle. The following describes the correspondence between different functional states and valves and pipelines in detail, taking the first section, i.e., steps 1-3, as an example: Step 1: Adsorption tower A, which has completed three reverse-up states, adsorption tower C, which has completed two reverse-up states, and adsorption tower E, which has completed one reverse-pressurization state, simultaneously enter the adsorption state. Valves A1, A9, C8, C10, E7, and E15 are opened. The raw material gas enters adsorption tower A through valve A1 at the lower interface of the first adsorption tower (adsorption tower A). Adsorption tower A enters the three-stage adsorption state. Easily adsorbed components are adsorbed by the adsorbent, while difficult-to-adsorb components (containing trace amounts or small amounts of easily adsorbed components) flow out of adsorption tower A through the upper interface of the first adsorption tower, and then through valve A9, adsorption pipeline 1, and valve C8 to the second adsorption tower. The gas enters the adsorption tower C through the lower interface, and the adsorption tower C enters the secondary adsorption state. The easily adsorbed components in the gas are adsorbed by the adsorbent, while the difficult-to-adsorb components containing trace amounts of easily adsorbed components flow out of the adsorption tower C through the upper interface of the second adsorption tower. They then enter the adsorption tower E through the lower interface of the third adsorption tower (adsorption tower E) via valve C10, adsorption pipeline 2, and valve E7. The easily adsorbed components are adsorbed by the adsorbent, while the difficult-to-adsorb components flow out of the adsorption tower E through the upper interface of the third adsorption tower. They then enter the difficult-to-adsorb component product gas pipeline through valve C15 and are sent out of the pressure swing adsorption unit through subsequent equipment (such as product gas buffer tanks). As adsorption towers A, C, and E enter the adsorption state, valves I1 and I9 close, and adsorption tower I (the first adsorption tower) ends its third adsorption state; valves B8 and B10 close, and adsorption tower B (the second adsorption tower) ends its second adsorption state; valves D7 and D15 close, and adsorption tower D (the third adsorption tower) ends its first adsorption state. Simultaneously, adsorption towers I, B, and D maintain their series connection from the adsorption state and are connected to adsorption tower F. The four adsorption towers enter a pressure equalization state, and valves I11, B6, B12, D5, D13, and F13 open. Adsorption tower I enters a three-stage pressure equalization and depressurization state, adsorption tower B enters a two-stage pressure equalization and depressurization state, adsorption tower D enters a one-stage pressure equalization and depressurization state, and adsorption tower F enters a pressure equalization and pressurization state. In the third adsorption tower (adsorption tower D), easily adsorbed components in the voids are adsorbed by the adsorbent. Difficult-to-adsorbed components containing trace amounts of easily adsorbed components flow out of adsorption tower D from the upper interface, and flow into adsorption tower F through valves D13 and F13 from the upper interface. The gas in the voids of the second adsorption tower (adsorption tower B) and the desorbed easily adsorbed components pass through the upper interface of the adsorption tower via valve B12, pressure equalization pipeline 2, and D... The gas enters the adsorption tower from the lower port of the third adsorption tower (adsorption tower D). Easily adsorbed components are adsorbed by the adsorbent, while difficult-to-adsorb components and trace amounts of easily adsorbed components flow out from the upper port of the third adsorption tower via valve D13 and then flow into adsorption tower F via valve F13 from the upper port of adsorption tower F. The gas and desorbed easily adsorbed components in the void of the first adsorption tower (adsorption tower I) enter the adsorption tower from the lower port of the second adsorption tower (adsorption tower B) through the upper port of the adsorption tower via valve I11, pressure equalization line 1, and valve B6. Most easily adsorbed components are adsorbed by the adsorbent in the blank zone and mass transfer zone, while difficult-to-adsorb components and trace amounts of easily adsorbed components are adsorbed by the adsorbent. The easily adsorbed component flows out of adsorption tower B from the upper interface of the second adsorption tower, and enters adsorption tower D from the lower interface of the bottom adsorption tower (adsorption tower D) through valve B12, pressure equalization pipeline 2, and valve D5. The easily adsorbed component is adsorbed by the adsorbent. The difficult-to-adsorb component containing trace amounts of easily adsorbed component flows out of adsorption tower D from the upper interface of the third adsorption tower, and enters adsorption tower F from the upper interface of adsorption tower F through valves D13 and F13. When the pressure between adsorption towers I, B, D, and F reaches equilibrium, the pressure equalization process is completed, and valves I11, B6, B12, D5, D13, and F13 are closed. While adsorption towers A, C, and E enter the adsorption state, valve G16 remains open, and adsorption tower G continues to be evacuated and depressurized; valve H3 remains open, and adsorption tower H continues to depressurize in the reverse direction. Step 2: Adsorption towers A, C, and E continue to be in a series adsorption state; When adsorption tower G finishes its vacuuming and depressurization process, valve G16 closes. Simultaneously, valves I2, I11, B6, B12, D5, D13, G13, or G4 open. Adsorption tower I enters the replacement state, adsorption tower B enters the secondary replacement gas adsorption state, adsorption tower D enters the primary replacement gas adsorption state, and adsorption tower G enters the replacement gas pressurization state. The replacement gas (easily adsorbed component product gas) enters adsorption tower I from the lower interface via the replacement gas pipeline and valve I2. The gas remaining in the adsorption tower voids after pressure equalization is pushed upwards by the replacement gas and flows out from the upper interface of adsorption tower I. It then enters adsorption tower B from the lower interface via valve I11, pressure equalization pipeline 1, and valve B6. Most of the easily adsorbed components are absorbed into the adsorption tower. The adsorbent components are adsorbed by the adsorbent in the blank zone and mass transfer zone. The difficult-to-adsorb components and a small amount of easily adsorbed components flow out of adsorption tower B from the upper interface of the second adsorption tower, and enter adsorption tower D from the lower interface of the third adsorption tower (adsorption tower D) through valve B12, pressure equalization pipeline 2, and valve D5. The difficult-to-adsorb components containing trace amounts of easily adsorbed components flow out of adsorption tower D from the upper interface of the third adsorption tower, or flow into adsorption tower G from the upper interface of the fourth adsorption tower (adsorption tower G) through valve D13 and valve G13, or enter adsorption tower G from the lower interface of the fourth adsorption tower (adsorption tower G) through valve D13, displacement pipeline, and valve G4. When the amount of displacement gas flowing into adsorption tower I reaches the set requirement, the displacement process is completed, and valves I2, I11, B6, B12, D5, D13, G13, or G4 are closed. As adsorption tower I enters the displacement state, the reverse depressurization process of adsorption tower H is completed, and it enters the vacuum depressurization state. Valve H3 is closed, and valve H16 is opened. As the pressure inside adsorption tower H decreases, the easily adsorbed components adsorbed on the adsorbent continue to desorb from the adsorbent, or are extracted from the adsorption tower by a vacuum pump through a vacuum tank, or are directly extracted from the adsorption tower by a vacuum pump. The extracted easily adsorbed components are pressurized by a compressor and output as easily adsorbed component product gas to the pressure swing adsorption device; adsorption tower F enters the blank waiting state before reverse pressurization. Step 3: Adsorption towers A, C, and E continue to be in a series adsorption state; When valves B14, D14, and F14 are opened simultaneously, adsorption tower B enters a three-stage reverse pressurization state, adsorption tower D enters a two-stage reverse pressurization state, and adsorption tower F enters a one-stage reverse pressurization state. The product gas of the difficult-to-adsorb component enters adsorption tower B, adsorption tower D, and adsorption tower F respectively through the reverse rise pipeline via valves B14, D14, and F14 from the upper interface of the adsorption tower. After the pressure in adsorption tower B, adsorption tower D, and adsorption tower F rises to the adsorption pressure, the three-stage reverse pressurization state of adsorption tower B is completed, the two-stage reverse pressurization state of adsorption tower D is completed, and the one-stage reverse pressurization state of adsorption tower F is completed. Then, valves B14, D14, and F14 are closed. As adsorption towers B, D, and F enter the reverse pressurization state, valve I3 opens, and adsorption tower I enters the reverse depressurization state. After the replacement state is completed, the easily adsorbed components remaining in the gaps of adsorption tower I, as well as the easily adsorbed components desorbed from the adsorbent as the pressure inside the adsorption tower decreases, are discharged from adsorption tower I through the lower interface of the adsorption tower. After being pressurized by the compressor, they are output as easily adsorbed component product gas from the pressure swing adsorption device. When adsorption towers B, D, and F enter the reverse pressurization state, valve H16 remains open, and adsorption tower H continues to evacuate and depressurize; adsorption tower G enters the blank waiting state before equalization and pressurization.

[0028] At this point, the first phase is complete. The valve location numbers and piping for the different adsorption towers in the other eight phases to achieve the same functional state are the same as in the first phase. Refer to the descriptions in steps 1-3 for guidance. Figure 1 The same principle applies to Table 1, and will not be repeated here.

[0029] The above are preferred embodiments of the present invention. It should be noted that, for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A three-tower series pressure swing adsorption device and a displacement process, characterized in that: The device includes at least 9 adsorption towers and corresponding valves and fittings, with the adsorption towers connected in series and parallel. Each adsorption tower is controlled by 16 valves to switch between various states; The lower interface of the adsorption tower is connected to 9 valves, and the upper interface is connected to 7 valves.

2. The three-tower series pressure swing adsorption device and process as described in claim 1, characterized in that: The nine valves connected to the lower interface of the adsorption tower include: The gas from the outlet of the secondary adsorption tower enters the primary adsorption tower through the primary adsorption inlet valve; the primary adsorption inlet valves of each adsorption tower are connected in parallel through adsorption pipeline 2. The secondary adsorption inlet valve allows gas from the outlet of the tertiary adsorption tower to enter the secondary adsorption tower; the secondary adsorption inlet valves of each adsorption tower are connected in parallel through adsorption pipeline 1. The feed gas enters the adsorption tower through the three-stage adsorption inlet valve. The three-stage adsorption inlet valves of each adsorption tower are connected in parallel through the feed gas pipeline. The gas from the outlet of the primary displacement adsorber enters the displacement adsorber through the displacement gas pressure boosting inlet valve. The displacement gas pressure boosting inlet valves of each adsorption tower are connected in parallel through displacement pipelines. The displacement gas inlet valve allows the displacement gas to enter the displacement adsorber. The displacement gas inlet valves of each adsorption tower are connected in parallel through the displacement gas pipeline. The reverse exhaust valve is used to discharge the gas inside the adsorption tower when the adsorption tower is in the reverse depressurization process. The reverse exhaust valves of each adsorption tower are connected in parallel through the reverse pipeline. When the adsorption tower is in a vacuum and depressurization state, the gas inside the adsorption tower is discharged from the adsorption tower through the extraction and exhaust valve. The extraction and exhaust valves of each adsorption tower are connected in parallel through extraction pipelines. The gas from the outlet of the secondary pressure equalization and depressurization adsorption tower enters the primary pressure equalization and depressurization adsorption tower through the primary pressure equalization and depressurization inlet valve; the gas from the outlet of the secondary displacement gas adsorption tower enters the primary displacement gas adsorption tower through the primary pressure equalization and depressurization inlet valve; the primary pressure equalization and depressurization inlet valves of each adsorption tower are connected in parallel through the pressure equalization pipeline 2. The secondary equalization and depressurization inlet valve allows gas from the outlet of the tertiary equalization and depressurization adsorption tower to enter the secondary equalization and depressurization adsorption tower; gas from the outlet of the displacement adsorption tower also enters the secondary displacement gas adsorption tower through the secondary equalization and depressurization inlet valve; the secondary equalization and depressurization inlet valves of each adsorption tower are connected in parallel through equalization pipeline 1.

3. The two-tower series pressure swing adsorption displacement device as described in claim 1, characterized in that: The seven valves connected to the upper interface of the adsorption tower include: The tertiary adsorption exhaust valve connects the tertiary adsorption tower, the secondary adsorption tower, and the primary adsorption tower in series via the tertiary adsorption exhaust valve, the secondary adsorption inlet valve, and the primary adsorption inlet valve; the tertiary adsorption exhaust valve of each adsorption tower is connected in parallel via adsorption pipeline 1. The gas inside the secondary adsorption tower is discharged into the primary adsorption tower through the secondary adsorption exhaust valve. Inside, the secondary adsorption exhaust valves of each adsorption tower are connected in parallel through adsorption pipeline 2; The primary adsorption exhaust valve allows the gas inside the primary adsorption tower to be discharged from the adsorption tower, serving as a difficult-to-clean exhaust valve. The adsorbed component product gas is discharged into the difficult-to-adsorb component product gas pipeline, and the primary adsorption exhaust valve of each adsorption tower is connected in parallel through the difficult-to-adsorb component product gas pipeline. Three-stage pressure equalization and depressurization exhaust valve, three-stage pressure equalization and depressurization adsorption tower, two-stage pressure equalization and depressurization adsorption tower, and one-stage pressure equalization and depressurization adsorption tower The adsorbers are connected in series via a three-stage equalization exhaust valve, a two-stage equalization inlet valve, a two-stage equalization exhaust valve, and a one-stage equalization inlet valve. The displacement gas from the outlet of the displacement adsorption tower is discharged into the two-stage displacement gas adsorption tower through the three-stage equalization exhaust valve. The displacement adsorption tower, the two-stage displacement gas adsorption tower, the one-stage displacement gas adsorption tower, and the displacement gas pressurization adsorption tower are connected in series during the displacement state via the three-stage equalization exhaust valve, equalization pipeline 1, two-stage equalization inlet valve, two-stage equalization exhaust valve, equalization pipeline 2, one-stage equalization inlet valve, one-stage equalization exhaust valve, or displacement pipeline and displacement gas pressurization inlet valve. The three-stage equalization exhaust valves of each adsorption tower are connected in parallel via equalization pipeline 1. The gas in the secondary pressure equalization and depressurization adsorption tower is discharged into the primary pressure equalization and depressurization adsorption tower through the secondary pressure equalization and depressurization valve; the gas from the outlet of the secondary replacement gas adsorption tower is discharged into the primary replacement gas adsorption tower through the secondary pressure equalization and depressurization valve; the secondary pressure equalization and depressurization valves of each adsorption tower are connected in parallel through the pressure equalization pipeline 2. The gas in the primary pressure equalization and depressurization adsorption tower is discharged into the pressure equalization and pressurization adsorption tower through the primary pressure equalization and depressurization exhaust valve; the gas from the outlet of the primary displacement gas adsorption tower is discharged into the displacement gas pressurization adsorption tower through the primary pressure equalization and depressurization exhaust valve; the primary pressure equalization and depressurization exhaust valves of each adsorption tower are connected in parallel through displacement pipelines. The reverse riser valve allows the reverse pressurized gas to enter the adsorption tower that requires reverse pressurization. The reverse riser valves of each adsorption tower are connected in parallel through the reverse riser gas pipeline.

4. A three-tower series pressure swing adsorption device and a displacement process, characterized in that: The pressure swing adsorption displacement device according to any one of claims 1-3 is used in the following manner: The replacement process is as follows: a three-tower series pressure swing adsorption replacement device is used. In one cycle, during the replacement state, four adsorption towers are connected in series to complete the replacement. In the displacement state, three of the four adsorption towers are connected in series, one end to the other. The adsorption tower upstream in the series connection is the first adsorption tower, the adsorption tower in the middle is the second adsorption tower, and the adsorption tower downstream is the third adsorption tower. The upper interface of the third adsorption tower is then connected to the upper or lower interface of the fourth adsorption tower, thus realizing the series connection of the four adsorption towers. The series connection method of the first, second, and third adsorption towers is the same as the series connection method when these three adsorption towers are in the adsorption state and the pressure equalization and depressurization state. The first adsorption tower is the displaced adsorption tower, the second adsorption tower receives the gas components flowing from the first adsorption tower, the third adsorption tower receives the gas components flowing from the second adsorption tower, and the fourth adsorption tower receives the gas components flowing from the third adsorption tower. In the displacement state, the three adsorption towers, originally in the pressure equalization and depressurization state, continue in series, connected end to end, as in the pressure equalization and depressurization state. The displacement gas enters the first adsorption tower from the lower inlet. The easily adsorbed components and a small amount of difficult-to-adsorbed components, originally remaining in the adsorption tower's voids, are pushed out of the adsorption tower from bottom to top by the displacement gas through the upper inlet, placing the first adsorption tower in the displacement state. The pushed-out gas then enters the second adsorption tower from the lower inlet. Most of the easily adsorbed components are adsorbed in the adsorbent mass transfer zone and blank zone, while the difficult-to-adsorbed components and a small amount of easily adsorbed components flow out of the second adsorption tower from the upper inlet, placing the second adsorption tower in the secondary displacement gas adsorption state. The gas flowing out of the second adsorption tower then enters the third adsorption tower from the lower inlet, where the easily adsorbed components are adsorbed... Adsorption by the adsorbent: the difficult-to-adsorb components and trace amounts of easily adsorbed components flow out of the third adsorption tower from the upper interface, and the third adsorption tower is in a first-stage displacement gas adsorption state. The gas flowing out of the third adsorption tower then flows into the fourth adsorption tower from the upper or lower interface, and the fourth adsorption tower is in a displacement gas pressurization state. The quality of the gas flowing into the fourth adsorption tower is equivalent to the product gas of the difficult-to-adsorbed components. After the pressure equalization and depressurization are completed, the displacement gas pushes the small amount of difficult-to-adsorbed components remaining in the voids of the first adsorption tower into the second adsorption tower. After the displacement state is completed, the high-purity easily adsorbed components remaining in the voids of the first adsorption tower are the easily adsorbed components. This part of the easily adsorbed components, as well as the easily adsorbed components desorbed from the adsorbent during the reverse depressurization and vacuum depressurization processes, are pressurized by the compressor and used as the easily adsorbed component product gas output device.

5. The displacement process of a three-tower series pressure swing adsorption displacement device as described in claim 1, characterized in that: The product gas containing easily adsorbed components is used as the replacement gas.

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