A pressure swing adsorption nitrogen generator and a preparation method thereof

Abstract

The application relates to a pressure swing adsorption type nitrogen generator and a preparation method, and relates to the technical field of nitrogen preparation.The nitrogen preparation device comprises a first adsorption tower and a second adsorption tower which are designed to alternately prepare nitrogen, the gas outlets of the first adsorption tower and the second adsorption tower are connected with each other through a connecting pipeline, a gas outlet pipeline which is communicated with a nitrogen storage tank is connected to the middle of one side of the connecting pipeline, two lag sections are formed between the gas outlet pipeline and the two gas outlets, the two lag sections are used for intercepting nitrogen containing residual oxygen, the gas outlets of the first adsorption tower and the second adsorption tower are respectively provided with oxygen detection members, reverse pressurizing pipelines which are communicated with the reverse pressurizing pipelines are arranged between carbon molecular sieve filling blocks and the gas outlet pipeline on the other side of the lag sections, the preparation purity of the nitrogen can be improved through the reverse pressurizing pipelines, the pressure difference is increased, the desorption rate of the adsorption tower can be accelerated, and the purity of the nitrogen prepared in the next process can be improved.

Description

Technical Field

[0001] This application relates to the field of nitrogen preparation technology, and in particular to a pressure swing adsorption nitrogen generator and its preparation method. Background Technology

[0002] Currently, nitrogen preparation technologies mainly include cryogenic separation, membrane separation, and pressure swing adsorption (PSA). Among them, PSA has gradually become the mainstream technology due to its advantages such as simple equipment, low energy consumption, and fast start-up. In recent years, with the improvement of carbon molecular sieve materials and the development of automated control technology, the efficiency and stability of PSA have been significantly improved, and it is widely used in industrial fields.

[0003] The existing technology involves a pressure swing adsorption (PSA) nitrogen generator that uses a dual-tower alternating adsorption-desorption process. PLC controls pneumatic valves to achieve continuous nitrogen production. The adsorption tower is filled with carbon molecular sieves, and oxygen and nitrogen molecules are separated by the difference in diffusion rates. At the same time, a reverse purging device is used to back purge the adsorption tower that needs to be desorbed, so that the oxygen inside can be quickly desorbed and enter the nitrogen production process, thereby increasing the nitrogen production rate.

[0004] However, in the above-mentioned and existing pressure swing adsorption nitrogen generators, after the oxygen content at the outlet of the adsorption tower is continuously monitored to exceed the standard, a control response is required to close the pneumatic valve. During the process from detection to valve closure, nitrogen mixed with trace amounts of oxygen continues to be output, thus affecting the purity of the final nitrogen produced. At the same time, the reverse purge gas source in the existing technology usually comes from the finished nitrogen or equalizing gas, and the desorption and regeneration process is complicated. Summary of the Invention

[0005] This application provides a pressure swing adsorption (PSA) nitrogen generator and its preparation method, which can solve the problems that the purity of the nitrogen produced may decrease in the continuous nitrogen preparation process due to the long response time of oxygen content detection and valve closure, and the desorption and regeneration process is complicated.

[0006] The technical solution of this application is as follows: A pressure swing adsorption (PSA) nitrogen generator, comprising:

[0007] An air supply treatment device, wherein the air supply treatment device is used to pressurize air and dry and filter the air;

[0008] A nitrogen preparation device includes a first adsorption tower and a second adsorption tower designed to alternately prepare nitrogen. Both the first and second adsorption towers have outlets at their upper ends, which are interconnected via connecting pipes. The lower ends of the first and second adsorption towers are connected to a gas delivery processing device. An outlet pipe connected to a nitrogen storage tank is located in the middle of one side of the connecting pipe, forming two hysteresis sections between the outlet pipe and the two outlets. Carbon molecular sieve packing blocks are provided in the hysteresis sections for secondary adsorption of residual oxygen in the nitrogen, thus forming a reverse-purge nitrogen gas.

[0009] Both the first and second adsorption towers are equipped with oxygen detectors at their outlets. On the other side of the lag section, a reverse pressurization pipeline is provided between the carbon molecular sieve packing block and the outlet pipeline, which is connected to itself. The reverse pressurization pipeline is used to increase the gas pressure in the lag section and to use the pressure difference to purge the first or second adsorption tower with reverse nitrogen.

[0010] By adopting the above scheme, a hysteresis section is set between the gas outlet and the gas outlet pipeline. When the oxygen detector detects that the oxygen content exceeds the standard and closes the gas outlet pipeline, the continuously output mixed nitrogen gas containing oxygen enters the hysteresis section. When passing through the carbon molecular sieve packing block, the mixed nitrogen gas can be adsorbed twice. After adsorption, it forms back-purge nitrogen gas, which is trapped between the control valve and the carbon molecular sieve packing block. At this time, by increasing the gas pressure of the hysteresis section through the reverse pressurization pipeline connected to the hysteresis section, the back-purge nitrogen gas trapped in the hysteresis section is pushed back by a larger pressure difference and back-purged in the carbon molecular sieve packing block and the first adsorption tower. This not only avoids the decrease in nitrogen purity due to insufficient response during continuous nitrogen production, but also avoids the presence of residual oxygen in the adsorption tower when back-purges oxygen in the adsorption tower, thereby improving the purity of nitrogen produced in the next process.

[0011] In one embodiment of this application, a control valve is provided inside one end of the hysteresis section near the outlet pipeline, and the carbon molecular sieve filling block is provided inside the other end;

[0012] The other ends of the two hysteresis sections are respectively connected to the first adsorption tower and the second adsorption tower.

[0013] By adopting the above scheme, carbon molecular sieve packing blocks are set inside the lag section, so that the air in the device can pass through the carbon molecular packing blocks after being filtered by the adsorption tower and undergo secondary adsorption to form back purge nitrogen, which facilitates the reverse discharge of residual oxygen during subsequent back purge.

[0014] In one embodiment of this application, the air supply treatment device includes a pressurizing air supply device and a separation treatment device arranged sequentially along the air supply direction. The pressurizing air supply device is used to pressurize the air, and the separation treatment device is used to remove oil, water and impurities from the air.

[0015] By adopting the above scheme, before the air is treated by pressure swing adsorption to produce nitrogen, the air pressure is increased so that the carbon molecular sieve filling layer can adsorb oxygen under high pressure according to the different rates of nitrogen and oxygen passing through. Before the carbon molecular sieve is introduced, impurities, oil and moisture in the air need to be separated to avoid carbon molecular sieve failure.

[0016] In one embodiment of this application, the upper end of the first adsorption tower and the second adsorption tower is provided with a recovery hood, the recovery hood is provided with a plurality of recovery channels, and the recovery hood is connected to the gas outlet;

[0017] The first adsorption tower and the second adsorption tower are provided with a gas equalization hood inside the lower end. The gas equalization hood has multiple air inlet channels. The lower end of the first adsorption tower and the second adsorption tower are connected to an air inlet pipe. One end of the air inlet pipe is connected to the gas delivery and treatment equipment, and the other end is connected to the gas equalization hood. The lower end of the first adsorption tower and the second adsorption tower are also connected to an exhaust pipe.

[0018] Both the first and second adsorption towers have a carbon molecular sieve filling layer between the recovery hood and the gas equalization hood.

[0019] By adopting the above scheme, a carbon molecular sieve packing layer is filled between the first adsorption tower and the second adsorption tower, and a gas equalization hood that can uniformly expand the air inlet surface is set inside the upper end. This prevents channeling when air enters the first adsorption tower, thereby enabling the carbon molecular sieve to adsorb oxygen more comprehensively and uniformly, improving the utilization rate of the carbon molecular sieve, and also improving the nitrogen production efficiency of the entire device.

[0020] In one embodiment of this application, the intake pipe includes:

[0021] An air intake section, one end of which is connected to the separation and processing device;

[0022] The branch section has two parts, each equipped with an air inlet valve. One end of each branch section is connected to the other end of the air inlet section, and the other end is connected to the first adsorption tower and the second adsorption tower, respectively.

[0023] By adopting the above scheme, when the first adsorption tower and the second adsorption tower alternately produce nitrogen, the opening and closing states of the inlet valves in the two branch sections are switched to achieve the purpose of alternating operation of the first adsorption tower and the second adsorption tower, thereby improving the nitrogen production efficiency of the device.

[0024] In one embodiment of this application, the reverse booster line includes:

[0025] A compression tube, one end of which is fitted onto and connected to the hysteresis section, and a compression drive component is provided inside the compression tube;

[0026] An extension pipeline is connected to the lag section to adjust its volume.

[0027] By adopting the above scheme, when oxygen is detected and the control valve is closed but the vent valve is opened, the compression drive can compress the volume in the lag section to a certain extent, thereby increasing the pressure difference with the outside. The reverse purge nitrogen in the compression pipe on the lag section side can purge the saturated carbon molecular sieve filling layer and carbon molecular sieve filling block more quickly, improving the cleanliness and speed of the purge and ensuring the purity of nitrogen preparation.

[0028] In one embodiment of this application, the compression drive includes a piston that is slidably sealed in the compression tube, and a drive rod is coaxially connected and fixed to one end of the piston. The drive rod is connected and fixed to the drive shaft of the drive component.

[0029] By adopting the above scheme, by setting a piston that can slide and seal inside the compression tube, and by using a drive rod to drive the piston to move, it is possible to flexibly push the reverse purging nitrogen in the compression tube to increase the gas pressure in the lag section.

[0030] In one embodiment of this application, the extension conduit includes:

[0031] Two connecting pipes, one end of which is connected to the lag section;

[0032] The U-shaped tube has its two ends connected to the other end of the connecting tube via connecting pipes;

[0033] The connecting pipe is coaxially sleeved on the outside of the U-shaped pipe and the connecting pipe. Each end of the connecting pipe is provided with a clamping bolt, which slides and seals with the U-shaped pipe and the connecting pipe.

[0034] By adopting the above scheme, by using an extended pipeline, and by adjusting the distance between the U-shaped tube and the two connecting pipes, the total volume of the lag section, the extended pipeline, and the compression tube can be adjusted, thereby adjusting the volume of backpurge nitrogen that can be accommodated. This allows the device to adjust the volume of backpurge nitrogen that the lag section can accommodate based on the gas flow rate and the usage of the carbon molecular sieve packing layer, enabling the device to collect more backpurge nitrogen during operation.

[0035] In one embodiment of this application, the separation processing apparatus includes:

[0036] An oil-water separator is provided inside, which is equipped with a filter for adsorbing and filtering oil and water in the air, and the oil-water separator is connected to the air compressor.

[0037] The drying tower is provided in at least two, and the at least two drying towers are interconnected and connected to the oil-water separator tank.

[0038] A pressure buffer tank, which is connected to one of the drying towers and to the air inlet pipeline.

[0039] By adopting the above scheme, when nitrogen needs to be prepared using air, the nitrogen needs to be pretreated. The filter inside the oil-water separator can adsorb moisture and oil in the air, while the drying tower can further dry the air after absorbing moisture and oil. The dried air can enter the pressure buffer tank, so that the pressure of the pretreated air can be balanced and compensated by the pressure buffer tank, avoiding pressure fluctuations in the air compressor that affect the gas pressure of the entire system.

[0040] The second objective of this invention is to provide a pressure swing adsorption method for preparing nitrogen.

[0041] The technical solution is as follows: A pressure swing adsorption (PSA) nitrogen preparation method, which uses a PSA nitrogen generator to prepare nitrogen, includes the following steps:

[0042] Step 1: Compress the air using an air compressor, and then filter and dry it sequentially to obtain clean air;

[0043] Step 2: Open the control valve near the first adsorption tower and close the control valve near the second adsorption tower, and pressurize the pure air obtained in Step 1 into the first adsorption tower to continuously adsorb oxygen from the pure air and output nitrogen.

[0044] Step 3: Continuously monitor the oxygen concentration at the outlet of the first adsorption tower until the oxygen concentration exceeds the threshold. Then, control the valve near the first adsorption tower to close and retain part of the mixed nitrogen in the lag section. The oxygen in the mixed nitrogen is then absorbed a second time by the carbon molecular sieve packing block to obtain reverse purge nitrogen.

[0045] Step 4: Control the compression drive to push the reverse purge nitrogen in the lag section, thereby increasing the pressure in the lag section and the first adsorption tower. After pressure holding, open the vent valve at the bottom of the first adsorption tower to purge the oxygen in the first adsorption tower and the carbon molecular sieve packing block.

[0046] Step 5: Close the control valve near the first adsorption tower and open the control valve near the second adsorption tower to pressurize pure air into the second adsorption tower and repeat nitrogen extraction on the second adsorption tower.

[0047] By adopting the above scheme, the oxygen concentration at the outlet of the adsorption tower is detected. When oxygen is detected, the corresponding control valve is closed. The nitrogen gas with trace amounts of oxygen in the lag section is then adsorbed again to form back-purge nitrogen gas. By pushing the volume of back-purge nitrogen gas inside the lag section, the pressure difference between the lag section and the first adsorption tower as a whole and the outside is increased. The pressure difference is used to back-purge the carbon molecular sieve filling layer with the filtered back-purge nitrogen gas, which improves the cleanliness and speed of back-purge, and at the same time improves the purity of the prepared nitrogen gas.

[0048] In summary, this application includes at least one of the following beneficial technical effects: by setting a hysteresis section between the gas outlet and the gas outlet pipeline, the oxygen detection device can promptly close the corresponding control valve when it detects the presence of oxygen in the prepared nitrogen. During the continuous preparation of nitrogen, nitrogen containing trace amounts of oxygen is trapped in the hysteresis section, thereby preventing oxygen from contaminating the already collected nitrogen. At the same time, in the hysteresis section, under the secondary adsorption of the carbon molecule filling layer, a portion of back-purge nitrogen is formed. In conjunction with the compression drive, the pressure difference between the first adsorption tower and the outside is increased, and the back-purge nitrogen is used to back-purge the adsorption tower that has been fully adsorbed with oxygen, thereby improving the cleanliness and efficiency of desorption and also improving the purity of the prepared nitrogen.

[0049] By setting up an extension pipeline and adjusting the distance between the U-shaped pipe and the two connecting pipes, the volume of the entire extension pipeline can be adjusted. Since the lag section is connected to the extension pipeline, the volume of the lag section can be indirectly controlled. This allows the device to adjust the volume of gas contained in the lag section according to different equipment and the flow rate of nitrogen preparation, ensuring that the device can retain nitrogen containing oxygen and guarantee the purity of the nitrogen.

[0050] By installing a gas equalization hood inside the first and second adsorption towers, the high-pressure air entering the first or second adsorption tower is diverted by the gas equalization hood, which expands the air intake area and allows the air to contact the carbon molecular sieve filling layer more evenly. This avoids channeling in the carbon molecular sieve filling layer, improves the utilization rate of the carbon molecular sieve filling layer, and increases the efficiency of nitrogen production. Attached Figure Description

[0051] Figure 1 This is a front view of a pressure swing adsorption nitrogen generator provided in the embodiments of this application;

[0052] Figure 2This is a top cross-sectional view of a pressure swing adsorption nitrogen generator connection pipeline used for nitrogen preparation, as provided in the embodiments of this application.

[0053] Figure 3 This is a top sectional view of the connecting pipeline of a pressure swing adsorption nitrogen generator provided in this application embodiment during backflushing;

[0054] Figure 4 This is a top sectional view of an extension pipeline for a pressure swing adsorption nitrogen generator provided in an embodiment of this application;

[0055] Figure 5 This is a top view of the inlet pipe of a pressure swing adsorption nitrogen generator provided in the embodiments of this application;

[0056] Figure 6 This is a front sectional view of the first adsorption tower of a pressure swing adsorption nitrogen generator provided in the embodiments of this application.

[0057] Explanation of reference numerals in the attached drawings: 1. Gas supply and processing equipment; 11. Pressurized gas supply device; 12. Separation and processing device; 121. Oil-water separator; 122. Drying tower; 123. Pressure buffer tank; 2. Nitrogen preparation device; 21. First adsorption tower; 22. Second adsorption tower; 23. Gas outlet pipeline; 24. Connecting pipeline; 241. Lag section; 242. Carbon molecular sieve packing block; 243. Control valve; 25. Oxygen detector. Components; 26. Reverse booster pipeline; 261. Compression pipe; 262. Compression drive component; 2621. Piston; 2622. Drive rod; 264. Extension pipeline; 2641. Connecting pipe; 2642. U-shaped pipe; 2643. Connecting pipe; 27. Recovery hood; 28. Gas equalization hood; 29. ​​Exhaust pipe; 210. Carbon molecular sieve filling layer; 211. Inlet pipeline; 2111. Inlet section; 2112. Branch section. Detailed Implementation

[0058] The following is in conjunction with the appendix Figures 1-6 This application provides a more detailed description of a pressure swing adsorption nitrogen generator and its preparation method.

[0059] Please see Figure 1This application provides a pressure swing adsorption (PSA) nitrogen generator, comprising an air supply treatment device 1 and a nitrogen preparation device 2. The air supply treatment device 1 is used to pressurize and dry / filter the air. The nitrogen preparation device 2 includes a first adsorption tower 21 and a second adsorption tower 22 designed to alternately prepare nitrogen. Both the first adsorption tower 21 and the second adsorption tower 22 have outlets at their upper ends, which are interconnected via a connecting pipe 24. The lower ends of the first adsorption tower 21 and the second adsorption tower 22 are connected to the air supply treatment device 1. An outlet pipe 23, connected to a nitrogen storage tank, is connected to one side of the connecting pipe 24, forming two hysteresis sections 241 between the outlet pipe 23 and the two outlets. Each hysteresis section 241 contains carbon molecular sieve packing blocks 242 for secondary adsorption of residual oxygen in the nitrogen, forming a reverse-purge nitrogen flow. The outlets of the first adsorption tower 21 and the second adsorption tower 22... Each outlet is equipped with an oxygen detection element 25. On the other side of the hysteresis section 241, between the carbon molecular sieve packing block 242 and the outlet pipe 23, there is a reverse pressurization pipe 26 connected to itself. The reverse pressurization pipe 26 is used to increase the gas pressure in the hysteresis section 241 and use the pressure difference to purge the reverse-purge nitrogen into the first adsorption tower 21 or the second adsorption tower 22. By setting the hysteresis section 241 between the outlet and the outlet pipe 23, during the process of closing the outlet pipe 23, the mixed nitrogen containing oxygen can be trapped in the hysteresis section 241 and formed into reverse-purge nitrogen under the secondary adsorption of the carbon molecular sieve packing block 242. At the same time, by increasing the gas pressure in the hysteresis section 241 through the reverse pressurization pipe 26, the trapped reverse-purge nitrogen is pushed back by a larger pressure difference. This not only improves the purity of nitrogen preparation, but also increases the speed of reverse-purge adsorption tower, avoids oxygen residue in the adsorption tower, and thus improves the purity of nitrogen prepared in the next process.

[0060] Please see Figure 2 and Figure 3 The hysteresis section 241 has a control valve 243 inside one end near the outlet pipe 23, and a carbon molecular sieve packing block 242 inside the other end. The other ends of the two hysteresis sections 241 are respectively connected to the first adsorption tower 21 and the second adsorption tower 22. By setting the carbon molecular sieve packing block 242 inside the hysteresis section 241, the mixed nitrogen gas can pass through the carbon molecular packing block and undergo secondary adsorption to obtain relatively pure reverse purge nitrogen gas, which facilitates subsequent reverse purge and allows the residual oxygen to be discharged to the outside.

[0061] In this embodiment, the carbon molecular sieve filling block 242 includes a hollowed-out placement block, and a filter screen is set in the placement block. Carbon molecular sieve particles are filled into the filter screen to form the carbon molecular sieve filling block 242.

[0062] Please see Figure 1 The air supply treatment device 1 includes a pressurized air supply device 11 and a separation treatment device 12 arranged sequentially along the air supply direction. The pressurized air supply device 11 is used to pressurize the air, and the separation treatment device 12 is used to remove oil, water and impurities from the air. Before the air is treated by pressure swing adsorption to produce nitrogen, the air pressure is increased so that the carbon molecular sieve filling layer 210 can adsorb oxygen under high pressure according to the different rates of nitrogen and oxygen passage. In addition, separating impurities, oil and moisture in the air can also prevent impurities, oil and moisture from causing the carbon molecular sieve to fail.

[0063] In this embodiment, the pressurized gas delivery equipment can be an air compressor.

[0064] Please see Figure 6 The first adsorption tower 21 and the second adsorption tower 22 are provided with a recovery hood 27 inside the upper end. The recovery hood 27 has multiple recovery channels inside and is connected to the gas outlet. The first adsorption tower 21 and the second adsorption tower 22 are provided with a gas equalization hood 28 inside the lower end. The gas equalization hood 28 has multiple air inlet channels inside. The lower end of the first adsorption tower 21 and the second adsorption tower 22 is connected to an air inlet pipe 211. One end of the air inlet pipe 211 is connected to the gas supply treatment device 1, and the other end is connected to the gas equalization hood 28. The lower end of the first adsorption tower 21 and the second adsorption tower 22 is also connected to an exhaust pipe 29. The first adsorption tower 21 and the second adsorption tower 22 are both provided with a carbon molecular sieve filling layer 210 between the recovery hood 27 and the gas equalization hood 28. By setting a gas equalization hood that can uniformly expand the air inlet surface, the carbon molecular sieve can adsorb oxygen more comprehensively and evenly, which improves the utilization rate of the carbon molecular sieve and also improves the nitrogen production efficiency of the entire device.

[0065] Please see Figure 5 The air inlet pipe 211 includes an air inlet section 2111 and a branch section 2112. One end of the air inlet section 2111 is connected to the separation and treatment device 12. There are two branch sections 2112, each equipped with an air inlet valve. One end of each branch section 2112 is connected to the other end of the air inlet section 2111, and the other end is connected to the first adsorption tower 21 and the second adsorption tower 22, respectively. By switching the opening and closing state of the air inlet valves in the two branch sections 2112, the first adsorption tower 21 and the second adsorption tower 22 can work alternately to improve the nitrogen production efficiency of the device.

[0066] Please continue reading. Figure 2 and Figure 3The reverse pressurization pipeline 26 includes a compression pipe 261. One end of the compression pipe 261 is mounted on and connected to the hysteresis section 241. The compression pipe 261 is provided with a compression drive 262. An extension pipe 264 is connected to the hysteresis section 241 for adjusting the volume of the hysteresis section 241. The compression drive 262 can push the reverse purge nitrogen in the compression pipe 261 located on one side of the hysteresis section 241, and use the reverse purge nitrogen to purge the saturated carbon molecular sieve filling layer 210, thereby improving the cleanliness of the purge.

[0067] Please continue reading. Figure 2 and Figure 3 The compression drive component 262 includes a piston 2621, which is slidably sealed in the compression tube 261. One end of the piston 2621 is coaxially connected and fixed to a drive rod 2622, which is connected and fixed to the drive shaft of the drive component. By setting a piston that can slide and seal inside the compression tube and using a drive rod to drive the piston to move, the reverse purge of nitrogen gas in the compression tube can be flexibly pushed to increase the gas pressure.

[0068] In this embodiment, the driving component can be a cylinder or an electric actuator.

[0069] Please continue reading. Figure 2 and Figure 3 The extension pipe 264 includes two connecting pipes 2641 and a U-shaped pipe 2642. One end of each connecting pipe 2641 is connected to the lag section 241. Both ends of the U-shaped pipe 2642 are connected to the other ends of the connecting pipes 2641 via connecting pipes 2643. The connecting pipe 2643 is coaxially sleeved on the outside of the U-shaped pipe 2642 and the connecting pipes 2641. Each end of the connecting pipe 2643 is provided with a clamping bolt, which slides and seals with the U-shaped pipe 2642 and the connecting pipe 2641. By adjusting the distance between the U-shaped pipe 2642 and the two connecting pipes 2641, the total volume of the lag section 241, the extension pipe 264, and the compression pipe 261 can be adjusted. This allows the device to adjust the gas volume of the reverse purge nitrogen that the lag section can accommodate according to the gas flow rate and the usage of the carbon molecular sieve filling layer 210, so that the device can be adjusted according to the different nitrogen preparation flow rates of different equipment.

[0070] Please see Figure 1The separation and processing device 12 includes an oil-water separator 121, a drying tower 122, and a pressure buffer tank 123. The oil-water separator 121 is equipped with a filter for adsorbing and filtering oil and water in the air. The oil-water separator 121 is connected to the air compressor. At least two drying towers 122 are provided, and the at least two drying towers 122 are interconnected and connected to the oil-water separator 121. The pressure buffer tank 123 is connected to one of the drying towers 122 and is connected to the air inlet pipe 211. When nitrogen needs to be prepared using air, the nitrogen needs to be pretreated. The filter inside the oil-water separator 121 can adsorb moisture and oil in the air. At the same time, the drying tower 122 can further dry the air after absorbing moisture and oil. The dried air can enter the pressure buffer tank 123, so that the pressure of the pretreated air can be balanced and compensated by the pressure buffer tank 123, avoiding pressure fluctuations in the air compressor that affect the gas pressure of the entire system.

[0071] In this embodiment, the filter medium can be activated carbon.

[0072] The second objective of this invention is to provide a pressure swing adsorption method for preparing nitrogen.

[0073] The technical solution is as follows: A pressure swing adsorption (PSA) nitrogen preparation method, which uses a PSA nitrogen generator to prepare nitrogen, includes the following steps:

[0074] Step 1: Compress the air using an air compressor, and then filter and dry it sequentially to obtain clean air;

[0075] Step 2: Open the control valve 243 near the first adsorption tower 21 and close the control valve 243 near the second adsorption tower 22, and pressurize the pure air obtained in Step 1 into the first adsorption tower 21 to continuously adsorb oxygen in the pure air and output nitrogen.

[0076] Step 3: Continuously monitor the oxygen concentration at the outlet of the first adsorption tower 21 until the oxygen concentration exceeds the threshold. Then, control valve 243 near the first adsorption tower 21 is closed, and part of the mixed nitrogen is intercepted in the lag section 241. The oxygen in the mixed nitrogen is then absorbed a second time by the carbon molecular sieve packing block 242 to obtain reverse purge nitrogen.

[0077] Step 4: Control the compression drive 262 to push the reverse purge nitrogen in the hysteresis section 241, thereby increasing the pressure in the hysteresis section 241 and the first adsorption tower 21. After pressure holding, open the vent valve at the lower end of the first adsorption tower 21 to purge the oxygen in the first adsorption tower 21 and the carbon molecular sieve packing block 242.

[0078] Step 5: Close the control valve 243 near the first adsorption tower 21 and open the control valve 243 near the second adsorption tower 22 to pressurize pure air into the second adsorption tower 22 and repeat nitrogen gas extraction on the second adsorption tower 22.

[0079] The above are all preferred embodiments of this application, and are not intended to limit the scope of protection of this application. Therefore, all equivalent changes made in accordance with the structure, shape and principle of this application should be covered within the scope of protection of this application.

Claims

1. A pressure swing adsorption (PSA) nitrogen generator, characterized in that, include: Air supply treatment equipment (1), the air supply treatment equipment (1) is used to pressurize air and dry and filter the air; A nitrogen preparation device (2) includes a first adsorption tower (21) and a second adsorption tower (22) designed to alternately prepare nitrogen. Both the first adsorption tower (21) and the second adsorption tower (22) are provided with gas outlets at their upper ends. The gas outlets of the first adsorption tower (21) and the second adsorption tower (22) are connected to each other through a connecting pipe (24). The lower ends of the first adsorption tower (21) and the second adsorption tower (22) are connected to the gas supply treatment equipment (1). A gas outlet pipe (23) connected to a nitrogen storage tank is connected to one side of the connecting pipe (24) to form two hysteresis sections (241) between the gas outlet pipe (23) and the two gas outlets. A control valve (243) is provided inside one end of the hysteresis section (241) near the gas outlet pipe (23), and a carbon molecular sieve packing block (242) is provided inside the other end for secondary adsorption of residual oxygen in nitrogen to form reverse purge nitrogen. Both the first adsorption tower (21) and the second adsorption tower (22) are equipped with oxygen detection devices (25) at their outlets. On the other side of the hysteresis section (241), there is a reverse boosting pipeline (26) connected to itself between the carbon molecular sieve filling block (242) and the outlet pipeline (23). The reverse boosting pipeline (26) includes a compression pipe (261). One end of the compression pipe (261) is mounted on the hysteresis section (241) and connected to the hysteresis section (241). The compression pipe (261) is equipped with a compression drive device (262) inside. The reverse boosting pipeline (26) is used to increase the gas pressure in the hysteresis section (241) and use the pressure difference to purge the first adsorption tower (21) or the second adsorption tower (22) with reverse purge nitrogen.

2. The pressure swing adsorption nitrogen generator according to claim 1, characterized in that: The other ends of the two hysteresis sections (241) are respectively connected to the first adsorption tower (21) and the second adsorption tower (22).

3. The pressure swing adsorption nitrogen generator according to claim 2, characterized in that: The air supply processing equipment (1) includes a pressurizing air supply device (11) and a separation processing device (12) arranged sequentially along the air supply direction. The pressurizing air supply device (11) is used to pressurize the air, and the separation processing device (12) is used to remove oil, water and impurities from the air.

4. A pressure swing adsorption nitrogen generator according to claim 3, characterized in that: The first adsorption tower (21) and the second adsorption tower (22) are provided with a recovery hood (27) inside the upper end. The recovery hood (27) has multiple recovery channels inside and is connected to the gas outlet. The first adsorption tower (21) and the second adsorption tower (22) are provided with a gas equalization hood (28) inside the lower end. The gas equalization hood (28) has multiple air inlet channels inside and is connected to an air inlet pipe (211) at the lower end of the first adsorption tower (21) and the second adsorption tower (22). One end of the air inlet pipe (211) is connected to the gas delivery treatment device (1) and the other end is connected to the gas equalization hood (28). The first adsorption tower (21) and the second adsorption tower (22) are also connected to an exhaust pipe (29) at the lower end. The first adsorption tower (21) and the second adsorption tower (22) are both provided with a carbon molecular sieve filling layer (210) between the recovery hood (27) and the gas equalization hood (28).

5. A pressure swing adsorption nitrogen generator according to claim 4, characterized in that, The air intake pipe (211) includes: an air intake section (2111), one end of which is connected to the separation and processing device (12); and two branch sections (2112), each equipped with an air intake valve. One end of each branch section (2112) is connected to the other end of the air intake section (2111), and the other ends are connected to the first adsorption tower (21) and the second adsorption tower (22), respectively.

6. A pressure swing adsorption nitrogen generator according to claim 5, characterized in that, The lag section (241) is connected to an extension pipe (264) for adjusting the volume of the lag section (241).

7. A pressure swing adsorption nitrogen generator according to claim 6, characterized in that, The compression drive (262) includes a piston (2621), which is slidably sealed in the compression tube (261). One end of the piston (2621) is coaxially connected and fixed to a drive rod (2622), which is connected and fixed to the drive shaft of the drive component.

8. A pressure swing adsorption nitrogen generator according to claim 7, characterized in that, The extension pipe (264) includes: two connecting pipes (2641), one end of which is connected to the lag section (241); a U-shaped pipe (2642), the two ends of which are connected to the other end of the connecting pipe (2641) via connecting pipes (2643); the connecting pipe (2643) is coaxially sleeved outside the U-shaped pipe (2642) and the connecting pipe (2641), and the two ends of the connecting pipe (2643) are respectively provided with clamping bolts, which slide and seal with the U-shaped pipe (2642) and the connecting pipe (2641).

9. A pressure swing adsorption nitrogen generator according to claim 8, characterized in that, The separation and processing device (12) includes: an oil-water separator (121), which is equipped with a filter for adsorbing and filtering oil and water in the air, and is connected to an air compressor; a drying tower (122), which is provided with at least two drying towers (122), which are interconnected and connected to the oil-water separator (121); and a pressure buffer tank (123), which is connected to one of the drying towers (122) and is connected to the air inlet pipe (211).

10. A method for preparing nitrogen by pressure swing adsorption, characterized in that, Nitrogen gas is prepared using a pressure swing adsorption nitrogen generator as described in any one of claims 1-9, comprising the following steps: Step 1: Air is compressed by an air compressor and filtered and dried sequentially to obtain pure air; Step 2: The control valve (243) near the first adsorption tower (21) is opened and the control valve (243) near the second adsorption tower (22) is closed, and the pure air obtained in Step 1 is pressed into the first adsorption tower (21) to continuously adsorb oxygen in the pure air and output nitrogen gas; Step 3: The oxygen concentration at the outlet of the first adsorption tower (21) is continuously monitored until the oxygen concentration exceeds the threshold, the control valve (243) near the first adsorption tower (21) is closed, and part of the mixed nitrogen gas is intercepted in the hysteresis section (241), and the oxygen in the mixed nitrogen gas is absorbed again by the carbon molecular sieve packing block (242) to obtain reverse purge nitrogen gas; Step 4: Control the compression drive (262) to push the reverse purge nitrogen in the hysteresis section (241), thereby increasing the pressure in the hysteresis section (241) and the first adsorption tower (21). After pressure holding, open the vent valve at the lower end of the first adsorption tower (21) to purge the oxygen in the first adsorption tower (21) and the carbon molecular sieve packing block (242). Step 5: Close the control valve (243) near the first adsorption tower (21) and open the control valve (243) near the second adsorption tower (22) to pressurize pure air into the second adsorption tower (22) and repeat nitrogen extraction on the second adsorption tower (22).

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