Air separation equipment
By pre-activating the molecular sieve with waste nitrogen protective gas in the standby air separation unit, the problem of difficulty in starting up the standby air separation molecular sieve was solved, and the rapid start-up of the air separation unit and the rapid supply of gas products were realized.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2025-04-25
- Publication Date
- 2026-04-03
AI Technical Summary
The backup air separation molecular sieve is difficult to start up quickly after a long period of inactivity, which leads to the problem of long start-up and purification time for air separation equipment.
By connecting the standby air separation molecular sieve to the fractionation tower of another operating air separation unit, the molecular sieve is pre-activated using a protective gas containing polluted nitrogen to prevent it from adsorbing water and carbon dioxide, thus ensuring the activity of the molecular sieve and allowing it to be used directly upon startup.
It enables rapid start-up of backup air separation units and rapid supply of gas products, avoiding the molecular sieve activation step and shortening the start-up and purification time.
Smart Images
Figure CN224071580U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to the field of air separation technology, specifically to an air separation device. Background Technology
[0002] An air separation device is a device used to extract nitrogen and oxygen from the air.
[0003] Air separation equipment requires the use of air separation molecular sieves to adsorb impurities such as water vapor and carbon dioxide from the air, thereby ensuring the purity of the obtained nitrogen and oxygen.
[0004] Under normal circumstances, when a standby air separation unit is shut down for a long time, the molecular sieve will inevitably adsorb water and carbon dioxide from the air, resulting in a decrease in the adsorption performance of the molecular sieve. Therefore, when the operating air separation unit is overhauled or malfunctions, the molecular sieve must be activated before starting the standby air separation unit.
[0005] Therefore, how to quickly activate the backup air separation molecular sieve and rapidly supply air to the air separation system is a technical problem that urgently needs to be solved by those skilled in the art. Utility Model Content
[0006] First, the technical problem to be solved by this utility model is to provide an air separation device that can solve the problem that the standby air separation molecular sieve still needs to be activated before it is put into use, which causes the air separation device to have a long start-up and purification time.
[0007] To solve the above-mentioned technical problems, this utility model provides an air separation device, which includes an air compression cooling purification component and a fractionation tower. The air compression cooling purification component includes an air supply cooling unit and a molecular sieve purification unit. Air flows to the fractionation tower after being purified by the air compression cooling purification component. The molecular sieve purification unit includes at least two molecular sieve purifiers connected in parallel. The feed end of each molecular sieve purifier is connected to the discharge end of the air supply unit, and the discharge end of each molecular sieve purifier is connected to the feed end of the fractionation tower. Each molecular sieve purifier is also connected to a sealed gas source to deliver polluted nitrogen into the molecular sieve purifier via the sealed gas source. The sealed gas source includes the fractionation tower of another air separation device in operation.
[0008] Furthermore, the molecular sieve purification unit includes at least two molecular sieve purifiers connected in parallel. The air compression cooling gas supply unit is connected to each of the molecular sieve purifiers via a purification delivery pipeline. The discharge end of each of the molecular sieve purifiers is connected to the inlet end of the fractionation tower via an air delivery pipeline. The outlet of the sealed gas source is connected to the molecular sieve purifier via a waste nitrogen pipeline.
[0009] The purification delivery pipeline is equipped with a purification delivery valve assembly, the air delivery pipeline is equipped with a fractionation delivery valve assembly, and the waste nitrogen pipeline is equipped with a waste nitrogen pipeline assembly.
[0010] The system can selectively connect at least one molecular sieve purifier to the outlet end of the air compression cooling gas supply unit and to the feed end of the fractionation tower by switching on and off the purification delivery valve assembly, the fractionation delivery valve assembly, and the waste nitrogen pipeline assembly, and disconnect at least one molecular sieve purifier from the air compression cooling gas supply unit, and deliver waste nitrogen into the molecular sieve purifier via the waste nitrogen pipeline.
[0011] Furthermore, the purification delivery pipeline includes a main purification pipeline and multiple branch purification pipelines connected to the main purification pipeline. The main purification pipeline is connected to the outlet end of the gas supply unit, and each branch purification pipeline is also connected to the inlet end of the corresponding molecular sieve purifier.
[0012] The main purification pipeline is connected to the multiple branch purification pipelines via purification selection valves, so that the main purification pipeline can be selectively connected to at least one of the branch purification pipelines; or, each of the branch purification pipelines is provided with a purification on / off valve.
[0013] Furthermore, the air delivery pipeline includes a main fractionation pipeline and a plurality of branch fractionation pipelines connected to the main fractionation pipeline. The main fractionation pipeline is connected to the feed end of the fractionation tower, and each of the branch fractionation pipelines is also connected to the discharge end of the corresponding molecular sieve purifier.
[0014] The main fractionation pipe is connected to the multiple branch fractionation pipes via fractionation selection valves, so as to selectively connect the main fractionation pipe to at least one of the branch fractionation pipes; or, each of the branch fractionation pipes is provided with a fractionation on / off valve.
[0015] Furthermore, the waste nitrogen outlet pipe at the top of the sealed gas source is also connected to the waste nitrogen outlet end of the corresponding molecular sieve purifier;
[0016] The sealed gas source pipeline is selectively connected to multiple molecular sieve purifiers by a group of waste nitrogen selection valves.
[0017] Furthermore, the molecular sieve purifier is equipped with a nitrogen discharge valve and a pressure gauge at the nitrogen discharge end or on the nitrogen discharge pipeline.
[0018] Furthermore, the nitrogen discharge valve is a ball valve or a safety valve.
[0019] Furthermore, it also includes a molecular sieve activation unit, which is connected to the outlet nitrogen end of the molecular sieve purifier via an activation pipe to introduce activation gas into the molecular sieve purifier.
[0020] Furthermore, the molecular sieve purifier includes an outer shell and an inlet pipe. An outlet is provided on the outer shell, and the inlet pipe extends into the outer shell. A receiving cavity suitable for accommodating the molecular sieve is formed in the outer shell between the inlet pipe and the outlet.
[0021] Furthermore, the pore size of the molecular sieve gradually increases in the direction from the inlet pipe to the outlet.
[0022] The beneficial effects of this utility model through the above technical solution are as follows:
[0023] This utility model provides an air separation device. When the molecular sieve purifier of the air separation device in standby mode is stationary, it is connected to the fractionation tower of another air separation device in operation mode. Therefore, it can transport the polluted nitrogen from the fractionation tower of the other air separation device in operation mode to the molecular sieve purifier of the air separation device in standby mode as a protective gas. This makes the molecular sieve in the molecular sieve purifier less likely to adsorb water or carbon dioxide, thereby ensuring the activity of the molecular sieve in the molecular sieve purifier. Thus, when the molecular sieve purifier is started, it can be used directly without activation, thereby ensuring that the air separation device in standby mode can start up quickly and provide gas products rapidly.
[0024] Other features and advantages of this invention will be described in detail in the following detailed description section. Attached Figure Description
[0025] The accompanying drawings are provided to further illustrate the present invention and form part of the specification. They are used together with the following detailed description to explain the present invention, but do not constitute a limitation thereof. In the drawings:
[0026] Figure 1 This is a schematic diagram of the connection principle of the waste nitrogen sealing gas pipeline of the air separation equipment of this utility model;
[0027] Figure 2 This is a schematic diagram of the air separation device of this utility model;
[0028] Figure 3 This is a schematic diagram of the internal structure of the molecular sieve purifier in the air separation device of this utility model.
[0029] Explanation of reference numerals in the attached figures
[0030] 1. Air compression cooling purification assembly; 11. Molecular sieve purifier; 111. Outer shell; 112. Inlet pipe; 12. Air compression cooling gas supply unit; 2. Fractionating tower; 3. Molecular sieve activation unit; 4. Sealed gas source. Detailed Implementation
[0031] The specific embodiments of this utility model will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are only for illustration and explanation of this utility model, and the protection scope of this utility model is not limited to the specific embodiments described below.
[0032] The directional terms used below are based on the premise that the conveyor belt is used to move the packaging bags forward.
[0033] This utility model provides an air separation device, such as... Figures 1 to 3 As shown, it includes an air compression cooling purification component 1 and a fractionation tower 2. The air compression cooling purification component 1 may include an air compression cooling supply unit 12 (which may be an air compressor and an air cooling tower, which is the prior art) and a molecular sieve purification unit. The molecular sieve purification unit is located after the air compression cooling supply unit 12. After the air is compressed by the air compressor, it is cooled and liquefied by the air compression cooling supply unit 12 and then flows to the fractionation tower 2 for fractionation to obtain nitrogen. The nitrogen can be discharged from the outlet located at the upper part of the fractionation tower 2.
[0034] The molecular sieve purification unit is configured to include a molecular sieve purifier 11. The feed end of each molecular sieve purifier 11 is connected to the discharge end of the air compression cooling gas supply unit 12. The discharge end of each molecular sieve purifier 11 is connected to the feed end of the fractionation tower 2. Each molecular sieve purifier 11 is also connected to a sealed gas source 4 to deliver polluted nitrogen into the molecular sieve purifier 11 via the sealed gas source 4. The sealed gas source 4 includes the fractionation tower 2 of another air separation device in operation.
[0035] Based on the above technical solution, the air separation equipment of this application, when in standby mode, is connected to the sealed gas source 4 (i.e., the fractionation tower of the air separation equipment in another operating state). Therefore, it can transport the polluted nitrogen in the fractionation tower 4 of the air separation equipment in another operating state to the molecular sieve purifier 11 of the air separation equipment in standby mode as a protective gas. This makes it difficult for the molecular sieve in the molecular sieve purifier 11 of the air separation equipment in standby mode to adsorb water or carbon dioxide, thereby ensuring the activity of the molecular sieve in the molecular sieve purifier 11 of the air separation equipment in standby mode. Thus, when the air separation equipment in standby mode is started, the molecular sieve purifier 11 of the air separation equipment in this state can be used directly without activation, thereby enabling the air separation equipment in standby mode to start up quickly and provide gas products quickly.
[0036] Specifically, the molecular sieve purification unit can be configured to include at least two molecular sieve purifiers 11 connected in parallel. The air compression cooling supply unit 12 is connected to each molecular sieve purifier 11 via a purification delivery pipeline. The outlet of each molecular sieve purifier 11 is connected to the inlet of the fractionation tower 2 via an air delivery pipeline. The outlet of the sealing gas source 4 is connected to the molecular sieve purifier 11 via a waste nitrogen pipeline. A purification delivery valve assembly is provided on the purification delivery pipeline connection, a fractionation delivery valve assembly is provided on the air delivery pipeline, and a waste nitrogen pipeline assembly is provided on the waste nitrogen pipeline. This allows for the selective connection of at least one molecular sieve purifier 11 to the air compression cooling supply unit by switching on and off the purification delivery valve assembly, the fractionation delivery valve assembly, and the waste nitrogen pipeline assembly. Unit 12 is connected, and at least one molecular sieve purifier 11 is disconnected from the air compression cooling gas supply unit 12. The molecular sieve purifier 11, which is disconnected from the air compression cooling gas supply unit 12, is connected to the sealed gas source 4 via a waste nitrogen pipeline. This enables the supply of waste nitrogen from the sealed gas source 4 to the molecular sieve purifier 11, so that the waste nitrogen can be used as a protective gas for the molecular sieve in the molecular sieve purifier 11. This makes it less likely for the molecular sieve in the molecular sieve purifier 11 of the air separation equipment in standby mode to adsorb water and carbon dioxide and fail. This allows the air separation equipment in standby mode to be turned on and used immediately without activation, enabling the air separation equipment in standby mode to start up quickly and provide gas products quickly.
[0037] Specifically, the purification delivery pipeline can be configured to include a main purification pipeline and multiple branch purification pipelines connected to the main purification pipeline. The main purification pipeline is connected to the outlet end of the air compression cooling gas supply unit 12, and each branch purification pipeline is also connected to the inlet end of the corresponding molecular sieve purifier 11. The main purification pipeline and the multiple branch purification pipelines can be connected via a purification selection valve, so that the main purification pipeline can be selectively connected to at least one branch purification pipeline, thereby achieving selective connection between the air compression cooling gas supply unit 12 and the molecular sieve purifier 11. Alternatively, a purification on / off valve can be provided on each branch purification pipeline, so that the main purification pipeline can be connected to at least one branch purification pipeline by the on / off setting of the purification on / off valve, thereby achieving selective connection between the air compression cooling gas supply unit 12 and the molecular sieve purifier 11.
[0038] Similarly, the air delivery pipeline can be configured to include a main fractionation pipeline and multiple branch fractionation pipelines connected to the main fractionation pipeline. The main fractionation pipeline is connected to the feed end of the fractionation tower 2, and each branch fractionation pipeline is also connected to the discharge end of the corresponding molecular sieve purifier 11. The main fractionation pipeline and the multiple branch fractionation pipelines can be connected via a fractionation selection valve to selectively connect the main fractionation pipeline to at least one branch fractionation pipeline, thereby achieving selective connection between the feed end of the fractionation tower 2 and the molecular sieve purifier 11. Alternatively, each branch fractionation pipeline can be equipped with a fractionation on / off valve, so that the main fractionation pipeline can be connected to at least one branch fractionation pipeline by the on / off setting of the fractionation on / off valve, thereby achieving selective connection between the feed end of the fractionation tower 2 and the molecular sieve purifier 11.
[0039] Similarly, the waste nitrogen pipeline can be configured to include a main waste nitrogen pipeline and multiple branch waste nitrogen pipelines connected to the main waste nitrogen pipeline. The main waste nitrogen pipeline is connected to the waste nitrogen outlet pipeline at the top of the sealing gas source 4, and each branch waste nitrogen pipeline is also connected to the outlet regenerated waste nitrogen feed end of the corresponding molecular sieve purifier 11. The main waste nitrogen pipeline and the multiple branch waste nitrogen pipelines can be connected via a waste nitrogen selection valve, so that the main waste nitrogen pipeline can be selectively connected to at least one branch waste nitrogen pipeline, thereby achieving selective connection between the sealing gas source 4 and the molecular sieve purifier 11. Alternatively, each branch waste nitrogen pipeline can be equipped with a waste nitrogen on / off valve, so that the main waste nitrogen pipeline can be connected to at least one branch waste nitrogen pipeline by the on / off setting of the waste nitrogen on / off valve, thereby achieving selective connection between the sealing gas source 4 and the molecular sieve purifier 11.
[0040] Furthermore, a nitrogen discharge valve and a pressure gauge can be installed at the outlet nitrogen end or on the nitrogen pipeline of the molecular sieve purifier 11. The pressure gauge can be used to detect the internal pressure of the molecular sieve purifier 11, so that the internal pressure of the molecular sieve purifier 11 can be known by monitoring the pressure data on the pressure gauge, ensuring that the molecular sieve purifier 11 is within a safe working pressure range. The molecular sieve purifier 11 can be depressurized by selecting a suitable nitrogen discharge valve. For example, when the nitrogen discharge valve is a safety valve, the safety valve will automatically open to release pressure when the pressure inside the molecular sieve purifier 11 reaches a preset value. Or when the nitrogen discharge valve is a ball valve, the ball valve will open to release pressure when the pressure inside the molecular sieve purifier 11 reaches a preset value.
[0041] In addition, such as Figure 2 As shown, it also includes a molecular sieve activation unit 3. The sieve activation unit is connected to the feed end of the molecular sieve purifier 11 via an activation pipe to introduce activation gas into the molecular sieve purifier 11. The activation gas can be dry high-temperature waste nitrogen, which is existing technology and will not be described in detail here.
[0042] Specifically, the molecular sieve purifier 11 includes an outer shell 111 and an inlet pipe 112. The outer shell 111 has an outlet, and the inlet pipe 112 extends into the outer shell 111. The outer shell 111 forms a cavity suitable for accommodating the molecular sieve between the inlet pipe 112 and the outlet. A gas distributor is provided at one end of the inlet pipe 112 located inside the outer shell 111 so that the gas entering the molecular sieve purifier 11 can be in uniform contact with the molecular sieve, and the pore size of the molecular sieve gradually increases in the direction from the inlet to the outlet.
[0043] This is to fully utilize the molecular sieve and extend the single-use lifespan of the molecular sieve purifier 11.
[0044] The specific structure and usage of the air separation device of this utility model will be described below with reference to a preferred embodiment:
[0045] The air separation device of this utility model includes an air compression cooling purification component 1 and a fractionation tower 2 connected in sequence. The air compression cooling purification component 1 includes an air compression cooling supply unit 12 (which can be an air compressor and an air cooling tower, which is the prior art) and a molecular sieve purification unit. The molecular sieve purification unit can be configured to include two molecular sieve purifiers 11 connected in parallel. The air compression cooling supply unit 12 is connected to each molecular sieve purifier 11 via a purification delivery pipeline. The discharge end of each molecular sieve purifier 11 is connected to the inlet end of the fractionation tower 2 via an air delivery pipeline. The outlet of the sealed gas source 4 (i.e., the fractionation tower of another air separation device in operation) is connected to the molecular sieve purifier 11 via a waste nitrogen pipeline.
[0046] Specifically, the purification delivery pipeline includes a main purification pipeline and two branch purification pipelines connected to the main purification pipeline. The main purification pipeline is connected to the outlet end of the air compression cooling gas supply unit 12, and the two branch purification pipelines are also connected to the inlet end of the corresponding molecular sieve purifiers 11. A sealing gas pressure-holding valve, denoted as pressure-holding valve V1222, is provided at the connection point between each purified waste nitrogen pipeline and the corresponding molecular sieve purifier 11. The sealing gas source 4 (i.e., the fractionation tower of another air separation device in operation) is connected to the corresponding molecular sieve purifier 11 via the waste nitrogen pipeline. On / off valves, denoted as waste nitrogen on / off valves V1211 and V1212, are provided on the waste nitrogen pipeline. The waste nitrogen pipeline includes a main waste nitrogen pipeline and two branch waste nitrogen pipelines connected to the main waste nitrogen pipeline. The main waste nitrogen pipeline is connected to the outlet of the sealed gas source 4. The two branch waste nitrogen pipelines are also connected to the outlet regeneration waste nitrogen feed end of the corresponding molecular sieve purifier 11. A total waste nitrogen on / off valve, denoted as V201, is provided on the main waste nitrogen pipeline. A waste nitrogen on / off valve, denoted as waste nitrogen on / off valve V1221, is provided at the connection point of each branch waste nitrogen pipeline to the corresponding molecular sieve purifier 11. Molecular sieve activation unit 3 is connected to the main activation pipeline via V1217 and V1218. The main activation pipeline is connected to the two branch activation pipelines, which in turn connect to the corresponding molecular sieve purifier 11. Each branch activation pipeline is equipped with waste nitrogen on / off valves V1211 and V1212. A waste nitrogen discharge valve (denoted as V1223) and a pressure gauge (denoted as PI1221) are provided on the main sealed gas waste nitrogen pipeline connected to each molecular sieve purifier 11.
[0047] During normal use, activation on / off valves V1217 and V1218 are closed, and pressure-holding valve V1222, located on the same branch pipe as activation on / off valves V1217 and V1218, is open. This opens fractionation on / off valves V1211 and V1212 on the branch fractionation pipe connected to the molecular sieve purifier 11, and also opens the total nitrogen on / off valve V201 and the nitrogen on / off valve V1221 connected to the molecular sieve purifier 11. This protects the molecular sieve in the molecular sieve purifier 11 and ensures proper functioning of the system. When introducing waste nitrogen, the original pressure of 12 kPa and dew point of -90°C can be adjusted to 5 kPa through the total waste nitrogen on / off valve V201 and the waste nitrogen on / off valve V1221. This ensures that the molecular sieve in the molecular sieve purifier 11 is not affected by the outside air, and the setting position of the pressure holding valve V1222 can better maintain the pressure of the molecular sieve purifier 11, preventing the pipeline between the waste nitrogen on / off valve V1221 and the pressure holding valve V1222 from being too long, which would cause the pressure gauge PI1221 to measure inaccurately.
[0048] Before putting the standby air separation molecular sieve purifier into operation, the connection between the molecular sieve purifier 11 and the sealed gas source 4 needs to be disconnected. First, close the main waste nitrogen on / off valve V201 from the sealed gas source 4 to the standby air separation unit, then close the waste nitrogen on / off valve V1221. Open the waste nitrogen discharge valve V1223 on the branch activation pipeline connected to the molecular sieve purifier 11. Wait until the pressure gauge PI1221 on the sealed gas waste nitrogen pipeline connected to the molecular sieve purifier 11 reads 0, then close the pressure holding valve V1222 on the pipeline connected to the molecular sieve purifier 11, and close the fractionation on / off valves V1211 and V1212 that supply waste nitrogen to the molecular sieve purifier 11. Keep the waste nitrogen discharge valve V1223 open to ensure that the standby air separation molecular sieve purifier 11 is completely disconnected from the sealed gas source 4.
[0049] The preferred embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the present invention is not limited to the specific details of the above embodiments. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solution of the present invention, and these simple modifications all fall within the protection scope of the present invention.
[0050] It should also be noted that the various specific technical features described in the above embodiments can be combined in any suitable manner without contradiction. To avoid unnecessary repetition, this utility model will not describe the various possible combinations separately.
[0051] Furthermore, various different embodiments of this utility model can be combined in any way, as long as they do not violate the spirit of this utility model, they should also be regarded as the content disclosed by this utility model.
Claims
1. An air separation plant comprising an air compression cooling purification assembly (1) and a fractionation column (2), the air compression cooling purification assembly (1) comprising an air compression cooling feed air unit (12) and a molecular sieve purification unit, air being purified by the air compression cooling purification assembly (1) and then being fed to the fractionation column (2), characterized in that, The molecular sieve purification unit comprises molecular sieve purifiers (11), the feed end of each molecular sieve purifier (11) is connected with the discharge end of the air compression cooling gas supply unit (12), the discharge end of each molecular sieve purifier (11) is connected with the feed end of the fractionating tower (2), and each molecular sieve purifier (11) is further connected with a seal gas source (4) to transport dirty nitrogen into the molecular sieve purifier (11) through the seal gas source (4), and the seal gas source (4) comprises a fractionating tower of another set of air separation equipment in a running state.
2. The air separation plant of claim 1, wherein, The molecular sieve purification unit comprises at least two parallel molecular sieve purifiers (11), the air compression cooling gas supply unit (12) is connected with each molecular sieve purifier (11) through a purification conveying pipeline, the discharge end of each molecular sieve purifier (11) is connected with the feed end of the fractionating tower (2) through an air conveying pipeline, and the air outlet of the seal gas source (4) is communicated with the molecular sieve purifier (11) through a dirty nitrogen pipeline. The purification conveying pipeline is provided with a purification conveying valve assembly, the air conveying pipeline is provided with a fractionating conveying valve assembly, and the dirty nitrogen pipeline is provided with a dirty nitrogen pipeline assembly. At least one molecular sieve purifier (11) is selectively communicated with the discharge end of the air compression cooling gas supply unit (12) and the feed end of the fractionating tower (2) through the opening and closing of the purification conveying valve assembly, the fractionating conveying valve assembly and the dirty nitrogen pipeline assembly, and at least one molecular sieve purifier (11) is disconnected from the air compression cooling gas supply unit (12) and dirty nitrogen is transported into the molecular sieve purifier (11) through the dirty nitrogen pipeline.
3. The air separation plant of claim 2, wherein, The purification conveying pipeline comprises a main purification pipeline and a plurality of branch purification pipelines communicated with the main purification pipeline, the main purification pipeline is connected with the discharge end of the air compression cooling gas supply unit (12), and each branch purification pipeline is further connected with the feed end of the corresponding molecular sieve purifier (11). The main purification pipeline and the plurality of branch purification pipelines are connected through a purification selection valve to selectively communicate the main purification pipeline with at least one branch purification pipeline, or each branch purification pipeline is provided with a purification on-off valve.
4. The air separation plant of claim 2, wherein, The air conveying pipeline comprises a main fractionating pipeline and a plurality of branch fractionating pipelines communicated with the main fractionating pipeline, the main fractionating pipeline is connected with the feed end of the fractionating tower (2), and each branch fractionating pipeline is further connected with the discharge end of the corresponding molecular sieve purifier (11). The main fractionating pipeline and the plurality of branch fractionating pipelines are connected through a fractionating selection valve to selectively communicate the main fractionating pipeline with at least one branch fractionating pipeline, or each branch fractionating pipeline is provided with a fractionating on-off valve.
5. The air separation plant of claim 2, wherein, The dirty nitrogen air outlet pipeline of the upper part of the seal gas source (4) is further connected with the outlet dirty nitrogen end of the corresponding molecular sieve purifier (11). The seal gas source (4) pipeline and the plurality of molecular sieve purifiers (11) are selectively connected by a dirty nitrogen selection valve group.
6. The air separation plant of claim 5, wherein, A dirty nitrogen discharge valve and a pressure gauge are arranged at the outlet dirty nitrogen end of the molecular sieve purifier (11) or on the dirty nitrogen pipeline.
7. The air separation plant of claim 6, wherein, The dirty nitrogen discharge valve is a ball valve or a safety valve.
8. The air separation plant of any one of claims 1 to 7, characterized by, A molecular sieve activation unit (3) is further included, which is connected with the outlet dirty nitrogen end of the molecular sieve purifier (11) via an activation pipeline to introduce activation gas into the molecular sieve purifier (11).
9. The air separation plant of claim 8, wherein, The molecular sieve purifier (11) comprises an outer housing (111) and an inlet pipeline (112), the outer housing (111) is provided with a gas outlet, and the inlet pipeline (112) extends into the outer housing (111), and a containing cavity adapted to contain molecular sieve is formed between the inlet pipeline (112) and the gas outlet in the outer housing (111).
10. The air separation plant of claim 9, wherein, The porosity of the molecular sieve gradually increases in the direction from the inlet pipeline (112) to the gas outlet.