Rectification device for oxygen-enriched nitrogen

Abstract

The utility model relates to a rectification device for oxygen-enriched nitrogen, which comprises a main heat exchanger and a rectification tower, a circulating air delivery pipe is arranged on the main heat exchanger, and a compressor, a compression end of a turbo expander, a first heat exchanger, a first air delivery branch pipe and an expansion end of the turbo expander are arranged on the circulating air delivery pipe. Cooling air conveying pipes are arranged at the expansion end of the turbo expander, the main heat exchanger and the inlet end of the compressor, a raw material air conveying header pipe is arranged on the rectifying tower and the main heat exchanger, and the circulating air conveying pipe is communicated with the raw material air conveying header pipe through a second air conveying branch pipe. And an oxygen-enriched nitrogen conveying header pipe is arranged at the top of the cold source channel of the tower top condenser and on the main heat exchanger. The cold source airflow obtaining time of the main heat exchanger is shortened. The utility model has the advantages of convenient use and wide market prospect.

Description

Technical Field

[0001] This utility model relates to the field of oxygen-enriched nitrogen distillation equipment, specifically to an oxygen-enriched nitrogen distillation apparatus. Background Technology

[0002] In blast furnace ironmaking, the optimal combination of pulverized coal injection (PFC) technology and oxygen enrichment rate has become a significant technical challenge. PFC involves injecting pulverized coal into the blast furnace to participate in the reduction reaction along with iron ore and air, providing fuel and heat while influencing the balance of carbon, oxygen, and other elements. Conversely, the oxygen enrichment rate regulates the oxygen supply within the blast furnace, significantly impacting the reduction reaction rate and furnace temperature distribution. The interaction between PFC technology and oxygen enrichment rate requires in-depth research, including aspects such as combustion kinetics, material balance, thermodynamic parameters, and reaction kinetics. Blast furnace ironmaking not only ensures sufficient reduction reaction to minimize the conversion of iron ore to iron but also considers the impact of carbon emissions and other waste gas emissions. Therefore, in-depth research is needed on the optimal combination of PFC injection rate and oxygen enrichment rate to achieve the best performance of the blast furnace ironmaking process.

[0003] Meanwhile, steel production enterprises also have a demand for nitrogen, specifically for low-pressure and medium-pressure nitrogen. Low-pressure nitrogen has a pressure range of 0.4 MPa to 0.9 MPa. The main users of low-pressure nitrogen are generally: bulk material chutes, nitrogen sealing in bulk material feeding systems, air sources for pneumatic valves, instrument air sources, air sources for purging pipelines, and air sources for blowdown pipelines. Medium-pressure nitrogen ranges from 1.0 MPa to 1.6 MPa. High-pressure nitrogen is mainly used for converter top and bottom blowing and hot metal desulfurization. Considering the above demands, the gas produced by the single-tower nitrogen generation process in air separation can fully meet the needs of steel production enterprises for both oxygen-enriched gas and nitrogen. This is because the waste nitrogen produced by single-tower nitrogen generation has a high oxygen content, fully meeting the oxygen content requirements of blast furnace processes for oxygen enrichment, and the nitrogen product produced by single-tower nitrogen generation can be provided to both low-pressure and high-pressure nitrogen users of steel production enterprises.

[0004] Although single-tower nitrogen production technology is quite mature, it is limited by conventional processes and generates a large amount of waste gas during start-up. This primarily manifests as the inability to produce qualified nitrogen products and waste nitrogen gas with adequate oxygen content. Existing technologies utilize spraying liquid nitrogen into the distillation column to achieve the required distillation temperatures and top parameters. While this can shorten the start-up time, achieving the start-up requirements for single-tower nitrogen production requires more than just the distillation column meeting the necessary parameters. The main heat exchanger in the distillation system must also effectively exchange heat between the heat source and cold source gas streams to meet process specifications. During start-up, insufficient cold source gas makes it difficult for the main heat exchanger to reach the required parameters. Even if spraying liquid nitrogen allows the downstream distillation column to meet the required parameters, the lack of a suitable temperature for the distillation feed gas means the single-tower nitrogen production process cannot achieve its start-up goals. Therefore, there is room for improvement in the existing technology, which aims to reduce the dependence of the main heat exchanger on the low-temperature gas emitted from the distillation column, so that the main heat exchanger can quickly obtain cold source gas and then deliver distillation feed gas at a suitable temperature to the distillation column, shorten the start-up phase of the single-tower nitrogen production process, reduce the time consumed by the enterprise during the start-up phase, and thus reduce the operating cost. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides an oxygen-enriched nitrogen distillation device that can shorten the time for the main heat exchanger to obtain cold source gas flow, thereby overcoming the deficiencies in existing technologies.

[0006] The technical solution adopted by this utility model is as follows: an oxygen-enriched nitrogen distillation device, including a main heat exchanger and a distillation column. The main heat exchanger is provided with a circulating air delivery pipe. Along the circulating air delivery pipe from its inlet end to its outlet end, there are sequentially arranged the outlet end of a compressor, the compression end of a turbine expander, the heat source channel of a first heat exchanger, the inlet end of a first air delivery branch pipe, and the expansion end of the turbine expander. Cooling air delivery pipes are provided on the expansion end of the turbine expander, the inlet end of the main heat exchanger, and the compressor. A raw material air delivery main pipe is provided on the distillation column and the main heat exchanger. The circulating air delivery pipe between the compressor and the compression end of the turbine expander and the raw material air delivery main pipe are connected through a second air delivery branch pipe. A column top condenser is provided at the top of the distillation column. The heat source channel of the column top and the column top condenser are connected. The cold source channel of the column bottom and the column top condenser are connected. An oxygen-enriched nitrogen delivery main pipe is provided at the top of the cold source channel of the column top condenser and on the main heat exchanger.

[0007] Preferably, the distillation column is provided with a first packing layer, a second packing layer, and a nozzle in sequence from bottom to top. The distillation column below the second packing layer is connected to the outlet end of the first air delivery branch pipe. The distillation column between the first and second packing layers is connected to the outlet end of the raw material air delivery main pipe. The distillation column above the nozzle is connected to the inlet end of the heat source channel of the top condenser through a first nitrogen delivery pipe. The nozzle is connected to the outlet end of the heat source channel of the top condenser through a liquid nitrogen reflux pipe.

[0008] Preferably, a second nitrogen supply pipe is provided on the first nitrogen supply pipe and the main heat exchanger. A first regulating valve is provided on both the first nitrogen supply pipe and the second nitrogen supply pipe between the second nitrogen supply pipe and the top condenser. A liquid nitrogen supply main pipe is provided at the outlet end of the heat source channel of the top condenser. The liquid nitrogen supply main pipe is connected to the liquid nitrogen return pipe. A second regulating valve is provided on both the liquid nitrogen supply main pipe and the liquid nitrogen return pipe on the side of the liquid nitrogen return pipe away from the top condenser.

[0009] Preferably, the cold source channels of the bottom and top condensers of the distillation column are connected by an oxygen-enriched liquid air delivery pipe, a third regulating valve is installed on the oxygen-enriched liquid air delivery pipe, and an undercooler is installed on the oxygen-enriched nitrogen gas delivery main pipe between the top condenser and the main heat exchanger and the oxygen-enriched liquid air delivery pipe.

[0010] Preferably, liquid level sensors are installed on the cold source channels of the bottom and top condensers of the distillation column.

[0011] Preferably, a fourth regulating valve is installed on the oxygen-enriched nitrogen gas delivery main pipe on the side of the main heat exchanger away from the distillation column. The inlet end of a first oxygen-enriched nitrogen gas delivery branch pipe is installed on the oxygen-enriched nitrogen gas delivery main pipe between the fourth regulating valve and the main heat exchanger. A fifth regulating valve is installed on the first oxygen-enriched nitrogen gas delivery branch pipe. A heat source channel for a second heat exchanger is installed on the circulating air delivery pipe between the compression end of the turbine expander and the heat source channel of the first heat exchanger. The inlet end of the cold source channel of the second heat exchanger is connected to the outlet end of the first oxygen-enriched nitrogen gas delivery branch pipe. A second oxygen-enriched nitrogen gas delivery branch pipe is installed on the outlet end of the cold source channel of the second heat exchanger.

[0012] Preferably, the second oxygen-enriched nitrogen gas delivery branch pipe is provided with a first temperature sensor, an electric heater, and a second temperature sensor sequentially along the direction from near the second heat exchanger to away from the second heat exchanger.

[0013] The beneficial effects of this utility model are as follows: First, this utility model diverts a portion of the purified compressed air received from the raw material air delivery main pipe to the circulating air delivery pipe. After being compressed again at the compression end of the turbine expander, it passes through the heat source channel of the first heat exchanger and the circulating water continuously supplied to the cold source channel of the first heat exchanger for heat exchange. It then enters the second heat source channel of the main heat exchanger and is discharged from the medium temperature zone of the main heat exchanger. After expansion and cooling at the expansion end of the turbine expander, it is sent back to the first cold source channel of the main heat exchanger and the heat source medium continuously supplied to the main heat exchanger. Finally, it is re-pressurized by the compressor and merged with the compressed air continuously supplied to the circulating air delivery pipe to form a refrigeration cycle. This shortens the time for the main heat exchanger to obtain a cold source, thereby enabling the main heat exchanger to enter the operating state as soon as possible and shortening the start-up time.

[0014] Secondly, a fourth regulating valve is installed on the oxygen-enriched nitrogen gas delivery main pipe on the side of the main heat exchanger away from the distillation column, as described in this utility model. The inlet end of a first oxygen-enriched nitrogen gas delivery branch pipe is installed on the oxygen-enriched nitrogen gas delivery main pipe between the fourth regulating valve and the main heat exchanger. A fifth regulating valve is installed on the first oxygen-enriched nitrogen gas delivery branch pipe. A second heat source channel for the second heat exchanger is installed on the circulating air delivery pipe between the compression end of the turbine expander and the heat source channel of the first heat exchanger. The inlet end of the cold source channel of the second heat exchanger is connected to the outlet end of the first oxygen-enriched nitrogen gas delivery branch pipe, and a second oxygen-enriched nitrogen gas delivery branch pipe is installed on the outlet end of the cold source channel of the second heat exchanger. After the oxygen-enriched nitrogen gas delivered to the cold source channel of the second heat exchanger via the first oxygen-enriched nitrogen gas delivery branch pipe and the medium continuously delivered to the heat source channel of the second heat exchanger undergo countercurrent heat exchange, a preset oxygen-enriched nitrogen gas is formed. This reduces the heating amplitude of the downstream electric heater for heating the oxygen-enriched nitrogen gas, thus achieving energy savings.

[0015] Furthermore, the second oxygen-enriched nitrogen gas delivery branch pipe of this utility model is provided with a first temperature sensor, an electric heater, and a second temperature sensor in sequence along the direction from near the second heat exchanger to far away from the second heat exchanger; both the first temperature sensor and the second temperature sensor facilitate the feedback of temperature parameters.

[0016] This utility model has a simple structure, is easy to operate, and has a clever design, which greatly improves work efficiency and has good social and economic benefits. It is a product that is easy to promote and use. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the structure of this utility model. Detailed Implementation

[0018] like Figure 1As shown, an oxygen-enriched nitrogen distillation apparatus includes a main heat exchanger 1 and a distillation column 2. A circulating air supply pipe 3 is installed on the main heat exchanger 1. Along the circulating air supply pipe 3 from its inlet to its outlet, the following are sequentially arranged: the outlet end of a compressor 4, the compression end of a turbine expander 5, the heat source channel of a first heat exchanger 6, the inlet end of a first air supply branch pipe 7, and the expansion end of the turbine expander 5. Cooling air supply lines are installed on the expansion end of the turbine expander 5, the inlet end of the main heat exchanger 1, and the inlet end of the compressor 4. The feed pipe 8, the distillation column 2 and the main heat exchanger 1 are provided with a feed air main pipe 9. The circulating air supply pipe 3 between the compressor 4 and the compression end of the turbine expander 5 and the feed air main pipe 9 are connected through a second air supply branch pipe 10. The top of the distillation column 2 is provided with a column top condenser 11. The top of the distillation column 2 and the heat source channel of the column top condenser 11 are connected. The bottom of the distillation column 2 and the cold source channel of the column top condenser 11 are connected. The top of the cold source channel of the column top condenser 11 and the main heat exchanger 1 are provided with an oxygen-enriched nitrogen gas supply main pipe 12.

[0019] The distillation column 2 is provided with a first packing layer 13, a second packing layer 14 and a nozzle 15 arranged sequentially from bottom to top. The distillation column 2 below the second packing layer 14 is connected to the outlet end of the first air delivery branch pipe 7. The distillation column 2 between the first packing layer 13 and the second packing layer 14 is connected to the outlet end of the raw material air delivery main pipe 9. The distillation column 2 above the nozzle 15 is connected to the inlet end of the heat source channel of the top condenser 11 through the first nitrogen delivery pipe 16. The nozzle 15 is connected to the outlet end of the heat source channel of the top condenser 11 through the liquid nitrogen reflux pipe 17. A second nitrogen supply pipe 18 is provided on the first nitrogen supply pipe 16 and the main heat exchanger 1. A first regulating valve 19 is provided on both the first nitrogen supply pipe 16 and the second nitrogen supply pipe 18 between the second nitrogen supply pipe 18 and the top condenser 11. A liquid nitrogen supply main pipe 20 is provided at the outlet end of the heat source channel of the top condenser 11. The liquid nitrogen supply main pipe 20 is connected to the liquid nitrogen return pipe 17. A second regulating valve 21 is provided on both the liquid nitrogen supply main pipe 20 and the liquid nitrogen return pipe 17 on the side of the liquid nitrogen return pipe 17 away from the top condenser 11.

[0020] The cold source channels of the bottom and top condensers 11 of the distillation column 2 are connected by an oxygen-enriched liquid air delivery pipe 22. A third regulating valve 23 is installed on the oxygen-enriched liquid air delivery pipe 22. An oxygen-enriched nitrogen gas delivery main pipe 12 between the top condenser 11 and the main heat exchanger 1, and an oxygen-enriched liquid air delivery pipe 22, are both equipped with subcoolers 24. This facilitates heat exchange between the oxygen-enriched nitrogen gas received by the oxygen-enriched nitrogen gas delivery main pipe 12 and the oxygen-enriched liquid air delivered by the oxygen-enriched liquid air delivery pipe 22 within the subcooler 24, thereby reducing the temperature of the oxygen-enriched liquid air. Liquid level sensors 25 are installed on both the bottom and top condenser 11 of the distillation column 2; these sensors facilitate feedback of liquid level parameters.

[0021] A fourth regulating valve 26 is installed on the oxygen-enriched nitrogen gas delivery main pipe 12 on the side of the main heat exchanger 1 away from the distillation column 2. The inlet end of the first oxygen-enriched nitrogen gas delivery branch pipe 27 is installed on the oxygen-enriched nitrogen gas delivery main pipe 12 between the fourth regulating valve 26 and the main heat exchanger 1. A fifth regulating valve 28 is installed on the first oxygen-enriched nitrogen gas delivery branch pipe 27. The heat source channel of the second heat exchanger 29 is installed on the circulating air delivery pipe 3 between the compression end of the turbine expander 5 and the heat source channel of the first heat exchanger 6. The inlet end of the cold source channel of the second heat exchanger 29 is connected to the outlet end of the first oxygen-enriched nitrogen gas delivery branch pipe 27. A second oxygen-enriched nitrogen gas delivery branch pipe 30 is installed on the outlet end of the cold source channel of the second heat exchanger 29. Furthermore, the second oxygen-enriched nitrogen gas delivery branch pipe 30 is provided with a first temperature sensor 31, an electric heater 32, and a second temperature sensor 33 in sequence along the direction from near the second heat exchanger 29 to away from the second heat exchanger 29. The installation of the first temperature sensor 31 and the second temperature sensor 33 is to facilitate the feedback of temperature parameters.

[0022] The usage instructions for this product are as follows: Figure 1 As shown, the specific steps include:

[0023] S1. The pre-cooled and purified compressed air from the upstream is transported to the raw material air transport main pipe 9 and then divided into two parts, namely the first part of compressed air and the second part of compressed air. The first part of compressed air continues to travel along the raw material air transport main pipe 9, exchanges heat with the first heat source channel of the main heat exchanger 1 and the cold source medium transported to the main heat exchanger 1, and is then transported to the distillation column 2 between the first packing layer 13 and the second packing layer 14 as the first distillation raw material to participate in the distillation in the distillation column 2.

[0024] The second part of compressed air is transported to the circulating air supply pipe 3 via the second air supply branch pipe 10. After being pressurized for the first time at the compression end of the turbine expander 5, it is transported to the heat source channel of the first heat exchanger 6 via the heat source channel of the second heat exchanger 29 and the circulating water continuously supplied to the cold source channel of the first heat exchanger 6 for counter-current heat exchange. Then it is transported to the second heat source channel of the main heat exchanger 1 and the cold source medium continuously supplied to the main heat exchanger 1 for heat exchange, and is divided into two parts again, namely the third part of compressed air and the fourth part of compressed air.

[0025] The third part of the compressed air is discharged from the medium temperature zone of the main heat exchanger 1 and then sent to the expansion end of the turbine expander 5 for expansion and cooling. After that, it is sent to the cooling air delivery pipe 8, where it exchanges heat with the first cold source channel of the main heat exchanger 1 and the heat source medium continuously supplied to the main heat exchanger 1. After that, it is discharged from the high temperature zone of the main heat exchanger 1 and continues to be sent along the cooling air delivery pipe 8 to the inlet end of the compressor 4 for a second compression. After the second compression, the third part of the compressed air and the second part of the compressed air continuously supplied through the second air delivery branch pipe 10 are combined to form the second part of the compressed air and form a refrigeration cycle.

[0026] The fourth part of compressed air is discharged from the low-temperature end of the main heat exchanger 1 and transported through the first air delivery branch pipe 7 to the distillation column 2 below the first packing layer 13 as the second distillation feedstock to participate in the distillation in the distillation column 2.

[0027] S2. The second distillation feedstock enters the distillation column 2 and continues to rise to form a first upward airflow. During the upward movement of the first upward airflow along the first packing layer 13 toward the second packing layer 14, it exchanges heat with the reflux condensate transported from the second packing layer 14 in a countercurrent manner. The nitrogen component in the reflux condensate is evaporated and merged into the first upward airflow and rises together. The oxygen component in the first upward airflow is liquefied and merged into the reflux condensate and flows down with the reflux condensate to the bottom of the distillation column 2.

[0028] The first rising gas flow merges with the first distillation feedstock through the first packing layer 13 to form a second rising gas flow, which is then conveyed to the second packing layer 14 and continues to rise along the inner cavity of the distillation column 2. During this process, it exchanges heat with the reflux condensate conveyed from the nozzle 15 to the second packing layer 14 in a countercurrent manner. The nitrogen component in the reflux condensate is evaporated and merged into the second rising gas flow, which rises together. The oxygen component in the second rising gas flow is liquefied and merged into the reflux condensate, which then flows down to the first packing layer 13 along with the reflux condensate. Finally, a nitrogen-rich zone is formed in the distillation column 2, and an oxygen-rich liquid air-rich zone is formed at the bottom of the distillation column 2.

[0029] S3. The oxygen-enriched liquid air enrichment zone is connected to the cold source channel of the tower top condenser 11 via the oxygen-enriched liquid air delivery pipe 22. During this process, it passes through the heat source channel of the cooler 24 and exchanges heat with the cold source continuously supplied to the subcooler 24. The nitrogen enrichment zone delivers pressurized nitrogen outward. The pressurized nitrogen is divided into two parts, namely the first part of pressurized nitrogen and the second part of pressurized nitrogen. The first part of pressurized nitrogen is delivered to the second nitrogen delivery pipe 18, exchanges heat with the second heat source channel of the main heat exchanger 1 and the cold source medium continuously supplied to the main heat exchanger 1, and then is delivered to the user of the finished nitrogen via the second nitrogen delivery pipe 18.

[0030] The second portion of pressurized nitrogen is transported through the first nitrogen transport pipe 16 to the heat source channel and cold source channel of the top condenser 11 of the column for heat exchange. After liquefaction, it forms liquid nitrogen and is transported to the liquid nitrogen transport main pipe 20. The liquid nitrogen entering the liquid nitrogen transport main pipe 20 is divided into two parts, namely the first part of liquid nitrogen and the second part of liquid nitrogen. The first part of liquid nitrogen is transported to the second packing layer 14 through the liquid nitrogen reflux pipe 17 and the nozzle 15 as the reflux condensate of the distillation column 2. The second part of liquid nitrogen is transported to the liquid nitrogen storage device through the outlet end of the liquid nitrogen transport main pipe 20 as finished liquid nitrogen for storage.

[0031] S4. After heat exchange between the oxygen-enriched liquid air enrichment zone of the cold source channel of the tower top condenser 11 and the medium continuously supplied to the heat source channel of the tower top condenser 11, oxygen-enriched nitrogen gas is formed and transported to the oxygen-enriched nitrogen gas delivery main pipe 12. It is first transported to the cold source channel of the subcooler 24 and the medium continuously supplied to the heat source channel of the subcooler 24 for heat exchange, and then transported to the second cold source channel of the main heat exchanger 1 and the heat source medium continuously supplied to the main heat exchanger 1 for heat exchange. After heat exchange, it continues to travel along the oxygen-enriched nitrogen gas delivery main pipe 12 and is delivered to the user of oxygen-enriched nitrogen gas through the outlet end of the oxygen-enriched nitrogen gas delivery main pipe 12.

[0032] When the upstream purification system needs to perform desorption, the oxygen-enriched nitrogen gas after heat exchange with the heat source medium continuously supplied to the main heat exchanger 1 through the second cold source channel of the main heat exchanger 1 in step S4 is divided into two parts: a first part of oxygen-enriched nitrogen gas and a second part of oxygen-enriched nitrogen gas. The first part of oxygen-enriched nitrogen gas continues to be supplied to the user of oxygen-enriched nitrogen gas through the outlet end of the oxygen-enriched nitrogen gas delivery main pipe 12. The second part of oxygen-enriched nitrogen gas is supplied to the cold source channel of the second heat exchanger 29 through the first oxygen-enriched nitrogen gas delivery branch pipe 27 and undergoes countercurrent heat exchange with the medium continuously supplied to the heat source channel of the second heat exchanger 29. After being discharged from the cold source channel of the second heat exchanger 29, it enters the second oxygen-enriched nitrogen gas delivery branch pipe 30. It first undergoes the first temperature feedback through the first temperature sensor 31, then further heating through the electric heater 32, and finally a second temperature feedback through the second temperature sensor 33 before being supplied to the purification system as high-temperature desorption gas.

[0033] This embodiment enables the product to divert a portion of the purified compressed air received from the raw material air delivery main pipe 9 into the circulating air delivery pipe 3, where it is recompressed at the compression end of the turbine expander 5. The compressed air then passes through the heat source channel of the first heat exchanger 6 and the circulating water continuously supplied to the cold source channel of the first heat exchanger 6 for heat exchange before entering the second heat source channel of the main heat exchanger 1. From there, it exits the medium-temperature zone of the main heat exchanger 1 and enters the expansion end of the turbine expander 5 for expansion and cooling before being returned to the first cold source channel of the main heat exchanger 1 and the continuously supplied heat source medium. Finally, it is recompressed by the compressor 4 and merged with the compressed air continuously supplied to the circulating air delivery pipe 3 to form a refrigeration cycle. This shortens the time it takes for the main heat exchanger 1 to obtain a cold source, allowing it to enter the operating state more quickly and thus reducing the start-up time.

[0034] The embodiments described above are merely preferred embodiments of this utility model and are not intended to limit the scope of implementation of this utility model. Therefore, all equivalent changes or modifications made to the structure, features and principles described in the patent claims of this utility model should be included within the scope of the patent application of this utility model.

Claims

1. An oxygen-enriched nitrogen distillation apparatus, comprising a main heat exchanger (1) and a distillation column (2), characterized in that: The main heat exchanger (1) is provided with a circulating air supply pipe (3). Along the inlet end of the circulating air supply pipe (3) to the outlet end of the circulating air supply pipe (3), the outlet end of the compressor (4), the compression end of the turbine expander (5), the heat source channel of the first heat exchanger (6), the inlet end of the first air supply branch pipe (7), and the expansion end of the turbine expander (5) are arranged in sequence. Cooling air supply pipes (8) are arranged on the expansion end of the turbine expander (5), the inlet end of the main heat exchanger (1), and the compressor (4). The distillation column (2) and the main heat exchanger (6) are arranged in sequence. The column (2) is equipped with a raw material air supply main pipe (9). The circulating air supply pipe (3) between the compressor (4) and the compressor end of the turbine expander (5) and the raw material air supply main pipe (9) are connected through a second air supply branch pipe (10). The top of the distillation column (2) is equipped with a column top condenser (11). The top of the distillation column (2) and the heat source channel of the column top condenser (11) are connected. The bottom of the distillation column (2) and the cold source channel of the column top condenser (11) are connected. The top of the cold source channel of the column top condenser (11) and the main heat exchanger (1) are equipped with an oxygen-enriched nitrogen supply main pipe (12).

2. The oxygen-enriched nitrogen distillation apparatus according to claim 1, characterized in that: The distillation column (2) is provided with a first packing layer (13), a second packing layer (14) and a nozzle (15) from bottom to top. The distillation column (2) below the second packing layer (14) is connected to the outlet end of the first air delivery branch pipe (7). The distillation column (2) between the first packing layer (13) and the second packing layer (14) is connected to the outlet end of the raw material air delivery main pipe (9). The distillation column (2) above the nozzle (15) and the inlet end of the heat source channel of the top condenser (11) are connected through the first nitrogen delivery pipe (16). The nozzle (15) and the outlet end of the heat source channel of the top condenser (11) are connected through the liquid nitrogen reflux pipe (17).

3. The oxygen-enriched nitrogen distillation apparatus according to claim 2, characterized in that: A second nitrogen delivery pipe (18) is provided on the first nitrogen delivery pipe (16) and the main heat exchanger (1). A first regulating valve (19) is provided on both the first nitrogen delivery pipe (16) and the second nitrogen delivery pipe (18) between the second nitrogen delivery pipe (18) and the top condenser (11). A liquid nitrogen delivery main pipe (20) is provided at the outlet end of the heat source channel of the top condenser (11). The liquid nitrogen delivery main pipe (20) and the liquid nitrogen return pipe (17) are connected. A second regulating valve (21) is provided on both the liquid nitrogen delivery main pipe (20) and the liquid nitrogen return pipe (17) on the side of the liquid nitrogen return pipe (17) away from the top condenser (11).

4. The oxygen-enriched nitrogen distillation apparatus according to claim 1, characterized in that: The cold source channels of the bottom and top condensers (11) of the distillation column (2) are connected by an oxygen-enriched liquid air delivery pipe (22). A third regulating valve (23) is installed on the oxygen-enriched liquid air delivery pipe (22). An oxygen-enriched nitrogen gas delivery main pipe (12) between the top condenser (11) and the main heat exchanger (1) and the oxygen-enriched liquid air delivery pipe (22) are provided with an undercooler (24).

5. The oxygen-enriched nitrogen distillation apparatus according to claim 4, characterized in that: Liquid level sensors (25) are respectively installed on the cold source channels of the bottom and top condensers (11) of the distillation column (2).

6. The oxygen-enriched nitrogen distillation apparatus according to claim 1, characterized in that: A fourth regulating valve (26) is provided on the oxygen-enriched nitrogen gas delivery main pipe (12) on the side of the main heat exchanger (1) away from the distillation column (2). The inlet end of the first oxygen-enriched nitrogen gas delivery branch pipe (27) is provided on the oxygen-enriched nitrogen gas delivery main pipe (12) between the fourth regulating valve (26) and the main heat exchanger (1). A fifth regulating valve (28) is provided on the first oxygen-enriched nitrogen gas delivery branch pipe (27). The heat source channel of the second heat exchanger (29) is provided on the circulating air delivery pipe (3) between the compression end of the turbine expander (5) and the heat source channel of the first heat exchanger (6). The inlet end of the cold source channel of the second heat exchanger (29) is connected to the outlet end of the first oxygen-enriched nitrogen gas delivery branch pipe (27). A second oxygen-enriched nitrogen gas delivery branch pipe (30) is provided on the outlet end of the cold source channel of the second heat exchanger (29).

7. The oxygen-enriched nitrogen distillation apparatus according to claim 6, characterized in that: The second oxygen-enriched nitrogen gas delivery branch pipe (30) is provided with a first temperature sensor (31), an electric heater (32), and a second temperature sensor (33) in sequence along the direction from near the second heat exchanger (29) to away from the second heat exchanger (29).

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